Method for producing aqueous coating material

Abstract

To provide an aqueous coating material that displays sufficient permeability and water cut-off performance to an inorganic porous substrate and gives a uniform finish.SOLUTION: An aqueous coating material of the invention is an aqueous coating material for an inorganic porous substrate and contains a synthetic resin emulsion (A) and a water-soluble silane compound (B). The synthetic resin emulsion (A) has an average particle diameter of 100 nm or less and a pH of 2 or more and 6 or less. The synthetic resin emulsion (A) contains an acrylic silicone resin emulsion. The aqueous coating material contains the water-soluble silane compound (B) of 0.1-20 pts.wt. relative to 100 pts.wt. of the resin solid content of the synthetic resin emulsion (A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel water-based coating material. [Background technology]

[0002] Conventionally, a method of applying a solvent-based penetrating water-absorption inhibitor containing a silane compound as a main component has been widely used to impart water-stopping performance and improve durability to inorganic porous substrates such as concrete and cement mortar used as the framework of buildings, civil engineering structures, etc. However, in recent years, there has been an increasing demand for water-based materials for such materials due to considerations of the surrounding environment and work hygiene.

[0003] As an example of such an aqueous material, Patent Document 1 describes an aqueous liquid for a primer containing a copolymer mainly composed of a cationic monomer, an alkoxysilane monomer, and an ethylenically unsaturated monomer. This aqueous liquid undergoes a crosslinking reaction to form a water-blocking coating, and it is described that by using a high-concentration, low-viscosity resin liquid, it improves substrate permeability, substrate reinforcement, and water resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-1680 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the process of impregnating an inorganic porous substrate with an aqueous liquid such as that described in Patent Document 1, the aqueous liquid may gel (cure) on the surface of the substrate, preventing the aqueous liquid components from fully penetrating into the substrate, resulting in insufficient water-stopping effects. Furthermore, the aqueous liquid components that are not impregnated and remain on the surface of the substrate may cause unevenness, adversely affecting water-stopping performance and aesthetics. Furthermore, when a wetting agent or penetrant is added to improve impregnation, the aqueous medium in the aqueous solution may easily penetrate into the substrate, but the resin components that form the water-stopping coating may not be fully impregnated, resulting in failure to achieve the desired performance.

[0006] The present invention has been made in consideration of these problems, and aims to provide an aqueous coating material that exhibits sufficient permeability and waterproofing performance for inorganic porous substrates and can provide a uniform finish. [Means for solving the problem]

[0007] As a result of extensive research into these problems, the inventors discovered an aqueous coating material containing a specific synthetic resin emulsion (A) and a water-soluble silane compound (B) in a specific weight ratio, and completed the present invention.

[0008] That is, the present invention has the following features. 1. A method for producing an aqueous coating for an inorganic porous substrate, comprising: The aqueous coating material contains a synthetic resin emulsion (A) and a water-soluble silane compound (B), The synthetic resin emulsion (A) has an average particle size of 10 nm or more and 90 nm or less and a pH of 2 or more. 3.7 is as follows: The synthetic resin emulsion (A) contains an acrylic silicone resin emulsion, The water-soluble silane compound (B) is capable of preparing a 1 wt % aqueous silane solution, The synthetic resin emulsion (A) contains 0.1 to 20 parts by weight of the water-soluble silane compound (B) relative to 100 parts by weight of the resin solid content, A method for producing an aqueous coating material, characterized in that the water-soluble silane compound (B) is mixed in an unemulsified state with the synthetic resin emulsion (A). 2. The method for producing an aqueous coating material according to 1., wherein the water-soluble silane compound (B) has a pH of less than 7 when formed into a 1% by weight aqueous solution of the silane. 3. The method for producing an aqueous coating material according to 1., wherein the water-soluble silane compound (B) is an epoxy group-containing silane compound. 4. The method for producing an aqueous coating material according to 1., wherein the aqueous coating material has a pH of 1.5 to 7. 5. The method for producing an aqueous coating material according to 1., wherein the inorganic porous substrate is selected from mortar, concrete, gypsum board, extruded board, slate board, fiber-mixed cement board, calcium silicate board, and ALC board. [Effects of the Invention]

