Curing agent for aqueous epoxy resin, aqueous epoxy resin composition, and cured product thereof

Abstract

Provided are: a curing agent for aqueous epoxy resin, containing a reaction composition (A) containing a reaction product of a compound represented by general formula (1) and an alkylene oxide; an aqueous epoxy resin composition containing the curing agent; and a cured product thereof.　(1): H2N-CH2-X-CH2-NH2 (In formula (1), X is a single bond or 1-6 C divalent hydrocarbon group).

Description

Curing agent for water-based epoxy resin, water-based epoxy resin composition and cured product thereof

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

[0002] Polyamines and compounds obtained by addition reactions of polyamines with alkenyl compounds, epoxy compounds, etc. are known to be useful as epoxy resin curing agents. Epoxy resin compositions using these epoxy resin curing agents are widely used in the fields of coatings, such as anticorrosion coatings for ships, bridges, and onshore and offshore steel structures; in the fields of civil engineering and construction, such as linings, reinforcements, crack repair materials, sealants, injection materials, primers, screeds, top coats, and FRP reinforcements for concrete structures, building flooring materials, water and sewerage linings, paving materials, and adhesives; in the fields of electrical and electronics, such as die attach materials and insulating sealants; and in the field of fiber-reinforced plastics.

[0003] In the paint industry, there has been a recent trend to reduce volatile organic compounds (VOCs), leading to growing interest in water-based paints, which use water as the main diluent.

[0004] It is known that a water-soluble polyamine is used as an epoxy resin curing agent in an aqueous epoxy resin composition suitable for use as a water-based paint. For example, Patent Document 1 discloses that an aqueous epoxy resin composition containing a water-based epoxy resin and a curing agent composition containing a reaction product of epichlorohydrin and a specified amine compound in a specified ratio has good workability and provides a coating film with excellent adhesion and chemical resistance, particularly excellent saltwater corrosion resistance.

[0005] International Publication No. 2020 / 110601

[0006] However, the water-soluble curing agent composition described in Patent Document 1 has been found to have a problem in that a sufficient pot life cannot be obtained in the aqueous epoxy resin composition obtained by mixing the water-soluble curing agent composition with the epoxy resin as the main component.

[0007] An object of the present invention is to provide a curing agent for aqueous epoxy resins that can prepare aqueous epoxy resin compositions having a long pot life, an aqueous epoxy resin composition containing the curing agent, and a cured product thereof.

[0008] The present inventors have found that a curing agent for aqueous epoxy resins containing an amine component having a specific structure can solve the above problems. That is, the present invention relates to the following: [1] A curing agent for aqueous epoxy resins containing a reaction composition (A) containing a reaction product of a compound represented by the following general formula (1) and an alkylene oxide. ２ N-CH ２ -X-CH ２ -NH ２ (1) (In formula (1), X is a single bond or a divalent hydrocarbon group having 1 to 6 carbon atoms.) [2] The curing agent for aqueous epoxy resins according to [1], wherein X in general formula (1) is a single bond or a phenylene group. [3] The curing agent for aqueous epoxy resins according to [1] or [2], wherein the alkylene oxide comprises ethylene oxide. [4] The curing agent for aqueous epoxy resins according to any one of [1] to [3], wherein the reaction composition (A) is water-soluble. [5] The curing agent for aqueous epoxy resins according to any one of [1] to [4], wherein the content of the reaction composition (A) in the curing agent for aqueous epoxy resins is 50 mass% or more. [6] The curing agent for aqueous epoxy resins according to any one of [1] to [5], wherein the reaction composition (A) is a composition obtained by reacting a compound represented by general formula (1) with an alkylene oxide in a molar ratio of 1 / 0.2 to 1 / 3. [7] An aqueous epoxy resin composition comprising an aqueous epoxy resin and the curing agent for aqueous epoxy resins described in any one of [1] to [6]. [8] The aqueous epoxy resin composition according to [7], wherein the aqueous epoxy resin comprises an epoxy resin emulsion. [9] A cured product of the aqueous epoxy resin composition according to [7] or [8].

[0009] According to the present invention, there are provided a curing agent for aqueous epoxy resins that can prepare aqueous epoxy resin compositions having a long pot life, an aqueous epoxy resin composition containing the curing agent, and a cured product thereof.

