JPH0732893B2 - Method for forming multicolor coatings - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a multicolor coating, and in particular, a colored base is applied to a surface to be coated of an automobile or the like, and a mica base coating has a difference in film thickness. The present invention relates to a method of forming a multicolor coating by coating as described above.

[Prior Art] The multi-color paint finish of automobiles has conventionally been done by two-tone finish. This is obtained by applying the first paint, baking it, masking a part of it, applying the second paint of a different color, and baking again. However, in such a method, since baking is performed twice, overbaking occurs, which causes problems such as yellowing, deterioration of weather resistance, and a large step at the parting portion. In addition, it has not been possible to sufficiently meet the recent demand for design diversity.

Various proposals have been made to solve these problems. For example, Japanese Unexamined Patent Publication No. 60-58270 discloses a two-tone color finishing method which comprises applying a two-tone color coating with an intermediate coating material and then coating the entire surface with a colored transparent or semi-transparent top coating material. Specifically, after forming a first intermediate coating film and baking, a part of it is masked and a second intermediate coating material is applied, and baking is performed in the same manner. After that, the masking is removed, a colored transparent or semitransparent topcoat paint is applied on the entire surface, and baking is performed again.

Further, in JP-A-60-118266, a first undercoat layer is formed by applying a paint of the first undercoating color to an object to be coated, and a second undercoating color is applied to a selected area on the first undercoat layer. Disclosed is a two-tone color coating method characterized in that a concealing paint is applied to form a second underlayer, and a clear paint is applied on the upper surfaces of the paint films of the first and second underlayers. In this method, a low hiding paint such as pearl mica is used for forming the second underlayer. In this coating method, three layers of color base, mica base and clear are used to create the color.

[Problems to be Solved by the Invention] However, in the method of Japanese Patent Laid-Open No. 60-58270, two-tone color finishing is performed by different color intermediate coatings, so it is necessary to bake twice, which is not economical.
In addition, the film thickness of the top coating is uniform, and it is not possible to provide sufficient variety in terms of design. The method disclosed in JP-A-60-118266 is based on a color base (first underlayer) and mica base (second base layer).
Since the three layers (underlayer) and clear (finishing layer) are colored, only a partly pearl mica tone is obtained, and a satisfactory finished appearance cannot be obtained.

Therefore, it is an object of the present invention to provide a method capable of economically forming a multicolor coating having a mica tone in a single baking.

[Means for Solving Problems] As a result of earnest research in view of the above object, the present inventors have found that the composite color of the colored base and the mica base coating film is changed by changing the film thickness of the mica base coating formed on the colored base. The present invention has been accomplished by discovering that the above can be variously changed.

That is, the method for forming a multicolor coating of the present invention comprises (a) a mica having a hiding power of 50 μm or more, which contains 0.1 to 10% by weight of a mica pigment in a part of a coated object on which a colored base is formed. The base paint is applied so as to have a dry film thickness of 10 to 25 μm to form a first mica base paint film. (B) Further, the mica base paint is applied to the entire surface of the coated object in an amount of 10 to 25 μm.
A second mica base coating film was formed by coating so as to obtain a dry film thickness of m, and was laminated with the mica base coating film obtained by the step (b) in the steps (a) and (b). It is characterized in that the composite color with the colored base is changed by the difference in the film thickness from the mica base coating film.

Further, the second method for forming a multicolor coating of the present invention comprises: (a) 0.1 to 10% by weight of a mica pigment in a part of an article to be coated with a colored base, and a hiding power of 50 μm or more. Is applied to form a first mica base coating film, and (b) the mica base paint is applied to almost the entire surface of the article to be coated in an amount of 10 to 25 μm. A second mica base coating film is formed by coating so as to have a dry film thickness of 25 μm, (c) a clear paint is further coated, and the mica base coating film and the step (a) obtained by the step (b) are obtained. ) And the film thickness of the mica base coating film laminated in step (b), the composite color with the colored substrate is changed.

The mica base paint reflects and scatters transmitted light by the mica particles dispersed in the paint to generate a pearl-like shine, but when it is formed on a colored base, it forms a complex color with it. It was also found that the composite color changed significantly depending on the film thickness of the mica base coating film. Utilizing this property, the method of the present invention achieves multicoloring of the mica paint by partially changing the coating film thickness of the mica base paint.

