Water-based water-repellent coating composition and inorganic building material with cured coating film

Abstract

To provide an aqueous water-repellent coating composition which gives a cured coating film excellent in water repellency, water resistance, and weather resistance.SOLUTION: The aqueous water-repellent coating composition according to the present invention contains (A) titanium oxide, (B) amorphous silica, and (C) a silicone resin. The titanium oxide (A) has a median diameter of 0.1 μm or more and 5 μm or less. The content of the titanium oxide (A) is 30 mass% or more and 65 mass% or less, the content of the amorphous silica is 10 mass% or more and 55 mass% or less, and a pigment mass concentration (PWC) is 50 mass% or more and 80 mass% or less based on 100 mass% of the aqueous water-repellent coating composition in terms of solid content.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aqueous water-repellent coating composition, particularly an aqueous water-repellent coating composition for inorganic building materials. The present invention also relates to an inorganic building material having a cured coating film formed from the aqueous water-repellent coating composition on at least one surface of an inorganic substrate. [Background technology]

[0002] Conventionally, inorganic substrates such as asbestos cement boards and calcium silicate boards are non-flammable and highly durable, and therefore have been coated and used as inorganic building materials. Inorganic building materials have been used, for example, as exterior walls (substrate: siding board) of houses, etc. From the viewpoint of contamination resistance, exterior walls of houses, etc., are often provided with a hydrophilic coating film that can wash away dirt with rainwater, etc. To address these problems, a purifying coating composition has been proposed (see Patent Document 1), which contains as its main components: (a) 3 to 15 parts by weight of amine silicate calculated as SiO2, (b) 0.5 to 8 parts by weight of a synthetic resin, (c) 0.002 to 2 parts by weight of at least one selected from the group consisting of silver, copper, and particulate titanium oxide calculated as 0.002 to 2 parts by weight of silver or copper atoms or 3 to 25 parts by weight of titanium oxide, (d) 15 to 75 parts by weight of a water-insoluble inorganic filler having an average particle size or average length of 0.01 to 50 μm (hereinafter also referred to as "(d) inorganic filler"), and (e) 15 to 75 parts by weight of water and / or a hydrophilic organic solvent (wherein (a) + (b) + (c) + (d) + (e) = 100 parts by weight). However, when a hydrophilic coating film is formed using the coating composition described in Patent Document 1, problems such as algae growth on the hydrophilic coating film occur in places with poor sunlight.

[0003] Furthermore, in coating films with high water permeability but low moisture permeability resistance, moisture that penetrates into the base material of the siding board from the edges or other areas remains inside the base material without being released, which accelerates the deterioration of the siding board. Here, moisture includes both rainwater from the outside and indoor humidity from the inside. Therefore, in recent years, there has been a demand for coating films with high water permeability resistance and high moisture permeability resistance. For example, a moisture-permeable waterproof coating composition characterized by containing a silicone resin emulsion and a synthetic resin emulsion other than the silicone resin emulsion has been proposed (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-298451 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-55600 Summary of the Invention [Problem to be solved by the invention]

[0005] The coating films made from the conventional coating compositions described in Patent Documents 1 and 2 have been evaluated for short- to medium-term weather resistance of about 2 to 5 years, but are thought to lack sufficient long-term (e.g., 10 years or more) weather resistance. However, in recent years, the warranty period for exterior walls of houses and the like has been extended, making it necessary to maintain performance over a long period of time. Therefore, there is a demand for improvements in the long-term water repellency and long-term weather resistance of exterior walls.

[0006] The present invention has been made in view of the above-mentioned background art, and an object of the present invention is to provide an aqueous water-repellent coating composition which can give a cured coating film that is excellent in long-term water repellency, water resistance, and long-term weather resistance. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems, and have found that the above problems can be solved by incorporating specific titanium oxide, amorphous silica, and silicone resin into an aqueous water-repellent coating composition and adjusting the specific titanium oxide content, amorphous silica content, and pigment mass concentration (PWC).The present invention was completed based on this finding.

