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

Emulsion-type epoxy resin curing agent composition and water-based epoxy resin composition

[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.

[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 an aqueous coating material. For example, Patent Document 1 discloses that an aqueous epoxy resin composition containing a water-soluble epoxy resin and a curing agent composition containing a reaction product of epichlorohydrin and a specific amine compound in a specific ratio has good workability and provides excellent coating film adhesion and chemical resistance, particularly saltwater corrosion resistance. However, since the reaction product contained in the curing agent composition is water-soluble, there is a limit to the improvement in the water resistance of the coating film.

[0005] Therefore, emulsion-type curing agents in which a water-insoluble polyamine curing agent is dispersed in water are also known as curing agents for aqueous epoxy resins (see, for example, Patent Documents 2 to 4). Generally, emulsion-type curing agents are required to have good emulsion stability in addition to curing performance. Patent Document 2 discloses a method for producing a curing agent suitable for curing aqueous epoxy resin emulsions, which comprises condensing xylylenediamine, aldehydes having 1 to 3 carbon atoms, and phenols having a hydrocarbon group having 4 or more carbon atoms as essential components, and then forming the resulting aqueous emulsion. It is described that the curing agent has excellent stability, curing ability, chemical resistance, coating performance, etc. Patent Document 3 discloses an aqueous dispersion of a modified polyamine containing a nonionic emulsifier containing a block copolymer of polyethylene glycol and polypropylene glycol, and indicates that the dispersion has good emulsion stability. Patent Document 4 discloses an emulsifier composition whose main component is a compound obtained by reacting a specified polyamide with a specified reactive organic compound, and an epoxy resin curing agent composition containing the emulsifier composition. It is also described that these emulsifier compositions and epoxy resin curing agent compositions exhibit good dispersibility and storage stability when an aqueous epoxy resin composition is prepared, and that the cured product has excellent physical properties such as water resistance.

[0006] International Publication No. 2020 / 110601 Japanese Patent Application Laid-Open No. 48-78254 Japanese Patent Application Laid-Open No. 2005-187757 Japanese Patent Application Laid-Open No. 2007-91976

[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 compositions obtained after mixing with a base epoxy resin, and the water resistance of the coating film after low-temperature curing was not sufficient. An object of the present invention is to provide an emulsion-type epoxy resin curing agent composition that can prepare an aqueous epoxy resin composition that has good emulsifiability, 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.

[0008] The present inventors have found that an emulsion-type epoxy resin curing agent composition containing a specific amine-based curing agent, a specific nonionic emulsifier, a cosolvent, and water can solve the above-mentioned problems. Specifically, the present invention relates to the following: [1] An emulsion-type epoxy resin curing agent composition containing: [A] a reaction composition obtained by subjecting 1 mole of xylylenediamine (a1) to a Mannich reaction of more than 1 mole but less than 1.5 moles of at least one compound (a2) selected from the group consisting of phenol and phenolic compounds having an alkyl group containing 3 or less carbon atoms with more than 1 mole but less than 1.5 moles of an aldehyde compound (a3); [B] a nonionic emulsifier having an aromatic ring and an HLB value of 14.0 or greater; [C] a cosolvent; and [2] the emulsion-type epoxy resin curing agent composition according to [1], wherein component (B) contains at least one member selected from the group consisting of polyoxyethylene styrenated phenyl ether and an ethylene oxide adduct of an aromatic hydrocarbon-formaldehyde resin. [3] The emulsion-type epoxy resin curing agent composition according to [1] or [2], wherein the component (C) contains a cosolvent having a hydroxy group. [4] The emulsion-type epoxy resin curing agent composition according to any one of [1] to [3], wherein the content of the component (A) in the emulsion-type epoxy resin curing agent composition is 10 to 60 mass%. [5] The emulsion-type epoxy resin curing agent composition according to any one of [1] to [4], wherein the content of the component (B) is 0.1 to 20 mass% relative to 100 mass% of the total of the components (A) and (B). [6] The emulsion-type epoxy resin curing agent composition according to any one of [1] to [5], wherein the mass ratio of the component (C) to the total mass of the components (A) and (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) contains 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 the component (A) is 35 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.

[10] An aqueous epoxy resin composition obtained by mixing the emulsion-type epoxy resin curing agent composition according to any one of [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 contains a solid epoxy resin.

[12] A method for producing the aqueous epoxy resin composition according to

[10] or

[11] , comprising the following steps (I) to (III) in order: Step (I): mixing the components (A), (B), and (C) to prepare mixture 1; Step (II): adding water to mixture 1 and stirring the mixture to effect phase inversion emulsification, thereby obtaining an emulsion-type epoxy resin curing agent composition; and Step (III): mixing the emulsion-type epoxy resin curing agent composition with the epoxy resin emulsion.

[0009] According to the present invention, there can be provided an emulsion-type epoxy resin curing agent composition capable of preparing an aqueous epoxy resin composition having good emulsifiability, low-temperature curing properties, and excellent water resistance of the coating film after low-temperature curing, as well as an aqueous epoxy resin composition containing the emulsion-type epoxy resin curing agent composition.

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

[0011] In this specification, the term "waterborne epoxy resin composition" refers to 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, and having a water content of preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and still more preferably 30% by mass or more.

[0012] In this specification, the term "reaction composition obtained by subjecting X, Y, and Z to the Mannich reaction" refers to a composition obtained by subjecting X, Y, and Z to the Mannich reaction, which contains not only the reaction products of X, Y, and Z, but also by-products other than the reaction products, unreacted raw materials, and the like.

