JP2022185765A - Aqueous coating - Google Patents

Abstract

To provide an aqueous coating that forms a coat with reduced gloss while suppressing changes in the appearance of the coat due to a disinfectant or the like such as discoloration and change of gloss.SOLUTION: An aqueous coating contains a resin emulsion, a coloring pigment, and an extender pigment. The pigment concentration by volume is 20-60%. The content of the extender pigment is 20-400 pts.wt. relative to the solid content of 100 pts.wt. of the resin emulsion. The extender pigment includes a low-oil-absorption extender pigment with an oil absorbency of less than 100 ml/100 g. In the total amount of the extender pigment, the proportion of the low-oil-absorption extender pigment is 50 wt.% or more. In the total amount of the extender pigment, the proportion of calcium carbonate is 20 wt.% or less.SELECTED DRAWING: None

Description

The present invention relates to novel aqueous coatings.

2. Description of the Related Art Conventionally, buildings, civil engineering structures, and the like are coated with various coating materials for the purpose of surface protection, aesthetic improvement, and the like. Among these, matte-type coating materials are generally used because they can form a coating with a reduced gloss on the surface and provide a calm finish. In recent years, in the field of coatings, the use of water-based coatings has been progressing against the background of the movement to reduce the load on the environment, and matte-type coating materials are no exception.

As an example of such a matte-type coating material, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-201419) contains a coating film-forming resin, a coloring pigment, and an extender pigment such as heavy calcium carbonate, Aqueous coatings are described with pigment volume concentrations of 20-60%.

Japanese Patent Application Laid-Open No. 2002-201419

By the way, in recent years, for the purpose of disinfection and sterilization, etc. on the interior surfaces of buildings, etc., alcohol-based, acid-based disinfectants and sterilization solutions (hereinafter referred to as "disinfectants, etc.") are used to clean the film surface. Opportunities for transformation are increasing. However, when an antiseptic solution or the like is used for the film of the water-based coating material as described above, the film may be discolored or its luster may be changed. In addition, if the disinfectant solution or the like remains on the film, there is a risk that the traces of the disinfectant or the like will become stains and the like, impairing the appearance of the film.

The present invention has been made in view of such points, and is an aqueous coating material that can suppress appearance changes such as discoloration and gloss change of the coating due to disinfectants etc. while forming a coating with reduced luster. It is intended to provide

In order to solve such problems, the present inventors have made intensive studies, and as a result, have conceived of an aqueous coating material having a specific extender composition, etc., and completed the present invention.

That is, the present invention has the following features.
1. An aqueous coating comprising a resin emulsion, a colored pigment, and an extender,
Pigment volume concentration is 20 to 60%,
The content of the extender pigment is 20 to 400 parts by weight with respect to 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 proportion of the low oil absorption extender pigment in the total amount of the extender pigment is 50% by weight or more,
A water-based coating material characterized in that the ratio of calcium carbonate in the total amount of the extender pigment is 20% by weight or less.
2. As the extender pigment, a high oil absorption extender pigment having an oil absorption of 100 ml/100 g or more is included,
1. The high oil absorption extender pigment accounts for 50% by weight or less of the total amount of the extender pigment. Aqueous dressings as described.

According to the present invention, it is possible to suppress appearance changes such as discoloration and gloss change of the coating caused by a disinfectant solution or the like while forming a coating with reduced luster.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated.

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.

Among these, the resin emulsion is a component that acts as a binder. A resin emulsion is obtained by emulsifying and dispersing a resin in an aqueous medium (medium containing water).

Examples of resins in the resin emulsion include vinyl acetate resins, vinyl chloride resins, epoxy resins, alkyd resins, acrylic resins, urethane resins, silicon resins, fluorine resins, and composites thereof. These can be used singly or in combination of two or more.

In the present invention, it is preferable that the resin emulsion contains an acrylic resin emulsion. An acrylic resin emulsion is an aqueous dispersion of polymer particles containing (meth)acrylic acid alkyl ester as a main component. Such an acrylic resin emulsion can be obtained, for example, by emulsion polymerization of a monomer group containing a (meth)acrylic acid alkyl ester and optionally 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, and 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, benzyl (meth)acrylate and the like. These can be used singly or in combination of two or more. The composition ratio of such (meth)acrylic acid alkyl ester is preferably 30% by weight or more, more preferably 40 to 99.9% by weight, and still more preferably 50 to 99.5% by weight, based on the total monomers constituting the resin. % by weight. In the present invention, alkyl acrylate and alkyl methacrylate are collectively referred to as alkyl (meth)acrylate. 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, and alkoxysilyl group-containing monomers. , aromatic monomers, and the like. These can be used singly 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.

