Epoxy resin composition and cured product thereof

Abstract

An epoxy resin composition and a cured product thereof. The epoxy resin composition comprises: an epoxy resin (A), an epoxy resin curing agent (B), a solvent (C), and an aromatic hydrocarbon formaldehyde resin (D); the mass ratio of the total content of component (C) and component (D) to the total content of components (B), (C), and (D) [(C+D) / (B+C+D)] is 0.42 to 0.57, and the mass ratio C / D of component (C) to component (D) is 1.00 or greater.

Description

Technical Field

[0001] The present invention relates to an epoxy resin composition and a cured product thereof. Background Art

[0002] Polyamine compounds are known to be useful as epoxy resin curing agents. Epoxy resin compositions utilizing these epoxy resin curing agents are widely used in the fields of coatings, such as anti-corrosion coatings for ships, bridges, and land and sea rail structures; concrete building linings, reinforcements, crack repair materials, sealants, injection materials, primers, screeds, surface coatings, FRP reinforcements; building flooring materials, water linings, paving materials, adhesives, and other civil engineering and construction fields; die-bonding materials, insulating sealants, and other electrical and electronic fields; and fiber-reinforced plastics.

[0003] Furthermore, in order to impart desired properties according to the intended use to epoxy resin compositions, it is known to use modified epoxy resins modified with aromatic hydrocarbon formaldehyde resins.

[0004] For example, Patent Document 1 discloses a thermosetting epoxy resin composition containing an epoxy resin and an aromatic hydrocarbon formaldehyde resin-modified novolac-type epoxy resin, which has excellent heat resistance, high adhesion, and moisture resistance.

[0005] Patent Document 2 discloses a heavy-duty anti-corrosion coating composition containing an epoxy resin, an amine-based curing agent, and a reaction product of an aromatic hydrocarbon formaldehyde resin and an epoxy resin in a specific ratio. The composition has no safety or sanitation issues, and exhibits excellent corrosion resistance, water resistance, and adhesion. Compared to tar, the composition can form a brighter coating film.

[0006] Patent Documents 1 and 2 disclose technologies for modifying epoxy resins using aromatic hydrocarbon formaldehyde resins. There are also known technologies for compounding aromatic hydrocarbon formaldehyde resins into epoxy resin compositions. For example, Patent Document 3 discloses a heavy-duty anticorrosion coating composition comprising an epoxy resin, an amine-based curing agent, an aromatic hydrocarbon formaldehyde resin, a pigment, and a solvent. This coating composition eliminates the safety and sanitation issues associated with tar, addresses the poor compatibility of petroleum resins, produces no sticky residue on the coating film, and exhibits excellent corrosion resistance and low-temperature curability.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 7-48499

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2000-26769

[0011] Patent Document 3: Japanese Patent Application Laid-Open No. 2001-152085 Summary of the Invention

[0012] Problems to be solved by the invention

[0013] In the epoxy resin compositions used for coatings, flooring materials, adhesives, sealants, etc., it is sometimes required to be able to cure at room temperature. In addition, in these uses, it is required that the mechanical properties of the cured product of the epoxy resin composition are good. As the mechanical properties of the cured product, from the viewpoint of durability, it is preferred that the mechanical strength is high and that it has flexibility. However, in the epoxy resin compositions of the prior art, there is still room for improvement for obtaining a cured product excellent in mechanical strength and flexibility.

[0014] An object of the present invention is to provide an epoxy resin composition that can be cured at room temperature and can form a cured product having high mechanical strength and flexibility, and a cured product thereof.

[0015] Solutions for solving problems

[0016] The present inventors have discovered that an epoxy resin composition containing an epoxy resin, an epoxy resin curing agent, a solvent, and an aromatic hydrocarbon formaldehyde resin in specific ratios can solve the above-mentioned problems.

[0017] That is, the present invention relates to the following solutions.

[0018] [1] An epoxy resin composition comprising: an epoxy resin (A), an epoxy resin curing agent (B), a solvent (C), and an aromatic hydrocarbon formaldehyde resin (D), wherein the mass ratio of the total content of component (C) and component (D) to the total content of components (B), (C), and (D) [(C+D) / (B+C+D)] is 0.42 to 0.57, and the mass ratio C / D of component (C) to component (D) is 1.00 or more.

[0019] [2] A cured product of the epoxy resin composition described in [1] above.

[0020] Effects of the Invention

[0021] The present invention provides an epoxy resin composition that can be cured at room temperature and can form a cured product having high mechanical strength and flexibility. The epoxy resin composition is suitable for use in coatings, adhesives, flooring materials, concrete structures, and the like. DETAILED DESCRIPTION

[0022] [Epoxy resin composition]

[0023] The epoxy resin composition of the present invention (hereinafter referred to as the "composition of the present invention") comprises: an epoxy resin (A), an epoxy resin curing agent (B), a solvent (C), and an aromatic hydrocarbon formaldehyde resin (D), wherein the mass ratio of the total content of component (C) and component (D) to the total content of components (B), (C), and (D) [(C+D) / (B+C+D)] is 0.42 to 0.57, and the mass ratio C / D of component (C) to component (D) is 1.00 or greater.

