Latent curing agent and one-component epoxy resin composition

Abstract

The object of the present invention is to provide an imidazole-based curing agent that exhibits high storage stability without encapsulation. [Solution] The above problem can be solved by a latent curing agent to which an epoxy compound having a specific structure represented by the general formula (1), (2), (3), (4), or (5) of the present invention is added to an imidazole compound.

Description

Technical Field

[0001] The present invention relates to a latent curing agent and a one-component epoxy resin composition. According to the present invention, a latent curing agent exhibiting excellent storage stability can be obtained.

Background Art

[0002] Amine compounds are widely used as curing agents for epoxy resins. In particular, imidazole-based curing agents can be sufficiently cured by heat curing even when the blending amount with the epoxy resin is small, and a cured product having a high glass transition point can be obtained.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a normal imidazole compound is formulated in an epoxy resin, the pot life is short, and it will be cured even at room temperature and cannot be used the next day. Therefore, it is used in a two-component system, and an imidazole-based curing agent that can be formulated as a one-component system is desired. To solve this problem, Novacure of Asahi Kasei E-Materials, in which a bisphenol A type epoxy resin is adducted to an imidazole compound, has been put on the market (Patent Document 1). However, since the storage stability of this curing agent is not sufficient, the above Novacure enhances the storage stability by performing a encapsulation treatment. Therefore, an object of the present invention is to provide an imidazole-based curing agent that exhibits high storage stability without encapsulation.

Means for Solving the Problems

[0005] As a result of intensive research on imidazole-based curing agents exhibiting high storage stability, the present inventor surprisingly found that an imidazole-based curing agent with high storage stability can be obtained by adding an epoxy compound having a specific structure to an imidazole compound. The present invention is based on such findings. Therefore, the present invention provides [1] General formula (1), (2), (3), (4), or (5):

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0006] The latent curing agent of the present invention exhibits excellent storage stability. [Modes for carrying out the invention]

[0007] [1] Latent curing agent The latent curing agent of the present invention is a general formula (1), (2), (3), (4), or (5): [ka] [ka] [ka] [ka] [ka] An epoxy compound represented by [formula] and an imidazole compound are attached to it.

[0008] The addition of epoxy compounds to imidazole compounds is not limited to this, but it involves the addition of the =NH group of the imidazole compound to the epoxy group (CH) of the epoxy compound. 2 (O)CH-) reacts with N-CH 2 This means forming a -CH(OH)- bond.

[0009] Epoxy compounds The epoxy compound is not particularly limited, as long as it has one of the structures of general formulas (1) to (5). By having the above structures, the epoxy compound can form a rigid skeleton. By forming a rigid skeleton, it is possible to improve the softening point of the epoxy compound and improve the storage stability of the latent curing agent.

[0010] The epoxy compound X is of general formula (6), (7), or (8): [ka] [ka] [ka] It is a base represented by .

[0011] R 2 is a hydrogen atom or -OCH 2 It is an epoxy group. If X is at the end of the epoxy compound, then at least one R 2 ha-OCH 2 It is an epoxy group. The two R's of X in general formula (4) 2 ha-OCH 2 It is an epoxy group. R 3 R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Specifically, alkyl groups having 1 to 3 carbon atoms are methyl, ethyl, or propyl groups. 3 This is preferably a hydrogen atom or a methyl group.

[0012] Y is given by the general formula (9): [ka] It is a base represented by . R 4 is, -OCH 2 It is an epoxy group, R 3R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Specifically, alkyl groups having 1 to 3 carbon atoms are methyl, ethyl, or propyl groups. 3 This is preferably a hydrogen atom or a methyl group.

[0013] Z is given by the general formula (10): [ka] This is a group represented by . The two bonds can be bonded to any carbon atom in the above structure. Specifically, they may be bonded to carbon atoms of two benzene rings. Alternatively, they may be bonded to carbon atoms forming a cyclopentane ring, or both bonds may be bonded to a single carbon atom.

