Metallic-effect pigment composition, metallic-effect coating comprising same, and application thereof

Abstract

Disclosed are a metallic-effect pigment composition, a metallic-effect coating comprising same, and an application thereof. The metallic-effect pigment composition comprises the following components: at least one aluminum powder pigment and a pearlescent pigment, wherein the pearlescent pigment at least comprises at least one silver pearlescent pigment and at least one white pearlescent pigment; and a mass ratio of the pearlescent pigment to the aluminum powder pigment is 1:0.8-1:3. After the metallic-effect pigment composition is incorporated into a metallic-effect coating, the metallic-effect pigment composition can provide the metallic-effect coating with good radar transmittance, and good hiding power and appearance (including metallic effect, brightness, sparkle, angle-dependent lightness, especially lightness at small viewing angles, etc.).

Description

Metallic effect pigment compositions, metallic effect coatings containing the same, and their applications. Technical Field

[0001] This invention relates to the field of metallic effect coatings. More specifically, it relates to a metallic effect pigment composition, a metallic effect coating comprising the same, and its application. Background Technology

[0002] With the development of automotive technology, people have increasingly higher demands for driving experience. Radar, as a component that can provide multiple functions such as obstacle detection, collision avoidance, navigation, and speed measurement, occupies an increasingly larger proportion in the automotive production field. The rise of autonomous driving technology in recent years has placed even higher demands on radar capabilities. Radars typically mounted behind bumpers or other vehicle components operate in the 24GHz or 77-81GHz bands. Among these, 77-81GHz band radars have gained wider application due to their small size, strong anti-interference capabilities, and policy approvals. Furthermore, because the wavelength of 77-81GHz band radar falls within the 1-10mm millimeter wave band, it is called millimeter-wave radar. Millimeter-wave radar features excellent penetration, anti-interference capabilities, and a small footprint, allowing it to identify targets even through plastic substrates (polypropylene, polycarbonate, etc.). In the automotive field, millimeter-wave radars are protected by obstructions (such as some plastic components on a car).

[0003] However, to achieve a better vehicle appearance, these coverings on the exterior surface of a car are generally coated with paint, such as metallic effect paint. Metallic effect paint is a type of paint containing flake-like metallic pigments (most commonly aluminum powder). It is favored by consumers for its metallic luster, angle-dependent color effect, shimmering properties, and good weather resistance, providing a striking visual appearance for vehicles. To achieve specific design effects, the amount of aluminum powder added to metallic effect paint is generally 2-7 wt%. Too little aluminum powder will not produce the desired performance; too much will cause many problems in terms of silver powder arrangement, spraying process, and storage stability. Furthermore, as an electromagnetic wave, millimeter-wave radar lacks the energy to penetrate metallic media. According to electrodynamics, for a good conductor like aluminum, the penetration depth of millimeter-wave radar is only about a few hundred nanometers. The indispensability of aluminum pigment and the need to improve radar transmittance are contradictory.

[0004] Aluminum pigments are thin, flake-like effect pigments obtained through grinding, typically with a size of 5-50 μm and a thickness of approximately several hundred nanometers. Their outer surface usually contains various additives, such as oleic acid, added during the grinding process. The aluminum pigments commonly used in automobiles are 10-25 μm in size, resembling silver coins, possessing high brightness, a delicate yet intense metallic appearance, and unique properties that are difficult to replace. Furthermore, it should be noted that the final effect of aluminum pigments in coatings is influenced by many factors, such as formulation components, spraying process, storage conditions, baking conditions, coating process, and raw material quality. During testing, the results of coating formulations often exhibit significant fluctuations, posing certain challenges to development.

