JP3430168B1 - Clear painted metal plate with vivid colors - Google Patents

Abstract

An object of the present invention is to provide a coated metal plate provided with a clear coating film that prevents mixing of interference colors and exhibits a clear color tone without whitening. [Constitution] A plurality of clear coatings C ₁ and C ₂ having different refractive indices are provided on the surface of a metal substrate S, and a transparent or translucent transparent color developing a different color tone for each of the clear coatings C ₁ and C ₂ . Color pigments Pr and Pg are dispersed.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clear-coated metal plate having a clear color tone which is colored by the interference of light. 2. Description of the Related Art As exterior materials for home electric appliances, OA appliances, kitchen appliances and the like, clear coated metal plates utilizing the metallic feeling of metal surfaces have begun to be used. Clear painted metal plate
An atmosphere that cannot be obtained with a conventional colored painted metal plate is brought out with a metallic feeling, so that it is expected as a product with high discrimination. The clear-painted metal plate is manufactured by applying a clear paint containing a coloring agent to the surface of an original paint plate and baking and drying. When a dye is used as a colorant, an organic pigment is usually used because the color is easily discolored at the time of baking and the color tone is not stable. In a color clear coating film containing an organic pigment, a specific wavelength component of light incident on the coating film is absorbed by the organic pigment, and the remaining incident light is reflected by the surface of the base metal plate, and reflected light excluding the absorption wavelength component A specific color tone appears. [0003] The amount of light absorbed by the organic pigment while the incident light is transmitted through the color clear coating film varies depending on the thickness of the coating film. The thinner the coating, the lower the absorption. Therefore, the color tone to be developed is highly dependent on the film thickness, and the color tone is liable to change slightly even with a slight change in the film thickness. Variations in color tone are emphasized as color unevenness when clear coating metal plates of different production lots are abutted and constructed. In addition, since the color tone is given by the organic pigment, the metallic luster of the base metal plate is liable to be deteriorated, and the color tone tends to give a low L value and a blackish cold feeling. The matting of the coating can prevent a decrease in the L value, but the matting impairs the transparency of the coating, lowers the sharpness and eliminates the luxury. Therefore, the present inventors have conducted various investigations and studies on pigments to be dispersed in a clear coating film. As a result, when a coloring pigment in which a flaky inorganic substrate is coated with a transparent metal oxide is dispersed, the color tone is caused by light interference. Were found, and it was found that a clear coated metal plate excellent in color tone stability without color tone fluctuation or L value decrease was obtained (Japanese Patent Application No. 2001-376893). However, it was found that dispersing a coloring pigment having a different color tone into the clear coating resulted in a whitish color tone, and the advantages of the clear coated metal plate were easily damaged. The present invention is a further improvement of the color pigment-dispersed clear coating film proposed in the prior application,
It is an object of the present invention to provide a clear coated metal plate that prevents a color tone from whitening by dispersing a coloring pigment in clear coating films having different refractive indices from each other and presents a clear and highly designed appearance. The clear coated metal plate of the present invention, in order to achieve the object, a plurality of clear coatings having different refractive indices provided on the surface of the metal substrate, the hue is different for each clear coating, scaly inorganic substrate. A coloring pigment coated with a transparent or translucent metal oxide is dispersed. [0006] The refractive index of the clear coating film can be changed according to the base resin of the clear coating material. Mica flakes, glass flakes, alumina flakes, silica flakes and the like are used as the scaly inorganic substrate, and TiO ₂ , SiO ₂ ,