[0009] The aqueous coating material of the present invention exhibits sufficient permeability and waterproofing performance for inorganic porous substrates, and can provide a uniform finish. DETAILED DESCRIPTION OF THE INVENTION

[0010] The aqueous coating material of the present invention is an aqueous coating material for inorganic porous substrates, and contains a synthetic resin emulsion (A) and a water-soluble silane compound (B).

[0011] The synthetic resin emulsion (A) of the present invention may be: (1) an average particle size of 100 nm or less (preferably 10 nm or more and 90 nm or less); (2) pH is 2 or more and 6 or less (preferably 2.5 or more and 5 or less), It is characterized in that:

[0012] When the average particle size of the resin particles in the synthetic resin emulsion (A) is within the range (1), the emulsion can exhibit excellent permeability, reinforcing properties, and adhesion to inorganic porous substrates. This allows the emulsion to exhibit excellent water-stopping performance. On the other hand, if the average particle size of the resin particles exceeds the range (1), sufficient water-stopping performance may not be obtained due to a decrease in permeability and reinforcing properties. In the present invention, the average particle size of the resin particles is a value measured by dynamic light scattering. Specifically, the average particle size can be measured using a dynamic light scattering measuring device ("LB-550" manufactured by Horiba, Ltd.) or the like (measurement temperature: 25°C).

[0013] Furthermore, when the pH of the synthetic resin emulsion (A) is within the range of (2) above, it can exhibit excellent permeability, reinforcing properties, and adhesion to inorganic porous substrates. This allows it to exhibit excellent water-stopping performance. Although the mechanism of action is unclear, it is thought that the surface of the inorganic porous substrate is alkaline except for a small portion, and that by forming a coating in an alkaline environment, it can firmly adhere to the inorganic substrate.

[0014] Although there are no particular limitations on the synthetic resin emulsion (A), an acrylic resin emulsion is preferred, and an acrylic silicone resin emulsion is even more preferred, as this can provide good adhesion to the inorganic porous substrate.

[0015] Furthermore, the synthetic resin emulsion (A) of the present invention preferably contains a cationic acrylic resin emulsion that satisfies the above (1) and (2). Such a cationic acrylic resin emulsion is preferably an aqueous dispersion of a polymer obtained by polymerizing a (meth)acrylic acid alkyl ester and a cationic monomer as essential components as constituent monomers.

[0016] The (meth)acrylic acid alkyl ester is the main component of the resin skeleton. In the present invention, the acrylic acid alkyl ester and the methacrylic acid alkyl ester are collectively referred to as the (meth)acrylic acid alkyl ester. Furthermore, the monomer is a general term for a compound having a polymerizable unsaturated double bond.

[0017] Specific examples of (meth)acrylic acid alkyl esters include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. These can be used alone or in combination of two or more.

[0018] The cationic monomer is not particularly limited as long as it is a cationic monomer having an unsaturated double bond, and examples thereof include cationic (meth)acrylamide-based monomers, cationic maleic acid amide-based monomers, cationic pyridine-based monomers, etc. These can be used alone or in combination of two or more.