Any acrylic resin emulsion may be used as long as it 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, silicon-modified acrylic resin emulsions, and fluorine-modified acrylic resin emulsions.

The average particle size of the resin emulsion in the present invention is preferably 50-500 nm, more preferably 70-300 nm, still more preferably 80-250 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 measurement device (measurement temperature is 25°C).

The glass transition temperature of the resin constituting the resin emulsion is preferably -30 to 60°C, more preferably -20 to 40°C. The glass transition temperature can be determined by the Fox calculation formula.

The resin emulsion in the present invention can be produced, for example, by a one-step or multi-step (two-step, or three-step or more) emulsion polymerization method. Among them, when multi-stage emulsion polymerization is employed, for example, a multi-layer structure emulsion (core-shell emulsion, etc.) can be obtained.

In the present invention, a cross-linkable resin emulsion can also be used as the resin emulsion. Crosslinking reactions in crosslinkable resin emulsions include, for example, 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, and carbonyl groups. 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. Of these, preferred cross-linking reactions include carboxyl group and epoxy group, carboxyl group and carbodiimide group, carboxyl group and oxazoline group, carbonyl group and hydrazide group, and hydrolyzable silyl groups. As such a crosslinkable resin emulsion, for example, one that causes a crosslink reaction between the functional groups in the emulsion particles, or one that causes a crosslink reaction between the separately mixed crosslinker and the functional groups in the emulsion particles is used. can. These may be either one-liquid type, two-liquid type, or the like.

As the cross-linking agent, for example, one containing a compound having one or more reactive functional groups selected from an epoxy group, a carbodiimide group, an oxazoline group, a hydrazide group and the like can be used. When the cross-linking agent has one or more reactive functional groups selected from epoxy groups, carbodiimide groups, and oxazoline groups, resin emulsions having carboxyl groups, for example, can be used. When the cross-linking agent has a hydrazide group, a resin emulsion having, for example, a carbonyl group can be used.

Examples of cross-linking agents containing epoxy groups include polyethylene glycol diglycidyl ether, polyhydroxyalkane polyglycidyl ether, diglycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like.

As a cross-linking agent containing a carbodiimide group, for example, JP-A-10-60272, JP-A-10-316930, JP-A-11-60667, JP-A-2016-196612, JP-A-2016-196613 , Japanese Patent Application Laid-Open Nos. 2018-104605 and 2019-038960.

Cross-linking agents containing an oxazoline group include, for example, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2- Examples thereof include resins obtained by copolymerizing a polymerizable oxazoline compound such as oxazoline with a monomer copolymerizable with the compound.

Examples of cross-linking agents containing a hydrazide group include malonic dihydrazide, succinic dihydrazide, glutaric dihydrazide, adipic dihydrazide, sebacic dihydrazide, and maleic dihydrazide.

The content of the cross-linking agent is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight in terms of solid content, with respect to 100 parts by weight of the solid content of the resin emulsion.

Color pigments are components that impart the desired color to the coating. Examples of coloring pigments include inorganic chromatic pigments such as ferric oxide (rouge), yellow iron oxide, ultramarine blue, and cobalt green; azo, naphthol, pyrazolone, anthraquinone, perylene, quinacridone, disazo organic chromatic pigments such as pigments, isoindolinone-based, benzimidazole-based, phthalocyanine-based, quinophthalone-based; 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, black iron oxide and other black pigments; titanium oxide, zinc oxide, alumina and other white pigments; other pearl pigments, aluminum pigments, luster pigments, phosphorescent pigments , fluorescent pigments, and the like. These can be used singly or in combination of two or more. The average particle size of the color pigment is preferably less than 1 μm, more preferably 0.01-0.9 μm. In the present invention, the average particle size of the pigment is an average value measured using a laser diffraction particle size distribution analyzer (measured at 25°C).

The content of the color pigment is preferably 1 to 500 parts by weight, more preferably 5 to 300 parts by weight, still more 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 coloring pigment is within such a range, it is preferable in terms of the coating's color developability, concealability, etc., and it is also advantageous in terms of exhibiting the effect of the present invention.

