JP3035683B2 - Top coating for automotive plastic parts and coating method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a motor vehicle plastic parts
The present invention relates to a material top coat and a coating method using the same .

[0002]

2. Description of the Related Art In recent years, with the objectives of reducing the weight of an automobile body, improving design and improving productivity, in recent years,
Some of the outer plate members are being replaced by plastic from metal.

[0003] Such a plastic member is generally applied to a structural member such as a fender or a door panel using hard plastic such as SMC or a polymer alloy, a spoiler, or the like, after coating with a primer, in the same manner as for a metal member. A hard coating forming top coat is applied. On the other hand, members made of a soft plastic (for example, RIM urethane or polypropylene), which is required to have impact resistance and bending resistance, such as bumpers and fesia, are coated with a softer material than the above-mentioned metal material topcoat after primer coating. A top coat that forms a film is applied.

[0004] A problem here is the stain resistance of a plastic member coated with a top coat which forms a soft coating film. That is, since the coating film made of the above-mentioned top coating for metal members is relatively hard, contamination resistance is not a major problem at present. Soot and dust easily adhere to it, which may cause black stains on the painted surface, and yellow stains are likely to occur in ash fall areas such as volcanic ash, all of which significantly reduce the appearance of the coating film Therefore, the improvement is strongly demanded. This phenomenon is particularly remarkable in a light-colored finish coating film.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a coating material suitable for coating a plastic member for automobiles, particularly a soft plastic, which can improve pollution resistance without deteriorating impact resistance and bending resistance. About the development of.

That is, the present invention provides a compound represented by the following general formula (I):

Embedded image [Where A is

Embedded image R ₁ represents a hydrogen atom or a methyl group, and R ₂ has 1 to 1 carbon atoms.
6 is a divalent aliphatic saturated hydrocarbon group, R ₃ and R ₄ are the same or different and each is a phenyl group, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and R ₅ is 1
And 10 to 10 alkyl groups are shown. n is 1 to 100
Indicates an integer. 5 to 40% by weight of the alkoxysilane group-containing vinyl monomer (A-1), 5 to 50% by weight of the hydroxyl group-containing vinyl monomer (A-2), and other copolymerizable vinyl An acrylic polymer (A) obtained by polymerizing a monomer component consisting of 10 to 90% by weight of the monomer (A-3) and hexamethoxymethylmelamine and / or a part or all of the methoxy group thereof is C ₄ A crosslinked cured coating film comprising, as a main component, an etherified melamine resin (B) substituted with the above alcohol and, if necessary, an acid neutralized with an amine compound as a curing catalyst (C). However, (a) TUKON hardness (Knoop Har
(b) a glass transition temperature of 50 to 90 ° C. and (c) a molecular weight between crosslinks of 500 or less. Top coating for components and

[0007]: The top coating described above, according to the coating method, which comprises using as a topcoat to the plastic member for an automobile exterior.

[0008] Each component constituting the coating material for automobile plastic parts of the present invention (hereinafter, may be abbreviated as "the present coating material") will be described.

Component (A): General formula (I)

Embedded image [Where A is

Embedded image R ₁ represents a hydrogen atom or a methyl group, and R ₂ has 1 to 1 carbon atoms.
6 is a divalent aliphatic saturated hydrocarbon group, R ₃ and R ₄ are the same or different and each is a phenyl group, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and R ₅ is 1
And 10 to 10 alkyl groups, respectively. n shows the integer of 1-100. 5 to 40% by weight of the alkoxysilane group-containing vinyl monomer (A-1), 5 to 50% by weight of the hydroxyl group-containing vinyl monomer (A-2), and other copolymerizable vinyl An acrylic polymer obtained by polymerizing a monomer component comprising 10 to 90% by weight of the monomer (A-3).

First, as the component (A-1), for example,
Acryloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltri-n-butoxysilane, acryloxypropylmethyldimethoxysilane, methacryloxypropylmethyldimethoxysilane, methacryloxypropylmethyldi-n-butoxysilane, etc. It is mentioned as a suitable thing.

The component (A-2) is a hydroxyl-containing vinyl monomer such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl (meth) acrylate, butanediol monoacrylate,
"Placcel FM-1", "Placcel FM-2",
"Placcel FM-3", "Placcel FA-1",
"Placcel FA-2" and "Placcel FA-3" (both manufactured by Daicel Chemical Industries, Ltd., trade names, 2-hydroxyethyl caprolactone-modified (meth) acrylates) and the like can be mentioned.