[0005] Generally, aluminum powder effect pigments are used in paint layers, with a thickness of approximately 12-18 μm. Within the paint layer, these flake-like pigments are arranged in parallel, forming a continuous, multi-layered, sheet-like structure. The radar frequencies used in sensors are 77-81 GHz, corresponding to a wavelength of approximately 4 mm. Although this wavelength is much larger than the size of a single metallic effect pigment (approximately 5-40 μm) and theoretically should not be blocked, the densely packed aluminum powder pigments form a structure resembling a multi-layered, integral aluminum film, thus causing signal loss to the radar signal. For coatings with lower aluminum powder pigment content, the loss is less due to the greater number of gaps, allowing radar waves to diffract. However, for coatings with higher aluminum powder pigment content, the gaps are fewer, resulting in significant loss. In mid-to-high-end coatings, where high aesthetic requirements are necessary, a higher aluminum powder pigment content (aluminum powder, colored aluminum, or other metallic pigments) is required, leading to radar wave loss of 3-5 dB, which is undesirable. Simply reducing the amount of aluminum powder pigment used would significantly impact various performance characteristics such as brightness, opacity, and flicker effect, making it impractical. Summary of the Invention

[0006] In view of the above problems, the object of the present invention is to provide a metallic effect pigment composition, a metallic effect coating comprising the same, and its application. The metallic effect coating comprising this metallic effect pigment composition has good radar transmittance and exhibits an excellent metallic effect appearance when used for coating plastic parts.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] On one hand, the present invention provides a metallic effect pigment composition comprising the following components:

[0009] At least one aluminum powder pigment; and

[0010] Pearl pigments, comprising at least one silver pearl pigment and at least one white pearl pigment;

[0011] The mass ratio of the pearlescent pigment to the aluminum powder pigment is 1:0.8-1:3.

[0012] Furthermore, the mass ratio of the silver pearlescent pigment to the white pearlescent pigment is 1.5:1 to 10:1.

[0013] Furthermore, the silver pearlescent pigment is a flake-shaped pigment containing an iron oxide or titanium iron oxide coating layer, the substrate of the flake-shaped pigment is selected from mica flakes, alumina flakes, titanium dioxide flakes or glass flakes, and the flake-shaped pigment has a silver powder appearance.

[0014] Furthermore, the D50 of the silver pearlescent pigment ranges from 5 to 50 μm, and the average thickness is 100 to 1000 nm.

[0015] Furthermore, the white pearlescent pigment is a mica sheet, glass sheet, or alumina sheet with or without oxide coating.

[0016] Furthermore, the D50 of the white pearlescent pigment ranges from 5 to 50 μm, and the average thickness is 100 to 1000 nm.

[0017] Furthermore, the aluminum powder pigment has a solid content of 65%-75% and a D50 of 5-30 μm.

[0018] In another aspect, the present invention provides a metallic effect coating with good radar transmittance, wherein the raw materials forming the coating include:

[0019] Film-forming resin, and

[0020] The metallic effect pigment composition as described above.

[0021] Furthermore, the metallic effect coating is a colored paint.

[0022] Furthermore, the raw material contains 1-7 wt% of the metallic effect pigment composition by weight percentage.

[0023] In another aspect, the present invention provides a metallic effect coating with good radar transmittance, which is prepared from the metallic effect coating described above.

[0024] Furthermore, the dry film thickness of the coating is 10-18 μm.

[0025] In another aspect, the present invention provides the use of the metallic effect coating described above for forming a coating film with good radar transmittance on a plastic substrate.

[0026] Furthermore, the plastic substrate is a plastic substrate for automotive plastic parts or smart devices.

[0027] Furthermore, the automotive plastic component is a car bumper.

[0028] The beneficial effects of this invention are as follows:

[0029] The metallic effect pigment composition provided in this invention, by using pearlescent pigments in a specific proportion and composition to partially replace aluminum powder pigments, when this composition is used in coatings (paints), the resulting coating has almost identical appearance performance compared to a coating containing only aluminum powder pigments. The color difference can be controlled to ΔE<1.5, especially the brightness at small angles (15° and 25°) is very similar, and the color variation with angle and the shimmering performance are equally excellent, making it directly applicable for commercial use. Attached Figure Description

[0030] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0031] Figure 1 shows a schematic diagram of millimeter-wave lidar penetrating a plastic substrate and coating.