[0008] That is, according to the present invention, the following inventions are provided. [1] A water-based water-repellent coating composition comprising (A) titanium oxide, (B) amorphous silica, (C) a silicone resin, and water, The median diameter of the titanium oxide (A) is 0.1 μm or more and 5 μm or less, The aqueous water-repellent coating composition has a content of (A) titanium oxide of 30% by mass or more and 65% by mass or less, a content of (B) amorphous silica of 10% by mass or more and 55% by mass or less, and a pigment mass concentration (PWC) of 50% by mass or more and 80% by mass or less, based on 100% by mass of the solid content of the aqueous water-repellent coating composition. [2] The aqueous water-repellent coating composition according to [1], wherein the (B) amorphous silica contains (b1) silica particles having a median diameter of 5 μm or more. [3] The aqueous water-repellent coating composition according to [1] or [2], wherein the (B) amorphous silica contains (b2) diatomaceous earth having a median diameter of 1 μm or more. [4] The aqueous water-repellent coating composition according to any one of [1] to [3], further comprising (D) a coating film-forming resin. [5] The aqueous water-repellent coating composition according to any one of [1] to [4], which is used for coating inorganic building materials. [6] A cured coating film formed from the aqueous water-repellent coating composition according to any one of [1] to [5]. [7] An inorganic building material with a cured coating film, comprising a cured coating film formed on at least one surface of the inorganic building material from the aqueous water-repellent coating composition according to any one of [1] to [5]. [8] A step of applying the aqueous water-repellent coating composition according to any one of [1] to [5] to at least a part of an inorganic building material; a step of drying and curing the coating film formed in the coating step; A method for producing an inorganic building material with a cured coating film, comprising: [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an aqueous water-repellent coating composition that can yield a cured coating film that is excellent in long-term water repellency, water resistance, and long-term weather resistance, and also to provide an inorganic building material that is provided with a cured coating film that is excellent in long-term water repellency, water resistance, and long-term weather resistance. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will now be described in more detail. In this specification, the term "solid content" refers to the amount of volatile components such as water removed from the aqueous water-repellent coating composition, and refers to the components that constitute the cured coating film when cured. The "pigment mass concentration (PWC)" is the percentage of the total mass of the pigment components relative to the mass of the solid content of the aqueous water-repellent coating composition, and is expressed by the following formula: The "pigment component" refers to the following solid particles: (A) titanium oxide, (B) amorphous silica, any other pigments, and additives. PWC = [total mass of pigment components] / [mass of solids in water-based water-repellent coating composition] x 100 (%)

[0011] <Water-based water-repellent coating composition> The aqueous water-repellent coating composition of the present invention contains at least (A) titanium oxide, (B) amorphous silica, (C) a silicone resin, and water. The aqueous water-repellent coating composition of the present invention may further contain (D) a film-forming resin and other components. A cured coating film formed from the aqueous water-repellent coating composition of the present invention has excellent long-term water repellency, water resistance, and long-term weather resistance. Such a cured coating film is suitable for use as a coating (top coat, back sealer) for building materials requiring these properties, particularly inorganic building materials.

[0012] The water content of the aqueous water-repellent coating composition according to the present invention is not particularly limited and can be appropriately adjusted to achieve a viscosity suitable for coating. The water content of the aqueous water-repellent coating composition is preferably 20% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 70% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less.

[0013] The pigment mass concentration (PWC) of the aqueous water-repellent coating composition according to the present invention is 50% by mass or more and 80% by mass or less, preferably 55% by mass or more and 80% by mass or less, and more preferably 60% by mass or more and 80% by mass or less. If the pigment mass concentration content is within the above range, a cured coating film having excellent long-term water repellency, water resistance, and long-term weather resistance can be obtained.

[0014] Each component of the aqueous water-repellent coating composition according to the present invention will now be described in detail.

[0015] ((A) Titanium oxide) The shape of (A) titanium oxide is not particularly limited, and any conventionally known titanium oxide can be used, as long as it has a median diameter of 0.1 μm or more and 5 μm or less. The median diameter of (A) titanium oxide is preferably 0.15 μm or more and 4.5 μm or less, more preferably 0.2 μm or more and 4 μm or less, and even more preferably 0.25 μm or more and 3.5 μm or less. If the median diameter of titanium oxide is within the above numerical range, the cured coating film can exhibit hiding power for the substrate (base). The median diameter of (A) titanium oxide can be calculated as the median value of the diameter of titanium oxide (fine particles) when the cured coating is observed using a scanning electron microscope or a transmission electron microscope.

[0016] As (A) titanium oxide, any of rutile, anatase, and brookite types may be used, with rutile being preferred due to its stability. (A) titanium oxide can typically be titanium dioxide as a color pigment. Titanium dioxide has photocatalytic reactivity and can cause paint film deterioration. Commercially available titanium dioxide for paint applications undergoes various surface treatments to suppress photocatalytic reactivity and to impart dispersion stability. Examples of surface treatment materials include silicon dioxide, aluminum oxide, zirconium dioxide, phosphate esters, selenium, and organic components (such as polyols).

[0017] (A) Commercially available titanium oxide products include, for example, TITONE R-5N (manufactured by Sakai Chemical Industry Co., Ltd.), TIPAQUE R-930, TIPAQUE PFC105, TIPAQUE BLACK SG-103, TIPAQUE ORANGE TY-200, and TIPAQUE YELLOW TY-70 (all manufactured by Ishihara Sangyo Kaisha, Ltd.).

[0018] The content of (A) titanium oxide is 25% by mass or more and 65% by mass or less, preferably 30% by mass or more and 63% by mass or less, more preferably 32% by mass or more and 60% by mass or less, and even more preferably 35% by mass or more and 55% by mass or less, based on 100% by mass of the solid content of the aqueous water-repellent coating composition. If the content of titanium oxide is within the above range, a cured coating film excellent in long-term water repellency, water resistance, and long-term weather resistance can be obtained.

[0019] ((B) Amorphous Silica) As the (B) amorphous silica, at least one of (b1) silica particles and (b2) diatomaceous earth can be used, and it is preferable to use (b2) diatomaceous earth.

