Epoxy resin composition

Abstract

To provide an epoxy resin composition having chemical resistance capable of suppressing swelling or dissolution caused by a solvent contained in a solvent ink used in inkjet printing technology.SOLUTION: There is provided an epoxy resin composition comprising 100 pts.mass of an epoxy resin (A), an amine-based curing agent (B) and 2 to 6 pts.mass of an imidazole-based curing agent (C), wherein the equivalent number ratio [the epoxy equivalent of the epoxy resin (A) / the active hydrogen equivalent of the amine-based curing agent (B)] of the epoxy equivalent of the epoxy resin (A) and the active hydrogen equivalent of the amine-based curing agent (B) is 2.0 to 13.0.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Although screen printing has been used traditionally, inkjet printing technology has come to be widely used in recent years because, unlike screen printing, it does not require the preparation of a pattern, it allows for finer printing than screen printing, and inkjet printing devices can be manufactured inexpensively.

[0003] Epoxy adhesives are used to bond components of an inkjet head of an inkjet printing device together, and Patent Document 1 discloses an inkjet head that uses an epoxy adhesive that satisfies certain conditions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-301178 Summary of the Invention [Problem to be solved by the invention]

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

[0006] Furthermore, if the curing temperature of an epoxy resin is high, the adherend is also heated, and when the adherend is cooled after the epoxy resin has cured, distortion or cracking occurs in the adherend, or the distortion of the adherend causes a decrease in adhesion between the adherends, and therefore, a low curing temperature is required for the epoxy resin.

[0007] 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. [Means for solving the problem]

[0008] The epoxy resin composition of the present invention comprises: The composition comprises 100 parts by mass of an epoxy resin (A), an amine-based curing agent (B), and 2 to 6 parts by mass of an imidazole-based curing agent (C), The present invention is characterized in that 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 the epoxy resin (A) / active hydrogen equivalent number of the amine-based curing agent (B)] is 2.0 to 13.0. [Effects of the Invention]

[0009] The epoxy resin composition of the present invention has the above-mentioned constitution, and therefore can produce a cured product that has excellent chemical resistance and is inhibited from swelling or dissolving in the solvent contained in the solvent ink used in inkjet printing.

[0010] 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 peeling in the adherend due to distortion of the adherend. DETAILED DESCRIPTION OF THE INVENTION

[0011] The epoxy resin composition of the present invention contains 100 parts by mass of an epoxy resin (A), an amine-based curing agent (B), and 2 to 6 parts by mass of an imidazole-based curing agent (C). The epoxy resin composition of the present invention is a two-component composition containing a base resin and a curing agent, and is used by mixing the base resin and the curing agent and curing the mixture. The epoxy resin composition of the present invention can also be used as a substantially one-component composition by quickly freezing the base resin and the curing agent after mixing and thawing the mixture before use.

[0012] [Epoxy resin (A)] The epoxy resin composition contains an epoxy resin (A) as the main component. The epoxy resin (A) is not particularly limited, and examples thereof include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, phenol novolac-type epoxy resins, tetraglycidyldiaminodiphenylmethane-type epoxy resins, aminophenol-type epoxy resins, aniline-type epoxy resins, benzylamine-type epoxy resins, and xylenediamine-type epoxy resins. The epoxy resins (A) may be used alone or in combination of two or more.

[0013] The epoxy resin (A) is preferably a bisphenol F epoxy resin, a phenol novolac epoxy resin, or a bisphenol A epoxy resin, since these resins improve the chemical resistance of the cured product of the epoxy resin composition, and more preferably a bisphenol F epoxy resin or a phenol novolac epoxy resin.

[0014] The epoxy resin (A) preferably contains a bisphenol F type epoxy resin and a phenol novolac type epoxy resin, as these improve the chemical resistance of the cured product of the epoxy resin composition.

[0015] Epoxy resins are generally products obtained by adding epichlorohydrin to the hydroxyl groups of a polyhydric alcohol such as a polyhydric phenol (for example, in the following formula (1), the repeating number n=0), or have repeating units obtained 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).

