Epoxy resin composition

Abstract

[Problem] To provide an epoxy resin composition which contains an isocyanuric acid type epoxy compound and a liquid epoxy compound and which enables suppression of precipitation during storage and also has excellent flowability. [Solution] An epoxy resin composition comprising a liquid epoxy compound D and a reaction product C of an epoxy compound A represented by formula [1] and a levopimaric acid derivative B. [1] (In the formula, R1 to R3 each independently represent a hydrogen atom or a methyl group and L1 to L3 each independently represent a C1-10 alkylene group.)

Description

Epoxy resin composition

[0001] The present invention relates to an epoxy resin composition, and more particularly to an epoxy resin composition in which precipitation of an epoxy compound contained in the resin composition is inhibited during storage.

[0002] Epoxy compounds have traditionally been used as industrial materials in a wide range of fields, such as adhesives, paints, and electronic materials, because the cured products thereof have excellent heat resistance, chemical resistance, high electrical insulation properties, and high adhesiveness.

[0003] Triglycidyl isocyanurate (trade name TEPIC (registered trademark)), an isocyanuric acid-type epoxy compound, has an isocyanuric acid skeleton as the mother nucleus and three epoxy groups per molecule, making it highly reactive, and the resulting cured product has a high crosslink density and a high glass transition temperature. Furthermore, because the skeleton is a triazine ring, it has the characteristics of excellent transparency, heat resistance, weather resistance, and light resistance, as well as excellent electrical properties at high temperatures.

[0004] The above-mentioned isocyanuric acid type epoxy compounds are generally solid, and when a liquid composition is required for casting or the like, epoxy resin compositions in combination with various organic solvents or general-purpose liquid epoxy compounds are considered. Furthermore, in order to improve the solubility of isocyanuric acid type epoxy compounds in organic solvents and the compatibility with liquid epoxy compounds, and thereby improve the handleability of resin compositions, compositions containing compounds in which the epoxy groups of the isocyanuric acid type epoxy compounds are modified with acid anhydrides have been proposed (Patent Documents 1 to 3).

[0005] International Publication No. 2006 / 035641 International Publication No. 2018 / 074517 Japanese Patent Application Laid-Open No. 2013-209502

[0006] The resin composition obtained by combining the above-mentioned isocyanuric acid type epoxy compound and a liquid epoxy compound has very poor handleability because the isocyanuric acid type epoxy compound easily precipitates during storage, resulting in a non-uniform composition. Furthermore, by modifying the epoxy groups of the isocyanuric acid type epoxy compound with an acid anhydride, the resin composition obtained by combining the modified compound and a liquid epoxy compound is prevented from precipitating during storage, but the composition becomes highly viscous after preparation, which also results in very poor handleability.

[0007] An object of the present invention is to provide an epoxy resin composition containing an isocyanuric acid type epoxy compound and a liquid epoxy compound, which is inhibited from precipitating during storage and has excellent fluidity.

[0008] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they found that by incorporating a levopimaric acid derivative into an epoxy resin composition, specifically by having an isocyanuric acid-type epoxy compound present as a reaction product with a levopimaric acid derivative, precipitation of the epoxy compound during storage can be suppressed and the resin composition has excellent fluidity without adversely affecting the curability of the composition or the properties of the cured product, and thus completed the present invention.

[0009] That is, as a first aspect, the present invention relates to an epoxy resin composition comprising: a reaction product C of an epoxy compound A represented by formula [1] and at least one levopimaric acid derivative B selected from the group consisting of compounds represented by formulas [2-1] to [2-5]; and a liquid epoxy compound D. (In the formula, R １ ~R ３ each independently represents a hydrogen atom or a methyl group; L １ ~L ３ each independently represents an alkylene group having 1 to 10 carbon atoms. (wherein R ４ , R ４’ , R ５ , R ５’ , R ６ , R ７ , R ８ , and R ８’each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms; R ９ , R ９’ , R １０ , and R １０’ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or —COOM, or R ９ or R ９’ and R １０ or R １０’ together form an acid anhydride, and M represents a hydrogen atom, an alkali metal atom, or an alkaline earth metal atom.) A second aspect relates to the epoxy resin composition according to the first aspect, in which the reaction product C is a reaction product of a mixture containing 0.3 to 20 parts by mass of the levopimaric acid derivative B relative to 100 parts by mass in total of the epoxy compound A and the epoxy compound D. A third aspect relates to the epoxy resin composition according to the first or second aspect, in which the levopimaric acid derivative B is at least one compound selected from the group consisting of compounds represented by the following formula: (wherein M' represents an alkali metal atom or an alkaline earth metal atom.) A fourth aspect relates to the epoxy resin composition according to any one of the first to third aspects, in which the epoxy compound D is an aromatic epoxy compound. A fifth aspect relates to the epoxy resin composition according to the fourth aspect, in which the aromatic epoxy compound is a bifunctional aromatic epoxy compound D1. A sixth aspect relates to the epoxy resin composition according to the fifth aspect, in which the bifunctional aromatic epoxy compound D1 is an epoxy compound having a bisphenol A skeleton or a bisphenol F skeleton. A seventh aspect relates to the epoxy resin composition according to any one of the first to sixth aspects, further comprising a curing agent E. An eighth aspect relates to the epoxy resin composition according to the seventh aspect, in which the curing agent E is at least one selected from the group consisting of acid anhydrides, amines, phenolic resins, polyamide resins, imidazoles, polymercaptan, and dicyanamide. A ninth aspect relates to a cured epoxy product, which is a cured product of the epoxy resin composition according to any one of the first to eighth aspects. As a tenth aspect, the present invention relates to a method for producing an epoxy resin composition, the method comprising a step of stirring a mixture containing an epoxy compound A represented by the following formula [1], at least one levopimaric acid derivative B selected from the group consisting of compounds represented by the following formulas [2-1] to [2-5], and a liquid epoxy compound D at a temperature higher than 100°C and lower than 200°C. (In the formula, R １ ~R ３ each independently represents a hydrogen atom or a methyl group; L １ ~L ３ each independently represents an alkylene group having 1 to 10 carbon atoms. (wherein R ４ , R ４’ , R ５ , R ５’ , R ６ , R ７ , R ８ , and R ８’ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms; R ９ , R ９’ , R１０ , and R １０’ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or —COOM, or R ９ or R ９’ and R １０ or R １０’ and M represent a hydrogen atom, an alkali metal atom, or an alkaline earth metal atom.) As an eleventh aspect, the present invention relates to a method for producing an epoxy resin composition according to the tenth aspect, which further comprises, after the stirring step, a step of cooling the mixture to room temperature to 100°C or less, and, after cooling, a step of adding a curing agent E to the mixture and stirring. As a twelfth aspect, the present invention relates to a method for inhibiting precipitation of an epoxy resin composition containing an epoxy compound A represented by the following formula [1] and a liquid epoxy compound D, the precipitation inhibiting method being characterized in that the epoxy resin composition contains a reaction product C of the epoxy compound A with at least one levopimaric acid derivative B selected from the group consisting of compounds represented by the following formulas [2-1] to [2-5]. (In the formula, R １ ~R ３ each independently represents a hydrogen atom or a methyl group; L １ ~L ３ each independently represents an alkylene group having 1 to 10 carbon atoms. (wherein R ４ , R ４’ , R ５ , R ５’ , R ６ , R ７ , R ８ , and R ８’ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms; R ９ , R ９’ , R １０ , and R １０’ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or —COOM, or R ９ or R ９’ and R １０ or R １０’together form an acid anhydride, and M represents a hydrogen atom, an alkali metal atom, or an alkaline earth metal atom.

