JP4846255B2 - Water-based paint - Google Patents

Description

  The present invention relates to a novel water-based paint.

Conventionally, in the paint field, solvent-based paints that use organic solvents such as aromatic hydrocarbons have been the mainstream, but in recent years, water is used as a medium from the standpoint of environmental issues, resource saving, occupational safety and health, etc. Switching to water-based paint is progressing.
Many water-dispersible resins (aqueous resin emulsions) are used as binders in water-based paints. In particular, acrylic resin emulsions obtained by copolymerization of alkyl acrylates and alkyl methacrylates are widely used because they exhibit excellent performance in coating properties such as weather resistance, water resistance, and chemical resistance. It has been.

  In such an acrylic resin emulsion, an emulsifier such as an anionic surfactant or a nonionic surfactant is usually used for the purpose of ensuring stability during emulsion polymerization and coating production, or stability during long-term storage. in use. However, surfactants generally have a property that tends to cause bubbles. Therefore, in the case where the acrylic resin emulsion as described above is made into a paint, a formulation in which an antifoaming agent is added is often employed. For example, Japanese Patent Application Laid-Open No. 8-48912 (Patent Document 1) describes a synthetic resin emulsion paint composed of an acrylic resin emulsion, a viscosity imparting agent, a white pigment, an antifoaming agent, and the like.

JP-A-8-48912

  Such an antifoaming agent is a component that acts effectively in reducing bubbles. However, on the other hand, there is a risk of causing various problems after the coating film is formed. For example, in clear type paints, there are cases where the vividness of the coating film is lowered, and in glossy type paints, the glossiness of the paint film becomes insufficient. In addition, the defoaming agent component remaining on the surface of the coating film may induce adhesion of contaminants, or may cause a decrease in adhesion when performing color change or touch-up (recoating).

  The present invention has been made in view of the above-described problems, and in an aqueous coating having an acrylic resin emulsion as a binder, it effectively reduces bubbles without adversely affecting the properties and physical properties of the formed coating film. It is intended to do.

  As a result of intensive studies to achieve the above object, the present inventor has conceived that a specific easily water-soluble solvent and a hardly water-soluble solvent are used in combination, and has completed the present invention.

  That is, the present invention has the following characteristics.

1. At least one or more (meth) acrylic acid alkyl ester and at least one or more carboxyl group-containing polymerizable monomer, wherein the (meth) acrylic acid alkyl ester has a constituent ratio of 70% by weight or more, carboxyl group-containing polymerizable monomer The monomer group having a composition ratio of 1% by weight or more and 10% by weight or less is emulsion-polymerized in the presence of an anionic surfactant and a nonionic surfactant of HLB 14 or more in the range of 10:90 to 90:10. Water dispersible resin (A) obtained by
An essential component is a readily water-soluble solvent (B) having a solubility in water at 20 ° C. of 10 g / 100 g or more, and a poorly water-soluble solvent (C) having a solubility in water at 20 ° C. of less than 10 g / 100 g,
The readily water-soluble solvent (B) is ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monomethyl ether acetate, ethylene Glycol monoethyl ether acetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol dimethyl ether, diethylene Glycol methyl ethyl ether, diethylene glycol diethyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, Propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether Ether, 1,3-butanediol, 1,4-butanediol, a solvent selected 1,5-pentanediol, hexylene glycol, diacetone alcohol, from N- methylpyrrolidone,
The poorly water-soluble solvent (C) is ethylene glycol monohexyl ether, ethylene glycol-2-ethylhexyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol dibutyl ether, diethylene glycol monohexyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dibutyl ether, propylene glycol Monobutyl ether, propylene glycol phenyl ether, propylene glycol diacetate, dipropylene glycol monobutyl ether, dipropylene glycol tertiary butyl ether, tripropylene glycol monobutyl ether, octylene glycol, 2-ethylhexylene glycol, 2,2,4-trimethyl -1,3-pen Emissions monoisobutyrate, a solvent selected from benzyl alcohol,
The water-dispersible resin (A) is 3 to 50% by weight in terms of solid content, the easily water-soluble solvent (B) is 0.01 to 10% by weight, and the hardly water-soluble solvent (C) is 0.01 to 10% by weight. %, And the weight ratio of the readily water-soluble solvent (B) to the hardly water-soluble solvent (C) is 95: 5 to 5:95.
2.1. In which a mixed solution of a readily water-soluble solvent (B) and a hardly water-soluble solvent (C) is prepared in advance, and the water-dispersible resin (A) and the mixed solution are prepared. 1. mixing, A method for producing a water-based paint as described in 1.

