Aqueous resin composition, coating film, method for manufacturing the coating film, aqueous resin composition set

Abstract

An aqueous resin composition comprising an aqueous resin emulsion (α), a curing agent (β), and a curing accelerator (γ), wherein the aqueous resin emulsion (α) contains a copolymer (X), a polyepoxy compound (Y), and an aqueous medium (Z), the copolymer (X) includes structural units derived from a (meth)acrylic acid ester (A) and structural units derived from an ethylenically unsaturated carboxylic acid (B), the structural units derived from the (meth)acrylic acid ester (A) include a structural unit derived from a hydrophilic (meth)acrylic acid ester (A1), one or both of the copolymer (X) and the polyepoxy compound (Y) include a carboxy group, the curing agent (β) contains an aromatic polyamine (F) having active hydrogen, and the curing accelerator (γ) contains a tertiary amine not having active hydrogen.

Description

[Technical Field]

[0001] This invention relates to an aqueous resin composition, a coating film, a method for producing the same, and a set of aqueous resin compositions. This application claims priority based on Japanese Patent Application No. 2021-092839, filed in Japan on June 2, 2021, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] Generally, metal products have surface treatments applied to their surfaces. In particular, metal products used outdoors, and metal products that are expected to be exposed to moisture, are often painted to prevent rust formation.

[0003] Traditionally, paints containing organic solvents have been used for surface coating of metal products. However, when applying paints containing organic solvents to the surface of metal products, measures against volatile organic compounds (VOCs) are necessary for workers and the surrounding environment. Therefore, there is a growing trend to use water-based paints instead of paints containing organic solvents for surface coating of metal products.

[0004] Patent Document 1 describes a thick coating paint composition containing an emulsion composition in which polymer particles are dispersed in an aqueous medium and aggregate. The polymer particles described in Patent Document 1 are produced by emulsion polymerization of structural units formed by polymerizing alkyl (meth)acrylate monomers having alkyl groups with 4 to 14 carbon atoms, structural units formed by polymerizing ethylenically unsaturated carboxylic acid monomers, and structural units formed by polymerizing other monomers, in the presence of a compound having at least two epoxy groups in one molecule and a basic catalyst.

[0005] Patent Document 2 describes a composition comprising an aqueous dispersion of thermoplastic polymer particles that have absorbed a thermosetting compound having an oxirane group. Furthermore, Patent Document 2 describes that the polymer particles have an anti-aggregation functional group at a concentration sufficient to stabilize the latex against aggregation.

[0006] Patent Document 3 describes how to form an acrylate resin (acrylic / epoxy latex) that has absorbed an epoxy compound by mixing an epoxy emulsion with an emulsion of acrylate resin. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2011-89092 [Patent Document 2] Japanese Patent Publication No. 2014-65914 [Patent Document 3] International Publication No. 2017 / 112018 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in aqueous resin compositions used for surface coating of metal products, there is still room for further improvement regarding the initial water resistance and moist heat adhesion to metal materials of the coating film obtained by curing them. In particular, in aqueous resin compositions used for corrosion protection coating of metal products used outdoors, such as steel towers, bridges, ships, and port facilities, there is a need to improve the initial water resistance of the coating film obtained by curing them for the following reasons.

[0009] In other words, a coating film formed using a paint containing an aqueous resin composition exhibits water resistance as the curing reaction of the resin contained in the coating film progresses. Therefore, after applying a paint containing an aqueous resin composition to a metal product to form a coating film, there was a risk that moisture from rainfall, etc., could reach the metal surface through the uncured coating film before it had fully cured, causing rust. For this reason, aqueous resin compositions used in the above applications are required to cure with short curing time at room temperature and to form a coating film that exhibits superior initial water resistance.

[0010] The present invention has been made in view of the above circumstances, and aims to provide an aqueous resin composition and an aqueous resin composition set that can harden with short curing time at room temperature to form a coating film with excellent initial water resistance and that yields a coating film with good moist heat adhesion to metal materials. Furthermore, the present invention aims to provide a coating film made from a cured product of the aqueous resin composition of the present invention, and a method for producing the coating film. [Means for solving the problem]

[0011] The configuration of the present invention for achieving the above objectives is as follows [1] to

[18] .

[0012] The present invention provides compositions according to the following first embodiment. [1] Aqueous resin emulsion (α) and Hardening agent (β), Contains a curing accelerator (γ), The aqueous resin emulsion (α) comprises a copolymer (X), a polyepoxy compound (Y) that does not have ethylenically unsaturated bonds and has two or more epoxy groups in one molecule, and an aqueous medium (Z). The content of the polyepoxy compound (Y) relative to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 1 to 40% by mass. The copolymer (X) comprises structural units derived from (meth)acrylic acid ester (A) and structural units derived from ethylenically unsaturated carboxylic acid (B). The content of structural units derived from the (meth)acrylic acid ester (A) relative to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 20 to 98% by mass. The content of structural units derived from the ethylenically unsaturated carboxylic acid (B) relative to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 0.1 to 10% by mass, and the structural units derived from the (meth)acrylic acid ester (A) include structural units derived from hydrophilic (meth)acrylic acid ester (A1) in which the number of carbon atoms in the alcohol-derived portion is 2 or less. The content of structural units derived from the hydrophilic (meth)acrylic acid ester (A1) relative to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 15 to 98% by mass. The copolymer (X) and the polyepoxy compound (Y), or both thereof, contain a carboxyl group. The curing agent (β) comprises an aromatic polyamine (F) having active hydrogen that is reactive to epoxy groups, The amount of aromatic polyamine (F) contained in the curing agent (β) is such that the amount of active hydrogen contained in the aromatic polyamine (F) is 0.10 equivalents or more and 1.50 equivalents or less per equivalent of epoxy groups contained in the aqueous resin emulsion (α). The curing accelerator (γ) comprises a tertiary amine that does not have active hydrogen that is reactive with epoxy groups, An aqueous resin composition in which the content of the curing accelerator (γ) is 0.0070 mol or more and 1.5 mol or less per equivalent of epoxy groups contained in the aqueous resin emulsion (α).

[0013] A first aspect of the present invention preferably has the following features. It is also preferable to combine two or more of the following features. [2] The aqueous resin composition according to [1], wherein the (meth)acrylic acid ester (A) is an alkyl (meth)acrylic acid ester. [3] The aqueous resin composition according to [1] or [2], wherein the ethylenically unsaturated carboxylic acid (B) comprises at least one from the group consisting of α,β-unsaturated monocarboxylic acid, α,β-unsaturated dicarboxylic acid, and vinyl compounds containing a carboxyl group. [4] The aqueous resin composition according to any one of [1] to [3], wherein the polyepoxy compound (Y) is at least one selected from bisphenol-type epoxy compounds, hydrogenated bisphenol-type epoxy compounds, diglycidyl ethers, triglycidyl ethers, tetraglycidyl ethers, diglycidyl esters, triglycidyl esters, and tetraglycidyl esters.

[0014] [5] The aqueous resin composition according to any one of [1] to [4], wherein the copolymer (X) consists of structural units derived from the (meth)acrylic acid ester (A) and structural units derived from the ethylenically unsaturated carboxylic acid (B). [6] The aqueous resin composition according to any one of [1] to [4], wherein the copolymer (X) comprises structural units derived from an ethylenically unsaturated aromatic compound (C) having a benzene ring and an ethylenically unsaturated bond. [7] The aqueous resin composition according to [6], wherein the ethylenically unsaturated aromatic compound (C) is an aromatic vinyl compound.

[0015] [8] The aqueous resin composition according to any one of [1] to [7], wherein the aromatic polyamine (F) comprises an aromatic polyamine having two or more benzene rings in one molecule. [9] The aqueous resin composition according to any one of [1] to [8], wherein the aromatic polyamine (F) comprises a compound represented by the following general formula (1-1).

[0016] [ka] (In formula (1-1), A 2 , A 3 Each of these independently represents a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group. n represents an integer from 1 to 12.

[0017]

[10] The aqueous resin composition according to [9], wherein the aromatic polyamine (F) comprises the compound represented by the general formula (1-1) and m-xylylenediamine.

[0018]

[11] The aqueous resin composition according to any one of [1] to

[10] , wherein the curing accelerator (γ) is at least one compound selected from the group consisting of tertiary aliphatic amines, tertiary alicyclic amines, and tertiary heteroaromatic amines.

[12] The aqueous resin composition according to any one of [1] to

[11] , wherein the aqueous resin emulsion (α) is an emulsion obtained by emulsion polymerization in the aqueous medium (Z) in the presence of the polyepoxy compound (Y) of monomers that form structural units of the copolymer (X).

[0019]

[13] The content of carboxyl groups in the total amount of the copolymer (X) and the polyepoxy compound (Y) is 0.10 × 10 -4 An aqueous resin composition according to any one of [1] to

[12] , wherein the concentration is mol / g or greater.

[14] The content of epoxy groups in the total amount of the copolymer (X) and the polyepoxy compound (Y) is 0.50 × 10 -4 An aqueous resin composition according to any one of [1] to

[13] , wherein the concentration is mol / g or greater.

[0020] A second aspect of the present invention provides a coating film as described below.

[15] A coating film comprising a cured product of an aqueous resin composition described in any one of items [1] to

[14] . A third aspect of the present invention provides a manufacturing method described below.

[16] A mixing step of preparing an aqueous resin composition according to any of [1] to

[14] by mixing an aqueous resin emulsion (α), a curing agent (β), and a curing accelerator (γ), A method for producing a coating film, comprising a coating step of applying the aqueous resin composition to a surface to be coated. The manufacturing method of the third embodiment of the present invention preferably has the following characteristics.

[17] The method for manufacturing a coating film according to

[16] , wherein the coating step is completed within one hour after the completion of the mixing step.

[0021] A fourth aspect of the present invention provides the aqueous resin composition set described below.

[18] The components of the aqueous resin composition described in any one of the items [1] to

[14] are stored separately as a first liquid and a second liquid. The first liquid comprises the aqueous resin emulsion (α), A set of aqueous resin compositions in which the second liquid contains the curing agent (β) and the curing accelerator (γ). [Effects of the Invention]

[0022] According to the present invention, it is possible to provide an aqueous resin composition and an aqueous resin composition set that can harden with short curing time at room temperature to form a coating film with excellent initial water resistance and that yields a coating film with good moist heat adhesion to metal materials. Furthermore, according to the present invention, it is possible to provide a coating film made from a cured product of the aqueous resin composition of the present invention, which has good initial water resistance and moist heat adhesion to metal materials. Furthermore, according to the present invention, it is possible to provide a method for producing a coating film that is made of a cured product of the aqueous resin composition of the present invention. [Modes for carrying out the invention]

[0023] The following describes in detail preferred examples of the aqueous resin composition, coating film, method for producing the coating film, and aqueous resin composition set of the present invention. It should be noted that the present invention is not limited to the embodiments shown below. The present invention allows for additions, omissions, substitutions, and modifications to the number, types, positions, quantities, ratios, materials, and configurations, for example, without departing from the spirit of the invention.

[0024] Herein, we will explain the following terms used in this specification. "(Meth)acrylate" means acrylate or methacrylate. Similarly, "(Meth)acrylic" means acrylic or methacrylic. An "ethylenically unsaturated bond" refers to a double bond between carbon atoms, excluding the carbon atoms that form the aromatic ring. "Weight-average molecular weight" shall be the standard polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0025] In a polymer using a compound having an ethylenically unsaturated bond, the structural unit derived from the compound having the ethylenically unsaturated bond may mean a unit in which the chemical structure of the part of the compound other than the ethylenically unsaturated bond is the same as the chemical structure of the part of the polymer other than the part corresponding to the ethylenically unsaturated bond of the structural unit. The ethylenically unsaturated bond of the compound may be changed to a single bond when forming the polymer. For example, in a polymer of methyl methacrylate, the structural unit derived from methyl methacrylate is represented by -CH2-C(CH3)(COOCH3)-.

[0026] Furthermore, in the case of polymers of compounds having ionic functional groups and ethylenically unsaturated bonds, for example, structural units having ionic functional groups such as carboxyl groups, like the structural unit (b) derived from the ethylenically unsaturated carboxylic acid (B) described later, may be considered structural units derived from the same ionic compound even if some of the functional groups are ion-exchanged or not. For example, the structural unit represented by -CH2-C(CH3)(COONa)- may also be considered a structural unit derived from methacrylic acid.

