JP2023180244A - Water-based sealer composition and inorganic base material with sealer coating film - Google Patents

Abstract

To provide a water-based sealer composition capable of forming a sealer coating film having excellent resistance to freezing and thawing and excellent adhesion.SOLUTION: A water-based sealer composition of the invention includes (A) an emulsifiable hydrophilic group-containing isocyanate prepolymer, (B) an emulsion resin liquid, and (C) a pigment. A mass ratio (a/b) of a coating film forming component mass (a) of the emulsifiable hydrophilic group-containing isocyanate prepolymer and a coating film forming component mass (b) of the emulsion resin liquid is 6-200.SELECTED DRAWING: None

Description

The present invention relates to water-based sealer compositions, particularly water-based sealer compositions for inorganic substrates. The present invention also relates to an inorganic substrate with a sealer coating, which is provided with a sealer coating formed from the aqueous sealer composition on at least one side of the inorganic substrate.

Conventionally, inorganic base materials such as asbestos cement boards and calcium silicate boards are nonflammable and have excellent durability, so they have been used as inorganic building materials by coating them. Inorganic building materials have been used, for example, as outer walls of houses and the like. However, since the inorganic base material is alkaline in nature, there is a risk that alkaline components will ooze out (efflorescence) on the surface of the base material, and it is necessary to prevent this. Furthermore, it was also necessary to prevent the surface of the base material from becoming powder, and to solidify and strengthen brittle parts. Therefore, when painting the surface of an inorganic base material, the painting operation has generally been performed by first applying a sealer coating to the surface, and then applying a top coat for aesthetic purposes. For example, a primer for inorganic wall materials containing an aqueous dispersion of a water-dispersible isocyanate oligomer has been proposed (see Patent Document 1). Furthermore, a two-component water-based top coating composition has been proposed, which is a mixture of a water-dispersible resin and a crosslinking agent containing a compound containing an isocyanate group (see Patent Document 2).

In recent years, the warranty period for exterior walls of houses, etc. has been extended, and it has become necessary to maintain performance over a long period of time. Exterior wall base materials are affected by rain and snow on the outside, and may contain a large amount of moisture on the inside due to condensation from the house. At that time, if the outside temperature drops below freezing and freezes, volumetric expansion of moisture occurs inside the base material, leading to damage to the base material. Furthermore, as a result of long-term use, the adhesion between the substrate and the cured coating film on the surface deteriorates, resulting in the problem that the cured coating film peels off.

Japanese Patent Application Publication No. 7-011167 Japanese Patent Application Publication No. 2001-262013

Conventional sealer coatings made of the paints described in Patent Document 1 and Patent Document 2 have poor freeze-thaw resistance and cannot withstand long-term outdoor use.

The present invention has been made in view of the above-mentioned background art, and its purpose is to provide a water-based sealer composition capable of forming a sealer coating film having excellent freeze-thaw resistance and excellent adhesion between a substrate and a cured coating film. Our goal is to provide the following.

In order to solve the above-mentioned problems, the present inventors conducted intensive studies and found that an aqueous sealer composition containing an emulsifying hydrophilic group-containing isocyanate prepolymer, an emulsion resin liquid, and a pigment, It has been found that the above problem can be solved by adjusting the mass ratio (a/b) of the coating film forming component mass (a) of the isocyanate prepolymer contained and the coating film forming component mass (b) of the emulsion resin liquid. did. The present invention was completed based on this knowledge.

