Epoxy resin curing agent, epoxy resin composition, and cured product thereof

Abstract

Provided are: an epoxy resin curing agent containing a reaction composition (A1) containing a reaction product of xylylenediamine and an alkylene oxide, and an amine compound (A2) other than the reaction composition (A1); an epoxy resin composition; and a cured product thereof.

Description

Epoxy resin curing agent, epoxy resin composition and cured product thereof

[0001] The present invention relates to an epoxy resin curing agent, an epoxy resin composition, and a cured product thereof.

[0002] Various polyamine compounds are widely known as epoxy resin curing agents. Epoxy resin compositions using polyamine compounds as epoxy resin curing agents are used in the coating field, such as anticorrosion coatings for ships, bridges, and land and sea steel structures, as well as in the civil engineering and construction field, such as linings, reinforcement, and repair materials for concrete structures, flooring materials for buildings, linings for water supply and sewerage systems, paving materials, and adhesives. Epoxy resin compositions used in the above fields are usually cured at the ambient temperature of use, and are therefore required to be fast-curing.

[0003] Polyamine compounds are known to have faster curing properties than other epoxy resin curing agent components such as phenolic compounds and boron complexes. However, there are also polyamine compounds, such as isophorone diamine, that have a relatively slow curing rate when used as an epoxy resin curing agent. For example, Patent Document 1 discloses an epoxy resin curing agent containing at least one compound (A) selected from the group consisting of N-aminoethylpiperazine and isophorone diamine, and norbornane diamine (B), and describes that this can improve the problems of slow curing rate and high initial viscosity inherent to isophorone diamine.

[0004] International Publication No. 2020 / 246144

[0005] The technology disclosed in Patent Document 1 relates to an epoxy resin curing agent and an epoxy resin composition used in molding by a high-cycle RTM method or the like, and is usually cured under heated conditions. On the other hand, the technology disclosed in Patent Document 1 leaves room for further improvement in terms of improving the curing speed as an epoxy resin curing agent and an epoxy resin composition that are cured at ambient temperatures such as room temperature. An object of the present invention is to provide an epoxy resin curing agent, an epoxy resin composition, and a cured product thereof that are fast-curing while containing an amine compound conventionally used as an epoxy resin curing agent, particularly an amine compound with a relatively slow curing speed.

[0006] The present inventors have found that an epoxy resin curing agent containing a predetermined reaction composition and another amine compound can solve the above-mentioned problems. Specifically, the present invention relates to the following: [1] An epoxy resin curing agent containing a reaction composition (A1) containing a reaction product of xylylenediamine and alkylene oxide, and an amine compound (A2) other than the reaction composition (A1). [2] The epoxy resin curing agent according to [1], wherein the amine compound (A2) comprises an amine compound (a2) having an amino group bonded to a secondary or tertiary carbon, or a modified product thereof. [3] The epoxy resin curing agent according to [2], wherein the amine compound (a2) comprises at least one selected from the group consisting of a linear polyether polyamine, a polyamine compound having an alicyclic structure, and a polyamine compound having an aromatic ring structure. [4] The epoxy resin curing agent according to [2] or [3], wherein the modified product of the amine compound (a2) comprises at least one selected from the group consisting of the following (i) to (iv): (i) a reaction composition comprising a reaction product of the amine compound (a2) and an epoxy compound having at least one epoxy group; (ii) a reaction composition comprising a Michael addition reaction product of the amine compound (a2) and at least one selected from the group consisting of an unsaturated hydrocarbon compound, an unsaturated carboxylic acid or a derivative thereof, and an unsaturated nitrile compound; (iii) a reaction composition comprising a polycondensation reaction product of the amine compound (a2) and a polymerized fatty acid; or (iv) a Mannich reaction product obtained by reacting the amine compound (a2) with a phenol compound and an aldehyde compound. [5] The epoxy resin curing agent according to any one of [1] to [4], wherein the mass ratio [(A1) / {(A1)+(A2)}] of the reaction composition (A1) to the total mass of the reaction composition (A1) and the amine compound (A2) is greater than 0 and 0.80 or less. [6] The epoxy resin curing agent according to any one of [1] to [5], wherein the content of the reaction composition (A1) in the epoxy resin curing agent is less than 50 mass% of all curing agent components. [7] The epoxy resin curing agent according to any one of [1] to [6], wherein the alkylene oxide in the reaction composition (A1) comprises ethylene oxide.[8] The epoxy resin curing agent according to any one of [1] to [7], wherein the reaction composition (A1) is a composition obtained by reacting xylylenediamine with an alkylene oxide in a molar ratio of 1 / 0.2 to 1 / 4. [9] An epoxy resin composition containing an epoxy resin and the epoxy resin curing agent according to any one of [1] to [8].

[10] The epoxy resin composition according to [9], further containing a non-reactive diluent.

[11] The epoxy resin composition according to

[10] , wherein the content of the non-reactive diluent in the epoxy resin composition is 1 to 60 mass%.

[12] A cured product of the epoxy resin composition according to any one of [9] to

[11] .

[0007] According to the present invention, it is possible to provide a fast-curing epoxy resin curing agent, an epoxy resin composition, and a cured product thereof, which contain an amine compound conventionally used as an epoxy resin curing agent, particularly an amine compound having a relatively slow curing rate.

[0008] [Definition] In this specification, the term "reaction composition containing a reaction product of X and Y" means a composition obtained by reacting X with Y, which contains not only the reaction product of X and Y (addition reaction product) but also by-products other than the reaction product, and unreacted raw materials such as X and Y. In this specification, the fast-curing property of an epoxy resin curing agent is determined using as an index the shortness of the semi-drying time of a coating film formed using an epoxy resin composition containing the epoxy resin curing agent, and specifically can be evaluated by the method described in the examples.

[0009] [Epoxy Resin Curing Agent] The epoxy resin curing agent of the present invention contains a reaction composition (A1) (hereinafter also simply referred to as "reaction composition (A1)") containing a reaction product of xylylenediamine and alkylene oxide, and an amine compound (A2) (hereinafter also simply referred to as "amine compound (A2)") other than the reaction composition (A1). The epoxy resin curing agent has fast curing properties even when it contains an amine compound with a relatively slow curing rate. Hereinafter, the epoxy resin curing agent of the present invention will also be referred to simply as "the curing agent of the present invention."

[0010] The reason why the above effects are achieved by using the epoxy resin curing agent of the present invention is unclear, but it is thought to be as follows. The reaction product of xylylenediamine and alkylene oxide in the reaction composition (A1) is a modified amine compound, but it exhibits little steric hindrance of the active hydrogen. In addition, the hydroxyl groups derived from the alkylene oxide promote the reaction with the epoxy groups in the epoxy resin. Therefore, it is thought that the reaction composition (A1) containing this reaction product exhibits fast curing properties as an epoxy resin curing agent. Furthermore, because the reaction composition (A1) is a modified amine compound, it has a higher molecular weight than general unmodified amine-based curing agents, and is therefore thought to be highly effective in shortening the semi-drying time of the formed coating film. Furthermore, because the reaction composition (A1) has a structure derived from alkylene oxide, it is thought that the inclusion of the reaction composition (A1) in the epoxy resin curing agent of the present invention results in coating films formed using an epoxy resin composition containing the curing agent having excellent flexibility and improved adhesion to substrates.

[0011] <Reaction Composition (A1)> The reaction composition (A1) contains a reaction product of xylylenediamine and alkylene oxide. In this specification, "reaction product of xylylenediamine and alkylene oxide" means an addition reaction product (adduct) of xylylenediamine and alkylene oxide. The reaction product of xylylenediamine and alkylene oxide includes not only an addition reaction product of 1 mole of xylylenediamine and 1 mole of alkylene oxide (1:1 adduct), but also multi-adducts such as a 1:2 adduct and a 1:3 adduct of xylylenediamine and alkylene oxide. Furthermore, "reaction composition (A1) containing a reaction product of xylylenediamine and alkylene oxide" refers to a reaction product obtained by the reaction of xylylenediamine and alkylene oxide, which may contain unreacted raw materials such as xylylenediamine in addition to the adduct.

[0012] Examples of xylylenediamine include orthoxylylenediamine, metaxylylenediamine (MXDA), and paraxylylenediamine (PXDA). Among these, from the viewpoint of fast curing, at least one selected from the group consisting of metaxylylenediamine and paraxylylenediamine is preferred, and metaxylylenediamine is more preferred.