[0010] According to the present invention, in an epoxy resin composition containing an isocyanuric acid type epoxy compound and a liquid epoxy compound, by having the isocyanuric acid type epoxy compound exist as a reaction product with a levopimaric acid derivative, it is possible to provide a resin composition that is inhibited from precipitating during storage and has excellent fluidity.

[0011] [Epoxy Resin Composition] The epoxy resin composition of the present invention comprises a reaction product C of an epoxy compound A represented by formula [1] (hereinafter also simply referred to as epoxy compound A) with at least one levopimaric acid derivative B (hereinafter also simply referred to as levopimaric acid derivative B) selected from the group consisting of compounds represented by formulas [2-1] to [2-5], and a liquid epoxy compound D. That is, the epoxy resin composition of the present invention may be any embodiment as long as it essentially contains, in addition to liquid epoxy compound D, a reaction product C of epoxy compound A and levopimaric acid derivative B. In one embodiment, the composition includes, in addition to liquid epoxy compound D, an embodiment containing the reaction product C of epoxy compound A and levopimaric acid derivative B; an embodiment containing levopimaric acid B and the reaction product C of epoxy compound A and levopimaric acid derivative B; and an embodiment containing epoxy compound A, levopimaric acid derivative B, and the reaction product C of epoxy compound A and levopimaric acid derivative B.

[0012] [Epoxy Compound A Represented by Formula [1]] The epoxy compound A used in the present invention is represented by the following formula [1]. In the above formula [1], R １ ~R ３ each independently represents a hydrogen atom or a methyl group; L １ ~L ３ each independently represents an alkylene group having 1 to 10 carbon atoms.

[0013] L １ ~L ３Examples of the alkylene group having 1 to 10 carbon atoms represented by the formula (I) include a methylene group, an ethylene group, a trimethylene group, a 1-methylethylene group, a tetramethylene group, a 1-methyltrimethylene group, a 1,1-dimethylethylene group, a pentamethylene group, a 1-methyltetramethylene group, a 2-methyltetramethylene group, a 1,1-dimethyltrimethylene group, a 1,2-dimethyltrimethylene group, a 2,2-dimethyltrimethylene group, a 1-ethyltrimethylene group, a hexamethylene group, a 1-methylpentamethylene group, and a 2-methylpentamethylene group. Examples of the alkyl group include a 3-methylpentamethylene group, a 1,1-dimethyltetramethylene group, a 1,2-dimethyltetramethylene group, a 2,2-dimethyltetramethylene group, a 1-ethyltetramethylene group, a 1,1,2-trimethyltrimethylene group, a 1,2,2-trimethyltrimethylene group, a 1-ethyl-1-methyltrimethylene group, a 1-ethyl-2-methyltrimethylene group, a cyclohexane-1,4-diyl group, a heptamethylene group, an octamethylene group, a nonamethylene group, a 2-methyloctamethylene group, and a decamethylene group. Preferred are a methylene group, a trimethylene group, and a hexamethylene group.

[0014] In the present invention, the epoxy compound represented by formula [1] may be a commercially available epoxy compound, or an isocyanurate ring-containing epoxy compound produced by a known method. Examples of commercially available epoxy compounds that can be used include, but are not limited to, TEPIC (registered trademark)-G, TEPIC (registered trademark)-S, TEPIC (registered trademark)-SP, TEPIC (registered trademark)-SS, and TEPIC (registered trademark)-HP (manufactured by Nissan Chemical Industries, Ltd., triglycidyl isocyanurate); tris(3,4-epoxybutyl)isocyanurate; TEPIC (registered trademark)-VL (registered trademark) (manufactured by Nissan Chemical Industries, Ltd., tris(4,5-epoxypentyl)isocyanurate); tris(5,6-epoxyhexyl)isocyanurate; and TEPIC (registered trademark)-FL (registered trademark) (manufactured by Nissan Chemical Industries, Ltd., tris(7,8-epoxyoctyl)isocyanurate).

