JP5468741B2 - Water-based resin composition and paint for building exterior topcoat containing the same - Google Patents

Description

The present invention relates to an aqueous resin composition. More specifically, with respect to aqueous resin compositions useful in the field of architectural exterior topcoat paints, etc., the amount of volatile organic compounds is small, the film-forming property is good, and the properties such as hardness, stain resistance, and water resistance The present invention relates to an aqueous resin composition capable of forming an excellent film and its use.

As a paint for buildings, there is a concern about an adverse effect on the environment, and the conversion from an organic solvent-type paint to a water-based paint is progressing. In particular, an emulsion-type resin composition has been frequently used. This emulsion type resin composition forms a coating film by evaporating water and fusing resin particles together. When heating and drying can be performed, the resin particles become soft, so fusion is easy and water is easily volatilized.For example, when painting on the outer wall of a building, drying is performed at room temperature, so that an emulsion can be made. Membrane properties become a problem.

That is, considering characteristics such as stain resistance and abrasion resistance of the coating film, it is desirable to use a relatively hard resin as a constituent of the coating film. However, since a hard resin has a high glass transition temperature (Tg), Then, fusion between resin particles hardly occurs, and the film forming property is inferior. In order to solve this low film-forming problem, a means has been adopted in which an organic solvent that plasticizes resin particles to promote fusion and coating is present in the emulsion.

However, in recent years, environmental issues have been emphasized, and not only building interior paints as a countermeasure against sick house syndrome, but also exterior paints are required to contain VOC-free (VOC) paints. The use of organic solvents as film forming aids has become unacceptable.

A conventional emulsion is, for example, an aqueous coating material containing emulsion particles obtained by emulsion polymerization of an ethylenically unsaturated monomer by a multistage emulsion polymerization method, and the layer inside the outermost layer of the particles is the outermost layer. The thing specified to the thing whose glass transition temperature is higher than an outer layer is disclosed (for example, refer patent document 1, 2). Although the low-temperature film-forming property is improved by making the emulsion into a hard core / soft shell type, the hardness is still insufficient. Moreover, such a hard core / soft shell type acrylic emulsion is inferior in properties such as gloss, and there is room for improvement to further improve the coating film properties. In addition, a multi-layer polymer emulsion is disclosed in which the glass transition temperatures of the three layers are different from each other (see, for example, Patent Documents 3 and 4). Furthermore, a method for producing an emulsion by emulsion polymerization of a monomer composition containing (meth) acrylic acid ester and 0.1 to 20% by weight of styrene based on the (meth) acrylic acid ester is disclosed. (For example, refer to Patent Document 5). However, in these emulsions, the low-temperature film-forming property and hardness are not sufficient, and there is room for contrivance to obtain emulsions that satisfy all the above-described characteristics.
As described above, the balance between the low-temperature film-forming property of the emulsion and the coating performance such as hardness is sufficiently satisfied, and the problem that the performance such as hardness cannot be fully expressed when the low-temperature film-forming property is imparted. It was where it was desired to do.
Japanese Patent Laying-Open No. 2005-247922 (pages 2, 18, etc.) JP 2002-256202 A (Pages 2, 5, etc.) JP 2004-59623 A (2nd, 5th page, etc.) Japanese Unexamined Patent Application Publication No. 2004-250607 (pages 2, 11, etc.) JP 2000-327722 A (2nd, 11th page, etc.)

The present invention has been made in view of the above situation, and is an aqueous resin having a low volatile organic compound content, good low-temperature film-forming properties, and capable of forming a film excellent in hardness, water resistance, gloss, and the like. The object is to provide a composition.

The inventors of the present invention have made various studies on the aqueous resin composition, and paying attention to the fact that the emulsion can be used to exhibit advantageous performance such as water resistance, and the multilayer structure emulsion particles obtained by multistage emulsion polymerization. The multilayer structure is formed by emulsion polymerization of at least three stages, and includes an intermediate layer, an outer layer outside the intermediate layer, and an inner layer inside the intermediate layer, and the intermediate layer has a glass transition temperature higher than that of the outer layer. The structural unit of the polymer that constitutes the intermediate layer is different from the constituent unit of the polymer that constitutes the inner layer. The inventors have found that the advantageous effects of forming a film having excellent characteristics and excellent gloss can be exhibited, and the above problems can be solved brilliantly. In addition, in the multilayer structure emulsion particles, when the glass transition temperature of the outer layer is −50 to 0 ° C. and the glass transition temperature of the intermediate layer is 50 to 150 ° C., the present invention preferably achieves both low-temperature film-forming properties and hardness. It has been found that the effect can be more fully exhibited. Furthermore, after setting the glass transition temperature of the entire emulsion appropriately, the glass transition temperature of the outer layer constituting the multilayer emulsion particles is set low, and the film thickness (ratio of monomer components forming the outer layer) is appropriate. It was found that the advantageous effects of the present invention, which are high in hardness and excellent in wear resistance, etc., are exhibited while maintaining a low-temperature film-forming property equivalent to or higher than that of an acrylic emulsion having a low hardness. . And it discovered that such an aqueous resin composition was suitable as a coating material for building exterior topcoats, and reached the present invention.
As a preferable form of the present invention, a form having a specific amount of a structural unit derived from a styrenic monomer or cyclohexyl (meth) acrylate in the multilayer structure emulsion particles can be mentioned. A form having a specific amount of a structural unit derived from a styrene monomer or cyclohexyl (meth) acrylate in the outer layer is also a preferred form of the present invention.

That is, the present invention is an aqueous resin composition in which three or more layers of multilayer emulsion particles are essential, and the multilayer emulsion particles are contained in the intermediate layer, the outer layer outside the intermediate layer, and in the intermediate layer. An aqueous resin composition comprising an inner layer, wherein the intermediate layer has a glass transition temperature higher than that of the outer layer, and the constituent unit of the polymer constituting the intermediate layer is different from the constituent unit of the polymer constituting the inner layer It is.
The present invention is also an aqueous resin composition essentially comprising three or more multilayer emulsion particles, wherein the multilayer emulsion particles are formed by multi-stage emulsion polymerization. Including the emulsion polymerization step, the middle emulsion polymerization step, and the latter emulsion polymerization step, the middle emulsion polymerization step differs from the former emulsion polymerization step in the composition of the monomer to be polymerized, and the middle emulsion polymerization step is more effective than the latter emulsion polymerization step. It is also an aqueous resin composition from which a polymer layer having a high glass transition temperature can be obtained.
The present invention is also a coating for a building exterior topcoat comprising the above aqueous resin composition.
In the present specification, the “aqueous resin composition” refers to those containing water and an emulsion as essential components. The emulsion may contain one type or two or more types, and may or may not contain other components.
The present invention is described in detail below.

The multilayer emulsion particles include an intermediate layer, an outer layer outside the intermediate layer, and an inner layer inside the intermediate layer, and the intermediate layer has a glass transition temperature higher than that of the outer layer. The constituent unit of the constituent polymer is different from the constituent unit of the polymer constituting the inner layer.
By making such multilayer emulsion particles essential, the aqueous resin composition of the present invention has good low-temperature film-forming properties and excellent hardness and the like of the formed film. The reason that the effect of improving the low temperature film forming property is that the intermediate layer has a glass transition temperature higher than that of the outer layer, so that the outer layer is easily deformed at a low temperature and has excellent low temperature film forming property. This is probably because of this. The reason why a film having excellent hardness can be formed is that in addition to the outer layer, an intermediate layer having a different polymer structural unit from the intermediate layer is present, so that a layer having a high glass transition temperature is present in the multilayer emulsion particles. Because it is pulled out to the outside, the hardness is increased by the intermediate layer having a high glass transition temperature, the layer having a low glass transition temperature in the outer layer is thinned, and the intermediate layer having a high glass transition temperature in the outer layer is increased in hardness. It is possible that the impact will increase.
Therefore, by specifying the multilayer structure emulsion particles as described above, the aqueous resin composition of the present invention is excellent in physical properties such as low-temperature film-forming property and hardness of the formed film.

The constituent unit of the polymer constituting the intermediate layer is different from the constituent unit of the polymer constituting the inner layer. The inner layer inside the intermediate layer is formed from a monomer composition different from that of the intermediate layer. That is, it is sufficient that the monomer units constituting the intermediate layer and the inner layer are entirely different from each other, for example, at least one different monomer unit or the same monomer In the case of a body unit, the ratio of the monomer units may be different, and it may be different to the extent that it is technically considered that there is a difference in characteristics between the intermediate layer and the inner layer.
One or more layers may be formed inside the inner layer, and one or more layers may be formed between the intermediate layer and the inner layer, and between the outer layer and the intermediate layer. One or a plurality of layers may be formed, and one or a plurality of layers may be formed outside the outer layer.
The multilayer structure emulsion particles contained in the aqueous resin composition of the present invention have an outer layer, an intermediate layer and an inner layer, but there may be a homogeneous portion in which these are compatible and cannot be distinguished.
In addition, the compound which comprises the aqueous resin composition of this invention, its raw material, etc. can use 1 type (s) or 2 or more types, respectively.
The intermediate layer preferably has a glass transition temperature higher than that of the inner layer.
Thereby, the effect of this invention can be exhibited more fully.