[0020] ((b1) Silica particles) The silica particles are not particularly limited in shape, etc., as long as they have a median diameter of 5 μm or more, and conventionally known amorphous silica can be used. The median diameter of the silica particles is preferably 10 μm or more and 100 μm or less, more preferably 15 μm or more and 70 μm or less, and even more preferably 20 μm or more and 50 μm or less. If the median diameter of the silica particles is within the above numerical range, the long-term water repellency and water repellency and slip-off properties of the cured coating film can be further improved. The median diameter of silica particles can be calculated as the median value of the diameters of amorphous silica (fine particles) when the cured coating is observed using a scanning electron microscope or a transmission electron microscope.

[0021] Commercially available amorphous silica particles include, for example, Sylysia 370 and Sylysia 470 (both manufactured by Fuji Silysia Chemical Ltd.), Mizukasil P-78F (manufactured by Mizusawa Industrial Chemicals Ltd.), and OSC-BL6030 (manufactured by Oriental Silicas Co., Ltd.).

[0022] ((b2) Diatomaceous earth) Diatomaceous earth is a type of algae and is a sediment formed from fossilized diatom shells composed primarily of silicon dioxide. Such diatomaceous earth is porous. The shape of the diatomaceous earth is not particularly limited, and any conventionally known diatomaceous earth can be used as long as it has a median diameter of 1 μm or more. The median diameter of the diatomaceous earth is preferably 2 μm or more and 100 μm or less, more preferably 3 μm or more and 70 μm or less, and even more preferably 10 μm or more and 50 μm or less. If the median diameter of the diatomaceous earth is within the above numerical range, the long-term water repellency, water resistance, and long-term weather resistance of the cured coating film can be further improved. The median diameter of diatomaceous earth can be calculated as the median value of the diameter of diatomaceous earth (fine particles) when the cured coating is observed using a scanning electron microscope or a transmission electron microscope.

[0023] Commercially available diatomaceous earth products that can be used include, for example, Celite Snow Floss (manufactured by Tokyo Diatomaceous Earth Industry Co., Ltd.), Radiolite F, Radiolite #100, Radiolite #300, Radiolite #700, and Radiolite #900 (all manufactured by Showa Chemical Industry Co., Ltd.).

[0024] The content of amorphous silica (the total content of (b1) silica particles and (b2) diatomaceous earth) is 10% by mass or more and 55% by mass or less, preferably 11% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 45% by mass or less, and even more preferably 20% by mass or more and 40% by mass or less, based on 100% by mass of the solids content of the aqueous water-repellent coating composition. If the content of amorphous silica is within the above range, a cured coating film with excellent long-term water repellency, water resistance, and long-term weather resistance can be obtained.

[0025] ((C) Silicone resin) As the silicone resin, any conventionally known silicone resin can be used without any particular limitation. From the viewpoint of coating workability, it is preferable to use, for example, a silicone resin emulsion or a silicone resin dispersion in which a polyorganosiloxane obtained by polycondensing an alkoxysilane compound or a condensate thereof is emulsified, dispersed, or dissolved in an aqueous medium.

[0026] Examples of alkoxysilane compounds that are constituent components of polyorganosiloxane include silane compounds having an alkoxy group having 1 to 6 carbon atoms, such as a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a tert-butoxy group, a pentyloxy group, and a hexyloxy group. The alkoxy group may be substituted with a halogen atom such as a chlorine atom or a fluorine atom.

[0027] The alkoxysilane compound may further have an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkanol group, or an aralkyl group. Examples of the alkyl group include linear or branched alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, n-heptyl, n-octyl, isooctyl, 2,2,4-trimethylpentyl, n-nonyl, n-decyl, and n-dodecyl. The alkyl group may be partially substituted with a halogen atom such as a chlorine atom or a fluorine atom, an acryloxy group, a methacryloxy group, a mercapto group, or an epoxycyclohexyl group.

[0028] Examples of cycloalkyl groups include cyclopentyl and cyclohexyl groups. The cycloalkyl groups may be partially substituted with lower alkyl groups having 1 to 6 carbon atoms, and an example of the cycloalkyl group is 4-ethylcyclohexyl. Examples of alkenyl groups include vinyl, allyl, n-5-hexenyl, and 4-vinylcyclohexenyl groups; examples of aryl groups include phenyl, biphenylyl, naphthyl, anthryl, and phenanthryl groups; examples of alkanol groups include o-, m-, and p-tolyl, xylyl, and ethylphenyl groups; and examples of aralkyl groups include benzyl, α-, and β-phenylethyl groups.

[0029] Examples of alkoxysilane compounds having a substituent include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropyltriethoxysilane. Examples of suitable silane include γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane, 3,4-epoxycyclohexylethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, di-n-propyldimethoxysilane, di-n-propyldiethoxysilane, di-i-propyldimethoxysilane, di-i-propyldiethoxysilane, divinyldimethoxysilane, divinyldiethoxysilane, diphenyldimethoxysilane, and diphenyldiethoxysilane. These may be used alone or in any combination of two or more.