2. Item 1. The pigment volume concentration is 25% or less . The water-based paint described.

3. Item 1. The pigment volume concentration exceeds 25% . The water-based paint described.

4). Item 1. A method for producing a water-based paint according to any one of Items 1 to 3 .
A water solution characterized by preparing a mixed solution of the easily water-soluble solvent (B) and the hardly water-soluble solvent (C) in advance, and mixing the water-based paint containing the water-dispersed resin (A) with the mixed solution. Manufacturing method of paint.

  In the water-based paint of the present invention, bubbles in the paint can be effectively reduced even if the use of an antifoaming agent is refrained. And in the coating film formed with this invention composition, the various problems resulting from an antifoamer can be improved. Specifically, a clear-type paint can form a coating film excellent in sharpness, and a glossy-type paint can obtain a coating film with high gloss. Furthermore, the stain resistance of the coating film, the adhesion during recoating, and the like can be improved.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The water-dispersible resin (A) in the present invention is obtained by emulsion polymerization of a monomer group containing at least one (meth) acrylic acid alkyl ester.

Among these, (meth) acrylic acid alkyl ester is a main component of the resin skeleton. 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.
Specific examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (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, Examples include cyclohexyl (meth) acrylate, phenyl (meth) acrylate, and benzyl (meth) acrylate. These can be used alone or in combination of two or more.

The component ratio of the (meth) acrylic acid alkyl ester in the monomer group is usually 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more. Although an upper limit is not specifically limited, Usually, it is 99.8 weight% or less, Preferably it is 99.5 weight% or less, More preferably, it is 99 weight% or less.
If the constituent ratio of the (meth) acrylic acid alkyl ester is within such a range, good physical properties in terms of weather resistance, water resistance, chemical resistance and the like can be ensured. Moreover, in order to ensure the stability of the emulsion using such (meth) acrylic acid alkyl ester, it is necessary to have a surfactant suitable for the stability, but in the present invention, the amount of surfactant used is relatively large. Even so, a sufficient bubble reduction effect can be obtained.

In the water dispersible resin (A), a carboxyl group-containing monomer can be used as a monomer component. The carboxyl group-containing monomer is a compound having both a carboxyl group and a polymerizable unsaturated bond in the molecule. In the present invention, the use of such a monomer increases the stability of the water-dispersible resin and can reduce the amount of surfactant used as a bubble generation source.
Specific examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid or a monoalkyl ester thereof, itaconic acid or a monoalkyl ester thereof, fumaric acid or a monoalkyl ester thereof, and the like. Among these, at least one selected from acrylic acid and methacrylic acid is particularly preferable.
The constitutional ratio of the carboxyl group-containing monomer in the monomer group is usually 0.2 wt% or more and 20 wt% or less, preferably 0.5 wt% or more and 15 wt% or less, more preferably 1 wt% or more and 10 wt% or less. .