The presence of two or more polymers having different glass transition temperatures can be confirmed by differential scanning calorimetry (DSC measurement) of the dried coating film of the multilayered emulsion particles (FIG. 1). Further, an atomic force microscope (Atomic Force Microscope): The presence of the polymer constituting the intermediate layer having a high glass transition temperature can be confirmed in the phase mode of AFM) (FIG. 2).
The difference from the hard core / soft shell / hard shell in the phase mode is that the hardness factor is greatly influenced in the phase mode, and the relatively harder one is depicted as white contrast.

The aqueous resin composition of the present invention preferably comprises a multilayer structure emulsion particle obtained by multistage emulsion polymerization.
The multilayer structure in the multilayer emulsion particles is usually formed by at least three stages of emulsion polymerization.
The at least three-stage emulsion polymerization preferably includes one-stage emulsion polymerization that forms the inner layer, one-stage emulsion polymerization that forms the intermediate layer, and one-stage emulsion polymerization that forms the outer layer. These emulsion polymerizations are performed in the order of emulsion polymerization for forming an inner layer, emulsion polymerization for forming an intermediate layer, and emulsion polymerization for forming an outer layer.
The at least three-stage emulsion polymerization may be one-stage or multiple-stage emulsion polymerization before the emulsion polymerization forming the inner layer. The emulsion polymerization forming the inner layer and the emulsion polymerization forming the intermediate layer In this case, one or more stages of emulsion polymerization may be performed, and one stage or a plurality of stages of emulsion polymerization is performed between the emulsion polymerization that forms the intermediate layer and the emulsion polymerization that forms the outer layer. The emulsion polymerization may be performed after the emulsion polymerization for forming the outer layer or may be performed in a plurality of stages. A combination of these may also be used.

In the above polymerization reaction, the polymerization may be started from a simple mixture of raw materials (aqueous medium, emulsifier and monomer component), or the raw material may be emulsified by mechanical stirring and pre-emulsion may be started. , Even if a part of the raw materials (for example, an aqueous medium, one or more of the monomer components) are simply mixed, and polymerization is started while the rest is added as a pre-emulsion Good.
In addition, the monomer component used in the polymerization reaction in each stage may be added alone, or may be added as a pre-emulsion together with an aqueous medium or an emulsifier, or a part of the pre-emulsion mixed with the rest. It may be added. Further, the addition method in the polymerization reaction at each stage may be any of batch addition, divided addition, continuous dropping, etc., and the addition method may be the same or different at each stage.
The multilayer emulsion particles are preferably formed by polymerizing the monomer component, but are formed by a reaction other than polymerization during or after the monomer component is polymerized. May be.

The glass transition temperature (Tg) of the multilayer emulsion particles can be adjusted from the homopolymer glass transition temperature (Tg) (absolute temperature; K) and the mass fraction of the monomer using the following formula. it can. It is preferable to determine the monomer composition using the calculated Tg as a guide.

Wherein, Tg represents the glass transition temperature (K) of a polymer for _{obtaining, W 1, W 2, ...} W n represents the mass fraction of each _{monomer, Tg 1, Tg 2, ...} Tg n is The glass transition temperature (K) of the corresponding monomer homopolymer is shown. In the tables and the like, each monomer name is abbreviated as follows. The number on the right is the glass transition temperature (K) value of the homopolymer used for the calculation.
MMA: Methyl methacrylate 378K
2EHA: 2-ethylhexyl acrylate 203K
St: Styrene 373K
CHMA: cyclohexyl methacrylate 356K
IBMA: Isobornyl methacrylate 453K
NVP: N-vinylpyrrolidone 448K
AA: Acrylic acid 368K
MAA: methacrylic acid 403K
HEMA: 2-hydroxyethyl methacrylate 328K
HALS: “ADK STAB (registered trademark) LA-87” (trade name, manufactured by Asahi Denka Kogyo Co., Ltd .: 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine)
403K
IBA: Isobornyl acrylate 367K
t-BMA: tert-butyl methacrylate 380K
BA: Butyl acrylate 217K
The glass transition temperature of the polymer can be measured by DSC (differential scanning calorimeter), DTA (differential thermal analyzer), and TMA (thermomechanical measuring device).
The glass transition temperature described later is obtained using the above formula. For example, the glass transition temperature of the entire multilayer emulsion particle is obtained from the mass fraction of each monomer in all monomer components used in the multistage emulsion polymerization and the glass transition temperature of the corresponding homopolymer of the monomer. It is.

It is a preferable embodiment of the present invention that the multilayer emulsion particles have a glass transition temperature of -20 to 30 ° C. of the whole emulsion.
When the glass transition temperature is less than −20 ° C., the hardness is low, and there is a fear that the formed film is inferior in stain resistance, abrasion resistance, etc., and when it exceeds 30 ° C., the low-temperature film-forming property is inferior. There is a fear.

The multilayer emulsion particles in the aqueous resin composition of the present invention preferably have an outer layer glass transition temperature of −50 to 0 ° C. and an intermediate layer glass transition temperature of 50 to 150 ° C.
The multilayer structure emulsion particles preferably have an inner layer glass transition temperature of -50 to 0 ° C.
By setting it as such a glass transition temperature, the outstanding effect of this invention which can make low temperature film forming property and hardness compatible can fully be exhibited.
If the glass transition temperature in the outer layer and / or the inner layer is less than −50 ° C., the hardness is low, and there is a risk of being inferior in the stain resistance, abrasion resistance, etc. of the formed film. There is a possibility that the film-forming property is inferior. More preferably, it is −40 ° C. or higher.
When the glass transition temperature of the intermediate layer is less than 50 ° C., the hardness is low, and there is a possibility that the formed film is inferior in stain resistance, abrasion resistance, and the like. If it exceeds 150 ° C, the low-temperature film-forming property may be inferior. More preferably, it is 70 ° C. or higher. More preferably, it is 85 degreeC or more. More preferably, it is 90 degreeC or more.
In the aqueous resin composition of the present invention, the multilayer emulsion particles preferably have an inner layer having a glass transition temperature lower than that of the intermediate layer.
Thereby, the film-forming property is improved by the internal stress relaxation when the particles are dried and fused. In addition, a smooth coating surface or coating surface is obtained and gloss is improved.

In the aqueous resin composition of the present invention, the multilayer emulsion particles preferably have a polymer whose inner layer has a lower solubility parameter than a polymer that forms an intermediate layer.
Thereby, a hard intermediate | middle layer is obtained and high coating-film hardness or film hardness expresses. When the solubility parameter of the inner layer is lower than that of the intermediate layer, the system is more hydrophilic because of the water (high solubility parameter, in other words, high SP [Solubility Parameter]) polymer is more likely to exist at the particle interface Therefore, it is considered that the phenomenon of replacing the polymer constituting the intermediate layer is difficult to occur.
The outer layer is a substantial fused layer when the emulsion is dried and the particles are fused, and preferably has a Tg lower than room temperature.
The solubility parameter difference between the polymer constituting the inner layer and the polymer constituting the intermediate layer is preferably 0.1 or more.

The calculated solubility parameter is described in “Polymer Engineering and Science”, 1974, Vol. 14, no. 2, p. It is a value calculated by the method described in 147-154. The method (solubility parameter calculation method) is outlined below.
The solubility parameter (δ) of the homopolymer is calculated by the following formula based on the evaporation energy (Δei) and the molar volume (Δvi) of the structural unit forming the polymer.
δ = (ΣΔei / ΣΔvi) ^1/2
Δei: Evaporation energy of atom or atomic group of component i Δvi: Solubility parameter of molar volume copolymer of atom or atomic group of component i is a homopolymer of each constituent monomer constituting the copolymer Is calculated by the above formula from the sum of Δei and Δvi multiplied by the mole fraction of the constituent monomers.

Table 1 below shows typical homopolymer solubility parameters.
Table 1 below shows the solubility parameters (SP values) of the homopolymers of the monomers listed in the left column in the right column. In the present specification, 2EHA represents 2-ethylhexyl acrylate. AA represents acrylic acid. BA represents butyl acrylate. BMA represents butyl methacrylate. CHMA represents cyclohexyl methacrylate. EA represents ethyl acrylate. HEMA represents 2-hydroxyethyl methacrylate. MAA represents methacrylic acid. MMA represents methyl methacrylate. St represents styrene. t-BMA represents tert-butyl methacrylate.

In this specification, the mass ratio of the outer layer to the mass ratio of the entire polymer is obtained from the mass of the monomer component used in the emulsion polymerization to form the outer layer with respect to the mass of the entire monomer component used in the multistage emulsion polymerization. It is.

The multilayered emulsion particles in the aqueous resin composition of the present invention have an outer layer of 40 to 84% by mass, an intermediate layer of 15 to 45% by mass, and an inner layer of 1 to 1%, assuming that the entire polymer constituting it is 100% by mass. It is preferably 25% by mass.
In the present specification, the mass ratio of the intermediate layer relative to the mass ratio of the entire polymer and the mass ratio of the inner layer are the same as the mass ratio of the outer layer described above, with respect to the mass of the entire monomer component used in the multistage emulsion polymerization. These are respectively determined from the mass of the monomer component used in the emulsion polymerization for forming the intermediate layer and the mass of the monomer component used in the emulsion polymerization for forming the inner layer.
By setting the multilayer emulsion particles to such a mass ratio, it is possible to achieve both the effect of increasing the hardness of the film formed from the resin composition, in addition to being excellent in low-temperature film-forming properties.