In the method of the present invention, the colored base is a coating film (color intermediate coating), a coloring tape, a fluorescent tape or the like and is not particularly limited. For example, in the coating of automobile outer panels, a color intermediate coating is used.

The color intermediate coating may be formed directly on the article to be coated, but it is usually formed after applying an undercoat (primer). The undercoat is usually formed by electrodeposition coating, and conventionally known anionic or cation type electrodeposition coating is used for this. When an anionic electrocoating material is used, it is carried out in water by using the article to be coated as an anode and separately providing a cathode. The reverse is true when a cationic electrodeposition paint is used. The film thickness of the electrodeposition coating is usually 15 to 20 μm as a dry film thickness, but even if it is higher than this, there is no particular problem in terms of performance except for economy.

There are various types of color intermediate coatings that can be used in the present invention, but those particularly preferable for automobile coating and the like are those based on a thermosetting resin. As the thermosetting resin, alkyd resin, oil-free alkyd resin, acrylic resin or the like can be used. The color intermediate coating composition further contains a curing agent, a coloring pigment, a solvent and the like. Examples of curing agents for thermosetting resins include melamine resins and polyisocyanates having free NCO groups. The weight ratio of the thermosetting resin to the curing agent is preferably 85:15 to 40:60. Further, as the coloring pigment, any one can be selected from white pigments such as titanium white and organic or inorganic pigments in order to produce a desired color. In general, the pigment concentration in the paint is preferably about 5 to 55% by weight. Further, the solvent is used to dissolve the thermosetting resin to improve the dispersibility of the color pigment, adjust the viscosity of the coating material to improve workability, and improve the finished appearance of the coating film. For these purposes, for example, aliphatic hydrocarbons, aromatic hydrocarbons, ketones, esters and the like are preferable.

Color intermediate paint is applied to a film thickness of 20 to 50 μm and 100 to 1
Bake at 60 ℃ for 10 to 20 minutes. If necessary, the resulting intermediate coating is water-ground with # 600 paper to improve smoothness.

Next, masking is partially applied to a colored base material consisting of a color intermediate coating with tape or paper according to a desired pattern. A mica base paint is applied on this masked colored substrate.

There are various mica-based paints that can be used in the method of the present invention. Among them, pearl white mica in which mica is coated with a thin layer of titanium white, and a coating layer of titanium white has a relatively thick interference color. Interfering mica that emits, colored mica coated with iron oxide, and the like are preferable. These mica pigments are commercially available from Merck Co., Marl Co., Nikko Kogyo Co., Ltd., Teikoku Kako Co., Ltd., EM Chemical Company and the like.

The mica-based paint has a hiding power of 50 μm or more in order to produce a clear composite color with the colored base. If the hiding power is less than 50 μm, the color change due to repeated coating of the mica base paint is too small, and multicolor coating cannot be effectively obtained. However, from the practical point of view, those having a hiding power of 50 to 150 μm are preferable.

Further, the content of the mica pigment in the mica-based paint of the present invention is 0.1 to 10% by weight. If it is less than 0.1% by weight, the color of the colored base is too strong and the effect of mica coating is insufficient.
On the other hand, when it exceeds 10% by weight, the gloss of the mica base coating film is lowered and the finished appearance is deteriorated. The preferable content of the mica pigment is 0.5 to 8% by weight.

The vehicle resin in the mica base paint may be the same as in the color intermediate coating paint, and the same additives and solvents as a curing agent can be used.

The mica base paint having the above composition is applied onto a partially masked color intermediate coating (colored base) to form a first layer of the mica base paint. The dry film thickness of this first layer is 10 ~
It is 25 μm, preferably 10 to 15 μm.

After forming the first mica-based coating film, the masking is removed and the second layer of the mica-based paint is applied repeatedly without baking. In order to fully exert the multicolor coating effect,
The second layer of mica-based paint is the same as the first layer, 0.
It preferably has a mica pigment content of 1 to 10% by weight and a hiding power of 50 μm or more. The coating thickness of the second layer of this mica-based paint is 10 to 25 μm, preferably 10 to 15 μm.

