Water-based epoxy resin composition, cured object of water-based epoxy resin composition, and production method for water-based epoxy resin composition

Abstract

This water-based epoxy resin composition comprises an epoxy resin (A), a hardener (B) including a product (b1) of reaction between epichlorohydrin and an amine compound represented by general formula (1), an aromatic hydrocarbon formaldehyde resin (C), and water.　(1): H2N-CH2-A-CH2-NH2 (In formula (1), A represents a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.)

Description

Water-based epoxy resin composition, cured product of the water-based epoxy resin composition, and method for producing the water-based epoxy resin composition

[0001] The present invention relates to an aqueous epoxy resin composition, a cured product of the aqueous epoxy resin composition, and a method for producing the aqueous epoxy resin 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, solvent regulations have been tightened in recent years for environmental and safety reasons, and studies are underway to develop water-based paints. One example of a water-based epoxy resin paint is the use of a water-based epoxy resin emulsified by adding an emulsifier and water to an epoxy resin as the base resin. For example, Patent Document 1 discloses an epoxy curing reagent composition containing an epichlorohydrin-metaxylylenediamine reaction product that is substantially free of metaxylylenediamine and at least one liquid hydroxyl-functional melting point depressant selected from the group consisting of plasticizer alcohols and aqueous alcoholic solvents, with the aim of producing a coating composition with high gloss, a long pot life, and a fast curing time, as well as an aqueous dispersion of an epoxy resin and a coating composition containing the epoxy curing reagent composition.

[0004] Special Publication No. 2001-502378

[0005] The epichlorohydrin-metaxylylenediamine reaction product used in the epoxy curing reagent composition of Patent Document 1 is known to have a fast curing rate but a short pot life when used to cure waterborne epoxy resin compositions. In contrast, Patent Document 1 describes a coating composition in which the epoxy curing reagent composition contains at least one liquid hydroxyl-functional melting point depressant selected from the group consisting of plasticizer alcohols and aqueous alcoholic solvents, thereby achieving a long pot life. However, the coating composition of Patent Document 1 has a problem in terms of environmental impact, as the epoxy curing reagent composition contains the melting point depressant, which increases the content of volatile organic solvents (VOCs).

[0006] According to the investigations of the present inventors, it has been found that a long pot life cannot be achieved simply by reducing the amount of volatile organic solvents (VOCs) in an aqueous epoxy resin composition. An object of the present invention is to provide an aqueous epoxy resin composition having a reduced content of volatile organic solvents (VOCs) and an extended pot life, a cured product of the aqueous epoxy resin composition, and a method for producing the aqueous epoxy resin composition.

[0007] The present inventors have found that an aqueous epoxy resin composition containing an epoxy resin, a curing agent containing a reaction product of epichlorohydrin and a specific amine compound, an aromatic hydrocarbon-formaldehyde resin, and water can solve the above-mentioned problems. The present invention relates to the following items [1] to

[14] . [1] An aqueous epoxy resin composition containing an epoxy resin (A), a curing agent (B) containing a reaction product (b1) of epichlorohydrin and an amine compound represented by the following general formula (1), an aromatic hydrocarbon-formaldehyde resin (C), and water. H ２ N-CH ２ -A-CH ２ -NH ２(1) (In formula (1), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.) [2] The aqueous epoxy resin composition according to [1], wherein the content ratio of the epoxy resin (A) to the curing agent (B) is 1 / 1.1 to 1 / 0.3, expressed as [number of epoxy groups in component (A) / number of active hydrogen atoms in component (B)]. [3] The aqueous epoxy resin composition according to [1] or [2], wherein the reaction product (b1) contains, as a main component, a compound represented by the following general formula (2): (In formula (2), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group; and n is a number from 1 to 12.) [4] The aqueous epoxy resin composition according to any one of [1] to [3], wherein the aromatic hydrocarbon-formaldehyde resin (C) has a number average molecular weight of 100 to 3,000. [5] The aqueous epoxy resin composition according to any one of [1] to [4], wherein the aromatic hydrocarbon-formaldehyde resin (C) has a hydroxyl value of 10 to 300 mgKOH / g. [6] The aqueous epoxy resin composition according to any one of [1] to [5], wherein the content of the aromatic hydrocarbon-formaldehyde resin (C) is 5 to 30 parts by mass per 100 parts by mass of the epoxy resin (A). [7] The aqueous epoxy resin composition according to any one of [1] to [6], further comprising a nonionic surfactant (D). [8] The aqueous epoxy resin composition according to [7], wherein the nonionic surfactant (D) is at least one selected from the group consisting of polyether surfactants and ester surfactants. [9] The aqueous epoxy resin composition according to any one of [1] to [8], wherein the total content of the epoxy resin (A) and the curing agent (B) is 50 mass% or more.

[10] A cured product of the aqueous epoxy resin composition according to any one of [1] to [9].

[11] A method for producing an aqueous epoxy resin composition containing an epoxy resin (A), a curing agent (B) containing a reaction product (b1) of epichlorohydrin and an amine compound represented by the following general formula (1), an aromatic hydrocarbon-formaldehyde resin (C), and water, the method comprising the step of mixing the epoxy resin (A), the curing agent (B), and an aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C).２ N-CH ２ -A-CH ２ -NH ２ (1) (In formula (1), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.)

[12] The method for producing an aqueous epoxy resin composition according to

[11] , wherein the reaction product (b1) contains a compound represented by the following general formula (2) as a main component: (In formula (2), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group, and n is a number from 1 to 12.)

[13] The method for producing an aqueous epoxy resin composition according to

[11] or

[12] , wherein the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) further contains a nonionic surfactant (D).

[14] The method for producing an aqueous epoxy resin composition according to

[13] , wherein the content of the nonionic surfactant (D) in the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) is 1.5 parts by mass or more and 15.0 parts by mass or less per 100 parts by mass of the aromatic hydrocarbon-formaldehyde resin (C).

[0008] According to the present invention, it is possible to provide an aqueous epoxy resin composition having a reduced content of volatile organic solvents (VOCs) and an extended pot life, a cured product of the aqueous epoxy resin composition, and a method for producing the aqueous epoxy resin composition.

[0009] [Waterborne Epoxy Resin Composition] The waterborne epoxy resin composition of the present invention (hereinafter also referred to as "the composition of the present invention") contains an epoxy resin (A), a curing agent (B) (hereinafter also referred to as "curing agent (B)") containing a reaction product (b1) of epichlorohydrin and an amine compound represented by the following general formula (1), an aromatic hydrocarbon formaldehyde resin (C), and water. ２ N-CH ２ -A-CH ２ -NH ２ (1) (In formula (1), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.)

[0010] Conventionally, a combination of an epoxy resin and a curing agent containing a reaction product of an amine compound has a relatively fast curing rate, but on the other hand, it has a short pot life and poor handleability. Attempts have been made to incorporate components containing a large amount of organic solvent in order to improve the pot life, but in this case, the content of volatile organic solvents (VOCs) has increased, which may result in a large environmental load. The composition of the present invention further contains an aromatic hydrocarbon formaldehyde resin (C) in addition to the epoxy resin (A) and the curing agent (B), thereby reducing the content of volatile organic solvents (VOCs) and extending the pot life. Therefore, the composition of the present invention reduces the environmental load while improving handleability when forming a coating film, etc.

