JP2024106556A - Water-based undercoat material and decorative finishing method - Google Patents

Abstract

To provide an aqueous undercoating material which can exhibit excellent performance as a base adjustment coating material used in decorative finishing of a building wall surface or the like.SOLUTION: An aqueous undercoating material contains acrylic silicon resin emulsion, and a pigment, wherein the acrylic silicon resin emulsion contains 20 wt.% or more of an aromatic monomer in a resin component, contains an extender pigment as the pigment, and has pigment volume concentration of 30-90%.SELECTED DRAWING: None

Description

The present invention relates to a new water-based primer and decorative finishing method.

Architectural walls and other surfaces are often painted to protect the structure and improve its appearance. One known method of finishing is to apply a base-conditioning coating material as a water-based undercoat, followed by a coating of various finishing materials. The base-conditioning coating material used in this case is a material that has the function of filling and repairing unevenness, cracks, holes, etc. in the base, as well as the function of imparting a desired uneven pattern by adjusting the amount applied and selecting painting equipment, etc.

Examples of such base preparation coating materials include cement-based base preparation coating materials and synthetic resin-based base preparation coating materials. Of these, synthetic resin-based base preparation coating materials have been favored in recent years because they have good adhesion to the base and can follow any displacement of the base.

For example, JP-A-8-134378 (Patent Document 1) discloses a base adjustment coating material whose main components are a synthetic resin emulsion, an extender pigment, and a thickener, and whose heating residue is 50 to 99% by weight. In addition, JP-A-2008-12373 (Patent Document 2) discloses a base adjustment material containing an aqueous dispersion of a copolymer whose glass transition temperature is -20°C or lower.

Japanese Patent Application Publication No. 8-134378 JP 2008-12373 A

Meanwhile, the above-mentioned building walls and the like have various substrates, and various existing coating films (old coating films) may be formed on the surfaces of these substrates, and the shapes and properties of the surfaces to be coated are diverse. In addition, building walls and the like may be composed of multiple plate-like wall materials, and the joints between these plate-like wall materials are often filled with a joint material such as a sealant. When such a surface is to be coated, it is required that the coating film properties of the entire surface, including the joints, are good.
However, the above-mentioned patent documents do not take into consideration the painting of such a surface to be coated. Even if a cosmetic finish is applied to such a surface to be coated using the base preparation coating material of the above-mentioned patent documents, there is a risk of problems such as swelling, peeling, and cracking occurring depending on environmental conditions such as sunlight, temperature, rainfall, and humidity.

The present invention has been made in consideration of the above-mentioned problems, and aims to provide a water-based primer that can exhibit excellent performance as a base-adjusting coating material used for the decorative finishing of building walls and the like, and a decorative finishing method using the water-based primer.

As a result of extensive research into achieving the above objective, the inventor came up with the idea of a water-based primer containing a specific resin emulsion and pigment, and completed the present invention.

That is, the present invention has the following features.
1. A water-based primer containing an acrylic silicone resin emulsion and a pigment,
The acrylic silicone resin emulsion contains 20% by weight or more of an aromatic monomer in its resin constituents,
The water-based primer material contains an extender pigment as the pigment, and has a pigment volume concentration of 30 to 90%.
2. The acrylic silicone resin emulsion contains, as a resin component,
(a) a (meth)acrylic acid alkyl ester having an alkyl main chain having 3 or more carbon atoms;
(b) an aromatic monomer, and (c) an alkoxysilane compound;
1. The water-based undercoat material according to claim 1,
3. The acrylic silicone resin emulsion contains, as a resin component,
(a1) a (meth)acrylic acid alkyl ester having an alkyl main chain having 3 to 5 carbon atoms;
(a2) (meth)acrylic acid alkyl ester having an alkyl main chain having 6 or more carbon atoms;
(b) an aromatic monomer, and (c) an alkoxysilane compound;
1. The water-based undercoat material according to claim 1,
4. The water-based undercoat material according to any one of 1. to 3., characterized in that it is for use on a surface having joints.
5. A decorative finishing method in which a water-based undercoat material is applied to a surface having joints, and then a finishing material is applied to the surface,
A decorative finishing method, characterized in that the water-based undercoat material according to any one of 1. to 3. is used as the water-based undercoat material.

The present invention provides a water-based primer that can exhibit excellent performance as a base-conditioning coating material used in the decorative finishing of building walls and the like, and a decorative finishing method using the water-based primer.

