JP2002256211A - Aqueous coating composition, method for coating film formation and coated material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous coating composition holding a balance of contradictory properties between polishing properties and chipping resistance, especially as an intercoating, to provide a method for forming a coating film and to obtain a coated material. SOLUTION: This aqueous coating composition comprises a polyester resin, a crosslinking agent and (a) a core/shell type emulsion having >=90 deg.C glass transition temperature of core part and/or (b) a crosslinkable resin particle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous coating composition,
The present invention relates to a method for forming a multilayer coating film and a coated article coated by this method.

[0002]

2. Description of the Related Art When a vehicle is running, it is unavoidable that splashed pebbles or the like collide with the coating surface of the vehicle body outer panel. When the pebbles collide with the coating film, a so-called chipping phenomenon may occur in which the coating film cracks or peels off. When a chipping phenomenon occurs in the coating film, water or the like enters from this portion, and rusts the base surface of the substrate to be coated. In North America, Canada, Northern Europe, etc., large amounts of rock salt and sand are sprayed on the road surface in winter to melt snow.In such areas, chipping resistance, especially in the coating of automobile outer panels, is important. There is a demand for a coating film in which the coating film does not peel off even if it collides, and the base material of the substrate to be coated does not rust.

[0003] For this reason, Japanese Patent Application Laid-Open No. Hei 6-41494 discloses a chipping-resistant coating material comprising a block polyisocyanate compound to which polycaprolactone diol is bonded and a resin containing two or more hydroxyl groups in one molecule. A composition and a method for forming a chipping-resistant coating film using the paint are described.

[0004] The above-mentioned chipping-resistant coating composition is very excellent in chipping resistance. However, when repairing a coating film formed using this chipping-resistant coating composition,
Although the area around the repaired part is polished, there is a problem in terms of sharpness that the polished coating film powder is entangled with the abrasive paper.

Conventionally, organic solvent-based paints have been mainly used as automotive paints, but there is a strong demand for a shift to water-based paints from the viewpoints of safety during painting, reduction of environmental pollution, and resource saving. I have. For example, Japanese Patent Application Laid-Open No. 2000-104010 discloses that a core having a glass transition temperature of −20 to 50 ° C., a glass transition temperature of a shell portion higher than 50 ° C., and a total glass transition temperature of both portions of 30 ° C. or less. An aqueous coating composition containing a shell emulsion and a film-forming aid which is an alcohol component having a boiling point of 100 to 270 ° C is described. When this aqueous coating composition is used as an intermediate coating for automobiles, there is a problem in the above-mentioned chipping resistance.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an aqueous coating composition, a method for forming a coating film, and a coated product, particularly as an intermediate coating material, which maintain a balance between contradictory abrasiveness and chipping resistance. To provide.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, have reached the present invention. 1. An aqueous coating composition containing a polyester resin, a crosslinking agent, (a) a core-shell emulsion having a glass transition temperature of the core of 90 ° C. or more and / or (b) crosslinkable resin particles. 2. The glass transition temperature of the core-shell emulsion of (a) the core portion of the core-shell emulsion is 100 to 150 ° C. and / or the glass transition temperature of the shell portion of the (b) crosslinkable resin particle is −20 to +45. The above-mentioned aqueous coating composition having a temperature of ° C. 3. The above-mentioned component (a) is contained in an amount of 5 to 50 solid parts by mass and / or the component (b) is contained in an amount of 5 to 50 solid parts by mass based on 100 parts by mass of the total solid content of the polyester resin and the crosslinking agent. Aqueous paint composition. 4. The above aqueous coating composition wherein the mixing ratio by mass of the solid content between the component (a) and the component (b) is (a) / (b) = 10/90 to 50/50. 5. The above aqueous coating composition, wherein the crosslinking agent is an amino resin and / or a blocked polyisocyanate compound. 6. A coating film forming method in which an intermediate coating film is formed on the base material on which an undercoat coating film is formed using the above-mentioned aqueous coating composition, and then a topcoat coating film is formed using a topcoat paint. 7. A coated article coated by the above-mentioned coating film forming method.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.

Water-based coating composition The water-based coating composition of the present invention comprises: (a) a glass transition temperature of a core of 90 ° C. or higher in order to maintain a balance between chipping resistance and abrasiveness in a polyester resin and a crosslinking agent; And / or (b) crosslinkable resin particles.

(A) The glass transition temperature of the core portion is 90 ° C. or less
Core-Shell Type Emulsion The core-shell type emulsion of the component (a) is a non-crosslinkable acrylic resin emulsion obtained by multi-stage emulsion polymerization. The component (a) has a core portion having a glass transition temperature of 90 ° C. or higher, and more preferably 100 to 15 ° C.
0 ° C. The addition of the core-shell type emulsion of the component (a) improves the balance between conflicting abrasiveness and chipping resistance.

The above-mentioned core-shell emulsion of the component (a) is an emulsion obtained by multistage emulsion polymerization. The polymer portion formed by polymerization of the monomer component added at the final stage of the multistage emulsion polymerization reaction is defined as a shell portion. The multi-stage emulsion polymerization may be divided into a two-stage reaction of a former stage for a core and a latter stage for a shell,
The reaction may be divided into two or more stages. When performing a multi-stage emulsion polymerization of two-stage reaction or more, since the polymer portion formed by polymerization of the monomer component added to the polymerization system in the final stage is located in the outermost layer of the emulsion particles, in the present invention, This polymer part is called a shell part. In the case of a multi-stage emulsion polymerization of three or more stages, it can be distinguished from a core portion, an intermediate layer portion (plural), and a shell portion. The body component is referred to as a core component monomer component, and the polymer portion constituted by the monomer component is referred to as a core portion.

