JP2010006930A - Aqueous coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-package type aqueous coating composition inhibiting softening of the coating film by sebum, stain of the coating film by handling, and delamination of the coating film. <P>SOLUTION: The present aqueous coating composition is a one-package type coating composition wherein a copolymer is dispersed in water, the copolymer being obtained from monomer mixture of cyano group-containing ethylenically unsaturated monomer and (meth)acrylic acid/acetoacetic acid diester of alkylene glycol. The composition contains 5-30 wt.% of the cyano-containing ethylenically unsaturated monomer and 1-10 wt.% of (meth)acrylic acid/acetoacetic acid diester of alkylene glycol, based on the total amount of the monomer mixture, and has resistance to sebum softening. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a one-component aqueous coating composition having sebum softening resistance.

In recent years, from the viewpoint of environmental protection, there is a social demand for switching from solvent-based paints to water-based paints. When such a water-based paint composition is applied to a part that is frequently touched by human hands (for example, a handrail of a staircase or a door), a part touched by a human hand compared to a solvent-based paint composition. The problem of softening the coating film tends to occur. The softening of the paint film not only causes the dirt on the hand and the like to be easily attached, but also causes the paint film to peel off due to physical contact such as repeated contact of the human hand, so a solution is desired. Yes.
JP-A-8-104829

  The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to provide a one-component water-based paint capable of suppressing softening of a coating film by sebum, scratches on the coating film and peeling of the coating film. It is to provide a composition.

  The aqueous coating composition of the present invention is a one-component aqueous coating composition in which a copolymer obtained from a monomer mixture containing a cyano group-containing ethylenically unsaturated monomer and a (meth) acrylic acid acetoacetic acid diester of alkylene glycol is dispersed in water. The content of the cyano group-containing ethylenically unsaturated monomer is 5 to 30% by weight based on the total amount of the monomer mixture, and the content of the (meth) acrylic acid acetoacetic acid diester of the alkylene glycol is It is 1 to 10% by weight based on the total amount of the monomer mixture, and has sebum softening resistance.

  In a preferred embodiment, the cyano group-containing ethylenically unsaturated monomer is acrylonitrile.

  In a preferred embodiment, the (meth) acrylic acid acetoacetic acid diester of alkylene glycol is 2-acetoacetoxyethyl methacrylate.

  According to another aspect of the present invention, an architectural paint is provided. The architectural paint of the present invention contains the water-based paint.

  According to still another aspect of the present invention, a method for forming a sebum softening-resistant coating film is provided. The sebum softening-resistant coating film forming method of the present invention includes a step of applying the aqueous coating composition to an object to be coated, and a step of drying the coating film after the application step.

  According to the present invention, an aqueous coating composition in which a copolymer having a specific content ratio of a repeating unit derived from a cyano group-containing ethylenically unsaturated monomer and a (meth) acrylic acid acetoacetic acid diester of alkylene glycol is dispersed in water. By using, it is possible to obtain a coating film having a small environmental load and excellent sebum softening resistance. More specifically, the water-based coating composition of the present invention not only provides sebum softening resistance equal to or higher than that of the solvent-based coating composition while being aqueous, but also a period until the sebum softening resistance is developed. Is significantly shorter than the solvent-based coating composition. Such an effect is a knowledge obtained for the first time by actually preparing an aqueous coating composition using a copolymer having the specific repeating unit in a specific content ratio. is there. Furthermore, the aqueous coating composition of the present invention is excellent in workability, such as being able to be used as a one-pack type coating.

A. Copolymer The copolymer used in the aqueous coating composition of the present invention is obtained by copolymerizing a monomer mixture containing a cyano group-containing ethylenically unsaturated monomer and a (meth) acrylic acid acetoacetic acid diester of alkylene glycol. be able to.

  Arbitrary appropriate things can be employ | adopted as said cyano group containing ethylenically unsaturated monomer. For example, acrylonitrile, methacrylonitrile, chloroacrylonitrile and the like can be used. Acrylonitrile is preferred. These cyano group-containing ethylenically unsaturated monomers may be used alone or in combination of two or more. Since the cyano group-containing ethylenic monomer has a high polarity, the aqueous coating composition of the present invention is not easily compatible with sebum, and a coating film densified by hydrogen bonding between cyano groups can be obtained. As a result, the coating film obtained from the aqueous coating composition of the present invention has little sebum adhesion and penetration and is excellent in sebum softening resistance. In the present specification, “sebum softening resistance” refers to resistance to a phenomenon in which a coating film softens due to adhesion and penetration of sebum generated from a human body or the like (for example, sebum generated from a human hand).