[0019] specifically, Examples of cationic (meth)acrylamide monomers include (meth)acrylamide trialkylammonium salts such as 3-acrylamidopropyltrimethylammonium chloride, 2-(meth)acrylamidoethyltrimethylammonium methosulfate, and 2-(meth)acrylamidoethyltrimethylammonium methosulfate; (meth)acrylamidohydroxyalkyltrialkylammonium salts such as 3-(meth)acrylamido-2-hydroxypropyltrimethylammonium chloride, 3-(meth)acrylamido-2-hydroxypropyltrimethylammonium methosulfate, and 3-(meth)acrylamido-2-hydroxypropyltrimethylammonium chloride; dialkylaminoalkyl(meth)acrylamide salts such as 2-dimethylaminoethyl(meth)acrylamide hydrochloride, 2-diethylaminopropyl(meth)acrylamide sulfate, and 2-dimethylaminoethyl(meth)acrylamide hydrochloride; dialkylaminohydroxyalkyl(meth)acrylamide salts such as 3-dimethylamido-2-hydroxypropyl(meth)acrylamide hydrochloride and 3-diethylamino-2-hydroxypropyl(meth)acrylamide sulfate; etc.

[0020] Examples of cationic maleic acid amide monomers include maleic acid (N,N-dimethylpropylenediamine monoamide) salts, etc. By including such cationic monomers, high adhesion to inorganic porous substrates can be exhibited.

[0021] Furthermore, the synthetic resin emulsion (A) of the present invention is preferably a cationic acrylic silicone resin emulsion that satisfies the above (1) and (2).The cationic acrylic silicone resin emulsion is preferably an aqueous dispersion of a polymer obtained by polymerizing the above (meth)acrylic acid alkyl ester, the above cationic monomer, and an alkoxysilane monomer as essential components.

[0022] The alkoxysilane monomer is preferably one having a hydrolyzable alkoxy group together with a polymerizable double bond, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, vinyltriacetoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, vinyltrichlorosilane, γ-(meth)acryloxypropyltris(β-methoxyethoxy)silane, etc. These can be used alone or in combination of two or more.

[0023] In the present invention, in addition to the above-mentioned monomers, for example, aromatic monomers, vinyl ester-based monomers, acrylonitrile-based monomers, etc. may be added as components constituting the synthetic resin emulsion (A). Examples of aromatic monomers include styrene, 2-methylstyrene, vinyltoluene, t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene, divinylbenzene, phenyl(meth)acrylate, and benzyl(meth)acrylate. Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl versatate. Examples of acrylonitrile-based monomers include acrylonitrile, methacrylonitrile, etc. These may be used alone or in combination of two or more.

[0024] The method for polymerizing the synthetic resin emulsion (A) is not particularly limited, and for example, a polymerization initiator, a polymerization catalyst, a reducing agent, a surfactant, a pH adjuster, etc. can be used, and polymerization can be carried out by a known method such as a batch method or an injection method. The polymerization temperature can also be appropriately selected.

[0025] The resin solids content of the synthetic resin emulsion (A) is preferably 1 to 50% by weight (more preferably 5 to 40% by weight). The synthetic resin emulsion (A) contains water as a medium, but may also contain a water-soluble solvent, etc. The minimum film-forming temperature and / or glass transition temperature of the synthetic resin emulsion (A) is preferably 5°C or lower (more preferably 0°C or lower). By using component (A) having such a minimum film-forming temperature and / or glass transition temperature, it is possible to reduce the amount of film-forming aids, etc. used.

[0026] The aqueous coating material of the present invention is characterized by containing a water-soluble silane compound (B) as an essential component. The inclusion of the water-soluble silane compound (B) further enhances the permeability of the synthetic resin emulsion (A), allowing it to form a coating inside the inorganic porous substrate and a uniform coating on the surface of the inorganic porous substrate. This results in superior water-stopping performance and an aesthetically pleasing finish. Particularly in low-temperature environments, a sufficient coating can be formed inside the inorganic porous substrate, resulting in sufficient water-stopping performance. While the mechanism of action is not limited, in general, the viscosity of aqueous coating materials tends to increase significantly in low-temperature environments, making it difficult for the aqueous coating material to penetrate into the inorganic porous substrate. In contrast, the aqueous coating material of the present invention reduces the viscosity of the aqueous coating material due to the action of the water-soluble silane compound (B), thereby enhancing the impregnation of the synthetic resin emulsion (A), and thereby allowing it to form a sufficient coating inside the inorganic porous substrate. This action results in sufficient permeability, allowing it to form a coating inside the inorganic porous substrate and a uniform coating on the surface of the inorganic porous substrate. The water-soluble silane compound in the present invention may be any compound that dissolves in water, and is preferably one that can be used to prepare a 1 wt % aqueous silane solution. When preparing this 1 wt % aqueous silane solution, the pH may be adjusted as necessary.

