JPH0326110B2 - - Google Patents

Description

[Detailed description of the invention]

OBJECTS OF THE INVENTION The present invention relates to high chroma metallic paint finishes, and its purpose is to expand the range of tones that cannot be obtained using conventional primary colors alone in the finishing of automobiles, motorcycles, etc. BACKGROUND ART Conventionally, automobiles, motorcycles, etc. have been painted with solid color finishes using ordinary organic or inorganic pigments and metallic finishes with paints using aluminum powder or the like. The metallic finish related to the present invention has changed from the original metallic base coating alone to a two-coat, one-bake system that has a clear coating layered on top of the metallic base to prevent discoloration of the metallic base and improve weather resistance. There is. Furthermore, in Japanese Patent Publication No. 59-2542, the first layer is a metallic base, the second layer is a clear coat containing 1 to 10 parts of a coloring pigment and/or extender based on the resin solid content, and the third layer is a clear coat. Discloses a system stacked in layers. Furthermore, JP-A-57-105266 discloses a method in which a two-layer clear coat is laminated on a metallic base coat, the vehicle being an acrylic monomer and a resin having a specified hydroxyl value, acid value, etc. The object of the present invention is to obtain a coating film with a deep color tone, which is difficult to achieve with these conventional metallic finishes. Structure of the Invention That is, the present invention involves applying a first clear paint as a first layer wet-on-wet on a base coat containing a metallic pigment, and then baking it, then applying a second clear paint as a second layer, and then applying a wet coating. It consists of four layers in which a third clear paint is further laminated and baked as a top coat while wet, and the second clear paint contains 0.5 to 10 parts of pigment based on the resin solid content, and the first clear paint and third clear paint 4 characterized in that the resins used are the same or different within the number average molecular weight range.
This is a method for forming a four-layer metallic coating film using two coats and two bakes. When painting an automobile, which is the most preferred object to be coated to which the present invention is applied, the process up to film formation/electrodeposition/intermediate coating of the object to be coated remains the same as in the past. In the method of the present invention, the metallic base is a resin component containing an ordinary acrylic resin as a main component and an amino resin as a crosslinking agent, and is used as a vehicle. The number average molecular weight of the acrylic resin is preferably 20,000 to 50,000. If the number average molecular weight is less than 20,000, it will be difficult for the metallic pigments to be arranged uniformly, and the desired saturation level will not be achieved.If it exceeds 50,000, the leveling of the paint film will be poor, so the finished skin of the paint film will not be smooth. decreases. The metallic pigment blended into this base coat is metal powder and/or foil mica,
It is preferable that 50% by weight or more of the particles have a diameter of 25μ or more. If the metallic pigment is smaller than 25μ,
If the amount of metallic pigment of 25μ or more is less than 50% by weight, it is not preferable in the present invention, which aims at high chroma, because the metallic feel will be reduced in relation to the pigment added to the second layer of the second clear paint. . Examples of such metallic pigments include Miraglow 1000 and Alpaste 52- manufactured by Toyo Aluminum Co., Ltd.
509, Asahi Kasei aluminum paste MG-21,
aluminum powder or paste etc.
Examples of foil mica include Iriodin 140 manufactured by Merck Co., Ltd., which is mica coated with titanium, Shimmer Pearl, and Iriodin 530 manufactured by Merck Co., Ltd., which is processed from these. Next, for the first layer as the first clear coat, a resin consisting of a combination of an acrylic resin and an amino resin as a crosslinking agent thereof, or a combination of an acrylic resin or a polyester resin and an isocyanate as a crosslinking agent thereof is used as a vehicle. The number average molecular weight of acrylic resin is preferably 5000 to 10000, and the number average molecular weight of polyester resin is
2000-4000 is preferred. If the number average molecular weight of the acrylic resin is less than 5000, coating film quality such as weather resistance and coating film hardness will deteriorate.
If it exceeds 10,000, the coating film will become thinner, which is not preferable. If the number average molecular weight of the polyester resin is less than 2000, craters will appear,
If it exceeds 4000, the coating film will become thinner during the drying process, which is not preferable. Next, the second layer as a second clear coat uses an acrylic resin and its crosslinking agent, an amino resin, as a vehicle. The number average molecular weight of this acrylic resin is 10,000~