[0027] Furthermore, for compounds having multiple independent ethylenically unsaturated bonds, one or more ethylenically unsaturated bonds may remain within the structural unit as a structural unit of the polymer of the compound. Multiple independent ethylenically unsaturated bonds may mean multiple ethylenically unsaturated bonds that do not form conjugated dienes with each other. For example, in the case of a polymer of divinylbenzene, the structural unit derived from divinylbenzene may be a structure without ethylenically unsaturated bonds (a form in which both parts corresponding to the two ethylenically unsaturated bonds of divinylbenzene are incorporated into the polymer chain), or it may be a structure having one ethylenically unsaturated bond (a form in which only the part corresponding to one of the ethylenically unsaturated bonds is incorporated into the polymer chain).

[0028] "Hardening" refers to the process where molecules in the raw materials bond together through chemical reactions, forming a polymer with a network structure. The term "coating film" refers to a cured product formed by curing the resin component contained in the aqueous resin composition of this embodiment, which is integrated with the surface to be coated, obtained by methods such as applying the aqueous resin composition to the surface to be coated and drying the medium. The term "coating" refers to a cured product formed by curing the resin component contained in the aqueous resin composition of this embodiment, which is peeled off the substrate after curing on the substrate.

[0029] <Aqueous resin composition> The aqueous resin composition of this embodiment comprises an aqueous resin emulsion (α), a curing agent (β), and a curing accelerator (γ). The aqueous resin composition of this embodiment is produced by mixing the aqueous resin emulsion (α), the curing agent (β), and the curing accelerator (γ), as described later.

[0030] [1-1. Water-based resin emulsion (α)] The aqueous resin emulsion (α) comprises a copolymer (X), a polyepoxy compound (Y) that does not have ethylenically unsaturated bonds and has two or more epoxy groups in one molecule, and an aqueous medium (Z). The aqueous resin emulsion (α) is an emulsion obtained by emulsion polymerization of monomers that form the structural units of the copolymer (X) in the aqueous medium (Z) in the presence of the polyepoxy compound (Y). By mixing the aqueous resin emulsion (α) with a curing agent (β) and a curing accelerator (γ) described later and curing it, a cured product with high strength and high elongation is formed.

[0031] <1-1-1. Copolymer (X)> The copolymer (X) has structural units (a) derived from (meth)acrylic acid ester (A) and structural units (b) derived from ethylenically unsaturated carboxylic acid (B). The structural unit (a) derived from (meth)acrylic acid ester (A) includes structural units (a1) derived from hydrophilic (meth)acrylic acid ester (A1).

[0032] Copolymer (X) may consist of structural unit (a) and structural unit (b) (referred to as copolymer (X1)). Copolymer (X) may also have structural unit (a), structural unit (b), and structural unit (c) derived from an ethylenically unsaturated aromatic compound (C) having a benzene ring and an ethylenically unsaturated bond (referred to as copolymer (X2)). Copolymer (X2) may consist only of structural units (a) to (c). Copolymer (X) may also have structural unit (d) other than structural units (a) to (c) (referred to as a structural unit derived from another monomer (D)).

[0033] The amount of copolymer (X) contained in the aqueous resin emulsion (α) can be arbitrarily selected, but it is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, relative to the total amount of aqueous resin emulsion (α). The amount of copolymer (X) contained in the aqueous resin emulsion (α) can be arbitrarily selected, but it is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, relative to the total amount of aqueous resin emulsion (α). However, it is not limited to these examples.

[0034] The content of copolymer (X) relative to the total amount of copolymer (X) and the polyepoxy compound (Y) described later is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 65% ​​by mass or more. The content of copolymer (X) relative to the total amount of copolymer (X) and the polyepoxy compound (Y) described later is preferably 99% by mass or less, more preferably 94% by mass or less, and even more preferably 88% by mass or less.

[0035] [(meth)acrylic acid ester (A)] The (meth)acrylate ester (A) preferably includes an alkyl (meth)acrylate, and more preferably consists of an alkyl (meth)acrylate. Examples of alkyl (meth)acrylates include, more preferably, linear, branched, or cyclic alkyl (meth)acrylates having 1 to 18 carbon atoms. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isobolonyl (meth)acrylate. These may be used individually or in combination of two or more.

[0036] Examples of (meth)acrylic acid esters (A) may also include examples of hydrophilic (meth)acrylic acid esters (A1) described later. (Meth)acrylic acid esters having a carboxyl group are not included in (meth)acrylic acid esters (A), but are included in ethylenically unsaturated carboxylic acids (B), which will be described later.

[0037] It is preferable that the (meth)acrylic acid ester (A) includes a compound with low hydrophilicity. This is because it improves the rust prevention properties of the coating film made from the cured product of the aqueous resin composition of this embodiment. For the same reason, the (meth)acrylic acid ester (A) may include a (meth)acrylic acid ester having an epoxy group.

[0038] Examples of the epoxy group-containing (meth)acrylic acid esters include glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, and 3,4-epoxycyclohexylpropyl (meth)acrylate.

[0039] Structural unit (a) may contain structural units derived from only one of these compounds, or it may contain structural units derived from two or more of these compounds. Furthermore, among these compounds, structural unit (a) preferably contains structural units derived from glycidyl (meth)acrylate.

[0040] Furthermore, (meth)acrylic acid ester (A) may be a (meth)acrylic acid ester that is neither an alkyl (meth)acrylic acid ester nor a compound having an epoxy group. Examples of such (meth)acrylic acid esters include (meth)acrylic acid esters having a hydroxyl group.

[0041] Examples of (meth)acrylic acid esters having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, mono(meth)acrylic acid esters of polyethylene glycol, and mono(meth)acrylic acid esters of polyalkylene glycols such as mono(meth)acrylic acid esters of polypropylene glycol. These (meth)acrylic acid esters having a hydroxyl group may be used individually or in combination of two or more.

[0042] The content of structural units (a) derived from (meth)acrylic acid ester (A) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is 20% by mass or more. This is because it is possible to improve the dispersibility between the monomer of copolymer (X) and the polyepoxy compound (Y) in the method for producing the aqueous resin emulsion (α) described later. From this viewpoint, the content of structural units (a) derived from (meth)acrylic acid ester (A) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is preferably 35% by mass or more, more preferably 45% by mass or more, and even more preferably 60% by mass or more.

[0043] In this embodiment, the content of structural units derived from the compound contained in the copolymer may mean a value calculated based on the mass of the compound used as a raw material for the copolymer. Specifically, for example, the content of structural units (a) derived from (meth)acrylic acid ester (A) relative to the total amount of copolymer (X) and polyepoxy compound (Y) may mean the ratio (mass%) of the mass of (meth)acrylic acid ester (A) used in the production of copolymer (X) relative to the total amount.

[0044] When the copolymer (X) consists of structural unit (a) and structural unit (b), i.e., when it is copolymer (X1), the following ratio is preferable from the viewpoint of improving the dispersibility between the monomer that forms copolymer (X1) and the polyepoxy compound (Y). That is, the content of structural unit (a) derived from (meth)acrylic acid ester (A) relative to the total amount of copolymer (X1) and polyepoxy compound (Y) is more preferably 50% by mass or more, and particularly preferably 60% by mass or more.

[0045] The content of structural units (a) derived from (meth)acrylic acid ester (A) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is 98% by mass or less. This is because exceeding 98% by mass tends to reduce the dispersibility of the aqueous resin emulsion (α). From this viewpoint, the content of structural units (a) derived from (meth)acrylic acid ester (A) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is preferably 92% by mass or less, and more preferably 87% by mass or less.

[0046] When copolymer (X) has structural units (a), structural units (b), and structural units (c), that is, when copolymer (X) is copolymer (X2), the dispersibility of aqueous resin emulsion (α) tends to decrease, so the following proportions are preferable. The content of structural unit (a) derived from (meth)acrylic acid ester (A) in copolymer (X2) is more preferably 75% by mass or less, and particularly preferably 65% ​​by mass or less.

[0047] [Hydrophilic (meth)acrylic acid ester (A1)] The structural units derived from the (meth)acrylic acid ester (A) include structural units derived from the hydrophilic (meth)acrylic acid ester (A1). Hydrophilic (meth)acrylic acid ester (A1) is a (meth)acrylic acid ester having a (meth)acryloyloxy group (CH2=CR-COO-, where R represents hydrogen or a methyl group), and the number of carbon atoms in the alcohol-derived portion, i.e., the portion other than the (meth)acryloyloxy group, is 2 or less. The number of carbon atoms in the portion other than the acryloyloxy group may be, for example, 1 or 2.

[0048] Examples of hydrophilic (meth)acrylic acid esters (A1) include methyl (meth)acrylate, ethyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. Hydrophilic (meth)acrylic acid ester (A1) is preferably an alkyl (meth)acrylate ester with 2 or fewer carbon atoms in the alcohol-derived portion, and more preferably methyl methacrylate.

[0049] The content of structural units (a1) derived from hydrophilic (meth)acrylic acid ester (A1) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is 15% by mass or more. If the content of structural units (a1) derived from hydrophilic (meth)acrylic acid ester (A1) is less than 15% by mass, rapid gelation will occur when the aqueous resin emulsion (α), the curing agent (β) containing aromatic polyamine, and the curing accelerator (γ) are mixed.

[0050] The content of structural units (a1) derived from hydrophilic (meth)acrylic acid ester (A1) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is 15% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. This is because the water resistance and rust prevention properties of the coating film made from the cured product of the aqueous resin composition of this embodiment are further improved. The content of structural units (a1) may be 45% by mass or more, or 50% by mass or more.

[0051] The upper limit of the content of structural units (a1) derived from hydrophilic (meth)acrylic acid ester (A1) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is the same as the upper limit of the content of structural units (a) derived from (meth)acrylic acid ester (A). That is, the upper limit is 98% by mass or less, preferably 92% by mass or less, and more preferably 87% by mass or less. However, if the polyepoxy compound (Y) described later is a hydrophobic compound such as a bisphenol-type epoxy compound, a hydrogenated bisphenol-type epoxy compound, or a phenol novolac-type epoxy compound, the proportion of structural unit (a1) to structural unit (a) is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 60% by mass or less. This is to improve the affinity between the copolymer (X) and the polyepoxy compound (Y).

[0052] [Ethylene-unsaturated carboxylic acid (B)] Ethylene-unsaturated carboxylic acid (B) is a compound having an ethylenically unsaturated bond and a carboxyl group. Ethylene-unsaturated carboxylic acid (B) preferably contains at least one from the group consisting of α,β-unsaturated monocarboxylic acid, α,β-unsaturated dicarboxylic acid, monoalkyl ester of α,β-unsaturated dicarboxylic acid, and vinyl compounds containing a carboxyl group. Examples of α,β-unsaturated mono or dicarboxylic acid include acrylic acid, methacrylic acid, crotonic acid, citraconic acid, itaconic acid, maleic acid, maleic anhydride, and fumaric acid. Examples of vinyl compounds containing a carboxyl group include monohydroxyethyl (meth)acrylate phthalate and monohydroxypropyl (meth)acrylate oxalate.

[0053] Structural unit (b) may be a structural unit derived from only one of these compounds, or it may contain structural units derived from two or more compounds. Among these compounds, it is preferable that the ethylenically unsaturated carboxylic acid (B) includes a compound having a (meth)acryloyl group and a carboxyl group, or consists only of a compound having a (meth)acryloyl group and a carboxyl group. It is also preferable that the ethylenically unsaturated carboxylic acid (B) includes (meth)acrylic acid, or consists only of (meth)acrylic acid. It is preferable that structural unit (b) consists only of structural units derived from a compound having a (meth)acryloyl group and a carboxyl group, and it is even more preferable that it includes structural units derived from (meth)acrylic acid.

[0054] The content of structural units (b) derived from ethylenically unsaturated carboxylic acid (B) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is 0.1% by mass or more. This is to improve the dispersibility of the aqueous resin emulsion (α). From this viewpoint, the content of structural units (b) derived from ethylenically unsaturated carboxylic acid (B) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is preferably 0.3% by mass or more, and more preferably 0.5% by mass or more. The content of structural units (b) may be 0.8% by mass or more, or 1.0% by mass or more.

