JP2001220539A - Water-based paint - Google Patents

Abstract

(57) Abstract: Provided is an aqueous coating material having a concentration region which exhibits pseudoplastic flow in a low concentration region and whose viscosity does not substantially change even when the concentration increases. A paint resin comprising a copolymer of at least one kind of highly hydrophilic group-containing ethylenic monomer and at least one kind of highly hydrophobic group-containing ethylenic monomer,
_{O- (C m H 2m O)} n -H [ wherein, R is an alkyl group, m is an integer of 3 or more, n represents an integer of 1 or more. And at least one organic solvent represented by the formula:

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-based paint.

[0002]

2. Description of the Related Art When coating a paint, it is necessary to control the viscous behavior of the paint in order to obtain high finish quality.
In particular, in the case of a water-based paint to be spray-coated, it is necessary that the viscosity is low at the time of spraying, that the viscosity is so high that it does not drip at the time of coating, and that the viscosity does not increase with the concentration after coating. The former can be realized by the fact that the spray paint exhibits pseudoplastic flow, and the latter can be realized by the fact that the viscosity of the paint has no concentration dependency in a predetermined concentration range. Conventionally, in order to control the viscosity of a water-based paint, a method using a composition comprising a water-soluble acrylic resin and resin particles (JP-A-63-11)
1976) has been proposed. However, in this method, the paint exhibits pseudoplastic flow in a low concentration region, but the viscosity of the paint increases monotonously with the concentration increase, so that the paint condition (particularly, the booth temperature and humidity conditions) fluctuates. The flow properties (leveling properties) of the paint fluctuate, and it is difficult to obtain good finish quality. In particular, when painting a large object to be painted such as an automobile in which concentration distribution tends to occur at the time of painting, the flowability varies depending on the place, and it is difficult to obtain good finish quality. On the other hand, a method using a copolymer of a highly hydrophilic group-containing ethylenic monomer and a highly hydrophobic group-containing ethylenic monomer (Japanese Unexamined Patent Application Publication No. 10-183065)
No.) shows pseudoplastic flow in the low concentration range, and the viscosity increase of the paint with the concentration increase can be reduced. However, depending on the composition of the coexisting solvent, the viscosity increases with the concentration increase, resulting in good finish quality. May not be obtained.

[0003]

SUMMARY OF THE INVENTION The present invention provides a water-based paint having a concentration region in which pseudoplastic flow is exhibited in a low concentration region and the viscosity hardly changes even when the concentration increases, in order to obtain a good finish quality. The purpose is to provide.

[0004]

As means for solving the above-mentioned problems, the present invention provides (A) at least one kind of highly hydrophilic group-containing ethylenic monomer and at least one kind of highly hydrophobic group-containing ethylene. And (B) at least one organic solvent represented by the following formula (1). _{RO- (C m H 2m O)} n -H (1) [ wherein, R is an alkyl group, m is an integer of 3 or more, n represents an integer of 1 or more. ]

A dispersion of a resin containing a highly hydrophilic group and a highly hydrophobic group containing water as a main solvent has a high hydrophobicity due to hydrophobic interaction due to a large amount of water as a solvent in a low concentration region. A group of bases meet and show pseudoplastic flow. Furthermore, as the amount of water decreases with increasing concentration, the association of highly hydrophobic groups decreases and the dispersion changes from an oil-in-water emulsion to a water-in-oil emulsion. Due to the change, the increase in viscosity due to the increase in concentration is suppressed. It is considered that this phase change is likely to be caused by the coexistence of an amphiphilic solvent having good compatibility with resin and water. However, when the amphiphilic solvent has a low boiling point, the above-mentioned phase change is unlikely to occur because it is easy to volatilize in the initial stage of coating (for example, during spraying), and the viscosity may increase as the concentration increases. is there.

In the case of a water-based paint containing the resin specified in the present invention and a predetermined alkylene glycol alkyl ether-based organic solvent, the organic solvent is amphiphilic and has good compatibility with the above resin. In addition, since it has a higher boiling point than water and is less likely to evaporate, an increase in viscosity due to an increase in concentration can be suppressed. As a result, the aqueous paint of the present invention exhibits pseudoplastic flow in a low concentration region, and has a region in which the viscosity hardly changes even when the concentration increases. For this reason, according to the water-based paint using the paint resin, a pseudo-plastic flow is exhibited in a low-concentration region, and since there is a concentration region in which the viscosity hardly changes even when the concentration is increased by spray coating or the like. Even when a large object to be coated such as an automobile has a concentration distribution at the time of coating, leveling is performed uniformly over the entire surface, and good finish quality is obtained.