[0013] As the alkylene oxide, from the viewpoint of rapid curing and improving the adhesion of the resulting coating film, an alkylene oxide having 2 to 6 carbon atoms is preferred, an alkylene oxide having 2 to 4 carbon atoms is more preferred, at least one selected from the group consisting of ethylene oxide and propylene oxide is even more preferred, it is even more preferred that it contains ethylene oxide, and it is even more preferred that it is ethylene oxide. One or more alkylene oxides can be used.

[0014] In the reaction composition (A1), the reaction molar ratio of xylylenediamine to alkylene oxide is not particularly limited, as long as the reaction composition (A1) has a sufficient amount of active hydrogen derived from amino groups to function as an epoxy resin curing agent. From the viewpoints of rapid curing and improving the adhesion of the resulting coating film, the reaction composition (A1) is a composition obtained by reacting xylylenediamine with alkylene oxide in a molar ratio (xylylenediamine / alkylene oxide) of preferably 1 / 0.2 to 1 / 4, more preferably 1 / 0.2 to 1 / 3, even more preferably 1 / 0.2 to 1 / 2, still more preferably 1 / 0.5 to 1 / 2, and even more preferably 1 / 0.8 to 1 / 1.2.

[0015] Reaction composition (A1) can be produced by reacting xylylenediamine with alkylene oxide under heated conditions. For example, xylylenediamine is charged into a reaction vessel, and while stirring, alkylene oxide is added by blowing or dropwise addition under heated conditions, preferably at 50 to 150°C, more preferably at 70 to 130°C. After the addition is complete, the reaction is continued for 0.5 to 12 hours while heating. The reaction is preferably carried out under an inert gas atmosphere such as nitrogen gas. After the reaction is complete, the resulting reaction liquid can be used as reaction composition (A1) as is. If necessary, the reaction liquid may be purified to remove unreacted materials before use as reaction composition (A1).

[0016] From the viewpoint of improving the adhesion of the resulting coating film, the active hydrogen equivalent (AHEW) of the reaction composition (A1) is preferably at least 55, more preferably at least 58. From the viewpoint of rapid curing, it is preferably at most 80, more preferably at most 75, and even more preferably at most 70. The active hydrogen equivalent (hereinafter also referred to as "AHEW") of the reaction composition (A1) is the mass per mole of active hydrogen derived from amino groups in the reaction composition (A1), and can be calculated, for example, from the amine value determined by titration.

[0017] <Amine Compound (A2)> The amine compound (A2) is an amine compound other than the reaction composition (A1). From the viewpoint of functioning as an epoxy resin curing agent, the amine compound (A2) is preferably a polyamine compound, i.e., a compound having two or more amino groups. From the viewpoint that the curing agent of the present invention can impart rapid curing properties by the reaction composition (A1) even when it contains an amine compound with a relatively slow curing rate, the amine compound (A2) preferably includes an amine compound (a2) having an amino group bonded to a secondary or tertiary carbon or a modified product thereof, and more preferably includes an amine compound (a2) having an amino group bonded to a secondary carbon or a modified product thereof. Since an amino group bonded to a secondary or tertiary carbon has greater steric hindrance than an amino group bonded to a primary carbon, amine compounds having such an amino group generally have a low curing rate as epoxy resin curing agents. However, in the curing agent of the present invention, the curing property improvement effect of the reaction composition (A1) can be obtained even when the amine compound (A2) includes an amine compound having an amino group bonded to a secondary or tertiary carbon or a modified product thereof. In this specification, the term "amino group bonded to a secondary or tertiary carbon" includes an amino group bonded directly to an aromatic ring.

[0018] (Amine Compound (a2)) The amine compound (a2) having an amino group bonded to a secondary or tertiary carbon (hereinafter also simply referred to as "amine compound (a2)") is a compound having two or more amino groups, at least one of which is bonded to a secondary or tertiary carbon. The number of amino groups in the amine compound (a2) is preferably 2 to 6, more preferably 2 to 4, even more preferably 2 to 3, and still more preferably 2. The number of amino groups bonded to a secondary or tertiary carbon in the amine compound (a2) is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 to 2.

[0019] The ratio of the number of amino groups bonded to secondary or tertiary carbon atoms to the total number of amino groups in the amine compound (a2) is preferably 0.25 or more, more preferably 0.40 or more, and even more preferably 0.45 or more and 1.0 or less, from the viewpoint that rapid curing properties can be imparted to the reaction composition (A1) even when an amine compound having a relatively slow curing rate is contained.

[0020] The "amino group bonded to a secondary or tertiary carbon" in the amine compound (a2) may be either a primary amino group or a secondary amino group, but from the viewpoint of rapid curing, it is preferably a primary amino group (-NH ２ )

[0021] The amine compound (a2) may be either a chain polyamine compound or a polyamine compound having a cyclic structure, and is preferably at least one selected from the group consisting of a chain diamine compound and a diamine compound having a cyclic structure. Chain polyamine compounds having an amino group bonded to a secondary or tertiary carbon are epoxy resin curing agent components that are highly flexible but cure slowly, while polyamine compounds having a cyclic structure are epoxy resin curing agent components that are low in flexibility and cure slowly.

[0022] Examples of the linear polyamine compound used as the amine compound (a2) include saturated or unsaturated linear aliphatic polyamine compounds having an amino group bonded to a secondary or tertiary carbon. The linear aliphatic polyamine compound may contain a heteroatom such as an oxygen atom in addition to the nitrogen atom in the amino group. Examples of the linear aliphatic polyamine compound containing a heteroatom include linear polyether polyamines. Specific examples of the linear polyether polyamine used as the amine compound (a2) include polyoxypropylene diamine, trimethylolpropane poly(oxypropylene) triamine, glyceryl poly(oxypropylene) triamine, polyether polyamines represented by the following general formula (I), and polyether polyamines represented by the following general formula (II). (In formula (I), n １ , n ２ and n ３ is the average number of repetitions, and n １ +n３ >1, n ２ >0.) (In formula (II), n ４ , n ５ and n ６ is the average number of repetitions, and n ４ +n ６ >1, n ５ >0.)

[0023] In formula (I), n １ +n ３ From the viewpoint of fast curing, n is preferably 2 to 30, more preferably 2 to 20, even more preferably 3 to 15, still more preferably 3 to 10, and even more preferably 3 to 8. ２ is preferably 2 to 60, more preferably 4 to 50, and even more preferably 6 to 40, from the viewpoint of rapid curing.

[0024] In formula (II), n ４ +n ６ From the viewpoint of rapid curing, n is preferably 2 to 30, more preferably 2 to 20, and even more preferably 3 to 15. ５ is preferably 1 to 40, more preferably 2 to 20, from the viewpoint of rapid curing.

[0025] Among the above, the linear polyether polyamine used as the amine compound (a2) preferably includes at least one selected from the group consisting of polyoxypropylene diamine, polyether polyamine represented by the general formula (I) above, and polyether polyamine represented by the general formula (II) above, and more preferably includes polyoxypropylene diamine. The average number of repeating oxypropylene (PO) units in the polyoxypropylene diamine is not particularly limited, but from the viewpoint of fast curing, it is preferably 2 to 90, more preferably 2 to 70, even more preferably 2 to 30, still more preferably 2 to 25, and even more preferably 2 to 10.

[0026] Commercially available products can also be used as the linear polyether polyamine used as the amine compound (a2). Examples of commercially available polyoxypropylene diamines include Jeffamine D series (D-230, D-400, D-2000, D-4000) manufactured by HUNTSMAN. Examples of trimethylolpropane poly(oxypropylene) triamines include Jeffamine T-403 manufactured by HUNTSMAN. Examples of glyceryl poly(oxypropylene) triamines include Jeffamine T-3000 and T-5000 manufactured by HUNTSMAN. Examples of the polyether polyamine represented by the general formula (I) include the Jeffamine ED series (ED-600, ED-900, ED-2003) manufactured by HUNTSMAN, and examples of the polyether polyamine represented by the general formula (II) include Jeffamine RT-1000 manufactured by HUNTSMAN.

