Aqueous coating material

Abstract

To provide an aqueous coating material which can suppress an appearance change in discoloration and a gloss change of a film in which gloss is reduced by an antiseptic solution while forming the film.SOLUTION: An aqueous coating material contains a resin emulsion, a coloring pigment and an extender pigment, wherein pigment volume concentration is 15 to 60%, an average particle diameter of the extender pigment is 80 μm or less, a content of the extender pigment is 20 to 400 pts.wt. with respect to 100 pts.wt. of a solid content of the resin emulsion, a low oil absorption amount extender pigment having an oil absorption amount of less than 100 ml / 100 g is contained as the extender pigment, a ratio of the low oil absorption amount extender pigment is 50 wt.% or more, and a ratio of calcium carbonate is 20 wt.% or less in a total amount of the extender pigment.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Conventionally, buildings and civil engineering structures have been coated with various coating materials for the purpose of surface protection, improving aesthetics, etc. Among these, matte-type coating materials are widely used because they can form a coating film with reduced surface gloss and provide a calm finish. In recent years, the coating field has been moving toward water-based coatings against the backdrop of efforts to reduce environmental impact, and matte-type coating materials are no exception.

[0003] As an example of such a matte-type coating material, for example, Patent Document 1 (JP 2002-201419 A) describes an aqueous coating material that contains a film-forming resin, a color pigment, and an extender pigment such as heavy calcium carbonate, and has a pigment volume concentration of 20 to 60%. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-201419 A Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, the number of occasions where the interior surfaces of buildings and the like are cleaned using alcohol-based, acidic, or other disinfectants or sanitizing solutions (hereinafter referred to as "disinfectants, etc.") for the purpose of disinfection and sterilization has increased. However, when disinfectants, etc. are used on the coating of the above-mentioned water-based coating material, the coating may discolor or lose its luster. In addition, if the disinfectants, etc. remain on the coating, the traces may become stains, etc., and the appearance of the coating may be damaged.

[0006] The present invention has been made in consideration of the above points, and aims to provide an aqueous coating material that can form a coating with reduced gloss while suppressing changes in appearance of the coating, such as discoloration and gloss changes, caused by disinfectants, etc. [Means for solving the problem]

[0007] In order to solve these problems, the present inventors conducted extensive research and came up with the idea of ​​an aqueous coating material having a specific extender pigment composition, thereby completing the present invention.

[0008] That is, the present invention has the following features. 1. An aqueous coating material comprising a resin emulsion, a color pigment, and an extender pigment, The pigment volume concentration is 15-60%. The average particle size of the body pigment is 80 μm or less, The content of the extender pigment is 20 to 400 parts by weight per 100 parts by weight of the solid content of the resin emulsion, The extender pigment includes a low oil absorption extender pigment having an oil absorption of less than 100 ml / 100 g, The ratio of the low oil absorption body pigment to the total amount of the body pigment is 50% by weight or more, The ratio of calcium carbonate to the total amount of the above body pigments is 20% by weight or less. 1. An aqueous coating material comprising: 2. The above-mentioned extender pigment includes a high oil absorption extender pigment having an oil absorption of 100 ml / 100 g or more, The ratio of the high oil absorption extender pigment to the total amount of the extender pigment is 50% by weight or less. 1. The aqueous coating material according to claim 1. Effect of the Invention

[0009] According to the present invention, it is possible to form a coating with reduced gloss while suppressing changes in appearance of the coating, such as discoloration and gloss changes, caused by disinfectants and the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described.

[0011] The aqueous coating material of the present invention (hereinafter also simply referred to as "coating material") contains a resin emulsion, a color pigment, and an extender pigment.

[0012] Among these, the resin emulsion is a component that acts as a binder. The resin emulsion is formed by emulsifying and dispersing a resin in an aqueous medium (a medium containing water).

[0013] Examples of the resin in the resin emulsion include vinyl acetate resin, vinyl chloride resin, epoxy resin, alkyd resin, acrylic resin, urethane resin, silicone resin, fluororesin, and composites thereof. These can be used alone or in combination of two or more.

