Water-based coating material

Abstract

To provide a water-based coating material that demonstrates excellent stain resistance along with resistance to cracking.SOLUTION: A water-based coating material of the present invention employs, as a binder, a three-layer-structured synthetic resin emulsion having a specific particle size and a specific glass transition temperature.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous coating material having excellent stain resistance and crack resistance.

Background Art

[0002] In recent years, in coating materials used for building and civil structures, in consideration of pollution-free and safety, a conversion from a solvent-based type using an organic solvent as a solvent to an aqueous type using water as a solvent has been attempted.

[0003] As an aqueous coating material, for example, there is a technique using a synthetic resin emulsion as a binder. In recent years, those adopting a multi-layer structured synthetic resin emulsion and having a coating film performance comparable to that of the solvent-based type have also appeared. (For example, Patent Document 1)

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For example, in Patent Document 1, a two-layer structured synthetic resin emulsion in which the glass transition temperature of the inner layer is 5 to 60°C and the glass transition temperature of the outer layer is 50 to 100°C is adopted to improve stain resistance and elastic suitability. However, in the above synthetic resin emulsion, it may be difficult to obtain a higher degree of elastic suitability. In the two-layer structured synthetic resin emulsion, there are limitations in improving physical properties such as stain resistance and crack resistance.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present invention has succeeded in realizing excellent stain resistance and excellent crack resistance by adopting a three-layer structured synthetic resin emulsion having a specific glass transition temperature and a specific particle diameter as a binder, and has completed the present invention.

[0007] That is, the present invention has the following features. 1. An aqueous coating material using a synthetic resin emulsion as a binder, wherein the synthetic resin emulsion has an inner layer with a glass transition temperature of more than 35°C and 120°C or less, an intermediate layer with a glass transition temperature of more than -10°C and 45°C or less, an outer layer with a glass transition temperature of -60°C or more and 10°C or less, the difference between the glass transition temperature of the inner layer and the glass transition temperature of the intermediate layer (inner layer Tg - intermediate layer Tg) is 35°C or more, the difference between the glass transition temperature of the intermediate layer and the glass transition temperature of the outer layer (intermediate layer Tg - outer layer Tg) is more than -10°C and less than 35°C, and is a multilayer structured synthetic resin emulsion having an average particle diameter of 50 nm or more and 300 nm or less.

Effects of the Invention

[0008] The aqueous coating material of the present invention has excellent stain resistance and excellent crack resistance.

Modes for Carrying Out the Invention

[0009] Hereinafter, modes for carrying out the present invention will be described.

[0010] The present invention is an aqueous coating material using a synthetic resin emulsion as a binder, wherein the synthetic resin emulsion has an inner layer with a glass transition temperature of more than 35°C and 120°C or less (preferably 40°C or more and 110°C or less, more preferably 45°C or more and 100°C or less), The glass transition temperature of the intermediate layer is above -10°C and below or equal to 45°C (preferably above -5°C and below or equal to 35°C, more preferably above 0°C and below or equal to 25°C), The glass transition temperature of the outer layer is above or equal to -60°C and below or equal to 10°C (preferably above or equal to -55°C and below or equal to 5°C, more preferably above or equal to -50°C and below or equal to 0°C), The difference between the glass transition temperature of the inner layer and the glass transition temperature of the intermediate layer (inner layer Tg - intermediate layer Tg) is 35°C or more (preferably 40°C or more and 130°C or less, more preferably 45°C or more and 110°C or less), The difference between the glass transition temperature of the intermediate layer and the glass transition temperature of the outer layer (intermediate layer Tg - outer layer Tg) is above -10°C and less than 35°C (preferably above -5°C and below or equal to 30°C, more preferably above 0°C and less than 25°C), It is characterized by being a multilayer structured synthetic resin emulsion with an average particle diameter of 50 nm or more and 300 nm or less (preferably 50 nm or more and less than 300 nm, more preferably 70 nm or more and 250 nm or less).

[0011] The synthetic resin emulsion of the present invention is provided with an intermediate layer between the outer layer and the inner layer, and by setting the glass transition temperature difference between the inner layer and the intermediate layer and the glass transition temperature difference between the intermediate layer and the outer layer, it is possible to achieve both excellent stain resistance and crack resistance.

[0012] Moreover, the total glass transition temperature of the outer layer, the intermediate layer, and the inner layer is preferably above 0°C and below or equal to 40°C (more preferably above 5°C and below or equal to 35°C).

[0013] Note that the glass transition temperature of each layer is a value obtained from the FOX calculation formula.