[0015] [Levopimaric Acid Derivative B] The levopimaric acid derivative B used in the present invention is at least one compound selected from the group consisting of compounds represented by the following formulas [2-1] to [2-5]. In the above formulas [2-1] to [2-5], R ４ , R ４’ , R ５ , R ５’ , R ６ , R ７ , R ８ , and R ８’ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, and M represents a hydrogen atom, an alkali metal atom, or an alkaline earth metal atom. ９ , R ９’ , R １０ , and R １０’ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or —COOM, or R ９ or R ９’ and R １０ or R １０’ together form an acid anhydride.

[0016] Examples of the linear or branched alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a neopentyl group, and an n-hexyl group.

[0017] Specific examples of the compounds represented by the above formulas [2-1] to [2-5] include compounds represented by the following formulas [2-1a], [2-1b], [2-2a], [2-3a], [2-3b], [2-4a], and [2-5a]. These compounds are resin acids constituting rosin and derivatives thereof, and are also called abietic acid (formula [2-1a]), abietic acid metal salt (formula [2-1b]), tetrahydroabietic acid (formula [2-2a]), acrylopimaric acid (formula [2-3a]), maleopimaric acid (formula [2-3b]), dihydroacrylopimaric acid (formula [2-4a]), or levopimaric acid (formula [2-5a]). (In the above formula, M′ represents an alkali metal atom or an alkaline earth metal atom.)

[0018] In the present invention, the levopimaric acid derivatives B represented by formulas [2-1] to [2-5] may be commercially available products or compounds produced by known methods. Commercially available products include levopimaric acid derivatives or abietic acid derivatives and their development products, available from Arakawa Chemical Industries, Ltd. and Harima Chemicals Group, Inc.

[0019] [Reaction Product C] The reaction product C in the present invention is a reaction product of an epoxy compound A represented by the above formula [1] and at least one levopimaric acid derivative B selected from the group consisting of compounds represented by the above formulas [2-1] to [2-5]. Reaction product C is an ester compound obtained by reacting some or all of the epoxy groups of the epoxy compound A with the levopimaric acid derivative B. The reaction of the epoxy compound A represented by the above formula [1] with the levopimaric acid derivative B can produce a compound in which one molecule of the levopimaric acid derivative B is added to the epoxy compound A, a compound in which two molecules of the levopimaric acid derivative B are added, and a compound in which three molecules of the levopimaric acid derivative B are added. The amounts of these compounds can be adjusted by adjusting the reaction conditions and the number of moles of the levopimaric acid derivative B reacted relative to the number of moles of the epoxy compound A. Unreacted epoxy compound (epoxy compound A) and unreacted levopimaric acid derivative B may be present in the reaction system. The reaction product C can be obtained, for example, by stirring a mixture containing the epoxy compound A represented by the formula [1], the levopimaric acid derivative B, and a liquid epoxy compound D described below at a temperature higher than 100°C and lower than 200°C.

[0020] In the epoxy resin composition of the present invention, the reaction product C can be a reaction product of a mixture containing the levopimaric acid derivative B represented by any of the formulae [2-1] to [2-5] in a ratio of, for example, 0.3 parts by mass to 20 parts by mass, or for example, 1 part by mass to 15 parts by mass, relative to the total amount of the epoxy compounds, i.e., the combined amount (100 parts by mass) of the epoxy compound A represented by the above formula [1] and the liquid epoxy compound D described below.

[0021] [Liquid Epoxy Compound D] The epoxy resin composition of the present invention contains a liquid epoxy compound D. The liquid epoxy compound D dissolves the epoxy compound A represented by the above formula [1], improves the handleability of the epoxy resin composition, and can also play a role in adjusting the physical properties, such as the elastic modulus, of the cured product of the resin composition. The liquid epoxy compound D is not limited to aliphatic epoxy compounds, alicyclic epoxy compounds, or aromatic epoxy compounds, as long as it is a liquid epoxy compound. Among these, aromatic epoxy compounds are preferred, and in a preferred embodiment, a bifunctional aromatic epoxy compound D1 having two epoxy groups can be mentioned. In particular, the aromatic epoxy compound D1 is preferably an epoxy compound having a bisphenol A skeleton or a bisphenol F skeleton.

[0022] Commercially available aromatic epoxy compounds can be used as the aromatic epoxy compound. Examples of the difunctional aromatic epoxy compound D1 include jER (registered trademark) 806, a bisphenol F type epoxy compound manufactured by Mitsubishi Chemical Corporation, and jER (registered trademark) 828, a bisphenol A type epoxy compound manufactured by Mitsubishi Chemical Corporation. Examples of the monofunctional aromatic epoxy compound include phenyl glycidyl ether (e.g., Denacol (registered trademark) EX-141, manufactured by Nagase ChemteX Corporation), phenol (EO) 5 glycidyl ether (e.g., Denacol (registered trademark) EX-145, manufactured by Nagase ChemteX Corporation), and p-tert-butylphenyl glycidyl ether (e.g., Denacol (registered trademark) EX-146, manufactured by Nagase ChemteX Corporation).

[0023] Furthermore, the aliphatic epoxy compound and alicyclic epoxy compound may be a monofunctional or difunctional aliphatic or alicyclic epoxy compound, and commercially available products may be used. For example, the monofunctional aliphatic epoxy compound may be oxiran-2-ylmethyl 2-(4,4-dimethylpentan-2-yl)-5,7,7-trimethyloctanoate (manufactured by Nissan Chemical Industries, Ltd., FOLDI (registered trademark) E101), and the bifunctional aliphatic epoxy compound may be 2,2-bis(oxiran-2-ylmethoxy)methyl)butyl 2-(4,4-dimethylpentan-2-yl)-5,7,7-trimethyloctanoate (manufactured by Nissan Chemical Industries, Ltd., FOLDI (registered trademark) E201), but are not limited thereto. Commercially available examples of the monofunctional alicyclic epoxy compound include 3,4-epoxycyclohexylmethyl methacrylate (e.g., Cyclomer (registered trademark) M-100, manufactured by Daicel Corporation), 3,4-epoxycyclohexylmethyl acrylate (e.g., Cyclomer (registered trademark) A-200, manufactured by Daicel Corporation), 1,2-epoxy-4-vinylcyclohexane (e.g., CELLOXIDE (registered trademark) 2000, manufactured by Daicel Corporation), and 1,2,8,9-diepoxylimonene (e.g., CELLOXIDE (registered trademark) 3000, manufactured by Daicel Corporation). Examples of the bifunctional alicyclic epoxy compound include diepoxybicyclohexyl (e.g., Celloxide (registered trademark) 8000 and 8010, manufactured by Daicel Corporation), 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexenecarboxylate (e.g., Celloxide (registered trademark) 2021P, manufactured by Daicel Corporation), epsilon-caprolactone-modified 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate (e.g., Celloxide (registered trademark) 2081, manufactured by Daicel Corporation), bis(3,4-epoxycyclohexylmethyl)adipate, and diepoxidized tetrahydroindene (e.g., Epocalic (registered trademark) THI-DE, manufactured by ENEOS Corporation).