The component (A-3) is a vinyl monomer copolymerizable with the components (A-1) and (A-2), and includes, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, Acrylics such as ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate Esters of an acid or methacrylic acid with a monohydric alcohol having 1 to 22 carbon atoms; carboxyl group-containing vinyl monomers such as acrylic acid, methacrylic acid and maleic anhydride; glycidyl group-containing vinyl monomers such as glycidyl acrylate and glycidyl methacrylate;
Amide vinyl monomers such as acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide; amine vinyl monomers such as dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, tert-butylaminoethyl methacrylate; styrene, vinyl Toluene, acrylonitrile, methacrylonitrile, α-methylstyrene,
Compounds having one polymerizable unsaturated bond in one molecule such as other vinyl monomers such as vinyl acetate.

The components (A) (A-1) to (A-
3) The proportions of the components are based on their total weight,
The component (A-1) is 5 to 40% by weight, preferably 5 to 30% by weight.
If the content is less than 5% by weight, the stainability is reduced, and
If it is more than 10% by weight, the storage stability of the paint will be poor. Also,
The component (A-2) is 5 to 50% by weight, preferably 10 to 4% by weight.
When the content is 0% by weight or less than 5% by weight, the reaction between the amino resin and the alkoxysilane group and the hydroxyl group does not proceed sufficiently, and the curability and stainability are reduced. When the content is more than 50% by weight, the water resistance is impaired. .

The copolymerization reaction of the components (A-1) to (A-3) can be carried out in the same manner as in a conventional method for synthesizing an acrylic resin or a vinyl resin, for example, by dissolving the components in an organic solvent. Alternatively, it can be carried out by dispersing and heating with stirring at a temperature of about 60 to 180 ° C. in the presence of a radical polymerization initiator. The reaction time is usually 1
It may be about 10 hours. The number average molecular weight of the component (A) is generally about 3,000 to 500,000, preferably 5,000 to 100,000.

Component B: Amino resin Known partial or fully methylolated amino resins obtained by reacting an amino component such as melamine, urea, benzoguanamine, acetoguanamine, steloguanamine, spiroguanamine, dicyandiamide and an aldehyde with an aldehyde. Aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. In addition, 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, and isobutyl alcohol. Alcohol, 2-ethylbutanol, 2-ethylhexanol and the like can be mentioned. In this coating, it is preferable to use etherified etherified melamine resins, especially some or all of hexamethoxymethylmelamine and its methoxy group at C ₄ or higher alcohols.

In the present invention, the component (B) is a trade name such as Cymel 303 (a full methoxylated melamine resin, manufactured by Mitsui Cyanamid), Uban 20SE-60 (a butylated melamine resin, manufactured by Mitsui Toatsu). A commercially available amino resin can be used.

The present coating composition contains the above components (A) and (B) as main components, and the mixing ratio of the two components can be arbitrarily selected according to the purpose. (A) component is 50 to 95% by weight, preferably 55
To 90% by weight, more preferably 60 to 80% by weight,
The component (B) is 5 to 50% by weight, preferably 10 to 45% by weight, and more preferably about 20 to 40% by weight.
If the component (B) is less than 5% by weight, water resistance and weather resistance may be more than 50% by weight, and mechanical properties and interlayer adhesion during recoating may be reduced. The paint may further include, if necessary, an alkoxysilane group-curing catalyst (C).
It is preferable to use As the component (C), for example, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, trichloroacetic acid, phosphoric acid, mono-n-propyl phosphoric acid, monoisopropyl phosphoric acid, mono-n-butyl phosphoric acid, mono-isobutyl phosphoric acid, mono-tert-phosphate -Butyl phosphoric acid, monooctyl phosphoric acid, monoalkyl phosphoric acid such as monodecyl phosphoric acid,
Di-n-propyl phosphoric acid, diisopropyl phosphoric acid, di-n-
Dialkyl phosphoric acids such as butyl phosphoric acid, diisobutyl phosphoric acid, di-tert-butyl phosphoric acid, dioctyl phosphoric acid, and didecyl phosphoric acid; phosphoric acid esters of β-hydroxyethyl (meth) acrylate; mono-n-propyl phosphorous acid; monoalkyl phosphites such as n-butyl phosphite, monoisobutyl phosphite, mono-tert-butyl phosphite, monooctyl phosphite, and monodecyl phosphite;
n-propyl phosphite, diisopropyl phosphite, di-n-
Examples thereof include acidic compounds such as butyl phosphite, diisobutyl phosphite, di-tert-butyl phosphite, dioctyl phosphite, and dialkyl phosphite such as didecyl phosphite.