[0014] In the present invention, the resin emulsion preferably includes an acrylic resin emulsion. The acrylic resin emulsion is an aqueous dispersion of polymer particles mainly composed of (meth)acrylic acid alkyl ester. Such an acrylic resin emulsion can be obtained, for example, by emulsion polymerization of a monomer group including (meth)acrylic acid alkyl ester and other monomers as required, by a known method.

[0015] Examples of (meth)acrylic acid alkyl esters include 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, phenyl (meth)acrylate, and benzyl (meth)acrylate. These can be used alone or in combination. The composition ratio of such (meth)acrylic acid alkyl esters is preferably 30% by weight or more, more preferably 40 to 99.9% by weight, and even more preferably 50 to 99.5% by weight, based on the total monomers constituting the resin. In the present invention, alkyl acrylates and alkyl methacrylates are collectively referred to as alkyl (meth)acrylates. In addition, in the present invention, "a to b" has the same meaning as "a or more and b or less".

[0016] Examples of the other monomers include carboxyl group-containing monomers, amino group-containing monomers, pyridine-based monomers, hydroxyl group-containing monomers, nitrile group-containing monomers, amide group-containing monomers, epoxy group-containing monomers, carbonyl group-containing monomers, alkoxysilyl group-containing monomers, and aromatic monomers. These can be used alone or in combination of two or more. The composition ratio of these other monomers is preferably 0.1 to 60% by weight, more preferably 0.5 to 50% by weight, based on the total monomers constituting the resin.

[0017] The acrylic resin emulsion may be any emulsion that satisfies the above conditions. Examples of the acrylic resin emulsion that can be used include an acrylic-styrene resin emulsion, an epoxy-modified acrylic resin emulsion, a urethane-modified acrylic resin emulsion, a silicon-modified acrylic resin emulsion, and a fluorine-modified acrylic resin emulsion.

[0018] The average particle size of the resin emulsion in the present invention is preferably 50 to 500 nm, more preferably 70 to 300 nm, and further preferably 80 to 250 nm. The average particle size of the resin emulsion is a value measured by a dynamic light scattering method. Specifically, it can be measured using a dynamic light scattering measuring device (measurement temperature: 25°C).

[0019] The glass transition temperature of the resin constituting the resin emulsion is preferably −30 to 60° C., and more preferably −20 to 40° C. This glass transition temperature can be determined by the Fox formula.

[0020] The resin emulsion in the present invention can be produced, for example, by one-stage to multi-stage (two-stage, three-stage or more) emulsion polymerization methods, etc. Among these, when multi-stage emulsion polymerization is adopted, for example, a multi-layer structure type emulsion (such as a core-shell type emulsion) can be obtained.

[0021] In the present invention, a crosslinking reaction type resin emulsion can also be used as the resin emulsion. Examples of the crosslinking reaction in the crosslinking reaction type resin emulsion include combinations of a carboxyl group and a metal ion, a carboxyl group and an epoxy group, a carboxyl group and a carbodiimide group, a carboxyl group and an aziridine group, a carboxyl group and an oxazoline group, a hydroxyl group and an isocyanate group, a carbonyl group and a hydrazide group, an epoxy group and a hydrazide group, an epoxy group and an amino group, and a combination of hydrolyzable silyl groups. Among these, preferred crosslinking reactions include a combination of a carboxyl group and an epoxy group, a carboxyl group and a carbodiimide group, a carboxyl group and an oxazoline group, a carbonyl group and a hydrazide group, and a combination of hydrolyzable silyl groups. Examples of such crosslinking reaction type resin emulsions include those in which functional groups in the emulsion particles undergo a crosslinking reaction, or those in which a crosslinking agent mixed separately and a functional group in the emulsion particles undergo a crosslinking reaction. These may be one-liquid type, two-liquid type, or the like.