[0024] In the epoxy resin composition of the present invention, the epoxy compound D can be contained in a proportion of, for example, 5 to 80 parts by mass, or for example, 10 to 70 parts by mass, relative to the total amount of the epoxy compounds, i.e., the combined amount (100 parts by mass) of the epoxy compound A and the epoxy compound D.

[0025] [Curing Agent E] The epoxy resin composition of the present invention may further contain a curing agent E. The curing agent is not particularly limited, but examples include acid anhydrides, amines, phenolic resins, polyamide resins, imidazoles, polymercaptans, and mixtures thereof. Among these, acid anhydrides and amines are particularly preferred. These curing agents, even if solid, can be used by dissolving them in a solvent. However, because evaporation of the solvent can reduce the density of the cured product and create pores, resulting in reduced strength and water resistance, it is preferable for the curing agent itself to be liquid at room temperature and atmospheric pressure. The curing agent can be contained in a ratio of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, per equivalent of epoxy groups in the entire epoxy compound, i.e., the total epoxy compound A represented by formula [1] and the liquid epoxy compound D. The equivalent of the curing agent relative to the epoxy compound is expressed as the equivalent ratio of the curable groups of the curing agent to the epoxy groups. In addition to the epoxy compound A represented by the above formula [1] and the liquid epoxy compound D, when other epoxy compounds are used in combination, the equivalent weight relative to the epoxy groups of all of these epoxy compounds falls within the above range.

[0026] As acid anhydride, the anhydride of the compound having a plurality of carboxyl groups in one molecule is preferred.As these acid anhydrides, for example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, ethylene glycol bistrimellitate, glycerol tristrimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylcyclohexene dicarboxylic anhydride, chlorendic anhydride etc. can be enumerated. Among these, methyltetrahydrophthalic anhydride, methyl-5-norbornene-2,3-dicarboxylic anhydride (methylnadic anhydride, methylhimic anhydride), hydrogenated methylnadic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, methylhexahydrophthalic anhydride, or a mixture of methylhexahydrophthalic anhydride and hexahydrophthalic anhydride, which are liquid at room temperature and normal pressure, are preferred. These liquid acid anhydrides have a viscosity of about 10 to 1,000 mPa s when measured at 25°C. One acid anhydride group is calculated as one equivalent.

[0027] Examples of amines include piperidine, N,N'-dimethylpiperazine, triethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, di(1-methyl-2-aminocyclohexyl)methane, menthanediamine, isophoronediamine, diaminodicyclohexylmethane, 1,3-bis(aminomethyl)cyclohexane, xylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, etc. Among these, liquids such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, bis(1-methyl-2-aminocyclohexyl)methane, menthanediamine, isophoronediamine, and diaminodicyclohexylmethane can be preferably used.

[0028] Examples of phenolic resins include phenol novolac resins and cresol novolac resins.

[0029] Polyamide resins are produced by condensation of dimer acid and polyamine, and are polyamide amines having primary and secondary amines in the molecule.

[0030] Examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, and epoxyimidazole adduct.

[0031] The polymercaptan is preferably a liquid polymer, for example, one in which a mercaptan group is present at the end of a polypropylene glycol chain or one in which a mercaptan group is present at the end of a polyethylene glycol chain.

[0032] Dicyandiamide, known as a latent curing agent, can also be used as curing agent E. Dicyandiamide is practically insoluble in epoxy resins at room temperature, but dissolves and reacts (cures) with epoxy groups when heated to 180°C or higher, making it a latent curing agent with excellent storage stability at room temperature. If a lower curing temperature is desired, the curing temperature can be lowered to, for example, approximately 120-140°C by using a urea- or imidazole-based curing accelerator F, as described below. Dicyandiamide also has the advantage of being able to maintain a semi-cured state for a certain period of time, and the cured product can exhibit high heat resistance and high adhesive strength. Because dicyandiamide contains a catalytic functional group (-CN group) within the compound, it generally does not need to be stoichiometrically equivalent to the epoxy group; it can cure even with a less-than-equivalent amount.

[0033] [Curing Accelerator F] The epoxy resin composition of the present invention may contain, in addition to the curing agent E, an appropriate curing accelerator F (also referred to as a curing aid). Examples of curing accelerators include organic phosphorus compounds such as triphenylphosphine and tributylphosphine; quaternary phosphonium salts such as ethyltriphenylphosphonium bromide and tetrabutylphosphonium O,O-diethylphosphorodithioate; and quaternary ammonium salts such as 1,8-diazabicyclo[5.4.0]undec-7-ene, salts of 1,8-diazabicyclo[5.4.0]undec-7-ene with octylic acid, zinc octylate, and tetrabutylammonium bromide. Furthermore, imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole, as well as amines such as 2,4,6-tris(dimethylaminomethyl)phenol and benzyldimethylamine, which are listed above as curing agents, can also be used as curing accelerators for other types of curing agents. When the aforementioned dicyanamide (DICY) is used as the curing agent, urea derivatives such as phenyldimethylurea and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), or the above-mentioned imidazoles and amines can be used. These curing accelerators can be used in a ratio of 0.001 to 5 parts by mass per part by mass of the curing agent.