[0030] The polyorganosiloxanes used in the present invention include those composed of a plurality of different alkoxysilane compounds, and two or more different polyorganosiloxanes can also be used in any combination.

[0031] For the aqueous water-repellent coating composition of the present invention, emulsions containing polyorganosiloxanes, specifically polydimethylsiloxane, polydiphenylsiloxane, or polymethylphenylsiloxane, are particularly suitable. Specific commercially available products include, but are not limited to, "WACKER BS 45," "WACKER BS 1306," "WACKER BSR50," "WACKER 290," "WACKER SMK 1311," and "WACKER SMK 2101" (all manufactured by Wacker Asahi Kasei Silicone Co., Ltd.), "TEGO Phobe 1000S," "TEGO Phobe 1400," "TEGO Phobe 1500N 10," "TEGO Phobe 1600," and "TEGO Phobe 1650" (all manufactured by Evonik Degussa).

[0032] The content of the silicone resin is preferably 1% by mass or more and 20% by mass or less, more preferably 2% by mass or more and 15% by mass or less, and even more preferably 3% by mass or more and 12% by mass or less, based on 100% by mass of the solid content of the aqueous water-repellent coating composition. If the content of the silicone resin is within the above range, the long-term water repellency, water resistance, and long-term weather resistance of the cured coating film can be further improved.

[0033] (D) Film-forming resin The (D) film-forming resin is not particularly limited, and conventionally known resins can be used in addition to the (C) silicone resin. Examples of such film-forming resins (excluding silicone resins) include synthetic resins such as epoxy resins, (meth)acrylic resins, polyurethane resins, fluorine-containing resins, and polyester resins; and natural resins such as shellac resins, rosin resins, cellulose resins, rubber resins, and cashew resins. These film-forming resins may be appropriately selected to suit the aqueous system (emulsified or dispersed system in water). These film-forming resins may be synthesized by conventionally known methods or may be commercially available products. Among these film-forming resins, (meth)acrylic resins are preferred.

[0034] The epoxy resin is not particularly limited, but examples thereof include resins containing two or more epoxy groups in the molecule, and resins produced by ring-opening reactions of these epoxy groups. Examples of such epoxy resins include glycidyl ether epoxy resins, glycidyl ester epoxy resins, glycidyl amine epoxy resins, bisphenol epoxy resins, novolac epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, fatty acid-modified epoxy resins, and epoxidized oil-based epoxy resins.

[0035] The (meth)acrylic resin is not particularly limited as long as it is a resin other than the following fluorine-based resins, and examples thereof include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate (meth)acrylic acid esters; alicyclic, aromatic, and heterocyclic (meth)acrylic acid esters; cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate (meth)acrylic acid esters; and vinyl group-containing (meth)acrylic acid esters; allyl (meth)acrylate. Examples of suitable resins include resins obtained by (co)polymerizing one or more monomers selected from the following group of monomers: acrylic acid esters; hydroxy group-containing (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate; alkoxy group-containing (meth)acrylic acid esters such as 2-methoxyethyl (meth)acrylate; alkylamino group-containing (meth)acrylic acid esters such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate; di- or tri(meth)acrylic acid esters such as ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate; and carboxy group-containing (meth)acrylic acid esters such as 2-(meth)acryloyloxyethyl phthalate. Here, for example, (meth)acrylic acid means acrylic acid or methacrylic acid, and other similar terms have similar meanings.

[0036] The (meth)acrylic resin may be a resin obtained by copolymerizing, in addition to the above-mentioned monomer group, one or more selected from styrene, vinyl acetate, propionic acid, vinyl butyrate, vinyl benzoate, vinyl toluene, α-methylstyrene, crotonate esters, itaconate esters, etc. Furthermore, the (meth)acrylic resin may be a modified (meth)acrylic resin that has been modified, for example, by alkyd modification, silicone modification, urethane modification, or polyester modification, as necessary.

[0037] The polyurethane resin is not particularly limited as long as it is a resin other than the (meth)acrylic resin and has two or more urethane bonds in the molecule.

[0038] The polyurethane resin can be synthesized, for example, by reacting a compound having active hydrogen at both ends with a polyisocyanate compound. Examples of the compound having active hydrogen include polyol compounds such as polyalkylene glycols, polybutadiene glycols, polyalkylene adipates, polybutadiene glycols, polyalkylene carbonates, silicone polyols, polyester polyols, and acrylic polyols.

[0039] Examples of the polyisocyanate compound include aliphatic polyisocyanates, aromatic polyisocyanates, alicyclic polyisocyanates, and blocked polyisocyanates blocked with β-diketone / oxime / phenol / caprolactam, etc.

