Emulsion-type epoxy resin curing agent composition and aqueous epoxy resin composition

Abstract

Provided is an emulsion-type epoxy resin curing agent composition that contains component (A): a reaction composition obtained by means of a Mannich reaction of 1 mol of xylylenediamine (a1) with more than 1 mol to less than 1.5 mol of at least one compound (a2) selected from the group consisting of phenols and phenol compounds having an alkyl group having no more than 3 carbon atoms and more than 1 mol to less than 1.5 mol of an aldehyde compound (a3), component (B): a nonionic emulsifier having an HLB value of 14.0 or more and having an aromatic ring, component (C): a cosolvent, and water. Also provided is an aqueous epoxy resin composition that includes said composition.

Description

Technical Field

[0001] The present invention relates to an emulsion-type epoxy resin curing agent composition and an aqueous epoxy resin composition containing the epoxy resin curing agent composition.

Background Art

[0002] Polyamines and compounds obtained by an addition reaction of a polyamine with an alkenyl compound, an epoxy compound, etc. are known to be useful as epoxy resin curing agents. Epoxy resin compositions using these epoxy resin curing agents are used in various fields such as the paint field such as anticorrosive paints for ships, bridges, and land and sea iron structures, lining, reinforcement, crack repair materials, sealing materials, injection materials, primers, screeds, topcoats, and FRP reinforcement for concrete structures, floor materials for buildings, lining of sewers and water supply systems, paving materials, adhesives, etc. in the civil engineering and construction fields, die attach materials, insulating encapsulants, etc. in the electrical and electronic fields, and fiber reinforced plastics fields.

[0003] In recent years, in the paint field, there has been a movement to reduce volatile organic compounds (VOCs), so the interest in waterborne paints has been increasing. Waterborne paints use water as the main component of the paint diluent.

[0004] In an aqueous epoxy resin composition suitable as a waterborne paint, it is known to use a water-soluble polyamine as an epoxy resin curing agent. For example, Patent Document 1 discloses that an aqueous epoxy resin composition prepared by blending an aqueous epoxy resin and a curing agent composition containing a reaction product of epichlorohydrin and a predetermined amine compound in a predetermined ratio has good workability and excellent adhesion and chemical resistance of the coating film, particularly saltwater corrosion resistance. However, since the reaction product contained in the above curing agent composition is water-soluble, there is a limit to improving the water resistance of the coating film.

[0005] Therefore, emulsion-type curing agents, in which a water-insoluble polyamine-based curing agent is dispersed in water, are also known as curing agents for water-based epoxy resins (see, for example, Patent Documents 2-4). Generally, emulsion-type curing agents are required to have good emulsification stability in addition to curing performance. Patent Document 2 discloses a method for producing a curing agent suitable for curing an aqueous epoxy resin emulsion, characterized by condensing xylylenediamine, aldehydes having 1 to 3 carbon atoms, and phenols having hydrocarbon groups with 4 or more carbon atoms as essential components, and then forming an aqueous emulsion from the mixture. It is also stated that the curing agent exhibits excellent stability, curability, chemical resistance, coating film performance, and the like. Patent Document 3 discloses an aqueous dispersion of a modified polyamine containing a nonionic emulsifier that includes a block copolymer of polyethylene glycol and polypropylene glycol, and demonstrates that the dispersion has good emulsification stability. Patent Document 4 discloses an emulsifier composition mainly composed of a compound obtained by reacting a predetermined polyamide with a predetermined reactive organic compound, and a curing agent composition for epoxy resins containing the emulsifier composition. It is stated that these emulsifier compositions and curing agent compositions for epoxy resins exhibit good dispersibility and storage stability when used to prepare aqueous epoxy resin compositions, and that the cured products have excellent properties such as water resistance. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2020 / 110601 [Patent Document 2] Japanese Unexamined Patent Publication No. 48-78254 [Patent Document 3] Japanese Patent Publication No. 2005-187757 [Patent Document 4] Japanese Patent Publication No. 2007-91976 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the emulsion-type curing agents described in Patent Documents 2 to 4 did not provide sufficient low-temperature curing properties for the aqueous epoxy resin composition obtained after mixing with the main epoxy resin, nor did they provide sufficient water resistance for the coating film after low-temperature curing. The object of the present invention is to provide an emulsion-type epoxy resin curing agent composition that can prepare an aqueous epoxy resin composition having good emulsifying properties, good low-temperature curing properties, and good water resistance of the coating film after low-temperature curing, and an aqueous epoxy resin composition containing the emulsion-type epoxy resin curing agent composition. [Means for solving the problem]

[0008] The inventors have found that an emulsion-type epoxy resin curing agent composition containing a specific amine-based curing agent, a specific nonionic emulsifier, a co-solvent, and water can solve the above problems. In other words, the present invention relates to the following. [1] An emulsion-type epoxy resin curing agent composition comprising: (A) a reaction composition obtained by reacting 1 mole of xylylenediamine (a1) with more than 1 mole but less than 1.5 moles of at least one compound (a2) selected from the group consisting of phenols and phenol compounds having alkyl groups with 3 or fewer carbon atoms, and more than 1 mole but less than 1.5 moles of an aldehyde compound (a3) ​​in a Mannich reaction; (B) a nonionic emulsifier having an aromatic ring and an HLB value of 14.0 or higher; (C) a cosolvent; and water. [2] The emulsion-type epoxy resin curing agent composition according to [1], wherein component (B) comprises at least one selected from the group consisting of polyoxyethylene styrene-derived phenyl ether and ethylene oxide adducts of aromatic hydrocarbon formaldehyde resins. [3] The emulsion-type epoxy resin curing agent composition according to [1] or [2], comprising the above component (C) as a cosolvent having a hydroxyl group. [4] The emulsion-type epoxy resin curing agent composition according to any one of [1] to [3], wherein the content of component (A) in the emulsion-type epoxy resin curing agent composition is 10 to 60% by mass. [5] The emulsion-type epoxy resin curing agent composition according to any one of [1] to [4], wherein the content of component (B) is 0.1 to 20% by mass relative to 100% by mass of the total of component (A) and component (B). [6] The emulsion-type epoxy resin curing agent composition according to any one of [1] to [5], wherein the mass ratio of component (C) to the total mass of component (A) and component (B) is 0.01 to 3.0. [7] The emulsion-type epoxy resin curing agent composition according to any one of [1] to [6], wherein the compound (a2) comprises at least one selected from the group consisting of phenol and cresol. [8] The emulsion-type epoxy resin curing agent composition according to any one of [1] to [7], wherein the content of unreacted xylylenediamine (a1) in component (A) is 35% by mass or less. [9] The emulsion-type epoxy resin curing agent composition according to any one of [1] to [8], wherein the emulsion is an oil-in-water emulsion. A water-based epoxy resin composition obtained by mixing an emulsion-type epoxy resin curing agent composition described in any one of items

[10] [1] to [9] with an epoxy resin emulsion.

[11] The aqueous epoxy resin composition according to

[10] , wherein the epoxy resin in the epoxy resin emulsion comprises a solid epoxy resin.

[12] A method for producing the aqueous epoxy resin composition described in

[10] or

[11] , comprising the following steps (I) to (III) in order. Step (I): A step of mixing components (A), (B), and (C) to prepare mixture 1. Step (II): A step in which water is added to the mixture 1 and stirred to perform phase inversion emulsification in order to obtain an emulsion-type epoxy resin curing agent composition. Step (III): A step of mixing the emulsion-type epoxy resin curing agent composition with the epoxy resin emulsion. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an emulsion-type epoxy resin curing agent composition that can prepare an aqueous epoxy resin composition having good emulsification properties, good low-temperature curing properties, and good water resistance of the coating film after low-temperature curing, and an aqueous epoxy resin composition containing the emulsion-type epoxy resin curing agent composition. [Modes for carrying out the invention]

[0010] [Definition] In this specification, "emulsion-type epoxy resin curing agent composition" means an epoxy resin curing agent composition in the form of an emulsion (preferably an oil-in-water emulsion). Furthermore, an emulsion-type epoxy resin curing agent composition is a composition that does not contain the epoxy resin that is the main component of the epoxy resin composition. "Epoxy resin that is the main component of the epoxy resin composition" means the epoxy resin that is intentionally added as the main component of the epoxy resin composition, and does not include epoxy resin that is unintentionally mixed in as unreacted raw materials, by-products, or impurities contained in the blended components.

[0011] In this specification, "water-based epoxy resin composition" means an epoxy resin composition containing at least an epoxy resin as a main component and an epoxy resin curing agent for curing the epoxy resin, wherein 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.

[0012] In this specification, "reaction composition obtained by the Mannich reaction of X, Y, and Z" means a composition obtained by the Mannich reaction of X, Y, and Z, which includes not only the reactants of X, Y, and Z, but also by-products other than the reactants, unreacted raw materials, etc.