In the present invention, pigments include extender pigments in addition to the above-described coloring pigments. This makes it possible to reduce the luster of the film surface and impart a calm finish. Extender pigments include, for example, kaolin, clay, aluminum silicate, calcined clay, calcined kaolin, pottery clay, china clay, diatomaceous earth, hydrous fine silicic acid, silica gel, zeolite, sodium sulfate, allophane, talc, mica, barite powder, barium sulfate, Precipitated barium sulfate, barium carbonate, magnesium carbonate, silica powder, aluminum hydroxide, ground calcium carbonate, trace calcium carbonate, porous calcium carbonate, siliceous shale, vermiculite, perlite, Oya stone powder, activated clay, activated carbon, shirasu A balloon etc. are mentioned. These can be used singly or in combination of two or more. The average particle size of the extender pigment is preferably 1-100 μm, more preferably 2-50 μm.

In the coating material of the present invention, these pigments (coloring pigments and extender pigments) are mixed within the range of pigment volume concentration of 20 to 60% (preferably 30 to 55%, more preferably 35 to 50%). By setting the pigment volume concentration within such a range, it is possible to obtain the effects of the present invention. If the pigment volume concentration is less than the above lower limit, it is difficult to obtain the gloss reduction effect, etc., and if it exceeds the above upper limit, it is difficult to suppress appearance changes such as discoloration and gloss change of the coating due to disinfectant etc. Become. The pigment volume concentration is the volume percentage of the pigment contained in the dry film, and is a value obtained by calculation from the mixed amount of the resin and pigment constituting the coating material. Note that the specific gravity of the resin is 1.

The present invention is characterized in that the extender satisfies the following conditions (1), (2) and (3). As a result, it is possible to suppress appearance changes such as discoloration and gloss change of the coating due to the disinfectant solution or the like while forming a coating with reduced luster.
(1) The content of the extender pigment is 20 to 400 parts by weight (preferably 40 to 300 parts by weight, more preferably 60 to 200 parts by weight) per 100 parts by weight of the solid content of the resin emulsion.
(2) As an extender pigment, a low oil absorption extender pigment having an oil absorption of less than 100 ml/100 g is included, 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 to 95% by weight, more preferably 60 to 90% by weight, still more preferably 65 to 85% by weight).
(3) The proportion of calcium carbonate in the total amount of the extender is 20% by weight or less (preferably 10% by weight or less, more preferably 3% by weight or less).

The reasons why the effect of the present invention is exhibited by providing the above conditions (1) to (3) are not limited to the following, but the extender pigment causes fine unevenness on the surface of the coating, It is considered that the suppression of permeation of the antiseptic solution or the like into the interior, the sufficient resistance of the coating to the antiseptic solution or the like, and the like contribute to this.

Regarding (1) above, if the content of the extender pigment is less than the above lower limit, the reduction in luster will be insufficient, and 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. be.

Regarding the above (2), the oil absorption is 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, still more preferably 25 to 85 ml/100 g, particularly preferably 30 to 80 ml/100 g ), various extender pigments can be used as long as the above physical properties are satisfied. Examples of low oil absorption extender pigments include kaolin, clay, aluminum silicate, calcined clay, calcined kaolin, porcelain clay, china clay, talc, barite powder, barium sulfate, silica powder, aluminum hydroxide, calcium carbonate and the like. These can be used singly 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 in ml of boiled linseed oil per 100g of pigment.

Regarding (2) above, if the ratio of the low oil absorption extender to the total amount of the extender is less than the above lower limit, there is a possibility that the appearance of the film may be changed by the disinfectant or the like.

Regarding (3) above, if the ratio of calcium carbonate in the total amount of the extender exceeds the above upper limit, there is a risk that the appearance of the film will change due to the disinfectant or the like. With regard to (3) above, in the present invention, an aspect in which calcium carbonate is not included as an extender pigment is also suitable. Examples of such calcium carbonate include heavy calcium carbonate, microcalcium carbonate, and porous calcium carbonate.