[0027] In the polyamine compound having a ring structure and an amino group bonded to a secondary or tertiary carbon atom, which is used as the amine compound (a2), examples of the ring structure include an alicyclic structure, an aromatic ring structure, and a heterocyclic structure. Among these, the polyamine compound having a ring structure preferably includes at least one selected from the group consisting of a polyamine compound having an alicyclic structure and a polyamine compound having an aromatic ring structure, more preferably includes a polyamine compound having an alicyclic structure, and even more preferably includes a diamine compound having an alicyclic structure. The polyamine compound having a ring structure preferably has one to three ring structures, more preferably has one to two ring structures, and even more preferably has only one ring structure.

[0028] Specific examples of polyamine compounds having an alicyclic structure, which are used as the amine compound (a2), include isophoronediamine (IPDA), norbornanediamine, tricyclodecanediamine, diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 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, 4,4'-diaminodicyclohexylmethane (PACM), menthenediamine, adamantanediamine, etc. Specific examples of polyamine compounds having an aromatic ring structure, which are used as the amine compound (a2), include 4,4'-diaminodiphenylmethane (DDM), 4,4'-diaminodiphenylsulfone (DDS), etc. Specific examples of the polyamine compound having a heterocyclic structure used as the amine compound (a2) include N-aminomethylpiperazine and N-aminoethylpiperazine.

[0029] The amine compound (a2) can be one or more of the above. Among the above, the amine compound (a2) preferably includes at least one selected from the group consisting of a chain aliphatic polyamine compound, a polyamine compound having an alicyclic structure, and a polyamine compound having an aromatic ring structure, more preferably includes at least one selected from the group consisting of a chain polyether polyamine, a polyamine compound having an alicyclic structure, and a polyamine compound having an aromatic ring structure, and even more preferably includes at least one selected from the group consisting of a chain polyether polyamine and a polyamine compound having an alicyclic structure. The amine compound (a2) is preferably polyoxypropylene diamine, trimethylolpropane poly(oxypropylene) triamine, glyceryl poly(oxypropylene) triamine, polyether polyamine represented by the general formula (I), polyether polyamine represented by the general formula (II), isophorone diamine, norbornane diamine, tricyclodecane diamine, diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 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'-diaminodicyclohexane The olefin copolymer contains at least one selected from the group consisting of 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylmethane, menthenediamine, adamantanediamine, 4,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenylsulfone, more preferably at least one selected from the group consisting of polyoxypropylenediamine, isophoronediamine, 4,4'-diaminodicyclohexylmethane, and 4,4'-diaminodiphenylmethane, and from the viewpoint of improving flexibility, it further preferably contains at least one selected from the group consisting of polyoxypropylenediamine, isophoronediamine, and 4,4'-diaminodicyclohexylmethane, and even more preferably contains at least one selected from the group consisting of polyoxypropylenediamine and isophoronediamine.

[0030] (Modified Product) Examples of the modified product of the amine compound (a2) include a reaction composition containing a reaction product of the amine compound (a2) with an epoxy compound having at least one epoxy group, a reaction composition containing a reaction product of the amine compound (a2) with an unsaturated hydrocarbon compound, a reaction composition containing a reaction product of the amine compound (a2) with an unsaturated carboxylic acid or a derivative thereof, a Mannich reaction product obtained by reacting the amine compound (a2) with a phenol compound and an aldehyde compound, and a ketimine (ketimine) obtained by reacting the amine compound (a2) with a ketone compound. Among the above, the modified product of the amine compound (a2) preferably contains at least one selected from the group consisting of the following (i) to (iv), and more preferably contains the following (i): (i) a reaction composition containing a reaction product of the amine compound (a2) with an epoxy compound having at least one epoxy group; (ii) a reaction composition containing a Michael addition reaction product of the amine compound (a2) with at least one selected from the group consisting of an unsaturated hydrocarbon compound, an unsaturated carboxylic acid or a derivative thereof, and an unsaturated nitrile compound; (iii) a reaction composition containing a polycondensation reaction product of the amine compound (a2) with a polymerized fatty acid; and (iv) a Mannich reaction product obtained by reacting the amine compound (a2) with a phenol compound and an aldehyde compound.

[0031] (i) In the reaction composition containing the reaction product of the amine compound (a2) and an epoxy compound having at least one epoxy group (hereinafter also referred to as "reaction composition (i)"), the epoxy compound used may be a compound having at least one epoxy group, and more preferably a compound having two or more epoxy groups.

[0032] Examples of the epoxy compound include epichlorohydrin, butyl glycidyl ether, alkyl (C8 to C10) glycidyl ether, alkyl (C12 to C14) glycidyl ether, benzyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, neopentyl glycol diglycidyl ether, 1,3-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, biphenol diglycidyl ether, dihydroxynaphthalene diglycidyl ether, dihydroxyanthracene diglycidyl ether, triglycidyl isocyanurate, tetraglycidyl glycoluril, and compounds having a glycidylamino group derived from metaxylylenediamine. Examples of the epoxy resin include polyfunctional epoxy resins having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane, polyfunctional epoxy resins having a glycidylamino group derived from diaminodiphenylmethane, polyfunctional epoxy resins having a glycidylamino group and a glycidyloxy group derived from paraaminophenol, polyfunctional epoxy resins having a glycidyloxy group derived from bisphenol A, polyfunctional epoxy resins having a glycidyloxy group derived from bisphenol F, polyfunctional epoxy resins having a glycidyloxy group derived from phenol novolac, and polyfunctional epoxy resins having a glycidyloxy group derived from resorcinol, and one or more of these may be used.

[0033] Among the above, from the viewpoints of economy, curability, and improving the adhesion of the resulting coating film, the epoxy compound is preferably an epoxy compound containing an aromatic ring or an alicyclic structure in the molecule, more preferably an epoxy compound containing an aromatic ring in the molecule, and even more preferably a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A.

[0034] The method for producing the reaction composition (i) is not particularly limited, and known methods can be used. For example, it can be obtained by subjecting an amine compound (a2) and an epoxy compound to an addition reaction under heated conditions. More specifically, an example includes a method in which an epoxy compound or a solution thereof is added dropwise, preferably at 80°C or below, more preferably 60°C or below, while stirring the amine compound (a2) or a solution thereof. After the addition is complete, the temperature is raised to preferably 60 to 150°C, more preferably 70 to 120°C, and the reaction is carried out for 0.5 to 12 hours. The ratio of the amine compound (a2) to the epoxy compound used in the addition reaction is not particularly limited as long as the resulting reaction composition (i) contains an amino group having an active hydrogen. However, it is preferable to use an excess amount of the amine compound (a2) relative to the epoxy equivalent of the epoxy compound. Specifically, the amine compound (a2) is reacted with the epoxy compound at a ratio of the number of active hydrogens in the amine compound (a2) to the number of epoxy groups in the epoxy compound, preferably 4 / 1 to 50 / 1, more preferably 5 / 1 to 20 / 1.

[0035] (ii) In the reaction composition (hereinafter also referred to as "reaction composition (ii)") containing a Michael addition reaction product of amine compound (a2) and at least one selected from the group consisting of unsaturated hydrocarbon compounds, unsaturated carboxylic acids or derivatives thereof, and unsaturated nitrile compounds, the unsaturated hydrocarbon compound used is preferably an unsaturated hydrocarbon compound having 2 to 10 carbon atoms, from the viewpoints of reactivity with amine compound (a2), curability, and improved adhesion of the resulting coating film. Examples of the unsaturated hydrocarbon compound include unsaturated aliphatic hydrocarbon compounds having 2 to 10 carbon atoms, and aromatic hydrocarbon compounds having 2 to 10 carbon atoms and having an ethylenically unsaturated bond, such as at least one selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, isobutylene, 2-pentene, 3-methyl-1-butene, 2-methyl-2-butene, 2,3-dimethyl-2-butene, cyclohexene, cyclohexadiene, styrene, and divinylbenzene. Among the above, from the viewpoints of reactivity with the amine compound (a2), curability, and improvement in adhesion of the resulting coating film, the unsaturated hydrocarbon compound is preferably an aromatic hydrocarbon compound having an ethylenically unsaturated bond, such as styrene or divinylbenzene, and more preferably styrene.