[0013] In this specification, the low-temperature curing property of an aqueous epoxy resin composition is determined using the semi-drying (dust-free) time under conditions of 5°C and 80% RH as an index. The low-temperature curing property and the water resistance of the coating film after low-temperature curing can be specifically evaluated by the method 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 "curing agent composition (of the present invention)") is an emulsion-type epoxy resin curing agent composition containing: component (A): a reaction composition obtained by subjecting 1 mole of xylylenediamine (a1) to a Mannich reaction of more than 1 mole but less than 1.5 moles of at least one compound (a2) selected from the group consisting of phenol and phenolic compounds having an alkyl group containing 3 or less carbon atoms, and more than 1 mole but less than 1.5 moles of an aldehyde compound (a3); component (B): a nonionic emulsifier having an aromatic ring and an HLB value of 14.0 or greater; component (C): a cosolvent; and water. The curing agent composition of the present invention has the above-mentioned configuration, and thereby exhibits the effect of enabling the preparation of an aqueous epoxy resin composition that has good emulsifiability, low-temperature curing properties, and excellent water resistance of the coating film after low-temperature curing.

[0015] The reason why the above-mentioned effects are achieved in the present invention is unclear, but is thought to be as follows. The reaction composition used as component (A) is a composition obtained by subjecting 1 mole of xylylenediamine (a1) to a Mannich reaction of at least one compound (a2) selected from the group consisting of phenol and phenolic compounds having an alkyl group containing 3 or less carbon atoms with an aldehyde compound (a3) ​​in specific ratios, and functions as an epoxy resin curing agent. Here, when compound (a2) is at least one selected from the group consisting of phenol and phenolic compounds having an alkyl group containing 3 or less carbon atoms, the resulting aqueous epoxy resin composition is less likely to produce a coating film that is sticky when cured under low-temperature conditions, and both the low-temperature curability and the water resistance of the coating film after low-temperature curing are thought to be improved. Furthermore, it is thought that by reacting xylylenediamine (a1), compound (a2), and aldehyde compound (a3) ​​in specific ratios, the emulsification properties of component (A) when used with components (B) and (C) are further improved. Specifically, it is believed that when the reaction ratio of compound (a2) and / or aldehyde compound (a3) ​​to 1 mole of xylylenediamine (a1) is more than 1 mole, it is possible to suppress a decrease in emulsifying ability caused by an increase in the content of unreacted xylylenediamine (a1) in component (A). On the other hand, when 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 a decrease in emulsifying ability caused by an excessive increase in viscosity of the resulting reaction composition can be suppressed.

[0016] Components (B) and (C) are used to stably emulsify component (A). The nonionic emulsifier of component (B) has an HLB value of 14.0 or higher, which gives it good affinity with water, and the presence of an aromatic ring gives it good affinity with component (A). Therefore, it is believed that the emulsification performance of component (A) in water is high. Furthermore, component (C) is capable of dissolving components (A) and (B) and also has affinity with water, so it is believed that an emulsion-type epoxy resin curing agent composition with high emulsion stability can be easily produced by the phase inversion emulsification method described below.

[0017] <Component (A): Mannich reaction composition> Component (A) is a reaction composition obtained by subjecting 1 mole of xylylenediamine (a1) to a Mannich reaction with more than 1 mole but less than 1.5 moles of at least one compound (a2) selected from the group consisting of phenol and phenolic compounds having an alkyl group containing 3 or less carbon atoms, and more than 1 mole but less than 1.5 moles of an aldehyde compound (a3). 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 metaxylylenediamine, and even more preferably metaxylylenediamine.

[0019] (At least one compound (a2) selected from the group consisting of phenol and phenolic compounds having an alkyl group having 3 or less carbon atoms) The compound (a2) is at least one compound selected from the group consisting of phenol and phenolic compounds having an alkyl group having 3 or less carbon atoms. Specific examples of the 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 emulsifiability, and from the viewpoint of improving the low-temperature curing properties of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing, the compound (a2) preferably includes at least one compound selected from the group consisting of phenol and cresol, and more preferably includes phenol.

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

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

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

[0023] In the Mannich reaction, 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) ​​are reacted with 1 mole of xylylenediamine (a1). 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 viewpoints of improving emulsifiability, and improving the low-temperature curing properties of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing. Furthermore, 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 viewpoints as above.

[0024] (Content of Unreacted Xylylenediamine (a1) in Component (A)) From the viewpoint of improving emulsifiability, 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. The lower limit is not particularly limited, and may be 0% by mass. Note that the "content of unreacted xylylenediamine (a1) in component (A)" here refers to the content of free xylylenediamine (a1), which is an unreacted raw material, 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] (Active Hydrogen Equivalent (AHEW) of Component (A)) From the viewpoint of exhibiting good curing performance even when the amount blended into the aqueous epoxy resin composition is small, 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 ease of production, etc., 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] <Component (B): Aromatic Ring-Containing Nonionic Emulsifier with an HLB Value of 14.0 or More> Component (B) is an aromatic ring-containing nonionic emulsifier with an HLB value of 14.0 or more. Here, HLB (hydrophile-lipophile balance) is a value indicating the affinity of the emulsifier (component (B)) for water and oil, and can be calculated using 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 group include a hydroxy group and an ethyleneoxy group (EO).

[0027] From the viewpoint of improving emulsifiability, 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, still more preferably 17.0 to 19.5, and even more preferably 17.5 to 19.0.