[0010] [Definition] In this specification, the term "curing agent for aqueous epoxy resins" refers to a curing agent for curing aqueous epoxy resins. The term "aqueous epoxy resin" refers to the main component of an aqueous epoxy resin composition, and includes a water-soluble epoxy resin or an epoxy resin used in the form of an aqueous dispersion (emulsion). The aqueous epoxy resin used in the present invention is preferably an epoxy resin emulsion. In this specification, the term "aqueous epoxy resin composition" refers to an epoxy resin composition containing at least an aqueous epoxy resin as the main component and an aqueous epoxy resin curing agent for curing the aqueous epoxy resin, and the water content is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and even more preferably 30% by mass or more.

[0011] In this specification, the term "reaction composition containing a reactant of X and Y" refers to a composition obtained by reacting X and Y, which contains not only the reactant of X and Y (addition reactant), but also by-products other than the reactant, and unreacted raw materials such as X and Y.

[0012] [Curing Agent for Waterborne Epoxy Resins] The curing agent for waterborne epoxy resins of the present invention (hereinafter also referred to simply as "curing agent (of the present invention)") contains a reaction composition (A) containing a reaction product of a compound represented by the following general formula (1) and an alkylene oxide. ２ N-CH ２ -X-CH ２ -NH ２ (1) (In formula (1), X is a single bond or a divalent hydrocarbon group having 1 to 6 carbon atoms.) By having the above-mentioned structure, the curing agent of the present invention exhibits the effect of being able to prepare an aqueous epoxy resin composition having a long pot life.

[0013] The reason why the above-mentioned effects are obtained in the present invention is not clear, but it is thought to be as follows. The reaction composition used as component (A) is an amine composition containing an alkylene oxide modified product of the compound (diamine) represented by the general formula (1) above, and acts as an amine-based epoxy resin curing agent. Here, the reactant contained in the reaction composition (A) has a hydroxy group at the terminal. For example, an addition reaction product obtained by reacting the compound represented by the general formula (1) above with ethylene oxide in a molar ratio of 1:1 is represented by the following general formula (1'): H ２ N-CH ２ -X-CH ２ -NH-CH ２ -CH ２ OH (1') (In formula (1'), X is the same as defined above.) Similarly, an addition reaction product obtained by reacting a compound represented by the general formula (1) with an alkylene oxide in a molar ratio of 1:2 or 1:3 also functions as an epoxy resin curing agent and has a terminal hydroxy group. Since the reactant contained in reaction composition (A) is a compound having a hydroxy group, when the above-mentioned epoxy resin emulsion is used as the aqueous epoxy resin (main component), the curing agent of the present invention is likely to exist in the aqueous phase, which is the continuous phase, of the emulsion and is less likely to dissolve in the oil phase, which is the discontinuous phase. Therefore, the emulsion state is not easily destroyed even when the curing agent of the present invention is mixed with the epoxy resin emulsion, and it is therefore believed that an aqueous epoxy resin composition with a long pot life can be prepared.

[0014] <Reaction Composition (A)> The reaction composition (A) is a composition containing a reaction product of a compound represented by the following general formula (1) and an alkylene oxide: ２ N-CH ２ -X-CH ２ -NH ２(1) (In formula (1), X is a single bond or a divalent hydrocarbon group having 1 to 6 carbon atoms.) In this specification, "a reaction product of a compound represented by general formula (1) and an alkylene oxide" means an addition reaction product (adduct) of a compound represented by general formula (1) with an alkylene oxide. The reaction product of a compound represented by general formula (1) with an alkylene oxide includes not only an addition reaction product of 1 mole of a compound represented by general formula (1) with 1 mole of an alkylene oxide (hereinafter also referred to as a 1:1 adduct), but also multi-adducts such as a 1:2 adduct and a 1:3 adduct of a compound represented by general formula (1) with an alkylene oxide. Furthermore, the "reaction composition (A) containing a reaction product of a compound represented by general formula (1) and an alkylene oxide" is a reaction product obtained by reacting a compound represented by general formula (1) with an alkylene oxide, and may contain unreacted raw materials such as the compound represented by general formula (1) in addition to the adduct.

[0015] From the viewpoint of improving curability, the reaction composition (A) preferably contains a 1:1 adduct of a compound represented by the general formula (1) and an alkylene oxide. Furthermore, from the viewpoint of improving the pot life of the resulting aqueous epoxy resin composition, the ClogP of the 1:1 adduct of a compound represented by the general formula (1) and an alkylene oxide is preferably 0 or less, more preferably −0.05 or less, and even more preferably −0.1 or less. The lower limit is not particularly limited, but is typically −3.0 or greater. ClogP is a parameter calculated by taking into account the contribution of fragments in the compound to the octanol / water partition coefficient (logP), and a smaller ClogP value indicates higher hydrophilicity. ClogP is the ClogP value displayed in the chemical properties window when drawing a compound's structural formula using the chemical structure drawing software "Chem Draw 20.0."

