JP4711615B2 - Water-based coating composition and method for coating inorganic substrate - Google Patents

Description

  The present invention relates to an aqueous coating composition applicable to surface makeup such as buildings and civil engineering structures, and a method for coating an inorganic substrate using the aqueous coating composition.

In buildings and civil engineering structures, inorganic base materials such as concrete, mortar, siding board, ALC board and the like are used for general purposes. Among these, concrete, mortar, etc. are usually obtained by hardening what knead | mixed cement, water, etc. in construction sites, such as a building. Inorganic building materials such as siding boards and ALC plates are mainly produced by molding cement-based materials into a plate shape by a papermaking method, an extrusion molding method, a casting method or the like.
However, in such an inorganic base material, the hydration reaction with cement and water may not be completed at the time of molding, and active components may remain. If moisture enters the inorganic base material from the outside due to rainfall or the like, the reaction between the active ingredient remaining in the base material and water proceeds, and there is a risk that the base material will crack. In a plate-like base material, there is a possibility that warpage, dimensional change and the like may occur.
Furthermore, in cold districts, if water enters the inorganic base material from the outside and is repeatedly frozen and thawed, the inside of the base material may be destroyed. Moreover, when the rainwater is acidified, it may cause the neutralization of cement and reduce the strength of the base material.

  By providing a coating film on the surface of the inorganic base material, it is possible to suppress the intrusion of moisture to some extent. For example, Japanese Patent Laid-Open No. 10-101458 (Patent Document 1) describes that an elastic coating material having waterproof properties is applied to the surface of an inorganic building material such as an ALC plate.

  As a technique for preventing moisture from entering the inorganic base material from the outside, a method of applying a water-repellent paint on the surface of the inorganic base material is also known. The water-repellent paint has a function of preventing water from entering from the outside because the formed coating film exhibits water repellency. For example, JP-A-8-92499 (Patent Document 2) describes a water-repellent paint comprising a specific water-repellent component and an organic solvent-based resin. Japanese Patent Application Laid-Open No. 2003-34586 (Patent Document 3) describes that a styrene acrylic resin emulsion paint containing a water repellent is applied to an inorganic substrate.

JP-A-10-101458 JP-A-8-92499 JP 2003-34586 A

  However, in the case of an inorganic base material that has been surface-coated by a method such as Patent Document 1, if moisture enters the base material from the back surface or side surface of the base material, the water is efficiently released to the outside. The film cannot be swollen and the coating film may swell or peel off.

The water-repellent paints described in Patent Document 2 and Patent Document 3 cannot necessarily be said to have sufficient weather resistance and durability, and water-repellent performance when exposed to sunlight or rain for a long time. In some cases, the substrate protection effect cannot be obtained.
In addition, conventional water-repellent paints are also prone to rain dripping, mold, algae and the like, and the aesthetics are greatly impaired. Of these, rain streak is particularly noticeable in urban areas and suburban areas where oily pollutants float in the atmosphere due to exhaust gases from automobiles and the like.
On the other hand, in paints used for buildings and civil engineering structures, conversion from solvent-based paints using an organic solvent as a solvent to water-based paints using water as a solvent is being attempted. This is carried out for the purpose of reducing the health hazards of the painters and residents and for the purpose of reducing air pollution. Even in the above-described water-repellent paint, there is a high demand for water-repellency.

  This invention is made | formed in view of such a point, The 1st subject in this invention can suppress the swelling of a coating film resulting from a water | moisture content, a peeling, a crack, etc. effectively, and the effect is made. It is to provide a water-repellent paint that can be sustained for a long time. Furthermore, it is a second object of the present invention to provide a water-repellent paint that has excellent stain resistance in addition to the above-described performance.

In order to solve these problems, the present inventor has intensively studied and used a synthetic resin emulsion having a reactive functional group as a binder, and also used a water-dispersed water repellent that is reactive with the binder. Furthermore, the inventors have conceived an aqueous coating composition in which the pigment mixing ratio is a specific pigment volume concentration, and have completed the present invention.
That is, the present invention has the following characteristics.