[0028] The nonionic emulsifier, component (B), may contain one or more aromatic rings. The "aromatic ring" referred to here may be either a single ring or a condensed ring, such as a benzene ring, a naphthalene ring, or an anthracene ring, with a benzene ring being preferred. From the viewpoint of further improving emulsifiability, as well as improving the low-temperature curing properties of the resulting aqueous 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 on 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 of component (B) preferably has a polyoxyethylene structure from the viewpoint of achieving an HLB value of 14.0 or more. The average number of moles of oxyethylene units added in 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 achieving an HLB value of 14.0 or more and further improving emulsifiability.

[0030] Examples of the nonionic emulsifier having an aromatic ring and a polyoxyethylene structure, which is used as component (B), include polyoxyethylene aryl ethers such as polyoxyethylene phenyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene naphthyl ether, polyoxyethylene bisphenol A ether, and polyoxyethylene bisphenol F ether; polyoxyethylene alkyl aryl ethers such as polyoxyethylene benzyl ether and polyoxyethylene dodecyl phenyl ether; ethylene oxide adducts of aromatic hydrocarbon formaldehyde resins; and ethylene oxide adducts of modified aromatic hydrocarbon formaldehyde resins; and one or more of these may be used. Among the above, from the viewpoint of improving emulsifiability, component (B) preferably contains at least one selected from the group consisting of polyoxyethylene styrenated phenyl ether, an ethylene oxide adduct of an aromatic hydrocarbon formaldehyde resin, and an ethylene oxide adduct of a modified aromatic hydrocarbon formaldehyde resin, and more preferably contains at least one selected from the group consisting of polyoxyethylene styrenated phenyl ether and an ethylene oxide adduct of an aromatic hydrocarbon formaldehyde resin.

[0031] (Polyoxyethylene styrenated phenyl ether) In this specification, polyoxyethylene styrenated phenyl ether encompasses various polyoxyethylene styrenated phenyl ethers such as polyoxyethylene monostyrenated phenyl ether, polyoxyethylene distyrenated phenyl ether, and polyoxyethylene tristyrenated phenyl ether, as well as mixtures thereof. Among these, the polyoxyethylene styrenated phenyl ether preferably comprises at least one selected from the group consisting of polyoxyethylene monostyrenated phenyl ether and polyoxyethylene distyrenated phenyl ether, and more preferably comprises polyoxyethylene distyrenated phenyl ether. As polyoxyethylene styrenated phenyl ethers having an HLB value of 14.0 or more, commercially available products such as "NOIGEN EA-207D" (HLB 18.7) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. and "BLAUNON TSP-50" (HLB 16.9) manufactured by Aoki Oil & Fat Industries Co., Ltd. can also be used.

[0032] (Ethylene oxide adduct of aromatic hydrocarbon formaldehyde resin) The ethylene oxide adduct of aromatic hydrocarbon formaldehyde resin is a compound obtained by an addition reaction between an aromatic hydrocarbon formaldehyde resin and ethylene oxide.

[0033] [Aromatic hydrocarbon formaldehyde resin] Aromatic hydrocarbon formaldehyde resin is a resin obtained by reacting an aromatic hydrocarbon with formaldehyde. In this specification, aromatic hydrocarbon formaldehyde resin refers to an unmodified aromatic hydrocarbon formaldehyde resin that is not modified with other functional groups or the like. Examples of the aromatic hydrocarbon 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 properties, the aromatic hydrocarbon preferably includes at least one selected from the group consisting of toluene, xylene, mesitylene, and pseudocumene, and more preferably includes xylene.

[0034] As formaldehyde, formalin and paraformaldehyde, which are easily available industrially, as well as compounds that generate formaldehyde, such as trioxane, can be used.

[0035] The aromatic hydrocarbon formaldehyde resin preferably includes at least one selected from the group consisting of a toluene formaldehyde resin obtained by reacting toluene with formaldehyde, a xylene formaldehyde resin obtained by reacting xylene with formaldehyde, a mesitylene formaldehyde resin obtained by reacting mesitylene with formaldehyde, and a pseudocumene formaldehyde resin obtained by reacting pseudocumene with formaldehyde, and more preferably includes a xylene formaldehyde resin.

[0036] From the viewpoint of improving emulsifiability, the content of the xylene formaldehyde resin in the 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, 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 is 100% by mass or less.

[0037] From the viewpoint of improving emulsifiability, the weight average molecular weight (Mw) of the aromatic hydrocarbon formaldehyde resin is, in terms of standard polystyrene, preferably 200 to 10,000, more preferably 300 to 8,000, even more preferably 350 to 5,000, still more preferably 400 to 3,000, still more preferably 400 to 1,500, and even more preferably 500 to 1,000. The weight average molecular weight (Mw) can be measured by gel permeation chromatography (GPC).

[0038] From the viewpoint of improving emulsifiability, the viscosity of the 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, still more preferably 300 to 15,000 mPa·s, still more preferably 500 to 10,000 mPa·s, still more preferably 1,000 to 10,000 mPa·s, still more preferably 2,000 to 10,000 mPa·s, and still more preferably 3,000 to 8,000 mPa·s. 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 additivity and improved emulsifiability. The hydroxyl value can be measured by the method described in JIS K0070-1992.

