JP5085951B2 - Water-based paint composition and coating method - Google Patents

Description

  The present invention relates to a water-based coating composition and a coating method using the same.

  In general, as a coating method for building walls, etc., a primer is applied to form a paint film with elasticity to follow small cracks that occur on the surface of the wall and to suppress the ingress of water from the outside. A coating method for applying a top coating that forms a coating film excellent in weather resistance, finish, and the like is well known. For example, Patent Document 1 includes an aqueous dispersion of a carbonyl group-containing copolymer, a hydrazide compound, and a pigment, on an elastic base coating film formed by an elastic base coating material in which the elongation rate of the formed coating film and the pigment volume concentration are within a specific range. A coating method for applying a top coat having a specific elongation is disclosed. According to the multilayer coating film formed by this coating method, it has a good finished appearance and high durability, and can maintain the aesthetics of the building over a long period of time. Depending on the combination, the intended purpose may not be achieved.

  For such a problem, Patent Document 2 describes an aqueous coating composition containing a core-shell type carbonyl group-containing copolymer emulsion in which carbonyl groups are unevenly distributed in the shell portion and a specific amount of pigment. When such a water-based coating composition is applied to a base coating composition, a multi-layer coating finish having a good finished appearance and high durability is possible regardless of the combination of the base material and the top coating material. In some cases, the adhesion is not sufficient.

  As a technique for improving adhesion to a substrate, Patent Document 3 discloses an emulsion resin having a glass transition temperature in a specific range obtained by emulsion polymerization of a monomer mixture containing an acetoacetoxy group-containing unsaturated monomer, and an aliphatic group. An aqueous primer composition comprising a dihydrazide compound is described. According to such an undercoating material composition, one carbonyl moiety of the acetoacetoxy group is crosslinked, and the other carbonyl moiety forms a strong hydrogen bond with the base material and the old coating film, and so on. Although it is possible to form an undercoat film excellent in initial water resistance, etc., the paint film may not follow the fine cracks that occur on the wall surface due to insufficient elongation of the film in a low temperature environment. is there.

  Patent Document 4 discloses a copolymer obtained by emulsion polymerization of a carbonyl group-containing unsaturated monomer, a carboxyl group-containing unsaturated monomer, and other radical polymerizable unsaturated monomers at a specific ratio. And a water-based coating composition containing a specific amount of polyvalent metal.

  According to the composition, it has a quick drying property, can form a coating film excellent in alkali resistance, substrate adhesion, stain resistance, film-forming property, etc., and is very useful as a coating for exterior building walls. The physical properties of the coating film in a low temperature environment may be insufficient.

  In general, the physical properties of the coating film are significantly reduced under a low temperature environment. A technique for lowering the glass transition temperature of the resin that is a film forming component is known to ensure the physical properties of the coating film at low temperatures, but simply by adjusting the glass transition temperature of the resin, the elongation rate of the coating film at low temperatures is Although improved, the toughness of the coating film at room temperature becomes insufficient, and it is very difficult to achieve both.

JP-A-6-190332 JP 2002-309160 A JP 2003-201440 A Japanese Patent Laid-Open No. 11-256073

  The object of the present invention is to have flexibility capable of following changes over time of the coated surface even in a low temperature environment, and toughness in a room temperature environment, such as water resistance, adhesion, etc. An object of the present invention is to provide an aqueous coating composition suitable for forming a coating film excellent in coating film properties and a coating method using the same.

As a result of intensive studies on the problems described above, the present inventors have found that an aqueous coating composition containing an aqueous copolymer dispersion and a pigment has a linear or branched carbon number of 6 or more in the aqueous copolymer dispersion. By adjusting the copolymerization amount of the acrylate containing alkyl group, the pigment concentration in the composition, and the blending amount of adipic acid dihydrazide to a specific range, the physical properties of the coating film at low and normal temperatures and adhesion to the coated surface The present inventors have found that an excellent coating film can be formed, and have reached the present invention. That is, the present invention
1. An aqueous coating composition containing an aqueous copolymer dispersion (A), a pigment (B) and an adipic acid dihydrazide (C) , wherein the aqueous copolymer dispersion (A) is linear or branched carbon An acrylate (a) containing an alkyl group having 6 or more alkyl groups, a carbonyl group-containing polymerizable unsaturated monomer (b) as a copolymerization component, and a linear or branched alkyl group having 6 or more carbon atoms The copolymerization ratio of the acrylate (a) contained is 65 to 85% by mass , the pigment volume concentration in the composition is in the range of 15 to 60%, and the amount of adipic acid dihydrazide (C) used is An aqueous coating composition characterized by being in the range of 0.01 to 0.3 mol with respect to 1 mol of carbonyl groups contained in the combined aqueous dispersion (A) ;
2.
2. The aqueous solution according to item 1, wherein the polymerizable unsaturated monomer used in the production of the aqueous copolymer dispersion (A) is selected such that the glass transition temperature of the copolymer is −20 ° C. or lower. Paint composition,
3. The copolymer aqueous dispersion (A) is a linear or branched acrylate (a) containing an alkyl group having 6 or more carbon atoms, 65 to 85 % by mass, a carbonyl group-containing polymerizable unsaturated monomer (b). 0.05 to 8 % by mass, linear or branched methacrylate containing 6 or less carbon atoms and / or vinyl aromatic compound (c1) 5 to 20 % by mass, carboxyl group-containing polymerizable unsaturated By copolymerizing the monomer (c2) 1 to 3 % by mass and other polymerizable unsaturated monomers 0 to 28.95 % by mass other than the above monomers (a), (b), (c1) and (c2) 3. The aqueous coating composition according to item 1 or 2, which is obtained.
4). 4. The aqueous coating composition according to any one of items 1 to 3, wherein the pigment (B) is a combination of an extender pigment and a color pigment.
5. 5. The aqueous coating composition according to any one of items 1 to 4 , further comprising a metal compound (D),
6). 6. The aqueous coating composition according to any one of 1 to 5 , further comprising a compound (E) having two or more functional groups capable of reacting with a carboxyl group in one molecule;
7). The aqueous coating composition according to any one of 1 to 6, further comprising a thickener, wherein the thickener is a combination of a fiber derivative compound and a polyether compound,
8). 8. A coating method comprising applying the aqueous coating composition according to any one of items 1 to 7 to a surface to be coated;
9. A coating method comprising: coating the surface to be coated with the aqueous coating composition according to any one of items 1 to 7 as an undercoat;
A multilayer coating film formed by the coating method described in 10.9,
About.