[0013] In this specification, the low-temperature curability of a water-based epoxy resin composition shall be determined using the dust-free time at 5°C and 80% RH as an indicator. The low-temperature curability and the water resistance of the coating film after low-temperature curing can be specifically evaluated by the methods described in the examples.

[0014] [Emulsion-type epoxy resin curing agent composition] The emulsion-type epoxy resin curing agent composition of the present invention (hereinafter, also simply referred to as “(the present invention) curing agent composition”) is Component (A): A reaction composition obtained by subjecting at least one compound (a2) selected from the group consisting of phenol and phenol compounds having an alkyl group with 3 or less carbon atoms to a Mannich reaction with more than 1 mol and less than 1.5 mol of an aldehyde compound (a3) per 1 mol of xylylenediamine (a1). Component (B): A nonionic emulsifier having an aromatic ring and having an HLB value of 14.0 or more. Component (C): A co-solvent and an emulsion-type epoxy resin curing agent composition containing water. By having the above configuration, the curing agent composition of the present invention has the effect that an aqueous epoxy resin composition having good emulsifiability, good low-temperature curability, and good water resistance of the coating film after low-temperature curing can be prepared.

[0015] Although the reason for obtaining the above effect in the present invention is not clear, it is considered as follows. The reaction composition used as component (A) is a composition obtained by subjecting at least one compound (a2) selected from the group consisting of phenol and phenol compounds having an alkyl group with 3 or less carbon atoms and an aldehyde compound (a3) to a Mannich reaction at a specific ratio per 1 mol of xylylenediamine (a1), and acts as an epoxy resin curing agent. Here, by the fact that the compound (a2) is at least one selected from the group consisting of phenol and phenol compounds having an alkyl group with 3 or less carbon atoms, it is considered that when the obtained aqueous epoxy resin composition is cured under low-temperature conditions, stickiness of the coating film is less likely to occur, and both the low-temperature curability and the water resistance of the coating film after low-temperature curing become good. Furthermore, it is believed that the emulsifying properties of component (A) can be further improved by reacting xylylenediamine (a1) with compound (a2) and aldehyde compound (a3) ​​in specific proportions, compared to the use of components (B) and (C). Specifically, it is believed that a reaction ratio of compound (a2) and / or aldehyde compound (a3) ​​to 1 mole of xylylenediamine (a1) greater than 1 mole can suppress the decrease in emulsifying properties caused by a large amount of unreacted xylylenediamine (a1) in component (A). On the other hand, if the reaction ratio of compound (a2) and / or aldehyde compound (a3) ​​to 1 mole of xylylenediamine (a1) is less than 1.5 moles, it is believed that the decrease in emulsifying properties caused by the resulting reaction composition becoming excessively viscous can be suppressed.

[0016] Components (B) and (C) are used to stably emulsify component (A). Component (B), a nonionic emulsifier, has a high HLB value of 14.0 or higher, resulting in better affinity with water. Furthermore, the presence of an aromatic ring gives it good affinity with component (A), thus enabling high emulsification performance of component (A) in water. Component (C) can dissolve components (A) and (B) and also has affinity for water. Therefore, it is considered that an emulsion-type epoxy resin curing agent composition with high emulsification stability can be easily produced by the phase inversion emulsification method described later.

[0017] <Component (A): Mannich reaction composition> Component (A) is a reaction composition obtained by reacting 1 mole of xylylenediamine (a1) with more than 1 mole but less than 1.5 moles of at least one compound (a2) selected from the group consisting of phenols and phenol compounds having alkyl groups with 3 or fewer carbon atoms, and more than 1 mole but less than 1.5 moles of an aldehyde compound (a3) ​​in a Mannich reaction. Component (A) acts as an epoxy resin curing agent.

[0018] (Xylylenediamine (a1)) The xylylenediamine used as component (a1) is at least one selected from the group consisting of orthoxylylenediamine, metaxylylenediamine, and paraxylylenediamine, preferably at least one selected from the group consisting of metaxylylenediamine and paraxylylenediamine, more preferably containing metaxylylenediamine, and even more preferably metaxylylenediamine.

[0019] (At least one compound selected from the group consisting of phenol and phenol compounds having an alkyl group with 3 or fewer carbon atoms (a2)) Compound (a2) is at least one selected from the group consisting of phenols and phenol compounds having an alkyl group with 3 or fewer carbon atoms. Specific examples of compound (a2) include phenol, cresol, ethylphenol (p-ethylphenol, etc.), and isopropylphenol (o-isopropylphenol, p-isopropylphenol, etc.), and one or more of these can be used. Among the above, from the viewpoint of improving emulsification properties, and from the viewpoint of improving the low-temperature curability of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing, compound (a2) preferably comprises at least one selected from the group consisting of phenol and cresol, and more preferably comprises phenol.

[0020] (Aldehyde compound (a3)) Examples of aldehyde compounds (a3) ​​include formaldehyde; formaldehyde-releasing compounds such as trioxane and paraformaldehyde; and other aldehydes such as benzaldehyde. Among these, aldehyde compound (a3) ​​preferably contains at least one selected from the group consisting of formaldehyde and formaldehyde-releasing compounds, and more preferably contains formaldehyde. From the viewpoint of improving workability in the Mannich reaction, when aldehyde compound (a3) ​​contains formaldehyde, it is more preferable to carry out the Mannich reaction using an aqueous solution of formaldehyde.

[0021] A preferred combination of xylylenediamine (a1), compound (a2), and aldehyde compound (a3) ​​is one in which xylylenediamine (a1) contains metaxylylenediamine, compound (a2) contains phenol, and aldehyde compound (a3) ​​contains formaldehyde.

[0022] (Mannich reaction) Component (A) can be produced by a Mannich reaction of xylylenediamine (a1), compound (a2), and aldehyde compound (a3). For the Mannich reaction, known methods can be used. For example, a mixture of xylylenediamine (a1) and compound (a2) is to be added dropwise by an aldehyde compound (a3) ​​or a solution thereof, preferably at 90°C or below, more preferably at 80°C or below. After the addition is complete, the temperature is preferably raised to 80-180°C, more preferably 90-150°C, and the reaction is carried out for 1-10 hours while removing the distillate from the reaction system.

[0023] In the Mannich reaction, 1 mole of xylylenediamine (a1) is reacted with more than 1 mole but less than 1.5 moles of compound (a2) and more than 1 mole but less than 1.5 moles of aldehyde compound (a3). In the Mannich reaction, the amount of compound (a2) reacted with 1 mole of xylylenediamine (a1) is preferably in the range of 1.1 to 1.4 moles, more preferably 1.1 to 1.3 moles, from the viewpoint of improving emulsification and improving the low-temperature curability of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing. Similarly, the amount of aldehyde compound (a3) ​​reacted with 1 mole of xylylenediamine (a1) is preferably in the range of 1.1 to 1.4 moles, more preferably 1.1 to 1.3 moles, from the same viewpoint as above.

[0024] (Content of unreacted xylylenediamine (a1) in component (A)) The content of unreacted xylylenediamine (a1) in component (A) obtained by the above reaction is preferably 35% by mass or less, more preferably 30% by mass or less, and more preferably 25% by mass or less, from the viewpoint of improving emulsification. The lower limit is not particularly limited and may be 0% by mass. In this context, "content of unreacted xylylenediamine (a1) in component (A)" refers to the content of unreacted, free xylylenediamine (a1) in component (A). The content of xylylenediamine (a1) in component (A) can be measured by gas chromatography (GC) analysis, specifically by the method described in the examples.

[0025] (Activated hydrogen equivalent (AHEW) of component (A)) The active hydrogen equivalent (AHEW) of component (A) is preferably 130 or less, more preferably 120 or less, and even more preferably 110 or less, from the viewpoint of exhibiting good curing performance even with a small amount added to the aqueous epoxy resin composition. Furthermore, from the viewpoint of ease of manufacture, it is preferably 70 or more, more preferably 80 or more, and even more preferably 90 or more. The AHEW of component (A) can be determined, for example, by titration.

[0026] <Ingredient (B): Nonionic emulsifier with an aromatic ring and an HLB value of 14.0 or higher> Component (B) is a nonionic emulsifier having an aromatic ring and an HLB value of 14.0 or higher. Here, HLB (Hydrophile-Lipophile Balance) is a value that indicates the affinity of the emulsifier (component (B)) for water and oil, and can be determined by the Griffin method using the following formula. HLB = 20 × [(Molecular weight of hydrophilic group contained in component (B)) / (Molecular weight of component (B))] Examples of the hydrophilic groups mentioned above include hydroxyl groups and ethyleneoxy (EO) groups.