[0036] Examples of the unsaturated carboxylic acid or derivative thereof used in the reaction composition (ii) include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, α-ethylacrylic acid, α-propylacrylic acid, α-isopropylacrylic acid, α-n-butylacrylic acid, α-t-butylacrylic acid, α-pentylacrylic acid, α-phenylacrylic acid, α-benzylacrylic acid, crotonic acid, 2-pentenoic acid, 2-hexenoic acid, 4-methyl-2-pentenoic acid, 2-heptenoic acid, 4-methyl-2-hexenoic acid, 5-methyl-2-hexenoic acid, 4,4-dimethyl-2-pentenoic acid, 4-phenyl-2-butenoic acid, cinnamic acid, o-methylcinnamic acid, m-methylcinnamic acid, p-methylcinnamic acid, and 2-octenoic acid, as well as esters, amides, acid anhydrides, and acid chlorides thereof. Among the above, the unsaturated carboxylic acid or derivative thereof is preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, and derivatives thereof, more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, and alkyl esters thereof, even more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, and alkyl esters thereof, still more preferably an alkyl ester of acrylic acid, and still more preferably methyl acrylate.

[0037] The unsaturated nitrile compound used in the reaction composition (ii) includes acrylonitrile, methacrylonitrile, etc., and preferably acrylonitrile.

[0038] The method for producing the reaction composition (ii) is not particularly limited, and known methods can be used. For example, in the Michael addition reaction of the amine compound (a2) and the unsaturated hydrocarbon compound, the reaction composition can be obtained by subjecting the amine compound (a2) and the unsaturated hydrocarbon compound to an addition reaction in the presence of a basic catalyst such as lithium amide, typically at 25 to 150°C, preferably 60 to 150°C. More specifically, a method can be used in which the unsaturated hydrocarbon compound or a solution thereof is added dropwise to a mixture of the amine compound (a2) and the basic catalyst, preferably at 80°C or lower, more preferably 60°C or lower, and after completion of the addition, the mixture is heated to preferably 60 to 150°C, more preferably 90 to 150°C, and the reaction is carried out for 0.5 to 12 hours. The reaction molar ratio of the amine compound (a2) to the unsaturated hydrocarbon compound in the addition reaction is not particularly limited as long as the resulting reaction composition (ii) contains an amino group having an active hydrogen, but is preferably in the range of 0.1 to 5.0 mol, more preferably 0.4 to 3.0 mol, even more preferably 0.5 to 1.5 mol, and still more preferably 0.8 to 1.2 mol, per 1 mol of the amine compound (a2).

[0039] In the Michael addition reaction of amine compound (a2) with an unsaturated carboxylic acid or a derivative thereof, or an unsaturated nitrile compound, the reaction product can be obtained by reacting amine compound (a2) with an unsaturated carboxylic acid or a derivative thereof, or an unsaturated nitrile compound under heated conditions. More specifically, an unsaturated carboxylic acid or a derivative thereof, or an unsaturated nitrile compound is added dropwise to amine compound (a2) or a solution thereof while stirring, preferably at 80°C or below, more preferably at 60°C or below, and after completion of the addition, the temperature is preferably raised to 60 to 150°C and the reaction is carried out for 0.5 to 12 hours. The reaction molar ratio of amine compound (a2) with unsaturated carboxylic acid or a derivative thereof, or unsaturated nitrile compound in the addition reaction is not particularly limited as long as the resulting reaction composition (ii) contains an amino group having an active hydrogen, but is preferably in the range of 0.3 to 1.0 mol, more preferably 0.6 to 1.0 mol, per 1 mol of amine compound (a2).

[0040] (iii) The polycondensation reaction product of the amine compound (a2) and the polymerized fatty acid (hereinafter also referred to as "reaction composition (iii)") is specifically a polyamidoamine. Examples of the polymerized fatty acid used in the reaction composition (iii) include dimers (dimer acids) of unsaturated fatty acids. The dimer acids may contain small amounts of monomers, trimers, and the like. The unsaturated fatty acids preferably include unsaturated fatty acids having 12 to 24 carbon atoms, more preferably 16 to 18 carbon atoms. The number of unsaturated bonds in the unsaturated fatty acids may be one or more, preferably 1 to 3, and more preferably 1 to 2. Specific examples of the unsaturated fatty acids include oleic acid, elaidic acid, cetoleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. One or more of these may be used.

[0041] The structure of the dimer acid is not limited as long as it is a dimer of the unsaturated fatty acid. For example, when the dimer acid is a dimer of oleic acid, the structure of the dimer includes a linear type (a), a monocyclic type (b), an aromatic ring type (c), and a polycyclic type (d) shown in the following structural formula:

[0042] The method for producing the reaction composition (iii) is not particularly limited, and known polycondensation methods can be used. For example, the reaction composition (iii) can be obtained by reacting an amine compound (a2) with a polymerized fatty acid under heating conditions. The reaction molar ratio of the amine compound (a2) to the polymerized fatty acid in the polycondensation reaction is not particularly limited as long as the resulting reaction composition (iii) contains an amino group having an active hydrogen, but is preferably in the range of 0.3 to 1.0 mol, more preferably 0.6 to 1.0 mol, per 1 mol of the amine compound (a2).

[0043] (iv) In the Mannich reaction product (hereinafter also referred to as "Mannich reaction product (iv)") obtained by reacting the amine compound (a2) with a phenol compound and an aldehyde compound, examples of the phenol compound used include naturally occurring phenol compounds such as phenol, alkylphenols, alkenylphenols, terpene phenols, and cardanol. From the viewpoints of reactivity with the amine compound (a2), curability, and improved adhesion of the resulting coating film, the number of carbon atoms in the alkyl group of the alkylphenol is preferably 1 to 24, more preferably 1 to 18, and the number of carbon atoms in the alkenyl group of the alkenylphenol is preferably 2 to 24, more preferably 2 to 18. Specific examples of the phenol compound include phenol, cresol, ethylphenol (e.g., p-ethylphenol), isopropylphenol (e.g., o-isopropylphenol, p-isopropylphenol), butylphenol (e.g., p-tert-butylphenol, p-sec-butylphenol, o-tert-butylphenol, o-sec-butylphenol), amylphenol (e.g., p-tert-amylphenol, o-tert-amylphenol), p-octylphenol, nonylphenol, p-cumylphenol, decylphenol, undecylphenol, p-dodecylphenol, tridecylphenol, tetradecylphenol, pentadecylphenol, pentadecenylphenol, pentadecadienylphenol, pentadecatrienylphenol, hexadecylphenol, heptadecylphenol, octadecylphenol, octadecenylphenol, terpene phenol, and cardanol. These may be used alone or in combination of two or more. Among the above, from the viewpoints of reactivity with the amine compound (a2), curability, and improvement in adhesion of the resulting coating film, the phenol compound used in the modified product (I) is preferably at least one selected from the group consisting of phenol, cresol, p-tert-butylphenol, nonylphenol, and cardanol, and more preferably phenol.

[0044] Examples of the aldehyde compound used in the Mannich reaction product (iv) include formaldehyde; formaldehyde-releasing compounds such as trioxane and paraformaldehyde; and other aldehydes such as benzaldehyde. Among these, at least one selected from the group consisting of formaldehyde and formaldehyde-releasing compounds is preferred. Among these, from the viewpoint of workability in the Mannich reaction, it is more preferred to use an aqueous formaldehyde solution.

[0045] The method for producing the Mannich reaction product (iv) is not particularly limited, and known methods can be used. For example, an aldehyde compound or a solution thereof is added dropwise to a mixture of an amine compound (a2) and a phenolic compound, preferably at 80°C or below, more preferably 60°C or below, and after the addition is complete, the temperature is raised to preferably 80 to 180°C, more preferably 90 to 150°C, and the reaction is carried out for preferably 0.5 to 12 hours while removing the distillate from the reaction system. The reaction molar ratio of the amine compound (a2), phenolic compound, and aldehyde compound in the Mannich reaction is not particularly limited as long as the resulting Mannich reaction product (iv) contains an amino group having an active hydrogen. However, from the viewpoints of reactivity with the amine compound (a2), curability, and improved adhesion of the resulting coating film, the following range is preferred. The aldehyde compound is used in a range of preferably 0.3 to 2 mol, more preferably 0.5 to 1.5 mol, per 1 mol of the amine compound (a2). The phenol compound is used in an amount of preferably 0.3 to 2 moles, more preferably 0.5 to 1.5 moles, per mole of the amine compound (a2).

