epoxy resin composition

Abstract

To provide an epoxy resin composition which has chemical resistance capable of suppressing swelling or dissolution caused by a solvent contained in a solvent ink used in inkjet printing technology, can be cured satisfactorily at normal temperature and can be cured satisfactorily even in a thin film state.SOLUTION: There is provided an epoxy resin composition comprising an epoxy resin (A), an amine-based curing agent (B) and an imidazole-based curing agent (C), wherein the equivalent number ratio [the epoxy equivalent number of the epoxy resin (A) / the active hydrogen equivalent number of the amine-based curing agent (B)] of the epoxy equivalent number of the epoxy resin (A) and the active hydrogen equivalent number of the amine-based curing agent (B) is 2.0 to 13.0 and the heating loss of the imidazole-based curing agent (C) is 10% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an epoxy resin composition.

Background Art

[0002] Conventionally, the screen printing method has been used. However, different from the screen printing method, it is not necessary to prepare a pattern, finer printing than the screen printing method is possible, and an inkjet printing apparatus can also be manufactured at a low cost. Therefore, in recent years, printing using inkjet printing technology has been widely used.

[0003] An epoxy adhesive is used as an adhesive for bonding the constituent members of an inkjet head of an inkjet printing apparatus. Patent Document 1 discloses an inkjet head using an epoxy adhesive that satisfies predetermined conditions.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the printing method using inkjet printing technology, solvent inks such as solvent-based inks and oil-based inks are used, and the solvents used in these solvent inks have problems such as swelling or dissolving the epoxy adhesive used in Patent Document 1.

[0006] Furthermore, to achieve finer printing, inkjet printing devices are undergoing miniaturization of the inkjet head. Therefore, the adhesives used to bond the components of the inkjet head are required to be thinner, and to cure well even in this thin-film state. However, epoxy adhesives have the problem of not curing well when applied as a thin film to a substrate.

[0007] Furthermore, if the curing temperature of the epoxy resin is high, the adherend is also heated, and when the adherend cools after the epoxy resin has cured, distortion or cracking occurs in the adherend, or the adhesion between adherends decreases due to the aforementioned distortion of the adherend. For this reason, a low curing temperature for epoxy resin is required.

[0008] The present invention provides an epoxy resin composition that has chemical resistance capable of suppressing swelling or dissolution caused by solvents contained in solvent inks used in inkjet printing technology, and that can be cured well at room temperature and also cured well in a thin film state. [Means for solving the problem]

[0009] The epoxy resin composition of the present invention is It comprises epoxy resin (A), amine-based curing agent (B), and imidazole-based curing agent (C), The equivalent ratio of the epoxy equivalent number of the epoxy resin (A) and the active hydrogen equivalent number of the amine-based curing agent (B) [epoxy equivalent number of epoxy resin (A) / active hydrogen equivalent number of amine-based curing agent (B)] is 2.0 to 13.0, The above-mentioned imidazole-based curing agent (C) is characterized by having a heat loss of 10% or less. [Effects of the Invention]

[0010] Since the epoxy resin composition of the present invention has the above-described structure, it is possible to produce a cured product with excellent chemical resistance in which swelling or dissolution is suppressed when exposed to solvents contained in solvent inks used in inkjet printing.

[0011] Furthermore, since the epoxy resin composition of the present invention can be cured at room temperature, when used as an adhesive, it reduces the occurrence of distortion and cracking in the adherend due to heating during curing, and also reduces the occurrence of delamination in the adherend due to the distortion of the adherend.

[0012] Furthermore, the epoxy resin composition of the present invention can cure well even when applied as a thin film with a thickness of 10 μm or less, thus enabling the thinning of the adhesive portion. Therefore, it can be suitably used in applications where miniaturization of inkjet heads and other components of inkjet printing devices is required. [Modes for carrying out the invention]

[0013] The epoxy resin composition of the present invention comprises an epoxy resin (A), an amine-based curing agent (B), and an imidazole-based curing agent (C). The epoxy resin composition of the present invention is a two-component type comprising a main component and a curing agent, and is used by mixing the main component and the curing agent and curing it. However, the epoxy resin composition of the present invention can also be used substantially as a one-component type by rapidly freezing it after mixing the main component and the curing agent, and then thawing it before use.

