Water-based coating material

Abstract

To provide an aqueous coating material which can suppress discoloration of a film due to moisture and other external factors while forming a film having reduced gloss.SOLUTION: An aqueous coating material, which contains pigment volume concentration of 30-70%, and is coated onto the surfaces of a building and a civil engineering structure, contains acrylic resin emulsion (A), a coloring pigment (B) and scaly powder (C) as an extender pigment, and contains a chromatic color pigment, a black pigment and a white pigment as the coloring pigment (B) under a specific condition, wherein the scaly powder (C) is one or two or more selected from talc and clay, and 310 pts.wt. or more and 1,200 pts.wt. or less of the scaly powder (C) is contained with respect to 100 pts.wt. of the coloring pigment (B).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novel aqueous coating material.

Background Art

[0002] Conventionally, in buildings, civil engineering structures, etc., coating is performed with various coating materials for the purposes of surface protection, improvement of aesthetics, etc. Among these, matte-type coating materials can form a film with reduced gloss on the surface and can provide a calm finish, so they are widely used. In recent years, in the coating field, with the background of movements to reduce the environmental load, etc., water-based conversion has been progressing, and matte-type coating materials are no exception.

[0003] As an example of such a matte-type coating material, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-201419) describes an aqueous coating material containing a film-forming resin such as a water-dispersible resin, a coloring pigment such as carbon black or red iron oxide, and an extender pigment such as heavy calcium carbonate, and having a pigment volume concentration of 20 to 60%.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above-mentioned aqueous coating material, when water comes into contact with the film, there is a risk that the water is absorbed and the film may discolor. On the other hand, there is also a risk that the surface of the film is scratched by external factors such as pressure, friction, and flying objects, and the original color tone may be impaired.

[0006] The present invention has been made in view of such points, and an object thereof is to provide an aqueous coating material capable of forming a coating film with reduced gloss and suppressing discoloration of the coating film due to moisture and other external factors.

Means for Solving the Problems

[0007] In order to solve such problems, as a result of intensive studies, the present inventor has conceived an aqueous coating material containing an acrylic resin emulsion (A), a coloring pigment (B), and a flaky powder (C) as a extender pigment, and the ratio of the flaky powder (C) to the coloring pigment (B) is a specific weight ratio, and has completed the present invention.

[0008] That is, the present invention has the following features. 1. An aqueous coating material having a pigment volume concentration of 30 to 70% and being applied to the surface of a building or a civil engineering structure, containing an acrylic resin emulsion (A), a coloring pigment (B), and a flaky powder (C) as a extender pigment, wherein the coloring pigment (B) contains a chromatic pigment and / or a black pigment, the total volume ratio of the chromatic pigment and the black pigment is 5% by volume or more in the total volume of the coloring pigment (B), the coloring pigment (B) does not contain a white pigment, or when containing a white pigment, the mixing ratio of the white pigment is at most 10 parts by weight out of 100 parts by weight of the coloring pigment (B), the flaky powder (C) is one or more selected from talc and clay, an aqueous coating material characterized by containing 346 parts by weight or more 1200 parts by weight or less of the flaky powder (C) with respect to 100 parts by weight of the coloring pigment (B). 2. The aqueous coating material according to 1., wherein the white pigment is one or more selected from titanium oxide, zinc oxide, and alumina.

Effects of the Invention

[0009] According to the present invention, it is possible to form a film with reduced gloss while suppressing discoloration of the film due to moisture and other external factors.

Mode for Carrying Out the Invention

[0010] Hereinafter, modes for carrying out the present invention will be described.

[0011] The aqueous coating material of the present invention (hereinafter also simply referred to as "coating material") contains an acrylic resin emulsion (A), a coloring pigment (B), and flaky powder (C) as a extender pigment.