[0022] The crosslinking agent may be, for example, a compound having one or more reactive functional groups selected from an epoxy group, a carbodiimide group, an oxazoline group, a hydrazide group, etc. When the crosslinking agent has one or more reactive functional groups selected from an epoxy group, a carbodiimide group, an oxazoline group, etc., the resin emulsion may be, for example, one having a carboxyl group, etc. When the crosslinking agent has a hydrazide group, the resin emulsion may be, for example, one having a carbonyl group, etc.

[0023] Examples of crosslinking agents containing an epoxy group include polyethylene glycol diglycidyl ether, polyhydroxyalkane polyglycidyl ether, diglycerol polyglycidyl ether, and sorbitol polyglycidyl ether.

[0024] Examples of crosslinking agents containing a carbodiimide group include those described in JP-A-10-60272, JP-A-10-316930, JP-A-11-60667, JP-A-2016-196612, JP-A-2016-196613, JP-A-2018-104605, and JP-A-2019-038960.

[0025] Examples of crosslinking agents containing an oxazoline group include resins obtained by copolymerizing a polymerizable oxazoline compound, such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, or 2-isopropenyl-2-oxazoline, with a monomer copolymerizable with the compound.

[0026] Examples of crosslinking agents containing a hydrazide group include malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, and maleic acid dihydrazide.

[0027] The content of the crosslinking agent is preferably 0.01 to 20 parts by weight, and more preferably 0.05 to 10 parts by weight, calculated as solid content, based on 100 parts by weight of the solid content of the resin emulsion.

[0028] The color pigment is a component that imparts a desired color to the coating material. Examples of the color pigment include inorganic chromatic pigments such as ferric oxide (red oxide), yellow iron oxide, ultramarine, and cobalt green; organic chromatic pigments such as azo, naphthol, pyrazolone, anthraquinone, perylene, quinacridone, disazo, isoindolinone, benzimidazole, phthalocyanine, and quinophthalone; black pigments such as carbon black, iron-manganese composite oxide, iron-copper-manganese composite oxide, iron-chromium-cobalt composite oxide, copper-chromium composite oxide, copper-manganese-chromium composite oxide, and black iron oxide; white pigments such as titanium oxide, zinc oxide, and alumina; and pearl pigments, aluminum pigments, photoluminescent pigments, phosphorescent pigments, and fluorescent pigments. These can be used alone or in combination. The average particle size of the color pigment is preferably less than 1 μm, and more preferably 0.01 to 0.9 μm. In the present invention, the average particle size of pigments (color pigments, extender pigments, etc.) is an average value measured using a laser diffraction particle size distribution measuring device (measurement temperature: 25° C.).

[0029] The content of the color pigment is preferably 1 to 500 parts by weight, more preferably 5 to 300 parts by weight, and further preferably 10 to 200 parts by weight, based on 100 parts by weight of the solid content of the resin emulsion. If the content of the color pigment is within such a range, it is suitable in terms of the color development and hiding power of the coating, and is also advantageous in terms of the manifestation of the effects of the present invention.

[0030] In the present invention, the pigment contains a body pigment in addition to the above color pigment. This reduces the gloss of the coating surface and gives a calm finish. Examples of the body pigment include kaolin, clay, aluminum silicate, calcined clay, calcined kaolin, china clay, diatomaceous earth, hydrated silicon dioxide, silica gel, zeolite, sodium sulfate, allophane, talc, mica, barite powder, barium sulfate, precipitated barium sulfate, barium carbonate, magnesium carbonate, silica powder, aluminum hydroxide, heavy calcium carbonate, light calcium carbonate, porous calcium carbonate, siliceous shale, vermiculite, perlite, Oya stone powder, activated clay, activated carbon, and shirasu balloon. These can be used alone or in combination of two or more. The average particle size of the body pigment is 80 μm or less, preferably 1 to 50 μm, more preferably 1.5 to 40 μm, and even more preferably 2 to 30 μm. In the present invention, the average particle size of the extender pigment is within this range, which is advantageous in terms of reducing gloss in the formed coating, improving finish, and ease of cleaning with a disinfectant or the like (ease of wiping off, etc.).