  The content of the cyano group-containing ethylenically unsaturated monomer is 5 to 30% by weight, preferably 10 to 25% by weight, more preferably 12 to 18% by weight, based on the total amount of the monomer mixture. is there. If the content of the cyano group-containing ethylenically unsaturated monomer is less than 5% by weight, the resulting coating film may not have sufficient sebum softening resistance. When the content ratio is more than 30% by weight, the adhesion to the object to be coated may be insufficient.

Arbitrary appropriate things can be employ | adopted as (meth) acrylic-acid acetoacetic acid diester of the said alkylene glycol. For example, 2-acetoacetoxyethyl acrylate, 2-acetoacetoxyethyl methacrylate, 2-acetoacetoxypropyl acrylate, 2-acetoacetoxypropyl methacrylate, 2-cyanoacetoacetoxyethyl methacrylate and the like can be used. 2-acetoacetoxyethyl methacrylate is preferred. These (meth) acrylic acetoacetic acid diesters of alkylene glycols can be used alone or in combination of two or more. By containing (meth) acrylic acid acetoacetic acid diester of alkylene glycol, the adhesion between the resulting coating film and the coated layer can be improved. Therefore, the water-based coating composition of the present invention can exhibit the adhesion even when a considerable amount of a cyano group-containing ethylenically unsaturated monomer capable of reducing the adhesion to the coated layer is contained during the polymerization of the copolymer. A sufficient coating film can be formed. That is, according to the aqueous coating composition of the present invention, the copolymer has a sebum softening-resistant effect by having a repeating unit derived from a cyano group-containing ethylenically unsaturated monomer, and the above-mentioned alkylene glycol (meth ) By having a repeating unit derived from acrylic acid acetoacetic acid diester, it is possible to form a coating film having excellent adhesion to the coating layer. Furthermore, by including a copolymer obtained by combining these monomers, it is possible to obtain a coating film whose period until application of sebum softening resistance is significantly shorter than that of the solvent-based coating composition. it can. This is presumably because a pseudo-crosslinked structure is formed by hydrogen bonding.

  The content ratio of the (meth) acrylic acid acetoacetic acid diester of the alkylene glycol is 1 to 10% by weight, preferably 3 to 7% by weight, based on the total amount of the monomer mixture. When the content ratio of the (meth) acrylic acid acetoacetic acid diester of alkylene glycol is in the above range, a coating film having excellent adhesion to the article to be coated can be obtained. Furthermore, according to the aqueous coating composition of the present invention, the (meth) acrylic acid acetoacetic acid diester of alkylene glycol having such a specific content, and the above-mentioned cyano group-containing ethylenically unsaturated monomer having the specific content are included. By including a copolymer that has been copolymerized, not only does it provide sebum softening resistance equivalent to or better than that of a solvent-based coating composition while being aqueous, but the period until the said sebum softening resistance is expressed is solvent-based. A coating film much shorter than that of the coating composition can be obtained.

  The monomer mixture may comprise a cyano group-containing ethylenically unsaturated monomer and other monomers copolymerizable with (meth) acrylic acetoacetic acid diester of alkylene glycol. Specific examples of the other monomers include methacrylic acid, acrylic acid, itaconic acid, maleic acid; methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-butyl methacrylate, n-butyl acrylate, Isobutyl methacrylate, isobutyl acrylate, t-butyl methacrylate, t-butyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl ester acrylic, Plaxel FM -1 (adduct of 2-hydroxyethyl acrylate and ε-caprolactone, manufactured by Daicel Chemical Industries, Ltd.); acrylamide and its derivatives; styrene, α-methylstyrene, t-butylstyrene, parachlorostyrene, vinyl naphth Styrene monomers such as thalene; vinyl acetate and the like. These other monomers may be used alone or in combination of two or more. The number, type, combination and amount of other monomers used can be appropriately set depending on the purpose.