[0046] The reaction compositions (i) to (iii) and the Mannich reaction product (iv) may be produced in a solvent or without a solvent, and the reaction with the amine compound (a2) is preferably carried out in an inert atmosphere such as nitrogen gas.

[0047] The amine compound (A2) may be one or more of these. Among the above, the amine compound (A2) preferably includes an amine compound (a2) having an amino group bonded to a secondary or tertiary carbon or a modified product thereof, more preferably a chain-like polyether polyamine having an amino group bonded to a secondary or tertiary carbon, a polyamine compound having an alicyclic structure having an amino group bonded to a secondary or tertiary carbon, a polyamine compound having an aromatic ring structure having an amino group bonded to a secondary or tertiary carbon, or a modified product thereof, even more preferably a chain-like polyether polyamine having an amino group bonded to a secondary or tertiary carbon, a polyamine compound having an alicyclic structure having an amino group bonded to a secondary or tertiary carbon, or a modified product thereof, still more preferably a chain-like polyether polyamine having an amino group bonded to a secondary carbon, isophorone diamine, or a modified product thereof, and even more preferably a polyoxypropylene diamine, isophorone diamine, or a modified product thereof. The modified product is preferably a reaction composition containing a reaction product of the amine compound (a2) and an epoxy compound having at least one epoxy group.

[0048] <Other Curing Agent Components> The epoxy resin curing agent of the present invention may contain curing agent components other than the reaction composition (A1) and the amine compound (A2), as long as the effects of the present invention are not impaired. The curing agent component may be a compound having two or more groups containing active hydrogen that can react with epoxy groups in the epoxy resin that is the main component of the epoxy resin composition, and examples of the curing agent component include phenol-based curing agents, acid anhydride-based curing agents, and hydrazide-based curing agents.

[0049] <Content> From the viewpoint of fast curing, the content of the reactive composition (A1) in the epoxy resin curing agent of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 5% by mass or more, still more preferably 10% by mass or more, still more preferably 15% by mass or more, and still more preferably 18% by mass or more, based on the total curing agent components. Furthermore, from the viewpoint of economic efficiency and from the viewpoint of being able to impart fast curing properties with the reactive composition (A1) even when an amine compound having a relatively slow curing rate is contained, the content is preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 60% by mass or less, still more preferably 50% by mass or less, still more preferably less than 50% by mass, still more preferably 45% by mass or less, still more preferably 40% by mass or less, still more preferably 30% by mass or less, and still more preferably 25% by mass or less. The content of the reactive composition (A1) in the epoxy resin curing agent of the present invention is preferably 1 to 80 mass%, more preferably 2 to 75 mass%, even more preferably 5 to 60 mass%, still more preferably 10 to 50 mass%, even more preferably 15 to 50 mass%, and still more preferably 18 to 50 mass% of all the curing agent components. The content of the reactive composition (A1) in the epoxy resin curing agent is even more preferably 10 mass% or more but less than 50 mass%, even more preferably 15 to 45 mass%, even more preferably 15 to 40 mass%, even more preferably 15 to 30 mass%, even more preferably 15 to 25 mass%, and still more preferably 18 to 25 mass% of all the curing agent components. In this specification, the term "total curing agent components in the curing agent" refers to all components contained in the curing agent that have two or more active hydrogens capable of reacting with epoxy groups in the epoxy resin that is the main component of the epoxy resin composition, and the content (mass %) of the reactive composition (A1) relative to the total curing agent components in the curing agent refers to the mass proportion of the reactive composition (A1) relative to the total amount of curable components contained in the curing agent.

[0050] From the viewpoint of being able to impart fast curing properties with the reaction composition (A1) even when an amine compound having a relatively slow curing rate is contained, the content of the amine compound (A2) in the epoxy resin curing agent of the present invention is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 40% by mass or more, still more preferably 50% by mass or more, still more preferably more than 50% by mass, still more preferably 55% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 75% by mass or more, based on the total curing agent components. Also, it is less than 100% by mass, and from the viewpoint of fast curing properties, it is preferably 99% by mass or less, more preferably 98% by mass or less, even more preferably 95% by mass or less, still more preferably 90% by mass or less, and still more preferably 85% by mass or less. The content of the amine compound (A2) in the epoxy resin curing agent of the present invention is preferably 20% by mass or more and less than 100% by mass, more preferably 25 to 99% by mass, even more preferably 40 to 98% by mass, still more preferably 50 to 95% by mass, even more preferably 50 to 90% by mass, and still more preferably 50 to 85% by mass, of all the curing agent components. The content of the amine compound (A2) in the epoxy resin curing agent is even more preferably more than 50% by mass and 99% by mass or less, even more preferably 55 to 98% by mass, even more preferably 60 to 95% by mass, even more preferably 70 to 90% by mass, and even more preferably 75 to 85% by mass.

[0051] The mass ratio of the reactive composition (A1) to the total mass of the reactive composition (A1) and the amine compound (A2) contained in the epoxy resin curing agent of the present invention, [(A1) / {(A1)+(A2)}], may be greater than 0, and from the viewpoint of fast curing, is preferably 0.01 or more, more preferably 0.02 or more, even more preferably 0.05 or more, still more preferably 0.10 or more, still more preferably 0.15 or more, and still more preferably 0.18 or more. Furthermore, from the viewpoint of economy and from the viewpoint of being able to impart fast curing properties by the reactive composition (A1) even when an amine compound with a relatively slow curing rate is contained, the mass ratio is preferably 0.80 or less, more preferably 0.75 or less, even more preferably 0.60 or less, still more preferably 0.50 or less, still more preferably less than 0.50, still more preferably 0.45 or less, still more preferably 0.40 or less, still more preferably 0.30 or less, and still more preferably 0.25 or less. The mass ratio [(A1) / {(A1)+(A2)}] is preferably greater than 0 and not greater than 0.80, more preferably 0.01 to 0.75, even more preferably 0.02 to 0.60, still more preferably 0.05 to 0.50, still more preferably 0.10 to 0.50, still more preferably 0.15 to 0.50, and still more preferably 0.18 to 0.50. The mass ratio [(A1) / {(A1)+(A2)}] is even more preferably 0.10 or greater and less than 0.50, even more preferably 0.15 to 0.45, even more preferably 0.15 to 0.40, still more preferably 0.15 to 0.30, and still more preferably 0.18 to 0.25.

[0052] The total content of the reaction composition (A1) and the amine compound (A2) in the epoxy resin curing agent is, from the viewpoint of fast curing property and effectively obtaining the effects of the present invention, 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, and still more preferably 95% by mass or more, but 100% by mass or less.

[0053] <Active Hydrogen Equivalent Weight (AHEW)> From the viewpoint of improving the adhesion of the resulting coating film, the active hydrogen equivalent weight (AHEW) of the epoxy resin curing agent is preferably 40 or more, more preferably 45 or more, and from the viewpoint of fast curing, it is preferably 500 or less, more preferably 300 or less, even more preferably 200 or less, still more preferably 100 or less, still more preferably 90 or less, still more preferably 80 or less, and still more preferably 70 or less. The AHEW of an epoxy resin curing agent is the mass of the epoxy resin curing agent per mole of active hydrogen contained in the epoxy resin curing agent, and can be calculated from the amine value determined, for example, by titration.

[0054] The epoxy resin curing agent of the present invention may be either a curing agent for non-aqueous epoxy resins or a curing agent for aqueous epoxy resins. When the amine compound (A2) contains an amine compound (a2) having an amino group bonded to a secondary or tertiary carbon, or a modified product thereof, the epoxy resin curing agent of the present invention is preferably a curing agent for non-aqueous epoxy resins. In this specification, an aqueous epoxy resin curing agent refers to an epoxy resin curing agent used for a water-soluble epoxy resin or an epoxy resin emulsion, and a non-aqueous epoxy resin curing agent refers to an epoxy resin curing agent that does not fall under the category of an aqueous epoxy resin curing agent.

[0055] [Epoxy Resin Composition] The epoxy resin composition of the present invention contains an epoxy resin as a main component and the epoxy resin curing agent of the present invention.