That is, according to the present invention, the following inventions are provided.
[1] (A) Emulsifying hydrophilic group-containing isocyanate prepolymer,
(B) emulsion resin liquid;
(C) A water-based sealer composition comprising a pigment,
The mass ratio (a/b) of the coating film forming component mass (a) of the emulsifying hydrophilic group-containing isocyanate prepolymer (A) to the coating film forming component mass (b) of the emulsion resin liquid (B) is 6. A water-based sealer composition having a molecular weight of at least 200.
[2] The aqueous sealer composition according to [1], wherein the pigment contains at least one of an extender pigment and a colored pigment.
[3] The water-based sealer composition according to [2], wherein the extender pigment contains at least one selected from the group consisting of calcium carbonate, clay, silica, talc, and mica.
[4] The water-based sealer composition according to [2] or [3], wherein the colored pigment contains at least one of a white pigment and a black pigment.
[5] Mass ratio of the mass (c) of the pigment (C) to the mass (d) of the total coating film-forming components of the (A) emulsifying hydrophilic group-containing isocyanate prepolymer and the emulsion resin liquid (B) The water-based sealer composition according to any one of [1] to [4], wherein c/d) is 0.01 or more and 0.60 or less.
[6] The water-based sealer composition according to any one of [1] to [5], which is used for coating inorganic building materials.
[7] A sealer coating film formed from the water-based sealer composition according to any one of [1] to [6].
[8] An inorganic substrate with a sealer coating, comprising a sealer coating formed from the aqueous sealer composition according to any one of [1] to [7] on at least one side of the inorganic substrate.
[9] An inorganic base material with a cured coating film, further comprising a cured coating film on the sealer coating surface of the inorganic base material with a sealer coating film according to [8].
[10] Coating the water-based sealer composition according to any one of [1] to [6] on at least a portion of the inorganic substrate;
A method for producing an inorganic substrate with a sealer coating film, comprising a step of drying and curing the coating film formed in the painting step to form a sealer coating film.

According to the present invention, there is provided a water-based sealer composition capable of forming a sealer coating film having excellent freeze-thaw resistance and excellent adhesion (sometimes simply referred to as "adhesion") between a substrate and a cured coating film. be able to. Further, according to the present invention, it is possible to provide a sealer coating film having excellent freeze-thaw resistance and adhesion, and an inorganic substrate provided with the sealer coating film.

The present invention will be explained in more detail below.
In addition, in this specification, "(meth)acrylate" represents acrylate and methacrylate.
"Coating film-forming component" refers to a water-based sealer composition from which volatile components such as water have been removed, and which constitutes a sealer coating film when cured.

<Water-based sealer composition>
The water-based sealer composition according to the present invention contains at least (A) an emulsifying hydrophilic group-containing isocyanate prepolymer, (B) an emulsion resin liquid, and (C) a pigment. Water-based sealer compositions according to the invention may further contain water and other ingredients. The sealer coating formed from the water-based sealer composition according to the present invention has excellent freeze-thaw resistance and adhesion. A water-based sealer composition capable of forming such a sealer coating film can be suitably used for coating inorganic substrates that require these performances.

The water content of the water-based sealer composition according to the present invention is not particularly limited, and can be adjusted as appropriate to provide a viscosity suitable for coating. The water content of the water-based sealer composition is preferably 5% by mass or more and 80% by mass or less, more preferably 7% by mass or more and 70% by mass or less, and even more preferably 9% by mass or more and 60% by mass or less. . If the water content of the water-based sealer composition is within the above numerical range, it is possible to improve the coating workability and the permeability into the inorganic base material.

Hereinafter, each component of the water-based sealer composition according to the present invention will be explained in detail.

((A) Emulsifying hydrophilic group-containing isocyanate prepolymer)
The emulsifying hydrophilic group-containing isocyanate prepolymer (A) is used as the emulsifying hydrophilic group-containing isocyanate prepolymer itself, in which an isocyanate compound and a nonionic surfactant are bonded, or by dissolving this in an isocyanate compound. In 100% by weight of such a prepolymer, it is desirable that isocyanate groups remain in an amount of preferably 5 to 30% by weight, more preferably 10 to 25% by weight. It is preferable that the remaining isocyanate group is within the above range because the adhesiveness between the sealer coating film and the inorganic substrate is excellent and the strength of the sealer coating film is further improved.

The isocyanate compounds include methylene bis(4-cyclohexyl isocyanate) (HMDI), hexamethylene diisocyanate (HDI), 4,4'-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), and Examples include isophorone diisocyanate (IPDI). Among these, HMDI, HDI, MDI, and TDI are preferred, and non-yellowing HMDI and HDI that are mildly reactive with water are more preferred. A sealer coating obtained from such a water-based sealer composition is preferable because it firmly adheres to the inorganic substrate and has higher strength. These isocyanate compounds may be used alone or in combination of two or more.

