Stacked coating film and coated article

Abstract

To provide a laminated coating film that shows a red color by a brilliant layer and a coloring layer having light transmissivity, which achieves a metallic color that improves FF property and has high designability.SOLUTION: A laminated coating film 12 has a brilliant layer 14 containing a brilliant material 21, and a coloring layer 15 that contains a red pigment 25 and has light transmissivity, in the brilliant layer 14, when Y value of an XYZ colorimetric system of reflected light measured at a light incident angle of 45° and a light-receiving angle of 5° is represented by Y(5°), and a Y value of reflected light measured at the light-receiving angle of 15° is represented by Y(15°), Y(5°) is 30 or more and 700 or less, Y(15°) is 0.01 times or more and 0.3 times or less the Y(5°), and concentration of the red coloring material in the coloring layer 15 is 1 mass% or more and 17 mass% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a laminated coating film including a colored layer (color clear layer) containing a pigment and having translucency on a luminescent layer (metallic base layer) containing a luminescent material, and a coated article including the laminated coating film.

Background Art

[0002] In recent years, for coated articles that require high design quality such as automobiles, it has been desired to obtain a coating color with high chroma of highlights and strong depth.

[0003] Patent Document 1 describes a laminated sheet for molding useful for automobile-related members and the like, and obtaining a design with a sense of depth. It is a laminated sheet in which a colored layer is stacked on a metallic gloss layer, and the lightness L of the transmitted light of the colored layer is 20 to 80, the gloss value of the metallic gloss layer is 200 or more, and the chroma C of the specularly reflected light at 45 degrees is 150 or more. The same document also describes adding aluminum flakes to the metallic gloss layer and adopting perylene red as the pigment of the colored layer. * is set to 20 to 80, the gloss value of the metallic gloss layer is set to 200 or more, and the chroma C of the specularly reflected light at 45 degrees * is set to 150 or more. The same document also describes adding aluminum flakes to the metallic gloss layer and adopting perylene red as the pigment of the colored layer.

[0004] Patent Document 2 describes realizing a metallic color with high FF property and high design quality by improving the FF property in a laminated coating film in which a warm color is produced by a luminescent layer containing a luminescent material formed directly or indirectly on the surface of a coated article and a colored layer containing a warm color pigment and having translucency stacked on the luminescent layer. In the above laminated coating film, with respect to the Y value calibrated with a standard white plate in the XYZ color system of the luminescent layer, when the incident angle of light is 45°, the Y value of the reflected light measured at a light receiving angle of 10° is Y(10°), and the Y value of the reflected light measured at a light receiving angle of 25° is Y(25°), Y(10°) is 50 or more and 950 or less, Y(25°)=k×Y(10°) (where k is a coefficient), k is 0.05 or more and 0.35 or less, and the warm color pigment concentration C of the colored layer is 1% by mass or more and 17% by mass or less.

[0005] Patent Document 3 describes a multi-layer coating film forming method that can be applied to various industrial products, particularly the outer panels of automobiles. The method can obtain a coating film with high brightness and high chroma in the highlight (near specular reflection light), high chroma in the shade (oblique direction), a large difference in lightness between the highlight and the shade, and a uniform finished design. In this method, a first color clear coating film is formed on a metallic base coating film obtained by applying a metallic base paint containing a colored pigment and a flaky glitter pigment, and then a second color clear coating film is formed thereon. The colored pigments contained in the first and second color clear coating films are the same. Also, the concentration of the colored pigment per unit film thickness in the first and second color clear coating films is in the range of 30 / 70 to 60 / 35 as the ratio of the former to the latter.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] When a metallic coating is applied to a vehicle body or the like, a metallic texture is obtained because of the high flip-flop property (hereinafter referred to as "FF property") in which the lightness changes depending on the viewing angle of the coated object. That is, the stronger the contrast between light (highlight) and dark (shade), the higher the FF property and the better the metallic texture. This FF property is often represented by the FI (flop index) value, which is a metallic feeling index of X-Rite. However, conventionally, the FI value actually obtained with metallic coatings is generally around 18, and a spectacularly high metallic texture has not been achieved.

[0008] To put it simply, the above FI value represents the intensity of brightness in the highlight (near the specular reflection direction) relative to the brightness in the shade. Therefore, when the brightness of the highlight is low, the FI value also becomes small. On the other hand, if the amount of the brightening agent is increased to enhance the brightness in the highlight, the diffuse reflection by the brightening agent also increases. As a result, the brightness in the shade also increases simultaneously, and a remarkable FF property cannot be obtained.

[0009] An object of the present disclosure is to improve the FF property and realize a metallic color with high design quality in a laminated coating film that produces a red color by a brightening layer and a colored layer having translucency.

Means for Solving the Problem

[0010] In order to solve the above problems, the present disclosure focused on the relationship between the reflection characteristics of the brightening layer and the concentration of the red coloring material in the colored layer.

[0011] The laminated coating film disclosed herein includes a brightening layer containing a brightening agent formed directly or indirectly on the surface of an object to be coated, and a colorant and a colored layer containing a red coloring material and having translucency, which is laminated on the brightening layer. The above-mentioned bright layer contains aluminum flakes as the above-mentioned brightening material. The colorant contained in the above-mentioned bright layer consists of a black-based colorant. The black-based colorant contained in the above-mentioned bright layer is carbon black. The concentration of the carbon black in the above-mentioned bright layer is 1% by mass or more and 20% by mass or less. Regarding the Y value calibrated with a standard white plate in the XYZ color system, for the brightening layer, when the incident angle of light (the angle from the perpendicular to the surface of the brightening layer) is 45°, the Y value of the reflected light measured at a light receiving angle (the inclination angle from the specular reflection direction to the light source side) of 5° is defined as Y(5°), and the Y value of the reflected light measured at a light receiving angle of 15° is defined as Y(15°), Y(5°) is 30 or more and 700 or less, Y(15°) = k × Y(5°) (where k is a coefficient), k is 0.01 or more and 0.3 or less, and the concentration of the red coloring material in the colored layer is 1 mass% or more and 17 mass% or less. and the above-mentioned red-based colorant is a red-based pigment, and the average particle size of the above-mentioned red-based pigment is 2 nm or more and 160 nm or less. It is characterized by the above.

[0012] In a laminated coating film that produces a red color with a light-emitting layer and a colored layer having translucency, the reflected light from the light-emitting material contained in the light-emitting layer passes through the colored layer, thereby vividly developing the coloring material (pigment and / or dye) contained in the colored layer. The higher the lightness in the highlight and the lower the lightness in the shade, the more vivid the red color development in the highlight can be obtained, and sufficient darkness of the shade can be obtained. Therefore, the FF property is increased, and a metallic color with high design quality can be realized.

[0013] Here, the Y value in the XYZ color system is a stimulus value representing lightness (visual reflectance). Y(5°) is an index of the luminance feeling of the highlight. Y(15°) is an index of whether the hue by the red coloring material clearly appears at an observation angle slightly deviated from the highlight direction. When Y(5°) is 30 or more and 700 or less, and k in Y(15°) = k × Y(5°) is 0.01 or more and 0.3 or less, the coloring material of the colored layer is vividly colored by the reflected light from the light-emitting layer, the hue by the coloring material clearly appears, and the FF property is also increased.