There exists a possibility that it may be inferior to low temperature film forming property etc. as the said outer layer is less than 40 mass%. On the other hand, if it exceeds 84% by mass, the hardness will be low, and the resulting coating film may be inferior in contamination resistance, abrasion resistance, and the like. More than 50% by mass is more preferable, 55% by mass or more is more preferable, and 60% by mass or more is still more preferable. Moreover, it is more preferable that it is 80 mass% or less, it is still more preferable that it is 75 mass% or less, and it is especially preferable that it is 70 mass% or less.
If the intermediate layer is less than 15% by mass, the hardness is low, and the formed film may be inferior in stain resistance, abrasion resistance, and the like. Moreover, when it exceeds 45 mass%, there exists a possibility that it may be inferior to low-temperature film-forming property. It is more preferably 25% by mass or more, and further preferably 30% by mass or more. Moreover, it is more preferable that it is 42 mass% or less, and it is still more preferable that it is 40 mass% or less.
When the inner layer is less than 1% by mass, the hardness is lowered, and there is a possibility that the formed film is inferior in stain resistance, abrasion resistance, and the like. Moreover, when it exceeds 25 mass%, there exists a possibility that it may be inferior to low-temperature film-forming property. It is more preferably 2% by mass or more, and further preferably 3% by mass or more. Moreover, it is more preferable that it is 12 mass% or less, and it is still more preferable that it is 10 mass% or less.

An aqueous resin composition essentially comprising multilayer emulsion particles obtained by multi-stage emulsion polymerization, wherein the multilayer emulsion particles are formed by emulsion polymerization of at least three stages to constitute multilayer emulsion particles. Assuming that the entire polymer to be treated is 100% by mass, the outer layer having a glass transition temperature of 0 ° C. or lower is 40 to 80% by mass, and the aqueous resin composition in which the glass transition temperature of the entire emulsion is −20 to 30 ° C. 1 is one preferred embodiment of the invention.
When the multilayer emulsion particles have the above-described structure, the low temperature film-forming property is enhanced by the specified outer layer, and the glass transition temperature of the whole emulsion is specified as described above. The film has a sufficiently increased hardness. In particular, since the multilayer structure is formed by emulsion polymerization of at least three stages, there is a layer that is the core of the aqueous resin composition, that is, the central part of the aqueous resin composition, and therefore an intermediate layer having a high glass transition temperature. Is pulled out more in the multilayer emulsion particles, and the hardness is increased by the intermediate layer having a high glass transition temperature.
In this case, the glass transition temperature difference between the intermediate layer and the inner layer is not particularly limited and may be the same, but the intermediate layer preferably has a glass transition temperature higher than that of the inner layer. Further, the intermediate layer is more preferably one having a glass transition temperature higher than that of the outer layer and the inner layer.
The upper limit of the glass transition temperature of the outer layer is more preferably −10 ° C., and further preferably −20 ° C.
The preferable form of the mass ratio of the said outer layer and the glass transition temperature of the said whole emulsion is the same as the preferable form of the aqueous resin composition of this invention mentioned above.
For example, the outer layer having a glass transition temperature of 0 ° C. or lower in the aqueous resin composition of the present invention is preferably more than 50% by mass. By setting to such a range, the composition can exhibit sufficient low-temperature film-forming properties.

The multilayer emulsion particles preferably have an average particle size of 70 to 450 nm. If the average particle diameter is less than 70 nm, the viscosity of the aqueous resin composition may be too high, or the dispersion stability may not be sufficiently maintained, and may be aggregated. May be inferior. More preferably, it is 80-400 nm, More preferably, it is 100-350 nm.
The average particle diameter can be determined by the dynamic light scattering method. For example, after the emulsion is diluted with distilled water and sufficiently stirred and mixed, about 10 ml is collected in a glass cell, and this is measured by the dynamic light scattering method. It is preferably obtained by measurement using NICOM P Model 380 (particle size distribution measuring instrument, trade name, manufactured by Particle Sizing Systems) using Windows-based software (Windows (registered trademark) Based Software). The analysis method is preferably performed by VOLUME-Weighted Gaussian Distribution Analysis (Solid Particles).
In addition, although the aqueous resin composition of this invention may contain emulsions other than the said multilayer structure emulsion particle, it is preferable that the average particle diameter as the whole aqueous resin composition is also the said range.

The monomer component that can be used for the synthesis of the aqueous resin composition of the present invention is preferably a radical polymerizable monomer.
The radical polymerizable monomer is not particularly limited, but (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citracone can be used to adjust the acid value of the aqueous resin composition to the preferred range. Acid, maleic anhydride, monomethyl maleate, monobutyl maleate, monomethyl itaconate, monobutyl itaconate, vinyl benzoic acid, monohydroxyethyl (meth) acrylate oxalate, carboxyl-terminated caprolactone modified acrylate (eg “Placcel FA” series; And a carboxyl group-containing monomer such as carboxyl group-terminated caprolactone-modified methacrylate (for example, “Placcel FMA” series; manufactured by Daicel Industries, Ltd.). Two or more of these may be used in combination. Of these, (meth) acrylic acid is preferred.
The preferred embodiment of the present invention is that the multilayer emulsion particles are multilayer acrylic emulsion particles. Sufficient water resistance can be exhibited by using multilayer emulsion acrylic particles. The multilayer structure acrylic emulsion particle means a multilayer structure emulsion particle in which a polymer constituting the particle has a structural unit derived from (meth) acrylic acid as an essential component.

Other usable monomers include the following radical polymerizable monomers.

Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t -Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl Carbitol (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, tert-butylcyclohexyl (meth) acrylate, cyclododecy (Meth) (meth) alkyl or cycloalkyl ester monomers of acrylic acid, such as acrylates.

2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, caprolactone-modified hydroxy (meta ) Hydroxyl group-containing monomers such as acrylates (eg, “Placcel F” series manufactured by Daicel Chemical Industries, Ltd.).
Alkoxyalkyl esters of (meth) acrylic acid such as methoxybutyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxybutyl (meth) acrylate, and trimethylolpropane tripropoxy (meth) acrylate.

Vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, 2-styrylethyltrimethoxysilane, vinyltrichlorosilane, γ- (meth) acryloyloxypropylhydroxy Hydroxysilanes such as silane and γ- (meth) acryloyloxypropylmethylhydroxysilane and / or hydrolyzable silane group-containing vinyl monomers.

(Meth) acrylamide, N-monomethyl (meth) acrylamide, N-monoethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, Nn-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, methylenebis (Meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (methacrylamide, (meth) acryloyloxyethyltrimethylammonium chloride, dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylamide, morpholine ethylene Oxide addition (meth) acrylate, N-vinyl pyridine, N-vinyl imidazole, N-vinyl pyrrole, N-vinyl pyrrolidone, N-vinyl oxazolidone, N-vinyl sac N'imido, N- vinyl methyl carbamate, N, N- methyl vinyl acetamide, 2-isopropenyl-2-oxazoline, 2-vinyl-2-oxazoline, (meth) nitrogen-containing monomers such as acrylonitrile.
Aziridinyl group-containing monomers such as (meth) acryloylaziridine and 2-aziridinylethyl (meth) acrylate.

Glycidyl (meth) acrylate, α-methylglycidyl acrylate, α-methylglycidyl methacrylate (for example, “MGMA” manufactured by Daicel Chemical Industries), glycidyl allyl ether, oxocyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylmethyl Acrylate (for example, “Cyclomer (registered trademark) A400” manufactured by Daicel Chemical Industries, Ltd.), 3,4-epoxycyclohexylmethyl methacrylate (for example, “Cyclomer (registered trademark) M100” manufactured by Daicel Chemical Industries, Ltd.) Epoxy group-containing monomers such as
Aromatic vinyl monomers such as vinyl toluene. Styrene and / or styrene derivatives described later (some are aromatic vinyl monomers and others are not).

Acrolein, diacetone acrylamide, boromyrstyrene, vinyl alkyl ketone having 4 to 7 carbon atoms (such as vinyl ethyl ketone), (meth) acryloxyalkyl propenal, acetonyl acrylate, diacetone (meth) acrylate, 2- Carbonyl group-containing monomers such as hydroxypropyl acrylate acetyl acetate and butanediol-1,4-acrylate acetyl acetate.

Perfluoroalkyl (meth) acrylates such as perfluorobutylethyl (meth) acrylate, perfluoroisononylethyl (meth) acrylate, and perfluorooctylethyl (meth) acrylate.

4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine (for example, “Adekastab (registered trademark) LA-87” manufactured by Asahi Denka Kogyo Co., Ltd.), 4- (meth) acryloylamino-2,2 , 6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine (for example, “Adekastab (registered trademark) LA-82” manufactured by Asahi Denka Kogyo Co., Ltd.), 4- (meth) acryloyl-1-methoxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 1- ( (Meth) acryloyl-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpipe Gin, 4- (meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4- Crotonoyloxy-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl UV-stable monomers such as -4-crotonoyloxy-2,2,6,6-tetramethylpiperidine.