[0007]

Embodiments of the present invention will be described below in detail. The aqueous coating composition of the present invention comprises a coating resin comprising a copolymer of at least one kind of highly hydrophilic group-containing ethylenic monomer and at least one kind of highly hydrophobic group-containing ethylenic monomer; And at least one organic solvent. _{RO- (C m H 2m O)} n -H (1) [R: alkyl group m = 3 or an integer n = 1 or more integer

The highly hydrophilic group-containing monomer for synthesizing the coating resin contained in the water-based coating of the present invention has a solubility parameter (δsp) of at least 9.5 in the present invention. The δsp is a parameter indicating the cohesive energy between molecules, and is represented by the equation (2). δsp = ((△ Hv−RT) / V) ^1/2 (2) ΔHv: latent heat of vaporization at temperature TK R: molecular gas constant T: absolute temperature V: molecular volume Specifically, using equation (3) The fact that δsp can be determined from the cohesive energy of atomic groups is described in Small (Journal of
Applied Chemistry, vol. 69, 2809p (1953) and Hoy (Journal
of Paint Technology, vo 1.42, No. 541, 76p (1970)). δsp = ρ (ΣG) / M (3) ρ: Density G: Cohesive energy M: Molecular weight

As the highly hydrophilic group-containing ethylenic monomer, an ethylenic monomer having an acidic group and an ethylenic monomer having a hydroxyl group are preferable. Examples of the acidic group of the ethylenic monomer containing an acidic group include carboxylic acid and sulfonic acid. Examples of carboxylic acid-containing monomers include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and the like.Examples of sulfonic acid group-containing monomers include styrene sulfonic acid, vinyl benzene sulfone Acids and the like. The ethylenic monomer containing an acidic group is a half ester of a dibasic acid monomer (maleic acid, fumaric acid, itaconic acid, etc.),
Half amides and half thioesters may be used. Examples of hydroxyl group-containing ethylenic monomers include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate. Examples include hydroxybutyl, vinyl alcohol, allyl alcohol and the like.

When an ethylenic monomer containing an acidic group and an ethylenic monomer containing a hydroxyl group are used as the highly hydrophilic group-containing ethylenic monomer for synthesizing the coating resin contained in the aqueous coating composition of the present invention, It is preferable to use 2 to 15% by weight of an ethylenic monomer having a group and 5 to 30% by weight of an ethylenic monomer having a hydroxyl group. More preferably, 3 to 10% by weight of an ethylenic monomer having an acidic group and 10 to 25% by weight of an ethylenic monomer having a hydroxyl group are used. When the amount of the ethylenic monomer containing an acidic group is less than 2% by weight, water dispersibility is poor,
If the resin aggregates and precipitates and exceeds 15% by weight, the hydrophilicity becomes too high and the water resistance of the coating film decreases. If the amount of the hydroxyl group-containing ethylenic monomer is less than 5% by weight, the curability of the coating film is poor, and if it exceeds 30% by weight, the hydrophilicity becomes too high and the water resistance of the coating film decreases.

The highly hydrophobic group-containing ethylenic monomer for synthesizing the coating resin contained in the water-based coating of the present invention includes:
In the present invention, it indicates an ethylenic monomer having a δsp of less than 9.0. As an ethylenic monomer having a δsp of less than 9.0,
N-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tertiary butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, dodecyl acrylate (lauryl), acrylic Cyclohexyl acrylate, hexadecyl acrylate (cetyl), heptadecyl acrylate, octadecyl acrylate (stearyl),
N-propyl methacrylate, n-butyl methacrylate,
Isobutyl methacrylate, tertiary butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, dodecyl methacrylate (lauryl), cyclohexyl methacrylate, hexadecyl methacrylate (cetyl), heptadecyl methacrylate, methacrylic acid Octadecyl (stearyl) and the like. The highly hydrophobic group-containing ethylenic monomer of the present invention preferably contains at least one kind of ethylenic monomer having an alkyl group having 12 to 24 carbon atoms.