50000 is preferred. . If the number average molecular weight is less than 10,000, it will be difficult to control the adhesion with the first layer of clear paint, and the paint will tend to mix with the third layer of clear paint, which is laminated wet-on-wet, resulting in poor gloss. If it exceeds 50,000, the smoothness of the coating film will decrease. It is essential that the second clear paint for the second layer contains 0.5 to 10 parts of pigment based on the resin solid content. When this pigment is blended into the first clear paint of the first layer to form a paint film, the clear paint is pierced by the unevenness of the metallic pigment, resulting in a flickering appearance and the desired paint film cannot be obtained. Further, it is not preferable to include a pigment in the third layer because it causes problems in finished appearance and weather resistance. The amount of pigment added to the second clear paint of the second layer is 0.5 to 10 parts based on the solid content of the resin. If it is less than 0.5 parts, the effect of imparting color will be poor, and if it is more than 10 parts, the hiding power will increase, resulting in a metallic pigment. This is not desirable because it cancels out the color of the color. The preferred range is 2 to 5 parts in the paint. As metallic pigments that can be applied to such purposes, highly transparent pigments are preferred, including butt-type pigments such as perylene, flavanthrone, and threne, quinacridone pigments, phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green, benzimidazolone, Isoindolinone, azo pigments such as watching red, transparent red petals,
There are transparent yellow petals, metal complex pigments, etc. In addition, a trace amount (non-transparent) colored pigment may be added in an amount of about 1% or less. Next, in the third layer as a third clear paint, an acrylic resin and its crosslinking agent, such as an amino resin or a polyester resin, or a combination of an acrylic resin and an isocyanate are used as a vehicle. The number average molecular weight of the acrylic resin is preferably 5,000 to 10,000. If the number average molecular weight is less than 5,000, coating film quality such as a decrease in weather resistance and hardness will deteriorate, and if it exceeds 10,000, the finished appearance will deteriorate, which is not preferable. The number average molecular weight of polyester resin is 2000~
A range of 4000 is preferred. If the number average molecular weight is less than 2,000, the quality of the coating film will deteriorate, such as a decrease in weather resistance and hardness, and if it exceeds 4,000, the finished appearance will deteriorate. The first clear paint and the third clear paint may be the same or different, but if they are different, resins with the same number average molecular weight are used. The reason why the base paint and the clear paint are made of a combination of resins having different molecular weights is because each paint is used for different purposes, as described below. Metallic base coating Formation of a uniform metallic paint film First layer of the first clear paint Second layer of the second clear paint that hides the convexities of the metallic pigment The clear coat uniformly provides a color layer that is not present in metallic pigments to the paint film. Makes the first and third layers of paint adhere firmly. Third layer of third clear paint Appearance of paint film (aesthetic appearance)
Improvement and ensuring durability such as weather resistance In addition, additives such as ultraviolet absorbers, light stabilizers, plasticizers, surface conditioners, and antistatic agents can be added to each clear paint as appropriate. To carry out the method of the present invention, an air spray or stationary or hand-held electrostatic atomizer is used for metallic base paints, and an electrostatic atomizer or air sprayer is used for clear paints. Then, the metallic base paint and the first clear coat are wet-on-wet.1
An excellent four-layer metallic coating can be formed by baking and then applying a wet-on-wet two-coat one-bake coating of a second clear (colored) and a third clear. A more detailed explanation will be given below based on examples. Base coat production example A1: Almatex NT448 (acrylic resin) manufactured by Mitsui Toatsu Chemical Co., Ltd. and 100 parts of melamine resin to Alpaste Milaglow 1000 manufactured by Toyo Aluminum Co., Ltd.
5% (solid content) and 2 phthalocyanine blue #314 (manufactured by Sanyo Shiki Co., Ltd.) dispersed in acrylic resin in advance.