[0031] In the coating material of the present invention, these pigments (color pigment and extender pigment) are mixed so that the pigment volume concentration is in the range of 15 to 60%. By setting the pigment volume concentration within this range, it is possible to obtain the effects of the present invention. If the pigment volume concentration is below the above lower limit, it becomes difficult to obtain the gloss reduction effect, and if it exceeds the above upper limit, it becomes difficult to suppress changes in appearance such as discoloration of the coating and gloss change caused by disinfectants, etc. The pigment volume concentration is the volume percentage of the pigment contained in the dry coating, and is a value calculated from the mixed amounts of the resin and pigment that constitute the coating material. The specific gravity of the resin is 1. Specifically, in a completely matte coating, the pigment volume concentration can be set to preferably 35 to 55% (more preferably 36 to 50%). In a 30% gloss coating, the pigment volume concentration can be set to preferably 15% or more and less than 35% (more preferably 18 to 34%).

[0032] The present invention is characterized in that the extender pigment satisfies the following conditions (1), (2), and (3), which makes it possible to form a coating with reduced gloss while suppressing changes in appearance, such as discoloration and gloss changes, of the coating caused by disinfectants and the like. (1) The content of the extender pigment is 20 to 400 parts by weight per 100 parts by weight of the solid content of the resin emulsion. (2) The extender pigment contains a low oil absorption extender pigment having an oil absorption of less than 100 ml / 100 g, and the ratio of the low oil absorption extender pigment to the total amount of the extender pigment is 50% by weight or more (preferably 55% by weight or more, more preferably 60 to 99% by weight, and even more preferably 65 to 98% by weight). (3) The ratio of calcium carbonate in the total amount of the extender pigment is 20% by weight or less (preferably 10% by weight or less, and more preferably 3% by weight or less).

[0033] The reasons why the effects of the present invention are achieved by satisfying the above conditions (1) to (3) are thought to be, but are not limited to, the following: the extender pigment creates fine irregularities on the coating surface, the penetration of disinfectants and the like into the coating is suppressed, and the coating has sufficient resistance to disinfectants and the like.

[0034] Regarding (1) above, if the content of the extender pigment is less than the above lower limit, the reduction in gloss will be insufficient, whereas if it exceeds the above upper limit, there is a risk that the appearance of the coating will change due to the disinfectant or the like.

[0035] Regarding the above (2), various extender pigments can be used as the low oil absorption extender pigment having an oil absorption of less than 100 ml / 100 g (preferably 10 ml / 100 g or more and less than 100 ml / 100 g, more preferably 20 to 90 ml / 100 g, even more preferably 25 to 85 ml / 100 g, and particularly preferably 30 to 80 ml / 100 g) as long as they satisfy the above physical properties. Examples of low oil absorption extender pigments include kaolin, clay, aluminum silicate, calcined clay, calcined kaolin, china clay, talc, barite powder, barium sulfate, silica powder, aluminum hydroxide, calcium carbonate, etc. These can be used alone or in combination of two or more.

[0036] The oil absorption (ml / 100 g) is a value determined by the method specified in JIS K5101-13-2:2004, and is expressed in ml of boiled linseed oil per 100 g of pigment.

[0037] Regarding (2) above, if the ratio of the low oil absorption body pigment to the total amount of the body pigments is less than the above lower limit, there is a risk that the appearance of the coating will change due to exposure to disinfectants, etc.

[0038] Regarding (3) above, if the ratio of calcium carbonate in the total amount of the body pigment exceeds the above upper limit, the appearance of the coating may be changed by disinfectants, etc. Regarding (3) above, in the present invention, an embodiment that does not contain calcium carbonate as an extender pigment is also preferable. Examples of such calcium carbonate include heavy calcium carbonate, light calcium carbonate, and porous calcium carbonate.