The water-dispersible resin (A) may contain a polymerizable monomer other than the above as a constituent component as necessary. Examples of such polymerizable monomers include amino group-containing monomers such as N-methylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and dimethylaminoethyl vinyl ether; 2-hydroxyethyl (meth) acrylate, hydroxy Hydroxyl group-containing monomers such as propyl (meth) acrylate; vinyl ester monomers such as vinyl acetate and vinyl propionate; nitrile group-containing monomers such as acrylonitrile and methacrylonitrile; styrene, 2-methylstyrene, vinyltoluene, t-butylstyrene, Aromatic monomers such as chlorostyrene, vinylanisole, vinylnaphthalene and divinylbenzene; polymers such as acrylamide, methacrylamide, maleic amide and N-methylol (meth) acrylamide Group containing monomers: Epoxy group containing monomers such as glycidyl (meth) acrylate, diglycidyl (meth) acrylate, and allyl glycidyl ether; Group-containing monomers; alkoxysilyl group-containing monomers such as vinyltrimethoxysilane, vinyltriethoxysilane, and γ- (meth) acryloyloxypropyltrimethoxysilane; vinylidene halide monomers such as vinylidene chloride and vinylidene fluoride; other, ethylene , Propylene, isoprene, butadiene, vinyl pyrrolidone, vinyl chloride, vinyl ether, vinyl ketone, vinyl amide, chloroprene and the like.
The composition ratio of the polymerizable monomer in the monomer group is usually 50% by weight or less, preferably 40% by weight or less, more preferably 30% by weight or less.

  The water-dispersible resin (A) in the present invention is obtained by emulsion polymerization of the above monomer group in the presence of an anionic surfactant and / or a nonionic surfactant having an HLB of 10 or more. Such a surfactant greatly contributes to the improvement of the stability of the emulsion, but on the other hand, it has the property of easily causing bubbles. In the present invention, even when such a surfactant is used, a sufficient bubble reduction effect can be exhibited.

  Specific examples of the anionic surfactant include sulfonic acid alkali metal salts such as sodium dodecylbenzene sulfonate, sodium lauryl naphthalene sulfonate, sodium stearyl diphenyl ether disulfonate; sodium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, Examples thereof include sulfate alkali metal salts such as sodium polyoxyethylene octylphenyl ether sulfate. As such an anionic surfactant, a non-polymerizable one is usually used.

  Examples of the nonionic surfactant having an HLB of 10 or more include polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene distearate, polyoxyethylene cetyl ether and the like. If the HLB value is less than 10, emulsion polymerization may not proceed smoothly. In the present invention, even when a nonionic surfactant having an HLB of 13 or more, or 14 or more is used, a sufficient bubble reduction effect can be obtained.

The amount of the surfactant used is usually 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the total amount of the monomer group. In addition, the usage-amount of surfactant said here is the total amount of anionic surfactant and HLB10 or more nonionic surfactant.
Moreover, when using together anionic surfactant and nonionic surfactant more than HLB10, the range whose these weight ratios (anionic surfactant: nonionic surfactant) will be 10: 90-90: 10 May be set as appropriate. Thus, if a surfactant is used in combination, the stability of the emulsion can be increased.

  The water-dispersible resin (A) can be produced by emulsion polymerization of a monomer group obtained by appropriately mixing the polymerizable monomers. A known method may be employed as the polymerization method, and feed emulsion polymerization, seed emulsion polymerization, etc. may be employed in addition to normal emulsion polymerization. In the polymerization, an initiator, a dispersant, a polymerization inhibitor, a polymerization inhibitor, a buffer, a chain transfer agent, and the like can be used.

  The glass transition temperature of the water dispersible resin (A) can be adjusted by selecting the kind of the polymerizable monomer, the mixing ratio, and the like. The glass transition temperature may be appropriately set in consideration of the final use of the water-dispersible resin, but is usually about -60 to 80 ° C, preferably about -30 to 50 ° C. In addition, the glass transition temperature of water-dispersible resin (A) can be calculated | required with the formula of Fox.

  In the water dispersible resin (A) in the present invention, it is desirable to adjust the pH to 7 to 10 with a basic compound. By adjusting the pH within such a range, the carboxyl group derived from the carboxyl group-containing monomer can be dissociated, and the stability of the water-dispersible resin can be improved. As a result, the use of a surfactant in the water-dispersible resin The amount can be reduced. Furthermore, the bubble reduction effect can be enhanced by mixing such a basic compound.