[0011] <Epoxy Resin (A)> The epoxy resin (A) is not particularly limited as long as it has two or more glycidyl groups capable of reacting with active hydrogen in the curing agent (B) described below and can be emulsified and dispersed in water, and may be any of a saturated or unsaturated aliphatic compound, an alicyclic compound, an aromatic compound, and a heterocyclic compound. From the viewpoint of improving the appearance and strength of the obtained cured product, the epoxy resin (A) is preferably an epoxy resin containing an aromatic ring or an alicyclic structure in the molecule.

[0012] Specific examples of the epoxy resin (A) include at least one resin 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 phenol novolac, and epoxy resins having a glycidyloxy group derived from resorcinol. Two or more of the above epoxy resins can also be used in combination.

[0013] Among the above, from the viewpoint of improving the appearance and strength of the obtained cured product, the epoxy resin (A) is more preferably one having as the main component 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, even more preferably one having as the main component 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 one having as the main component an epoxy resin having a glycidyloxy group derived from bisphenol A. Here, the term "main component" means that other components may be contained within a range that does not deviate from the spirit of the present invention, and preferably means 50 to 100 mass%, more preferably 70 to 100 mass%, and even more preferably 90 to 100 mass% of the total.

[0014] The epoxy equivalent of the epoxy resin (A) is preferably 100 g / equivalent or more, more preferably 150 g / equivalent or more, and even more preferably 300 g / equivalent or more, from the viewpoint of improving the appearance and strength of the obtained cured product, and is preferably 1000 g / equivalent or less, more preferably 800 g / equivalent or less, and even more preferably 600 g / equivalent or less, from the viewpoint of low viscosity and curability of the aqueous epoxy resin composition.

[0015] From the viewpoints of curability and extension of pot life, and of improving the appearance and strength of the obtained cured product, the content of the epoxy resin (A) is preferably from 50% by mass to 99% by mass, more preferably from 60% by mass to 98% by mass, and even more preferably from 70% by mass to 95% by mass, of the solid content of the composition of the present invention.

[0016] <Curing Agent (B)> The composition of the present invention contains a curing agent (B) containing a reaction product (b1) of epichlorohydrin and an amine compound represented by the following general formula (1): H ２ N-CH ２ -A-CH ２ -NH ２(1) (In formula (1), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.)

[0017] (Reaction Product (b1)) The reaction product (b1) is a reaction product of epichlorohydrin and an amine compound represented by the general formula (1). In the general formula (1), A is preferably a 1,3-phenylene group or a 1,4-phenylene group, and more preferably a 1,3-phenylene group. That is, the amine compound represented by the general formula (1) is at least one selected from the group consisting of orthoxylylenediamine, metaxylylenediamine (MXDA), and paraxylylenediamine (PXDA), preferably one or more selected from the group consisting of metaxylylenediamine and paraxylylenediamine, and more preferably metaxylylenediamine.

[0018] The reaction product (b1) preferably contains a compound represented by the following general formula (2) as a main component: The "main component" here refers to a component whose content is 50% by mass or more when the total amount of all components in the reaction product (b1) is taken as 100% by mass. (In formula (2), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group; and n is a number from 1 to 12.)

[0019] The content of the compound represented by general formula (2) in the reaction product (b1) is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 72% by mass or more, from the viewpoints of curability and pot life extension. The upper limit is 100% by mass. Furthermore, from the viewpoint of obtaining good curing performance as a curing agent, it is preferable that the proportion of the compound represented by general formula (2) where n = 1 is high. The content of the compound represented by general formula (2) where n = 1 in the reaction product (b1) is preferably 15% by mass or more, more preferably 18% by mass or more, and even more preferably 20% by mass or more. The content of the compound represented by general formula (2) in the reaction product (b1) and the composition of the compound represented by general formula (2) can be determined by gas chromatography (GC) analysis and gel permeation chromatography (GPC) analysis.

[0020] From the viewpoint of curability and pot life extension, the active hydrogen equivalent weight (AHEW) of the reaction product (b1) is preferably from 40 to 100, more preferably from 45 to 90, and even more preferably from 50 to 80. The AHEW of the reaction product (b1) can be determined by titration.

[0021] Furthermore, the proportion of the amine compound represented by general formula (1) relative to the total amount of the compound represented by general formula (2) and the amine compound represented by general formula (1) in reaction product (b1) is preferably 20% by mass or more and 35% by mass or less, more preferably 24% by mass or more and 28% by mass or less. When the content of the amine compound represented by general formula (1) (i.e., raw material diamine) in reaction product (b1) is 20% by mass or more, it is easy to reduce the viscosity of the aqueous epoxy resin composition and workability is further improved, and when it is 35% by mass or less, the appearance and strength of the obtained cured product are further improved.

[0022] The reaction product (b1) is obtained by reacting epichlorohydrin with a diamine represented by the general formula (1) (hereinafter also referred to as the "starting diamine"). The reaction between epichlorohydrin and the starting diamine can be carried out by a known method, and the method is not particularly limited. However, from the viewpoint of reaction efficiency, it is preferably carried out in the presence of a basic catalyst. The basic catalyst is preferably an alkali metal hydroxide, more preferably one or more selected from the group consisting of potassium hydroxide and sodium hydroxide, and even more preferably sodium hydroxide. The alkali metal hydroxide may be used in a solid state or in the form of an aqueous solution, but is more preferably used in the form of an aqueous solution. The concentration of the alkali metal hydroxide aqueous solution is preferably in the range of 30 to 55% by mass.

[0023] In the reaction of epichlorohydrin with the starting diamine, the amount of the basic catalyst used is preferably about equimolar to the amount of epichlorohydrin, and is preferably 0.7 to 2.0 mol, more preferably 0.8 to 1.5 mol, and even more preferably 0.9 to 1.2 mol per mol of epichlorohydrin used.

[0024] The amounts of epichlorohydrin and starting diamine used are preferably in the range of 1.5 to 12 moles, more preferably 1.5 to 6.0 moles, and even more preferably 1.8 to 3.0 moles, such that the molar ratio of starting diamine to 1 mole of epichlorohydrin is in the range of 1.5 to 12 moles, more preferably 1.5 to 6.0 moles, and even more preferably 1.8 to 3.0 moles, from the viewpoint of obtaining the compound represented by the general formula (2) in which n = 1 with high selectivity.

[0025] The reaction between epichlorohydrin and the starting diamine is preferably carried out by first mixing the starting diamine with a basic catalyst and then adding the epichlorohydrin to carry out the reaction. For example, the starting diamine and basic catalyst are charged into a reactor, heated with stirring under an inert atmosphere such as nitrogen gas, and then epichlorohydrin is added to carry out the reaction. The method for adding epichlorohydrin is not particularly limited, but examples include adding epichlorohydrin to the reactor using a dropping funnel or a liquid pump. The temperature during the addition of epichlorohydrin is preferably 40 to 100°C, more preferably 50 to 80°C. After the addition of epichlorohydrin is complete, the reaction temperature may be increased to improve reaction efficiency; the reaction temperature is preferably 55 to 120°C. A reaction temperature of 55°C or higher allows the addition reaction between epichlorohydrin and the starting diamine to proceed efficiently. The reaction time is not particularly limited, and is usually preferably 10 minutes to 6 hours, more preferably 20 minutes to 4 hours, from the end of the addition of epichlorohydrin. If the reaction time is 10 minutes or more, the amount of unreacted raw materials remaining is small, and if it is 6 hours or less, it is advantageous in terms of productivity.