[0012] The acrylic resin emulsion (A) (hereinafter also referred to as "(A) component") is a component that mainly acts as a binder. The acrylic resin emulsion (A) is an aqueous dispersion of polymer particles mainly composed of (meth)acrylic acid alkyl esters. Such (A) component can be obtained, for example, by emulsion polymerization of a monomer group containing (meth)acrylic acid alkyl esters and other monomers as necessary by a known method.

[0013] Examples of the (meth)acrylic acid alkyl ester 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, benzyl (meth)acrylate, etc. These can be used alone 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, still more preferably 50 to 99.5% by weight based on all the monomers constituting the component (A). In the present invention, the acrylic acid alkyl ester and the methacrylic acid alkyl ester are collectively referred to as (meth)acrylic acid alkyl ester. Also, in the present invention, "a to b" is synonymous with "a or more and b or less".

[0014] 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, aromatic monomers, etc. 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 all the monomers constituting the component (A).

[0015] (Component (A) may be any one that satisfies the above conditions. As component (A), for example, an acrylic styrene resin emulsion, an epoxy-modified acrylic resin emulsion, a urethane-modified acrylic resin emulsion, a silicone-modified acrylic resin emulsion, a fluorine-modified acrylic resin emulsion, etc. can also be used. Further, the form of component (A) may be, for example, a multilayer structured emulsion (core-shell type emulsion) obtained by multi-stage polymerization, or a cross-linking reaction type emulsion that causes a cross-linking reaction, etc. Examples of the cross-linking reaction type emulsion include those in which a cross-linking reaction occurs between functional groups in the emulsion particles, or those in which a cross-linking agent separately mixed and functional groups in the emulsion particles cause a cross-linking reaction.)

[0016] (The average particle diameter of component (A) is preferably 50 to 500 nm, more preferably 70 to 300 nm, still more preferably 80 to 250 nm, and particularly preferably 85 to 200 nm. In the present invention, the average particle diameter is a value measured by the dynamic light scattering method. Specifically, it can be measured using a dynamic light scattering measuring device (such as "LB-550" manufactured by Horiba, Ltd.) (the measurement temperature is 25°C).)

[0017] (The glass transition temperature of component (A) is preferably -30 to 60°C, more preferably -20 to 40°C. This glass transition temperature can be obtained by Fox's calculation formula.)

[0018] (The mixing ratio of component (A) is preferably 10 to 2000 parts by weight, more preferably 50 to 1000 parts by weight, and still more preferably 100 to 600 parts by weight with respect to 100 parts by weight of the coloring pigment (B) in terms of solid content. If component (A) has such a mixing ratio, the effects of the present invention can be sufficiently obtained. In particular, when the lower limit of the mixing ratio of component (A) is the above value, it is suitable in terms of suppressing discoloration of the coating film, preventing desorption of the coloring pigment from the coating film (preventing color transfer), durability of the coating film, etc. When the upper limit of the mixing ratio of component (A) is the above value, it is suitable in terms of color development property, hiding property, etc. of the coating film.)

[0019] The coloring pigment (B) (hereinafter also referred to as the “component (B)”) is a component that imparts a desired color. Examples of the component (B) include inorganic colored pigments such as ferric oxide (red iron oxide), yellow iron oxide, ultramarine, cobalt green, etc.; organic colored pigments such as azo-based, naphthol-based, pyrazolone-based, anthraquinone-based, perylene-based, quinacridone-based, disazo-based, isoindolinone-based, benzimidazole-based, phthalocyanine-based, quinophthalone-based, etc.; 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, black iron oxide, etc.; white pigments such as titanium oxide, zinc oxide, alumina, etc.; and other pearl pigments, aluminum pigments, bright pigments, phosphorescent pigments, fluorescent pigments, etc. These can be used alone or in combination of two or more. The average particle size of the component (B) is preferably less than 1 μm, more preferably 0.01 to 0.9 μm.