The mixing amount of the basic compound may be within a range in which the pH of the water-dispersible resin becomes a predetermined value, but is usually 0.01 to 10 parts by weight, preferably 0 with respect to 100 parts by weight of the total amount of the monomer group. 0.05 to 5 parts by weight. With such a mixing amount, a sufficient effect can be obtained in the stability of the emulsion, the bubble reduction ability and the like.
The timing of mixing the basic compound is not particularly limited, and may be any before, during or after the polymerization of the water-dispersible resin, or may be during the production of an aqueous paint.

  Examples of basic compounds include ammonia, monoethylamine, diethylamine, triethylamine, isopropylamine, diisopropylamine, aminoethanol, 1-amino-2-propanol, 2-amino-2-methyl-1-propanol, 2- (methyl Amino) -2-methyl-1-propanol, N, N-dimethylethanolamine, N- (2-aminoethyl) ethanolamine, N-methylethanolamine, sodium methylsiliconate, sodium hydroxide, potassium hydroxide, water Calcium oxide, calcium oxide, anhydrous sodium carbonate, sodium hydrogen carbonate, ammonium carbonate, ammonium hydrogen carbonate and the like can be mentioned.

  In the water-based paint of the present invention, the water-dispersible resin (A) functions as a binder. The mixing ratio of the water-dispersible resin (A) in the water-based paint is usually 3 to 50% by weight in terms of solid content. When the mixing ratio of the water dispersible resin (A) is within such a range, bubbles are likely to be generated, but in the present invention, the bubble generation can be sufficiently reduced. In particular, in the present invention, even when the lower limit of the mixing ratio (in terms of solid content) of the water-dispersible resin (A) is 10% by weight or more, and even 20% by weight or more, excellent effects can be obtained. .

In the present invention, with respect to the water-dispersible resin (A), a water-soluble solvent (B) having a solubility in water of 10 g / 100 g or more (hereinafter also referred to simply as “water-soluble solvent”), and water solubility Is less than 10 g / 100 g of a poorly water-soluble solvent (C) (hereinafter also referred to simply as “a poorly water-soluble solvent”). In the present invention, by using these two components having different solubility characteristics in water, an excellent bubble reduction effect can be obtained. Although its mechanism of action is not clear, the presence of the readily water-soluble solvent (B) in the paint makes it difficult for the poorly water-soluble solvent (C) to diffuse, and it effectively reaches the bubbles present in the paint and breaks. It is presumed to exert a foaming action. That is, in the present invention, it is considered that the effect of reducing bubbles is exerted by the action of the readily water-soluble solvent (B) as a carrier of the hardly water-soluble solvent (C).
The solubility in water in the present invention is the maximum mass (g) that can be dissolved in 100 g of water. The measurement temperature is 20 ° C.

The readily water-soluble solvent (B) is not particularly limited as long as the solubility in water is within the above range, but specific compounds include, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl. Ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether , Diethylene glycol monobutyl ether, diethylene Recall monoethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, propylene glycol, propylene glycol monomethyl ether, propylene glycol mono Ethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether Dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, 1,3-butanediol, 1,4-butanediol, 1,5-pentadiol, hexylene glycol, diacetone alcohol, N-methylpyrrolidone, etc. Can be mentioned.
The solubility of the readily water-soluble solvent (B) in water is 10 g / 100 g or more, preferably 20 g / 100 g or more, more preferably ∞.

Examples of the poorly water-soluble solvent (C) include ethylene glycol monohexyl ether, ethylene glycol-2-ethylhexyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol dibutyl ether, diethylene glycol monohexyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dibutyl ether, Propylene glycol monobutyl ether, propylene glycol phenyl ether, propylene glycol diacetate, dipropylene glycol monobutyl ether, dipropylene glycol tertiary butyl ether, tripropylene glycol monobutyl ether, octylene glycol, 2-ethylhexylene glycol, 2,2,4 -Trimethyl-1 3-pentanediol mono-isobutyrate, benzyl alcohol and the like.
The solubility of the poorly water-soluble solvent (C) in water is less than 10 g / 100 g, preferably less than 5 g / 100 g, more preferably less than 4 g / 100 g.