2- [2'-hydroxy-5 '-(meth) acryloyloxymethylphenyl] -2H-benzotriazole, -2- [2-hydroxy-5- (meth) acryloyloxyethylphenyl] 2H-1,2 , 3-Benzotriazole, 2- [2, -hydroxy-5 '-(meth) acryloyloxymethylphenyl] -5-t-butyl-2H-benzotriazole, 2- [2'-hydroxy-5'-(meta ) Acryloylaminomethyl-5'-tert-octylphenyl] -2H-benzotriazole, 2- [2'-hydroxy-5 '-(meth) acryloyloxypropylphenyl] -2H-benzotriazole, 2- [2 '-Hydroxy-5'-(meth) acryloyloxyhexylphenyl] -2H-benzotriazole, 2- [2'- Droxy-3'-t-butyl-5 '-(meth) acryloyloxyethylphenyl] -2H-benzotriazole, 2- [2'-hydroxy-3'-t-butyl-5'-(meth) acryloyloxyethyl Phenyl] -5-chloro-2H-benzotriazole, 2- [2'-hydroxy-5'-t-butyl-3 '-(meth) acryloyloxyethylphenyl] -2H-benzotriazole, 2- [2'- Hydroxy-5 '-(meth) acryloyloxyethylphenyl] -5-chloro-2H-benzotriazole, 2- [2'-hydroxy-5'-(meth) acryloyloxyethylphenyl] -5-cyano-2H-benzo Triazole, 2- [2'-hydroxy-5 '-(meth) acryloyloxyethylphenyl] -5-t-butyl Benzotriazoles such as 2H-benzotriazole, 2- [2'-hydroxy-5 '-(β- (meth) acryloyloxyethoxy) -3'-t-butylphenyl] -4-t-butyl-2H-benzotriazole UV-absorbing monomers.

2-hydroxy-4- (meth) acryloyloxybenzophenone, 2-hydroxy-4- [2-hydroxy-3- (meth) acryloyloxy] propoxybenzophenone, 2-hydroxy-4- [2- (meth) acryloyloxy] Such as ethoxybenzophenone, 2-hydroxy-4- [3- (meth) acryloyloxy-2-hydroxypropoxy] benzophenone, 2-hydroxy-3-tert-butyl-4- [2- (meth) acryloyloxy] butoxybenzophenone, etc. Benzophenone UV-absorbing monomers.
Etc., and one or more of these can be used.

Examples of the styrene derivative include α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, o-methoxystyrene, m- Methoxystyrene, p-methoxystyrene, o-ethoxystyrene, m-ethoxystyrene, p-ethoxystyrene, o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, o-chlorostyrene, m-chlorostyrene, p- Chlorostyrene, o-bromostyrene, m-bromostyrene, p-bromostyrene, o-acetoxystyrene, m-acetoxystyrene, p-acetoxystyrene, ot-butoxystyrene, mt-butoxystyrene, pt -Butoxystyrene and the like are preferred. These can use 1 type (s) or 2 or more types. In the styrene derivative, the benzene ring is substituted with a functional group such as an alkyl group such as a methyl group or a tert-butyl group, a nitro group, a nitrile group, an alkoxyl group, an acyl group, a sulfone group, a hydroxyl group, or a halogen atom. May be.
Of the styrene and / or styrene derivatives, styrene is preferable.

Further, in the aqueous resin composition of the present invention, it may contain a polymer having the above-described polymerizable ultraviolet-absorbing monomer or ultraviolet-stable monomer as a monomer component, You may contain the ultraviolet absorber and ultraviolet stabilizer which are addition type compounds which do not have a polymerizable unsaturated bond group.
The polymer is preferably obtained by using a silane coupling agent to improve water resistance, and is polymerizable unsaturated such as (meth) acryloyl group, vinyl group, allyl group, propenyl group. A silane coupling agent having a linking group is preferred.

The emulsifier used in the multistage emulsion polymerization is not particularly limited, and a known anionic emulsifier, nonionic emulsifier, cationic emulsifier, or the like can be used.
Examples of the anionic emulsifier include alkyl sulfonate salts such as sodium alkyl diphenyl ether disulfonate (for example, “Perex SSL” manufactured by Kao), ammonium dodecyl sulfonate, sodium dodecyl sulfonate, and the like; ammonium dodecyl benzene sulfone And alkylaryl sulfonate salts such as sodium dodecyl naphthalene sulfonate; polyoxyethylene alkyl sulfonate salts (for example, “Hitenol 18E” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., “Latemul E-118B” manufactured by Kao Corporation, etc. ); Dialkylsulfosuccinate; arylsulfonic acid formalin condensate; fatty acid salt such as ammonium laurate, sodium stearate; bis (polyoxyethylene polycyclic phenyl ether) methacrylate Sulfonated salt (for example, “Antox MS-60” manufactured by Nippon Emulsifier Co., Ltd.), propenyl-alkylsulfosuccinate ester salt, (meth) acrylic acid polyoxyethylene sulfonate salt, (meth) acrylic acid polyoxyethylene Phosphonate salts (for example, “Eleminol RS-30” manufactured by Sanyo Chemical Industries, Ltd.), sulfonate salts of allyloxymethylalkyloxypolyoxyethylene (for example, “Aqualon KH-10” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), etc. A sulfate ester (salt) having an allyl group, a sulfate ester salt of allyloxymethylalkoxyethyl polyoxyethylene (for example, “Adekaria Soap SR-10” manufactured by Asahi Denka Kogyo Co., Ltd.), polyoxyalkylene alkenyl ether ammonium sulfate (for example, , "Latemul PD-" manufactured by Kao 04 ", etc.) and the like are suitable.

Examples of the nonionic emulsifier include polyoxyethylene alkyl ethers (for example, “Naroacty N-200” manufactured by Sanyo Chemical Industries, Ltd., “Neugen TDS series”, “Neugen SD series” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Kao Corporation. "Emulgen 1118S" manufactured by Kao Corporation, "Emulgen 1108S" manufactured by Kao Corporation, etc.) Condensate of polyethylene glycol and polypropylene glycol; sorbitan fatty acid ester; polyoxyethylene sorbitan fatty acid ester; fatty acid monoglyceride; polyoxyalkylene decyl ether (Daiichi Kogyo Seiyaku Co., Ltd. "Neugen XL series"), polyoxyethylene styrenated phenol ether (Daiichi Kogyo Seiyaku "Neugen EA series"); condensation product of ethylene oxide and aliphatic amine; allyloxymethylalkoxy Tylhydroxypolyoxyethylene (for example, “Adekaria soap ER-20” manufactured by Asahi Denka Kogyo Co., Ltd.), polyoxyalkylene alkenyl ether (for example, “Latemul PD-420”, “Latemul PD-430” manufactured by Kao Corporation) Etc. are suitable.

As the cationic emulsifier, for example, alkylammonium salts such as dodecylammonium chloride are suitable.
As the amphoteric emulsifier, for example, a betaine ester type emulsifier is suitable.
Examples of the polymer emulsifier include poly (meth) acrylates such as sodium polyacrylate; polyvinyl alcohol; polyvinylpyrrolidone; polyhydroxyalkyl (meth) acrylates such as polyhydroxyethyl acrylate; and these polymers. A copolymer having one or more of the polymerizable monomers as a copolymerization component is suitable.

The above-mentioned emulsifiers can be used alone or in combination of two or more, and may be used in an amount of about 0.01 to 10% by mass with respect to 100% by mass of the raw material monomer. In order to adjust the weight average molecular weight of the multilayer structure emulsion particles, 2-ethylhexyl thioglycolate, t-dodecyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid, 2-mercaptoethanol , Α-methylstyrene, α-methylstyrene dimer and the like chain transfer agents are used. These may be used in an amount of 0.01 to 10% by mass with respect to 100% by mass of the raw material monomer of the multilayer structure emulsion particles. If the amount is too large, the water resistance of the formed film may decrease.

As the aqueous medium, water is usually used, but if necessary, a hydrophilic solvent such as a lower alcohol such as methanol can be used in combination. What is necessary is just to set the usage-amount of an aqueous medium suitably in consideration of the desired resin solid content and viscosity of the multilayer structure emulsion particle to be obtained. Regarding the addition timing of the aqueous medium, it may be previously charged in a reaction kettle, or may be added as a pre-emulsion during the main polymerization reaction. Moreover, you may use an aqueous medium in processes, such as cooling, washing | cleaning, solid content adjustment, and viscosity adjustment, as needed.

Examples of the polymerization initiator used in the multistage emulsion polymerization include azo compounds such as 2,2-azobis (2-diaminopropane) hydrochloride; persulfates such as potassium persulfate; peroxides such as hydrogen peroxide. Etc.
As the usage-amount of the said polymerization initiator, it is preferable to set it as 0.01-1 mass% with respect to the usage-amount of all the polymerizable unsaturated bond group containing compounds. If it is less than 0.01% by mass, the polymerization rate may be slow and unreacted monomer components may remain. If it exceeds 1% by mass, the water resistance of the formed film may be reduced. . More preferably, it is 0.05-0.8 mass%, More preferably, it is 0.1-0.5 mass%.
The addition method may be any method such as batch charging, divided charging, and continuous dropping. Furthermore, in order to speed up the completion of the polymerization, a part of the polymerization initiator may be added before and after the completion of the dropping of the monomer component in the final stage.