[0014] [Epoxy resin (A)] The main component of the epoxy resin composition contains epoxy resin (A). Epoxy resin (A) is not particularly limited and includes, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, tetraglycidyldiaminodiphenylmethane type epoxy resin, aminophenol type epoxy resin, aniline type epoxy resin, benzylamine type epoxy resin, and xylenediamine type epoxy resin. Epoxy resin (A) may be used alone or in combination of two or more types.

[0015] Since the chemical resistance of the cured product of the epoxy resin composition is improved, bisphenol F type epoxy resin, phenol novolac type epoxy resin, and bisphenol A type epoxy resin are preferred, and bisphenol F type epoxy resin and phenol novolac type epoxy resin are more preferred.

[0016] Since the chemical resistance of the cured product of the epoxy resin composition is improved, it is preferable that the epoxy resin (A) contains bisphenol F type epoxy resin and phenol novolac type epoxy resin.

[0017] Generally, an epoxy resin is a product obtained by adding epichlorohydrin to the hydroxyl group of a polyhydric alcohol such as a polyhydric phenol (for example, in the following formula (1), the repeating number n = 0), or has a repeating unit generated by ring-opening addition of epichlorohydrin to a polyhydric alcohol (for example, in the following formula (1), the repeating number n is a natural number).

[0018] When the epoxy resin (A) is a bisphenol F type epoxy resin (for example, a reaction product of bisphenol F and epichlorohydrin), it has the structural formula shown below. However, the repeating number n is 0 or a natural number.

[0019]

Chemical formula

[0020] The epoxy composition may contain a diluent for adjusting the viscosity of the main agent within a range that does not inhibit the action curing of the present invention. Whether the diluent has reactivity is irrelevant. The diluent is not particularly limited. For example, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 2,2’,2”-[1,2,3-propanetriyltri(oxymethylene)]trisoxolane, pentaerythritol polyglycidyl ether, 1,4-bis[(oxiran-2-ylmethoxy)methyl]cyclohexane, phenyl glycidyl ether, 1,3-bis(oxiranylmethoxy)benzene, benzyl glycidyl ether, 3,4-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate, etc. may be mentioned. In addition, the diluent may be used alone or two or more kinds may be used in combination.

[0021] [Amine curing agent (B)] The curing agent of the epoxy composition includes an amine curing agent (B) and an imidazole curing agent (C). Since the epoxy resin composition contains the amine curing agent (B) and the imidazole curing agent (C) respectively in a predetermined ratio, it can be cured at a low temperature and the cured product produced has excellent chemical resistance.

[0022] The amine-based curing agent (B) is not particularly limited and includes, for example, polyaminoamides, polyoxyalkylenediamines (e.g., polyoxyethylenediamine, polyoxypropylenediamine, polyoxybutylenediamine, polyoxypentylenediamine, etc.), polyoxyalkylentriamines (e.g., polyether polyamines such as polyoxyethylenetriamine and polyoxypropylenetriamine, polyoxybutylenediamine, polyoxypentylenediamine, etc.), diethylenetriamine, triethylenetetramine, tetraethylenepentamine, m-xylenediamine, trimethylhexamethyl Examples include aliphatic amines such as rediamine, 2-methylpentamethylenediamine, diethylaminopropylamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, 1,2-diaminocyclohexane, and laromine C-260; aromatic amines such as 4,4-diamino-3,3-methyldiphenylmethane, diphenylmethane, metaphenylenediamine, diaminodiphenylsulfone, and N-aminoethylpiperazine; and modified products of the above aliphatic and aromatic amines (e.g., MXDA modified products, IPDA modified products, etc.). The amine-based curing agent (B) may be used alone or in combination of two or more types.

[0023] Among the amine-based curing agents (B), polyether polyamines are preferred because they improve the chemical resistance of the cured epoxy resin composition, polyoxyalkylenetriamine [formula (5)] and polyoxyalkylenediamine [formula (6)] are more preferred, and polyoxypropylenetriamine and polyoxypropylenediamine are even more preferred.

[0024] [ka]

[0025] In formula (5), R 1 The alkylene group having 1 to 3 carbon atoms is preferred. 1 They may be identical or different from one another.

[0026] In formula (5), x, y, and z are each a number greater than or equal to 1. x+y+z is preferably between 5 and 6. When x+y+z is within this range, the chemical resistance of the cured epoxy resin composition is improved.

[0027] [ka]

[0028] In formula (6), R 2 The alkylene group having 1 to 3 carbon atoms is preferred. 2 They may be identical or different from one another.