The following describes how to implement the present invention.

The water-based primer of the present invention contains an acrylic silicone resin emulsion and a pigment, and the acrylic silicone resin emulsion contains 20% by weight or more of aromatic monomer in the resin components, and contains an extender pigment as the pigment, and the pigment volume concentration is 30 to 90%. Such a water-based primer is suitable as a base adjustment coating material, and can sufficiently suppress the occurrence of defects such as swelling, peeling, and cracking, particularly when used for the decorative finish of a coating surface having joints. Such effects are achieved by the water-based primer of the present invention having the above-mentioned configuration having performance suitable for a base adjustment coating material used on a coating surface having joints in terms of the strength, elongation, adhesion, etc. of the coating film.

The acrylic silicone resin emulsion of the water-based primer of the present invention acts as a binder. For example, an acrylic silicone resin emulsion containing an alkyl (meth)acrylate ester, an aromatic monomer, and an alkoxysilane compound as resin components can be used. The ratio of aromatic monomer in the resin components is 20% by weight or more, preferably 25 to 75% by weight, and more preferably 30 to 70% by weight. In the present invention, alkyl acrylate ester and alkyl methacrylate ester are collectively referred to as alkyl (meth)acrylate ester. A monomer is a general term for a compound having a polymerizable unsaturated double bond. In the present invention, "α to β" is synonymous with "α or more and β or less."

Examples of (meth)acrylic acid alkyl esters include those having an alkyl main chain with 1 to 2 carbon atoms in the alkyl portion, those having an alkyl main chain with 3 or more carbon atoms in the alkyl portion, and those having a cyclic alkyl group in the alkyl portion.

Of these, the (meth)acrylic acid alkyl esters having an alkyl main chain with 1 to 2 carbon atoms in the alkyl portion can be those in which the alkyl portion is a straight-chain or branched alkyl group (excluding cyclic groups) and the main chain (the longest straight carbon chain) has 1 to 2 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, and t-butyl (meth)acrylate. These can be used alone or in combination of two or more.

An alkyl (meth)acrylate ester having an alkyl main chain with 3 or more carbon atoms (hereinafter also referred to as "component (a)") has an alkyl portion which is a linear or branched alkyl group (excluding cyclic groups) and has 3 or more carbon atoms in the main chain (the longest carbon linear chain). Component (a) has an alkyl main chain with 3 or more carbon atoms in the alkyl portion. As long as it has such an alkyl main chain, the alkyl portion of component (a) may have various side chains (e.g., an alkyl group with fewer carbon atoms than the alkyl main chain). As component (a), any (meth)acrylate alkyl ester that satisfies these conditions can be used, for example:
(meth)acrylic acid alkyl esters (a1) having an alkyl main chain having 3 to 5 carbon atoms, such as n-propyl (meth)acrylate, isobutyl (meth)acrylate, 1-ethylpropyl (meth)acrylate, t-pentyl (meth)acrylate, neopentyl (meth)acrylate, n-butyl (meth)acrylate, 2-methylbutyl (meth)acrylate, isopentyl (meth)acrylate, 3-methylbutyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-pentyl (meth)acrylate, 2-methylpentyl (meth)acrylate, and 4-methylpentyl (meth)acrylate;
Examples of such alkyl (meth)acrylates (a2) include alkyl (meth)acrylates having an alkyl main chain having 6 or more carbon atoms, such as n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-heptyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, and n-lauryl (meth)acrylate. These can be used alone or in combination of two or more.

Examples of (meth)acrylic acid alkyl esters having a cyclic alkyl group in the alkyl portion include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyl (meth)acrylate.

Examples of aromatic monomers (hereinafter also referred to as "component (b)") include styrene-based monomers such as styrene, 2-methylstyrene, vinyltoluene, ethylvinylbenzene, vinylnaphthalene, and chlorostyrene, as well as phenyl (meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate. These can be used alone or in combination of two or more.

