Aqueous resin emulsion and coated article

Abstract

To provide an aqueous resin emulsion excellent in adhesion to a substrate and a top coating material, quick-drying properties, water resistance, and storage stability.SOLUTION: The aqueous resin emulsion contains resin particles each including an inner layer and a protective layer surrounding the inner layer. The inner layer contains a copolymer (A) containing a polymerizable monomer (a1) and a crosslinkable monomer (a2) as constituent units. The protective layer contains at least a copolymer (B) containing a polymerizable monomer (b1) and a carboxy group-containing polymerizable monomer (b2) as constituent units, and a chain transfer agent. The copolymer (A) contains 0.1-15 wt.% of the crosslinkable monomer (a2) in 100 wt.% of all monomers constituting the copolymer (A). The copolymer (B) contains 5-20 wt.% of the carboxy group-containing polymerizable monomer (b2) in 100 wt.% of all monomers constituting the copolymer (B).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an aqueous resin emulsion and a coated article. [Background technology]

[0002] At construction sites, the demand for repair applications is increasing year by year. Currently, weak solvent-soluble acrylic lacquer-type NAD resin paints are widely used as repair primers (hereinafter referred to as sealers) that combine high adhesion to Western-style roof tiles, deteriorated slate roofs, various ceramic roofing materials, and old paint films, with the effect of reinforcing fragile surfaces and adhesion to topcoats. In recent years, due to environmental considerations, there has been a shift from solvent-based to water-based paints not only for topcoats but also for sealers, and many water-based repair sealers have been developed.

[0003] However, compared to solvent-based sealers, water-based repair sealers have poor wetting and penetration into various substrates and old paint films, resulting in poor substrate adhesion. Furthermore, water-based repair sealers dry slowly, resulting in poor film formation when dried at room temperature, and many other problems, such as poor water resistance and poor adhesion to topcoats.

[0004] Therefore, Patent Documents 1 and 2 propose aqueous emulsions that form dense coating films by polymerizing aromatic vinyl monomers (for example, styrene, α-methylstyrene, etc.), thereby improving water resistance and adhesion.

[0005] Furthermore, Patent Documents 3 and 4 propose water-soluble resin emulsions containing a water-soluble resin or a hydrophobic resin, which are made soluble in an aqueous dispersion medium by neutralizing a copolymer containing an acrylic acid or methacrylic acid ester and a carboxyl group-containing unsaturated monomer with an alkali, thereby improving the wettability and permeability to the substrate, and improving the substrate adhesion and reinforcing effect. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-181605 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-166428 [Patent Document 3] Japanese Patent Application Publication No. 11-217559 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-241427 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in Patent Documents 1 and 2, a large amount of aromatic vinyl monomer is used in the production process of the aqueous emulsion, which makes the coating film made of the aqueous emulsion hard and brittle. Therefore, the aqueous emulsions of Patent Documents 1 and 2 may not be able to achieve sufficient adhesion to the substrate or sufficient reinforcement effect for the substrate.

[0008] In addition, Patent Documents 3 and 4 contain a large amount of carboxy-containing unsaturated monomer, which causes the coating to dry slowly at room temperature or low temperatures such as in cold regions, resulting in insufficient water resistance and adhesion to topcoats. In addition, Patent Document 4 improves the water resistance of the coating by reducing the average particle size of the resin particles (to 50 nm or less), but the storage stability is insufficient.

[0009] Therefore, an object of the present invention is to provide an aqueous resin emulsion that is excellent in adhesion to substrates and topcoats, quick drying properties, water resistance, and storage stability. [Means for solving the problem]

[0010] In order to achieve the object of the present invention, the present invention has the following configuration: That is, an aqueous resin emulsion containing resin particles comprising an inner layer and a protective layer surrounding the inner layer, wherein the inner layer comprises a copolymer (A) containing a polymerizable monomer (a1) and a crosslinkable monomer (a2) as structural units, and the protective layer comprises at least a copolymer (B) containing a polymerizable monomer (b1) and a carboxyl group-containing polymerizable monomer (b2) as structural units, and a chain transfer agent, and the polymerizable monomer (a1) and the polymerizable monomer (b1) are selected from the group consisting of a (meth)acrylic acid alkyl ester monomer, a hydroxyl group-containing unsaturated ... the copolymer (A) contains at least one of the crosslinkable monomer (a2) in an amount of 0.1 to 15% by weight based on 100% by weight of all the monomers constituting the copolymer (A), the copolymer (B) contains the carboxyl group-containing polymerizable monomer (b2) in an amount of 5 to 20% by weight based on 100% by weight of all the monomers constituting the copolymer (B), the weight average molecular weight (Mw) of the copolymer (B) is 3,000 to 20,000, and the average particle diameter D of the copolymer (A) is A and the average particle diameter D of the resin particles B Ratio to (D A / D B ) is greater than 0 and not greater than 0.70, where the average particle size D A is measured by laser diffraction and scattering, and the average particle diameter D B is measured by dynamic light scattering. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an aqueous resin emulsion that is excellent in adhesion to substrates and topcoats, quick drying properties, water resistance, and storage stability. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram illustrating an outline of a resin particle. [Figure 2] FIG. 1 is a diagram illustrating how a resin particle emulsion penetrates into a substrate when DA / DB=0. [Figure 3]FIG. 1 is a diagram illustrating how a resin particle emulsion penetrates into a substrate when DA / DB=0.7. [Figure 4] FIG. 10 is a diagram illustrating how a resin particle emulsion penetrates into a substrate when DA / DB is greater than 0.7. [Figure 5] FIG. 1 is a diagram illustrating how a resin particle emulsion remains on a substrate when DA / DB=0. [Figure 6] FIG. 10 is a diagram illustrating how a resin particle emulsion remains on a substrate when DA / DB=0.7. [Figure 7] FIG. 10 is a diagram illustrating how a resin particle emulsion remains on a substrate when DA / DB is greater than 0.7. DETAILED DESCRIPTION OF THE INVENTION

[0013] The following describes the embodiments in detail. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more features among the multiple features described in the embodiments may be combined in any desired manner.

[0014] In this specification, a numerical range specified using "to" is intended to include the numerical values ​​before and after "to" as the range's lower and upper limits.

[0015] In this specification, the term "(meth)acrylic" is intended to include both the terms "acrylic" and "methacrylic." Similarly, the term "(meth)acrylate" is intended to include both the terms "acrylate" and "methacrylate." Examples of (meth)acrylic monomers include (meth)acrylic acid esters and (meth)acrylic acid, and (meth)acrylic acid may be salts. Of these, it is more preferable to use (meth)acrylic acid esters and (meth)acrylic acid, and it is even more preferable to use (meth)acrylic acid esters.

[0016] <Water-based resin emulsion> The aqueous resin emulsion contains resin particles that include an inner layer and a protective layer surrounding the inner layer. Such an aqueous resin emulsion can also be called a protective colloid emulsion. The inner layer is formed of copolymer (A). The protective layer is formed of copolymer (B). Here, FIG. 1 is a diagram illustrating an outline of the resin particles.

[0017] The resin particle 100 includes an inner layer 110 and a protective layer 120 surrounding the inner layer 110. Although FIG. 1 shows only one resin particle 100 for ease of explanation, multiple resin particles 100 are present in a dispersion medium (e.g., water). The inner layer 110 (copolymer (A)) is a high-molecular-weight polymer insoluble in the dispersion medium (water). The protective layer 120 (copolymer (B)) is a water-soluble resin neutralized with a basic compound. The protective layer 120 can function as a dispersion stabilizer. The average particle diameter 130 is the average particle diameter of the inner layer 110, and is the average particle diameter D described below. A The average particle diameter 140 is the average particle diameter of the resin particles 100 including the protective layer 120 surrounding the inner layer 110, and corresponds to the average particle diameter D B In this specification, the term "average particle diameter D B It should be noted that " does not represent the average particle size of the protective layer 120 alone without surrounding the inner layer 110.

[0018] The weight ratio (B / A) of the copolymer (A) to the copolymer (B) is 25 / 75 to 75 / 25. When the weight ratio (B / A) is within the above-mentioned range, the D A / D B On the other hand, if the weight ratio (B / A) is not within the range of the above-mentioned predetermined ratio, D A / D B If the ratio is not the desired ratio, only a part of the performance required for the aqueous resin emulsion can be realized.