  In one embodiment, the copolymer is dispersed in water, and the shape thereof is preferably granular and spherical, and more preferably spherical. The dimension (for example, diameter in the case of a spherical shape) is not particularly limited as long as the effect of the present invention is exhibited. The dimension is preferably 0.05 μm to 0.5 μm, more preferably 0.08 μm to 0.3 μm, and particularly preferably 0.1 μm to 0.2 μm.

  The glass transition temperature of the copolymer is preferably -40 ° C to 50 ° C, more preferably 0 ° C to 25 ° C. The glass transition temperature can be measured with a differential scanning calorimeter (DSC) or the like.

  The copolymer can be polymerized by any appropriate polymerization method. Preferably, the copolymer can be obtained by copolymerizing the monomer mixture by an emulsion polymerization method in an aqueous medium using an emulsifier and a polymerization initiator.

  Any appropriate anionic, cationic, nonionic or amphoteric surfactant can be adopted as the emulsifier. As the emulsifier, a commercially available reactive emulsifier may be used. Specific examples of commercially available reactive emulsifiers include trade name “Antox MS-60” manufactured by Nippon Emulsifier Co., Ltd., trade name “Aqualon HS-10” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Soap SE-10N "and the like. These emulsifiers may be used alone or in combination of two or more.

  The content of the emulsifier is preferably 1 to 5% by weight with respect to the total amount of the monomer mixture.

  Any appropriate polymerization initiator can be adopted as the polymerization initiator as long as it is a water-soluble polymerization initiator. Specific examples of the polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate; 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-methylpropionamidine) dihydrochloride And azo compounds such as 2,2′-azobis (N, N′-dimethyleneisobutyroamidine). Commercial products may be used as the polymerization initiator. Specific examples of commercially available polymerization initiators include trade name “V-50” and trade name “VA-061” manufactured by Wako Pure Chemical Industries, Ltd. These polymerization initiators may be used alone or in combination of two or more.

  The content of the polymerization initiator is preferably 0.1 to 5% by weight with respect to the total amount of the monomer mixture.

B. Water-based paint composition The water-based paint composition of the present invention contains the above copolymer. The proportion of the copolymer in the aqueous coating composition of the present invention is preferably 60 to 90% by weight.

  The aqueous coating composition of the present invention may contain any appropriate other component. For example, a pigment may be included in order to enhance the base concealability and various performances of the resulting coating film. Examples of the pigment include yellow lead, yellow iron oxide, iron oxide, carbon black, titanium dioxide, dial, azo chelate pigment, insoluble azo pigment, condensed azo pigment, phthalocyanine pigment, indigo pigment, and perinone pigment. And pigments such as perylene pigments, dioxane pigments, quinacridone pigments, isoindolinone pigments and metal complex pigments, and extender pigments such as calcium carbonate, precipitated barium sulfate, clay and talc.

  When the aqueous coating composition of the present invention contains the above pigment, the total pigment concentration represented by [total pigment weight / (total pigment weight + total solid content weight)] × 100 is preferably 1 to 30% by weight. More preferably, it is 5 to 25% by weight.

  The aqueous coating composition of the present invention contains water. The water may be water contained in an emulsion obtained at the time of polymerization of the copolymer, may be water blended separately from the emulsion, or a combination thereof. Any appropriate amount of water can be adopted as long as the effects of the present invention are not impaired. The amount of water is typically 30 to 50% by weight with respect to the total amount of the aqueous coating composition.

  The water-based coating composition of the present invention includes a dispersant, a viscosity modifier, an organic solvent, a curing catalyst, a surface modifier, an antifoaming agent, a plasticizer, a film-forming aid, an ultraviolet absorber, and an antioxidant as necessary. Etc.

  Arbitrary appropriate methods can be employ | adopted for the manufacturing method of the water-based coating composition of this invention. For example, methods such as kneading a blend of the above copolymer and pigment using a kneader, a roll, etc., and dispersing using a sand grind mill, a disper or the like can be mentioned.

  The aqueous coating composition of the present invention can be used as a one-pack type aqueous coating composition. The aqueous coating composition of the present invention is a one-component aqueous coating composition that is excellent in storage stability and workability by containing the above copolymer, and obtains a coating film having the above-mentioned sebum softening resistance. Can do.