[0020] In the present invention, it is desirable that the coloring pigment (B) contains a colored pigment and / or a black pigment. Thereby, while imparting a rich color with high chroma and / or low lightness, the effects of the present invention can be obtained. A colored pigment is a pigment that exhibits a colored color such as yellow, orange, red, green, blue, purple, etc., and a black pigment is a pigment that exhibits black. As the colored pigment, for example, the above-mentioned inorganic colored pigments, the above-mentioned organic colored pigments, etc. can be used. The total volume ratio of the colored pigment and the black pigment is preferably 5% by volume or more, more preferably 15% by volume or more, and still more preferably 30% by volume or more in the total volume of the component (B).

[0021] In the present invention, as the pigment, in addition to the above-mentioned coloring pigment (B), an extender pigment is included. Thereby, it becomes possible to reduce the gloss on the coating film surface and impart a calm finish feeling. Examples of the extender pigment include heavy calcium carbonate, light calcium carbonate, kaolin, clay, pottery clay, china clay, diatomaceous earth, hydrated fine silica powder, talc, mica, barite powder, barium sulfate, precipitated barium sulfate, barium carbonate, magnesium carbonate, silica powder, aluminum hydroxide, and the like. These can be used alone or in combination of two or more. The average particle diameter of the extender pigment is preferably 1 to 100 μm, more preferably 2 to 50 μm.

[0022] The present invention is characterized by including flaky powder (C) (hereinafter also referred to as "(C) component") as the above-mentioned extender pigment. Thereby, while forming a coating film with reduced gloss, it is possible to suppress discoloration of the coating film due to moisture and other external factors. Furthermore, effects such as prevention of desorption of the coloring pigment from the coating film (color bleeding prevention) can also be enhanced. Although the mechanism of action is not clear, it is presumed that the flaky powder (C) exerts an action of blocking water, an action of smoothing the coating film surface, etc. due to its shape, and contributes to suppression of discoloration of the coating film. Specific examples of the flaky powder (C) include, for example, talc, mica, clay, etc., and these can be used alone or in combination of two or more. The average particle diameter of the (C) component is preferably 1 to 100 μm, more preferably 2 to 50 μm.

[0023] The mixing ratio of the (C) component is 300 parts by weight or more, preferably 310 parts by weight or more, more preferably 320 parts by weight or more, based on 100 parts by weight of the (B) component. Thereby, effects such as gloss reduction effect and discoloration suppression effect can be sufficiently obtained. The upper limit of the mixing ratio of the (C) component is preferably 2000 parts by weight or less, more preferably 1200 parts by weight or less, still more preferably 1000 parts by weight or less, based on 100 parts by weight of the (B) component. By setting the upper limit of the mixing ratio of the (C) component to the above value, sufficient color development property by the coloring pigment (B) can be obtained, and it is also suitable in terms of preventing cracking of the coating film and the like.

[0024] In addition, the volume ratio of component (C) in the total volume of the pigments (the total volume of the coloring pigment and the extender pigment) is preferably 40 to 99% by volume, more preferably 50 to 95% by volume. When the volume ratio of component (C) is within such a range, more excellent effects can be obtained in terms of the effect of reducing gloss, the effect of suppressing discoloration, and the like.

[0025] The coating material of the present invention mixes these pigments (coloring pigment and extender pigment) within a range where the pigment volume concentration is 30 to 70% (preferably 35 to 60%). By setting the pigment volume concentration within such a range, the effects of the present invention can be obtained. Furthermore, it is also possible to prevent the desorption (color transfer) of the pigment from the coating film. When the pigment volume concentration is less than the above lower limit, it becomes difficult to obtain the effect of reducing gloss, etc., and when it exceeds the above upper limit, it becomes difficult to obtain the effect of suppressing discoloration of the coating film, etc. The pigment volume concentration is the volume percentage of the pigment contained in the dry coating film, and is a value obtained by calculation from the mixing amounts of the resin and the pigment constituting the aqueous coating material.