[0026] After the reaction is complete, the resulting reaction solution contains an addition reaction product of epichlorohydrin and the starting diamine, unreacted starting diamine, the basic catalyst, and water and salts produced by the reaction. For example, when an alkali metal hydroxide is used as the basic catalyst, an alkali metal chloride is produced as the salt. Depending on the type of basic catalyst, the catalyst can be removed by filtration, washing with water, adsorption, or the like. The water produced by the reaction can be removed under reduced pressure at a temperature of 100°C or less, for example. The salts produced by the reaction can be removed by filtration, for example.

[0027] The basic catalyst, water, and salts are removed from the reaction mixture as described above to obtain the reaction product (b1). If necessary, furthermore, an operation for removing unreacted starting diamine may be carried out.

[0028] The curing agent (B) may further contain other curing agent components in addition to the reaction product (b1). Examples of such "other curing agent components" include polyamine compounds other than the reaction product (b1) and the raw material diamine, or modified products thereof. Furthermore, the curing agent (B) may further contain known curing accelerators, non-reactive diluents, and the like, as long as the effects of the present invention are not impaired. Examples of curing accelerators include tris(dimethylaminomethyl)phenol, benzyl alcohol, salicylic acid, triphenyl phosphite, styrenated phenol, bisphenol A, N,N'-bis(3-(dimethylamino)propyl)urea, and mercaptan-terminated polysulfide compounds such as "Thiokol LP-3" (manufactured by Toray Fine Chemicals Co., Ltd.). However, from the viewpoint of achieving the effects of the present invention, the content of the reaction product (b1) contained in the curing agent (B) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total amount of the curing agent components. The upper limit is 100% by mass.

[0029] The content ratio of the epoxy resin (A) to the curing agent (B) in the aqueous epoxy resin composition of the present invention, expressed as [number of epoxy groups in component (A) / number of active hydrogen atoms in component (B)], is preferably 1 / 1.1 to 1 / 0.3, more preferably 1 / 0.8 to 1 / 0.4, and even more preferably 1 / 0.7 to 1 / 0.5. When the content ratio is in the range of 1 / 1.1 to 1 / 0.3, the appearance and strength of the resulting cured product are further improved.

[0030] Furthermore, from the viewpoints of curability and extension of pot life, and of improving the appearance and strength of the obtained cured product, the content of the curing agent (B) in the composition of the present invention is preferably from 2 to 15% by mass, more preferably from 3 to 12% by mass, and even more preferably from 4 to 10% by mass.

[0031] Furthermore, from the viewpoints of curability and extension of pot life, and of improving the appearance and strength of the obtained cured product, the total content of the epoxy resin (A) and the curing agent (B) is preferably 50% by mass or more, more preferably 50% by mass or more and 99% by mass or less, even more preferably 60% by mass or more and 98% by mass or less, and still more preferably 70% by mass or more and 95% by mass or less, of the solid content of the composition of the present invention.

[0032] <Aromatic hydrocarbon formaldehyde resin (C)> In the resin composition of this embodiment, the aromatic hydrocarbon formaldehyde resin (C) may be an unmodified aromatic hydrocarbon formaldehyde resin, or may be a modified aromatic hydrocarbon formaldehyde resin modified with various compounds. That is, the aromatic hydrocarbon formaldehyde resin (C) is preferably one or more selected from unmodified aromatic hydrocarbon formaldehyde resins and modified aromatic hydrocarbon formaldehyde resins. The aromatic hydrocarbon formaldehyde resin (C) may be one or more of the unmodified aromatic hydrocarbon formaldehyde resins and modified aromatic hydrocarbon formaldehyde resins described below, either singly or in combination.

[0033] (Unmodified aromatic hydrocarbon formaldehyde resin) The unmodified aromatic hydrocarbon formaldehyde resin is obtained by reacting an aromatic hydrocarbon with formaldehyde. Examples of the aromatic hydrocarbon include at least one selected from the group consisting of benzene, toluene, xylene, mesitylene, ethylbenzene, propylbenzene, decylbenzene, cyclohexylbenzene, pseudocumene (1,2,4-trimethylbenzene), biphenyl, methylbiphenyl, naphthalene, methylnaphthalene, dimethylnaphthalene, ethylnaphthalene, anthracene, methylanthracene, dimethylanthracene, ethylanthracene, and binaphthyl. Among these, from the viewpoints of curability and pot life extension, the aromatic hydrocarbon is preferably at least one selected from the group consisting of xylene, toluene, mesitylene, and pseudocumene, and more preferably xylene. Examples of formaldehyde that can be used include industrially available formalin and paraformaldehyde, as well as formaldehyde-generating compounds such as trioxane.

[0034] From the viewpoints of curability and an extended pot life, the unmodified aromatic hydrocarbon formaldehyde resin preferably contains at least one resin selected from the group consisting of a xylene formaldehyde resin obtained by reacting xylene with formaldehyde, a toluene formaldehyde resin obtained by reacting toluene 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 contains a xylene formaldehyde resin.

[0035] The unmodified aromatic hydrocarbon-formaldehyde resin may be a commercially available product, or may be prepared by a known method. Examples of commercially available products include "Nikanol H," "Nikanol LLL," and "Nikanol Y-100" manufactured by Fudow Co., Ltd. Known methods include, for example, 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.

[0036] (Modified aromatic hydrocarbon formaldehyde resin) The modified aromatic hydrocarbon formaldehyde resin can be obtained by reacting the unmodified aromatic hydrocarbon formaldehyde resin with various compounds. The compound used for modification is preferably one or more selected from phenols, alcohols, and carboxylic acids, and is preferably a phenol. That is, in the resin composition of this embodiment, the modified aromatic hydrocarbon formaldehyde resin is preferably one or more selected from phenol-modified aromatic hydrocarbon formaldehyde resins, alcohol-modified aromatic hydrocarbon formaldehyde resins, and carboxylic acid-modified aromatic hydrocarbon formaldehyde resins, and is more preferably a phenol-modified aromatic hydrocarbon formaldehyde resin. By using a modified aromatic hydrocarbon formaldehyde resin, the hydroxyl value of the aromatic hydrocarbon formaldehyde resin (C) can be relatively increased, thereby maintaining curability and further extending the pot life.

[0037] Phenol-modified aromatic hydrocarbon formaldehyde resins are obtained by reacting unmodified aromatic hydrocarbon formaldehyde resins with phenols in the presence of an acid catalyst. Examples of phenols that can be used include monohydric phenols such as phenol, cresol, butylphenol, nonylphenol, t-butylphenol, and naphthol; dihydric phenols such as catechol, resorcinol, hydroquinone, and bisphenol; and trihydric phenols such as pyroganol and phloroglucinol. Among these, monohydric phenols are preferred, t-butylphenol is more preferred, and p-t-butylphenol is even more preferred.