[0027] From the viewpoint of improving emulsification, the HLB of component (B) is preferably 14.0 to 20.0, more preferably 15.0 to 20.0, even more preferably 16.0 to 19.5, even more preferably 17.0 to 19.5, and even more preferably 17.5 to 19.0.

[0028] The nonionic emulsifier, component (B), only needs to contain one or more aromatic rings. The "aromatic ring" here can be a monocyclic or fused ring, and examples include a benzene ring, a naphthalene ring, or an anthracene ring, but a benzene ring is preferred. From the viewpoint of further improving emulsification properties, and from the viewpoint of improving the low-temperature curability of the resulting water-based epoxy resin composition and the water resistance of the coating film after low-temperature curing, component (B) preferably contains two or more aromatic rings. There is no particular upper limit to the number of aromatic rings, but it is preferably 100 or less, more preferably 50 or less, and even more preferably 30 or less.

[0029] The nonionic emulsifier, which is component (B), preferably has a polyoxyethylene structure from the viewpoint of achieving an HLB value of 14.0 or higher. The average number of moles of oxyethylene units added to component (B) is preferably in the range of 4 to 300, more preferably 5 to 200, and even more preferably 5 to 150, from the viewpoint of further improving emulsification properties, with an HLB value of 14.0 or higher.

[0030] Examples of nonionic emulsifiers having an aromatic ring and a polyoxyethylene structure used as component (B) include polyoxyethylene aryl ethers such as polyoxyethylene phenyl ether, polyoxyethylene styrene-phenyl ether, polyoxyethylene naphthyl ether, polyoxyethylene bisphenol A ether, and polyoxyethylene bisphenol F ether; polyoxyethylene alkylaryl ethers such as polyoxyethylene benzyl ether and polyoxyethylene dodecylphenyl ether; ethylene oxide adducts of aromatic hydrocarbon formaldehyde resins; ethylene oxide adducts of modified aromatic hydrocarbon formaldehyde resins; and one or more of these can be used. Among the above, component (B) preferably comprises at least one selected from the group consisting of polyoxyethylene styrene-phenyl ether, ethylene oxide adduct of aromatic hydrocarbon formaldehyde resin, and ethylene oxide adduct of modified aromatic hydrocarbon formaldehyde resin, and more preferably comprises at least one selected from the group consisting of polyoxyethylene styrene-phenyl ether and ethylene oxide adduct of aromatic hydrocarbon formaldehyde resin.

[0031] (Polyoxyethylene styrene-derived phenyl ether) In this specification, polyoxyethylene styrene-phenyl ethers include various polyoxyethylene styrene-phenyl ethers such as polyoxyethylene monostyrene-phenyl ethers, polyoxyethylene distyrene-phenyl ethers, and polyoxyethylene tristyrene-phenyl ethers, and mixtures thereof. Among these, polyoxyethylene styrene-phenyl ethers preferably include at least one selected from the group consisting of polyoxyethylene monostyrene-phenyl ethers and polyoxyethylene distyrene-phenyl ethers, and more preferably include polyoxyethylene distyrene-phenyl ethers. As polyoxyethylene styrene-phenyl ethers with an HLB value of 14.0 or higher, commercially available products such as "Neugen EA-207D" (HLB 18.7) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. and "BLAUNON TSP-50" (HLB 16.9) manufactured by Aoki Yushi Kogyo Co., Ltd. can also be used.

[0032] (Ethylene oxide adduct of aromatic hydrocarbon formaldehyde resin) Ethylene oxide adducts of aromatic hydrocarbon formaldehyde resins are compounds obtained by an addition reaction between aromatic hydrocarbon formaldehyde resin and ethylene oxide.

[0033] [Aromatic hydrocarbon formaldehyde resin] Aromatic hydrocarbon formaldehyde resin is a resin obtained by reacting aromatic hydrocarbons with formaldehyde. In this specification, aromatic hydrocarbon formaldehyde resin means an unmodified aromatic hydrocarbon formaldehyde resin that has not been modified by other functional groups or the like. The aromatic hydrocarbons include at least one selected from the group consisting of benzene, toluene, xylene, mesitylene, pseudocumene, ethylbenzene, propylbenzene, decylbenzene, cyclohexylbenzene, biphenyl, methylbiphenyl, naphthalene, methylnaphthalene, dimethylnaphthalene, ethylnaphthalene, anthracene, methylanthracene, dimethylanthracene, ethylanthracene, and binaphthyl. Among these, from the viewpoint of improving emulsification, the aromatic hydrocarbons preferably include at least one selected from the group consisting of toluene, xylene, mesitylene, and pseudocumene, and more preferably include xylene.

[0034] As formaldehyde, industrially readily available formalin and paraformaldehyde, as well as formaldehyde-generating compounds such as trioxane, can be used.

[0035] The aromatic hydrocarbon formaldehyde resin preferably comprises at least one selected from tolueneformaldehyde resin obtained by reacting toluene with formaldehyde, xyleneformaldehyde resin obtained by reacting xylene with formaldehyde, mesityleneformaldehyde resin obtained by reacting mesitylene with formaldehyde, and pseudocumeneformaldehyde resin obtained by reacting pseudocumene with formaldehyde, and more preferably comprises xyleneformaldehyde resin.

[0036] From the viewpoint of improving emulsification, the content of xyleneformaldehyde resin in aromatic hydrocarbon formaldehyde resin is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and 100% by mass or less.

[0037] The weight-average molecular weight (Mw) of aromatic hydrocarbon formaldehyde resin is preferably 200 to 10,000, more preferably 300 to 8,000, even more preferably 350 to 5,000, even more preferably 400 to 3,000, even more preferably 400 to 1,500, and even more preferably 500 to 1,000, based on standard polystyrene, from the viewpoint of improving emulsification properties. The weight-average molecular weight (Mw) can be measured by gel filtration chromatography (GPC).

[0038] The viscosity of aromatic hydrocarbon formaldehyde resin at 25°C is preferably 30 to 30,000 mPa·s, more preferably 50 to 20,000 mPa·s, even more preferably 100 to 15,000 mPa·s, even more preferably 300 to 15,000 mPa·s, even more preferably 500 to 10,000 mPa·s, even more preferably 1,000 to 10,000 mPa·s, even more preferably 2,000 to 10,000 mPa·s, and even more preferably 3,000 to 8,000 mPa·s, from the viewpoint of improving emulsification. The above viscosity can be measured using a rotational viscometer at 25°C.

[0039] The hydroxyl value (mgKOH / g) of the aromatic hydrocarbon formaldehyde resin is preferably 20 to 150 mgKOH / g, more preferably 25 to 120 mgKOH / g, and even more preferably 30 to 100 mgKOH / g, from the viewpoint of ethylene oxide addition and improved emulsification. The above hydroxyl value can be measured by the method described in JIS K0070-1992.

[0040] The hydroxyl group equivalent (g / equivalent) of aromatic hydrocarbon formaldehyde resin is preferably 200 to 2,500 g / equivalent, more preferably 500 to 2,000 g / equivalent, even more preferably 800 to 1,800 g / equivalent, and even more preferably 1,000 to 1,500 g / equivalent, from the viewpoint of ethylene oxide addition and improved emulsification. The above hydroxyl group equivalent is determined by measuring the hydroxyl value by the method described in JIS K0070-1992 and converting the value of the hydroxyl value to the hydroxyl group equivalent.

[0041] Aromatic hydrocarbon formaldehyde resin may be a commercially available product or may be manufactured by a known method. As a method for producing aromatic hydrocarbon formaldehyde resin, for example, one can refer to a method described in Japanese Patent Publication No. 37-5747, which involves a condensation reaction between aromatic hydrocarbons and formaldehyde in the presence of a catalyst.

[0042] Examples of commercially available aromatic hydrocarbon formaldehyde resins include the xylene formaldehyde resins "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," all manufactured by Fudo Co., Ltd.

[0043] The ethylene oxide adduct of aromatic hydrocarbon formaldehyde resin is obtained by reacting the aromatic hydrocarbon formaldehyde resin with ethylene oxide under heating and pressurizing conditions with a basic catalyst. More specifically, a method is used in which the aromatic hydrocarbon formaldehyde resin and a basic catalyst are charged into a reactor equipped with a heating and pressurizing mechanism such as an autoclave, and ethylene oxide is fed in and the reaction is carried out under heating and pressurizing conditions.