[0040] The fluorine-based resin is not particularly limited, and examples thereof include resins having repeating units derived from fluorine-containing ethylene monomers, and specific examples thereof include olefin compounds having fluorine atoms such as tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, trifluoroethylene, vinylidene fluoride, vinyl fluoride, and perfluoroalkyl vinyl ether; and resins obtained by homopolymerizing or copolymerizing compounds such as fluorine atom-containing (meth)acrylate compounds with other monomers. Examples of the other monomers include unsaturated carboxylic acid esters, unsaturated carboxylic acids, α,β-unsaturated nitriles, carbonyl group-containing compounds, conjugated dienes, aromatic vinyls, vinyl ethers, allyl ethers, and alkoxysilanes.

[0041] The polyester resin is not particularly limited as long as it is a resin other than the (meth)acrylic resin and has two or more ester bonds in the molecule, and examples thereof include resins synthesized using a polybasic acid or anhydride thereof and a polyhydric alcohol. Examples of the polybasic acid include phthalic acid, succinic acid, adipic acid, glutaric acid, sebacic acid, isosebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid, dimer acid, trimellitic acid, pyromellitic acid, pimelic acid, and azelaic acid. Examples of the polyhydric alcohol include 1,6-hexanediol, diethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, neopentyl glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol.

[0042] From the viewpoint of coating workability, it is preferable to use a resin emulsion, a resin dispersion, or a resin that is liquid at room temperature (25° C.) as the film-forming resin. These emulsions and dispersions may contain conventionally known additives such as emulsifiers and surfactants, and these can be obtained by polymerizing the monomers described in the above-mentioned column for each resin according to a known method such as emulsion polymerization.

[0043] The content of the film-forming resin is preferably from 1 to 30% by mass, more preferably from 2 to 25% by mass, and even more preferably from 3 to 20% by mass, based on 100% by mass of the solids content of the aqueous water-repellent coating composition. If the content of the film-forming resin is within the above range, the long-term water repellency, water resistance, and long-term weather resistance of the cured coating film can be further improved.

[0044] (Other ingredients) The aqueous water-repellent coating composition of the present invention may contain other components in addition to the above components, provided that the object of the present invention is not impaired. These other components may include, as needed, a diluent (water), extender pigments and coloring pigments (excluding (A) titanium oxide and (B) amorphous silica), pH adjusters, thickeners, dispersants, film-forming aids, antifoaming agents, antifouling agents, non-reactive diluents, matting agents, anti-settling agents, leveling agents, heat stabilizers, UV absorbers, light stabilizers, adhesion improvers, preservatives, antibacterial agents, antifungal agents, antiviral agents, silane coupling agents, plasticizers, etc.

[0045] (Diluent (water)) The diluent (water) is not particularly limited, and may be tap water, ion-exchanged water, etc. The diluent (water) may be, for example, water derived from the (C) silicone resin and the (D) film-forming resin, but from the viewpoints of making it easier to prepare the aqueous water-repellent coating composition, adjusting the viscosity of the composition, and improving coating workability and penetration into inorganic building materials, it is preferable to further blend a diluent (water) into the composition.

[0046] The content of the diluent (water) in the water-based water-repellent coating composition is not particularly limited, but is preferably 10 to 90 mass %, more preferably 20 to 85 mass %, and even more preferably 30 to 80 mass %.

[0047] (Film-forming agent) Examples of the coalescent include conventionally known alcohols, glycol ethers, and esters, such as alcohols having 1 to 3 carbon atoms such as isopropyl alcohol, alcohols such as 2,2,4-trimethylpentanediol and 2,2,4-trimethylpentanediol monoisobutyrate, glycol ethers such as ethylene glycol diethyl ether, diethylene glycol diethyl ether, propylene glycol diethyl ether and dipropylene glycol diethyl ether, and esters such as 2,2,4-trimethylpentanediol diisobutyrate. One or more types of coalescent may be used.

[0048] The content of the coalescence aid in the water-based water-repellent coating composition may be determined taking into consideration that the water-based water-repellent coating composition may freeze in winter due to the inclusion of water, and also taking into consideration the need to obtain appropriate coating workability as a water-based water-repellent coating composition. The content of the coalescence aid in the water-based water-repellent coating composition is not particularly limited, but is preferably 0.1 to 10 mass%.

[0049] <Method for preparing water-based water-repellent coating composition> The aqueous water-repellent coating composition of the present invention can be obtained by mixing and stirring the above-mentioned components using a conventionally known device such as a mixer, disperser, or stirrer. Examples of such devices include a mixing and dispersion mill, a homodisper, a mortar mixer, a roll, a paint shaker, and a homogenizer. The aqueous water-repellent coating composition of the present invention is preferably prepared by thoroughly mixing and stirring the components other than the (D) film-forming resin, and then finally mixing in the (D) film-forming resin.

[0050] <Inorganic building materials with hardened coating> The inorganic building material with a cured coating film according to the present invention comprises, on at least a portion of the inorganic building material, a cured coating film formed from the aqueous water-repellent coating composition described above. In the present invention, the inorganic building material with a cured coating film can be used, for example, as the surface of a building (such as a top coat on an exterior wall) or the back surface (such as a back sealer on a residential building). In particular, by providing a cured coating film on the wall material (surface) of a building, it is possible to maintain long-term water repellency, water resistance, long-term weather resistance, and other performance properties over the long term, and to prevent the adhesion of algae, etc.