[0019] Average particle size D of copolymer (A) A and the average particle diameter of the resin particles D B Ratio to (D A / D B ) is greater than 0 and less than 0.70. Here, the average particle diameter D A is measured by laser diffraction and scattering, and the average particle diameter D B is measured by dynamic light scattering. The average particle diameter D of 100 resin particles in the aqueous resin emulsion is measured by laser diffraction and scattering. A and the average particle diameter D measured by dynamic light scattering. B D is the ratio of A / D B The thickness of the protective layer 120 can be determined by measuring D. A / D B If the thickness of the protective layer 120 satisfies the condition that the ratio is 0.70 or less, the particles of the inner layer 110 can be stably dispersed, and therefore the storage stability of the aqueous resin emulsion is excellent. A / D B The manner in which resin particles 100 having different ratios permeate into an inorganic porous substrate (for example, calcium silicate board) will be described. Note that "calcium silicate board" is an abbreviation for calcium silicate board.

[0020] Figure 2(a) shows the D A / D B This shows the state before the resin particle emulsion is applied to the substrate when D = 0. A / D B When ρ = 0, the resin particles 100 have only the protective layer 120. The resin particles 100 are applied to a substrate 200. The substrate 200 is, for example, a calcium silicate board. FIG. 2(b) is a diagram showing the state after the resin particles 100 have penetrated into the substrate 200. Only the protective layer 120 is present in the substrate 200. This provides excellent reinforcement and adhesion to the substrate 200, but since there is no coating film on the substrate 200, adhesion to the topcoat paint and water resistance are poor.

[0021] Figure 3(a) shows the D A / D B This shows the state of the resin particle emulsion before it is applied to the substrate when D = 0.7. A / D BWhen ρ = 0.7, the resin particles 100 have both an inner layer 110 and a protective layer 120. The resin particles 100 are applied to a substrate 200. FIG. 3(b) shows the state after the resin particles 100 have penetrated into the substrate 200. The inner layer 110 is present on the substrate 200, and the protective layer 120 is present without gaps within the substrate 200. As shown in FIG. 3(c), a uniform film is formed without gaps between the particles of the inner layer 110 (high molecular weight polymer). As a result, the protective layer 120 penetrates uniformly into the substrate 200, providing excellent reinforcement and adhesion to the substrate 200, and the uniform film formed by the inner layer 100 on the substrate 200 provides good adhesion to the topcoat paint and water resistance.

[0022] Figure 4(a) shows the D A / D B This shows the state of the resin particle emulsion before it is applied to the substrate when D is greater than 0.7. A / D B = 0.7 or more, the resin particles 100 have both the inner layer 110 and the protective layer 120. The resin particles 100 are applied to the substrate 200. FIG. 4(b) shows the state after the resin particles 100 have penetrated into the substrate 200. The inner layer 110 is present on the substrate 200, and the protective layer 120 is present inside the substrate 200. However, the average particle diameter D A As a result, it is not possible to uniformly arrange the multiple protective layers 120 within the substrate 200, resulting in gaps between the protective layers 120. This reduces the reinforcement and adhesion of the substrate 200, but only improves adhesion to the topcoat paint and water resistance.

[0023] <Protective layer> The protective layer contains at least a copolymer (B) containing, as structural units, a polymerizable monomer (b1) and a carboxy group-containing polymerizable monomer (b2), and a chain transfer agent.

[0024] (Copolymer (B)) Copolymer (B) contains 5 to 20 wt% of the carboxyl group-containing polymerizable monomer (b2) based on 100 wt% of all monomers constituting copolymer (B). The acid content (the amount of the carboxyl group-containing polymerizable monomer) must be in the range of 5 to 20 wt% when all monomers constituting copolymer (B) are taken as 100 wt%. For example, if the acid content is less than 5 wt%, copolymer (B) will not become a water-soluble resin. On the other hand, if the acid content is more than 20 wt%, the drying of the coating film will be slow and adhesion to the substrate will be reduced.

[0025] (Polymerizable monomer (b1)) The copolymer (B) contains 80 to 95% by weight of the polymerizable monomer (b1) based on 100% by weight of all the monomers constituting the copolymer (B).

[0026] Copolymer (B) can contain 0 to 15 wt% of a styrene-based monomer as a polymerizable monomer (b1) based on 100 wt% of all monomers constituting copolymer (B). Examples of styrene-based monomers include styrene, α-methylstyrene, chlorostyrene, methylstyrene, and t-butylstyrene. If copolymer (B) is produced using more than 15 wt% of a styrene-based monomer, the copolymer (B) will be more hydrophobic, making it difficult for the water-soluble resin neutralized from copolymer (B) to dissolve in water (i.e., the dispersion stabilization function of the protective layer will be reduced). Therefore, when a styrene-based monomer is used as polymerizable monomer (b1), it is preferably used in an amount of 15 wt% or less. That is, copolymer (B) can contain 15 wt% or less of a styrene-based monomer as a polymerizable monomer (b1) based on 100 wt% of all monomers constituting copolymer (B).

[0027] The polymerizable monomer (b1) includes at least one of a (meth)acrylic acid alkyl ester monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, and a piperidyl group-containing unsaturated monomer.

[0028] Examples of the (meth)acrylic acid alkyl ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, and isopropyl (meth)acrylate. Examples of suitable alkyl (meth)acrylates include alkyl (meth)acrylates having a linear or branched alkyl group, such as decyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; and alicyclic alkyl (meth)acrylates, such as cyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyl (meth)acrylate. One or more of these alkyl (meth)acrylates may be used. Among these, alkyl (meth)acrylates having a linear or branched alkyl group with 1 to 18 carbon atoms (more preferably 1 to 12 carbon atoms) are preferred.

[0029] Other (meth)acrylic acid ester monomers include, for example, polyalkylene glycol (meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and methoxypolyethylene glycol mono(meth)acrylate; (meth)acrylic acid alkyl esters having a halogen atom such as 2-chloroethyl (meth)acrylate, trifluoroethyl (meth)acrylate, 2-(perfluorobutyl)ethyl (meth)acrylate, and perfluorooctylethyl (meth)acrylate; (meth)acrylic acid esters having an amino group such as 2-(dimethylamino)ethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, and 3-(dimethylamino)propyl (meth)acrylate; and (meth)acrylic acid esters having a carboxy group such as carboxyethyl (meth)acrylate and carboxypentyl (meth)acrylate. Examples of such esters include (meth)acrylic acid esters and derivatives thereof having an epoxy group, such as glycidyl (meth)acrylate, glycerin mono(meth)acrylate, 2-methylglycidyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate; (meth)acrylates having a sulfonic acid group, such as 2-sulfoethyl (meth)acrylate and 3-sulfopropyl (meth)acrylate; (meth)acrylates having a phosphoric acid group, such as 2-(phosphonooxy)ethyl (meth)acrylate; (meth)acrylates having an isocyanate group, such as 2-isocyanatoethyl (meth)acrylate; (meth)acrylates having a heterocyclic ring, such as tetrahydrofurfuryl (meth)acrylate; and polyalkylene glycol mono(meth)acrylates terminated with an alkyl group or an aryl group, such as methoxypolyethylene glycol (meth)acrylate and phenoxypolyethylene glycol (meth)acrylate. These may be used alone or in combination.

[0030] Examples of hydroxyl group-containing unsaturated monomers 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, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. One or more of these can be used.

[0031] Examples of the amide group-containing unsaturated monomer include unsaturated monomers having a cyano group, such as acrylonitrile and methacrylonitrile; and acrylamide monomers, such as (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-[2-dimethylaminoethyl](meth)acrylamide, N-[3-dimethylaminopropyl](meth)acrylamide, diacetone acrylamide, 4-acryloylmorpholine, and 4-methacryloylmorpholine. These may be used alone or in combination.

[0032] Examples of the piperidyl group-containing unsaturated monomer include 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and 2,2,6,6-tetramethyl-4-piperidyl methacrylate, and one or more members selected from this group can be used.

[0033] (Carboxy group-containing polymerizable monomer (b2)) Examples of the carboxyl group-containing polymerizable monomer (b2) include unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and citraconic acid; unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride; and unsaturated carboxylic acid monoesters such as maleic acid monomethyl ester, maleic acid monobutyl ester, itaconic acid monomethyl ester, and itaconic acid monobutyl ester. It is more preferable to use one or more of these unsaturated carboxylic acid monomers. Among these, (meth)acrylic acid is even more preferable.

[0034] (Crosslinking monomer (b3)) The copolymer (B) may further contain a crosslinkable monomer (b3) as a constituent unit. The crosslinkable monomer (b3) is an optional component and may be contained, for example, in an amount of 0 to 5% by weight based on 100% by weight of all the monomers constituting the copolymer (B). The crosslinkable monomer (b3) includes at least one of a polyfunctional monomer and a silane coupling agent.