  According to the water-based coating composition of the present invention, it is possible to form a flexible and tough coating film, and to follow changes in the coated surface over time even in a low-temperature environment. It is possible to form a coating film that can suppress the intrusion.

Copolymer aqueous dispersion (A)
The copolymer aqueous dispersion (A) applied to the aqueous coating composition of the present invention is a linear or branched acrylate (a) containing an alkyl group having 6 or more carbon atoms and a carbonyl group-containing polymerizability. An unsaturated monomer (b) is used as a copolymerization component, and the copolymerization ratio of the acrylate (a) containing a linear or branched alkyl group having 6 or more carbon atoms in the copolymer is 50 masses. % Or more.

  Specific examples of the acrylate (a) containing a linear or branched alkyl group having 6 or more carbon atoms in the aqueous copolymer dispersion (A) include n-hexyl acrylate, heptyl acrylate, and octyl. Acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecyl acrylate, octadecyl acrylate, nonadecyl acrylate, icosyl acrylate , Heicosyl acrylate, docosyl acrylate and the like can be mentioned, and these can be used alone or in combination of two or more. The acrylate (a) particularly preferably contains a linear or branched alkyl group having 7 or more, more preferably 8 or more carbon atoms.

  In the present invention, the copolymerization ratio of the acrylate (a) containing a linear or branched alkyl group having 6 or more carbon atoms in the copolymer aqueous dispersion (A) is required to be 50% by mass or more. It is. When the copolymerization ratio of the acrylate (a) is less than 50% by mass, the low-temperature flexibility of the coating film formed from the aqueous coating composition of the present invention, the toughness of the coating film at room temperature, and the water resistance of the coating film are poor. It is not preferable because it is sufficient.

  In the present invention, specific examples of the carbonyl group-containing polymerizable unsaturated monomer (b) include (meth) acrolein, formylstyrene, a vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, Vinyl butyl ketone, etc.), acetoacetoxyethyl (meth) acrylate, acetoacetoxyallyl ester, diacetone (meth) acrylamide and the like can be mentioned, and these can be used alone or in combination of two or more.

  In the present invention, the copolymer aqueous dispersion (A) is used in addition to the linear or branched acrylate (a) having an alkyl group having 6 or more carbon atoms and the carbonyl group-containing polymerizable unsaturated monomer (b). Other polymerizable unsaturated monomers (c) other than these can be copolymerized as necessary. Specific examples of the other polymerizable unsaturated monomer (c) include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, and n-hexyl methacrylate. Methacrylates containing a linear or branched alkyl group having 6 or less carbon atoms such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-pentyl acrylate Acrylates containing a linear or branched alkyl group having 5 or less carbon atoms, such as: vinyl aromatic compounds such as styrene and α-methylstyrene; heptyl methacrylate, octyl methacrylate, 2-ethyl Hexyl methacrylate, nonyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecyl methacrylate, octadecyl methacrylate, nonadecyl methacrylate, icosyl methacrylate, heicosyl Methacrylates containing linear or branched alkyl groups having 7 or more carbon atoms such as methacrylate and docosyl methacrylate; having cyclic hydrocarbon groups such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate (meth) Acrylate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3- Hydroxypropyl (meth) acrylate, hydroxyalkyl (meth) acrylate such as hydroxybutyl (meth) acrylate, allyl alcohol, ε-caprolactone modified form of the above hydroxyalkyl (meth) acrylate, containing polyoxyethylene chain whose molecular terminal is a hydroxyl group Hydroxyl group-containing polymerizable unsaturated monomers such as (meth) acrylate; Carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, maleic acid, crotonic acid and β-carboxyethyl acrylate; Aralkyl such as benzyl (meth) acrylate (Meth) acrylates; alkoxyalkyl (meth) acrylates such as 2-methoxyethyl (meth) acrylate and 2-ethoxyethyl (meth) acrylate; perfluoroalkyl (meth) acrylates, N, N- Diethylaminoethyl (meth) acrylate; (meth) acrylamide, (meth) acrylonitrile; vinyl ester compounds such as vinyl acetate and vinyl propionate; allyl (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) Acrylate, tetraethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate Lilate, 1,1,1-trishydroxymethylethane di (meth) acrylate, 1,1,1-trishydroxymethylethane tri (meth) acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, Polyvinyl compounds having at least two polymerizable unsaturated groups in one molecule such as triallyl isocyanurate, diallyl terephthalate, divinylbenzene, etc .; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3, 4 -Epoxy group-containing polymerizable unsaturated monomers such as epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and allyl glycidyl ether; Isocyanate group-containing polymerizable unsaturated monomers such as anatoethyl (meth) acrylate and m-isopropenyl-α, α-dimethylbenzyl isocyanate; vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ An alkoxysilyl group-containing polymerizable unsaturated monomer such as methacryloyloxypropyltriethoxysilane; an epoxy group-containing polymerizable unsaturated monomer or a reaction product of a hydroxyl group-containing polymerizable unsaturated monomer and an unsaturated fatty acid, dicyclopentenyloxyethyl Examples include (meth) acrylate, dicyclopentenyloxypropyl (meth) acrylate, and oxidatively curable group-containing polymerizable unsaturated monomers such as dicyclopentenyl (meth) acrylate. These may be used alone or in combination of two or more. It can be used in conjunction look.