In the polymerization step, for the purpose of accelerating the decomposition of the polymerization initiator, for example, a reducing agent such as sodium bisulfite or a transition metal salt such as ferrous sulfate may be added. Moreover, you may add additives, such as a pH buffer, a chelating agent, a chain transfer agent, and a film-forming auxiliary, as needed.

The polymerization temperature is preferably 0 to 100 ° C. More preferably, it is 40-95 degreeC. The polymerization temperature may be constant or may be changed during the polymerization or at each stage. The polymerization time may be appropriately set according to the progress of the reaction, but for example, it is preferably 2 to 8 hours from the start to the end of the polymerization. The atmosphere during the polymerization is generally carried out in an inert gas atmosphere such as nitrogen in order to increase the efficiency of the polymerization initiator.

In the polymerization step, some or all of the acidic groups of the resulting polymer may be neutralized with a neutralizing agent. The neutralization may be performed after the final stage monomer component is added. For example, in the case of a two-stage polymerization mode, the neutralization may be performed between the first-stage polymerization reaction and the second-stage polymerization reaction. Also good. It can also be performed at the end of the initial reaction.
Examples of the neutralizing agent include alkali metal and alkaline earth metal hydroxides such as sodium hydroxide; alkali metal and alkaline earth metal carbonates such as calcium carbonate; organic amines such as ammonia and monomethylamine; The alkaline substance can be used. Among these, when importance is attached to water resistance, alkaline substances having volatility such as ammonia are preferable.

The multi-layered emulsion particles have a structure in which at least one layer has a monomer unit derived from at least one monomer selected from the group consisting of cyclohexyl (meth) acrylate, styrene, and t-butyl (meth) acrylate. It is preferably formed by coalescence.
The total amount of the monomer units in the polymer constituting the multilayer emulsion particles is preferably 5% by mass or more based on the total amount of the monomer units in the polymer constituting the multilayer emulsion particles. If it is less than 5% by mass, the effects of the present invention may not be sufficiently exhibited.
"The total amount of the monomer units in the polymer constituting the multilayer emulsion particles is 5% by mass or more based on the total amount of the monomer units in the polymer constituting the multilayer emulsion particles" For example, when the multilayer structure emulsion particles are constituted only by the inner layer, the intermediate layer, and the outer layer, regardless of whether one or more of the inner layer, the intermediate layer, and the outer layer contain the specific monomer unit. The total amount of the specific monomer units in the polymer constituting the inner layer, the intermediate layer and the outer layer is 5% by mass or more based on the total amount of monomer units in the polymer constituting the inner layer, the intermediate layer and the outer layer. If it is. More preferably, it is 10 mass% or more.
For example, the multilayer emulsion particles include at least one monomer unit derived from at least one monomer selected from the group consisting of cyclohexyl (meth) acrylate, styrene, and t-butyl (meth) acrylate. The total amount of the monomer units in the polymer constituting the multilayer emulsion particles is 5% by mass based on the total amount of the monomer units in the polymer constituting the multilayer emulsion particles. This is the preferred embodiment of the present invention.
By making such multilayer emulsion particles essential, the aqueous resin composition of the present invention has good low-temperature film-forming properties and excellent hardness and the like of the formed film.
Among them, the multilayer emulsion particles are formed of a polymer having at least one monomer-derived monomer unit selected from the group consisting of cyclohexyl methacrylate, styrene, and t-butyl methacrylate. More preferably.

The present invention is also an aqueous resin composition essentially comprising three or more multilayer emulsion particles, wherein the multilayer emulsion particles are formed by multi-stage emulsion polymerization. Including the emulsion polymerization step, the middle emulsion polymerization step, and the latter emulsion polymerization step, the middle emulsion polymerization step differs from the former emulsion polymerization step in the composition of the monomer to be polymerized, and the middle emulsion polymerization step is more effective than the latter emulsion polymerization step. It is also an aqueous resin composition from which a polymer layer having a high glass transition temperature can be obtained.
The multi-stage emulsion polymerization includes a first-stage emulsion polymerization process, a middle-stage emulsion polymerization process, and a second-stage emulsion polymerization process, and is performed in this order, and a layer in the multilayer structure emulsion particles is formed by a polymer obtained by each polymerization process. Will be. In this embodiment, the preceding, middle, and subsequent steps may be essential, and other emulsion polymerization steps may be included before the preceding step, between the preceding and middle steps, between the middle and subsequent steps, and after the subsequent steps. Good.
By making such multilayer emulsion particles essential, the aqueous resin composition of the present invention has good low-temperature film-forming properties and excellent hardness and the like of the formed film.
Preferred forms of the layer formed by the polymer obtained by the preceding emulsion polymerization process, the middle emulsion polymerization process, and the latter emulsion polymerization process are the same as the preferred forms of the inner layer, the intermediate layer, and the outer layer, respectively. . Moreover, the preferable form of the said aqueous resin composition is the same as the preferable form of this invention mentioned above.

The aqueous resin composition of the present invention preferably has a minimum film forming temperature of 10 ° C or lower.
If the minimum film-forming temperature (hereinafter also referred to as MFT) exceeds 10 ° C., it is necessary to add a small amount of an organic compound such as a film-forming aid. Moreover, there is a possibility that it becomes impractical when painting in the open air.
The MFT is more preferably 5 ° C. or less, and further preferably 0 ° C. or less.
MFT is measured according to JIS K6828-2 (2003), and is a boundary temperature between a film-formed part and a non-film-formed part when an emulsion is applied in a strip shape on a flat plate having an appropriate temperature gradient. Yes, and is defined as “the lowest temperature at which a uniform film without cracks is obtained”. In the present invention, an MFT tester (“TP-801 LT type” manufactured by Tester Sangyo Co., Ltd.) is used, and a 250 μm (wet) film is produced on a stainless steel grooveless flat plate with an applicator, and the measurement temperature range is −5 ° C. The minimum film forming temperature (° C.) can be measured at ˜ + 30 ° C. The presence or absence of a crack in the film can be determined visually according to JIS K6828-2.

The film obtained by drying the aqueous resin composition of the present invention at 23 ° C. for 24 hours preferably has a KOENIG hardness of 4 times or more, and more preferably 9 times or more. This film refers to a film formed only from the aqueous resin composition of the present invention, and is not a “coating film” obtained from the paint after the paint additive or the like is blended with the aqueous resin composition of the present invention. . In the present specification, for convenience, a film obtained only from the aqueous resin composition of the present invention is referred to as “film”, and a film obtained from the paint for building exterior topcoat of the present invention is referred to as “coating film”.
The aqueous resin composition of the present invention preferably has a Königs hardness of 4 times or more. If the above film has a König hardness of less than 4 times, it may not be possible to obtain a coating film having excellent hardness intended in the present invention.

As the above-mentioned Koenig hardness, a value measured using a pendulum type hardness meter (Konig type; model 299; manufactured by Eriksen (Germany)) is adopted. Specifically, a 250 μm (wet; solid content concentration: 40 to 60% by mass) film of the aqueous resin composition was prepared on a glass plate with an applicator and allowed to stand at 23 ° C. for 24 hours. Set in a type hardness tester, the measurement start angle is 6 °, and the number of reciprocations of the pendulum (tungsten carbide steel ball) until the measurement end angle falls below 3 ° is the Königs hardness (times). If the coating film has tack, the pendulum stops, so that the larger the number, the harder the hardness and the better the performance.

This invention is also a manufacturing method of the aqueous resin composition which prepares the said aqueous resin composition.
By the production method of the present invention, the amount of volatile organic compounds is small, water resistance is improved, weather resistance is excellent, and environmentally advantageous. It is possible to easily produce an aqueous resin composition that can be suitably used in the process.
The preferred forms of the raw material, polymerization conditions, additives, etc. of the method for producing the aqueous resin composition of the present invention are the same as the preferred forms of the aqueous resin composition of the present invention described above.

The present invention is also a coating for a building exterior top coat containing the aqueous resin composition of the present invention.
The coating for building exterior topcoat of the present invention is excellent in low-temperature film-forming properties, and the coating film formed thereby can exhibit characteristics such as hardness, and is used in various applications such as building and building exterior coatings. Can be suitably used. Moreover, since it contains the said aqueous resin composition, even if the organic compound is reduced, it is excellent in low-temperature film-forming property.
The content ratio of the aqueous resin composition of the present invention in the paint for building exterior topcoats of the present invention is preferably, for example, 10% by mass or more and 90% by mass or less with respect to 100% by mass of the paint for building exterior topcoats. More preferably, they are 15 mass% or more and 85 mass% or less, More preferably, they are 20 mass% or more and 80 mass% or less. If it is less than 10% by mass or more than 90% by mass, it may not be suitable as a coating for a building exterior topcoat of the present invention.
When the mass of the building exterior topcoat paint is 100% by mass, the total amount of volatile organic compounds is preferably 1% by mass or less. By setting the paint for a building exterior topcoat according to the present invention as described above, it is possible to obtain a paint that does not place a burden on the environment while maintaining the properties as a paint.
In addition, although the coating material containing the aqueous resin composition of the present invention is one of the present invention, the architectural exterior topcoat coating material of the present invention is preferably one of the coating materials including the aqueous resin composition of the present invention. It can be said that this is an embodiment.