[0016] The reaction composition (A) is preferably water-soluble from the viewpoint of use as a curing agent for aqueous epoxy resins and from the viewpoint of improving the pot life of the resulting aqueous epoxy resin composition. In other words, a water-soluble reaction composition (A) is distinguished from an aqueous epoxy resin curing agent used in the form of an aqueous dispersion. Here, "water-soluble" means that the reaction composition (A) is soluble in water at room temperature (25°C) in an amount of preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, still more preferably 40% by mass or more, and even more preferably 50% by mass or more.

[0017] (Compound Represented by General Formula (1)) In the compound represented by the general formula (1), X is a single bond or a divalent hydrocarbon group having 1 to 6 carbon atoms. The divalent hydrocarbon group having 1 to 6 carbon atoms is preferably at least one selected from the group consisting of a linear alkylene group having 1 to 6 carbon atoms, a branched alkylene group having 2 to 6 carbon atoms, a cycloalkylene group having 4 to 6 carbon atoms, and a phenylene group. Examples of linear alkylene groups having 1 to 6 carbon atoms include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group. Examples of branched alkylene groups having 2 to 6 carbon atoms include an ethylidene group, a propylene group, a propylidene group, an isopropylidene group, a butylene group, and an isobutylidene group. Examples of cycloalkylene groups having 4 to 6 carbon atoms include a cyclobutylene group, a cyclopentylene group, and a cyclohexylene group.

[0018] Among the above, from the viewpoint of improving the pot life of the resulting aqueous epoxy resin composition, X in the general formula (1) is preferably a single bond, a linear alkylene group having 1 to 6 carbon atoms, a cyclohexylene group, or a phenylene group, more preferably a single bond, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a cyclohexylene group, or a phenylene group, even more preferably a single bond or a phenylene group, still more preferably a single bond, a 1,3-phenylene group, or a 1,4-phenylene group, and from the viewpoint of improving the pot life of the resulting aqueous epoxy resin composition and the drying speed of the coating film, still more preferably a 1,3-phenylene group or a 1,4-phenylene group.

[0019] That is, the compound represented by the general formula (1) preferably contains at least one selected from the group consisting of ethylenediamine, triethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, bis(aminomethyl)cyclohexane, and xylylenediamine, more preferably contains at least one selected from the group consisting of ethylenediamine and xylylenediamine, even more preferably contains at least one selected from the group consisting of ethylenediamine, metaxylylenediamine, and paraxylylenediamine, and still more preferably contains at least one selected from the group consisting of metaxylylenediamine and paraxylylenediamine. One or more types of the compound represented by the general formula (1) can be used.

[0020] (Alkylene Oxide) From the viewpoint of improving the pot life of the resulting aqueous epoxy resin composition, the alkylene oxide preferably includes an alkylene oxide having 2 to 6 carbon atoms, more preferably includes an alkylene oxide having 2 to 4 carbon atoms, even more preferably includes at least one selected from the group consisting of ethylene oxide and propylene oxide, even more preferably includes ethylene oxide, and even more preferably is ethylene oxide. One or more alkylene oxides can be used.

[0021] In the reaction composition (A), the reaction molar ratio of the compound represented by the general formula (1) to the alkylene oxide is not particularly limited, so long as the reaction composition (A) has a sufficient amount of active hydrogen derived from amino groups to function as an epoxy resin curing agent. From the viewpoints of improving curability, the pot life of the resulting aqueous epoxy resin composition, and the drying speed of the coating film, the reaction composition (A) is a composition obtained by reacting the compound represented by the general formula (1) with the alkylene oxide in a molar ratio (compound represented by the general formula (1) / alkylene oxide) of preferably 1 / 0.2 to 1 / 3, more preferably 1 / 0.2 to 1 / 2.5, 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.

[0022] Reaction composition (A) can be produced by reacting a compound represented by general formula (1) with an alkylene oxide under heated conditions. For example, the compound represented by general formula (1) is charged into a reaction vessel, and while stirring, the 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 (A) as is. If necessary, the reaction liquid may be purified by distillation to remove unreacted materials before use as reaction composition (A).