[0027] Examples of the water-soluble silane compound (B) include epoxy group-containing silane compounds such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane; amino group-containing silane compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltriethoxysilane; (meth)acrylic group-containing silane compounds such as 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and 3-(meth)acryloxypropyltriethoxysilane; and other compounds such as 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, and 3-isocyanatopropylethoxysilane. These can be used alone or in combination of two or more.

[0028] Furthermore, the water-soluble silane compound (B) preferably has a pH of less than 7 (more preferably 1 or more and 6.5 or less, even more preferably 1.5 or more and 6 or less) when 1% by weight of the silane solution is dissolved in water. (That is, the solubility in water of a pH of less than 7 (more preferably 1 or more and 6.5 or less, even more preferably 1.5 or more and 6 or less) is preferably at least 1 g / 100 g.) In this case, the stability of the aqueous coating material is improved (gelation, etc., is suppressed), and the effects of the present invention can be further enhanced. In the present invention, an epoxy group-containing silane compound is suitable as the water-soluble silane compound (B). The pH of the 1% by weight of the silane solution is measured when a 1% by weight of the silane solution is prepared.

[0029] The water-soluble silane compound (B) is contained in an amount of 0.1 to 20 parts by weight (preferably 0.3 to 15 parts by weight, more preferably 0.5 to 10 parts by weight) per 100 parts by weight of the resin solid content of the synthetic resin emulsion (A), which allows the aqueous coating material to have sufficient permeability into inorganic porous substrates and to form a coating film with excellent waterproofing performance and a uniform finish.

[0030] The aqueous coating material of the present invention preferably has a pH of 1.5 to 7 (more preferably 2 to 6.5). Its heating residue is preferably 2 to 30% by weight (more preferably 5 to 20% by weight), and its viscosity measured by Iwata Cup NK-2 is 20 seconds or less (more preferably 15 seconds or less) (at 23°C). In this case, sufficient permeability and waterproofing performance can be imparted to the inorganic porous substrate, and a uniform finish can be obtained. The heating residue of the aqueous coating material is a value measured according to the method of JIS K 5601-1-2, where the heating temperature is 105°C and the heating time is 60 minutes.

[0031] The method for producing the aqueous coating material of the present invention is not particularly limited, and the synthetic resin emulsion (A) and the water-soluble silane compound (B) may be mixed by a conventional method, and stirring may be performed during mixing. The aqueous coating material of the present invention is preferably in a form in which the water-soluble silane compound (B) is dissolved in water, and it is preferable that the water-soluble silane compound (B) is mixed with the synthetic resin emulsion (A) in an unemulsified state.

[0032] The aqueous coating material of the present invention preferably contains a coalescing agent (C). This allows the coating material to fully exhibit its film-forming properties inside the inorganic porous substrate. The amount of the coalescing agent (C) is preferably 10 parts by weight or less (more preferably 0.5 to 5 parts by weight) per 100 parts by weight of the resin solids content of the synthetic resin emulsion (A). Even when the amount of the coalescing agent (C) mixed is within the above range, the aqueous coating material penetrates into the inorganic porous substrate to form a coating, thereby fully exhibiting water-stopping performance. Generally, synthetic resin emulsions containing coalescing agents swell, increasing the viscosity of the aqueous coating material. However, in the present invention, the viscosity of the aqueous coating material is reduced by the action of the water-soluble silane compound (B), so the effect of the coalescing agent (C) can be fully exhibited even when the amount used is within the above range.