The architectural exterior topcoat paint of the present invention may contain additives as necessary, and examples of the additives include pigments and aggregates.
Examples of the pigment include inorganic pigments such as titanium oxide, antimony trioxide, zinc white, lithopone, lead white and other white pigments, carbon black, yellow lead, molybdenum red, red pigments and the like, Examples of the organic pigment include azo compounds such as benzidine and hanza yellow, and phthalocyanines such as phthalocyanine blue. These may be used alone or in combination of two or more. It is preferable to select one having good weather resistance so as not to lower the weather resistance of the coating film. For example, with respect to titanium oxide which is a white pigment, rutile type is used rather than using anatase type titanium oxide. It is preferable to use titanium oxide in terms of the weather resistance of the coating film. As the rutile type, chlorine-based titanium oxide is more preferable than sulfuric acid-based titanium oxide because weather resistance can be maintained and expressed over a long period of time.

The aggregate may be a transparent aggregate or a colored aggregate. Examples of the transparent aggregate include feldspar, cinnabar, meteorite, cold water sand, glass beads, synthetic resin beads, and the like. Examples of the colored aggregate include marble powder, granite powder, serpentine, fluorite, colored cinnabar powder, colored ceramic powder, etc., and these may be used alone or in combination of two or more. .
When the additive such as the pigment or the aggregate is included, the content ratio in the paint for building exterior topcoat of the present invention is 40% by mass when used for a clear paint or the like in order to fully exhibit the effect. Less than is preferable. Moreover, when using for an enamel paint etc., Preferably it is 5-80 mass%, More preferably, it is 10-70 mass%, More preferably, it is 20-60 mass%.
In addition to the pigments and aggregates, they may further contain fillers, leveling agents, dispersants, thickeners, wetting agents, plasticizers, stabilizers, dyes, antioxidants, and the like. These may be used alone or in combination of two or more.

The building exterior topcoat paint may be applied in a single layer, or may be applied in two or more layers. Further, when two or more layers are overcoated, only a part of the layers may be formed by the paint for building exterior topcoat of the present invention, or all the layers may be used for the building exterior topcoat of the present invention. The form formed with a paint may be sufficient.
For example, the above-described overcoating method may be performed by applying a first layer (undercoat layer) paint to a coating object that has been subjected to primer treatment or sealer treatment, and then drying, followed by the second layer (overcoat layer) paint. The method of overcoating and drying can be mentioned. As a method for applying the paint, spray, roller, brush, or iron can be used.

The aqueous resin composition and the paint for building exterior topcoat containing the same according to the present invention can be used for various applications, for example, for plastic molded products, for home appliances, steel products, large structures, vehicles (for example, It can be used for various undercoating, intermediate coating, top coating, etc. for solid color for automobile repair, for metallic base, for clear top), for building materials, for interior / exterior of buildings, for roof tiles, for woodwork. In particular, it can be suitably used as a building material, a building interior / exterior, and more preferably a building material or a building exterior. Furthermore, it can be preferably used for a clear top coat for a stone-like paint. Such a water-based resin composition for building and building materials topcoat using the water-based resin composition of the present invention is also one preferred embodiment of the present invention. More preferably, it is an aqueous resin composition for clear top of building materials.
When using the aqueous resin composition of the present invention and the paint for building exterior topcoat containing the same as a building material, examples of the base material include slate plates, flexible boards, cement slag papermaking plates, cement slag molding plates, Hard wood chip cement board, extrusion molding cement board, metal board, plastic board, ceramic board, calcium silicate board, wood board, metal part steel plate etc. can be mentioned, and coating film is formed by applying on these base materials can do. In addition, when used for building exteriors, examples of the base material include concrete, PC panel, cement mortar, ALC panel, concrete block, slate board, asbestos cement siding, etc. A coating film can be formed by applying to.

The aqueous resin composition of the present invention has the above-mentioned constitution, has a small amount of volatile organic compounds, can form a film with improved water resistance and excellent weather resistance, and is environmentally advantageous. For example, it can be suitably used in various applications such as paints for building materials and building exteriors.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by mass” and “%” means “% by mass”.

< Reference Example 1>
In a flask equipped with a dropping funnel, a stirrer, a nitrogen introduction tube, a thermometer and a reflux condenser, 460 parts of deionized water and an emulsifier “AQUALON (registered trademark) KH-10” (anionic reactive surfactant [polyoxyalkyl] 8 parts of a 25% aqueous solution of ether sulfate ammonium salt], trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and heated to 78 ° C. with stirring while gently blowing nitrogen gas.
After the temperature increase, the mixed solution of the first-stage monomer composition (first-stage pre-emulsion composition) shown in Table 2 in an aqueous solution of the emulsifier “AQUALON (registered trademark) KH-10” adjusted to 8% concentration is 67% as the monomer concentration. Then, 15 parts of pre-emulsion (10 parts as a monomer) prepared by mixing well was added to the flask all at once. After the flask internal temperature was stabilized at 75 ° C., 100 parts of a 3% aqueous potassium persulfate solution was added to initiate polymerization. At this time, the temperature in the reaction system was raised to 80 ° C. and maintained for 20 minutes. This is the first stage polymerization reaction.
After completion of the first stage polymerization reaction, the second stage monomer composition shown in Table 3 with an aqueous solution of an emulsifier “AQUALON (registered trademark) KH-10” adjusted to 8% concentration while maintaining the reaction system at 80 ° C. Second-stage pre-emulsion composition) 600 parts of pre-emulsion (400 parts as monomer) prepared by mixing well so that the mixed solution becomes 67% as the monomer concentration was uniformly dropped over 60 minutes and then aged at 80 ° C. for 60 minutes did. The process up to this point was defined as the second stage polymerization reaction.
After completion of the second stage polymerization reaction, the third stage monomer composition shown in Table 4 with an aqueous solution of an emulsifier “AQUALON (registered trademark) KH-10” adjusted to 8% concentration while maintaining the reaction system at 80 ° C. (3rd stage pre-emulsion composition) 881 parts of pre-emulsion (590 parts as monomer) prepared by mixing well so that the mixed solution becomes 67% as monomer concentration was dropped uniformly over 120 minutes and then aged at 80 ° C for 120 minutes did. The process up to here was designated as the third stage polymerization reaction.
After cooling to room temperature, 25% aqueous ammonia was added so that the pH was 8.5. Furthermore, after adding deionized water so that a solid content concentration might be 50%, it filtered with the 100-mesh metal-mesh, and the emulsion 1 was obtained.

(Emulsion property evaluation)
The minimum film-forming temperature (MFT) and Konig hardness of the obtained emulsion 1 were measured, and the results are shown in Table 7.
(Painting and paint physical property evaluation)
Next, the obtained emulsion 1 was made into a paint by adjusting the amount of the thickener so that the viscosity became 80 KU with the formulation shown in Table 6, and paint 1 was obtained.
The minimum film-forming temperature (MFT), König hardness, water resistance and gloss of the obtained paint 1 were measured, and the results are shown in Table 7.

The monomer composition in each of the following examples is as shown in the first-stage pre-emulsion composition to the fourth-stage pre-emulsion composition shown in Tables 2 to 5 below.
<Example 2>
The pre-emulsion composition of the first to third stages is as shown in Tables 2 to 4, the pre-emulsion amount of the first stage is “45 parts (30 parts as a monomer)”, and the second stage emulsifier is “Hitenol (registered) Trademark) 18E "(anionic surfactant [polyoxyethylene alkyl ether ammonium sulfate salt], trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and the pre-emulsion amount changed to" 640 parts (430 parts as a monomer) " Then, polymerization and evaluation were performed in the same manner as in Reference Example 1 except that the amount of the pre-emulsion in the third stage was changed to “800 parts (540 parts as a monomer)”.

<Example 3>
The pre-emulsion composition in the first to third stages is as shown in Tables 2 to 4, the pre-emulsion amount in the first stage is "75 parts (50 parts as a monomer)", and the second stage emulsifier is "Latemul (registered trademark)" ) PD-104 "(anionic reactive surfactant, trade name, manufactured by Kao Corporation), the pre-emulsion amount was changed to" 522 parts (350 parts as a monomer) ", and the pre-emulsion amount in the third stage The polymerization and the evaluation were performed in the same manner as in Reference Example 1 except that the value was changed to “900 parts (600 parts as a monomer)”.