[0023] From the viewpoint of improving the pot life of the resulting aqueous epoxy resin composition, the content of the compound represented by the general formula (1) in the reaction composition (A) is preferably 35% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less, even more preferably 20% by mass or less, and even more preferably 15% by mass or less. The lower limit is not particularly limited and may be 0% by mass. Note that the "content of the compound represented by the general formula (1) in the reaction composition (A)" here refers to the content of the compound represented by the general formula (1) as an unreacted raw material in the reaction composition (A). The content of the compound represented by the general formula (1) in the reaction composition (A) can be measured by gas chromatography (GC) analysis, specifically by the method described in the Examples.

[0024] From the viewpoint of improving the pot life of the resulting aqueous epoxy resin composition, the active hydrogen equivalent (AHEW) of the reaction composition (A) is preferably 35 or more, more preferably 40 or more, and even more preferably 50 or more. From the viewpoint of improving the drying speed of a coating film of the resulting aqueous epoxy resin composition, the active hydrogen equivalent (AHEW) is preferably 100 or less, more preferably 90 or less. The active hydrogen equivalent (hereinafter also referred to as "AHEW") of the reaction composition (A) is the mass per mole of active hydrogen derived from amino groups in the reaction composition (A), and can be calculated, for example, from the amine value determined by titration.

[0025] The curing agent for aqueous epoxy resins of the present invention may contain a curing agent component other than the reaction composition (A). Examples of such curing agent components include compounds having two or more active hydrogen-containing groups capable of reacting with the epoxy groups in the base resin used in the aqueous epoxy resin composition. Examples of such curing agent components include amine-based curing agents other than the reaction composition (A), phenol-based curing agents, acid anhydride-based curing agents, and hydrazide-based curing agents.

[0026] However, from the viewpoint of improving the pot life of the resulting aqueous epoxy resin composition and the drying speed of the coating film, the content of reaction composition (A) in the aqueous epoxy resin curing agent 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, and still more preferably 95% by mass or more, but not more than 100% by mass. The content of reaction composition (A) in the aqueous epoxy resin curing agent means the content of reaction composition (A) in all curing agent components contained in the aqueous epoxy resin curing agent, and the curing agent components contained in the aqueous epoxy resin curing agent mean components contained in the curing agent that have two or more active hydrogens capable of reacting with epoxy groups in the epoxy resin.

[0027] The active hydrogen equivalent weight (AHEW) of the curing agent for aqueous epoxy resins of the present invention is preferably 35 or more, more preferably 40 or more, and even more preferably 50 or more, from the viewpoint of improving the pot life of the resulting aqueous epoxy resin composition. Also, from the viewpoint of improving the drying speed of the coating film of the resulting aqueous epoxy resin composition, it is preferably 150 or less, more preferably 120 or less, even more preferably 100 or less, and even more preferably 90 or less.

[0028] [Water-based Epoxy Resin Composition] The present invention provides a water-based epoxy resin composition containing a water-based epoxy resin and the curing agent for the water-based epoxy resin.

[0029] <Water-Based Epoxy Resin> Water-based epoxy resins are the main component of water-based epoxy resin compositions, and examples include water-soluble epoxy resins and epoxy resin emulsions. As described above, water-based epoxy resins preferably include epoxy resin emulsions. Epoxy resin emulsions are emulsions containing at least an epoxy resin and water. In the following description and examples, water-based epoxy resins or epoxy resin emulsions may be simply referred to as "main component." Examples of epoxy resin emulsions include those in which an epoxy resin is emulsified and dispersed in water. Both self-emulsifying and non-self-emulsifying epoxy resins can be used as the epoxy resin. When a non-self-emulsifying epoxy resin is used, for example, the epoxy resin emulsion can be prepared by dispersing the non-self-emulsifying epoxy resin in water in the presence of an emulsifier. The epoxy resins used in the epoxy resin emulsions are described below.

[0030] (Epoxy Resin) The epoxy resin in the epoxy resin emulsion may have an epoxy group that reacts with the active hydrogen of the curing agent component in the aqueous epoxy resin curing agent. From the viewpoint of preparing an aqueous epoxy resin composition with a long pot life and improving the water resistance, hardness, etc. of the resulting coating film, the epoxy resin in the epoxy resin emulsion preferably contains a solid epoxy resin, more preferably a solid epoxy resin having an aromatic ring or an alicyclic structure in the molecule. The solid epoxy resin referred to here is an epoxy resin that is solid at 25°C.