[0029] In formula (6), m is a number of 1 or more. m is preferably 1 to 5, more preferably 1 to 4, and more preferably 1 to 3. When m is within the above range, the chemical resistance of the cured epoxy resin composition is improved.

[0030] In the present invention, an alkylene group is a divalent atomic group formed by removing (extracting) one hydrogen atom from each of the different carbon atoms bonded to aliphatic saturated hydrocarbons, or a divalent atomic group formed by removing (extracting) two hydrogen atoms from methane, and includes both linear and branched atomic groups.

[0031] In formula (5), examples of alkylene groups include ethylene, propylene [-CH(CH3)-CH2-], trimethylene [-CH2-CH2-CH2-], butylene, amylene [-(CH2)5-], and hexylene, with propylene being preferred.

[0032] In formula (6), examples of alkylene groups include ethylene, propylene [-CH(CH3)-CH2-], trimethylene [-CH2-CH2-CH2-], butylene, amylene [-(CH2)5-], and hexylene, with propylene being preferred.

[0033] The amine-based curing agent (B) is preferable to have a cyclic skeleton because it improves the chemical resistance of the cured epoxy resin composition. The cyclic skeleton may be either an alicyclic skeleton or an aromatic ring skeleton.

[0034] An alicyclic skeleton is a structure in which carbon atoms are bonded in a ring and does not possess aromaticity. Examples of alicyclic skeletons include the cyclopropyl skeleton, cyclobutyl skeleton, cyclopentyl skeleton, and cyclohexyl skeleton, with the cyclohexyl skeleton being preferred.

[0035] The aromatic ring skeleton may be a monocyclic aromatic ring or a compound fused aromatic ring (fused aromatic ring). The aromatic ring is not particularly limited and examples include a benzene ring, naphthalene ring, anthracene ring, biphenyl, phenoxyphenyl, etc., with the benzene ring being preferred. In the aromatic ring, one or more hydrogen atoms are abstracted from either the aromatic ring or the fused aromatic ring and are covalently bonded to other atoms.

[0036] Examples of amine-based curing agents (B) having a cyclic skeleton include aliphatic amines having an alicyclic skeleton such as 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, and 1,2-diaminocyclohexane; reaction adducts of metaxylylenediamine and styrene [formula (2)]; aromatic amines having an aromatic ring skeleton such as 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, 4,4-diamino-3,3-methyldiphenylmethane, diphenylmethane, metaphenylenediamine, diaminodiphenylsulfone, and N-aminoethylpiperazine. Metaxylylenediamine and styrene reaction adducts [formula (2)], 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, and N-aminoethylpiperazine are preferred.

[0037] [ka]

[0038] In the epoxy resin composition, the equivalent ratio of the epoxy equivalent number of epoxy resin (A) to the active hydrogen equivalent number of the amine-based curing agent (B) [epoxy equivalent number of epoxy resin (A) / active hydrogen equivalent number of amine-based curing agent (B)] (hereinafter sometimes simply referred to as the "equivalent ratio") is 2.0 or higher, preferably 3.0 or higher, more preferably 4.0 or higher, more preferably 5.0 or higher, more preferably 6.0 or higher, more preferably 7.0 or higher, more preferably 8.0 or higher, more preferably 9.0 or higher, more preferably 10.0 or higher, and more preferably 11.0 or higher. In the epoxy resin composition, the equivalent ratio of the epoxy equivalent number of the epoxy resin (A) to the active hydrogen equivalent number of the amine-based curing agent (B) [epoxy equivalent number of epoxy resin (A) / active hydrogen equivalent number of amine-based curing agent (B)] is 13.0 or less, more preferably 12.8 or less, more preferably 12.5 or less, more preferably 12.3 or less, and more preferably 12.0 or less. When the equivalent ratio is within the above range, the epoxy resin composition can be cured at room temperature of 23°C, and distortion or cracking of the adherend due to heating during curing, or peeling of the adherend due to distortion of the adherend, can be reduced.

[0039] The epoxy equivalent of epoxy resin (A) is the value obtained by dividing the molecular weight of the epoxy resin by the number of epoxy groups in one molecule. In this invention, the epoxy equivalent of epoxy resin refers to the value measured in accordance with JIS K7236.

[0040] If epoxy resin (A) contains multiple types of epoxy resins, the epoxy equivalent of the epoxy resins refers to the value calculated based on the following formula.