<Example 4>
The pre-emulsion composition of the 1st to 3rd stages is as shown in Tables 2 to 4, and the first stage emulsifier is “Hytenol (registered trademark) 18E” (anionic surfactant [polyoxyethylene alkyl ether ammonium sulfate salt], The product name was changed to “Daiichi Kogyo Seiyaku Co., Ltd.”, the pre-emulsion amount was “150 parts (100 parts as a monomer)”, and the second stage emulsifier was “Antox MS-60” (anionic reactive surfactant). , Trade name, manufactured by Asahi Denka Co., Ltd., the pre-emulsion amount was changed to "373 parts (250 parts as a monomer)", and the third-stage emulsifier was "Latemul (registered trademark) PD-104" (anionic system) Reactive surfactant, trade name, manufactured by Kao Co., Ltd.) and polymerization and polymerization were conducted in the same manner as in Reference Example 1 except that the amount of pre-emulsion was changed to “970 parts (650 parts as a monomer)”. Evaluation was performed.

<Example 5>
The pre-emulsion composition of the 1st to 3rd stages is as shown in Tables 2 to 4, and the first stage emulsifier is “Hytenol (registered trademark) 18E” (anionic surfactant [polyoxyethylene alkyl ether ammonium sulfate salt], The product name was changed to “Daiichi Kogyo Seiyaku Co., Ltd.”, the amount of pre-emulsion was set to “373 parts (250 parts as a monomer)”, and 150 parts of 373 parts of pre-emulsion were charged into the flask all at once. After the flask internal temperature was stabilized at 75 ° C., 100 parts of a 3% aqueous potassium persulfate solution was added to initiate polymerization. At this time, the temperature in the reaction system was raised to 80 ° C. and maintained for 20 minutes. Further, 150 parts of the remaining pre-emulsion was added dropwise over 60 minutes. This is the first stage polymerization reaction. Next, the second stage emulsifier was changed to “Antox MS-60” (anionic reactive surfactant, trade name, manufactured by Asahi Denka Co., Ltd.), and the pre-emulsion amount was “300 parts (200 parts as a monomer)”. The emulsifier of the third stage was changed to “Latemul (registered trademark) PD-104” (anionic reactive surfactant, trade name, manufactured by Kao Corporation), and the pre-emulsion amount was changed to “820 parts (550% as a monomer). Polymerization and evaluation were carried out in the same manner as in Reference Example 1 except that the part was changed to “Part.

< Reference Example 6>
The pre-emulsion composition of the 1st to 3rd stages is as shown in Tables 2 to 4, and the first stage emulsifier is “Hytenol (registered trademark) 18E” (anionic surfactant [polyoxyethylene alkyl ether ammonium sulfate salt], The product name was changed to “Daiichi Kogyo Seiyaku Co., Ltd.”, the pre-emulsion amount was “150 parts (100 parts as a monomer)”, and the second stage emulsifier was “Antox MS-60” (anionic reactive surfactant). , Trade name, manufactured by Asahi Denka Co., Ltd., the pre-emulsion amount was changed to "373 parts (250 parts as a monomer)", and the third-stage emulsifier was "Latemul (registered trademark) PD-104" (anionic system) Reactive surfactant, trade name, manufactured by Kao Co., Ltd.) and polymerization and polymerization were conducted in the same manner as in Reference Example 1 except that the amount of pre-emulsion was changed to “970 parts (650 parts as a monomer)”. Evaluation was performed.

<Reference Example 7 >
The first to third stage pre-emulsion composition is as shown in Tables 2 to 4, and the first stage pre-emulsion is changed to 45 parts (30 parts as monomer), and the second stage pre-emulsion is changed to 641 parts (as monomer). 430 parts), 450 parts (300 parts as a monomer) of the third-stage pre-emulsion was uniformly added dropwise over 60 minutes, and then aged at 80 ° C. for 60 minutes. Further, after completion of the third-stage polymerization, Was maintained at 80 ° C., and the mixed solution of the fourth-stage monomer composition (fourth-stage pre-emulsion composition) shown in Table 5 with an aqueous solution of an emulsifier “KH-10” adjusted to 8% concentration was adjusted to 67% as the monomer concentration. A pre-emulsion 358 parts (240 parts as a monomer) prepared by mixing well was uniformly added dropwise over 60 minutes, followed by aging at 80 ° C. for 120 minutes. Polymerization and evaluation were performed in the same manner as in Reference Example 1 except that this was the fourth-stage polymerization reaction, which was cooled to room temperature.

< Reference Example 8>
The first to third stage pre-emulsion composition is as shown in Tables 2 to 4, and the first stage pre-emulsion is changed to 45 parts (30 parts as monomer), and the second stage pre-emulsion is 150 parts (as monomer). 100 parts), and 522 parts (350 parts as a monomer) of the third stage pre-emulsion were uniformly added dropwise over 60 minutes, followed by aging at 80 ° C. for 60 minutes, and after completion of the third stage polymerization, Was maintained at 80 ° C., and the mixed solution of the fourth-stage monomer composition (fourth-stage pre-emulsion composition) shown in Table 5 with an aqueous solution of an emulsifier “KH-10” adjusted to 8% concentration was adjusted to 67% as the monomer concentration. A pre-emulsion 780 parts (520 parts as a monomer) prepared by mixing well was uniformly added dropwise over 60 minutes and then aged at 80 ° C. for 120 minutes. Polymerization and evaluation were performed in the same manner as in Reference Example 1 except that this was the fourth-stage polymerization reaction, which was cooled to room temperature.

< Reference Example 9>
The pre-emulsion composition of the 1st to 3rd stages is as shown in Tables 2 to 4, and the pre-emulsion of the 1st stage is changed to 75 parts (50 parts as a monomer) and the emulsifier of the 2nd stage is changed to “PD-104”. The polymerization and evaluation were performed in the same manner as in Reference Example 1 except that the pre-emulsion was changed to 522 parts (350 parts as a monomer) and the third-stage pre-emulsion was changed to 900 parts (600 parts as a monomer).

< Reference Example 10>
The composition of the 1st to 3rd stages of the pre-emulsion is as shown in Tables 2 to 4. The polymerization and evaluation were performed in the same manner as in Reference Example 1 except that the pre-emulsion was changed to 640 parts (430 parts as a monomer) and the third-stage pre-emulsion was changed to 800 parts (540 parts as a monomer).

<Comparative Example 1>
The pre-emulsion composition of the 1st to 3rd stages is as shown in Tables 2 to 4, and the first stage emulsifier is “Hytenol (registered trademark) 18E” (anionic surfactant [polyoxyethylene alkyl ether ammonium sulfate salt], The product name was changed to “Daiichi Kogyo Seiyaku Co., Ltd.”, the pre-emulsion amount was set to “450 parts (300 parts as a monomer)”, and 150 parts of 450 parts of the pre-emulsion were charged into the flask at once. After the flask internal temperature was stabilized at 75 ° C., 100 parts of a 3% aqueous potassium persulfate solution was added to initiate polymerization. At this time, the temperature in the reaction system was raised to 80 ° C. and maintained for 20 minutes. Further, 300 parts of the remaining pre-emulsion was added dropwise over 60 minutes. This is the first stage polymerization reaction. Next, the second stage emulsifier was changed to “Antox MS-60” (anionic reactive surfactant, trade name, manufactured by Asahi Denka Co., Ltd.), and the pre-emulsion amount was “373 parts (250 parts as a monomer)”. The third-stage emulsifier was changed to “Latemul (registered trademark) PD-104” (anionic reactive surfactant, trade name, manufactured by Kao Corporation), and the pre-emulsion amount was “670 parts (450 monomer as monomer). Polymerization and evaluation were carried out in the same manner as in Reference Example 1 except that the part was changed to “Part.

<Comparative example 2>
The pre-emulsion composition in the first to third stages is as shown in Tables 2 to 4, and the pre-emulsion amount in the first stage is changed to “150 parts (100 parts as a monomer)”. Polymerization and evaluation were performed in the same manner as in Reference Example 1 except that the amount of pre-emulsion in the third stage was changed to “970 parts (650 parts as a monomer)”. The composition of the first and second stages is the same, and the particle layer has two layers.

<Comparative Example 3>
The first and second stage pre-emulsion compositions are as shown in Tables 2 and 3, and the first stage pre-emulsion is changed to 150 parts (100 parts as monomer), and the second stage pre-emulsion is 1343 parts (as monomer). 900 parts) was uniformly dropped over 180 minutes, then aged at 80 ° C. for 120 minutes and changed to cooling to room temperature, and polymerization and evaluation were performed in the same manner as in Reference Example 1 except that the third stage was not produced. . The composition of the first and second stages is the same, and the particle layer is one layer.

<Comparative Example 4>
The first to third stage pre-emulsion composition is as shown in Tables 1 to 3, and the first stage pre-emulsion was changed to 150 parts (100 parts as monomer), and the second stage pre-emulsion was 373 parts (250 monomers). Part) and the third pre-emulsion was changed to 970 parts (650 parts as a monomer), and polymerization and evaluation were performed in the same manner as in Reference Example 1.
In the present specification, IBA represents isobornyl acrylate. IBM stands for isobornyl methacrylate. HALS represents ADEKA STAB (registered trademark) LA-82 (light stabilizer, trade name, manufactured by ADEKA CORPORATION). In Table 7, “CHMA, St, t-BMA total amount (%)” is cyclohexyl methacrylate in the polymer constituting the multilayer emulsion particles relative to the total amount of monomer units in the polymer constituting the multilayer emulsion particles, It represents the total amount of monomer units derived from styrene and t-butyl methacrylate.