Examples of the alkoxysilane compound (hereinafter also referred to as "component (c)") include alkoxysilane compounds having a polymerizable unsaturated double bond, such as γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltriisopropoxysilane;
Alkoxysilane compounds having a glycidyl group, such as γ-glycidoxymethacryloxypropyltrimethoxysilane, γ-glycidoxymethacryloxypropylmethyldimethoxysilane, γ-glycidoxymethacryloxypropyltriethoxysilane, γ-glycidoxymethacryloxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane;
Alkoxysilane compounds having an amino group, such as N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropylmethyldimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, N-2(aminoethyl)3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane;
alkoxysilane compounds having a mercapto group, such as γ-mercaptopropyltrimethoxysilane;
Tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-i-propoxysilane, tetra-n-butoxysilane, tetra-i-butoxysilane, tetra-t-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrippropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltrippropoxysilane, ethyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltrippropoxysilane, propyltributoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltrippropoxy Examples of the alkoxysilane include silane, butyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethylsilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, cyclohexylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, and γ-anilinopropyltrimethoxysilane, and alkoxysilane modified products in which at least a portion of the alkoxyl groups of these alkoxysilanes are modified with a polyoxyalkylene group-containing compound, an amino group-containing compound, a fluorine-containing compound, etc. These can be used alone or in combination of two or more.

The acrylic silicone resin emulsion may contain other monomers (other monomers) as resin constituents. Examples of such other monomers include:
Carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid or its monoalkyl ester, itaconic acid or its monoalkyl ester, fumaric acid or its monoalkyl ester;
Carbonyl group-containing monomers, such as acrolein, diacetone acrylamide, diacetone methacrylamide, and acetoacetoxyethyl methacrylate;
Hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and 6-hydroxyhexyl vinyl ether;
Amino group-containing monomers such as dimethylaminoethyl (meth)acrylate and dimethylaminopropyl (meth)acrylate;
Amide group-containing monomers such as (meth)acrylamide and ethyl(meth)acrylamide;
Nitrile group-containing monomers such as acrylonitrile;
Epoxy group-containing monomers such as glycidyl (meth)acrylate;
Sulfonic acid-containing vinyl monomers such as styrene sulfonic acid and vinyl sulfonic acid;
Acid anhydrides such as maleic anhydride and itaconic anhydride;
Chlorine-containing monomers such as vinyl chloride, vinylidene chloride, and chloroprene;
Alkylene glycol monoallyl ethers such as ethylene glycol monoallyl ether, propylene glycol monoallyl ether, and diethylene glycol monoallyl ether;
Vinyl ester monomers such as vinyl acetate and vinyl propionate;
Ethylene, propylene, isobutylene, etc. can be used. These can be used alone or in combination of two or more. In addition, an ethylenically unsaturated double bond-containing ultraviolet absorber, an ethylenically unsaturated double bond-containing light stabilizer, etc. can also be used.

The acrylic silicone resin emulsion of the present invention contains, as a resin component,
(a) a (meth)acrylic acid alkyl ester having an alkyl main chain having 3 or more carbon atoms;
(b) an aromatic monomer, and (c) an alkoxysilane compound;
Such an acrylic silicone resin emulsion is suitable for improving the effects of the present invention, and is also suitable for water resistance, adhesion, etc., in the initial film formation stage. In particular, component (a) acts advantageously in terms of elongation, adhesion, etc., and contributes to preventing cracking, peeling, etc. Component (b) acts advantageously in terms of strength, etc., and contributes to preventing blistering, cracking, etc. Component (c) acts advantageously in terms of strength, adhesion, etc., and contributes to preventing blistering, peeling, cracking, etc.

The ratio of component (a) in the resin components is preferably 20 to 80% by weight, more preferably 25 to 75% by weight, and even more preferably 30 to 70% by weight. The ratio of component (b) in the resin components is preferably 20% by weight or more, more preferably 25 to 75% by weight, and even more preferably 30 to 70% by weight. The ratio of component (c) in the resin components is preferably 0.01% by weight or more, more preferably 0.01 to 5% by weight, and even more preferably 0.02 to 3% by weight.

As the component (a),
(a1) a (meth)acrylic acid alkyl ester having an alkyl main chain having 3 to 5 carbon atoms (hereinafter also referred to as “component (a1)”);
(a2) (meth)acrylic acid alkyl ester having an alkyl main chain with 6 or more carbon atoms (hereinafter also referred to as "(a2) component"). When the (a) component contains the (a1) component and the (a2) component, in addition to extensibility and adhesion, it is advantageous in terms of strength, and can further improve performance such as prevention of blistering, peeling, and cracking. It is particularly suitable in terms of improving performance in joints.