[0034] The epoxy resin composition of the present invention may contain a solvent, if necessary. The solvent is not particularly limited as long as it does not impair the effects of the present invention, and alcohols, ketones, ethers, and esters can be used. Examples of the solvent include alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol; ketones such as cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, γ-butyl lactone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone; ethers such as butyl cellosolve; and esters such as ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, and propylene glycol monomethyl ether acetate, but are not limited to these.

[0035] [Other Components] The epoxy resin composition of the present invention may contain conventional additives as needed. Examples of such additives include curing catalysts (photoacid generators, thermal acid generators, base generators, etc.), curable monomers (cationically curable monomers such as vinyl group-containing compounds and oxetanyl group-containing compounds), thickeners, sensitizers, defoamers, leveling agents, coatability improvers, lubricants, stabilizers (antioxidants, heat stabilizers, light resistance stabilizers, etc.), plasticizers, surfactants (fluorine-based surfactants, silicone-based surfactants, nonionic surfactants, etc.), adhesion promoters, dissolution promoters, fillers, antistatic agents, curing agents, etc. These additives may be used alone or in combination of two or more.

[0036] [Method for Producing Epoxy Resin Composition] The method for producing the epoxy resin composition of the present invention is not particularly limited, but it is preferable to produce the composition by, for example, including a step of stirring a mixture containing an epoxy compound A represented by the above formula [1], at least one levopimaric acid derivative B selected from the group consisting of compounds represented by the above formulas [2-1] to [2-5], and the liquid epoxy compound D at a temperature higher than 100°C and lower than 200°C.

[0037] Furthermore, an epoxy resin composition containing curing agent E can be produced by including, after the stirring step, a step of cooling the mixture to room temperature to 100°C or less, and, after cooling, a step of adding the curing agent E to the mixture and stirring. A curing accelerator F may also be added when adding the curing agent E. When adding the curing agent E (and optionally the curing accelerator F), a portion of the liquid epoxy compound D may be set aside in the previous stirring step of the epoxy compound A and the epoxy compound D, and the set aside portion of the liquid epoxy compound D may be mixed with the curing agent E (and optionally the curing accelerator F), and the mixture may then be added to the mixture. The stirring after the addition of the curing agent E (and optionally the curing accelerator F) is preferably carried out under reduced pressure, followed by degassing.

[0038] [Epoxy Cured Product] The epoxy resin composition of the present invention can be applied to a substrate or poured into a casting plate coated with a release agent, and then pre-cured (if necessary) at a temperature of 100 to 120°C, followed by full curing (post-curing) at a temperature of 120 to 200°C, to obtain a cured product. The heating time can be adjusted appropriately depending on the size and thickness of the epoxy resin. For example, the pre-curing and full curing times are each 1 to 12 hours, e.g., about 2 to 5 hours. The cured product of the epoxy resin composition of the present invention is also within the scope of the present invention.

[0039] [Method for inhibiting precipitation of epoxy compound A] The present invention also relates to a method for inhibiting precipitation of epoxy compound A in an epoxy resin composition containing epoxy compound A represented by the above formula [1] and liquid epoxy compound D. The method for inhibiting precipitation is characterized in that the epoxy resin composition contains the isocyanuric acid type epoxy compound as a reaction product with a levopimaric acid derivative, i.e., the epoxy resin composition contains a reaction product C of the epoxy compound A with at least one levopimaric acid derivative B selected from the group consisting of the compounds represented by the above formulas [2-1] to [2-5].

[0040] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0041] In the examples, the apparatus and conditions used for preparing samples and analyzing physical properties are as follows: (1) NMR apparatus: AVANCE III (600 MHz) [manufactured by Bruker] Measurement conditions: １３ C-NMR Deuterated solvent: DMSO-d ６ (2) Viscosity (Rheometer) Apparatus: MCR-302 [manufactured by Anton Paar] Measurement speed: 1 rpm, Measurement temperature: 70°C, 100°C (3) Glass transition temperature Tg Apparatus: Dynamic viscoelasticity measuring apparatus DMA Q800 [manufactured by TA Instruments] Deformation mode: Dual cantilever Frequency: 1 Hz Strain: 0.05% Sweep temperature: 30 to 300°C Heating rate: 5°C / min (4) Flexural strength, flexural modulus, deflection Apparatus: Desktop precision universal testing machine Autograph AGS-5kNX [manufactured by Shimadzu Corporation] Measurement was performed based on JIS K-6911. (4-1) Flexural strength The height (thickness) and width of the test specimen were measured, and the test specimen was supported and a load was applied to its center with a pressure wedge, and the load at which the test specimen broke was measured. P: Load (N) {kgf} when the test piece breaks, L: Distance between supports (mm), W: Width of the test piece (mm), h: Height of the test piece (mm), Bending strength σ: (MPa) {kgf / mm ２} was calculated based on the following formula: Flexural strength σ = (3PL) / (2Wh ２ ) (4-2) Flexural modulus Flexural modulus (E): (MPa) {kgf / mm ２} can be calculated by the following formula, where F / Y is the gradient of the linear portion of the load-deflection curve (N / mm) {kgf / mm}. ３ / (4Wh ３ ) × [F / Y]