[0038] Alcohol-modified aromatic hydrocarbon-formaldehyde resins are obtained by reacting unmodified aromatic hydrocarbon-formaldehyde resins with alcohols using an acid catalyst. Examples of alcohols that can be used include lower alcohols such as methanol, ethanol, butanol, 1-propanol, and 2-propanol; higher alcohols such as 1-octanol, 1-dodecanol, and benzyl alcohol; aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, diethylene glycol, and triethylene glycol; aliphatic cyclic diols such as 1,4-cyclohexanedimethanol; and polyols having three or more hydroxyl groups such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0039] Carboxylic acid-modified aromatic hydrocarbon-formaldehyde resins are obtained by reacting unmodified aromatic hydrocarbon-formaldehyde resins with carboxylic acids in the presence of an acid catalyst. Examples of carboxylic acids that can be used include saturated aliphatic acids such as formic acid, acetic acid, propionic acid, lauric acid, succinic acid, and succinic anhydride; aromatic carboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, and terephthalic acid; unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, fumaric acid, maleic acid, and maleic anhydride; and hydroxy acids such as lactic acid, malic acid, and citric acid.

[0040] Of the above, the modified aromatic hydrocarbon formaldehyde resin is preferably a phenol-modified aromatic hydrocarbon formaldehyde resin, more preferably a t-butylphenol-modified aromatic hydrocarbon formaldehyde resin obtained by reacting t-butylphenol with an unmodified aromatic hydrocarbon formaldehyde resin, even more preferably a t-butylphenol-modified xylene formaldehyde resin obtained by reacting t-butylphenol with a xylene formaldehyde resin, and even more preferably a p-t-butylphenol-xylene formaldehyde resin.

[0041] The modified aromatic hydrocarbon formaldehyde resin may be a commercially available product or may be prepared by a known method, such as "Nikanol HP-70," "Nikanol HP-120," "Nikanol K-100," or "Nikanol L-5," manufactured by Fudow Co., Ltd.

[0042] The number average molecular weight of the aromatic hydrocarbon formaldehyde resin (C) is preferably 100 to 3,000, more preferably 150 to 1,500, even more preferably 200 to 1,000, and even more preferably 250 to 500, from the viewpoints of curability and handleability.

[0043] The hydroxyl value of the aromatic hydrocarbon formaldehyde resin (C) is preferably 10 to 300 mgKOH / g, more preferably 12 to 200 mgKOH / g, even more preferably 16 to 120 mgKOH / g, and even more preferably 20 to 50 mgKOH / g. When the hydroxyl value is 10 mgKOH / g or more, the curability of the composition of the present invention is further improved. Furthermore, when the hydroxyl value is 300 mgKOH / g or less, the pot life of the composition of the present invention is further extended.

[0044]

[0044] From the viewpoints of curability and pot life extension, and of reducing the content of volatile organic solvents (VOCs) in the composition, the content of the aromatic hydrocarbon formaldehyde resin (C) in the aqueous epoxy resin composition is preferably from 3 to 30% by mass, more preferably from 5 to 25% by mass, and even more preferably from 7 to 20% by mass, of the solid content of the composition of the present invention.

[0045]

[0044] The content of the aromatic hydrocarbon formaldehyde resin (C) in the aqueous epoxy resin composition is preferably from 5 to 30 parts by mass, more preferably from 7 to 27 parts by mass, and even more preferably from 10 to 25 parts by mass, per 100 parts by mass of the epoxy resin (A), from the viewpoints of curability and extension of pot life, and of reducing the content of volatile organic solvents (VOCs) in the composition.

[0046] It is difficult to identify the structure of the unmodified aromatic hydrocarbon formaldehyde resin of the present embodiment by analysis.Similarly, it is also difficult to identify the structure of a modified aromatic hydrocarbon formaldehyde resin made from an unmodified aromatic hydrocarbon formaldehyde resin.

[0047] <Nonionic surfactant (D)> The composition of the present invention preferably further contains a nonionic surfactant (D). By containing the nonionic surfactant (D), the composition of the present invention can be maintained in a stable state regardless of changes in properties such as pH, and therefore the pot life is further extended.

[0048] As the nonionic surfactant (D), any known surfactant can be used. However, from the viewpoint of improving the mixability with the hydrophilic resin, one or more surfactants selected from polyether surfactants and ester surfactants are preferred, and polyether surfactants are more preferred.

[0049] Specific examples of polyether surfactants include the following (1) to (5): (1) polyoxyalkyl ethers such as polyoxyethylene stearyl ether and polyoxyethylene lauryl ether; (2) polyoxyethylene alkenyl ethers such as polyoxyethylene oleyl ether; (3) polyoxyethylene alkyl phenyl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene styrylphenyl ether and α-[5-methyl-2,3-bis(2-phenylethyl)phenyl]-ω-hydroxypoly(oxy-1,2-ethanediyl); (4) polyoxyethylene-polyoxypropylene block copolymer; and (5) reaction products of ethyl oxide and propyl oxide with compounds containing terminal isocyanate groups, such as 1,3-diisocyanato(methyl)benzene-2-methyloxirane-oxirane polymers. Among these, from the viewpoint of improving the mixability with the hydrophilic resin, the polyether surfactant preferably contains one or more selected from polyoxyalkyl ether, polyoxyethylene alkylphenyl ether, and reaction products of ethyl oxide and propyl oxide with a compound containing a terminal isocyanate group, and more preferably contains one or more selected from polyoxyethylene stearyl ether, α-[5-methyl-2,3-bis(2-phenylethyl)phenyl]-ω-hydroxypoly(oxy-1,2-ethanediyl), and 1,3-diisocyanato(methyl)benzene-2-methyloxirane-oxirane polymer.

[0050] Examples of ester surfactants include the following (6) to (9): (6) sorbitan higher fatty acid esters such as sorbitan monolaurate and sorbitan trioleate; (7) polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; (8) polyoxyethylene higher fatty acid esters such as polyoxyethylene monolaurate and polyoxyethylene monooleate; and (9) glycerin higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride.

[0051] Commercially available nonionic surfactants (D) include, for example, "Softlon PE-35" (1,3-diisocyanato(methyl)benzene-2-methyloxirane-oxirane polymer) manufactured by Yoshimura Oil Chemical Co., Ltd.; "Brawnon SR-705" (polyoxyethylene stearyl ether), "Brawnon SR-720" (polyoxyethylene stearyl ether), "Brawnon SR-730" (polyoxyethylene stearyl ether), and "YKA-7200" (polyoxyethylene stearyl ether) manufactured by Aoki Oil & Fats Industries Co., Ltd.; and "Newcol 707" (α-[5-methyl-2,3-bis(2-phenylethyl)phenyl]-ω-hydroxypoly(oxy-1,2-ethanediyl)) manufactured by Nippon Nyukazai Co., Ltd.

[0052] In the present invention, the nonionic surfactant (D) may be any one of the above surfactants or a combination of two or more of them.

[0053] From the viewpoints of curability and pot life extension, and of reducing the content of volatile organic solvents (VOCs) in the composition, the content of the nonionic surfactant (D) in the composition of the present invention is preferably from 0.05% by mass to 5.0% by mass, more preferably from 0.1% by mass to 3.0% by mass, even more preferably from 0.15% by mass to 1.0% by mass, and still more preferably from 0.2% by mass to 0.5% by mass.