[0016] 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 following structural formula: where the repeating number n is 0 or a natural number.

[0017] [ka]

[0018] The epoxy-based composition may contain a diluent to adjust the viscosity of the base resin, as long as the diluent does not inhibit the action curing of the present invention. The diluent may or may not be reactive. The diluent is not particularly limited, and examples thereof include 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)]trisoxirane, pentaerythritol polyglycidyl ether, 1,4-bis[(oxiran-2-ylmethoxy)methyl]cyclohexane, phenyl glycidyl ether, 1,3-bis(oxiranylmethoxy)benzene, benzyl glycidyl ether, and 3,4-epoxycyclohexylmethyl(3,4-epoxy)cyclohexanecarboxylate. The diluents may be used alone or in combination.

[0019] [Amine-based curing agent (B)] The curing agent for the epoxy composition contains 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) in a predetermined ratio, it can be cured at low temperatures, and the resulting cured product has excellent chemical resistance.

[0020] The amine-based curing agent (B) is not particularly limited, and examples thereof include polyaminoamides, polyoxyalkylenediamines (e.g., polyoxyethylenediamine, polyoxypropylenediamine, polyoxybutylenediamine, polyoxypentylenediamine, etc.), polyether polyamines such as polyoxyalkylene triamines (e.g., polyoxyethylenetriamine, polyoxypropylenetriamine, polyoxybutylenetriamine, polyoxypentylenetriamine, etc.), diethylenetriamine, triethylenetetramine, tetraethylenepentamine, m-xylenediamine, trimethylhexamethylene Examples of the amine curing agent (B) include aliphatic amines such as diamine, 2-methylpentamethylenediamine, diethylaminopropylamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, 1,2-diaminocyclohexane, and Larmin 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 amines and aromatic amines (e.g., MXDA-modified products, IPDA-modified products, etc.). The amine curing agent (B) may be used alone or in combination of two or more types.

[0021] Among the amine-based curing agents (B), polyether polyamines are preferred because they improve the chemical resistance of the cured product of the epoxy resin composition, polyoxyalkylene triamines [formula (5)] and polyoxyalkylenediamines [formula (6)] are more preferred, and polyoxypropylene triamines and polyoxypropylene diamines are more preferred.

[0022] [ka]

[0023] In formula (5), R 1 is preferably an alkylene group having 1 to 3 carbon atoms. 1 may be the same as or different from each other.

[0024] In formula (5), x, y, and z are each a number equal to or greater than 1. x+y+z is preferably 5 to 6. When x+y+z is within the above range, the chemical resistance of the cured product of the epoxy resin composition is improved.

[0025] [ka]

[0026] In formula (6), R 2 is preferably an alkylene group having 1 to 3 carbon atoms. 2 may be the same as or different from each other.

[0027] In formula (6), m is a number equal to or greater than 1. m is preferably 1 to 5, more preferably 1 to 4, and even more preferably 1 to 3. When m is within the above range, the chemical resistance of the cured product of the epoxy resin composition is improved.

[0028] In the present invention, the alkylene group refers to a divalent atomic group generated by removing (abtracting) one hydrogen atom bonded to each different carbon atom in an aliphatic saturated hydrocarbon, or a divalent atomic group generated by removing (abtracting) two hydrogen atoms from methane, and includes both linear and branched atomic groups.

[0029] In formula (5), examples of the alkylene group include an ethylene group, a propylene group [-CH(CH3)-CH2-], a trimethylene group [-CH2-CH2-CH2-], a butylene group, an amylene group [-(CH2)5-], and a hexylene group, with a propylene group being preferred.

[0030] In formula (6), examples of the alkylene group include an ethylene group, a propylene group [-CH(CH3)-CH2-], a trimethylene group [-CH2-CH2-CH2-], a butylene group, an amylene group [-(CH2)5-], and a hexylene group, with a propylene group being preferred.

[0031] The amine curing agent (B) preferably has a cyclic skeleton, which may be either an alicyclic skeleton or an aromatic ring skeleton, since this improves the chemical resistance of the cured product of the epoxy resin composition.

[0032] The alicyclic skeleton refers to a structure in which carbon atoms are bonded in a ring shape and which does not have aromaticity. Examples of the alicyclic skeleton include a cyclopropyl skeleton, a cyclobutyl skeleton, a cyclopentyl skeleton, and a cyclohexyl skeleton, and the cyclohexyl skeleton is preferred.

[0033] The aromatic ring skeleton may be a monocyclic aromatic ring or may be a condensed aromatic ring formed by condensing monocyclic aromatic rings. The aromatic ring is not particularly limited and may be, for example, a benzene ring, a naphthalene ring, an anthracene ring, biphenyl, or phenoxyphenyl, with a benzene ring being preferred. The aromatic ring has one or more hydrogen atoms removed from either the aromatic ring or the condensed aromatic ring, and is bonded to other atoms via a covalent bond.

[0034] Examples of the amine curing agent (B) having a cyclic skeleton include aliphatic amines having an alicyclic skeleton such as 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, norbornene diamine, and 1,2-diaminocyclohexane; aromatic amines having an aromatic ring skeleton such as a reaction adduct of metaxylylenediamine and styrene [formula (2)], 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, 4,4-diamino-3,3-methyldiphenylmethane, diphenylmethane, metaphenylenediamine, diaminodiphenyl sulfone, and N-aminoethylpiperazine; and preferred are a reaction adduct of metaxylylenediamine and styrene [formula (2)], 1,3-bisaminomethylcyclohexane, bis(4-aminocyclohexyl)methane, and N-aminoethylpiperazine.

[0035] [ka]

[0036] 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 the epoxy resin (A) / active hydrogen equivalent number of the amine-based curing agent (B)] (hereinafter, sometimes simply referred to as "equivalent number ratio") is 2.0 or more, preferably 3.0 or more, more preferably 4.0 or more, more preferably 5.0 or more, more preferably 6.0 or more, more preferably 7.0 or more, more preferably 8.0 or more, more preferably 9.0 or more, more preferably 10.0 or more, and more preferably 11.0 or more. 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 curing agent (B) [epoxy equivalent number of the epoxy resin (A) / active hydrogen equivalent number of the amine 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 still more preferably 12.0 or less. When the equivalent ratio is within the above range, the epoxy resin composition can be cured at a 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.

[0037] The epoxy equivalent of the 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 the present invention, the epoxy equivalent of the epoxy resin refers to a value measured in accordance with JIS K7236.

[0038] When the epoxy resin (A) contains multiple types of epoxy resins, the epoxy equivalent of the epoxy resin refers to a value calculated based on the following formula.

[0039] When the epoxy resin (A) contains a total of n types of epoxy resins, the epoxy equivalent of the kth epoxy resin is Ek [g / eq], and the content of the kth epoxy resin is Wk (parts by mass), the value calculated based on the following formula is the epoxy equivalent E of the epoxy resin (A).

[0040] TIFF2025145545000005.tif32170

[0041] The active hydrogen equivalent of the amine curing agent (B) is calculated as follows: Active hydrogen equivalent of amine curing agent (B) [g / eq] = Molecular weight of amine-based curing agent (B) / Number of active hydrogen atoms in amine-based curing agent (B)

[0042] The number of active hydrogen atoms in the amine curing agent (B) refers to the total number of active hydrogen atoms contained in each of the multiple amino groups contained in one molecule of the amine curing agent (B).

[0043] When the amine curing agent (B) contains a plurality of types of amine curing agents, the amount of active hydrogen in the amine curing agent (B) refers to a value calculated based on the following formula.

[0044] Amine curing agent (B) contains a total of m types of amine curing agents, the active hydrogen equivalent of the kth amine curing agent is Qk [g / eq], and the content of the kth amine curing agent is Gk (parts by mass), then the value calculated based on the following formula is the amount of active hydrogen Q of amine curing agent (B).

[0045]

number

[0046] The equivalent ratio R 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 the epoxy resin (A) / active hydrogen equivalent number of the amine-based curing agent (B)] is calculated based on the following formula.

[0047] TIFF2025145545000007.tif31170

[0048] [Imidazole-based curing agent (C)] The epoxy resin composition contains an imidazole curing agent (C). By containing a predetermined amount of the imidazole curing agent (C) together with a predetermined amount of the amine curing agent (B), the epoxy resin composition exhibits good curability and chemical resistance at room temperature (23°C).

[0049] The imidazole curing agent (C) is a compound having an imidazole ring in the molecule. The imidazole curing agent (C) is not particularly limited, but a compound having a substituent on the imidazole ring (imidazole derivative) is preferred. The imidazole curing agent (C) may be used alone or in combination of two or more.

[0050] The imidazole derivative is not particularly limited, and examples thereof include 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, etc. The imidazole derivatives may be used alone or in combination of two or more.

[0051] The imidazole curing agent (C) is preferably an imidazole substituted with alkyl groups at the 1- and 2-positions, more preferably 1,2-dimethylimidazole or 2-ethyl-4-methylimidazole, and even more preferably 2-ethyl-4-methylimidazole. Examples of the alkyl group include chain alkyl groups such as methyl, ethyl, isopropyl, t-butyl, hexyl, dodecyl, and pentadecyl groups, and cyclic alkyl groups such as cyclopentyl and cyclohexyl groups, with chain alkyl groups being preferred, and ethyl and methyl groups being more preferred.

[0052] The content of the imidazole curing agent (C) in the epoxy resin composition is 2 parts by mass or more, preferably 2.5 parts by mass or more, and more preferably 3 parts by mass or more, per 100 parts by mass of the epoxy resin (A). The content of the imidazole curing agent (C) in the epoxy resin composition is 6 parts by mass or less, preferably 5 parts by mass or less, more preferably 3.9 parts by mass or less, more preferably 3.6 parts by mass or less, and more preferably 3.5 parts by mass or less, per 100 parts by mass of the epoxy resin (A). When the content of the imidazole curing agent (C) is within the above range, the chemical resistance of the cured product of the epoxy resin composition is improved.

[0053] [Epoxy resin composition] The epoxy resin composition is a two-part composition consisting of a base component containing an epoxy resin (A) and a curing agent containing an amine-based curing agent (B) and an imidazole-based curing agent (C), and is used by mixing the base component and the curing agent and curing the mixture before use. The composition is particularly suitable for use as an adhesive for bonding components that make up the inkjet head of an inkjet printing device.

[0054] Epoxy resin compositions can be cured at room temperature, and the cured product produced by curing the epoxy resin composition has excellent chemical resistance. Therefore, heating is not required to bond adherends together, and adherends can be firmly bonded together without distortion or cracking that occurs in the adherends due to heating and cooling. Furthermore, because the cured product of the epoxy resin composition has excellent chemical resistance, it will not swell or dissolve due to solvents, etc., even in applications where solvent-containing inks are used, such as the inkjet head of an inkjet printing device, and the adherends can be firmly maintained in a bonded state. [Example]

[0055] The present invention will be described in more detail below using examples, but the present invention is not limited thereto. Specific numerical values ​​of blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the upper limit values ​​(numeric values ​​defined as "equal to or less than") or lower limit values ​​(numeric values ​​defined as "equal to or greater than") of the corresponding blending ratios (content ratios), physical property values, parameters, etc. described in the "Summary of the Invention."

[0056] The following raw materials were used in producing the curable compositions of the Examples and Comparative Examples.