[0042] The abbreviations for the components used in the examples are as follows: TEPIC-S: triglycidyl isocyanurate [manufactured by Nissan Chemical Industries, Ltd., trade name: TEPIC (registered trademark)-S, epoxy equivalent: 100 g / eq.] jER828: bisphenol A type epoxy resin [manufactured by Mitsubishi Chemical Corporation, jER (registered trademark) 828, epoxy equivalent: 185 g / eq.] ] Ad-1: Abietic acid [manufactured by Tokyo Chemical Industry Co., Ltd., (purity >80.0%)] Ad-2: Hydrogenated acrylated rosin [containing 30 to 50 mass% of dihydroacrylopimaric acid represented by formula (2-4a), acid value: 239.6 mg KOH / g, manufactured by Arakawa Chemical Industries, Ltd.] Ad-3: Terephthalic acid [manufactured by Tokyo Chemical Industry Co., Ltd.] MH-700: Rikacid (registered trademark) MH-700 [manufactured by New Japan Chemical Co., Ltd., mixture of 4-methylcyclohexane-1,2-dicarboxylic anhydride and cyclohexane-1,2-dicarboxylic anhydride, acid anhydride equivalent: 165 g / eq. Ad-4: acrylic acid-modified rosin [containing 60 to 70% by mass of acrylopimaric acid represented by formula (2-3a), acid value: 247.1 mg KOH / g, manufactured by Arakawa Chemical Industries, Ltd.] Ad-5: 1,4-cyclohexanedicarboxylic acid [manufactured by Tokyo Chemical Industry Co., Ltd.] PX-4ET: tetrabutylphosphonium o,o-diethylphosphorodithioate [manufactured by Nippon Chemical Industry Co., Ltd., Hishicolin (registered trademark) PX-4ET] DICY: dicyandiamide [manufactured by Mitsubishi Chemical Corporation, jER Cure (registered trademark) DICY7] DCMU: 3-(3,4-dichlorophenyl)-1,1-dimethylurea [manufactured by Tokyo Chemical Industry Co., Ltd.] MEK: methyl ethyl ketone [manufactured by Kanto Chemical Co., Ltd.] PGMEA: propylene glycol monomethyl ether acetate [manufactured by Kanto Chemical Co., Ltd.]

[0043] [Preparation of Epoxy Resin Composition] Example 1 10 g of TEPIC-S, 9 g of jER828, and 1 g of Ad-1 were placed in a vessel and mixed under heating at 150° C. for 1 hour to obtain the epoxy resin composition of Example 1.

[0044] (Examples 2 to 12, Examples 24 to 29, Comparative Examples 1 to 10) The epoxy resin compositions of the Examples and Comparative Examples were obtained in the same manner as in Example 1, except that the ingredients and their amounts were changed as shown in Table 1. In Comparative Examples 7 and 8, which incorporated Ad-3, the heating conditions during preparation were 160°C and 3 hours of heat mixing, and in Comparative Examples 9 and 10, which incorporated Ad-5, the heating conditions were 160°C and 2 hours. In the following explanation, the example numbers of the epoxy resin compositions will also be used as example numbers for performance evaluation and physical property evaluation.

[0045] The formation of reaction product C in the epoxy resin composition of Example 6 was confirmed by the following method. TEPIC-S (epoxy compound A), Ad-2 (levopimaric acid derivative B), jER828 (liquid epoxy compound D), the resin composition of Example 6, and the resin composition of Comparative Example 1 １３ The C-NMR spectrum was measured, and the peak intensities before and after the reaction were compared. As a result, the peak (176-180 ppm) derived from the carboxyl group of Ad-2 disappeared, and a new peak derived from an ester bond resulting from the reaction of the carboxyl group of Ad-2 with the epoxy group of TEPIC-S was observed on the high magnetic field side (174-178 ppm). This confirmed that TEPIC-S (epoxy compound A) and Ad-2 (levopimaric acid derivative B) had reacted to produce reaction product C. The resin compositions of the other examples were also confirmed by the same method.

[0046] [Performance evaluation of epoxy resin compositions] (1) Presence or absence of crystal precipitation The epoxy resin compositions of Examples 1 to 12, Examples 24 to 29, and Comparative Examples 1 to 10 were placed in glass containers and sealed, and then left at room temperature for one week, after which the presence or absence of crystal precipitation was visually observed. Evaluation was performed according to the following evaluation criteria. The obtained results are also shown in Table 1. <Evaluation criteria> A: No crystal precipitation, N: Crystal precipitation

[0047] (2) Viscosity Measurement of Epoxy Resin Compositions The viscosities at 70°C and 100°C were measured for the epoxy resin compositions of Examples 1 to 4, Examples 24 and 25, and Comparative Examples 1 and 7 to 10. The results are shown in Table 1.

[0048]

[0049] As shown in Table 1, the epoxy resin compositions of Examples 1 to 12 and Examples 24 to 29, which were prepared by containing Ad-1, Ad-2, or Ad-4, showed no crystal precipitation after standing at room temperature for one week. On the other hand, the epoxy resin compositions of Comparative Examples 1 to 6, which were prepared without using Ad-1, Ad-2, or Ad-4, showed crystal precipitation after standing at room temperature for one week, confirming that they lacked storage stability.

[0050] Furthermore, the epoxy resin compositions of Examples 1 to 4 and Examples 24 and 25 showed an increase in viscosity compared to the epoxy resin composition of Comparative Example 1 which did not contain Ad-1, Ad-2 or Ad-4, but still had low viscosities of approximately 1,000 mPa s or less at 70°C and approximately 130 mPa s or less at 100°C, demonstrating excellent fluidity. On the other hand, the epoxy resin compositions of Comparative Examples 7 and 8, which were prepared by containing Ad-3 (terephthalic acid) instead of Ad-1, Ad-2 or Ad-4, and the epoxy resin compositions of Comparative Examples 9 and 10, which were prepared by containing Ad-5 (1,4-cyclohexanedicarboxylic acid), showed no crystal precipitation after being left at room temperature for one week, but had higher viscosities at both 70°C and 100°C than the epoxy resin compositions of the Examples having equivalent blends of each component (Example 1, Example 2 or Example 25 compared to Comparative Examples 7 and 9, and Example 3, Example 4 or Example 24 compared to Comparative Examples 8 and 10), resulting in poor handleability of the resin compositions.