The weight ratio of the (a1) component to the (a2) component in the resin constituent components preferably satisfies (a1)/(a2) ≧ 0.6, more preferably 10 ≧ (a1)/(a2) ≧ 0.8, even more preferably 8.0 ≧ (a1)/(a2) ≧ 1.0, and particularly preferably 5.0 ≧ (a1)/(a2) ≧ 1.2.

The acrylic silicone resin emulsion of the present invention can be produced by polymerizing a group of monomers containing the above-mentioned resin components. Any known method can be used as the polymerization method, and in addition to normal emulsion polymerization, soap-free emulsion polymerization, feed emulsion polymerization, seed emulsion polymerization, multi-stage emulsion polymerization, etc. can also be used. During polymerization, for example, emulsifiers, initiators, dispersants, polymerization inhibitors, polymerization retarders, buffers, chain transfer agents, pH adjusters, etc. can be used.

As the emulsifier, various surfactants that can be used in emulsion polymerization can be used, and these may be reactive types (reactive surfactants) having polymerizable unsaturated double bonds. As the emulsifier, for example, anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. can be used alone or in combination.

The glass transition temperature (Tg) of the acrylic silicone resin emulsion is preferably -50 to 20°C or lower, more preferably -30°C to 15°C. The glass transition temperature can be calculated using Fox's formula. However, component (c) is excluded from the calculation of the glass transition temperature in this invention.

The average particle size of the acrylic silicone resin emulsion is preferably 300 nm or less, more preferably 20 to 250 nm, and even more preferably 50 to 200 nm. The average particle size referred to here is a value measured by dynamic light scattering.

The water-based primer of the present invention contains an extender pigment as a pigment. The extender pigment contributes to, for example, the function of filling and repairing unevenness, cracks, holes, etc. in the base, the function of homogenizing the base surface, the function of imparting the desired coating surface shape, etc. In the present invention, the blending of such an extender pigment can impart performance suitable for a base adjustment coating material.

Examples of extender pigments include heavy calcium carbonate, light calcium carbonate, clay, kaolin, talc, barium carbonate, white carbon, diatomaceous earth, kansui stone, china clay, barite powder, barium sulfate, precipitated barium sulfate, barium carbonate, magnesium carbonate, silica powder, silica sand, silica stone powder, quartz powder, hydrous silicic acid powder, aluminum hydroxide, resin beads, glass beads, hollow balloons, etc. These can be used alone or in combination of two or more.

The average particle size of the extender pigment is preferably 0.1 to 100 μm, more preferably 0.5 to 80 μm, and even more preferably 1 to 50 μm. The average particle size of the extender pigment is a value measured by a laser diffraction particle size distribution measuring device.

The content of the extender pigment is preferably 100 to 2000 parts by weight, more preferably 250 to 1800 parts by weight, and even more preferably 400 to 1400 parts by weight, per 100 parts by weight of the solid content of the acrylic silicone resin emulsion. By having the content of the extender pigment within this range, the performance as a base adjustment coating material can be improved. In particular, by having the content of the extender pigment be equal to or greater than the above lower limit, the strength is increased, and it is suitable in terms of preventing blistering and cracking. By having the content of the extender pigment be equal to or less than the above upper limit, the adhesion, extensibility, etc. are sufficiently ensured, and it is suitable in terms of preventing peeling and cracking.

In addition to extender pigments, color pigments can be used as pigments. Examples of color pigments include titanium oxide, zinc oxide, alumina, carbon black, graphite, black iron oxide, iron-manganese composite oxide, iron-copper-manganese composite oxide, iron-chromium composite oxide, iron-chromium-cobalt composite oxide, copper-chromium composite oxide, copper-manganese-chromium composite oxide, copper-magnesium composite oxide, bismuth-manganese composite oxide, ferric oxide (red oxide), molybdate orange, permanent red, permanent carmine, anthraquinone red, perylene red, quinacridone red, yellow iron oxide, titanium yellow, fast yellow, benzimidazolone yellow, chrome green, cobalt green, phthalocyanine green, ultramarine blue, Prussian blue, cobalt blue, phthalocyanine blue, quinacridone violet, dioxazine violet, aluminum pigments, and pearl pigments. These can be used alone or in combination of two or more. The average particle size of the color pigment is preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 0.01 to 0.9 μm. The average particle size of the color pigment is a value measured by a laser diffraction particle size distribution measuring device.