  The weight ratio of the readily water-soluble solvent (B) and the hardly water-soluble solvent (C) is usually 95: 5 to 5:95, preferably 90:10 to 10:90, more preferably 80:20 to 20: 80, more preferably 70:30 to 30:70. In the present invention, an excellent bubble reduction effect can be obtained by using both components in such a ratio.

The method for mixing the above-mentioned components is not particularly limited, but in order to sufficiently obtain the effects of the present invention, it is desirable to mix in the following procedure.
(A) A mixed solution of a readily water-soluble solvent (B) and a hardly water-soluble solvent (C) is prepared in advance, and the water-dispersed resin (A) and the mixed solution are mixed.
(A) After mixing the water-dispersed resin (A) and the readily water-soluble solvent (B), the poorly water-soluble solvent (C) is mixed.
Among these, according to the method (a), a more excellent effect can be obtained.

  The mixing ratio of the readily water-soluble solvent (B) in the aqueous paint of the present invention is usually 0.01 to 10% by weight, preferably 0.05 to 8% by weight, more preferably 0.1 to 5% by weight. . The mixing ratio of the poorly water-soluble solvent (C) is usually 0.01 to 10% by weight, preferably 0.05 to 8% by weight, more preferably 0.1 to 5% by weight in the aqueous coating material. When the mixing ratio of the easily water-soluble solvent (B) or the hardly water-soluble solvent (C) is too small, it is difficult to obtain the effect of reducing bubbles. When the mixing ratio is too large, there is a possibility that problems such as taking more time than necessary for drying the coating film and causing stickiness on the surface of the coating film may occur.

  In addition to the above-described components, the water-based paint of the present invention can be mixed with components that can be used in ordinary paints. Examples of such components include pigments, aggregates, fibers, thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreezing agents, antiseptics, antifungal agents, anti-algae agents, and antibacterial agents. Agents, dispersants, adsorbents, ultraviolet absorbers, antioxidants, light stabilizers, catalysts, crosslinking agents and the like. Such components are desirably mixed with the water-dispersed resin (A) before mixing the readily water-soluble solvent (B) or the hardly water-soluble solvent (C).

Among these, color pigments, extender pigments and the like that can be generally blended into paints can be used as the pigment. Examples of color pigments include titanium oxide, zinc oxide, carbon black, lamp black, bone black, graphite, black iron oxide, copper chrome black, cobalt black, copper manganese iron black, red potato, molybdate orange, permanent red, and permanent. Carmine, anthraquinone red, perylene red, quinacridone red, yellow iron oxide, titanium yellow, first yellow, benzimidazolone yellow, chrome green, cobalt green, phthalocyanine green, ultramarine, bitumen, cobalt blue, phthalocyanine blue, quinacridone violet, dioxazine Violet etc. are mentioned. The average particle diameter of the color pigment is usually less than 1 μm (preferably 0.5 μm or less).
Examples of extender pigments include heavy calcium carbonate, precipitated calcium carbonate, kaolin, talc, clay, porcelain clay, china clay, barium sulfate, barium carbonate, silica, diatomaceous earth, and resin beads. The average particle diameter of these extender pigments is usually 1 μm to 100 μm (preferably 2 μm to 80 μm).

  The water-based paint of the present invention can be mixed with an antifoaming agent if necessary, but the mixing amount is preferably 2% by weight or less in the water-based paint, more preferably 1% by weight or less, and further Preferably it is 0.5 wt% or less. In this invention, even if it is a case where there are few amounts of mixing of an antifoamer in this way, the bubble in a coating material can be reduced effectively. Moreover, various problems caused by the antifoaming agent in the formed coating film can be improved. In addition, the antifoamer said here has a mineral oil and / or a silicone compound as a main component.