[0035] As the polyfunctional monomer, a monomer having two or more polymerizable unsaturated bonds can be used. Examples of the polyfunctional monomer include 2-hydroxy-3-acryloyloxypropyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and dipropylene glycol di(meth)acrylate. Examples of the acrylate include bifunctional (meth)acrylates such as (meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, and glycerin di(meth)acrylate; polyfunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate; allyl (meth)acrylate; divinylbenzene; and diallyl phthalate. One or more of these can be used.

[0036] Examples of the crosslinkable monomer include silane coupling agents such as vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-acryloxypropyltrimethoxysilane, and one or more of these can be used.

[0037] The crosslinkable monomer can be appropriately selected depending on the type of reactive group. For example, when the reactive group is a carbonyl group, it is preferable to use a polyfunctional hydrazide compound or the like as a crosslinking agent. When the reactive group is a carboxy group, it is preferable to use a polyfunctional epoxy compound, a polyfunctional carbodiimide compound, a melamine-based crosslinking agent such as methylolmelamine, a polyfunctional oxazoline compound, a polyvalent metal, or the like as a crosslinking agent. When the reactive group is a phosphoric acid group or a phosphoric acid ester group, it is preferable to use a compound having many hydroxyl groups as a crosslinking agent. When the reactive group is a hydroxyl group, it is preferable to use a polyfunctional isocyanate compound, its blocked isocyanate, acid anhydride, or the like as a crosslinking agent. When the reactive group is a glycidyl group, it is preferable to use a polyfunctional carboxy group-containing compound, polyamine, acid anhydride, or the like as a crosslinking agent. When the reactive group is an isocyanate group or a blocked isocyanate group, it is preferable to use a polyol, polyamine, polycarboxylic acid compound, or the like as a crosslinking agent. One or more of these reactive groups can be used.

[0038] Examples of polymerizable monomers having a carbonyl group as a reactive group include acrolein, diacetone (meth)acrylamide, diacetone (meth)acrylate, and acetoacetoxyethyl (meth)acrylate, etc. One or more of these can be used.

[0039] Examples of polymerizable monomers having a carboxy group as a reactive group, i.e., carboxy group-containing polymerizable monomers, include unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and citraconic acid; and monoesters of unsaturated carboxylic acids such as maleic acid monomethyl ester, maleic acid monobutyl ester, itaconic acid monomethyl ester, and itaconic acid monobutyl ester. Furthermore, the carboxy group-containing polymerizable monomer may be one that generates a carboxy group when dissolved in water, such as anhydrides of unsaturated carboxylic acids such as maleic anhydride and itaconic anhydride. One or more of these may be used.

[0040] Examples of polymerizable monomers having a phosphoric acid group or a phosphoric acid ester group as a reactive group include (meth)acrylates having a phosphoric acid group, such as 2-(phosphonooxy)ethyl (meth)acrylate, etc. One or more of these can be used.

[0041] Examples of polymerizable monomers having a hydroxyl group as a reactive group include hydroxyl group-containing (meth)acrylic acid esters such as 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, glycerin mono(meth)acrylate, 4-hydroxyphenyl (meth)acrylate, and [4-(hydroxymethyl)cyclohexyl]methyl (meth)acrylate. One or more of these can be used.

[0042] Examples of polymerizable monomers having an isocyanate group or a blocked isocyanate group as a reactive group include (meth)acrylates having an isocyanate group, such as 2-isocyanatoethyl (meth)acrylate and 2-(2-methacryloyloxyethyloxy)ethyl isocyanate, etc. One or more of these can be used.

[0043] Examples of polymerizable monomers having a glycidyl group as a reactive group include glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate, and one or more of these can be used.

[0044] (chain transfer agent) Copolymer (B) contains 0.1 to 15.0% by weight of a chain transfer agent relative to 100% by weight of all monomers constituting copolymer (B). Furthermore, by incorporating the above-mentioned predetermined amount of chain transfer agent into copolymer (B), the weight average molecular weight (Mw) of copolymer (B) can be controlled to 3,000 to 20,000, thereby improving the impregnation ability into the substrate. The chain transfer agent is not particularly limited, and may be one or more alkyl mercaptans such as hexyl mercaptan, lauryl mercaptan, octyl mercaptan, n-dodecyl mercaptan, and t-dodecyl mercaptan.

[0045] (hydrophilic solvent) Examples of hydrophilic solvents that can be used include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and tert-amyl alcohol; polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and glycerin; ketones such as acetone, methyl ethyl ketone, and diacetone alcohol; and ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether. The use of a hydrophilic solvent during the polymerization reaction of the polymerizable monomer (b1) or the like can adjust the molecular weight of the copolymer (B) and penetrate into the molecular chain, thereby assisting in the water-solubilization of the copolymer (B).

[0046] (Physical properties of copolymer (B)) The pH of copolymer (B) is 7.0 to 10.5. Here, to convert copolymer (B) into a water-soluble resin, copolymer (B) is neutralized with a basic compound 30 minutes after the end of polymerization. By adjusting the pH of copolymer (B) to the range of 7.0 to 10.5, the particles of copolymer (B) are converted into a water-soluble resin. Here, if copolymer (B) is not properly converted into a water-soluble resin, copolymer (A) cannot be encapsulated, and adhesion to the topcoat paint cannot be exhibited.

[0047] The haze of copolymer (B) is 0 to 25%. As a guide for making copolymer (B) a water-soluble resin, if the haze of copolymer (B) after neutralization (with ion-exchanged water as the standard: 0) is in the range of 0 to 25%, copolymer (B) functions as a protective layer.

[0048] The weight-average molecular weight (Mw) of the copolymer (B) is 3,000 to 20,000. Having the weight-average molecular weight (Mw) of the copolymer (B) within the above range enhances the ability of the copolymer (B) to impregnate the substrate. If the weight-average molecular weight (Mw) of the copolymer (B) is less than 3,000, the functionality of the protective layer is reduced, making it impossible to form the final aqueous resin particle emulsion. On the other hand, if the weight-average molecular weight (Mw) of the copolymer (B) is greater than 20,000, the copolymer (B) becomes less soluble in water, making it difficult to form a water-soluble resin, resulting in reduced ability to impregnate the substrate. If a water-soluble resin in which a high-molecular-weight copolymer (B) is dissolved in water is impregnated into a substrate, the high cohesive force of the copolymer (B) can cause damage to the substrate. Thus, if the weight-average molecular weight (Mw) of the copolymer (B) is greater than 20,000, there is a problem of reduced adhesion to the substrate.

[0049] Average particle diameter D B The average particle size D is 50 to 300 nm. B If is smaller than 50 nm, D A / D B If the average particle diameter D is greater than 0 and less than 0.70, the protective layer becomes smaller than the core (inner layer), and the particles in the inner layer cannot be dispersed. More specifically, in the above case, aggregation and sedimentation are observed in a storage stability test at 50°C. On the other hand, B If is greater than 300 nm, D A / D B When the particle size of the core (inner layer) is greater than 0 and less than 0.70, the particle size of the core (inner layer) will be a maximum of 210 nm or more, which will result in poor water resistance on substrates that the water-based sealer penetrates. There is no particular problem with the protective layer, as it penetrates into the substrate, but if the particle size of the core (inner layer) that forms a film on the substrate is greater than 210 nm, the interparticle spots will become too large, which will have a negative effect on water resistance.

[0050] (Method for producing copolymer (B)) The copolymer (B) is produced by emulsifying and dispersing any combination of the polymerizable monomer (b1) to the crosslinkable monomer (b3) in an aqueous dispersion medium. Examples of the emulsifying and dispersing method include known emulsion polymerization.

[0051] (aqueous dispersion medium) Examples of aqueous dispersion media include water, mixed solvents in which water is mixed with alcohol (e.g., methanol, ethanol, etc.), and water-soluble solvents such as alcohols and glycol ethers, and one or more solvents selected from this group can be used.

[0052] (emulsifier) When polymerizing the polymerizable monomer (b1), etc., a surfactant can be used as an emulsifier. The emulsifier to be used is not particularly limited, but examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants, and one or more of these can be used. In the present invention, it is preferable to use an anionic surfactant or a nonionic surfactant, and it is more preferable to use an anionic surfactant.

[0053] (polymerization initiator, polymerization accelerator) A polymerization initiator can be used when polymerizing the polymerizable monomer (b1) or the like. The polymerization initiator is not particularly limited, but examples thereof include persulfates, organic peroxides, peroxides such as hydrogen peroxide, and azo compounds, and one or more of these can be used. Furthermore, a redox polymerization initiator can be used in combination with a peroxide, or one or more reducing agents can be used as a polymerization accelerator.