[0012] The core-shell type emulsion of the above-mentioned component (a) is used when a polymer portion formed by polymerization of a monomer component added before the final stage of a multistage emulsion polymerization reaction is used as a core portion. Glass transition temperature (Tg)
To 90 ° C. or higher, preferably 100 to 150 ° C., and the monomer component constituting the core-shell type emulsion is selected so that the Tg of the shell is −20 to + 45 ° C. An aqueous coating film capable of maintaining a good balance between chipping resistance and grindability can be formed without deteriorating film forming properties.

When the Tg of the core portion of the core-shell emulsion in the component (a) is less than 90 ° C., the grindability decreases. If the Tg of the core exceeds 150 ° C., the chipping resistance may be insufficient. Further, if the Tg of the shell portion is less than -20 ° C, the sharpness may decrease, and if the Tg of the shell portion exceeds + 45 ° C, the chipping resistance may be insufficient.

In order to obtain an aqueous coating film capable of exhibiting both the above-mentioned chipping resistance and abrasiveness, the mass of the monomer component constituting the core portion is determined by changing the mass of all the simple components constituting the core / shell type emulsion. The content is preferably 10 to 90% by mass in the monomer component. Particularly preferably, the content is 50 to 85% by mass. When the mass of the monomer component constituting the core portion exceeds 90% by mass, the shell portion is too small, and the chipping resistance may be insufficient. When the mass is less than 10% by mass, the core portion is small. Too much, there is a possibility that the grinding performance is not sufficiently exhibited.

The monomers having a low glass transition temperature include:
Ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, and the like, while monomers having a high glass transition temperature include , Acrylic acid, methacrylic acid, methyl acrylate, isopropyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, 2-hydroxy methacrylate Ethyl, hydroxypropyl methacrylate, etc.
Examples thereof include (meth) acrylic acid alkyl esters, styrene, and acrylonitrile.

Here, Tg (K) is obtained by the following equation.

[0017]

(Equation 1)

[0018] In _{addition, Tg 1, Tg 2, Tg} i, Tg n is,
Polymer Hand Book (Second
Edition, J.M. Brandup E. H. Imm
ergut). The total Tg of the core part and the shell part is (mass% of core part × Tg of core part) +
It can be calculated by (mass% of shell part × Tg of shell part).

The core-shell type emulsion (a) preferably has an acid value of 5 or more and has a carboxyl group-containing monomer. When the acid value is less than 5, the effect of improving the grinding property is small. A more preferred acid value is from 5 to 80. 8
If it exceeds 0, the water solubility increases, and the particle properties of the emulsion may be lost. A particularly preferred acid value range is 1
0 to 70.

The carboxyl group-containing monomer is a compound having at least one carboxyl group and at least one polymerizable double bond in one molecule. Specific examples thereof include (meth) acrylic acid, itaconic acid and fumaric acid. , Maleic acid,
Carboxylic acids containing a polymerizable unsaturated group such as maleic anhydride, crotonic acid, citraconic acid, maleic acid monoester, fumaric acid monoester, itaconic acid monoester, citraconic acid monoester, etc., alone or in combination of two or more Can be used.

The above-mentioned core-shell type emulsion comprises a carboxyl group-containing monomer which is an essential component and a monomer other than the carboxyl group-containing monomer (hereinafter referred to as “other monomer”) in the core portion. Or shell part.

The other monomers include methyl (meth) acrylate, ethyl (meth) acrylate, (meth)
(Meth) acrylic acid such as butyl acrylate, 2-ethylhexyl (meth) acrylate and C ₁ -C ₁₈ (aliphatic,
(Meth) acrylates which are esters of alcohols (including alicyclic and aromatic); (meth) acrylic acid 2
-Hydroxyethyl, 2-hydroxypropyl (meth) acrylate, hydroxyl group-containing (meth) acrylates such as monoester of (meth) acrylic acid and polypropylene glycol; (meth) acrylamide;
N-monomethyl (meth) acrylamide, N-monoethyl (meth) acrylamide, N, N-dimethyl (meth)
(Meth) acrylamide derivatives such as acrylamide;
Basic polymerizable monomers such as dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, vinylpyridine, vinylimidazole, and vinylpyrrolidone; N-methylol (meth) Acrylamide, N-
Crosslinkable (meth) acrylamides such as butoxymethyl (meth) acrylamide; styrene, vinyltoluene, α
Styrene derivatives such as methylstyrene and chloromethylstyrene; vinyl esters such as vinyl acetate and vinyl propionate; halogenated monomers such as vinyl fluoride, vinylidene fluoride, vinyl chloride and vinylidene chloride; butadiene, isoprene Conjugated dienes such as ethylene; olefins such as propylene and butene;
One or more of these can be used in combination.