[0039] In the present invention, it is desirable that the body pigment further satisfies the following condition (4), which can provide more favorable effects overall in terms of reducing gloss, preventing uneven gloss, and preventing changes in the appearance of the coating caused by disinfectants, etc. (4) The extender pigment contains a high oil absorption extender pigment having an oil absorption of 100 ml / 100 g or more, and the proportion of the high oil absorption extender pigment in the total amount of the extender pigment is 50% by weight or less (preferably 45% by weight or less, more preferably 1 to 40% by weight, and even more preferably 2 to 35% by weight).

[0040] Regarding the above (4), various extender pigments can be used as the high oil absorption extender pigment having an oil absorption of 100 ml / 100 g or more (preferably 100 to 400 ml / 100 g, more preferably 105 to 350 ml / 100 g, and even more preferably 110 to 300 ml / 100 g) as long as they satisfy the above physical properties. Examples of high oil absorption extender pigments include zeolite, sodium sulfate, hydrated silicon dioxide, allophane, diatomaceous earth, siliceous shale, vermiculite, perlite, Oya stone powder, activated clay, activated carbon, and shirasu balloons. These can be used alone or in combination of two or more.

[0041] In addition to the above-mentioned components, various additives can be mixed into the coating material of the present invention. Examples of such additives include pigment dispersants, emulsifiers, viscosity regulators, film-forming assistants, leveling agents, coupling agents, wetting agents, plasticizers, antifreeze agents, pH adjusters, preservatives, antifungal agents, anti-algae agents, antibacterial agents, defoamers, adsorbents, deodorizers, UV absorbers, light stabilizers, antioxidants, catalysts, crosslinking agents, solvents, and water. Powders with large particle sizes (e.g., fillers and aggregates with an average particle size of more than 80 μm) are disadvantageous in flattening the coating and in terms of workability during cleaning (e.g., wiping workability), so it is desirable not to mix them.

[0042] The coating material of the present invention can be produced by uniformly mixing the above-mentioned resin emulsion, color pigment, extender pigment, and various additives, if necessary, in a conventional manner.

[0043] The coating material of the present invention is an aqueous material that contains water as a medium (i.e., contains an aqueous medium). The aqueous medium may contain a water-soluble solvent in addition to water, if necessary. Examples of the water-soluble solvent include alcohols, glycols, and glycol ethers.

[0044] The aqueous coating material of the present invention can be applied to, for example, surface finishing of the coated surface of buildings, civil engineering structures, etc. Examples of substrates constituting the coated surface include concrete, mortar, porcelain tile, fiber-mixed cement board, cement calcium silicate board, slag cement perlite board, cement board, ALC board, siding board, gypsum board, plywood, extrusion molding board, steel board, plastic board, etc. The surfaces of these substrates may be subjected to some surface treatment (for example, treatment with putty, sealer, surfacer, filler, etc.), may already have a coating film formed thereon, or may have wallpaper, etc., attached thereto.

[0045] When applying the coating material of the present invention, various application tools can be used, such as a spray, roller, brush, etc. Among these, as the roller, for example, a fibrous roller with short, medium or long hair (wool roller, etc.) can be used.

[0046] When applying, it is possible to dilute the coating material with water. The amount of water to be mixed may be appropriately determined taking into consideration the type of coating equipment, the condition of the surface to be coated, the temperature during application, etc., but is preferably about 0 to 20% by weight based on the total weight of the aqueous coating material.

[0047] The coating amount of the coating material of the present invention is preferably 0.1 to 0.8 kg / m 2 , more preferably 0.12 to 0.6 kg / m 2 , and more preferably 0.15 to 0.4 kg / m 2 By applying the water-based coating material in such an amount, it is possible to form a matte, flat, thin coating film with excellent color development, hiding power, etc.