[0032] Figure 2 shows an SEM image of the coating cross-section in Example 3. Detailed Implementation

[0033] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0034] Metallic effect coatings commonly used in automobiles typically contain 1-6 wt% aluminum powder. The higher the aluminum powder content in the coating, the more closely the aluminum powder in the resulting coating forms a dense, continuous, multi-layered structure. This leads to greater loss when radar millimeter waves penetrate such a coating.

[0035] Some publicly available radar-compatible coatings with metallic effects either have high radar transmittance but poor performance in terms of substrate coverage, color difference, or small-angle brightness; or they have good coating effect on the substrate but excessive radar loss.

[0036] For coating plastic parts used to block millimeter-wave radar (e.g., automotive plastic parts, specifically car bumpers), in order to achieve a good balance between good radar transmittance and excellent metallic effect in the coating of plastic parts, and to realize a truly commercially viable and perfect alternative to aluminum powder pigments, one specific embodiment of the present invention provides a metallic effect pigment composition comprising the following components:

[0037] At least one aluminum powder pigment; and

[0038] Pearl pigments, comprising at least one silver pearl pigment and at least one white pearl pigment;

[0039] The mass ratio of the pearlescent pigment to the aluminum powder pigment is 1:0.8-1:3.

[0040] In this metallic effect pigment composition, silver pearlescent pigment and white pearlescent pigment are selected as pearlescent pigments, and the pearlescent pigments are mixed with aluminum powder pigments in a certain mass ratio. When this metallic effect pigment composition is used in metallic effect coatings, it can give the metallic effect coatings good radar transmittance, good hiding power and appearance (including metallic feel, brightness, shimmering, multi-angle brightness (especially small angle brightness) effect, etc.).

[0041] Pearlescent pigments exhibit similar angle-dependent color variation, high brightness, and shimmering effects to aluminum pigments, but their hiding power is significantly lower. Combinations of multiple pearlescent pigments can improve brightness at various angles. However, for coating systems primarily composed of aluminum pigments, excessive addition of pearlescent pigments may affect the arrangement of both the aluminum and pearlescent pigments, leading to lower brightness and altered shimmering properties.

[0042] In some preferred examples, the mass ratio of the pearlescent pigment to the aluminum powder pigment is, but is not limited to, 1:1 to 1:3. In this case, the aforementioned effects are better. In some specific examples, the mass ratio of the pearlescent pigment to the aluminum powder pigment is, but is not limited to, 1:1 to 1:2.5, 1:1 to 3:7, 1:1, 3:7, etc.

[0043] In this embodiment, suitable aluminum powder pigments can be those commonly used in automotive metallic effect coatings; no further requirements are specified. Preferred aluminum powder pigments refer to flake-shaped aluminum pigments prepared by grinding spherical aluminum powder, exhibiting a silvery metallic appearance. One or more aluminum powder pigments can be selected according to actual production needs. These aluminum powder pigments have structures in the shape of silver dollars, cornflakes, or other suitable shapes. Suitable aluminum powder pigments have a solid content of 65%-75%, a D50 of 5-30 μm, preferably 5-25 μm, more preferably 9-15 μm, which helps to obtain a coating with a finer and brighter metallic effect, or 16-25 μm, which helps to obtain a coating with a strong shimmering metallic effect.

[0044] Exemplary aluminum powder pigments include, but are not limited to, those selected from Toyo Aluminium's 4660NS (D50 of 9µm) and 6220NS (D50 of 18µm). It should be noted that the results show that using aluminum powder from other suppliers does not affect the technical effects of this invention.

[0045] It is understood that in this embodiment, the pearlescent pigment includes one or more silver pearlescent pigments and one or more white pearlescent pigments.