[0055] The content of structural units (b) derived from ethylenically unsaturated carboxylic acid (B) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is 10% by mass or less. This is to suppress the copolymer (X) from becoming gel-like in high-temperature environments and to improve the high-temperature stability of the aqueous resin emulsion (α). From this viewpoint, the content of structural units (b) derived from ethylenically unsaturated carboxylic acid (B) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is preferably 7% by mass or less, and more preferably 5% by mass or less. The content of structural units (b) may be 4% by mass or less, or even 3% by mass or less.

[0056] Furthermore, the content of structural units (b) derived from ethylenically unsaturated carboxylic acid (B) relative to the total amount of copolymer (X) is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.8% by mass or more. The content of structural units (b) derived from ethylenically unsaturated carboxylic acid (B) relative to the total amount of copolymer (X) is preferably 12% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less.

[0057] [Ethylene-unsaturated aromatic compounds (C)] The ethylenically unsaturated aromatic compound (C) is a compound that does not fall under either (meth)acrylic acid ester (A) or ethylenically unsaturated carboxylic acid (B), and has a benzene ring and an ethylenically unsaturated bond. The ethylenically unsaturated aromatic compound (C) is preferably an aromatic vinyl compound.

[0058] Examples of aromatic vinyl compounds as ethylenically unsaturated aromatic compounds (C) include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, tert-butoxystyrene, vinyltoluene, divinyltoluene, vinylnaphthalene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromostyrene, tribromostyrene, fluorostyrene, styrenesulfonic acid and its salts, α-methylstyrenesulfonic acid and its salts, p-hydroxystyrene, m-hydroxystyrene, o-hydroxystyrene, p-isopropenylphenol, m-isopropenylphenol, and o-isopropenylphenol. Structural unit (c) may be derived from only one of these compounds, or it may include structural units derived from two or more of these compounds. Among these, structural unit (c) is more preferably composed of structural units derived from hydrocarbons, and particularly preferably derived from styrene.

[0059] When copolymer (X) contains structural units (c) derived from ethylenically unsaturated aromatic compounds (C), i.e., copolymer (X) is copolymer (X2), the content of structural units (c) relative to the total amount of copolymer (X2) and polyepoxy compound (Y) is preferably 5% by mass or more. This is to improve the water resistance of the coating film made from the cured product of the aqueous resin composition of this embodiment. From this viewpoint, the content of structural units (c) relative to the total amount of copolymer (X2) and polyepoxy compound (Y) is more preferably 10% by mass or more, and even more preferably 15% by mass or more. The content of structural units (c) may be 18% by mass or more, 20% by mass or more, or 23% by mass or more.

[0060] When copolymer (X) is copolymer (X2), the content of structural units (c) relative to the total amount of copolymer (X2) and polyepoxy compound (Y) is preferably 50% by mass or less. This is because the weather resistance of the coating film made from the cured product of the aqueous resin composition of this embodiment is improved. From this viewpoint, the content of structural units (c) relative to the total amount of copolymer (X2) and polyepoxy compound (Y) is more preferably 40% by mass or less, and even more preferably 35% by mass or less. The content of structural units (c) may be 33% by mass or less, 30% by mass or less, or 28% by mass or less.

[0061] The content of structural units (c) relative to the total amount of copolymer (X2) is preferably 5% by mass or more, more preferably 15% by mass or more, and even more preferably 25% by mass or more. The content of structural units (c) relative to the total amount of copolymer (X2) is preferably 55% by mass or less, more preferably 45% by mass or less, and even more preferably 35% by mass or less.

[0062] [Other monomers (D)] The other monomer (D) is a compound that does not fall under any of the categories of (meth)acrylic acid ester (A), ethylenically unsaturated carboxylic acid (B), or ethylenically unsaturated aromatic compound (C), and has an ethylenically unsaturated bond that can copolymerize with the compound used in the synthesis of copolymer (X). Other monomers (D) include, for example, conjugated diene compounds, maleimide compounds, vinyl ether compounds, allyl ether compounds, dialkyl esters of unsaturated dicarboxylic acids, and vinyl compounds having a cyano group.

[0063] Examples of the aforementioned conjugated diene compounds include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and chloroprene (2-chloro-1,3-butadiene). These conjugated diene compounds may be used individually or in combination of two or more.

[0064] Examples of the maleimide compounds include maleimide, N-methylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-dodecylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-diethylphenyl)maleimide, N-(2-methoxyphenyl)maleimide, N-benzylmaleimide, N-(4-hydroxyphenyl)maleimide, N-naphthylmaleimide, and N-cyclohexylmaleimide. These maleimide compounds may be used individually or in combination of two or more.

[0065] Examples of the vinyl ether compound include alkyl vinyl ethers such as methyl vinyl ether or ethyl vinyl ether, and hydroxyl group-containing alkyl vinyl ethers in which some hydrogen atoms are substituted with hydroxyl groups.

[0066] Examples of the allyl ether compounds include allyl alkyl ethers such as allyl methyl ether or allyl ethyl ether, hydroxyl group-containing allyl alkyl ethers in which some hydrogen atoms are substituted with hydroxyl groups, and allyl glycidyl ether.

[0067] Examples of the dialkyl esters of the unsaturated dicarboxylic acids mentioned above include dialkyl esters of unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, and tetrahydrophthalic anhydride. These dialkyl esters of unsaturated dicarboxylic acids may be used individually or in combination of two or more.

[0068] Examples of vinyl compounds having a cyano group include acrylonitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile, and α-fluoroacrylonitrile. These cyano group-containing vinyl monomers may be used individually or in combination of two or more.

[0069] <1-1-2. Polyepoxy Compounds (Y)> Polyepoxy compound (Y) is a compound that does not have ethylenically unsaturated bonds and has two or more epoxy groups in one molecule. The polyepoxy compound (Y) is preferably at least one selected from bisphenol-type epoxy compounds, hydrogenated bisphenol-type epoxy compounds, diglycidyl ethers, triglycidyl ethers, tetraglycidyl ethers, diglycidyl esters, triglycidyl esters, and tetraglycidyl esters.

[0070] Examples of compounds having two or more epoxy groups in one molecule include diglycidyl ether of bisphenol A, diglycidyl ether of hydrogenated bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of hydrogenated bisphenol F, polyglycidyl ether of glycerin, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diglycidyl ester of phthalic acid, 1,4-cyclohexanedimethanol diglycidyl ether, 1,3-cyclohexanedimethanol diglycidyl ether, and diglycidyl ester of hexahydrophthalic acid. The compound may contain one of these compounds or two or more.

[0071] The polyepoxy compound (Y) is more preferably a bisphenol-type epoxy compound or a hydrogenated bisphenol-type epoxy compound, even more preferably a bisphenol A-type epoxy compound or a hydrogenated bisphenol A-type epoxy compound, and even more preferably a bisphenol A-type epoxy compound. This is because the water resistance and rust prevention properties of the coating film made from the cured product of the aqueous resin composition of this embodiment are further improved.

[0072] The weight-average molecular weight of the polyepoxy compound (Y) is not particularly limited, but is preferably 1000 or less, more preferably 800 or less, and even more preferably 500 or less. This improves the compatibility of the polyepoxy compound (Y) with the copolymer (X), resulting in an aqueous resin emulsion (α) with excellent dispersibility and storage stability. The lower limit of the weight-average molecular weight of the polyepoxy compound (Y) can be arbitrarily selected and may be, for example, 200 or 300, but is not limited to these.

[0073] The epoxy equivalent (mass of polyepoxy compound (Y) per mole of epoxy groups) of the polyepoxy compound (Y) is preferably 500 g / mol or less, more preferably 350 g / mol or less, even more preferably 250 g / mol or less, and particularly preferably 200 g / mol or less. This is because it increases the strength of the film made from the cured product of the aqueous resin composition of this embodiment. The lower limit of the epoxy equivalent can be arbitrarily selected and may be, for example, 70 g / mol or more, or 120 g / mol or more, but is not limited to these examples.

[0074] The content of polyepoxy compound (Y) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is 1% by mass or more. This is because curing the aqueous resin composition yields a coating film with excellent rust prevention properties. From this viewpoint, the content of polyepoxy compound (Y) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. If necessary, it may be 12% by mass or more, or even 20% by mass or more. The content of the polyepoxy compound (Y) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is 40% by mass or less. This is because a highly dispersible aqueous resin emulsion (α) can be obtained. From this viewpoint, the content of the polyepoxy compound (Y) relative to the total amount of copolymer (X) and polyepoxy compound (Y) is preferably 35% by mass or less, and more preferably 30% by mass or less.

[0075] The amount of polyepoxy compound (Y) contained in the aqueous resin emulsion (α) is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 4% by mass or more, relative to the total amount of the aqueous resin emulsion (α). The amount of polyepoxy compound (Y) contained in the aqueous resin emulsion (α) is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, relative to the total amount of the aqueous resin emulsion (α).

[0076] <1-1-3. Aqueous medium (Z)> The aqueous medium (Z) can be selected arbitrarily, but water is preferred. However, as long as the dispersibility of the copolymer (X) and the polyepoxy compound (Y) is not impaired, for example, a solution of water with a water-soluble solvent added may be used as the aqueous medium (Z). The hydrophilic (water-soluble) solvent added to the water can be selected arbitrarily, and examples include methanol, ethanol, and N-methylpyrrolidone.

[0077] The amount of aqueous medium (Z) in the aqueous resin emulsion (α) can be selected as needed, but it is preferably an amount such that the non-volatile content concentration in the aqueous resin emulsion (α) is 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. The amount of aqueous medium (Z) in the aqueous resin emulsion (α) can be selected as needed, but it is preferably 80% by mass or less, and more preferably 70% by mass or less. The non-volatile content concentration in the aqueous resin emulsion (α) may be 50-70% by mass or 55-65% by mass.

[0078] <1-1-4. Method for producing aqueous resin emulsion (α)> The method for producing the aqueous resin emulsion (α) according to this embodiment can be carried out by emulsion polymerization in an aqueous medium (Z) in the presence of a polyepoxy compound (Y), using monomers containing (meth)acrylic acid ester (A) and ethylenically unsaturated carboxylic acid (B) (i.e., monomers for constituting the copolymer (X)).

[0079] The content of each raw material in the total raw materials used in the manufacture of aqueous resin emulsion (α) is the same as the content of structural units derived from the raw materials or compounds corresponding to the raw materials in the aqueous resin emulsion (α).

[0080] In the method for producing the aqueous resin emulsion (α) of this embodiment, the emulsion polymerization method can be one in which all components, including monomers, are added at once, or one in which each component is continuously supplied while polymerization is performed. Stirring is preferable during the polymerization reaction. Emulsion polymerization is preferably carried out at a temperature of any choice, for example, 30 to 90°C, more preferably 40 to 80°C, and even more preferably 40 to 70°C. This is to suppress the reaction of carboxyl groups contained in the monomer with epoxy groups contained in the polyepoxy compound (Y).

[0081] Emulsifiers may be used in emulsion polymerization. The emulsifier used can be arbitrarily selected and examples include nonionic surfactants such as polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenol ethers, polyoxyalkylene fatty acid esters, and polyoxyalkylene sorbitan fatty acid esters, and anionic surfactants such as alkyl sulfate salts, alkylbenzene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, polyoxyalkylene alkyl sulfates, and polyoxyalkylene alkyl phosphate esters. These may be used individually or in combination of two or more. Among these emulsifiers, alkylbenzene sulfonates are preferred, and sodium dodecylbenzenesulfonate is more preferred.

[0082] In emulsion polymerization, it is preferable to use a polymerization initiator. For example, it is preferable to use a peroxide as the polymerization initiator. Examples of peroxides that can be used as polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate, and hydrogen peroxide. In addition, a redox initiator using a combination of a peroxide and a reducing agent can also be used. Examples of reducing agents include sodium sulfoxylate formaldehyde, ascorbic acid, sulfites, tartaric acid or its salts. Furthermore, alcohols and mercaptans may be used as chain transfer agents as needed.

[0083] According to the method for producing the aqueous resin emulsion (α) of this embodiment, it is believed that an aqueous resin emulsion (α) can be obtained in which the polyepoxy compound (Y) is uniformly dispersed in the particles of the copolymer (X) produced. Here, "uniformly dispersed" does not necessarily mean that the copolymer (X) and the polyepoxy compound (Y) are miscible; it is sufficient that the domains of the polyepoxy compound (Y) are present without bias both on the central and surface sides of the copolymer (X) particles.