(Evaluation criteria for Königs hardness of emulsion film)
◎: 10 times or more ○: 7 to 9 times Δ: 4 to 6 times ×: 0 to 3 times (Evaluation criteria for Königs hardness of paint coating film)
◎: 16 times or more ○: 13-15 times Δ: 10-12 times ×: 0-9 times

(Evaluation criteria for water resistance of paint film)
○: No abnormality Δ: Swelling / peeling is observed in an area of less than 5% ×: Swelling / peeling is observed in an area of 5% or more (evaluation criteria for gloss of paint coating film)
○: 78 or more Δ: 70 or more, less than 78 ×: less than 70

(Measurement of Koenig hardness)
The Konig hardness was measured using a pendulum type hardness meter (Konig type; model 299; manufactured by Eriksen (Germany)). Specifically, a 250 μm (wet; solid content concentration: 40 to 60% by mass) film of an aqueous resin composition is prepared on a glass plate with an applicator and is not directly exposed to a constant temperature wind at 23 ° C. and a humidity of 50%. After drying for 24 hours at the place, set this coated plate on the above pendulum type hardness meter, set the measurement start angle to 6 °, and the number of reciprocations of the pendulum (tungsten carbide steel ball) until the measurement end angle falls below 3 °. It was set to Koenig hardness (times).

(Measurement of minimum film-forming temperature)
The minimum film-forming temperature (MFT) was measured according to JIS K6828-2 (2003). Using an MFT tester (“TP-801 LT type” manufactured by Tester Sangyo Co., Ltd.), a 200 μm (wet) film was produced on a stainless steel grooveless flat plate with an applicator, and the measurement temperature range was −5 ° C. to + 30 ° C. The minimum film forming temperature (° C.) was measured. The presence or absence of cracks in the film was visually determined according to JIS K6828-2.

(Differential scanning calorimetry)
As the glass transition temperature, two peaks were observed on a low temperature side of 0 ° C. or lower and a high temperature side of 100 ° C. or higher.
In differential scanning calorimetry (DSC measurement), for example, measurement was performed under the following conditions.
Body: DSC220 (trade name, manufactured by Seiko)
Temperature program:
20 ° C to 200 ° C: 20 ° C / min,
200 ° C to -100 ° C: 10 ° C / min (measurement pretreatment stage),
−100 ° C. to 200 ° C .: 20 ° C./min (measurement),
200 ° C. to 20 ° C .: 10 ° C./min (cooling).
The temperature program indicates a temperature change per unit time in each temperature range.
In FIG. 1, “Temp Cel” indicates a cell temperature (° C.). “DSC” indicates differential scanning calorimetry, and “DDSC” indicates temperature modulated differential scanning calorimetry. FIG. 1 shows the measurement using the coating film formed from the paint for building exterior topcoat of the present invention obtained in Example 3.

(Coating phase detection)
Phase detection is a detection method that uses the phase difference signal between the excitation signal and the detection signal as a feedback signal during amplitude detection, and can detect slight amplitude changes such as friction, viscoelasticity, magnetism, and surface potential. it can. For this reason, when there is a distribution in the sample composition, a contrast (high Tg is white and low Tg is black) is depicted and observed with a characteristic difference (mainly Tg difference). In addition, it is known that it is affected by the depth direction, that is, the inside of the particle although it is surface observation.
In the Examples, it is recognized that a high Tg polymer component is present as an intermediate layer in one particle in a coating film in which particles of about 150 nm are formed.
FIG. 2 shows the phase detection results for the coating film formed from the paint for building exterior topcoat of the present invention obtained in Example 3.
(Measurement with an atomic force microscope (AFM))
Measurement with an atomic force microscope (AFM) was performed under the following conditions.
Atomic Force Microscope (AFM): Scanning probe microscope (manufactured by Veeco)
Application: Tapping mode AFM,
Microscope type: D3100EX,
SPM probe: Single crystal Si probe NCH-10V
Scan condition: scan size: 1.0 μm, scan speed: 0.8 Hz, scan line: 512, date scale height: 50 nm, date scale phase ( Date Scale phase): 50.

(Measurement of average particle size)
For example, after the emulsion is diluted with distilled water and sufficiently stirred and mixed, about 10 ml of the average particle size is collected in a glass cell, and this is collected by NICOM P Model 380 (particle size distribution analyzer, trade name, It can be determined by measurement using Windows-based software (Windows (registered trademark) Based Software) by Particle Sizing Systems (manufactured by Particle Sizing Systems). The analysis method can be carried out by a volume-weighted Gaussian distribution analysis (VOLUME-Weighted GAUSSIAN DISTRIBUTION ANALYSIS).

(Measurement of water resistance)
Nozawa flexible sheet (JIS K-5410: test plate as defined in 1990, slate plate, trade name, manufactured by Nozawa Co., Ltd.) was coated on a DAN transparent sealer (manufactured by Nippon Paint) at 130g / ^{m 2} brush and dried for 1 day The paint was applied to a sealer plate with a 6 mil applicator, dried at room temperature for 1 day, then immersed in water at 23 ° C., the state of the coating film after 7 days was observed, and judged based on the criteria.

(Gloss value measurement)
The paint was applied to a glass plate with a 6 mil applicator, dried at room temperature for 1 day, and then a 60 ° gloss value was measured with a gloss meter.

In the above-described Examples and Comparative Examples, only three-layer emulsion particles and four-layer emulsion particles are disclosed as the multilayer structure emulsion particles. However, the multilayer structure emulsion particles are an intermediate layer, an outer layer outside the intermediate layer, An inner layer is included in the intermediate layer, the intermediate layer has a higher glass transition temperature than the outer layer, and the structural unit of the polymer constituting the intermediate layer is the structural unit of the polymer constituting the inner layer. As long as it is a form which is different, the action mechanism which produces the effect of this invention is the same. That is, in the aqueous resin composition, the multilayer structure emulsion particles essential for the aqueous resin composition have the above-mentioned constitution, and the essential characteristics of the present invention are the same. If it has chemical characteristics, etc., the effects as shown in this embodiment will be achieved. Therefore, if it is set as the aqueous resin composition which uses the multilayer structure emulsion particle | grains in this invention as essential, it can be said that the advantageous effect of this invention is expressed reliably.

It is a figure which shows the result of the differential scanning calorimetry (DSC measurement) of the coating film formed from the coating material for building exterior topcoats of this invention. It is the figure which showed the phase detection result using the atomic force microscope of the coating film formed from the coating material for building exterior topcoats of this invention.

Claims (5)

An aqueous resin composition essentially comprising three or more multilayer emulsion particles,
The multilayer structure emulsion particles are multilayer structure acrylic emulsion particles, and include an intermediate layer, an outer layer outside the intermediate layer, and an inner layer inside the intermediate layer, and the glass transition temperature of the outer layer is −50 to −10 ° C. And the glass transition temperature of the intermediate layer is 90 to 150 ° C., and the constituent unit of the polymer constituting the intermediate layer is different from the constituent unit of the polymer constituting the inner layer, and constitutes the multilayer emulsion particles. When the total polymer to be treated is 100% by mass, the outer layer exceeds 50% by mass and is 84% by mass or less, the intermediate layer is 15 to 45% by mass, and the inner layer is 3 to 25% by mass. An aqueous resin composition. The multi-layered emulsion particles have a structure in which at least one layer has a monomer unit derived from at least one monomer selected from the group consisting of cyclohexyl (meth) acrylate, styrene, and t-butyl (meth) acrylate. The total amount of the monomer units in the polymer constituting the multilayer emulsion particles formed by coalescence is 5% by mass or more based on the total amount of the monomer units in the polymer constituting the multilayer emulsion particles. The aqueous resin composition according to claim 1, wherein the aqueous resin composition is present. An aqueous resin composition essentially comprising three or more multilayer emulsion particles,
The multi-layered emulsion particles are multi-layered acrylic emulsion particles and are formed by multi-stage emulsion polymerization. The multi-stage emulsion polymerization includes a first-stage emulsion polymerization process, a middle-stage emulsion polymerization process, and a second-stage emulsion polymerization process. In the emulsion polymerization process, the composition of the monomer to be polymerized is different from that in the previous emulsion polymerization process, and a polymer layer having a glass transition temperature of 90 to 150 ° C. is obtained by the middle emulsion polymerization process, and the glass transition is performed by the latter emulsion polymerization process. When a polymer layer having a temperature of −50 to −10 ° C. is obtained and the total amount of the polymer constituting the multilayer emulsion particles is 100% by mass, the polymer layer obtained by the former emulsion polymerization step is 3 to 25% by mass. The polymer layer obtained by the middle emulsion polymerization step is 15 to 45% by mass, and the polymer layer obtained by the latter emulsion polymerization step is 50% by mass. Beyond, the aqueous resin composition being not more than 84 wt%. An architectural exterior topcoat paint comprising the aqueous resin composition according to claim 1. The building exterior topcoat paint according to claim 4, wherein the amount of the total volatile organic compound is 1% by mass or less, assuming that the mass of the exterior exterior topcoat paint is 100% by mass.

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