Further, tetraisopropyl titanate,
Tin-containing compounds such as tetrabutyl titanate, tin octylate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dimaleate; butylamine, tert-butylamine, dibutylamine, hexylamine, ethylenediamine, triethylamine, isophoronediamine, imidazole And basic compounds such as lithium hydroxide, sodium hydroxide, potassium hydroxide and sodium methylate can also be mentioned as the component (C).

As the component (C), the above acidic compound (particularly, a strongly acidic compound such as paratoluenesulfonic acid and dodecylbenzenesulfonic acid) may be used, for example, triethylamine, diethanolamine, 2-amino-2-methylpropanol and the like. A neutralized (blocked) strong acid catalyst neutralized (blocked) with an amine compound also serves as a curing catalyst for the alkoxysilane group. That is, at a baking temperature of 100 ° C. or more, the neutralized (blocked) strong acid catalyst becomes a common catalyst for the reaction of the resin and the reaction of the alkoxysilane. Further, since the neutralized (blocked) strong acid catalyst does not function as a curing catalyst for alkoxysilane at room temperature, a one-pack type alkoxysilane curing system is also possible.

For the purpose of, for example, achieving high solids and improving the workability of coating, polymer particles can be added to the paint according to need. Such a polymer particle is obtained by using, as a dispersion stabilizer resin, a copolymer obtained by using an alkoxysilane group-containing vinyl monomer represented by the general formula (I) and a hydroxyl group-containing unsaturated monomer as essential monomer components. Non-aqueous polymer particles insoluble in the organic liquid obtained by polymerizing a radical polymerizable unsaturated monomer in an organic liquid in the presence of the resin are preferred.

Further, the coating composition of the present invention uses the above components and has a cured coating film having a TUKON hardness of 4 to 12, preferably 6 to 10, a glass transition temperature of 50 to 90 ° C.
Preferably at a temperature of 60 to 80 ° C and a molecular weight between crosslinks of 500
It is adjusted as follows. In the present invention, the object cannot be achieved if any of these requirements is omitted.

The TUKON hardness of a cured coating film baked under a predetermined heating condition is determined at 20 ° C. by an American Chain & C
Measured by TUKON microhardness tester manufactured by able Company. The higher the value, the harder. In the present invention, if the TUKON hardness is less than 4, the stain resistance is remarkably reduced, and if the TUKON hardness is more than 12, the impact resistance and the bending resistance become insufficient.

The glass transition temperature of the isolated coating film was measured using a vibron dynamic viscoelasticity analyzer DAYNAMIC VISCO ELASTOMETER MODE.
Dynamic glass transition temperature (° C) measured using L VIBRON DDV-IIEA type (TOYO BALDWIN CO.Ltd) at a frequency of 110 Hz and a heating rate of 3 ° C / min. When it is lower, the stain resistance is significantly reduced.

The molecular weight between crosslinks is a theoretically calculated value obtained by applying the value of the glass transition temperature measured above to the following rubber viscoelasticity equation such as Flory. Is not preferred.

Molecular weight between cross-links Mc = 3ρRT / Emin [where R = 8.131 × 10 ⁷ (evg / Kmol), T = temperature (K) at minimum elastic modulus, ρ = density (g) of sample coating film /cm)
In general, 0.5, Emin = minimum modulus at high temperature (dyn
e / cm)

In the present coating composition, for example, the following method is used to adjust the coating film hardness and physical properties of the present coating composition using the above components to the above-mentioned specific ranges.

To adjust the hardness and the glass transition temperature,
In the monomer component (A), a hard component, for example, styrene, methyl methacrylate, isobutyl methacrylate, and the like, and a soft component, for example, n-butyl acrylate, 2-ethylhexyl methacrylate, or ε
A method by changing the compounding ratio with -caprolactone-modified hydroxyethyl methacrylate (for example, "Placel FM-3", trade name, manufactured by Daicel Chemical Industries, Ltd.) is preferable. At this time, the soft component is 2% of the component (A).
It is preferably in the range of 0 to 60% by weight.

The molecular weight between crosslinks of the coating film is adjusted by controlling the alkoxysilane group-containing vinyl monomer (A-1) represented by the general formula (I) and the hydroxyl group-containing vinyl monomer, which are essential monomer components of the component (A). A method by changing the compounding amount and the compounding ratio of the monomer (A-2) is preferable.