The above-mentioned core-shell type emulsion is produced by performing two or more stages of multi-stage emulsion polymerization. In the above-mentioned emulsion polymerization, any known radical polymerization initiator can be used without any particular limitation. Specifically, persulfates and peroxides such as ammonium persulfate, sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide, and t-butyl peroxybenzoate; 2,2'-azobisisobutyro Water solubility such as nitrile, 2,2'-azobis (2-amidinopropane) hydrochloride, 2,2'-azobis (2,4-dimethylvaleronitrile), 4,4'-azobis (4-cyanopentanoic acid) Azo compounds can be mentioned. The amount used is 0.1% of the monomer component.
About 1% by mass is preferable. When accelerating the polymerization rate or when polymerizing at a low temperature, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, or Rongalite may be combined.

The emulsifier is not particularly limited either, and fatty acid salts such as sodium lauryl sulfate, higher alcohol sulfates, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether sulfate, polyoxynonylphenyl Anionic surfactants such as alkyl allyl polyether sulfates such as ammonium ether sulfonate, polyoxyethylene polyoxypropylene glycol ether sulfate, and reactive emulsifiers such as monomers having a sulfonic acid group or a sulfate group; Polyoxyethylene alkylphenyl such as polyoxyethylene alkyl ether and polyoxynonylphenyl ether, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene-polyoxy Nonionic surfactants such as ropylene block copolymers and reactive nonionic surfactants; cationic surfactants such as alkylamine salts and quaternary ammonium salts; and a known emulsifier such as (modified) polyvinyl alcohol are added. Just do it.

The above-mentioned emulsifiers can be used alone or in combination of two or more.
It is good to use about 01 to 10 mass%. Further, if necessary, t-dodecyl mercaptan, n- octyl mercaptan, n- dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid, may be used a chain transfer agent such as 2-mercaptoethanol. The polymerization temperature is 0 to 100 ° C, preferably 50 to 80 ° C, and the polymerization time is 1 to 15 hours. The emulsion polymerization may be added a hydrophilic solvent and additives.

The amount of the component (a) in the aqueous coating composition is determined based on the total solid content of the polyester resin and the crosslinking agent.
5 to 50 parts by mass of solid content is preferable to 0 parts by mass.
If the amount is less than 5 solid parts by mass, chipping resistance and abrasiveness may be insufficient, and if it exceeds 50 solids parts, the coating film appearance may be insufficient. More preferably, it is 10 to 25 parts by mass of solid content.

(B) Crosslinkable Resin Particles The above (b) crosslinkable resin particles are acrylic resin emulsions having crosslinkability in the core obtained by multi-stage emulsion polymerization in the same manner as the component (a). The shell portion of the component (b) can be obtained by synthesizing the same configuration as the core-shell emulsion of the component (a).

In order to synthesize so that the core portion of the component (b) has a crosslinkable substance, a compound having two or more radically polymerizable ethylenically unsaturated groups in the molecule is used. Such compounds (hereinafter referred to as “crosslinkable compounds”) include polymerizable unsaturated monocarboxylic acid ester compounds of polyhydric alcohols, polymerizable unsaturated alcohol ester compounds of polybasic acids, and two or more vinyl groups. Substituted aromatic compounds, adducts of an epoxy group-containing ethylenically unsaturated monomer and a carboxyl group-containing ethylenically unsaturated group monomer and the like can be mentioned. The following compounds and monomers can be used alone or in combination of two or more.

Examples of the above-mentioned polymerizable unsaturated monocarboxylic acid ester compounds of polyhydric alcohols include ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and 1,3-butylene glycol. Dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol diacrylate, 1, 6-hexanediol dimethacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, pentaerythritol Acrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, glycerol diacrylate, glycerol dimethacrylate, glycerol acroxy dimethacrylate, 1,1,1-trishydroxymethylethane diacrylate, 1 1,1,1-trishydroxymethylethane dimethacrylate, 1,1,1-trishydroxymethylethanetriacrylate, 1,1,1-
Trishydroxymethylethanetrimethacrylate,
Examples thereof include 1,1,1-trishydroxymethylpropane diacrylate and 1,1,1-trishydroxymethylpropane dimethacrylate.

Examples of the above-mentioned polymerizable unsaturated alcohol ester compounds of polybasic acids include diallyl terephthalate, diallyl phthalate, triallyl trimellitate and the like. Examples of the aromatic compound substituted with two or more vinyl groups include divinylbenzene.

Glycidyl acrylate or glycidyl methacrylate and acrylic acid, methacrylic acid, crotonic acid, maleic acid are used as adducts of the above-mentioned epoxy group-containing ethylenically unsaturated monomer and carboxyl group-containing ethylenically unsaturated group monomer. And the like. These monomers can be used alone or in combination of two or more.

The core of the cross-linkable resin particles (b) has a cross-linking property. For this purpose, a preferable ratio in the total amount of the compounds for forming the core of the cross-linkable compound is 1 to 20% by mass. It is. If the proportion is less than 1% by mass, both the chipping resistance and the abrasive property may be insufficient, and if it exceeds 20% by mass, the chipping resistance may be insufficient. More preferably, it is 2 to 10% by mass.

As the compound other than the crosslinkable compound forming the core of the crosslinkable resin particles (b), the monomer used in the core / shell emulsion of the component (a) is used. A preferable ratio of the compounds other than the crosslinkable compound to the total amount of the compounds is 80 to 99% by mass.

The method for synthesizing the crosslinkable resin particles (b) is the same as the method for synthesizing the core-shell type emulsion of the component (a), and the description thereof is omitted. The glass transition temperature of the shell portion of the (b) crosslinkable resin particles is -20 to 20.
Preferably it is + 45 ° C.