[0051] Building materials refer to components used in the structure and finishing of buildings. Examples include windows, walls, ceilings, floors, roofs, fixtures, wallpaper, etc. Wall materials (top coats, back sheets) and floor materials are particularly preferred.

[0052] The inorganic building material is not particularly limited as long as it is a commonly used inorganic substrate, and examples of the inorganic substrate 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, GRC (glass fiber reinforced cement) board, CFRC (carbon fiber reinforced cement) board, SFRC (steel fiber reinforced cement) board, and rock wool inorganic molded body.

[0053] The thickness of the building material is not particularly limited, but is preferably 0.1 to 30 mm, more preferably 1 to 20 mm, for example.

[0054] <Method for manufacturing inorganic building materials with hardened coating film> The inorganic building material with a cured coating film according to the present invention comprises a step of applying the above-mentioned aqueous water-repellent coating composition to at least a part of the inorganic building material (coating step), and a step of drying and curing the coating film formed in the coating step (curing step).

[0055] (painting process) The coating process is a process of coating at least one side of an inorganic building material with the aqueous water-repellent coating composition by a conventionally known method. For example, a sponge roll coater, a natural roll coater, a reverse roll coater, a curtain flow coater, a knife coater, a die coater, an air spray, an airless spray, a roller, a brush coating, immersion, etc. can be used, and can be appropriately selected. Among these, the use of a spray, a flow coater, or a sponge roll coater is preferred because it allows a larger amount of coating to be applied to the substrate and improves coating film performance such as water resistance.

[0056] The coating amount of the aqueous water-repellent coating composition is preferably 1 to 300 g / m 2 and more preferably 10 to 200 g / m 2 When the coating amount is equal to or greater than the lower limit, the adhesion between the cured coating film and the substrate (building material) is improved, and when the coating amount is equal to or less than the upper limit, the cured coating film has excellent drying properties and workability is improved. The aqueous water-repellent coating composition may be applied multiple times.

[0057] The coating thickness after curing and drying is preferably 0.5 to 150 μm. From the viewpoints of drying and curing properties, the upper limit is more preferably 100 μm, and from the viewpoints of long-term water repellency, water resistance, and long-term weather resistance, the lower limit is more preferably 5 μm.

[0058] (hardening process) The curing step is a step in which the coated surface of the building material is dried to cure the applied aqueous water-repellent coating composition and form a cured coating film. Examples of drying methods include hot air drying (using a dryer, etc.). The drying temperature is preferably 10 to 200°C, with a more preferred upper limit of 150°C from the viewpoint of the smoothness and appearance of the coating film, and a more preferred lower limit of 30°C from the viewpoint of drying speed. [Example]