  In the present invention, the polymerizable unsaturated monomer used for the production of the copolymer aqueous dispersion (A) has a glass transition temperature of -20 ° C or lower, preferably in the range of -30 to -60 ° C. It is desirable from the point of followability with respect to the coated surface of the coating film formed by the aqueous coating composition of the present invention.

  In the present invention, the glass transition temperature (absolute temperature) is a value calculated by the following formula.

1 / Tg = W ₁ / T ₁ + W ₂ / T ₂ +... W _n / T _{n
Wherein, W 1, W 2 ··· W} n is the weight percent of each monomer [= (amount / monomer total weight of each monomer) × _{100], T 1, T 2 ··· T} n each It is the glass transition temperature (absolute temperature) of the homopolymer of the monomer. The glass transition temperature of the homopolymer of each monomer is a value according to Polymer Hand Book (4th edition, edited by J. Brandrup / EHImmergut), and the glass transition temperature of a monomer not described in the literature is the homopolymeric homopolymer of the monomer. The polymer is synthesized so that the weight average molecular weight is about 50,000, and the value when the glass transition temperature is measured by differential scanning thermal analysis is used.

  In the present invention, the other polymerizable unsaturated monomer (c) has a linear or branched carbon number of 6 or less from the viewpoint of the water resistance of the coating film formed from the aqueous coating composition of the present invention. From the viewpoint of pigment dispersibility, it is desirable to use the carboxyl group-containing polymerizable unsaturated monomer (c2) as the methacrylate and / or vinyl aromatic compound (c1) containing the above alkyl group.

In the present invention, as an example of the composition of the monomer component forming the copolymer in the copolymer aqueous dispersion (A) as described above,
The acrylate (a) having a linear or branched alkyl group having 6 or more carbon atoms,
50 to 85% by mass, preferably 65 to 85% by mass,
A carbonyl group-containing polymerizable unsaturated monomer (b),
0.01 to 10% by mass, preferably 0.05 to 8% by mass,
A methacrylate and / or vinyl aromatic compound (c1) containing a linear or branched alkyl group having 6 or less carbon atoms,
5 to 25% by mass, preferably 5 to 20% by mass,
The carboxyl group-containing polymerizable unsaturated monomer (c2) is
0.05-5% by mass, preferably 1.0-3.0% by mass,
Other polymerizable unsaturated monomers other than (a), (b), (c1) and (c2)
0 to 44.94% by mass, preferably 0 to 28.95% by mass,
Can be mentioned.

  The method for polymerizing the monomer is not particularly limited. For example, by copolymerizing the polymerizable unsaturated monomer in the presence of a surfactant as an emulsifier according to a general emulsion polymerization method. It can be manufactured easily.

  In addition, the use of an emulsion polymer obtained by an emulsion polymerization method is preferable because it can reduce the amount of the organic solvent in the finally obtained aqueous coating composition and can set the molecular weight of the copolymer high. .

  As the emulsifier used in the production of the copolymer aqueous dispersion (A), conventionally known emulsifiers can be used. Examples of applicable emulsifiers include anionic emulsifiers, nonionic emulsifiers, both Examples include ionic emulsifiers.

  Examples of the anionic emulsifier include diammonium dodecyl diphenyl ether disulfonate, sodium dodecyl diphenyl ether disulfonate, calcium dodecyl diphenyl ether disulfonate, alkyl diphenyl ether disulfonate such as sodium alkyl diphenyl ether disulfonate; sodium dodecyl benzene sulfonate, ammonium dodecyl benzene sulfonate, etc. Alkyl benzene sulfonates; alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate; aliphatic carboxylates such as fatty acid sodiums and potassium oleate; sulfate salts containing polyoxyalkylene units (for example, polyoxyethylene alkyl ethers) Sodium sulfate, polyoxyethylene alkyl ether sulfate Polyoxyethylene alkyl ether sulfate salts such as nium; polyoxyethylene alkyl phenyl ether sulfate salts such as sodium polyoxyethylene alkyl phenyl ether sulfate and polyoxyethylene alkyl phenyl ether ammonium sulfate; polyoxyethylene polycyclic sodium phenyl ether sulfate; Polyoxyethylene polycyclic phenyl ether sulfate salts such as ammonium polyoxyethylene phenyl ether sulfate; etc.); naphthalene sulfonic acid formalin condensate sodium naphthalene sulfonic acid formalin condensate salt, etc .; sodium dialkylsulfosuccinate, monoalkyl succinate And alkyl succinate sulfonates such as disodium sulfonate and the like. These may be used alone or in combination of two or more. It is possible to use Te Align.

  Examples of nonionic emulsifiers include polyoxyalkylene unit-containing ether compounds (for example, polyoxyalkylene alkyl ether compounds such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene tridecyl ether, polyoxyethylene oleyl ether). Polyoxyalkylene alkyl phenyl ether compounds such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether; polyoxyalkylene polycyclic phenyl ether compounds such as polyoxyethylene polycyclic phenyl ether; etc.); polyoxyethylene monolaur Polyoxyalkylene alkyl ester compounds such as rate, polyoxyethylene monostearate, polyoxyethylene monooleate; Polyoxyalkylene alkylamine compounds such as reoxyethylene alkylamine; sorbitan compounds such as sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate; Can be used alone or in combination of two or more.