[0044] In the above reaction, the amount of ethylene oxide charged to 100 parts by mass of aromatic hydrocarbon formaldehyde resin is preferably 120 to 800 parts by mass, more preferably 150 to 600 parts by mass, even more preferably 180 to 500 parts by mass, even more preferably 200 to 450 parts by mass, even more preferably 250 to 450 parts by mass, and even more preferably 300 to 450 parts by mass, from the viewpoint of adjusting the HLB of the resulting aromatic hydrocarbon formaldehyde resin ethylene oxide adduct to a desired range. That is, the aromatic hydrocarbon formaldehyde resin ethylene oxide adduct is obtained by reacting 100 parts by mass of aromatic hydrocarbon formaldehyde resin with ethylene oxide preferably 120 to 800 parts by mass, more preferably 150 to 600 parts by mass, even more preferably 180 to 500 parts by mass, even more preferably 200 to 450 parts by mass, even more preferably 250 to 450 parts by mass, and even more preferably 300 to 450 parts by mass.

[0045] Either inorganic or organic bases can be used as the basic catalyst in the above reaction. Examples of inorganic bases include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, while examples of organic bases include alkali metal alkoxides such as potassium methoxide and sodium methoxide, as well as amines such as triethylamine. These can be used individually or in combination of two or more. Among the basic catalysts mentioned above, from the viewpoint of improving reaction efficiency and economic efficiency, an inorganic base is preferred, more preferably containing an alkali metal hydroxide, and even more preferably containing potassium hydroxide.

[0046] The reaction temperature in the above reaction is preferably 100 to 190°C, more preferably 140 to 190°C, from the viewpoint of improving reaction efficiency. The reaction time varies depending on the amount of ethylene oxide used, but is preferably 1 to 30 hours, more preferably 1 to 15 hours, even more preferably 1 to 12 hours, and even more preferably 1 to 7 hours. The reaction time here includes the ethylene oxide feed time. The pressure during the above reaction is preferably higher than atmospheric pressure (1 atmosphere; 0.1013 MPa), preferably in the range of 0.12 to 5 MPa, more preferably 0.15 to 2 MPa, and even more preferably 0.15 to 1 MPa.

[0047] From the viewpoint of improving emulsification properties, the weight-average molecular weight of the ethylene oxide adduct of aromatic hydrocarbon formaldehyde resin is preferably 1,000 to 100,000, more preferably 2,000 to 50,000, even more preferably 3,000 to 25,000, and even more preferably 4,000 to 20,000, in terms of standard polystyrene. The weight-average molecular weight mentioned above can be determined by the same method as described above.

[0048] (Ethylene oxide adduct of modified aromatic hydrocarbon formaldehyde resin) Ethylene oxide adducts of modified aromatic hydrocarbon formaldehyde resins are compounds obtained by an addition reaction between a modified aromatic hydrocarbon formaldehyde resin and ethylene oxide.

[0049] [Modified aromatic hydrocarbon formaldehyde resin] Modified aromatic hydrocarbon formaldehyde resin is a resin obtained by modifying the aforementioned aromatic hydrocarbon formaldehyde resin with phenols, polyols, etc. From the viewpoint of improving emulsification properties, it is preferable that the modified aromatic hydrocarbon formaldehyde resin is a resin obtained by modifying the aromatic hydrocarbon formaldehyde resin with phenols.

[0050] Examples of phenols include naturally occurring phenolic compounds such as phenols, alkylphenols, alkenylphenols, terpenephenols, and cardanol. In alkylphenols, the number of carbon atoms in the alkyl group is preferably 1 to 24, more preferably 1 to 18, and in alkenylphenols, the number of carbon atoms in the alkenyl group is preferably 2 to 24, more preferably 2 to 18. Specific examples of phenols include phenol, cresol, ethylphenol (p-ethylphenol, etc.), isopropylphenol (o-isopropylphenol, p-isopropylphenol, etc.), butylphenol (p-tert-butylphenol, p-sec-butylphenol, o-tert-butylphenol, o-sec-butylphenol, etc.), amylphenol (p-tert-amylphenol, o-tert-amylphenol, etc.), p-octylphenol, nonylphenol, p-cumylphenol, decylphenol, undecylphenol, p-dodecylphenol, tridecylphenol, tetradecylphenol, pentadecylphenol, pentadecenylphenol, pentadecadienylphenol, pentadecadrienylphenol, pentadecatrienylphenol, hexadecylphenol, heptadecylphenol, octadecylphenol, octadecenylphenol, terpenephenol, and cardanol. One or more of these can be used. Among the above, the phenols preferably include at least one selected from the group consisting of phenol, cresol, butylphenol, and nonylphenol, more preferably include at least one selected from the group consisting of phenol and butylphenol, and even more preferably include phenol.

[0051] Furthermore, examples of polyols include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, trimethylolpropane, neopentyl glycol, and others, and one or more of these can be used.

[0052] Modified aromatic hydrocarbon formaldehyde resins can be obtained, for example, by reacting the aromatic hydrocarbon formaldehyde resin with phenols or polyols in the presence of an acid or basic catalyst.

[0053] Commercially available products can also be used as modified aromatic hydrocarbon formaldehyde resins. Examples of commercially available phenol-modified aromatic hydrocarbon formaldehyde resins (phenol-modified aromatic hydrocarbon formaldehyde resins) include the alkylphenol-modified xylene formaldehyde resins "GHP-150," "HP-210," and "HP-70" manufactured by Fudo Co., Ltd., the phenol-modified (novolac type) xylene formaldehyde resins "NP-100," "GP-212," "P-100," "GP-200," and "HP-30," and the phenol-modified (resol type) xylene formaldehyde resins "PR-1440M," "PR-1440," and "GRL." Examples of commercially available polyol-modified aromatic hydrocarbon formaldehyde resins (polyol-modified aromatic hydrocarbon formaldehyde resins) include Fudo Co., Ltd.'s polyol-modified xylene formaldehyde resin "K-100".

[0054] The ethylene oxide adduct of the modified aromatic hydrocarbon formaldehyde resin is obtained by reacting the modified aromatic hydrocarbon formaldehyde resin with ethylene oxide, similar to the method for producing the ethylene oxide adduct of the aromatic hydrocarbon formaldehyde resin. The production conditions, weight-average molecular weight, and preferred embodiments thereof for the ethylene oxide adduct of the modified aromatic hydrocarbon formaldehyde resin are the same as those for the ethylene oxide adduct of the aromatic hydrocarbon formaldehyde resin described above.

[0055] <Component (C): Cosolvent> The co-solvent, which is component (C), is a solvent that can dissolve components (A) and (B), and also has an affinity for water. From the viewpoint of reducing volatile organic compounds (VOCs) and suppressing the volatilization of component (C) during the manufacturing process and maintaining good emulsification properties, component (C) contains a solvent with a boiling point at atmospheric pressure preferably of 120°C or higher, more preferably 150°C or higher, even more preferably 160°C or higher, even more preferably 170°C or higher, and even more preferably 180°C or higher.

[0056] The cosolvent used as component (C) preferably includes a cosolvent having a hydroxyl group, from the viewpoint of improving emulsification properties and improving the low-temperature curability of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing. The cosolvent having a hydroxyl group is a cosolvent having at least one hydroxyl group, and may have a chain structure or a ring structure. From the viewpoint of improving emulsification properties, and from the viewpoint of improving the low-temperature curability of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing, the cosolvent used as component (C) is preferably a cosolvent having a hydroxyl group and a ring structure. Specific examples of cosolvents having a hydroxyl group that can be used as component (C) include propylene glycol monomethyl ether (boiling point 120°C), propylene glycol n-propyl ether (boiling point 150°C), propylene glycol n-butyl ether (boiling point 171°C), benzyl alcohol (boiling point 205.3°C), furfuryl alcohol (boiling point 170°C), tetrafurfuryl alcohol (boiling point 178°C), and aromatic hydrocarbon formaldehyde resins, and one or more of these can be used. The aromatic hydrocarbon formaldehyde resin referred to herein is synonymous with the aromatic hydrocarbon formaldehyde resin described in component (B). Commercially available aromatic hydrocarbon formaldehyde resins used as component (C) include xylene formaldehyde resins manufactured by Fudo Co., Ltd., such as "Nikanol Y-50," "Nikanol Y-100," and "Nikanol Y-300."

[0057] Among the above, from the viewpoint of improving emulsification properties, and from the viewpoint of improving the low-temperature curability of the obtained aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing, component (C) preferably contains at least one selected from the group consisting of benzyl alcohol, furfuryl alcohol, tetrafurfuryl alcohol, and aromatic hydrocarbon formaldehyde resin, which is a cosolvent having a hydroxyl group and a ring structure, and more preferably contains benzyl alcohol.

[0058] <Water> As the water used in the curing agent composition, purified water such as distilled water or ion-exchanged water (deionized water), tap water, industrial water, etc., can be used.