[0084] <1-1-5. Properties of Aqueous Resin Emulsion (α)> [pH of aqueous resin emulsion (α)] The pH of the aqueous resin emulsion (α) is preferably 2 to 10, and more preferably 5 to 9. A pH within this range improves the mechanical and chemical stability of the aqueous resin emulsion (α). The pH was measured at a liquid temperature of 25°C using a pH meter with a hydrogen ion concentration indicator and a glass electrode as the standard electrode. For example, the pH can be adjusted by adding a basic substance to the aqueous resin emulsion (α) during or after emulsion polymerization. Examples of basic substances used for pH adjustment include ammonia, triethylamine, ethanolamine, and caustic soda. These may be used individually or in combination of two or more.

[0085] [Non-volatile content concentration of aqueous resin emulsion (α)] The non-volatile content concentration of the aqueous resin emulsion (α) is preferably 10 to 65% by mass, more preferably 15 to 60% by mass, and even more preferably 20 to 55% by mass. The non-volatile content concentration may also be 30 to 50% by mass, or 35 to 45% by mass. The non-volatile content concentration in the aqueous resin emulsion (α) can be appropriately determined considering the workability in the mixing step of the aqueous resin emulsion (α) with the curing agent (β) and curing accelerator (γ), etc., or in the coating step of the aqueous resin composition, as described later. The non-volatile content concentration in the aqueous resin emulsion (α) can be appropriately adjusted by adjusting the amount of aqueous medium (Z) added.

[0086] The non-volatile content concentration of the aqueous resin emulsion (α) was determined by the following method. 1 g of aqueous resin emulsion (α) was weighed onto a 5 cm diameter aluminum dish, dried at atmospheric pressure in a drying oven at 105°C for 1 hour with circulating air, and the mass of the resulting residue was measured. The ratio (mass %) of the measured residue mass to the mass of the aqueous resin emulsion (α) before drying was determined as the non-volatile content concentration of the aqueous resin emulsion (α).

[0087] [Viscosity of aqueous resin emulsion (α)] In this embodiment, the viscosity of the aqueous resin emulsion (α) is measured at 23°C. The measurement of the viscosity of the aqueous resin emulsion (α) is performed using a B-type viscometer, and the measured value is obtained by selecting a rotor according to the viscosity of the aqueous resin emulsion at a rotational speed of 60 rpm. For example, when the viscosity of the aqueous resin emulsion (α) is about several mPa·s to several hundred mPa·s, it is measured using Rotor No. 1. The viscosity may be, for example, 0.1 to 300 mPa·s, 1 to 100 mPa·s, 3 to 50 mPa·s, or 5 to 25 mPa·s.

[0088] [Glass transition point of the copolymer (X)] The glass transition point Tg of the copolymer (X) is calculated based on the glass transition points of the homopolymers of each monomer used in the synthesis of the copolymer (X). The specific calculation method of the glass transition point Tg of the copolymer (X) is as follows: the glass transition point Tg i of the homopolymer of the monomer M i (i = 1, 2, 3...), and the mass fraction X i of the monomer i in all monomers i (ΣX i (total monomers) = 1), and is calculated by the following formula (1). In formula (1), both Tg and Tg i are calculated using values in absolute temperature (K). 1 / Tg = Σ(X i / Tg i )…(1)

[0089] As the glass transition point of the homopolymer used for the calculation of Tg, the values described in known materials shall be used. Specifically, the values are listed in "Polymer Handbook" (3rd Edition, John Wiley & Sons, Inc., 1989). For monomers with multiple types of values described in the above Polymer Handbook, the highest value shall be adopted.

[0090] The glass transition temperature Tg of copolymer (X) is preferably -30°C (243K) or higher. This is because the strength of the film made from the cured aqueous resin composition of this embodiment is improved. From this viewpoint, the glass transition temperature Tg of copolymer (X) is more preferably -10°C (263K) or higher, and even more preferably 0°C (273K) or higher. The glass transition temperature Tg of copolymer (X) may be 5°C or higher, or 10°C or higher. The glass transition temperature Tg of copolymer (X) is preferably 100°C (373K) or lower, and more preferably 80°C (353K) or lower. This is because the adhesion of the coating film made from the cured aqueous resin composition of this embodiment to the substrate is improved. From this viewpoint, the glass transition temperature Tg of copolymer (X) is more preferably 60°C (333K) or lower, and particularly preferably 50°C (323K) or lower. This is because in this range, the flexibility of the coating film made from the cured aqueous resin composition of this embodiment can be improved. The glass transition temperature Tg of copolymer (X) may be 40°C or lower, or 30°C or lower.

[0091] [Epoxy group content in aqueous resin emulsion (α)] The epoxy group content in aqueous resin emulsion (α) is the ratio of moles of epoxy groups contained in 1 g of aqueous resin emulsion (α). The method for determining the amount of epoxy groups N1 [mol / g] per 1 g of aqueous resin emulsion (α) is as described in the examples below.

[0092] [Epoxy group content in the total amount of copolymer (X) and polyepoxy compound (Y)] The polyepoxy compound (Y) contained in the aqueous resin emulsion (α) in this embodiment contains epoxy groups. The content of epoxy groups in the total amount of copolymer (X) and polyepoxy compound (Y) is 0.50 × 10⁻⁶. -4 Preferably, the concentration is 1.0 × 10⁻⁶ or higher. -4 It is more preferable that the value be mol / g or higher, and 4.0 × 10 -4 It is more preferably mol / g or higher, and 6.0 × 10 -4It is even more preferable that the concentration be mol / g or higher. This is because it can improve the water resistance, rust prevention, and adhesion to the substrate of the coating film made from the cured product of the aqueous resin composition of this embodiment.

[0093] The epoxy group content in the total amount of copolymer (X) and polyepoxy compound (Y) is 50 × 10 -4 It is preferable that the concentration be mol / g or less, and 30 × 10 -4 It is more preferable that the amount be mol / g or less, and 20 × 10 -4 It is even more preferable that the amount is mol / g or less. The content of epoxy groups in the total amount of copolymer (X) and polyepoxy compound (Y) is 15 × 10⁻⁶. -4 mol / g or less, or 10 × 10 -4 It may be less than mol / g.

[0094] [Epoxy group content in the non-volatile components of aqueous resin emulsion (α)] The epoxy group content in the nonvolatile components of the aqueous resin emulsion (α) is 0.50 × 10⁻⁶. -4 Preferably, it is mol / g or higher, 3.0 × 10 -4 It is more preferable that the concentration be mol / g or higher, and 5.0 × 10 -4 It is even more preferable that the concentration be mol / g or higher. This is because it can improve the water resistance, rust prevention, and adhesion to the substrate of the coating film made from the cured product of the aqueous resin composition of this embodiment. The epoxy group content in the nonvolatile content of the aqueous resin emulsion (α) is 1.0 × 10⁻⁶. -4 mol / g or more, or 6.0 × 10⁻⁶ -4 It may be mol / g or higher.

[0095] The epoxy group content in the nonvolatile components of the aqueous resin emulsion (α) is 50 × 10 -4 It is preferable that the concentration be mol / g or less, and 30 × 10 -4 It is more preferable that the amount be mol / g or less, and 20 × 10 -4 It is even more preferable that the concentration be mol / g or less. The epoxy group content in the nonvolatile content of the aqueous resin emulsion (α) is 15 × 10⁻⁶. -4mol / g or less, or 10 × 10 -4 It may be less than mol / g.

[0096] R is the content of epoxy groups in the nonvolatile matter of (α) in the aqueous resin emulsion. EP [mol / g] is a value obtained as follows: The non-volatile content concentration of aqueous resin emulsion (α) is C S [mass%], if N1 [mol / g] is the amount of epoxy groups contained in 1g of aqueous resin emulsion (α), then the epoxy group content R EP This can be expressed as shown in equation (2). The method for determining N1 is described later in the examples. R EP [mol / g] = N1 / (C) S / 100) ... (2)

[0097] [Carboxylate group content in aqueous resin emulsion (α)] The carboxyl group content in aqueous resin emulsion (α) is the ratio of moles of carboxyl groups contained in 1 g of aqueous resin emulsion (α). The method for determining the number of moles of carboxyl groups per 1 g of aqueous resin emulsion (α) is as described in the examples below.

[0098] [Carboxylate group content in the total amount of copolymer (X) and polyepoxy compound (Y)] In this embodiment, one or both of the copolymer (X) and the polyepoxy compound (Y) contained in the aqueous resin emulsion (α) contain carboxyl groups, and it is preferable that the copolymer (X) contains carboxyl groups. The content of carboxyl groups in the total amount of copolymer (X) and polyepoxy compound (Y) is 0.10 × 10⁻⁶. -4 It is preferable that the concentration be mol / g or higher, and 0.50 × 10 -4 It is more preferable that the concentration be mol / g or higher, and 1.0 × 10⁻⁶ -4 It is even more preferable that the concentration be mol / g or higher. This is because it can suppress the aggregation of the copolymer (X) during and after polymerization and during storage of the aqueous resin emulsion (α).

[0099] The content of carboxyl groups in the total amount of copolymer (X) and polyepoxy compound (Y) is 10 × 10 -4 It is preferable that the amount is mol / g or less, and 5.0 × 10 -4 It is more preferable that the concentration is mol / g or less. 3.0 × 10 -4 It may be less than mol / g, or 2.5 × 10 -4 mol / g or less, or 2.0 × 10⁻⁶ -4 It may be less than mol / g.

[0100] [Carboxylate group content in the non-volatile content of aqueous resin emulsion (α)] The carboxyl group content in the nonvolatile components of aqueous resin emulsion (α) is 0.10 × 10⁻⁶. -4 It is preferable that the concentration be mol / g or higher, and 0.50 × 10 -4 It is more preferable that the concentration be mol / g or higher, and 1.0 × 10⁻⁶ -4 It is even more preferable that the concentration be mol / g or higher. This is because it can suppress the aggregation of the copolymer (X) during and after polymerization and during storage of the aqueous resin emulsion (α).

[0101] The carboxyl group content in the nonvolatile components of aqueous resin emulsion (α) is 10 × 10 -4 It is preferable that the amount is mol / g or less, and 5.0 × 10 -4 It is more preferable that the concentration is mol / g or less. 3.0 × 10 -4 It may be less than mol / g, or 2.5 × 10 -4 mol / g or less, or 2.0 × 10⁻⁶ -4 It may be less than mol / g.

[0102] Here, the carboxyl group mentioned above refers not only to -COOH but also to cations other than hydrogen ions and -COOH -This also includes structures in which and are bonded. The carboxyl group content in the nonvolatile content of aqueous resin emulsion (α) is determined by subtracting the decrease in the amount of functional groups that react with carboxyl groups in the raw materials before and after polymerization from the carboxyl group content in the raw materials, as shown in the formula below. The raw materials refer to the components used in the synthesis of aqueous resin emulsion (α). Furthermore, in this invention, the functional group that reacts with carboxyl groups is the epoxy group, and the hydroxyl group is not considered a functional group that reacts with carboxyl groups.

[0103] The following is the content of carboxyl groups in the nonvolatile matter of aqueous resin emulsion (α) R CX The method for determining [mol / g] is explained in detail. Let N3 [mol / g] be the total amount of carboxyl groups in the raw materials (including initiators, solvents, and other additives), let N2 [mol / g] be the total amount of epoxy groups in the raw materials (including initiators, solvents, and other additives), and let N1 [mol / g] be the amount of epoxy groups contained in 1 g of aqueous resin emulsion (α). The non-volatile content concentration of aqueous resin emulsion (α) is C S Let it be expressed as [mass%]. At this time, the carboxyl group content R CX This is expressed as shown in equation (3). The methods for determining N1 and N2 will be described later in the examples. N2 can be obtained by calculation. R CX [mol / g] = {N3 - (N2 - N1)} / (C S / 100) ... (3)

[0104] [1-2. Hardener (β)] The curing agent (β) contains an aromatic polyamine (F) having active hydrogen that is reactive to the epoxy group. Here, the active hydrogen that is reactive to the epoxy group refers to a hydrogen atom that can be removed from the nitrogen atom after the amino group of the aromatic polyamine (F) has nucleophilically attacked the epoxy group to form a bond.