The compounding amount of the component (b) in the aqueous coating composition is 10% in total solid content of the polyester resin and the crosslinking agent.
5 to 50 parts by mass of solid content is preferable to 0 parts by mass.
If the amount is less than 5 solid parts by mass, chipping resistance and abrasiveness may be insufficient, and if it exceeds 50 solids parts, the coating film appearance may be insufficient. More preferably, it is 10 to 25 parts by mass of solid content.

When the core-shell type emulsion of the component (a) and the crosslinkable resin particles of the component (b) are used in combination, the mixing ratio (a) / (b) = 10
/ 90 to 50/50 are preferred. In this range, the chipping resistance and the sharpening property are further improved.

The average particle diameter of the core-shell type emulsion (a) and the crosslinkable resin particles (b) is preferably from 10 to 1,000 nm. If the average particle diameter is less than 10 nm, the chipping resistance may be insufficient, and if it exceeds 1000 nm, the appearance of the formed coating film may be insufficient.

Polyester resin Examples of the polyester resin include a saturated polyester resin and an unsaturated polyester resin. Examples thereof include a condensate obtained by heat-condensing a polybasic acid and a polyhydric alcohol. Examples of the polybasic acids include saturated polybasic acids and unsaturated polybasic acids. Examples of the saturated polybasic acids include phthalic anhydride, terephthalic acid, and succinic acid. Examples of the acid include maleic acid, maleic anhydride, fumaric acid and the like. Examples of polyhydric alcohols include dihydric alcohols and trihydric alcohols. Examples of dihydric alcohols include ethylene glycol and diethylene glycol. Examples of trihydric alcohols include glycerin and trimethylolpropane. And the like. If necessary, a monohydric alcohol or a monoepoxy compound having one glycidyl group in the molecule (“Kadura E” manufactured by Shell Chemical Co., Ltd.) may be used in combination.

It is preferable to use a urethane-modified polyester resin in combination with the above-mentioned polyester resin component, because the chipping resistance is more excellent.

The urethane-modified polyester resin is obtained by reacting a polyisocyanate compound with a polyester resin obtained by reacting a polyhydric alcohol component and a polybasic acid component as exemplified above. Examples of the polyisocyanate compound include araliphatic polyisocyanate compounds such as xylylene diisocyanate, meta- or para-tetramethyl xylylene diisocyanate, aromatic polyisocyanate compounds such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and isophorone. Diisocyanate, hexamethylene diisocyanate, and their burettes and isocyanurates, trimethylhexamethylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated 4,
Examples thereof include aliphatic polyisocyanates such as 4′-diphenylmethane diisocyanate and alicyclic polyisocyanates. Preferred are xylylene diisocyanate, tolylene diisocyanate and isophorone diisocyanate.

The amount of the urethane-modified polyester resin used in combination may be the total amount of the polyester resin and the crosslinking agent.
10 to 50 parts by mass of a solid content is preferable with respect to 0 parts by mass. If the amount is less than 10 parts by mass, the chipping property may be insufficient. If the amount exceeds 50 parts by mass, the hardness of the multilayer coating film may be insufficient. More preferably, the total resin of the polyester resin and the crosslinking agent is 100
It is 25 to 50 parts by mass of solid content with respect to parts by mass.

The acid value of the polyester resin is 10 to 1
00, more preferably 30-80, and the hydroxyl value is preferably 20-300, more preferably 50-2.
00. If the acid value is less than 10, the aqueous solution may be insufficient, and if it exceeds 100, the water resistance of the coating film may be reduced. Further, when the hydroxyl value is less than 20, the curability of the coating film may be insufficient, and 300
If it exceeds 300, the water resistance of the coating film may decrease.

The number average molecular weight of the above polyester resin is 1,000 to 50,000, preferably 2,000 to 30,
000 is suitable. If the number average molecular weight is less than 1000, the hardness of the coating film, water resistance may be reduced,
On the other hand, if it exceeds 50,000, atomization at the time of spray coating becomes worse, and as a result, the smoothness of the coating film may be reduced.

Crosslinking Agent As the above-mentioned crosslinking agent, preferably, an amino resin and / or a blocked polyisocyanate compound can be used.

Examples of the above-mentioned amino resin include methylolated amino obtained by reacting an amino component such as melamine, urea, benzoguanamine, acetoguanamine, steloguanamine, spiroguanamine and dicyandiamide with an aldehyde such as formaldehyde, acetaldehyde, paraformaldehyde and benzaldehyde. Resins. The above-mentioned methylolated amino resin is methyl alcohol, ethyl alcohol, n-propyl alcohol, i-
Those etherified with alcohols such as propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethylbutanol, and 2-ethylhexanol can be used.

Commercially available amino resins include Cymel 303, Cymel 325, Cymel 1156 (manufactured by Mitsui Cyanamid), U-Van 20N, and U-Van 20S.
B, U-Van 128 (Mitsui Chemicals), Sumimar M-
50W, Sumimar M-40N, Sumimar M-30W
(Manufactured by Sumitomo Chemical Co., Ltd.) and at least one of hydrophilic melamine and / or hydrophobic melamine resins.

In the above-mentioned blocked polyisocyanate compound, an excess of active isocyanate groups is blocked by a blocking agent described later. Further, a polyisocyanate in which active isocyanate groups are partially blocked in advance by a blocking agent can also be used.