C. Sebum softening-resistant coating film forming method The sebum softening-resistant coating film forming method of the present invention comprises an application step of applying the aqueous coating composition to an object to be coated, and a drying step of drying the coating film after the application step. Including.

  Examples of the coating method in the coating step include brush coating, air spray, airless spray, electrostatic coating, and the like. The film thickness of the obtained coating film can be set to any appropriate film thickness depending on the application and the like. In general, the dry film thickness in one coating is preferably 20 to 30 μm.

  Arbitrary appropriate drying methods may be employ | adopted for the drying method in the said drying process. Typically, it is natural drying. The drying time of the coating film is preferably 24 hours or more, more preferably 5 days or more.

  The period until the coating film formed from the aqueous coating composition of the present invention exhibits sebum softening resistance is preferably 24 hours or more, more preferably 5 days or more, and particularly preferably 1 month or more at room temperature. is there. Thus, obtaining the water-based coating composition which can express sebum softening resistance in a short period (for example, 24 hours) is one of the great achievements of the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, parts and% in the examples are based on mass.

[Production Example 1]
A flask equipped with a stirrer, a condenser tube and a dropping funnel was charged with 260 parts of deionized water and 1.2 parts of Antox MS-60 (reactive emulsifier manufactured by Nippon Emulsifier Co., Ltd.), and the temperature was raised to 80 ° C. Next, an initiator consisting of 140 parts deionized water and 1.2 parts potassium persulfate, 340 parts deionized water, Antox
MS-60 3.2 parts, styrene (ST) 170 parts, methyl methacrylate (MMA) 85 parts, butyl acrylate (BA) 170 parts, methacrylic acid (MAA) 25 parts, 2-acetoacetoxyethyl metalate (AAEM) ) 25 parts, a monomer pre-emulsion prepared in advance from 25 parts of acrylonitrile (AN) was added dropwise over 2 hours. Thereafter, the contents were held at 80 ° C. for 1 hour to obtain an emulsion resin composition A. Further, 10 parts of 25% aqueous ammonia was added to adjust the pH to 7.5. The solid content was 40%, and the particle size was 0.12 μm (according to laser light scattering method; the same applies hereinafter).

[Production Examples 2 to 7]
Emulsion resin compositions B to G were obtained in the same manner as in Production Example 1 except that the compositions of the monomers (ST, MMA, BA, MAA, AAEM and AN) were adjusted as shown in Table 1.

[Example 1]
The emulsion resin composition A obtained in Production Example 1 is 22 parts as a solid content, 43 parts of water as a solvent (the total amount of water as a solvent of the emulsion resin composition A and water used in the production of the paint), pigment 22 parts of (titanium dioxide) and 13 parts of additives (dispersant, antifoaming agent, viscosity modifier, film-forming aid, etc.) were mixed to obtain an aqueous coating composition.

[Example 2]
An aqueous coating composition was obtained in the same manner as in Example 1 except that the emulsion resin composition B was used in place of the emulsion resin composition A.

[Example 3]
An aqueous coating composition was obtained in the same manner as in Example 1 except that the emulsion resin composition C was used in place of the emulsion resin composition A.

[Comparative Example 1]
An aqueous coating composition was obtained in the same manner as in Example 1 except that the emulsion resin composition D was used in place of the emulsion resin composition A.

[Comparative Example 2]
An aqueous coating composition was obtained in the same manner as in Example 1 except that the emulsion resin composition E was used instead of the emulsion resin composition A.

[Comparative Example 3]
An aqueous coating composition was obtained in the same manner as in Example 1 except that the emulsion resin composition F was used instead of the emulsion resin composition A.

[Comparative Example 4]
An aqueous coating composition was obtained in the same manner as in Example 1 except that the emulsion resin composition G was used instead of the emulsion resin composition A.