[0031] Preferred examples of epoxy resins used in the epoxy resin emulsion include at least one selected from the group consisting of epoxy resins having a glycidylamino group derived from metaxylylenediamine, epoxy resins having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane, epoxy resins having a glycidylamino group derived from diaminodiphenylmethane, epoxy resins having a glycidylamino group and a glycidyloxy group derived from paraaminophenol, 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, epoxy resins having a glycidyloxy group derived from hydrogenated bisphenol F, epoxy resins having a glycidyloxy group derived from phenol novolac, and epoxy resins having a glycidyloxy group derived from resorcinol. The above epoxy resins may be used alone or in combination of two or more.

[0032] Among the above, from the viewpoint of preparing an aqueous epoxy resin composition having a long pot life, the epoxy resin preferably comprises at least one selected from the group consisting of an epoxy resin having a glycidylamino group derived from meta-xylylenediamine, an epoxy resin having a glycidyloxy group derived from bisphenol A, and an epoxy resin having a glycidyloxy group derived from bisphenol F, more preferably at least one selected from the group consisting of an epoxy resin having a glycidyloxy group derived from bisphenol A and an epoxy resin having a glycidyloxy group derived from bisphenol F, and even more preferably an epoxy resin having a glycidyloxy group derived from bisphenol A.

[0033] The epoxy equivalent of the epoxy resin used in the epoxy resin emulsion is preferably 150 g / equivalent or more, more preferably 200 g / equivalent or more, from the viewpoint of preparing an aqueous epoxy resin composition with a long pot life, and is preferably 1000 g / equivalent or less, more preferably 800 g / equivalent or less, even more preferably 800 g / equivalent or less, and still more preferably 600 g / equivalent or less, from the viewpoint of the curability of the resulting aqueous epoxy resin composition. Here, the "epoxy equivalent of the epoxy resin" means the epoxy equivalent of the epoxy resin alone contained in the emulsion.

[0034] The content of the epoxy resin in the epoxy resin emulsion is not particularly limited, but is preferably 30% by mass or more, more preferably 35% by mass or more, and from the viewpoint of emulsion stability, is preferably 80% by mass or less.

[0035] (Emulsifier) ​​The epoxy resin emulsion may further contain an emulsifier. The emulsifier used in the epoxy resin emulsion is not particularly limited as long as it is capable of emulsifying the epoxy resin. Any of nonionic emulsifiers, anionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers, and reactive emulsifiers having a reactive group such as an epoxy group can be used. Among the above, from the viewpoint of preparing an aqueous epoxy resin composition having a long pot life using the curing agent composition of the present invention, the emulsifier used in the epoxy resin emulsion preferably includes at least one selected from the group consisting of nonionic emulsifiers not having a reactive group such as an epoxy group and anionic emulsifiers, and more preferably includes a nonionic emulsifier not having a reactive group. Examples of the nonionic emulsifier include polyether compounds, ester compounds, and alkanolamide compounds. The emulsifiers can be used alone or in combination of two or more.

[0036] When the epoxy resin emulsion contains an emulsifier, the content of the emulsifier in the epoxy resin emulsion is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 30 parts by mass, and even more preferably 1 to 20 parts by mass, per 100 parts by mass of the epoxy resin. When the content of the emulsifier is 0.1 part by mass or more per 100 parts by mass of the epoxy resin, the emulsion stability is improved, and when it is 40 parts by mass or less, the water resistance and other properties of the resulting aqueous epoxy resin composition can be maintained well.

[0037] (Water) The content of water in the epoxy resin emulsion is not particularly limited, but from the viewpoint of emulsion stability and improved handleability, it is preferably 15 to 80 mass %, more preferably 20 to 70 mass %, and even more preferably 25 to 60 mass %.

[0038] As the epoxy resin emulsion, commercially available products such as "Araldite PZ 3961-1" (a water-based emulsion of a solid epoxy resin having a glycidyloxy group derived from bisphenol A) manufactured by HUNTSMAN Advanced Materials can also be used.