[0014] However, it is difficult to sufficiently increase the FI value only by setting the reflection characteristics of the light-emitting layer as described above. When the amount of the light-emitting material is increased to increase the lightness in the highlight, the amount of light in the shade direction increases due to the diffuse reflection (scattering reflection) of the incident light generated at the fine irregularities and edges on the surface of the light-emitting material, so the lightness of the shade also increases.

[0015] Therefore, the present disclosure combines the reflection characteristics of the light-emitting layer and the transmission characteristics of the colored layer in order to achieve a high FI value. That is, an important feature of the present disclosure is that the high FI value of the laminated coating film is realized by the combination of the above-described reflection characteristics of the light-emitting layer and the transmission characteristics of the colored layer.

[0016] Specifically, the light transmission characteristics of the colored layer vary depending on the concentration of the colorant in the colored layer. When the concentration of the red-based colorant in the colored layer is low, the color development of the red-based hue becomes insufficient. Also, when the concentration of the colorant is low, the reflected light from the light-emitting layer, particularly the light due to diffuse reflection, is not significantly attenuated when passing through the colored layer, and the lightness of the shade increases, resulting in a decrease in the FI value. On the other hand, when the colorant concentration is 1% by mass or more, sufficient color development of the red-based hue can be ensured, and the light due to diffuse reflection is sufficiently absorbed by the colorant when passing through the colored layer, so the lightness of the shade decreases and the FI value increases. However, when the colorant concentration becomes excessively high, the effect of the colorant absorbing and / or shielding the reflected light from the light-emitting layer becomes large, and the lightness of the highlight decreases, resulting in a decrease in the FI value. Also, when the colorant is a pigment, light scattering by the pigment particles also causes an increase in the lightness of the shade and, consequently, a decrease in the FI value. Therefore, the upper limit of the colorant concentration is preferably 17% by mass.

[0017] In addition, Y(5°) is preferably 150 or more and 500 or less, more preferably 200 or more and 400 or less, and particularly preferably 200 or more and 300 or less. Also, k is preferably 0.03 or more and 0.2 or less, more preferably 0.05 or more and 0.15 or less. Furthermore, the concentration of the red-based colorant is preferably 4% by mass or more and 10% by mass or less, more preferably 5% by mass or more and 9% by mass or less, and particularly preferably 5% by mass or more and 7% by mass or less.

[0018] on The light-emitting layer uses, as the above-mentioned light-emitting material, contains aluminum flakes. Preferably, the above-mentioned aluminum flakes having an average particle diameter of 5 μm or more and 30 μm or less and an average thickness of 10 nm or more and 500 nm or less ri and the concentration of the aluminum flakes in the light-emitting layer is 1% by mass or more and 17% by mass or less.

[0019] Since such aluminum flakes have a visible light reflectance of about 90% or more, sufficient light quantity in the highlight direction can be ensured, and sufficient brightness of the highlight can be obtained. In particular, the diffuse reflection at the edge of the aluminum flakes becomes stronger as the thickness of the flakes increases. By reducing the thickness of the aluminum flakes as described above, the intensity of the diffuse reflection can be weakened. Thus, the brightness of the shade can be reduced.

[0020] Also, when the concentration of the aluminum flakes is less than 1% by mass, the amount of reflected light by the aluminum flakes is insufficient, and sufficient brightness of the highlight cannot be obtained. When the concentration of the aluminum flakes exceeds 17% by mass, the influence of diffuse reflection due to the fine irregularities and edges on the surface of the aluminum flakes becomes large, and the brightness of the shade becomes too high. By setting the concentration of the aluminum flakes within the above range, high FI can be achieved while ensuring sufficient darkness of the shade. The concentration of the above aluminum flakes is preferably 5% by mass or more and 12% by mass or less.

[0021] Preferably, the surface roughness Ra of the above aluminum flakes is 50 nm or less.

[0022] Diffuse reflection due to fine irregularities on the surface of the aluminum flakes causes an increase in the brightness of the shade. By setting the surface roughness Ra of the aluminum flakes within the above range, the diffuse reflection can be reduced, so that the brightness of the shade can be reduced.

[0023] Examples of the red coloring material for the coloring layer include red pigments with excellent weather resistance and / or red dyes with excellent transparency. From the viewpoint of ensuring sufficient weather resistance of the laminated coating film, a red pigment can preferably be adopted.

[0024] As the above red pigment, organic pigments such as perylene red, dibromoanthraslone red, azo red, anthraquinone red, quinacridone red, and diketopyrrolopyrrole can preferably be used.

[0025] on The said coloring layer contains a red pigment as the said red coloring material do. Preferably, The spectral transmittance spectrum of the colored layer in absolute value representation obtained by dividing the spectral reflectance measured at a light incident angle of 45° and a light receiving angle of 15° in the state where the colored layer is laminated on the phosphorescent layer by the spectral reflectance measured at a light incident angle of 45° and a light receiving angle of 15° in the state where the colored layer is removed and the surface of the phosphorescent layer is exposed has a tangent slope at 620 nm of 0.02 nm -1 or more and 0.06 nm -1 or less.

[0026] Here, the inventors of the present application have found that the tangent slope of the spectral transmittance spectrum at 620 nm is in a proportional relationship with the chroma C * . The higher the chroma C * , the better the red color development. When the tangent slope is 0.02 nm -1 or more and 0.06 nm -1 or less, a sufficient chroma C * can be obtained, so that a vivid red color development with less turbidity and high transparency can be obtained.

[0027] Note that the light receiving angle for measuring the spectral reflectance to obtain the spectral transmittance spectrum of the colored layer is set to 15° at which the red hue is distinct. In the case of a red coloring material, since the spectral reflectance rises in the wavelength range of 590 nm to 650 nm, the tangent slope of the spectrum at the median value 620 nm of that wavelength range is used. The tangent slope of the spectral transmittance spectrum is preferably 0.03 nm -1 or more and 0.06 nm -1 or less.

[0028] According to this configuration, the transmission characteristics of the colored layer and the reflection characteristics of the phosphorescent layer cooperate, and in the highlight, red vividly emits with a transparent feeling and brightly, and the red color of the highlight becomes more prominent due to the decrease in brightness on the shade side. Thus, it is advantageous for realizing a highly designed metallic color.

[0029] in this configuration The average particle diameter of the red pigment is 2 nm or more and 160 nm or less.