[0014] R 1 It is either a single bond or an alkylene group having 1 to 3 carbon atoms. Specifically, the alkylene group having 1 to 3 carbon atoms is a methylene group, an ethylene group, or a propyl group. 1 R is preferably a single bond or a methylene group. 1 It may be bonded to either of the two ring structures of X.

[0015] n is 1 to 15, preferably 1 to 10, more preferably 1 to 8, even more preferably 1 to 5, even more preferably 1 to 3, even more preferably 1 or 2, and most preferably 1. The epoxy compound represented by general formula (1) is a polymer, and n may be a single polymer or a mixture of polymers with n ranging from 1 to 15. In the case of a mixture, n in general formula (1) represents the average number of repeats. In the case of a single polymer, n is an integer. m is 0 to 15, preferably 0 to 10, more preferably 0 to 8, even more preferably 0 to 5, even more preferably 0 to 3, even more preferably 0 to 2, and even more preferably 0 or 1. The epoxy compound represented by general formula (2) is a polymer, and the number of m may be a single polymer or a mixture of polymers with m values ​​from 0 to 15. In the case of a mixture, m in general formula (1) represents the average number of repeats. In the case of a single polymer, m is an integer.

[0016] (end) One R of X located at the end 2 ha-OCH 2 It is an epoxy group. Hydrogen atoms are bonded to the terminal bonds of X and Y at the ends. In other words, the terminal X and Y are monovalent groups, not divalent groups.

[0017] (Epoxy group) The number of epoxy groups in the epoxy compound is not particularly limited as long as the effects of the present invention are obtained, but for example, the upper limit is 5 or less, preferably 4 or less, and more preferably 3 or less. The lower limit is not particularly limited as long as the effects of the present invention are obtained, but preferably 2 or more. By being within this range, gelation during the synthesis of imidazole-epoxy adducts can be prevented, and a good epoxy resin cured product can be obtained.

[0018] (Repeating unit) -OCH in the repeating unit in general formula (1) or (2) 2 The number of epoxy groups is either one or two.

[0019] (Average number of epoxy groups) The epoxy compound represented by general formula (1) or (2) is a polymer, but as described above, it may be a mixture of polymers where n is 1 to 15, or a mixture of polymers where m is 0 to 15. In the case of a mixture, the average number of epoxy groups contained in the epoxy compound represented by general formula (1) or (2) is, for example, 5 or less as the upper limit, preferably 4 or less, and more preferably 3 or less. The lower limit is not particularly limited as long as the effects of the present invention are obtained, but is preferably 2 or more. By being within this range, gelation of the epoxy resin cured product is prevented, and a good epoxy resin cured product can be obtained.

[0020] The epoxy compounds used in the present invention are not limited to those described above, but specifically include compounds represented by the following formula. [ka] In the formula, m ranges from 0 to 15, and l ranges from 1 to 15. m is between 0 and 15, preferably between 0 and 10, more preferably between 0 and 8, even more preferably between 0 and 5, even more preferably between 0 and 3, even more preferably between 0 and 2, and even more preferably between 0 or 1. The epoxy compound represented by the above formula is a polymer, and the number of m may be a single polymer or a mixture of polymers with m between 0 and 15. In the case of a mixture, m in the above formula represents the average number of repetitions. In the case of a single polymer, m is an integer. l is 1 to 15, preferably 1 to 10, more preferably 1 to 8, even more preferably 1 to 5, even more preferably 1 to 3, even more preferably 1 or 2, and most preferably 1. The epoxy compound represented by the above formula is a polymer, and the number of l may be a single polymer or a mixture of polymers with l values ​​from 1 to 15. In the case of a mixture, l in the above formula represents the average number of repetitions. In the case of a single polymer, l is an integer.