1. (A) a multilayer emulsion comprising at least two layers of a core part and a shell part, having an epoxy group in the core part, a carboxyl group in the shell part, and a glass transition temperature of -30 to 60 ° C;
(B) a water-dispersed water repellent having an amino group, and (c) a pigment,
(A) The component (b) contains 1 to 100 parts by weight of the solid content with respect to 100 parts by weight of the component,
A water-based paint composition having a pigment volume concentration of 40 to 75%.
2. The component (c-1) contains a photocatalyst (c-1), and the content of the component (c-1) is 0.1 to 50 parts by weight with respect to 100 parts by weight of the solid content of the component (a). 1. The aqueous coating composition according to.
3. Against inorganic substrate, 1. Or 2. A method for coating an inorganic substrate, comprising applying the water-based coating composition described in 1.

  By coating the inorganic base material with the water-based coating composition of the present invention, it is possible to effectively suppress swelling, peeling, cracking, etc. of the coating film due to moisture, and to maintain the effect over a long period of time. it can. Furthermore, in the present invention, the contamination resistance can be enhanced.

  Hereinafter, the present invention will be described in detail together with embodiments thereof.

The aqueous coating composition of the present invention comprises
(A) a synthetic resin emulsion having a reactive functional group and a glass transition temperature of −30 to 60 ° C. (hereinafter referred to as “component (a)”),
(B) Contains a water-dispersed water repellent (hereinafter referred to as “(b) component”) having a functional group capable of reacting with the component (a), and (c) a pigment (hereinafter referred to as “(c) component”). To do.

  Among these, (a) component functions as a binder of this invention composition, and has at least 1 sort (s) of reactive functional group. In the present invention, this (a) component and the later-described (b) component have reactivity with each other, so that excellent water repellency persistence can be exhibited. Examples of combinations of reactive functional groups in component (a) and component (b) include carboxyl group and carbodiimide group, carboxyl group and epoxy group, carboxyl group and aziridine group, carboxyl group and oxazoline group, hydroxyl group and isocyanate group, Examples thereof include a carbonyl group and a hydrazide group, an epoxy group and an amino group, and an alkoxysilyl group. These can be used alone or in combination of two or more.

As the component (a) in the present invention, various synthetic resin emulsions can be used as long as it has a reactive functional group as described above. Specifically, for example, a vinyl acetate resin emulsion, a vinyl chloride resin emulsion, an epoxy resin emulsion, an acrylic resin emulsion, a urethane resin emulsion, an acrylic silicon resin emulsion, a fluororesin emulsion, etc., or a composite system thereof can be used. Among these, acrylic silicon resin emulsions and fluorine resin emulsions can be preferably used because of excellent weather resistance.
A synthetic resin emulsion obtained by copolymerizing a polymerizable ultraviolet absorber and / or a polymerizable light stabilizer is also preferable in that it has excellent weather resistance. Examples of the polymerizable ultraviolet absorber include 2-hydroxy-4-acryloxybenzophenone and 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole. Examples thereof include 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6,6-pentamethylpiperidine and the like.

  As the component (a) in the present invention, a multilayer emulsion containing at least two layers of a core part and a shell part and having a reactive functional group in one or both of the core part and the shell part is preferable. By using such a multilayer structure emulsion, the effect of preventing the occurrence of swelling, peeling, cracking and the like in the formed coating film is enhanced. Moreover, the stain resistance of the coating film can be increased. In addition, the core part said here means the inner layer part of a multilayer structure emulsion, and is layers other than an outermost layer part. A shell part means the outermost layer part of a multilayer structure emulsion. The component (a) may have a multilayer structure composed of a plurality of core parts and shell parts.