[0026] The coating material of the present invention may contain a silicone resin emulsion (D) (hereinafter also referred to as "component (D)") in addition to the above-described components. In the present invention, by including the silicone resin emulsion (D), the effect of suppressing the discoloration of the coating film due to external factors such as moisture, pressure, friction, and flying objects can be further enhanced. Such an effect is considered to be achieved because the silicone resin constituting component (D) has the action of blocking moisture, and further has a low glass transition temperature and elasticity.

[0027] Component (D) is an aqueous dispersion of resin particles mainly composed of a silicone resin. Such a silicone resin emulsion (D) can be obtained, for example, by polymerizing silicone components such as siloxane compounds and alkoxysilane compounds. As the silicone resin emulsion (D), those containing monomers other than the silicone component as constituent components may be used, but in the present invention, those containing the silicone component in the polymer constituting component (D) are preferably 50% by weight or more, more preferably 70% by weight or more, and still more preferably 90% by weight or more.

[0028] Among the silicone components constituting the (D) component, examples of the siloxane compound include cyclic siloxane compounds, linear siloxane compounds, branched siloxane compounds, and the like. Among these, examples of the cyclic siloxane compound include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and the like. As the alkoxysilane compound, a silane compound having one or more alkoxyl groups in the molecule can be used. For example, in addition to tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, etc., silane coupling agents such as vinylmethyldimethoxysilane, γ-(meth)acryloyloxytrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, etc. can be mentioned. These can be used alone or in combination of two or more. Also, at the time of polymerization of the (D) component, an emulsifier, a catalyst, a neutralizing agent, etc. can be appropriately mixed. The average molecular weight of the silicone resin is preferably 10,000 or more, more preferably 50,000 or more.

[0029] The average particle diameter of the (D) component is preferably smaller than the average particle diameter of the acrylic resin emulsion (A). Thereby, discoloration of the coating film due to moisture and other external factors can be sufficiently suppressed, and excellent discoloration resistance can be exhibited. The average particle diameter of the (D) component is preferably set within a range relatively smaller than that of the (A) component, but is preferably 100 nm or less, more preferably 5 to 80 nm, still more preferably 10 to 70 nm, and particularly preferably 20 to 65 nm.

[0030] The mixing ratio of the (D) component is preferably 1 to 100 parts by weight, more preferably 2 to 80 parts by weight, still more preferably 3 to 60 parts by weight, based on 100 parts by weight of the coloring pigment (B) in terms of solid content. If the (D) component has such a mixing ratio, it is suitable in terms of improving the effects of the present invention. Also, since the upper limit of the mixing ratio of the (D) component is the above value, it becomes difficult for contaminants and the like to adhere to the coating film, and discoloration of the coating film due to contamination can also be suppressed.

[0031] In the present invention, in addition to the above-described components, various additives and the like can also be mixed. Examples of such additives include pigment dispersants, emulsifiers, thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreezing agents, pH adjusters, antiseptics, fungicides, algicides, antibacterial agents, defoaming agents, adsorbents, deodorants, ultraviolet absorbers, light stabilizers, antioxidants, catalysts, crosslinking agents, and the like. Further, as long as the effects of the present invention are not significantly inhibited, resin emulsions other than the component (A) and the component (D) can also be mixed.

[0032] The coating material of the present invention is an aqueous material containing water as a medium. The medium may contain a water-soluble solvent as necessary in addition to water. Examples of the water-soluble solvent include alcohols, glycols, glycol ethers, and the like.

[0033] The coating material of the present invention can be applied to the surfaces (such as wall surfaces) of buildings, civil engineering structures, and the like. The substrate to be coated is not particularly limited, but an inorganic substrate is preferably used. In particular, in the present invention, a cement-based inorganic substrate is suitable. When the coating material of the present invention is applied to a cement-based inorganic substrate, the effects of the present invention can be sufficiently exhibited.