[0041] Epoxy resin (A) contains a total of n types of epoxy resins. When the epoxy equivalent of the k-th epoxy resin is Ek [g / eq] and the content of the k-th epoxy resin is Wk (parts by mass), the epoxy equivalent E of epoxy resin (A) is calculated based on the following formula.

[0042] TIFF0007911416000005.tif32170

[0043] The active hydrogen equivalent of the amine-based curing agent (B) is calculated as follows: Active hydrogen equivalent [g / eq] of amine-based curing agent (B) = Molecular weight of amine-based curing agent (B) / Number of active hydrogen atoms in amine-based curing agent (B)

[0044] The number of active hydrogens in an amine-based curing agent (B) refers to the total number of active hydrogens contained in each of the multiple amino groups within a single molecule of the amine-based curing agent (B).

[0045] When amine-based curing agent (B) contains multiple types of amine-based curing agents, the amount of active hydrogen in amine-based curing agent (B) refers to the value calculated based on the following formula.

[0046] Amine-based curing agent (B) contains a total of m types of amine-based curing agents. When the active hydrogen equivalent of the k-th amine-based curing agent is Qk [g / eq] and the content of the k-th amine-based curing agent is Gk (parts by mass), the active hydrogen amount Q of amine-based curing agent (B) is calculated based on the following formula.

[0047]

number

[0048] The equivalent ratio R[epoxy equivalent of epoxy resin (A) / active hydrogen equivalent of amine-based curing agent (B)] between the epoxy equivalent of epoxy resin (A) and the active hydrogen equivalent of the amine-based curing agent (B) is calculated based on the following formula.

[0049] TIFF0007911416000007.tif31170

[0050] [Imidazole-based curing agent (C)] The epoxy resin composition contains an imidazole-based curing agent (C). By containing a predetermined amount of imidazole-based curing agent (C) together with a predetermined amount of amine-based curing agent (B), the epoxy resin composition exhibits good curability and chemical resistance at room temperature (23°C).

[0051] The imidazole-based curing agent (C) is a compound having an imidazole ring in its molecule. The imidazole-based curing agent (C) is not particularly limited, but compounds having substituents on the imidazole ring (imidazole derivatives) are preferred. The imidazole-based curing agent (C) may be used alone or in combination of two or more types.

[0052] The imidazole derivative is not particularly limited, and examples include 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzylimidazole, and 1-benzyl-2-phenylimidazole, with 1-benzyl-2-phenylimidazole being preferred. The imidazole derivative may be used alone or in combination of two or more types.

[0053] The imidazole-based curing agent (C) is preferably an imidazole in which the 1st or 2nd position is substituted with a substituent having an aromatic ring skeleton, more preferably an imidazole in which both the 1st and 2nd positions are substituted with substituents having an aromatic ring skeleton, and even more preferably 1-benzyl-2-phenylimidazole.

[0054] The aromatic ring skeleton may be a monocyclic aromatic ring or a compound fused aromatic ring (fused aromatic ring), but a monocyclic aromatic ring is preferred. The aromatic ring is not particularly limited and examples include a benzene ring, naphthalene ring, anthracene ring, biphenyl, phenoxyphenyl, etc., with a benzene ring being preferred. In the aromatic ring, one or more hydrogen atoms are abstracted from either the aromatic ring or the fused aromatic ring and are covalently bonded to other atoms.

[0055] The substituent having an aromatic ring skeleton is not particularly limited, and examples include a benzyl group, a phenyl group, and a naphthylmethyl group. Phenyl and benzyl groups are preferred because they allow the epoxy resin composition to be cured more effectively in a thin film form.

[0056] The imidazole-based curing agent (C) has a heat loss of 10% or less, preferably 8% or less, and more preferably 6% or less. When the heat loss of the imidazole-based curing agent (C) is 10% or less, the epoxy resin composition has excellent curability even in the form of a thin film.