  Examples of amphoteric surfactants include dimethylalkylbedines, dimethylalkyllaurylbedines, and alkylglycines.

  As the emulsifier, a reactive emulsifier containing a polymerizable unsaturated group and an anionic group or a nonionic group in the molecule can also be used.

  As the usage-amount of the said emulsifier, it is 0.5-6 mass% with respect to all the polymerizable unsaturated monomers used for manufacture of a copolymer aqueous dispersion (A), Preferably it exists in the range of 1-4 mass%. It can be.

  The polymerization initiator used for the polymerization includes tert-butylperoxy 2-ethylhexanoate, benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert-butyl hydro gen. Organic peroxides such as peroxide, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, diisopropylbenzene hydroperoxide; azobisisobutyronitrile, azobis (2,4 -Dimethylvaleronitrile), azobis (2-methylpropiononitrile), azobis (2-methylbutyronitrile), 4,4'-azobis (4-cyanobutanoic acid), dimethylazobis (2-methyl) Azo compounds such as lupropionate), azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], azobis {2-methyl-N- [2- (1-hydroxybutyl)]-propionamide}; Examples thereof include persulfates such as potassium sulfate, ammonium persulfate, and sodium persulfate.

  As a suitable usage-amount of the said polymerization initiator, 0.001-15 mass% with respect to all the polymerizable unsaturated monomers used for manufacture of a copolymer aqueous dispersion (A), especially 0.01-0. .50% by weight, more particularly in the range of 0.10 to 0.40% by weight.

  The weight average molecular weight of the copolymer aqueous dispersion (A) obtained as described above is from the viewpoint of flexibility at low temperature and toughness at normal temperature of the coating film formed from the aqueous coating composition of the present invention. It is desirable to be in the range of 50,000 to 1,000,000, particularly 150,000 to 500,000.

  In this specification, the weight average molecular weight is a value obtained by converting the weight average molecular weight measured by gel permeation chromatograph (“HLC8120GPC” manufactured by Tosoh Corporation) based on the weight average molecular weight of polystyrene. Columns are “TSKgel G-4000H × L”, “TSKgel G-3000H × L”, “TSKgel G-2500H × L”, “TSKgel G-2000H × L” (both manufactured by Tosoh Corporation, trade names) ), Mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 cc / min, detector: RI.

Pigment (B)
Examples of the pigment (B) used in the aqueous coating composition of the present invention include coloring pigments such as titanium oxide, carbon black, and bengara; barita powder, precipitated barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, silica And extender pigments such as white carbon, diatomaceous earth, talc, magnesium carbonate, alumina white, and gloss white. These can be used alone or in combination of two or more.

  In the present invention, the amount of the pigment (B) used is desirably adjusted so that the pigment volume concentration is in the range of 15 to 60%, preferably 15 to 45%, more preferably 25 to 42%. .

  When the pigment volume concentration is less than 15%, a tough coating film cannot be obtained. On the other hand, when the pigment volume concentration exceeds 60%, crack followability of the coating film is lowered, which is not preferable.

  In the present specification, the pigment volume concentration is a volume ratio of the pigment content in the total solid content of the total resin content and the total pigment content in the paint. In this specification, the specific gravity of the pigment which is the basis for calculating the volume of the pigment is according to “Paint Raw Material Handbook 6th Edition” (Japan Paint Manufacturers Association), and the specific gravity of the resin solids is Approximate to 1.

  In the present invention, the pigment (B) is preferably a combination of extender pigments and colored pigments. The combined use ratio is 99/1 to 60/40, preferably 95/5 to 70/30, in terms of extender pigment / colored pigment mass ratio. To preferred.

Hydrazine derivative (C)
The water-based coating composition of the present invention can be blended with a hydrazine derivative (C) as necessary for the purpose of improving the water resistance, adhesion, and toughness of the coating film at room temperature. The hydrazine derivative (C) has a functional group that undergoes a crosslinking reaction with the carbonyl group of the copolymer aqueous dispersion (A). Specific examples thereof include hydrazine, hydrazine hydrate, oxalic acid dihydrazide, and malonic acid dihydrazide. Dihydrazides of saturated aliphatic carboxylic acids having 2 to 18 carbon atoms such as succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide; monoolefinic unsaturated compounds such as maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide Dicarboxylic acid dihydrazide; phthalic acid, terephthalic acid or isophthalic acid dihydrazide; pyromellitic acid dihydrazide, trihydrazide or tetrahydrazide; nitrilotriacetic acid trihydrazide, citric acid trihydrazide, 1,2,4-benzenetrihydra Ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphthoic acid tetrahydrazide; polyhydrazide obtained by reacting a low polymer having a carboxylic acid lower alkyl ester group with hydrazine or hydrazine hydrate (hydrazine hydride) Etc .; Carbonic dihydrazide, bissemicarbazide; Diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate and polyisocyanate compounds derived therefrom are reacted with N, N-substituted hydrazines such as N, N-dimethylhydrazine and the hydrazides exemplified above in excess. A polyfunctional semicarbazide obtained by the above process; isoforms in a reaction product of the polyisocyanate compound and an active hydrogen compound containing a hydrophilic group such as polyether polyols and polyethylene glycol monoalkyl ethers; Aqueous polyfunctional semicarbazide obtained by overreact the above-exemplified dihydrazide in Aneto group; a mixture of polyfunctional semicarbazide and aqueous polyfunctional semicarbazide; bis-acetyl-di hydrazone, or the like may be suitably used. The compounds described above can be used alone or in combination of two or more.