As the nonionic surfactant, a nonionic surfactant obtained by adding ethylene oxide to a higher alcohol is used. The nonionic surfactant has the following general formula:
RO _{( CH2CH2O} ) _nH
(In the above general formula, R is an alkyl group having 1 to 18 carbon atoms, and n = an integer of 2 to 18.)
Polyethylene glycol ethers shown in the following are used. Since such polyethylene glycol ether has self-emulsifying properties, the polymerization reaction product of the polyethylene glycol ether and the isocyanate compound can be diluted into an emulsion with water.

(A) A commercially available product can also be used as the emulsifying hydrophilic group-containing isocyanate prepolymer. Examples of commercially available products include WIC105 (manufactured by Ohtake Meishin Kagaku Co., Ltd.) and Hibisol L-impregnated sealer (manufactured by Chugoku Toyo Co., Ltd.).

(A) The content of the emulsifying hydrophilic group-containing isocyanate prepolymer is preferably 10% by weight or more and 95% by weight or less, more preferably 20% by weight or more and 92% by weight based on the total solid content of the aqueous sealer composition. % or less. (A) When the content of the emulsifying hydrophilic group-containing isocyanate prepolymer is within the above numerical range, it is easy to form a sealer coating film with excellent freeze-thaw resistance and adhesion.

((B) Emulsion resin liquid)
Examples of the emulsion resin liquid (B) include acrylic resin emulsions and the like. The acrylic resin contained in the acrylic resin emulsion is preferably a homopolymer of (meth)acrylate or a copolymer of (meth)acrylate and a monomer copolymerizable to (meth)acrylate.

When the acrylic resin is a copolymer of (meth)acrylate and a monomer copolymerizable to (meth)acrylate, the component unit derived from (meth)acrylate is preferably 20 to 99.9% by weight. , more preferably 40 to 99.5% by weight, preferably 0.1 to 80% by weight, more preferably 0.5 to 60% by weight of the component unit derived from a monomer copolymerizable with the component unit. consists of the amount of However, the total component unit amount in the acrylic resin is 100% by weight.

The weight average molecular weight (Mw) of the acrylic resin is preferably 5,000 to 300,000, more preferably 50,000 to 200,000. When the acrylic resin has the above composition or molecular weight, it is easy to form a sealer coating film having excellent freeze-thaw resistance and adhesion.

The glass transition point Tg of the acrylic resin is preferably 20 to 70°C, more preferably 30 to 50°C.

The acrylic resin is preferably an acrylic resin that does not have a functional group having active hydrogen, such as a hydroxyl group, a carboxyl group, an amino group, an amide group, or a mercapto group, in its side chain. Since the acrylic resin does not have such a functional group in its side chain, the acrylic resin and the emulsifying hydrophilic group-containing isocyanate prepolymer do not react with each other. can be used.

The acrylic resin is produced by appropriately selecting monomers so as to have the above-mentioned component composition, the above-mentioned weight average molecular weight, glass transition point, etc., and by a known method such as a solution radical polymerization method.

As the monomer that can be polymerized or copolymerized, (meth)acrylate and a monomer that can be copolymerized with (meth)acrylate are used.

(Meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, (n-, (meth)acrylate), i-, t-)butyl, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, ( C1-18 alkyl ester or cycloalkyl ester of (meth)acrylic acid such as stearyl meth)acrylate and cyclohexyl (meth)acrylate; methoxybutyl (meth)acrylate, methoxyethyl (meth)acrylate, methacryl Alkoxy esters of (meth)acrylic acid having 2 to 18 carbon atoms such as ethoxybutyl acid; dialkylamino esters of (meth)acrylic acid such as dimethylaminoethyl (meth)acrylate and dimethylaminopropyl (meth)acrylate; glycidyl methacrylate, etc. can be mentioned. Among these, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, It is preferable to use n-hexyl methacrylate, lauryl methacrylate, dimethylaminoethyl methacrylate, and glycidyl methacrylate. These monomers may be used alone or in combination of two or more.