ZrO ₂ , Fe ₂ O ₃ , SnO ₂ , Fe ₃ O ₄ , Cr ₂ O ₃ , Z
It is coated with a metal oxide such as nO or Al ₂ O ₃ . The hue of the coloring pigment can be adjusted by the thickness of the metal oxide film. The clear coating film in which a plurality of coloring pigments having different hues are dispersed is presumed to cause a whitening phenomenon due to the mixture of interference colors. For example, in a clear coating film in which red and blue organic pigments are dispersed, red and blue are mixed with each other to produce a purple hue. In the coating film C, the interference colors Lr and Lg emitted from the individual color pigments Pr and Pg intersect with each other, and as a result, are observed as light Lw having high whiteness (FIG. 1). The present inventors have conducted various investigations and examinations on a clear coating film which does not whiten under such a premise. As a result, the clear coating has a multilayer structure with different refractive indices,
It has been found that when dispersing a coloring pigment which emits an interference color having a different hue in each clear coating film, a clear coating film exhibiting a sharp color tone without unexpected whitening can be obtained. The mechanism by which the multilayer structure of the clear coatings with different refractive indices suppresses whitening is unknown, but the hue of the coloring pigment is emphasized or suppressed by the refractive index of the clear coating, and it becomes the background of hue. It is speculated that the cause may be that light is refracted in multiple steps in the clear coating film. In a clear coated metal plate in which a plurality of clear coatings C ₁ and C ₂ are laminated on a metal substrate S, the incident light Lin is refracted by the surface clear coating C ₁ and further refracted by the lower clear coating C _2. . Part of the incident light Lin is reflected by the coloring pigments Pr and Pg dispersed in the clear coating films C ₁ and C ₂ (FIG. 2). Since the transparent or translucent metal oxide film M is formed on the surface of the coloring pigments Pr and Pg, light is reflected on the metal oxide film M.
And on the surface of the scaly inorganic substrate F (FIG. 3). The light L ₁ reflected on the surface of the metal oxide film M and the scaly inorganic substrate F
Since the optical path difference ΔL is generated between the light L ₂ reflected by the surface of interference color Lr by the interference effect of light, it is emitted as Lg. The light of the interference color wavelengths Lr and Lg is applied to the clear coating C
_1, passes through the C ₂ is emitted to the outside as reflected light L _ref.
It is presumed that the hue component of the reflected light _Lref is emphasized or attenuated when passing through the clear coating films C ₁ and C ₂ , and whitening is suppressed. In fact, as is clear from the examples described later, when two types of color pigments having different hues are dispersed in the single-layer clear coating film C, the values of a and b are decreased.
When dispersed in each of the multiple clear coatings C ₁ and C ₂ having different refractive indices, a coating having a clear color tone without a decrease in the a value and the b value can be obtained. In addition, since the color is developed by the interference effect of light, a clear painted metal plate having a different hue depending on the viewing angle and exhibiting a clear color tone is obtained. DESCRIPTION OF THE PREFERRED EMBODIMENTS A metal substrate S is used in a product form in which a glossy metal surface is observed. Therefore, stainless steel, various plated steel sheets, aluminum, aluminum alloy, copper, copper alloy, magnesium , Magnesium alloys and the like are used. Prior to the formation of a clear coating film, degreasing and pickling
Chromate treatment, phosphate treatment, chromium-free treatment, etc.
An appropriate pre-coating treatment is performed on the metal substrate S. [0012] The paint for forming the clear coating film does not impose any particular restrictions on the kind of the paint, but has high transparency such as acrylic, polyester, urethane, polyolefin, and the like.
Organic resins such as fluorine-based, epoxy-based, vinyl acetate-based, and chloroprene-based resins, or resins that form these shrinking patterns or organic resins containing inorganic polymers can also be used. The rate changes.