[0034] Such cement-based inorganic substrates are materials obtained with cement as an essential component. As components other than cement, for example, aggregates such as silica sand, silica stone, fly ash, and fibers such as pulp and glass wool may be included. Specifically, examples of cement-based inorganic substrates include concrete, mortar, fiber-reinforced cement boards, slate boards, calcium silicate cement boards, slag cement perlite boards, ALC boards, siding boards, and the like. Among these, substrates such as concrete and mortar can be obtained, for example, by hardening a mixture with water or the like at the construction site. Inorganic building materials such as ALC boards and siding boards are, for example, formed into a plate shape by various methods such as a papermaking method, an extrusion molding method, and a casting method. When the coating material of the present invention is applied to a cement-based inorganic building material, it is particularly suitable in that it can sufficiently suppress cracks, warping, dimensional changes, etc. of the substrate. The surface of these substrates may be subjected to some surface treatment (for example, sealer, surfacer, putty, filler, etc.), or may already have a coating film formed thereon, etc.

[0035] When applying the coating material of the present invention, for example, various coating tools such as sprayers, rollers, and brushes can be used. It is also possible to dilute with water during coating. The mixing amount of water may be appropriately set in consideration of the type of coating tool, the state of the coating base, the temperature during coating, etc., but is preferably about 0 to 20% by weight based on the entire coating material.

[0036] The coating amount of the coating material of the present invention is preferably 0.1 to 1 kg / m 2 , more preferably 0.2 to 0.6 kg / m 2 . Also, drying after applying the coating material of the present invention may preferably be performed at normal temperature (5 to 40°C), but heating is also possible. The drying time is preferably about 0.5 to 4 hours at normal temperature. The number of coating times is preferably about 1 to 2 times.

[0037] The coating material of the present invention can form a film with reduced gloss, that is, a matte film. Here, the term "matte" includes not only what is generally called matte but also what is called 3-minute gloss, 5-minute gloss, etc. Specifically, the degree of matte can be defined by the specular glossiness. The specular glossiness of the coating material of the present invention is preferably 40 or less, more preferably 20 or less, and even more preferably 0.1 to 10. The specular glossiness is a value obtained by coating the coating material on one side of a glass plate using a film applicator with a gap of 150 μm, placing the coated surface horizontally, and drying it for 48 hours in a standard state (temperature 23°C, relative humidity 50%), and then measuring the specular glossiness (measurement angle 60 degrees).

Examples

[0038] Examples and comparative examples are shown below to clarify the features of the present invention more clearly.

[0039] (Manufacture of coating material) Each aqueous coating material was manufactured by mixing and stirring each raw material in parts by weight shown in Table 1 by a conventional method. The following were used as raw materials.

[0040] ·Resin 1: Acrylic resin emulsion (emulsion polymer of methyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, and methacrylic acid, composition ratio of (meth)acrylic acid alkyl ester in all monomers: 98% by weight, average particle diameter: 130 nm, solid content: 50% by weight, glass transition temperature: 5°C, resin specific gravity: 1.0, medium: water) ·Resin 2: Acrylic styrene resin emulsion (emulsion polymer of methyl methacrylate, styrene, n-butyl acrylate, 2-ethylhexyl acrylate, and acrylic acid, composition ratio of (meth)acrylic acid alkyl ester in all monomers: 75% by weight, average particle diameter: 150 nm, solid content: 50% by weight, glass transition temperature: 8°C, resin specific gravity: 1.0, medium: water) · Resin 3: Silicone resin emulsion (emulsion dispersion of octamethylcyclotetrasiloxane - alkoxysilane compound polymer, silicone component ratio in resin: 100% by weight, average particle size: 50 nm, solid content: 30% by weight, resin specific gravity: 1.0, medium: water) · Colored pigment 1: Chromatic pigment (petal, average particle size 0.2 μm, specific gravity 5.0) · Colored pigment 2: Chromatic pigment (yellow iron oxide, average particle size 0.5 μm, specific gravity 4.0) · Colored pigment 3: Black pigment (carbon black, average particle size 0.1 μm, specific gravity 1.8) · Colored pigment 4: White pigment (titanium oxide, average particle size 0.2 μm, specific gravity 4.2) · Extender pigment 1: Flaky powder (talc, average particle size 12 μm, specific gravity 2.7) · Extender pigment 2: Granular powder (silica powder, average particle size 4 μm, specific gravity 2.6) · Film - forming aid: Ester - based film - forming aid · Dispersant: Anionic dispersant · Thickener: Cellulose - based thickener, urethane - based thickener · Defoamer: Mineral oil - based defoamer