  The amount of the hydrazine derivative (C) used is 0.01 to 1.0 mol, preferably 0.01 to 0.7 mol, relative to 1 mol of the carbonyl group contained in the aqueous copolymer dispersion (A). More preferably, it is in the range of 0.01 to 0.3 mol.

Metal compound (D)
The water-based coating composition of the present invention is used for the purpose of improving the water resistance, adhesion, and toughness of the coating film at room temperature, particularly when the copolymer aqueous dispersion (A) has a carboxyl group. The metal compound (D) can be blended as necessary.

  Examples of the metal compound (D) include those capable of ionic crosslinking with a carboxyl group. Specific examples of the metal compound (D) include copper, silver, lithium, beryllium, zinc, aluminum, cobalt, nickel, calcium, Inorganic salts such as oxides, hydroxides, carbonates and chlorides of metals such as strontium, barium, vanadium, chromium, manganese, iron, tin, zirconium, molybdenum and magnesium; or organometallic complexes such as acetylacetone zinc; etc. Can be mentioned.

  The metal compound (D) in the present invention may be a polyvalent metal compound, preferably a zinc compound, particularly zinc oxide.

  As a usage-amount of a metal compound (C), it exists in the range of 0.001-0.5 mol with respect to 1 mol of carboxyl groups in a copolymer aqueous dispersion (A), Preferably it is 0.02-0.4. It is preferable to be in the molar range.

  In the present invention, when the aqueous coating composition contains a hydrazine derivative (C), the carbonyl group of the copolymer aqueous dispersion (A) is crosslinked with the hydrazine derivative, and the carboxyl of the copolymer aqueous dispersion (A). The crosslinking of the group and the metal compound (D) is used in combination, and the strength of the coating film can be improved.

Compound (E) having two or more functional groups capable of reacting with a carboxyl group in one molecule
For the purpose of improving the adhesion of the formed coating film, the aqueous coating composition of the present invention has 1 functional group capable of reacting with a carboxyl group, particularly when the copolymer aqueous dispersion (A) has a carboxyl group. A compound (E) having two or more molecules in the molecule can be blended as necessary.

  Specific examples of the compound (E) having two or more functional groups capable of reacting with a carboxyl group used for such a purpose include polycarbodiimide compounds and polyoxazoline compounds.

  As the polycarbodiimide compound, a compound having two or more carbodiimide groups in the molecule is suitable, and it is desirable that the compound is water-soluble or water-dispersible, and is not particularly limited, but the carbodiimide equivalent is 100 to 800. It is desirable that the compound be in the range of 200 to 600.

  Specific examples thereof include “Carbodilite V-02”, “Carbodilite V-04”, “Carbodilite V-06”, “Carbodilite E-01”, “Carbodilite E-04” (trade name, manufactured by Nisshinbo Co., Ltd.) And other commercial products. These can be used alone or in a mixture of two or more.

  Examples of the polyoxazoline compound include compounds having two or more oxazoline groups in the molecule, such as 2,2′-p-phenylene-bis- (1,3-oxazoline) and 2,2′-tetramethylene. Low molecular weight poly (1,3-oxazoline) compounds such as -bis- (1,3-oxazoline), 2,2'-octamethylene-bis- (2-oxazoline); and further, 2-isopropenyl-1 1,3-oxazoline obtained by copolymerizing a homopolymer of a 1,3-oxazoline group-containing vinyl monomer such as 1,3-oxazoline or various vinyl monomers copolymerizable therewith And a vinyl polymer containing a group, which is preferably a water-soluble or water-dispersible compound, and is not particularly limited, but the oxazoline group equivalent is 10 800, it is desirable that preferably compounds within the scope of 200 to 600.

  Commercially available products of such polyoxazoline compounds include “Epocross K-1000”, “Epocross K-1020E”, “Epocross K-1030E”, “Epocross K-2010E”, “Epocross K” manufactured by Nippon Shokubai Chemical Industry Co., Ltd. -2020E "," Epocross K-2030E "," Epocross WS-500 "," Epocross WS-700 ", and the like.

  The amount of the compound (E) used is such that the amount of the compound (E) is within the range of 0.1 to 1.0 mol, preferably 1 mol of the carboxyl group in the copolymer aqueous dispersion (A). It is preferable to be within the range of 0.2 to 0.6 mol.

  By using the compound (E), the strength of the coating film is improved by the progress of the crosslinking between the carboxyl group of the copolymer aqueous dispersion (A) and the compound (E), and the reduction of the carboxyl group is accompanied. The water resistance of the formed coating film can be improved and the adhesion to the surface to be coated can be improved.

  In addition, the aqueous coating composition of the present invention can contain a thickener from the viewpoints of coating workability and prevention of pigment settling.

  As the thickener, conventionally known ones can be used without limitation, and specific examples thereof include inorganic compounds such as water-soluble alkali silicate, montmorillonite, colloidal alumina; fibers such as methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, etc. Derivative compounds; polyether compounds such as pluronic polyethers, polyether dialkyl esters, polyether dialkyl ethers, polyether urethane modified products, polyether epoxy modified products; polyacrylic acid soda, polyacrylic acid (meth) acrylic acid Polyacrylic acid compounds such as ester copolymers; polyvinyl compounds such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl benzyl alcohol copolymer; sodium caseinate, casein Protein derivatives such as ammonium; maleic anhydride copolymers such as partial esters of vinyl methyl ether-maleic anhydride copolymer, half esters of a reaction product of drying oil fatty acid allyl alcohol ester-maleic anhydride, etc. Can be used alone or in combination of two or more. In particular, a combination of a fiber derivative-based compound and a polyether-based compound is preferable because it improves the coating workability such as roller coating and spray coating and exhibits good finish.