[0105] The amino group of the aromatic polyamine (F) is preferably one selected from the group consisting of an unsubstituted amino group (-NH2 (no substituent)) or an amino group with only one substituent (-NHR (R is a substituent)). The aromatic polyamine (F) having active hydrogen described above has a benzene ring and two or more amino groups in one molecule. The aromatic polyamine (F) having active hydrogen may be a compound having only one type of amino group, or a compound having two or more types of amino groups. The curing agent (β) may contain only one type of aromatic polyamine (F) having the above-mentioned active hydrogen, or it may contain two or more types.

[0106] Examples of the aromatic polyamine (F) having the above-mentioned active hydrogen include m-xylylenediamine (hereinafter sometimes referred to as "MXDA"), diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone, and modified versions thereof. The modified version is preferably a compound obtained by an addition reaction in which an atom or group of atoms is bonded to the amino group of MXDA.

[0107] In this embodiment, since the curing agent (β) contains the above-mentioned aromatic polyamine (F) having active hydrogen, the aqueous resin composition hardens with short curing time at room temperature and forms a coating film with excellent initial water resistance and moist heat adhesion to metal materials. Therefore, the aqueous resin composition of this embodiment can be suitably used for corrosion protection coating of metal products such as iron. Although the reason for this effect is not entirely clear, the curing agent (β) containing the aromatic polyamine (F) having the active hydrogen can easily penetrate into the particles of the aqueous resin emulsion (α). This is thought to be due to the curing-accelerating function of the curing agent (β) on the polyepoxy compound (Y) contained in the aqueous resin emulsion (α), resulting in the aqueous resin composition curing in a short time.

[0108] Generally, when comparing aromatic compounds and aliphatic compounds of similar molecular weight, aromatic compounds are more hydrophobic. The aromatic polyamine (F) containing the active hydrogen contained in the curing agent (β) is presumed to be more hydrophobic than the aqueous resin emulsion (α). Therefore, it is considered that the aromatic polyamine (F) containing the active hydrogen does not easily remain in the aqueous layer of the aqueous resin composition and is easily distributed into the interior of the particles of the aqueous resin emulsion (α). As a result, the aromatic polyamine (F) containing the active hydrogen penetrates into the interior of the particles of the aqueous resin emulsion (α) more easily than, for example, an aliphatic polyamine of similar molecular weight, and approaches the epoxy groups of the aqueous resin emulsion (α). Consequently, it is considered that the aqueous resin composition of this embodiment containing the aromatic polyamine (F) containing the active hydrogen accelerates the curing of the polyepoxy compound (Y) contained in the aqueous resin emulsion (α) and speeds up the curing of the aqueous resin composition compared to the case containing an aliphatic polyamine of similar molecular weight.

[0109] As for the aromatic polyamine (F) having the active hydrogen described above, it is preferable to include aromatic polyamines (F) having two or more benzene rings in one molecule, and more preferably aromatic polyamines (F) having three or more benzene rings in one molecule, from the viewpoint of facilitating the curing reaction of the aqueous resin composition. The reason for this effect is not entirely clear, but aromatic polyamines (F) having two or more benzene rings in one molecule are more hydrophobic than aromatic polyamines (F) having only one benzene ring in one molecule. Therefore, aromatic polyamines (F) having two or more benzene rings in one molecule can penetrate more easily into the interior of the particles of the aqueous resin emulsion (α), and can approach the epoxy groups of the polyepoxy compound (Y) contained in the aqueous resin emulsion (α) more easily than aromatic polyamines (F) having only one benzene ring in one molecule. As a result, it is presumed that the curing-accelerating function of the curing agent (β) on the polyepoxy compound (Y) is obtained more effectively, and the curing speed of the aqueous resin composition is increased.

[0110] As for the aromatic polyamine (F) having the active hydrogen described above, from the viewpoint of water solubility and availability, it is preferable that the aromatic polyamine (F) contains 13 or fewer benzene rings in one molecule, and more preferably that it contains 10 or fewer benzene rings.

[0111] Examples of aromatic polyamines (F) having two or more benzene rings in one molecule include compounds represented by the following general formula (1-1) and compounds represented by the following general formula (1-2).

[0112] [ka] (In formula (1-1), A 2 , A 3 Each of these independently represents a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group. n represents an integer from 1 to 12.

[0113] [ka] (In formula (1-2), A 1 (This represents a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group.)

[0114] A in equation (1-1) 2 , A 3 , and A in equation (1-2) 1 In formula (1-1), A represents a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group. 2 , A 3 , and A in equation (1-2) 1 In all cases, the curing reaction of the aqueous resin composition proceeds more easily, so a 1,3-phenylene group is preferred.

[0115] In the compound represented by formula (1-1), A is included in the repeating unit. 2 (A written in parentheses) 2) and A not included in the repeating unit 3 (A written outside the parentheses) 3 ) may be the same or different. Also, in the compound represented by formula (1-1), when n is 2 to 12, the A included in the repeating unit 2 These may all be the same, or they may contain different ones. The compound represented by formula (1-1) can be easily manufactured, so the A contained in the compound 2 , A 3 It is preferable that they are all the same.

[0116] In formula (1-1), n, which is the number of repeating units indicated in parentheses, represents an integer from 1 to 12. As the aromatic polyamine (F) having active hydrogen, multiple types of compounds with different numbers of repeating units (number of n) in formula (1-1) may be used. The number of n in formula (1-1) is preferably 2 or more from the viewpoint of allowing the curing reaction of the aqueous resin composition to proceed more easily. Furthermore, the number of n in formula (1-1) is preferably 9 or less in order to ensure good water solubility and availability of the aromatic polyamine (F) having active hydrogen.

[0117] From the viewpoint of obtaining an aqueous resin composition that can form a coating film with superior initial water resistance, the content of the compound in general formula (1-1) where n is 1 is preferably 10% to 35% by mass, more preferably 15% to 30% by mass, and even more preferably 18% to 25% by mass.

[0118] The compound represented by general formula (1-1) has higher hydrophobicity compared to the compound represented by general formula (1-2). Therefore, the compound represented by general formula (1-1) can more easily approach the epoxy groups of the polyepoxy compound (Y) contained in the aqueous resin emulsion (α). Thus, when the aromatic polyamine (F) having the active hydrogen mentioned above contains the compound represented by general formula (1-1), an aqueous resin composition is formed that can create a coating film with superior initial water resistance.

[0119] The aromatic polyamine (F) having active hydrogen is more preferably composed of the compound represented by general formula (1-1) and MXDA. In this case, an aqueous resin composition is formed that can form a coating film with superior initial water resistance. This is presumed to be due to the synergistic effect of the high hydrophobicity of the compound represented by general formula (1-1) and the low steric hindrance of MXDA. That is, it is presumed that this synergistic effect makes it easier for the aromatic polyamine (F) having active hydrogen to approach the epoxy groups contained in the aqueous resin emulsion (α), further accelerating the curing of the polyepoxy compound (Y) contained in the aqueous resin emulsion (α), and thus increasing the curing speed of the aqueous resin composition. Furthermore, when the aromatic polyamine (F) having active hydrogen contains the compound represented by general formula (1-1) and MXDA, the curing of the aqueous resin composition is accelerated due to the synergistic effect, thus forming a cured product with higher film yield strength.

[0120] When the above-mentioned aromatic polyamine (F) having active hydrogen contains the compound represented by general formula (1-1) and MXDA, the content of MXDA in the above-mentioned aromatic polyamine (F) having active hydrogen is preferably 10% to 40% by mass, more preferably 20% to 30% by mass, and even more preferably 24% to 28% by mass. Furthermore, the content of the compound represented by general formula (1-1) in the above-mentioned aromatic polyamine (F) having active hydrogen is preferably 60% to 90% by mass, more preferably 70% to 80% by mass, and even more preferably 72% to 76% by mass. This is because the synergistic effect of including the compound represented by general formula (1-1) and MXDA becomes more pronounced.

[0121] The content of the compound in which the number of n in general formula (1-1) is 1 is preferably 10% to 35% by mass, more preferably 15% to 30% by mass, and even more preferably 18% to 25% by mass, relative to the total amount of the aromatic polyamine (F) having active hydrogen.

[0122] As the aromatic polyamine (F) having the active hydrogen described above, a commercially available product may be used. Examples of commercially available products containing aromatic polyamine (F) having two or more benzene rings in one molecule include Gaskamine 328 (trade name, Mitsubishi Gas Chemical Company, Inc.) and Gaskamine 240 (trade name, Mitsubishi Gas Chemical Company, Inc.). Both Gaskamine 328 and Gaskamine 240 are mixtures containing a modified MXDA and MXDA. Gaskamine 328 contains a compound represented by general formula (1-1) as a modified MXDA. Gaskamine 240 contains a compound represented by general formula (1-2) as a modified MXDA.

[0123] More specifically, Gaskamine 328 contains the compound represented by formula (1-1), which is an aromatic polyamine consisting of the reaction product of epichlorohydrin and MXDA, and MXDA. Specifically, Gaskamine 328 contains the compound represented by formula (1-1) (A in formula (1-1) 2 and A 3 All of these are 1,3-phenylene groups. n is 1 to 12. It contains 73.3% by mass of (1-1). The content of the compound with n = 1 in the compound represented by formula (1-1) contained in Gaskamine 328 is 20.9% by mass. In addition, Gaskamine 328 contains 26.7% by mass of MXDA.

[0124] Gaskamine 240 contains a compound represented by formula (1-2), which is an aromatic polyamine consisting of a reaction product of styrene and MXDA, and MXDA. Specifically, Gaskamine 240 contains the compound represented by formula (1-2) (wherein formula (1-2), A 1 It contains 99% or more of the 1,3-phenylene group. In addition, Gaskamine 240 contains less than 1% by mass of MXDA. Furthermore, the individual components of the curing agent (β) contained in the aqueous resin composition and their respective content can be confirmed using chromatographic analysis such as gas chromatography (GC) analysis and gel filtration chromatography (GPC) analysis.

[0125] The amount of the aromatic polyamine (F) containing the above-mentioned active hydrogen in the curing agent (β) is preferably 0.10 equivalents or more, more preferably 0.20 equivalents or more, and more preferably 0.30 equivalents or more, of the active hydrogen contained in the aromatic polyamine (F) per equivalent of epoxy groups contained in the aqueous resin emulsion (α). This is because the crosslinking density of the aqueous resin composition after curing increases, improving the initial water resistance and film yield strength, and the reaction rate of the epoxy groups contained in the aqueous resin emulsion (α) increases, improving the moist heat adhesion to the metal material.

[0126] The amount of aromatic polyamine (F) containing the above-mentioned active hydrogen in the curing agent (β) is preferably 1.50 equivalents or less, more preferably 1.3 equivalents or less, and more preferably 1.2 equivalents or less, of the amount of active hydrogen contained in aromatic polyamine (F) per equivalent of epoxy groups contained in aqueous resin emulsion (α). This is because it is possible to suppress excessive curing shrinkage of the aqueous resin composition and to form a cured product with good moist heat adhesion to metal materials.

[0127] [1-3. Curing accelerator (γ)] The curing accelerator (γ) has the function of accelerating the curing of the aqueous resin composition and forming a film with high film yield strength. The curing accelerator (γ) contains a tertiary amine that does not have active hydrogen that is reactive to epoxy groups. The tertiary amine in this embodiment is NR 1 R 2 R 3 (In the formula, R 1 R 2 R 3 These are substituents, and they may be different from each other, or two or more of them may be the same. 1 R 2 R 3 These may be bonded to each other to form a ring. ) This is a compound represented by ).

[0128] The curing accelerator (γ) is a tertiary aliphatic amine, a tertiary alicyclic amine, a tertiary heteroaromatic amine, or a tertiary amine (NR 1 R 2 R3 It is preferably at least one compound selected from the group consisting of tertiary aromatic amines having a phenyl group not directly bonded to the nitrogen atom of (). This is to enhance the nucleophilicity of the curing accelerator (γ) and promote the curing reaction efficiently.

[0129] Examples of the tertiary aliphatic amine include triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, tri-sec-butylamine, tri-n-hexylamine, and the like.

[0130] Examples of the tertiary alicyclic amine include 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,5-diazabicyclo[4.3.0]nona-5-ene, 1,8-diazabicyclo[5.4.0]undeca-7-ene, and the like.

[0131] As the tertiary heteroaromatic amine, it is preferable to use a compound having an imidazole skeleton. Specifically, examples include imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, and the like.

[0132] Tertiary aromatic amines having a phenyl group not directly bonded to the nitrogen atom of the tertiary amine (NR 1 R 2 R 3 ) include dimethylbenzylamine, diethylbenzylamine, tribenzylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 2-phenylimidazole, and the like.

[0133] Among these curing accelerators (γ), it is particularly preferable to use the compounds of the following (i) and / or (ii). (i) A tertiary alicyclic amine having no active hydrogen with respect to the epoxy group and having a saturated ring structure in which two nitrogen atoms are bonded by three substituents of the amino group. (ii) A tertiary heteroaromatic amine having no active hydrogen with respect to the epoxy group and having a heteroaromatic ring structure containing two or more nitrogen atoms.

[0134] (i) Examples of tertiary alicyclic amines include 1,4-diazabicyclo[2.2.2]octane (DABCO). (ii) Examples of tertiary heteroaromatic amines include imidazoles. The curing accelerator (γ) may be used individually or in combination of two or more types.

[0135] The content of the curing accelerator (γ) is 0.0070 mol or more, preferably 0.070 mol or more, more preferably 0.18 mol or more, and even more preferably 0.30 mol or more, relative to one equivalent of epoxy groups contained in the aqueous resin emulsion (α). This is because the film formed from the cured product of the aqueous resin composition of this embodiment has a high film yield strength.

[0136] The content of the curing accelerator (γ) is 1.5 mol or less, preferably 1.0 mol or less, more preferably 0.70 mol or less, even more preferably 0.44 mol or less, even more preferably 0.40 mol or less, and particularly preferably 0.38 mol or less, relative to one equivalent of epoxy groups contained in the aqueous resin emulsion (α). This is because the cured product of the aqueous resin composition of this embodiment forms a coating film with good moist heat adhesion to metal materials. Furthermore, when the content of the curing accelerator (γ) is 1.5 mol or less, gelation of the aqueous resin composition in a short time can be suppressed, and a cured product with good rust prevention properties can be obtained.

[0137] [1-4. Other ingredients] The aqueous resin composition according to this embodiment may contain a pigment. Examples of pigments include titanium dioxide, talc, barium sulfate, carbon black, red iron oxide, calcium carbonate, silicon dioxide, talc, mica, kaolin, clay, ferrite, and silica sand. The pigment may contain only one compound or two or more compounds. The pigment is preferably present in the aqueous resin composition at an amount of 0.1 to 50% by mass, and more preferably at an amount of 1 to 40% by mass, in order to improve the opacity of the coating film.

[0138] The aqueous resin composition may contain additives such as fillers, organic or inorganic hollow balloons, dispersants (e.g., amino alcohols, polycarboxylates, etc.), surfactants, coupling agents (e.g., silane coupling agents, etc.), defoaming agents, preservatives (e.g., biocides, fungicides, antifungal agents, algicides, and combinations thereof), flowing agents, leveling agents, and neutralizing agents (e.g., hydroxides, amines, ammonia, carbonates, etc.).

[0139] As the coupling agent, it is preferable to use a silane coupling agent. Examples of silane coupling agents include epoxysilane compounds. Specific examples include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 2-(3,4-epoxycyclohexy)ethyltrimethoxysilane.

[0140] The amount of silane coupling agent added is preferably 0.1 to 5 parts by mass, and more preferably 0.3 to 3 parts by mass, per 100 parts by mass of aqueous resin emulsion. This is because it improves the rust prevention properties and adhesion to metal materials of the cured aqueous resin composition.

[0141] <Method for producing aqueous resin compositions> The aqueous resin composition of this embodiment can be produced by mixing an aqueous resin emulsion (α), a curing agent (β), a curing accelerator (γ), and other components as needed. Known methods can be used to mix each component contained in the aqueous resin composition of this embodiment.

[0142] The aqueous resin composition of this embodiment comprises an aqueous resin emulsion (α), a curing agent (β), and a curing accelerator (γ). As a result, a coating film is obtained that hardens with short curing time at room temperature and exhibits good initial water resistance and moist heat adhesion to metal materials.

[0143] <coating film> The coating film of this embodiment consists of a cured product of the aqueous resin composition of this embodiment. The coating film of this embodiment may, if necessary, be laminated with a coating film consisting of an undercoat layer provided below and / or a topcoat layer provided above the coating film, which is made of a cured product of the aqueous resin composition of the present invention.

[0144] <Method for manufacturing coating film> Next, a method for producing a coating film made from a cured aqueous resin composition of this embodiment will be described in detail. In the method for manufacturing the coating film of this embodiment, first, an aqueous resin emulsion (α), a curing agent (β), a curing accelerator (γ), and other components as needed are mixed. This prepares the aqueous resin composition of this embodiment (mixing step). Next, the aqueous resin composition obtained in the mixing step is applied to the surface to be coated (coating step).

[0145] In the mixing step, the aqueous resin emulsion (α), curing agent (β), curing accelerator (γ), and other components as needed are mixed and stirred by a known method. This yields an aqueous resin composition in which each component is dispersed. The stirring in the mixing step can be performed, for example, by a robotics machine (manufactured by Primix Corporation). In order to sufficiently disperse each component contained in the aqueous resin composition of this embodiment, it is preferable to stir in the mixing step for 5 minutes or more. Furthermore, in order to suppress the hardening of the resin components contained in the aqueous resin composition, it is preferable to limit the stirring time to within 1 hour.

[0146] In the coating process, an aqueous resin composition is applied to the surface of the object to be coated. Examples of materials forming the surface to be coated include metal materials such as iron. The surface to be coated may have been pre-treated with a primer, undercoat, or other surface treatment. Methods for applying the aqueous resin composition can be known, including, but are not limited to, methods using brushes, rollers, etc. Furthermore, in order to prevent the resin components contained in the aqueous resin composition from hardening before the application process is completed, the application process is preferably completed within one hour after the completion of the mixing process, and more preferably within 30 minutes.

[0147] In the method for manufacturing the coating film of this embodiment, it is preferable to perform a curing step after the coating step to harden the coating film obtained by applying it to the surface to be coated. In the curing process, the resin components contained in the aqueous resin composition are cured by drying and curing the coated surface of the object to be coated with the aqueous resin composition. The curing time varies depending on the temperature of the curing atmosphere. For example, it is preferable to cure for 5 hours or more at room temperature (20°C), 1 hour or more at 40°C, and 5 minutes or more at 60°C.

[0148] The coating film of this embodiment consists of a cured product of the aqueous resin composition of this embodiment. Therefore, it has good initial water resistance and good wet-heat adhesion to metal materials. Furthermore, in the method for manufacturing the coating film of this embodiment, an aqueous resin composition is prepared by mixing an aqueous resin emulsion (α), a curing agent (β), and a curing accelerator (γ), and this is applied to the surface to be coated. Therefore, the coating film of this embodiment, which consists of the cured product of the aqueous resin composition of this embodiment, can be formed.

[0149] <Water-based resin composition set> Next, the aqueous resin composition set of this embodiment will be described in detail. The aqueous resin composition set of this embodiment is such that the components of the aqueous resin composition of this embodiment are stored separately as a first liquid and a second liquid. The first liquid in the aqueous resin composition set of this embodiment contains an aqueous resin emulsion (α). The second liquid contains a curing agent (β) and a curing accelerator (γ).

[0150] The coating film of this embodiment may be manufactured using the aqueous resin composition set of this embodiment. That is, the aqueous resin composition of this embodiment is prepared by mixing the first liquid and the second liquid in the aqueous resin composition set of this embodiment (mixing step). Then, the aqueous resin composition is applied to the surface to be coated in the same manner as the coating film manufacturing method described above (coating step).

[0151] The aqueous resin composition set of this embodiment is stored separately as a first liquid containing an aqueous resin emulsion (α) and a second liquid containing a curing agent (β) and a curing accelerator (γ). Therefore, the aqueous resin composition set of this embodiment has excellent storage stability because the resin components contained in the aqueous resin emulsion (α) do not react with the curing agent (β) and harden during storage. The first liquid and the second liquid may be stored in separate containers. The shape and material of the containers can be arbitrarily selected. The container containing the first liquid and the container containing the second liquid may be separated from each other or in contact with each other. Furthermore, by using the aqueous resin composition set of this embodiment, a coating film with good initial water resistance and moist heat adhesion to metal materials can be obtained, similar to the case when using the aqueous resin composition of this embodiment.

[0152] <Application Fields> The aqueous resin composition of the present invention is useful in a variety of fields. In particular, the aqueous resin composition of the present invention is suitable for use as an anticorrosive coating applied to the surface of metal products used outdoors, such as steel towers, bridges, ships, and port facilities. The articles on which a coating film made of the cured product of the aqueous resin composition of the present invention is formed, that is, the objects to be coated with the aqueous resin composition of the present invention, can be arbitrarily selected. Specifically, examples of objects to be coated include metal products used outdoors such as steel towers, bridges, ships, and port facilities; various household goods; home appliances such as refrigerators; playground equipment installed in amusement parks and parks; sports equipment; buildings (interiors, exteriors, etc.); various industrial goods and their parts, including transportation machinery and machine tools; automobile bodies and chassis; railway vehicle bodies and undercarriage equipment; ships; shipping containers; and aircraft. [Examples]

[0153] The present invention will be described in detail below using examples. Note that the following examples do not limit the entirety of the present invention, and any implementations carried out without departing from the scope of this description are included within the technical scope of the present invention.

[0154] <1. Synthesis of aqueous resin emulsion (α)> (Water-based resin emulsion (α-1)) 158 parts of deionized water were placed in a separable flask equipped with a condenser, thermometer, stirrer, and dropping funnel, and the temperature was raised to 60°C. Nitrogen gas was blown into the contents of the separable flask to deoxygenate them. An emulsion consisting of methyl methacrylate, 2-ethylhexyl acrylate, methacrylic acid, hydrogenated bisphenol A epoxy, sodium dodecylbenzenesulfonate as an emulsifier, and 356 parts by mass of deionized water in the amounts (parts by mass) shown in Table 1 was added dropwise over 3 hours. Simultaneously with the emulsion, 1.2 parts by mass of potassium persulfate dissolved in 41 parts by mass of deionized water as an oxidizing agent and 0.4 parts by mass of sodium bisulfite dissolved in 21 parts by mass of deionized water as a reducing agent were added dropwise over 3.3 hours at 60°C to polymerize. After the dropwise addition was complete, the mixture was aged for 1.5 hours. Then, it was cooled, and 0.8 parts by mass of aqueous ammonia as a basic substance was added to obtain aqueous resin emulsion (α-1).

[0155] Table 1 shows the amount (parts by mass) of each material used in the synthesis of aqueous resin emulsion (α-1). The value for "Ion-exchanged water" in Table 1 indicates the amount of ion-exchanged water contained in the synthesized aqueous resin emulsion (α-1). In addition, the numbers in parentheses in the content percentages of copolymer (X) and polyepoxy compound (Y) in Table 1 indicate the ratio (mass%) of each material to the total amount (100%) of copolymer (X) and polyepoxy compound (Y).

[0156] [Table 1]

[0157] The following polyepoxy compounds (Y) were used as shown in Table 1. Hydrogenated bisphenol A epoxy (epoxy equivalent 215 g / mol; manufactured by Kyoei Chemical Co., Ltd.; Epolite 4000) Bisphenol A type epoxy (epoxy equivalent 190 g / mol; manufactured by Mitsubishi Chemical Corporation; JER828) 1,6-Hexanediol diglycidyl ether (epoxy equivalent 160 g / mol; manufactured by Kyoei Chemical Co., Ltd.; Epolite 1600)

[0158] (Water-based resin emulsion (α-2)~(α-6)) Aqueous resin emulsions (α-2) to (α-6) were synthesized in the same manner as aqueous resin emulsion (α-1), except that each material shown in Table 1 was used in the amounts (parts by mass) shown in Table 1. For aqueous resin emulsions (α-2) to (α-6), the "exchanged ion water" values ​​shown in Table 1 indicate the amount of exchanged ion water contained in the synthesized aqueous resin emulsions (α-2) to (α-6), similar to the synthesized aqueous resin emulsion (α-1).

[0159] <2. Evaluation of water-based resin emulsion (α)> The following items were evaluated for each of the aqueous resin emulsions (α-1) to (α-6). The results are shown in Table 2. Note that aqueous resin emulsion (α-6), which has an excessive content of polyepoxy compound (Y), was not evaluated because it aggregated during synthesis. In the following explanation, when referring to aqueous resin emulsions (α-1) to (α-6) collectively, it may be written as aqueous resin emulsion (α).

[0160] <2-1. Non-volatile content concentration> 1 g of aqueous resin emulsion (α) was weighed onto a 5 cm diameter aluminum dish and dried at atmospheric pressure in a drying oven at 105°C for 1 hour while circulating air. The mass of the residue obtained after drying was measured, and the ratio (mass %) of the mass after drying to the mass of aqueous resin emulsion (α) before drying was determined.

[0161] <2-2. Percentage of epoxy groups remaining> The residual epoxy group rate of aqueous resin emulsion (α) is the ratio of the amount of epoxy groups N1 [mol / g] contained in the synthesized aqueous resin emulsion (α) to the total amount of epoxy groups N2 [mol / g] contained in the components used in the synthesis of aqueous resin emulsion (α) (including raw materials, initiators, solvents, and other additives).

[0162] The amount of epoxy groups N1 [mol / g] in the synthesized aqueous resin emulsion (α) was measured by the following method. An excess amount of hydrogen chloride was added to the total amount of epoxy groups contained in the components (raw materials) used in the synthesis of aqueous resin emulsion (α) and reacted with the epoxy groups. Next, the amount of unreacted hydrogen chloride was titrated with potassium hydroxide to confirm the amount of remaining hydrogen chloride. At this time, potassium hydroxide is consumed by the reaction with acidic components, including carboxylic acids, contained in aqueous resin emulsion (α). Therefore, the amount of acidic components was titrated in advance by a blank measurement without using hydrogen chloride, and the results of this measurement were corrected. The specific measurement procedure is as follows (i) to (ii).

[0163] (i) Blank measurement (confirmation of acidic component content) A 1g (5g in this example and comparative example) of aqueous resin emulsion (α) was weighed into a 100mL Erlenmeyer flask, 25g of tetrahydrofuran (THF) was added, and the mixture was stirred with a magnetic stirrer to obtain a homogeneous solution. 0.15mL of 0.1% by mass aqueous cresol red was added to this solution as an indicator. The solution was titrated with a 0.1M potassium hydroxide / ethanol solution while stirring. The equivalence point was defined as the point at which the purple color persisted for 30 seconds after the addition of the potassium hydroxide / ethanol solution. The amount of potassium hydroxide / ethanol solution used in the titration was V. KOH1 Let it be [mL].

[0164] (ii) Main measurement A 2g (5g in this example and comparative example) of aqueous resin emulsion (α) was weighed into a 100mL Erlenmeyer flask, 25g of THF was added, and the mixture was stirred with a magnetic stirrer to dissolve it. A 0.2M hydrogen chloride / dioxane solution was added to this mixture and stirred for 1 hour to obtain a homogeneous solution. The amount of hydrogen chloride / dioxane solution added here was V HCl[mL] (25 mL in this Example and Comparative Example). 0.15 mL of an aqueous solution of 0.1% by mass cresol red was added to this solution as an indicator. The solution was titrated with a 0.1 M potassium hydroxide / ethanol solution while stirring. The point at which the purple color persisted for 30 seconds after the addition of the potassium hydroxide / ethanol solution was taken as the equivalence point. Here, let the amount of the potassium hydroxide / ethanol solution used in the titration be V KOH2 [mL].

[0165] From each of the numerical values obtained in (i) and (ii), the amount of epoxy groups N1 [mol / g] per 1 g of the aqueous resin emulsion (α) was calculated by the following formula (4). N1 = (0.2 × V HCl / 1000 - 0.1 × V KOH2 / 1000) / W2 + (0.1 × V KOH1 / 1000) / W1…(4)

[0166] The total amount of epoxy groups N2 [mol / g] contained in the components (raw materials) used in the synthesis of the aqueous resin emulsion (α) is the mass m of each component i [parts by mass] (i = 1, 2, 3, ···) and the epoxy equivalent EP i [g / mol], and is obtained by the following formula (5). Here, the components used in the synthesis of the aqueous resin emulsion (α) mean all the components described as raw materials of the aqueous resin emulsion (α) in Table 1. N2 = Σ(m i / EP i ) / Σm i …(5)

[0167] For compounds that do not contain epoxy groups such as methyl methacrylate and ion-exchanged water, 1 / EP i = 0. From the amount of epoxy groups thus obtained, the residual ratio of the epoxy groups in the aqueous resin emulsion (α) is represented by 100 × N1 / N2 [mol%].

[0168] <2-3. Content of epoxy groups in non-volatile matter, content of epoxy groups in components (X) + (Y)> The non-volatile content concentration C, determined by the method described above, S [Mass %], the epoxy group content N1 in aqueous resin emulsion (α), the total amount of epoxy groups in the raw materials N2, and the epoxy group content R in the non-volatile components of aqueous resin emulsion (α) EP The [mol / g] value was calculated based on equation (2) explained above. R EP =N1 / (C S / 100) ... (2)

[0169] Furthermore, using the epoxy group content N1 in the aqueous resin emulsion (α) obtained by the above method, the total mass α [g] of all components (raw materials) used in the synthesis of the aqueous resin emulsion (α), the mass X [g] of the raw materials used in the copolymer (X), and the mass Y [g] of the raw materials used in the polyepoxy compound (Y), the epoxy group content R in component (X) + (Y) is calculated based on the following formula. EP The [mol / g] value was calculated. R in (X)+(Y) EP =N1 / {(X+Y) / α}

[0170] <2-4. Carboxylate group content in non-volatile matter, carboxylate group content in component (X) + (Y)> The total amount of carboxyl groups N3 [mol / g] contained in the components (raw materials) used in the synthesis of aqueous resin emulsion (α) is equal to the mass m of each component. i [Mass part] (i=1,2,3,···) and carboxyl equivalent CX i [g / mol] can be calculated using the following formula (6). Here, the components used in the synthesis of aqueous resin emulsion (α) refer to all the components listed in Table 1 as raw materials for aqueous resin emulsion (α). N3 = Σ(m i / CX i ) / Σm i …(6) From the N3 obtained here, the carboxyl group content R in the nonvolatile matter of the aqueous resin emulsion (α) is calculated. CX The [mol / g] value was calculated based on equation (3) explained above. R CX ={N3-(N2-N1)} / (CS / 100) ... (3)

[0171] Furthermore, using the epoxy group content N1 in the aqueous resin emulsion (α) obtained by the above method, the total amount of epoxy groups in the raw materials N2, the total amount of carboxyl groups N3 contained in the components (raw materials) used in the synthesis of the aqueous resin emulsion (α), the total mass α [g] of all components (raw materials) used in the synthesis of the aqueous resin emulsion (α), the mass X [g] of the raw materials used for copolymer (X), and the mass Y [g] of the raw materials used for polyepoxy compound (Y), the carboxyl group content R in component (X) + (Y) is calculated based on the following formula. CX The [mol / g] value was calculated. R in (X)+(Y) CX ={N3-(N2-N1)} / {(X+Y) / α}

[0172] <2-5. pH> The pH at 23°C was measured using a pH meter (HM-30G glass electrode type hydrogen ion concentration indicator manufactured by Toa DKK Co., Ltd.).

[0173] <2-6. Viscosity> The viscosity of aqueous resin emulsion (α) was measured under the following conditions and with the following equipment. Temperature: 23℃ Measuring equipment: B type viscometer Rotor: No.1 Rotation speed: 60 rpm

[0174] <2-7. Glass Transition Temperature> The glass transition temperature Tg of copolymer (X) is the value calculated by the above equation (1).

[0175] <2-8.Dispersibility> The state of the aqueous resin emulsion (α) immediately after synthesis was visually observed and evaluated according to the following criteria. ○ (Acceptable): No aggregation, precipitation, separation, or gelation was observed. × (Unacceptable): At least one of the following was observed: aggregation, precipitation, separation, and gelation.

[0176] <2-9. High temperature stability> The high-temperature stability of aqueous resin emulsion (α) was evaluated as follows. First, aqueous resin emulsion (α) was placed in a 70 ml glass bottle, sealed tightly, and left to stand at 60°C for 7 days. After that, the state of aqueous resin emulsion (α) in the glass bottle was observed visually and evaluated according to the following criteria. ○ (Acceptable): No aggregation, thickening, precipitation, separation, or gelation was observed. × (Unacceptable): At least one of the following was observed: aggregation, thickening, precipitation, separation, and gelation.

[0177] [Table 2]

[0178] <2-10. Evaluation Results> As shown in Table 2, aqueous resin emulsions (α-1) to (α-5) all exhibited good dispersibility and high-temperature stability. In contrast, aqueous resin emulsion (α-6), which had an excessive content of polyepoxy compound (Y), exhibited insufficient dispersibility. From these findings, it was found that aqueous resin emulsions (α) in which the amount of (meth)acrylic acid ester (A) added is 20-98% by mass, the amount of ethylenically unsaturated carboxylic acid (B) added is 0.1-10% by mass, and the amount of polyepoxy compound (Y) added is 1-40% by mass, relative to the total amount of raw materials (monomers) used in copolymer (X) and polyepoxy compound (Y), exhibit excellent dispersibility and high-temperature stability.

[0179] <3. Examples 1-10 and Comparative Examples 1-15 (Preparation of Aqueous Resin Compositions)> To 100 parts by mass of the aqueous resin emulsion (α) shown in Tables 3 to 5 (with a non-volatile content of 40% by mass), 60 parts by mass of deionized water and the curing agent (β) and curing accelerator (γ) shown in Tables 3 to 5 were added in the amounts (parts by mass) shown in Tables 3 to 5 and stirred for 10 minutes to prepare the aqueous resin compositions of Examples 1 to 10 and Comparative Examples 1 to 15.

[0180] In Tables 3 to 5, the "active hydrogen equivalent to epoxy group" for each curing agent (β) represents the equivalent amount of active hydrogen contained in the aromatic polyamine (F) containing active hydrogen in curing agent (β) relative to one equivalent of epoxy group contained in the aqueous resin emulsion (α). The "number of moles per epoxy group" for the curing accelerator (γ) is a numerical value that indicates the number of moles of the curing accelerator (γ) per equivalent of epoxy groups contained in the aqueous resin emulsion (α). In Table 3, "MXDA content [mass%]" refers to the MXDA content in the aromatic polyamine (F) containing active hydrogen, which is included in the curing agent (β).

[0181] As shown in Tables 3 to 5, Gaskamine 328 (Mitsubishi Gas Chemical Company, Inc.) or m-xylylenediamine (MXDA) (Mitsubishi Gas Chemical Company, Inc.) were used as aromatic polyamines (F). The equivalent amount of active hydrogen contained in MXDA is 34 g / mol. The equivalent amount of active hydrogen contained in Gaskamine 328 is 55 g / mol. Gaskamine 328 is a mixture containing a modified form of MXDA and MXDA. Gaskamine 328 contains 73.3% by mass of the compound represented by general formula (1-1), which is a modified form of MXDA. Gaskamine 328 contains 26.7% by mass of MXDA.

[0182] As shown in Tables 3 to 5, the aliphatic polyamines used were EH-8051 (trade name: ADEKA Hardener EH-8051, manufactured by ADEKA Corporation) or ED-600 (trade name: JEFFAMINE ED-600, manufactured by Huntsman Japan Co., Ltd.). The equivalent amount of active hydrogen contained in Adeka Hardener EH-8051 is 180 g / mol. The equivalent amount of active hydrogen contained in JEFFAMINE ED-600 is 132 g / mol.

[0183] [Table 3]

[0184]

Table 4

[0185]

Table 5

[0186] <4. Evaluation of coating films and films> Using the aqueous resin compositions of Examples 1 to 10 and Comparative Examples 1 to 15 respectively, coating films and films were formed by the methods shown below, and the following items were evaluated. The results are shown in Tables 3 to 5. The coating films and films of Examples 1 to 10 and Comparative Examples 1 to 15 were formed by applying the aqueous resin composition to the surface to be coated within 1 hour after preparing the aqueous resin composition (completion of coating within 1 hour after the end of the mixing step).

[0187] <4-1. Method for measuring film yield strength> The aqueous resin composition was applied by casting so as to cover the entire surface of a flat plate made of a rectangular polyethylene film having a length of 90 mm and a width of 190 mm placed horizontally. After drying this at 23°C for 72 hours and then aging at 50°C for 24 hours, a coating film having a thickness of about 300 μm was prepared. The obtained coating film was peeled off from the flat plate. The film obtained by peeling the coating film from the flat plate was cut out into a rectangle having a width of 10 mm and a length of 30 mm to obtain a test piece.

[0188] The following test was performed with the longitudinal direction of this test piece as the tensile direction. The thickness of the test piece was measured using Mitutoyo Corporation's Quick Micro (registered trademark) MDQ-MX. The measurement was performed at three locations for each test piece, and the average value of the measurement results at the three locations was taken as the thickness t [mm] of the test piece. The thickness of the test piece was about 300 μm.

[0189] The test of film yield strength was carried out by the method shown below using an autograph AG-X (manufactured by Shimadzu Corporation). With the distance between chucks set at 10 mm, both sides in the longitudinal direction of the test piece were gripped by the chucks. The test piece was pulled at a speed of 100 mm / min in an atmosphere of 23°C and a relative humidity (RH) of 50%.

[0190] Assuming the distance between chucks is L [mm] and the change in the length of the test piece (the difference between the distance between chucks during the test and the distance between chucks before the test) is ΔL [mm], the strain S is calculated as 100×ΔL / L [%]. Also, assuming the load applied to the test piece (the measured load) is F [N] and the maximum value of the load until the test piece breaks is F max [N], the point that first satisfies the following conditions from the start of the test is defined as the yield point Y (S y , F y ).

[0191] (Conditions for the yield point) The strain S is 2% or more (S y ≧2%). The change amount of the load F accompanying the increase in the strain S changes from increase to decrease. F = F y -0.01F max Until it becomes, dF / dS < 0 continues. S ≦ S y +0.05%, there is no point where F > F[[ID=3)] y .

[0192] The film yield strength, which is the stress σ y applied to the test piece at the yield point Y, is calculated by the formula shown below. σ y [N / mm 2 = F y / (W × t) (In the formula, W is the width [mm] of the test piece and t is the thickness [mm] of the test piece.)

[0193] <4-2. Initial water resistance> An aqueous resin composition was applied to the surface of a cold-rolled steel sheet (thickness: 800 μm) at a basis weight of 50 g / m 2The material was applied using a brush and dried at 23°C for 1 day (24 hours). This formed a rectangular test specimen measuring 70 mm in length and 150 mm in width with a coating on its surface. The thickness of the coating on the test specimen was approximately 100 μm.

[0194] The test specimens prepared in this manner were immersed in deionized water, sealed, and stored at 23°C for 7 days. After that, the test specimens were removed from the deionized water. For the extracted test specimens, the area where rust occurred ("area %) and the area where blistering occurred ("area %) within the test area were measured using the method described below. The test area was defined as a rectangular region of 45 mm in length and 125 mm in width within the coating of the test specimen.

[0195] The test specimens were visually inspected, and areas where the coating surface had discolored to brown or black due to storage were identified as areas where rust had occurred. Each rusted area within the test region was measured using a ruler, and the total area of ​​the rusted areas within the test region was calculated. Using these results, the percentage of the rusted area relative to the total area of ​​the test region was determined. The test specimens were visually inspected and evaluated by touch to check for the presence of areas where blistering had occurred on the coating surface due to storage. As a result, all areas where blistering occurred were found to have a roughly circular planar shape. Therefore, assuming that each blistered area had a perfect circle planar shape, the maximum straight-line distance connecting the contour lines of the blistered area was measured with a ruler, and this result was defined as the diameter. Then, using the diameters of each blistered area, the total area of ​​the blistered areas within the test area was calculated, and the ratio of the blistered area to the area of ​​the test area (%) was determined.

[0196] <4-3. Moist heat adhesion of coatings to metal materials> A water-based resin composition was applied to the surface of a cold-rolled steel sheet (800 μm thick) at a basis weight of 50 g / m². 2The material was applied using a brush and dried at 23°C for 7 days. This formed a rectangular test specimen measuring 70 mm in length and 150 mm in width with a coating on its surface. The test area was defined as a rectangular region measuring 45 mm in length and 125 mm in width within the coating of the test specimen. The thickness of the coating on the test specimen was approximately 100 μm.

[0197] The test specimens prepared in this manner were stored for 3 days in a constant temperature chamber at 40°C and 98% relative humidity (RH). Then, in accordance with JIS K-5400 (1990) "Section 8.5.2 Grid Tape Method," 100 grid-like cuts (1 mm apart) were made with a cutter, penetrating the coating formed in the test area of ​​the test specimen, and cellophane tape (registered trademark) was applied. One hour after application, the cellophane tape (registered trademark) was peeled off, and the number of squares on which the coating remained attached to the steel plate was counted. The moist heat adhesion of the coating to the metal material was then evaluated based on the number of squares that remained attached.

[0198] <4-4. Evaluation Results> As shown in Table 3, the cured films of the resin compositions of Examples 1 to 10, which contain aqueous resin emulsions (α-1) to (α-5) and an aromatic polyamine curing agent (β), all have a yield strength of 10 [N / mm²]. 2 The yield strength of the coating was high. Furthermore, the coating films made from the cured resin compositions of Examples 1 to 10, which were cured at room temperature for a short period of time (23°C for 1 day (24 hours)), all showed good initial water resistance, with blistering occurring in 30% or less of the area and rust occurring in 15% or less of the area. Furthermore, the coating films made from the cured resin compositions of Examples 1 to 10, which were cured at room temperature, all showed a moist heat adhesion result of 100 / 100 to metal materials, indicating good moist heat adhesion to metal materials.

[0199] Furthermore, as shown in Tables 4 and 5, the cured films of Comparative Examples 1 to 15 all had a yield strength of 10 [N / mm²]. 2 The yield strength of the coating was high. However, the coating films made from the cured aqueous resin compositions of Comparative Examples 1-6, 8-10, and 12-14, which used an aliphatic polyamine as the curing agent (β), Comparative Examples 7 and 11, which contained 1.5 equivalents or more of an aromatic polyamine curing agent (β), and Comparative Example 15, which contained 1.5 mol or more of a curing accelerator (γ) per equivalent of epoxy groups, all showed inferior moist heat adhesion to metal materials compared to the coating films made from the cured aqueous resin compositions of Examples 1-10. [Industrial applicability]

[0200] According to the present invention, it is possible to provide an aqueous resin composition and an aqueous resin composition set that can harden with short curing time at room temperature to form a coating film with excellent initial water resistance and that yields a coating film with good moist heat adhesion to metal materials.

Claims

1. Aqueous resin emulsion (α) and, Hardening agent (β), Contains a curing accelerator (γ), The aqueous resin emulsion (α) comprises a copolymer (X), a polyepoxy compound (Y) that does not have ethylenically unsaturated bonds and has two or more epoxy groups in one molecule, and an aqueous medium (Z). The content of the polyepoxy compound (Y) relative to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 1 to 40% by mass. The copolymer (X) comprises structural units derived from (meth)acrylic acid ester (A) and structural units derived from ethylenically unsaturated carboxylic acid (B). The content of structural units derived from the (meth)acrylic acid ester (A) relative to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 20 to 98% by mass. The content of structural units derived from the ethylenically unsaturated carboxylic acid (B) relative to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 0.1 to 10% by mass, and the structural units derived from the (meth)acrylic acid ester (A) include structural units derived from a hydrophilic (meth)acrylic acid ester (A1) in which the number of carbon atoms in the alcohol-derived portion is 2 or less. The content of structural units derived from the hydrophilic (meth)acrylic acid ester (A1) relative to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 15 to 98% by mass. The copolymer (X) and the polyepoxy compound (Y), or both thereof, contain a carboxyl group. The curing agent (β) comprises an aromatic polyamine (F) having active hydrogen that is reactive to epoxy groups, The amount of aromatic polyamine (F) contained in the curing agent (β) is such that the amount of active hydrogen contained in the aromatic polyamine (F) is 0.10 equivalents or more and 1.50 equivalents or less per equivalent of epoxy groups contained in the aqueous resin emulsion (α). The curing accelerator (γ) comprises a tertiary amine that does not have active hydrogen that is reactive with epoxy groups, The aqueous resin composition wherein the content of the curing accelerator (γ) is 0.0070 mol or more and 1.5 mol or less per equivalent of epoxy groups contained in the aqueous resin emulsion (α).

2. The aqueous resin composition according to claim 1, wherein the (meth)acrylic acid ester (A) is an alkyl (meth)acrylic acid ester.

3. The aqueous resin composition according to claim 1 or claim 2, wherein the ethylenically unsaturated carboxylic acid (B) comprises at least one from the group consisting of α,β-unsaturated monocarboxylic acids, α,β-unsaturated dicarboxylic acids, and vinyl compounds containing a carboxyl group.

4. The aqueous resin composition according to claim 1 or claim 2, wherein the polyepoxy compound (Y) is at least one selected from bisphenol-type epoxy compounds, hydrogenated bisphenol-type epoxy compounds, diglycidyl ethers, triglycidyl ethers, tetraglycidyl ethers, diglycidyl esters, triglycidyl esters, and tetraglycidyl esters.

5. The aqueous resin composition according to claim 1 or claim 2, wherein the copolymer (X) consists of structural units derived from the (meth)acrylic acid ester (A) and structural units derived from the ethylenically unsaturated carboxylic acid (B).

6. The aqueous resin composition according to claim 1 or claim 2, wherein the copolymer (X) comprises structural units derived from an ethylenically unsaturated aromatic compound (C) having a benzene ring and an ethylenically unsaturated bond.

7. The aqueous resin composition according to claim 6, wherein the ethylenically unsaturated aromatic compound (C) is an aromatic vinyl compound.

8. The aqueous resin composition according to claim 1 or claim 2, wherein the aromatic polyamine (F) comprises an aromatic polyamine having two or more benzene rings in one molecule.

9. The aqueous resin composition according to claim 1 or claim 2, wherein the aromatic polyamine (F) comprises a compound represented by the following general formula (1-1). 【Chemistry 1】 (In formula (1-1), A ２ A ３ Each of these independently represents a 1,2-phenylene group, a 1,3-phenylene group, or a 1,4-phenylene group. n represents an integer from 1 to 12.

10. The aqueous resin composition according to claim 9, wherein the aromatic polyamine (F) comprises the compound represented by the general formula (1-1) and m-xylylenediamine.

11. The aqueous resin composition according to claim 1 or claim 2, wherein the curing accelerator (γ) is at least one compound selected from the group consisting of tertiary aliphatic amines, tertiary alicyclic amines, and tertiary heteroaromatic amines.

12. The aqueous resin composition according to claim 1 or 2, wherein the aqueous resin emulsion (α) is an emulsion obtained by emulsion polymerization in the aqueous medium (Z) in the presence of the polyepoxy compound (Y) in which monomers that form structural units of the copolymer (X) are emulsion polymerized.

13. The content of carboxyl groups in the total amount of the copolymer (X) and the polyepoxy compound (Y) is 0.10 × 10 －４ The aqueous resin composition according to claim 1 or claim 2, wherein the concentration is mol / g or more.

14. The epoxy group content in the total amount of the copolymer (X) and the polyepoxy compound (Y) is 0.50 × 10 －４ The aqueous resin composition according to claim 1 or claim 2, wherein the concentration is mol / g or more.

15. A coating film comprising a cured product of the aqueous resin composition described in claim 1.

16. A mixing step of preparing the aqueous resin composition described in claim 1 by mixing an aqueous resin emulsion (α), a curing agent (β), and a curing accelerator (γ), A method for producing a coating film, comprising a coating step of applying the aqueous resin composition to a surface to be coated.

17. The method for manufacturing a coating film according to claim 16, wherein the coating step is completed within one hour after the completion of the mixing step.

18. The components of the aqueous resin composition according to claim 1 are stored separately as a first liquid and a second liquid. The first liquid comprises the aqueous resin emulsion (α), A set of aqueous resin compositions in which the second liquid comprises the curing agent (β) and the curing accelerator (γ).

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