The paint of the present invention is obtained by dissolving or dispersing the components (A) and (B) in a conventional organic solvent for paints. If necessary, coloring pigments (eg, titanium oxide, carbon black, phthalocyanine blue, quinacridone red, azo type, quinacridone type, etc.), extender pigments (eg, silica, barita, talc, polymer particles, etc.), metal flakes Pigments (aluminum flakes, nickel flakes, copper flakes, brass flakes, chromium flakes, etc.), mica powder (eg, pearl mica, colored pearl mica, etc.), curing catalyst (C), coating surface adjuster, ultraviolet absorber, cellulose acetate Butyrate, anti-settling agent, anti-sagging agent and the like can be appropriately compounded. Therefore, the present paint can be used as a clear paint, a colored paint, or a metallic paint. These can be used as a top coat for the plastic member, as a base coat for one coat, one bake or two coat finishes, and / or as a top coat (clear).

The coating method of the present coating composition is not particularly limited, and can be carried out by appropriately selecting a conventionally known means. Preferred examples include electrostatic coating (bell type, REA method, etc.) and air spray coating. In these coating methods, it is usually appropriate to dilute the paint to a viscosity of about 12 to 35 seconds (Ford Cup # 4/20 ° C.) before coating. The coating film thickness is
For example, in the case of clear paint, 20 to 80 μm, especially 30 to 5 μm
0μ, 10 to 4 for colored paints (including metallic paints)
0 μm, particularly preferably 10 to 30 μm (all based on the cured coating film). And the curing of the coating film is 60 to 160 ° C.
Or more by heating. Although the coating material of the present invention may be applied directly to a plastic member, it is preferable to previously apply a surface treatment by solvent vapor degreasing, polishing, acid treatment, corona discharge, etc., and further apply a primer or the like.

The paint of the present invention is suitable for painting the surface of a plastic member used for an outer plate of an automobile body. In particular, compared to conventional soft coating film forming paints,
The impact resistance and the bending resistance are equal or higher, and the contamination resistance can be remarkably improved. Therefore, it is preferable to apply the invention to the soft plastic member described above. Soft plastic members, such as bumpers and fesia, have material properties that can withstand shock and deformation due to collisions at low temperatures, and coatings applied to such members do not hinder these material properties. It is required to have flexibility. Specifically, the elongation at -20 ° C is required to be 5% or more, preferably 10% or more. With conventional paints, if the elongation of the coating is at this level, the TUKON hardness will be less than 4.
The molecular weight between crosslinks of the coating film is larger than 500, and the stain resistance is extremely poor. In contrast, the coating of the present invention has a TUKON hardness of 4 to 12, a glass transition temperature of 50 to 90 ° C, and a molecular weight between crosslinks of 50 even though it has the above-mentioned low temperature elongation.
Since it can be easily adjusted to 0 or less, the stain resistance can be remarkably improved without deteriorating impact resistance and bending resistance.

Further, the cured coating film of the present coating material is T
Even if the UKON hardness is adjusted to 4 to 12, preferably 6 to 10 and the elongation is adjusted to 15 to 50%, the elongation at low temperature (about -20 ° C) does not decrease. This is because the coating film of the specific composition of the present invention has a high crosslinking density, the temperature dependency such as hardness and physical properties of the coating film is small, and flexibility at low temperature and room temperature at room temperature, which were difficult in the prior art, This makes it possible to achieve both hardness and physical properties required for stain resistance. In addition, it is needless to say that the present paint can be applied to hard plastic members.

Further, the cured coating film of the present coating material is less susceptible to hydrolysis at the cross-linking points, -Si-O-Si-, -Si-O
Since -R- is introduced, it has extremely excellent surface properties (acid resistance, water repellency, scratch resistance, and chemical resistance), and becomes more excellent in contamination.

Hereinafter, the present invention will be described more specifically with reference to Production Examples, Examples and Comparative Examples.

I Production Example of Component (A) (A-1): 150 g of styrene 200 g of n-butyl acrylate 200 g of 2-ethylhexyl methacrylate 150 g of 150 g of 2-hydroxyethyl acrylate 150 g of Praxel FM-3 (manufactured by Daicel Chemical Industries, Ltd.) Name) 150 g of γ-methacryloxypropyltrimethoxysilane A mixture of 20 g of azobisisobutyronitrile was mixed with 1 g of xylene in the same amount as the mixture.
The solution was added dropwise at 20 ° C. over 3 hours and aged at the same temperature for 2 hours. The number average molecular weight of the obtained transparent polymer determined by GPC was 18,000.