  The reactive functional group in the multilayer emulsion is preferably at least one selected from an amino group, a carboxyl group, and an epoxy group. In particular, an embodiment in which reactive functional groups are included in both the core part and the shell part, and these reactive functional groups can react with each other is desirable. When the multi-layered emulsion is in such an embodiment, the coating film properties such as stain resistance, weather resistance and water resistance can be improved. Examples of the combination of reactive functional groups in this case include a carboxyl group and an epoxy group, and an amino group and an epoxy group. In the present invention, a multilayer structure emulsion having an epoxy group in the core part and a carboxyl group in the shell part is particularly suitable.

  In order to generate an amino group in the component (a), an amino group-containing monomer may be used as the monomer constituting the component (a). Examples of amino group-containing monomers include N-methylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminoethyl vinyl ether, N- (2-dimethylaminoethyl) acrylamide, and N- (2-dimethylamino). Ethyl) methacrylamide and the like.

  In order to generate a carboxyl group in the component (a), a carboxyl group-containing monomer may be used as the monomer constituting the component (a). Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid or a monoalkyl ester thereof, itaconic acid or a monoalkyl ester thereof, fumaric acid or a monoalkyl ester thereof, or ammonium salts or organic amine salts thereof. And alkali metal salts. Among these, at least one selected from acrylic acid and methacrylic acid is particularly preferable.

  In order to generate an epoxy group in the component (a), an epoxy group-containing monomer may be used as the monomer constituting the component (a). Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, diglycidyl (meth) acrylate, and allyl glycidyl ether. Of these, glycidyl (meth) acrylate is particularly preferred.

  Although the manufacturing method of (a) component is not specifically limited, For example, emulsion polymerization, soap-free emulsion polymerization, dispersion polymerization, feed emulsion polymerization, feed dispersion polymerization, seed emulsion polymerization, seed dispersion polymerization, etc. are employable. The amount of the reactive functional group used in (a) is usually 0.1 to 40% by weight, preferably 0.5 to 20% by weight, based on the total amount of monomers constituting component (a). Moreover, when the component (a) is a multilayer structure emulsion, the weight ratio of the monomers used for the core part and the shell part is usually about 10/90 to 90/10.

The glass transition temperature (hereinafter referred to as “Tg”) of the component (a) is set to −30 to 60 ° C., preferably −10 to 40 ° C. When Tg is lower than −30 ° C., contaminants tend to adhere. When Tg is higher than 60 ° C., cracks are likely to occur in the coating film and the water shielding effect may be reduced. The Tg in the present invention is a value obtained from the formula of Fox from the type of monomer constituting the component (a) and its constituent ratio.
In particular, the component (a) in the present invention is preferably a multilayer emulsion having a glass transition temperature of the shell portion higher than that of the core portion. By using such a component (a), the followability to the displacement of the base is enhanced, and a more reliable water shielding effect can be obtained. Furthermore, since the water vapor permeation performance of the coating film is improved, the effect of dissipating moisture remaining inside the base material is increased, and the occurrence of swelling and peeling of the coating film can be sufficiently prevented. Moreover, the stain resistance of the coating film can be increased.
(A) The average particle diameter of a component is about 0.05-0.2 micrometer normally.

Component (b) in the composition of the present invention is a water-dispersed water repellent having a functional group capable of reacting with component (a) described above. In the present invention, water repellency can be imparted to the formed coating film by including the component (b). Furthermore, since the component (a) and the component (b) are reactive with each other, it is possible to maintain water repellency over a long period of time.
Although the functional group of (b) component will not be specifically limited if it can react with the functional group of (a) component, (a) component has 1 or more types chosen from an amino group, a carboxyl group, and an epoxy group. In this case, the component (b) preferably has at least one functional group selected from an amino group, a carboxyl group, and an epoxy group. In particular, when component (a) has an epoxy group, component (b) has an amino group and / or carboxyl group, and when component (a) has a carboxyl group, component (b) has an epoxy group When the component (a) has an amino group, it is desirable to use a component having an epoxy group as the component (b). Among these, a combination of the component (a) having an epoxy group and the component (b) having an amino group is particularly desirable.
Such a component (b) usually has units represented by the following formulas (1) and (2).