[0057] The heat loss of the imidazole-based curing agent (C) refers to the value measured according to the following procedure. Prepare a metallic container with a circular base with a diameter of 50 mm and a peripheral wall with a height of 8 mm formed from the outer edge of the base upwards. Drop 0.15 to 0.25 g of the imidazole-based curing agent (C) into this container as a sample. Measure the mass M0 of the sample dropped into the container. Next, leave the sample in the container in an atmosphere of 80°C for 15 hours and measure the mass M1 of the sample after heating. Calculate the heat loss (%) of the imidazole-based curing agent (C) using the following formula. Loss on heating of imidazole-based curing agent (C) (%) = 100 × (M0 - M1) / M0

[0058] The content of imidazole-based curing agent (C) in the epoxy resin composition is preferably 2 parts by mass or more, more preferably 2.5 parts by mass or more, and more preferably 3 parts by mass or more, per 100 parts by mass of epoxy resin (A). The content of imidazole-based curing agent (C) in the epoxy resin composition is preferably 12 parts by mass or less, more preferably 11 parts by mass or less, more preferably 10 parts by mass or less, more preferably 9.5 parts by mass or less, and more preferably 9.0 parts by mass or less, per 100 parts by mass of epoxy resin (A). When the content of imidazole-based curing agent (C) is within the above range, the chemical resistance of the cured product of the epoxy resin composition is improved.

[0059] [Epoxy resin composition] The epoxy resin composition is a two-component type, comprising a main component containing epoxy resin (A) and a curing agent containing an amine-based curing agent (B) and an imidazole-based curing agent (C). It is used after mixing the main component and curing the mixture before use and is suitable for use as an adhesive. In particular, it is suitable for use as an adhesive between the components that make up the inkjet head of an inkjet printing device.

[0060] Epoxy resin compositions can be cured at room temperature even in the form of a thin film, and the cured product produced by curing the epoxy resin composition has excellent chemical resistance. Therefore, heating is not required when bonding adherends together, and adherends can be firmly bonded and integrated without causing distortion or cracking due to heating and cooling. Since epoxy resin compositions cure well even in the form of a thin film, the thickness of the cured epoxy resin composition can be reduced, and when used as an adhesive between adherends, the size of the bonded area can be reduced, and the size of the product obtained by bonding adherends can be reduced. Furthermore, since the cured product of the epoxy resin composition has excellent chemical resistance, even when using inks containing solvents, such as inkjet heads in inkjet printing machines, it will not swell or dissolve due to solvents, and the bond between adherends can be firmly maintained. [Examples]

[0061] The present invention will be described more specifically below with reference to examples, but the present invention is not limited thereto. Specific numerical values ​​such as blending ratios (content), physical properties, and parameters used in the following description may be replaced with the corresponding upper limits (numerical values ​​defined as "less than or equal to" or "less than") or lower limits (numerical values ​​defined as "greater than or equal to") of the blending ratios (content), physical properties, and parameters described in the "Means for Solving the Problems" section.

[0062] The following raw materials were used in the production of the curable compositions of the examples and comparative examples.

[0063] [Epoxy resin (A)] • Bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER807", epoxy equivalent: 171g / eq) • Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "jER828", epoxy equivalent: 190g / eq) • Phenol novolac type epoxy resin (DIC Corporation, product name "EPICLON N-730A", epoxy equivalent: 176g / eq)

[0064] [Amine-based curing agent (B)] • Polyoxypropylene triamine (Huntsman Corporation, product name "Jeffermin T-403", active hydrogen equivalent: 81 g / eq, formula (3), x+y+z=5~6)

[0065] [ka]

[0066] • Polyoxypropylenediamine (Huntsman Corporation, product name "Jeffermin D-230", active hydrogen equivalent: 60 g / eq, formula (4), m is approximately 2.5)

[0067] [ka]

[0068] • Reaction adduct of metaxylylenediamine and styrene (manufactured by Mitsubishi Gas Chemical Company, product name "Gascamin 240", active hydrogen equivalent: 103 g / eq, formula (2))

[0069] [ka]

[0070] • 1,3-Bisaminomethylcyclohexane (manufactured by Mitsubishi Gas Chemical Company, product name "1,3-BAC", active hydrogen equivalent: 36g / eq) • Bis(4-aminocyclohexyl)methane (manufactured by Chori GLEX Co., Ltd., product name "PACM", active hydrogen equivalent: 53g / eq) • N-aminoethylpiperazine (Huntsman Corporation, product name "N-AEP", active hydrogen equivalent: 43g / eq)