[0033] The film-forming aid (C) may be water-insoluble, slightly soluble, or water-soluble. Examples include, but are not limited to, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and benzyl alcohol. Preferred are propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monobutyl ether. These may be used alone or in combination of two or more.

[0034] In addition to the above-mentioned components, the aqueous coating material of the present invention may contain, as necessary, coloring pigments, extender pigments, anti-rust pigments, pH adjusters, plasticizers, preservatives, anti-mold agents, anti-algae agents, anti-foaming agents, leveling agents, pigment dispersants, anti-settling agents, anti-sagging agents, matting agents, catalysts, crosslinking agents, curing accelerators, ultraviolet absorbers, light stabilizers, etc., within the range that does not impair the effects of the present invention.

[0035] (Inorganic porous base material) Examples of the inorganic porous substrate of the present invention include those used for exposed concrete surfaces, non-combustible boards, tunnel interior boards, floor surfaces, flooring materials, etc., such as mortar, concrete, gypsum boards, siding boards, extrusion molded boards, slate boards, fiber-mixed cement boards, calcium silicate boards, and ALC boards.

[0036] When the above-mentioned aqueous coating material is applied to such an inorganic porous substrate, it has sufficient permeability, imparts waterproofing performance to the inorganic porous substrate, and produces a finish with excellent aesthetics without causing unevenness or the like.

[0037] Various methods can be used to apply the aqueous coating material, such as brush coating, roller coating, spray coating, etc. When applying the coating in a factory, a roll coater, flow coater, etc. can also be used.

[0038] The amount of the aqueous coating material to be applied is preferably 0.01 to 0.5 kg / m 2 (More preferably 0.05 to 0.3 kg / m 2 The number of coats of the aqueous coating material can be determined appropriately depending on the condition of the substrate, but is preferably 1 to 2 coats. The drying time of the aqueous coating material is preferably 1 hour or more. The drying temperature is preferably 0°C or higher and 50°C or lower, more preferably 5°C or higher and 40°C or lower.

[0039] The coating film formed by the aqueous coating material of the present invention has excellent adhesion to a wide variety of topcoat materials. The topcoat material is not particularly limited as long as it is generally used for painting buildings and civil engineering structures.

[0040] The method of applying the topcoat material is not particularly limited and can be applied by any known method, but it can be applied by various methods such as brush coating, spray coating, roller coating, roll coater, flow coater, etc. In other words, each topcoat material can be applied based on the usual process with the optimal coating specifications for each topcoat material. [Example]

[0041] Examples and comparative examples will be given below to clarify the features of the present invention.

[0042] (Production of aqueous coating materials 1 to 15) According to the formulations shown in Table 1, component (A), component (B), additives, and water were mixed in a conventional manner to obtain aqueous coating materials 1 to 15. The following raw materials were used: (A1) Acrylic resin emulsion (solid content: 40% by weight, average particle size: 70 nm, pH: 5.1) (A2) Cationic acrylic resin emulsion (solid content: 30% by weight, average particle size: 60 nm, pH: 3.7) (A3) Cationic acrylic silicone resin emulsion (solid content: 30% by weight, average particle size: 40 nm, pH: 3.5) (A4) Acrylic resin emulsion (solid content: 40% by weight, average particle size: 125 nm, pH: 4.0) (A5) Acrylic resin emulsion (solid content: 40% by weight, average particle size: 70 nm, pH: 8.7) (B1) 3-glycidoxypropyltrimethoxysilane (active ingredient: 100% by weight, water solubility: pH 5.3 in 1% by weight aqueous solution) (B2) 3-glycidoxypropyltriethoxysilane (active ingredient: 100% by weight, water soluble: pH 4.0 of 1% by weight aqueous solution) (B3) 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (active ingredient: 100% by weight, water soluble: pH 4.0 of 1% by weight aqueous solution) (B4) N-phenyl-3-aminopropyltrimethoxysilane (active ingredient: 100% by weight, water solubility: pH 4.0 of 1% by weight aqueous solution) (B5) 3-aminopropyltrimethoxysilane (active ingredient: 100% by weight, water soluble: pH 10 of 1% by weight aqueous solution) (B6) P-Styryltrimethoxysilane (active ingredient: 100% by weight, water-insoluble) (B7) Propyltrimethoxysilane emulsion (active ingredient: 30% by weight, contains surfactant) Additive 1: Propylene glycol monobutyl ether Additives 2: Antifoaming agents, thickeners, etc.