（式中、Ｒ^１は同一または異なって、アルキル基、アリール基、アラルキル基を示し、Ｒ^２はアルキレン基、オキシアルキレン基を示す。Ｘはアミノ基、カルボキシル基、エポキシ基を示す。ｍ，ｎは１以上の整数である。）

(Wherein R ¹ is the same or different and represents an alkyl group, an aryl group or an aralkyl group, R ² represents an alkylene group or an oxyalkylene group, X represents an amino group, a carboxyl group or an epoxy group. M, n is an integer of 1 or more.)

Of these, an amino group is preferred as the functional group of the component (b). As an amino group, for example, —NH ₂ , —NHCH ₃ , —N (CH ₃ ) ₂ , —NH (CH ₂ ) ₂ NH ₂ , —NH (CH ₂ ) ₂ NHCH ₃ , —NH (CH ₂ ) ₂ N _{(CH 3) 2} or the like can be mentioned.

  The form of (b) component will not be restrict | limited especially if it is the form disperse | distributed in water, Any of the forced emulsification type emulsion using surfactant or a self-emulsification type emulsion may be sufficient.

  The mixing ratio of the component (b) is usually 1 to 100 parts by weight, preferably 2 to 50 parts by weight, more preferably 3 to 30 parts by weight in terms of solid content with respect to 100 parts by weight of the solid content of the component (a). is there. When the amount of the component (b) is less than 1 part by weight, sufficient water repellency cannot be obtained. When there is more (b) component than 100 weight part, there exists a possibility that the stain resistance of a coating film may fall.

Examples of the component (c) in the composition of the present invention include heavy calcium carbonate, precipitated calcium carbonate, kaolin, talc, clay, porcelain clay, china clay, silica, barium sulfate, barium carbonate, quartz sand, quartzite, diatomaceous earth, and oxidation. Examples thereof include titanium, zinc oxide, aluminum oxide, iron oxide, and resin beads, and one or more of these can be used.
(C) The average particle diameter of a component is about 0.01-200 micrometers normally, Preferably it is about 0.1-100 micrometers. When the average particle size is smaller than 0.01 μm, it is difficult to set the pigment volume concentration high, and as a result, water cannot be efficiently diffused to the outside. Moreover, there exists a possibility that stain resistance may become inadequate. When the average particle size is larger than 200 μm, it becomes difficult to form a smooth coating film.

The component (c) is blended so that the pigment volume concentration in the formed coating film is 10 to 90%, preferably 30 to 90%, more preferably 40 to 80%, and most preferably 45 to 75%. . With such a pigment volume concentration, the water vapor transmission performance and strength of the formed coating film are enhanced, and the occurrence of swelling and peeling of the coating film can be sufficiently suppressed. Moreover, the coating film excellent in stain resistance can also be formed. When the pigment volume concentration is less than 10%, the coating film is liable to swell and peel off. Further, the contamination resistance tends to decrease. When the pigment volume concentration is larger than 90%, the coating film is likely to be cracked and the water shielding effect may be reduced.
In addition, the pigment volume concentration in this invention is a volume percentage of (c) component contained in a dry coating film, and is a value computed by a following formula. Since the component (b) has substantially no film forming performance, it is excluded when calculating the pigment volume concentration.

<Formula> Pigment volume concentration (%) = [(c _w / c _ρ ) / {(a _w / a _ρ ) + (c _w / c _ρ )}] × 100
(Wherein, _{a w} is (a) mixing of the component solids, a _[rho component (a) solids content of the specific gravity, the mixing amount of _{c w} component (c), the c _[rho specific gravity of component (c) Show.)

