Laminated coating film and coated article

Abstract

The laminated coating film (12) comprises a bright layer (14) and a colored layer (15), the bright layer (14) contains a bright material (21), the colored layer (15) is laminated on the bright layer (14), and the colored layer (15) contains a colored layer red pigment (25) and has light transmittance. The laminated coating film satisfies the following formulae (1)-(3): 5 < = L * (theta) < = 25 (10 DEG < = theta < = 25 DEG)... (1) 20 < = C * (theta) < = 65 (10 DEG < = theta < = 25 DEG)... (2) 2 < = C * (80 DEG)... (3), where L * (theta) and C * (theta) are the lightness (L *) value and the chroma (C *) value of reflected light measured at a light receiving angle (theta), respectively.

Description

Technical Field

[0001] The present disclosure relates to a laminated coating film and a coated article having the laminated coating film. Background Art

[0002] In recent years, for coated articles such as automobiles that are required to have high design aesthetics, there has been a desire to obtain a colored coating with deep and vivid color development.

[0003] Patent Document 1 describes the following: Regarding a laminated film for molding useful for automotive-related components, etc., a design aesthetic with a sense of depth is obtained. Specifically, in a laminated film formed by laminating a colored layer on a metallic luster layer, the lightness L of the light transmitted through the colored layer is ＊ 20 to 80, the gloss value of the metallic luster layer is 200 or more, and the chroma C of the specular reflected light at 45 degrees is ＊ 150 or more. This document also describes the following: Aluminum flakes are added to the metallic luster layer, and perylene red is used as the pigment for the colored layer.

[0004] Patent Document 2 describes the following: Regarding a laminated coating film that uses a bright layer and a colored layer to exhibit a warm color system, the FF property is improved to achieve a metallic luster color with high design aesthetics. Among them, the bright layer is directly or indirectly formed on the surface of the coated article and contains a bright material, and the colored layer overlaps on the bright layer, contains a warm color system pigment and has translucency. Specifically, in the laminated coating film, regarding the Y value of the bright layer corrected with a standard white board in the XYZ colorimetric system, when the Y value of the reflected light measured with an incident light angle of 45° and a light receiving angle of 10° is set as Y(10°), and the Y value of the reflected light measured with an incident light angle of 45° and a light receiving angle of 25° is set as 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 concentration C of the warm color system pigment in the colored layer is 1% by mass or more and 17% by mass or less.

[0005] Patent Document 3 has the following description: For a laminated coating film including a bright layer and a colored layer, the FF property is improved to achieve a metallic luster color with high design aesthetics. Among them, the bright layer is directly or indirectly formed on the surface of the object to be coated and contains a bright material; the colored layer overlaps on the bright layer, contains a red pigment system and has light transmittance. In the technology of this document, regarding the Y value corrected with a standard white board in the XYZ colorimetric system of the bright layer, when the incident angle of light (the angle measured from the perpendicular line of the surface of the bright layer) is set to 45° and the light receiving angle (the inclination angle inclined from the specular reflection direction toward the light source side) is 5°, the Y value of the reflected light measured is set as Y(5°), and when the incident angle of light (the angle measured from the perpendicular line of the surface of the bright layer) is set to 45° and the light receiving angle is 15°, the Y value of the reflected light measured is set as Y(15°), the Y(5°) of the bright layer is 30 or more and 700 or less. In addition, Y(15°) = k × Y(5°), (where k is a coefficient.), and k is 0.01 or more and 0.3 or less. Moreover, the concentration of the above-mentioned red coloring material in the above-mentioned colored layer is 1% by mass or more and 17% by mass or less.

[0006] Patent Document 4 describes a method for forming a multi-layer coating film applicable to various industrial products, especially applicable to automotive outer panels. This method can obtain the following coating film: having high brightness and high saturation in the bright part (near the specular reflected light), having high saturation in the dark part (oblique direction), having a large difference in brightness between the bright part and the dark part, and having a uniform appearance of the finished product. In this method, a first colored transparent coating film is formed on a metallic base coating film obtained by coating a metallic base coating containing a coloring pigment and a scaly bright pigment, and a second colored transparent coating film is formed on the first colored transparent coating film. And the coloring pigments contained in the first colored transparent coating film and the second colored transparent coating film are the same. In addition, the ratio of the concentration of the coloring pigment per unit film thickness in the first colored transparent coating film to the concentration of the coloring pigment per unit film thickness in the second colored transparent coating film is in the range of 30 / 70 to 60 / 35.

[0007] Patent Document 1: Japanese Unexamined Patent Publication No. 2006 - 281451

[0008] Patent Document 2: Pamphlet of International Publication No. 2018 / 061215

[0009] Patent Document 3: Japanese Unexamined Patent Publication No. 2022 - 078780

[0010] Patent Document 4: Japanese Unexamined Patent Publication No. 2012 - 232236 Summary of the Invention

[0011] -Technical Problems to be Solved by the Invention-

[0012] However, in dark color systems with overall low lightness, it is difficult to ensure the lightness difference between the highlight and the shadow parts, thus there are problems such as it being difficult to balance the vivid red color rendering with a sense of transparency and the strong sense of depth.

[0013] Therefore, the present disclosure provides a laminated coating film and a coated article of a dark color system that can balance the vivid red color rendering with a sense of transparency and the strong sense of depth while ensuring overall low lightness.

[0014] - Technical solutions for solving technical problems -

[0015] To solve the above technical problems, the laminated coating film disclosed herein is characterized in that:

[0016] It includes a bright layer and a colored layer. The bright layer contains bright materials and is formed directly or indirectly on the surface of the object to be coated; the colored layer is laminated on the bright layer, and the colored layer contains coloring materials and has light transmittance.

[0017] When the incident angle of light is set to 45° and the lightness L* value and chroma C* value of the reflected light measured under the light-receiving angle θ are set to L*(θ) and C*(θ) respectively, the laminated coating film satisfies the following formulas (1) to (3).

[0018] 5 ≤ L*(θ) ≤ 25 (10° ≤ θ ≤ 25°)......(1)

[0019] 20 ≤ C*(θ) ≤ 65 (10° ≤ θ ≤ 25°)......(2)

[0020] 2 ≤ C*(80°)......(3).

[0021] In the laminated coating film of a dark color system, that is, a hue with overall low lightness, by making the highlight part (10° ≤ θ ≤ 25°) have low lightness and high chroma as shown in the above formulas (1) and (2), thus, even in an overall darker hue, an extremely fine, highly transparent, and vivid color rendering can be obtained. In addition, by making the shadow part (θ = 80°) have a certain chroma although the lightness is extremely low as shown in the above formula (3), a strong sense of depth with both chroma can be achieved.

[0022] Preferably, when the θ values at which the L*(θ) of the laminated coating film becomes the upper limit value and the lower limit value are set to θ1 and θ2 respectively,

[0023] For the laminated coating film, the coefficient k satisfying C*(θ1) = k × C*(θ2) is 0.03 or more and 0.5 or less, where 10° ≤ θ ≤ 25°.

[0024] Regarding C*(θ1) and C*(θ2) corresponding to the upper limit value and the lower limit value of the lightness L* value of the bright part, by making k satisfy the above numerical range, it is possible to more effectively ensure high transparency red color development in the bright part.

[0025] When the θ values at which the L*(θ) of the laminated coating film becomes the upper limit value and the lower limit value are set as θ1 and θ2 respectively,

[0026] If the difference ΔC* = C*(θ1) - C*(80°) between C*(θ1) and the C*(80°) is defined as the chroma shading sense index, it is preferably 50 or more, where 10° ≤ θ ≤ 25°.

[0027] The larger the chroma shading sense index, the lower the overall lightness. However, since the contrast of the chroma between the bright part and the dark part can be ensured, it is possible to balance the bright and vivid red color development with a transparent feeling and a strong depth feeling.

[0028] In addition, it is preferably that when the light-receiving angle θ is 45°, in the change of the Y value of the laminated coating film measured continuously in the direction parallel to the surface of the laminated coating film, the average value of the standard deviation of the Y value calculated for each specified measurement distance is defined as the particle feeling index of the laminated coating film, and the particle feeling index is 0.09 or more and 0.12 or less.

[0029] By making the particle feeling index within the above numerical range, in the dark color system, although it has a low lightness, it is possible to obtain a bright and deep hue.

[0030] In particular, for the laminated coating film of the dark color system, when both the chroma shading sense index and the particle feeling index satisfy the above numerical range, while ensuring the overall low lightness, it is possible to more effectively balance the bright and vivid red color development with a transparent feeling and a strong depth feeling.

[0031] It is preferably that the bright layer satisfies the following formulas (4) to (6).

[0032] 11 ≤ L*(θ) ≤ 70 (10° ≤ θ ≤ 25°) …… (4)

[0033] 6 ≤ C*(θ) ≤ 30 (10° ≤ θ ≤ 25°) …… (5)

[0034] 0.5 ≤ C*(80°) …… (6).

[0035] By making the L* value and the C* value of the bright layer containing the bright material satisfy the above formulas (4) to (6), it is easy to achieve the numerical range of the above L* value and C* value of the laminated coating film.

[0036] In one embodiment, the light-reflecting layer contains a first coloring material and a second coloring material.

[0037] The first coloring material is a black-based coloring material.

[0038] The second coloring material is a coloring material of a color other than black-based.

[0039] If the light diffusely reflected from the minute irregularities, edges, and the underlying layer (such as an electrophoretic coating film) on the surface of the light-reflecting material passes through the coloring layer, the amount of light in the shaded part increases, and the lightness of the shaded part rises. If the lightness of the shaded part increases, the whiteness of the shaded part will increase, which is the reason for the blurring of the red color display in the bright part.

[0040] In this structure, since the light-reflecting layer contains a black-based coloring material, most of the incident light passing through the gaps between the light-reflecting materials is absorbed and / or blocked by the black-based coloring material in the light-reflecting layer, so that the reflection of light from the underlying layer almost disappears. Moreover, the light diffusely reflected due to the minute irregularities and edges of the light-reflecting material is absorbed and / or blocked by the black-based pigment, so that the lightness of the shaded part decreases.

[0041] As the black-based coloring material contained in the light-reflecting layer, black-based pigments with excellent weather resistance and / or black-based dyes with excellent transparency can be cited. However, from the viewpoint of ensuring sufficient weather resistance of the laminated coating film, black-based pigments can be used. As the black-based pigment, for example, carbon black, chromium oxide, iron oxide, manganese oxide, black indigo pigments, etc. can be used.

[0042] In addition, by containing a coloring material of a color other than black-based, such as a red-based coloring material, in the above-mentioned light-reflecting layer, light scattering can be suppressed, and the chroma of the shaded part can be ensured, bringing a strong sense of depth.

[0043] Preferably, the solid content concentration of the first coloring material in the light-reflecting layer is 1% by mass or more and 20% by mass or less.

[0044] If the solid content concentration of the first coloring material is too low, it may not be possible to sufficiently obtain the light absorption function and the light concealing function. On the other hand, if the solid content concentration of the first coloring material is too high, in the case where the first coloring material is a pigment, for example, it is likely to be in a state where the structures mechanically entangled by the aggregation of primary particles, light scattering will increase, so that the transparency may decrease and the lightness of the shaded part may increase. Therefore, by making the solid content concentration of the first coloring material in the light-reflecting layer within the above range, it is beneficial to reduce the lightness of the shaded part.

[0045] Preferably, the solid content concentration of the second coloring material in the lightness layer is 1% by mass or more and 20% by mass or less.

[0046] In this way, it is possible to obtain a sufficient effect of suppressing light scattering, and it is also possible to sufficiently ensure the chroma of the shaded part, bringing a strong sense of depth.

[0047] Preferably, the first coloring material is a black-based pigment, and the second coloring material is a red-based pigment.

[0048] In this way, it is possible to suppress light scattering, and in the case of a hue with an overall low lightness, it is also possible to achieve a hue that maintains the vividness of red.

[0049] Preferably, the coloring material contained in the coloring layer is a red-based pigment,

[0050] The solid content concentration of the red-based pigment in the coloring layer is 1% by mass or more and 17% by mass or less.

[0051] By making the coloring layer contain a red-based pigment at the above solid content concentration, thus, in a hue with an overall low lightness, it is also possible to ensure the chroma of red and achieve a vivid red with a transparent feeling.

[0052] As a coated object having the above laminated coating film on the object to be coated, for example, it can be an automobile body, or it can also be a motorcycle, the body of other transportation means, or it can also be other metal products or plastic products.

[0053] -Effects of the Invention-

[0054] As described above, according to the present disclosure, in a laminated coating film having a dark color system, that is, a hue with an overall low lightness, by making the bright part (10° ≤ θ ≤ 25°) have a low lightness and a high chroma as shown in the above formulas (1) and (2), thus, even in a hue that is overall dark, it is possible to obtain extremely fine and highly transparent color development. In addition, by making the shaded part (θ = 80°) have a very low lightness but ensure a certain chroma as shown in the above formula (3), thus, it is possible to achieve a sense of depth that is both chromatic and thick. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is a cross-sectional view schematically showing the laminated coating film;

[0056] Figure 2 is an explanatory diagram showing the measurement method of the L* value of the laminated coating film;

[0057] Figure 3 (a) of is an explanatory diagram showing the measurement method of the particle feeling index of the laminated coating film, Figure 3The graph (b) shows an example of the measurement results of the particle feeling index of the laminated coating film;

[0058] Figure 4 The graph (a) shows the relationship between the L* value and the light-receiving angle of the laminated coating films of the examples and comparative examples. Figure 4 The graph (b) shows the relationship between the C* value and the light-receiving angle of the laminated coating films of the examples and comparative examples;

[0059] Figure 5 The graph shows the relationship between the chroma shading feeling index and the particle feeling index of the laminated coating films of the examples and comparative examples;

[0060] Figure 6 The graph shows the relationship between the PWC of the black pigment in the bright layer and the average particle size. DETAILED DESCRIPTION

[0061] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its application, or the scope of its use.

[0062] (First Embodiment)

[0063] <TERMS>

[0064] In this specification, the proportion (mass %) of the mass of each solid component in all the solid components (excluding solvents and water, all of the solid components such as pigments, bright materials, resins, and additive materials) contained in the coating composition is referred to as "solid component concentration" or "PWC".

[0065] <STRUCTURAL EXAMPLE OF LAMINATED COATING FILM>

[0066] Hereinafter, structural examples of the laminated coating film and the coated object will be described.

[0067] As Figure 1 shown, the vehicle body 11 (coated object) in the present embodiment has a laminated coating film 12, and the laminated coating film 12 is provided on the surface of the steel plate 11A (object to be coated) with the electrophoretic coating film 13 interposed therebetween. The laminated coating film 12 is obtained by sequentially laminating a bright layer 14, a light-transmissive colored layer 15, and a colorless light-transmissive layer 16. The electrophoretic coating film 13 is formed on the surface of the steel plate 11A in advance by cationic electrophoretic coating.

[0068] The bright layer 14 contains a resin component as a base material, a bright material 21, a black pigment 23 (first coloring material, black coloring material), and a bright layer red pigment 24 (second coloring material, coloring material of a color other than black).

[0069] The colored layer 15 contains a resin component as a base material and a red pigment 25 (coloring material) for the colored layer.

[0070] As the resin components of the bright layer 14 and the colored layer 15, for example, acrylic resins, polyester resins, polyurethane resins, melamine resins, etc. can be used alone or in combination of multiple types, but these do not limit the intention of the present disclosure. As the resin component of the colorless light-transmitting layer 16, for example, a combination of a carboxylic acid group-containing acrylic resin and a polyester resin, a combination of an epoxy group-containing acrylic resin, and a combination of an acrylic resin and / or a polyester resin and a polyisocyanate can be used.

[0071] The bright layer 14 and the colored layer 15 may also contain additive materials such as an ultraviolet ray shielding material, an adhesive material, a tackifier, a pigment dispersant, a surface conditioning material, etc. as needed. In particular, from the viewpoint of the light resistance of the laminated coating film 12, it is preferable to contain an ultraviolet ray shielding material. As the ultraviolet ray shielding material, an organic compound-based ultraviolet absorber, an inorganic compound-based ultraviolet scatterer, etc. (hereinafter, sometimes referred to as "inorganic UVA") can be adopted, and among them, nanoparticles of metal oxides such as iron oxide are preferably adopted.

[0072] The film thickness of the bright layer 14 is preferably 6 μm or more and 15 μm or less, more preferably 7 μm or more and 13 μm or less; the film thickness of the colored layer 15 is preferably 8 μm or more and 15 μm or less.

[0073] The surface roughness Ra of the electrophoretic coating film 13 is preferably 2.0 μm or less, more preferably 1.0 μm or less. In this way, the orientation of the bright material 21 of the bright layer 14 is improved.

[0074] <Bright layer>

[0075] [Bright material]

[0076] The bright layer 14 contains high-reflection flakes 21A and low-reflection flakes 21B as the bright material 21, and the visible light reflectivity of the low-reflection flakes 21B is lower than that of the high-reflection flakes 21A.

[0077] · High-reflection flakes

[0078] As the high-reflection flakes 21A contained in the bright layer 14, metal flakes with a high visible light reflectivity can be adopted. In the present embodiment, aluminum flakes are adopted as the high-reflection flakes 21A.

[0079] From the viewpoint of obtaining sufficient lightness and chroma of the bright part, it is preferable that the visible light reflectivity of the aluminum flakes is 90% or more. In this way, the light quantity in the direction of the bright part can be sufficiently ensured, and sufficient lightness and chroma of the bright part can be obtained.

[0080] As such aluminum flakes, specifically, it is preferable to use flakes having an average particle diameter 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. In particular, in the case of vapor-deposited aluminum flakes, the average thickness is preferably 10 nm or more and 50 nm or less; in the case of thin-film aluminum flakes, the average thickness is preferably 100 nm or more and 500 nm or less.

[0081] It should be noted that in this specification, the "average particle diameter" of the brightening material 21, various pigments, inorganic UVA composed of nanoparticles, etc. is obtained, for example, by obtaining the 50% value of the particle size distribution, i.e., D50, and this particle size distribution is measured by a laser diffraction type particle size distribution measuring device. The average particle diameter is preferably the number average particle diameter.

[0082] In addition, 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 (for example, 50) of brightening materials 21, and calculating their average value.

[0083] If the average particle diameter is too small, the reflection characteristics may be reduced; if the average particle diameter is too large, although the reflection characteristics are excellent, the particle feeling of the appearance may become too strong. In addition, the thicker the thickness of the aluminum flakes, the stronger the diffuse reflection at the edges of the aluminum flakes, but as described above, since the thickness is very thin, this diffuse reflection is very weak. As a result, it is beneficial to reduce the lightness of the shaded part.

[0084] It should be noted that the aspect ratio (average particle diameter / average thickness) of the aluminum flakes is preferably 30 or more and 300 or less.

[0085] In addition, the surface roughness Ra of the aluminum flakes is preferably 50 nm or less. In particular, in the case of vapor-deposited aluminum flakes, the surface roughness Ra is preferably 7 nm or less; in the case of smooth aluminum flakes, the surface roughness Ra is preferably 50 nm or less. In this way, the diffuse reflection caused by the fine unevenness on the surface of the aluminum flakes can be reduced, so the lightness of the shaded part can be reduced.

[0086] Note that, from the viewpoint of increasing the brightness of the bright part, the bright material 21 is oriented substantially parallel to the surface of the bright layer 14 (the average orientation angle of the bright material 21 with respect to the surface of the bright layer 14 is 1.2 degrees or less). For example, after coating a coating material containing the bright material 21, a black pigment 23, a red pigment 24 of the bright layer, etc. on the electrophoretic coating film 13, the solvent is evaporated by drying, and the film volume shrinks and becomes thinner, whereby the bright material 21 is arranged with an average orientation angle of 1.2 degrees or less. The average orientation angle of the bright material 21 can be obtained as follows: Based on the 3D shape data (xyz coordinates) of the surface of the bright layer 14 measured by a laser microscope (manufactured by Keyence Corporation, VK-X1000), calculate the inclination of a plurality of (for example, 50) bright materials 21 contained in one field of view with respect to the surface of the bright layer 14, and take their average value.

[0087] There are two types of aluminum flakes, floating type and non-floating type, and either type can be used, but non-floating type aluminum flakes are preferably used.

[0088] Since the surface tension of the floating type aluminum flakes is low, when coating a coating material containing the floating type aluminum flakes, the aluminum flakes will float on the surface of the bright layer 14 and be oriented parallel to the surface. If the aluminum flakes float on the surface of the bright layer 14, the amount of reflected light increases and the metallic luster is enhanced, but a flat and strong luster like specular reflection will be obtained. In addition, in the case of floating type aluminum flakes, due to factors such as a small surface area and a reduced amount of resin component arranged on the surface of the bright layer 14, there is a problem that the adhesion between the bright layer 14 and the colored layer 15 is reduced and it is easily peeled off due to external reasons such as chipping.

[0089] In contrast, since the surface tension of the non-floating type aluminum flakes is high, when coating a coating material containing the non-floating type aluminum flakes, for example, as Figure 1 shown, the aluminum flakes will be oriented parallel to the surface of the bright layer 14 and irregularly dispersed in the film thickness direction. In this way, since the amount of reflected light changes corresponding to the position of the aluminum flakes in the film thickness direction, a metallic texture luster with a three-dimensional effect can be obtained, and thus a more aesthetically designed coloring can be obtained. In addition, in the case of non-floating type aluminum flakes, the amount of resin component arranged on the surface of the bright layer 14 can be sufficiently ensured, so that sufficient adhesion between the bright layer 14 and the colored layer 15 can be ensured.

[0090] · Low-reflection flakes

[0091] Although highly reflective scales 21A such as aluminum scales are effective in increasing the brightness of bright areas, there are diffuse reflections caused by minute irregularities on the scale surfaces, diffuse reflections at the scale edges, and diffuse reflections of the electrophoretic coating film 13. Therefore, simply adjusting the concentration of the highly reflective scales 21A cannot adjust the brightness of the bright and dark areas to the desired darkness. Thus, in the present embodiment, the highly reflective scales 21A and the low reflective scales 21B are used simultaneously, and the light absorption function and the light concealing function of the low reflective scales 21B are utilized to adjust the reflection characteristics of the laminated coating film.

[0092] When the highly reflective scales 21A and the low reflective scales 21B are used simultaneously, most of the incident light passing through the gaps between the highly reflective scales 21A hits the low reflective scales 21B and is blocked, so that the reflection of light by the underlying layer (electrophoretic coating film 13) almost disappears. Also, the light diffusely reflected by the highly reflective scales 21A is blocked or absorbed by the low reflective scales 21B, whereby the brightness of the dark areas is reduced.

[0093] The visible light reflectance of the low reflective scales 21B is preferably 3 / 4 or less, more preferably 1 / 2 or less, of that of the highly reflective scales 21A. It is sufficient that the average particle diameter of the low reflective scales 21B is 5 μm or more and 20 μm or less. From the viewpoint of suppressing diffuse reflection, the thickness of the low reflective scales 21B is preferably 10 nm or more and 100 nm or less, and the surface roughness Ra of the low reflective scales 21B is 100 nm or less. The thicker the thickness of the scaly bright material, the stronger the diffuse reflection at the edge of the scaly bright material. However, since the thickness of the low reflective scales 21B is thin, the diffuse reflection is weak. As a result, it is advantageous for reducing the brightness of the dark areas.

[0094] Specific examples of the low reflective scales 21B include scales such as those having a visible light reflectance of 3 / 4 that of aluminum scales, scales represented by chromium scales having a visible light reflectance of 1 / 2 that of aluminum scales, scales represented by stainless steel scales having a visible light reflectance of 1 / 4 that of aluminum scales, and scales represented by chromium oxide scales having a visible light reflectance of 1 / 18 that of aluminum scales. Examples of the low reflective scales 21B that can be cited include scales represented by plate-like iron oxide (α-Fe2O3) scales and carbon scales. As the low reflective scales 21B, chromium oxide scales are preferably used.

[0095] It should be noted that in order to adjust the light reflection characteristics, only the high-reflection flakes 21A can be used as the light-reflecting material of the light-reflecting layer 14, and a light-absorbing black bottom layer (absorbing layer) or other dark base layers (absorbing layers) that absorb light are provided between the light-reflecting layer 14 and the electrophoretic coating film 13. That is to say, it is a method of adjusting the PWC of the high-reflection flakes 21A in the light-reflecting layer 14, and the light that has passed through the gaps between the high-reflection flakes 21A is absorbed by the dark bottom layer. In the case of adopting this method, although it is necessary to coat the dark bottom layer, the reflection characteristics can be adjusted.

[0096] · Area ratio of the light-reflecting material

[0097] The ratio of the projected area of the light-reflecting material 21 to the bottom surface of the light-reflecting layer 14 when the light-reflecting material 21 is projected onto the bottom surface of the light-reflecting layer 14 (in this specification, it is also referred to as the "area ratio"). Per unit area, it is preferably 3% or more and 70% or less, more preferably 20% or more and 50% or less.

[0098] If the area ratio of the light-reflecting material 21 is too small, the amount of reflected light reflected by the light-reflecting material 21 is insufficient, and sufficient chroma of the bright part cannot be obtained. On the other hand, if the area ratio of the light-reflecting material 21 is too large, the amount of the light-reflecting material 21 is large, and the influence of diffuse reflection caused by the fine unevenness or edges on the surface of the light-reflecting material 21 becomes large, the brightness of the bright part and the dark part increases, and the strength and weather resistance of the light-reflecting layer 14 decrease. By making the area ratio of the light-reflecting material 21 within the above range, sufficient darkness of the bright part and the dark part can be ensured, the chroma shadow sense can be improved, and sufficient strength and weather resistance can be obtained.

[0099] For example, magnify the surface of the light-reflecting layer 14 with a microscope and observe the surface of the light-reflecting layer 14. Calculate the area ratio of the light-reflecting material 21 in multiple fields of view (for example, 10 fields of view) through image processing, and take their average value, then the area ratio per unit area of the light-reflecting material 21 can be obtained.

[0100] For example, by making the PWC of the light-reflecting material 21 in the light-reflecting layer 14 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, the area ratio of the light-reflecting material 21 as described above can be achieved. If the PWC of the light-reflecting material 21 is less than 1% by mass, a sufficient area ratio of the light-reflecting material 21 cannot be obtained. If the PWC of the light-reflecting material 21 exceeds 17% by mass, the area ratio of the light-reflecting material 21 will be too large.

[0101] In addition, when the high-reflection flakes 21A and the low-reflection flakes 21B are used as the light-reflecting material 21, it is preferable that the proportion of the low-reflection flakes 21B in the light-reflecting material 21 is 10% by mass or less.

[0102] [Black pigment system]

[0103] Although the scaly bright material 21 is effective in increasing the lightness of the bright part, there are diffuse reflections caused by minute irregularities on the surface of the scales, diffuse reflections at the edges of the scales, and also diffuse reflections at the bottom layer (the electrophoretic coating film 13 in the present embodiment). If the light that has undergone such diffuse reflection passes through the colored layer 15, then particularly the amount of light in the shaded part increases, and the lightness of the shaded part rises. If the lightness of the shaded part increases, then the white color in the shaded part increases, so the red color development in the bright part becomes blurred, and thus the overall lightness rises and the chroma shading sensation decreases. Therefore, it is preferable to make the bright layer 14 contain a black pigment system 23, and use the light absorption function and light hiding function of the black pigment system 23 to adjust the reflection characteristics of the shaded part.

[0104] Since most of the incident light passing through the gaps between the bright materials 21 is absorbed and / or shielded by the black pigment system 23, the diffuse reflection caused by the bottom layer (the electrophoretic coating film 13) almost disappears. Moreover, the light from the minute irregularities and edge diffuse reflections of the bright material 21 is absorbed and / or shielded by the black pigment system 23, whereby the lightness of the shaded part decreases.

[0105] As the black pigment system 23 contained in the bright layer 14, there is no intention of limitation, but for example, carbon black with excellent weather resistance can be used.

[0106] The PWC of the black pigment system 23 in the bright layer 14 is 1% by mass or more and 20% by mass or less, preferably 3% by mass or more and 19% by mass or less, more preferably 5% by mass or more and 15% by mass or less. If the PWC of the black pigment system 23 is too low, it may not be possible to sufficiently obtain its light absorption function and light hiding function. On the other hand, if the PWC of the black pigment system 23 is too high, the structures formed by the aggregation of the primary particles are likely to become mechanically entangled with each other, and light scattering increases, so it may lead to a decrease in transparency and an increase in the lightness of the shaded part. Therefore, by setting the PWC of the black pigment system 23 in the bright layer 14 within the above range, it is very advantageous for reducing the lightness of the shaded part.

[0107] The average particle size of the black pigment system 23 is preferably 10 nm or more and 200 nm or less, more preferably 50 nm or more and 160 nm or less. Since the average particle size of 200 nm or less is less than half the wavelength of the lower limit of visible light (wavelength 400 nm), light scattering caused by the particles of the black pigment system 23 can be suppressed, and thus the darkness of the shaded part can be ensured. If the average particle size of the black pigment system 23 is less than 10 nm, it is difficult to ensure sufficient low lightness. If the average particle size of the black pigment system 23 exceeds 200 nm, light scattering caused by the particles of the black pigment system 23 cannot be sufficiently suppressed, and thus it is difficult to ensure sufficient darkness of the shaded part.

[0108] In order to adjust the light reflection characteristics, a light-absorbing black base layer (absorbing layer) or other dark base layers (absorbing layers) can also be provided between the light-reflecting layer 14 and the electrophoretic coating film 13. That is to say, it is in such a way that the light passing through the gaps between the light-reflecting materials 21 in the light-reflecting layer 14 is absorbed by the dark base layer. In the case of adopting this method, although it is necessary to coat the dark base layer, the reflection characteristics can be adjusted.

[0109] [Red series pigment of light-reflecting layer]

[0110] The light-reflecting layer 14 contains a coloring material of a color other than the black series, preferably contains a coloring material of the same color as the coloring material contained in the coloring layer 15. For example, it preferably contains a red series coloring material. In this way, light scattering can be suppressed, and the chroma of the bright part and the dark part, especially the dark part, can be ensured. A hue that maintains the vividness and depth of red can also be achieved in a hue with an overall low lightness.

[0111] In the present embodiment, a red series pigment 24 of the light-reflecting layer is contained as the red series coloring material. Specifically, as the red series pigment 24 of the light-reflecting layer, for example, organic pigments such as perylene red, dibromo anza slon red, azo red, anthraquinone red, quinacridone red, and diketopyrrolopyrrole can be used, and perylene red with excellent weather resistance is particularly preferably used.

[0112] The average particle size of the red series pigment 24 of the light-reflecting layer is 10 nm or more and 200 nm or less, preferably 50 nm or more and 200 nm or less.

[0113] Since the average particle size of the red series pigment 24 of the light-reflecting layer is 200 nm or less, geometric optical scattering or Mie scattering caused by pigment particles does not occur; since the average particle size of the red series pigment 24 of the light-reflecting layer is 10 nm or more, Rayleigh scattering can also be avoided, which is beneficial to the realization of a vivid red color with a transparent feeling and a strong depth sense.

[0114] The PWC of the red series pigment 24 of the light-reflecting layer in the light-reflecting layer 14 is 1% by mass or more and 20% by mass or less, preferably 2% by mass or more and 10% by mass or less, and more preferably 4% by mass or more and 8% by mass or less.

[0115] If the PWC of the red pigment 24 in the light-reflecting layer 14 is less than 1% by mass, sufficient color rendering of red in the highlight part cannot be obtained. On the other hand, if the PWC of the red pigment 24 in the light-reflecting layer 14 exceeds 20% by mass, the absorption and / or shielding effect of the reflected light caused by the pigment particles increases, and the lightness and chroma of the highlight part decrease. Moreover, the lightness of the shadow part increases due to the light scattering effect caused by the pigment particles, so the chroma shadow feeling decreases.

[0116] [Entire coloring material]

[0117] For the laminated coating film of dark color systems, it is necessary to reduce the overall lightness. In this regard, it is effective to contain a black pigment 23 in the light-reflecting layer 14. Moreover, in addition to the coloring layer 15, the light-reflecting layer 14 also contains a red pigment, which is very advantageous in ensuring the chroma shadow feeling between the highlight part and the shadow part sufficiently despite the overall low lightness, and taking into account the bright red color rendering with a transparent feeling and the thick and profound feeling.

[0118] That is to say, it is preferable to contain both the black pigment 23 and the red pigment 24 in the light-reflecting layer 14.

[0119] Moreover, the total PWC of all the coloring materials contained in the light-reflecting layer 14, that is, the sum of the black pigment 23 and the red pigment 24 in the light-reflecting layer, is preferably 1% by mass or more and 26% by mass or less, and more preferably 5% by mass or more and 25% by mass or less.

[0120] In addition, the ratio of the red pigment 24 in the light-reflecting layer to the sum of the black pigment 23 and the red pigment 24 in the light-reflecting layer is preferably 80% by mass or less, and more preferably 5% by mass or more and 50% by mass or less.

[0121] With the above configuration, despite the overall low lightness, it is possible to effectively take into account the bright red color rendering with a transparent feeling and the thick depth feeling.

[0122] <Coloring layer>

[0123] [Red pigment in the coloring layer]

[0124] As the red pigment 25 in the coloring layer, for example, organic pigments such as perylene red, strontium dibromate red, azo red, anthraquinone red, quinacridone red, and diketopyrrolopyrrole can be used, and perylene red with excellent weather resistance is particularly preferably used.

[0125] The average particle diameter of the red pigment 25 in the coloring layer is preferably 2 nm or more and 160 nm or less, and more preferably 2 nm or more and 30 nm or less.

[0126] Since the average particle size of the red pigment is 160 nm or less, geometric optical scattering and Mie scattering caused by pigment particles do not occur. Since the average particle size of the red pigment is 2 nm or more, Rayleigh scattering can also be avoided, which is beneficial for vivid red color development with a sense of transparency. In addition, due to the small average particle size, for the same PWC, compared with the case of larger pigment particle size, the frequency of light being absorbed when passing through the colored layer by hitting pigment particles is higher, so the attenuation of light becomes larger. If the attenuation of light becomes larger, the amount of light passing through the colored layer 15 will decrease, and the overall chroma will decrease. However, since the amount of light in the highlight direction is originally large, the influence of light attenuation on chroma is small. On the other hand, since the amount of light in the shadow direction is originally small, the influence of light attenuation on chroma becomes larger. Thus, by reducing the particle size of pigment particles, an improvement in chroma shadow effect can be achieved, which is beneficial for achieving both vivid red color development with a sense of transparency and a strong sense of depth.

[0127] The PWC of the red pigment 25 in the colored layer 15 of the colored layer is 1% by mass or more and 17% by mass or less, preferably 4% by mass or more and 10% by mass or less.

[0128] If the PWC of the red pigment 25 in the colored layer 15 of the colored layer is less than 1% by mass, sufficient color development of red in the highlight part cannot be obtained. If the PWC of the red pigment 25 in the colored layer exceeds 17% by mass, the absorption and / or shielding effect of the reflected light caused by pigment particles increases, and the chroma of the highlight part decreases, and the lightness and chroma of the shadow part both increase due to the light scattering effect caused by pigment particles. Therefore, the chroma shadow effect index decreases.

[0129] <Optical properties of the laminated coating film>

[0130] [L* value and C* value]

[0131] The L* value and C* value are the lightness and chroma of the L*a*b* colorimetric system, respectively. It should be noted that the C* value can be calculated from the values of a* and b* using the formula C* = √((a*) 2 +(b*) 2 ).

[0132] Figure 2 Shows the measurement method of the L* value of the laminated coating film 12. The incident angle of the light from the light source 41 (the angle measured from the object to be measured, here the angle from the perpendicular line on the surface of the laminated coating film 12) is 45°. The light receiving angle θ of the sensor 42 (the inclination angle from the specular reflection direction towards the light source side) is such that the specular reflection direction is 0°. The measurement was carried out using a three-dimensional variable-angle spectrocolorimeter GCMS - 4 manufactured by Murakami Color Technology Research Institute Co., Ltd.

[0133] When the L* value and C* value of the reflected light measured at a light incident angle of 45° and a light receiving angle θ are L*(θ) and C*(θ) respectively, the laminated coating film 12 satisfies the following formulas (1) to (3).

[0134] 5 ≤ L*(θ) ≤ 25 (10° ≤ θ ≤ 25°) ……(1)

[0135] 20 ≤ C*(θ) ≤ 65 (10° ≤ θ ≤ 25°) ……(2)

[0136] 2 ≤ C*(80°) ……(3).

[0137] In other words, L*(θ) at the bright light part where 10° ≤ θ ≤ 25° is 5 or more and 25 or less, preferably 6 or more and 25 or less, more preferably 8 or more and 24 or less, and particularly preferably 8.77 or more and 23.41 or less. In addition, C*(θ) at 10° ≤ θ ≤ 25° is 20 or more and 65 or less, preferably 21 or more and 65 or less, more preferably 23 or more and 63 or less, and particularly preferably 31.2 or more and 62.68 or less.

[0138] In addition, when the light receiving angle is 90°, since the reflected light overlaps with the incident light, it is difficult to measure. Therefore, C*(80°) at the light receiving angle of 80° near the light receiving angle of 90° is set as the C* value of the dark part. C*(80°) is 2 or more, preferably 2.2 or more and 10 or less, more preferably 3 or more and 8 or less, and particularly preferably 4 or more and 5 or less.

[0139] In the laminated coating film 12 having a dark red color like aged wine, that is, having a red hue with low lightness as a whole, by making the bright light part (10° ≤ θ ≤ 25°) have low lightness and high chroma as shown in the above formulas (1) and (2), extremely fine, highly transparent and vivid red color development can be obtained even in a dark hue as a whole. In addition, by making the dark part (θ = 80°) have a certain chroma although the lightness is extremely low as shown in the above formula (3), a deep sense with both chroma and thickness can be achieved.

[0140] It should be noted that for the laminated coating film of dark color system, from the viewpoint of ensuring sufficient low lightness, it is preferable that the lightness L*(80°) of the dark part (θ = 80°) is 5 or less, and more preferably 4 or less.

[0141] [k]

[0142] For the laminated coating film 12 of dark color system, although the bright light part has low lightness, from the viewpoint of obtaining a vivid red color development with a transparent feeling despite the low lightness, it is preferable that the slope of the chroma of the bright light part is within a specified numerical range.

[0143] Specifically, when the L*(θ) of the laminated coating film 12 at the bright light part (10° ≤ θ ≤ 25°) reaches the upper limit value (for example, 25, preferably 24, more preferably 23.41) and the lower limit value (for example, 5, preferably 8, more preferably 8.77), θ is set as θ1 and θ2 respectively.

[0144] Regarding the laminated coating film 12, if the coefficient k that satisfies C*(θ1) = k × C*(θ2) is set as the slope of the chroma at the bright light part, k is preferably 0.03 or more and 0.5 or less, and more preferably 0.1 or more and 0.5 or less.

[0145] Regarding C*(θ1) and C*(θ2) corresponding to the upper limit value and the lower limit value of the lightness L* value at the bright light part, by making k satisfy the above numerical range, it is possible to more effectively ensure a vivid red color display with high transparency at the bright light part.

[0146] [Chroma shadow sense index]

[0147] In the laminated coating film of dark-colored colors, both the bright light part and the dark part have low lightness. In order to also take into account a vivid red color display with a transparent feeling and a strong depth feeling in the case of low lightness, it is effective to ensure the contrast of the chroma between the bright light part and the dark part. In this specification, the contrast of the chroma between the bright light part and the dark part is called "chroma shadow sense".

[0148] As a representative value of the chroma C* value of the bright light part of the laminated coating film 12, the chroma C*(θ1) at the above light-receiving angle θ1 is adopted, and the chroma difference between the bright light part and the dark part, that is, ΔC* = C*(θ1) - C*(80°), is set as an index representing the above chroma shadow sense, namely the chroma shadow sense index (in this specification, also called "C*FF").

[0149] The larger the chroma shadow sense index, the lower the overall lightness. However, since the contrast of the chroma between the bright light part and the dark part can be ensured, it is possible to take into account a vivid red color display with a transparent feeling and a strong depth feeling.

[0150] Specifically, the chroma shadow sense index is preferably 50 or more, and more preferably 50 or more and 60 or less.

[0151] [Particle sense index]

[0152] The Y value in the XYZ colorimetric system is the Y in the three stimulus 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 is a stimulus value representing brightness (luminous reflectance).

[0153] [Mathematical formula 1]

[0154]

[0155] It should be noted that x(λ), y(λ), and z(λ) (omitting their respective overline marks) are CIE color-matching functions, and Le, Ω, and λ are the spectral radiance of the color of the color measurement observer.

[0156] Figure 3 (a) of shows a method for measuring the particle feeling index of the laminated coating film 12. In this specification, "particle feeling" means a texture such as "glitter" and "roughness" felt according to the intensity of the diffused light reflected by the bright material 21 or the like located in the laminated coating film 12. Since it is generally considered that the intensity of the diffused light brings about the particle feeling, a correlation relationship is assumed to exist between the magnitude of the change in the above Y value, that is, the deviation of the Y value, and the particle feeling, and the standard deviation of the Y value, which is an index representing the deviation of the Y value, is set as the index of the particle feeling. It should be noted that the device used in the measurement is based on the microfacet spectral color difference meter VSS 7700 manufactured by Nippon Denshoku Industries Co., Ltd., and the workbench on which the sample is placed can move.

[0157] The incident angle of the light source 41 with respect to the laminated coating film 12 is 45° (the inclination angle measured from the perpendicular line to the surface of the laminated coating film 12). The light receiving angle θ of the sensor 42 (the inclination angle from the specular reflection direction toward the light source side) is such that the specular reflection direction is 0°.

[0158] The light receiving angle θ is set to 45° (the perpendicular direction to the surface of the laminated coating film 12), and the measurement is continuously performed in the direction parallel to the surface of the laminated coating film 12 to measure the change in the Y value. Specifically, a sample having the laminated coating film 12 is placed on a workbench (not shown), and the Y value is measured for each circular light spot region M having a specified measurement area. The workbench moves in the direction of arrow A1 at a specified speed. In this way, the Y value of the light spot region M on the surface of the laminated coating film 12 can be continuously measured in the direction of arrow A2. The light spot diameter R of the light spot region M is 0.2 mm, the measurement pitch P is 0.2 mm, and the moving speed of the workbench is 5 mm / min. Under these conditions, the Y value of each light spot region was measured. It should be noted that the measurement start position was set to 0 mm, and the measurement was continuously performed within a range of 50 mm in the measurement distance in the direction of A2 from the measurement start position.

[0159] An example of the measurement results is shown in Figure 3(b). It is considered that the Y value of the part where the bright material 21 exists is high, and the Y value of the part where the bright material 21 does not exist is low. In the change of the obtained Y value, the standard deviation of the Y value is calculated for each specified measurement distance of 5 mm, and the average value of the standard deviation is calculated, and the average value is set as the particle feeling index of the laminated coating film 12. It should be noted that, if Figure 4 As shown by the dotted line in (b), it is assumed that if the Y value is greater than 1.3, the difference in the Y value cannot be recognized by human vision, so all Y values ​​greater than 1.3 are set to 1.3.

[0160] It can be said that the smaller the value of the particle index, the more delicate, less variable and more uniform the texture.

[0161] In the case of dark colors, from the viewpoint of obtaining a vivid and deep hue despite low lightness, the graininess index is preferably 0.09 to 0.12, and more preferably 0.09 to 0.11.

[0162] It should be noted that for dark-colored laminated coatings, when the chroma shadow index and the particle index both satisfy the above-mentioned numerical ranges, while ensuring overall low brightness, it is also possible to more effectively balance the transparent bright red color rendering and the strong sense of depth.

[0163] <Optical properties of glitter layer>

[0164] Similar to the optical properties of the laminated coating film 12, only the optical properties of the glittering layer 14 were studied.

[0165] Specifically, the optical properties of a sample in which only the bright layer 14 was provided via the electrophoretic coating film 13 on the surface of the steel sheet 11A before the colored layer 15 and the colorless light-transmitting layer 16 were formed were examined in the same manner as the laminated coating film 12 .

[0166] In the laminated coating film 12, the colored layer 15 for suppressing light transmission is laminated on the upper side of the glittering layer 14. Therefore, the brightness L*(θ) of the bright part (10°≤θ≤25°) of the glittering layer 14 is preferably higher than that of the bright part of the laminated coating film 12.

[0167] On the other hand, the chroma C*(θ) of the bright part (10°≤θ≤25°) of the glittering layer 14 may be lower than the chroma C*(θ) of the bright part of the laminated coating film 12 .

[0168] By increasing the lightness L*(θ) of the highlight portion (increasing the reflectivity), the coloring material of the coloring layer 15 can be made to develop color prominently, thereby increasing the chroma C*(θ) of the highlight portion of the laminated coating film 12 .

[0169] In addition, the chroma C*(80°) of the shaded part (θ = 80°) of the light-reflecting layer 14 may also be lower than the chroma C*(80°) of the shaded part of the laminated coating film 12.

[0170] Specifically, it is preferable that the light-reflecting layer 14 satisfies the following formulas (4) to (6).

[0171] 11 ≤ L*(θ) ≤ 70 (10° ≤ θ ≤ 25°) ……(4)

[0172] 6 ≤ C*(θ) ≤ 30 (10° ≤ θ ≤ 25°) ……(5)

[0173] 0.5 ≤ C*(θ) (θ = 80°) ……(6)

[0174] In other words, L*(θ) at the bright part, that is, 10° ≤ θ ≤ 25°, is 11 or more and 70 or less, preferably 12 or more and 68 or less. In addition, C*(θ) at 10° ≤ θ ≤ 25° is 6 or more and 30 or less, preferably 6.5 or more and 25 or less.

[0175] In addition, C*(80°) representing the chroma of the shaded part is 0.5 or more, preferably 0.6 or more and 10 or less, more preferably 0.7 or more and 8 or less, and particularly preferably 1 or more and 8 or less.

[0176] By making the L* value and C* value of the light-reflecting layer 14 containing a light material satisfy the above formulas (4) to (6), it is easy to achieve the numerical ranges of the above L* value and C* value of the laminated coating film 12.

[0177] <Examples>

[0178] Hereinafter, examples of the present embodiment will be described.

[0179] A coated board having a laminated coating film (the bottom layer is an electrophoretic coating film) was produced. The laminated coating film includes the colored layer in Production Example 1 shown in Table 1 and the light-reflecting layers in Examples 1 to 9 (in this specification, sometimes represented by symbols "E1 to E9" respectively) and Comparative Examples 1 and 6 (in this specification, sometimes represented by symbols "C1, C6" respectively) shown in Table 2.

[0180] [Table 1]

[0181]

[0182] [Table 2]

[0183]

[0184] [Example 1]

[0185] A cationic electrodeposition coating was electrodeposited on a phosphatized and passivated steel sheet (substrate), and sintered at 160 °C for 30 minutes to achieve a dry film thickness of 20 μm. A first base coating for the bright layer (an acrylic emulsion-based waterborne coating) shown in Table 2 was applied to the electrodeposition coating film of the obtained coated object by using a rotary atomizing electrostatic coater, thereby forming an uncured bright layer. The average particle diameter and thickness of the brightening material, i.e., aluminum flakes, were 15 μm and 200 nm, respectively. In addition, the average particle diameter and thickness of chromium oxide flakes were 10 μm and 50 nm, respectively.

[0186] Next, a second base coating for the colored layer (an acrylic emulsion-based waterborne coating) shown in Table 1 was applied to the uncured bright layer by using a rotary atomizing electrostatic coater, thereby forming an uncured colored layer.

[0187] It should be noted that iron oxide nanoparticles (average particle diameter 50 nm) were used as the inorganic UVA in Tables 1 and 2.

[0188] Next, a two-component polyurethane clear coat was applied to the uncured colored layer by using a rotary atomizing electrostatic coater, thereby forming an uncured colorless light-transmitting layer. A benzotriazole-based UVA (CAS No. 70321-86-7 (molecular weight 447)), which is an organic ultraviolet absorber, was incorporated into the clear coat so that the PWC reached 5% by mass.

[0189] Then, the above uncured bright layer, uncured colored layer, and uncured colorless light-transmitting layer were simultaneously heated (heated at 140 °C for 20 minutes) to cure them.

[0190] The dry thicknesses of the bright layer and the colored layer were both 12 μm, and the dry thickness of the colorless light-transmitting layer was 30 μm.

[0191] It should be noted that it is also possible to preheat (heat at 80 °C for 3 minutes) after applying the first base coating and the second base coating in a wet-on-wet manner, and then bake (heat at 140 °C for 20 minutes) after applying the clear coat.

[0192] [Examples 2 to 9 and Comparative Examples 1 and 2]

[0193] A laminated coating film was formed in the same manner as in Example 1 above, except that the first base coating for the bright layer shown in Table 2 was used.

[0194] [Optical Property Evaluation 1]

[0195] Then, as shown in Table 3, the indexes of each optical property were investigated using the above method. It should be noted that the above upper limit value L*(θ1) and lower limit value L*(θ2) are L*(10°) of E1 at θ = 10°, which is 23.41, and L*(25°) of E1 at θ = 25°, which is 8.77, respectively. In addition, through the appearance visual test in which the observer observes the laminated coating film from various angles, the transparency, vividness, and depth sense of the vivid red color display with a sense of transparency were evaluated. The appearance visual test was evaluated according to four grades of "◎", "○", "△", and "×". Regarding the evaluation of the intensity of the transparency, vividness, and depth sense of the red color display, "◎" is the highest, and it decreases in the order of "○" → "△" → "×".