The resin for paint contained in the water-based paint of the present invention is prepared by using the above-mentioned monomer in a reaction vessel in the presence of a solvent, using a polymerization initiator such as an azo compound or an organic peroxide.
It is obtained by polymerizing at a temperature of ° C. for 3 to 15 hours.
As the solvent, methyl alcohol, ethyl alcohol, n
-Propyl alcohol, isopropyl alcohol, n-
Alcohols such as butyl alcohol and isobutyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol mono n-butyl ether, ethylene glycol monoisobutyl ether, propylene glycol Alkylene glycol alkyl ethers such as monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono n-propyl ether, propylene glycol monoisopropyl ether, propylene glycol mono n-butyl ether, propylene glycol monoisobutyl ether, and the like, and mixed solvents thereof can be used. . As azo compounds, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4′-dimethylvaleronitrile), dimethyl 2,
2'-azobisisobutyrate and the like; on the other hand, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisobutyrate, tert-butyl peroxy 2-ethylhexano Eate, cumene hydroperoxide and the like can be used.

The number average molecular weight of this resin is from 2000 to 100,000,
It is preferably from 3,000 to 50,000, and if it is less than 2,000, the viscosity is too low in a low concentration region, so that it is easy to sag and the physical properties of the coating film are inferior. On the other hand, if it exceeds 100,000, the water dispersibility becomes poor, and the viscosity monotonously increases with the increase in the concentration, so that the flow property deteriorates, which is not desirable.

The organic solvent contained in the aqueous coating composition of the present invention is the organic solvent represented by the above formula (1). When m is less than 2 in the organic solvent represented by the formula (1), it is not preferable because it has strong toxicity to the human body. Examples of the organic solvent represented by the formula (1) for obtaining the water-based coating resin of the present invention include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono n-propyl ether, propylene glycol monoisopropyl ether, Propylene glycol mono n-butyl ether, propylene glycol monoisobutyl ether, propylene glycol monotertiary butyl ether, propylene glycol mono n-hexyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono n-propyl ether, Dipropylene glycol monoisopropyl ether, dipropylene glycol mono n-butyl ether, dipropyl Glycol monoisobutyl ether, dipropylene glycol monotertiary butyl ether, dipropylene glycol mono n-hexyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol mono n-propyl ether, tripropylene glycol monoisopropyl Ether, tripropylene glycol mono n-butyl ether, tripropylene glycol monoisobutyl ether, tripropylene glycol monotertiary butyl ether, tripropylene glycol mono n-hexyl ether, butylene glycol monomethyl ether, butylene glycol monoethyl ether, butylene glycol mono n- Propyl ether, butylene glycol Monoisopropyl ether, butylene glycol monobutyl n- butyl ether, butylene glycol monobutyl isobutyl ether, butylene glycol monobutyl tertiary butyl ether, butylene glycol mono n
-Hexyl ether and the like. The alkylene glycol alkyl ether represented by the formula (1) has a boiling point of
It is desirable that the temperature be 150 ° C. or higher. Organic solvent has a boiling point of 150
When the temperature is lower than ° C, the effect of suppressing an increase in viscosity due to an increase in concentration is small because the solvent easily evaporates during spray coating.

In order to disperse a coating resin containing the aqueous coating composition of the present invention in an aqueous medium, it is necessary to at least partially neutralize acidic groups in the resin with a basic substance. Examples of the basic substance include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, diethylenetriamine, triethylenetetramine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, Diisopropanolamine, dimethylethanolamine, morpholine, methylmorpholine, piperazine,
There is ammonia and the like.