  When combining a fibrin derivative compound and a polyether compound, the use ratio of both is 1/99 to 99/1, preferably 10/90 to 90 / in mass ratio of fibrin derivative compound / polyether compound. It is preferable to be within the range of 10.

  The amount of the thickener used is 0.01 to 5% by mass, preferably 0.1 to 3% by mass, based on the solid content of the copolymer aqueous dispersion (A).

  In the present invention, the aqueous coating composition includes a resin other than the copolymer aqueous dispersion (A) as necessary, for example, a water-soluble or water-dispersible resin such as an acrylic resin, a urethane resin, and a fluororesin. May be.

  In addition, the above-mentioned water-based paint composition includes an antifoaming agent, a curing catalyst, a pigment dispersant, a fragrance, an antiseptic, a deodorant, an antibacterial agent, a neutralizing agent, a surfactant, an aqueous water repellent, an antifungal agent, a freezing agent. Paint additives such as an inhibitor, an ultraviolet absorber, a light stabilizer, and a film-forming aid can be included as necessary.

The aqueous coating composition of the present invention has very good coating film properties such as water resistance of the formed coating film, and the formed coating film has flexibility even under low temperature conditions and exhibits toughness under normal temperature conditions. can do. Specifically, the elongation at 23 ° C. can be 300% or more, particularly 300 to 900%, the elongation at −20 ° C. is 70% or more, particularly 70 to 200%, and the maximum stress at 23 ° C. is 1 .3 N / mm ² or more, particularly 1.3 to 3.0 N / mm ² .

  In this specification, the elongation rate and the maximum stress of the formed coating film, which are indices of flexibility and toughness, are obtained by coating a sample on a release paper (200 mm × 200 mm) using a doctor blade, a temperature of 23 ° C., a relative humidity of 50 After drying and curing for 2 weeks under the condition of%, the coating film was peeled off to obtain a free coating film having a dry film thickness of about 1 mm. Using the name “Autograph AG2000B type” (manufactured by Shimadzu Corporation), the temperature is 23 ° C. or −20 ° C. and the tensile speed is 200 mm / min.

Coating method The method of the present invention is a coating method for coating the surface to be coated with the aqueous coating composition of the present invention obtained as described above.

  Examples of coated surfaces include gypsum boards, concrete surfaces, mortar surfaces, slate plates, PC plates, ALC plates, cemented calcium silicate plates, base materials such as wood, stone, plastic, metal, etc. Examples of the acrylic resin-based, acrylic urethane resin-based, polyurethane resin-based, fluororesin-based, silicon acrylic resin-based, vinyl acetate resin-based, and epoxy resin-based coating surfaces.

  Since the coating film formed from the aqueous coating composition of the present invention is excellent in adhesion when the coated surface is a coated surface, the sealer step of applying the sealer to the coated surface may be omitted. Is possible.

  On the other hand, the coated surface may be seal-coated using a conventionally known sealer as required.

The coating amount of the aqueous coating composition of the present invention is, for example, 0.1 to ² kg / m ^2, preferably 0.2 to 1.5 kg / m ² .

  As a coating means for applying the aqueous coating composition of the present invention, for example, a known coating device such as a roller, an air spray, an airless spray, a ricin gun, a universal gun or a brush can be used.

  As a method for drying the formed coating film, any one of heat drying, forced drying, and room temperature drying can be employed.

  Moreover, this invention is a coating method characterized by coating the above-mentioned aqueous coating composition on the surface to be coated as an undercoat, and then overcoating the coated surface.

  As the top coating used in the method of the present invention, water-based or organic solvent-based top coatings that can impart coloration and gloss to the finished surface, weather resistance, waterproofing, etc. can be applied without limitation, The paint may be cross-linked or non-cross-linked.

  Examples of the top coat include acrylic resin emulsion-based paints, isocyanate cross-linking curable paints, and the like.

  As the acrylic resin emulsion-based paint, an acrylic resin emulsion is used as a base resin component, and a crosslinking agent that undergoes a crosslinking reaction with the acrylic resin emulsion may be added. A urethane-based resin emulsion or a fluorine-based resin emulsion. Etc. may be blended as necessary.

  The isocyanate cross-linking curable paint is preferably a two-component paint comprising an isocyanate curing agent and a main agent having an active hydrogen that reacts with an isocyanate group. Examples of the main agent include fluorine resins, acrylic resins, and polyester resins. What uses hydroxyl-containing resin, such as resin and silicone resin, as base resin can be used conveniently.

The top coating is applied on the coated surface after the aqueous coating composition of the present invention is applied. As a coating method, a known method such as roller, air spray, airless spray, lysine gun, universal gun, brush, etc. Painting equipment can be used. The coating amount of the top coating is suitably about 0.1 to 0.5 kg / m ² , and the drying method of the formed coating film can be any of heat drying, forced drying, and room temperature drying. .

  The coating film formed by the aqueous coating composition of the present invention has both flexibility at low temperature and toughness at normal temperature, and is excellent in coating film properties such as water resistance, and also with the coated surface and the top coating film. Since the adhesiveness is also excellent, the coating film formed by the aqueous coating composition of the present invention and the multilayer coating film formed by the top coating can maintain the aesthetics of buildings and the like over a long period of time.

  Hereinafter, the present invention will be described in more detail with reference to examples. “Part” and “%” indicate “part by mass” and “% by mass”, respectively.