[0059] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0060] [Examples 1 to 18, Comparative Examples 1 to 15] <Preparation of Water-Based Water-Repellent Coating Composition> First, the following raw materials were prepared for preparing the water-based water-repellent coating composition. Titanium dioxide 1: White, median diameter 0.5 μm, manufactured by Sakai Chemical Industry Co., Ltd., product name: TITONE R-5N Titanium dioxide 2: White, median diameter 0.28 μm, manufactured by Ishihara Sangyo Kaisha, Ltd., product name: Typaque PFC105 (ultra-high weather resistance) Titanium dioxide 3: Black, median diameter 1.2 μm, manufactured by Ishihara Sangyo Kaisha, Ltd., product name: Typaque Black SG-103 (black heat-shielding) Titanium dioxide 4: Orange, median diameter 0.7 μm, manufactured by Ishihara Sangyo Kaisha, Ltd., product name: Typaque Orange TY-200 (high weather resistance) Titanium dioxide 5: Yellow, median diameter 0.7 μm, manufactured by Ishihara Sangyo Kaisha, Ltd., product name: Typaque Yellow TY-70 (high weather resistance) Silica particles 1: Median diameter 6.4 μm, Fuji Silysia Chemical Ltd., Product name: Silica 370 Silica particles 2: Median diameter 14 μm, Fuji Silysia Chemical Ltd., Product name: Silica 470 (14 μ) Silica particles 3: Median diameter 18 μm, Mizusawa Industrial Chemicals, Ltd., product name: Mizukasil P-78F Silica particles 4: Median diameter 20 to 50 μm, manufactured by Oriental Silicas Co., Ltd., product name: OSC-BL6030 Diatomaceous earth 1: Median diameter 1-2 μm, manufactured by Tokyo Diatomaceous Earth Industry Co., Ltd., Product name: Celite Snow Floss Diatomaceous earth 2: Median diameter 4.3 μm, manufactured by Showa Chemical Industry Co., Ltd., product name: Radiolite F Diatomaceous earth 3: Median diameter 13 μm, manufactured by Showa Chemical Industry Co., Ltd., product name: Radiolite #100 Diatomaceous earth 4: Median diameter 15 μm, manufactured by Showa Chemical Industry Co., Ltd., product name: Radiolite #300 Diatomaceous earth 5: Median diameter 30 μm, manufactured by Showa Chemical Industry Co., Ltd., product name: Radiolite #700 Diatomaceous earth 6: Median diameter 40 μm, manufactured by Showa Chemical Industry Co., Ltd., product name: Radiolite #900 Silicone resin 1: Wacker Chemicals Co., Ltd., product name: BS45 Silicone resin 2: Water-dilutable, manufactured by Wacker Chemicals Co., Ltd., product name: BS1306 Carbon black: Orion Engineered Carbons GmbH, Carbon Black FW200 Iron oxide 1: Yellow iron oxide, manufactured by Toda Kogyo Co., Ltd., product name: Yellow iron oxide TSY-1 Iron oxide 2: Bengalese red, manufactured by Toda Pigment Co., Ltd., product name: Moonlight BB Calcium carbonate 1: Median diameter 5 μm, manufactured by Maruo Calcium Co., Ltd., product name: Tankal Super SS Calcium carbonate 2: Median diameter 12 μm, manufactured by Maruo Calcium Co., Ltd., product name: Heavy calcium carbonate Calcium carbonate 3: Median diameter 20 μm, manufactured by Maruo Calcium Co., Ltd., product name: R Heavy Carbon Mica 1: Median diameter 42 μm, manufactured by Yamaguchi Mica Co., Ltd., product name: SYA-41R Mica 2: Median diameter 16 μm, manufactured by Lingshou Huajing Mica Co., Ltd., Product name: Mica powder 325 mesh Mica 3: Median diameter 2.4 μm, manufactured by Yamaguchi Mica Co., Ltd., product name: Mica powder A-11 Acrylic emulsion: Manufactured by Ohtake Meishin Chemical Co., Ltd., product name: WSR325 pH adjuster: Wacker Chemicals Co., Ltd., product name: BS198 Thickener: Sumitomo Seika Chemicals Co., Ltd., product name: FUJI CHEMI HEC SW-25F Preservative: Osaka Gas Chemicals Co., Ltd., product name: Deltop Dispersant: Rohm & Haas Company, trade name: 25% Orotane 731 aqueous solution Film-forming agent: JNC Corporation, product name: Texanol (A) CS-12 Defoamer: BASF Japan Ltd., product name: Foamaster MO 2111 NC

[0061] Next, components (A) to (C) and components other than component (D) were thoroughly mixed and stirred using a Homodisper according to the formulations shown in Tables 1 to 4, and then component (D) was added and mixed and stirred using a Homodisper to obtain an aqueous water-repellent coating composition.

[0062] <Manufacturing inorganic building materials with hardened coating> The aqueous water-repellent coating compositions obtained in Examples 1 to 18 and Comparative Examples 1 to 15 were diluted with 40 parts by mass of water per 100 parts by mass of the composition and then applied to an inorganic building board (calcium silicate board) at a rate of 140 g / m using an air spray. 2 The coating was applied in a coating amount of 100 μm. The coated surface of the inorganic building material was then dried in a hot air dryer at 100°C for 20 minutes to harden the coating film, yielding an inorganic building material with a hardened coating film. The thickness of the hardened coating film was 40 to 50 μm.

[0063] <Evaluation of inorganic building materials with hardened coating> The inorganic building materials with cured coating films produced in Examples 1 to 18 and Comparative Examples 1 to 15 were subjected to the following evaluation tests.

[0064] [Water repellency evaluation] (Contact angle measurement test) To evaluate the water repellency of inorganic building materials with cured coatings, the contact angle of water was measured. Specifically, an automatic contact angle meter ("Drop Master DM500", manufactured by Kyowa Interface Science Co., Ltd.) was used to drop 1 μl of pure water onto the cured coating surface of a test panel (10 cm × 10 cm) of the inorganic building material with cured coating. The contact angle with water was measured 10 seconds after the drop landed, and the water repellency was evaluated according to the following criteria. The evaluation results are shown in Tables 1 to 4. [Evaluation criteria] 5 points: The contact angle was 130 degrees or more. 4 points: The contact angle was between 120 degrees and 130 degrees. 3 points: The contact angle was between 110 degrees and 120 degrees. 2 points: The contact angle was between 100 degrees and 110 degrees. 1 point: The contact angle was less than 100 degrees.

[0065] (Slip-off test) To evaluate the water repellency of inorganic building materials with a cured coating film, the water sliding property was measured. Specifically, a test panel (10 cm × 10 cm) of the inorganic building material with a cured coating film was tilted 30 degrees relative to a horizontal table, with the cured coating surface facing upward. Next, one drop of water (approximately 0.05 mL) was dropped onto the top edge of the test panel from a height of 5 cm above the test panel using a dropper, and the sliding property was evaluated according to the following criteria. The evaluation results are shown in Tables 1 to 4. [Evaluation criteria] 5 points: The water droplets rolled off the test plate. 4 points: The drop rolled but stopped halfway down the test plate. 3 points: The droplet stopped immediately after rolling. 2 points: Water droplets formed but did not roll. 1 point: The water spread out without forming droplets.