[0048] The coating material of the present invention can be used as a room temperature drying aqueous coating material. Therefore, the coating material of the present invention can be applied or dried after application in an environment of room temperature (preferably 5 to 40°C). However, heating is also possible if necessary. The drying time is preferably about 0.5 to 4 hours at room temperature. The number of coats can be one or two or more (preferably one or two). When the number of coats is two or more, it is desirable that the total amount of coats is within the above range.

[0049] In the present invention, a coating with reduced gloss, that is, a matte coating, can be formed. The term "matte" as used herein includes what is generally called matte, as well as what is called 30% gloss, 50% gloss, etc. Specifically, the degree of matte can be determined by the specular gloss. The 60° specular gloss of the coating material of the present invention is preferably 50 or less, more preferably 0.1 to 30. Specifically, when a completely matte coating is formed by the coating material of the present invention, the 60° specular gloss can be 5 or less (preferably 0.1 to 4). When a 30% gloss coating is formed by the coating material of the present invention, the 60° specular gloss can be more than 5 and 30 or less (preferably 6 to 20).

[0050] The specular gloss is a value obtained by applying a coating material to one side of a glass plate using a film applicator with a gap of 150 μm, placing the coated surface horizontally, and drying it under standard conditions (temperature 23°C, relative humidity 50%) for 48 hours, and then measuring the specular gloss (measurement angle 60 degrees).

[0051] In the present invention, the change in appearance of the coating, such as discoloration and gloss change caused by a disinfectant or the like, can be suppressed. Therefore, the coating of the coating material of the present invention can be repeatedly cleaned with a disinfectant or the like. For cleaning with a disinfectant or the like, for example, a method of wiping the coating surface with a cloth containing a disinfectant or the like, a method of spraying a disinfectant or the like on the coating surface and then wiping it off with a cloth or the like can be adopted. Examples of the disinfectant or the like include an alcohol solution, hypochlorous acid water, a sodium hypochlorite aqueous solution, a surfactant aqueous solution, and a chlorous acid aqueous solution. These can be used alone or in combination, taking into consideration disinfection, sterilization, safety, and the like. After cleaning with a disinfectant or the like, wiping with water can also be performed as necessary. EXAMPLES

[0052] The following examples and comparative examples will be presented to clarify the features of the present invention, but the present invention is not limited to these examples.

[0053] (Production of water-based coating materials) Each aqueous coating material was produced by mixing and stirring the raw materials in a conventional manner in the parts by weight shown in Table 1. The following raw materials were used.

[0054] Resin 1: Acrylic resin emulsion (emulsion polymer of methyl methacrylate, styrene, n-butyl acrylate, 2-ethylhexyl acrylate, and acrylic acid, (meth)acrylic acid alkyl ester composition ratio 70% by weight, average particle size: 130 nm, solid content: 50% by weight, glass transition temperature: 5°C, resin specific gravity: 1.0, medium: water) Resin 2: Cross-linking reaction type acrylic resin emulsion (emulsion polymer of methyl methacrylate, styrene, n-butyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, and acrylic acid, (meth)acrylic acid alkyl ester composition ratio 75% by weight, average particle size: 140 nm, solid content: 50% by weight, glass transition temperature: 4°C, resin specific gravity: 1.0, medium: water) Crosslinker: Adipic dihydrazide ·Colored pigment 1: Chromatic pigment (Bengara, average particle size 0.2μm, specific gravity 5.0) Color pigment 2: Chromatic pigment (yellow iron oxide, average particle size 0.5 μm, specific gravity 4.0) Color pigment 3: Black pigment (carbon black, average particle size 0.1 μm, specific gravity 1.8) Color pigment 4: White pigment (titanium oxide, average particle size 0.2 μm, specific gravity 4.2) · Extender pigment 1: Talc (average particle size 12 μm, specific gravity 2.7, oil absorption 35 ml / 100 g) Extender pigment 2: Aluminum silicate (average particle size 4 μm, specific gravity 2.6, oil absorption 50 ml / 100 g) · Extender pigment 3: Silica powder (average particle size 4μm, specific gravity 2.6, oil absorption 10ml / 100g) Extender pigment 4: Heavy calcium carbonate (average particle size 4 μm, specific gravity 2.7, oil absorption 22 ml / 100 g) · Extender pigment 5: Diatomaceous earth (average particle size 10 μm, specific gravity 2.3, oil absorption 180 ml / 100 g) Extender pigment 6: Hydrous silicon dioxide (average particle size 4 μm, specific gravity 2.0, oil absorption 240 ml / 100 g) Dispersant: Anionic dispersant Coalescence agent: Ester-based coalescence agent Thickeners: Cellulose-based thickeners, urethane-based thickeners Defoamer: Silicone-based defoamer