[0054] In the composition of the present invention, the content of the nonionic surfactant (D) derived from the nonionic surfactant (D) contained in the aqueous dispersion of the aromatic hydrocarbon formaldehyde resin (C) described below is preferably from 0.05 to 1.5% by mass, more preferably from 0.1 to 1.0% by mass, and even more preferably from 0.15 to 0.5% by mass. In the composition of the present invention, when the aqueous dispersion of the epoxy resin (A) described below is used in the production, the content of the nonionic surfactant (D) derived from the aqueous dispersion of the epoxy resin (A) is preferably from 0.05 to 3.5% by mass, more preferably from 0.1 to 3.0% by mass, and even more preferably from 0.15 to 2.5% by mass.

[0055]

[0044] From the viewpoints of curability and pot life extension, and of reducing the content of volatile organic solvents (VOCs) in the composition, the content of the nonionic surfactant (D) is preferably from 0.1 to 10.0% by mass, more preferably from 0.2 to 5.0% by mass, more preferably from 0.3 to 2.0% by mass, and even more preferably from 0.5 to 1.0% by mass, relative to 100 parts by mass of the epoxy resin (A).

[0056] In the composition of the present invention, the content of the nonionic surfactant (D) derived from the nonionic surfactant (D) contained in the aqueous dispersion of the aromatic hydrocarbon formaldehyde resin (C) described below is preferably 0.1 to 3.0 parts by mass, more preferably 0.2 to 2.0 parts by mass, and even more preferably 0.3 to 1.0 parts by mass, per 100 parts by mass of the epoxy resin (A). In addition, when the aqueous dispersion of the epoxy resin (A) described below is used in the production of the composition of the present invention, the content of the nonionic surfactant (D) derived from the aqueous dispersion of the epoxy resin (A) is preferably 0.1 to 8.0 parts by mass, more preferably 0.2 to 6.0 parts by mass, and even more preferably 0.3 to 4.0 parts by mass, per 100 parts by mass of the epoxy resin (A).

[0057] (Other Surfactants) The composition of the present invention may contain other surfactants other than the nonionic surfactant (D) described above, as long as the properties of this embodiment are not impaired. Examples of other surfactants include cationic surfactants and anionic surfactants. In the composition of the present invention, from the viewpoint of the storage stability of the composition of the present invention and from the viewpoint of suppressing the occurrence of aggregation and the like in the obtained aqueous epoxy resin composition and ensuring sufficient mixing, it is preferable that the content of other surfactants in the aromatic hydrocarbon-formaldehyde resin composition be as small as possible, more preferably 1.0% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0% by mass.

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

[0059] (Co-solvent) When the composition of the present invention has a high viscosity during heat-melt mixing, making emulsion phase inversion difficult, or when the film-forming properties during drying and curing are poor, a co-solvent may be added as needed along with water as a solvent. The co-solvent is not particularly limited as long as it dissolves the above components (A) to (D). Preferably, it is one or more selected from glycol ethers, alcohols, ketones, acetates, and aromatic hydrocarbons, more preferably acetate, and even more preferably propylene glycol monomethyl ether acetate. The above-mentioned co-solvents may be used alone or in combination of two or more. From the viewpoint of reducing the content of volatile organic solvents (VOCs), the content of the co-solvent in the composition of the present invention is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, and even more preferably 0% by mass.

[0060] The content of water in the composition of the present invention is preferably 40% by mass or more and 60% by mass or less, more preferably 45% by mass or more and 55% by mass or less. When a co-solvent is contained, the total content of water and the co-solvent in the composition of the present invention is preferably 40% by mass or more and 60% by mass or less, more preferably 45% by mass or more and 55% by mass or less.

[0061] <Other Components> The composition of the present invention may contain additives such as an antifoaming agent, an antiseptic, a dispersion stabilizer, a pH adjuster, a leveling agent, a tackifier, a silane coupling agent, a rust inhibitor, a lubricant, a curing catalyst, a water absorbent, a moisture absorbent, and a hydrolysis inhibitor, as needed, within the range that does not impair the properties of this embodiment.

[0062] <Uses> The composition of the present invention has a reduced content of volatile organic solvents (VOCs) and an extended pot life, and therefore reduces the environmental impact and is easy to handle, and is therefore suitable for use in various paints such as anticorrosion paints, adhesives, flooring materials, sealants, polymer cement mortars, gas barrier coatings, primers, screeds, top coats, sealants, crack repair materials, concrete materials, etc. Anticorrosion paints are used, for example, for painting buildings such as ships, bridges, and factories, as well as other iron structures on land and at sea.

[0063] [Cured Product of Waterborne Epoxy Resin Composition] The cured product of the waterborne epoxy resin composition of the present invention (hereinafter also simply referred to as "the cured product of the present invention") is obtained by curing the above-mentioned waterborne epoxy resin composition of the present invention by a known method. The curing conditions for the waterborne epoxy resin composition are appropriately selected depending on the application and form, and are not particularly limited. The form of the cured product of the present invention is not particularly limited, and can be selected depending on the application. For example, when the waterborne epoxy resin composition is an anticorrosion paint, the cured product of the waterborne epoxy resin composition is usually a film-like cured product.

[0064] [Method for producing aqueous epoxy resin composition] The method for producing an aqueous epoxy resin composition of the present invention (hereinafter also referred to as "the production method of the present invention") is a method for producing an aqueous epoxy resin composition containing an epoxy resin (A), a curing agent (B) containing a reaction product (b1) of epichlorohydrin and an amine compound represented by the following general formula (1), an aromatic hydrocarbon-formaldehyde resin (C), and water, and includes a step of mixing the epoxy resin (A), the curing agent (B), and an aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C). ２ N-CH ２ -A-CH ２ -NH ２ (1) (In formula (1), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.) The mixing method in the mixing step may be a method using a known method and device.

[0065] <Epoxy Resin (A)> Preferred examples of the epoxy resin (A) include the same epoxy resin (A) as in the composition of the present invention. In the production method of the present invention, the epoxy resin (A) may be mixed as is, or an aqueous dispersion of the epoxy resin (A) may be mixed. Among these, in the production method of the present invention, from the viewpoint of the miscibility of the respective components and the extension of the pot life of the resulting aqueous epoxy resin composition, it is preferable to mix an aqueous dispersion of the epoxy resin (A), and it is more preferable to mix an epoxy resin emulsion.

[0066] The epoxy resin emulsion may be, for example, one in which the epoxy resin (A) is emulsified and dispersed in water, and is preferably an epoxy resin emulsion containing the epoxy resin (A), a surfactant, and water.

[0067] The concentration of the epoxy resin (A) in the epoxy resin emulsion is not particularly limited, but from the viewpoint of setting the viscosity of the resulting aqueous epoxy resin composition in a handleable range and from the viewpoint of the stability of the epoxy resin emulsion, it is preferably 30% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 70% by mass or less.

[0068] The surfactant used in the epoxy resin emulsion may be any of nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric emulsifiers, and reactive group-containing surfactants. Among these, nonionic surfactants are preferred from the viewpoints of extending the pot life and productivity of the resulting aqueous epoxy resin composition. Preferred examples of nonionic surfactants include those similar to the nonionic surfactant (D) in the composition of the present invention described above. One surfactant may be used alone, or two or more surfactants may be used in combination.

[0069] The content of the surfactant in the epoxy resin emulsion is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 30 parts by mass, and even more preferably 1 to 20 parts by mass, per 100 parts by mass of the epoxy resin (A). When the content of the surfactant is 0.1 part by mass or more per 100 parts by mass of the epoxy resin (A), the emulsion stability of the epoxy resin (A) is good, and when the content is 40 parts by mass or less, the pot life of the resulting aqueous epoxy resin composition is further extended, and the appearance and strength are likely to be further improved.