[0054] Specific examples of persulfates include potassium persulfate, sodium persulfate, and ammonium persulfate. Specific examples of organic peroxides include diacyl peroxides such as benzoyl peroxide and dilauroyl peroxide, dialkyl peroxides such as t-butylcumyl peroxide and dicumyl peroxide, peroxyesters such as t-butyl peroxylaurate and t-butyl peroxybenzoate, and hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide. Specific examples of azo compounds include 2,2'-azobis(2-amidinopropane) dihydrochloride and 4,4'-azobis(4-cyanopentanoic acid).

[0055] The reducing agent as a polymerization accelerator is not particularly limited, but examples thereof include ascorbic acid and its salts, erythorbic acid and its salts, tartaric acid and its salts, sulfurous acid and its salts, bisulfurous acid and its salts, thiosulfuric acid and its salts, and iron(II) salts.

[0056] (basic compounds) Examples of basic compounds used to neutralize the carboxyl group derived from the carboxyl group-containing polymerizable monomer (b2) include amines such as ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, and dimethylaminoethanol; aminoalcohols such as 1-amino-2-propanol, 2-amino-2-methyl-1-propanol, and N,N-dimethylaminoethanol; and alkali metal hydroxides such as potassium hydroxide and sodium hydroxide. One or more of these may be used.

[0057] (Other additives) A crosslinking agent may be used as needed so long as the weight average molecular weight (Mw) of the copolymer (B) is in the range of 3000 to 20000. The use of a crosslinking agent can improve the substrate adhesion and water resistance of the aqueous resin emulsion.

[0058] <Inner layer> The inner layer contains a copolymer (A) containing a polymerizable monomer (a1) and a crosslinkable monomer (a2) as structural units. The incorporation of a crosslinking agent (crosslinkable monomer (a2)) into the copolymer (A) makes the copolymer (A) hydrophobic, thereby providing a coating film on the substrate with water resistance and adhesion to a topcoat. Another advantage is that the copolymer (A) is encapsulated within a highly hydrophilic protective layer (copolymer (B)).

[0059] (Copolymer (A)) The copolymer (A) contains 85 to 99.9% by weight of the polymerizable monomer (a1) and 0.1 to 15% by weight of the crosslinkable monomer (a2) based on 100% by weight of all the monomers constituting the copolymer (A).

[0060] (Polymerizable monomer (a1)) Copolymer (A) can contain 0 to 15 wt% of a styrene-based monomer as a polymerizable monomer (a1) based on 100 wt% of all monomers constituting copolymer (A). Examples of styrene-based monomers include styrene, α-methylstyrene, chlorostyrene, methylstyrene, and t-butylstyrene. If copolymer (A) is produced using more than 15 wt% of a styrene-based monomer, the structural strength of copolymer (A) increases, but the coating film may become too hard, resulting in reduced substrate adhesion (substrate breakage). Therefore, when a styrene-based monomer is used as polymerizable monomer (a1), it is preferably used in an amount of 15 wt% or less. That is, copolymer (A) can contain 15 wt% or less of a styrene-based monomer as a polymerizable monomer (a1) based on 100 wt% of all monomers constituting copolymer (A).

[0061] The polymerizable monomer (a1) includes at least one of a (meth)acrylic acid alkyl ester monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, and a piperidyl group-containing unsaturated monomer.

[0062] Examples of the (meth)acrylic acid alkyl ester monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, and isopropyl (meth)acrylate. Examples of suitable alkyl (meth)acrylates include alkyl (meth)acrylates having a linear or branched alkyl group, such as decyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; and alicyclic alkyl (meth)acrylates, such as cyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyl (meth)acrylate. One or more of these alkyl (meth)acrylates may be used. Among these, alkyl (meth)acrylates having a linear or branched alkyl group with 1 to 18 carbon atoms (more preferably 1 to 12 carbon atoms) are preferred.

[0063] Other (meth)acrylic acid ester monomers include, for example, polyalkylene glycol (meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and methoxypolyethylene glycol mono(meth)acrylate; (meth)acrylic acid alkyl esters having a halogen atom such as 2-chloroethyl (meth)acrylate, trifluoroethyl (meth)acrylate, 2-(perfluorobutyl)ethyl (meth)acrylate, and perfluorooctylethyl (meth)acrylate; (meth)acrylic acid esters having an amino group such as 2-(dimethylamino)ethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, and 3-(dimethylamino)propyl (meth)acrylate; and (meth)acrylic acid esters having a carboxy group such as carboxyethyl (meth)acrylate and carboxypentyl (meth)acrylate. Examples of such esters include (meth)acrylic acid esters and derivatives thereof having an epoxy group, such as glycidyl (meth)acrylate, glycerin mono(meth)acrylate, 2-methylglycidyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate; (meth)acrylates having a sulfonic acid group, such as 2-sulfoethyl (meth)acrylate and 3-sulfopropyl (meth)acrylate; (meth)acrylates having a phosphoric acid group, such as 2-(phosphonooxy)ethyl (meth)acrylate; (meth)acrylates having an isocyanate group, such as 2-isocyanatoethyl (meth)acrylate; (meth)acrylates having a heterocyclic ring, such as tetrahydrofurfuryl (meth)acrylate; and polyalkylene glycol mono(meth)acrylates terminated with an alkyl group or an aryl group, such as methoxypolyethylene glycol (meth)acrylate and phenoxypolyethylene glycol (meth)acrylate. These may be used alone or in combination.

[0064] Examples of hydroxyl group-containing unsaturated monomers 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, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. One or more of these can be used.

[0065] Examples of the amide group-containing unsaturated monomer include unsaturated monomers having a cyano group, such as acrylonitrile and methacrylonitrile; and acrylamide monomers, such as (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-[2-dimethylaminoethyl](meth)acrylamide, N-[3-dimethylaminopropyl](meth)acrylamide, diacetone acrylamide, 4-acryloylmorpholine, and 4-methacryloylmorpholine. These may be used alone or in combination.

[0066] Examples of the piperidyl group-containing unsaturated monomer include 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and 2,2,6,6-tetramethyl-4-piperidyl methacrylate, and one or more members selected from this group can be used.

[0067] (Crosslinkable monomer (a2)) The crosslinkable monomer (a2) includes at least one of a polyfunctional monomer and a silane coupling agent.

[0068] As the polyfunctional monomer, a monomer having two or more polymerizable unsaturated bonds can be used. Examples of the polyfunctional monomer include 2-hydroxy-3-acryloyloxypropyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and dipropylene glycol di(meth)acrylate. Examples of the acrylate include bifunctional (meth)acrylates such as (meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, and glycerin di(meth)acrylate; polyfunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate; allyl (meth)acrylate; divinylbenzene; and diallyl phthalate. One or more of these can be used.

[0069] Examples of the crosslinkable monomer (a2) include silane coupling agents such as vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-acryloxypropyltrimethoxysilane, and one or more of these can be used.

[0070] The crosslinkable monomer (a2) can be appropriately selected depending on the type of reactive group. For example, when the reactive group is a carbonyl group, it is preferable to use a polyfunctional hydrazide compound or the like as a crosslinking agent. When the reactive group is a carboxyl group, it is preferable to use a polyfunctional epoxy compound, a polyfunctional carbodiimide compound, a melamine-based crosslinking agent such as methylolmelamine, a polyfunctional oxazoline compound, a polyvalent metal, or the like as a crosslinking agent. When the reactive group is a phosphoric acid group or a phosphoric acid ester group, it is preferable to use a compound having many hydroxyl groups as a crosslinking agent. When the reactive group is a hydroxyl group, it is preferable to use a polyfunctional isocyanate compound, its blocked isocyanate, acid anhydride, or the like as a crosslinking agent. When the reactive group is a glycidyl group, it is preferable to use a polyfunctional carboxyl group-containing compound, polyamine, acid anhydride, or the like as a crosslinking agent. When the reactive group is an isocyanate group or a blocked isocyanate group, it is preferable to use a polyol, polyamine, polycarboxylic acid compound, or the like as a crosslinking agent. One or more of these reactive groups can be used.

[0071] Examples of polymerizable monomers having a carbonyl group as a reactive group include acrolein, diacetone (meth)acrylamide, diacetone (meth)acrylate, and acetoacetoxyethyl (meth)acrylate, etc. One or more of these can be used.

[0072] Examples of polymerizable monomers having a carboxy group as a reactive group, i.e., carboxy group-containing polymerizable monomers, include unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and citraconic acid; and monoesters of unsaturated carboxylic acids such as maleic acid monomethyl ester, maleic acid monobutyl ester, itaconic acid monomethyl ester, and itaconic acid monobutyl ester. Furthermore, the carboxy group-containing polymerizable monomer may be one that generates a carboxy group when dissolved in water, such as anhydrides of unsaturated carboxylic acids such as maleic anhydride and itaconic anhydride. One or more of these may be used.