[0056] <Epoxy Resin> The epoxy resin, which is the main component of the epoxy resin composition, is a polyfunctional epoxy resin having two or more epoxy groups in the molecule. The epoxy resin may be a saturated or unsaturated linear aliphatic epoxy resin, or may be an epoxy resin having a ring structure such as an aromatic ring, an alicyclic structure, or a heterocyclic structure. From the viewpoints of fast curing and obtaining a coating film with high adhesion, it is preferable to contain an epoxy resin having an aromatic ring or an alicyclic structure.

[0057] Specific examples of the epoxy resin include epoxy resins having a glycidylamino group derived from meta-xylylenediamine, epoxy resins having a glycidylamino group derived from para-xylylenediamine, epoxy resins having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane, epoxy resins having a glycidylamino group derived from 1,4-bis(aminomethyl)cyclohexane, epoxy resins having a glycidylamino group derived from diaminodiphenylmethane, and epoxy resins having a glycidylamino group and / or a glycidyloxy group derived from para-aminophenol. The epoxy resin may be at least one resin selected from the group consisting of epoxy resins having a glycidyloxy group derived from bisphenol A, epoxy resins having a glycidyloxy group derived from bisphenol F, epoxy resins having a glycidyloxy group derived from phenol novolac, epoxy resins having a glycidyloxy group derived from hydrogenated bisphenol A, epoxy resins having a glycidyloxy group derived from hydrogenated bisphenol F, epoxy resins having a glycidyloxy group derived from hydrogenated phenol novolac, and epoxy resins having a glycidyloxy group derived from resorcinol. One or more of the above epoxy resins may be used.

[0058] Among the above, from the viewpoints of fast curing and obtaining a coating film with high adhesion, the epoxy resin preferably contains, as a main component, at least one selected from the group consisting of epoxy resins having a glycidylamino group derived from meta-xylylenediamine, epoxy resins having a glycidylamino group derived from para-xylylenediamine, epoxy resins having a glycidyloxy group derived from bisphenol A, epoxy resins having a glycidyloxy group derived from bisphenol F, epoxy resins having a glycidyloxy group derived from hydrogenated bisphenol A, and epoxy resins having a glycidyloxy group derived from hydrogenated bisphenol F, and more preferably contains, as a main component, an epoxy resin having a glycidyloxy group derived from bisphenol A. Here, the term "main component" means that other components may be contained within the scope of the present invention, and preferably means 50 to 100 mass%, more preferably 70 to 100 mass%, and even more preferably 90 to 100 mass% of the total.

[0059] The epoxy resin as the base resin may contain a reactive diluent other than the above-mentioned epoxy resin from the viewpoint of improving handleability. 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-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diglycidyl ether. One or more of the above-mentioned reactive diluents can be used.

[0060] The content ratio of the epoxy resin to the epoxy resin curing agent in the epoxy resin composition of the present invention is such that the ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin (number of active hydrogens in the epoxy resin curing agent / number of epoxy groups in the epoxy resin) is preferably 1 / 0.5 to 1 / 2, more preferably 1 / 0.75 to 1 / 1.5, and even more preferably 1 / 0.8 to 1 / 1.2.

[0061] The contents of the epoxy resin and epoxy resin curing agent in the epoxy resin composition are not limited as long as the ratio of the number of active hydrogen atoms derived from amino groups in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin falls within the above-mentioned range. However, from the viewpoints of fast curing and obtaining a coating film with excellent appearance and adhesion, the contents are preferably within the following ranges.

[0062] The content of the epoxy resin in the epoxy resin composition is preferably 30 to 90 mass%, more preferably 40 to 85 mass%, even more preferably 50 to 85 mass%, and still more preferably 60 to 85 mass%.

[0063] The content of the epoxy resin curing agent in the epoxy resin composition is preferably 10 to 70% by mass, more preferably 15 to 60% by mass, even more preferably 15 to 50% by mass, still more preferably 15 to 40% by mass, even more preferably 15 to 30% by mass, and still more preferably 15 to 25% by mass. The content of the epoxy resin curing agent in the epoxy resin composition is preferably 15 to 60 parts by mass, more preferably 20 to 50 parts by mass, even more preferably 20 to 40 parts by mass, and still more preferably 20 to 35 parts by mass, per 100 parts by mass of the epoxy resin as the main component.

[0064] From the viewpoint of effectively obtaining the effects of the present invention, the total content of the epoxy resin and the epoxy resin curing agent in the epoxy resin composition is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, still more preferably 70% by mass or more, and still more preferably 80% by mass or more, but is 100% by mass or less.

[0065] <Non-reactive diluent> The epoxy resin composition may further contain a non-reactive diluent from the viewpoint of improving handleability and obtaining a coating film with high adhesion. Examples of non-reactive diluents include benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, and aromatic hydrocarbon formaldehyde resins, and one or more of these can be used. The aromatic hydrocarbon formaldehyde resin is a resin obtained by reacting an aromatic hydrocarbon with formaldehyde, and examples thereof include a toluene formaldehyde resin obtained by reacting toluene with formaldehyde, a xylene formaldehyde resin obtained by reacting xylene with formaldehyde, a mesitylene formaldehyde resin obtained by reacting mesitylene with formaldehyde, and a pseudocumene formaldehyde resin obtained by reacting pseudocumene with formaldehyde. Among these, from the viewpoint of obtaining a coating film with high adhesion, xylene formaldehyde resin is preferred as the aromatic hydrocarbon formaldehyde resin. Commercially available aromatic hydrocarbon formaldehyde resins include "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," which are xylene formaldehyde resins manufactured by Fudow Co., Ltd.

[0066] Among the above, from the viewpoint of obtaining a coating film with high adhesion, the non-reactive diluent preferably contains at least one selected from the group consisting of benzyl alcohol and an aromatic hydrocarbon formaldehyde resin, more preferably contains at least one selected from the group consisting of benzyl alcohol and a xylene formaldehyde resin, even more preferably contains benzyl alcohol, and even more preferably is benzyl alcohol. When the non-reactive diluent contains benzyl alcohol, from the viewpoint of obtaining a coating film with high adhesion, the content of benzyl alcohol in the non-reactive diluent is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, still more preferably 55% by mass or more, and even more preferably 70% by mass or more, and is 100% by mass or less.

[0067] When the epoxy resin composition contains a non-reactive diluent, the content of the non-reactive diluent in the epoxy resin composition is preferably 1 to 60 mass%, more preferably 2 to 50 mass%, even more preferably 5 to 40 mass%, still more preferably 10 to 30 mass%, still more preferably 10 to 25 mass%, and still more preferably 10 to 20 mass%, from the viewpoints of rapid curing property, improved handleability, and obtaining a coating film with high adhesion.

[0068] From the viewpoint of obtaining the effects of the present invention, the total content of the epoxy resin, epoxy resin curing agent, and non-reactive diluent in the epoxy resin composition is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, and still more preferably 90% by mass or more, but is 100% by mass or less.

[0069] The epoxy resin composition of the present invention may further contain other components such as curing accelerators, fillers, modifying components such as plasticizers, flow-adjusting components such as thixotropic agents, pigments, leveling agents, tackifiers, elastomer fine particles, etc., depending on the intended use.

[0070] The epoxy resin composition of the present invention may contain solvents (water and volatile solvents) other than the non-reactive diluent, but the content thereof in the epoxy resin composition is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less. The epoxy resin composition of the present invention is preferably a non-aqueous epoxy resin composition. The content of water in the non-aqueous epoxy resin composition is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less.

[0071] <Method for producing epoxy resin composition> There is no particular limitation on the method for producing the epoxy resin composition of the present invention, and the composition can be produced by mixing the epoxy resin, the epoxy resin curing agent, and other components used as needed using known methods and devices. There is also no particular limitation on the order in which the components contained in the epoxy resin composition are mixed. The epoxy resin curing agent may be prepared and then mixed with the epoxy resin, or the components constituting the epoxy resin curing agent and other components may be simultaneously mixed with the epoxy resin to prepare the composition.

[0072] From the viewpoint of ease of production, when the non-reactive diluent is used, the epoxy resin composition is preferably prepared by preparing an epoxy resin curing agent composition containing an epoxy resin curing agent and a non-reactive diluent, and then mixing the epoxy resin curing agent composition with the epoxy resin as the main component. When the curing accelerator is used, the epoxy resin composition is preferably prepared by preparing an epoxy resin curing agent composition containing an epoxy resin curing agent and a curing accelerator, and then mixing the epoxy resin curing agent composition with the epoxy resin as the main component.