Monomers that can be copolymerized with (meth)acrylate include styrene, vinyl acetate, maleic acid, itaconic acid, methacrylic acid, acrylic acid, acrylamide, vinyltoluene, acrylonitrile, and aliphatic carboxylic acid metal (meth)acrylate. Can be mentioned.
Among these, it is preferable to use styrene, vinyl acetate, methacrylic acid, and acrylic acid. These monomers may be used alone or in combination of two or more.

The acrylic resin emulsion can be prepared by making the acrylic resin into an emulsion using an emulsifier. Acrylic emulsions can also be prepared directly by emulsion polymerization. The emulsifier is not particularly limited and may be appropriately selected from anionic emulsifiers and nonionic emulsifiers.

The solid content of the acrylic resin emulsion is preferably about 40 to 60% by weight based on 100% by weight of the emulsion.

(B) A commercially available product can also be used as the emulsion resin liquid. Commercially available products include, for example, Ultrasol N-80 (manufactured by Aica Kogyo Co., Ltd.).

The mass ratio (a/b) of the mass (a) of the coating film forming component of the (A) emulsifying hydrophilic group-containing isocyanate prepolymer to the mass (b) of the coating film forming component of the (B) emulsion resin liquid is 6 or more. It is 200 or less, preferably 6.5 or more and 150 or less, more preferably 7 or more and 100 or less. If the mass ratio (a/b) is within the above numerical range, a sealer coating film with excellent freeze-thaw resistance and adhesion can be formed.

(C) Pigment (C) As the pigment, at least one of extender pigments and coloring pigments can be used. By blending a pigment into a water-based sealer composition, a sealer coating film with excellent freeze-thaw resistance and adhesion can be formed.

The extender pigment is not particularly limited, and conventionally known extender pigments can be used. Examples of extender pigments include calcium carbonate, clay, silica, mica, talc, barium sulfate, feldspar, kaolin, alumina white, magnesium carbonate, barium carbonate, dolomite, and silica. Among these, calcium carbonate, clay, silica, talc and mica are preferred. These extender pigments may be used alone or in combination of two or more.

The coloring pigment is not particularly limited, and conventionally known coloring pigments can be used. Examples of coloring pigments include conventionally known white pigments such as titanium oxide, black pigments such as carbon black, red pigments such as iron oxide (bengara), and yellow pigments such as yellow iron oxide. , blue pigments such as ultramarine blue, and the like. Among these, white pigments and black pigments are preferred. These coloring pigments may be used alone or in combination of two or more.

The mass ratio (c) of the mass (c) of the pigment (C) in the sealer composition to the mass (d) of the total film-forming components of (A) the emulsifying hydrophilic group-containing isocyanate prepolymer and (B) the emulsion resin liquid. /d) is preferably 0.01 or more and 0.60 or less, more preferably 0.02 or more and 0.50 or less, and still more preferably 0.03 or more and 0.40 or less. If the mass ratio (c/d) is within the above numerical range, a sealer coating film with excellent freeze-thaw resistance and adhesion can be formed.

(Other ingredients)
The water-based sealer composition according to the present invention may contain other components in addition to the above-mentioned components as long as the object of the present invention is not impaired. Other ingredients include water, thickener, dispersant, film forming aid, antifoaming agent, pH adjuster, antifouling agent, non-reactive diluent, matting agent, anti-settling agent, leveling agent, heat stabilizer. , an ultraviolet absorber, a light stabilizer, an adhesion improver, a preservative, an antibacterial agent, an antifungal agent, an antiviral agent, a silane coupling agent, a plasticizer, and the like may be added as necessary.

(water)
The water is not particularly limited, and tap water, ion exchange water, etc. may be used. Water may be, for example, water derived from the emulsion resin liquid (B), but it facilitates the preparation of the water-based sealer composition, adjusts the viscosity of the composition, and improves coating workability and inorganic substrates. From the viewpoint of improving the permeability of the sealer, it is preferable to further include water in the sealer composition.