[0059] <Epoxy resin curing agent components other than component (A)> The curing agent composition does not exclude the inclusion of epoxy resin curing agent components other than component (A). Other epoxy resin curing agent components besides component (A) include compounds having two or more groups with active hydrogen that can react with the epoxy groups in the main component used in aqueous epoxy resin compositions. Examples of such epoxy resin curing agent components include amine-based curing agents, phenol-based curing agents, acid anhydride-based curing agents, hydrazide-based curing agents, and the like. However, the content of component (A) in the epoxy resin curing agent component is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and 100% by mass or less, from the viewpoint of improving emulsification and improving the low-temperature curability of the obtained water-based epoxy resin composition and the water resistance of the coating film after low-temperature curing.

[0060] <Content> The content of each component in the emulsion-type epoxy resin curing agent composition is preferably within the following ranges. The content of component (A) in the curing agent composition is preferably 10 to 60% by mass, more preferably 20 to 60% by mass, even more preferably 30 to 55% by mass, and even more preferably 40 to 55% by mass, from the viewpoint of improving emulsification and improving the low-temperature curability of the resulting water-based epoxy resin composition and the water resistance of the coating film after low-temperature curing.

[0061] The content of component (B) in the curing agent composition is preferably 0.5 to 20% by mass, more preferably 1 to 18% by mass, even more preferably 1 to 15% by mass, even more preferably 1 to 12% by mass, even more preferably 2 to 10% by mass, and even more preferably 2 to 8% by mass, from the viewpoint of improving emulsification and improving the low-temperature curability of the obtained water-based epoxy resin composition and the water resistance of the coating film after low-temperature curing.

[0062] Furthermore, the content of component (B) in the curing agent composition relative to 100% by mass of the total of component (A) and component (B) is preferably 0.1 to 20% by mass, more preferably 0.5 to 18% by mass, even more preferably 1 to 15% by mass, even more preferably 3 to 15% by mass, and even more preferably 5 to 12% by mass, from the viewpoint of improving emulsification and improving the low-temperature curability of the obtained water-based epoxy resin composition and the water resistance of the coating film after low-temperature curing.

[0063] From the viewpoint of improving emulsification, the total content of component (A) and component (B) in the curing agent composition is preferably 10.5 to 70% by mass, more preferably 20 to 65% by mass, even more preferably 30 to 65% by mass, even more preferably 35 to 60% by mass, and even more preferably 40 to 60% by mass.

[0064] The content of component (C) in the curing agent composition is preferably 2 to 30% by mass, more preferably 3 to 25% by mass, even more preferably 4 to 20% by mass, and even more preferably 5 to 15% by mass, from the viewpoint of improving emulsification and improving the low-temperature curability of the resulting water-based epoxy resin composition and the water resistance of the coating film after low-temperature curing.

[0065] Furthermore, the mass ratio of component (C) to the total mass of component (A) and component (B) in the curing agent composition is preferably 0.01 to 3.0, more preferably 0.05 to 2.0, even more preferably 0.08 to 1.0, even more preferably 0.10 to 0.80, even more preferably 0.12 to 0.50, and even more preferably 0.15 to 0.40, from the viewpoint of improving emulsification and improving the low-temperature curability of the resulting water-based epoxy resin composition and the water resistance of the coating film after low-temperature curing.

[0066] The total content of components (A) to (C) in the curing agent composition is preferably 15 to 85% by mass, more preferably 20 to 80% by mass, even more preferably 30 to 70% by mass, even more preferably 40 to 65% by mass, and even more preferably 50 to 65% by mass, from the viewpoint of improving curability and emulsification.

[0067] From the viewpoint of emulsification stability, the water content in the curing agent composition is preferably 15 to 85% by mass, more preferably 20 to 80% by mass, even more preferably 30 to 70% by mass, even more preferably 35 to 60% by mass, and even more preferably 35 to 50% by mass. The water content in the curing agent composition may be the remainder of components (A) to (C).

[0068] <Other ingredients> The curing agent composition may further contain, depending on the application, other components such as fillers, plasticizers and other modifying components, thixotropes and other flow adjusting components, leveling agents, dispersants, defoamers, and tackifiers.

[0069] <Method for producing the curing agent composition> The method for producing the emulsion-type epoxy resin curing agent composition is not particularly limited, but from the viewpoint of improving emulsification, it is preferable to produce it by a method having the following steps (I) and (II) in order. Step (I): A step of mixing components (A), (B), and (C) to prepare mixture 1. Step (II): A step in which water is added to the mixture 1 and stirred to perform phase inversion emulsification in order to obtain an emulsion-type epoxy resin curing agent composition. Details of steps (I) and (II) will be described later in the section on the method for producing the aqueous epoxy resin composition.

[0070] <Form of the curing agent composition> In the emulsion-type epoxy resin curing agent composition, the emulsion is preferably an oil-in-water emulsion. That is, the curing agent composition of the present invention is an epoxy resin curing agent composition in which component (A) is emulsified and dispersed in water.

[0071] <AHEW of the curing agent composition> The AHEW of the curing agent composition varies depending on the content of component (A) in the composition, but from the viewpoint of improving emulsification and handling properties, it is preferably in the range of 120 to 1000, more preferably 150 to 800, even more preferably 150 to 600, and even more preferably 150 to 400.

[0072] [Water-based epoxy resin composition] The present invention provides an aqueous epoxy resin composition obtained by mixing the emulsion-type epoxy resin curing agent composition with an epoxy resin emulsion. That is, the aqueous epoxy resin composition of the present invention is an emulsion-type aqueous epoxy resin composition, preferably an aqueous epoxy resin composition in which the emulsion is an oil-in-water emulsion.

[0073] <Epoxy resin emulsion> The epoxy resin emulsion is the main component of the water-based epoxy resin composition and is an emulsion containing at least epoxy resin and water. In the following description and examples, the epoxy resin emulsion may be simply referred to as the "main component."

[0074] (Epoxy resin) The epoxy resin in the epoxy resin emulsion may be any epoxy resin having epoxy groups that react with the active hydrogen present in the epoxy resin curing agent component in the curing agent composition. From the viewpoint of improving the low-temperature curability of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing, the epoxy resin in the epoxy resin emulsion preferably includes a solid epoxy resin, and more preferably includes a solid epoxy resin containing an aromatic ring or alicyclic structure in its molecule. In this context, "solid epoxy resin" refers to epoxy resin that is solid at 25°C.

[0075] Preferred specific examples of epoxy resins used in epoxy resin emulsions 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 para-aminophenol, 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.

[0076] Among the above, from the viewpoint of improving the low-temperature curability of the obtained aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing, the epoxy resin preferably comprises at least one selected from the group consisting of an epoxy resin having a glycidylamino group derived from metaxylylenediamine, 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, it comprises 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, it comprises an epoxy resin having a glycidyloxy group derived from bisphenol A.

[0077] 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 emulsification stability, and preferably 1000 g / equivalent or less, more preferably 800 g / equivalent or less, even more preferably 800 g / equivalent or less, and even more preferably 600 g / equivalent or less, from the viewpoint of the curability of the resulting aqueous epoxy resin composition.

[0078] The epoxy resin content 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 emulsification stability, is preferably 80% by mass or less.

[0079] (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, and any of nonionic emulsifiers, anionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers, and reactive emulsifiers having reactive groups such as epoxy groups can be used. Among the above, from the viewpoint of improving the low-temperature curability of the resulting water-based epoxy resin composition and the water resistance of the coating film after low-temperature curing, the emulsifier used in the epoxy resin emulsion preferably includes at least one selected from the group consisting of nonionic emulsifiers and anionic emulsifiers that do not have reactive groups, and more preferably includes a nonionic emulsifier that does not have reactive groups. Examples of the nonionic emulsifiers mentioned above include polyether compounds, ester compounds, and alkanolamide compounds. Furthermore, component (B) may be used as an emulsifier in epoxy resin emulsions. Emulsifiers can be used alone or in combination of two or more types.

[0080] When the epoxy resin emulsion contains an emulsifier, the amount of 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 epoxy resin. If the amount of emulsifier is 0.1 parts by mass or more per 100 parts by mass of epoxy resin, the emulsion stability is improved, and if it is 40 parts by mass or less, the low-temperature curability of the resulting water-based epoxy resin composition and the water resistance of the coating film after low-temperature curing can be well maintained.

[0081] (water) The water content in the epoxy resin emulsion is not particularly limited, but from the viewpoint of emulsification stability and improved handling, it is preferably 15 to 80% by mass, more preferably 20 to 70% by mass, and even more preferably 25 to 60% by mass.

[0082] As an epoxy resin emulsion, commercially available products such as "Araldite PZ 3961-1" from HUNTSMAN Advanced Materials (an aqueous emulsion of solid epoxy resin having a glycidyloxy group derived from bisphenol A) can also be used.