Production of copolymer aqueous dispersion Production Example 1
Add 300 parts of deionized water and 0.1 part of Newcol 707SF (manufactured by Nippon Emulsifier Co., Ltd., an anionic surfactant having a polyoxyethylene chain, non-volatile content of 30%) to a 2 liter 4-necked flask, and after nitrogen replacement , Kept at 85 ° C. In the pre-emulsion formed by emulsifying the following composition, 3% by mass and 30% by mass of the following catalyst aqueous solution were added and stirred. From 20 minutes after the addition, 97% by mass of the following pre-emulsion and 70% by mass of the following aqueous catalyst solution were added dropwise over 4 hours.
Pre-emulsion Deionized water 287 parts Methacrylic acid 16 parts Styrene 80 parts 2-Ethylhexyl acrylate 664 parts Diacetone acrylamide 40 parts "Newcol 707SF" 53 parts.

Aqueous catalyst solution Ammonium persulfate 1.5 parts Deionized water 120 parts After completion of dropping, 56 parts of deionized water was added, and this was further maintained at 75C for 2 hours, and then cooled to 40C or less. Subsequently, the pH was adjusted to 8 to 9 with aqueous ammonia to obtain a copolymer aqueous dispersion (A-1) having a solid content of 50%. The weight average molecular weight of the obtained copolymer was 290,000.

Production Examples 2-7
In the above Production Example 1, copolymer aqueous dispersions (A-2) to (A-7) were produced in the same manner as in Production Example 1 except that the monomer composition was changed to Table 1.

Production Examples 1 to 23 and Comparative Examples 1 to 8
The components shown in Table 2 were blended in the aqueous copolymer dispersion obtained in the above production example, and mixed by stirring to obtain each water-based coating for base preparation, which was used in the following evaluation tests. Evaluation methods and evaluation criteria are as follows.

(Note 1) extender pigment: calcium carbonate with a specific gravity of 2.7,
(Note 2) Color pigment: Titanium oxide having a specific gravity of 4.1,
(Note 3) Polyoxazoline 1: “Epocross WS-500” trade name, manufactured by Nippon Shokubai Co., Ltd., polyoxazoline, oxazoline group equivalent 220, active ingredient 40%,
(Note 4) Polyoxazoline 2: “Epocross K-2020E”, trade name, manufactured by Nippon Shokubai Co., Ltd., polyoxazoline, oxazoline group equivalent 550, active ingredient 40%,
(Note 5) Polycarbodiimide: “Carbodilite V-02”: trade name, manufactured by Nisshinbo Co., Ltd., water-soluble polycarbodiimide, carbodiimide equivalent 590, active ingredient 40%,
(Note 6) Film-forming auxiliary: “TEXNOL”: trade name, manufactured by Eastman Chemical Co., 2,2,4-trimethylpentanediol monoisobutyrate,
(Note 7) Thickener 1: 2.5% hydroxyethyl cellulose aqueous solution,
(Note 8) Thickener 2: “Adecanol UH-526”, trade name, manufactured by Asahi Denka Co., Ltd., modified polyether urethane,
(Note 9) Antifoaming agent: “SN deformer A63”, trade name, manufactured by San Nopco,
(Note 10) Dispersant: “Nopco Santo K”, trade name, manufactured by San Nopco.

Evaluation test (*) Elongation rate of coating film, maximum stress Each base-forming water-based paint was applied to release paper (200 mm x 200 mm) using a doctor blade, and the temperature was 23 ° C and the relative humidity was 50% for 2 weeks. After drying and curing, the coating film was peeled off to obtain a free coating film having a dry film thickness of about 1 mm. The elongation rate and maximum stress of this free coating film were measured using an Instron tensile tester (trade name “Autograph AG2000B”). The measurement was performed at a temperature of 23 ° C. or −20 ° C. under a tensile speed of 200 mm / min. The higher the value, the better.

(*) Zero-span test Each base adjustment water-based paint is applied to the surface of a plate having a groove having a width of 1 mm and a depth of 3 mm at the center of the back surface of the flexible plate so that the dry film thickness is 1 mm. After drying and curing for 2 weeks under the conditions of a temperature of 23 ° C. and a relative humidity of 50%, the groove on the center of the back surface of the flexible board was pressed with a finger so as not to damage the coating film, and only the flexible board was cracked. This was used as a test body, and this test body was attached to an Instron tensile tester (trade name “Autograph AG2000B type” manufactured by Shimadzu Corporation), and a tensile test was performed at −10 ° C. under a tensile speed of 20 mm / min.
○: Elongation 3.0 mm or more,
X: Elongation is less than 3.0 mm.

(*) Coating workability Each base preparation water-based paint was applied on a mortar plate with a sand-bone roller so that the coating amount was about 1.0 kg / m ^2, and sensory evaluation was performed with respect to workability and finish at that time.
○: There is little splashing and sagging during painting, the roller is easy to move, it is finished evenly and smoothly, and there is no abnormality in the appearance of the coating film.
X: A lot of splash and sagging at the time of coating, the roller is difficult to move, it is difficult to finish uniformly, or the appearance of the coating film is bad.

(*) Initial water resistance After adjusting the water-based paint for forming each base with water to a suitable viscosity for coating, it was coated on a mortar plate with a sand bone roller so that the coating amount was about 1.0 kg / m ^2, and the temperature was 20 It was dried for 4 hours at 80 ° C. and a relative humidity of 80%. Then, each coating plate was sprayed with clean water by spraying, and the coating state was visually evaluated.
○: There is no abnormality in the coating film,
Δ: swelling occurs in the coating film,
X: A part of coating film starts to melt.