For example, a refractive index of about 1.4 for an epoxy system, about 1.5 for a polyolefin system, and about 1.6 for a polyester system. Anticorrosive pigments, coloring pigments, dyes, and the like may be added to the clear coating film forming paint as needed as long as the transparency is not impaired. In FIG. 2, the clear coating films having the two-layer structure C ₁ and C ₂ are provided on the metal substrate S, but the number of the clear coating films can be appropriately changed as long as the refractive indexes are different from each other. Since the clear-coated metal plate may be processed into a product shape after forming the clear coating films C ₁ and C ₂ , the lower layer is required to have high adhesion to the metal substrate S and high flexibility of the coating film itself. required for clearcoats C _2. On the other hand, the surface layer clearcoats C _1, sometimes耐疵with is required. The resin system of the clear paint is selected in consideration of the characteristics according to the purpose. For example, the clear paint films C ₁ and C ₂ are formed by using a paint appropriately mixed with a curing agent such as melamine and isocyanate.
Is formed. The coloring pigment to be incorporated in the clear paint forms a metal oxide film M on a scaly inorganic substrate F such as mica, glass flake, alumina flake, silica flake by a wet method, a CVD method, a powder sputtering method or the like. It is manufactured by Since the probability of the incident light L _in chromogenic pigment surface enough to orient the scale-like inorganic substrates F in the creepage direction of the metal substrate S is reflected increases, the aspect ratio (maximum ratio of diameter to thickness) of greater scale-like inorganic substrates F Is more preferable.
Specifically, when the aspect ratio becomes 60 or more, most of the flaky inorganic substrate F is dispersed in the clear coating films C ₁ and C ₂ with an orientation parallel or almost parallel to the surface of the metal substrate S, and the transparent metal The interference color of the oxide film M is strongly exhibited, resulting in a vivid color tone and a brilliant feeling. Mica is used as a scaly inorganic substrate F,
In the case of TiO ₂ coating by a wet method, various methods can be adopted. For example, mica is suspended in a dilute aqueous solution of titanic acid and heated to 70 to 100 ° C. to precipitate hydrated titanium oxide particles, which are hydrolysis products of a titanium salt, on the mica surface. Baking at high temperature with Ti
O ₂ coating is formed. The thickness of the TiO ₂ coating can be controlled by processing conditions such as the concentration of the titanium salt, the temperature of the suspension, and the processing time. In the case of producing a coloring pigment by the powder sputtering method, a scaly inorganic substrate F such as mica or glass flake is used.
Is put in a rotating drum, and sputtering is performed in a reactive atmosphere with Ti as a target, whereby a TiO ₂ coating is formed on the surface of the scaly inorganic substrate F. After the clear paint containing the coloring pigment is applied to the original coating plate, the lower clear coating film C ₂ is obtained by heating at 200 to 280 ° C. for 30 to 120 seconds, depending on the type and amount of the clear paint resin. It is baked on the metal substrate S.
Then laminating the surface layer clearcoats C ₁ in the lower layer clear coating film C ₂ by a similar method. Observation of the obtained clear-coated metal plate reveals a clear color tone without whitening because the intermingling of interference colors is suppressed. Moreover, since the metallic luster of the metal substrate S is utilized and the metallic luster giving a cool feeling of the inorganic material is softened by the clear coating films C ₁ and C ₂ , the appearance becomes milder. Further, since the color tone varies depending on the viewing angle, a clear painted metal plate having excellent design properties is obtained. EXAMPLE SUS with a hairline finish of 0.4 mm thickness
430 stainless steel plate was used for the original plate for painting. The coated original plate was pickled with 2% hydrochloric acid and subjected to an acid-based surface treatment.
A coating type chromate treatment with a reduced adhesion amount of 20 mg / m ² was performed. In the clear coating for the lower layer coating C2, ₂ coloring pigments Pr were used.