[0051] [Cured Product Properties of Epoxy Resin Composition 1 (Curing Agents: MH-700, PX-4ET)] (Example 13) 10.5 g of TEPIC-S, 9.45 g of jER828, and 1.05 g of Ad-1 were placed in a container and mixed under heating at 150°C for 1 hour, and then cooled to 70°C. 25.575 g of MH-700 (epoxy equivalent ratio: 1 equivalent) as a curing agent and 0.210 g of PX-4ET as a curing accelerator were then added. This mixture was degassed under reduced pressure while stirring at 70°C for 30 minutes, yielding an epoxy resin composition.

[0052] (Examples 14 to 20, Reference Examples 1 to 5) Epoxy resin compositions of the Examples and Reference Examples were obtained in the same manner as in Example 13, except that the ingredients and their amounts were changed as shown in Table 2. In Reference Examples 1 and 3, in which Ad-3 was added, TEPIC-S, jER828, and Ad-3 were mixed under heating at 160°C for 3 hours.

[0053] Each composition was sandwiched between two glass substrates that had been previously treated with Optool (registered trademark) DSX [manufactured by Daikin Industries, Ltd.] for release, along with a 3 mm thick U-shaped silicone rubber spacer. This was heated at 100°C for 2 hours (pre-curing), then heated to 150°C and heated for 5 hours (main curing). After gradual cooling, the glass substrates were removed to obtain each 3 mm thick cured product. The obtained cured products were evaluated for glass transition temperature, flexural strength (stress), flexural modulus, and deflection. Each physical property was measured using the following procedure. The results are also shown in Table 2.

[0054] [Glass Transition Temperature (Tg)] The storage modulus E' and loss modulus E'' were measured by DMA, and the temperature at which the value of tan δ (loss modulus E'' / storage modulus E') obtained from these showed a maximum was defined as Tg.

[0055] [Flexural strength (stress), flexural modulus, and deflection] Measurements were made in accordance with JIS K-6911:2006. Specifically, a load was applied to the center of a test piece (80 x 10 x 3 mm) supported at a support distance of 64 mm using a pressure wedge, and the gradient F / Y [N / mm] of the linear portion of the load-deflection curve was determined. In addition, the load P [N] at which the test piece broke was determined. From these values ​​and the values ​​of the support distance L [mm], width W [mm], and thickness h [mm] of the test piece, the flexural modulus was calculated using the following formula: Flexural modulus [MPa] = (L ３ ÷4Wh ３ ) × (F / Y) Bending strength (stress) [MPa] = 3PL ÷ 2Wh ２ The deflection (push distance) at the breaking point was evaluated as [deflection].

[0056]

[0057] [Cured Product Properties of Epoxy Resin Composition 2 (Curing Agents: DICY, DCMU)] (Example 21) 13.5 g of TEPIC-S, 9.45 g of jER828 (30% by mass of the amount of jER828 used), and 2.25 g of Ad-2 were placed in a container and mixed by heating at 150°C for 1 hour, followed by cooling to 70°C. Thereafter, a mixture (22.05 g of jER828 (70% by mass of the amount of jER828 used), 1.35 g of DICY, and 1.35 g of DCMU) that had previously been processed using a triple-roll mill was further added. This mixture was degassed under reduced pressure while stirring at 70°C for 30 minutes, yielding an epoxy resin composition.

[0058] (Examples 22 to 23, Reference Examples 6 to 8) Cured products of each Example and Reference Example were obtained in the same manner as in Example 21, except that the blended components and their blended amounts were changed as shown in Table 3.

[0059] Each composition was sandwiched between two glass substrates that had been previously treated with an Optool (registered trademark) DSX [manufactured by Daikin Industries, Ltd.] for release, along with a 3 mm thick U-shaped silicone rubber spacer. This was heated (cured) at 130°C for 2 hours, slowly cooled, and then the glass substrates were removed to obtain 3 mm thick cured products. The resulting cured products were evaluated for glass transition temperature, flexural strength (stress), flexural modulus, and deflection using the same procedures as in Examples 14 to 20 and Reference Examples 1 to 5 above. The results are also shown in Table 3.

[0060]

[0061] As shown in Table 2, the cured products of the epoxy resin compositions prepared using Ad-1 or Ad-2 exhibited glass transition temperatures, flexural strength (stress), flexural modulus, and deflection equivalent to those of the cured products of the epoxy resin compositions prepared using Ad-3 and those of the epoxy resin compositions prepared without using Ad-1 to Ad-3. Furthermore, as shown in Table 3, even when the type of curing agent was changed, the cured products of the epoxy resin compositions prepared using Ad-2 and those prepared without using Ad-2 exhibited equivalent cured product properties.

[0062] [Evaluation of Solvent Solubility of Epoxy Resin Compositions] (Epoxy Resin Composition A) 10 g of TEPIC-S, 10 g of jER828, and 2 g of Ad-2 were placed in a vessel and mixed under heating at 150°C for 1 hour to obtain Epoxy Resin Composition A. (Epoxy Resin Composition B) 10 g of TEPIC-S and 10 g of jER828 were placed in a vessel and mixed under heating at 150°C for 1 hour to obtain Epoxy Resin Composition B.

[0063] (Example 30) 1 g of epoxy resin composition A and 9 g of MEK solvent were mixed in a glass container, and the solubility of the epoxy resin composition in the solvent and the presence or absence of crystal precipitation after leaving it at room temperature for 2 weeks were visually observed. Evaluation was performed according to the following evaluation criteria. The results are also shown in Table 4. <Evaluation criteria> A: Uniformly dissolved and no crystal precipitation after 2 weeks B: Uniformly dissolved but crystal precipitation occurred within 1 week C: Not uniformly dissolved (insoluble)

[0064] Examples 31 to 33 Solvent solubility evaluation was carried out in the same manner as in Example 30, except that the blending components and their blending amounts were changed as shown in Table 4.

[0065] Comparative Examples 11 to 14 Solvent solubility evaluation was carried out in the same manner as in Example 30, except that the blending components and their blending amounts were changed as shown in Table 5.