[0073] Examples of polymerizable monomers having a phosphoric acid group or a phosphoric acid ester group as a reactive group include (meth)acrylates having a phosphoric acid group, such as 2-(phosphonooxy)ethyl (meth)acrylate, etc. One or more of these can be used.

[0074] Examples of polymerizable monomers having a hydroxyl group as a reactive group include hydroxyl group-containing (meth)acrylic acid esters such as 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, glycerin mono(meth)acrylate, 4-hydroxyphenyl (meth)acrylate, and [4-(hydroxymethyl)cyclohexyl]methyl (meth)acrylate. One or more of these can be used.

[0075] Examples of polymerizable monomers having an isocyanate group or a blocked isocyanate group as a reactive group include (meth)acrylates having an isocyanate group, such as 2-isocyanatoethyl (meth)acrylate and 2-(2-methacryloyloxyethyloxy)ethyl isocyanate, etc. One or more of these can be used.

[0076] Examples of polymerizable monomers having a glycidyl group as a reactive group include glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate, and one or more of these can be used.

[0077] (Method for producing copolymer (A)) The copolymer (A) is produced by emulsifying and dispersing the polymerizable monomer (a1) and the crosslinkable monomer (a2) in an aqueous dispersion medium. Examples of the emulsifying and dispersing method include known emulsion polymerization.

[0078] (aqueous dispersion medium) Examples of aqueous dispersion media include water, mixed solvents in which water is mixed with alcohol (e.g., methanol, ethanol, etc.), and water-soluble solvents such as alcohols and glycol ethers, and one or more solvents selected from this group can be used.

[0079] (emulsifier) When polymerizing the polymerizable monomer (a1) or the like, a surfactant can be used as an emulsifier. The emulsifier to be used is not particularly limited, but examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants, and one or more of these can be used. In the present invention, it is preferable to use an anionic surfactant or a nonionic surfactant, and it is more preferable to use an anionic surfactant.

[0080] (polymerization initiator, polymerization accelerator) A polymerization initiator can be used when polymerizing the polymerizable monomer (a1) and the like. The polymerization initiator is not particularly limited, but examples thereof include persulfates, organic peroxides, peroxides such as hydrogen peroxide, and azo compounds, and one or more of these can be used. Furthermore, a redox polymerization initiator can be used in combination with a peroxide, or one or more reducing agents can be used as a polymerization accelerator.

[0081] Specific examples of persulfates include potassium persulfate, sodium persulfate, and ammonium persulfate. Specific examples of organic peroxides include diacyl peroxides such as benzoyl peroxide and dilauroyl peroxide, dialkyl peroxides such as t-butylcumyl peroxide and dicumyl peroxide, peroxyesters such as t-butyl peroxylaurate and t-butyl peroxybenzoate, and hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide. Specific examples of azo compounds include 2,2'-azobis(2-amidinopropane) dihydrochloride and 4,4'-azobis(4-cyanopentanoic acid).

[0082] The reducing agent as a polymerization accelerator is not particularly limited, but examples thereof include ascorbic acid and its salts, erythorbic acid and its salts, tartaric acid and its salts, sulfurous acid and its salts, bisulfurous acid and its salts, thiosulfuric acid and its salts, and iron(II) salts.

[0083] <Applications of water-based resin emulsion> The aqueous resin emulsion has both a sealer application and a primer application. For example, the aqueous resin emulsion can be used both as an aqueous sealer application (for inorganic building materials such as western roof tiles, calcium silicate boards, aged slate roofs, various ceramic roofing materials, and old paint films) and as a primer application.

[0084] Conventional water-based sealers have only been used for either sealing (reinforcing impregnated substrates and providing substrate adhesion (anchor effect)) or primer (reducing topcoat absorption and improving adhesion to topcoats). This meant that users had to prepare two types of water-based sealers, one for sealing and one for priming, and then use them interchangeably during repair work. This increased sealer management and workload was a hassle for users. Furthermore, the substrates to which water-based sealers are applied are generally inorganic porous substrates, and the permeability of the sealer varies depending on the number of voids (large or small) in the inorganic porous substrate. This means that when the type of inorganic porous substrate (e.g., the size and number of voids) changes, conventional water-based sealers may not be able to provide sufficient sealing performance, or may not be able to provide sealing performance at all.

[0085] On the other hand, the aqueous resin emulsion of the present invention is a sealer that can be used as both a sealer and a primer, thereby reducing the burden on users on sealer management and operation. Furthermore, the aqueous resin emulsion of the present invention has the following characteristics so that it can exhibit sufficient sealing performance even when the type of inorganic porous substrate to which the aqueous sealer is applied changes. That is, by taking the form of a protective colloid-type emulsion, the aqueous resin emulsion can adequately seal and reinforce inorganic porous substrates having various voids. A protective colloid-type emulsion refers to a resin particle emulsion containing a water-soluble resin (first protective layer) obtained by neutralizing a high-acid-value emulsion and a water-insoluble high-molecular-weight polymer (second inner layer) formed therein.

[0086] The mechanism by which the aqueous resin emulsion of the present invention penetrates into a calcium silicate board (a substrate into which an aqueous sealer easily penetrates) as an example of an inorganic porous substrate has been explained using FIGS. 2 to 4, but a supplementary explanation will be given below.

[0087] First, the first layer of water-soluble resin impregnates the calcium silicate board, reinforcing it and improving adhesion to the board. In this way, the water-soluble resin exerts a sealing effect. Next, the second layer of high-molecular-weight polymer that remains without impregnating the calcium silicate board exerts a primer effect, improving adhesion to the top coat of paint.

[0088] Meanwhile, the mechanism by which the aqueous resin emulsion of the present invention forms a coating film on a slate board (a substrate into which an aqueous sealer does not easily or does not penetrate) as an example of an inorganic porous substrate will be described with reference to Figs. 5 to 7.

[0089] First, Figure 5(a) shows the D A / D B This shows the state before the resin particle emulsion is applied to the substrate when D = 0. A / D B When ρ = 0, the resin particles 100 have only the protective layer 120. The resin particles 100 are applied to a substrate 300. The substrate 300 is, for example, a slate board. FIG. 5(b) is a diagram showing the state in which the resin particles 100 remain on the substrate 300. Because the resin particles 100 do not penetrate the substrate 300, only the protective layer 120 remains on the substrate 300. In the state shown in FIG. 5(b), the protective layer 120 (water-soluble resin) does not dry, and the protective layer 120, which has strong water retention, absorbs water. As a result, when the resin particle emulsion of FIG. 5 is applied to a substrate that is difficult or does not penetrate, the film-forming properties, adhesion to the topcoat paint, and water resistance are poor.

[0090] Figure 6(a) shows the D A / D B This shows the state of the resin particle emulsion before it is applied to the substrate when D = 0.7. A / D B When ρ=0.7, the resin particles 100 have both the inner layer 110 and the protective layer 120. The resin particles 100 are applied to the substrate 300. Fig. 6(b) is a diagram showing the state in which the resin particles 100 remain on the substrate 300.

[0091] The first protective layer 120 (water-soluble resin) barely penetrates the substrate 300 (slate board), remaining on the substrate 300 (slate board) along with the second inner layer 110 (high-molecular-weight polymer). However, because the water-soluble resin has high water retention and does not take a particulate form, it acts as an aid in particle fusion of the second layer copolymer (A), i.e., the high-molecular-weight polymer. As a result, as shown in Figure 6(c), a uniform film is formed with no gaps between the particles of the inner layer 110 (high-molecular-weight polymer), resulting in excellent water resistance, adhesion to the topcoat paint, and the aesthetic appearance of the coated product (slate board).

[0092] Figure 7(a) shows the D A / D B This shows the state of the resin particle emulsion before it is applied to the substrate when D is greater than 0.7. A / D B = 0.7 or greater, the resin particles 100 have both an inner layer 110 and a protective layer 120. The resin particles 100 are applied to a substrate 300. FIG. 7(b) shows the state of the resin particles 100 remaining on the substrate 300. Compared to the resin particles 100 in FIG. 6, the resin particles 100 in FIG. 7(b) have an inner layer 110 with a larger average particle diameter 130 and a protective layer 120 that is thinner and less than a predetermined amount. Therefore, the protective layer 120 (water-soluble resin) cannot promote particle fusion in the inner layer 110, making it difficult to form a uniform film on the substrate 300 without gaps between the inner layers 110. Therefore, when the resin particle emulsion in FIG. 7 is applied to a substrate that is difficult or impossible to penetrate, the film-forming properties, adhesion to a topcoat paint, and water resistance are poor.