The water-based paint of the present invention is often used as a thermosetting paint by adding a crosslinking agent. Examples of crosslinking agents include amino resins and blocked polyisocyanates. Examples of the amino resin include a known partially or completely methylolated amino resin obtained by reacting an aldehyde with an amino component such as melamine, urea, benzoguanamine, and acetoguanamine. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. Further, those obtained by etherifying the methylolated amino resin with an appropriate alcohol can also be used. Examples of the alcohol used for the etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol,
Isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like can be mentioned. Specifically, methyl etherified melamine resin, butyl etherified melamine resin, methyl and butyl mixed etherified melamine resin, methyl and isobutyl mixed etherified melamine resin, and the like can be used. Blocked polyisocyanates are obtained by reacting a blocking agent with all polyisocyanate groups having two or more free isocyanate groups in one molecule. When heated to a temperature higher than the dissociation temperature, the isocyanate groups are regenerated, and Cross-linking reaction occurs. Examples of the polyisocyanate compound include aliphatic isocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, cyclic aliphatic isocyanates such as xylene diisocyanate and isophorone diisocyanate, and aromatic isocyanates such as tolylene diisocyanate. Examples of the blocking agent include phenol compounds, lactam compounds, alcohol compounds,
Oxime compounds and the like are used.

The aqueous coating composition of the present invention may be mixed with a cellulose acetate, an epoxy resin, a polyester resin, an alkyd resin, an acrylic resin or the like, if necessary, when forming the coating. Moreover, the following known components can be contained. That is, organic pigments (quinacridone type such as quinacridone, azo type such as pigment red, phthalocyanine type such as phthalocyanine blue and phthalocyanine green), inorganic pigments (titanium oxide, barium sulfate, calcium carbonate, clay, silica, mica, etc.), Carbon-based pigment (carbon black), metallic powder (aluminum powder, mica-like iron oxide, stainless steel powder, etc.),
Surface conditioner, UV absorber, antioxidant, curing catalyst (dodecylbenzenesulfonic acid, paratoluenesulfonic acid,
Naphthalenesulfonic acid, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, triethylamine, diethanolamine, etc.).

The water-based paint of the present invention can be used as a primer, a primer / intermediate coat, or a primer / intermediate coat / overcoat base either directly on a material to be coated such as a metal (for example, a steel sheet, a surface-treated steel sheet, etc.), plastic or the like. Can be applied to the coated surface. In the present invention, the object to be coated is not particularly limited, and is applied to transport equipment and buildings such as automobiles, ships, aircraft, and the like, or to outer panel coatings such as electric appliances, and is particularly preferable for coatings that require high finish quality such as automobiles. Applied. When used as an automotive paint, for example, 2 coats 1 bake such as a top coat base / clear top coat, 2 coats 2 bake, or 3 coats 2 bake such as intermediate coat / top coat base / clear top coat, 3 coats 1 bake, etc. It can be used as a topcoat base paint (metallic paint or solid color paint) and a solid paint such as a clear topcoat, one coat and one bake. The water-based paint of the present invention is preferably spray-coated on the surface of the object to be coated. In this case, the coating method is not particularly limited, and examples thereof include air spray coating, airless spray coating, air atomization type, and airless atomization type. Alternatively, there is a rotary atomizing electrostatic coating.

[0019]

EXAMPLES The present invention will be described more clearly with reference to examples. The present invention is not limited to these examples.

<Example 1> Synthesis of resin for paint A reaction vessel equipped with a stirrer, a temperature controller and a reflux condenser was charged with 82 parts by weight of isopropyl alcohol, and the temperature was raised to 80 ° C after purging with nitrogen. Here, 5 parts by weight of acrylic acid,
After adding a monomer solution comprising 17 parts by weight of 2-hydroxyethyl acrylate, 66 parts by weight of n-butyl methacrylate, 12 parts by weight of stearyl acrylate and 0.8 parts by weight of azobisisobutyronitrile over 5 hours, 1 hour Stirring was continued to obtain a resin having a number average molecular weight of 15,000. Then, the resin solution was desolvated with an evaporator until the solid content concentration became 80% by weight, and then 6 parts by weight of dimethylethanolamine and 36 parts by weight of deionized water were added to add 60% by weight of solid content.
To obtain a resin dispersion for aqueous paint.

<Example 2> Synthesis of resin for coating material A reaction vessel equipped with a stirrer, a temperature controller and a reflux condenser was charged with 82 weight of ethylene glycol monomethyl ether.
After purging with nitrogen, the temperature was raised to 80 ° C. Here, 7 parts by weight of metal acrylate, 2-hydroxyethyl methacrylate 19
Parts by weight, n-butyl acrylate 62 parts by weight, stearyl acrylate 12 parts by weight and azobisisobutyronitrile 0.
After the monomer solution consisting of 8 parts by weight was added over 5 hours, stirring was continued for 1 hour to obtain a resin having a number average molecular weight of 14,000. The resin solution was desolvated with an evaporator until the solid content concentration became 80% by weight, and then 6 parts by weight of dimethylethanolamine and 36 parts by weight of deionized water were added to form an aqueous coating composition having a solids concentration of 60% by weight. A resin dispersion was obtained.