  In the present invention, various forms of paints can be designed by combining and mixing the above components. Specific forms of paint include, for example, clear paint, glossy paint, matte paint, and the like.

(1) Clear coating The clear coating contains components (A), (B), and (C) as essential components, and the formed coating film has transparency. As long as the transparency of the formed coating film is within a range that can be secured, coloring can be performed with a coloring pigment or the like. Further, the gloss of the formed coating film can be adjusted by an extender pigment or the like. The pigment volume concentration in the clear coating is usually 10% or less (preferably 5% or less).
When the present invention is applied to such a clear coating, it is possible to form a coating film excellent in sharpness, and to improve the stain resistance of the coating film, adhesion during recoating, and the like.

(2) Glossy paint The glossy paint is a paint capable of forming a colored and glossy coating film, and contains (A) component, (B) component, (C) component and a colored pigment as essential components. The glossy paint is specified in JIS K5660 “Glossy Synthetic Resin Emulsion Paint”, and its specular gloss is 70 or more (preferably 75 or more, more preferably 80 or more). In a glossy paint, a desired color can be expressed by appropriately setting the type and blending ratio of the color pigment. In such a glossy paint, a thick film type coating material such as a single-layer elastic coating material can be designed by mixing an extender pigment or the like as long as the glossiness is not impaired. The mixing ratio of the pigment in the glossy paint is usually set so that the pigment volume concentration is 25% or less (preferably 20% by weight or less).
When the present invention is applied to such a glossy paint, a coating film with high gloss can be obtained. Furthermore, the stain resistance of the coating film, the adhesion during recoating, and the like can be improved.

(3) Matte paints Matte paints are paints that can form colored paint films with reduced gloss, and in addition to (A), (B), and (C) components, coloring pigments and extender pigments are essential. It is included as a component. The specular gloss of the mat paint is usually 40 or less (preferably 20 or less, more preferably 10 or less). The glossiness of the matte paint can be appropriately adjusted depending on the type of extender pigment used, the particle diameter, the mixing ratio, and the like. By such adjustment, in addition to what is commonly referred to as frosting, it is also possible to design paints referred to as 3 minutes, 5 minutes, etc. In the matte paint, the pigment amount may be adjusted so that the pigment volume concentration exceeds 25% (preferably 30% by weight or more and 70% by weight or less).
In the present invention, as such a mat paint, a thick film type coating material such as a mat type single-layer elastic coating material or a multilayer finishing coating material main material can be designed. In the multi-layer finish coating main material, it is not necessary to use a color pigment.
In such a matte paint, a dispersant is usually used in order to stably disperse a large amount of pigment. When the dispersant is added to the paint, bubbles are likely to be generated, but in the present invention, the bubbles can be effectively reduced by the action of the components (B) and (C). The mixing ratio of the dispersant is generally about 0.05 to 1% by weight in the water-based paint, although it depends on the kind and amount of the pigment.

The water-based paint of the present invention as described above can be applied by a known method. As a coating method, for example, spray coating, roller coating, brush coating, or the like can be employed. Among these, in the present invention, even when coating is performed with a roller, an excellent bubble reduction effect can be obtained.
The coating amount at the time of painting can be appropriately set according to the form of the paint, the desired finish appearance, etc., but is usually about 0.1 to 3 kg / m2. At the time of painting, the viscosity of the paint can be appropriately adjusted by diluting with water or the like. The dilution ratio is usually about 0 to 20% by weight.
The coating and drying of the paint of the present invention may be usually performed at room temperature (about 5 to 40 ° C.), but may be performed at a high temperature as necessary.

  Examples are given below to clarify the features of the present invention.