[0093] As described above, the aqueous resin emulsion of the present invention can fully exert its effects as a sealer and / or primer for various inorganic porous substrates having different permeabilities, and therefore has the excellent effect of being able to serve the dual roles of a sealer and a primer.

[0094] <Painted products> The coated article comprises a substrate and a coating film formed from an aqueous resin emulsion provided on at least one surface of the substrate. The aqueous resin emulsion is the aqueous resin emulsion described above.

[0095] The gel fraction of the coating film is 50 to 100%. Here, the level of water resistance can be determined by preparing a coating film of the aqueous resin emulsion (a film formed by drying the aqueous resin emulsion) and measuring the gel fraction of the coating film. If the gel fraction of the coating film is less than 50%, the coating film will have poor water resistance and will exhibit blisters and peeling, resulting in reduced adhesion to the substrate.

[0096] (base material) The substrate includes an inorganic porous substrate, such as a calcium silicate board, a wood-chip cement board, a pulp cement board, a siding board, or a deteriorated old coating (such as deteriorated roof tiles or deteriorated Colonial (registered trademark)), which is easily permeable to the aqueous resin emulsion, or a slate board (flexible board), a roof tile, or a galvanized iron sheet, which is difficult to permeate with the aqueous resin emulsion.

[0097] <Method for producing aqueous resin emulsion> The method for producing an aqueous resin emulsion includes at least the following three steps: polymerizing 80 to 95% by weight of polymerizable monomer (b1) and 5 to 20% by weight of carboxyl group-containing polymerizable monomer (b2) in an aqueous medium in the presence of a surfactant, a polymerization initiator, and a chain transfer agent to produce copolymer (B), neutralizing copolymer (B) with a basic compound, and polymerizing 85 to 99.9% by weight of polymerizable monomer (a1) and 0.1 to 15% by weight of crosslinkable monomer (a2) in an aqueous solution of the neutralized copolymer (B) to produce copolymer (A). Polymerizable monomer (a1) and polymerizable monomer (b1) include at least one of a (meth)acrylic acid alkyl ester monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, and a piperidyl group-containing unsaturated monomer. The weight average molecular weight (Mw) of the copolymer (B) is 3,000 to 20,000. The average particle diameter D of the copolymer (A) A and the average particle diameter of the resin particles DB Ratio to (D A / D B ) is greater than 0 and less than 0.70. Here, the average particle diameter D A is measured by laser diffraction and scattering, and the average particle diameter D B is measured by a dynamic light scattering method. Note that the specific configuration and properties of the aqueous resin emulsion have been described above, and therefore detailed description thereof will be omitted.

[0098] The method for producing the aqueous resin emulsion will be described below. Table 1 shows the raw material composition and physical properties of Examples 1 to 7. Table 2 shows the raw material composition and physical properties of Examples 8 to 14. Table 3 shows the raw material composition and physical properties of Examples 15 to 17 and Comparative Examples 1 to 4. Table 4 shows the raw material composition and physical properties of Comparative Examples 5 to 11.

[0099] [Table 1]

[0100] [Table 2]

[0101] [Table 3]

[0102] [Table 4]

[0103] (Example 1: Method for producing copolymer (B)) 21.8 parts of ion-exchanged water, 2.0 parts of polyoxyethylene alkyl ether sodium sulfate (Kao Corporation, trade name: Latemul E-118B) as an emulsifier, 6.5 parts of cyclohexyl methacrylate and 15 parts of methyl methacrylate as polymerizable monomers (b1), 3.5 parts of methacrylic acid (100%) as a carboxyl group-containing polymerizable monomer (b2), 1.5 parts of ISO-propyl alcohol as a hydrophilic solvent, and 1.5 parts of n-dodecyl mercaptan as a chain transfer agent were weighed and stirred. In this way, an emulsified mixture (1) containing the monomers constituting the copolymer (B) was prepared.

[0104] A 2 L three-necked round-bottom flask equipped with a stirrer, reflux condenser, thermometer, dropping device, and nitrogen gas inlet tube was charged with 52.5 parts of ion-exchanged water and 0.3 parts of polyoxyethylene alkyl ether sodium sulfate (Kao Corporation, trade name: Latemul E-118B). The air in the flask was replaced with nitrogen gas, and the flask's internal temperature was heated to 80 ° C. with stirring. Next, 4.0 parts of a 5% aqueous ammonium persulfate solution (Mitsubishi Gas Chemical Company, Inc., trade name: Ammonium Persulfate) was added to the flask, and immediately the previously prepared emulsified mixture (1) and 1.0 part of a 5% aqueous ammonium persulfate solution were added dropwise over 1.0 hour. After 30 minutes, 4.4 parts of triethanolamine were added, and the mixture was left at 80 ° C. for 30 minutes to obtain copolymer (B).

[0105] (Example 1: Method for producing copolymer (A)) 41.7 parts of ion-exchanged water, 2.5 parts of polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon KH-10) as an emulsifier, 34.5 parts of 2-ethylhexyl acrylate, 19 parts of cyclohexyl methacrylate, and 21 parts of methyl methacrylate as polymerizable monomers (a1), and 0.5 parts of trimethylolpropane trimethacrylate as a crosslinkable monomer (a2) were weighed and stirred. In this way, an emulsified mixed liquid (2) containing the monomers constituting the copolymer (A) was prepared.

[0106] (Example 1: Method for producing aqueous resin emulsion) Sixty minutes after the completion of the dropwise addition of the emulsified mixture (1), the prepared emulsified mixture (2) and 3.0 parts of 5% ammonium persulfate were added dropwise to the flask over a period of 3.0 hours. The reaction was continued for another 3.0 hours while maintaining the internal temperature of the flask at 80°C. The internal temperature was then cooled to room temperature, and the pH was adjusted to approximately 8.5 with ammonia (25%) and water, and the solid content was adjusted to 35.0%, followed by filtration to remove aggregates. This yielded the aqueous resin emulsion of Example 1, which contained resin particles with a protective layer (copolymer (B)) surrounding an inner layer (copolymer (A)). The physical properties of the aqueous resin emulsion were analyzed: viscosity: 10 mPa·s / 25°C, solid content: 35.0%, pH: 8.5, and average particle diameter D measured by dynamic light scattering. B Here, the method for analyzing the physical properties of the copolymer (A / B) and the aqueous resin emulsion will be explained.

[0107] (Measurement of weight average molecular weight (Mw) of copolymer (B)) The weight average molecular weight (Mw) of the copolymer (B) was measured using GPC (gel permeation chromatography) under the following measurement conditions. Measurement conditions Analytical equipment: Tosoh HLC-8120GPC Column: Shodex KF-G (guard column) + KF-806M x 2 Column temperature: 40℃ ·Flow rate: 1.0ml / min ·Injection volume: 100μl Mobile phase: tetrahydrofuran (THF) Detector: Differential refractive index detector (RI) Standard sample: Polystyrene

[0108] (Measurement of Haze of Copolymer (B)) The haze of the copolymer (B) was measured by the following measurement and calculation methods. Haze meter: Nippon Denshoku Industries Co., Ltd., NDH4000 model Haze (diffuse transmittance / total light transmittance x 100%)

[0109] (Average particle diameter D of copolymer (A) measured by laser diffraction / scattering method) A (measurement of Average particle size D of resin particles in aqueous resin emulsion measured by laser diffraction and scattering method A Specifically, the particle size distribution measuring device (Shimadzu Corporation, product name "Laser Diffraction Nanoparticle Size Distribution Measuring Device SALD-7100") that utilizes the laser diffraction and scattering method was used to measure the particle size (D50) at 50% cumulative in the volume-based particle size distribution when the refractive index was 1.35-0.05i, which was defined as the average particle size D A was measured as.

[0110] (The average particle diameter of the resin particles measured by dynamic light scattering, D B (measurement of Average particle size D of resin particles in aqueous resin emulsion measured by dynamic light scattering method B Specifically, the average particle diameter D (nm) was measured by cumulant analysis using a particle size distribution analyzer (Otsuka Electronics, product name "Concentrated Particle Size Analyzer FPER-1000") that utilizes dynamic light scattering and a concentrated probe. B The average particle diameter D A and D B Using the measured values ​​of each, the ratio of them, D A / D B was calculated.

[0111] (manufacturing stability) The agglomerates formed during the production of the aqueous resin emulsion were evaluated according to the following criteria. ○: Almost no formation of aggregates is observed. △: A small amount of aggregates formed. ×: A large amount of aggregates was formed.