[0014] Also, the average particle diameter of the synthetic resin emulsion of the present invention is 50 nm or more and 300 nm or less, When the average particle diameter is too small, it is difficult to obtain the above effects due to each glass transition temperature, and it is not practical in terms of production. When the average particle diameter is too large, unevenness may be prominent due to the difference in glass transition temperature during and after film formation, and it may have an adverse effect on the film-forming physical properties.

[0015] The average particle diameter is a value measured by the dynamic light scattering method. Specifically, it is a value measured using a dynamic light scattering particle size distribution measuring device (LB-550, manufactured by Horiba, Ltd.), and the measurement temperature is 25°C.

[0016] In addition, for the resin composition ratios of the outer layer, intermediate layer, and inner layer of the synthetic resin emulsion of the present invention, the resin composition ratio of the inner layer is 10% by mass or more and 60% by mass or less (preferably 15% by mass or more and 55% by mass or less) based on the total synthetic resin emulsion, the resin composition ratio of the intermediate layer is 5% by mass or more and 50% by mass or less (preferably 10% by mass or more and 45% by mass or less) based on the total synthetic resin emulsion, and the resin composition ratio of the outer layer is 10% by mass or more and 50% by mass or less (preferably 15% by mass or more and 45% by mass or less) based on the total synthetic resin emulsion, which is preferable. In the present invention, one layer of the outermost layer of the synthetic resin emulsion is defined as the outer layer, one layer of the innermost layer is defined as the inner layer, and the layers existing in between are defined as the intermediate layer. That is, when there are two or more layers existing in the middle, they are all combined and regarded as the intermediate layer.

[0017] The synthetic resin emulsion of the present invention can be produced by polymerizing various monomers by a known method. For example, it can be obtained by mixing various monomers and various additives as required and performing three-stage polymerization by a commonly known polymerization method (emulsion polymerization method, suspension polymerization method, dispersion polymerization method, etc.). Also, it is not limited to three-stage polymerization, and methods such as one-stage, two-stage polymerization, or multi-stage polymerization, as well as dropwise polymerization, feed polymerization, etc. can also be used. The polymerization temperature is not particularly limited, but it may be about 20°C to 90°C, and the polymerization time is not particularly limited, but it may be about 1 hour to 24 hours.

[0018] Examples of the additives used during polymerization include water, emulsifier, initiator, solvent, dispersant, emulsion stabilizer, polymerization inhibitor, polymerization retarder, buffer, crosslinking agent, pH adjuster, chain transfer agent, catalyst, etc., and the necessary amounts may be added according to various polymerization methods and purposes.