The mica-based coating film formed on the colored substrate as described above has only the second layer (10
.About.25 .mu.m), but the first layer + second layer (20-50 .mu.m) in the unmasked portion. As described above, since the coating film of the mica-based paint changes in film thickness according to the desired pattern, the composite color with the colored substrate also changes accordingly. As a result, a multicolor coating having a desired pattern can be obtained.

After the mica base paint has been applied, apply clear paint as needed. The same thermosetting resin and curing agent as those used for the color intermediate coating composition can be used for the clear coating composition. It is economical to apply the clear paint wet-on-wet on the coating film of the mica base paint, but there is no problem even if it is applied after baking the mica base paint. In either case, the top layer of clear paint is baked.

[Examples] The present invention will be described in more detail based on the following examples.

Example 1 A multicolor coating with a colored base and a mica base coating was formed under the following conditions.

(1) Object to be coated: 0.8 mm x 300 mm x 500 mm steel plate.

(2) Pretreatment: Zinc phosphate type surface treatment agent "Granodine SD
-5000 "(manufactured by Nippon Paint Co., Ltd.) coating.

(3) Undercoat: "Power Top U-30" (manufactured by Nippon Paint Co., Ltd.) was applied as a cationic electrodeposition paint. Dry film thickness 20
μm. Bake at 180 ℃ for 20 minutes.

(4) Color intermediate coating: "Olga P-2 Blue" (N-Paint manufactured by Nippon Paint Co., Ltd. as an oil-free melamine-based paint)
-6) is painted. Bake at 140 ℃ for 20 minutes. Dry film thickness 35μ
m.

(5) Mica-based paint and coating: (a) Mica-based paint: Interference blue Acrylic resin paint containing 5% by weight of "Exterior Highlight Blue" from Marl as mica ("Super" manufactured by Nippon Paint Co., Ltd.) Rack M-12 "). Hiding power 200μm.

(B) First layer: One stripe is attached to the central portion of the color intermediate coating with masking tape, the object to be coated is placed on the conveyor, and the above mica base paint is applied by a spray gun under the following conditions. .

Spray gun: REA cap No.6 Number of spray guns: 2 Spray gun distance: 30cm Spray gun stroke: 25 reciprocations / minute Coating viscosity: 13 seconds / # 4 Ford cup 20 ° C Discharge rate: 300cc / minute Atomizing air pressure : 4.5Kg / cm ² Applied voltage: -60KV Conveyor speed: 4m / min Pattern width: 30cm Film thickness: 10μm (c) Second layer: After coating the first layer, remove the masking tape and apply the above mica base paint first. Wet-on-wet coating under the same conditions as the layers. Film thickness 10 μm.

(6) Clear coating: "Superlac O-28M clear" (manufactured by Nippon Paint Co., Ltd.) as an acrylic resin-based clear coating was applied wet-on-wet on the second layer of the obtained mica-based coating. Bake at 140 ℃ for 20 minutes. Dry film thickness 35μm.

With respect to the obtained multicolor coating, multicolor (contrast of two colors), PGd value (visibility), gloss, accelerated weather resistance, adhesion and impact resistance were measured under the following conditions.

Polychromatic: Visual judgment.

PGd value: Evaluated by PGD-4 type manufactured by Japan Color Research Institute.

Glossiness: judged by the naked eye.

Accelerated weather resistance: JIS K 5400 6.17 Expressed by gloss retention (%) after 400 hours.

Adhesion: JIS K 5400 6.15 Measured by a cellophane tape peeling test of 100 (1) substrate at 1 mm intervals. It is represented by the number of remaining grids.

Impact resistance: JIS K 5400 6.13 500 g weight and 1/2 inch diameter shot type are used.

Example 2 A multicolor coating was formed under the same conditions as in Example 1 except that the brightness of the "Orga P-2 Blue" paint for color intermediate coating was changed from N-6 to N-3, and the same test was conducted. went.

Example 3 A multicolor coating was formed under the same conditions as in Example 1 except that the concentration of the mica pigment in the mica-based paint was changed to 10% by weight, and the same test was performed.

Example 4 Part of the color intermediate coating film in the fifth step of Example 1
Fluorescent tape made by Sumitomo 3M of 20 x 400 mm is attached, and the sixth
Superlac M-12 was coated to a hiding power of 200 μm in the step, Superlac O-28M clear was coated in a wet-on-wet manner in the seventh step, and a test piece was prepared in the same manner as in Example 1 except for the above. Tested.