[0073] [Cured Product] The cured product of the epoxy resin composition of the present invention (hereinafter also simply referred to as "the cured product of the present invention") is obtained by curing the epoxy resin composition by a known method. The curing conditions for the epoxy resin composition are appropriately selected depending on the application and form, and are not particularly limited. The form of the cured product of the present invention is also not particularly limited, and can be selected depending on the application. From the viewpoint of forming a coating film, the cured product of the epoxy resin composition is preferably a film-like cured product. The coating film that is the cured product of the epoxy resin composition of the present invention is fast-curing and also has good adhesion.

[0074] <Applications> The epoxy resin composition of the present invention is fast-curing and can form a coating film with good adhesion, and is therefore suitably used in coating applications such as marine paints, heavy-duty anticorrosion paints, tank paints, pipe interior paints, exterior paints, and flooring paints.

[0075] 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. Various measurements and evaluations in each example were carried out as follows.

[0076] (RCI Curing Time) An epoxy resin composition was applied to a glass plate (25 mm x 348 mm x 2.0 mm, manufactured by Taiyu Kizai Co., Ltd.) using a 76 μm applicator at 23° C. and 50% RH to form a coating film. The glass plate on which the coating film had been formed was set in a paint drying time measuring instrument (manufactured by Taiyu Kizai Co., Ltd.), and the marks left when the needle of the measuring instrument scratched the coating film surface were observed, and the time to reach each drying stage (touch dry, semi-dry) was measured according to the following criteria. A shorter time indicates a faster curing rate. In this specification, a shorter semi-drying time is considered to be "fast curing." Touch dry (Set to Touch): The time until the needle mark begins to remain on the glass plate. Semi-dry (Dust Free): The time until the needle mark appears from within the coating film and emerges on the coating film surface.

[0077] (Touch Dryness) A zinc phosphate-treated steel plate (SPCC-SD PB-N144, 0.8 mm x 70 mm x 150 mm, manufactured by Paltec Co., Ltd.) was used as the substrate. The epoxy resin composition was applied to the substrate using an applicator under conditions of 23°C and 50% RH to form a coating film (coating film thickness immediately after application: 200 μm). This coating film was stored under conditions of 23°C and 50% RH, and evaluated by touch after 1, 2, and 7 days according to the following criteria. Ex: Excellent (the coating film is not sticky when pressed with a thumb at a force of about 50N, and no fingerprints remain) G: Good (the coating film is not sticky when pressed with a thumb at a force of about 50N, but fingerprints remain after touching) F: Fair (the coating film is sticky when pressed with a thumb at a force of about 50N, but not when pressed with a thumb at a force of about 5N) P: Poor (the coating film is sticky when pressed with a thumb at a force of about 5N)

[0078] (Appearance) Using the same method as above, an epoxy resin composition was applied to a substrate (zinc phosphate-treated steel plate) to form a coating film (thickness immediately after application: 200 μm). The appearance of the resulting coating film was visually observed one day later, and the transparency, smoothness, and gloss were evaluated using the following criteria. <Transparency> Ex: Excellent (no cloudiness) G: Good (slight cloudiness, but no problems in use) F: Fair (slight cloudiness, but no problems in use) P: Poor (cloudiness) <Smoothness> Ex: Excellent (no unevenness) G: Good (slight unevenness, but no problems in use) F: Fair (some unevenness, but no problems in use) P: Poor (cracking or unevenness over the entire surface) <Gloss> Ex: Excellent (glossy) G: Good (slightly inferior gloss, but no problems in use) F: Fair (low gloss, but no problems in use) P: Poor (no gloss)

[0079] (Erichsen Test) Using the same method as described above, an epoxy resin composition was applied to a substrate (zinc phosphate-treated steel plate) to form a coating film (thickness immediately after application: 200 μm). This coating film was stored under conditions of 23°C and 50% RH. After 7 days, the coating film was subjected to an Erichsen test under conditions of 23°C and 50% RH using an Erichsen film strength tester ("HD-4510" manufactured by Ueshima Seisakusho Co., Ltd.) in accordance with JIS K 5600-5-2:1999 (cupping resistance) at 23°C and 50% RH to measure the minimum indentation depth (mm) until the coating film developed defects. A larger value indicates a higher coating film's ability to adapt to deformation and better adhesion to the substrate. A minimum indentation depth greater than 9 mm was indicated as ">9."

[0080] Production Example 1 (Production of Reaction Composition (A1) (Reaction Molar Ratio 1 / 1) Comprising a Reaction Product of Metaxylylenediamine and Ethylene Oxide) 136.19 g (1 mol) of metaxylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Inc.) was charged into a reaction vessel and heated to 80°C while stirring under a nitrogen stream. While continuing to stir, 44.05 g (1 mol) of ethylene oxide was blown into the reaction vessel over 5 hours, and after completion of the blowing, the mixture was stirred at 80 to 120°C for 1 hour to react, thereby obtaining Reaction Composition (A1). The active hydrogen equivalent weight (AHEW) derived from the amino groups of Reaction Composition (A1) was 60.

[0081] Production Example 2 (Production of a solution of a reaction composition (IPDA-jER828 reaction composition) containing a reaction product of isophorone diamine and an epoxy compound) A 500 mL separable flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a dropping funnel, and a condenser was charged with 137 g of isophorone diamine (IPDA, manufactured by EVONIK). Under a nitrogen stream, 50 g of a polyfunctional epoxy resin having glycidyloxy groups derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent) was added dropwise over 2 hours (an amount such that the number of active hydrogens in IPDA / the number of epoxy groups in the epoxy compound = 12 / 1) was added dropwise over 2 hours with stirring. After completion of the dropwise addition, the temperature was raised to 80°C, and the reaction was carried out for 2 hours, yielding an IPDA-jER828 reaction composition. The reaction composition solution was diluted with benzyl alcohol, a non-reactive diluent, to 40% by mass, to obtain a reaction composition solution with a concentration of 60% by mass. The active hydrogen equivalent weight (AHEW) of the reaction composition solution (total amount including benzyl alcohol) was 106.

[0082] Examples 1-2 and Comparative Example 1 (Preparation and Evaluation of Epoxy Resin Compositions (1)) In Examples 1-2, the reaction composition (A1) obtained in Production Example 1 and isophorone diamine (IPDA, AHEW43, manufactured by EVONIK) were used as the epoxy resin curing agent, and a polyfunctional epoxy resin having glycidyloxy groups derived from bisphenol A (jER828, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 186 g / equivalent) was used as the main epoxy resin. In Comparative Example 1, only isophorone diamine was used as the epoxy resin curing agent, and jER828 was used as the main epoxy resin. The curing agent and main resin were blended and mixed in the proportions shown in Table 1 to prepare epoxy resin compositions. The ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the main epoxy resin (number of active hydrogens in the curing agent / number of epoxy groups in the main epoxy resin) was 1 / 1. Using the obtained epoxy resin compositions, the RCI cure time was measured by the method described above. The results are shown in Table 1.

[0083] Examples 3-4, Comparative Example 2 In Examples 3-4, the reaction composition (A1) obtained in Production Example 1 and polyoxypropylene diamine (HUNTSMAN's "Jeffamine D-230", AHEW60) were used as the epoxy resin curing agent, and a multifunctional epoxy resin having glycidyloxy groups derived from bisphenol A (Mitsubishi Chemical Corporation's "jER828", epoxy equivalent 186 g / equivalent) was used as the main epoxy resin. In Comparative Example 2, only "Jeffamine D-230" was used as the epoxy resin curing agent, and "jER828" was used as the main epoxy resin. The curing agent and main resin were blended and mixed in the proportions shown in Table 2 to prepare epoxy resin compositions. The ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the main epoxy resin (number of active hydrogens in the curing agent / number of epoxy groups in the main epoxy resin) was 1 / 1. The RCI curing time of the obtained epoxy resin composition was measured by the method described above, and the results are shown in Table 2.