[0019] As monomers, for example, carboxyl group-containing monomers such as (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, isocrotonic acid, salicylic acid, cinnamic acid, etc., hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxypentyl (meth)acrylate, 4-hydroxypentyl (meth)acrylate, 1-methyl-4-hydroxypentyl (meth)acrylate, 3-ethyl-3-hydroxyhexyl (meth)acrylate, 2-hydroxydecyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1-methyl-4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 2-methyl-8-hydroxyoctyl (meth)acrylate, 7-methyl-8-hydroxyoctyl (meth)acrylate, 9-hydroxynonyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, hydroxymethylcyclohexyl (meth)acrylate, etc., alkoxysilyl group-containing monomers such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, etc., (Meth)acrylamide, ethyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-n-propyl (meth)acrylamide, N-cyclopropyl (meth)acrylamide, N-(meth)acryloylpyrrolidine, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-methyl-N-ethyl (meth)acrylamide, N-methyl-N-isopropyl (meth)acrylamide, N-methyl-N-n-propyl (meth)acrylamide, N-methylol (meth)acrylamide, N-[3-(dimethylamino)propyl] (meth)acrylamide, vinylamide, N,N-methylenebisacrylamide, diacetone (meth)acrylamide, N-methylol (meth)acrylamide, acrylamide glycolic acid, methyl acrylamide glycolate, dimethoxyhydroxyethyl acrylamide and other amide group-containing monomers, Alkyl group-containing monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, i-butyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-hexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, trifluoroethyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, t-amyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, dodecenyl (meth)acrylate, octadecyl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-phenylethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, tripropylmethyl (meth)acrylate, triisopropylmethyl (meth)acrylate, tributylmethyl (meth)acrylate, triisobutylmethyl (meth)acrylate, trit-butylmethyl (meth)acrylate, etc. Cycloalkyl group-containing monomers such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclododecyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, etc. (Methoxy) polyethylene glycol (meth)acrylate, (methoxy) polypropylene glycol (meth)acrylate, (methoxy) polyethylene glycol - polypropylene glycol (meth)acrylate, (methoxy) polyethylene glycol allyl ether, (methoxy) polypropylene glycol allyl ether, (methoxy) polyethylene glycol - polypropylene glycol allyl ether and other alkylene glycol chain - containing monomers, Butyl vinyl benzylamine, vinyl phenylamine, p - aminostyrene, N,N - dimethylaminoethyl (meth)acrylate, N,N - dimethylaminopropyl (meth)acrylate, N,N - diethylaminoethyl (meth)acrylate, N,N - dimethylaminopropyl (meth)acrylate, N,N - diethylaminopropyl (meth)acrylate, N - [2 - (meth)acryloyloxyethyl]piperidine, N - [2 - (meth)acryloyloxyethyl]pyrrolidine, N - [2 - (meth)acryloyloxyethyl]morpholine, 4 - [N,N - dimethylamino]styrene, 4 - [N,N - diethylamino]styrene, 2 - vinylpyridine, 4 - vinylpyridine and other amino - group - containing monomers, Glycidyl (meth)acrylate, diglycidyl fumarate, 3,4 - epoxycyclohexyl (meth)acrylate, 3,4 - epoxyvinylcyclohexane, allyl glycidyl ether, ε - caprolactone - modified glycidyl (meth)acrylate, β - methyl glycidyl (meth)acrylate and other glycidyl - group - containing monomers, Diacetone (meth)acrylate, diacetone (meth)acrylamide, acrolein, vinyl methyl ketone, vinyl ethyl ketone, vinyl (iso)butyl ketone, acetonyl acrylate, acryloxyalkyl propanal, methacryloxyalkyl propanal, 2 - hydroxypropyl acrylate acetyl acetate, tandiol acrylate acetyl acetate, acetoacetoxyethyl (meth)acrylate, acetoacetoxyallyl ester and other carbonyl - group - containing monomers, (Meth)acrylonitrile and other nitrile - group - containing monomers, Isocyanate group-containing monomers such as methacryloyl isocyanate, Oxazoline group-containing monomers such as vinyl oxazoline, 2-vinyl-2-oxazoline, 2-propenyl 2-oxazoline, etc., Hydrazino group-containing monomers such as propylene-1,3-dihydrazine and butylene-1,4-dihydrazine, Acetoacetoxyl group-containing monomers such as acetoacetoxyethyl (meth)acrylate and acetoacetoxy allyl ester, Methylol group-containing monomers such as N-methylol (meth)acrylamide, Piperidyl group-containing monomers such as 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1-methylcarbamoyloxy-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonyloxy-2,2,6,6-tetramethylpiperidine, etc., Vinylidene halide-based monomers such as vinylidene fluoride, Aromatic vinyl-based monomers such as styrene, 2-methylstyrene, chlorostyrene, vinyltoluene, t-butylstyrene, vinyl anisole, vinyl naphthalene, etc., Sulfonic acid-containing monomers such as styrene sulfonic acid and vinyl sulfonic acid, Benzophenone monomers such as 2-hydroxy-4-(meth)acryloxybenzophenone, 2-hydroxy-5-(meth)acryloxybenzophenone, 2-hydroxy-4-{ (meth)acryloxy-ethoxy}benzophenone, 2-hydroxy-4-{ (meth)acryloxy-diethoxy}benzophenone, 2-hydroxy-4-{ (meth)acryloxy-triethoxy}benzophenone, Benzotriazole monomers such as 2-{2'-hydroxy-5'-(meth)acryloxyethylphenyl}-2H-benzotriazole, 2-{2'-hydroxy-5'-(meth)acryloxyethyl-3-t-butylphenyl}-2H-benzotriazole, 3-(meth)acryloyl-2-hydroxypropyl-3-{3'-(2''-benzotriazole)-4-hydroxy-5-t-butyl} phenylpropionate, Other monomers such as ethylene, propylene, isoprene, butadiene, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl ether, vinyl ketone, and the like, and one or more of these can be used. In the present invention, in particular, by using one or more monomers selected from carboxyl group-containing monomers, alkyl group-containing monomers, cycloalkyl group-containing monomers, aromatic vinyl monomers, and alkoxysilyl group-containing monomers, it is possible to improve stain resistance and crack resistance, which is preferable. In particular, when using one or more selected from cycloalkyl group-containing monomers, aromatic vinyl monomers, and alkoxysilyl group-containing monomers, it is possible to improve stain resistance, which is preferable. In addition, when using a carboxyl group-containing monomer, by further using a crosslinking agent described later, it is possible to improve stain resistance, and further improve weather resistance and water resistance, which is preferable. In addition, by using one or more monomers selected from amide group-containing monomers, it is possible to improve crack resistance, pigment miscibility, storage stability, and glossiness, which is preferable.