In this invention, a photocatalyst (henceforth "(c-1) component") can be included as (c) component. In the present invention, by mixing such a component (c-1), when various contaminants (particularly organic contaminants) adhere to the surface of the formed coating film, it becomes possible to decompose them. Contamination resistance can be further increased. Furthermore, in this invention, since (b) component is contained as an essential component, deterioration of (a) component by (c-1) component can also be suppressed.
When the component (c-1) is mixed, any one of the acrylic resin resin emulsion, the fluororesin emulsion, the polymerizable ultraviolet absorber and / or the synthetic light stabilizer copolymerized with the polymerizable light stabilizer is used as the component (a). If used, it is more suitable in terms of suppressing deterioration of component (a).

Examples of the component (c-1) include TiO ₂ , ZnO, Bi ₂ O ₃ , BiVO ₄ , SrTiO ₃ , CdS, InP, InPb, GaP, GaAs, BaTiO ₃ , BaTiO ₄ , BaTi ₄ O ₉ , K ₂ NbO. ₃ , Nb ₂ O ₅ , Fe ₂ O ₃ , Ta ₂ O ₅ , Ta ₃ N ₅ , K ₃ Ta ₃ Si ₂ O ₃ , WO ₃ , SnO ₂ , NiO, Cu ₂ O, SiC, MoS ₂ , RuO ₂ In addition to CeO ₂ and the like, composites of these with metals, metal oxides, porous bodies, layered compounds and the like can be mentioned.
The mixing amount of the component (c-1) is usually 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the solid content of the component (a). When the component (c-1) is less than 0.1 part by weight, the effect of improving the stain resistance cannot be expected. When the amount of the component (c-1) is more than 50 parts by weight, it is difficult to suppress the deterioration of the component (a).

  In the composition of the present invention, in addition to the above-described components, components that can be used in ordinary paints can also be included. Examples of such components include coloring pigments, dyes, aggregates, fibers, thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreezing agents, pH adjusting agents, preservatives, and antifungal agents. An agent, an anti-algae agent, an antibacterial agent, a dispersant, an antifoaming agent, an ultraviolet absorber, an antioxidant, a catalyst, a crosslinking agent, etc. can be used.

The composition of the present invention can be applied to the surface of a building inner / outer wall or a civil engineering structure. The base material to be coated is not particularly limited, but is usually an inorganic base material. Particularly, in the present invention, a cement-based inorganic base material is suitable. When the composition of the present invention is coated on a cement-based inorganic base material, the effects of the present invention can be sufficiently exerted. Such a cement-based inorganic base material is a material obtained by using cement as an essential component. As components other than cement, for example, aggregates such as silica sand, silica stone, and fly ash, fibers such as pulp and glass wool, and the like may be included.
Specifically, examples of the cement-based inorganic base material include concrete, mortar, fiber-mixed cement board, cement calcium silicate board, slag cement pearlite board, asbestos cement board, ALC board, and siding board. Among these, base materials such as concrete and mortar are usually obtained by curing a material kneaded with water or the like at a construction site. Inorganic building materials such as ALC plates and siding plates are formed into plates by various methods such as papermaking, extrusion, and casting. When the composition of the present invention is applied to a cement-based inorganic building material, it is particularly preferable in that cracks, warpage, dimensional changes, and the like of the substrate can be sufficiently suppressed.
The surface of these base materials may have been subjected to some surface treatment (for example, a sealer, a surfacer, a filler, etc.), or may already have a coating film formed thereon.