<Example 3> Preparation of aqueous paint A melamine resin (Cymel manufactured by Mitsui Cytec Co., Ltd.) was added to the resin dispersion for aqueous paint having a solid content of 60% by weight prepared in Example 1.
325) was added so that the solid content weight ratio of the water-based paint resin and the melamine resin was 10: 3, and further added to the solid content of the resin (total of the water-based paint resin and the melamine resin) by 20%.
% By weight of dipropylene glycol mono-n-propyl ether and 10% by weight of aluminum powder based on the solid content of the resin were added and diluted with water to prepare an aqueous paint having a solid content of 25% by weight.

Example 4 Preparation of Water-Based Paint A melamine resin (Mycoat 508 manufactured by Mitsui Cytec Co., Ltd.) was added to the resin dispersion for water-based paint having a solid content concentration of 60% by weight prepared in Example 1 and the above-mentioned resin for water-based paint. The melamine resin is added so that the solid content weight ratio becomes 10: 3, and further added to the resin (total of the above-mentioned water-based paint resin and the melamine resin) solid content.
20% by weight of dipropylene glycol mono n-butyl ether and 10% by weight of aluminum powder based on the solid content of the resin were added and diluted with water to prepare an aqueous coating material having a solids concentration of 25% by weight.

<Example 5> Preparation of aqueous paint A melamine resin (Mycoat 508 manufactured by Mitsui Cytec Co., Ltd.) was added to the aqueous paint resin dispersion having a solid content concentration of 60% by weight prepared in Example 2 and the above-mentioned aqueous paint resin. The melamine resin is added so that the solid content weight ratio becomes 10: 3, and further added to the resin (total of the above-mentioned water-based paint resin and the melamine resin) solid content.
20% by weight of tripropylene glycol mono-n-propyl ether and 10% by weight of aluminum powder based on the solid content of the resin were added and diluted with water to prepare an aqueous coating material having a solids concentration of 25% by weight.

<Comparative Example 1> Preparation of water-based paint A melamine resin (Cymel manufactured by Mitsui Cytec Co., Ltd.) was added to the resin dispersion for water-based paint having a solid content concentration of 60% by weight prepared in Example 1.
325) is added so that the weight ratio of the solid content of the resin for water-based paint and the melamine resin is 10: 3, and 10% based on the solid content of the resin (total of the resin for water-based paint and the melamine resin).
% By weight of aluminum powder and diluted with water to prepare an aqueous paint having a solid content of 25% by weight.

<Comparative Example 2> Synthesis of resin for coating material A reaction vessel equipped with a stirrer, a temperature controller and a reflux condenser was charged with 82 parts by weight of isopropyl alcohol, and the temperature was raised to 80 ° C after purging with nitrogen. Here, 5 parts by weight of acrylic acid,
2-hydroxyethyl acrylate 18 parts by weight, methyl methacrylate 77 parts by weight and azobisisobutyronitrile 0.
After the monomer solution consisting of 8 parts by weight was added over 5 hours, stirring was continued for 1 hour to obtain a resin having a number average molecular weight of 13,000. The resin solution was desolvated with an evaporator until the solid content concentration became 80% by weight, and then 7 parts by weight of dimethylethanolamine and 35 parts by weight of deionized water were added to form an aqueous paint having a solids concentration of 60% by weight. A resin dispersion was obtained.

<Comparative Example 3> Preparation of water-based paint A melamine resin (Cymel manufactured by Mitsui Cytec Co., Ltd.) was added to the resin dispersion for water-based paint having a solid content concentration of 60% by weight prepared in Comparative Example 2.
325) was added so that the solid content weight ratio of the water-based paint resin and the melamine resin was 10: 3, and further added to the solid content of the resin (total of the water-based paint resin and the melamine resin) by 20%.
% By weight of dipropylene glycol mono-n-propyl ether and 10% by weight of aluminum powder based on the solid content of the resin were added and diluted with water to prepare an aqueous paint having a solid content of 25% by weight.