[0040] From the viewpoint of ethylene oxide additivity and improved emulsifiability, the hydroxyl equivalent (g / equivalent) of the 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 still more preferably 1,000 to 1,500 g / equivalent. The hydroxyl equivalent can be determined by measuring the hydroxyl value according to the method described in JIS K0070-1992 and converting the hydroxyl value to a hydroxyl equivalent.

[0041] The aromatic hydrocarbon-formaldehyde resin may be a commercially available product or may be produced by a known method, such as the method described in Japanese Patent Publication No. 37-5747, in which an aromatic hydrocarbon and formaldehyde are subjected to a condensation reaction in the presence of a catalyst.

[0042] Commercially available aromatic hydrocarbon formaldehyde resins include, for example, xylene formaldehyde resins manufactured by Fudow Co., Ltd., such as "Nikanol Y-50," "Nikanol Y-100," "Nikanol Y-300," "Nikanol Y-1000," "Nikanol L," "Nikanol LL," "Nikanol LLL," "Nikanol G," "Nikanol H," and "Nikanol H-80."

[0043] The ethylene oxide adduct of an aromatic hydrocarbon-formaldehyde resin can be obtained by reacting the aromatic hydrocarbon-formaldehyde resin with ethylene oxide in the presence of a basic catalyst under heated and pressurized conditions. More specifically, the aromatic hydrocarbon-formaldehyde resin and the basic catalyst are charged into a reactor equipped with a heating and pressurizing mechanism such as an autoclave, and ethylene oxide is fed thereto to react them under heated and pressurized conditions.

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

[0045] The basic catalyst used in the reaction can be either an inorganic base or an organic base. 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, and amines such as triethylamine. These bases can be used alone or in combination of two or more. Among the basic catalysts, from the viewpoints of improving reaction efficiency and economy, inorganic bases are preferred, alkali metal hydroxides are more preferred, and potassium hydroxide is even more preferred.

[0046] From the viewpoint of improving the reaction efficiency, the reaction temperature in the above reaction is preferably 100 to 190°C, more preferably 140 to 190°C. 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 still more preferably 1 to 7 hours. The reaction time here also includes the feed time of ethylene oxide. The pressure during the above reaction is preferably a pressure exceeding normal pressure (1 atmosphere; 0.1013 MPa), and is 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 emulsifiability, the weight average molecular weight of the ethylene oxide adduct of the aromatic hydrocarbon formaldehyde resin is, in terms of standard polystyrene, preferably 1,000 to 100,000, more preferably 2,000 to 50,000, even more preferably 3,000 to 25,000, and still more preferably 4,000 to 20,000. The weight average molecular weight is determined by the same method as described above.

[0048] (Ethylene oxide adduct of modified aromatic hydrocarbon-formaldehyde resin) The ethylene oxide adduct of modified aromatic hydrocarbon-formaldehyde resin is a compound obtained by an addition reaction between a modified aromatic hydrocarbon-formaldehyde resin and ethylene oxide.

[0049] [Modified aromatic hydrocarbon formaldehyde resin] The modified aromatic hydrocarbon formaldehyde resin is a resin obtained by modifying the aromatic hydrocarbon formaldehyde resin with a phenol, a polyol, etc. From the viewpoint of improving emulsifiability, the modified aromatic hydrocarbon formaldehyde resin is preferably a resin obtained by modifying an aromatic hydrocarbon formaldehyde resin with a phenol.

[0050] The phenols include naturally occurring phenolic compounds such as phenol, alkylphenols, alkenylphenols, terpene phenols, cardanol, etc. The number of carbon atoms in the alkyl group of the alkylphenol is preferably 1 to 24, more preferably 1 to 18, and the number of carbon atoms in the alkenyl group of the alkenylphenol is preferably 2 to 24, more preferably 2 to 18. Specific examples of phenols include phenol, cresol, ethylphenol (e.g., p-ethylphenol), isopropylphenol (e.g., o-isopropylphenol, p-isopropylphenol), butylphenol (e.g., p-tert-butylphenol, p-sec-butylphenol, o-tert-butylphenol, o-sec-butylphenol), amylphenol (e.g., p-tert-amylphenol, o-tert-amylphenol), p-octylphenol, nonylphenol, p-cumylphenol, decylphenol, undecylphenol, p-dodecylphenol, tridecylphenol, tetradecylphenol, pentadecylphenol, pentadecenylphenol, pentadecadienylphenol, pentadecatrienylphenol, hexadecylphenol, heptadecylphenol, octadecylphenol, octadecenylphenol, terpene phenol, and cardanol, and these may be used alone or in combination. 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] Examples of the polyols include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, trimethylolpropane, and neopentyl glycol, and these may be used alone or in combination of two or more.

[0052] The modified aromatic hydrocarbon-formaldehyde resin can be obtained, for example, by reacting the aromatic hydrocarbon-formaldehyde resin with a phenol or a polyol in the presence of an acid or base catalyst.

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

[0054] The ethylene oxide adduct of a modified aromatic hydrocarbon-formaldehyde resin can be obtained by reacting a modified aromatic hydrocarbon-formaldehyde resin with ethylene oxide in the same manner as in the production of the ethylene oxide adduct of an aromatic hydrocarbon-formaldehyde resin. The production conditions, weight-average molecular weight, and preferred embodiments thereof are the same as those of the ethylene oxide adduct of an aromatic hydrocarbon-formaldehyde resin.