[0083] <Mixing ratio> The water-based epoxy resin composition is obtained by mixing an emulsion-type epoxy resin curing agent composition with an epoxy resin emulsion. The mixing ratio of the emulsion-type epoxy resin curing agent composition to the epoxy resin emulsion is such that the number of active hydrogens in the epoxy resin curing agent component (number of active hydrogens in the epoxy resin curing agent component / number of epoxy groups in the epoxy resin) is preferably 0.5 / 1 to 2 / 1, more preferably 0.6 / 1 to 1.5 / 1, and even more preferably 0.7 / 1 to 1.2 / 1. The term "epoxy resin curing agent component" as used herein includes component (A) and epoxy resin curing agent components other than component (A).

[0084] <Content> The content of component (A) in the water-based epoxy resin composition is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, even more preferably 3 to 12% by mass, and even more preferably 5 to 10% by mass, from the viewpoint of emulsification stability and improvement of low-temperature curability and water resistance of the coating film after low-temperature curing.

[0085] The content of the epoxy resin curing agent component in the aqueous epoxy resin composition is preferably 1 to 25% by mass, more preferably 2 to 20% by mass, even more preferably 3 to 15% by mass, and even more preferably 5 to 12% by mass, from the viewpoint of emulsification stability and improvement of low-temperature curing properties and water resistance of the coating film after low-temperature curing. The "content of the epoxy resin curing agent component" as used herein also includes the content of component (A) mentioned above.

[0086] The epoxy resin content in the water-based 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 even more preferably 35 to 50% by mass, from the viewpoint of emulsification stability and improvement of low-temperature curability and water resistance of the coating film after low-temperature curing.

[0087] The content of component (B) in the aqueous epoxy resin composition is preferably 0.1 to 5% by mass, more preferably 0.2 to 3% by mass, even more preferably 0.3 to 2% by mass, and even more preferably 0.3 to 1% by mass, from the viewpoint of improving emulsion stability and preparing an aqueous epoxy resin composition with a long pot life.

[0088] The content of component (C) in the aqueous epoxy resin composition is preferably 0.2 to 10% by mass, more preferably 0.4 to 8% by mass, even more preferably 0.8 to 6% by mass, and even more preferably 1 to 5% by mass, from the viewpoint of improving emulsion stability and preparing an aqueous epoxy resin composition with a long pot life.

[0089] Of the nonvolatile components in the water-based epoxy resin composition, the total content of the epoxy resin curing agent component containing component (A), the epoxy resin, and the emulsifier containing component (B) is preferably 10 to 90% by mass, more preferably 15 to 85% by mass, even more preferably 20 to 80% by mass, and even more preferably 30 to 70% by mass, from the viewpoint of emulsion stability and improvement of low-temperature curability and water resistance of the coating film after low-temperature curing.

[0090] The water content in the water-based 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, from the viewpoint of emulsification stability and improvement of low-temperature curability and water resistance of the coating film after low-temperature curing. 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 term "water content" as used here refers to the total amount of water contained in the water-based epoxy resin composition.

[0091] <Other ingredients> The water-based epoxy resin composition may further contain, depending on the application, other components such as pigments, non-pigment fillers, modifying components such as plasticizers, flow modifiers such as thixotropes, leveling agents, dispersants, defoamers, and tackifiers. When the water-based epoxy resin composition contains pigments, an effect of improving chemical resistance can also be obtained. When the water-based epoxy resin composition contains a pigment, the pigment content in the water-based epoxy resin composition is preferably 1 to 45% by mass, more preferably 2 to 40% by mass, even more preferably 5 to 35% by mass, and even more preferably 10 to 35% by mass, from the viewpoint of improving colorability and chemical resistance, and improving the water resistance of the resulting coating film.

[0092] The present invention does not exclude the inclusion of organic solvents other than component (C) in the aqueous epoxy resin composition, but it is preferable that the content of such organic solvents is low. The content of organic solvents other than component (C) in the aqueous epoxy resin composition is preferably less than 10% by mass, more preferably 8% by mass or less, and even more preferably 6% by mass or less.

[0093] [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 emulsion-type epoxy resin curing agent composition with an epoxy resin emulsion, but preferably has the following steps (I) to (III) in order from the viewpoint of improving emulsification and improving low-temperature curing properties and the water resistance of the coating film after low-temperature curing. Step (I): A step of mixing components (A), (B), and (C) to prepare mixture 1. Step (II): A step in which water is added to the mixture 1 and stirred to perform phase inversion emulsification in order to obtain an emulsion-type epoxy resin curing agent composition. Step (III): A step of mixing the emulsion-type epoxy resin curing agent composition with the epoxy resin emulsion.

[0094] <Process (I)> In step (I), components (A), (B), and (C) are mixed to prepare a mixture 1 containing components (A), (B), and (C). Components (A) and (B) used in step (I) may be used in a state of 100% by mass of active ingredients, or a solution of component (A) or a solution of component (B) may be prepared in advance and used in that state. The mixing order of components (A), (B), and (C) is not particularly limited, and components (A), (B), and (C) may be blended and mixed simultaneously.

[0095] Mixture 1 can be prepared by mixing using a known stirring device such as a disper. The temperature during the preparation of mixture 1 may be room temperature, usually in the range of 0 to 40°C, preferably 0 to 35°C. The mixing time during the preparation of mixture 1 is not particularly limited as long as components (A), (B), and (C) become a homogeneous solution, and is usually selected in the range of 0.5 minutes to 12 hours.

[0096] <Process (II)> In step (II), water is added to the mixture 1 obtained in step (I) and stirred to induce phase inversion emulsification, thereby obtaining an emulsion-type epoxy resin curing agent composition. The addition of water to mixture 1 is preferably carried out while stirring the mixture 1. The water may be added continuously or in stages. When adding water in stages, the number of stages is preferably 2 to 20, more preferably 3 to 15, from the viewpoint of improving emulsification and improving low-temperature curing properties and the water resistance of the coating film after low-temperature curing. The stirring device can be the same as the one used in process (I). Alternatively, known emulsifying devices such as high-pressure emulsifiers and ultrasonic emulsifiers may be used.

[0097] The temperature during phase inversion emulsification in step (II) may be room temperature, but from the viewpoint of improving emulsification, it is preferably in the range of 0 to 60°C, and more preferably in the range of 0 to 55°C. The mixing time during phase inversion emulsification is not particularly limited and is usually selected in the range of 0.5 minutes to 12 hours.

[0098] <Process (III)> In step (III), the emulsion-type epoxy resin curing agent composition obtained in step (II) is mixed with the epoxy resin emulsion. By first preparing the epoxy resin emulsion, which is the main component, as an emulsion and then mixing it with the emulsion-type epoxy resin curing agent composition, a water-based epoxy resin composition with higher emulsification stability can be prepared. The preferred mixing ratio of the emulsion-type epoxy resin curing agent composition to the epoxy resin emulsion is as described in the section on water-based epoxy resin compositions.

[0099] In the mixing step of step (III), the same stirring device as used in step (I) can be used. The mixing temperature in step (III) may be room temperature, usually in the range of 0 to 40°C, preferably 0 to 35°C. The mixing time in step (III) is not particularly limited and is usually selected in the range of 0.5 minutes to 12 hours. Any optional components added to the water-based epoxy resin composition may be added at any step. However, any optional components other than water added to the emulsion-type epoxy resin curing agent composition are preferably added in step (I).

[0100] [Cured product] The present invention can provide 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 not particularly limited and can be selected according to the application. For example, when a water-based epoxy resin composition is used as a paint, the cured product is usually a film-like cured product.

[0101] [paint] The present invention provides a paint containing the water-based epoxy resin composition. The paint, by containing the water-based epoxy resin composition, exhibits good low-temperature curing properties and water resistance of the coating film after low-temperature curing. Examples of such paints include anticorrosive paints, marine paints, tank paints, pipe interior paints, exterior paints, and flooring paints. Anticorrosive paints are used, for example, for painting ships, bridges, factory buildings, and other land and sea steel structures.

[0102] The content of the water-based epoxy resin composition in the paint is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and may be 100% by mass.

[0103] <Application> The water-based epoxy resin composition of the present invention is suitably used in paints, adhesives, flooring materials, sealants, polymer cement mortar, gas barrier coatings, primers, screeds, topcoats, sealing materials, crack repair materials, concrete materials, and the like. [Examples]

[0104] 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. The epoxy resin curing agent composition and the aqueous epoxy resin composition were evaluated by the following method.