[0043] (Examples I-1 to I-10, Comparative Examples I-1 to I-5) Test specimens [I] were prepared for the aqueous coating materials 1 to 15, and the following evaluations were carried out for each. The results are shown in Table 1. <Preparation of test specimen [I]> A water-based coating material was applied at a rate of 0.1 kg / m to an inorganic porous substrate (slate board: L100 x W100 x T3 mm). 2 The specimen was brushed with the paint and cured at room temperature (25°C) for 24 hours to prepare specimen [I].

[0044] <Evaluation of penetration and aesthetics> The surface condition of the above test specimen [I] was visually evaluated for the permeability of the aqueous coating material and the aesthetics (appearance). The evaluation criteria were as follows: A: Good penetration and even finish. B: Penetration is generally good, but there are some uneven areas. C: A coating is formed on the entire surface of the substrate, and the permeability is insufficient. D: Cracks or the like occurred in the coating on the surface of the substrate, and penetration was insufficient.

[0045] <Water-stopping evaluation> Water was sprayed onto the test specimen [I] using a spray bottle to evaluate the water permeability. The evaluation criteria are as follows: A: Water does not penetrate (does not turn wet). B: Water penetrates partially (partially turns wet color). C: Water penetrates the substrate (almost the entire surface turns wet). D: Water penetrates the substrate (the entire surface becomes wet). [Table 1]

[0046] (Examples II-1 to II-10) The following test specimens [II] were prepared for each of the aqueous coating materials 1 to 10, and similar evaluations were carried out. The results are shown in Table 2. <Preparation of test specimen [II]> A water-based coating material was applied at a rate of 0.1 kg / m to an inorganic porous substrate (slate board: L100 x W100 x T3 mm). 2 The specimen [II] was painted with a brush and cured at a low temperature (5°C) for 24 hours.

[0047]

Table 2

Claims

1. 1. A method for producing an aqueous coating for an inorganic porous substrate, comprising: The aqueous coating material contains a synthetic resin emulsion (A) and a water-soluble silane compound (B), The synthetic resin emulsion (A) has an average particle size of 10 nm or more and 90 nm or less and a pH of 2 or more and 3.7 or less, The synthetic resin emulsion (A) contains an acrylic silicone resin emulsion, The water-soluble silane compound (B) is capable of preparing a 1 wt % aqueous silane solution, The synthetic resin emulsion (A) contains 0.1 to 20 parts by weight of the water-soluble silane compound (B) relative to 100 parts by weight of the resin solid content, A method for producing an aqueous coating material, comprising mixing the water-soluble silane compound (B) in an unemulsified state with the synthetic resin emulsion (A).

2. 2. The method for producing an aqueous coating material according to claim 1, wherein the water-soluble silane compound (B) has a pH of less than 7 when formed into a 1 wt % aqueous solution of the silane.

3. 2. The method for producing an aqueous coating material according to claim 1, wherein the water-soluble silane compound (B) is an epoxy group-containing silane compound.

4. 2. The method for producing an aqueous coating material according to claim 1, wherein the aqueous coating material has a pH of 1.5 to 7.

5. The method for producing an aqueous coating material according to claim 1, characterized in that the inorganic porous substrate is selected from mortar, concrete, gypsum board, extruded molded board, slate board, fiber-mixed cement board, calcium silicate board, and ALC board.

Images