Comparative Example 1 A multicolor coating was formed under the same conditions as in Example 1 except that the color intermediate coating was multicolored by masking and the mica base coating film was a single layer, and the same test was performed.

The test results of Examples 1 to 4 and Comparative Example 1 described above are shown in Table 1 below.

From the results shown in Table 1, it can be seen that the multicolor coating formed by the method of the present invention has excellent color tone contrast and good coating performance.

Example 5 A multicolor coating was formed under the same conditions as in Example 1, except that the concentration and hiding power of the mica pigment in the mica base coating were as shown in Table 2 below.

The same tests as in Example 1 were carried out for each multicolor coating. The results are shown in Table 2.

From the results in Table 2, it can be seen that when the mica pigment concentration is in the range of 0.1 to 10% by weight, the color tone contrast is good.

Example 6 A multicolor coating was formed under the same conditions as in Example 1 except that the thicknesses of the first layer and the second layer of the mica-based paint were changed as shown in Table 3 below, and the same test was performed. . The results are shown in Table 3.

From the results of Table 3, the film thickness outside the range of the present invention (Sample N
It can be seen that o.1 and 4) have poor color tone contrast. For sample No. 1, sufficient contrast of color tone was not obtained even if the concentration of mica pigment was higher than 5% by weight, and for sample No. 4, even if the concentration of mica pigment was lower than 5% by weight. Similarly, a satisfactory color tone contrast was not obtained.

[Effects of the Invention] The method for forming a multicolor coating of the present invention has the following effects.

(1) By utilizing the film thickness difference of the mica-based paint, it is possible to easily obtain contrasts of various color tones.

(2) To obtain a coating film of extremely various designs by attaching a coloring tape or a fluorescent tape to a part of the color intermediate coating to form a multicolored mica coating film. You can

(3) Since the mica base coating film is multicolored, the complex color with the colored base can be a beautiful pearl mica tone.

(4) Since the mica base paint can be applied wet-on-wet on the color intermediate coating, the number of bakings can be reduced as a whole, which is economical.

(5) Due to the above characteristics, the method of the present invention is particularly effective for the cosmetic coating of automobile outer panels.

Claims (6)

[Claims] (A) A mica base paint containing 0.1 to 10% by weight of a mica pigment and having a hiding power of 50 μm or more is dried to a thickness of 10 to 25 μm. The first mica base coating film is formed by coating so as to have a film thickness, and (b) the mica base paint is applied to almost the entire surface of the object to be coated so as to have a dry film thickness of 10 to 25 μm. Difference in film thickness between the mica base coating film obtained in step (b) and the mica base coating film laminated in step (a) and step (b) by forming a second mica base coating film by stacking The method for forming a multicolor coating is characterized in that the composite color with the colored base is changed by means of. 2. A mica-based paint having a hiding power of 50 μm or more containing 0.1 to 10% by weight of a mica pigment in a part of a coated object on which (a) a colored base is formed, and dried to 10 to 25 μm. The first mica base coating film is formed by coating so as to have a film thickness, and (b) the mica base paint is applied to almost the entire surface of the article to be coated.
A second mica base coating film is formed by coating the dry coating film to a dry film thickness of 10 to 25 μm, and (c) a clear paint is further applied, and thus the mica base coating film obtained in step (b) and the step A method for forming a multicolor coating, wherein a composite color with the colored base is changed by a difference in film thickness between the mica base coating film laminated in (a) and the step (b). 3. The method for forming a multicolor coating according to claim 1, wherein the second mica base coating film is formed on the first mica base coating film by wet on wet. A method for forming a characteristic multicolor coating. 4. The method for forming a multicolor coating according to claim 2, wherein the second mica base coating film is formed on the first mica base coating film by wet on wet. A method for forming a characteristic multicolor coating. 5. The method for forming a multicolor coating according to claim 1 or 3, wherein the colored base is a color coating film to which a coloring tape or a fluorescent tape is attached. A method for forming a multicolor coating, comprising: 6. The method for forming a multicolor coating according to claim 2 or 4, wherein the colored base is a colored coating film having a colored tape or a fluorescent tape attached to a part thereof. A method for forming a multicolor coating, comprising: