KR20210091114A - Aqueous resin emulsion, manufacturing method thereof, and aqueous resin composition - Google Patents

Abstract

An aqueous resin emulsion comprising a copolymer (X), a polyepoxy compound (Y), and an aqueous medium (Z), wherein the polyepoxy is based on the total amount of the copolymer (X) and the polyepoxy compound (Y). The content of the compound (Y) is 1 to 40% by mass, and the copolymer (X) contains a structural unit derived from (meth)acrylic acid ester (A) and a structural unit derived from an ethylenically unsaturated carboxylic acid (B). and the content rate of the structural unit derived from the (meth)acrylic acid ester (A) with respect to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 20 to 98% by mass, and the copolymer (X) And the content rate of the structural unit derived from the said ethylenically unsaturated carboxylic acid (B) with respect to the total amount of the said polyepoxy compound (Y) is 0.1-10 mass %, The structural unit derived from the said (meth)acrylic acid ester (A) contains a (meth)acryloyloxy group, and contains a structural unit derived from a hydrophilic (meth)acrylic acid ester (A1) having 2 or less carbon atoms in portions other than the (meth)acryloyloxy group, The content of the structural unit derived from the hydrophilic (meth)acrylic acid ester (A1) with respect to the total amount of the copolymer (X) and the polyepoxy compound (Y) is 15 to 98% by mass, and the aqueous resin emulsion is In the aqueous medium (Z), the monomer constituting the structural unit of the copolymer (X) is an emulsion polymerized in the presence of the polyepoxy compound (Y), and the epoxy group content in the nonvolatile matter of the aqueous resin emulsion is 0.50 × 10 ^-4 mol/g or more, and the content of carboxyl ^{groups in the nonvolatile matter of the aqueous resin emulsion is 0.10×10 -4} mol/g or more, to provide an aqueous resin emulsion.

Description

Aqueous resin emulsion, manufacturing method thereof, and aqueous resin composition

The present invention relates to an aqueous resin emulsion, a method for preparing the same, and an aqueous resin composition.

This application claims priority based on Japanese Patent Application No. 2018-212769 for which it applied to Japan on November 13, 2018, The content is used here.

Generally, metal products including machine tools and transport machines are surface-treated for the purpose of protection from impact and rust prevention. In particular, anti-rust coating is often applied to the surface of products that are expected to be used outdoors or exposed to moisture. Conventionally used paints often contain organic solvents, so it is necessary to take measures against volatile organic compounds (VOCs) for workers and the surrounding environment. Therefore, the movement from solvent-based paints to water-based paints is becoming active, and excellent water-based paints having performance equivalent to those of solvent-based paints are required.

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

Patent Document 2 describes a composition comprising an aqueous dispersion of thermoplastic polymer particles in which a thermosetting compound having an oxirane group has been absorbed. It is described that the polymer particles have anti-aggregation functional groups, thereby stabilizing the latex against agglomeration.

In patent document 3, it is described that the acrylate resin (acrylic/epoxy latex) which absorbed the epoxy compound is formed by mixing an epoxy emulsion with the emulsion of an acrylate resin.

Patent Document 4 describes an aqueous dispersion containing an epoxy resin, an aqueous resin composition containing a polyaddition polyamine, and a carboxylic acid polymer. More specifically, it is described that a radical polymerizable monomer and an epoxy resin are polymerized in water to obtain an epoxy-modified acrylic emulsion as the aqueous dispersion.

Japanese Patent Laid-Open No. 2011-89092 Japanese Patent Laid-Open No. 2014-65914 International Publication No. 2017/112018 Japanese Patent Laid-Open No. 2005-2353

In Patent Document 1, a carboxy group and an epoxy group are reacted by a basic catalyst. Accordingly, the polymer particles included in the emulsion composition are already crosslinked. From this point, in patent document 1, in order to maintain dispersion stability favorably, it is necessary to control the crosslinking degree precisely.

In the invention described in Patent Document 2, the monomer having an anti-aggregation functional group has high hydrophilicity. Therefore, the coating film formed using the composition described in this document does not have sufficient water resistance and rust prevention properties.

In invention of patent document 3, the epoxy compound is made to absorb after the synthesis|combination of an acrylic resin. As a result, since the epoxy compound does not sufficiently penetrate to the inside of the particle|grains of an acrylic resin, even if it hardens|cures, many unreacted carboxy groups remain inside the particle|grains, and water resistance and rust prevention property become inadequate. Moreover, since an epoxy compound does not fully permeate even to the inside of particle|grains of an acrylic resin, there exists a location where an acrylic resin and an epoxy resin are not in contact. For this reason, when hardening using an amine etc., the phase comprised only with the acrylic resin with low water resistance is not protected, but it is estimated that water resistance and rust prevention property become inadequate.

In addition, the composition of patent document 3 is expected that the water resistance and intensity|strength of the coating film which hardened this for the said reason will not be enough.

Patent Document 4 discloses an aqueous resin composition containing an epoxy resin-containing aqueous dispersion, a polyaddition polyamine, and a carboxylic acid polymer. In the manufacturing examples shown in Table 2 etc., the raw material of the aqueous dispersion (epoxy-modified acrylic emulsion) containing an epoxy resin is disclosed. Although the example in which the monomer (methyl methacrylate) with hydrophilicity other than methacrylic acid is used (Production Example 8) is also shown, the quantity is small. In patent document 4, when adding a polyamine to an aqueous dispersion, gelation is suppressed by adding a carboxylic acid polymer. When a carboxylic acid polymer is not included, when a polyamine is mixed as a hardening|curing agent, gelation will advance rapidly so that the comparison between Comparative Example 1 and Example 10 may show (Table 8 and Table 9). However, the addition of the carboxylic acid polymer leads to an increase in material cost.

In addition, for example, in the emulsion used as a paint, in the coating process of the product (to be coated), or in the mixing process of the emulsion and curing agent, etc. immediately before that, a process of redispersing the particles contained in the emulsion is required. In this case, it leads to an increase in the cost of the product. In this use, in order to reduce the manufacturing cost of the object to be coated, the emulsion is required to have excellent dispersion stability.

In addition, the paint or the emulsion used for the paint is often left outdoors at a high temperature, and the inside of the container may become hot. Even when stored under such an environment, in order to sufficiently maintain the quality, the emulsion is required to have excellent high-temperature stability.

The present invention provides an aqueous resin emulsion, an aqueous resin composition, and a method for producing an aqueous resin emulsion, which has excellent high temperature stability and dispersion stability, and when included in a coating material, a coating film with high water resistance, rust prevention properties and adhesion to metal materials is obtained. make it a task

The configuration of the present invention for solving the above problems is as follows.

A 1st aspect of this invention provides the following aqueous resin emulsion.

[1] An aqueous resin emulsion comprising a copolymer (X), a polyepoxy compound (Y) having two or more epoxy groups in one molecule without having an ethylenically unsaturated bond, and an aqueous medium (Z), the copolymer The content of the polyepoxy compound (Y) with respect to the total amount of (X) and the polyepoxy compound (Y) is 1 to 40% by mass, and the copolymer (X) is derived from (meth)acrylic acid ester (A). A structural unit and a structural unit derived from an ethylenically unsaturated carboxylic acid (B) are derived from the (meth)acrylic acid ester (A) with respect to the total amount of the copolymer (X) and the polyepoxy compound (Y) The content rate of the structural unit of is 20-98 mass %, The content rate of the structural unit derived from the said ethylenically unsaturated carboxylic acid (B) with respect to the total amount of the said copolymer (X) and the said polyepoxy compound (Y) is 0.1 to 10 mass%, and the structural unit derived from the (meth)acrylic acid ester (A) includes a structural unit derived from the hydrophilic (meth)acrylic acid ester (A1) having 2 or less carbon atoms in the alcohol-derived portion, and the copolymer The content of the structural unit derived from the hydrophilic (meth)acrylic acid ester (A1) with respect to the total amount of (X) and the polyepoxy compound (Y) is 15 to 98% by mass, and the aqueous resin emulsion is in the aqueous medium ( In Z), the monomer constituting the structural unit of the copolymer (X) is an emulsion polymerized in the presence of the polyepoxy compound (Y), and the epoxy group content in the nonvolatile matter of the aqueous resin emulsion is 0.50 × 10 ^-4 mol/g or more, and the content of carboxyl groups in the non-volatile matter of the aqueous resin emulsion is 0.10×10 ^-4 mol/g or more, the aqueous resin emulsion.

The aqueous resin emulsion of the first aspect of the present invention preferably includes the following characteristics. It is also preferable to combine two or more of the following characteristics.

[2] As described in [1], the content of carboxyl groups in the nonvolatile matter of the aqueous resin emulsion ^{is preferably 10×10 -4} mol/g or less.

[3] The content of the epoxy group in the nonvolatile matter of the aqueous resin emulsion according to [1] or [2] ^{is preferably 50×10 -4} mol/g or less.

[4] The (meth)acrylic acid ester (A) according to any one of [1] to [3], preferably includes a (meth)acrylic acid alkylester.

[5] The ethylenically unsaturated carboxylic acid (B) according to any one of [1] to [4], preferably contains a compound having a (meth)acryloyl group and a carboxy group.

[6] The polyepoxy compound (Y) according to any one of [1] to [5], wherein the polyepoxy compound (Y) is a bisphenol-type epoxy compound, a hydrogenated bisphenol-type epoxy compound, diglycidyl ether, triglycidyl ether, or tetraglycidyl. It is preferable that it is at least 1 sort(s) chosen from ether, diglycidyl ester, triglycidyl ester, and tetraglycidyl ester.

[7] The glass transition point of the copolymer (X) according to any one of [1] to [6] is preferably -30°C or more and 100°C or less.

[8] The copolymer (X) according to any one of [1] to [7], comprising a structural unit derived from (meth)acrylic acid ester (A) and a structural unit derived from an ethylenically unsaturated carboxylic acid (B). It is preferable to do

[9] The copolymer (X) according to any one of [1] to [8], wherein the copolymer (X) contains a structural unit (c) derived from an ethylenically unsaturated aromatic compound (C) having a benzene ring and an ethylenically unsaturated bond. desirable.

[10] The ethylenically unsaturated aromatic compound (C) according to [9], preferably an aromatic vinyl compound.

A 2nd aspect of this invention provides the following aqueous resin compositions.

[11] The water-based resin emulsion (α), which is the water-based resin emulsion according to any one of [1] to [10], and a curing agent (β) having a functional group having reactivity with an epoxy group, wherein the curing agent (β) Content of the said functional group contained is 0.01 equivalent or more and 1.0 equivalent or less with respect to the quantity of the epoxy group contained in the said polyepoxy compound (Y), The aqueous resin composition.

The aqueous resin composition of the 2nd aspect of this invention contains the following characteristics preferably.

[12] The curing agent (β) according to [11], preferably has at least one selected from the group consisting of an amine group, a carboxy group, and a mercapto group.

A 3rd aspect of this invention provides the manufacturing method of the following aqueous resin emulsion.

[13] (meth)acrylic acid ester (A) and ethylenically unsaturated carboxylic acid (B) in the presence of a polyepoxy compound (Y) having no ethylenically unsaturated bond and having two or more epoxy groups in one molecule A method for producing an aqueous resin emulsion, comprising the step of emulsion polymerization of a monomer containing in an aqueous medium (Z) to obtain an aqueous resin emulsion,

In the aqueous resin emulsion, the addition amount of the polyepoxy compound (Y) to the total amount of the monomer and the polyepoxy compound (Y) is 1 to 40% by mass, and the amount of the monomer and the polyepoxy compound (Y) is 1 to 40% by mass. The addition amount of the said (meth)acrylic acid ester (A) with respect to the total amount is 20-98 mass %, The addition amount of the said ethylenically unsaturated carboxylic acid (B) with respect to the total amount of the said monomer and the said polyepoxy compound (Y). is 0.1 to 10 mass%, and the (meth)acrylic acid ester (A) contains a hydrophilic (meth)acrylic acid ester (A1) having 2 or less carbon atoms in an alcohol-derived moiety, the monomer and the polyepoxy compound (Y ), the addition amount of the hydrophilic (meth)acrylic acid ester (A1) is 15 to 98 mass %, the content of the epoxy group in the nonvolatile matter of the aqueous resin emulsion is 0.50 × 10 ^-4 mol/g or more, The method for producing an aqueous resin emulsion, wherein the aqueous resin emulsion has a carboxyl group content of 0.10×10 ^{−4 mol/g or more in the nonvolatile matter.}

The manufacturing method of the aqueous resin emulsion of the 3rd aspect of this invention preferably includes the following characteristics.

[14] In the aqueous resin emulsion, the emulsion polymerization is preferably performed at 30 to 90°C.

In the fourth aspect of the present invention, in the presence of a polyepoxy compound (Y), a monomer containing (meth)acrylic acid ester (A) and ethylenically unsaturated carboxylic acid (B) is emulsified in an aqueous medium (Z). comprising a process of polymerization,

The addition amount of (meth)acrylic acid ester (A) with respect to the total amount of the said monomer and polyepoxy compound (Y) is 20-98 mass %,

The addition amount of ethylenically unsaturated carboxylic acid (B) with respect to the total amount of the said monomer and polyepoxy compound (Y) is 0.1-10 mass %,

A method for producing an aqueous resin emulsion is provided, wherein the addition amount of the polyepoxy compound (Y) to the total amount of the monomer and the polyepoxy compound (Y) is 1 to 40 mass%.

According to the present invention, a water-based resin emulsion, a water-based resin composition, and a method for producing an water-based resin emulsion are provided, which have excellent high-temperature stability and dispersion stability, and when included in a paint, a coating film with high water resistance, rust prevention properties and adhesion to metal materials is obtained can do.

BRIEF DESCRIPTION OF THE DRAWINGS It is a graph which showed the relationship between the elongation and stress of the coating film obtained from the aqueous resin composition which concerns on Example 101.
FIG. 2 is a graph showing the relationship between elongation and stress of a coating film obtained from an aqueous resin composition according to Comparative Example 104. FIG.

Hereinafter, examples of preferred embodiments of the water-based resin emulsion of the present invention, the method for producing the water-based resin emulsion, the water-based resin composition, and the method for producing the water-based resin composition will be described in detail.

In addition, this invention is not limited only to embodiment described below. For example, the present invention is not limited to the following examples, and addition, omission, substitution or change is possible with respect to the number, kind, position, amount, ratio, material, configuration, etc., without departing from the spirit of the present invention. do.

(Explanation of the phrase)

"Cure" means that molecules contained in the raw material are bonded to each other by a chemical reaction to form a polymer having a network structure.

"(meth)acrylate" means acrylate or methacrylate, and "(meth)acryl" means acryl or methacryl, respectively.

An "ethylenically unsaturated bond" means the double bond between carbon atoms except the carbon atom which forms an aromatic ring.

Let "weight average molecular weight" be a standard polystyrene conversion value measured by gel permeation chromatography (GPC: gel permeation chromatography).

"Coating film" means a coating film formed by drying a medium after application of the aqueous resin composition containing the aqueous resin emulsion according to the present embodiment, and curing the resin component, unless otherwise specified.

<1. Aqueous Resin Composition>

The aqueous resin composition according to the present embodiment contains an aqueous resin emulsion (α) and a curing agent (β). The aqueous resin composition according to the present embodiment is produced by mixing an aqueous resin emulsion (α) and a curing agent (β) as described later.

<1-1. Water-based resin emulsion (α)>

The aqueous resin emulsion (α) contains a copolymer (X), a polyepoxy compound (Y) having two or more epoxy groups in one molecule without having an ethylenically unsaturated bond, and an aqueous medium (Z). The aqueous resin emulsion (α) is an emulsion in which a monomer serving as a structural unit of the copolymer (X) is emulsion-polymerized in the presence of a polyepoxy compound (Y) in an aqueous medium (Z). This is because, when mixed with a curing agent (β) to be described later and cured, a coating film having high strength and high elongation is obtained.

<1-1-1. Copolymer (X)>

The copolymer (X) has a structural unit (a) derived from (meth)acrylic acid ester (A) and a structural unit (b) derived from an ethylenically unsaturated carboxylic acid (B). Moreover, the structural unit (a) derived from (meth)acrylic acid ester (A) contains the structural unit (a1) derived from hydrophilic (meth)acrylic acid ester (A1).

The copolymer (X) may include a structural unit (a) and a structural unit (b) (referred to as copolymer (X1)). The copolymer (X) has a structural unit (a), a structural unit (b), and a 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)) may be used. The copolymer (X) may have a structural unit (d) (referred to as a structural unit derived from another monomer (D)) other than the structural units (a) to (c).

[(meth)acrylic acid ester (A)]

As (meth)acrylic acid ester (A), it is preferable that (meth)acrylic acid alkylester is included. As an example of (meth)acrylic acid alkylester, what has a C1-C18 linear, branched or cyclic alkyl group is more preferable. 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, isoboronyl (meth)acrylate, etc. are mentioned. These may be used by 1 type, and may be used in combination of 2 or more type. The example of hydrophilic (meth)acrylic acid ester (A1) mentioned later can also be contained in the example of (meth)acrylic acid ester (A). In addition, (meth)acrylic acid ester which has a carboxy group is not contained in (meth)acrylic acid ester (A), but is contained in the ethylenically unsaturated carboxylic acid (B) mentioned later.

It is preferable that the compound with low hydrophilicity is contained as (meth)acrylic acid ester (A). It is because the rust prevention property of a coating film is improved. From the same reason, as (meth)acrylic acid ester (A), you may contain the (meth)acrylic acid ester which has an epoxy group.

As (meth)acrylic acid ester which has the said epoxy group, For example, (meth)acrylic acid glycidyl, (meth)acrylic acid beta-methylglycidyl, 4-hydroxybutyl (meth)acrylate glycidyl ether, 3; 4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, etc. are mentioned. The structural unit (a) may include a structural unit derived from only one of these compounds, or may include a structural unit derived from two or more of these compounds. Moreover, it is preferable that the structural unit (a) contains the structural unit derived from glycidyl (meth)acrylate among these compounds.

In addition, (meth)acrylic acid ester may be sufficient as (meth)acrylic acid ester (A), either of a (meth)acrylic acid alkylester and the compound which has an epoxy group may be sufficient as it. As such (meth)acrylic acid ester, the (meth)acrylic acid ester etc. which have a hydroxyl group are mentioned.

Examples of the (meth)acrylic acid ester 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 is mentioned. Moreover, mono(meth)acrylic acid ester of polyalkylene glycol, such as mono(meth)acrylic acid ester of polyethyleneglycol, and mono(meth)acrylic acid ester of polypropylene glycol, etc. are mentioned. Only 1 type may be used for (meth)acrylic acid ester which has these hydroxyl groups, and may use 2 or more types together.

The content rate of the structural unit (a) derived from (meth)acrylic acid ester (A) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y) is 20 mass % or more. This is because the dispersion stability of the monomer of the copolymer (X) and the polyepoxy compound (Y) can be improved in the method for producing an aqueous resin emulsion described later. From this viewpoint, it is preferable that the content rate of the structural unit (a) derived from (meth)acrylic acid ester (A) with respect to the total amount of copolymer (X) and polyepoxy compound (Y) is 35 mass % or more, and 45 mass % or more. It is more preferable, and it is still more preferable that it is 60 mass % or more.

In addition, when the copolymer (X) contains the structural unit (a) and the structural unit (b), that is, when it is the copolymer (X1), it is preferable that the ratio is the following from the viewpoint of similar dispersion stability improvement. That is, the content of the structural unit (a) derived from (meth)acrylic acid ester (A) with respect to the total amount of the copolymer (X1) and the polyepoxy compound (Y) is more preferably 50 mass% or more, and 60 mass% or more It is particularly preferred.

The content rate of the structural unit (a) derived from (meth)acrylic acid ester (A) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y) is 98 mass % or less. When it exceeds 98 mass %, it is because there exists a tendency for the dispersion stability of an aqueous resin emulsion to fall. From this point of view, the content of the structural unit (a) derived from (meth)acrylic acid ester (A) with respect to the total amount of the copolymer (X) and the polyepoxy compound (Y) is preferably 92% by mass or less, and 87% by mass or less. more preferably.

In addition, when the copolymer (X) has a structural unit (a), a structural unit (b) and a structural unit (c), that is, when the copolymer (X) is a copolymer (X2), from the same viewpoint, the following It is preferable that it is a ratio. That is, as for the content rate of the structural unit (a) derived from (meth)acrylic acid ester (A) in copolymer (X2), it is more preferable that it is 75 mass % or less, It is especially preferable that it is 65 mass % or less.

[Hydrophilic (meth)acrylic acid ester (A1)]

The structural unit derived from the (meth)acrylic acid ester (A) includes a structural unit derived from the hydrophilic (meth)acrylic acid ester (A1).

The hydrophilic (meth)acrylic acid ester (A1) has a (meth)acryloyloxy group (CH ₂ =CR-COO-, R represents hydrogen or a methyl group), and an alcohol-derived moiety, that is, a (meth)acryloyloxy group It is (meth)acrylic acid ester whose carbon atom number in a part other than this is 2 or less. 1 or 2 may be sufficient as the said carbon atom number of parts other than an acryloyloxy group, for example. Examples of the hydrophilic (meth)acrylic acid ester (A1) include methyl (meth)acrylate, ethyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylic acid. The hydrophilic (meth)acrylic acid ester (A1) is preferably a (meth)acrylic acid alkylester having 2 or less carbon atoms in the alcohol-derived moiety, and more preferably methyl methacrylate.

The content rate of the structural unit (a1) derived from hydrophilic (meth)acrylic acid ester (A1) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y) is 15 mass % or more. This is because, when the content of the hydrophilic (meth)acrylic acid ester is small as described above, gelation proceeds rapidly when the aqueous resin emulsion (α) is mixed with a curing agent containing a polyamine.

The content of the structural unit (a1) 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% by mass or more, preferably 20% by mass or more, It is more preferable that it is 30 mass % or more, and it is still more preferable that it is 40 mass % or more. It is because the water resistance and rust prevention property of the coating film after hardening improve more. 45 mass % or more or 50 mass % or more may be sufficient as the said content rate.

The upper limit of the content rate of the structural unit (a1) derived from the hydrophilic (meth)acrylic acid ester (A1) with respect to the total amount of the copolymer (X) and the polyepoxy compound (Y) is the structure derived from the (meth)acrylic acid ester (A) It is the same as the upper limit of the content rate described in unit (a). However, when 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 novolak type epoxy compound, the ratio of the structural unit (a1) to the structural unit (a) It is preferable that it is 90 mass % or less, It is more preferable that it is 80 mass % or less, It is still more preferable that it is 70 mass % or less. This is because the affinity between the copolymer (X) and the polyepoxy compound (Y) is improved.

[Ethylenic Unsaturated Carboxylic Acid (B)]

The ethylenically unsaturated carboxylic acid (B) is a compound having an ethylenically unsaturated bond and a carboxy group. The ethylenically unsaturated carboxylic acids (B) are α,β-unsaturated monocarboxylic acids, α,β-unsaturated dicarboxylic acids, monoalkyl esters of α,β-unsaturated dicarboxylic acids, and vinyl containing carboxyl groups. It is preferable to include at least 1 sort(s) from the group which consists of compounds. Examples of the 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. As a vinyl compound containing a carboxy group, phthalic acid monohydroxyethyl (meth)acrylate, oxalic acid monohydroxypropyl (meth)acrylate, etc. are mentioned, for example. The structural unit (b) may be derived from only one of these compounds, or may include structural units derived from two or more of these compounds. Among these compounds, the ethylenically unsaturated carboxylic acid (B) preferably contains a compound having a (meth)acryloyl group and a carboxyl group, and further preferably contains (meth)acrylic acid. That is, the structural unit (b) preferably includes a structural unit derived from a compound having a (meth)acryloyl group and a carboxy group, and further preferably includes a structural unit derived from (meth)acrylic acid.

The content rate of the structural unit (b) derived from an ethylenically unsaturated carboxylic acid (B) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y) is 0.1 mass % or more. This is because the dispersion stability of the aqueous resin emulsion (α) is improved. From this viewpoint, it is preferable that the content rate of the structural unit (b) derived from an ethylenically unsaturated carboxylic acid (B) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y) is 0.3 mass % or more, and 0.5 mass % More preferably. 0.8 mass % or more or 1.0 mass % or more may be sufficient as the said content rate. The content rate of the structural unit (b) derived from an ethylenically unsaturated carboxylic acid (B) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y) is 10 mass % or less. This is because it suppresses the copolymer (X) from becoming a gel in a high-temperature environment and improves the high-temperature stability of the aqueous resin emulsion (α). From this viewpoint, it is preferable that the content rate of the structural unit (b) derived from an ethylenically unsaturated carboxylic acid (B) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y) is 7 mass % or less, and 5 mass % or less is more preferable. 4 mass % or less or 3 mass % or less may be sufficient as the said content rate.

[Ethylenically Unsaturated Aromatic Compound (C)]

The ethylenically unsaturated aromatic compound (C) does not correspond to any of the (meth)acrylic acid ester (A) and the ethylenically unsaturated carboxylic acid (B), and is a compound having a benzene ring and an ethylenically unsaturated bond. It is preferable that an ethylenically unsaturated aromatic compound (C) is an aromatic vinyl compound. Examples of the aromatic vinyl compound as the ethylenically unsaturated aromatic compound (C) include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, and 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-isopropenyl phenol. The structural unit (c) may be derived from only one of these compounds, or may include structural units derived from two or more of these compounds. Among these, it is more preferable that the structural unit (c) contains the structural unit derived from hydrocarbon, and it is especially preferable that it is a structural unit derived from styrene.

When the copolymer (X) contains the structural unit (c) derived from the ethylenically unsaturated aromatic compound (C), that is, when the copolymer (X) is the copolymer (X2), the copolymer (X2) and the polyepoxy compound It is preferable that the content rate of the structural unit (c) with respect to the total amount of (Y) is 5 mass % or more. This is because the water resistance of the coating film is improved. From this viewpoint, the content of the structural unit (c) with respect to the total amount of the copolymer (X2) and the polyepoxy compound (Y) is more preferably 10 mass % or more, and still more preferably 15 mass % or more. 18 mass % or more, 20 mass % or more, or 23 mass % or more may be sufficient as the said content rate.

When copolymer (X) is a copolymer (X2), it is preferable that the content rate of the structural unit (c) with respect to the total amount of a copolymer (X2) and a polyepoxy compound (Y) is 50 mass % or less. This is because the weather resistance of the coating film is improved. From this viewpoint, the content rate of the structural unit (c) with respect to the total amount of the copolymer (X2) and the polyepoxy compound (Y) is more preferably 40 mass % or less, and still more preferably 35 mass % or less. 33 mass % or less, 30 mass % or less, or 28 mass % or less may be sufficient as the said content rate.

[Other Monomer (D)]

The other monomer (D) does not correspond to any of the (meth)acrylic acid ester (A), the ethylenically unsaturated carboxylic acid (B) and the ethylenically unsaturated aromatic compound (C), and is also used in the synthesis of the copolymer (X). It is a compound which has an ethylenically unsaturated bond copolymerizable with the compound used. As another monomer (D), a conjugated diene compound, a maleimide compound, a vinyl ether compound, an allyl ether compound, the dialkyl ester of unsaturated dicarboxylic acid, the vinyl compound etc. which have a cyano group are mentioned, for example.

Examples of the conjugated diene compound include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, chloroprene (2-chloro-1,3-). butadiene) and the like. Only 1 type may be used for these conjugated diene compounds, and may use 2 or more types together.

Examples of the maleimide compound include maleimide, N-methylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-dodecylmaleimide, N-phenylmaleimide, and N-(2-methylphenyl). ) Maleimide, N- (4-methylphenyl) maleimide, N- (2,6-dimethylphenyl) maleimide, N- (2,6-diethylphenyl) maleimide, N- (2-methoxyphenyl) Maleimide, N-benzyl maleimide, N-(4-hydroxyphenyl) maleimide, N-naphthyl maleimide, N-cyclohexyl maleimide, etc. are mentioned. These maleimide-type compounds may use only 1 type, and may use 2 or more types together.

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.

Examples of the allyl ether compound 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 ethers.

As dialkyl ester of the said unsaturated dicarboxylic acid, For example, Unsaturation, such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, etc. The dialkyl ester of dicarboxylic acid is mentioned. Only 1 type may be used for these dialkyl ester, and can also use 2 or more types together. Only 1 type may be used for these unsaturated compounds, and may use 2 or more types together.

Examples of the vinyl compound having a cyano group include acrylonitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-chloroacrylonitrile and α-fluoroacrylonitrile. there is. Only 1 type may be used for these cyano group containing vinyl monomers, and may use 2 or more types together.

<1-1-2. Polyepoxy compound (Y)>

A polyepoxy compound (Y) is a compound which does not have an ethylenically unsaturated bond and has two or more epoxy groups in 1 molecule. The polyepoxy compound (Y) is a bisphenol type epoxy compound, a hydrogenated bisphenol type epoxy compound, diglycidyl ether, triglycidyl ether, tetraglycidyl ether, diglycidyl ester, triglycidyl ester and tetraglycidyl ester. It is preferable that it is at least 1 sort(s) chosen from cidyl ester. As examples of compounds having two or more epoxy groups in one molecule, diglycidyl ether of bisphenol A, diglycidyl ether of hydrogenated bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of hydrogenated bisphenol F Cydyl ether, glycerin polyglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diglycidyl ester of phthalic acid, 1,4-cyclohexanedimethanol Diglycidyl ether, 1,3-cyclohexane dimethanol diglycidyl ether, diglycidyl ester of hexahydrophthalic acid, etc. are mentioned. One of these compounds may be included, or two or more types may be included.

As for the said polyepoxy compound (Y), it is more preferable that they are a bisphenol-type epoxy compound and a hydrogenated bisphenol-type epoxy compound, It is still more preferable that they are a bisphenol-A epoxy compound and a hydrogenated bisphenol-A epoxy compound. It is because the water resistance and rust prevention property of the coating film after hardening improve more.

Although the weight average molecular weight of a polyepoxy compound (Y) is not specifically limited, Preferably it is 1000 or less, More preferably, it is 800 or less, More preferably, it is 500 or less. The compatibility with the copolymer (X) of the polyepoxy compound (Y) is improved, and an emulsion having excellent dispersion stability and storage stability can be obtained. The lower limit of the molecular weight may be arbitrarily selected, for example, 200 or 300 may be sufficient, but is not limited thereto.

The epoxy equivalent of the polyepoxy compound (Y) (the mass of the polyepoxy compound (Y) per mol of the epoxy group) is preferably 500 g/mol or less, more preferably 350 g/mol or less, and still more preferably 250 g/mol or less. It is because the intensity|strength of the coating film which hardened the aqueous resin composition mentioned later becomes high. The lower limit of the epoxy equivalent may be arbitrarily selected, and for example, 70 g/mol or more may be sufficient, and 120 g/mol or more may be sufficient, but it is not limited to these examples.

The content rate of the polyepoxy compound (Y) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y) is 1 mass % or more. It is because the water-based resin composition is hardened|cured and the coating film which has the outstanding rust prevention property is obtained. From this viewpoint, the content rate of the polyepoxy compound (Y) with respect to the total amount of the copolymer (X) and the polyepoxy compound (Y) is preferably 5 mass % or more, more preferably 8 mass % or more, and 10 mass % or more more preferably. 12 mass % or more or 20 mass % or more may be sufficient as needed. The content rate of the polyepoxy compound (Y) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y) is 40 mass % or less. This is because an aqueous resin emulsion (α) with high dispersion stability is obtained. From this viewpoint, it is preferable that it is 35 mass % or less, and, as for the content rate of the polyepoxy compound (Y) with respect to the total amount of a copolymer (X) and a polyepoxy compound (Y), it is more preferable that it is 30 mass % or less.

<1-1-3. aqueous medium (Z)>

As the aqueous medium (Z), it can be arbitrarily selected, and it is preferable to use water. However, as long as the dispersion stability of the copolymer (X) and the polyepoxy compound (Y) is not impaired, for example, water in which a water-soluble solvent is added may be used as the aqueous medium (Z). The hydrophilic solvent to be added to water can be arbitrarily selected, and examples thereof include methanol, ethanol, and N-methylpyrrolidone.

<1-1-4. Method for producing aqueous resin emulsion (α)>

The method for producing the aqueous resin emulsion (α) according to the present embodiment comprises a (meth)acrylic acid ester (A) and an ethylenically unsaturated carboxylic acid (B) in the presence of a polyepoxy compound (Y) ( That is, it is carried out by emulsion polymerization of the monomer for constituting the copolymer (X) in the aqueous medium (Z). According to the production method of the present embodiment using this method, it is considered that an aqueous resin emulsion (α) in which the polyepoxy compound (Y) is uniformly dispersed in the particles of the resulting copolymer (X) can be obtained. Here, "uniformly present" does not necessarily mean that the copolymer (X) and the polyepoxy compound (Y) are compatible with each other, and in both the center side and the surface side of the copolymer (X) particles, the poly The domain of the epoxy compound (Y) should just exist without bias. As a specific method of emulsion polymerization, the method of inject|throwing-in each component containing a monomer collectively, the method of superposing|polymerizing while continuously supplying each component, etc. can be used. It is preferable to stir during the polymerization reaction.

The content of each raw material in the entire raw material used for production of the aqueous resin emulsion (α) is the same as the content of the structural unit derived from the raw material or a compound corresponding to the raw material in the aqueous resin emulsion (α).

The polymerization is preferably carried out at an arbitrarily selected temperature, for example, at a temperature of 30 to 90°C, more preferably at a temperature of 40 to 80°C, still more preferably at a temperature of 40 to 70°C. It is because the carboxy group contained in a monomer suppresses reaction with the epoxy group contained in a polyepoxy compound (Y).

The emulsifier used in the emulsion polymerization can be arbitrarily selected, for example, nonionic interfaces such as polyoxyalkylene alkyl ether, polyoxyalkylene alkyl phenol ether, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, etc. Anionic surfactants, such as an activator, an alkyl sulfate ester salt, an alkylbenzene sulfonate, an alkyl sulfosuccinate, an alkyl diphenyl ether disulfonate, a polyoxyalkylene alkyl sulfate, and polyoxyalkylene alkyl phosphate ester, are mentioned. These may be used individually by 1 type, and may be used in combination of 2 or more type. Alkylbenzenesulfonate is preferable as these emulsifiers, and it is more preferable to use sodium dodecylbenzenesulfonate.

In emulsion polymerization, it is preferable to use a polymerization initiator. As a polymerization initiator, it is preferable to use a peroxide, for example. As a peroxide used as a polymerization initiator, persulfate, such as potassium persulfate and ammonium persulfate, hydrogen peroxide, etc. are mentioned, for example. Moreover, the redox-type initiator by the combined use of a peroxide and a reducing agent can also be used. As a reducing agent, sodium sulfoxylate formaldehyde, ascorbic acid, a sulfite, tartaric acid, its salt, etc. are mentioned. Moreover, you may use alcohol and mercaptans as a chain transfer agent as needed.

<1-1-5. Characteristics of water-based resin emulsion (α)>

[pH of aqueous resin emulsion (α)]

It is preferable that it is 2-10, and, as for the pH of the aqueous resin emulsion (alpha), it is more preferable that it is 5-9. When the pH is within this range, the mechanical stability and chemical stability of the aqueous resin emulsion (α) can be improved. pH is the value measured in the liquid temperature of 25 degreeC using the pH meter by the hydrogen ion concentration indicator which used the glass electrode as a standard electrode. For example, the pH can be adjusted by adding a basic substance to the aqueous resin emulsion (?) during emulsion polymerization or after completion of the emulsion polymerization. Ammonia, triethylamine, ethanolamine, caustic soda etc. are mentioned as an example of the basic substance used for pH adjustment. These may be used individually by 1 type, and may be used in combination of 2 or more type.

[Concentration of non-volatile matter in aqueous resin emulsion (α)]

The concentration of the nonvolatile matter of the aqueous resin emulsion (α) is preferably 10 to 65 mass%, more preferably 15 to 60 mass%, still more preferably 20 to 55 mass%. 30-50 mass % or 35-45 mass % may be sufficient as the said density|concentration. However, in consideration of workability in the process of mixing with a curing agent (β) or the like described later or in the coating process of the aqueous resin composition, the concentration of nonvolatile matter in the aqueous resin emulsion (α) is determined by the amount of the aqueous medium (Y) added. can be appropriately adjusted by adjusting the

In addition, the nonvolatile matter concentration here is the mass of the residue obtained after weighing 1 g of the aqueous resin emulsion (α) in an aluminum dish with a diameter of 5 cm and drying it at 105 ° C. for 1 hour while circulating air in a dryer at atmospheric pressure, It is the ratio (mass %) with respect to the mass of the aqueous resin emulsion (alpha) before drying.

[Viscosity of water-based resin emulsion (α)]

In the present embodiment, the viscosity of the aqueous resin emulsion (α) is measured at 23°C. The measurement of the viscosity of the water-based resin emulsion (?) is performed using a B-type viscometer, and is a value measured by selecting a rotor according to the viscosity of the water-based resin emulsion at a rotation speed of 60 rpm. For example, when the viscosity of the water-based resin emulsion (α) is several mPa·s to several hundreds of 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.

[Glass Transition Point of Copolymer (X)]

The glass transition point Tg of the copolymer (X) is calculated based on the glass transition point of the homopolymer of each monomer used for the synthesis of the copolymer (X). In the specific method of calculating the glass transition point Tg of the copolymer (X) is the glass transition of the homopolymer of the monomer advantage _{M i (i = 1, 2} , 3 ...,) used as the starting material Tg _i and, the total monomer From the mass fraction X _i (SigmaX _i (all monomers) = 1) of the monomer i, it is calculated by the following formula (1). In Formula (1), _{both Tg and Tg i} are calculated as the value of the absolute temperature (K).

1/Tg=Σ(X _i /Tg _i ) … (One)

It is preferable that the glass transition point Tg of copolymer (X) is -30 degreeC (243K) or more. It is because the intensity|strength of a coating film improves. From this viewpoint, the glass transition point Tg of the copolymer (X) is more preferably -10°C (263K) or higher, and still more preferably 0°C (273K) or higher. It is because the intensity|strength of the coating film after hardening improves in the case of such a range. 5 degreeC or more or 10 degreeC or more may be sufficient as the glass transition point Tg of copolymer (X). It is preferable that it is 100 degreeC (373K) or less, and, as for the glass transition point Tg of copolymer (X), it is more preferable that it is 80 degreeC (353K) or less. It is because the adhesiveness with respect to the base material of a coating film improves. From this viewpoint, the glass transition point Tg of the copolymer (X) is more preferably 60°C (333K) or less, and particularly preferably 50°C (323K) or less. This is because, in the case of such a range, the flexibility of the coating film after curing can be improved. The glass transition point Tg of the copolymer (X) may be 40°C or less or 30°C or less.

[Epoxy group content in non-volatile matter of water-based resin emulsion (α)]

The content of the epoxy group in the nonvolatile matter of the aqueous resin emulsion (α) is 0.50×10 ^-4 mol/g or more, ^{preferably 3.0×10 -4} mol/g or more, and more preferably 5.0×10 ^-4 mol/g or more do. This is because the water resistance, rust prevention properties, and adhesion to the base material of the coating film after curing can be improved. The content rate of the epoxy group in the nonvolatile matter of the aqueous resin emulsion (α) may be 1.0×10 ^-4 mol/g or more, or 6.0×10 ^-4 mol/g or more.

The content of epoxy groups in the nonvolatile matter of the aqueous resin emulsion (α) ^{is preferably 50×10 -4} mol/g or less, more preferably 30×10 ^-4 mol/g or less, and 20×10 ^-4 mol/g or less. more preferably. The content of the epoxy group in the nonvolatile matter of the aqueous resin emulsion (α) may be 15×10 ^-4 mol/g or less, or 10×10 ^-4 mol/g or less.

_{The content rate R EP} [mol/g] of the epoxy group in the nonvolatile matter in the aqueous resin emulsion (α) is a value obtained as follows. Speaking of the nonvolatile matter concentration of the aqueous resin emulsion (α) C _S [% by mass], the amount of the epoxy group-N ₁ [mol / g] which comprises an aqueous resin emulsion (α) per 1g, the content R _EP of epoxy groups, the expression (2) is displayed. The method of calculating|requiring N<_1> is as described later in an Example.

R _EP =N ₁ /( _CS /100) … (2)

[Carboxy group content in non-volatile matter of aqueous resin emulsion (α)]

The content of carboxyl groups in the nonvolatile matter of the aqueous resin emulsion (α) is 0.10×10 ^-4 mol/g or more, ^{preferably 0.50×10 -4} mol/g or more, and more preferably 1.0×10 ^-4 mol/g or more. do. This is because aggregation of the copolymer (X) can be suppressed during and after the polymerization of the aqueous resin emulsion (α) during storage.

The content of carboxyl groups in the nonvolatile matter of the aqueous resin emulsion (α) ^{is preferably 10×10 -4} mol/g or less, and more preferably 5.0×10 ^-4 mol/g or less. It may be 3.0×10 ^-4 mol/g or less, 2.5×10 ^-4 mol/g or less, or 2.0×10 ^-4 mol/g or less.

Here, the carboxyl group includes not only -COOH, but also a structure in which a cation other than a hydrogen ion and -COO- are bonded. The content of carboxyl groups in the nonvolatile matter of the aqueous resin emulsion (α) is obtained by subtracting the amount of decrease before and after polymerization of the functional groups reacting with the carboxyl groups in the raw material from the content of carboxyl groups in the raw material, as shown by the following formula. The said raw material refers to the component used for the synthesis|combination of the aqueous resin emulsion (alpha). In addition, the functional group which reacts with a carboxy group is an epoxy group in this invention, and a hydroxyl group is not considered to be a functional group which reacts with a carboxy group.

_{Hereinafter, the method of calculating|requiring} content rate R CX [mol/g] of the carboxyl group in the non-volatile matter of the aqueous resin emulsion (alpha) is demonstrated in detail. Let the total amount of carboxyl groups in the raw material (including initiator, solvent, and other additives) be N ₃ [mol/g], and the total amount of epoxy groups in the raw material (including initiator, solvent, other additives, etc.) is N ₂ [mol/g] ], and the amount of epoxy groups contained per 1 g of the aqueous resin emulsion (α) is N ₁ [mol/g]. A non-volatile content concentration of the aqueous resin emulsion (α) Let _S C [% by mass]. At this time, the content rate R _CX of a carboxy group is represented as Formula (3). An example of a method for obtaining N ₁ and N _{2 will be described later in Examples.} N ₂ can be obtained by calculation.

R _CX ={N ₃ -(N ₂ -N ₁ )}/( _CS /100) … (3)

<1-2. Hardener (β)>

The curing agent (β) has a functional group having reactivity with respect to an epoxy group. The curing agent (β) is preferably a compound having at least one selected from the group consisting of an amino group, a carboxy group, and a mercapto group. Examples of the curing agent (β) having an amino group include aliphatic polyamines, alicyclic polyamines, aromatic polyamines, polyamides and tertiary amines. Examples of the aliphatic polyamine include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and modified products thereof. Examples of the alicyclic polyamine include isophoronediamine, menthanediamine, N-aminoethylpiperazine, diaminodicyclohexylmethane and modified products thereof. Examples of the aromatic polyamine include m-xylylenediamine, diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone, and modified products thereof. As polyamide, the condensate of dicarboxylic acid, such as a dimer acid, and the above-mentioned polyamine is mentioned, for example. Examples of the tertiary amine include tertiary amino group-containing compounds such as dimethylbenzylamine and 2,4,6-trisdimethylaminomethylphenol, modified products thereof, imidazole, 2-methylimidazole, 2 -Imidazole compounds, such as ethyl-4-methylimidazole and 2-phenylimidazole, these modified products, etc. are mentioned. As another polyamine, dicyandiimide, adipic acid dihydrazide, etc. are mentioned. As the curing agent (β) having a carboxyl group, a compound having two or more carboxyl groups in the molecule is preferable. Examples include phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic acid, pyromellitic acid, benzophenonetetracarboxylic acid, and 1,2,3,4-butanetetracarboxylic acid. can Examples of the curing agent (β) having a mercapto group include a condensate of thioglycolic acid and a polyhydric alcohol, polysulfide, and the like. You may combine these hardening|curing agents 1 type or 2 or more types. Preferably, it is a polyamine-based curing agent.

Further, examples of commercially available curing agents include Epi-cure 8535, 8536, 8537, 8290 and 8292; Anquamine 401; Casamid 360 and 362; Epilink 381, DP660, HZ350, 92-113 and 92-116; Beckopox EH659W, EH623W, VEH2133W; Adeka Hardner EH-8051; Fujicure FXI-919; tomide TXH-674-B and TXS-53-C; Epotuf 37-680 and 37-681; licacid BTW; And Karenz MT BD-1.

The content of the functional group having reactivity with respect to the epoxy group contained in the curing agent (β) is preferably 0.01 equivalent or more with respect to the amount of the epoxy group contained in the polyepoxy compound (Y), and more preferably 0.1 equivalent or more. It is because the adhesiveness with respect to the rust prevention property of the water-based resin composition after hardening and a metal material improves.

The content of the functional group having reactivity with respect to the epoxy group contained in the curing agent (β) is preferably 1.5 equivalents or less with respect to the amount of the epoxy groups contained in the polyepoxy compound (Y), and more preferably 1.0 equivalent or less. It is because the intensity|strength of a coating film improves. 0.8 equivalent or less, or 0.5 equivalent or less may be sufficient.

<1-3. Other Ingredients>

The aqueous resin composition according to the present embodiment may contain a pigment. Examples of the pigment include titanium oxide, talc, barium sulfate, carbon black, bengala, calcium carbonate, silicon oxide, talc, mica, kaolin, clay, ferrite, and silica sand. It is preferable that 0.1-50 mass % is contained in an aqueous resin composition, and, as for a pigment, it is more preferable that 1-40 mass % is contained. It is because the hiding property of a coating film is improved.

The aqueous resin composition may include a filler, an organic or inorganic hollow balloon, a dispersant (eg, aminoalcohol, polycarboxylate, etc.), a surfactant, a coupling agent (eg, a silane coupling agent, etc.), a defoaming agent, a preservative (eg For example, including additives such as biocides, fungicides, fungicides, algicides, and combinations thereof), flow agents, leveling agents, neutralizing agents (e.g., hydroxides, amines, ammonia, carbonates, etc.) do.

It is preferable to use a silane coupling agent as a coupling agent. An epoxysilane compound is mentioned as a silane coupling agent. Specific examples include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexy)ethyl trime Toxysilane etc. are mentioned.

It is preferable that it is 0.1-5 mass parts with respect to 100 mass parts of aqueous resin emulsion, and, as for the addition amount of a silane coupling agent, it is more preferable that it is 0.3-3 mass parts. It is because the adhesiveness with respect to the rust prevention property of the water-based resin composition after hardening and a metal material improves.

<2. Method of forming a coating film>

An example of the method for forming a coating film using the aqueous resin emulsion (α) of the present embodiment will be described. A method for forming a coating film includes a mixing step of mixing an aqueous resin emulsion (α), a curing agent (β) and, if necessary, other components above to obtain a water-based resin composition, a coating step of applying the water-based resin composition to an object to be coated; It includes a curing process of curing the applied coating film.

In a mixing process, the aqueous resin emulsion (alpha), the hardening|curing agent (beta), and other components are mixed as needed, and the aqueous resin composition in which each component contained is fully disperse|distributed by mixing and stirring is obtained. Stirring can be performed, for example by Robomix (manufactured by Primix Corporation). In order to fully disperse each component, it is preferable to perform stirring for 5 minutes or more. In addition, in order to suppress hardening of a resin component, it is preferable to perform stirring within 1 hour.

An application process applies an aqueous resin composition to a to-be-coated object. The to-be-coated object is a metal material, for example. You may perform surface treatment, such as a primer and an undercoat, to a to-be-coated object beforehand. Although the method using a brush, a roller etc. is mentioned as a method of application|coating, it is not limited to this. In addition, in order to suppress that the resin component hardens|cures before the application|coating process is completed, it is preferable that the application|coating process is performed within 1 hour after completion|finish of a mixing process.

At a hardening process, the resin component contained in an aqueous resin composition is hardened by drying and curing the to-be-coated object to which the aqueous resin composition was apply|coated. The curing time depends on the ambient temperature. For example, it is preferable that it is 5 hours or more at 20 degreeC, it is preferable that it is 1 hour or more at 40 degreeC, and it is preferable that it is 5 minutes or more at 60 degreeC.

<3. Field of application of the present invention>

The aqueous resin emulsion (α) and the aqueous resin composition of the present invention are useful in various fields, particularly in the field of paints for metals. In addition to the coating film obtained from the coating material using the water-based resin emulsion (α) and/or the water-based resin composition of the present invention, the object to be coated, that is, the article to be coated, may be provided with an undercoat layer, a top coat layer, etc. as needed. An article to which a paint comprising the water-based resin emulsion (α) and/or the water-based resin composition of the present invention is applied, that is, an object to be coated can be arbitrarily selected. For example, various household goods, amusement park or amusement rides, home appliances such as refrigerators, sporting goods, buildings (interior and exterior), various industrial goods and parts thereof including transport and machine tools, and automobiles body and chassis, body and underfloor equipment of rail vehicles, ships, marine containers, aircraft, and the like.

Example

Hereinafter, the present invention will be described in detail using examples, but the following examples do not limit the present invention in its entirety, and all things implemented within a range that do not deviate from the contents of the present invention are included in the technical scope of the present invention do.

<1. Synthesis of aqueous resin emulsion (α)>

<1-1. Examples 1 to 10 and Comparative Examples 1 to 4>

158 mass parts of ion-exchange water was thrown into the separable flask which has a cooling tube, a thermometer, a stirrer, and a dropping funnel, and it heated up at 60 degreeC. Nitrogen gas was blown into the contents of the separable flask and deoxygenated. Here, 216 mass parts of methyl methacrylate (A-1), 115 mass parts of 2-ethylhexyl acrylate (A-2), 5 mass parts of methacrylic acid (B-1), hydrogenated bisphenol A epoxy (Y-1) ) 59 mass parts, 5 mass parts of sodium dodecylbenzenesulfonate, and the monomer emulsion containing 356 mass parts of ion-exchange water were dripped over 3 hours. At the same time, as an oxidizing agent, 1.2 parts by mass of potassium persulfate was dissolved in 41 parts by mass of ion-exchanged water, and as a reducing agent, 0.4 parts by mass of sodium bisulfite dissolved in 21 parts by mass of ion-exchanged water was added dropwise at 60°C over 3.3 hours to polymerize. After completion of the dropping, the mixture was aged for 1.5 hours. Then, it cooled, and 0.8 mass parts of aqueous ammonia was added, and the aqueous resin emulsion ((alpha)-1) was obtained. Let this be Example 1.

For the synthesis of aqueous resin emulsions (α-2) to (α-10) (Examples 2 to 10) and (cα-1) to (cα-4) (Comparative Examples 1 to 4), Copolymer (X) The types and amounts (parts by mass) of the monomers and polyepoxy compound (Y) used in the synthesis are shown in Tables 1-1 to 1-4. About the addition amount and preparation method of other components, it carried out similarly to the aqueous resin emulsion (alpha-1). In addition, in Comparative Examples 2 and 3 (cα-3), the polymer was agglomerated without being dispersed.

<Table 1-1>

<Table 1-2>

<Table 1-3>

<Table 1-4>

<1-2> Comparative Example 5

An emulsion of a copolymer (X) was synthesized by the following method in the same formulation as in Example 1 except that the polyepoxy compound (Y) was not used.

30 g of polyethylene glycol-tert-octylphenyl ether 70 mass % aqueous solution (Triton (registered trademark) X-405 (manufactured by Dow Chemical Corporation)) and 67 g of ion-exchanged water were stirred until a uniform solution was obtained to obtain an aqueous surfactant solution. . While stirring the obtained aqueous surfactant solution using an overhead stir bar, 129.5 g of bisphenol A liquid epoxy resin (Y-5) (DER331 (epoxy equivalent 187 g/mol, manufactured by Olin)) was added, and the epoxy resin was Further stirring was continued until no adhesion of the droplets to the inner wall of the vessel was visible. The resulting mixture was stirred with an overhead stir bar at 3000 rpm for 20 minutes to obtain an epoxy dispersion. 45.3 g of the obtained epoxy dispersion and 401.5 g of the emulsion of the copolymer (X) were placed in a flask and stirred at 60° C. for 2 hours to obtain an aqueous resin emulsion (cα-5). The mass ratio of the copolymer (X) and the epoxy resin in the obtained aqueous resin emulsion (cα-5) is computable to 85.0:15.0.

The parts by mass of each component used in the preparation of the aqueous resin emulsion (cα-5) of Comparative Example 5 are as shown in Tables 2-1 and 2-2. These values are conversion values which made the total usage-amount of the monomer for copolymer (X) 336 mass parts in agreement with Example 1.

<2. Evaluation of aqueous resin emulsion (α)>

The aqueous resin emulsions (α-1) to (α-10) and (cα-1) to (cα-5) were evaluated as follows. In addition, in the following description, when water-based resin emulsions (α-1) to (α-10) and (cα-1) to (cα-5) are generically referred to as an aqueous resin emulsion (α), there is.

<2-1. pH>

It measured using the pH meter (Toa DKK Co., Ltd. glass electrode type hydrogen ion concentration indicator HM-30G).

<2-2. Concentration of non-volatile matter>

In an aluminum dish with a diameter of 5 cm, 1 g of the aqueous resin emulsion (α) is weighed and dried at 105° C. for 1 hour while circulating air at atmospheric pressure and in a dryer. ) with respect to the mass (mass %) was calculated|required.

<2-3. Viscosity>

The viscosity of the aqueous resin emulsion (?) was measured under the following conditions and apparatus.

Temperature: 23℃

Measuring Instrument: Type B Viscometer

Rotor: No.1

RPM: 60rpm

<2-4. Glass Transition Point>

The glass transition point Tg of the copolymer (X) is a value calculated by the formula (1).

<2-5. Dispersion Stability>

The state of the aqueous resin emulsion (?) was visually observed and evaluated according to the following criteria.

○ (possible): No aggregation, precipitation, separation, and gelation were observed.

x (impossible): At least any of aggregation, precipitation, separation, and gelation was observed.

<2-6. High Temperature Stability>

The high temperature stability of the aqueous resin emulsion (α) was evaluated as follows. First, the aqueous resin emulsion (α) was put into a 70 ml glass bottle, sealed with a stopper, and left still at 60°C for 7 days. Thereafter, the state of the aqueous resin emulsion (?) in the glass bottle was visually observed and evaluated according to the following criteria.

○ (possible): No aggregation, thickening, precipitation, separation, and gelation were observed.

x (impossible): At least any of aggregation, thickening, precipitation, separation, and gelation was observed.

<2-7. Residual ratio of epoxy groups>

The residual ratio of epoxy groups in the aqueous resin emulsion (α) is the amount of epoxy groups contained in the aqueous resin emulsion (α) after synthesis N ₁ [mol/g] of the component (raw material, _{It is a ratio with respect to the total amount N 2} [mol/g] of the epoxy groups contained in the initiator, solvent, other additives, etc.).

Measurement of the amount of epoxy groups N ₁ [mol/g] of the aqueous resin emulsion (α) after synthesis is measured by adding excess hydrogen chloride to the total amount of epoxy groups contained in the component (raw material) used for the synthesis of the aqueous resin emulsion (α). It was added and reacted with an epoxy group. Next, the amount of remaining hydrogen chloride was confirmed by titrating unreacted hydrogen chloride with potassium hydroxide. Moreover, at this time, potassium hydroxide is consumed by reaction with acidic components, including the carboxylic acid contained in the aqueous resin emulsion (alpha). For this reason, the amount of an acidic component was titrated beforehand by the empty measurement which does not use hydrogen chloride, and the result of this measurement was corrected. A specific measurement procedure is as follows (i) to (iii).

(i) Co-measurement (confirmation of acid content)

The aqueous resin emulsion (α) _{was weighed in an amount of W 1} [g] (5 g in this Example and Comparative Example) in a 100 mL Erlenmeyer flask, 25 g of THF was added thereto, and stirred with a magnetic stir bar to obtain a uniform solution. 0.15 mL of 0.1 mass % cresol red aqueous solution was added to this solution as an indicator. With 0.1M potassium hydroxide/ethanol solution, the solution was titrated with stirring. After the potassium hydroxide/ethanol solution was added dropwise, the point at which the purple color continued for 30 seconds was regarded as the equivalence point. Let the amount of potassium hydroxide/ethanol solution used for titration be V _KOH1 [mL].