[0020] As the emulsifier, there is no particular limitation, and anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, zwitterionic emulsifiers, reactive emulsifiers, etc. can be used. For example, anionic emulsifiers such as alkyl sulfonates such as sodium dodecylbenzenesulfonate and sodium dodecylsulfonate, alkyl sulfates such as sodium dodecylbenzenesulfate and sodium dodecylsulfate, fatty acid salts such as ammonium laurate salt and sodium stearate salt, rosin acid salts, alkyl sulfosuccinates, dialkyl sulfosuccinates, α-olefin sulfonates, alkyl naphthalene sulfonates, polyoxyalkylene alkyl (aryl) sulfate ester salts, polyoxyalkylene alkyl (aryl) sulfonate ester salts, Quaternary ammonium salts such as lauryl trialkylammonium salt, stearyl trialkylammonium salt, and trialkylbenzylammonium salt, primary to tertiary amine salts, cationic surfactants such as lauryl pyridinium salt, benzalkonium salt, benzethonium salt, and laurylamine acetate, Nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyalkylene alkyl phenyl ether, polyalkylene glycol, polyoxyalkylene alkyl ester, polyoxyalkylene sorbitan alkyl ester, and sorbitan alkyl ester, Zwitterionic surfactants such as carboxy betaine type, sulfo betaine type, aminocarboxylic acid type, and imidazoline derivative type, Also, reactive emulsifiers such as polyoxyalkylene alkenyl ether sulfates, polyoxyalkylene alkenyl ethers, polyoxyalkylene allyl alkyl ether sulfate esters, polyoxyalkylene allyl alkyl ethers, polyoxyalkylene alkyl allyl alkyl ether sulfate esters, polyoxyalkylene alkyl allyl alkyl ethers, polyoxyalkylene alkyl allyl phenyl ether sulfate esters, polyoxyalkylene alkyl allyl phenyl ethers, polyoxyalkylene propenyl alkyl ether sulfate esters, polyoxyalkylene propenyl alkyl ethers, polyoxyalkylene alkyl propenyl alkyl ether sulfate esters, polyoxyalkylene alkyl propenyl alkyl ethers, polyoxyalkylene alkyl propenyl phenyl ether sulfate esters, polyoxyalkylene alkyl propenyl phenyl ethers, polyoxyalkylene allyloxyalkyl alkoxyalkyl ether sulfate esters, polyoxyalkylene allyloxyalkyl alkoxyalkyl ethers, polyoxyalkylene allyloxyalkyl ether sulfate esters, polyoxyalkylene allyloxyalkyl ethers, polyoxyalkylene styrenated propenyl phenyl ether sulfate esters, polyoxyalkylene styrenated propenyl phenyl ethers, alkyl allyl sulfosuccinate esters, alkyl propenyl sulfosuccinate esters, (meth)acrylic acid polyoxyalkylene sulfonates, etc. Specifically, Ereminol JS-20 (manufactured by Sanyo Chemical Industries, Ltd.), Ereminol RS-30 (manufactured by Sanyo Chemical Industries, Ltd.), Aqualon KH-05 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon KH-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AR-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AR-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AR-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon BC-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon BC-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon BC-3025 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adeka Resorcinol SR-10 (manufactured by Adeka Corporation), Adeka Resorcinol SR-20 (manufactured by Adeka Corporation), Adeka Resorcinol SR-3025 (manufactured by Adeka Corporation),ADEKA LIA SOAP SE-10N (manufactured by ADEKA CORPORATION), ANTOX MS-60 (manufactured by Nippon Emulsion Co., Ltd.), LATEMUL PD-104 (manufactured by Kao Corporation), LATEMUL PD-105 (manufactured by Kao Corporation), AQUALON KN-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON KN-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON KN-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON KN-5065 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON AN-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON AN-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON AN-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON AN-5065 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON RN-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON RN-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), AQUALON RN-50 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), ADEKA LIA SOAP ER-10 (manufactured by ADEKA CORPORATION), ADEKA LIA SOAP ER-20 (manufactured by ADEKA CORPORATION), ADEKA LIA SOAP ER-30 (manufactured by ADEKA CORPORATION), ADEKA LIA SOAP ER-40 (manufactured by ADEKA CORPORATION), ADEKA LIA SOAP NE-10 (manufactured by ADEKA CORPORATION), ADEKA LIA SOAP NE-20 (manufactured by ADEKA CORPORATION), ADEKA LIA SOAP NE-30 (manufactured by ADEKA CORPORATION), LATEMUL PD-420 (manufactured by Kao Corporation), LATEMUL PD-430 (manufactured by Kao Corporation), LATEMUL PD-450 (manufactured by Kao Corporation) and other reactive emulsifiers etc. are mentioned. In the present invention, the use of a reactive emulsifier is particularly preferable in terms of weather resistance, water resistance, etc.