% and sufficiently stirred with a stirrer to obtain base coat A1. The average particle size of Miragrow 1000 is 25 μ Base coat manufacturing example A2 10% (solid content) of Iriodin 140 made by Shimmer Pearl Co., Ltd. based on Almatex NT448 made by Mitsui Toatsu Chemical Co., Ltd. and 100 parts of melamine resin, Paliogen Maroon 3920 made by BASF Co., Ltd. 1 % and thoroughly stirred with a stirrer to obtain base coat A2. The average particle size of Iriodin 140 is 85μ Base coat manufacturing example A3 Dianal HR-559 manufactured by Mitsubishi Rayon Co., Ltd. (7.5% (solid content) Alpaste HS-2 manufactured by Toyo Aluminum Co., Ltd. based on 100 parts of acrylic resin and melamine resin, Toyo Soda 2.5% of Rubicron 500RG, a quinacridone-based pigment, and 0.3% of Carbon Black MA100, manufactured by Mitsubishi Kasei Corporation, were mixed thoroughly with a stirrer to obtain base coat A3.The average particle size of Alpaste HS-2 was 18μ Base coat Production Example A4 10% (solid content) of aluminum paste MG21 manufactured by Asahi Kasei Co., Ltd. was blended with 100 parts of Dianal HR-559 manufactured by Mitsubishi Rayon Co., Ltd. and melamine resin, and thoroughly stirred with a stirrer to obtain base coat A4. The average particle size of MG21 is 24μ Base coat manufacturing example A5 10% (solid content) Alpaste 52-509 manufactured by Toyo Aluminum Co., Ltd. for 100 parts of Almatex NT448 and melamine resin manufactured by Mitsui Toatsu Chemical Co., Ltd.
Mix thoroughly with a stirrer and apply the base coat.
Got A5. The average particle size of Alpaste 52-509 is 30μ Base coat manufacturing example A6 Base coat A2 Paliogen Maroon #3920
Base coat A6 was obtained in the same manner as A2 except that the base coat was changed to 3%. First and third clear paint production example B1 70 parts by weight of acrylic resin Almatex NT448 with a molecular weight of 8000 manufactured by Mitsui Toatsu Chemical Co., Ltd. (the same applies below)
and 30 parts of melamine resin manufactured by Dainippon Ink and Chemicals Co., Ltd. to obtain Daiichi Clear Paint B1. Example of manufacturing the first and third clear paints B2 Example of manufacturing the first clear paint and the third clear paint using acrylic two-component urethane Acrydec A-801 with a molecular weight of 6000 manufactured by Dainippon Ink & Chemicals Co., Ltd. B2
And so. First clear paint manufacturing example B3 70 parts by weight of acrylic resin Dianal HR-559 with a molecular weight of 6000 manufactured by Mitsubishi Rayon Co., Ltd. (the same applies below)
and 30 parts of melanin resin manufactured by Dainippon Ink and Chemicals Co., Ltd. to obtain Daiichi Clear Paint B3. Example of manufacturing the first clear paint B4 5 parts of Phthalocyanine Blue #314 is blended with the first clear paint B1, and dispersed with Premix and a sand grind mill to make the first clear paint.
Got B4. Second clear paint production example C1 70 parts by weight of acrylic resin Almatex NT-U-23 with a molecular weight of 15,000 (manufactured by Mitsui Toatsu Chemical Co., Ltd.), melamine resin part manufactured by Mitsui Toatsu Chemical Co., Ltd., and phthalocyanine manufactured by Sanyo Shiki Co., Ltd. 5 parts of Blue #314 were blended and dispersed in Premix and a sand grind mill to obtain a second clear paint C1. Second clear paint manufacturing example C2 In the manufacturing example of C1, two parts of BASF's Paliogen Maroon #3920 was blended instead of Phthalocyanine Blue #314, and dispersed with Premix and a sand grind mill to obtain the second clear paint C2. Ta. Second clear paint production example C3 In the production example of C1, 2.5 parts of Rubicron 500RG was added instead of Phthalocyanine Blue #314,
A second clear paint C3 was obtained by dispersing with Premix and a sand grind mill. Second clear paint production example C4 In the production example of C1, 3 parts of Paliogen Maroon #3910 manufactured by BASF was blended instead of phthalocyanine blue and dispersed with Premix and a sand grind mill to obtain a second clear paint C4. Manufacturing example of second clear paint C5 Second clear paint using 70 parts by weight (the same applies hereinafter) of acrylic resin Almatex NT-U-23 with a molecular weight of 15,000 manufactured by Mitsui Toatsu Chemical Co., Ltd. and 30 parts of melamine resin manufactured by Mitsui Toatsu Chemical Co., Ltd. Obtained C5. Third clear paint manufacturing example D1 70 parts by weight of acrylic resin Dianal HR-522 with a molecular weight of 8000 manufactured by Mitsubishi Rayon Co., Ltd. (the same applies below)
3 parts of Paliogen Maroon #3910 was blended with 30 parts of melamine resin manufactured by Mitsui Toatsu Chemical Co., Ltd., and dispersed using Premix and a sand grind mill to obtain the third clear paint D1. The metallic base coat obtained as above, the first clear paint, the second clear paint,
The third clear paint was applied by the following method. On a 10cm x 30cm test plate, apply Nippon Paint Co., Ltd.'s electrocoating paint Power Top U-30 to a dry film thickness of 20μ (the same applies hereafter), and then paint and bake Nippon Paint Co., Ltd.'s intermediate coating Olga S50 Sealer. death,
Four metallic layers were then laminated with four coats and two bases. The metallic base coat was applied to about 20μ by air spray, and after flashing off the solvent for 1 to 3 minutes, the first clear paint was applied to about 30μ by air spray, and then baked at 140°C for 30 minutes. Furthermore, after applying the second clear paint to a thickness of about 25μ by air spray and flashing off the solvent for 1 to 3 minutes, apply the third clear paint to a thickness of about 30μ by air spray, and then baking at 140℃ for 30 minutes. A metallic coating consisting of layers was obtained. However, acrylic two-component urethane is heated at 120℃ x 20
Forced drying was performed in minutes.