[0021] Imidazole compounds Imidazole compounds are not limited to, but for example, general formula (11): [ka] (In the formula, R 13 and R 14 Each of these can be independently represented by an imidazole (which is a hydrogen atom, or a linear or branched alkyl group or aromatic group having 1 to 17 carbon atoms). Specifically, imidazole, 4-cyanomethylimidazole, 4-ethylimidazole, 4,5-bis(hydroxymethyl)imidazole, 2-phenylimidazole, 4-phenylimidazole, 4-hydroxymethyl-5-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2-butylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2,4-dimethylimidazole, 2-methyl-4-ethylimidazole, 2-methyl-4-propylimidazole Examples include 2-methyl-4-butylimidazole, 2-ethyl-4-methylimidazole, 2,4-diethylimidazole, 2-ethyl-4-propylimidazole, 2-ethyl-4-butylimidazole, 2-propyl-4-methylimidazole, 2-propyl-4-ethylimidazole, 2,4-dipropylimidazole, 2-propyl-4-butylimidazole, 2-butyl-4-methylimidazole, 2-butyl-4-ethylimidazole, 2-butyl-4-propylimidazole, and 2,4-dibutylimidazole. Preferably, examples include 2-methylimidazole, 2-ethylimidazole, 2,4-dimethylimidazole, 2-methyl-4-ethylimidazole, 2-ethyl-4-methylimidazole, and 2,4-diethylimidazole. Preferably, the solution is imidazole, 2-methylimidazole, or 2-ethyl-4-methylimidazole.

[0022] The content of the imidazole compound and epoxy compound in the latent curing agent of the present invention is not particularly limited, but is 0.5 to 2.0 equivalents of the epoxy compound per mole of the imidazole compound, more preferably 0.8 to 1.7 equivalents, and even more preferably 1.0 to 1.5 equivalents.

[0023] [2] One-component epoxy resin composition The one-component epoxy resin composition of the present invention comprises the latent curing agent and the epoxy resin.

[0024] Epoxy resin The epoxy resin contained in the one-component epoxy resin composition of the present invention is an epoxy resin having an average of one or more epoxy groups per molecule, and preferably an epoxy resin having an average of more than one epoxy group. The number of epoxy groups is not particularly limited as long as it is an average of one or more, but is preferably two or more. The upper limit of epoxy groups is not particularly limited when considering the effect of the epoxy resin in the epoxy resin composition. Note that "average" means the average number of epoxy groups in one molecule when two or more types of epoxy resins are mixed. Specifically, examples of epoxy resins include, for example, epoxy compounds of mononuclear polyvalent phenol compounds (polyglycidyl ethers), epoxy compounds of polynuclear polyvalent phenol compounds (polyglycidyl ethers), epoxy compounds of polyhydric alcohols (polyglycidyl ethers), epoxy compounds of hydroxycarboxylic acids (polyglycidyl ether esters), epoxy compounds of aliphatic, aromatic, or alicyclic polybasic acids (polyglycidyl esters), epoxy compounds of hydroxycarboxylic acids (glycidyl ether esters), epoxy compounds of polyhydric carboxylic acids (glycidyl esters), epoxy compounds of aminophenols (glycidylaminoglycidyl ethers), epoxy compounds of polyhydric amines (glycidylamines), or other epoxy compounds.

[0025] More specifically, examples of the mononuclear polyvalent phenol compound include catechol, resorcinol, hydroquinone, or halogen (e.g., chlorine, bromine) derivatives thereof.

[0026] More specifically, the aforementioned polynuclear polyvalent phenolic compounds include, for example, bisphenol F, bisphenol A, bisphenol S, bisphenol AD, tetramethylbisphenol F, tetramethylbisphenol A, or halogen derivatives thereof; naphthol, biphenol, bixylenol, bisresorcinol, trihydroxybiphenyl, tetrahydroxyphenylethane, phenol novolac, cresol novolac, terpene phenol, phenolized dicyclopentadiene, or halogen derivatives thereof.

[0027] More specifically, examples of the aforementioned polyhydric alcohols include glycerin, neopentyl glycol, ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, polyethylene glycol, polypropylene glycol, thiodiglycol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, bisphenol A-ethylene oxide, or propylene oxide adducts.

[0028] More specifically, examples of the hydroxycarboxylic acids include p-oxybenzoic acid or β-oxynaphthoic acid.