[0046] In this embodiment, the exemplary silver pearlescent pigment refers to a flake-shaped pigment containing an iron oxide or titanium iron oxide coating layer. The substrate of the flake-shaped pigment may be mica flakes, alumina flakes, titanium dioxide flakes, glass flakes, etc., containing or not containing titanium oxide, and the flake-shaped pigment has a silver powder appearance.

[0047] In this embodiment, the silver pearlescent pigment has high hiding power. High hiding power means that when used at an addition amount of 5 wt% and a spray thickness of 15 μm, the resulting coating has a hiding power of less than 50 μm on black and white checkered paper, more preferably less than 30 μm.

[0048] In some examples, the D50 of the silver pearlescent pigment ranges from 5 to 50 μm, and the average thickness is 100 to 1000 nm.

[0049] In some preferred examples, the D50 of the silver pearlescent pigment is preferably 5-40 μm. By controlling the D50 of the silver pearlescent pigment, different brightness, hiding power, and angle-dependent color effects can be achieved, depending on the product requirements.

[0050] Exemplary silver pearlescent pigments include, but are not limited to, Merck’s iriodin series 9602, 9605, and 9612, or Merck’s xirallic series T61-10WNT microsilver, and ECAR’s OEM opaque silver series.

[0051] In this embodiment, the white pearlescent pigment may be mica flakes, glass flakes, alumina flakes, or other materials that are coated with or not coated with oxides.

[0052] In this embodiment, the white pearlescent pigment may not have a metallic appearance. In some examples, the D50 of the white pearlescent pigment ranges from 5 to 50 μm, and the average thickness is 100 to 1000 nm.

[0053] In some preferred examples, the D50 of the white pearlescent pigment is preferably 5-40 μm. By controlling the D50 of the white pearlescent pigment, different brightness, hiding power, and angle-dependent color effects can be achieved, depending on the product requirements.

[0054] Exemplary white pearlescent pigments include, but are not limited to, Merck's iriodin series 9121 or 9119, Merck's xirallic series T60-10WNT crystal silver (i.e., Xirallic T61-10), and ECAR's OEM silver series.

[0055] During our research, we discovered that the mass ratio of silver to white pearlescent pigments in the pearlescent pigment composition affects the hiding power, multi-angle brightness, and shimmer of the resulting coating. In some examples, the mass ratio of silver to white pearlescent pigment is 1.5:1 to 10:1. In some preferred examples, the mass ratio of silver to white pearlescent pigment is, but is not limited to, 2:1 to 10:1, 2:1 to 5:1, 2:1 to 4:1, 2:1, and 4:1, in which case the aforementioned effects are even better.

[0056] According to another specific embodiment of the present invention, a metallic effect coating with good radar transmittance is provided, wherein the raw materials forming the coating include:

[0057] Film-forming resin, and

[0058] The metallic effect pigment composition as described above.

[0059] In this embodiment, the metallic effect coating is an oil-based coating, which can be used as a color paint. This metallic effect coating is preferably used in the coating of automotive plastic parts. When applied to automotive plastic parts, this metallic effect coating not only provides excellent hiding power and a good appearance (including metallic feel, brightness, shimmer, and multi-angle brightness (especially small-angle brightness) effects), but also has good radar transmittance, making it commercially viable.

[0060] For example, the automotive plastic parts include, but are not limited to, bumpers. Preferably, the automotive plastic parts are plastic parts used to shield millimeter-wave radar.

[0061] For example, the materials of the automotive plastic parts include, but are not limited to, PP, ABS, PC, etc.

[0062] For example, the film-forming resin in this embodiment may be acrylate, acrylic resin, etc.

[0063] It is understood that the raw materials forming the metallic effect coating may also contain organic solvents (such as butyl acetate), and other additives, such as thickeners and rheology modifiers, may be added as needed.

[0064] In some examples, the raw material contains 1-7 wt% of the metallic effect pigment composition. This amount of metallic effect pigment imparts to the metallic effect coating superior radar transmittance, while maintaining an appearance and hiding power equal to or better than that of metallic effect pigments containing only pure aluminum powder pigments.

