JP2024080281A - Water-based coating material - Google Patents

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

The present invention relates to a new water-based coating material.

Traditionally, buildings and civil engineering structures have been coated with various coating materials for the purpose of protecting their surfaces and improving their aesthetics. Among these, matte coating materials are widely used because they can form a film with reduced surface gloss and provide a calm finish. In recent years, the coating field has seen a shift to water-based coatings in response to the movement to reduce the burden on the environment, and matte coating materials are no exception.

As an example of such a matte-type coating material, for example, Patent Document 1 (JP Patent Publication 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%.

JP 2002-201419 A

In recent years, the number of times that coating surfaces are cleaned using alcohol-based, acidic, or other disinfectants or sanitizing solutions (hereinafter referred to as "disinfectants, etc.") for the purpose of disinfecting and sterilizing the interior surfaces of buildings and the like has increased. However, when disinfectants, etc. are used on the coating of the above-mentioned aqueous coating material, the coating may discolor or lose its luster. In addition, if the disinfectant, etc. remains on the coating, the traces may become stains, etc., and the appearance of the coating may be damaged.

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

In order to solve these problems, the inventors conducted extensive research and came up with the idea of an aqueous coating material with a specific extender pigment composition, which led to the completion of the present invention.

That is, the present invention has the following features.
1. An aqueous coating material containing a resin emulsion, a color pigment, and an extender pigment,
The pigment volume concentration is 15 to 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 body pigment includes a low oil absorption body 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,
2. A water-based coating material comprising said body pigments, the proportion of calcium carbonate being 20% by weight or less.
2. The body pigment includes a high oil absorption body pigment having an oil absorption of 100 ml/100 g or more,
2. The water-based coating material according to 1., characterized in that the ratio of the high oil absorption body pigment to the total amount of the body pigment is 50% by weight or less.

The present invention 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, etc.

The following describes how to implement the present invention.

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

Of these, the resin emulsion is the component that acts as a binder. Resin emulsions are made by emulsifying and dispersing resin in an aqueous medium (a medium that contains water).

Examples of resins in the resin emulsion include vinyl acetate resin, vinyl chloride resin, epoxy resin, alkyd resin, acrylic resin, urethane resin, silicone resin, fluororesin, etc., or composites of these. These can be used alone or in combination of two or more types.

In the present invention, a preferred embodiment contains an acrylic resin emulsion as the resin emulsion. The acrylic resin emulsion is an aqueous dispersion of polymer particles whose main component is an alkyl (meth)acrylate ester. Such an acrylic resin emulsion can be obtained, for example, by emulsion polymerization of a monomer group containing an alkyl (meth)acrylate ester and, if necessary, other monomers, by a known method.

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 of two or more. 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" is synonymous with "a or more and b or less."

Examples of 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.

The acrylic resin emulsion may be any emulsion that satisfies the above conditions. Examples of acrylic resin emulsions that can be used include acrylic-styrene resin emulsions, epoxy-modified acrylic resin emulsions, urethane-modified acrylic resin emulsions, silicone-modified acrylic resin emulsions, and fluorine-modified acrylic resin emulsions.

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 even more preferably 80 to 250 nm. The average particle size of the resin emulsion is a value measured by dynamic light scattering. Specifically, it can be measured using a dynamic light scattering measuring device (measurement temperature: 25°C).

The glass transition temperature of the resin that constitutes the resin emulsion is preferably -30 to 60°C, and more preferably -20 to 40°C. This glass transition temperature can be calculated using the Fox formula.

The resin emulsion of the present invention can be produced, for example, by a one-stage or multi-stage (two-stage, three-stage or more) emulsion polymerization method. When multi-stage emulsion polymerization is used, for example, a multi-layer structure type emulsion (such as a core-shell type emulsion) can be obtained.

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

The crosslinking agent may be, for example, one that contains 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., a resin emulsion having, for example, a carboxyl group may be used. When the crosslinking agent has a hydrazide group, a resin emulsion having, for example, a carbonyl group may be used.

Examples of crosslinking agents containing epoxy groups include polyethylene glycol diglycidyl ether, polyhydroxyalkane polyglycidyl ether, diglycerol polyglycidyl ether, and sorbitol polyglycidyl ether.

Examples of crosslinking agents containing carbodiimide groups 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.

Examples of crosslinking agents containing oxazoline groups include resins obtained by copolymerizing polymerizable oxazoline compounds such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-isopropenyl-2-oxazoline with monomers that are copolymerizable with the compounds.

Examples of crosslinking agents containing hydrazide groups include malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, and maleic acid dihydrazide.

The content of the crosslinking agent is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight, calculated as solid content, per 100 parts by weight of the solid content of the resin emulsion.

Color pigments are components that impart a desired color to the coating material. Examples of color pigments 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 the average value measured using a laser diffraction particle size distribution measuring device (measurement temperature: 25°C).

The content of the color pigment is preferably 1 to 500 parts by weight, more preferably 5 to 300 parts by weight, and even more preferably 10 to 200 parts by weight, per 100 parts by weight of the solid content of the resin emulsion. If the content of the color pigment is within this range, it is favorable 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.

In the present invention, the pigment includes 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 body pigments 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 balloons. 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, the finish, and ease of cleaning with disinfectants, etc. (e.g., ease of wiping).

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 changes in gloss 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 make up the coating material. The specific gravity of the resin is set to 1.
Specifically, in a completely matte coating, the pigment volume concentration can be set to preferably 35 to 55% (more preferably 36 to 50%), and 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%).