[0029] More specifically, examples of the aforementioned polycarboxylic acids include phthalic acid, methylphthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, endomethylenetetrahydrophthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, decandiolic acid, dodecandiolic acid, tetradecandiolic acid, octadecandiolic acid, or polymerized fatty acids.

[0030] More specifically, examples of the aforementioned aminophenols include p-aminophenol or p-aminoalkylphenol.

[0031] More specifically, examples of the aforementioned polyhydric amines include aniline, o-toluidine, tribromoaniline, m-xylylenediamine, 1,2-diaminocyclohexane, 1,3-bisaminomethylcyclohexane, 4,4′-diaminodiphenylmethane, 4,4′-diaminodicyclohexylmethane, 2,2′-dimethyl-4,4′-4,4′-diaminodicyclohexylmethane, or diaminodiphenylsulfone.

[0032] More specifically, other epoxy compounds include, for example, epoxidized polyolefins, epoxidized polybutadienes, epoxidized soybean oil, glycidyl hydantoin, di or triglycidyl isocyanurates, vinylcyclohexene diepoxides, dicyclopentadiene diepoxides, or 3,4-epoxycyclohexyl-3,4-epoxycyclohexanecarboxylate.

[0033] Among the epoxy resins exemplified above, it is particularly preferable to use bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, naphthol type epoxy resin, or diaminodiphenylmethane type epoxy resin, as these exhibit excellent heat resistance, electrical properties such as insulation, and adhesive properties when the epoxy resin composition of the present invention is cured. The epoxy resin can be used individually or in mixtures of two or more types.

[0034] In the epoxy resin composition according to the present invention, monofunctional epoxy compounds can be used in combination as the epoxy resin, as long as they do not impair the effects of the present invention. Examples include butyl glycidyl ether, phenyl glycidyl ether, higher alcohol glycidyl ether, glycidyl benzoate ester, branched fatty acid glycidyl ester (Cardura E; manufactured by Momentive Performance Materials), and styrene oxide. Generally, these monofunctional epoxy compounds have low viscosity, which is advantageous in terms of handling the epoxy resin composition, but they may reduce the mechanical properties and heat resistance (glass transition temperature) of the final epoxy resin cured product, so their use should be kept to a minimum. Furthermore, one or more of the above monofunctional epoxy resins can be used in combination.

[0035] <Other components in epoxy resin compositions> The epoxy resin composition of the present invention may optionally contain various additives, such as surfactants, fluidity improvers, thixotropic agents, extender pigments and other fillers, coloring pigments or dyes for coloring, rust-inhibiting pigments or rust inhibitors, other resin powders, waxes, etc., to the extent that the effects of the present invention are obtained. In addition, solvents to reduce the viscosity of the epoxy resin composition may be added, such as aromatic solvents such as toluene and xylene; ketone solvents such as dimethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; alcohol solvents such as methanol, ethanol, and isopropyl alcohol; and glycol or glycol ester solvents such as methoxypropanol and methoxypropyl acetate.

[0036] In the one-component epoxy resin composition of the present invention, the weight ratio or molar ratio of the latent curing agent to the epoxy resin is not particularly limited, as long as the one-component epoxy resin composition can be cured to any desired degree of gelation. That is, curable epoxy resin compositions are used for various applications such as adhesives, coatings, sealants, and impregnations, and the desired curing state, curing time, and usage conditions differ depending on the application. Therefore, the weight ratio or molar ratio of the epoxy resin having an average of more than one epoxy group in its molecule in the one-component epoxy resin composition can be appropriately selected. However, the content of the epoxy resin and the latent curing agent in the one-component epoxy resin composition of the present invention is preferably 2 to 50 parts by weight of the latent curing agent per 100 parts by weight of the epoxide compound, more preferably 4 to 40 parts by weight, and most preferably 5 to 30 parts by weight.

[0037] The one-component curable epoxy resin composition of the present invention is a thermosetting epoxy resin composition that does not harden at room temperature (e.g., 0°C to 40°C), but hardens rapidly when heated (e.g., 80°C to 200°C), and can be used as an adhesive, paint, coating, sealing, and impregnation agent.