[0021] As initiators, for example, persulfate initiators such as ammonium persulfate, potassium persulfate, and sodium persulfate; azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4'-dimethylvaleronitrile), 2,2'-azobis(2-amidinopropane) dihydrochloride, and 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride; dialkyl peroxides such as benzoyl peroxide, lauroyl peroxide, and decanoyl peroxide; peroxy esters such as t-butyl peroxybenzoate; hydroperoxides such as cumene hydroperoxide, paramethane hydroperoxide, and t-butyl hydroperoxide; redox initiators, photopolymerization initiators, reactive initiators, etc. can be used.

[0022] The aqueous coating material of the present invention uses the above synthetic resin emulsion as a binder. In addition to the above components, various additives can be blended within a range that does not inhibit the effects of the present invention. Such additives include, for example, dispersion media such as water and solvents, colorants, ultraviolet absorbers, crosslinking agents, aggregates, dispersants, gelling agents, film-forming aids, plasticizers, antifreeze agents, preservatives, fungicides, algicides, antibacterial agents, defoaming agents, leveling agents, coupling agents, low-pollution agents, hydrophilizing agents, water-repellent agents, thickeners, pigment dispersants, anti-settling agents, anti-dripping agents, surface modifiers, wetting agents, pH adjusters, fibers, antioxidants, curing catalysts, matting agents, fragrances, light stabilizers, photocatalysts, flame retardants, etc.

[0023] Examples of colorants include colored pigments, colored aggregates, colored resin particles, etc.

[0024] Examples of coloring pigments include inorganic coloring pigments such as titanium oxide, zinc oxide, carbon black, lamp black, bone black, graphite, black iron oxide, cobalt black, copper manganese iron black, ferric oxide (red iron oxide), molybdate orange, yellow iron oxide, titanium yellow, ultramarine blue, dark blue, cobalt blue, cobalt green, iron chromium composite oxide, manganese bismuth composite oxide, manganese yttrium composite oxide, manganese iron cobalt composite oxide, etc.; organic coloring 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.; functional pigments such as pearl pigments, fluorescent pigments, phosphorescent pigments, metallic pigments, etc.; extender pigments such as heavy calcium carbonate, precipitated calcium carbonate, kaolin, talc, clay, pottery clay, china clay, barium sulfate, barium carbonate, silica powder, diatomaceous earth, etc. Also, pearl pigments, aluminum pigments, metallic pigments, phosphorescent pigments, fluorescent pigments, etc. may be mentioned. These can be used alone or in combination of two or more kinds.

[0025] Examples of colored aggregates include crushed materials such as marble, gneiss, serpentine, granite, fluorite, gypsum, feldspar, silica, silica sand, etc.; crushed ceramic materials; crushed ceramic products; crushed glass materials; glass beads; crushed resin materials; resin beads; metal grains; mica, talc, clay, diatomaceous earth, shell pieces, coral pieces, plant pieces, wood pieces, and other various aggregates. Also, those obtained by color-coating the surfaces of such various aggregates with, for example, pigments, dyes, glazes, etc. may be mentioned.

[0026] Colored resin particles are, for example, gel-like or solid particles containing the above-mentioned coloring pigments, colored aggregates, and synthetic resins. Examples of synthetic resins include those formed from acrylic resins, urethane resins, epoxy resins, vinyl acetate resins, polyester resins, alkyd resins, vinyl chloride resins, acrylic silicone resins, and fluororesins.

[0027] The blending amount of such a colorant is preferably 1 part by mass or more and 2,000 parts by mass or less, more preferably 5 parts by mass or more and 1,500 parts by mass or less, based on 100 parts by mass of the solid content of the synthetic resin emulsion. One kind or two or more kinds of colorants can be used, and one color or a combination of two or more colors can be used.