[0055] <Component (C): Cosolvent> The cosolvent of component (C) is a solvent that is capable of dissolving components (A) and (B) and has affinity for water. From the viewpoint of reducing volatile organic compounds (VOCs) and suppressing volatilization during the production process of component (C) and maintaining good emulsifiability, component (C) comprises a solvent whose boiling point at normal pressure is preferably 120°C or higher, more preferably 150°C or higher, even more preferably 160°C or higher, still more preferably 170°C or higher, and even more preferably 180°C or higher.

[0056] The cosolvent used as component (C) preferably contains a cosolvent having a hydroxy group, from the viewpoint of improving emulsifiability and improving the low-temperature curing properties of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing. The cosolvent having a hydroxy group is a cosolvent having at least one hydroxy group, and may have a chain structure or a ring structure. From the viewpoint of improving emulsifiability and improving the low-temperature curing properties 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 hydroxy group and a ring structure. Specific examples of the cosolvent having a hydroxy group 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 here has the same meaning as the aromatic hydrocarbon formaldehyde resin described for component (B). Commercially available aromatic hydrocarbon formaldehyde resins used as component (C) include xylene formaldehyde resins such as "Nikanol Y-50," "Nikanol Y-100," and "Nikanol Y-300" manufactured by Fudoh Co., Ltd.

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

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

[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). Examples of epoxy resin curing agent components other than component (A) include compounds having two or more active hydrogen-containing groups capable of reacting with epoxy groups in the base resin used in the aqueous epoxy resin composition. Examples of such epoxy resin curing agent components include amine-based curing agents, phenol-based curing agents, acid anhydride-based curing agents, and hydrazide-based curing agents. However, from the viewpoints of improving emulsifiability and improving the low-temperature curing properties of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing, the content of component (A) in the epoxy resin curing agent components 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, but not more than 100% by mass.

[0060] <Contents> The contents of each component in the emulsion-type epoxy resin curing agent composition are preferably in 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 still more preferably 40 to 55% by mass, from the viewpoints of improving emulsifiability, and improving the low-temperature curing properties of the resulting aqueous 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, still more preferably 1 to 12% by mass, still more preferably 2 to 10% by mass, and still more preferably 2 to 8% by mass, from the viewpoint of improving emulsifiability, and from the viewpoint of improving the low-temperature curing properties of the resulting aqueous 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 the total of component (A) and component (B) (100% by mass) is preferably 0.1 to 20% by mass, more preferably 0.5 to 18% by mass, even more preferably 1 to 15% by mass, still more preferably 3 to 15% by mass, and still more preferably 5 to 12% by mass, from the viewpoints of improving emulsifiability, low-temperature curing properties of the resulting aqueous epoxy resin composition, and improving the water resistance of the coating film after low-temperature curing.

[0063] From the viewpoint of improving emulsifiability, the total content of component (A) and component (B) in the curing agent composition is preferably 10.5 to 70 mass%, more preferably 20 to 65 mass%, even more preferably 30 to 65 mass%, still more preferably 35 to 60 mass%, and even more preferably 40 to 60 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 still more preferably 5 to 15% by mass, from the viewpoint of improving emulsifiability, low-temperature curing properties of the resulting aqueous epoxy resin composition, and water resistance of the coating film after low-temperature curing.

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

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

[0067] From the viewpoint of emulsion stability, the content of water 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, still more preferably 35 to 60% by mass, and even more preferably 35 to 50% by mass. The content of water in the curing agent composition may be the remainder of components (A) to (C).

[0068] <Other Components> The curing agent composition may further contain other components such as a modifying component such as a filler or a plasticizer, a flow adjusting component such as a thixotropic agent, a leveling agent, a dispersant, an antifoaming agent, or a tackifier depending on the application.

[0069] <Method for producing 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 emulsifiability, it is preferable to produce it by a method having the following steps (I) and (II) in this order: Step (I): mixing the components (A), (B), and (C) to prepare mixture 1 Step (II): adding water to mixture 1 and stirring the mixture to cause phase inversion emulsification 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 an aqueous epoxy resin composition.

[0070] <Form of Curing Agent Composition> The emulsion in the emulsion-type epoxy resin curing agent composition 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 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 emulsifiability and handleability, it is preferably in the range of 120 to 1,000, more preferably 150 to 800, even more preferably 150 to 600, and still more preferably 150 to 400.

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

[0073] <Epoxy Resin Emulsion> The epoxy resin emulsion is the main component of the aqueous epoxy resin composition and is an emulsion containing at least an 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 an epoxy group that reacts with the active hydrogen contained in the epoxy resin curing agent component in the curing agent composition. From the viewpoint of improving the low-temperature curing properties 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 contains a solid epoxy resin, and more preferably contains a solid epoxy resin containing 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.

[0075] Specific preferred examples of the epoxy resin 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.

[0076] Among the above, from the viewpoint of improving the low-temperature curing properties of the resulting 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 epoxy resins having a glycidylamino group derived from metaxylylenediamine, epoxy resins having a glycidyloxy group derived from bisphenol A, and epoxy resins having a glycidyloxy group derived from bisphenol F, more preferably at least one selected from the group consisting of epoxy resins having a glycidyloxy group derived from bisphenol A and epoxy resins having a glycidyloxy group derived from bisphenol F, and even more preferably 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 emulsion stability, 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 curability of the resulting aqueous epoxy resin composition.

[0078] 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.

[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. 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 improving the low-temperature curing properties of the resulting aqueous 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 having no reactive groups, and more preferably includes a nonionic emulsifier having no reactive groups. Examples of the nonionic emulsifier include polyether compounds, ester compounds, and alkanolamide compounds. The emulsifier used in the epoxy resin emulsion may also include the aforementioned component (B). The emulsifiers may be used alone or in combination of two or more.