As the above polyisocyanate compound,
Although it is possible to use those used in the urethane-modified polyester resin, more preferably an aliphatic polyisocyanate, hexamethylene diisocyanate,
Lysine diisocyanate, trimethylhexamethylene diisocyanate and the like can be mentioned. Further, a multimer of these polyisocyanates can be used. These aliphatic polyisocyanates include adducts such as polyhydric alcohols, burettes, and isocyanurates. In the present invention, burettes or isocyanurates are preferable, and burettes are more preferable. Things. By using a burette type polyisocyanate, a coating film which is soft and has good chipping resistance can be obtained.

Examples of the blocking agent for blocking the active isocyanate group of the polyisocyanate compound include oximes, lactams such as ε-caprolactam, phenols such as phenol and xylenol, and alcohols. It is preferably used as an agent. Specific examples of the oximes used as the blocking agent include methyl ethyl ketone oxime, acetoaldoxime and the like.

The above polyester resin is used in a mixture with the above crosslinking agent, and the curing reaction can proceed at heating or at room temperature.

The proportions of the polyester resin and the crosslinking agent are, as solid contents, 90 to 50% by mass of the polyester resin and 10 to 50% by mass of the crosslinking agent, preferably 85 to 60% by mass of the polyester resin. Yes, 1 crosslinking agent
5 to 40% by mass. If the crosslinking agent is less than 10% by mass (the polyester resin exceeds 90% by mass), the crosslinking in the coating film is not sufficient. On the other hand, when the crosslinking agent exceeds 50% by mass (when the polyester resin is less than 50% by mass), the storage stability of the coating composition is reduced and the curing speed is increased, so that the appearance of the coating film may be reduced.

In the aqueous coating composition, a brilliant pigment and / or a coloring pigment and, if necessary, an extender pigment can be used. As the glitter pigment, preferably, aluminum flake pigment, metal oxide-coated aluminum flake pigment, metal oxide-coated alumina flake pigment, metal oxide-coated silica flake pigment, graphite pigment, interference mica pigment, colored mica pigment, metal titanium Flake pigments, stainless flake pigments, plate-like iron oxide pigments, phthalocyanine flake pigments, metal-plated glass flake pigments, metal oxide-coated glass flake pigments, hologram pigments and the like. Further, as the coloring pigment, as an organic pigment, an azo lake pigment, an insoluble azo pigment, a condensed azo pigment, a phthalocyanine pigment, an indigo pigment, a perinone pigment, a perylene pigment, a phthalone pigment, a dioxazine pigment, and a quinacridone pigment are used. Pigments, isoindolinone pigments, metal complex pigments, and the like can be mentioned, and inorganic iron oxides include yellow iron oxide, red iron oxide, carbon black, and titanium dioxide. Examples of the extender include talc, calcium carbonate, precipitated barium sulfate, and silica. When the pigment is added here, the mass concentration (PWC) of the pigment in the solid content of the paint is 1 to
It is preferably 60% by mass, more preferably 10 to 50% by mass.

The above-mentioned aqueous coating composition contains, in addition to the above components,
Polyamide wax which is a lubricant dispersion of aliphatic amide and polyethylene wax which is a colloidal dispersion mainly composed of polyethylene oxide, anti-settling agent, curing catalyst, ultraviolet absorber, antioxidant, leveling agent, silicone and organic polymer Surface conditioning agents, anti-sagging agents, thickeners, defoamers, etc.
An additive such as a lubricant can be appropriately added and contained.

If necessary, ether alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and ethylene glycol monobutyl ether, methanol, ethanol, isopropanol, n-butanol, sec-butanol, t-
A small amount of a hydrophilic organic solvent such as alcohol, ester, and ketone such as butanol may be used.

The aqueous coating film using the aqueous coating composition is formed by spray coating or roll coating. The formed aqueous coating film is set at room temperature, and overcoated by wet-on-wet or wet-on-dry. Overcoat the membrane.

The viscosity of the aqueous coating composition at the time of coating may be appropriately changed according to the coating method. Prepare at 4 to 30-40 seconds / 20 ° C.

[0057] A method of forming a coating film forming a coating film The present invention is a base material undercoating film is formed, after forming the intermediate coating film using the above aqueous coating composition, using a top coat paint It forms a top coat.

The above-mentioned base material is not limited, and metals such as iron, aluminum, copper and alloys thereof; polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer resin, polyamide resin, acrylic resin , Vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin, etc. and various FRs
A material obtained by conducting a conductive treatment on a plastic material such as P may be used. In the coating film forming method of the present invention, the coated material obtained by the coating film forming method of the present invention on the base material is, in the case of an automobile body and parts, subjected to a degreasing treatment or a chemical conversion treatment on the base material to be coated in advance. Then, it is preferable that an electrodeposition coating film is formed by a cationic electrodeposition coating as an undercoating film, baked and cured, and an intermediate coating film is formed thereon by the aqueous coating composition.

In the method of forming a coating film of the present invention, a solid top coating film, or a top coating base coating film and a top clear top coating film are formed on the above-mentioned intermediate coating film.

As the electrodeposition paint used for forming the electrodeposition coating film, a cationic electrodeposition paint or an anion electrodeposition paint can be used. From the viewpoint of corrosion resistance, it is preferable to use a cationic electrodeposition paint. As the cationic electrodeposition paint, a modified epoxy resin into which an amino group has been introduced and a blocked isocyanate-curable amino-modified epoxy resin-based cationic electrodeposition paint using a blocked polyisocyanate curing agent are used.