[0028] As the ultraviolet absorber, it is particularly preferable to blend an oxalic acid anilide or its derivative, and the weather resistance and stain resistance can be improved. In particular, when a cycloalkyl group-containing monomer and / or an aromatic vinyl-based monomer is included as the monomer constituting the synthetic resin emulsion, excellent weather resistance and stain resistance can be exhibited by combining an oxalic acid anilide or its derivative. Such an ultraviolet absorber can also be mixed with the above monomers during the production of the synthetic resin emulsion. By mixing the ultraviolet absorber during the production of the synthetic resin emulsion, more excellent weather resistance and stain resistance can be exhibited.

[0029] The blending amount of such an ultraviolet absorber is preferably 0.1 part by mass or more and 10 parts by mass or less, more preferably 0.3 part by mass or more and 5 parts by mass or less, based on 100 parts by mass of the solid content of the synthetic resin emulsion.

[0030] Examples of the crosslinking agent include a hydrazino group-containing compound, an isocyanate group-containing compound, an amino group-containing compound, an epoxy group-containing compound, an oxazoline group-containing compound, a silanol group-containing compound, a metal complex, etc. In the present invention, it is particularly preferable to include a carbodiimide group-containing compound. When a monomer having a carboxyl group is included as the monomer constituting the synthetic resin emulsion, the carbodiimide group-containing compound can form a strong coating film by crosslinking the carbodiimide group and the carboxyl group, and exhibit excellent stain resistance and crack resistance. Such a crosslinking agent can also be mixed with the above monomers during the production of the synthetic resin emulsion. In the present invention, by incorporating the above ultraviolet absorber into such a crosslinked structure, a coating film excellent in stain resistance, and further in weather resistance and water resistance can be formed.

[0031] Examples of the carbodiimide group-containing compound include compounds containing a carbodiimide group (-N=C=N-) or its tautomer, a cyanamide group (NC-NH-), and can be obtained using a diisocyanate compound as a raw material. Examples of the diisocyanate compound include aliphatic isocyanates such as hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, and lysine diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylene diisocyanate; aromatic diisocyanates such as 2,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, o-tolidine diisocyanate, naphthylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, and 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate. One or more of these can be used. Further, the carbodiimide group-containing compound may be one in which some or all of the isocyanate groups are modified with a compound having a functional group capable of reacting with the isocyanate group. Examples of the functional group capable of reacting with the isocyanate group include a hydroxyl group, an amine group, a carboxyl group, and an epoxy group, and one or more of these can be appropriately selected and used. In the present invention, it is particularly preferable to use glycols such as alkylene glycol and alkylene glycol alkyl ether.

[0032] The blending amount of such a crosslinking agent is preferably 0.1 part by mass or more and 10 parts by mass or less, more preferably 0.3 part by mass or more and 5 parts by mass or less, based on 100 parts by mass of the solid content of the synthetic resin emulsion.

[0033] The aqueous coating material in the present invention can be preferably used mainly as a topcoat material, a finishing material, a protective material, etc., and can be finished by applying one or more coats. For example, it can be applied to various base materials such as concrete, mortar, siding board, extruded board, ALC, gypsum board, perlite board, tile, glass board, wooden board, plastic board, metal board. In addition, as these base materials, it can also be applied to those subjected to some surface treatment (filler treatment, putty treatment, surfacer treatment, sealer treatment, etc.), or those with an undercoat material or an intermediate coat material applied, or an existing coating film that already has a coating film formed.

[0034] As the coating method, for example, various methods such as brush coating, trowel coating, roller coating, spray coating, gun coating can be adopted. The coating amount during coating is preferably 0.03 to 8.0 kg / m 2 、more preferably 0.05 to 6.0 kg / m 2 per application. Also, once the coating is applied and the coating film has dried, the next coating (overcoating) can be carried out. The drying temperature is preferably -10 to 50°C, more preferably -5 to 40°C.

Examples

[0035] Examples are shown below to make the features of the present invention clearer. Note that the present invention is not limited to the examples here.

[0036] (Examples 1 to 9, Comparative Examples 1 to 8) Using the monomer components shown below, three-layer structural synthetic resin emulsions 1 to 17 (solid content: 50% by mass) having an inner layer, an intermediate layer, and an outer layer were obtained by a conventional three-stage polymerization method. The monomers used in the inner layer were methyl methacrylate (glass transition temperature: 105 °C), styrene (glass transition temperature: 100 °C), 2-ethylhexyl acrylate (glass transition temperature: -70 °C), cyclohexyl methacrylate (glass transition temperature: 83 °C). The monomers used in the intermediate layer were methyl methacrylate, 2-ethylhexyl acrylate, cyclohexyl methacrylate. The monomers used in the outer layer were methyl methacrylate, 2-ethylhexyl acrylate, butyl acrylate (glass transition temperature: -56 °C), cyclohexyl methacrylate, acrylic acid (glass transition temperature: 95 °C). Also, an ammonium polyoxyethylene alkyl sulfate ester salt was used as the emulsifier, and ammonium persulfate was used as the initiator. The mixing ratios of the above monomers were adjusted to design the glass transition temperatures of each inner layer, intermediate layer, and outer layer. The glass transition temperatures are shown in Table 1. Furthermore, 100 parts by mass of each three-layer structural synthetic resin emulsion (solid content: 50% by mass), 60 parts by mass of titanium oxide, 60 parts by mass of heavy calcium carbonate, 100 parts by mass of water, and 10 parts by mass of additives (thickener, film-forming aid, defoamer, dispersant) were mixed by a conventional method to obtain each aqueous coating material.