[0065] The metallic effect coating in this embodiment can be prepared by mixing the components.

[0066] For example, in some preparation methods, the metallic effect coating is dispersed and then added to a raw material containing a film-forming resin, and then mixed to obtain the coating.

[0067] It should be noted that, in the metallic effect coating of this embodiment, apart from the pigments selected from the metallic effect pigment composition of this embodiment, the other components, such as film-forming resins, solvents, and other additives, can be conventional selections and addition amounts found in conventional metallic effect coatings.

[0068] According to another specific embodiment of the present invention, a metallic effect coating with good radar transmittance is provided, which is prepared from the metallic effect coating as described above.

[0069] Specifically, the metallic effect coating is obtained by applying the metallic effect paint to a substrate and then curing it. A suitable application method is spraying, which allows the flake-like pigments to be better arranged on the substrate.

[0070] For example, the dry film thickness of the coating is 10-18 μm.

[0071] It is understandable that, since the metallic effect coating is prepared from the metallic effect pigment, the metallic effect coating has the effect brought about by the metallic effect pigment, which will not be elaborated here.

[0072] According to yet another specific embodiment of the present invention, the metallic effect coating described above is provided for use in forming a coating film with good radar transmittance on a plastic substrate.

[0073] It is understood that the coating formed here can be a metallic effect coating as described above.

[0074] For example, the metallic effect coating is applied to a plastic substrate and cured into a film to obtain the paint film.

[0075] An exemplary method for forming a coating with good radar transmittance on the plastic substrate includes the following steps:

[0076] The primer, the metallic effect coating, the topcoat, and / or clear varnish are sequentially sprayed onto the plastic substrate and then baked to obtain the final product.

[0077] In some specific examples, the baking temperature is 60-80°C and the time is 20-30 minutes.

[0078] For example, a schematic diagram of the effect of millimeter-wave radar on the coating is shown in Figure 1 below. In Figure 1, the black ellipse in the Basecoat represents aluminum powder pigment, and the white ellipse represents pearlescent pigment. As can be seen from Figure 1, after the millimeter wave passes through the substrate, primer, color paint, and clear coat in sequence, the radar transmission experiences very little loss.

[0079] In some examples, the plastic substrate is a plastic substrate for automotive plastic parts or smart devices.

[0080] In some examples, the automotive plastic components or plastic substrates include, but are not limited to, bumpers, and their materials include, but are not limited to, PP, ABS, PC, etc. The automotive plastic components are preferably plastic components used to shield millimeter-wave radar.

[0081] The technical solution of the present invention will be described below with reference to some specific embodiments:

[0082] The raw materials involved in specific embodiments of the present invention are described below:

[0083] The aluminum powder pigments used are Toyo Aluminium's 4660NS (D50 of 9µm) and 6220NS (D50 of 18µm). It should be noted that the results show that using aluminum powder from other suppliers does not affect the technical effect of this invention.

[0084] Pearl pigments:

[0085] Silver pearlescent pigments are selected from: Merck's iriodin series 9602, 9605, 9612, or Merck's xirallic series T61-10WNT microsilver, and Aika's OEM opaque silver series (superfine, fine, medium), etc.

[0086] White pearlescent pigments are selected from: Merck's iriodin series 9121 or 9119, Merck's xirallic series T60-10WNT crystalsilver, and ECAR's OEM silver series (superfine, fine, medium) for white appearance, etc.

[0087] Of course, the available pearlescent pigments are not limited to the suppliers mentioned above.

[0088] Coating system: Nippon Paint's solvent-based base products for plastic parts were selected, including Pin 600 intense color base and Pin 600 light color base. The formulations of Pin 600 intense color base and Pin 600 light color base are shown in Table 1 and Table 2 below, respectively.