[0024] The composition of the present invention, having the above-mentioned structure, can be cured at room temperature (hereinafter referred to as "room temperature curable"), and can form a cured product having high mechanical strength and flexibility. The reason for this is not clear, but is considered as follows.

[0025] In existing epoxy resin compositions with room temperature curing properties, it is difficult to balance the mechanical strength and flexibility of the cured product. In this regard, it can be considered that the epoxy resin composition of the present invention contains, in addition to the epoxy resin (A) and the epoxy resin curing agent (B), a specific ratio of component (C) and component (D), thereby allowing the component (C) and component (D) in the cured product of the epoxy resin composition that cures at room temperature to act as plasticizers, and without excessively reducing the Tg of the cured product, the cured product obtained can balance mechanical strength and flexibility. Specifically, it can be considered that if the mass ratio [(C+D) / (B+C+D)] is in the range of 0.42 to 0.57, flexibility is easily exhibited, and if the mass ratio C / D is 1.00 or more, the reduction in the mechanical strength of the cured product can be suppressed, and thus a cured product with high mechanical strength and flexibility can be formed.

[0026] In this specification, the "room temperature-curable epoxy resin composition" refers to an epoxy resin composition that is cured at room temperature, preferably 5 to 45°C, without intentionally heating.

[0027] In the present invention, the mechanical strength of the cured epoxy resin composition is evaluated by tensile strength and flexural strength, and the flexibility is evaluated by displacement at break. The tensile strength, flexural strength, and displacement at break of the cured epoxy resin composition can be measured using the methods described in the Examples.

[0028] The components used in the composition of the present invention are described below.

[0029] Epoxy resin (A)

[0030] The epoxy resin (A) (hereinafter also referred to as "component (A)") is not particularly limited as long as it has two or more glycidyl groups reactive with the active hydrogen in the epoxy resin curing agent (B) described below. It may be any of saturated or unsaturated aliphatic compounds, alicyclic compounds, aromatic compounds, and heterocyclic compounds. From the perspective of forming a cured product with high mechanical strength and flexibility, the epoxy resin (A) is preferably one containing an aromatic ring or alicyclic structure in its molecule.

[0031] Specific examples of the epoxy resin include at least one resin selected from the group consisting of epoxy resins having glycidylamino groups derived from m-xylylenediamine, epoxy resins having glycidylamino groups derived from p-xylylenediamine, epoxy resins having glycidylamino groups derived from 1,3-bis(aminomethyl)cyclohexane, epoxy resins having glycidylamino groups derived from 1,4-bis(aminomethyl)cyclohexane, epoxy resins having glycidylamino groups derived from diaminodiphenylmethane, epoxy resins having glycidylamino groups and / or glycidyloxy groups derived from p-aminophenol, epoxy resins having glycidyloxy groups derived from bisphenol A, epoxy resins having glycidyloxy groups derived from bisphenol F, epoxy resins having glycidyloxy groups derived from phenol novolac, and epoxy resins having glycidyloxy groups derived from resorcinol. Two or more of these epoxy resins may be used in combination.

[0032] Among the above, from the viewpoint of improving room temperature curability and forming a cured product with high mechanical strength and flexibility, the epoxy resin preferably contains as the main component at least one selected from the group consisting of an epoxy resin having a glycidyl amino group derived from m-xylylenediamine, an epoxy resin having a glycidyl amino group derived from p-xylylenediamine, an epoxy resin having a glycidyloxy group derived from bisphenol A, and an epoxy resin having a glycidyloxy group derived from bisphenol F. From the viewpoint of forming a cured product with high mechanical strength and flexibility, and from the viewpoint of availability and economic efficiency, it is more preferable to use as the main component an epoxy resin having a glycidyloxy group derived from bisphenol A.

[0033] It should be noted that the "main component" herein means that other components may be contained within the scope of the present invention, and preferably accounts for 50 to 100 mass %, more preferably 70 to 100 mass %, and even more preferably 90 to 100 mass % of the total.

[0034] From the perspective of improving workability, the epoxy resin (A) may contain, in addition to the above-mentioned epoxy resin as a main component, a reactive diluent. Examples of the reactive diluent include low molecular weight compounds having at least one epoxy group, such as aromatic monoglycidyl ethers such as phenyl glycidyl ether and cresyl glycidyl ether; alkyl monoglycidyl ethers such as butyl glycidyl ether, hexyl glycidyl ether, octyl glycidyl ether, decyl glycidyl ether, lauryl glycidyl ether, and tetradecyl glycidyl ether; and diglycidyl ethers of aliphatic diols such as 1,3-propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diglycidyl ether.

[0035] The reactive diluents may be used alone or in combination of two or more.

[0036] From the viewpoint of forming a cured product having high mechanical strength and flexibility, the epoxy equivalent of the epoxy resin (A) is preferably 80 g / equivalent or more, more preferably 100 g / equivalent or more, even more preferably 120 g / equivalent or more, and even more preferably 150 g / equivalent or more. From the viewpoint of improving the handleability of the resulting epoxy resin composition and enhancing room temperature curing properties, the epoxy equivalent is preferably 1,000 g / equivalent or less, more preferably 800 g / equivalent or less, even more preferably 500 g / equivalent or less, and even more preferably 300 g / equivalent or less.

[0037] <Epoxy resin curing agent (B)>

[0038] The epoxy resin curing agent (B) used in the present invention (hereinafter also referred to as "curing agent (B)" or "component (B)") includes amine curing agents, acid anhydride curing agents, phenolic curing agents, etc., and one or more of these can be used. Among them, from the viewpoint of having rapid curing properties and excellent room temperature curing properties, the epoxy resin curing agent (B) preferably contains at least an amine curing agent. From the viewpoint of improving room temperature curing properties, the content of the amine curing agent in the epoxy resin curing agent (B) is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and is 100% by mass or less.

[0039] The amine curing agent is not particularly limited as long as it is a compound having at least two amino groups in the molecule. Examples thereof include polyamine compounds having at least two amino groups in the molecule and modified products thereof.

[0040] Examples of the polyamine compound include: chain aliphatic polyamine compounds such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, 2-methylpentamethylenediamine, and trimethylhexamethylenediamine; aromatic ring-containing aliphatic polyamine compounds such as o-xylylenediamine, m-xylylenediamine (MXDA), and p-xylylenediamine (PXDA); isophoronediamine (IPDA), menthenediamine, norbornanediamine, tricyclodecanediamine, adamantanediamine, diaminocyclohexane, 1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,4-diamino-2-methylcyclohexane, Polyamine compounds having an alicyclic structure, such as 1,4-diamino-3,6-diethylcyclohexane, diaminodiethylmethylcyclohexane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (bis(4-amino-3-methylcyclohexyl)methane), 3,3',5,5'-tetramethyl-4,4'-diaminodicyclohexylmethane, and 4,4'-diaminodicyclohexylmethane; aromatic polyamine compounds, such as phenylenediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, diethyltoluenediamine, and 2,2'-diethyl-4,4'-methylenedianiline; polyamine compounds having a heterocyclic structure, such as N-aminoethylpiperazine and N,N'-bis(aminoethyl)piperazine; polyether polyamine compounds, etc.

[0041] Examples of modified polyamine compounds include Mannich-modified products, epoxy-modified products, Michael adducts, Michael adduct-polycondensates, styrene-modified products, and polyamide-modified products of the above-mentioned compounds. These may be used alone or in combination of two or more.

[0042] Among the above, from the viewpoint of improving room temperature curing properties and forming a cured product with high mechanical strength and flexibility, the epoxy resin curing agent (B) is preferably a modified product of a polyamine compound, more preferably an epoxy modified product of a polyamine compound, and still more preferably a reaction composition comprising a reaction product of a polyamine compound represented by the following formula (1) and an epoxy compound having at least one epoxy group.

[0043] H2N-CH2-A-CH2-NH2(1)

[0044] (In formula (1), A is a phenylene group or a cyclohexylene group.)

[0045] A reaction composition comprising a reactant between a polyamine compound and an epoxy compound having at least one epoxy group refers to a product obtained by reacting the polyamine compound with the epoxy compound, and refers to a composition containing, in addition to the reactant (adduct) between the polyamine compound and the epoxy compound, byproducts other than the reactant, unreacted raw materials, and the like. Hereinafter, this reaction composition is also referred to simply as the "above-mentioned reaction composition."

[0046] In formula (1), A is phenylene or cyclohexylene, preferably phenylene. Specifically, A is selected from at least one of the group consisting of 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 1,2-cyclohexylene, 1,3-cyclohexylene, and 1,4-cyclohexylene. From the viewpoint of forming a cured product with high mechanical strength, A is preferably selected from one or more of the group consisting of 1,2-phenylene, 1,3-phenylene, and 1,4-phenylene, more preferably 1,3-phenylene. It should be noted that the cyclohexylene in this specification includes any of cis-isomers and trans-isomers.

[0047] Specific examples of the polyamine compound represented by formula (1) include o-xylylenediamine, m-xylylenediamine (MXDA), p-xylylenediamine (PXDA), 1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, and 1,4-bis(aminomethyl)cyclohexane. Among these, at least one selected from the group consisting of o-xylylenediamine, m-xylylenediamine, and p-xylylenediamine is preferred, and m-xylylenediamine is more preferred.

[0048] The epoxy compound used in the reaction composition may be a compound having at least one epoxy group, and more preferably a compound having two or more epoxy groups.

[0049] Specific examples of the epoxy compound include epichlorohydrin, butyl diglycidyl ether, neopentyl glycol diglycidyl ether, 1,3-propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, biphenol diglycidyl ether, dihydroxynaphthyl diglycidyl ether, dihydroxyanthryl diglycidyl ether, triglycidyl isocyanurate, tetraglycidyl glycoluril, and a polyfunctional epoxy compound having a glycidyl amino group derived from m-xylylenediamine. Epoxy resins, polyfunctional epoxy resins having glycidylamino groups derived from 1,3-bis(aminomethyl)cyclohexane, polyfunctional epoxy resins having glycidylamino groups derived from diaminodiphenylmethane, polyfunctional epoxy resins having glycidylamino groups and / or glycidyloxy groups derived from p-aminophenol, polyfunctional epoxy resins having glycidyloxy groups derived from bisphenol A, polyfunctional epoxy resins having glycidyloxy groups derived from bisphenol F, polyfunctional epoxy resins having glycidyloxy groups derived from phenol novolac, and polyfunctional epoxy resins having two or more glycidyloxy groups derived from resorcinol, etc. These may be used alone or in combination of two or more.

[0050] From the viewpoint of forming a cured product with high mechanical strength and from the viewpoint of curability, the epoxy compound is preferably a compound containing an aromatic ring or an alicyclic structure in the molecule, more preferably a compound containing an aromatic ring in the molecule, and even more preferably a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A.

[0051] The reaction composition can be obtained by a ring-opening addition reaction between a polyamine compound and an epoxy compound using known methods. For example, the polyamine compound is placed in a reactor, and the epoxy compound is added thereto all at once or in portions, such as by dropwise addition, followed by heating to allow the reaction to proceed. This addition reaction is preferably carried out under an inert atmosphere such as nitrogen.

[0052] The amount of the polyamine compound and the epoxy compound used is not particularly limited as long as the ratio is such that the obtained reactant contains an amino group having active hydrogen. From the viewpoint of the obtained reactant functioning as an epoxy resin curing agent, it is preferred to use an excess of the polyamine compound relative to the epoxy equivalent of the epoxy compound in the addition reaction. Specifically, the polyamine compound and the epoxy compound are used in such a manner that the number of active hydrogens in the polyamine compound relative to the number of epoxy groups in the epoxy compound (the number of active hydrogens in the polyamine compound / the number of epoxy groups in the epoxy compound) is preferably 50 / 1 to 4 / 1, more preferably 20 / 1 to 4 / 1.

[0053] The temperature and reaction time during the addition reaction can be appropriately selected. From the viewpoints of reaction rate, productivity, and prevention of raw material decomposition, the temperature during the addition reaction is preferably 25 to 150° C., more preferably 40 to 120° C. The reaction time, calculated from the completion of the addition of the epoxy compound, is preferably 0.5 to 12 hours, more preferably 1 to 6 hours.

[0054] From the viewpoint of forming a cured product having high mechanical strength and flexibility, the content of the reaction composition in the epoxy resin curing agent (B) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, still more preferably 90% by mass or more, and is 100% by mass or less.

[0055] From the viewpoint of exhibiting high curability even with a small amount of epoxy resin composition, the active hydrogen equivalent weight (AHEW) of the epoxy resin curing agent (B) is preferably 150 or less, more preferably 120 or less, and even more preferably 110 or less. On the other hand, from the viewpoint of forming a cured product having high mechanical strength and flexibility, the AHEW of the curing agent is preferably 35 or more, more preferably 50 or more.

[0056] Solvent (C)

[0057] Examples of the solvent (C) (hereinafter referred to as "component (C)") include alcohol solvents, alkylene glycol solvents, ester solvents, ketone solvents, ether solvents, and hydrocarbon solvents.

[0058] Examples of the alcohol solvent include aliphatic monohydric alcohols having 1 to 10 carbon atoms, such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, pentanol, hexanol, cyclohexanol, octanol, 2-ethylhexanol, and decanol; monohydric alcohols containing an aromatic ring, such as benzyl alcohol; and monohydric alcohols containing a heterocyclic ring, such as furfuryl alcohol and tetrahydrofurfuryl alcohol.

[0059] Examples of the alkylene glycol solvent include ethylene glycol, diethylene glycol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether [2-(2-methoxyethoxy)ethanol], triethylene glycol monomethyl ether [2-{2-(2-methoxyethoxy)ethoxy}ethanol], ethylene glycol monoethyl ether, diethylene glycol monoethyl ether [2-(2-ethoxyethoxy)ethanol], ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, and triethylene glycol monoisopropyl ether. Butyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, triethylene glycol monoisobutyl ether, ethylene glycol phenyl ether [phenoxyethanol], diethylene glycol phenyl ether, triethylene glycol phenyl ether, propylene glycol, dipropylene glycol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, propylene glycol monoisopropyl ether, dipropylene glycol monoisopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, propylene glycol monoisobutyl ether, dipropylene glycol monoisobutyl ether, propylene glycol phenyl ether, dipropylene glycol phenyl ether, etc.

[0060] Examples of the ester solvent include ethyl acetate and butyl acetate, and examples of the ketone solvent include acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0061] Examples of the ether solvent include diethyl ether, diisopropyl ether, and tetrahydrofuran. Examples of the hydrocarbon solvent include hydrocarbon compounds having 6 to 12 carbon atoms, such as toluene, xylene, isooctane, and isododecane.

[0062] Among the above, from the viewpoint of solubility of the epoxy resin (A), the epoxy resin curing agent (B), and the aromatic hydrocarbon formaldehyde resin (D), the solvent (C) is preferably at least one selected from the group consisting of alcohol solvents, alkylene glycol solvents, ester solvents, and hydrocarbon solvents, and more preferably at least one selected from the group consisting of alcohol solvents and alkylene glycol solvents.

[0063] Furthermore, from the viewpoint of forming a cured product having a higher 5% weight loss temperature, the boiling point of the solvent (C) at 1 atm is preferably 140°C or higher, more preferably 200°C or higher.

[0064] Among the above, from the viewpoint of forming a cured product having flexibility and a higher 5% weight loss temperature, the solvent (C) more preferably contains at least one selected from the group consisting of benzyl alcohol, dipropylene glycol monobutyl ether, and propylene glycol phenyl ether, and even more preferably contains benzyl alcohol.

[0065] From the viewpoint of forming a flexible cured product having a higher 5% weight loss temperature, the total content of benzyl alcohol, dipropylene glycol monobutyl ether, and propylene glycol phenyl ether in the solvent (C) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, still more preferably 90% by mass or more, and is 100% by mass or less.

[0066] Furthermore, from the viewpoint of forming a cured product having flexibility and a higher 5% weight loss temperature, the content of benzyl alcohol in the solvent (C) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, yet more preferably 90% by mass or more, and is 100% by mass or less.

[0067] <Aromatic hydrocarbon formaldehyde resin (D)>

[0068] The aromatic hydrocarbon formaldehyde resin (D) (hereinafter, also simply referred to as "resin (D)" or "component (D)") is a resin obtained by reacting an aromatic hydrocarbon with formaldehyde.

[0069] Examples of the aromatic hydrocarbon include at least one selected from the group consisting of benzene, toluene, xylene, mesitylene, unimolecular trimethylolbenzene, ethylbenzene, propylbenzene, decylbenzene, cyclohexylbenzene, biphenyl, methylbiphenyl, naphthalene, methylnaphthalene, dimethylnaphthalene, ethylnaphthalene, anthracene, methylanthracene, dimethylanthracene, ethylanthracene, and binaphthyl. Among these, from the perspective of forming a cured product having high mechanical strength and flexibility, the aromatic hydrocarbon constituting the aromatic hydrocarbon formaldehyde resin (D) is preferably at least one selected from the group consisting of toluene, xylene, mesitylene, and unimolecular trimethylolbenzene, and more preferably xylene. That is, the aromatic hydrocarbon formaldehyde resin (D) is preferably selected from at least one of toluene formaldehyde resin obtained by reacting toluene with formaldehyde, xylene formaldehyde resin obtained by reacting xylene with formaldehyde, mesitylene formaldehyde resin obtained by reacting mesitylene with formaldehyde, and unimolecular trimethylolbenzene formaldehyde resin obtained by reacting unimolecular trimethylolbenzene with formaldehyde, and more preferably includes xylene formaldehyde resin.

[0070] From the viewpoint of forming a cured product having high mechanical strength and flexibility, the content of the xylene formaldehyde resin in the aromatic hydrocarbon formaldehyde resin (D) is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, still further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and is 100% by mass or less.

[0071] From the viewpoint of forming a cured product having high mechanical strength and flexibility, the viscosity of the aromatic hydrocarbon formaldehyde resin (D) at 25°C is preferably 30 mPa·s or more, more preferably 50 mPa·s or more, further preferably 100 mPa·s or more, further preferably 200 mPa·s or more, and even more preferably 250 mPa·s or more. The upper limit of the viscosity is not particularly limited. However, from the viewpoint of forming a cured product having high mechanical strength and flexibility, maintaining good compatibility with the epoxy resin (A), and handling properties, it is preferably 30,000 mPa·s or less, more preferably 20,000 mPa·s or less, further preferably 15,000 mPa·s or less, still further preferably 10,000 mPa·s or less, still further preferably 8,000 mPa·s or less, still further preferably 5,000 mPa·s or less, still further preferably 2,000 mPa·s or less, still further preferably 1,000 mPa·s or less, still further preferably 800 mPa·s or less, and still further preferably 500 mPa·s or less.

[0072] The viscosity can be measured at 25° C. using an E-type viscometer, and specifically, can be measured by the method described in Examples.

[0073] From the perspective of forming a cured product with high mechanical strength and flexibility, the hydroxyl equivalent weight (g / equivalent) of the aromatic hydrocarbon formaldehyde resin (D) is preferably 200 to 5,000 g / equivalent, more preferably 500 to 4,000 g / equivalent, even more preferably 1,000 to 3,500 g / equivalent, and even more preferably 1,500 to 3,000 g / equivalent. The hydroxyl equivalent weight is determined by measuring the hydroxyl value by the method described in JIS K0070-1992 and converting the resulting hydroxyl value into a hydroxyl equivalent weight.

[0074] A commercially available aromatic hydrocarbon formaldehyde resin (D) may be used, or the aromatic hydrocarbon formaldehyde resin (D) may be produced by a known method.

[0075] Examples of the method for producing the aromatic hydrocarbon formaldehyde resin (D) include a method described in Japanese Patent Publication No. 37-5747, in which an aromatic hydrocarbon and formaldehyde are subjected to a condensation reaction in the presence of a catalyst.

[0076] Examples of commercially available aromatic hydrocarbon formaldehyde resins (D) include xylene formaldehyde resins such as "Nikanol Y-50," "Nikanol Y-100," "Nikanol Y-300," "Nikanol Y-1000," "Nikanol L," "Nikanol LL," "Nikanol LLL," "Nikanol G," "Nikanol H," and "Nikanol H-80," manufactured by Fudow Co., Ltd.

[0077] <Content>

[0078] The content and content ratio of each component in the epoxy resin composition are preferably in the following ranges.

[0079] From the viewpoint of improving room temperature curability and forming a cured product having high mechanical strength and flexibility, the ratio of the epoxy resin (A) to the epoxy resin curing agent (B) in the epoxy resin composition is such that the ratio of the number of active hydrogen atoms in the epoxy resin curing agent (B) to the number of epoxy groups in the epoxy resin (A) [number of active hydrogen atoms / number of epoxy groups] is preferably 1 / 0.8 to 1 / 1.2, more preferably 1 / 0.9 to 1 / 1.1, and even more preferably 1 / 1.

[0080] From the viewpoint of improving room temperature curability and forming a cured product having high mechanical strength and flexibility, the content of the epoxy resin (A) in the epoxy resin composition is preferably 20 to 80 mass %, more preferably 30 to 70 mass %, and even more preferably 40 to 65 mass %.

[0081] From the viewpoint of room temperature curing properties and the formation of a cured product having high mechanical strength and flexibility, the content of the epoxy resin curing agent (B) in the epoxy resin composition is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass.

[0082] From the viewpoint of forming a cured product having high mechanical strength and flexibility, in the epoxy resin composition, the mass ratio of the total content of component (C) and component (D) to the total content of components (B), (C), and (D) [(C+D) / (B+C+D)] is 0.42 to 0.57, preferably 0.45 to 0.55, and more preferably 0.47 to 0.53.

[0083] From the viewpoint of forming a cured product having high mechanical strength and flexibility, in the epoxy resin composition, the mass ratio C / D of component (C) to component (D) is 1.00 or more, preferably 1.00 to 3.50, more preferably 1.20 to 3.30, even more preferably 1.20 to 3.00, still more preferably 1.20 to 2.70, still more preferably 1.20 to 2.50, and still more preferably 1.30 to 2.20.

[0084] The content of the solvent (C) in the epoxy resin composition may satisfy the ranges of the mass ratio [(C+D) / (B+C+D)] and the mass ratio C / D. From the viewpoint of forming a cured product having high mechanical strength and flexibility, the content of the solvent (C) in the epoxy resin composition is preferably 1 to 30% by mass, more preferably 2 to 20% by mass, further preferably 3 to 20% by mass, further preferably 5 to 20% by mass, and further preferably 7 to 15% by mass.

[0085] The content of the aromatic hydrocarbon formaldehyde resin (D) in the epoxy resin composition may satisfy the ranges of the mass ratio [(C+D) / (B+C+D)] and the mass ratio C / D described above. However, from the viewpoint of forming a cured product having high mechanical strength and flexibility, the content is preferably 1 to 25% by mass, more preferably 2 to 20% by mass, further preferably 3 to 15% by mass, further preferably 3 to 12% by mass, and further preferably 4 to 10% by mass in the epoxy resin composition.

[0086] The epoxy resin composition of the present invention may further contain other components such as known curing accelerators, fillers, and plasticizers, flow control components such as thixotropic agents, pigments, leveling agents, and tackifiers, as long as the effects of the present invention are not impaired.

[0087] However, from the perspective of improving room temperature curability and forming a cured product with high mechanical strength and flexibility, the epoxy resin composition of the present invention preferably has a low pigment content. The pigment content in the epoxy resin composition is preferably less than 5% by mass, more preferably less than 2% by mass, further preferably less than 1% by mass, further preferably less than 0.1% by mass, and further preferably 0% by mass.

[0088] The epoxy resin composition of the present invention is preferably a non-aqueous epoxy resin composition, preferably having a low water content. The water content in the epoxy resin composition is preferably less than 10% by mass, more preferably less than 5% by mass, even more preferably less than 2% by mass, even more preferably less than 1% by mass, even more preferably less than 0.1% by mass, and even more preferably 0% by mass. The water content herein refers to the amount of water intentionally added to the epoxy resin composition, and does not exclude the presence of small amounts of water as impurities.

[0089] The total content of the epoxy resin (A), epoxy resin curing agent (B), solvent (C), and aromatic hydrocarbon formaldehyde resin (D) in the epoxy resin composition is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and is 100% by mass or less.

[0090] <Method for producing epoxy resin composition>

[0091] The epoxy resin composition can be prepared by mixing components (A) to (D) and, if necessary, other components using any known methods and apparatus. The order of mixing the components in the epoxy resin composition is not particularly limited; however, from the perspective of improving workability, it is preferred to prepare a solution in which the epoxy resin curing agent (B) is dissolved in the solvent (C) and then mix this solution with components (A) and (D).

[0092] The temperature and time for mixing the components of the epoxy resin composition can be adjusted appropriately. From the perspective of suppressing viscosity increases, the mixing temperature is preferably 80°C or lower, more preferably 50°C or lower. From the perspective of epoxy resin miscibility, the mixing temperature is preferably 15°C or higher, more preferably 20°C or higher. The mixing time is preferably 0.1 to 20 minutes, more preferably 1 to 10 minutes.

[0093] [cured material]

[0094] The cured product of the epoxy resin composition of the present invention is obtained by curing the composition of the present invention using a known method. The curing conditions of the epoxy resin composition can be appropriately selected according to the application and form, and are carried out by a known method at a temperature and time that fully cures the epoxy resin composition. For example, in applications requiring room temperature curing properties, the curing conditions of the epoxy resin composition are preferably selected within the range of a curing temperature of 5 to 45°C and a curing time of 1 hour to 10 days. However, as long as the solvent (C) does not volatilize excessively, a curing temperature and curing time outside the above range may also be used. In addition, it is not excluded to perform post-curing of the cured product after room temperature curing using a curing temperature and curing time outside the above range.

[0095] The form of the cured product is not particularly limited and can be selected according to the intended use. For example, when the epoxy resin composition is used for various coating applications, the cured product is generally a film-shaped cured product.

[0096] <Application>

[0097] The epoxy resin composition of the present invention is room-temperature curable and can form a cured product with high mechanical strength and flexibility. Therefore, it can be used in coatings, adhesives, flooring materials, sealants, polymer cement mortars, gas barrier coatings, primers, screeds, surface coatings, sealing materials, concrete structures, crack repair materials, road paving materials, etc., and is particularly suitable for coatings, adhesives, flooring materials, concrete structures, etc.

[0098] [Example]

[0099] The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, various measurements and evaluations in the Examples were performed by the following methods.

[0100] (Viscosity measurement)

[0101] The viscosity of the component (D) at 25° C. was measured using an E-type viscometer “TVE-22H Cone-Plate Viscometer” (manufactured by Toki Sangyo Co., Ltd.).

[0102] (Determination of tensile strength, flexural strength, and breaking point displacement)

[0103] The epoxy resin composition obtained in each example was poured between two aluminum plates and cured at 23°C and 50% RH for 7 days. The cured epoxy resin composition was then heated at 80°C for 1 hour to obtain a 4 mm thick cured product. The product was then cut using a cutting machine into test pieces conforming to the following JIS standards. The tensile strength, flexural strength, and displacement at break were measured using an Autograph (manufactured by Shimadzu Corporation) under the following conditions. Larger values ​​indicate better results.

[0104] Tensile strength: The tensile strength was measured by a tensile test at a temperature of 23° C. and a test speed of 5 mm / min in accordance with JIS K7161-1: 2014 and JIS K7161-2: 2014.

[0105] Bending strength and breaking point displacement: A bending test was conducted at 23°C in accordance with JIS K7171:2016 to measure the bending strength and breaking point displacement.

[0106] (Glass transition temperature (Tg) measurement)

[0107] Approximately 5 mg of the epoxy resin composition obtained in each example was cured at 23°C and 50% RH for 7 days. The cured product was heated from -10°C to 100°C at a heating rate of 1°C / min using a differential scanning calorimeter ("DSC25" manufactured by TA Instruments) to determine its Tg.

[0108] (5% weight loss temperature determination)

[0109] Approximately 15 mg of the epoxy resin composition obtained in each example was cured for 7 days at 23°C and 50% RH. The cured product was heated from 25°C to 300°C using a thermogravimetric analyzer ("TG / DTA6200" manufactured by Seiko Instruments Inc.) at a nitrogen flow rate of 50 mL / min and a heating rate of 10°C / min. The temperature at which the weight decreased by 5% by mass was defined as the 5% weight loss temperature.

[0110] Production Example 1 (Production of a Reaction Composition (MXDA-jER828 Reaction Composition) Solution Containing a Reaction Product of Meta-Xylylenediamine and an Epoxy Compound)

[0111] A 1-liter separable flask equipped with a stirrer, thermometer, nitrogen inlet tube, dropping funnel, and condenser was charged with 179 g of m-xylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.). Under a nitrogen stream, 121 g of a polyfunctional epoxy resin ("jER828," manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent) derived from bisphenol A and containing glycidyl groups was added dropwise over 2 hours while stirring under a nitrogen stream (the number of active hydrogen atoms in m-xylylenediamine / the number of epoxy groups in the epoxy compound = 8 / 1). After the addition was complete, the mixture was heated to 80°C and reacted for 2 hours to obtain an MXDA-jER828 reaction composition. Benzyl alcohol, the solvent (C), was added to the mixture in an amount of 40% by mass of the total weight to dilute the mixture, yielding a reaction composition solution having a concentration of 60% by mass of the reaction composition. The active hydrogen equivalent weight (AHEW) of the reaction composition solution (including the total amount of benzyl alcohol) was 109.8.

[0112] Example 1 (Preparation and Evaluation of Epoxy Resin Composition)

[0113] A liquid epoxy resin containing a glycidyl group derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 186 g / equivalent) was used as the epoxy resin (A), and the MXDA-jER828 reaction composition solution obtained in Production Example 1 was used as a mixture of the epoxy resin curing agent (B) and the solvent (C). Furthermore, a xylene formaldehyde resin ("Nikanol Y-300" manufactured by Fudow Corporation) was used as the component (D).

[0114] The above components (A) to (D) were blended in the amounts shown in Table 1, stirred and mixed at 23°C to prepare an epoxy resin composition. The ratio of the number of active hydrogen atoms in the epoxy resin curing agent (B) to the number of epoxy groups in the epoxy resin (A) (number of active hydrogen atoms in the epoxy resin curing agent (B) / number of epoxy groups in the epoxy resin (A)) was set to 1 / 1.

[0115] The epoxy resin compositions thus obtained were subjected to various evaluations according to the aforementioned methods. The results are shown in Table 1.

[0116] Examples 2 to 4, Comparative Examples 1 to 4

[0117] Epoxy resin compositions were prepared and evaluated in the same manner as in Example 1, except that the components and amounts in the epoxy resin compositions were changed as shown in Table 1. The results are shown in Table 1. Note that the amounts listed in Table 1 are all amounts of active ingredients.

[0118] [Table 1]

[0119]

[0120] The components described in Table 1 are as follows.

[0121] Epoxy resin (A)

[0122] *1jER828: Bisphenol A-derived liquid epoxy resin with a glycidyl group, manufactured by Mitsubishi Chemical Corporation, “jER828”, epoxy equivalent: 186 g / equivalent

[0123] <Epoxy resin curing agent (B)>

[0124] *2MXDA-jER828 reaction composition: the reaction composition obtained in Preparation Example 1 (excluding the amount of benzyl alcohol)

[0125] <Aromatic hydrocarbon formaldehyde resin (D)>

[0126] *3Y-300: Xylene formaldehyde resin, "Nikanol Y-300" manufactured by Fudow Co., Ltd., viscosity at 25°C: 285 mPa·s, hydroxyl equivalent: 2,805 g / equivalent (hydroxyl value: 20 mgKOH / g)

[0127] *4Y-100: Xylene formaldehyde resin, "Nikanol Y-100" manufactured by Fudow Co., Ltd., viscosity at 25°C: 109 mPa·s, hydroxyl equivalent: 2,244 g / equivalent (hydroxyl value: 25 mgKOH / g)

[0128] *5Y-50: Xylene formaldehyde resin, "Nikanol Y-50" manufactured by Fudow Co., Ltd., viscosity at 25°C: 50 mPa·s, hydroxyl equivalent: 2,805 g / equivalent (hydroxyl value: 20 mgKOH / g)

[0129] As shown in Table 1, the epoxy resin composition of this example can be cured at 23° C., and its cured product has a tensile strength of 30 MPa or more and a flexural strength of 50 MPa or more, indicating high mechanical strength and good flexibility.

[0130] Comparison between Example 1 and Example 3 shows that when the solvent (C) is benzyl alcohol, the 5% weight loss temperature is higher than that in the case of propylene glycol phenyl ether, and the heat resistance is more excellent.

[0131] In contrast, the cured products of the epoxy resin compositions of Comparative Examples 1 to 3 had poor mechanical strength and flexibility. Note that the components of the epoxy resin composition of Comparative Example 4 were incompatible, and evaluation was not possible.

[0132] Industrial applicability

[0133] The present invention provides an epoxy resin composition that can be cured at room temperature and can form a cured product having high mechanical strength and flexibility. The epoxy resin composition is suitable for use in coatings, flooring materials, concrete structures, adhesives, and the like.

Claims

1. An epoxy resin composition comprising: Epoxy resin (A), epoxy resin curing agent (B), solvent (C), and aromatic hydrocarbon formaldehyde resin (D), The epoxy resin (A) comprises an epoxy resin containing an aromatic ring or an alicyclic structure in the molecule, The epoxy resin curing agent (B) is a reaction composition containing a reactant of a polyamine compound represented by the following formula (1) and an epoxy compound having at least one epoxy group: H2N-CH2-A-CH2-NH2(1) In formula (1), A is phenylene or cyclohexylene, The content of the epoxy resin (A) in the epoxy resin composition is 20 to 80% by mass. The content of the epoxy resin curing agent (B) in the epoxy resin composition is 5 to 50% by mass. The mass ratio of the total content of components (C) and (D) to the total content of components (B), (C), and (D) [(C+D) / (B+C+D)] is 0.42 to 0.57, and the mass ratio C / D of component (C) to component (D) is 1.00 to 3.

50.

2. The epoxy resin composition according to claim 1, wherein The solvent (C) includes at least one selected from the group consisting of benzyl alcohol, dipropylene glycol monobutyl ether, and propylene glycol phenyl ether.

3. The epoxy resin composition according to claim 1 or 2, wherein The aromatic hydrocarbon formaldehyde resin (D) has a viscosity of 100 mPa·s or more at 25°C.

4. The epoxy resin composition according to claim 1 or 2, wherein The aromatic hydrocarbon constituting the aromatic hydrocarbon formaldehyde resin (D) is at least one selected from the group consisting of toluene, xylene, mesitylene, and trimethylolbenzene. A cured product, which is a cured product of the epoxy resin composition according to claim 1 or 2.

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