[0084] Example 5 and Comparative Example 3 In Example 5, the reaction composition (A1) obtained in Production Example 1 and 4,4'-diaminodicyclohexylmethane (PACM, AHEW53) were used as the epoxy resin curing agent, and a multifunctional epoxy resin having glycidyloxy groups derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 186 g / equivalent) was used as the base epoxy resin. In Comparative Example 3, only PACM was used as the epoxy resin curing agent, and "jER828" was used as the base epoxy resin. The curing agent and base were blended and mixed in the proportions shown in Table 3 to prepare an epoxy resin composition. The ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the base epoxy resin (number of active hydrogens in the curing agent / number of epoxy groups in the base epoxy resin) was 1 / 1. Using the obtained epoxy resin composition, the RCI cure time was measured using the method described above. The results are shown in Table 3. In the following description, the amounts in the tables are all amounts of active ingredients.

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[0088] According to Tables 1 to 3, it can be seen that the epoxy resin compositions of Examples 1 to 5 containing the epoxy resin curing agent of the present invention have shorter semi-drying times and are faster curing than the corresponding epoxy resin compositions of Comparative Examples.

[0089] Examples 6 to 7 and Comparative Example 4 (Preparation and Evaluation of Epoxy Resin Compositions (2)) The reaction composition (A1) obtained in Production Example 1 was diluted with benzyl alcohol to 40 mass% of the total amount, yielding a solution of reaction composition (A1) with a concentration of 60 mass%. In Examples 6 and 7, the epoxy resin curing agent solution was a mixed solution prepared by mixing the solution of reaction composition (A1) and the IPDA-jER828 reaction composition solution (60 mass%) obtained in Production Example 2, such that the reaction composition (A1) and the IPDA-jER828 reaction composition were mixed in the ratios shown in Table 4. In Comparative Example 4, only the IPDA-jER828 reaction composition solution obtained in Production Example 2 was used as the epoxy resin curing agent solution. Furthermore, a multifunctional epoxy resin having glycidyloxy groups derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 186 g / equivalent) was used as the base epoxy resin. The curing agent solution and the base resin were blended and mixed in the proportions shown in Table 4 to prepare an epoxy resin composition. The ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the base epoxy resin (number of active hydrogens in the curing agent / number of epoxy groups in the base epoxy resin) was 1 / 1. The obtained epoxy resin composition was subjected to various evaluations using the methods described above. The results are shown in Table 4.

[0090] Examples 8-9 and Comparative Example 5: The reaction composition (A1) obtained in Production Example 1 was diluted with benzyl alcohol to 40% by mass of the total amount to obtain a solution of reaction composition (A1) with a concentration of 60% by mass. Also, polyoxypropylenediamine (Huntsman's "Jeffamine D-230", AHEW60) was diluted with benzyl alcohol to 40% by mass of the total amount to obtain a polyoxypropylenediamine solution with a concentration of 60% by mass. In Examples 8-9, the epoxy resin curing agent solution was a mixed solution obtained by mixing the reaction composition (A1) solution and a polyoxypropylenediamine solution in the proportions of reaction composition (A1) and polyoxypropylenediamine shown in Table 5. In Comparative Example 5, only the polyoxypropylenediamine solution was used as the epoxy resin curing agent solution. The base epoxy resin used was a multifunctional epoxy resin having glycidyloxy groups derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 186 g / equivalent). The curing agent solution and base resin were blended and mixed in the proportions shown in Table 5 to prepare an epoxy resin composition. The ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the base epoxy resin (number of active hydrogens in the curing agent / number of epoxy groups in the base epoxy resin) was 1 / 1. The obtained epoxy resin composition was subjected to various evaluations using the methods described above. The results are shown in Table 5.

[0091] Examples 10-11, Comparative Example 6 For Examples 10-11, epoxy resin compositions were prepared in the same manner as in Examples 8-9, except that 4,4'-diaminodicyclohexylmethane (PACM) was used instead of polyoxypropylenediamine. For Comparative Example 6, an epoxy resin composition was prepared in the same manner as in Comparative Example 5, except that only a 60% by mass PACM-benzyl alcohol solution was used as the epoxy resin curing agent solution. The obtained epoxy resin compositions were subjected to various evaluations using the methods described above. The results are shown in Table 6.

[0092] Examples 12-13, Comparative Example 7 For Examples 12-13, epoxy resin compositions were prepared in the same manner as in Examples 8-9, except that 4,4'-diaminodiphenylmethane (DDM) was used instead of polyoxypropylenediamine. For Comparative Example 7, an epoxy resin composition was prepared in the same manner as in Comparative Example 5, except that only a 60% by mass DDM-benzyl alcohol solution was used as the epoxy resin curing agent solution. The obtained epoxy resin compositions were subjected to various evaluations using the methods described above. The results are shown in Table 7.

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[0097] Tables 4 to 7 show the evaluation results of epoxy resin compositions containing an epoxy resin as a base, an epoxy resin curing agent, and a non-reactive diluent. The epoxy resin compositions of Examples 6 to 13, which contain a non-reactive diluent, also exhibited shorter semi-drying times and faster curing than the corresponding epoxy resin compositions of Comparative Examples. Furthermore, it can be seen that the coatings formed using the epoxy resin compositions of Examples 6 to 13 exhibited better Erichsen test results. The amine compound (A2), "Jeffamine D-230," used in Table 5, is known as a highly flexible diamine. However, as shown in Table 5, the coatings formed using the epoxy resin compositions of Examples 8 and 9 exhibited better Erichsen test results than the coating of Comparative Example 5, which used only "Jeffamine D-230" as the epoxy resin curing agent.

[0098] According to the present invention, it is possible to provide a fast-curing epoxy resin curing agent, an epoxy resin composition, and a cured product thereof, which contain an amine compound conventionally used as an epoxy resin curing agent, particularly an amine compound having a relatively slow curing rate.

Claims

1. An epoxy resin curing agent comprising a reaction composition (A1) containing a reaction product of xylylenediamine and alkylene oxide, and an amine compound (A2) other than the reaction composition (A1).

2. The epoxy resin curing agent according to claim 1, wherein the amine compound (A2) comprises an amine compound (a2) having an amino group bonded to a secondary or tertiary carbon, or a modified product thereof.

3. The epoxy resin curing agent according to claim 2, wherein the amine compound (a2) comprises at least one selected from the group consisting of linear polyether polyamines, polyamine compounds having an alicyclic structure, and polyamine compounds having an aromatic ring structure.

4. The epoxy resin curing agent according to claim 2 or 3, wherein the modified product of the amine compound (a2) comprises at least one selected from the group consisting of the following (i) to (iv): (i) a reaction composition comprising a reaction product of the amine compound (a2) with an epoxy compound having at least one epoxy group, (ii) a reaction composition comprising a Michael addition reaction product of the amine compound (a2) with at least one selected from the group consisting of an unsaturated hydrocarbon compound, an unsaturated carboxylic acid or a derivative thereof, and an unsaturated nitrile compound, (iii) a reaction composition comprising a polycondensation reaction product of the amine compound (a2) with a polymerized fatty acid, or (iv) a Mannich reaction product obtained by reacting the amine compound (a2) with a phenol compound and an aldehyde compound.

5. The epoxy resin curing agent according to any one of claims 1 to 4, wherein the mass ratio of the reaction composition (A1) to the total mass of the reaction composition (A1) and the amine compound (A2), [(A1) / {(A1)+(A2)}], is greater than 0 and not greater than 0.

80.

6. The epoxy resin curing agent according to any one of claims 1 to 5, wherein the content of the reaction composition (A1) in the epoxy resin curing agent is less than 50 mass% of all curing agent components.

7. The epoxy resin curing agent according to any one of claims 1 to 6, wherein in the reaction composition (A1), the alkylene oxide comprises ethylene oxide.

8. The epoxy resin curing agent according to any one of claims 1 to 7, wherein the reaction composition (A1) is a composition obtained by reacting xylylenediamine with an alkylene oxide in a molar ratio of 1 / 0.2 to 1 / 4.

9. An epoxy resin composition comprising an epoxy resin and the epoxy resin curing agent according to any one of claims 1 to 8.

10. The epoxy resin composition according to claim 9, further comprising a non-reactive diluent.

11. The epoxy resin composition according to claim 10, wherein the content of the non-reactive diluent in the epoxy resin composition is 1 to 60 mass %.

12. A cured product of the epoxy resin composition according to any one of claims 9 to 11.

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