In the present invention, it is desirable that the extender further satisfies the following condition (4). As a result, overall more favorable effects can be exhibited in terms of reduction in luster, suppression of changes in the appearance of the film caused by disinfectant or the like, and the like.
(4) As an extender pigment, a high oil absorption extender pigment having an oil absorption of 100 ml/100 g or more is included, and the ratio of the high oil absorption extender pigment to the total amount of the extender pigment is 50% by weight or less (preferably 5 to 45% by weight, more preferably 10 to 40% by weight, still more preferably 15 to 35% by weight).

Regarding the above (4), 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 300 ml/100 g, still more preferably 110 to 250 ml/100 g) has the physical properties Various extender pigments can be used as long as they satisfy Examples of highly oil-absorbing bulk pigments include silica gel, zeolite, sodium sulfate, aluminum silicate, allophane, diatomaceous earth, siliceous shale, vermiculite, perlite, Oya stone powder, activated clay, activated carbon, and shirasu balloon. These can be used singly or in combination of two or more.

In the coating material of the present invention, various additives can be mixed in addition to the above components. Examples of such additives include pigment dispersants, emulsifiers, viscosity modifiers, film-forming aids, leveling agents, coupling agents, wetting agents, plasticizers, antifreeze agents, pH adjusters, preservatives, antiseptics. Mildew agents, anti-algae agents, antibacterial agents, defoaming agents, adsorbents, deodorants, ultraviolet absorbers, light stabilizers, antioxidants, catalysts, cross-linking agents, solvents, water and the like. Granules with a large particle size (for example, fillers with an average particle size of 80 μm or more, aggregates, etc.) are disadvantageous in flattening the coating, so it is desirable not to mix them.

The coating material of the present invention can be produced by uniformly mixing the above resin emulsion, color pigment, extender pigment, and, if necessary, various additives by a conventional method.

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

The water-based coating material of the present invention can be applied, for example, to surface finishing of surfaces to be coated such as buildings and civil engineering structures. Substrates constituting the surface to be coated include, for example, 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, and extrusion. Molded plates, steel plates, plastic plates and the like can be used. The surface of these substrates may be subjected to some surface treatment (for example, treatment with putty, sealer, surfacer, filler, etc.), and those with a coating film already formed, or those with wallpaper or the like attached. etc.

When coating the coating material of the present invention, for example, various coating tools such as sprays, rollers and brushes can be used. Among these, as the roller, for example, a fibrous roller (wool roller, etc.) with short hair, medium hair, or long hair can be used.

It is also possible to dilute with water when applying. The amount of water to be mixed may be appropriately set in consideration of the type of coating equipment, the state of the surface to be coated, the temperature at the time of coating, etc., but it is preferably about 0 to 20% by weight with respect to the entire water-based coating material. .

The coating amount of the coating material of the present invention is preferably 0.1-0.8 kg/m ² , more preferably 0.12-0.6 kg/m ² , still more preferably 0.15-0.4 kg/m ² . is. By applying the water-based coating material in such a coating amount, it is possible to form a matte, flat and thin coating which is excellent in color developability, concealability and the like.

The coating material of the present invention can be used as a room-temperature-drying water-based coating material. Therefore, the coating or drying after coating of the coating material of the present invention can be carried out in an environment of normal temperature (preferably 5 to 40° C.). However, it is also possible to heat if necessary. The drying time is preferably about 0.5 to 4 hours at room temperature. The number of coatings can be one or two or more (preferably one to two). When the number of coatings is two or more, it is desirable that the total coating amount is within the above range.

The present invention can form a coating with reduced gloss, ie, a matte coating. The term "matte" as used herein includes not only what is generally called matte, but also what is called 30% gloss, 50% gloss, and the like. Specifically, the degree of matting can be defined by the degree of specular gloss. The 60-degree specular glossiness of the coating material of the present invention is preferably 40 or less, more preferably 20 or less, still more preferably 0.1-10. When a completely matte coating is formed from the coating material of the present invention, the 60 degree specular glossiness is preferably 8 or less, more preferably 6 or less, still more preferably 5 or less, and particularly preferably 0.1 to 4. , the 85-degree specular gloss is preferably 8 or less, more preferably 6 or less, even more preferably 5 or less, and particularly preferably 0.1 to 4.