(Filming aid)
Examples of the film-forming aid include conventionally known alcohols, glycol ethers, and esters, such as alcohols having 1 to 3 carbon atoms such as isopropyl alcohol, 2,2,4-trimethylpentanediol, 2, Alcohols such as 2,4-trimethylpentanediol monoisobutyrate (Texanol); glycol ethers such as ethylene glycol diethyl ether, diethylene glycol diethyl ether, propylene glycol diethyl ether, dipropylene glycol diethyl ether, and ethylene glycol monobutyl ether (butyl cellosolve) esters such as 2,2,4-trimethylpentanediol diisobutyrate. One type of film-forming aid may be used, or two or more types may be used.

The content of the coalescent agent in the aqueous sealer composition is not particularly limited, but is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass.

<Method for preparing water-based sealer composition>
The aqueous sealer composition according to the present invention can be obtained by mixing and stirring the above-mentioned components using a conventionally known device such as a mixer, a disperser, or an agitator. Such devices include, for example, mixing/dispersing mills, homodispers, mortar mixers, rolls, paint shakers, homogenizers, and the like. The water-based sealer composition according to the present invention is prepared by thoroughly mixing and stirring the components other than the curing agent (A) emulsifying hydrophilic group-containing isocyanate prepolymer, and finally adding the curing agent (A) emulsifying hydrophilic group-containing isocyanate. Preferably, the prepolymer is mixed to prepare a water-based sealer composition.

The viscosity of the water-based sealer composition is preferably adjusted by diluting it with water, depending on the coating method. Although the viscosity is not particularly limited, it is desirable that it is, for example, 6 to 30 seconds, preferably 7 to 20 seconds in an Iwata cup. By setting the viscosity within this range, the desired coating amount can be easily adjusted.

<Inorganic base material with sealer coating>
The inorganic substrate with a sealer coating according to the present invention has a sealer coating formed from the above water-based sealer composition on at least a portion of the inorganic substrate. In the present invention, the inorganic base material with a sealer coating can be used, for example, on the front side (outer wall side) or the back side (house side) of a building. By using an inorganic base material with a sealer coating, it is possible to provide a building material with excellent freeze-thaw resistance and adhesion.

Building materials refer to members used for the structure and finishing of buildings. Examples include windows, walls, ceilings, floors, roofs, fittings, wallpaper, etc. Particularly preferred are wall materials (top coat, back sheet), floor materials, and the like.

The inorganic base material is not particularly limited as long as it is a commonly used inorganic base material. For example, inorganic base materials include asbestos cement board, asbestos perlite board, calcium silicate board, asbestos cement calcium silicate board, gypsum board, mortar board, pulp cement board, wood chip cement board, and GRC (glass fiber reinforced cement) board. , CFRC (carbon fiber reinforced cement) board, SFRC (steel fiber reinforced cement) board, rock wool inorganic molded body, and the like.

The density (specific gravity) of the inorganic base material is not particularly limited, but is preferably 0.9 to 1.25 g/cm ² , more preferably 0.95 to 1.2 g/cm ² . The density of the inorganic base material can be measured by the Archimedes method.

The thickness of the inorganic base material is not particularly limited, but is preferably, for example, 0.1 to 30 mm, more preferably 1 to 20 mm.

<Production method of inorganic base material with sealer coating>
The inorganic substrate with a sealer coating film according to the present invention can be obtained by applying the water-based sealer composition described above to at least a portion of the inorganic substrate (painting step), and drying the coating film formed in the coating step to harden it. This includes a step (curing step) of forming a sealer coating film.

(Painting process)
The coating process is a process of coating the above water-based sealer composition on at least one side of the inorganic base material by a conventionally known method. Coating methods include, for example, sponge roll coater, natural roll coater, reverse roll coater, curtain flow coater, knife coater, die coater, air spray, airless spray, roller, brush coating, dipping, etc., and can be selected as appropriate. can. Among these, it is preferable to use a spray, flow coater, or sponge roll coater because the amount of coating onto the substrate can be increased and coating film performance such as freeze-thaw resistance and adhesion is improved.