[0030] Since the average particle diameter of the red pigment particles (in this specification, the "average particle diameter of the pigment particles" may be referred to as the "pigment particle diameter") is 160 nm or less, there is no geometric optical scattering or Mie scattering by the pigment particles, and since it is 2 nm or more, Rayleigh scattering is also avoided, which is advantageous for a clear and vivid red color with a sense of transparency. Also, due to the small pigment particle diameter, at the same pigment concentration, compared to the case where the pigment particle diameter is large, when light passes through the colored layer, the frequency of hitting and being absorbed by the pigment particles is higher, and thus the attenuation of light becomes larger. When the attenuation of light becomes larger, the amount of light passing through the colored layer decreases, and the overall lightness decreases. However, since the amount of light in the highlight direction is originally large, the influence of light attenuation on lightness is small. On the other hand, since the amount of light in the shade direction is originally small, the influence of light attenuation on lightness becomes large. Thus, by reducing the diameter of the above-mentioned pigment particles, high FI can be achieved, which is advantageous for obtaining a high metallic texture. The average particle diameter of the red pigment is more preferably 2 nm or more and 30 nm or less.

[0031] All the colorants contained in the above-mentioned colored layer may be the above-mentioned red-based colorant, or the above-mentioned red-based colorant and black-based colorant. Preferably, the colored layer further contains a black coloring material.

[0032] According to this configuration, when the reflected light from the brightening material of the brightening layer passes through the colored layer, the reflected light is absorbed by the black coloring material over the entire wavelength range. Since the amount of light in the shade direction is small, when absorbed by the black coloring material, the amount of reflected light passing through the colored layer is greatly reduced. On the other hand, since the amount of reflected light in the highlight is large, even if a part of it is absorbed by the black coloring material, the amount of reflected light passing through the colored layer is sufficiently ensured. Thus, the coated article provided with the laminated coating film appears pitch black in the shade, while the red color appears vivid in the highlight, and a more highly designed metallic color is achieved.

[0033] Preferably, the concentration of the black coloring material in the colored layer is 6% by mass or less.

[0034] If the concentration of the black-based colorant becomes too high, the amount of absorbed reflected light increases, so the blackness of the highlight excessively increases and the red color development in the highlight becomes cloudy. According to this configuration, by setting the concentration of the black-based colorant within the above range, an excessive increase in the blackness in the highlight can be suppressed and the cloudiness of the red color development can be suppressed. Thus, a vivid red color development in the highlight can be obtained.

[0035] Preferably, the ratio of the black-based colorant to the total of the red-based colorant and the black-based colorant in the coloring layer is 26% by mass or less.

[0036] Even when the ratio of the black-based colorant in the colorant increases too much, the blackness of the highlight excessively increases, which causes the red color development in the highlight to become cloudy. According to this configuration, since an excessive increase in the blackness in the highlight can be suppressed and the cloudiness of the red color development can be suppressed, it is advantageous for obtaining a vivid red color development in the highlight.

[0037] Examples of the coated article provided with the above laminated coating film on the object to be coated include an automobile body, and may also be a body of a motorcycle or other vehicle, or other metal products or plastic products.

[0038] Also, the laminated coating film and the coated article of the present disclosure may have the following configurations.

[0039] In this configuration, The above brightening layer contains a colorant, and the colorant black-based colorant consists of .

[0040] When light diffusely reflected on the fine irregularities, edges, and base (e.g., electrodeposition coating film) on the surface of the brightening material passes through the coloring layer, the amount of light in the shade direction increases and the lightness of the shade becomes higher. When the lightness of the shade increases, the whiteness of the shade increases, which causes the red color development in the highlight to become blurred.

[0041] In this configuration, since the luminous layer contains a black coloring material, in the luminous layer, most of the incident light passing through the gaps between the luminescent materials is absorbed and / or shielded by the black coloring material, so that almost no light is reflected by the substrate. Further, since the light diffusely reflected by the minute irregularities and edges on the surface of the luminescent material is absorbed and / or shielded by the black coloring material, the lightness of the shade is reduced.

[0042] Examples of the black coloring material contained in the luminous layer include black pigments having excellent weather resistance and / or black dyes having excellent transparency. From the viewpoint of ensuring sufficient weather resistance of the laminated coating film, a black pigment can be adopted. As the black pigment, for example, carbon black, chromium oxide, iron oxide, manganese oxide, black indigoid pigment, etc. can be used.

[0043] In this configuration, When the black coloring material contained in the luminous layer is carbon black ri the concentration of the carbon black in the luminous layer is 1% by mass or more and 20% by mass or less. is.

[0044] If the concentration of carbon black is too low, there is a risk that its light absorption function and hiding power cannot be sufficiently obtained. On the other hand, if the concentration of carbon black is too high, the structure formed by the aggregation of primary particles is likely to be mechanically entangled, and light scattering increases, so that transparency decreases and the lightness of the shade may increase. Therefore, setting the concentration of carbon black in the luminous layer within the above range is advantageous for reducing the lightness of the shade.

[0045] The average particle size of the carbon black is preferably 200 nm or less.

[0046] According to this configuration, since the average particle size of carbon black is equal to or less than half the wavelength of the lower limit of visible light (wavelength 400 nm), light scattering by the carbon black particles can be suppressed.

[0047] The above-mentioned light-emitting layer may contain a colorant other than the above-mentioned black-based colorant, such as a red-based colorant, as the colorant. Thereby, light scattering is suppressed. Note that In this configuration, From the viewpoint of increasing the FI, the above-mentioned bright layer only the black-based colorant is contained as the colorant is.

[0048] When the above-mentioned light-emitting layer has an incident angle of light (angle from the perpendicular to the surface of the light-emitting layer) of 45°, and the brightness index L of the reflected light measured at the light-receiving angle (tilt angle from the specular reflection direction toward the light source side) θ is L * value is L * (θ), it is preferable that L * (θ) is 10 or less at 45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110°.

[0049] Thereby, by making the brightness in the shade direction (45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110°) 10 or less, sufficient shade darkness can be ensured. Note that the above-mentioned L * (θ) at 45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110° is preferably 5 or less. In particular, the above-mentioned L * (θ) at 45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110° is preferably 10 or less when the light-emitting layer contains a black-based colorant and a red-based colorant, and is preferably 5 or less when the light-emitting layer contains only the black-based colorant.

[0050] When the above-mentioned light-emitting material is projected onto the bottom surface of the above-mentioned light-emitting layer, it is preferable that the ratio of the projected area of the above-mentioned light-emitting material occupying the bottom surface is 3% or more and 70% or less per unit area.

[0051] If the ratio of the projected area of the brightening material is less than the lower limit value, the amount of reflected light from the brightening material is insufficient, and sufficient brightness of the highlight cannot be obtained. On the other hand, when the ratio of the projected area of the brightening material exceeds the upper limit value, since the amount of the brightening material contained in the brightening layer is large, the influence of diffuse reflection due to fine irregularities or edges on the surface of the brightening material becomes large, and the brightness of the shade becomes too high. By setting the ratio of the projected area of the brightening material within the above range, high FI can be achieved while ensuring sufficient darkness of the shade. The ratio of the area of the brightening material is preferably 20% or more and 50% or less per unit area.

[0052] It is preferable that the above-mentioned brightening layer has a spectral reflectance of 0.02 or less in absolute value with respect to a standard white plate in the wavelength range of 450 nm to 700 nm measured at a light receiving angle of 45° and 110° with a light incident angle of 45°.