The content of the color pigment is preferably 1 to 200 parts by weight, more preferably 2 to 100 parts by weight, and even more preferably 3 to 60 parts by weight, per 100 parts by weight of the solid content of the acrylic silicone resin emulsion. By having the content of the color pigment within this range, the water-based primer can be colored to the desired color, and hiding properties, etc. can be improved.

The pigment volume concentration of the water-based primer of the present invention is 30 to 90%, preferably 50 to 88%, and more preferably 60 to 85%. By having the pigment volume concentration within this range, it is possible to impart performance as a base adjustment coating material, and further to ensure performance such as prevention of swelling, peeling, and cracking. In particular, by having the pigment volume concentration be equal to or higher than the above lower limit, strength is increased, which is preferable in terms of preventing swelling and cracking. By having the pigment volume concentration be equal to or lower than the above upper limit, adhesion, elongation, etc. are sufficiently ensured, which is preferable in terms of preventing peeling and cracking. Note that the pigment volume concentration in the present invention is the volume percentage of the pigment contained in the dried coating film, and is a value calculated from the weight parts and specific gravity of the resin and pigment that constitute the water-based primer. Note that the specific gravity of the resin component is 1.

In addition to the above-mentioned components, the water-based primer of the present invention can be mixed with various additives as needed, such as anti-rust pigments, aggregates, fibers, pH adjusters, plasticizers, preservatives, anti-mold agents, anti-algae agents, defoamers, leveling agents, coupling agents, dispersants, anti-settling agents, anti-sagging agents, thickeners (thixotropic adjusters), film-forming agents, matting agents, crosslinking agents, catalysts, curing accelerators, adhesion agents, UV absorbers, light stabilizers, solvents, water, etc. The water-based primer of the present invention can be manufactured by uniformly mixing the above-mentioned acrylic silicone resin emulsion, pigments, and various additives as needed by conventional methods.

The water-based primer of the present invention can be configured to include a crosslinking agent. In this case, an acrylic silicone resin emulsion having a reactive functional group is used as the resin, and a crosslinking agent capable of reacting with the reactive functional group is used as the crosslinking agent. Suitable combinations of reactive functional groups include, for example, combinations of a carboxyl group and a carbodiimide group, a carboxyl group and an epoxy group, a carboxyl group and an oxazoline group, a carbonyl group and a hydrazide group, and the like, and one or more of these can be used.

The water-based primer of the present invention is a water-based 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 water-based undercoat material of the present invention can be applied to a surface to be coated, such as the wall surface of a building or civil engineering structure. Examples of the substrate that constitutes such a surface to be coated include concrete, mortar, metal, wood, glass, and various plate-shaped wall materials. Among these, examples of plate-shaped wall materials include inorganic hardened bodies mainly composed of cement, calcium silicate, lime, gypsum, and the like. Specific examples of such plate-shaped wall materials include cement boards, extrusion molding boards, slate boards, PC boards, ALC boards, fiber-reinforced cement boards, siding boards, ceramic boards, calcium silicate boards, gypsum boards, and hard wood chip cement boards. Such surfaces to be coated may have an existing coating film (old coating film) on the surface of the substrate.

In the present invention, the surface to be coated is preferably a surface that includes joints. Such a surface is formed by arranging multiple wall plate materials side by side, with joints between the wall plate materials. It is desirable that the joints are filled with a joint material such as a sealant or a dry joint material. The width of the joints is preferably about 3 to 20 mm (more preferably 5 to 15 mm).

The present invention is particularly effective when the joints of the surface to be coated contain a sealant. The sealant may be one that has deteriorated over time, or it may be one that has been newly applied before the application of the water-based primer.

Examples of sealants include silicone-based sealants, modified silicone-based sealants, polysulfide-based sealants, modified polysulfide-based sealants, acrylic urethane-based sealants, polyurethane-based sealants, SBR-based sealants, and butyl rubber-based sealants.

The method of filling the sealant is not particularly limited, and known methods using a gun or spatula, for example, can be used. In addition, before filling the sealant, processing such as filling with a backup material or applying a primer may be performed in advance. As the backup material, for example, a foamed polyethylene backup material can be used. As the primer, for example, a synthetic rubber primer, an acrylic primer, a urethane primer, an epoxy primer, a silicone resin primer, a silane primer, etc. can be used.

In the present invention, a decorative finish can be achieved by applying (painting) a water-based primer and a topcoat in that order to the surface to be coated as described above.