The electrodeposition conditions for forming the electrodeposited coating film are 200
Energize at ~ 300V for 90 ~ 300 seconds, dry film thickness 10 ~ 3
It is preferable to set the thickness to 0 μm.

Next, an aqueous intermediate coating film is formed using the aqueous coating composition. The formation of the aqueous intermediate coating film,
Spray coating and roll coating are performed, and the formed aqueous intermediate coating film is 120 to 18 when baking and drying is performed.
Bake and dry at 0 ° C. for 20 to 30 minutes.

The dry thickness of the aqueous intermediate coating film is 5 to 1
00 μm is preferred. If it is less than 5 μm, the coating properties such as chipping resistance and abrasiveness cannot be sufficiently exhibited, and if it exceeds 100 μm, the appearance of the coating film may be insufficient. More preferably, it is 10 to 80 μm.

Next, on the aqueous intermediate coating film,
A top coat is formed using a top coat. As the top coat, a top coat solid paint containing a color pigment,
Alternatively, an overcoat base paint containing a brilliant pigment and / or a color pigment and an overcoat top clear paint having transparency formed on a coating film formed by the overcoat base paint are used.

The above top coating composition is composed of a resin for forming a coating film as a vehicle, and a crosslinking agent, a pigment, an additive, and a solvent, which are optionally blended.

Examples of the resin for forming a coating film constituting the vehicle include an acrylic resin, a polyester resin, an alkyd resin, a fluororesin, an epoxy resin, a polyurethane resin, and a polyether resin. More than one species can be used in combination.
In particular, acrylic resins and polyester resins are preferably used. As the cross-linking agent, those used in the aqueous coating composition can be the above-mentioned amino resin or blocked polyisocyanate compound. As the pigment, the additive and the solvent, those used in the aqueous coating composition can be used.

As the top clear top coating, a coating containing a carboxyl group-containing polymer and an epoxy group-containing polymer described in Japanese Patent Publication No. Hei 8-19315 contains a pigment in order to prevent acid rain and wet-on-wet. It is preferably used from the viewpoint of not disturbing the orientation of the glittering pigment when applied to the overcoating base coating film.

A powder coating can be used as the top clear coating. As the powder coating,
Thermoplastic powder coatings and thermosetting powder coatings can be used, but thermosetting powder coatings are preferred from the viewpoint of coating film properties. Examples of the thermosetting powder coating include an epoxy powder coating, an acrylic powder coating, and a polyester powder coating, and an acrylic powder coating having good weather resistance is preferable. As the functional group monomer of the acrylic resin used in the acrylic powder coating, a vinyl monomer having a glycidyl group, a hydroxyl group, and a carboxyl group can be used. For example, there are glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, acrylic acid, methacrylic acid, and the like.

Examples of the crosslinking agent used in the powder coating include polycarboxylic acids, phenols, amines, blocked isocyanates, uretdione group-containing blocked isocyanates,
There are alkoxyalkyl glycols, epoxy compounds, hydroxyalkylamide compounds and the like. Preferably,
From the viewpoint of weather resistance, an epoxy-containing acrylic resin using a polycarboxylic acid as a crosslinking agent is preferable.

The above-mentioned overcoat film is formed by spray coating or roll coating for liquid paints, and electrostatic spray coating for powder paints. Bake and dry at 180 ° C. for 20 to 30 minutes.

The dry film thickness of the above top-coat solid coating film is 2
0-100 μm is preferred. The dry film thickness of the above-mentioned base coat is preferably 10 to 100 μm. The dry film thickness of the top clear coating film is preferably 20 to 100 μm. If the lower limit is less than 10 or 20 μm, it is difficult to conceal the base, and if it is more than 100 μm, the coating film may have poor appearance.

Coated product The coated product of the present invention is obtained by the above-mentioned coating film forming method, and comprises a polyester resin, a crosslinking agent, (a) a core-shell type emulsion having a core having a glass transition temperature of 90 ° C. or more, and And / or (b) the presence of the crosslinkable resin particles makes it possible to obtain a coating film having a good balance between chipping resistance and abrasiveness of the formed coating film.

[0073]

EXAMPLES Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the compounding amount represents a mass part unless there is particular notice. The names of raw materials, paints, and equipment represent trade names unless otherwise specified.

Examples 1 to 21 and Comparative Examples 1 to 7 Production Example 1: (a) A core shell having a core Tg of 90 ° C. or higher.
After preparing 651 parts of ion-exchanged water in a 2 L separable flask equipped with a stirrer, a reflux condenser, a dropping funnel, a nitrogen inlet tube, and a temperature sensor, while blowing nitrogen gas,
Under stirring, the temperature was raised to 70 ° C. Next, 300 parts of methyl methacrylate, 194 parts of styrene, 6 parts of methacrylic acid (calculated Tg of a core obtained from the above monomers: 104 ° C.), a 15% aqueous solution of polyoxyethylene were prepared from the dropping funnel. 33 parts of ammonium nonylphenyl ether sulfate (“HITENOL N-08”; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 40 parts of polyoxyethylene nonylphenyl ether (“Nonipol 200”; manufactured by Sanyo Chemical Co., Ltd.) in 25% aqueous solution and deionized A pre-emulsion (A) consisting of 102 parts of water was dropped over 1 hour and 30 minutes as a first-stage monomer component. At this time, 30 parts of a 5% aqueous solution of ammonium persulfate was simultaneously added dropwise over 1 hour and 30 minutes.