[0038] 《Epoxy resin cured product》 The epoxy resin cured product of the present invention is obtained by heating the one-component epoxy resin composition. Specific cured products include adhesives, painted surfaces, coatings, sealants, or impregnated materials.

[0039] [3] Method for manufacturing latent curing agent The method for producing the latent curing agent of the present invention involves adding (1), (2), (3), (4), or (5) to an imidazole compound: [ka] [ka] [ka] [ka] [ka] (wherein X is general formula (6), (7), or (8): [ka] [ka] [ka] (In the formula, R 2 is a hydrogen atom or -OCH 2 It is an epoxy group, R 3 This is a group represented by a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Y is given by the general formula (9): [ka] (R in the formula 4 is, -OCH 2 It is an epoxy group, R 3 This is a group represented by a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Z is given by the general formula (10): [ka] (In the formula, the two bonds may be bonded to any carbon atom of the structure of general formula (10), and two bonds may be bonded to one carbon atom) is the group represented by R 1 R is either a single bond or an alkylene group having 1 to 3 carbon atoms, and is bonded to X. 1 It may bond to either of the two ring structures of X, n is between 1 and 15, and m is between 0 and 15. One R of X located at the end 2 ha-OCH 2It is an epoxy group, and hydrogen atoms are bonded to the terminal bonds of X and Y at the ends, and the two R of X in general formula (4) 2 ha-OCH 2 It is an epoxy group, and -OCH in repeating units 2 The number of epoxy groups is 1 or 2. The process includes adding one of the epoxy compounds represented by [the formula].

[0040] In the method for producing the latent curing agent of the present invention, the "imidazole compound" and "epoxy compound" can be used without being limited to those described in the "latent curing agent" section above. The weight ratio or molar ratio of the epoxy compound to the imidazole compound in the addition step is not limited, but is 0.5 to 2.0 equivalents of the epoxy compound per mole of imidazole compound, more preferably 0.8 to 1.7 equivalents, and even more preferably 1.0 to 1.5 equivalents.

[0041] Addition reactions are not particularly limited, but include the =NH group of an imidazole compound and the epoxy group (CH) of an epoxy compound. 2 (O)CH-) reacts with N-CH 2 This means forming a -CH(OH)- bond. Imidazole compounds = NH group and epoxy group (CH) of epoxy compounds 2 In the (O)CH-) reaction, not all groups need to react, but typically 1.0 to 1.5 equivalents of epoxy are used per mole of imidazole. Therefore, the epoxy groups are essentially all consumed by the addition reaction described above.

[0042] The reaction temperature is not particularly limited, but is, for example, 60 to 150°C, preferably 80 to 120°C.

[0043] 《Action》 Although the mechanism by which storage stability is improved in the latent curing agent of the present invention has not been analyzed in detail, it can be presumed as follows. However, the present invention is not limited by the following presumption. The imidazole compound used in the latent curing agent has a rigid structure. This is thought to improve the softening point of the latent curing agent of the present invention and raise the glass transition temperature of the latent curing agent resin. By raising the Tg of the curing agent resin, it is possible to reduce the amount of low-molecular-weight components that dissolve from the surface of the curing agent particles into the epoxy resin in the epoxy resin formulation, and as a result, it is presumed that the storage stability is improved. [Examples]

[0044] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the scope of the present invention.

[0045] Example 1 In this example, a latent curing agent was prepared using 2-methylimidazole as the imidazole compound and XD-1000 (dicyclopentadiene-phenol type epoxy resin manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 250 g / eq) as the epoxy compound. Specifically, 82 parts of 2-methylimidazole and 82 parts of a 1:1 (by weight) mixed solvent of xylene and 2-propanol were added to a 1 L four-necked flask equipped with a stirrer and a nitrogen inlet tube, and the temperature was raised to 80°C while stirring under a nitrogen stream. After the internal temperature reached 80°C, an epoxy solution prepared by dissolving 300 parts of XD-1000 in 300 parts of the xylene-2-propanol mixed solvent was added dropwise over 2 hours. After the dropwise addition was complete, the temperature was maintained at 80°C for 30 minutes while stirring, then the temperature was raised to 200°C, and the solvent was removed by reducing the pressure to obtain a brown solid compound. This was then finely ground using a jet mill to obtain a latent curing agent with a particle size of approximately 5 μm. Ten parts of the obtained latent curing agent were mixed with 100 parts of epoxy resin (jER828 (Bisphenol A type epoxy resin manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 190 g / eq)), and the storage stability and Tg of the cured product were measured. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0046] (Measurement of softening point) The softening point of the obtained solid compound was measured in accordance with JIS K 7234.