The water-based primer of the present invention can be applied directly to the surface to be coated, but various pretreatments can also be performed as necessary. Pretreatments include, for example, removal of existing coatings that have deteriorated significantly, removal of contaminants by high-pressure water washing, repair with putty or filler, restoration of the surface shape, etc. If a new sealant has been applied to the surface to be coated, it is desirable to apply the water-based primer approximately 2 to 10 days after the sealant has been applied.

When applying the water-based undercoat material, known painting tools can be used. Examples of painting tools that can be used include sprays, rollers, brushes, and trowels. The amount of water-based undercoat material applied can be set appropriately depending on the surface shape of the surface to be coated and the painting tool used, but is preferably 0.1 to 2 kg/m ² , and more preferably 0.3 to 1.5 kg/m ^2. The water-based undercoat material can also be appropriately diluted with water during application.

The solids content of the water-based primer at the time of painting is preferably 50-90% by weight, more preferably 60-80% by weight. The viscosity of the water-based primer at the time of painting is preferably 10-500 Pa·s, more preferably 20-400 Pa·s. By having the solids content and viscosity of the water-based primer at the time of painting (or the diluted water-based primer if diluted) within these ranges, the effects of the present invention can be stably obtained. The viscosity referred to here is the value determined by measuring the viscosity at 2 rpm (the guideline value at the second rotation) with a BH type viscometer, and the measurement temperature is 23°C.

The application and drying of the water-based primer can be carried out in an environment at room temperature (preferably 0 to 50°C, more preferably 5 to 45°C). The drying time of the water-based primer at room temperature is preferably 2 hours or more, more preferably 3 hours or more.

In the present invention, a finishing material can be applied after the above-mentioned water-based undercoat material has been applied and dried. By applying the finishing material, a cosmetic finish with aesthetic appeal can be obtained. One or more types of finishing materials can be used. Examples of specifications using two or more types of finishing materials include specifications in which one or more types of materials called sealers, intermediate coating materials, main materials, etc. are applied, and then a finishing material that will become the outermost surface of the coating film is applied.

The coating film formed by the water-based undercoat material of the present invention can exhibit excellent adhesion to a wide variety of finishing materials. There are no particular limitations on the finishing material, so long as it is one that is generally used for painting buildings, etc., and examples of the binder include organic binders such as acrylic resin, polyurethane resin, epoxy resin, fluororesin, alkyd resin, and polyester resin, inorganic binders such as silicon resin, alkoxysilane, colloidal silica, and silicate, and organic-inorganic composite binders such as acrylic silicon resin.

In addition to the binders mentioned above, the components of the finishing material include, for example, color pigments, extender pigments, aggregates, thickeners, film-forming agents, leveling agents, wetting agents, plasticizers, antifreeze agents, pH adjusters, preservatives, antifungal agents, anti-algae agents, antibacterial agents, dispersants, defoamers, adsorbents, coupling agents, fibers, crosslinking agents, UV absorbers, light stabilizers, antioxidants, catalysts, solvents, water, etc. Finishing materials can be manufactured by uniformly mixing the above components in the usual manner according to the type of material.

Specific examples of finishing materials that can be used include weather-resistant topcoat paint for architecture (JIS K5658:2010), weather-resistant paint for steel structures (JIS K5659:2021), glossy synthetic resin emulsion paint (JIS K5660:2021), synthetic resin emulsion paint (JIS K5663:2021), synthetic resin emulsion pattern paint (JIS K5668:2021), acrylic resin non-aqueous dispersion paint (JIS K5670:2021), high solar reflectance paint for roofs (JIS K5675:2011), architectural coating waterproofing material (JIS A6021:2022), architectural finishing coating material (JIS A6909:2021), and other multi-colored pattern paints, stone-like finishing coating materials, sandstone-like finishing coating materials, clear paints, etc.

The method of applying the finishing material is not particularly limited, and a method suitable for each material can be adopted. Examples of application tools that can be used include sprays, rollers, trowels, and brushes. The amount of the finishing material applied varies depending on the type, but is preferably 0.2 to 5 kg/ ^m2 , and more preferably 0.3 to 4 kg/ ^m2 . When applying, the finishing material can be diluted as necessary. The application and drying of the finishing material can be carried out in an environment of room temperature (preferably 0 to 50°C, and more preferably 5 to 45°C).