After completion of the dropwise addition, the mixture was aged for 40 minutes, and subsequently, 2-ethylhexyl acrylate 11
6 parts, methyl methacrylate 206 parts, styrene 150
Parts, acrylic acid 28 parts (Tg of shell obtained from the above monomer: 40 ° C.), 15% aqueous solution of Hytenol N-
08, 33 parts, 25% aqueous nonipol 200, 40 parts
And a pre-emulsion (B) composed of 102 parts of deionized water was dropped over 1 hour and 30 minutes as a monomer component in the final stage. At this time, 30 parts of a 5% aqueous solution of ammonium persulfate was simultaneously added dropwise over 1 hour and 30 minutes. After completion of dropping, aging was performed for 1 hour. Cool, 25
% Ammonia water was added for neutralization,
A shell emulsion was obtained. This core-shell type emulsion has a core Tg of 104 ° C. and a shell Tg of 4 ° C.
0 ° C., nonvolatile content 49.2%, pH 6.0, viscosity 550 m
Pa · s (using a B-type viscometer, rotor No. 2, 30
Times / minute, measured at 25 ° C .; the same applies hereinafter), average particle diameter 140
nm (measured by a light-scattering particle size analyzer; the same applies hereinafter).

Production Example 2: Production Example of Crosslinkable Resin Particles (b) 651 parts of ion-exchanged water was charged into a 2 L separable flask equipped with a stirrer, a reflux condenser, a dropping funnel, a nitrogen inlet tube, and a temperature sensor. After that, while blowing nitrogen gas,
Under stirring, the temperature was raised to 70 ° C. Then, hydroxyethyl acrylate 25 prepared in advance was dropped from the dropping funnel.
Parts, styrene 100 parts, ethylene glycol dimethacrylate 5 parts, methyl methacrylate 200 parts, methacrylate 2 parts, ethylhexyl methacrylate 168
Part of a 15% aqueous solution of ammonium polyoxyethylene nonylphenyl ether sulfate (“HYTENOL N-0
8 "; Daiichi Kogyo Seiyaku Co., Ltd.), 33 parts of a 25% aqueous solution of polyoxyethylene nonylphenyl ether (" Nonipol 200 "; manufactured by Sanyo Chemical Co., Ltd.) and 40 parts of pre-emulsion (C) consisting of 102 parts of deionized water. It was added dropwise over 1 hour and 30 minutes as the first-stage monomer component. At this time,
At the same time, 30 parts of a 5% aqueous solution of ammonium persulfate was added dropwise over 1 hour and 30 minutes.

After completion of the dropwise addition, the mixture was aged for 40 minutes, and subsequently, 2-ethylhexyl acrylate 11
6 parts, methyl methacrylate 206 parts, styrene 150
Parts, acrylic acid 28 parts (Tg of shell obtained from the above monomer: 40 ° C.), 15% aqueous solution of Hytenol N-
08, 33 parts, 25% aqueous nonipol 200, 40 parts
And a pre-emulsion (D) consisting of 102 parts of deionized water was dropped over 1 hour and 30 minutes as a monomer component in the final stage. At this time, 30 parts of a 5% aqueous solution of ammonium persulfate was simultaneously added dropwise over 1 hour and 30 minutes. After completion of dropping, aging was performed for 1 hour. Cool, 25
% Ammonia water was added for neutralization,
A shell emulsion was obtained. This core-shell emulsion has a shell Tg of 40 ° C. and a non-volatile content of 49.2.
%, PH 6.0, viscosity 550 mPa · s (measured with a B-type viscometer), and average particle size 140 nm (measured with a light scattering type particle size measuring device).

Preparation of Aqueous Coating Composition A melamine resin (Cymel 325, Mitsui, Mitsui) was stirred while stirring 60 parts of a polyester resin in which titanium dioxide was dispersed so as to be 40% by PWC after preparation at 500 rpm with water. In the examples, (a) the core-shell type emulsion prepared above and / or the (b) crosslinkable resin particles described above were added in combination with the combination shown in Table 1 and the amount added. 0.2 parts of dispersant and butyl cellosolve 10 as a cosolvent
And an aqueous coating composition was prepared. The comparative example is
(A) A core-shell type emulsion and (b) those not blended with crosslinkable resin particles were used.

Preparation of Substrate A dull steel plate (300 mm in length, 100 mm in width and 0.8 mm in thickness) was degreased and then subjected to a chemical conversion treatment using a zinc phosphate treating agent (“Surfdine SD2000”, manufactured by Nippon Paint Co., Ltd.). After that, cationic electrodeposition paint ("Power Top U-5
0 ", manufactured by Nippon Paint Co., Ltd.) was electrodeposited so that the dry film thickness was 25 μm. Then, it was baked at 160 ° C. for 30 minutes. Next, the aqueous coating composition prepared above was applied by air spray coating so that the dry film thickness became 40 μm, and baked at 140 ° C. for 30 minutes to form an intermediate coating film layer. Subsequently, the following top coating solid coating, top coating base coating, and top coating clear coating were formed by air spray coating in the steps shown in Table 1 to form a multilayer coating film. The abrasiveness was evaluated by the intermediate coating film, and the chipping resistance was evaluated by the multilayer coating film.