The coating amount of the above water-based sealer composition is preferably 10 to 300 g/m ² , more preferably 20 to 200 g/m ² . If the coating amount is at least the above lower limit, the adhesion between the sealer coating film and the base material (building material) will improve, and if it is below the above upper limit, the drying properties of the sealer coating film will be excellent and workability will be improved. improves. Alternatively, the water-based sealer composition may be applied multiple times.

The coating film thickness after curing and drying is preferably 0.5 to 150 μm. The upper limit is more preferably 100 μm from the viewpoint of drying properties and curability, and the lower limit is more preferably 5 μm from the viewpoints of freeze-thaw resistance and adhesion.

(Curing process)
The curing step is a step of drying the painted surface of the building material and curing the applied water-based sealer composition to form a sealer coating film. Examples of the drying method include hot air drying (using a dryer, etc.). The drying temperature is preferably 10 to 200°C, a more preferable upper limit from the viewpoint of the smoothness and appearance of the coating film is 150°C, and a more preferable lower limit from the viewpoint of drying rate is 30°C.

<Inorganic base material with cured coating>
The inorganic substrate with a cured coating film according to the present invention further comprises a cured coating film on the sealer coating surface of the above-mentioned inorganic substrate with a sealer coating film. The cured coating film can be formed using a conventionally known undercoat paint and/or topcoat paint.

<Production method of inorganic base material with cured coating film>
The method for producing a substrate with a cured coating according to the present invention is to apply an undercoat and/or topcoat on the sealer coating surface of the above-mentioned inorganic substrate with a sealer coating, and to cure the cured coating. It includes a step of forming.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 3, Comparative Example 1]
<Preparation of water-based sealer composition>
First, the following raw materials were prepared to prepare a water-based sealer composition.
・Emulsifying hydrophilic group-containing isocyanate prepolymer (HDI isocyanurate, manufactured by Ohtake Meishin Chemical Co., Ltd., product name: WIC105)
・Emulsion resin liquid (acrylic resin emulsion, manufactured by Aica Kogyo Co., Ltd., product name: Ultrasol N-80)
・Pigment 1 (Extender pigment, calcium carbonate, manufactured by Maruo Calcium Co., Ltd., product name: Tancal Super SS)
・Pigment 2 (color pigment, titanium dioxide, manufactured by Sakai Chemical Industry Co., Ltd., product name: Titanium White R-5N)
・Pigment 3 (color pigment, carbon black dispersion, manufactured by Dainichiseika Kagyo Co., Ltd., product name: MF5630)
・pH adjuster (manufactured by Wacker Chemicals Co., Ltd., product name: BS198)
・Thickener (hydroxyethyl cellulose, manufactured by Daicel Chemical Industries, Ltd., product name: HEC Daicel)
・Preservative (isothiazoline compound, manufactured by So Japan Co., Ltd., product name: Acticide MB)
・Dispersant (hydrophobic polycarboxylic acid copolymer, manufactured by San Nopco Co., Ltd., product name: SN5040)
・Coating agent 1 (Texanol, manufactured by JNC Corporation, product name: CS-12)
・Filming aid 2 (ethylene glycol monobutyl ether, manufactured by (Sankyo Chemical) Co., Ltd., trade name: butyl cellosolve)
・Filming aid 3 (manufactured by Nippon Nyukazai Co., Ltd., product name: BFDG)
・Defoaming agent (mineral oil, polyether compound, manufactured by San Nopco Co., Ltd., product name: SN154)

Next, each component other than component (A) was thoroughly mixed and stirred using a homodisper according to the formulation shown in Table 1. Thereafter, component (A) was further added and mixed and stirred using a homodisper to obtain a water-based sealer composition. An aqueous solution of an aqueous sealer composition was obtained by diluting with water 12.5 times the weight of 100 parts of the base ingredient.