The coating film formed by this type of decorative finishing method can impart aesthetic appeal to the coated surface, and when used for decorative finishing of coated surfaces that have joints in particular, it can exhibit excellent performance such as preventing blistering, peeling, and cracking.

The following examples will clarify the features of the present invention. However, the present invention is not limited to these examples.

(Manufacturing of water-based undercoat materials)
Each water-based undercoat material was manufactured by mixing and stirring the raw materials in a conventional manner according to the composition shown in Table 1. The following raw materials were used.

Resin 1: Acrylic silicone resin emulsion (emulsion polymer of 2-ethylhexyl acrylate, styrene, γ-methacryloyloxypropyltrimethoxysilane, and methacrylic acid (weight ratio 42:54:1:3), (a1)/(a2)=0, average particle size: 150 nm, solid content: 50% by weight, glass transition temperature: 3°C, resin specific gravity: 1.0, medium: water)
Resin 2: Acrylic silicone resin emulsion (emulsion polymer of n-butyl acrylate, 2-ethylhexyl acrylate, styrene, γ-methacryloyloxypropyltrimethoxysilane, and methacrylic acid (weight ratio 18:26:52:1:3), (a1)/(a2)=0.69, average particle size: 150 nm, solid content: 50% by weight, glass transition temperature: 5° C., resin specific gravity: 1.0, medium: water)
Resin 3: Acrylic silicone resin emulsion (emulsion polymer of n-butyl acrylate, 2-ethylhexyl acrylate, styrene, γ-methacryloyloxypropyltrimethoxysilane, and methacrylic acid (weight ratio 24:22:50:1:3), (a1)/(a2)=1.09, average particle size: 150 nm, solid content: 50% by weight, glass transition temperature: 3° C., resin specific gravity: 1.0, medium: water)
Resin 4: Acrylic silicone resin emulsion (emulsion polymer of n-butyl acrylate, 2-ethylhexyl acrylate, styrene, γ-methacryloyloxypropyltrimethoxysilane, and methacrylic acid (weight ratio 26:20:50:1:3), (a1)/(a2)=1.30, average particle size: 150 nm, solid content: 50% by weight, glass transition temperature: 4°C, resin specific gravity: 1.0, medium: water)
Resin 5: Acrylic silicone resin emulsion (emulsion polymer of methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene, γ-methacryloyloxypropyltrimethoxysilane, and methacrylic acid (weight ratio 12.5:34:13:36:1.5:3), (a1)/(a2)=2.62, average particle size: 150 nm, solid content: 50% by weight, glass transition temperature: 4° C., resin specific gravity: 1.0, medium: water)
Resin 6: Acrylic silicone resin emulsion (emulsion polymer of methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene, γ-methacryloyloxypropyltrimethoxysilane, and methacrylic acid (weight ratio 8:39.5:9:40:0.5:3), (a1)/(a2)=4.39, average particle size: 150 nm, solid content: 50% by weight, glass transition temperature: 4° C., resin specific gravity: 1.0, medium: water)
Resin 7: Acrylic silicone resin emulsion (emulsion polymer of n-butyl acrylate, 2-ethylhexyl acrylate, styrene, γ-methacryloyloxypropyltrimethoxysilane, and methacrylic acid (weight ratio 28:18:50:1:3), (a1)/(a2)=1.56, average particle size: 150 nm, solid content: 50% by weight, glass transition temperature: 4°C, resin specific gravity: 1.0, medium: water)
Resin 8: Acrylic silicone resin emulsion (emulsion polymer of methyl methacrylate, 2-ethylhexyl acrylate, styrene, γ-methacryloyloxypropyltrimethoxysilane, and methacrylic acid (weight ratio 44:42:10:1:3), (a1)/(a2)=0, average particle size: 150 nm, solid content: 50% by weight, glass transition temperature: 5°C, resin specific gravity: 1.0, medium: water)
Resin 9: Acrylic resin emulsion (emulsion polymer of 2-ethylhexyl acrylate, styrene, and methacrylic acid (weight ratio 42:55:3), (a1)/(a2)=0, average particle size: 150 nm, solid content: 50% by weight, glass transition temperature: 4° C., resin specific gravity: 1.0, medium: water)
Pigment 1: Color pigment (titanium oxide, average particle size 0.3 μm, specific gravity 4.2)
Pigment 2: Extender pigment (heavy calcium carbonate, average particle size 8 μm, specific gravity 2.7)
Dispersant: Anionic dispersant Film-forming aid: Ester film-forming aid Thickener: Hydroxyethyl cellulose aqueous solution (solid content 3% by weight)
・Antifoaming agent: Silicone-based antifoaming agent