[0041] (Test method) (1) Specular glossiness The specular glossiness (measurement angle 60 degrees) was measured when the coating material was applied to one side of a glass plate using a film applicator with a gap of 150 μm, the coated surface was placed horizontally, and dried in a standard state for 48 hours.

[0042] (2) Color fastness 1 The coating material was applied to one side of a glass plate using a film applicator with a gap of 150 μm, the coated surface was placed horizontally, and the sample dried in a standard state for 14 days was used as the test specimen. The surface of the coating film of this test specimen was rubbed with a paper towel, and the degree of discoloration due to the scratch was evaluated. The evaluation was carried out in four grades (excellent: a > b > c > d: poor), where "a" indicates no discoloration was observed and "d" indicates significant discoloration was observed.

[0043] (3) Color fastness 2 A test piece was prepared in the same manner as the above-mentioned "color fastness 1". After continuously flowing water over the coating surface of this test piece for 1 minute, the degree of discoloration due to water was evaluated. The evaluation was performed in four grades (excellent: a > b > c > d: poor), where those with no discoloration were rated as "a" and those with significant discoloration were rated as "d".

[0044] (4) Color fastness 3 On a slate board pre-coated with an undercoat material, the coating material was applied by brush coating at an application rate of 0.3 kg / m 2 and dried in the standard state for 14 days to obtain a test piece. This test piece was immersed in water at 23°C for 7 days, and the color difference (ΔE) of the coating before and after immersion was measured with a color difference meter. The evaluation was performed in four grades (excellent: a > b > c > d: poor), where those with a color difference of less than 0.3 were rated as "a", those with a color difference of 0.3 or more and less than 0.6 were rated as "b", those with a color difference of 0.6 or more and less than 1.0 were rated as "c", and those with a color difference of 1.0 or more were rated as "d".

[0045] (5) Color bleeding prevention On one side of a glass plate, the coating material was applied using a film applicator with a gap of 150 μm, and the coated surface was placed horizontally and dried in the standard state for 14 days to obtain a test piece. The coating surface of this test piece was rubbed with a paper wipe, and the degree of coloring of the paper wipe (the degree of color bleeding to the paper wipe) was evaluated. The evaluation was performed in four grades (excellent: a > b > c > d: poor), where those with no coloring were rated as "a" and those with significant coloring were rated as "d".

[0046] (Test results) The test results are shown in Table 1. In Examples 1 to 8, good results were obtained in each test.

[0047]

Table 1

Claims

1. An aqueous coating material having a pigment volume concentration of 30 to 70% and being applied to the surface of a building or civil engineering structure, comprising an acrylic resin emulsion (A), a coloring pigment (B), and a flaky powder (C) as an extender pigment, wherein the coloring pigment (B) includes a colored pigment and / or a black pigment, the total volume ratio of the colored pigment and the black pigment is 5% by volume or more in the total volume of the coloring pigment (B), the coloring pigment (B) does not contain a white pigment, or when a white pigment is contained, the mixing ratio of the white pigment is at most 10 parts by weight per 100 parts by weight of the coloring pigment (B), the flaky powder (C) is one or more selected from talc and clay, and the aqueous coating material is characterized by containing 346 parts by weight or more and 1200 parts by weight or less of the flaky powder (C) per 100 parts by weight of the coloring pigment (B).

2. The aqueous coating material according to Claim 1, wherein the white pigment is one or more selected from titanium oxide, zinc oxide, and alumina.

Images