[0066]

[0067]

[0068] As shown in Examples 30 to 33 in Table 4, in epoxy resin composition A prepared using Ad-2, the components were uniformly dissolved in MEK and PGMEA, and crystal precipitation was suppressed when left at room temperature. On the other hand, as shown in Comparative Examples 11 to 14 in Table 5, in epoxy resin composition B prepared without using Ad-2, when MEK was used as the solvent, the components were uniformly dissolved, but crystal precipitation was observed when left at room temperature, and when PGMEA was used as the solvent, the components did not dissolve.

[0069] As shown in Tables 1 to 5, it has been confirmed that the epoxy resin composition of the present invention inhibits precipitation of the epoxy compound during storage without adversely affecting the curability of the composition or the properties of the cured product, and also has excellent flowability of the resin composition.

Claims

1. A reaction product C of an epoxy compound A represented by formula [1] and at least one levopimaric acid derivative B selected from the group consisting of compounds represented by formula [2-1], formula [2-3], formula [2-4] and formula [2-5], and Liquid epoxy compound D 1. An epoxy resin composition comprising: 【Chemical 1】 (In the formula, R １ ~R ３ each independently represents a hydrogen atom or a methyl group; L １ ~L ３ each independently represents an alkylene group having 1 to 10 carbon atoms. 【Chemistry 2】 (wherein R ４ , R ４’ , R ５ , R ５’ , R ６ , R ７ , R ８ , and R ８’ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms; R ９ , R ９’ , R １０ , and R １０’ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or —COOM, or R ９ or R ９’ and R １０ or R １０’ together to form an acid anhydride, M represents a hydrogen atom, an alkali metal atom, or an alkaline earth metal atom (excluding compounds in which, in the formula [2-1], R 4 is an isopropyl group, R 5 is a hydrogen atom, R 5′ is a hydrogen atom, R 6 is a methyl group, R 7 is a methyl group, R 8 is a hydrogen atom, and M is a hydrogen atom).

2. 2. The epoxy resin composition according to claim 1, wherein the reaction product C is a reaction product of a mixture containing 0.3 to 20 parts by mass of the levopimaric acid derivative B relative to 100 parts by mass in total of the epoxy compound A and the epoxy compound D.

3. The levopimaric acid derivative B is at least one compound selected from the group consisting of compounds represented by the following formula: The epoxy resin composition according to claim 1 or 2. 【Chemistry 3】 (In the formula, M′ represents an alkali metal atom or an alkaline earth metal atom.)

4. 4. The epoxy resin composition according to claim 1, wherein the epoxy compound D is an aromatic epoxy compound.

5. 5. The epoxy resin composition according to claim 4, wherein the aromatic epoxy compound is a difunctional aromatic epoxy compound D1.

6. 6. The epoxy resin composition according to claim 5, wherein the difunctional aromatic epoxy compound D1 is an epoxy compound having a bisphenol A skeleton or a bisphenol F skeleton.

7. The epoxy resin composition according to claim 1 , further comprising a curing agent E.

8. 8. The epoxy resin composition according to claim 7, wherein the curing agent E is at least one selected from the group consisting of acid anhydrides, amines, phenolic resins, polyamide resins, imidazoles, polymercaptans, and dicyanamides.

9. A cured epoxy product, which is a cured product of the epoxy resin composition according to any one of claims 1 to 8.

10. Epoxy compound A represented by the following formula [1]: At least one levopimaric acid derivative B selected from the group consisting of compounds represented by the following formulas [2-1], [2-3], [2-4], and [2-5], and a step of stirring a mixture containing a liquid epoxy compound D at a temperature of more than 100°C and less than 200°C; A method for producing an epoxy resin composition. 【Chemistry 4】 (In the formula, R １ ~R ３ each independently represents a hydrogen atom or a methyl group; L １ ~L ３ each independently represents an alkylene group having 1 to 10 carbon atoms. 【Chemistry 5】 (wherein R ４ , R ４’ , R ５ , R ５’ , R ６ , R ７ , R ８ , and R ８’ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms; R ９ , R ９’ , R １０ , and R １０’ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or —COOM, or R ９ or R ９’ and R １０ or R １０’ together to form an acid anhydride, M represents a hydrogen atom, an alkali metal atom, or an alkaline earth metal atom (excluding compounds in which, in the formula [2-1], R 4 is an isopropyl group, R 5 is a hydrogen atom, R 5′ is a hydrogen atom, R 6 is a methyl group, R 7 is a methyl group, R 8 is a hydrogen atom, and M is a hydrogen atom).

11. After the stirring step, further cooling the mixture to room temperature to 100°C or less; After cooling, adding curing agent E to the mixture and stirring. A method for producing the epoxy resin composition according to claim 10.

12. A method for suppressing precipitation of an epoxy compound A in an epoxy resin composition containing an epoxy compound A represented by the following formula [1] and a liquid epoxy compound D, comprising: The epoxy resin composition contains a reaction product C of the epoxy compound A and at least one levopimaric acid derivative B selected from the group consisting of compounds represented by the following formulas [2-1], [2-3], [2-4], and [2-5]. 【Chemistry 6】 (In the formula, R １ ~R ３ each independently represents a hydrogen atom or a methyl group; L １ ~L ３ each independently represents an alkylene group having 1 to 10 carbon atoms. 【Chemistry 7】 (wherein R ４ , R ４’ , R ５ , R ５’ , R ６ , R ７ , R ８ , and R ８’ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms; R ９ , R ９’ , R １０ , and R １０’ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or —COOM, or R ９ or R ９’ and R １０ or R １０’ together to form an acid anhydride, M represents a hydrogen atom, an alkali metal atom, or an alkaline earth metal atom (excluding compounds in which, in the formula [2-1], R 4 is an isopropyl group, R 5 is a hydrogen atom, R 5′ is a hydrogen atom, R 6 is a methyl group, R 7 is a methyl group, R 8 is a hydrogen atom, and M is a hydrogen atom).

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