(Test 1)
A water-based undercoat material was sprayed onto a 100 mm x 300 mm x 6 mm slate board at a coating amount of 1 kg/ ^m2 , and then dried for 10 hours to obtain the specimen [I]. After immersing this specimen [I] in water for 24 hours, the appearance of the coating film (state of defects such as swelling, peeling, and cracking) was visually confirmed. The evaluation criteria were "A" for no defects, "B" for slight defects, and "C" for many defects. All painting and drying were performed under standard conditions (temperature 23°C, relative humidity 50%).

(Test 2)
Two 100 mm x 300 mm x 6 mm slate boards were placed side by side and the joint between the boards (width 10 mm) was filled with a two-component polyurethane sealant (corresponding to F-25LM-8020 (PU-2) of JIS A5758 "Architectural sealant") to serve as the substrate to be painted.
The entire surface of the above substrate was spray-painted with a water-based undercoat material at a coating amount of 1 kg/ ^m2 , dried for 24 hours, and then spray-painted with an acrylic resin-based water-based paint (corresponding to JIS K5660 "glossy synthetic resin emulsion paint". Color: light brown.) as a finishing material at a coating amount of 0.3 kg/ ^m2 and dried for 7 days to prepare test specimen [II]. Note that painting and drying were all performed under standard conditions.

The coating appearance (state of defects such as blistering, peeling, and cracking) of the specimen [II] prepared by the above method was visually confirmed, and then the adhesion of the area including the joints was evaluated by the cross-cut tape method according to JIS K5600-5-6. The evaluation criteria are as follows.
AA: No abnormality in the appearance of the coating film. Missing area is less than 2% A: No abnormality in the appearance of the coating film. Missing area is 2% to less than 10% B: No abnormality in the appearance of the coating film. Missing area is 10% to less than 20% C: No abnormality in the appearance of the coating film. Missing area is 20% or more D: Abnormality in the appearance of the coating film.

(Test 3)
Specimen [II] prepared in the same manner as in Test 2 above was immersed in water for 10 days, after which the appearance of the coating (state of defects such as blistering, peeling, and cracking) was visually inspected, and then the adhesion of the area including the joints was evaluated using the cross-cut tape method according to JIS K5600-5-6. The evaluation criteria were the same as in Test 2.

(Test 4)
For specimen [II] prepared in the same manner as in Test 2 above, a hot-cold cycle test was carried out for a total of 10 cycles, consisting of 18 hours of water immersion, 3 hours of standing at -20°C, and 3 hours of standing at 50°C. The coating appearance (state of defects such as blistering, peeling, and cracking) was then visually inspected, and the adhesion of the area including the joints was evaluated using the cross-cut tape method according to JIS K5600-5-6. The evaluation criteria were the same as in Test 2.

(Test Results)
The test results are shown in Table 1. In Examples 1 to 9, good results were obtained in all tests.

Claims (5)

A water-based primer material comprising an acrylic silicone resin emulsion and a pigment,
The acrylic silicone resin emulsion contains 20% by weight or more of an aromatic monomer in its resin constituents,
The water-based primer material contains an extender pigment as the pigment, and has a pigment volume concentration of 30 to 90%. The acrylic silicone resin emulsion contains, as a resin component,
(a) a (meth)acrylic acid alkyl ester having an alkyl main chain having 3 or more carbon atoms;
(b) an aromatic monomer, and (c) an alkoxysilane compound;
The water-based primer according to claim 1, characterized in that it comprises The acrylic silicone resin emulsion contains, as a resin component,
(a1) a (meth)acrylic acid alkyl ester having an alkyl main chain having 3 to 5 carbon atoms;
(a2) (meth)acrylic acid alkyl ester having an alkyl main chain having 6 or more carbon atoms;
(b) an aromatic monomer, and (c) an alkoxysilane compound;
The water-based primer according to claim 1, characterized in that it comprises The water-based primer described in any one of claims 1 to 3, characterized in that it is for use on surfaces having joints. A decorative finishing method in which a water-based undercoat material is applied to a surface having a joint, and then a finishing material is applied to the surface.
A decorative finishing method, comprising using the water-based undercoat material according to any one of claims 1 to 3 as the water-based undercoat material.