<Production example 1 of inorganic base material with sealer coating>
An inorganic building material board (substrate density (Archimedes method): 1.0 g/cm ² ) was prepared as an inorganic base material, and the board surface temperature was preheated to 35° C. using a hot air dryer. An aqueous solution of the water-based sealer composition of Example 1 was applied to the surface of the substrate in an amount of 80 g/m ² by air spray, and dried at 100° C. for 10 minutes using a hot air dryer to form a sealer coating. Inorganic base material 1-1 was obtained.

Next, a top coat (acrylic resin emulsion paint, product name: CMP top coat enamel, manufactured by Chugoku Paint Co., Ltd.) was applied to 100 parts by mass on the sealer coat of the inorganic base material 1-1 with a sealer coat. A solution diluted with 20 parts by mass of water was applied in an amount of 100 g/m ² by air spray, and dried at 100° C. for 10 minutes using a hot air dryer to obtain an inorganic substrate 1-2 with a cured coating film.

Next, a top coat (acrylic resin emulsion paint, product name: CMP top coat enamel, manufactured by Chugoku Paint Co., Ltd.) was applied to the coating film of the inorganic base material 1-2 with a cured coating film based on 100 parts by mass of water. A diluted product of 20 parts by mass was applied in an amount of 100 g/m ² by air spray and dried at 100° C. for 10 minutes using a hot air drier to obtain a cured inorganic substrate 1-3.

<Production example 2 of inorganic base material with sealer coating film>
An inorganic substrate with a cured coating film 2-3 was obtained in the same manner as in Production Example 1, except that the aqueous solution of the water-based sealer composition of Example 1 was changed to the aqueous solution of the water-based sealer composition of Example 2.

<Production example 3 of inorganic base material with sealer coating film>
An inorganic building material board (substrate density (Archimedes method): 1.1 g/cm ² ) was prepared as an inorganic base material, and the board surface temperature was preheated to 35° C. using a hot air dryer. An aqueous solution of the water-based sealer composition of Example 1 was applied to the surface of the base material in an amount of 70 g/m ² by air spray, and dried at 100° C. for 10 minutes using a hot air dryer to form a sealer coating. Inorganic base material 3-1 was obtained.

Subsequently, on the sealer coating film of the inorganic base material 3-1 with a sealer coating film, an undercoat paint (acrylic resin emulsion paint, product name: CMP undercoat enamel, manufactured by Chugoku Paint Co., Ltd.) was added to 100 parts by mass. A solution diluted with 100 parts by mass of water was applied in an amount of 65 g/m ² by air spray, and dried at 100° C. for 10 minutes using a hot air dryer to obtain an inorganic substrate 3-2 with a cured coating.

Next, a top coat (acrylic resin emulsion paint, product name: CMP top coat enamel, manufactured by Chugoku Paint Co., Ltd.) was added to 100 parts by mass of water on the cured inorganic base material 3-2. A diluted product of 20 parts by mass was applied in an amount of 100 g/m ² by air spray and dried at 100° C. for 10 minutes using a hot air dryer to obtain an inorganic substrate 3-3 with a cured coating film.

<Production example 4 of inorganic base material with sealer coating>
An inorganic substrate 4-3 with a cured coating film was obtained in the same manner as in Production Example 3, except that the aqueous solution of the water-based sealer composition of Example 1 was changed to the aqueous solution of the water-based sealer composition of Example 2.

<Production example 5 of inorganic base material with sealer coating>
An inorganic substrate with a cured coating film 5-3 was obtained in the same manner as in Production Example 3, except that the aqueous solution of the water-based sealer composition of Example 1 was changed to the aqueous solution of the water-based sealer composition of Example 3.

<Production example 6 of inorganic base material with sealer coating>
An inorganic substrate 6-3 with a cured coating film was obtained in the same manner as in Production Example 3, except that the aqueous solution of the water-based sealer composition of Example 1 was changed to the aqueous solution of the water-based sealer composition of Comparative Example 1.

<Evaluation of inorganic base material with coating film>
The following evaluation tests were conducted on each of the inorganic substrates with cured coatings produced in Production Examples 1 to 6 above. The evaluation results are shown in Table 2.