[0057] [Epoxy resin (A)] Bisphenol F epoxy resin (Mitsubishi Chemical Corporation, product name "jER807", epoxy equivalent: 171g / eq) Bisphenol A epoxy resin (Mitsubishi Chemical Corporation, product name "jER828", epoxy equivalent: 190g / eq) Phenol novolac epoxy resin (DIC Corporation, product name "EPICLON N-730A", epoxy equivalent: 176g / eq)

[0058] [Amine-based curing agent (B)] Polyoxypropylene triamine (Huntsman Corporation, trade name "Jeffamine T-403", active hydrogen equivalent: 81 g / eq, formula (3), x + y + z = 5 to 6)

[0059] [ka]

[0060] Polyoxypropylenediamine (Huntsman Corporation, trade name "Jeffamine D-230", active hydrogen equivalent: 60 g / eq, formula (4), m is approximately 2.5)

[0061] [ka]

[0062] Reaction adduct of metaxylylenediamine and styrene (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "Gaskamine 240", active hydrogen equivalent: 103 g / eq, formula (2))

[0063] [ka]

[0064] 1,3-bisaminomethylcyclohexane (Mitsubishi Gas Chemical Company, Inc., product name "1,3-BAC", active hydrogen equivalent: 36g / eq) Bis(4-aminocyclohexyl)methane (manufactured by Chori GLEX Co., Ltd., trade name "PACM", active hydrogen equivalent: 53g / eq) N-aminoethylpiperazine (Huntsman, product name "N-AEP", active hydrogen equivalent: 43g / eq)

[0065] [Imidazole-based curing agent (C)] 2-Ethyl-4-methylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., trade name "Curezol 2E4MZ") 1,2-Dimethylimidazole (manufactured by Shikoku Chemicals Corporation, trade name "Curezol 1,2DMZ") 1-benzyl-2-methylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., trade name "Curezol 1B2MZ")

[0066] (Examples 1 to 20, Comparative Examples 1 to 9) Two-component epoxy resin compositions were prepared, each consisting of a base resin containing a predetermined amount of epoxy resin (A) shown in Tables 1 and 2, and a curing agent containing a predetermined amount of amine-based curing agent (B) and imidazole-based curing agent (C) shown in Tables 1 and 2.

[0067] The curability and chemical resistance of the obtained epoxy resin compositions were evaluated in the following manner.

[0068] (curable) The curability of the epoxy resin composition was evaluated according to the gel time measurement method of JIS C2105 by leaving it to stand at 23°C for 48 hours, then lifting the glass rod and evaluating it based on the following criteria.

[0069] A: The test tube was lifted at the same time as the glass rod. B: The test tube did not lift up at the same time as the glass rod.

[0070] (chemical resistance) A circular container with a 50 mm diameter and a release-treated bottom was prepared. The container had a peripheral wall extending upward from the outer periphery of the bottom to a height of 8 mm. The base and curing agent of an epoxy resin composition were uniformly mixed to prepare a sample. A sample of 0.15 to 0.25 g was dropped into the container and cured at 80°C for 15 hours to produce a granular cured product. This cured product was used as a test specimen. The mass of the test specimen, S0 (g), was measured. The test specimen was then immersed in N-methyl-2-pyrrolidone and allowed 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 using the following formula to indicate chemical resistance. Swelling and cracking of the test specimen were recorded as "cracked," while complete dissolution of the test specimen in N-methyl-2-pyrrolidone was recorded as "dissolved." Change (%) = 100 × (S1 - S0) / S0

[0071] [Table 1]

[0072] [Table 2]

Claims

1. The composition comprises 100 parts by mass of an epoxy resin (A), an amine-based curing agent (B), and 2 to 6 parts by mass of an imidazole-based curing agent (C), an epoxy resin composition characterized in that the equivalent ratio of the epoxy equivalent of the epoxy resin (A) to the active hydrogen equivalent of the amine curing agent (B) [epoxy equivalent of epoxy resin (A) / active hydrogen equivalent of amine curing agent (B)] is 2.0 to 13.

0.

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

3. 3. The epoxy resin composition according to claim 1, wherein the amine-based curing agent (B) contains a polyoxyalkylene triamine.

4. 3. The epoxy resin composition according to claim 1, wherein the imidazole curing agent (C) contains 2-ethyl-4-methylimidazole.

5. 3. The epoxy resin composition according to claim 1, which is used for bonding components of an inkjet head.

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