[0047] (Measurement of Tg) A mixture of 100 parts epoxy resin (jER828) and 10 parts latent curing agent was poured into a casting mold and cured at 150°C for 1 hour. Dynamic viscoelasticity measurements were performed on the cured material at a heating rate of 2°C / min and a frequency of 1 Hz to determine the glass transition temperature. The evaluation criteria for Tg in Table 1 are as follows. ○: Above 150℃ △: 100~150℃ ×: Below 100 degrees

[0048] (Storage stability) The initial viscosity of a formulation prepared by mixing 100 parts of epoxy resin (jER828) with 10 parts of the obtained latent curing agent was measured. This was stored at 40°C, and the change in viscosity over time was measured. The viscosity increase ratio was calculated from the ratio. The evaluation criteria for storage stability in Table 1 are as follows. ◎: At 40℃, the increase in viscosity is less than double in one week. ○: At 40℃, the increase in viscosity more than doubles in one week (the increase in viscosity is less than double in one day). △: At 40℃, the increase in viscosity more than doubles in one day. ×: Gel formed at 40°C in 1 day.

[0049] Example 2 In this example, the procedure of Example 1 was repeated except that the amount of XD-1000 was changed to the amount shown in Table 1. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0050] Example 3 In this example, the procedure of Example 1 was repeated, except that 2-ethyl-4-methylimidazole was used instead of 2-methylimidazole. The composition is shown in Table 1. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0051] Example 4 In this example, the procedure of Example 1 was repeated, except that imidazole was used instead of 2-methylimidazole. The composition is shown in Table 1. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0052] Example 5 In this example, the procedure of Example 1 was repeated, except that NC-7000L (naphthol-cresol novolac type epoxy resin manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 230 g / eq) was used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0053] Example 6 In this example, the procedure of Example 1 was repeated, except that NC-3000H (biphenyl-novolac type epoxy resin manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 290 g / eq) was used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0054] Example 7 In this example, the procedure of Example 1 was repeated, except that HP-4032D (Naphthalene-type epoxy resin manufactured by DIC Corporation, epoxy equivalent: 136 g / eq) was used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the curing agent of the present invention demonstrated excellent storage stability for one-component epoxy resin compositions. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0055] Example 8 In this example, the procedure of Example 1 was repeated, except that HP-4700 (Naphthalene-type epoxy resin manufactured by DIC Corporation, epoxy equivalent: 165 g / eq) and jER828 were used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0056] Example 9 In this example, the procedure of Example 1 was repeated, except that HP-4032D and HP-4700 were used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0057] Example 10 In this example, the procedure of Example 1 was repeated, except that HP-4770 (Naphthalene-type epoxy resin manufactured by DIC Corporation, epoxy equivalent: 204 g / eq) was used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0058] Example 11 In this example, the procedure of Example 1 was repeated, except that Ogusol PG-100 (fluorene-type epoxy resin manufactured by Osaka Gas Chemical Co., Ltd., epoxy equivalent: 254 g / eq) was used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the curing agent of the present invention exhibited a high softening point, and the one-component epoxy resin composition showed excellent storage stability. Furthermore, the resulting cured product exhibited a Tg of 150°C or higher.

[0059] Comparative Example 1 In this comparative example, the procedure of Example 1 was repeated, except that jER828 was used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the resulting curing agent, when used in a one-component epoxy resin composition, also exhibited poor storage stability.

[0060] Comparative Example 2 In this example, the procedure of Example 3 was repeated, except that jER828 was used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the resulting curing agent, when used in a one-component epoxy resin composition, also exhibited poor storage stability.