[0071] [Imidazole-based curing agent (C)] • 1-Benzyl-2-phenylimidazole (manufactured by Shikoku Chemicals Co., Ltd., product name "Curezol 1B2PZ", loss on heating: 1.0%) • 2-Ethyl-4-methylimidazole (manufactured by Shikoku Chemicals Co., Ltd., product name "Curezol 2E4MZ", loss on heating: 32.5%) • 1,2-Dimethylimidazole (manufactured by Shikoku Chemicals Co., Ltd., product name "Curezol 1,2DMZ", loss on heating: 99.8%) • 1-Benzyl-2-methylimidazole (manufactured by Shikoku Chemicals Co., Ltd., product name "Curezol 1B2MZ", weight loss on heating: 12.8%)

[0072] (Examples 1-17, Comparative Examples 1-8) A two-component epoxy resin composition was prepared, comprising a main component containing a predetermined amount of epoxy resin (A) as shown in Tables 1 and 2, and a curing agent containing predetermined amounts of amine-based curing agent (B) and imidazole-based curing agent (C) as shown in Tables 1 and 2.

[0073] The obtained epoxy resin compositions were evaluated for room-temperature curability, thin-film curability, and chemical resistance according to the following procedure.

[0074] (Room temperature curable) The curing properties of the epoxy resin composition were evaluated based on the following criteria after standing for 48 hours at 23°C in accordance with the method for measuring gelation time specified in JIS C2105, and then lifting the glass rod.

[0075] A... The test tube was lifted at the same time as the glass rod. B... The test tube did not lift at the same time as the glass rod.

[0076] (thin film curability) A sample was prepared by mixing the main component and curing agent of an epoxy resin composition. 0.2 g of this sample was coated as a thin film with a thickness of 10 μm onto a glass plate with a smooth surface, and a test specimen was prepared on the glass plate. The test specimen was then heated at 80°C for 15 hours.

[0077] A cloth soaked in acetone was prepared. The test specimen on the glass plate was wiped with the cloth and evaluated according to the following criteria. If the test specimen was not wiped off, it could be concluded that the entire specimen had hardened. If part or all of the test specimen was wiped off, it could be concluded that the test specimen had not hardened sufficiently. A...The test sample was not wiped away. B...Part or all of the test specimen was wiped away.

[0078] (Chemical resistance) A circular container with a diameter of 50 mm and a release-treated bottom surface, and a peripheral wall with a height of 8 mm formed upward from the outer edge of the bottom surface, was prepared. The main component and hardener of the epoxy resin composition were uniformly mixed to prepare the sample. 0.15 to 0.25 g of the sample was dropped into the container, and the sample was cured at 80°C for 15 hours to produce granular cured material, which was used as the test specimen. The mass S0 (g) of the test specimen was measured. Next, the test specimen was immersed in N-methyl-2-pyrrolidone and left to stand at 80°C for 24 hours. After 24 hours, the test specimen was removed and its mass S1 (g) was measured. The change (%) was calculated based on the following formula and defined as chemical resistance. If the test specimen swelled and cracked, it was recorded as "cracked," and if the test specimen completely dissolved in N-methyl-2-pyrrolidone, it was recorded as "dissolved." Change (%) = 100 × (S1 - S0) / S0

[0079] [Table 1]

[0080] [Table 2]

Claims

1. It comprises epoxy resin (A), amine-based curing agent (B), and imidazole-based curing agent (C), The equivalent ratio of the epoxy equivalent number of the epoxy resin (A) to the active hydrogen equivalent number of the amine-based curing agent (B) [epoxy equivalent number of epoxy resin (A) / active hydrogen equivalent number of amine-based curing agent (B)] is 2.0 to 13.0, The heat loss of the above imidazole-based curing agent (C) is 10% or less. The above imidazole-based curing agent (C) is an imidazole in which the 1st and 2nd positions are substituted with substituents having an aromatic skeleton. The heat loss of the imidazole-based curing agent (C) is the percentage of the mass of the imidazole-based curing agent (C) that was reduced by heating, relative to the mass of the imidazole-based curing agent (C) before heating, after heating the imidazole-based curing agent (C) in an atmosphere of 80°C for 15 hours. An epoxy resin composition characterized by its use for bonding components of an inkjet head.

2. The epoxy resin composition according to claim 1, characterized in that the epoxy resin (A) comprises a bisphenol F type epoxy resin and / or a phenol novolac type epoxy resin.

3. The epoxy resin composition according to claim 1 or 2, characterized in that the amine-based curing agent (B) contains a polyoxyalkylentriamine.

4. The epoxy resin composition according to claim 1 or 2, characterized in that the imidazole-based curing agent (C) comprises 1-benzyl-2-phenylimidazole.

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