When the composition of the present invention is painted at a construction site or the like, it can be applied regardless of whether it is a new construction or a renovation. The plate-like inorganic building material can be coated before being brought into a construction site or the like (that is, during or after the molding of the inorganic building material). It can also be applied to partial repairs.
When painting the composition of the present invention, various painting tools such as sprays, rollers, scissors and brushes can be used.
In the case of painting, it is also possible to dilute with water. The mixing amount of water may be appropriately set in consideration of the type of coating equipment, the state of the coating base, the temperature at the time of coating, and the like, but is usually about 0 to 10 parts by weight with respect to 100 parts by weight of the paint.
The application amount of the composition of the present invention is usually about 0.2 to ² kg / m ² . In addition, drying after coating the composition of the present invention is usually performed at room temperature, but can be performed. The drying time is usually about 0.5 to 4 hours at room temperature.

  Examples and Comparative Examples are shown below to clarify the features of the present invention.

(Manufacture of paint compositions)
Water 50 parts by weight, dispersant 6 parts by weight, inorganic pigment A 100 parts by weight, inorganic pigment B 45 parts by weight, resin A 200 parts by weight, film-forming aid 18 parts by weight, water repellent A 50 parts by weight, thickener 33 parts by weight, The coating composition of Test Example 1 was produced by mixing and stirring 1 part by weight of an antifoaming agent by a conventional method.
Subsequently, each coating composition was manufactured according to the composition shown in Tables 1 and 2. In addition, the following were used as a raw material.

Resin A: Core-shell type acrylic resin emulsion (core part; methyl methacrylate-cyclohexyl methacrylate-2-ethylhexyl acrylate-glycidyl methacrylate copolymer, shell part; methyl methacrylate-cyclohexyl methacrylate-2-ethylhexyl acrylate-methacrylic acid copolymer, (Solid content 50% by weight, total Tg 5 ° C, core Tg-20 ° C, shell Tg 25 ° C)
Resin B: Core-shell type acrylic resin emulsion (core part; methyl methacrylate-cyclohexyl methacrylate-2-ethylhexyl acrylate-glycidyl methacrylate copolymer, shell part; methyl methacrylate-cyclohexyl methacrylate-2-ethylhexyl acrylate-methacrylic acid-4-methacryloyl Oxy-2,2,6,6-tetramethylpiperidine copolymer, solid content 50 wt%, total Tg 5 ° C., core Tg-20 ° C., shell Tg 25 ° C.)
Resin C: acrylic resin emulsion (methyl methacrylate-styrene-2-ethylhexyl acrylate-methacrylic acid copolymer, solid content 50% by weight, Tg 5 ° C.)
Water repellent A: water-dispersed water repellent (emulsified dispersion of amino group-containing dimethylsiloxane compound, solid content 50% by weight)
Water repellent B: Water-dispersed water repellent (epoxy group-containing dimethylsiloxane compound emulsified dispersion, solid content 50% by weight)
Water repellent C: Water-dispersed water repellent (emulsified dispersion of dimethylsiloxane compound, solid content 50% by weight)
Inorganic pigment A: rutile type titanium oxide (average particle diameter 0.2 μm)
Inorganic pigment B: Clay (average particle size 8 μm)
Photocatalyst: anatase type titanium oxide (average particle size 0.02 μm)
・ Film-forming auxiliary: 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate ・ Dispersant: polycarboxylic acid-based dispersant (solid content 30% by weight)
・ Thickener: Hydroxyethylcellulose 3% by weight aqueous solution ・ Defoamer: Mineral oil-based defoamer

(Test method)
(1) Water repellent durability SK # 1000 primer (epoxy resin primer; manufactured by SK Kaken Co., Ltd.) is sprayed on two 150 × 70 × 0.8 mm aluminum plates so that the dry film thickness is about 30 μm. The specimen substrate was coated and dried for 8 hours at a temperature of 23 ° C. and a relative humidity of 50% (hereinafter, standard state).
Next, the coating composition produced on the test specimen substrate was spray-coated so that the dry film thickness was about 15 μm, and dried in a standard state for 7 days to obtain a test specimen. 0.2 cc of deionized water is dropped on the coating film surface of the prepared specimen, and the contact angle immediately after dropping is measured with a CA-A type contact angle measuring device manufactured by Kyowa Interface Science Co., Ltd. It was a corner. Next, the test specimen was immersed in water at 23 ± 2 ° C. for 3 hours, dried for 1 hour in a standard state, and then contact angle was measured in the same manner.
The water repellency persistence was evaluated by confirming how much the contact angle after water immersion decreased with respect to the initial contact angle.
・ Evaluation method ◎: Difference between initial contact angle and contact angle after water immersion is less than 5 degrees ○: Difference between initial contact angle and contact angle after water immersion is 5 degrees or more and less than 10 degrees △: Initial contact angle The difference between the contact angle after water immersion is 10 degrees or more and less than 15 degrees X: The difference between the initial contact angle and the contact angle after water immersion is 15 degrees or more