[0070] The epoxy resin emulsion may contain components other than the epoxy resin (A), surfactant, and water. The total content of the epoxy resin, surfactant, and water is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, with the upper limit being 100% by mass. Examples of components other than the epoxy resin (A), surfactant, and water include aqueous solvents. Examples of such aqueous solvents include protic polar solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and 1-propoxy-2-propanol; and aprotic polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone. These solvents may be used alone or in combination of two or more. Among these, protic polar solvents are preferred from the viewpoint of improving workability.

[0071] Commercially available epoxy resin emulsions that can be used in the production method of the present invention include jER series emulsions "W2801," "W2821R70," "W3435R67," "W8735R70," "W1155R55," and "W5654R45" manufactured by Mitsubishi Chemical Corporation, "EM-101-50" manufactured by ADEKA Corporation, "EPICLON EXA-8610" manufactured by DIC Corporation, Araldite series emulsions "PZ 3901," "PZ 3921," and "PZ 3961-1" manufactured by Huntsman Advanced Materials, "DER 915" and "DER917" manufactured by Olin, and EPIREZ series emulsions "Resin 3520-WY-55" and "Resin 3520-WY-55" manufactured by Hexion. Examples of commercially available products include "6520-WH-53".

[0072] <Curing Agent (B)> The curing agent (B) is preferably the same as the curing agent (B) in the composition of the present invention. In the production method of the present invention, the reaction product (b1) preferably contains a compound represented by the general formula (2) as a main component.

[0073] The curing agent (B) may contain a solvent from the viewpoint of improving the productivity of the resulting aqueous epoxy resin composition. Examples of the solvent include water or an aqueous solvent, with water being preferred from the viewpoints of the environment and safety. When the curing agent (B) contains water, the content of water in the curing agent (B) is preferably 1 to 80% by mass, more preferably 15 to 70% by mass, and even more preferably 30 to 60% by mass, from the viewpoint of improving the productivity of the resulting aqueous epoxy resin composition.

[0074] <Aromatic Hydrocarbon Formaldehyde Resin (C)> In the production method of the present invention, the aromatic hydrocarbon formaldehyde resin (C) is mixed as an aqueous dispersion of the aromatic hydrocarbon formaldehyde resin (C). By mixing the aromatic hydrocarbon formaldehyde resin (C) as an aqueous dispersion, the aromatic hydrocarbon formaldehyde resin (C) can be dispersed as particles in the resulting aqueous epoxy resin composition, which is thought to appropriately slow the reaction between the epoxy resin (A) and the curing agent (B) in the composition and extend the pot life. Furthermore, because the aromatic hydrocarbon formaldehyde resin (C) is dispersed as particles, it does not inhibit the reaction between the epoxy resin (A) and the curing agent (B) after application to form a cured product such as a coating film, which is thought to reduce the impact on curability. Furthermore, by mixing the aromatic hydrocarbon formaldehyde resin (C) as an aqueous dispersion, the amount of volatile organic solvents (VOCs) used can be reduced, further reducing the environmental impact.

[0075] Preferred examples of the aromatic hydrocarbon formaldehyde resin (C) include the same as the aromatic hydrocarbon formaldehyde resin (C) in the composition of the present invention described above.

[0076]

[0044] In the production method of the present invention, the content of the aromatic hydrocarbon formaldehyde resin (C) in the aqueous dispersion of the aromatic hydrocarbon formaldehyde resin (C) is preferably from 15.0% by mass to 65.0% by mass, more preferably from 20.0% by mass to 62.0% by mass, and even more preferably from 25.0% by mass to 60.0% by mass, from the viewpoint of extending the pot life of the resulting aqueous epoxy resin composition.

[0077] In the production method of the present invention, the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) preferably further contains a nonionic surfactant (D). Preferred examples of the nonionic surfactant (D) include the same nonionic surfactants as those in the composition of the present invention.

[0078] In the production method of the present invention, the inclusion of a nonionic surfactant (D) in the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) is believed to enable the resulting aqueous epoxy resin composition to remain stable regardless of changes in properties such as pH, compared to when an ionic surfactant such as a cationic surfactant or anionic surfactant is used. Furthermore, the use of a nonionic surfactant (D) is believed to prevent aggregation of the resulting aqueous epoxy resin composition when it is mixed with the epoxy resin (A) and curing agent (B), thereby enabling thorough mixing. Therefore, the inclusion of a nonionic surfactant (D) in the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) enhances the effects of the aromatic hydrocarbon-formaldehyde resin (C), further reducing the content of volatile organic solvents (VOCs) in the resulting aqueous epoxy resin composition and extending its pot life.

[0079]

[0044] In the production method of the present invention, the content of the nonionic surfactant (D) in the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) is preferably 1.5 parts by mass or more and 15.0 parts by mass or less, more preferably 2.0 parts by mass or more and 10.0 parts by mass or less, and even more preferably 2.5 parts by mass or more and 5.0 parts by mass or less, per 100 parts by mass of the aromatic hydrocarbon-formaldehyde resin (C), from the viewpoint of extending the pot life of the resulting aqueous epoxy resin composition.

[0080]

[0044] In the production method of the present invention, the content of the nonionic surfactant (D) in the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) is preferably from 0.1% by mass to 10.0% by mass, more preferably from 0.5% by mass to 5.0% by mass, and even more preferably from 1.0% by mass to 3.0% by mass, from the viewpoint of extending the pot life of the resulting aqueous epoxy resin composition.

[0081] In the production method of the present invention, the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) may contain other surfactants besides the nonionic surfactant (D) as long as the properties of the present invention are not impaired. Examples of other surfactants include cationic surfactants and anionic surfactants. In the resin composition of this embodiment, the content of other surfactants in the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) is preferably as low as possible, more preferably 1.0% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0% by mass, from the viewpoints of suppressing aggregation and the like of the resulting aqueous epoxy resin composition and extending the pot life.

[0082] (Method for Producing Aqueous Dispersion of Aromatic Hydrocarbon-Formaldehyde Resin (C)) Conventionally known methods such as phase inversion emulsification and high-pressure emulsification can be used to produce an aqueous dispersion of aromatic hydrocarbon-formaldehyde resin (C). When aromatic hydrocarbon-formaldehyde resin (C) is a solid resin, the aromatic hydrocarbon-formaldehyde resin composition can be produced by the following methods (i) to (iii): (i) A method in which aromatic hydrocarbon-formaldehyde resin (C) is heated to a liquid state, and then a nonionic surfactant (D) and water are added. (ii) A method in which aromatic hydrocarbon-formaldehyde resin (C) is dissolved in a solvent in which aromatic hydrocarbon-formaldehyde resin (A) is soluble or in water, and then a nonionic surfactant (D) and water are added to perform phase inversion emulsification. (iii) A method in which the aromatic hydrocarbon-formaldehyde resin (A) is dissolved in a small amount of a solvent or water in which the aromatic hydrocarbon-formaldehyde resin (A) is soluble, and then the nonionic surfactant (D) is kneaded into the solution, and hot water is further added to carry out phase inversion emulsification. In the above (i) to (iii), if excess solvent or water is present after phase inversion emulsification, the solvent or water can be removed under reduced pressure.