(ii) main measurement

The aqueous resin emulsion (α) _{was weighed in an amount of W 2} [g] (5 g in this Example and Comparative Example) in a 100 mL Erlenmeyer flask, 25 g of THF was added thereto, and dissolved by stirring well with a magnetic stir bar. A 0.2 M hydrogen chloride/dioxane solution was added thereto, followed by stirring for 1 hour to obtain a uniform solution. Let the amount of hydrogen chloride / dioxane solution added here be V _HCl [mL] (25 mL in this Example and Comparative Example). 0.15 mL of 0.1 mass % cresol red aqueous solution was added to this solution as an indicator. With 0.1M potassium hydroxide/ethanol solution, the solution was titrated with stirring. The point at which the purple color continued for 30 seconds after the potassium hydroxide/ethanol solution was dripped was made into an equivalence point. Let the amount of potassium hydroxide/ethanol solution used for titration be V _KOH2 [mL].

From the respective numerical values obtained in (i) and (ii), the amount of epoxy groups N ₁ [mol/g] per 1 g of the aqueous resin emulsion (α) was calculated by the following formula (4).

N ₁ =(0.2×V _HCl /1000-0.1×V _KOH2 /1000)/W ₂ +(0.1×V _KOH1 /1000)/W ₁ … (4)

_{The total amount N 2} [mol/g] of the epoxy groups contained in the component (raw material) used for the synthesis of the aqueous resin emulsion (α) is _{the mass m i} [mass part] of each component (i = 1, 2, 3, ...) From and epoxy equivalent EP _i [g/mol], it is calculated|required by the following formula|equation (5). Here, the component used for the synthesis of the aqueous resin emulsion (α) means all the components shown in Tables 1-1 to 1-4.

N ₂ =Σ(m _i /EP _i )/Σm _i … (5)

In addition, about the compound which does not contain epoxy groups, such as methyl methacrylate and ion-exchange water, _{it becomes 1/EP i} =0.

From the amount of the epoxy groups determined in this way, the residual ratio of the epoxy groups in the aqueous resin emulsion (α) is expressed as 100×N ₁ /N ₂ [mol%]. In addition, about the aqueous resin emulsion (cα-1) _{, since N 2} =0, which is the total amount of epoxy groups in the raw material, the residual ratio of the epoxy groups in Table 1-4 was “-”.

<2-8. Content rate of epoxy group in non-volatile matter>

From the concentration of non-volatile matter obtained by the above method, the content of epoxy groups in the aqueous resin emulsion (α) N ₁ , and the total amount of epoxy groups in the raw material N ₂ , the content of epoxy groups in the non-volatile matter of the aqueous resin emulsion (α) R _EP [mol/g] It calculated|required based on Formula (2) demonstrated above.

R _EP =N ₁ /( _CS /100) … (2)

<2-9. Content rate of carboxyl group in non-volatile matter>

_{The total amount N 3} [mol/g] of carboxyl groups contained in the component (raw material) used for the synthesis of the aqueous resin emulsion (α) is _{the mass m i} [mass part] of each component (i = 1, 2, 3, ...) From and carboxy equivalent CX _i [g/mol], it is calculated|required by the following formula|equation (6). Here, the component used for the synthesis of the water-based resin emulsion (α) means all the components described as raw materials for the water-based resin emulsion (α) in Tables 1-1 to 1-4.

N ₃ =Σ(m _i /CX _i )/Σm _i … (6)

From the N _{3 obtained here, the content R CX} [mol/g] of the carboxyl group in the nonvolatile matter of the aqueous resin emulsion (α) was determined based on the formula (3) described above.

R _CX ={N ₃ -(N ₂ -N ₁ )}/( _CS /100) … (3)

<3. Examples 101 to 114 and Comparative Examples 101 to 104 (production of aqueous resin composition)>

In each Example and Comparative Example, 100 parts by mass of the aqueous resin emulsion (α) shown in Tables 2-1 and 2-2, 60 parts by mass of ion-exchanged water, and the kind shown in Tables 2-1 and 2-2 of the curing agent (β) was added in the amount (parts by mass) shown in these tables, followed by stirring for 10 minutes to prepare an aqueous resin composition. In addition, in Table 2-1 and Table 2-2, "amine equivalent", "carboxy equivalent", and "mercapto equivalent" mean the mass (g) per mol of amino group, carboxy group, and mercapto group, respectively. In addition, the "equivalent to the epoxy group" of each curing agent is a numerical value indicating the molar ratio of the functional group contained in the curing agent (β) to the amount of the raw material-based epoxy group contained in the aqueous resin emulsion (α).

<Table 2-1>

<Table 2-2>

<4. Evaluation of Coatings>

<4-1. Water Swelling Rate>

The aqueous resin compositions obtained in Examples 101 to 114 and Comparative Examples 101 to 104 were cast so as to spread evenly over the entire horizontally placed 90 mm x 190 mm rectangular polyethylene film. After drying this at 23 degreeC for 72 hours, the coating film was produced by curing at 50 degreeC for 24 hours. This coating film was peeled from a flat plate, and the peeled coating film was cut out to 10 mm x 10 mm. After weighing the cut-out coating film, it was immersed in ion-exchange water at 23 degreeC for 24 hours. The coating film was taken out from the ion-exchange water, the coating film immediately after that was measured, and this was made into the mass of the coating film before drying. Then, the coating film was dried at 105 degreeC for 3 hours, the coating film was measured again, and this was made into the mass of the coating film after drying. From the mass of the coating film before drying and the mass of the coating film after drying, the value calculated|required by following formula (7) was made into water-resistant swelling ratio.

{(mass of coating film before drying - mass of coating film after drying)/mass of coating film after drying} x 100... (7)

<4-2. Anti-rust>

The water-based resin compositions prepared in Examples 101 to 114 and Comparative Examples 101 to 104 were coated on a cold-rolled steel sheet (hereinafter referred to as “substrate”) to a weight of 50 g/m 2 per unit area using a brush, and at 60 ° C. A coating film was formed on the surface of the substrate by drying in a constant temperature bath for 10 minutes.

A cutout consisting of two intersecting straight lines (that is, an X-shape) was formed in the coating film so as to form a diagonal of a 30 mm x 45 mm rectangle (in this evaluation, this rectangle was used as the test area), and it was set as the test body. The infeed was made to reach the substrate using a cutter knife. A neutral salt spray test (section 4.2.1) was performed based on JIS Z-2371 (2000) with respect to the specimen in which the cut was formed. In the specimen after the neutral salt spray test, the area [area %] occupied by the expansion of the coating film in the test region, the size of the expansion [mm], and the size [mm] of the rust flowing from the cut were measured. The size of the expansion is the longest dimension in the region occupied by one independent expansion. In addition, the size of the rust which flows is made into the maximum value of the width|variety of the rust centering on the cross-cut part.

<4-3. Adhesion of coating film to metal material>

A coating film was formed on the surface of the base material of the cold rolled steel sheet in the same manner as in the evaluation of the rust prevention properties. In accordance with JIS K-5400 (1990) "Section 8.5.2 Checker Tape Method", using a steel plate with a coating film as a test piece, insert cut-outs (100 squares) at intervals of 1 mm with a cutter so as to penetrate the coating film, and cellophane A tape (registered trademark) was bonded. The cellophane tape (registered trademark) was peeled off after 1 hour, and the adhesion of the coating film to the metal material was evaluated by counting the number of cells remaining without the coating film being peeled off the steel plate.

<4-4. Elongation-Stress Measurement of Coatings>

The aqueous resin composition obtained in Example 101 and Comparative Example 104 was cast so that it spreads evenly over the whole on a horizontally placed 90 mm x 190 mm rectangular polyethylene film. After drying this at 23 degreeC for 72 hours, the coating film was produced by curing at 50 degreeC for 24 hours. This coating film was peeled from the flat plate, and the peeled coating film was cut out into a rectangle of 10 mm x 30 mm, and it was set as the test piece. The following tests were performed with the longitudinal direction of this test piece as the tensile direction. The thickness of the test piece used Mitsutoyo Corporation Quick Micro (registered trademark) MDQ-MX, and the average value of 3 points|pieces was made into thickness t [mm] of the test piece. The thickness t of the test piece is shown in Tables 3 and 4.

The test was performed using Autograph AG-X (made by Shimadzu Corporation). The interval (distance between chucks) was set to 10 mm, and both sides in the long side direction of the test piece were gripped with the chuck. The test piece was tension|pulled at the speed|rate of 100 mm/min in 23 degreeC, 50%RH atmosphere.

Table 3 shows the relationship between the elongation and stress of the coating film obtained from the aqueous resin composition according to Example 101. Table 4 shows the relationship between the elongation and stress of the coating film obtained from the aqueous resin composition according to Comparative Example 104.

In addition, if the distance between chucks is L [mm] and the length change of the test piece (difference between the distance between the chucks during the test and the distance between the chucks before the test) is ΔL [mm], the elongation is calculated as 100 × ΔL/L [%]. If the load (measured load) applied to the test piece is F[N], the width of the test piece is W[mm], and the thickness of the test piece is t[mm], the stress applied to the test piece is F/(W×t)[N/ mm2]. Further, as described above, W = 10 mm.

In addition, the value obtained by integrating the value of stress (N/mm 2 ) with the value of elongation (%) was calculated as the stress integral value Σ, based on the values shown in Tables 3 and 4, as follows. _{Let X n be} the value of the elongation (ΔL/L [%]) at the nth point _{, and σ n} be the stress (N/mm 2 ). Assuming that the origin is X ₀ =0 and σ ₀ =0, the stress integral value Σ ₁ from the origin to the first point becomes (X ₁ ×σ ₁ )/2. _{The stress integral value Σ 2} from the origin to the second point is Σ ₁ +{(X ₂ -X ₁ )×(σ ₁ +σ ₂ )/2}. _{Therefore, the stress integral Σ n} from the origin to the nth point is Σ _n-1 + {(X _n -X _n-1 )×(σ _n +σ _n-1 )/2} (that is, Σ _n = {( X ₁ ×σ ₁ )/2)}+{(X ₂ -X ₁ )×(σ ₁ +σ ₂ )/2}+… +{(X _n -X _n-1 )×(σ _n +σ _n-1 )/2}.