[0055] (Test Method) Test 1 Each water-based coating material was applied to one side of a glass plate using a film applicator with a gap of 150 μm, and the coated surface was placed horizontally and dried for 48 hours under standard conditions (air temperature 23°C, relative humidity 50%) to prepare a test plate. The 60-degree specular gloss of this test plate was measured, and those with a specular gloss of 5 or less were rated as "I" (of these, those with a specular gloss of 0.1 to 4 were rated as "Ia"), and those with a specular gloss of more than 5 and less than 30 were rated as "II" (of these, those with a specular gloss of 6 to 20 were rated as "IIa").

[0056] Test 2 Each water-based coating material (5% diluted by weight) was applied to one side of the gypsum board using a wool roller at a rate of 0.2 kg / m 2 The test panels were painted with the same paint and dried for 48 hours. Painting and drying were performed under standard conditions. The resulting test panels were visually inspected for finish (degree of gloss unevenness) and rated on a 5-point scale (Excellent: AA>A>B>C>D: Poor), with "AA" being no gloss unevenness and "D" being significant gloss unevenness.

[0057] Test 3 A test plate was prepared in the same manner as in Test 1 above. An aqueous solution of ethanol was spotted on the coating surface of this test plate, then wiped off, and the degree of change in appearance (color, gloss) was evaluated. The evaluation was done on a 5-point scale (Excellent: AA>A>B>C>D: Poor), with "AA" being a rating for no change in appearance and "D" being a rating for a significant change in appearance.

[0058] Test 4 A test plate was prepared in the same manner as in Test 1 above. Hypochlorous acid water was spotted on the coating surface of this test plate, then wiped off, and the degree of change in appearance (color, gloss) was evaluated. The evaluation was performed on a 5-point scale (excellent: AA>A>B>C>D: poor), with "AA" being a rating for no change in appearance and "D" being a rating for a significant change in appearance.

[0059] (Test Results) The test results are shown in Table 1. In Examples 1 to 18, good results were obtained in each test.

[0060] [Table 1]

Claims

1. An aqueous coating material comprising a resin emulsion, a color pigment, and an extender pigment, The pigment volume concentration is 15 to 60%; The average particle size of the extender pigment is 80 μm or less, the content of the extender pigment is 20 to 400 parts by weight per 100 parts by weight of the solid content of the resin emulsion; The extender pigment includes a low oil absorption extender pigment having an oil absorption of less than 100 ml / 100 g, the ratio of the low oil absorption extender pigment to the total amount of the extender pigment is 50% by weight or more; The extender pigment includes a high oil absorption extender pigment having an oil absorption of 100 ml / 100 g or more, the ratio of the high oil absorption extender pigment to the total amount of the extender pigment is 1 to 50% by weight; The ratio of calcium carbonate to the total amount of the extender pigment is 20% by weight or less, The aqueous coating material is characterized in that the 60-degree specular gloss of the coating film of the aqueous coating material is more than 5 and 30 or less.

2. The aqueous coating material according to claim 1, characterized in that the high oil absorption body pigment is one or more selected from silica gel, zeolite, sodium sulfate, aluminum silicate, hydrous silicon dioxide, allophane, diatomaceous earth, siliceous shale, vermiculite, perlite, Oya stone powder, activated clay, activated carbon, and shirasu balloon.