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【table】

[Table] The evaluation in Table 2 was performed by the following method. (1) Marcel value SM color computer manufactured by Suga Test Instruments Example 2.5PB 5.25/16.42 ↑ ↑ ↑ Hue Brightness Saturation The original saturation differs depending on the hue, but improvement in saturation can be seen in each color gamut. . (The saturation values for each color are higher than in the past.) Comparative Examples 5 and 6 have improved only the saturation, but the appearance and quality are not sufficient. In Comparative Example 9, the brightness and chroma are decreased, and a deep color tone cannot be obtained. (2) Depth Judgment with the naked eye ◎ Excellent ○ Average × No depth (3) Flickering Judgment with the naked eye ◎ Not at all ○ Almost none × Severe flickering (4) Discoloration Used by Daiei Kagaku Seiki Seisakusho Dyed Rubbing Fastness Tester Check after 3 months of exposure to Okinawa.
Evaluation results after rubbing 10 times with a flannel coated with 10all). (5) PGD value Measured value by Japan Color Research Institute This is a measuring device for image sharpness that simultaneously measures the smoothness and gloss of the painted surface, so the higher the value, the better. Effects of the Invention According to the configuration of the present invention, it is possible to use metallic pigments with large diameters that could not be used in the conventional two-coat, one-bake process. As a result, brightness, complex color tone, and deep, vivid color tone that could not be achieved with metallic pigments alone were obtained. These effects are metallic base / first clear / second (transparent colored)
This was effectively achieved by a 4-coat, 2-bake metallic coating film consisting of 4 layers of clear/third clear.

Claims (1)

[Scope of Claims] 1. A first clear paint is applied as a first layer wet-on-wet on a birth coat containing a metallic pigment, and then baked, a second clear paint is applied as a second layer, and a second clear paint is applied as a second layer. It consists of four layers in which a third clear paint is further laminated and baked as a top coat while wet, and the second clear paint contains 0.5 to 10 parts of pigment based on the resin solid content, and the first clear paint and third clear paint A method for forming a four-layer metallic coating film by four coats and two bakes, characterized in that the resins used are the same or different within a number average molecular weight range. 2 50% by weight of metallic pigment in base coat
or more has a diameter of 25μ or more Claim 1
A method for forming a four-layer metallic coating film as described in Section 3. 3. A method for forming a four-layer metallic coating film according to claim 1, which is applied as a top coating film for automobiles.