(Synthesis example)
A reaction vessel was charged with 50 parts by weight of deionized water, and the temperature was raised to 70 ° C. while stirring and nitrogen replacement. Separately prepared emulsion monomer (3 parts by weight of sodium dodecylbenzenesulfonate, 6 parts by weight of polyoxyethylene phenyl ether (HLB15.0) and 0.9 parts by weight of ammonium persulfate were dissolved in 250 parts by weight of deionized water. In an aqueous solution, 62 parts by weight of styrene, 55 parts by weight of methyl methacrylate, 170 parts by weight of 2-ethylhexyl acrylate, 9 parts by weight of acrylic acid, and 4 parts by weight of acrylamide were continuously added dropwise over 3 hours. After completion of the dropwise addition, the mixture was aged for 3 hours, cooled to 30 ° C., and then added with 25 wt% aqueous ammonia as a basic compound to adjust the pH to 8.2 to obtain a synthetic resin emulsion 1.

(Test Example 1)
In Test Example 1, the following test was performed using a mixed solution (weight ratio 50:50) of diethylene glycol diethyl ether (water solubility ∞) and diethylene glycol monohexyl ether (water solubility 1.7 g / 100 g) as a solvent. .

-Foam-breakability test 50 parts by weight of the synthetic resin emulsion 1 obtained by the above method was prepared, and 50 parts by weight of water was mixed uniformly into this test tube. After shaking 50 times, the solvent was reduced to 0. 2 parts by weight were added. At this time, the time until the volume of the bubbles was halved was measured. The evaluation was as follows: A: less than 10 seconds, O: 10 seconds or more and less than 30 seconds, Δ: 30 seconds or more and less than 60 seconds, and X: 60 seconds or more.

・ Foam suppression test 50 parts by weight of the synthetic resin emulsion 1 was prepared, 50 parts by weight of water and 2 parts by weight of the solvent were mixed uniformly, and the mixture was allowed to stand at room temperature for 16 hours. The volume increase rate due to bubbles immediately after shaking 50 times was measured. Evaluation was made into ○: less than 100% and x: 100% or more.

・ Film coat clarity test 50 parts by weight of the synthetic resin emulsion 1 was prepared, 50 parts by weight of water and 2 parts by weight of the solvent were mixed uniformly, and then allowed to stand at room temperature for 16 hours. Was applied to a glass plate with a WET film thickness of 0.15 mm. After drying at room temperature for 48 hours, the clarity of the coating film was visually confirmed. The evaluation was as follows: ○: no abnormality, x: cloudy occurrence.

(Test Example 2)
In Test Example 2, a mixed solution (weight ratio 50:50) of diethylene glycol diethyl ether (water solubility ∞) and diethylene glycol dibutyl ether (water solubility 0.3 g / 100 g) was used in the same manner as in Test Example 1. The test was conducted.

(Test Example 3)
In Test Example 3, a mixed solution (weight ratio 50:50) of tripropylene glycol monomethyl ether (water solubility ∞) and tripropylene glycol monobutyl ether (water solubility 3 g / 100 g) was used as a solvent. The test was conducted in the same manner.

(Test Example 4)
In Test Example 4, a test was conducted using a mixed solution (weight ratio 50:50) of dipropylene glycol monopropyl ether (water solubility 19 g / 100 g) and diethylene glycol dibutyl ether (water solubility 0.3 g / 100 g) as a solvent. The test was conducted in the same manner as in Example 1.

(Test Example 5)
In Test Example 5, the test was performed in the same manner as in Test Example 1 using diethylene glycol diethyl ether (water solubility ∞) as a solvent.

(Test Example 6)
In Test Example 6, the test was conducted in the same manner as Test Example 1 using diethylene glycol monohexyl ether (water solubility 1.7 g / 100 g) as a solvent.

(Test Example 7)
In Test Example 7, the test was conducted in the same manner as Test Example 1 using a silicone-based antifoaming agent instead of the solvent.

  The test results are shown in Table 1. In Test Examples 1 to 4 in which two types of solvents having different solubility in water were used in combination, better results were obtained than Test Examples 5 to 6 in which the solvent was used alone.