Using mass% compounded refractive index of about 1.4 epoxy clear resin coating, upper layer coating the refractive index of about 1.6 of the polymeric polyester clear paint for C ₁ in which a coloring pigment Pg blended 2% by weight A system clear resin paint was used. Color pigments Pr, Pg
The mica flakes having an aspect ratio of 150 and a central particle size of 30 μm and having a color tone shown in Table 1 and having a TiO ₂ film having a thickness of 50 to 140 nm were used. The lower coat layer C ₂ for the clear coating was applied to the painted original plate, to form a lower layer clear coating film C ₂ having a dry film thickness of 10μm by heating 50 seconds at 210 ° C.. Then, the clear paint for top coating film C ₁ was coated to form a top layer clear coating film C ₁ having a dry film thickness of 10μm by heating 60 seconds at 230 ° C.. For comparison, a dry film in which a single color pigment is dispersed by blending 4% by mass of a color pigment having a different hue alone in a high molecular weight polyester clear resin paint having a refractive index of about 1.6 and a total of 4% by mass. 20 μm thick single layer clear coating C
(Test Nos. 2, 6, 10 and 3, 7, 11) and a single-layer clear coating film C (Test Nos. 4, 8, 12) having a dry film thickness of 20 μm in which two kinds of color pigments were dispersed were formed on the original coating plate. did. Using a spectrophotometer (CD-3700d: manufactured by Minolta Co., Ltd.), the JI
The color tone was measured according to the color difference display method specified in SZ8737. FIG. 4 shows the results of the investigation. In FIG. 4, the horizontal axis indicates the sample number. As can be seen from the investigation results in FIG. 4, in the clear coated metal plates 1, 5, and 9 according to the present invention, the intermingling of interference colors is suppressed, and the whitening of the mixed color pigments Pr and Pg is suppressed without whitening. It can be seen that a clear coating film having a high color tone while maintaining the color tone is formed. On the other hand, in Comparative Examples 4, 8, and 12 in which two color pigments Pr and Pg were blended into a single-layer clear coating film, an increase in L value and a decrease in a value and b value were detected, and intermingling of interference colors was detected. , Resulting in achromatic coloration. [0020] As described above, the clear coated metal plate of the present invention has a plurality of clear coatings having different refractive indices laminated on a metal substrate, and the color tone of each clear coating is different. The coloring pigment is dispersed. In this way, by using different coloring pigments according to the refractive index of the clear coating film, the interference of interference colors and, consequently, the increase in whiteness are suppressed, and the advantages of coloring pigments that exhibit a clear color tone are effectively utilized. The formed clear coating film is formed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a surface portion of a clear coated metal plate in which a coloring pigment which emits an interference color having a different hue is mixed in a clear coating film. FIG. 3 is a schematic view showing a surface portion of a clear coated metal plate in which color pigments emitting interference colors having different hues are dispersed. FIG. 3 is an explanatory view of a mechanism in which interference colors are developed. FIG. 4 is a layer configuration and a color pigment of a clear coating film. Showing the effect of the dispersion form of color on the color tone [Description of References] S: Metal substrate C, C ₁ , C ₂ : Clear coating film Pr,
Pg: color pigment F: scale-like inorganic substrates M: metal oxide film t: thickness Lin metal oxide film: the incident light L _1, L _2: interference color [Delta] L: optical path difference

────────────────────────────────────────────────── ─── Continued on the front page (72) Koji Mori, Inventor 7-1, Takayashinmachi, Ichikawa-shi, Chiba Nisshin Steel Co., Ltd. Technical Research Institute (56) References JP-A-9-24578 (JP, A) JP-A-9-193279 (JP, A) JP-A-5-8342 (JP, A) JP-A-2001-121642 (JP, A) JP-A-2000-135772 (JP, A) JP-A-5-137849 (JP, A) A) JP-A-2000-25188 (JP, A) JP-A-2002-36450 (JP, A) JP-A-7-111946 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 C09D 1/00-201/10 C09C 1/00-3/12 B05D 1/00-7/26

Claims (1)

(57) [Claims 1] A plurality of clear coatings provided on the surface of a metal substrate and having different refractive indices have different hues for each of the clear coatings, and the scale-like inorganic substrate is transparent or transparent. A clear-painted metal plate exhibiting a vivid color tone, characterized in that color pigments coated with a translucent metal oxide are dispersed.