[0105] (Xylylenediamine content in component (A) and component (A')) 0.10 g of the reaction composition, which is component (A) or component (A'), and 0.03 g of diphenyl ether (manufactured by Kanto Chemical Co., Ltd.) as an internal standard were weighed and diluted with 1.5 g of methanol to prepare a sample for measurement. The sample was analyzed using a gas chromatography (GC) analyzer under the following conditions, and the xylylenediamine content in component (A) or component (A') was calculated from the GC area values ​​of xylylenediamine and the internal standard. [GC measurement conditions] Equipment: Agilent Technologies, Inc. "7890B GC" Column; Agilent Technologies, Inc. "CP-Sil 8 CB for Amines" (Length 30m, Film Thickness 0.25μm, Inner Diameter 0.25mm) Column temperature: 40°C for 10 minutes → increase temperature by 20°C / min → 250°C for 10 minutes → increase temperature by 20°C / min → 300°C for 10 minutes Carrier gas: Helium Carrier gas flow rate: 2.2553 mL / min Inlet pressure: 22.474 psi (constant pressure mode) Detector: FID Inlet temperature: 250℃ Detector temperature: 310℃

[0106] (emulsifying) The emulsion-type epoxy resin curing agent compositions listed in Table 1 were prepared using the method described below, and their emulsification state was visually observed according to the following criteria. Compositions receiving an A or B rating were considered acceptable. <Evaluation Criteria> A: Good emulsification state B: It emulsified immediately after production ended, but partially separated after 3 days. C: Separation occurs a few minutes after the end of manufacturing. D: Separation immediately after the end of production

[0107] (Dry to the touch) A zinc phosphate treated steel sheet (manufactured by Paltec Co., Ltd.; SPCC-SD PB-N144 0.8×70×150 mm) was used as the substrate. The water-based epoxy resin composition shown in Table 2 was applied to the substrate using an applicator to form a coating film (coating film thickness immediately after application: 200 μm). This coating film was stored at 5°C and 80% RH and evaluated by touch after 1, 2, and 7 days according to the following criteria. Example: Excellent (Even when pressing the thumb with a force of approximately 50N, the coating does not become sticky, and no fingerprints are left behind.) G: Good (When pressing the thumb with a force of approximately 50N, the coating does not feel sticky, but fingerprints remain after touching it.) F: Acceptable (The coating becomes sticky when a thumb is pressed against it with a force of approximately 50N) P: Defective (The coating becomes sticky when a thumb is pressed against it with a force of approximately 5N)

[0108] (Pencil hardness) A water-based epoxy resin composition shown in Table 2 was applied to a substrate (zinc phosphate treated steel sheet) using the same method as described above to form a coating film (thickness immediately after application: 200 μm). This coating film was stored at 5°C and 80% RH, and its pencil hardness was measured after 1, 2, and 7 days in accordance with JIS K5600-5-4:1999.

[0109] (Waterproof spot) A water-based epoxy resin composition shown in Table 2 was applied to a substrate (zinc phosphate treated steel sheet) in the same manner as described above to form a coating film (thickness immediately after application: 200 μm). This coating film was stored at 5°C and 80% RH, and after 1, 2, and 7 days, 2 to 3 drops of pure water were dropped onto the surface of the coating film using a dropper, and the area was capped with a 50 mL screw-top bottle. After 24 hours, the water was wiped off, and the appearance was visually observed and evaluated according to the following criteria. In this specification, the better the result of the water resistance spot test of a coating film cured under the above conditions, the higher the water resistance of the coating film when cured at low temperatures. Example: Excellent (no change at all) G: Good (slight change) F: Acceptable (There is some slight whitening, but it does not affect usability) P: Poor (whitening)

[0110] (Curing rate (RCI)) A water-based epoxy resin composition, as shown in Table 2, was applied to a glass plate (manufactured by Taiyu Kikai Co., Ltd., 25 × 348 × 2.0 mm) using a 76 μm applicator under conditions of 5°C and 80% RH to form a coating film. The glass plate with the coating film was placed in a paint drying time measuring instrument (manufactured by Taiyu Kikai Co., Ltd.), and the time to reach each drying stage (Set to Touch, Dust Free, Dry Through) was measured by observing the streaks left when the instrument's needle scratched the surface of the coating film, according to the following criteria. A shorter time indicates a faster curing speed. In this specification, products with a short semi-drying time under the above conditions are judged to have "excellent low-temperature curing properties." Touch-dry (Set to Touch): The time it takes for needle marks to begin to appear on the glass plate. Semi-dry (Dust Free): The time it takes for needle marks to appear on the surface of the paint film, even though they are not fully dry. Complete drying (Dry through): The time it takes for needle marks to disappear from the paint film.

[0111] (Appearance of the coating) Using the same method as described above, the aqueous epoxy resin compositions shown in Table 2 were applied to the substrate (zinc phosphate treated steel sheet) to form a coating film (thickness immediately after application: 200 μm). This coating film was stored at 5°C and 80% RH, and after 7 days, the appearance of the coating film was visually observed and its transparency, smoothness, and gloss were evaluated according to the following criteria. <Transparency> Example: Excellent (no cloudiness) G: Good (slightly cloudy) F: Acceptable (slightly cloudy, but usable) P: Poor (cloudy) <Smoothness> Example: Excellent (no bumps or unevenness) G: Good (slightly uneven) F: Usable (Some unevenness, but still usable) P: Defective (has defects or unevenness throughout) <Glossy> Ex: Excellent (glossy) G: Good (slightly less glossy) F: Acceptable (Low gloss, but usable) P: Defective (no gloss)

[0112] Production Example 1 (Preparation of Mannich reaction composition of MXDA-phenol-formaldehyde (1 / 1.2 / 1.2)) In a 1-liter flask equipped with a stirrer, thermometer, nitrogen inlet tube, dropping funnel, and condenser, 136 g (1 mole) of metaxylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 113 g (1.2 moles) of phenol were charged, and the mixture was heated to 80°C while stirring under a nitrogen stream. Next, 97 g (1.2 moles) of formalin (37% aqueous solution containing 8% methanol) was added dropwise over 1.5 hours at 80°C. After the addition was complete, the temperature was raised to 100°C and the reaction was carried out for 1.5 hours. The temperature was raised to 150°C over 2 hours while distilling off the water, and the reaction was carried out at the same temperature for 1 hour to obtain the Mannich reaction composition of MXDA-phenol-formaldehyde. The reaction molar ratio of MXDA, phenol, and formaldehyde was MXDA / phenol / formaldehyde = 1 / 1.2 / 1.2. The resulting Mannich reaction composition had an AHEW of 102 and an MXDA content of 25% by mass.

[0113] Manufacturing Example 2 (Production of ethylene oxide adducts from xyleneformaldehyde resin) In a pressure-resistant and heat-resistant container equipped with a thermometer, stirrer, nitrogen inlet tube, condenser, and alkylene oxide inlet tube, 100 parts by mass of xylene formaldehyde resin (Nikanol LL, manufactured by Fudo Co., Ltd., weight-average molecular weight: 556, hydroxyl value: 40 mg KOH / g, hydroxyl group equivalent: 1320 g / equivalent, viscosity (25℃): 4700 mPa·s) and 0.1 parts by mass of potassium hydroxide were charged. The reaction was carried out under conditions of a reaction temperature of 155℃ and a pressure of 0.2~0.4 MPa while intermittently feeding 396 parts by mass of ethylene oxide to the mixture. After the above reaction, acetic acid was added to the reaction solution to adjust the pH of the reaction solution to a range of 6.0 to 6.5 and stop the reaction, yielding an ethylene oxide adduct of xyleneformaldehyde resin (weight-average molecular weight: 6000 to 7000, melting point: 56°C, HLB value: 17.7, average number of moles of oxyethylene units added: 119, state (25°C): solid). Furthermore, in the ethylene oxide adduct of xyleneformaldehyde resin, the average number of moles of oxyethylene units added was calculated using the following formula. Average number of moles of oxyethylene units added = (Hydroxyl group equivalent of xyleneformaldehyde resin (g / equivalent) × Amount of ethylene oxide charged (parts by mass)) / (Molar mass of ethylene oxide (g / mol) × Amount of xyleneformaldehyde resin charged (parts by mass))

[0114] Comparative Manufacturing Example 1 (Preparation of Mannich reaction composition of MXDA-phenol-formaldehyde (1 / 1 / 0.67)) A Mannich reaction composition was obtained in the same manner as in Production Example 1, except that the amount of phenol used was changed to 94 g (1 mole) and the amount of formalin (37% aqueous solution containing 8% methanol) used to 54 g (0.67 mole). The obtained Mannich reaction composition had an AHEW of 62 and an MXDA content of 38% by mass.

[0115] Comparative Manufacturing Example 2 (Preparation of Mannich reaction composition of MXDA-phenol-formaldehyde (1 / 1.5 / 1.5)) A Mannich reaction composition was obtained in the same manner as in Production Example 1, except that the amount of phenol used was changed to 141 g (1.5 mol) and the amount of formalin (37% aqueous solution containing 8% methanol) used was changed to 122 g (1.5 mol). The obtained Mannich reaction composition had an AHEW of 118 and an MXDA content of 16% by mass.