[0083] In the above (i) to (iii), the water used is preferably the same as the water in the composition of the present invention. Furthermore, when water is used in the above (i) to (iii), a co-solvent may be used together with water as a solvent, if necessary. The co-solvent is preferably the same as the co-solvent in the composition of the present invention.

[0084] The solid content (non-volatile content) concentration of the aqueous dispersion of the aromatic hydrocarbon formaldehyde resin (C) is not particularly limited, but from the viewpoint of mixability with the epoxy resin (A) and the curing agent (B), it is preferably from 20.0 mass % to 75.0 mass %, more preferably from 25.0 mass % to 70.0 mass %, and even more preferably from 30.0 mass % to 65.0 mass %.

[0085] From the viewpoints of storage stability and mixability with hydrophilic resins, the average particle size of the solid content in the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) is preferably 0.2 to 2 μm, and more preferably 0.3 to 1.0 μm. In the present invention, the average particle size refers to the volume average particle size (D50) of the emulsion (particles) measured by a dynamic scattering intensity method.

[0086] From the viewpoints of storage stability and miscibility with hydrophilic resins, the pH of the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C), as measured at 25° C. when the aqueous dispersion is diluted 100 times with water, is preferably 2 to 9, and more preferably 3 to 7. The aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) has a white to milky white appearance.

[0087] 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.

[0088] <Production of Aqueous Dispersion of Aromatic Hydrocarbon Formaldehyde Resin (C)> (Production Example 1) A cylindrical, flat-bottomed, four-neck separable flask equipped with a stirrer and a digital thermometer was charged with 745.18 parts by mass of Nikanol H (xylene formaldehyde resin, manufactured by Fudow Co., Ltd.) as the aromatic hydrocarbon formaldehyde resin (C), 19.46 parts by mass of Softlon PE-35 (nonionic surfactant, nonvolatile content 35% by mass, manufactured by Yoshimura Oil Chemical Co., Ltd.) as the nonionic surfactant (D), 3.31 parts by mass of Brownon SR-730 (nonionic surfactant, manufactured by Aoki Oil & Fat Industries Co., Ltd.), 4.17 parts by mass of Newcol 707 (nonionic surfactant, manufactured by Nippon Nyukazai Co., Ltd.), and 9.72 parts by mass of YKA-7200 (nonionic surfactant, manufactured by Aoki Oil & Fat Industries Co., Ltd.), and 29.18 parts by mass of water, and the temperature was adjusted to 30 to 35°C. Thereafter, 50.66 parts by mass of water was added, and the mixture was stirred for 120 minutes. Then, 437.54 parts by mass of water was further added stepwise to dilute the mixture, thereby obtaining an aqueous dispersion of aromatic hydrocarbon-formaldehyde resin (C) (non-volatile content 58.8%, pH 6.1, viscosity (30°C) 380 mPa s, average particle size 0.65 μm, white liquid).

[0089] Details of the nonionic surfactant (D) used in Production Example 1 are as follows: Softlon PE-35: nonionic surfactant (polyether surfactant), 1,3-diisocyanato(methyl)benzene / 2-methyloxirane / oxirane polymer, nonvolatile content 35% by mass, manufactured by Yoshimura Oil Chemical Co., Ltd. Brownon SR-730: nonionic surfactant (polyether surfactant), polyoxyethylene stearyl ether, manufactured by Aoki Oil & Fat Industries Co., Ltd. Newcol 707: nonionic surfactant (polyether surfactant), α-[5-methyl-2,3-bis(2-phenylethyl)phenyl]-ω-hydroxypoly(oxy-1,2-ethanediyl), manufactured by Nippon Nyukazai Co., Ltd. YKA-7200: nonionic surfactant (polyether surfactant), polyoxyethylene stearyl ether, manufactured by Aoki Oil & Fat Industries Co., Ltd.

[0090] The properties of the aromatic hydrocarbon-formaldehyde resin (C) used in Production Example 1 and the aqueous dispersion obtained in Production Example 1 are shown in Table 1. The pH, viscosity (30°C), and average particle size of the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C), as well as the content of volatile organic solvents (VOCs) in the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C), were measured as follows.

[0091] (pH) A preparation liquid was obtained by diluting 1 g of the aqueous dispersion of aromatic hydrocarbon formaldehyde resin (C) obtained in Production Example 1 with 99 g of ion-exchanged water. The pH of the aqueous dispersion of aromatic hydrocarbon formaldehyde resin (C) obtained in Production Example 1 was determined from the obtained preparation liquid using a pH meter (F-51: manufactured by Horiba, Ltd.).

[0092] (Viscosity (30°C)) The aqueous dispersion of aromatic hydrocarbon-formaldehyde resin (C) obtained in Production Example 1 was placed in a 250 ml container, and the sample temperature was adjusted to 30°C. After that, using a Brookfield type viscometer (BL; manufactured by Tokyo Keiki) with rotor No. 2, the rotor was rotated at 60 rpm for 1 minute, and the indicated value was read. The indicated value was multiplied by the conversion multiplier for rotor No. 2 to determine the viscosity (30°C) of the aqueous dispersion of aromatic hydrocarbon-formaldehyde resin (C) obtained in Production Example 1.

[0093] (Average Particle Diameter) Using a measuring device (FPAR-1000; manufactured by Otsuka Electronics Co., Ltd.), the volume average particle diameter (D50) of the emulsion (particles) in the aqueous dispersion of the aromatic hydrocarbon formaldehyde resin (C) obtained in Production Example 1 was determined by a dynamic scattering intensity method, and this was taken as the average particle diameter.

[0094] (Volatile Organic Solvent (VOC) Content in Aqueous Dispersion of Aromatic Hydrocarbon-Formaldehyde Resin (C)) The aromatic hydrocarbon-formaldehyde resin (C) obtained in Production Example 1 was diluted four times with acetone, and then the VOC content was measured by gas chromatography (GC analysis) under the following measurement conditions. The VOC content in the aromatic hydrocarbon-formaldehyde resin (C) was determined as a toluene-equivalent value. (Measurement conditions) Apparatus: Gas chromatograph: Agilent 7890A (Agilent Technologies, Inc.) Column: DB-5MS (30 m x 0.25 mm x 0.25 μm) Detector: FID Carrier gas: Helium (flow rate: 1 mL / min) Sample injection amount: 1.0 μL Column temperature conditions: Initial temperature 50°C, maintained for 5 minutes → heated to 320°C at a heating rate of 20°C / min Injection port temperature: 300°C Detector temperature: 300°C Internal standard substance: tetradecane

[0095]

[0096] <Production of Waterborne Epoxy Resin Composition> In the following examples and comparative examples, the production of waterborne epoxy resin compositions was carried out in an environment of 23°C and 50% RH. (Example 1) Into a plastic container were added 18.5 g of Araldite PZ 3961-1 (solid content concentration: 52 mass%, manufactured by Huntsman) as the epoxy resin (A), 1.32 g of Gaskamine 328W50 (solid content concentration: 50 mass%, reaction product of metaxylylenediamine and epichlorohydrin, manufactured by Mitsubishi Gas Chemical Company, Inc.) as the curing agent (B), and 1.85 g of the aqueous dispersion obtained in Production Example 1 as the aqueous dispersion of aromatic hydrocarbon formaldehyde resin (C), followed by stirring and mixing to obtain a waterborne epoxy resin composition.