<Evaluation 1>
The coating film obtained from the aqueous coating composition obtained above was evaluated by the following method. The results are shown in Table 2.
(Sebum softening resistance)
(I) The obtained coating composition was diluted 5% with tap water, and applied onto a bonded steel plate with a brush twice at about 100 g / m ² when wet (coating drying condition: room temperature for 3 hours). A specimen was allowed to stand at room temperature for a day.
(Ii) As the sebum softening evaluation liquid, an evaluation liquid in which oleic acid and a commercially available oil (Healthy resetter manufactured by Nisshin Oillio Co., Ltd.) were mixed at a ratio of 3: 7 was used as a pseudo sebum.
(Iii) About 1 cc of the evaluation liquid was spotted on a part of the test body and left to stand at room temperature for 24 hours, and then the evaluation liquid was wiped off. Immediately after that, JIS
According to the scratch hardness (pencil method) defined in K 5600-5-4, the part which was not made into the part which spotted the evaluation liquid was evaluated.
(Adhesion)
(I) On a steel plate (a polished steel plate defined in JIS G 3141 (SPCC-SB) is used after degreasing with xylene), an aqueous hypon primer (manufactured by Nippon Paint Co., Ltd.) is used as a primer at a wet 140 g / m ² brush. After coating and drying at room temperature for 4 hours, aqueous fine urethane U100 (manufactured by Nippon Paint Co., Ltd.) was applied twice with a brush (coating drying condition: room temperature for 3 hours) and dried at room temperature for 7 days or more. .
(Ii) The coating composition obtained above was diluted 5% with tap water, and applied to a steel plate having the above-mentioned treatment with a brush twice at about 100 g / m ² in wet condition (coating drying conditions) : Room temperature 3 hours), after standing at room temperature for 7 days, JIS
It was measured by the method defined in K 5600-5-6. The adhesion was scored according to the classification of evaluation of JIS K 5600-5-6. Specifically, classification 0 in JIS K 5600-5-6 is 10 points, classification 1 is 8 points, classification 2 is 6 points, classification 3 is 4 points, classification 4 is 2 points, classification 5 Was 0.

[Example 4]
The coating composition obtained in Example 2 was diluted 5% with tap water and applied onto a bonded steel plate with a brush twice at about 100 g / m ² when wet (coating drying condition: room temperature for 3 hours) A coating film was obtained.
The sebum softening resistance of the coating film was evaluated after standing at room temperature for 1 day, standing at room temperature for 5 days, and standing at room temperature for 1 month.
The evaluation was performed in the same manner as in the evaluation of sebum softening resistance (ii) to (iii). The results are shown in Table 3.

[Comparative Example 5]
Turpentine-soluble 2-part urethane resin paint (trade name "Fine urethane U100", Nippon Paint Co., Ltd.) was diluted 5% in mineral spirits, in the wet-about 100g / m ² at twice brush on top of the bonderized steel It was coated (coating drying condition: room temperature 3 hours) to obtain a coating film.
The obtained coating film was subjected to the same evaluation as in Example 4. The results are shown in Table 3.

[Comparative Example 6]
Synthetic resin blended paint (trade name “Hi / CR Deluxe 300G”, manufactured by Nippon Paint Co., Ltd.) is diluted 5% with mineral spirit and applied onto the bonde steel plate with a brush twice at about 100 g / m ² when wet ( Coating drying condition: room temperature 16 hours), a coating film was obtained.
The obtained coating film was subjected to the same evaluation as in Example 4. The results are shown in Table 3.

[Example 5]
The coating composition obtained in Example 2 was diluted 5% with tap water and applied onto a bonded steel plate with a brush twice at about 100 g / m ² when wet (coating drying condition: room temperature for 3 hours). The test piece (3 cm × 3.5 cm) on which a coating film was formed was obtained by allowing to stand at room temperature for 5 days.

[Comparative Example 7]
The coating composition obtained in Comparative Example 1 was diluted 5% with tap water and applied onto a bonded steel plate with a brush twice at about 100 g / m ² when wet (coating drying condition: room temperature 3 hours), The test piece (3 cm × 3.5 cm) on which a coating film was formed was obtained by allowing to stand at room temperature for 5 days.

[Comparative Example 8]
The coating composition obtained in Comparative Example 2 was diluted 5% with tap water and applied onto a bonded steel plate with a brush twice at about 100 g / m ² when wet (overlap drying condition: room temperature 3 hours), The test piece (3 cm × 3.5 cm) on which a coating film was formed was obtained by allowing to stand at room temperature for 5 days.