[0080] 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, relative to 100 parts by mass of the epoxy resin. When the content of the emulsifier is 0.1 part by mass or more relative to 100 parts by mass of the epoxy resin, emulsion stability is improved, and when it is 40 parts by mass or less, the low-temperature curing properties of the resulting aqueous epoxy resin composition and the water resistance of the coating film after low-temperature curing can be maintained well.

[0081] (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 %.

[0082] 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.

[0083] <Mixing Ratio> The aqueous 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 and the epoxy resin emulsion is such that the number of active hydrogens in the epoxy resin curing agent component relative to the number of epoxy groups in the epoxy resin (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 aqueous 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 still more preferably 5 to 10% by mass, from the viewpoint of emulsion stability, and from the viewpoint of improving low-temperature curing properties 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 still more preferably 5 to 12% by mass, from the viewpoints of emulsion stability, low-temperature curing ability, and improving the water resistance of the coating film after low-temperature curing. The "content of the epoxy resin curing agent component" referred to here also includes the content of the component (A).

[0086] The content of the epoxy resin 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 50% by mass, from the viewpoint of emulsion stability and improving low-temperature curing properties 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 mass%, more preferably 0.2 to 3 mass%, even more preferably 0.3 to 2 mass%, and still more preferably 0.3 to 1 mass%, from the viewpoint of improving emulsion stability and preparing an aqueous epoxy resin composition having a long pot life.

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

[0089] Of the nonvolatile components in the aqueous 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 still more preferably 30 to 70% by mass, in terms of emulsion stability, and improving low-temperature curing properties and water resistance of the coating film after low-temperature curing.

[0090] 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, from the viewpoints of emulsion stability, low-temperature curing ability, and improving the 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 water content here refers to the total amount of water contained in the aqueous epoxy resin composition.

[0091] <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. When the aqueous epoxy resin composition contains a pigment, it can also achieve improved chemical resistance. When the aqueous epoxy resin composition contains a pigment, the content of the pigment in the aqueous 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 viewpoints of improving colorability and chemical resistance, and improving the water resistance of the resulting coating film.

[0092] Although the aqueous epoxy resin composition of the present invention does not exclude the inclusion of an organic solvent other than component (C), it is preferable that the content of the organic solvent be small. The content of the organic solvent 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 from the viewpoint of improving emulsifiability, low-temperature curing properties, and water resistance of the coating film after low-temperature curing, it preferably includes the following steps (I) to (III) in this order: Step (I): Mixing the components (A), (B), and (C) to prepare mixture 1; Step (II): Adding water to mixture 1 and stirring the mixture to effect phase inversion emulsification, thereby obtaining an emulsion-type epoxy resin curing agent composition; Step (III): Mixing the emulsion-type epoxy resin curing agent composition with the epoxy resin emulsion.

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

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

[0096] <Step (II)> In step (II), water is added to the mixture 1 obtained in step (I) and stirred to cause 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. Water may be added continuously or in portions. When water is added in portions, the number of portions is preferably 2 to 20, more preferably 3 to 15, from the viewpoint of improving emulsifiability, low-temperature curing properties, and water resistance of the coating film after low-temperature curing. The stirring device may be the same as that used in step (I). Also, known emulsification devices such as a high-pressure emulsification device or an ultrasonic emulsification device may be used.

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

[0098] <Step (III)> In step (III), the emulsion-type epoxy resin curing agent composition obtained in step (II) is mixed with the epoxy resin emulsion. The epoxy resin emulsion, which is the main component, is first made into an emulsion state and then mixed with the emulsion-type epoxy resin curing agent composition, thereby making it possible to prepare an aqueous epoxy resin composition with higher emulsion stability. The preferred mixing ratio of the emulsion-type epoxy resin curing agent composition and the epoxy resin emulsion is as described in the section on aqueous epoxy resin compositions.

[0099] In the mixing step of step (III), the same stirring device as used in step (I) can be used. The temperature during mixing 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 also not particularly limited and is usually selected in the range of 0.5 minutes to 12 hours. Optional components added to the aqueous epoxy resin composition may be added in any step. However, 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 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.

[0101] [Paint] The present invention provides a paint containing the aqueous epoxy resin composition. By containing the aqueous epoxy resin composition, the paint exhibits good low-temperature curing properties and water resistance of the coating film after low-temperature curing. Examples of such paints include anticorrosion paints, marine paints, tank paints, pipe interior paints, 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.

[0102] 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.

[0103] <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.

[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 methods.

[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., 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 xylylenediamine content in Component (A) or Component (A') was calculated from the GC area values ​​of xylylenediamine 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

[0106] (Emulsification) The emulsion-type epoxy resin curing agent compositions shown in Table 1 were produced by the method described below, and the emulsification state was visually observed according to the following criteria. Those rated A or B were considered to be acceptable. <Evaluation criteria> A: Good emulsification state B: Emulsified immediately after production but partially separated after 3 days C: Separated within a few minutes after production D: Separated immediately after production

[0107] (Dry to Touch) A zinc phosphate-treated steel plate (SPCC-SD PB-N144, 0.8 x 70 x 150 mm, manufactured by Paltec Co., Ltd.) was used as the substrate. The aqueous 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 under conditions of 5°C and 80% RH, and evaluated by touch with the finger after 1, 2, and 7 days according to the following criteria: Ex: Excellent (the coating film was not sticky even when pressed with a thumb with a force of about 50 N, and no fingerprints remained). G: Good (the coating film was not sticky when pressed with a thumb with a force of about 50 N, but fingerprints remained after touching with the finger). F: Fair (the coating film was sticky when pressed with a thumb with a force of about 50 N). P: Poor (the coating film was sticky when pressed with a thumb with a force of about 5 N).