[0097] Example 2 An aqueous epoxy resin composition was obtained in the same manner as in Example 1, except that the amount of the aqueous dispersion of aromatic hydrocarbon-formaldehyde resin (C) obtained in Production Example 1 was changed to 3.70 g.

[0098] Comparative Example 1 An aqueous epoxy resin composition was obtained in the same manner as in Example 1, except that the aqueous dispersion of the aromatic hydrocarbon formaldehyde resin (C) was not used.

[0099] Comparative Examples 2 to 4 Aqueous epoxy resin compositions were obtained in the same manner as in Example 1, except that propylene glycol-n-propyl ether was blended in the blending amount shown in Table 2 instead of the aqueous dispersion of aromatic hydrocarbon-formaldehyde resin (C) in Example 1.

[0100] The compositions of the water-based epoxy resin compositions obtained in Examples 1 and 2 and Comparative Examples 1 to 4 are shown in Table 2.

[0101] <Evaluation Method> The aqueous epoxy resin compositions obtained in Examples 1 and 2 and Comparative Examples 1 to 4 were evaluated as follows. The evaluation results are shown in Table 2.

[0102] (Volatile Organic Solvent (VOC) Content in Waterborne Epoxy Resin Composition) The VOC content in the waterborne epoxy resin compositions obtained in the Examples and Comparative Examples was calculated from the VOC content in the epoxy resin (A) used in each Example and Comparative Example, the VOC content in the aqueous dispersion of aromatic hydrocarbon (C), and the content of propylene glycol-n-propyl ether. The VOC content in the epoxy resin (A) was measured in the same manner as in the "Volatile Organic Solvent (VOC) Content in Aromatic Hydrocarbon-Formaldehyde Resin (C)" section above. Propylene glycol monomethyl ether and benzyl alcohol were confirmed as VOCs in the epoxy resin (A). The content of each VOC was determined from calibration data obtained from samples with known VOC concentrations. The VOC content in the aqueous dispersion of aromatic hydrocarbon (C) was measured in the same manner as in the "Volatile Organic Solvent (VOC) Content in Aromatic Hydrocarbon-Formaldehyde Resin (C)" section above. The content of propylene glycol-n-propyl ether was calculated from the amount blended during the production of the aqueous epoxy resin composition.

[0103] (Pot Life Evaluation) The aqueous epoxy resin compositions obtained in the Examples and Comparative Examples were applied to a zinc phosphate-treated steel sheet (SPCC-SD PB-N144, manufactured by Paltec Co., Ltd.) using a 200 μm applicator under conditions of 23°C and 50% RH to form a coating film. The application was carried out every 30 minutes after blending the aqueous epoxy resin composition, and the time until a film could be formed without any problems (no cracks or the like occurred when the film was formed) was confirmed and evaluated. A longer time indicates a longer pot life.

[0104] (Curing speed) The aqueous epoxy resin compositions obtained in the Examples and Comparative Examples were applied to a glass plate (manufactured by Taiyu Kizai Co., Ltd.) at 23°C and 50% RH using a 76 μm applicator to form a coating film. The glass plate on which the coating film had been formed was set in a paint drying time measuring device (manufactured by Taiyu Kizai Co., Ltd.), and the needle of the measuring device scratched the coating film surface, leaving marks, and the time required for the coating to reach semi-dryness was measured according to the following criteria. The results are shown in Table 2. A shorter time indicates a faster curing speed. Semi-dry (dust free): the time required for the needle mark to emerge from within the coating film onto the coating film surface.

[0105]

[0106] From Table 2, it can be seen that the waterborne epoxy resin composition of the present invention has an extended pot life despite having a low content of volatile organic solvents (VOCs).

[0107] The present invention can provide an aqueous epoxy resin composition having a reduced content of volatile organic solvents (VOCs) and an extended pot life, a cured product of the aqueous epoxy resin composition, and a method for producing the aqueous epoxy resin composition.

Claims

1. A water-based epoxy resin composition comprising an epoxy resin (A), a curing agent (B) containing a reaction product (b1) of epichlorohydrin and an amine compound represented by the following general formula (1), an aromatic hydrocarbon formaldehyde resin (C), and water. ２ N-CH ２ -A-CH ２ -NH ２ (1) (In formula (1), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.) 2. The aqueous epoxy resin composition according to claim 1, wherein the content ratio of the epoxy resin (A) to the curing agent (B) is 1 / 1.1 to 1 / 0.3, expressed as [number of epoxy groups in component (A) / number of active hydrogen atoms in component (B)].

3. The aqueous epoxy resin composition according to claim 1 or 2, wherein the reaction product (b1) contains a compound represented by the following general formula (2) as a main component: (In formula (2), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group; and n is a number from 1 to 12.) 4. The aqueous epoxy resin composition according to any one of claims 1 to 3, wherein the aromatic hydrocarbon formaldehyde resin (C) has a number average molecular weight of 100 to 3,000.

5. The aqueous epoxy resin composition according to any one of claims 1 to 4, wherein the aromatic hydrocarbon formaldehyde resin (C) has a hydroxyl value of 10 to 300 mgKOH / g.

6. The aqueous epoxy resin composition according to any one of claims 1 to 5, wherein the content of the aromatic hydrocarbon formaldehyde resin (C) in the aqueous epoxy resin composition is 5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the epoxy resin (A).

7. The aqueous epoxy resin composition according to any one of claims 1 to 6, further comprising a nonionic surfactant (D).

8. The aqueous epoxy resin composition according to claim 7, wherein the nonionic surfactant (D) is at least one selected from the group consisting of polyether surfactants and ester surfactants.

9. The aqueous epoxy resin composition according to any one of claims 1 to 8, wherein the total content of the epoxy resin (A) and the curing agent (B) in the aqueous epoxy resin composition is 50 mass% or more.

10. A cured product of the waterborne epoxy resin composition according to any one of claims 1 to 9.

11. A method for producing an aqueous epoxy resin composition containing an epoxy resin (A), a curing agent (B) containing a reaction product (b1) of epichlorohydrin and an amine compound represented by the following general formula (1), an aromatic hydrocarbon formaldehyde resin (C), and water, the method comprising the step of mixing the epoxy resin (A), the curing agent (B), and an aqueous dispersion of the aromatic hydrocarbon formaldehyde resin (C). ２ N-CH ２ -A-CH ２ -NH ２ (1) (In formula (1), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.) 12. The method for producing an aqueous epoxy resin composition according to claim 11, wherein the reaction product (b1) contains a compound represented by the following general formula (2) as a main component: (In formula (2), A is a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group; and n is a number from 1 to 12.) 13. The method for producing a water-based epoxy resin composition according to claim 11 or 12, wherein the aqueous dispersion of the aromatic hydrocarbon formaldehyde resin (C) further contains a nonionic surfactant (D).

14. The method for producing an aqueous epoxy resin composition according to claim 13, wherein the content of the nonionic surfactant (D) in the aqueous dispersion of the aromatic hydrocarbon-formaldehyde resin (C) is 1.5 parts by mass or more and 15.0 parts by mass or less per 100 parts by mass of the aromatic hydrocarbon-formaldehyde resin (C).

Images