[0037] (Example 10) A three-layer structural synthetic resin emulsion 18 was produced in the same manner as in Example 3, except that an ammonium polyoxyethylene alkyl sulfate ester salt and an ammonium polyoxyethylene allyloxyalkyl alkoxyalkyl ether sulfate ester salt were mixed at a mass ratio of 1:1 and used as the emulsifier, and an aqueous coating material was obtained in the same manner.

[0038] (Example 11) 100 parts by mass of a three-layer structured synthetic resin emulsion 3 (solid content: 50% by mass), 60 parts by mass of titanium oxide, 60 parts by mass of heavy calcium carbonate, 100 parts by mass of water, 10 parts by mass of additives (thickener, film-forming aid, defoaming agent, dispersant), and 1 part by mass of 2-ethyl-2'-ethoxyoxalanilide as an ultraviolet absorber were mixed by a conventional method to obtain an aqueous coating material.

[0039] (Example 12) 100 parts by mass of a three-layer structured synthetic resin emulsion 3 (solid content: 50% by mass), 60 parts by mass of titanium oxide, 60 parts by mass of heavy calcium carbonate, 100 parts by mass of water, 10 parts by mass of additives (thickener, film-forming aid, defoaming agent, dispersant), and 1 part by mass of a glycol-modified product of polycarbodiimide obtained from 4,4'-dicyclohexylmethane diisocyanate as a cross-linking agent were mixed by a conventional method to obtain an aqueous coating material.

[0040] (Example 13) A three-layer structured synthetic resin emulsion 19 was produced in the same manner as in Example 3 except that cyclohexyl methacrylate was not used and methyl methacrylate and 2-ethylhexyl acrylate were used instead of cyclohexyl methacrylate. An aqueous coating material was obtained in the same manner. The glass transition temperatures of methyl methacrylate and 2-ethylhexyl acrylate were adjusted so that the glass transition temperatures of the inner layer, intermediate layer, and outer layer were the same as those in Example 3.

[0041] (Example 14) An aqueous coating material was obtained in the same manner as in Example 3 except that 2-ethyl-2'-ethoxyoxalanilide (ultraviolet absorber) was contained in the monomer to produce a three-layer structured synthetic resin emulsion 19. The content of the ultraviolet absorber was 1 part by mass per 100 parts by mass of the total monomers.

[0042] (Example 15) An aqueous coating material was obtained in the same manner as in Example 3, except that a three-layer structured synthetic resin emulsion 20 was produced by containing 2-ethyl-2'-ethoxyoxalanilide (ultraviolet absorber) and a glycol-modified product of polycarbodiimide obtained from 4,4'-dicyclohexylmethane diisocyanate (crosslinking agent) in the monomer. The content of the ultraviolet absorber is 1 part by mass with respect to 100 parts by mass of the total monomers, and the content of the crosslinking agent is 2 parts by mass with respect to 100 parts by mass of the total monomers.

[0043] (Example 16) A three-layer structured synthetic resin emulsion 21 was produced in the same manner as in Example 3, except that acrylamide (glass transition temperature: 153 °C) was further added as the monomer used for the outer layer, and an aqueous coating material was obtained in the same manner. Among the total amount of monomers used for the outer layer, the content of acrylamide is 1.3% by mass, and the glass transition temperature was adjusted with methyl methacrylate and 2-ethylhexyl acrylate. The glass transition temperatures of the inner layer, intermediate layer, and outer layer are the same as those in Example 3.

[0044] (Example 17) A three-layer structured synthetic resin emulsion 22 was produced in the same manner as in Example 3, except that acrylamide was further added as the monomer used for the inner layer and the monomer used for the outer layer, and an aqueous coating material was obtained. Among the total amount of monomers used for the inner layer, the content of acrylamide is 0.6% by mass, and among the total amount of monomers used for the outer layer, the content of acrylamide is 0.5% by mass, and the glass transition temperature was adjusted with methyl methacrylate and 2-ethylhexyl acrylate. The glass transition temperatures of the inner layer, intermediate layer, and outer layer are the same as those in Example 3.