(*) Storage stability Put 80 ml of each water-based paint composition into a 100 ml glass wide-mouthed bottle, seal it tightly, store it in a constant temperature bath at 40 ° C for 1 month, and compare the change in state with that before storage. It was evaluated by.
〇: Almost no change,
Δ: Viscosity slightly increases but practical level,
X: Purination.

Coating Examples 24-46 and Comparative Examples 9-16
Each base preparation aqueous paint obtained above was applied on a mortar plate (90 × 300 × 20 mm) with a sand bone roller so that the coating amount was about 1.0 kg / m ^2, and the temperature was 20 ° C. and the relative humidity. It was dried at 75% for 1 day. Next, the top coating material shown in Table 3 was applied onto the base-adjusted coating film by airless spraying so that the coating amount was about 0.2 kg / m ² and dried at a temperature of 20 ° C. and a relative humidity of 75% for 7 days. A painted finish was obtained. Subsequently, the obtained paint finish board was used for the following performance test. The results are shown in Table 3. In Table 3, the types of top coating paints a to d and the performance test methods are as follows.

Topcoat type a. “Ares Aqua Silicon AC”: trade name, manufactured by Kansai Paint Co., Ltd., water-based acrylic silicone resin paint,
b. “Rivel Top”: trade name, manufactured by Kansai Paint Co., Ltd., a two-component water-based acrylic urethane resin-based paint containing a hydroxyl group-containing resin and an isocyanate curing agent,
c. “Ares Aquaretan”: trade name, manufactured by Kansai Paint Co., Ltd., water-based acrylic resin emulsion paint,
d. “Ares Aqua Gloss”: trade name, manufactured by Kansai Paint Co., Ltd., aqueous reaction curable acrylic resin emulsion paint.

(*) Zero-span test with multi-layer coating The amount of each base adjustment aqueous paint applied to the surface of the plate with a groove of 1mm width and 3mm depth at the center of the back side of the flexible plate with sand roller There was applied to approximately 1.0 kg / m ^2, temperature 20 ° C., a relative humidity of 75% and dried for 1 day, then base adjustment member coating weight applied by airless spraying each top coating on the membrane is about 0. After coating for ² kg / m ² and drying for 7 days at a temperature of 20 ° C. and a relative humidity of 75%, press the finger in the center groove on the back of the flexible plate so as not to damage the multilayer coating film. In addition, a sample obtained by dividing only the flexible plate is used as a test body, and this test body is attached to an Instron tensile tester (trade name “Autograph AG2000B type” manufactured by Shimadzu Corporation) at −10 ° C. under a tensile speed of 20 mm / min. A tensile test was performed.
○: Elongation of 3.0 mm or more, no crack up to 3.0 mm,
X: A hole or tear that reaches the undercoat film occurs in the topcoat film when the elongation is less than 3.0 mm.

(*) Water resistance test The coated finish plates obtained in Examples 24 to 46 and Comparative Examples 9 to 16 were immersed in clean water at 20 ° C, and the state of the coating film surface was visually evaluated.
○: No abnormality in the coating film after immersion for 7 days,
Δ: Dandruff occurs in the coating film on the seventh day of immersion.
X: Swelling occurs in the coating film on the third day of immersion.

Claims (10)

An aqueous coating composition containing an aqueous copolymer dispersion (A), a pigment (B) and an adipic acid dihydrazide (C) , wherein the aqueous copolymer dispersion (A) is linear or branched carbon An acrylate (a) containing an alkyl group having 6 or more alkyl groups, a carbonyl group-containing polymerizable unsaturated monomer (b) as a copolymerization component, and a linear or branched alkyl group having 6 or more carbon atoms The copolymerization ratio of the acrylate (a) contained is 65 to 85% by mass , the pigment volume concentration in the composition is in the range of 15 to 60%, and the amount of adipic acid dihydrazide (C) used is An aqueous coating composition characterized by being in the range of 0.01 to 0.3 mol with respect to 1 mol of carbonyl groups contained in the combined aqueous dispersion (A) . The polymerizable unsaturated monomer used in the production of the copolymer aqueous dispersion (A) is selected so that the glass transition temperature of the copolymer is -20 ° C or lower. Water-based paint composition. The copolymer aqueous dispersion (A) is a linear or branched acrylate (a) containing an alkyl group having 6 or more carbon atoms, 65 to 85 % by mass, a carbonyl group-containing polymerizable unsaturated monomer (b). 0.05 to 8 % by mass, linear or branched methacrylate containing 6 or less carbon atoms and / or vinyl aromatic compound (c1) 5 to 20 % by mass, carboxyl group-containing polymerizable unsaturated By copolymerizing the monomer (c2) 1 to 3 % by mass and other polymerizable unsaturated monomers 0 to 28.95 % by mass other than the above monomers (a), (b), (c1) and (c2) The aqueous coating composition according to claim 1 or 2, which is obtained. The aqueous paint composition according to any one of claims 1 to 3, wherein the pigment (B) is a combination of an extender pigment and a color pigment. The water-based coating composition of any one of Claims 1 thru | or 4 which further contains a metal compound (D). The aqueous coating composition according to any one of claims 1 to 5 , further comprising a compound (E) having two or more functional groups capable of reacting with a carboxyl group in one molecule. The aqueous coating composition according to any one of claims 1 to 6, further comprising a thickener, wherein the thickener is a combination of a fiber derivative compound and a polyether compound. A coating method comprising coating the water-based coating composition according to any one of claims 1 to 7 on a surface to be coated. A coating method comprising: coating the surface to be coated with the aqueous coating composition according to any one of claims 1 to 7 as an undercoat, and then overcoating the coated surface. A multilayer coating film formed by the coating method according to claim 9.