[Comparative Example 9]
Synthetic resin blended paint (trade name “Hi / CR Deluxe 300G”, manufactured by Nippon Paint Co., Ltd.) is diluted 5% with mineral spirit and applied onto the bonde steel plate with a brush twice at about 100 g / m ² when wet. After repeated drying (room temperature: 16 hours), the sample was allowed to stand at room temperature for 5 days to obtain a test piece (3 cm × 3.5 cm) on which a coating film was formed.

[Comparative Example 10]
Turpentine-soluble 2-part urethane resin paint (trade name "Fine urethane U100", Nippon Paint Co., Ltd.) was diluted 5% in mineral spirits, in the wet-about 100g / m ² at twice brush on top of the bonderized steel After coating (coating drying condition: room temperature 3 hours), the test piece (3 cm × 3.5 cm) having a coating film formed thereon was left to stand at room temperature for 5 days.

[Comparative Example 11]
The coating composition obtained in Comparative Example 4 was diluted 5% with tap water and applied onto a bonded steel plate with a brush twice at about 100 g / m ² when wet (coating drying condition: room temperature for 3 hours), The test piece (3 cm x 3.5 cm) in which the coating film was formed was obtained by allowing to stand at room temperature for 5 days.

<Evaluation 2>
(Hand stain dirt evaluation)
The test pieces obtained in Example 5 and Comparative Examples 7 to 11 were evaluated by the following methods. The results are shown in FIG.
(I) The test piece is attached to a push-type iron door that is often touched by human hands in the state of being close to each other as shown in FIGS. 1 (a), 2 (a), and 3 (a). I attached.
(Ii) The state of the test piece was visually observed after 6 months (number of contact of human hand: about 10,000 times) (FIG. 1 (b), FIG. 2 (b) and FIG. 3 (b)).

As is clear from Table 2, the water-based coating composition of the present invention can form a coating film having excellent sebum softening resistance and excellent adhesion. Further, as is apparent from Table 3, the coating film obtained from the aqueous coating composition of the present invention can obtain sebum softening resistance in one day after coating, compared to one month of the solvent-based coating composition. Very short. Further, as apparent from FIGS. 1 to 3, the aqueous coating composition of the present invention has a function of preventing scratches and dirt, and the effect is equal to or better than that of the solvent-based coating composition.
That is, according to the present invention, it is possible to obtain a coating film that exhibits an effect equivalent to or better than that of a solvent-based coating composition (anti-sebum softening resistance and scratch resistance prevention) while being an aqueous coating composition with a low environmental load. it can. Furthermore, according to the present invention, it is possible to obtain an aqueous coating composition that has a shorter period until the above-described effects are exhibited and is excellent in workability.

  The coating composition of the present invention can be suitably used for painting buildings and building materials.

(A) is a photograph immediately after the test piece installation in Comparative Example 7 and Comparative Example 8, and (b) is a photograph of the test piece after 6 months from the installation. (A) is a photograph immediately after the test piece installation in Comparative Example 9 and Example 5, and (b) is a photograph of the test piece 6 months after the installation. (A) is a photograph immediately after installation of the test piece in Comparative Example 10 and Comparative Example 11, and (b) is a photograph of the test piece after 6 months have elapsed since the installation.

Claims (5)

A one-component aqueous coating composition in which a copolymer obtained from a monomer mixture containing a cyano group-containing ethylenically unsaturated monomer and a (meth) acrylic acid acetoacetic acid diester of alkylene glycol is dispersed in water,
The content of the cyano group-containing ethylenically unsaturated monomer is 5 to 30% by weight with respect to the total amount of the monomer mixture, and the content of the (meth) acrylic acid acetoacetic acid diester of the alkylene glycol is the total amount of the monomer mixture. 1 to 10% by weight,
Has sebum softening resistance,
Water-based paint composition.   The aqueous coating composition according to claim 1, wherein the cyano group-containing ethylenically unsaturated monomer is acrylonitrile.   The aqueous coating composition according to claim 1 or 2, wherein the (meth) acrylic acid acetoacetic acid diester of alkylene glycol is 2-acetoacetoxyethyl methacrylate.   A building paint comprising the water-based paint composition according to claim 1. Applying the aqueous coating composition according to any one of claims 1 to 3 to an object to be coated;
A method of forming a sebum softening-resistant coating film, comprising: drying the coating film after the coating step.