In this evaluation, the stress is the load applied per unit cross-sectional area, and the elongation is the rate of change in length. Therefore, it can be said that the stress integral value Σ is the amount of work required to elongate a sample of unit cross-sectional area and unit length (distance between chucks) until fracture, ie, the amount of energy absorbed by the coating film up to fracture.

<Table 3>

<Table 4>

BRIEF DESCRIPTION OF THE DRAWINGS It is a graph which showed the relationship between the elongation and stress of the coating film obtained from the aqueous resin composition which concerns on Example 101. FIG. 2 is a graph showing the relationship between elongation and stress of a coating film obtained from an aqueous resin composition according to Comparative Example 104. FIG. 1 and 2, x represents a breaking point.

<5. Evaluation Results>

From Tables 1-1 to 1-4, it can be seen that all of the aqueous resin emulsions (α-1) to (α-10) of Examples 1 to 10 are excellent in dispersion stability and high temperature stability. In addition, from Table 2-1 and Table 2-2, the aqueous resin emulsions (α-1) to (α-10) were excellent after curing when included in the paint by mixing the curing agent (β) in an appropriate type and amount. It turns out that a coating film with high water resistance, rust prevention property, and adhesiveness to a metal material is obtained.

The aqueous resin emulsion (cα-1) of Comparative Example 1 not containing the polyepoxy compound (Y) did not contain a crosslinking component. For this reason, as shown in Table 2-1 and Table 2-2, water resistance, rust prevention property, and the adhesiveness with respect to a metal material were inadequate.

In contrast, in the aqueous resin emulsion (cα-2) of Comparative Example 2 in which the polyepoxy compound (Y) was added in an excessive amount, the polymer was not dispersed but aggregated.

Comparative Example in which the ethylenically unsaturated carboxylic acid (B) is not used as a monomer of the copolymer (X), that is, the copolymer (X) does not have the structural unit (b) derived from the ethylenically unsaturated carboxylic acid (B) Similarly, the aqueous resin emulsion (cα-3) of No. 3 was agglomerated without dispersing the polymer.

In the polymerization of the copolymer (X), the ethylenically unsaturated monomer (B) is used in excess, that is, the copolymer (X) contains the structural unit (b) derived from the ethylenically unsaturated carboxylic acid (B) in excess. In the aqueous resin emulsion (cα-4) of Comparative Example 4, the high temperature stability was insufficient.

In Comparative Example 5 in which emulsion polymerization was not performed, the stress integral value of the produced coating film (Comparative Example 104), ie, the amount of energy absorbed by the coating film until fracture was small.

After synthesizing the copolymer (X), when a coating film is prepared using the aqueous resin emulsion (cα-5) obtained by mixing the copolymer (X) and the polyepoxy compound (Y), the aqueous resin emulsion (α-1) ), it was found that the strength of the coating film was significantly lowered.

From the above, it was found that the aqueous resin emulsion (α) according to the present invention was excellent in high temperature stability and dispersion stability.

Moreover, it turned out that when the water-based resin composition which concerns on this invention was included in a coating material, the coating film with the outstanding water resistance, rust prevention property, and high adhesiveness to a metal material was obtained.

<Industrial Applicability>

ADVANTAGE OF THE INVENTION According to this invention, it is excellent in high temperature stability and dispersion stability, and when included in a paint, it can provide the manufacturing method of the water-based resin emulsion by which a coating film with high water resistance, rust prevention property, and adhesiveness to a metal material is obtained.

Claims (14)

An aqueous resin emulsion comprising a copolymer (X), a polyepoxy compound (Y) having two or more epoxy groups in one molecule without having an ethylenically unsaturated bond, and an aqueous medium (Z),
The content rate of the said polyepoxy compound (Y) with respect to the total amount of the said copolymer (X) and the said polyepoxy compound (Y) is 1-40 mass %,
The copolymer (X) is
A structural unit derived from (meth)acrylic acid ester (A);
a structural unit derived from an ethylenically unsaturated carboxylic acid (B);
The content rate of the structural unit derived from the said (meth)acrylic acid ester (A) with respect to the total amount of the said copolymer (X) and the said polyepoxy compound (Y) is 20-98 mass %,
The content rate of the structural unit derived from the said ethylenically unsaturated carboxylic acid (B) with respect to the total amount of the said copolymer (X) and the said polyepoxy compound (Y) is 0.1-10 mass %,
The structural unit derived from the (meth)acrylic acid ester (A) includes a structural unit derived from a hydrophilic (meth)acrylic acid ester (A1) having 2 or less carbon atoms in the alcohol-derived moiety,
The content rate of the structural unit derived from the said hydrophilic (meth)acrylic acid ester (A1) with respect to the total amount of the said copolymer (X) and the said polyepoxy compound (Y) is 15-98 mass %,
The aqueous resin emulsion is an emulsion in which a monomer serving as a structural unit of the copolymer (X) in the aqueous medium (Z) is emulsion-polymerized in the presence of the polyepoxy compound (Y),
The content of the epoxy group in the nonvolatile matter of the aqueous resin emulsion is 0.50×10 ^-4 mol/g or more,
The aqueous resin emulsion, wherein the content of carboxyl groups in the nonvolatile matter of the aqueous resin emulsion is 0.10×10 ^-4 mol/g or more. The aqueous resin emulsion according to claim 1, wherein the content of carboxyl groups in the nonvolatile matter of the aqueous resin emulsion is 10×10 ⁻⁴ mol/g or less. The aqueous resin emulsion according to claim 1 or 2, wherein the content of the epoxy group in the nonvolatile matter of the aqueous resin emulsion is 50×10 ⁻⁴ mol/g or less. The aqueous resin emulsion according to any one of claims 1 to 3, wherein the (meth)acrylic acid ester (A) contains a (meth)acrylic acid alkylester. The aqueous resin emulsion according to any one of claims 1 to 4, wherein the ethylenically unsaturated carboxylic acid (B) contains a compound having a (meth)acryloyl group and a carboxy group. The polyepoxy compound (Y) according to any one of claims 1 to 5, wherein the polyepoxy compound (Y) is a bisphenol type epoxy compound, a hydrogenated bisphenol type epoxy compound, diglycidyl ether, triglycidyl ether, or tetraglycidyl ether. , an aqueous resin emulsion, which is at least one selected from diglycidyl esters, triglycidyl esters and tetraglycidyl esters. The aqueous resin emulsion according to any one of claims 1 to 6, wherein the copolymer (X) has a glass transition point of -30°C or higher and 100°C or lower. 8. The method according to any one of claims 1 to 7, wherein the copolymer (X) comprises a structural unit derived from (meth)acrylic acid ester (A) and a structural unit derived from an ethylenically unsaturated carboxylic acid (B). , aqueous resin emulsion. The aqueous solution according to any one of claims 1 to 8, wherein the copolymer (X) comprises a structural unit (c) derived from an ethylenically unsaturated aromatic compound (C) having a benzene ring and an ethylenically unsaturated bond. resin emulsion. The aqueous resin emulsion according to claim 9, wherein the ethylenically unsaturated aromatic compound (C) is an aromatic vinyl compound. The water-based resin emulsion (α), which is the water-based resin emulsion according to any one of claims 1 to 10, and a curing agent (β) having a functional group having reactivity with an epoxy group, and contained in the curing agent (β) Content of the said functional group used is 0.01 equivalent or more and 1.0 equivalent or less with respect to the quantity of the epoxy group contained in the said polyepoxy compound (Y), The aqueous resin composition. The aqueous resin composition according to claim 11, wherein the curing agent (β) is a compound having at least one selected from the group consisting of an amino group, a carboxy group, and a mercapto group. In the presence of a polyepoxy compound (Y) that does not have an ethylenically unsaturated bond and has two or more epoxy groups in one molecule, (meth)acrylic acid ester (A) and an ethylenically unsaturated carboxylic acid (B) A method for producing an aqueous resin emulsion, comprising the step of emulsion polymerization of a monomer in an aqueous medium (Z) to obtain an aqueous resin emulsion, comprising:
In the aqueous resin emulsion,
The addition amount of the said polyepoxy compound (Y) with respect to the total amount of the said monomer and the said polyepoxy compound (Y) is 1-40 mass %,
The addition amount of the (meth)acrylic acid ester (A) with respect to the total amount of the monomer and the polyepoxy compound (Y) is 20 to 98% by mass,
The addition amount of the said ethylenically unsaturated carboxylic acid (B) with respect to the total amount of the said monomer and the said polyepoxy compound (Y) is 0.1-10 mass %,
The (meth)acrylic acid ester (A) includes a hydrophilic (meth)acrylic acid ester (A1) having 2 or less carbon atoms in the alcohol-derived moiety,
The addition amount of the said hydrophilic (meth)acrylic acid ester (A1) with respect to the total amount of the said monomer and the said polyepoxy compound (Y) is 15-98 mass %,
The content of the epoxy group in the non-volatile matter of the aqueous resin emulsion is 0.50 × 10 ^-4 mol/g or more,
The method for producing an aqueous resin emulsion, wherein the aqueous resin emulsion has a carboxyl group content of 0.10×10 ^{−4 mol/g or more in the nonvolatile matter.} The method for producing an aqueous resin emulsion according to claim 13, wherein in the aqueous resin emulsion, the emulsion polymerization is performed at 30 to 90°C.

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