(A-2) to (A-6): Under the same conditions as in the composition shown in Table 1, the acrylic polymer (A-
2) to (A-6) were produced. The number average molecular weight by GPC was 18,000 in all cases.

[0037]

[Table 1]

II Examples (Coatings) (1) Clear Coatings Example 1 (A-1) 140 parts of solution Cymel 303 (Note 1) 30 parts Nacure 5225 (Note 2) 1.5 parts Surface conditioner 0.1 part ( 1.0 part of UV absorber (manufactured by Ciba-Geigy, Tinuvin 900) The above mixture was diluted with Swarsol # 1000 to adjust the viscosity (Ford Cup # 4, 20 ° C.) to 25 seconds. (C
-1). (Note 1) Cymel 303: Fully methoxylated melamine resin manufactured by Mitsui Cyanamid Co., Ltd. (Note 2) Nacure 5225: KING INDUS
TRIES neutralized dimethyl oxazolidine of dodecylbenzenesulfonic acid

Example 2, Comparative Examples 1-4 The solution (A-1) in Example 1 was replaced with (A-2)
It was manufactured in the same manner as in Example 1 except that the same amount was substituted for (A-6). Example 2, Comparative Examples 1-4 and (C-2)-(C
Table 2 shows the relationship with -6).

[0040]

[Table 2]

(2) Solid color paint Example 3 Titanium white JR-701 100 parts (Titanium dioxide manufactured by Teikoku Chemical Co., Ltd.) (A-1) Solution 140 parts Cymer 303 30 parts Nacure 5225 1.5 parts Surface conditioner 0. One part of the mixture was diluted with Swazol # 1000 and adjusted to a viscosity (Ford Cup # 4, 20 ° C) of 25 seconds (S-
1).

Example 4 A solution (A-2) was prepared using the same formulation as in (S-1) except for using the solution (S-2).

Comparative Example 5 Titanium White JR-701 100 parts (A-2) Solution 140 parts 60% Uban 20SE-60 50 parts (Mitsui Toatsu Co., Butylated melamine resin) A mixture of 0.1 part of a surface conditioner Was diluted with Swarsol # 1000 and adjusted to a viscosity of 25 seconds (Ford Cup # 4, 20 ° C.) (S-
3).

III Example (coating method) Example 5 A plastic member (test piece: note below) was treated with a Soflex No. 1200 white (Kansai Paint Co., Ltd., product name,
Melamine curing type solid color paint) with a dry film thickness of 25
After spray coating to a thickness of about 30 μm and setting at room temperature for 10 minutes, the coating is cured by heating at 120 ° C. for 30 minutes. Then, the SOFLEX No. 1400 White Pearl Mica (manufactured by Kansai Paint Co., Ltd., trade name, melamine-curable base coat paint) is spray-coated so that the dry film thickness becomes 15 to 20 μm,
After flashing off for 5 to 10 minutes, the clear coating material (C-1) of Example 1 was spray-coated so as to have a dry film thickness of 35 to 40 μm, set at room temperature for 10 minutes, and then heated at 120 ° C. for 30 minutes. Was performed to form a coating film.

R-RIM (Rei) steam-degreased with trichlorethane
n Forced-Reaction Injecti
On Molding) Urethane plastic is spray-coated with a urethane elastomer resin-based gray paint primer [Kansai Paint Co., Ltd. “Sofflex No. 1000” primer] to a dry film thickness of 15 to 20 μm, and then at 80 ° C. for 30 minutes. It was baked and dried to obtain a test piece.

With respect to the coating film composed of the base coat paint and the clear coat paint described above, under the same conditions, the coating film is formed in a thickness of 0.1 to 1.0.
It was also formed on a 3 m thick tin plate and a 3 mm thick hard polypropylene plate.

The plastic member-coated panel was subjected to a low-temperature bending property and an exposure contamination test. The painted tin plate is TUK
It was used for measurement of ON hardness. The coating film on the polypropylene plate was peeled and cut, and used for measurement of glass transition temperature and molecular weight between crosslinks by vibron.

Example 6 and Comparative Examples 6 to 9 Using the clear coatings (C-2) to (C-6) shown in Table 3, coating films were formed under the same conditions as in Example 5, and were subjected to a test. did.