Topcoat paint 1: Organic solvent type acrylic / melamine resin-based topcoat solid paint (“Super Nicks”).
White ”, dry film thickness 40 μm, Nippon Paint Co., Ltd.) Topcoat 2: organic solvent type acrylic / melamine resin-based topcoat metallic paint (“ Super Luck M-95 Silver Metallic ”, dry film thickness 15 μm, Nippon Paint Co., Ltd.), Topcoat 3: Water-based acrylic / melamine resin topcoat metallic paint (“Super Nicks M-300 Silver Metallic”, dry film thickness 15 μm, manufactured by Nippon Paint Co., Ltd.) Topcoat paint 4: Acrylic / melamine resin topcoat clear paint (“Super Rack O-130 Clear ", dry film thickness 35 μm, manufactured by Nippon Paint Co., Ltd., Topcoat 5: Topcoat clear containing a carboxyl group-containing polymer and an epoxy group-containing polymer (" Macflow O-590 Clear ", dried Thickness 35
μm, Nippon Paint Co., Ltd.), Topcoat 6: epoxy-modified acrylic resin / polycarboxylic acid-based powder coating, topcoat clear paint (“Powax A Clear”, dry film thickness 60 μm, Nippon Paint Co., Ltd.).

Evaluation Method Abrasiveness: The cured aqueous intermediate coating film was polished with a # 600 wet paper, and the entanglement of the polishing powder of the intermediate coating film on the polishing paper was evaluated. 4: No entanglement of the abrasive powder of the intermediate coating film. 3: Slight entanglement of the abrasive powder of the intermediate coating film. 2: Entanglement of polishing powder of the intermediate coating film. 1: There is remarkable entanglement of the abrasive powder of the intermediate coating film.

Chipping resistance: A test was carried out using a Gravelo tester (manufactured by Suga Test Instruments Co., Ltd.) under the following conditions, and evaluated visually. Stone size: No. 7 crushed stone (according to JIS-A-5001) Amount of stone: 50 g Distance: 35 cm Air pressure: 4.0 kg / cm ² Angle: 45 ° Test temperature: -20 ° C 5 ... Excellent (no peeling at all) Absent). 4: Good (slight peeling is observed). 3: Normal (peeling less than 1 mmφ is scattered). 2 ... Slightly inferior (peeling is noticeable). 1: Inferior (peeling is noticeable).

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[Table 1]

As is evident from the results in Table 1, Examples 1 to 21 are coatings obtained by the method of forming a coating film using the aqueous coating composition of the present invention, and the balance between the abrasiveness and the chipping resistance. A peeled coating film was obtained. On the other hand, in Comparative Examples 1 to 7, it was not possible to balance the abrasiveness and the chipping resistance.

[0085]

According to the present invention, a polyester resin,
By forming an intermediate coating film with a crosslinking agent, (a) a core-shell type emulsion having a glass transition temperature of a core portion of 90 ° C. or more and / or (b) an aqueous coating composition containing crosslinkable resin particles, The chipping resistance can be obtained by the impact absorption of the impacting object to the coating film, and the coating film has good abrasiveness, and obtains a coating film that balances conflicting chipping resistance and coating abrasiveness. be able to.

The coating film obtained by the present invention has a good balance between the above-mentioned good chipping resistance and abrasiveness.
It is preferably used in fields such as vehicle skins, parts such as automobiles and motorcycles, parts, coil coating, and the home appliance industry.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C09D 175/04 C09D 175/04 201/00 201/00 F term (reference) 4D075 AE03 CA02 CA04 DA06 DB02 DB06 DB07 DB36 DB38 DB40 DB43 DB47 DB48 DB50 DB53 DB61 DC12 DC13 EA06 EA13 EA43 EB12 EB13 EB14 EB15 EB17 EB19 EB20 EB22 EB32 EB33 EB35 EB37 EB38 EB45 EB53 EB56 EC07 4J038 CG142 DA132 DA162 DA172 DA03 GA0311 MA13 MA14 NA01 NA11 NA12 PA04 PA19 PB07 PB09 PC02 PC08

Claims (7)

[Claims] 1. An aqueous coating composition comprising a polyester resin, a crosslinking agent, (a) a core-shell type emulsion having a glass transition temperature of 90 ° C. or more in a core portion and / or (b) crosslinkable resin particles. 2. The glass transition temperature of the core-shell emulsion of (a) the core-shell emulsion of 100 to 150 ° C. and / or (b) the shell transition of the cross-linkable resin particles. Is -20 to + 45 ° C
The aqueous coating composition according to claim 1, which is: 3. Component (a) is added in an amount of 5 parts by weight based on 100 parts by weight of the total solid content of the polyester resin and the crosslinking agent.
50 parts by mass of solid content and / or 5 parts of component (b)
The aqueous coating composition according to claim 1, wherein the aqueous coating composition contains from 50 to 50 parts by mass of a solid content. 4. The mixing ratio by mass of the solid content between the component (a) and the component (b) is (a) / (b) = 10/90 to 50 /.
The water-based coating composition according to any one of claims 1 to 3, wherein the number is 50. 5. The aqueous coating composition according to claim 1, wherein the crosslinking agent is an amino resin and / or a blocked polyisocyanate compound. 6. The method according to claim 1, wherein the base material on which the undercoating film is formed is provided on the base material.
A method for forming a coating film, comprising forming an intermediate coating film using the aqueous coating composition according to any one of Items 1 to 5, and then forming a topcoat film using the topcoat paint. 7. A coated article coated by the coating film forming method according to claim 6.