[0066] [Water resistance evaluation] (Water resistance test) To evaluate the water resistance of the cured coating film, a hot water resistance test was conducted. Specifically, each test piece (10 mm × 10 mm) with a cured coating film was immersed in hot water at 60°C for 240 hours. The test piece was then removed from the hot water, and the coating surface was lightly wiped. A cross-cut adhesion test was conducted based on JIS K5400 to evaluate the adhesion of the cured coating film to inorganic building materials. [Evaluation criteria (adhesion after 240 hours of water resistance test / cross-cut test)] 5 points: 25 squares remaining. 4 points: The number of remaining squares was between 23 and 25. 3 points: The number of remaining squares was 21 or more but less than 23. 2 points: The number of remaining squares was 19 or more but less than 21. 1 point: The number of remaining squares was 17 or more but less than 19. 0 points: Fewer than 17 squares remaining.

[0067] Subsequently, a contact angle measurement test and a sliding test were carried out in the same manner as in the water repellency evaluation, except that the test plates after the water resistance test were used. The evaluation results are shown in Tables 1 to 4.

[0068] [Weather resistance evaluation] (Weather resistance test) Weathering tests were conducted to evaluate the weathering resistance of the inorganic building materials with cured coatings. Specifically, accelerated weathering tests were conducted using an Eye Super UV Tester on the cured coating surface of test panels (5cm x 5cm) of each inorganic building material with cured coatings to evaluate the weathering resistance of the coating. Specifically, the weathering tests were conducted under the following conditions: Testing equipment: Eye Super UV Tester (manufactured by Iwasaki Electric Co., Ltd., filter: WJ100-SUV, irradiance on test piece surface: 75 mW / cm 2 , wavelength range; 295~450nm) Test time: 1000 hours Test cycle: 4 hours of irradiation → 4 hours of condensation (30-second shower before and after condensation) Average humidity: 50% when irradiated, 98% when condensed, Black panel temperature: 63°C during irradiation, 30°C during condensation

[0069] Subsequently, the gloss of the cured coating surface of the test panel after the weather resistance test was measured using a gloss meter ("GLOSSMETER", manufactured by Murakami Color Research Laboratory Co., Ltd.). The gloss of the cured coating surface of the test panel before the weather resistance test was measured in advance using the same method, and the gloss retention was calculated using the following formula. The evaluation results are shown in Tables 1 to 4. Gloss retention rate (%) = gloss of the cured coating surface of the test panel after weather resistance test / gloss of the cured coating surface of the test panel before weather resistance test × 100 [Evaluation criteria] 5 points: Gloss retention was 90% or more. 4 points: Gloss retention was 80% or more but less than 90%. 3 points: Gloss retention was 70% or more but less than 80%. 2 points: Gloss retention was 60% or more but less than 70%. 1 point: Gloss retention was less than 60%.

[0070] The contact angle measurement test and the sliding test were carried out in the same manner as in the water repellency evaluation, except that the test plates after the weather resistance test were used. The evaluation results are shown in Tables 1 to 4.

[0071] [Table 1]

[0072] [Table 2]

[0073] [Table 3]

[0074] [Table 4]

Claims

1. A water-based water-repellent coating composition comprising (A) titanium oxide, (B) amorphous silica, and (C) a silicone resin, The median diameter of the titanium oxide (A) is 0.1 μm or more and 5 μm or less, The (B) amorphous silica is (b2) diatomaceous earth having a median diameter of 1 μm or more, The aqueous water-repellent coating composition has a content of (A) titanium oxide of 30% by mass or more and 65% by mass or less, a content of (B) amorphous silica of 10% by mass or more and 30.8% by mass or less, and a pigment mass concentration (PWC) of 50% by mass or more and 80% by mass or less, based on 100% by mass of the aqueous water-repellent coating composition in terms of solid content.

2. 2. The aqueous water-repellent coating composition according to claim 1, wherein the median diameter of the diatomaceous earth (b2) is 10 μm or more and 50 μm or less.

3. An aqueous water-repellent coating composition as described in claim 1 or 2, wherein the content of the (C) silicone resin is 1 mass % or more and 20 mass % or less, based on 100 mass % of the solid content of the aqueous water-repellent coating composition.

4. The aqueous water-repellent coating composition according to any one of claims 1 to 3, further comprising (D) a film-forming resin.

5. The aqueous water-repellent coating composition according to any one of claims 1 to 4, which is used for coating inorganic building materials.

6. A cured coating film formed from the aqueous water-repellent coating composition according to any one of claims 1 to 5.

7. An inorganic building material with a cured coating film, comprising a cured coating film formed from the aqueous water-repellent coating composition according to any one of claims 1 to 5 on at least one surface of the inorganic building material.

8. A step of applying the aqueous water-repellent coating composition according to any one of claims 1 to 5 to at least a part of an inorganic building material; a step of drying and curing the coating film formed in the coating step; A method for producing an inorganic building material with a cured coating film, comprising:

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