[0112] (Storage stability) The aqueous resin emulsion was placed in a glass vial and allowed to stand at 50° C. After one week of standing, the state of the contents was visually evaluated based on the presence or absence of sediment. ○: No sediment is observed. ×: Sediment is observed.

[0113] (gel fraction) The aqueous resin emulsion was dried at 130°C for 30 minutes to form a resin film, which was then peeled off to obtain a measurement sample. Then, 0.5 g of the measurement sample was weighed out, immersed in 100 ml of tetrahydrofuran at 23°C, and left at 23°C for 1 day. The tetrahydrofuran solution was then filtered through a 200-mesh wire net, and the insoluble matter remaining on the wire net was dried at 130°C for 1 hour, returned to 23°C, and its weight was measured. The gel fraction (%) was then calculated using the following formula: Gel fraction (%) = insoluble matter / weight before immersion × 100

[0114] (Examples 2 to 17: Method for producing aqueous resin emulsion) The aqueous resin emulsions of Examples 2 to 17 were produced in the same manner as in Example 1, except that the polymerizable monomer (a1), polymerizable monomer (b1), crosslinkable monomers (a2, b3), carboxy group-containing polymerizable monomer (b2), hydrophilic solvent, and chain transfer agent in Example 1 were changed to the amounts shown in Table 1. However, because multistage emulsion polymerization was used, the amounts of the polymerization initiator and surfactant used were divided depending on the monomer ratio. The solids content and pH of the aqueous resin emulsions of Examples 2 to 17 were adjusted to be approximately the same as those of Example 1.

[0115] (Comparative Examples 1 to 11: Methods for producing aqueous resin emulsions) The aqueous resin emulsions of Comparative Examples 1 to 11 were produced in the same manner as in Example 1, except that the polymerizable monomer (a1), polymerizable monomer (b1), crosslinkable monomers (a2, b3), carboxy group-containing monomer (b2), hydrophilic solvent, and chain transfer agent in Example 1 were changed to the amounts shown in Table 1. However, because multistage emulsion polymerization was used, the amounts of the polymerization initiator and surfactant were each divided depending on the monomer ratio.

[0116] <Method for manufacturing test sample 1> Test Sample 1 was produced by blending the aqueous resin emulsions prepared in Examples 1 to 17 and Comparative Examples 1 to 11 with a film-forming agent (butyl glycol), a wetting agent (manufactured by Nissin Chemical Industry Co., Ltd., trade name: Olfine E1010), a defoaming agent (manufactured by ADEKA Corporation, trade name: Adekanate B-187), and a thickener (manufactured by ADEKA Corporation, trade name: Adekanol UH-420), and adjusting the solids content to 28% with water. Test Sample 1 was diluted to 10% with water before testing, and the evaluation tests described below, "drying property test, water resistance test, and adhesion test (initial and after immersion)," were performed. Note that gelation occurred during the aqueous resin emulsion polymerization in Comparative Example 7, so none of the subsequent evaluation tests could be performed.

[0117] (Drying test) Test sample 1 was applied to the surface of a slate board (manufactured by TP Giken Co., Ltd., product name: flexible board) with a thickness of 200 g / m 2 After applying the coating with a brush so that the coating was uniform, the coating was dried for 1 hour in an atmosphere of 23°C x 50% RH, and the drying property of the coating was evaluated by touching with a finger. (Evaluation criteria) 〇: Dry and fingertips do not get dirty. ×: Semi-dry, or not dry and sticks to fingertips and stains.

[0118] (Water resistance test) Test sample 1 was applied to the surface of a slate board (manufactured by TP Giken Co., Ltd., product name: flexible board) with a thickness of 200 g / m 2 After painting with a brush so that the color was as shown in the figure, the sample was dried for 1 hour in an atmosphere of 23°C x 50% humidity, immersed in water at 23°C for 1 day, and then removed, and the degree of whitening was evaluated visually. (Evaluation criteria) ○: Almost no bleaching is observed. ×: bleached.

[0119] (Initial adhesion test: cross-cut method) [Preparation of test samples 2, 3, 4, and 5] The aqueous resin emulsions prepared in Examples 1 to 17 and Comparative Examples 1 to 11 were applied to various inorganic substrates or various old coating films, and then a topcoat paint was applied to prepare test samples 2 to 5. Test samples 2 to 5 were used to evaluate the adhesion of the formed coating films by the cross-cut method.

[0120] (Preparation of test sample 2 for evaluating the adhesion of a coating film on an inorganic substrate at 23°C) Test sample 2 was prepared to evaluate the adhesion of the aqueous resin emulsion coating to various inorganic substrates and topcoats at 23°C. The aqueous resin emulsions prepared above in the Examples and Comparative Examples were applied to the surfaces of a slate board and a calcium silicate board at a rate of 200 g / m. 2 After applying the paint with a brush so that the surface was uniform, the paint was dried for 36 hours in an atmosphere of 23°C and 50% humidity. After drying, a one-component water-based silicone resin (SK Chemical Co., Ltd., product name: Water-based Yane Fresh Silicone) was applied as a top coat at 300 g / m². 2 After painting with a brush so that the number of coats was two, the coating was dried for three days in an atmosphere of 23°C x 50% humidity to form a coating film, and test sample 2 was obtained.

[0121] (Preparation of test sample 3 for evaluating the adhesion of a coating film on an inorganic substrate at 10°C) In addition, assuming a cold climate, test sample 3 was prepared under more severe drying conditions, with the plate temperature lowered to 10°C (the inorganic substrate was left in an incubator set to 10°C for 3 hours, and a surface thermometer was used to confirm that the temperature had reached 10°C). Except for setting the inorganic substrate plate temperature to 10°C, the same preparation conditions were used as for test sample 2, and the aqueous resin emulsion and top coat paint were applied in that order to form a coating. This gave test sample 3.

[0122] (Preparation of test sample 4 to evaluate the adhesion of the paint film on the old paint film at 23°C) Test Sample 4 was prepared to evaluate the adhesion of a water-based resin emulsion coating to an old coating at 23°C. A slate board (TP Giken Co., Ltd., product name: Flexible Board) was coated with 200 g / m2 of a two-component weak solvent sealer (SK Kaken Co., Ltd., product name: Mild Sealer EPO). 2After painting with a brush so that the surface was as shown, the surface was dried for 3 days in an atmosphere of 23°C x 50% RH to prepare the base. Next, each of the paints (1) and (2) was applied in the following coating amounts and dried for 3 days in an atmosphere of 23°C x 50% RH. (1) A one-component water-based fluororesin (SK Chemical Co., Ltd., product name: Water-based Yane Fresh Fusso) was applied at a coating weight of 300 g / m 2 The paint was applied with a brush so that the finish was two coats. (2) A two-component weak solvent resin (manufactured by SK Chemicals, product name: Cooltite Si) was applied with a brush so that the coating amount was 300 g / m2 (two coats).

[0123] After drying, the old paint film was formed on the slate boards using a Super Xenon Weather Meter (manufactured by Suga Test Instruments) for 1,000 cycles (based on JIS K 5600-7-7 Cycle A: Cycle 1 irradiation for 102 minutes (irradiance: 60 W / m², black panel temperature: 63°C, humidity: 50%), Cycle 2 irradiation + pure water shower for 18 minutes (irradiance: 60 W / m², room temperature: 38°C, humidity: 95%, total 120 minutes is one cycle).

[0124] Next, using each slate board on which an old coating film made of the above-mentioned various paints had been formed, 200 g / m of each of the prepared aqueous resin emulsions of the Examples and Comparative Examples was applied onto the old coating film. 2 The coating was applied so that the thickness was 300g / m², and then dried for 36 hours in an atmosphere of 23°C and 50% humidity. After drying, a one-component water-based silicone resin (SK Chemical Co., Ltd., product name: Water-based Yane Fresh Silicon) was applied as a top coat. 2 After painting with a brush so that the number of coats was two, the coating was dried for three days in an atmosphere of 23°C and 50% humidity to form a coating film, and test sample 4 was obtained.

[0125] (Preparation of test sample 5 to evaluate the adhesion of the paint film on the old paint film at 10°C) In addition, assuming cold regions, and under more severe drying conditions, the temperature of each old paint film was lowered to 10°C (each old paint film was left in an incubator set to 10°C for 3 hours, and a surface thermometer was used to confirm that the temperature had reached 10°C), and the samples were then coated. Except for the fact that the temperature of each old paint film was set to 10°C, the water-based resin emulsion and top coat were applied in that order to form a paint film under the same preparation conditions as for Test Sample 4. This gave Test Sample 5.