[0053] Thereby, sufficient darkness of the shade can be obtained. In particular, when the brightening layer contains a black-based colorant and a red-based colorant, the spectral reflectance is preferably 0.02 or less, and when the brightening layer contains only a black-based colorant, the spectral reflectance is preferably 0.01 or less.

[0054] It is preferable that a transparent clear layer is directly laminated on the above-mentioned brightening layer. Acid resistance and scratch resistance can be obtained by the transparent clear layer.

Advantages of the Invention

[0055] According to the present disclosure, in the brightening layer, Y(5°) is 30 or more and 700 or less, Y(15°) is 0.01 times or more and 0.3 times or less of Y(5°), and the concentration of the red-based colorant in the coloring layer is 1% by mass or more and 17% by mass or less. Therefore, due to the combination of the reflection characteristics of the brightening layer and the transmission characteristics of the coloring layer, the reflected light from the brightening layer vividly develops the red color of the coloring layer near the highlight, while the high FI of the laminated coating film can be achieved, which is advantageous for realizing a metallic color with high design properties that highly combines vividness and depth.

Brief Description of the Drawings

[0056]

Figure 1

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Mode for Carrying Out the Invention

[0057] Hereinafter, embodiments for carrying out the present disclosure will be described based on the drawings. The following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0058] <Configuration Example of Laminated Coating Film> As shown in FIG. 1, the vehicle body 11 (coated object) of the automobile of the present embodiment includes a laminated coating film 12 provided on the surface of a steel plate 11A (object to be coated) via an electrodeposition coating film 13. The laminated coating film 12 is formed by sequentially laminating a gloss layer 14, a colored layer 15 having translucency, and a transparent clear layer 16. The electrodeposition coating film 13 is formed on the surface of the steel plate 11A by cationic electrodeposition coating in advance.

[0059] The gloss layer 14 contains a resin component as a base material, a brightening material 21, and a first black pigment 23 as a black coloring material. The colored layer 15 contains a resin component as a base material, a red pigment 25 as a red coloring material, and a second black pigment 27 as a black coloring material.

[0060] As the resin component of the gloss layer 14 and the colored layer 15, although not intended to be limiting, for example, an acrylic resin, a polyester resin, a urethane resin, a melamine resin, etc. can be adopted alone or in combination of multiple types. As the resin component of the transparent clear layer 16, for example, a carboxylic acid group-containing acrylic resin, a combination of a polyester resin and an epoxy-containing acrylic resin, a combination of an acrylic resin and / or a polyester resin and a polyisocyanate, etc. can be adopted.

[0061] The gloss layer 14 and the colored layer 15 may contain additives such as an ultraviolet shielding material, a viscous material, a thickening material, a pigment dispersant, a surface conditioner, etc. as necessary. In particular, from the viewpoint of the light resistance of the laminated coating film 12, it is desirable to contain an ultraviolet shielding material. As the ultraviolet shielding material, an organic compound-based ultraviolet absorber, an inorganic compound-based ultraviolet scattering agent, etc. can be adopted, and among them, it is preferable to adopt nanoparticles of a metal oxide such as iron oxide.

[0062] The film thickness of the gloss layer 14 is preferably 6 μm or more and 15 μm or less, more preferably 7 μm or more and 13 μm or less, and the film thickness of the colored layer 15 is preferably 8 μm or more and 15 μm or less.

[0063] The surface roughness Ra of the electrodeposited film 13 is preferably 2.0 μm or less, more preferably 1.0 μm or less. Thereby, the orientation of the brightening material 21 of the brightening layer 14 is improved.

[0064] <Brightening layer> [Brightening material] As the brightening material 21 contained in the brightening layer 14, a metal flake or the like having a high visible light reflectance can be adopted. In this embodiment, aluminum flakes are adopted as the brightening material 21.

[0065] From the viewpoint of obtaining sufficient brightness of the highlight, the aluminum flakes preferably have a visible light reflectance of 90% or more. Thereby, a sufficient amount of light in the highlight direction can be ensured, and sufficient brightness of the highlight can be obtained.

[0066] Specifically, as such aluminum flakes, those having an average particle size of 5 μm or more and 30 μm or less, preferably 10 μm or more and 15 μm or less, and an average thickness of 10 nm or more and 500 nm or less are preferably adopted. In particular, the average thickness is preferably 10 nm or more and 50 nm or less in the case of vapor-deposited aluminum flakes, and 100 nm or more and 500 nm or less in the case of thin-film aluminum flakes.

[0067] In this specification, the average particle size of the brightening material 21 and various coloring pigments is obtained by determining D50, which is the 50% value of the particle size distribution measured by, for example, a laser diffraction particle size distribution measuring device.

[0068] The average thickness of the brightening material 21 is obtained, for example, by observing with a scanning electron microscope, measuring the thicknesses of a plurality of (for example, 50) brightening materials 21, and calculating the average value thereof.

[0069] If the average particle size is too small, the reflection characteristics may deteriorate. If the average particle size is too large, although the reflection characteristics are excellent, the particle feeling of the appearance may become too strong. In addition, the diffuse reflection at the edges of the aluminum flakes becomes stronger as the thickness of the flakes increases. As described above, since the thickness is thin, the diffuse reflection is weak. Therefore, it is advantageous for reducing the lightness of the shade.

[0070] In addition, the aspect ratio (average particle size / average thickness) of the aluminum flakes is preferably 30 or more and 300 or less.

[0071] Further, the aluminum flakes preferably have a surface roughness Ra of 50 nm or less. In particular, in the case of vapor-deposited aluminum flakes, the surface roughness Ra is preferably 7 nm or less, and in the case of smooth aluminum flakes, the surface roughness Ra is preferably 50 nm or less. Thereby, the diffuse reflection due to the fine irregularities on the surface of the aluminum flakes can be reduced, and the lightness of the shade can be reduced.

[0072] In addition, the brightening material 21 is oriented so as to be substantially parallel to the surface of the brightening layer 14 (so that the average orientation angle of the brightening material 21 with respect to the surface of the brightening layer 14 is 1.2 degrees or less) in order to increase the lightness of the highlight. For example, after applying a paint containing the brightening material 21, the first black pigment 23, etc. on the electrodeposition coating film 13, the brightening material 21 is arranged so that the average orientation angle is 1.2 degrees or less by utilizing the volume shrinkage and thinning of the coating film due to the evaporation of the solvent during baking. The average orientation angle of the brightening material 21 is obtained by calculating the inclination of the brightening material 21 with respect to the surface of the brightening layer 14 in a plurality (for example, 50) of brightening materials 21 included in one field of view from the 3D shape data (xyz coordinates) of the surface of the brightening layer 14 measured using a laser microscope (manufactured by Keyence Corporation, VK-X1000) and averaging them.

[0073] There are two types of aluminum flakes, the leafing type and the non-leafing type, and either can be used, but it is preferable to use the non-leafing type of aluminum flakes.

[0074] Since the leafing type aluminum flakes have a low surface tension, when a paint containing the leafing type aluminum flakes is applied, the aluminum flakes float on the surface of the brightening layer 14 and are oriented parallel to the surface. When the aluminum flakes float on the surface of the brightening layer 14, the amount of reflected light increases and the FF property is enhanced, but a flat and strong gloss like specular reflection is obtained. Also, in the case of the leafing type aluminum flakes, due to the small surface area and the decrease in the amount of the resin component disposed on the surface of the brightening layer 14, etc., the adhesion between the brightening layer 14 and the coloring layer 15 decreases, and there is a problem that it becomes easy to peel off due to external factors such as chipping.

[0075] On the other hand, since the non - leafing type aluminum flakes have a high surface tension, when a paint containing the non - leafing type aluminum flakes is applied, as shown in FIG. 1 for example, the aluminum flakes are irregularly dispersed in the film thickness direction while being oriented parallel to the surface of the brightening layer 14. As a result, since the amount of reflected light changes corresponding to the position of the aluminum flakes in the film thickness direction, a three - dimensional metallic gloss can be obtained, and a more design - oriented metallic color can be obtained. Also, in the case of the non - leafing type aluminum flakes, since a sufficient amount of the resin component disposed on the surface of the brightening layer 14 can be ensured, sufficient adhesion between the brightening layer 14 and the coloring layer 15 can be ensured.

[0076] [Area ratio of the brightening material] The ratio of the projected area of the brightening material 21 on the bottom surface of the brightening layer 14 when the brightening material 21 is projected onto the bottom surface (also referred to as "area ratio" in this specification) is preferably 3% or more and 70% or less, more preferably 20% or more and 50% or less per unit area.

[0077] If the area ratio of the brightening material 21 is too small, the amount of reflected light by the brightening material 21 is insufficient, and sufficient brightness of the highlight cannot be obtained. On the other hand, if the area ratio of the brightening material 21 is too large, since the amount of the brightening material 21 is large, the influence of diffuse reflection due to the fine unevenness and edges on the surface of the brightening material 21 becomes large, the brightness of the shade increases, and the strength and weather resistance of the brightening layer 14 decrease. By setting the area ratio of the brightening material 21 within the above range, it is possible to achieve high FI while ensuring sufficient darkness of the shade, and to obtain sufficient strength and weather resistance.

[0078] The area ratio per unit area of the aluminum flakes can be obtained, for example, by magnifying and observing the brightening layer 14 from its surface with a microscope, calculating the area ratio of the aluminum flakes in a plurality of visual fields (for example, 10 visual fields) by image processing, and averaging them.

[0079] Specifically, FIG. 2 is a photograph taken of the brightening layer according to Production Example 1 shown in Table 1 from its surface side. In Production Example 1, aluminum flakes are used as the brightening material 21, carbon black is used as the first black pigment 23, and an acrylic resin, a urethane resin, and a melamine resin are used as the resin component. It is a coated plate formed by forming only the brightening layer 14 on the surface of the steel plate 11A via the electrodeposition coating film 13.

[0080]

Table 1

[0081] The whitish particles in FIG. 2 are aluminum flakes. From the figure, when the aluminum flakes are projected onto the bottom surface of the brightening layer 14, the area ratio of the aluminum flakes occupying the bottom surface can be calculated as 22.5% per unit area.

[0082] The area ratio of the brightening material 21 as described above can be achieved, for example, by setting the concentration of the brightening material 21 in the brightening layer 14 to preferably 1% by mass or more and 17% by mass or less, more preferably 5% by mass or more and 12% by mass or less. If the concentration of the brightening material 21 is less than 1% by mass, a sufficient area ratio of the brightening material 21 cannot be obtained. If the concentration of the brightening material 21 exceeds 17% by mass, the area ratio of the brightening material 21 becomes too large.

[0083] [First black pigment] Although the flaky brightening material 21 is effective in increasing the brightness of the highlight, there is diffuse reflection due to minute irregularities on the flake surface and diffuse reflection at the edges of the flakes. Furthermore, there is diffuse reflection at the base (electrodeposition coating film 13 in this embodiment). When the light diffusely reflected in this way passes through the colored layer 15, the amount of light in the shade direction increases and the brightness of the shade increases. When the brightness of the shade increases, the whiteness of the shade increases, which causes the red color development in the highlight to become blurred and the vividness to decrease. Therefore, it is desirable to contain the first black pigment 23 as a black coloring material in the brightening layer 14 and adjust the reflection characteristics of the shade by utilizing the light absorption function and hiding ability of the first black pigment 23.

[0084] Most of the incident light passing through the gaps between the brightening materials 21 is absorbed and / or shielded by the first black pigment 23, so that there is almost no diffuse reflection by the base (electrodeposition coating film 13). Then, the light diffusely reflected by the minute irregularities and edges of the brightening material 21 is absorbed and / or shielded by the first black pigment 23, thereby reducing the brightness of the shade.

[0085] As the first black pigment 23 contained in the bright layer 14, although not intended to be limiting, for example, carbon black with excellent weather resistance can be adopted. The concentration of the first black pigment 23 in the bright layer 14 is preferably 1% by mass or more and 20% by mass or less. If the concentration of carbon black is too low, there is a risk that its light absorption function and hiding power cannot be sufficiently obtained. On the other hand, if the concentration of carbon black is too high, the structures formed by the aggregation of primary particles are likely to be mechanically entangled, increasing light scattering, so the transparency decreases and the lightness of the shade may increase. Therefore, setting the concentration of carbon black in the bright layer 14 within the above range is advantageous for reducing the lightness of the shade.

[0086] The average particle size of carbon black is preferably 200 nm or less. Since the average particle size of carbon black is 1 / 2 wavelength or less of the lower limit of visible light (wavelength 400 nm), light scattering by carbon black particles can be suppressed. Thus, an increase in the lightness of the shade can be suppressed.

[0087] The bright layer 14 may contain a colorant of a color other than black, for example, a red colorant. Thereby, light scattering can be suppressed. From the viewpoint of increasing the FI value, it is desirable to contain only a black colorant as the colorant.

[0088] Also, for adjusting the light reflection characteristics, a black or other dark underlayer (absorbing layer) that absorbs light may be provided between the bright layer 14 and the electrodeposition coating film 13. That is, it is a method of absorbing the light transmitted through the gaps between the brightening materials 21 in the bright layer 14 with the dark underlayer. In the case of this method, coating of the dark underlayer is required, but it is possible to adjust the reflection characteristics.

[0089] <Reflection characteristics of the bright layer> [Y value] The Y value in the XYZ color system is Y among the tristimulus values X, Y, and Z defined by the following formula in the CIE XYZ color space (https: / / ja.wikipedia.org / wiki / CIE_1931_%E8%89%B2%E7%A9%BA%E9%96%93), and it is a stimulus value representing brightness (visual reflectance).

[0090]

Number

[0091] Note that x(λ), y(λ), and z(λ) (the superscript bar notation is omitted for each) are CIE color-matching functions, and Le, Ω, λ are the spectral radiance of color for a colorimetric observer.

[0092] Fig. 3 shows the method for measuring the Y value of the phosphorescent layer 14. The incident angle of the light source 41 with respect to the phosphorescent layer 14 is 45° (the inclination angle from the perpendicular to the surface of the phosphorescent layer 14). The light-receiving angle θ (the inclination angle from the specular reflection direction toward the light source side) by the sensor 42 sets the specular reflection direction as 0°. For the measurement, a three-dimensional variable-angle spectrocolorimeter system GCMS-4 manufactured by Murakami Color Research Laboratory Co., Ltd. was used.

[0093] In this embodiment, in order to increase the FI value, the reflection intensity Y(5°) at a light-receiving angle of 5° and the reduction rate k of the reflection intensity when the light-receiving angle changes from 5° to 15° are set so as to be within a predetermined range.

[0094] The reflection intensity Y(5°) at a light-receiving angle of 5° is an index of the luminance feeling of the highlight. Also, the reflection intensity Y(15°) at a light-receiving angle of 15° is an index of whether or not the hue by the red pigment 25 clearly appears at an observation angle slightly deviated from the highlight direction. The above reduction rate k is represented by the coefficient k in Y(15°) = k × Y(5°).

[0095] The Y(5°) of the light-emitting layer 14 is 30 or more and 700 or less, preferably 150 or more and 500 or less, more preferably 200 or more and 400 or less, and particularly preferably 200 or more and 300 or less. And the coefficient k is 0.01 or more and 0.3 or less, preferably 0.03 or more and 0.2 or less, more preferably 0.05 or more and 0.15 or less. By setting the reflection characteristics of the light-emitting layer 14 in this way, the red pigment 25 of the colored layer 15 can be vividly colored by the reflected light from the light-emitting layer 14. Thus, the hue due to the red pigment 25 appears clearly and the FF property also increases.

[0096] Specifically, FIG. 4 shows the relationship between the Y value calibrated with a standard white plate in the XYZ colorimetric system of the light-emitting layer 14 (Table 1) of the above-described Production Example 1 and the light-receiving angle. When the Y value of the reflected light measured at a light-receiving angle of 5° is Y(5°) and the Y value of the reflected light measured at a light-receiving angle of 15° is Y(15°), in the example of FIG. 4, Y(5°) = 236 and Y(15°) = 13.1.

[0097] [L * value] L * value is the * L * a * b * lightness index of the colorimetric system. The L * value can be measured in the same manner as the Y value.

[0098] As shown in FIG. 3, for the light-emitting layer 14, with the light incident angle being 45°, the lightness index L * (θ) of the reflected light measured at the light-receiving angle θ is defined. At this time, in the present embodiment, L * (θ) at 45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110° is 10 or less, preferably 5 or less. Note that since the reflected light overlaps with the incident light at a light-receiving angle of 90°, measurement is difficult. Therefore, measurement is not performed in the region of 80° < θ < 100°. By setting the lightness in the shade direction (45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110°) to 10 or less, preferably 5 or less, sufficient shade darkness can be ensured.

[0099] Specifically, FIG. 5 is a graph showing the relationship between the L value of the phosphorescent layer 14 of Production Example 1 and the light reception angle θ. As shown in FIG. 5, when the light reception angle is 45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110°, the L value is 5 or less. * As shown in FIG. 5, when the light reception angle is 45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110°, the L value is 5 or less. * Specifically, FIG. 5 is a graph showing the relationship between the L value of the phosphorescent layer 14 of Production Example 1 and the light reception angle θ. As shown in FIG. 5, when the light reception angle is 45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110°, the L value is 5 or less.

[0100] Note that the above L(θ) in the range of 45° ≤ θ ≤ 80° and 100° ≤ θ ≤ 110° only needs to satisfy the condition of being 10 or less when the phosphorescent layer 14 contains a red colorant in addition to the first black pigment 23. * (θ) only needs to satisfy the condition of being 10 or less when the phosphorescent layer 14 contains a red colorant in addition to the first black pigment 23.

[0101] [Spectral reflectance] The spectral reflectance indicates the wavelength dependence of the reflectance. The spectral reflectance of the phosphorescent layer 14 can be measured in the same manner as the Y value and the L value. * The spectral reflectance of the phosphorescent layer 14 can be measured in the same manner as the Y value and the L value.

[0102] In the present embodiment, for the phosphorescent layer 14, the spectral reflectance with respect to the standard white plate in the wavelength range of 450 nm to 700 nm measured with the light incident angle of 45° and the light reception angles θ of 45° and 110° (representative shade directions) is 0.02 or less, preferably 0.01 or less, in absolute value display.

[0103] Specifically, FIG. 6 is a graph showing the relationship between the above spectral reflectance of the phosphorescent layer 14 of Production Example 1 and the wavelength. As shown in FIG. 6, at the light reception angles of 45° and 110°, the spectral reflectance in the wavelength range of 450 nm to 700 nm is 0.01 or less. Thereby, sufficient darkness of the shade can be obtained.

[0104] Note that the above spectral reflectance only needs to be 0.02 or less when the phosphorescent layer 14 contains a red colorant in addition to the first black pigment 23.

[0105] [Coloring layer] [Red pigment] As the red pigment 25, for example, organic pigments such as perylene red, dibromoanthraslone red, azo red, anthraquinone red, quinacridone red, diketopyrrolopyrrole can be used, and it is particularly preferable to use perylene red which is excellent in weather resistance.

[0106] Details will be described later, but the average particle size of the red pigment 25 is preferably 2 nm or more and 160 nm or less, more preferably 2 nm or more and 30 nm or less.

[0107] Since the average particle size of the red pigment is 160 nm or less, there is no geometric optical scattering or Mie scattering by the pigment particles, and since it is 2 nm or more, Rayleigh scattering is also avoided, which is advantageous for a transparent and vivid red color development. Also, due to the small average particle size, at the same pigment concentration, compared to the case where the pigment particle size is large, when light passes through the colored layer, the frequency of hitting and being absorbed by the pigment particles is higher, and thus the light attenuation becomes larger. When the light attenuation becomes larger, the amount of light passing through the colored layer 15 decreases, and the overall brightness decreases. However, since the amount of light in the highlight direction is originally large, the influence of light attenuation on the brightness is small. On the other hand, since the amount of light in the shade direction is originally small, the influence of light attenuation on the brightness becomes large. Thus, by reducing the diameter of the pigment particles, high FI can be achieved, which is advantageous for obtaining a high metallic texture.

[0108] The concentration of the red pigment 25 in the colored layer 15 is 1 mass% or more and 17 mass% or less, preferably 4 mass% or more and 10 mass% or less, more preferably 5 mass% or more and 9 mass% or less, and particularly preferably 5 mass% or more and 7 mass% or less.

[0109] If the concentration of the red pigment 25 in the colored layer 15 is less than 1 mass%, sufficient color development of red in the highlight cannot be obtained. Also, if the concentration of the red pigment 25 exceeds 17 mass%, the absorption and / or shielding effect of the reflected light by the pigment particles becomes large, the brightness of the highlight decreases, and due to the light scattering effect by the pigment particles, the brightness of the shade increases, so the FI value decreases.

[0110] [Second black pigment] Since the colored layer 15 contains the second black pigment 27, when the reflected light from the light-emitting material 21 of the light-emitting layer 14 passes through the colored layer 15, the reflected light is absorbed by the second black pigment 27 over the entire wavelength range. Since the shade direction has less light quantity, when absorbed by the second black pigment 27, the light quantity of the reflected light passing through the colored layer 15 is greatly reduced. On the other hand, since the reflected light of the highlight has a large light quantity, even if a part of it is absorbed by the second black pigment 27, the light quantity of the reflected light passing through the colored layer 15 is sufficiently ensured. Thus, the vehicle body 11 provided with the laminated coating film 12 appears jet black in the shade, while the red color appears vivid in the highlight, achieving a more highly designed metallic color.

[0111] As the second black pigment 27, although not intended to be limiting, for example, carbon black with excellent weather resistance can be adopted.

[0112] The average particle size of the carbon black is preferably 20 nm or more and 160 nm or less. Since the average particle size of the carbon black is 1 / 2 wavelength or less of the lower limit of visible light (wavelength 400 nm), light scattering by the carbon black particles can be suppressed.

[0113] The concentration of the second black pigment 27 in the colored layer 15 is preferably 6% by mass or less. Also, the ratio of the second black pigment 27 to the total of the red pigment 25 and the second black pigment 27 in the colored layer 15 is preferably 26% by mass or less.

[0114] If the concentration of the second black pigment 27 and / or the ratio of the second black pigment 27 in the coloring material becomes too high, the absorption amount of the reflected light increases, so the blackness of the highlight excessively increases and the red color development in the highlight becomes turbid. By setting the concentration of the second black pigment 27 and / or the ratio of the second black pigment 27 in the coloring material within the above range, an excessive increase in the blackness in the highlight can be suppressed and the turbidity of the red color development can be suppressed. Thus, a vivid red color development in the highlight can be obtained.

[0115] [Entire coloring material] The total amount of all colorants contained in the coloring layer 15, that is, the total of the red pigment 25 and the optional second black pigment 27, is preferably 1% by mass or more and 23% by mass or less.

[0116] The transmission characteristics of the coloring layer 15 change depending on the concentration of the colorants contained in the coloring layer 15. In particular, when the concentration of all colorants in the coloring layer is low, the reflected light from the light-emitting layer, especially the light due to diffuse reflection, is not attenuated much when passing through the coloring layer, and the lightness of the shade increases, so the FI value decreases. On the other hand, when the concentration of all colorants becomes 1% by mass or more, the light due to diffuse reflection is sufficiently absorbed by the pigment particles when passing through the coloring layer 15, so the lightness of the shade decreases and the FI value increases. On the other hand, when the concentration of all colorants becomes excessively high, the effect of the pigment particles absorbing and / or shielding the reflected light from the light-emitting layer 14 becomes large and the lightness of the highlight decreases, so the FI value decreases. Also, since the scattering of light by the pigment particles also causes an increase in the lightness of the shade and thus a decrease in the FI value, the upper limit of the concentration of all colorants is preferably 23% by mass.

[0117] <Transmission characteristics of the coloring layer> [Spectral transmittance] The transmission characteristics of the coloring layer 15 are represented by, for example, its spectral transmittance. The spectral transmittance of the coloring layer 15 is a value obtained by dividing the spectral reflectance measured in the state where the coloring layer 15 is laminated on the light-emitting layer 14 by the spectral reflectance measured in the state where the coloring layer 15 is removed and the surface of the light-emitting layer 14 is exposed, and here it is expressed as an absolute value. The spectral reflectance measured in the state where the coloring layer 15 is laminated on the light-emitting layer 14 may be the coating film in the state where the coloring layer 15 is laminated on the light-emitting layer 14 in the method shown in FIG. 3.

[0118] When obtaining the spectral transmittance spectrum of the coloring layer 15, the incident angle in the measurement of each spectral reflectance is 45°, and the light-receiving angle is 15° at which the red hue clearly appears.

[0119] And in the case of the red colorant, since the spectral reflectance rises in the wavelength range of 590 nm to 650 nm, the slope of the tangent of the spectrum at the median value 620 nm of that wavelength range is set within a predetermined range.

[0120] That is, in the colored layer 15 of the present embodiment, the slope of the tangent line at 620 nm of the spectrum of the spectral transmittance is 0.02 nm -1 or more and 0.06 nm -1 or less, preferably 0.03 nm -1 or more and 0.06 nm -1 or less.

[0121] Specifically, FIG. 7 shows the spectrum of the spectral transmittance of the colored layer 15 in the coated plate of F (Example 3) shown in Table 2. For the measurement of the spectral reflectance, the variable-angle spectroscopic color measurement system GCMS-4 manufactured by the above-mentioned Murakami Color Research Laboratory was used. FIG. 7 is a spectral transmittance spectrum in the measurement wavelength range of 390 to 730 nm. The specifications of the laminated coating film 12 of the coated plate F (Example 3) and the slope of the tangent line at the wavelength of 620 nm of the spectrum are as shown in Table 2.

[0122]

Table 2

[0123] Next, as shown in Table 2, a plurality of coated plates A to E and G having the same configuration as the coated plate F (Example 3) were produced except that the pigment particle size of the colored layer 15 was variously changed, and the spectral transmittance spectra of each coated plate were measured. Then, the slope of the tangent line at 620 nm was obtained from the spectral transmittance spectrum as described above, and the XY and Z values in the XYZ color system were obtained using the equal-color function. XYZ was converted to L * a * b * and the chroma C * =√((a * ) 2 +(b * ) 2 ) was obtained.

[0124] According to the study of the present disclosure, as shown in FIG. 8, the chroma C * is proportional to the slope of the tangent line at the wavelength of 620 nm of the spectral transmittance spectrum. And at a slope of 0.02 nm -1 the chroma C * becomes approximately 50, and at a slope of 0.06 nm -1 the chroma C* becomes approximately 150. Therefore, the slope of the tangent line is 0.02 nm -1 or more, from the viewpoint of obtaining a vivid red color with less turbidity and high transparency, a sufficient chroma C * is considered to be obtained.

[0125] Also, as shown in FIG. 9, the slope of the above tangent line depends on the average particle diameter (pigment particle diameter) of the red pigment in the colored layer 15. Here, when the pigment particle diameter exceeds 160 nm, there is a risk that the transparency will decrease due to diffuse reflection by the pigment particles, that is, geometric optical scattering or Mie scattering, resulting in a color development with poor metallic luster. Also, when the pigment particle diameter is less than 2 nm, there is a risk of coloring purple due to Rayleigh scattering. According to FIGS. 8 and 9, when the slope of the above tangent line is 0.02 nm -1 or more and 0.06 nm -1 or less, preferably 0.03 nm -1 or more and 0.06 nm -1 or less, the average particle diameter of the pigment particles will be 2 nm or more and 160 nm or less, preferably 2 nm or more and 30 nm or less. Thus, both diffuse reflection by the pigment particles and Rayleigh scattering can be avoided, and a vivid red color development with less turbidity and high transparency can be obtained.

[0126] <Optical properties of the laminated coating film> [FI value] The FI value is an index of metallic feeling from X-Rite and represents FF property. As shown in FIG. 10, the FI value is the lightness index L of the reflected light (45° reflected light) with a light incident angle (angle from the perpendicular to the surface) of 45° with respect to the surface of the laminated coating film 12 and a light receiving angle (tilt angle from the specular reflection direction to the light source side) of 45° * 45°, the lightness index L of the reflected light (15° reflected light) with a light receiving angle of 15° * 15°, and the lightness index L of the reflected light (110° reflected light) with a light receiving angle of 110° * 110°, and is a value obtained by the following formula.

[0127] FI = 2.69×(L * 15° - L * 110°) 1.11 / L * 45° 0.86 The FI value is 20 or more, preferably 30 or more, more preferably 35 or more, and particularly preferably 40 or more, from the viewpoint of obtaining excellent vividness of red color development and excellent metallic texture in the laminated coating film 12.

[0128] [Combination of reflection characteristics of the bright layer and transmission characteristics of the colored layer] As described above, in the laminated coating film 12 according to the present embodiment, by combining the reflection characteristics of the bright layer 14 and the transmission characteristics of the colored layer 15, excellent color development of the red hue in the laminated coating film 12 and an increase in the FI value are realized.

[0129] That is, the reflection characteristics of the bright layer 14 and the transmission characteristics of the colored layer 15 cooperate with each other. In the highlight, red vividly emits light with a sense of transparency, while on the shade side, the brightness decreases, making the red in the highlight more prominent and obtaining a deep and high metallic texture. Thus, a highly designed metallic color that achieves both vividness and depth is realized.

[0130] [Examples] Coated plates provided with the laminated coating films (the base is an electrodeposition coating film) of Examples 1 to 17 and Comparative Examples 1 to 4 shown in Tables 3 to 5 were produced. Then, the area ratio per unit area of aluminum flakes, Y(5°), Y(15°), the slope of the tangent line of the spectral transmittance spectrum at a wavelength of 620 nm, and the FI value were examined. Also, the vividness of red color development and the strength of contrast were evaluated by an external appearance visual test. The external appearance visual test was a four-level evaluation of "◎", "○", "△", and "×". The evaluation of the vividness of red and the strength of contrast is such that "◎" is the highest, and it gradually decreases in the order of "○" → "△" → "×".

[0131]

Table 3

[0132]

Table 4

[0133]

Table 5

[0134] FIG. 11 is a graph showing the dependence of the FI value on Y(5°) and the concentration of the red pigment 25 in the colored layer 15 (pigment concentration) based on the results of Tables 3 and 4. However, k represented by Y(15°)=k×Y(5°) is 0.01 or more and 0.3 or less.

[0135] When the Y(5°) of the bright layer 14 is 30 or more and 700 or less, and the pigment concentration of the colored layer 15 is 1% by mass or more and 17% by mass or less, the FI value can be made 20 or more. Also, when Y(5°) is 150 or more and 500 or less, and the pigment concentration of the colored layer 15 is 4% by mass or more and 10% by mass or less, the FI value can be made 30 or more. When Y(5°) is 200 or more and 400 or less, and the pigment concentration of the colored layer 15 is 5% by mass or more and 9% by mass or less, the FI value can be made 35 or more. When Y(5°) is 200 or more and 300 or less, and the pigment concentration of the colored layer 15 is 5% by mass or more and 7% by mass or less, the FI value can be made 40 or more.

Explanation of Signs

[0136] 11 Vehicle body 11A Steel plate 12 Multilayer coating film 13 Electrodeposition coating film 14 Bright layer 15 Colored layer 16 Transparent clear layer 21 Bright material 23 First black pigment (black coloring material) 25 Red pigment (red coloring material) 27 Second black pigment (black coloring material)

Claims

1. It comprises a brightening layer containing a brightening material and a coloring material formed directly or indirectly on the surface of an object to be coated, and a colored layer containing a red-based coloring material and having translucency, which is superposed on the brightening layer. The brightening layer contains aluminum flakes as the brightening material. The coloring material contained in the brightening layer consists of a black-based coloring material. The black-based coloring material contained in the brightening layer is carbon black. The concentration of the carbon black in the brightening layer is 1% by mass or more and 20% by mass or less. With respect to the Y value calibrated with a standard white plate in the XYZ color system, for the brightening layer, when the incident angle of light (angle from the perpendicular to the surface of the brightening layer) is 45°, and the receiving angle (tilt angle from the specular reflection direction to the light source side) is 5°, the Y value of the reflected light measured is Y(5°), and when the receiving angle is 15°, the Y value of the reflected light measured is Y(15°). Y(5°) is 30 or more and 700 or less. Y(15°) = k × Y(5°) (where k is a coefficient), and k is 0.01 or more and 0.3 or less. The concentration of the red-based coloring material in the colored layer is 1% by mass or more and 17% by mass or less. The red-based coloring material is a red-based pigment. The laminated coating film is characterized in that the average particle diameter of the red-based pigment is 2 nm or more and 160 nm or less.

2. In Claim 1, The aluminum flakes have an average particle diameter of 5 μm or more and 30 μm or less, and an average thickness of 10 nm or more and 500 nm or less. The laminated coating film is characterized in that the concentration of the aluminum flakes in the brightening layer is 1% by mass or more and 17% by mass or less.

3. In Claim 2, The laminated coating film is characterized in that the surface roughness Ra of the aluminum flakes is 50 nm or less.

4. In any one of Claims 1 to 3, The laminated coating film is characterized in that the concentration of the red coloring material in the coloring layer is 4% by mass or more and 10% by mass or less.

5. In any one of Claims 1 to 4, The spectral transmittance spectrum of the coloring layer in absolute value representation obtained by dividing the spectral reflectance measured at a light incident angle of 45° and a light receiving angle of 15° with the coloring layer laminated on the bright layer by the spectral reflectance measured at a light incident angle of 45° and a light receiving angle of 15° with the surface of the bright layer exposed by removing the coloring layer has a tangent slope at 620 nm of －１ 0.02 nm or more －１ and 0.06 nm or less. The laminated coating film is characterized by this.

6. In Claim 5, the tangent slope is 0.03 nm －１ or more and 0.06 nm －１ or less. The laminated coating film is characterized by this.

7. In any one of Claims 1 to 6, All the coloring materials contained in the coloring layer are the red coloring material, or the red coloring material and the black coloring material. The laminated coating film is characterized by this.

8. In any one of Claims 1 to 6, the coloring layer further contains a black coloring material. The laminated coating film is characterized by this.

9. In Claim 8, the concentration of the black coloring material in the coloring layer is 6% by mass or less. The laminated coating film is characterized by this.

10. In Claim 8 or Claim 9, the ratio of the black coloring material to the total of the red coloring material and the black coloring material is 26% by mass or less. The laminated coating film is characterized by this.

11. A coated article comprising the laminated coating film according to any one of Claims 1 to 10.

Images