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).

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.

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

Regarding (2) above, various extender pigments can be used as low oil absorption extender pigments 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.

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

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

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

In the present invention, it is preferable that the body pigment further satisfies the following condition (4), which can provide more favorable effects overall in terms of reducing gloss, suppressing uneven gloss, and suppressing 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).

Regarding (4) above, various extender pigments can be used as high oil absorption extender pigments 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.

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 aids, 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, aggregates, etc. with an average particle size of more than 80 μm) are detrimental to the flattening of the coating and are also detrimental to workability during cleaning (e.g., wiping workability), so it is desirable not to mix them.

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

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

The aqueous coating material of the present invention can be applied to, for example, surface finishing of the surfaces to be coated, such as buildings and civil engineering structures. Examples of substrates that constitute the surfaces to be coated include concrete, mortar, porcelain tiles, fiber-mixed cement boards, cement calcium silicate boards, slag cement perlite boards, cement boards, ALC boards, siding boards, gypsum boards, plywood, extrusion molding boards, steel boards, plastic boards, etc. The surfaces of these substrates may be ones that have been subjected to some kind of surface treatment (e.g., treatment with putty, sealer, surfacer, filler, etc.), ones that already have a coating film formed, ones that have wallpaper, etc., attached, etc.

When applying the coating material of the present invention, various application tools such as sprays, rollers, brushes, etc. can be used. Among these, rollers that can be used include, for example, short-, medium-, or long-haired fibrous rollers (wool rollers, etc.).

When applying, it is possible to dilute the coating with water. The amount of water to be mixed can be set appropriately taking into consideration the type of coating equipment, the condition of the surface to be coated, the temperature during application, etc., but it is preferably about 0 to 20% by weight of the entire water-based coating material.

The coating material of the present invention is preferably applied in an amount of 0.1 to 0.8 kg/m ² , more preferably 0.12 to 0.6 kg/m ² , and even more preferably 0.15 to 0.4 kg/m ^2. By applying the aqueous coating material in such an amount, it is possible to form a matte, flat, thin coating having excellent color development, hiding power, etc.

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 coating be within the above range.

In the present invention, a coating with reduced gloss, that is, a matte coating, can be formed. Note that "matte" as used here 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-degree 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 using the coating material of the present invention, the 60-degree specular gloss can be 5 or less (preferably 0.1 to 4). When a 30% gloss coating is formed using the coating material of the present invention, the 60-degree specular gloss can be more than 5 and 30 or less (preferably 6 to 20).

The specular gloss is a value obtained by applying the 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 then drying for 48 hours under standard conditions (air temperature 23°C, relative humidity 50%), and then measuring the specular gloss (measurement angle 60 degrees).

In the present invention, it is possible to suppress changes in appearance such as discoloration and gloss of the coating caused by a disinfectant or the like. Therefore, the coating of the coating material of the present invention can be repeatedly cleaned with a disinfectant or the like. For example, cleaning with a disinfectant or the like can be performed by wiping the surface of the coating with a cloth containing the disinfectant or the like, or by spraying the disinfectant or the like on the surface of the coating and then wiping it off with a cloth or the like. Examples of disinfectants or the like include alcohol solutions, hypochlorous acid water, sodium hypochlorite aqueous solutions, surfactant aqueous solutions, and hypochlorous acid water. These can be used alone or in combination of two or more types, taking into consideration disinfection properties, sterilization properties, safety, and the like. After cleaning with a disinfectant or the like, wiping with water can also be performed as necessary.

The following examples and comparative examples will be presented to clarify the features of the present invention. Note that the present invention is not limited to these examples.

(Production of Water-Based Coating Materials)
Each aqueous coating material was produced by mixing and stirring the raw materials in the weight parts shown in Table 1 in a conventional manner. The raw materials used were as follows.

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)
Crosslinking agent: adipic dihydrazide Coloring pigment 1: chromatic pigment (red oxide, average particle size 0.2 μm, 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 4 μm, specific gravity 2.6, oil absorption 10 ml/100 g)
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 Film-forming aid: Ester film-forming aid Thickener: Cellulose thickener, urethane thickener Defoamer: Silicone defoamer

(Test method)
Test 1
Each aqueous 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 which, 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 30 or less were rated as "II" (of which, those with a specular gloss of 6 to 20 were rated as "IIa").

Test 2
Each aqueous coating material (diluted by 5% by weight) was applied to one side of a gypsum board using a wool roller at a coating amount of 0.2 kg/ ^m2 , and the board was dried for 48 hours to prepare a test board. The painting and drying were performed under standard conditions. The resulting test boards 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" indicating no gloss unevenness and "D" indicating significant gloss unevenness.

Test 3
A test plate was prepared in the same manner as in Test 1. An aqueous solution of ethanol was spotted on the coating surface of this test plate, and then the surface was 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.

Test 4
A test plate was prepared in the same manner as in Test 1. Hypochlorous acid water was spotted on the coating surface of this test plate, and 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 the one where no change in appearance was observed and "D" being the one where a significant change in appearance was observed.

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

Claims (2)

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 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 body pigment includes a low oil absorption body 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,
2. A water-based coating material comprising said body pigments, the proportion of calcium carbonate being 20% by weight or less. The body pigment includes a high oil absorption body pigment having an oil absorption of 100 ml/100 g or more,
2. The aqueous coating material according to claim 1, wherein the ratio of said high oil absorption body pigment to the total amount of said body pigments is 50% by weight or less.