[0126] (Evaluation of initial adhesion using the cross-cut method) Using the test samples 2 to 5 prepared above, the adhesion to the inorganic substrate, old paint film, and topcoat paint was evaluated by making a 5 mm wide cross-cut in accordance with JIS K5600-5-6 (adhesion cross-cut method), and the results were visually evaluated using the following six-level classification criteria of 0 to 5. Classifications 0 and 1 indicate pass, and classifications 2 to 5 indicate fail. (Evaluation criteria) Classification 0 (pass): No peeling on any grid Class 1 (pass): Small peeling of the coating at the intersection of the cuts, peeling of the cross-cut area is 5% or less Category 2 (Fail): The coating has peeled along the edges of the cuts and / or at the intersections, with more than 5% but not more than 15% peeling in the cross-cut areas. Category 3 (fail): The coating peeled off completely along the edges of the cuts, and the peeling in the cross-cut area was more than 15% but not more than 35%. Category 4 (fail): The coating peeled off completely along the edges of the cuts, and the peeling in the cross-cut area was more than 35% but not more than 65%. Class 5 (fail): Peeling of Class 4 or higher

[0127] (Adhesion test after immersion) A set of test samples 2 to 5 identical to test samples 2 to 5 used in the initial adhesion test was prepared, and test samples 2 to 5 were used to evaluate adhesion after immersion in water. Test samples 2 to 5 were immersed in water in an atmosphere of 23°C x 50% humidity for 7 days, removed, and dried for 30 minutes. Then, using the dried test samples 2 to 5, adhesion after immersion was evaluated in the same manner as in the initial adhesion test. The following evaluation criteria are the same as those for the initial adhesion test. (Evaluation criteria) Classification 0 (pass): No peeling on any grid Class 1 (pass): Small peeling of the coating at the intersection of the cuts, peeling of the cross-cut area is 5% or less Category 2 (Fail): The coating has peeled along the edges of the cuts and / or at the intersections, with more than 5% but not more than 15% peeling in the cross-cut areas. Category 3 (fail): The coating peeled off completely along the edges of the cuts, and the peeling in the cross-cut area was more than 15% but not more than 35%. Category 4 (fail): The coating peeled off completely along the edges of the cuts, and the peeling in the cross-cut area was more than 35% but not more than 65%. Class 5 (fail): Peeling of Class 4 or higher

[0128] (Test results) Table 5 shows the test results for Examples 1 to 14. Table 6 shows the test results for Examples 15 to 17 and Comparative Examples 1 to 11.

[0129] [Table 5]

[0130] [Table 6]

[0131] (Test results for Examples 1 to 17) According to Tables 5 and 6, Examples 1 to 17 have excellent properties in all of drying property, water resistance, initial adhesion, and adhesion after immersion in water.

[0132] (Test results for Comparative Examples 1 to 11) On the other hand, a large amount of aggregates was formed during polymerization in Comparative Examples 2, 3, 8, and 9. The reasons for the formation of aggregates in Comparative Examples 2, 3, 8, and 9 will be explained below. In addition, the reason why a water-soluble resin emulsion could not be produced in Comparative Example 7 will also be explained.

[0133] In Comparative Example 2, the amount of basic compound added 30 minutes after polymerization of the polymerizable monomer (b1) etc. in the production process of copolymer (B) was small, and neutralization and dissolution were not possible, resulting in a decrease in the function of the protective layer, which is thought to have reduced the stability of the aqueous resin emulsion.

[0134] In Comparative Example 3, the amount of acid (amount of carboxy-containing polymerizable monomer (b2)) was small, which is thought to have reduced the function of the protective layer and the stability of the aqueous resin emulsion.

[0135] In Comparative Example 8, the amount of chain transfer agent in the mixed solution of the polymerizable monomer (b1) etc. was large, and the weight average molecular weight (Mw) of the copolymer (B) was low, which is thought to have reduced the function of the protective layer and the stability of the aqueous resin emulsion.

[0136] In Comparative Example 9, the proportion of copolymer (B) (20 parts) was low, which is thought to have resulted in a decrease in the function of the protective layer and a decrease in the stability of the aqueous resin emulsion.

[0137] In Comparative Example 7, since no chain transfer agent was added to the mixed solution of the polymerizable monomer (b1) etc., the weight average molecular weight (Mw) of the copolymer (B) became high and the copolymer (B) did not dissolve in water, which resulted in a very high viscosity of the polymerization solution of the copolymer (B), resulting in an excessively large particle size and making it impossible to prepare an aqueous resin emulsion.

[0138] As described above, the aqueous resin emulsion of the present invention has significant effects such as excellent adhesion to substrates and topcoats, quick drying properties, water resistance, and storage stability.

[0139] Furthermore, the present invention can provide an aqueous resin emulsion that is environmentally friendly and highly safe for the human body, which can contribute to achieving Goal 12 of the United Nations-led Sustainable Development Goals (SDGs), "Responsible Consumption and Production."

[0140] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention. [Explanation of symbols]

[0141] 100 resin particles 110 Inner layer 120 protective layer 130 Average particle size 140 Average particle size 200 Base material 300 Base material

Claims

1. An aqueous resin emulsion containing resin particles including an inner layer and a protective layer surrounding the inner layer, the inner layer contains a copolymer (A) containing a polymerizable monomer (a1) and a crosslinkable monomer (a2) as structural units, the protective layer contains at least a copolymer (B) containing, as structural units, a polymerizable monomer (b1) and a carboxy group-containing polymerizable monomer (b2), and a chain transfer agent; the polymerizable monomer (a1) and the polymerizable monomer (b1) each contain at least one of a (meth)acrylic acid alkyl ester monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, and a piperidyl group-containing unsaturated monomer; The copolymer (A) contains the crosslinkable monomer (a2) in an amount of 0.1 to 15% by weight based on 100% by weight of all monomers constituting the copolymer (A), The copolymer (B) contains the carboxy group-containing polymerizable monomer (b2) in an amount of 5 to 20% by weight based on 100% by weight of all monomers constituting the copolymer (B), The weight average molecular weight (Mw) of the copolymer (B) is 3,000 to 20,000; The average particle diameter D of the copolymer (A) Ａ and the average particle diameter D of the resin particles Ｂ The ratio (D Ａ / D Ｂ ) is greater than 0 and less than or equal to 0.70; Here, the average particle diameter D Ａ is measured by laser diffraction / scattering method, and the average particle diameter D Ｂ is measured by dynamic light scattering, Water-based resin emulsion.

2. The copolymer (B) further contains a crosslinkable monomer (b3) as a constituent unit, The crosslinkable monomer (b3) and the crosslinkable monomer (a2) each contain at least one of a polyfunctional monomer and a silane coupling agent. The aqueous resin emulsion according to claim 1.

3. The copolymer (B) contains the chain transfer agent in an amount of 0.1 to 15.0% by weight based on 100% by weight of all monomers constituting the copolymer (B). The aqueous resin emulsion according to claim 1.

4. The copolymer (A) contains the polymerizable monomer (a1) in an amount of 85 to 99.9% by weight based on 100% by weight of all monomers constituting the copolymer (A), The copolymer (B) contains the polymerizable monomer (b1) in an amount of 80 to 95% by weight based on 100% by weight of all monomers constituting the copolymer (B). The aqueous resin emulsion according to claim 3.

5. The pH of the copolymer (B) is 7.0 to 10.

5. The aqueous resin emulsion according to claim 1.

6. The haze of the copolymer (B) is 0 to 25%. The aqueous resin emulsion according to claim 1.

7. the weight ratio (B / A) of the copolymer (A) to the copolymer (B) is 25 / 75 to 75 / 25; The aqueous resin emulsion according to claim 1.

8. The average particle diameter D Ｂ is 50 to 300 nm, The aqueous resin emulsion according to claim 1.

9. It has both sealer and primer applications. The aqueous resin emulsion according to claim 1.

10. The copolymer (A) contains 15% by weight or less of a styrene-based monomer as the polymerizable monomer (a1) based on 100% by weight of all monomers constituting the copolymer (A), and / or The copolymer (B) contains 15% by weight or less of a styrene-based monomer as the polymerizable monomer (b1) based on 100% by weight of all monomers constituting the copolymer (B). The aqueous resin emulsion according to any one of claims 1 to 9.

11. A substrate; a coating film formed from the aqueous resin emulsion according to claim 1 and provided on at least one surface of the substrate; Painted products.

12. The gel fraction of the coating film is 50 to 100%. The coated article according to claim 11.

13. The substrate comprises an inorganic porous substrate; The coated article according to claim 11.

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