[0039] The aqueous epoxy resin composition of the present invention is obtained by blending and mixing an aqueous epoxy resin (preferably an epoxy resin emulsion) as a main component with an aqueous epoxy resin curing agent. The blending ratio of the main component to the curing agent is such that the number of active hydrogen atoms in the curing agent relative to the number of epoxy groups in the main component (number of active hydrogen atoms in the curing agent / number of epoxy groups in the main component) is preferably 0.5 / 1 to 2 / 1, more preferably 0.6 / 1 to 1.5 / 1, even more preferably 0.6 / 1 to 1.2 / 1, still more preferably 0.6 / 1 to 1 / 1, and even more preferably 0.6 / 1 to 0.9 / 1.

[0040] <Contents> The contents of each component in the aqueous epoxy resin composition are preferably within the following ranges: From the viewpoint of improving curability and preparing an aqueous epoxy resin composition with a long pot life, the content of reaction composition (A) in the aqueous epoxy resin composition is preferably 1 to 20% by mass, more preferably 2 to 20% by mass, even more preferably 2 to 18% by mass, still more preferably 2 to 15% by mass, still more preferably 2 to 12% by mass, still more preferably 3 to 12% by mass, still more preferably 3 to 10% by mass, and still more preferably 5 to 10% by mass.

[0041] From the viewpoint of improving curability and preparing an aqueous epoxy resin composition with a long pot life, the content of the aqueous epoxy resin curing agent in the aqueous epoxy resin composition is preferably 1 to 25% by mass, more preferably 2 to 20% by mass, even more preferably 2 to 18% by mass, still more preferably 2 to 15% by mass, still more preferably 2 to 12% by mass, still more preferably 3 to 12% by mass, still more preferably 3 to 10% by mass, and still more preferably 5 to 10% by mass. The "content of the aqueous epoxy resin curing agent" referred to here also includes the content of reaction composition (A).

[0042] The content of the aqueous epoxy resin (main component) in the aqueous epoxy resin composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, even more preferably 30 to 55% by mass, and still more preferably 35 to 55% by mass, from the viewpoint of improving curability and preparing an aqueous epoxy resin composition having a long pot life.

[0043] Of the non-volatile components in the aqueous epoxy resin composition, the total content of the aqueous epoxy resin curing agent, the epoxy resin in the base resin, and the emulsifier is preferably 10 to 90% by mass, more preferably 15 to 85% by mass, even more preferably 20 to 80% by mass, and still more preferably 30 to 70% by mass, from the viewpoint of preparing an aqueous epoxy resin composition having a long pot life.

[0044] The water content in the aqueous epoxy resin composition is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and even more preferably 30% by mass or more. The upper limit of the water content can be adjusted as appropriate, but is usually 90% by mass or less, preferably 80% by mass or less, and more preferably 70% by mass or less. The water content here refers to the total amount of water contained in the aqueous epoxy resin composition.

[0045] <Other Components> The aqueous epoxy resin composition may further contain other components such as pigments, fillers other than pigments, modifying components such as plasticizers, flow-adjusting components such as thixotropic agents, leveling agents, dispersants, antifoaming agents, and tackifiers depending on the intended use.

[0046] Although the aqueous epoxy resin composition of the present invention does not exclude the inclusion of an organic solvent, it is preferable that the content of the organic solvent in the aqueous epoxy resin composition is small. The content of the organic solvent in the aqueous epoxy resin composition is preferably less than 10% by mass, more preferably 8% by mass or less, and even more preferably 7% by mass or less.

[0047] <Method for producing aqueous epoxy resin composition> The method for producing the aqueous epoxy resin composition of the present invention is not particularly limited as long as it includes a step of mixing an aqueous epoxy resin and an aqueous epoxy resin curing agent, and the composition can be produced using a known mixing device or mixing method.

[0048] [Cured Product] The present invention provides a cured product of the aqueous epoxy resin composition. The cured product is obtained by curing the aqueous epoxy resin composition by a known method. The curing conditions for the aqueous epoxy resin composition are appropriately selected depending on the application and form. The form of the cured product is also not particularly limited and can be selected depending on the application. For example, when the aqueous epoxy resin composition is a paint, the cured product is usually a film-like cured product.

[0049] <Paint> The present invention can provide a paint containing the aqueous epoxy resin composition. By including the aqueous epoxy resin composition, the paint has a long pot life and excellent workability. Examples of such paints include anticorrosion paints, marine paints, tank paints, paints for pipe interiors, exterior paints, and flooring paints. Anticorrosion paints are used, for example, for painting ships, bridges, buildings such as factories, and other iron structures on land and sea.

[0050] The content of the aqueous epoxy resin composition in the coating material 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 may be 100% by mass.