[0061] Comparative Example 3 In this example, the procedure of Example 1 was repeated, except that jER1001 (bisphenol A type epoxy resin manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 475 g / eq) was used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the one-component epoxy resin composition of the present invention had poor storage stability, and the Tg of the resulting cured product was 100-150°C.

[0062] Comparative Example 4 In this example, the procedure of Example 3 was repeated, except that jER1001 was used instead of XD-1000. The composition is shown in Table 1. As shown in Table 1, the one-component epoxy resin composition of the present invention had poor storage stability, and the Tg of the resulting cured product was 100-150°C.

[0063] [Table 1] [Industrial applicability]

[0064] The latent curing agent of the present invention can be used in a one-component epoxy resin composition. Furthermore, the one-component epoxy resin composition of the present invention can be used as a thermosetting epoxy resin composition in adhesives, paints, and the like.

Claims

1. General formulas (1), (2), (3), (4), or (5): 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 【Transformation 5】 (wherein X is general formula (6), (7), or (8): 【Transformation 6】 【Transformation 7】 【Transformation 8】 (In the formula, R ２ is a hydrogen atom or -OCH ２ It is an epoxy group, R ３ This is a group represented by a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Y is given by the general formula (9): 【Chemistry 9】 (In the formula R ４ is, -OCH ２ It is an epoxy group, R ３ This is a group represented by a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Z is given by general formula (10): 【Chemistry 10】 (In the formula, the two bonds may be bonded to any carbon atom of the structure of general formula (10), and the two bonds may be bonded to one carbon atom) is the group represented by R １ R is either a single bond or an alkylene group having 1 to 3 carbon atoms, and is bonded to X. １ It may bond to either of the two ring structures of X, n is between 1 and 15, and m is between 0 and 15. One R of X present at the end ２ is -OCH ２ is an epoxy group, and a hydrogen atom is bonded to the terminal bond of X and Y present at the end. Two Rs of X in the general formula (4) ２ are -OCH ２ is an epoxy group, and -OCH in repeating units ２ The number of epoxy groups is one or two. A latent curing agent having an epoxy compound represented by one of the following attached to an imidazole compound.

2. The latent compound according to claim 1, wherein the epoxy compound is selected from the group consisting of epoxy compounds represented by the following formula. 【Chemistry 11】 (In the formula, m is between 0 and 15, and l is between 1 and 15.)

3. A one-component epoxy resin composition comprising a latent curing agent according to claim 1 or 2, and an epoxy resin.

4. An epoxy resin cured product obtained by heating the one-component epoxy resin composition described in claim 3.

5. The imidazole compound may be (1), (2), (3), (4), or (5): 【Chemistry 12】 【Chemistry 13】 【Chemistry 14】 【Chemistry 15】 【Chemistry 16】 (wherein X is general formula (6), (7), or (8): 【Chemistry 17】 [Chemistry 18] 【Chemistry 19】 (In the formula, R ２ is a hydrogen atom or -OCH ２ It is an epoxy group, R ３ This is a group represented by a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Y is given by the general formula (9): 【Chemistry 20】 (In the formula R ４ is, -OCH ２ It is an epoxy group, R ３ This is a group represented by a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Z is given by general formula (10): 【Chemistry 21】 (In the formula, the two bonds may be bonded to any carbon atom of the structure of general formula (10), and the two bonds may be bonded to one carbon atom) is the group represented by R １ R is either a single bond or an alkylene group having 1 to 3 carbon atoms, and is bonded to X. １ It may bond to either of the two ring structures of X, n is between 1 and 15, and m is between 0 and 15. One R of X is located at the end ２ ha-OCH ２ It is an epoxy group, and hydrogen atoms are bonded to the terminal bonds of X and Y at the ends, and the two R of X in general formula (4) ２ ha-OCH ２ It is an epoxy group, and -OCH in repeating units ２ The number of epoxy groups is one or two. The process includes adding one of the epoxy compounds represented by A method for manufacturing a latent curing agent.

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