[0089] The raw material ratio of the pin600 intense color base material is as follows:

[0090] Table 1

[0091] The raw material ratio of the pin600 light color base material is as follows:

[0092] Table 2

[0093] The solvent used is butyl acetate, a commonly used organic solvent in coatings. Other solvents such as xylene can also be used.

[0094] Comparative Examples 1-5

[0095] Comparative Examples 1-5 provide a coating whose raw material composition is shown in Table 3 below.

[0096] The preparation of this coating includes the following steps:

[0097] The aluminum powder pigment is dispersed using an organic solvent and then mixed with the base material to obtain the coating.

[0098] Table 3

[0099] Table 3 above shows a comparative example of different addition amounts of aluminum powder pigments for models 4660NS and 6220NS. The purpose is to clearly show the impact of different addition amounts of aluminum powder pigments on the technical effect and to further confirm the significant improvement effect brought about by the addition of pigments.

[0100] Comparative Examples 6-9

[0101] Comparative Examples 6-9 provide a coating whose raw material composition is shown in Table 4 below.

[0102] The preparation of this coating includes the following steps:

[0103] The coating is obtained by dispersing aluminum powder pigment and pearlescent pigment with an organic solvent and then mixing them with the base material.

[0104] Table 4

[0105] Table 4 above shows the comparative effects of adding silver or white pearlescent pigments alone on the basis of adding aluminum powder pigments, in order to verify the advantages of the metallic pigment composition scheme of the present invention.

[0106] Examples 1-6

[0107] A metallic effect coating with good radar transmittance is described in Table 5 below.

[0108] The preparation of this coating includes the following steps:

[0109] The coating is obtained by dispersing aluminum powder pigment and pearlescent pigment with an organic solvent and then mixing them with the base material.

[0110] Table 5

[0111] The application method of the above-mentioned metallic effect coatings is as follows:

[0112] Spray (using an ecogun machine) Flex 700 primer (Nippon Paint product), metallic effect paint of the present invention embodiment or comparative example, and Flex 200 Nippon Paint product on a 3mm thick PP board (150*200mm) in sequence, with the thicknesses shown in Table 6 below. Then place it flat in an oven and bake at 80℃ for 30 minutes, and then perform the following index tests.

[0113] Table 6

[0114] Performance testing:

[0115] Optical properties were tested using a BYK-MAC tester;

[0116] Radar transmission loss was tested using a Rohdeschwarz QAR device.

[0117] The properties of the above-mentioned metallic effect coatings after coating are shown in Table 7 below.

[0118] Table 7

[0119] In Table 7, regarding performance ΔE, the following information is provided:

[0120] Reference 1 refers to the E value in Comparative Example 1 as a reference. When the aluminum powder pigment in the formulations of other embodiments or comparative examples is 4660 NS, the absolute value of the difference between the E value of the coating obtained by the coating film of these embodiments or comparative examples and the E value in Comparative Example 1 is the ΔE value corresponding to that embodiment or comparative example;

[0121] Reference 2 refers to the E value in Comparative Example 4 as a reference. When the aluminum powder pigment in the formulations of other embodiments or comparative examples is 6220NS, the absolute value of the difference between the E value of the coating obtained by the coating film of these embodiments or comparative examples and the E value in Comparative Example 4 is the ΔE value corresponding to that embodiment or comparative example.

[0122] As can be seen from Table 7 above:

[0123] 1) Comparative Examples 1-5 show that as the amount of silver powder used is continuously reduced, several indicators of the metallic effect coating change, including an increase or decrease in brightness at small angles (L15°) and medium angles (L45°), a larger color difference (△E), an increase in dynamic index (FI), and a decrease in hiding power.

[0124] 2) Comparative Examples 6-9 show that the use of a single pearlescent pigment can reduce color difference and improve brightness (L) to a certain extent, but the dynamic index will be significantly affected, while the flicker (G) and hiding power are not significantly different compared with the same amount of silver powder.