[0051] <Applications> In addition to the above-mentioned coating materials, the aqueous epoxy resin composition of the present invention can be suitably used for adhesives, flooring materials, sealants, polymer cement mortars, gas barrier coatings, primers, screeds, top coats, sealants, crack repair materials, concrete materials, etc.

[0052] 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. Analysis of reaction composition (A) was carried out by the following method.

[0053] (Content of Compound Represented by General Formula (1) (Unreacted Polyamine) in Reaction Composition) 0.10 g of the reaction composition obtained in each Production Example and 0.03 g of diphenyl ether (manufactured by Kanto Chemical Co., Inc.) as an internal standard were weighed out and diluted with 1.5 g of methanol to prepare a measurement sample. The sample was analyzed using a gas chromatography (GC) analyzer under the following conditions, and the content of unreacted polyamine in the reaction composition was calculated from the GC area values ​​of the polyamine and the internal standard. [GC measurement conditions] Apparatus: "7890B GC" manufactured by Agilent Technologies, Inc. Column: "CP-Sil 8 CB for Amines" manufactured by Agilent Technologies, Inc. (length 30 m, film thickness 0.25 μm, inner diameter 0.25 mm) Column temperature: 40°C for 10 minutes → 20°C / minute temperature increase → 250°C for 10 minutes → 20°C / minute temperature increase → 300°C for 10 minutes Carrier gas: Helium carrier gas Flow rate: 2.2553 mL / min Injection port pressure: 22.474 psi (constant pressure mode) Detector: FID Injection port temperature: 250°C Detector temperature: 310°C

[0054] 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 allow the reaction to proceed, thereby obtaining reaction composition (A1). Reaction composition (A1) contained a reaction product represented by the following structural formula (a 1:1 adduct of metaxylylenediamine and ethylene oxide, ClogP = -0.1302), and the active hydrogen equivalent (AHEW) derived from the amino groups of reaction composition (A1) was 60, and the metaxylylenediamine content in reaction composition (A1) was 26% by mass.

[0055] Production Example 2 (Distillation Purification Product of Reaction Composition (A1) Obtained in Production Example 1 (Production of Reaction Composition (A2)) The reaction composition (A1) obtained in Production Example 1 was distilled and purified by 5-stage precision distillation, and unreacted meta-xylylenediamine was distilled off to obtain a reaction composition (A2). The active hydrogen equivalent (AHEW) derived from amino groups of the reaction composition (A2) was 86, and the content of unreacted meta-xylylenediamine in the reaction composition (A2) was 0 mass%.

[0056] Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-4 (Preparation of aqueous curing agent solutions for aqueous epoxy resins) Aqueous curing agent solutions for aqueous epoxy resins were prepared by blending, stirring, and mixing the curing agent and water in the amounts shown in Table 1. The blending amount (mass %) in Table 1 means the amount of active ingredient.

[0057]

[0058] Details of the curing agents used in Example 1-3 and Comparative Examples 1-1 to 1-4 are shown below: 2-(2-aminoethylamino)ethanol (A3): Compound represented by the following structural formula (a reaction product of ethylenediamine and ethylene oxide in a molar ratio of 1 / 1), manufactured by Tokyo Chemical Industry Co., Ltd., AHEW: 35, ClogP: -2.3616 Metaxylylenediamine: MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd., AHEW: 34, ClogP: 0.046 Reaction product of metaxylylenediamine and epichlorohydrin: Gaskamine 328, manufactured by Mitsubishi Gas Chemical Co., Ltd., AHEW: 55, 1:1 adduct of metaxylylenediamine and epichlorohydrin, ClogP: 0.2836 1,3-bis(aminomethyl)cyclohexane: 1,3-BAC, manufactured by Mitsubishi Gas Chemical Co., Ltd., AHEW: 35.6, ClogP: 0.618 Ethylenediamine: Tokyo Chemical Industry Co., Ltd., AHEW: 15, ClogP: -2.022

[0059] Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-9 (Preparation and Evaluation of Waterborne Epoxy Resin Compositions) The curing agents or curing agent aqueous solutions listed in Table 2 were used, and "Araldite PZ 3961-1" (a waterborne emulsion of a solid epoxy resin having glycidyloxy groups derived from bisphenol A, manufactured by HUNTSMAN Advanced Materials, epoxy equivalent (solid content): 503 g / equivalent, solid content concentration: 53% by mass, water content: 40% by mass, methoxypropanol content: 7% by mass) was used as the base. Each component listed in Table 2 was weighed into a 100 mL disposable cup and mixed with a wooden spatula for approximately 2 minutes under conditions of 23°C / 50% RH or 40°C / 40% RH to prepare a waterborne epoxy resin composition. The blend amounts (mass%) in Table 2 refer to the blend amounts as they are. The resulting aqueous epoxy resin compositions were evaluated by the following methods, and the results are shown in Table 2.