[0196] [Table 3]

[0197]

[0198] [Optical Property Evaluation 2]

[0199] In addition, as shown in Table 4, as Comparative Examples 2 to 5 (in this specification, sometimes represented by the symbols "C2 to C5" respectively), for the dark red coatings A to D formed on the surface of a commercially available coating material, evaluations were conducted on the same items as the evaluation items of the laminated coating film shown in Table 3.

[0200] [Table 4]

[0201]

[0202] [Discussion]

[0203] Figure 4 (a) of is a graph showing the relationship between the L* values of the laminated coating films of E1 to E4 and C1 to C5 and the light-receiving angle θ; Figure 4 (b) of is a graph showing the relationship between the C* values of the laminated coating films of E1 to E4 and C1 to C5 and the light-receiving angle θ.

[0204] As Figure 4 shown, it can be seen that among E1 to E4, the lightness L* values and C* values in the bright light part (10° ≤ θ ≤ 25°) fall within the Figure 4 area of the above numerical range indicated by the hatching of the midpoint.

[0205] In addition, in Figure 4 , the calculation methods of θ1, θ2, C*(θ1), and C*(θ2) of E1 to E4 and C1 when the upper limit value L*(θ1) and lower limit value L*(θ2) of the L* value in the bright light part are set to 23.41 and 8.77, respectively, are shown by dotted lines.

[0206] Figure 5A graph showing the relationship between the chroma shading index and the particle feeling index of E1 to E4 and C1 to C5. As Figure 5 shown, among E1 to E4, both the chroma shading index and the particle feeling index satisfy the above numerical ranges.

[0207] Figure 6 The relationship between the PWC and the average particle size of the black-based pigments (carbon black) in the light-reflecting layer of E1 to E7, C1, and C6 is shown. In E1, E2, and E5, the chroma shading index C*FF is 55 or more, and in E3, E4, E6, and E7, the chroma shading index C*FF is 50 or more. From this, it can be seen that the laminated coating film of dark red can ensure low overall lightness while achieving both vivid red color development with a transparent feeling and a strong sense of depth. From Figure 6 it can be known the preferred numerical ranges of the PWC and the average particle size of the black-based pigments in the light-reflecting layer.

[0208] In addition, regarding E8 and E9, it can also be known that in each evaluation item, the above numerical ranges are satisfied.

[0209] (Second Embodiment)

[0210] Hereinafter, other embodiments related to the present disclosure will be described in detail. It should be noted that in the description of these embodiments, the same reference numerals are given to the same parts as those in the first embodiment, and detailed descriptions thereof are omitted.

[0211] The second coloring material contained in the light-reflecting layer 14 is not limited to a red-based coloring material, and may be a coloring material of other hues. In this case, as described above, the coloring material contained in the coloring layer 15 is preferably a coloring material of the same color category as the second coloring material.

[0212] The laminated coating film of Example 10 (E10) shown in the coating composition table of Table 5 is an example in which phthalocyanine blue, a blue-based pigment, is used as the second coloring material and the coloring material.

[0213] [Table 5]

[0214]

[0215]

[0216] Regarding the laminated coating film of Table 5, it can also be known that the optical properties satisfy the requirements of the optical properties of the first embodiment, and a dark blue laminated coating film that can ensure low overall lightness while achieving both vivid blue color development with a transparent feeling and a strong sense of depth can be obtained.

[0217] -Symbol Explanation-

[0218] 11 Vehicle body

[0219] 11A steel plate

[0220] 12 laminated coating film

[0221] 13 electrophoretic coating film

[0222] 14 bright layer

[0223] 15 coloring layer

[0224] 16 colorless light-transmitting layer

[0225] 21 bright material

[0226] 21A high-reflection scale

[0227] 21B low-reflection scale

[0228] 23 black-based pigment (first coloring material)

[0229] 24 bright layer red-based pigment (second coloring material)

[0230] 25 coloring layer red-based pigment (coloring material)

Claims

1. A laminated coating film, characterized in that: The laminated coating film includes a bright layer and a colored layer. The bright layer contains a bright material and is formed directly or indirectly on the surface of an object to be coated. The colored layer is laminated on the bright layer. The colored layer contains a coloring material and has translucency. When the light incident angle is set to 45° and the light receiving angle is θ, and the lightness L* value and chroma C* value of the reflected light measured are set as L*(θ) and C*(θ) respectively, the laminated coating film satisfies the following formulas (1) to (3). 5 ≤ L*(θ) ≤ 25 (10° ≤ θ ≤ 25°)......(1) 20 ≤ C*(θ) ≤ 65 (10° ≤ θ ≤ 25°)......(2) 2≤C*(80°)……(3)。 2. The laminated coating film according to claim 1, characterized in that: When the θ values at which L*(θ) of the laminated coating film becomes the upper limit value and the lower limit value are set as θ1 and θ2 respectively. For the laminated coating film, the coefficient k satisfying C*(θ1) = k × C*(θ2) is 0.03 or more and 0.5 or less, where 10° ≤ θ ≤ 25°.

3. The laminated coating film according to claim 1 or 2, characterized in that: If the θ values at which L*(θ) of the laminated coating film becomes the upper limit value and the lower limit value are set as θ1 and θ2 respectively. If the difference ΔC* = C*(θ1) - C*(80°) between C*(θ1) and C*(80°) is set as the chroma shadow feeling index, then this chroma shadow feeling index is 50 or more, where 10° ≤ θ ≤ 25°.

4. The laminated coating film according to claim 1 or 2, characterized in that: When the light receiving angle θ is set to 45°, in the change of the Y value of the laminated coating film measured continuously in the direction parallel to the surface of the laminated coating film, if the average value of the standard deviation of the Y value calculated for each specified measurement distance is set as the particle feeling index of the laminated coating film, then this particle feeling index is 0.09 or more and 0.12 or less.

5. The laminated coating film according to claim 1 or 2, characterized in that: The bright layer satisfies the following formulas (4) to (6). 11 ≤ L*(θ) ≤ 70 (10° ≤ θ ≤ 25°)......(4) 6 ≤ C*(θ) ≤ 30 (10° ≤ θ ≤ 25°)......(5) 0.5≤C*(80°)……(6)。 6. The laminated coating film according to claim 1 or 2, characterized in that: The bright layer contains a first coloring material and a second coloring material. The first coloring material is a black-based coloring material. The second coloring material is a coloring material of a color other than black-based.

7. The laminated coating film according to claim 6, characterized in that: The solid content concentration of the first coloring material in the bright layer is 1% by mass or more and 20% by mass or less.

8. The laminated coating film according to claim 6, characterized in that: The solid content concentration of the second coloring material in the bright layer is 1% by mass or more and 20% by mass or less.

9. The laminated coating film according to claim 6, characterized in that: The first coloring material is a black-based pigment. The second coloring material is a red-based pigment.

10. The laminated coating film according to claim 1 or 2, wherein: the coloring material contained in the coloring layer is a red-based pigment, the solid content concentration of the red-based pigment in the coloring layer is 1% by mass or more and 17% by mass or less.

11. A coated article, wherein: the coated article includes the laminated coating film according to claim 1 or 2.

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