[0045] (Example 18) A three-layer structured synthetic resin emulsion 23 was produced and an aqueous coating material was obtained in the same manner as in Example 1, except that acrylamide was further added as the monomer used for the inner layer and the monomer used for the outer layer. Among the total amount of the monomers used for the inner layer, the content of acrylamide was 0.6% by mass, and among the total amount of the monomers used for the outer layer, the content of acrylamide was 0.5% by mass. The glass transition temperature was adjusted with methyl methacrylate and 2-ethylhexyl acrylate. The glass transition temperatures of the inner layer, the intermediate layer, and the outer layer were the same as those in Example 1.

[0046] The following crack resistance test, stain resistance test, and storage stability test were conducted on the obtained aqueous coating material. The evaluation results are shown in Table 1.

[0047] (Crack resistance test) A slate board (150 mm in length × 70 mm in width × 6 mm in thickness) with a cut in the horizontal center part that had been subjected to a sealer treatment was used as a test substrate. Each aqueous coating material was applied to this test substrate with a coating roller so that the dry film thickness was 0.15 mm, and it was cured for 14 days. In addition, all the production and curing of the test plates were carried out under standard conditions (temperature 23°C, relative humidity 50%). Also, the upper and lower ends of 20 mm each were left uncoated. Regarding the obtained test plates, the crack resistance was evaluated using a tensile testing machine. The evaluation was carried out as follows: those with no abnormality observed when the test substrate was stretched by 1.5 mm were rated as "◎", those with no abnormality observed when the test substrate was stretched by 1.0 mm were rated as "○", those with no abnormality observed when the test substrate was stretched by 0.5 mm were rated as "△", and those with cracks observed when the test substrate was stretched by 0.5 mm were rated as "×".

[0048] (Stain resistance test) For a slate board (300 mm in length × 150 mm in width × 6 mm in thickness) that had been previously coated with an acrylic resin-based paint (white), each aqueous coating material was applied with a coating roller so that the dry film thickness was 0.15 mm, and it was dried for 24 hours to obtain a test piece. In addition, all the production and curing of the test plates were carried out under standard conditions (temperature 23°C, relative humidity 50%). Regarding the obtained specimens, they were vertically placed facing south in Ibaraki City, Osaka Prefecture and left standing outdoors for 6 months. After 6 months, the contamination state of the specimen surface was visually evaluated. The evaluation was carried out in four grades (excellent: ◎ > ○ > △ > ×: poor), where those with no contamination were rated as "◎" and those with significant contamination were rated as "×".

[0049] (Storage Stability Test) Each aqueous coating material was put into a 1000 ml container, sealed, and stored in a thermostat at 50 °C for 30 days. Then, the viscosities before and after storage were measured, and the viscosity change before and after storage was evaluated. For the measurement of viscosity, a BH-type viscometer was used and carried out under standard conditions (temperature 23 °C, relative humidity 50%). The evaluation criteria are as follows. ◎: Viscosity change less than 10% 〇: Viscosity change of 10% or more and less than 20% △: Viscosity change of 20% or more and less than 30% ×: Viscosity change of 30% or more

[0050] As a result, Examples 1 to 18 within the specified range of the present invention obtained good results in the crack resistance test, stain resistance test, and storage stability test. In particular, Examples 1, 2, and 18 obtained excellent results in both the stain resistance test and the crack resistance test. On the other hand, Comparative Examples 1 to 8 outside the specified range of the present invention showed inferior results compared to Examples 1 to 18.

[0051]

Table 1

Claims

[Claim 1] An aqueous coating material using a synthetic resin emulsion as a binder, The synthetic resin emulsion comprises: The glass transition temperature of the inner layer is higher than 35°C and not higher than 120°C; The glass transition temperature of the intermediate layer is higher than -10°C and not higher than 45°C; The glass transition temperature of the outer layer is −60° C. or higher and 10° C. or lower, the difference between the glass transition temperature of the inner layer and the glass transition temperature of the intermediate layer (inner layer Tg - intermediate layer Tg) is 35°C or more; the difference between the glass transition temperature of the intermediate layer and the glass transition temperature of the outer layer (intermediate layer Tg - outer layer Tg) is more than -10°C and less than 35°C; An aqueous coating material characterized in that it is a multi-layered synthetic resin emulsion having an average particle size of 50 nm or more and 300 nm or less.

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