JPS63170475A - Clear coating composition for topcoating - Google Patents

Abstract

PURPOSE:To obtain the titled two-coat metallic paint composition having excellent sparkle and weather resistance, etc., by compounding an amino resin, a resin containing isocyanate group and an acrylic resin produced by the copolymerization of a specific monomer and a monomer having double bond. CONSTITUTION:The objective composition can be produced by compounding (A) an acrylic resin produced by copolymerizing (i) 20-60pts.wt. of a monomer of formula I and/or formula II (R is H or methyl) and (ii) 80-40pts.wt. of a monomer having double bond (e.g. butyl methacrylate) with (B) an amino resin or (C) a resin containing isocyanate group. The ratio of the component A to the component B or C is preferably 80:20-65:35.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a top coat clear paint composition for a two-coat type metallic paint.

(Prior art) In general, two-coat metallic paints are applied by applying a base coat consisting of resin, aluminum pigment, and colored pigment, and then applying a transparent top coat clear paint either as is or after drying and baking. It is.

Conventionally used top coat clear paint compositions include, for example, alkylated acrylates and alkylated methacrylates such as methyl, ethyl, butyl, and octyl, acrylic acid, methacrylic acid, and derivatives thereof having functional groups, acrylonitrile, acrylamide,
Monomers containing double bonds, such as styrene, are mixed with monomers such as amino resins or isocyanate group-containing resins.
(See No. 1).

(Problem to be Solved by the Invention) However, with the conventional top coat clear paint having the above-mentioned composition, when the particle size of the aluminum pigment in the base coat is increased in order to increase the metallic shine, the image clarity is not sufficient. There is a problem. Another problem was that the color saturation was lost depending on the viewing angle.

(Means for Solving the Problems) The present inventor has focused on these conventional problems and, as a result of intensive research, has developed a method that increases the refractive index of the top coat clear paint to a predetermined value or higher, and uses a specific composition. I found that this solved the problem. If the refractive index of the top coat clear is simply increased, it would be possible to use a resin obtained by copolymerizing the top coat clear as a component of the top coat clear, but these paints have a long-term natural background. or yellowing due to weathering tests.
Problems such as cracking and peeling may occur. Therefore, in this invention, 20 to 60 parts by weight of a monomer represented by the general formula (1) and/or (2): (wherein R represents a hydrogen atom or a methyl group, and each R may be the same or different) Monomer with double bond 80~
The above-mentioned problems have been solved by creating a top coat clear composition in which an amino resin or an isocyanate group-containing resin is blended with an acrylic resin obtained by copolymerizing 40 parts by weight of acrylic resin.

Examples of monomers of the above general formulas (1) and (H) include cyclohexyl methacrylate and vinylcyclohexane, and examples of copolymerizable monomers with double bonds include methyl, ethyl, butyl, and octyl. Alkylated acrylates and alkylated methacrylates and acrylic acid, methacrylic acid with functional groups, such as
Hydroxyl methacrylate, glycidyl methacrylate, styrene, acrylonitrile, acrylamide and the like can be mentioned.

The acrylic resin in this invention is the above-mentioned
Or 20 to 60 parts by weight of the monomer (for 100 parts by weight of the acrylic resin after copolymerization) and 80 to 40 parts by weight of the above-mentioned copolymerizable monomer (10 parts by weight of the acrylic resin after copolymerization).
It can be easily obtained by copolymerizing in a conventional manner at a ratio of 0 parts by weight, for example, by an ester reaction of acrylic acid or methacrylic acid with an alcohol. in this case,
As a polymerization initiator, for example, benzoyl peroxide,
Appropriate amounts of p-tert-butyl perbenzoate, cumene hydroperoxide, etc. can be used. Formula I above
If the monomer represented by If the amount exceeds parts by weight, it becomes difficult to obtain smoothness.