(Test Example 8)
30 parts by weight of the synthetic resin emulsion 1 obtained in the above synthesis example was prepared in a container, and 3 parts by weight of a cellulose-based thickener and 0.2 parts by weight of a polycarboxylic acid-based dispersant were stirred while stirring with a stirring blade. Next, 2 parts by weight of a mixed solution (weight ratio 50:50) of diethylene glycol diethyl ether (water solubility ∞) and diethylene glycol dibutyl ether (water solubility 0.3 g / 100 g) is mixed as a solvent. The coating material 1 was manufactured by mixing about 60 minutes after mixing 60 weight part of quality calcium carbonate (average particle diameter of 4 micrometers). The coating material 1 has a pigment volume concentration of 60%.
This coating material 1 is applied to a slate plate previously coated with a primer at a coating amount of 0.8 kg / m ² using a mastic roller, and then dried and cured at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours. A test plate was obtained.

  On the other hand, coating material 2 was produced in the same manner as coating material 1 except that diethylene glycol diethyl ether (water solubility ∞) was used instead of the above mixed solution as a solvent. Moreover, the coating material 3 was manufactured by the method similar to the coating material 1 except having used diethylene glycol dibutyl ether (solubility in water 0.3g / 100g) instead of the said mixed solution. About the coating material 2 and the coating material 3, it painted by the method similar to the coating material 1, respectively, and produced the test board.

  The surface of the obtained test plate was observed to confirm the occurrence of pinholes. As a result, the coating film of the coating material 1 clearly had fewer pinholes than the coating films of the coating material 2 and the coating material 3, and had a good finished appearance.

Claims (2)

At least one or more (meth) acrylic acid alkyl ester and at least one or more carboxyl group-containing polymerizable monomer, wherein the (meth) acrylic acid alkyl ester has a constituent ratio of 70% by weight or more, carboxyl group-containing polymerizable monomer The monomer group having a composition ratio of 1% by weight or more and 10% by weight or less is emulsion-polymerized in the presence of an anionic surfactant and a nonionic surfactant of HLB 14 or more in the range of 10:90 to 90:10. Water dispersible resin (A) obtained by
An essential component is a readily water-soluble solvent (B) having a solubility in water at 20 ° C. of 10 g / 100 g or more, and a poorly water-soluble solvent (C) having a solubility in water at 20 ° C. of less than 10 g / 100 g,
The readily water-soluble solvent (B) is ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monomethyl ether acetate, ethylene Glycol monoethyl ether acetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol dimethyl ether, diethylene Glycol methyl ethyl ether, diethylene glycol diethyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, Propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether Ether, 1,3-butanediol, 1,4-butanediol, a solvent selected 1,5-pentanediol, hexylene glycol, diacetone alcohol, from N- methylpyrrolidone,
The poorly water-soluble solvent (C) is ethylene glycol monohexyl ether, ethylene glycol-2-ethylhexyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol dibutyl ether, diethylene glycol monohexyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dibutyl ether, propylene glycol Monobutyl ether, propylene glycol phenyl ether, propylene glycol diacetate, dipropylene glycol monobutyl ether, dipropylene glycol tertiary butyl ether, tripropylene glycol monobutyl ether, octylene glycol, 2-ethylhexylene glycol, 2,2,4-trimethyl -1,3-pen Emissions monoisobutyrate, a solvent selected from benzyl alcohol,
The water-dispersible resin (A) is 3 to 50% by weight in terms of solid content, the easily water-soluble solvent (B) is 0.01 to 10% by weight, and the hardly water-soluble solvent (C) is 0.01 to 10% by weight. %, And the weight ratio of the readily water-soluble solvent (B) to the hardly water-soluble solvent (C) is 95: 5 to 5:95. A method for producing the water-based paint according to claim 1, wherein a mixed solution of a readily water-soluble solvent (B) and a hardly water-soluble solvent (C) is prepared in advance, and the water-dispersible resin (A) and the water-dispersible resin (A) The method for producing a water-based paint according to claim 1, wherein the mixed solution is mixed.