[Evaluation of paint film adhesion]
In order to evaluate the adhesion of the cured coating film to inorganic building materials, an adhesion test was conducted with reference to JIS A5422:2008. Specifically, a 50 mm wide cloth adhesive tape LS (manufactured by Nichiban Co., Ltd., hereinafter referred to as "tape") was pasted onto the cured coating film of the test piece so that the length of the adhesive part was approximately 50 mm. After that, the tape was rubbed with a plastic eraser specified in JIS A 6050 to sufficiently adhere the tape to the effect coating. Thereafter, after 1 to 2 minutes had elapsed, the tape was peeled off, the area of the peeled cured coating film was determined, and the adhesion was evaluated using the following evaluation criteria. Those with an evaluation result of A or B were considered to have passed.
<Evaluation criteria (initial adhesion)>
-A: Peeling area was less than 0.5%.
-B: The peeled area was 0.5% or more and less than 1.0%.
-C: Peeling area was 1.0% or more.

[Freeze-thaw resistance evaluation]
In order to evaluate the freeze-thaw resistance of the cured coating film, a freeze-thaw resistance test was conducted with reference to JIS A1435. Specifically, one cycle consists of cooling the test piece in -20°C air for 2 hours and then immersing it in 20°C water for 2 hours, and after 100 cycles, 200 cycles, and 300 cycles. Visual evaluation of the appearance of the cured coating film was performed using the following evaluation criteria. Further, the same adhesion test as above was conducted on the test pieces after 100 cycles, 200 cycles, and 300 cycles, and the adhesion after the freeze-thaw resistance test was evaluated using the following evaluation criteria. Those with an evaluation result of A or B were considered to have passed.
<Evaluation criteria (appearance/visual inspection)>
-A: Good condition with no peeling, cracking, or blistering.
-B: There was slight peeling, cracking, and blistering, but the overall condition was good.
-C: There were many peelings, cracks, and blisters, which was poor.
<Evaluation criteria (adhesion after freeze-thaw test)>
-A: Peeling area was less than 3%.
-B: The peeled area was 3% or more and less than 5%.
-C: Peeling area was 5% or more.

Claims (10)

(A) an emulsifying hydrophilic group-containing isocyanate prepolymer;
(B) emulsion resin liquid;
(C) A water-based sealer composition comprising a pigment,
The mass ratio (a/b) of the coating film forming component mass (a) of the emulsifying hydrophilic group-containing isocyanate prepolymer (A) to the coating film forming component mass (b) of the emulsion resin liquid (B) is 6. A water-based sealer composition having a molecular weight of at least 200. The water-based sealer composition according to claim 1, wherein the pigment includes at least one of an extender pigment and a colored pigment. The water-based sealer composition according to claim 2, wherein the extender pigment contains at least one selected from the group consisting of calcium carbonate, clay, silica, talc, and mica. The water-based sealer composition according to claim 2, wherein the colored pigment includes at least one of a white pigment and a black pigment. The mass ratio (c/d) of the mass (c) of the pigment (C) to the mass (d) of the total coating film-forming components of the (A) emulsifying hydrophilic group-containing isocyanate prepolymer and the emulsion resin liquid (B). ) is 0.01 or more and 0.60 or less, the aqueous sealer composition according to claim 1. The water-based sealer composition according to claim 1, which is used for coating inorganic building materials. A sealer coating film formed from the water-based sealer composition according to any one of claims 1 to 6. An inorganic substrate with a sealer coating, comprising a sealer coating formed from the aqueous sealer composition according to any one of claims 1 to 6 on at least one side of the inorganic substrate. An inorganic substrate with a cured coating film, further comprising a cured coating film on the sealer coating surface of the inorganic substrate with a sealer coating film according to claim 8. Coating the aqueous sealer composition according to any one of claims 1 to 6 on at least a portion of the inorganic substrate;
A method for producing an inorganic substrate with a sealer coating film, comprising a step of drying and curing the coating film formed in the painting step to form a sealer coating film.