The specular glossiness was measured by applying a coating material to one side of the glass plate using a film applicator with a gap of 150 μm, placing the coated surface horizontally and drying for 48 hours under standard conditions (temperature 23 ° C., relative humidity 50%). It is a value obtained by measuring the specular glossiness (measurement angle of 60 degrees or 85 degrees) when

In the present invention, it is possible to suppress appearance changes such as discoloration and change in luster of the film due to disinfectant or the like. Therefore, the coating of the dressing of the present invention can be repeatedly cleaned with an antiseptic solution or the like. For cleaning with an antiseptic solution or the like, for example, a method of wiping the film surface with a cloth containing an antiseptic solution or the like, a method of spraying the antiseptic solution or the like on the film surface and wiping it off with a cloth, etc. can be adopted. Examples of the disinfectant include alcohol solution, hypochlorous acid water, sodium hypochlorite aqueous solution, surfactant aqueous solution, chlorous acid water, and the like. These can be used singly or in combination of two or more in consideration of disinfection, sterilization, safety and the like. After cleaning with an antiseptic solution or the like, wiping with water or the like can be performed as necessary.

Examples and comparative examples are shown below to further clarify the features of the present invention. It should be noted that the invention is not limited to the examples herein.

(Manufacture of water-based coating material)
Each water-based coating material was produced by mixing and stirring each raw material in the parts by weight shown in Table 1 by a conventional method. The following materials were used as raw materials.

・Resin 1: acrylic resin emulsion (methyl methacrylate, styrene, n-butyl acrylate, 2-ethylhexyl acrylate, emulsion polymer of acrylic acid, composition ratio of (meth)acrylic acid alkyl ester: 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: Crosslinking reaction type acrylic resin emulsion (methyl methacrylate, styrene, n-butyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, emulsion polymer of acrylic acid, composition ratio of (meth)acrylic acid alkyl ester: 75% by weight , average particle diameter: 140 nm, solid content: 50% by weight, glass transition temperature: 4 ° C., resin specific gravity: 1.0, medium: water)
・Crosslinking agent: adipic acid dihydrazide ・Coloring pigment 1: Chromatic pigment (rouge, average particle size 0.2 μm, specific gravity 5.0)
Coloring pigment 2: Chromatic pigment (yellow iron oxide, average particle size 0.5 μm, specific gravity 4.0)
Coloring pigment 3: black pigment (carbon black, average particle size 0.1 μm, specific gravity 1.8)
- Coloring 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)
・Dispersant: Anionic dispersant ・Coating agent: Ester-based cohesive agent ・Thickener: Cellulose-based thickener, urethane-based thickener ・Anti-foaming agent: Silicone anti-foaming agent

(Test method)
○ Test 1
Each water-based coating material is applied to one side of a glass plate using a film applicator with a gap of 150 μm, and the coated surface is placed horizontally and dried for 48 hours under standard conditions (temperature of 23 ° C and relative humidity of 50%) to form a test plate. made. The 60-degree specular gloss of this test plate was measured. The evaluation criteria are "AA" for specular glossiness of 4 or less, "A" for over 4 to 5 or less, "B" for over 5 to 6 or less, "C" for over 6 to 8 or less, and "D" for over 8. did.

○Test 2
The 85-degree specular glossiness of the test plate obtained in Test 1 was measured. The evaluation criteria are "AA" for specular glossiness of 4 or less, "A" for over 4 to 5 or less, "B" for over 5 to 6 or less, "C" for over 6 to 8 or less, and "D" for over 8. did.

○Test 3
A test plate was prepared in the same manner as in Test 1 above. An ethanol aqueous solution was spotted on the film surface of this test plate, and then wiped off, and the degree of change in appearance (color, luster) was evaluated. The evaluation was performed on a 5-point scale (excellent: AA>A>B>C>D: poor), with "AA" indicating no change in appearance and "D" indicating significant change in appearance. .

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

(Test results)
Table 1 shows the test results. In Examples 1-13, good results were obtained in each test.

Claims (2)

An aqueous coating comprising a resin emulsion, a colored pigment, and an extender,
Pigment volume concentration is 20 to 60%,
The content of the extender pigment is 20 to 400 parts by weight with respect to 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 proportion of the low oil absorption extender pigment in the total amount of the extender pigment is 50% by weight or more,
A water-based coating material characterized in that the ratio of calcium carbonate in the total amount of the extender pigment is 20% by weight or less. As the extender pigment, a high oil absorption extender pigment having an oil absorption of 100 ml/100 g or more is included,
2. The water-based coating material according to claim 1, wherein the proportion of said high oil absorption extender pigment is 50% by weight or less in the total amount of said extender pigment.