[0116] Comparative Manufacturing Example 3 (Preparation of Mannich reaction composition of MXDA-cardanol-formaldehyde (1 / 1.2 / 1.2)) In Production Example 1, a Mannich reaction composition was obtained using the same method as in Production Example 1, except that cardanol ("LB-7000" manufactured by Tohoku Chemical Co., Ltd.) was used instead of phenol, and the amount of cardanol used was changed to 363 g (1.2 mol) and the amount of formalin (37% aqueous solution containing 8% methanol) used was changed to 97 g (1.2 mol). The obtained Mannich reaction composition had an AHEW of 191 and an MXDA content of 23% by mass.

[0117] Comparative Manufacturing Example 4 (Preparation of MXDA-jER828 reaction composition (epoxy adduct) solution) In a 500 ml separable flask equipped with a stirrer, thermometer, nitrogen inlet tube, dropping funnel, and condenser, 136 g (1 mole) of metaxylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.) was charged. Under a nitrogen stream, while stirring, 186 g of a polyfunctional epoxy resin having glycidyloxy groups derived from bisphenol A ("jER828," manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent) (an amount such that the number of active hydrogens in metaxylylenediamine / the number of epoxy groups in the epoxy compound = 2 / 1) was added dropwise over 1 hour. After the dropwise addition was complete, the temperature was raised to 80°C and the reaction was carried out for 2 hours to obtain the MXDA-jER828 reaction composition. Benzyl alcohol was added to this to a concentration of 25% by mass of the total volume to dilute it and obtain a solution of the reaction composition with a concentration of 75% by mass. The AHEW of the MXDA-jER828 reaction composition (excluding benzyl alcohol) was 107, and the MXDA content was 12% by mass.

[0118] Example 1-1 (Production and evaluation of emulsion-type epoxy resin curing agent composition) As component (A), the Mannich reaction composition obtained in Production Example 1 was used, and as component (B), polyoxyethylene styrene-phenyl ether ("Neugen EA-207D", manufactured by Daiichi Kogyo Seiyaku Co., Ltd., HLB: 18.7, active ingredient amount: 55% by mass (residue: water)) was used. As component (C), benzyl alcohol was used. Components (A), (B), and (C) were weighed into a container in the amounts shown in Table 1, and mixed at 1000 rpm using a disperser. 4 g of water was then added and mixed at 1000 rpm for 1 minute. Next, 2 g of water was added and mixed at 1000 rpm for 1 minute. This process was repeated six times to obtain an emulsion-type epoxy resin curing agent composition. The resulting curing agent composition was evaluated for emulsification using the method described above. The AHEW and evaluation results for the curing agent composition are shown in Table 1.

[0119] Comparative Examples 1-1 to 1-3 The emulsion-type epoxy resin curing agent composition was manufactured and evaluated in the same manner as in Example 1-1, except that component (A') listed in Table 1 was used instead of component (A), and the amounts of component (A') and component (B) were changed as shown in Table 1. The results are shown in Table 1.

[0120] Comparative Example 1-4 The emulsion-type epoxy resin curing agent composition was manufactured and evaluated in the same manner as in Example 1-1, except that 24 g of the MXDA-jER828 reaction composition solution obtained in Comparative Manufacturing Example 4 (benzyl alcohol content: 6 g) was used instead of component (A), and 2 g of the ethylene oxide adduct of xyleneformaldehyde resin obtained in Manufacturing Example 2 (HLB: 17.7) was used as component (B). The results are shown in Table 1. Note that the amounts (g) listed in Table 1 are all amounts of active ingredients.

[0121] [Table 1]

[0122] As shown in Table 1, the curing agent compositions of Comparative Examples 1-1 and 1-2, which used Mannich reaction compositions in which the reaction molar ratio of MXDA-phenol-formaldehyde was outside the specified range of the present invention, showed significantly inferior emulsifying properties. In the following comparative examples, only the curing agent compositions of Comparative Examples 1-3 and 1-4, which received an "A" rating for emulsification, were used to manufacture and evaluate the water-based epoxy resin compositions.

[0123] Example 2-1 (Production and evaluation of aqueous epoxy resin composition) As the curing agent composition, the curing agent composition obtained in Example 1-1 was used, and as the main component, "Araldite PZ 3961-1" (an aqueous emulsion of a solid epoxy resin having a glycidyloxy group derived from bisphenol A, manufactured by HUNTSMAN Advanced Materials, epoxy equivalent (solids): 503 g / equivalent, solids concentration: 53% by mass, water content: 40% by mass, methoxypropanol content: 7% by mass) was used. The curing agent composition and the main component were mixed in the proportions shown in Table 2 to prepare an aqueous epoxy resin composition with the composition shown in Table 2. Various evaluations were performed using the obtained aqueous epoxy resin composition according to the method described above. The results are shown in Table 2.

[0124] Example 2-2, Comparative Examples 2-1 to 2-4 A water-based epoxy resin composition was prepared and evaluated in the same manner as in Example 2-1, except that the curing agent composition described in Table 2 was used and the curing agent composition was mixed with the main component in the proportions shown in Table 2. The results are shown in Table 2. Note that the ingredient amounts (mass %) listed in Table 2 are all in their natural form.

[0125] [Table 2]

[0126] Table 2 shows that the water-based epoxy resin composition containing the emulsion-type epoxy resin curing agent composition of this example has a shorter half-curing time (Dust Free) under low-temperature conditions than the water-based epoxy resin compositions of Comparative Examples 2-1 and 2-2, and also exhibits better pencil hardness, water resistance, and appearance of the coating film. Furthermore, it can be seen that the water resistance of the coating film during low-temperature curing is better compared to the water-based epoxy resin compositions of Comparative Examples 2-3 and 2-4.

[0127] According to the present invention, it is possible to provide an emulsion-type epoxy resin curing agent composition that can prepare an aqueous epoxy resin composition having good emulsification properties, good low-temperature curing properties, and good water resistance of the coating film after low-temperature curing, and an aqueous epoxy resin composition containing the emulsion-type epoxy resin curing agent composition.

Claims

1. Component (A): A reaction composition obtained by reacting 1 mole of xylylenediamine (a1) with more than 1 mole but less than 1.5 moles of phenol (a2) and more than 1 mole but less than 1.5 moles of an aldehyde compound (a3) ​​in a Mannich reaction. Ingredient (B): Nonionic emulsifier having an aromatic ring with an HLB value of 14.0 or higher. Component (C): At least one cosolvent selected from the group consisting of propylene glycol monomethyl ether, propylene glycol n-propyl ether, propylene glycol n-butyl ether, benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, and aromatic hydrocarbon formaldehyde resin, and An emulsion-type epoxy resin curing agent composition containing water.

2. The emulsion-type epoxy resin curing agent composition according to claim 1, wherein component (B) comprises at least one selected from the group consisting of polyoxyethylene styrene-derived phenyl ether and ethylene oxide adducts of aromatic hydrocarbon formaldehyde resins.

3. The emulsion-type epoxy resin curing agent composition according to claim 1, wherein the content of component (A) in the emulsion-type epoxy resin curing agent composition is 10 to 60% by mass.

4. The emulsion-type epoxy resin curing agent composition according to claim 1, wherein the content of component (B) is 0.1 to 20% by mass relative to 100% by mass of the total of component (A) and component (B).

5. The emulsion-type epoxy resin curing agent composition according to claim 1, wherein the mass ratio of component (C) to the total mass of component (A) and component (B) is 0.01 to 3.

0.

6. The emulsion-type epoxy resin curing agent composition according to claim 1, wherein the content of unreacted xylylenediamine (a1) in component (A) is 35% by mass or less.

7. The emulsion-type epoxy resin curing agent composition according to claim 1, wherein the emulsion is an oil-in-water emulsion.

8. A water-based epoxy resin composition obtained by mixing the emulsion-type epoxy resin curing agent composition according to any one of claims 1 to 7 with an epoxy resin emulsion.

9. The aqueous epoxy resin composition according to claim 8, wherein the epoxy resin in the epoxy resin emulsion includes a solid epoxy resin.

10. A method for producing the aqueous epoxy resin composition according to claim 8, comprising the following steps (I) to (III) in order. Step (I): A step of mixing components (A), (B), and (C) to prepare mixture 1. Step (II): A step in which water is added to the mixture 1 and stirred to perform phase inversion emulsification in order to obtain an emulsion-type epoxy resin curing agent composition. Step (III): A step of mixing the emulsion-type epoxy resin curing agent composition with the epoxy resin emulsion.

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