[0060] (Pot Life) Waterborne epoxy resin compositions were prepared by the above method under conditions of 23°C / 50% RH or 40°C / 40% RH. The waterborne epoxy resin compositions were then applied every 30 minutes using the following method and allowed to dry under the same temperature and humidity conditions as above. Evaluation was terminated when the dried coating cracked and film formation became impossible, or when the waterborne epoxy resin composition thickened so much that coating became impossible. The pot life was measured 30 minutes before the end of evaluation and is shown in Table 2. [Coating Method] The waterborne epoxy resin composition was dropped onto a zinc phosphate-treated steel plate ("SPCC-SD PB-N144 Φ5-1" manufactured by Paltec Co., Ltd., 70 mm x 150 mm x 0.8 mm thick) and applied using a 200 μm applicator.

[0061] (Dryness to Touch) The same zinc phosphate-treated steel sheet (manufactured by Paltec Co., Ltd.) as above was used as the substrate. The aqueous epoxy resin composition was applied to the substrate using an applicator under conditions of 23°C / 50% RH to form a coating film (coating film thickness immediately after application: 200 μm). This coating film was left to stand under conditions of 23°C / 50% RH, and after 1, 2, and 10 days, the dryness to touch was evaluated by touching with a finger 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)

[0062]

[0063] Details of the curing agents used in Comparative Examples 2-7 to 2-8 are shown below: Reaction product of metaxylylenediamine and styrene: "Gaskamine 240" manufactured by Mitsubishi Gas Chemical Company, Inc., AHEW: 103, 1:1 adduct of metaxylylenediamine and styrene, ClogP: 2.559. Note that, since Gaskamine 240 is water-insoluble, no aqueous curing agent solution was prepared, and it was directly blended into the waterborne epoxy resin compositions of Comparative Examples 2-7 to 2-8.

[0064] It can be seen from Table 2 that the aqueous epoxy resin compositions using the aqueous epoxy resin curing agents of this Example have a longer pot life than the aqueous epoxy resin compositions of Comparative Examples. Furthermore, a comparison of Examples 2-3 and 2-4, Examples 2-5 and 2-6, and Comparative Example 2-9 reveals that the aqueous epoxy resin compositions of Examples 2-3 and 2-4 are the most advantageous in terms of pot life (40°C / 40% RH) and tack-dry rate.

[0065] According to the present invention, there are provided a curing agent for aqueous epoxy resins that can prepare aqueous epoxy resin compositions having a long pot life, an aqueous epoxy resin composition containing the curing agent, and a cured product thereof.

Claims

1. A curing agent for water-based epoxy resins, comprising a reaction composition (A) containing a reaction product of a compound represented by the following general formula (1) and an alkylene oxide: ２ N-CH ２ -X-CH ２ -NH ２ (1) (In formula (1), X is a single bond or a divalent hydrocarbon group having 1 to 6 carbon atoms.) 2. The curing agent for waterborne epoxy resins according to claim 1, wherein X in the general formula (1) is a single bond or a phenylene group.

3. The curing agent for waterborne epoxy resins according to claim 1 or 2, wherein the alkylene oxide comprises ethylene oxide.

4. The curing agent for water-based epoxy resins according to any one of claims 1 to 3, wherein the reaction composition (A) is water-soluble.

5. The aqueous epoxy resin curing agent according to any one of claims 1 to 4, wherein the content of the reaction composition (A) in the aqueous epoxy resin curing agent is 50 mass% or more.

6. The curing agent for aqueous epoxy resins according to any one of claims 1 to 5, wherein the reaction composition (A) is a composition obtained by reacting the compound represented by general formula (1) with an alkylene oxide in a molar ratio of 1 / 0.2 to 1 / 3.

7. A water-based epoxy resin composition comprising a water-based epoxy resin and the curing agent for water-based epoxy resins according to any one of claims 1 to 6.

8. The water-based epoxy resin composition of claim 7, wherein the water-based epoxy resin comprises an epoxy resin emulsion.

9. A cured product of the aqueous epoxy resin composition according to claim 7 or 8.

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