[0108] (Pencil Hardness) Each of the aqueous epoxy resin compositions shown in Table 2 was applied to a substrate (zinc phosphate-treated steel plate) in the same manner as described above to form a coating film (thickness immediately after application: 200 μm). This coating film was stored under conditions of 5°C and 80% RH, and the pencil hardness was measured after 1, 2, and 7 days in accordance with JIS K5600-5-4:1999.

[0109] (Water Resistance Spot Test) The waterborne epoxy resin compositions shown in Table 2 were applied to a substrate (zinc phosphate-treated steel plate) in the same manner as above to form a coating film (thickness immediately after application: 200 μm). This coating film was stored under conditions of 5°C and 80% RH, and after 1, 2, and 7 days, 2 to 3 drops of pure water were dropped onto the coating film surface using a dropper, and the spot was covered with a 50 mL screw cap. 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 for a coating film cured under the above conditions, the higher the water resistance of the coating film when cured at low temperature. Ex: Excellent (no change at all) G: Good (slight change) F: Fair (slight whitening, but no problems in use) P: Poor (whitening)

[0110] (Cure Rate (RCI)) The aqueous epoxy resin compositions shown in Table 2 were applied to a glass plate (25 x 348 x 2.0 mm, manufactured by Taiyu Kizai Co., Ltd.) at 5°C and 80% RH using a 76 µm applicator to form a coating film. The glass plate on which the coating film was formed was set in a paint drying time measuring instrument (manufactured by Taiyu Kizai Co., Ltd.), and the needle of the measuring instrument scratched the coating film surface, leaving marks that were observed. The time required to reach each drying stage (Set to Touch, Dust Free, Dry Through) was measured according to the following criteria. A shorter time indicates a faster curing rate. In this specification, a composition with a shorter semi-drying time under the above conditions is considered to have "excellent low-temperature curing properties." Set to Touch: The time until the needle marks start to remain on the glass plate. Dust Free: The time until the needle marks appear on the surface of the coating. Dry Through: The time until the needle marks no longer remain on the coating.

[0111] (Appearance of Coating Film) The aqueous epoxy resin composition shown in Table 2 was applied to a substrate (zinc phosphate-treated steel plate) in the same manner as above to form a coating film (thickness immediately after application: 200 μm). This coating film was stored under conditions of 5° C. and 80% RH. After 7 days, the appearance of the coating film was visually observed and the transparency, smoothness, and gloss were evaluated according to the following criteria. <Transparency> Ex: Excellent (no cloudiness) G: Good (slight cloudiness) F: Fair (slight cloudiness but usable) P: Poor (cloudiness) <Smoothness> Ex: Excellent (no unevenness) G: Good (slight unevenness) F: Fair (some unevenness but usable) P: Poor (cracking or unevenness over the entire surface) <Gloss> Ex: Excellent (glossy) G: Good (slightly inferior gloss) F: Fair (low gloss but usable) P: Poor (no gloss)

[0112] Production Example 1 (Production of MXDA-phenol-formaldehyde (1 / 1.2 / 1.2) Mannich reaction composition) A 1-liter flask equipped with a stirrer, thermometer, nitrogen inlet tube, dropping funnel, and condenser was charged with 136 g (1 mol) of metaxylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 113 g (1.2 mol) of phenol, and the temperature was raised to 80 ° C. while stirring under a nitrogen stream. Next, 97 g (1.2 mol) of formalin (37% aqueous solution containing 8% methanol) was added dropwise at 80 ° C. over 1.5 hours, and after completion of the dropwise addition, 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 water, and the reaction was carried out at the same temperature for 1 hour to obtain a MXDA-phenol-formaldehyde Mannich reaction composition. 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 mass%.

[0113] Production Example 2 (Production of Ethylene Oxide Adduct of Xylene Formaldehyde Resin) A pressure-resistant and heat-resistant vessel equipped with a thermometer, a stirrer, a nitrogen inlet pipe, a cooling pipe, and an alkylene oxide inlet pipe was charged with 100 parts by mass of xylene formaldehyde resin ("Nikanol LL" manufactured by Fudow Co., Ltd., weight average molecular weight: 556, hydroxyl value: 40 mgKOH / g, hydroxyl equivalent: 1320 g / equivalent, viscosity (25°C): 4700 mPa·s) and 0.1 parts by mass of potassium hydroxide, and a reaction was carried out under conditions of a reaction temperature of 155°C and a pressure of 0.2 to 0.4 MPa while intermittently feeding 396 parts by mass of ethylene oxide thereto. After the reaction, acetic acid was added to the reaction solution, and the pH of the reaction solution was adjusted to a range of 6.0 to 6.5 to terminate the reaction, thereby obtaining an ethylene oxide adduct of xylene formaldehyde 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). In the ethylene oxide adduct of xylene formaldehyde 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 xylene formaldehyde resin (g / equivalent) × amount of ethylene oxide charged (parts by mass)) / (molar mass of ethylene oxide (g / mol) × amount of xylene formaldehyde resin charged (parts by mass)).