The thus obtained acrylic resin and amino resin or isocyanate group-containing resin (for example, the product name [Sumidur N
-75J Sumitomo Bayer Urethane ■) and 80:2
The top coat clear paint composition of the present invention can be obtained by blending in a ratio (solid content weight ratio) of 0 to 65:35. Mixing ratios (pinholes) of the amino resin or isocyanate group-containing resin to be mixed may occur, and smoothness may be difficult to obtain.

In addition, in this invention, even if other acrylic resins are mixed so that the monomer represented by the above formula (1) and/or (2) is in a proportion of 20 to 60 parts by weight out of 100 parts by weight of the acrylic resin solid content, this The purpose of the invention can be achieved.

(Effect of the invention) As explained above, according to this invention, shine (
It is possible to obtain a top coat clear paint composition that has excellent metallic appearance), less decrease in brightness and brightness depending on the viewing direction, and excellent weather resistance (gloss retention).

(Examples 1 to 3) and (Comparative Examples 1 to 6) 1) First,
Various acrylic resins A used for top coat clear paint
-G and amino resins were prepared as follows: Aku 4' 8-person reflux, thermometer, addition funnel, and a heating device.
! 400 parts by weight of xylene and 1 part of butyl acetate in a flask
00 parts by weight was added thereto, and while heating to about 140°C, 505 parts by weight of a mixture of the monomers and polymerization initiator shown in Table 18 were added dropwise over 2 hours, and then kept at 145°C for about 2 hours. , a resin mixture with a heating residue of 50.1% was obtained.

100 parts by weight of xylene, 300 parts by weight of Solgesso 1tloOJ (manufactured by Esso Chemical Co., Ltd.) and 100 parts by weight of n-butyl alcohol were placed in the above flask and heated to about 140°C.
The monomers and polymerization initiators shown in Tables IB to G were mixed and added dropwise to the 505 heavy-duty apparatus for 1.5 hours while heating at 145°C for about 2 hours. Resins B to G as heating residues were obtained.

In a 1" flask equipped with a refluxer, thermometer, fractionator and heating device, 222 parts by weight of n-butyl alcohol and 25 parts by weight of melamine were added.
2 parts by weight and 300 parts by weight of a formaldehyde n-butyl alcohol solution (formaldehyde: 40, n-butyl alcohol: 50, water: 10 (weight ratio)),
Approximately 2 hours 100-. The mixture was heated to 105° C., condensed water was removed, and then the pressure was reduced using a vacuum pump, and 220 parts by weight of xylene was added thereto to obtain an amino resin with a heating residue of 59%.

Top Coat Clear゛° S Rules The above amino resin or isocyanate group-containing resin (trade name: Sumidur N75J (manufactured by Sumitomo Bayer Urethane)) shown in Table 2 is added to various acrylic resins A-G having the compositions shown in Table 1 above. After mixing in the following proportions, the mixed solvent (product name [Solhesso IIklloOJ (Esso Chemical)
(manufactured by)/trade name [Tsurupez l1h150 J (manufactured by Esoso Kagaku ■)/n-butanol-40150/10 (weight ratio)] was added, mixed uniformly, and the viscosity was adjusted at 20°C for 25 seconds using a Ford cup floor 4. Topcoat clear paint compositions I to II (Examples 1 to 3) of the present invention and comparative compositions I to II for comparison purposes were obtained. Test pieces were prepared by coating the various coating compositions thus obtained by the method described below, and performance tests were conducted. The results of these tests are shown in Table 3. From this table, it can be seen that the clear coating composition of the present invention has excellent shine, weather resistance, etc.

In addition, the shine (metallic appearance) was measured for the top coat clear paint composition ■ of Example 2 and the comparative composition ■ of Comparative Example 6, and the results of these measurements are shown in Figure 1 (composition ■) and Figure 2 ( Composition (■) is shown. Comparing these results, it can be seen that the composition of the present invention has excellent shine.

[Preparation of test piece]

0, 8m+s (thickness) x 75mm (41)
x 150m+m (length) cold-rolled steel plate was degreased, subjected to zinc phosphate chemical conversion treatment, coated with cationic electrodeposition paint (approximately 20μ), baked at 170°C for 30 minutes, and coated with alkyd-melamine intermediate coating. Painted (approximately 35μ) and heated at 140℃ x 3
Bake for 0 minutes and apply base coat enamel (approximately 20μ)
Various top coat clear paint compositions I~ shown in Table 2
Paint (approximately 30μ) each of ■, and clear paint composition ■
For other cases, bake at 140°C for 30 minutes, and for clear paint composition (3), bake at 90°C for 30 minutes, and after 24 hours,
I wanted to use it for various tests, so I painted it with air spray after the intermediate coating).

In this case, the above base coat enamel is made of 8 rounds of Nialuminum pigment (trade name "High Sparkle", Toyo Aluminum) as follows.
10 parts by weight of butyl acetate (65% by weight)
2 parts by weight were added and uniformly dispersed, and 48.9 parts by weight of acrylic resin A shown in Table 1 and the above amino resin 6.
Add 2 parts by weight, mix uniformly, add a pre-prepared mixed solvent (xylene/butyl acetate/2-ethoxyethyl acetate = 40/40/20 (weight ratio)), and add Ford Cup N114. The viscosity was adjusted at 20° C. for about 14 seconds.

〔performance test〕

l]31: Measured with a PGD meter (manufactured by Murakami Color Research Institute) (results are shown as PGD values).

Hardness: The degree of scratches on the painted surface with a marking pencil is expressed by the hardness of the pencil lead (JIS 56006-78 (pencil)).

fl Uni Fluorescent Ultraviolet Condensation Test (ASTM G-53
-77) accelerated test UV irradiation at 80°C for 8 hours - dew condensation at 50°C for 4 hours was repeated. Tested for a total of 2000 hours. Visual appearance and gloss by specular reflectance (JIS K5400) are measured.

Reverse cry: Measured using a variable angle colorimeter (VC-1, Suga Test Instruments (manufactured by Kiki). A schematic diagram of this variable angle colorimeter is shown in Figure 3. A light source is placed directly above the test piece 1. Irradiate the light of 2, test piece 1
The L1 value (brightness) of the reflected light is measured by the light receiver 3 at the positions of θ-10'' and 80''.

Folding" - ← L evening" - M2J Lee: Measured with a microscopic gloss meter. A schematic diagram of the gloss meter is shown in fourth.

While running the test piece 1, light from a light source 2 is irradiated onto the test piece 1, and the intensity of the reflected light is measured by a light receiver 3. The metallic effect (the degree of sparkle of the aluminum pigment) is measured by the intensity of reflected light.

[Brief explanation of the drawing]

Figure 1 is a curve diagram showing the results of measuring the brightness (metallic feel) of the top coat clear paint composition of Example 2, Figure 2 is a curve diagram showing the results of measuring the brightness of the comparative top coat clear paint composition of Comparative Example 6 Figure 3 is an explanatory diagram showing the outline of the variable angle colorimeter used to measure color tone, Figure 4 is an outline diagram of the microscopic gloss meter used to measure shine. FIG. 1...Test piece 2...Light source 3...Receiver Patent applicant Nissan Motor Co., Ltd. Representative Patent Attorney Hidetoshi Sugimura Patent Attorney Oki Sugimura
Made by. Figure 1 Figure 2 Figure 3 - Figure 4 Travel distance

Claims (1)

[Claims] 1. General formula I and/or II; ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) (Formula (wherein, R represents a hydrogen atom or a methyl group, and each R may be the same or different) and 80 to 60 parts by weight of a monomer having a double bond.
A top coat clear paint composition comprising an acrylic resin obtained by copolymerizing 40 parts by weight with an amino resin or an isocyanate group-containing resin.