Example 7 A plastic member (test piece) was spray-coated with a solid color paint (S-1) so as to have a dry film thickness of 35 to 40 μm and set at room temperature for 10 minutes.
Heating was performed at 20 ° C. for 30 minutes to form a coating film. Under the same conditions, a coating film was formed on a tin plate and a hard polypropylene plate, and subjected to a test in the same manner as in Example 5.

Example 8 and Comparative Example 10 Solid color paints (S-2) and (S-3) shown in Table 3
Was used to form a coating film under the same conditions as in Example 7, and used for the test.

Table 3 shows the test results in Examples 5 to 8 and Comparative Examples 6 to 10.

[0052]

[Table 3]

Test Method The TUKON hardness was determined at 20 ° C. for a cured coating film baked under predetermined heating conditions at the American Chain & Cable Company.
Measured by TUKON microhardness tester made by
The higher the value, the harder. It was measured on a tin plate coated.

The glass transition temperature of the isolated coating film was measured using a vibron dynamic viscoelastic apparatus DAYNAMIC VISCO ELASTOMETER MODEL VIB.
The dynamic glass transition temperature (° C.) measured using a RON DDV-IIEA type (TOYO BALDWIN CO. Ltd.) at a frequency of 110 Hz and a heating rate of 3 ° C./min. It was measured on a polypropylene plate.

The molecular weight between crosslinks is a theoretical calculation value obtained by applying the value of the glass transition temperature measured above to the following rubber viscoelasticity formula such as Flory. It was measured on a polypropylene plate. Molecular weight between crosslinks Mc = 3ρRT / Emin [where R =
8.131 × 10 ⁷ (evg / Kmol), T = temperature at minimum elasticity (K), ρ = density of sample coating (g / cm), generally 0.5, Emin = high temperature range Minimum elastic modulus (dyne / cm)]

Low-temperature flexibility: A test plate coated on a plastic member was left in an atmosphere of -20 ° C. for 4 hours, and then bent at 180 ° C. between iron bars having a diameter of 20 mm. The sample having no change or the extent to which minute cracks were generated was evaluated as ○, and the sample with significant cracks was evaluated as ×.

Exposure pollution A: Observation of the painted surface after standing for 6 months with the painted surface horizontal at the point where the test plate painted on the plastic member faces the high traffic road in Hiratsuka city did. In the visual observation, ◎ indicates no abnormality at all, ○ indicates slight stain, △ indicates black or yellow spots dotted and conspicuous, and × indicates the entire surface is covered with black or yellow and the stain is remarkable. S & M Color Computer Model 4 (manufactured by Suga Test Instruments Co., Ltd.)
The values of ΔE for A and the values of Δb for B were described.

Exposure contamination B: In the area of Kagoshima city where volcanic ash fallout was large, the painted surface was observed after standing for 6 months with the painted surface horizontal. The evaluation method is the same as A above.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09D 161/28 C09D 161/28 // C08F 299/08 C08F 299/08 (72) Inventor Masaharu Ishiguro 4-chome Higashiyawata, Hiratsuka-shi, Kanagawa 17-1 Kansai Paint Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 143/04 C09D 161/28 CAPLUS (STN)

Claims (2)

(57) [Claims] 1. A compound of the general formula (I) [In the formula, A is ## STR2 ## R ₁ represents a hydrogen atom or a methyl group, and R ₂ has 1 to 1 carbon atoms.
6 is a divalent aliphatic saturated hydrocarbon group, R ₃ and R ₄ are the same or different and each is a phenyl group, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and R ₅ is 1
And 10 to 10 alkyl groups are shown. n is 1 to 100
Indicates an integer. 5 to 40% by weight of the alkoxysilane group-containing vinyl monomer (A-1), 5 to 50% by weight of the hydroxyl group-containing vinyl monomer (A-2), and other copolymerizable vinyl An acrylic polymer (A) obtained by polymerizing a monomer component comprising 10 to 90% by weight of the monomer (A-3) and hexamethoxymethylmelamine and / or a part or all of the methoxy group thereof is C ₄ The above-mentioned alcohol-substituted etherified melamine resin (B) is used as a main component, and if necessary, an acid neutralized with an amine compound is used as a curing catalyst (C). , (A) TUKON hardness (Knoop Hardn)
(b) a glass transition temperature of 50 to 90 ° C., and (c) a molecular weight between crosslinks of 500 or less. Top coating for components. 2. A coating method, wherein the top coating composition according to claim 1 is used as a top coating on a plastic member for an automobile exterior.