[0114] Comparative Production Example 1 (Production 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 charged was changed to 94 g (1 mole) and the amount of formalin (37% aqueous solution containing 8% methanol) charged was changed 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 Production Example 2 (Production of a 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 charged was changed to 141 g (1.5 mol) and the amount of formalin (37% aqueous solution containing 8% methanol) charged 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 Production Example 3 (Production of MXDA-cardanol-formaldehyde (1 / 1.2 / 1.2) Mannich reaction composition) A Mannich reaction composition was obtained in the same manner as in Production Example 1, except that cardanol ("LB-7000" manufactured by Tohoku Kako Co., Ltd.) was used instead of phenol, and the amount of cardanol charged was changed to 363 g (1.2 mol), and the amount of formalin (37% aqueous solution containing 8% methanol) charged was changed to 97 g (1.2 mol). The obtained Mannich reaction composition had an AHEW of 191 and an MXDA content of 23 mass%.

[0117] Comparative Production Example 4 (Production of MXDA-jER828 Reaction Composition (Epoxy Adduct) Solution) A separable flask with an internal volume of 500 milliliters equipped with a stirrer, thermometer, nitrogen inlet tube, dropping funnel, and condenser was charged with 136 g (1 mole) of metaxylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.), and while stirring under a nitrogen stream, 186 g (an amount such that the number of active hydrogens in metaxylylenediamine / the number of epoxy groups in the epoxy compound = 2 / 1) of a multifunctional epoxy resin having glycidyloxy groups derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent) was added dropwise over 1 hour. After completion of the dropwise addition, the temperature was raised to 80 ° C. and the reaction was carried out for 2 hours, yielding a MXDA-jER828 reaction composition. Benzyl alcohol was added to the reaction mixture in an amount of 25% by mass to dilute the mixture, thereby obtaining a solution with a reaction composition concentration of 75% by mass. The AHEW of the MXDA-jER828 reaction mixture (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) The Mannich reaction composition obtained in Production Example 1 was used as component (A), and polyoxyethylene styrenated phenyl ether ("Noigen EA-207D", manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., HLB: 18.7, amount of active ingredient: 55 mass% (remainder: water)) was used as component (B). Benzyl alcohol was used as component (C). Components (A), (B), and (C) were weighed into a container in the amounts shown in Table 1, and mixed at 1000 rpm using a disper. 4 g of water was added thereto and mixed at 1000 rpm for 1 minute. Next, 2 g of water was added and mixed at 1000 rpm for 1 minute. This operation was repeated six times to obtain an emulsion-type epoxy resin curing agent composition. The emulsifiability of the obtained curing agent composition was evaluated using the method described above. The AHEW and evaluation results of the curing agent composition are shown in Table 1.

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

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

[0121]

[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 range specified in the present invention, showed significantly poor emulsification properties. Hereinafter, with regard to the curing agent compositions of the comparative examples, only the curing agent compositions of Comparative Examples 1-3 and 1-4, which were rated "A" for emulsification properties, were used to produce and evaluate aqueous epoxy resin compositions.

[0123] Example 2-1 (Preparation and Evaluation of Waterborne Epoxy Resin Composition) The curing agent composition obtained in Example 1-1 was used as the curing agent composition, and "Araldite PZ 3961-1" (aqueous emulsion of a solid epoxy resin having a glycidyloxy group derived from bisphenol A, manufactured by HUNTSMAN Advanced Materials, epoxy equivalent (solid content): 503 g / equivalent, solid content concentration: 53 mass%, water content: 40 mass%, methoxypropanol content: 7 mass%) was used as the base agent. The curing agent composition and base agent were mixed in the ratios shown in Table 2 to prepare waterborne epoxy resin compositions having the compositions shown in Table 2. The obtained waterborne epoxy resin compositions were subjected to various evaluations using the methods described above. The results are shown in Table 2.

[0124] Example 2-2, Comparative Examples 2-1 to 2-4 Aqueous epoxy resin compositions were prepared and evaluated in the same manner as in Example 2-1, except that the curing agent compositions shown in Table 2 were used and the curing agent compositions and the base resin were mixed in the ratios shown in Table 2. The results are shown in Table 2. The blending amounts (mass%) shown in Table 2 are all as is.

[0125]

[0126] As can be seen from Table 2, the aqueous epoxy resin composition containing the emulsion-type epoxy resin curing agent composition of this example has a shorter semi-curing time (dust-free) under low-temperature conditions than the aqueous epoxy resin compositions of Comparative Examples 2-1 and 2-2, and the pencil hardness, water resistance, and appearance of the coating film are also good. It is also clear that the water resistance of the coating film when cured at low temperatures is better than that of the aqueous epoxy resin compositions of Comparative Examples 2-3 and 2-4.

[0127] According to the present invention, there can be provided an emulsion-type epoxy resin curing agent composition capable of preparing an aqueous epoxy resin composition having good emulsifiability, low-temperature curing properties, and excellent water resistance of the coating film after low-temperature curing, as well as 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 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. Ingredient (B): Nonionic emulsifier having an aromatic ring with an HLB value of 14.0 or higher. Component (C): Co-solvent, 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, comprising the aforementioned component (C) as a cosolvent having a hydroxyl group.

4. 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.

5. 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).

6. 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.

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

10. 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 9 with an epoxy resin emulsion.

11. The aqueous epoxy resin composition according to claim 10, wherein the epoxy resin in the epoxy resin emulsion includes a solid epoxy resin.

12. A method for producing the aqueous epoxy resin composition according to claim 10, 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.