-Evaluation of Viscosity of Aqueous Paint- <Example 6> For the aqueous paints prepared in Examples 3, 4, 5, and Comparative Examples 1 and 3, the shear rate dependence of the viscosity was measured with a rotary viscometer. The viscosity behavior (pseudoplastic flow or Newtonian flow) was examined (Table 1), and the viscosity of the paint whose concentration was increased to 30 to 50% by weight was measured at a shear rate of 10 ^-1 s ^-1 using a rotary viscometer. (FIG. 1).

[0029]

[Table 1] As shown in Table 1, the water-based paints of Examples 3 to 5 all showed pseudoplastic flow, whereas the water-based paint of Comparative Example 1 showed pseudoplastic flow, but the water-based paints of Comparative Example 3 Was Newtonian flow. Further, as shown in FIG.
In the water-based paints Nos. To 5, when the solid content concentration was 30 to 50% by weight, the viscosity was almost constant without depending on the concentration.
In contrast, the water-based paints of Comparative Examples 1 and 3 increased in viscosity with concentration in the range of 25 to 50% by weight.

<Evaluation of Finish><Example7> The water-based paints prepared in Examples 3, 4, and 5 and Comparative Examples 1 and 3 were applied to a steel sheet which had been subjected to electrodeposition coating and intermediate coating by a dry coating film having a thickness of 20 μm. Air spray coating was performed to evaluate the coating properties. Next, the coated plate was baked in a dryer at 140 ° C. for 30 minutes, and the finished quality was evaluated. Finish quality was checked on the skin. Table 2 shows the results.

[0031]

[Table 2] As shown in Table 2, all of the water-based paints of Examples 3 to 5 had good coatability and physical properties of the coating film (skin).

[0032]

According to the present invention, there is provided a water-based paint having a concentration region in which pseudoplastic flow is exhibited in a low concentration region and the viscosity hardly changes even when the concentration increases.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a solid content concentration and a viscosity of a water-based paint of an example and a water-based paint of a comparative example.

Continuing from the front page (72) Inventor Hiroshi Nakamura 41-cho, Yokomichi, Nagakute-machi, Aichi-gun, Aichi Prefecture Inside of Toyota Central Research Laboratory Co., Ltd. (72) Inventor Masafumi Harada 41, Oku-michi, Nagakute-machi, Aichi-gun No. 1 Inside Toyota Central Research Institute Co., Ltd. (72) Inventor Kazuyuki Tachi 41-cho, Chukumi Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture No. 1 Inside Toyota Central Research Institute Co., Ltd. (72) Inventor Mamoru Mitsuzaki Toyota, Toyota City, Aichi Prefecture No. 1 Toyota Motor Corporation (72) Inventor Yasumasa Okumura 33-1, Kanzakicho, Amagasaki City, Hyogo Prefecture Kansai Paint Corporation (72) Inventor Motoshi Yabuta 33-1, Kanzakicho, Amagasaki City, Hyogo Prefecture F term in Kansai Paint Co., Ltd. (reference) 4J038 CC091 CE011 CE021 CG011 CG031 CG071 CG141 CG151 CH121 EA011 GA03 GA06 GA13 JA27 KA06

Claims (4)

[Claims] 1. A coating resin comprising: (A) a copolymer of at least one kind of highly hydrophilic group-containing ethylenic monomer and at least one kind of highly hydrophobic group-containing ethylenic monomer; An aqueous paint comprising at least one of the following organic solvents: _{RO- (C m H 2m O)} n -H [ wherein, R is an alkyl group, m is an integer of 3 or more, n represents an integer of 1 or more. ] 2. The organic solvent has a boiling point of 150 ° C. or higher.
The aqueous paint according to claim 1. 3. The water-based coating composition according to claim 1, wherein said highly hydrophilic group-containing ethylenic monomer is an acidic group-containing monomer and / or a hydroxyl group-containing monomer. 4. The water-based paint according to claim 1, wherein said highly hydrophobic group-containing ethylenic monomer is an ethylenic monomer having an alkyl group having 12 to 24 carbon atoms.