(2) Wet cold / heat repeatability SK clear sealer (acrylic resin emulsion base coat; manufactured by SK Kaken Co., Ltd.) is spray-coated on a 150 × 70 × 3 mm siding plate to a dry film thickness of 30 μm. After drying in the state for 8 hours, the prepared coating composition was spray-coated so that the dry film thickness was 40 μm to prepare a test specimen. After curing for 14 days in the standard state, the prepared specimen was immersed in 23 ± 2 ° C. water for 18 hours in accordance with JIS K 5660 6.14, and then immediately kept in a thermostatic bath maintained at −20 ± 3 ° C. for 3 hours. It was cooled and then warmed for 3 hours in another thermostat kept at 50 ± 3 ° C. This operation was repeated 8 times, and then placed in a standard state for about 1 hour, and the state of the coating film surface was visually observed.
Evaluation method A: No cracking or peeling occurred.
○: Almost no cracking or peeling occurred.
Δ: Partial cracking and peeling occurred.
X: Cracking and peeling occurred remarkably.

(3) Contamination resistance A 300 × 150 × 3 mm aluminum plate bent at a third of the length from the top so that the inner angle is 135 degrees (hereinafter referred to as “exposure plate”). SK # 1000 primer (epoxy resin-based primer; manufactured by SK Kaken Co., Ltd.) was spray-coated so that the dry film thickness was about 30 μm, and was dried in a standard state for 8 hours. (Exposed plate has convex surface)
Next, the prepared coating composition was spray-coated on an exposure plate coated with the above-described primer so that the dry film thickness was 40 μm, and dried in a standard state for 7 days to obtain a test specimen. About the produced test body, outdoor exposure was implemented in Ibaraki City, Osaka Prefecture, and the presence or absence of the rain-stain stain | pollution | contamination in the vertical surface 6 months later was evaluated visually. The exposure plate was installed so that the surface with the large area was in the vertical direction and the surface with the small area was at the top.
・ Evaluation method ◎: No rain streak contamination occurred.
○: Rain line contamination hardly occurred.
Δ: Rain line contamination slightly occurred.
X: Significant rain streak contamination occurred.

(Test results)
Test results are shown in Tables 1-2. In Test Examples 1 to 9, good results were obtained in water repellency durability and wet / cold heat resistance. Furthermore, in Test Examples 1 to 7, good results were obtained in terms of contamination resistance.

Claims (3)

(A) a multilayer emulsion comprising at least two layers of a core part and a shell part, having an epoxy group in the core part, a carboxyl group in the shell part, and a glass transition temperature of -30 to 60 ° C;
(B) a water-dispersed water repellent having an amino group, and (c) a pigment,
(A) The component (b) contains 1 to 100 parts by weight of the solid content with respect to 100 parts by weight of the component,
A water-based paint composition having a pigment volume concentration of 40 to 75%. The component (c-1) contains a photocatalyst (c-1), and the content of the component (c-1) is 0.1 to 50 parts by weight with respect to 100 parts by weight of the solid content of the component (a). The water-based coating composition according to claim 1 . A method for coating an inorganic base material, comprising applying the aqueous coating composition according to claim 1 or 2 to the inorganic base material.