[0125] 3) Examples 1-2 show that, surprisingly, the replacement of the pearlescent composition with about 30 wt% has very close properties to pure aluminum powder pigments, exhibiting very small small-angle brightness deviation, low color difference, and almost identical dynamic index and scintillability, with only a slight reduction in hiding power, because the hiding power of pearlescent pigments cannot achieve the effect of aluminum powder.

[0126] 4) Examples 3-4 show that the deviation of various indicators is slightly larger for the substitution of 50 wt% pearlescent composition than for the substitution of 30 wt%, which is understandable, but still better than simply reducing the amount of silver powder by 50 wt%. It should be noted that silver pearlescent pigment and white pearlescent pigment show a certain synergy, and the addition of white pearlescent pigment can improve the brightness of the coating, etc.

[0127] 5) Examples 5-6 show that, for replacing large-particle-size aluminum powder pigments (18µm), the pearlescent compositions in the above examples are slightly less effective than those for smaller-particle-size aluminum powder pigments (9µm). This is because the pearlescent composition exhibits strong angle-dependent color variation. Targeted adjustments to the type of pearlescent pigment can achieve the same good replacement effect. These embodiments only demonstrate the effectiveness of the technical solutions and do not list replacement solutions for every type of aluminum powder. Generally, aluminum powder pigments with a D50 of 9-15µm can achieve a delicate and bright metallic effect, while larger particle sizes (16-25µm) result in a stronger shimmering effect, each with its own application advantages. The excellent replacement effect shown by the above examples for small-particle-size pigments demonstrates their application advantages in automotive scenarios.

[0128] 6) The test results of radar loss show that reducing the amount of silver powder reduces radar loss accordingly, which is in line with theoretical expectations. Moreover, comparing the data of simply reducing the amount of silver powder and adding alternative pearlescent pigments, it can be seen that pearlescent powder has no effect on loss. The table shows that when 30% of the pearlescent pigments replace silver powder, the transmission loss can be reduced by 38.9%, and when 50% of the pearlescent pigments replace silver powder, the transmission loss can be reduced by 63.9%. On the one hand, the pearlescent pigments with lower dielectric constants replace the conductive aluminum pigments, and on the other hand, the addition of pearlescent pigments increases the gaps between aluminum pigments, thereby enhancing the transmission and diffraction capabilities of millimeter-wave radar.

[0129] The gloss and sharpness of the coatings from representative Examples 1 and 3 were tested, and the results are shown in Table 8 below. Table 8 shows that the substitution of pearlescent pigments does not affect the gloss and sharpness of the coatings (this is only for comparison to illustrate the effect of pearlescent pigments; the specific values ​​can be adjusted according to the formulation, process, and specifications). The cross-sectional SEM image of Example 3 (as shown in Figure 2) also shows that the silver powder / pearlescent composition mixed pigments are well-arranged, and the presence of the pearlescent composition did not cause any change in the arrangement of the silver powder.

[0130] Table 8

[0131] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A metallic effect pigment composition, characterized in that, It contains the following components: At least one aluminum powder pigment; and Pearl pigments, comprising at least one silver pearl pigment and at least one white pearl pigment; The mass ratio of the pearlescent pigment to the aluminum powder pigment is 1:0.8-1:

3.

2. The metallic effect pigment composition according to claim 1, characterized in that, The mass ratio of the silver pearlescent pigment to the white pearlescent pigment is 1.5:1-10:1; Preferably, the silver pearlescent pigment is a flake pigment containing an iron oxide or titanium iron oxide coating layer, the substrate of the flake pigment is selected from mica flakes, alumina flakes, titanium dioxide flakes or glass flakes, and the flake pigment has a silver powder appearance; Preferably, the D50 of the silver pearlescent pigment is in the range of 5-50 μm, and the average thickness is 100-1000 nm; Preferably, the white pearlescent pigment is a mica sheet, glass sheet, or alumina sheet with or without oxide coating; Preferably, the white pearlescent pigment has a D50 range of 5-50 μm and an average thickness of 100-1000 nm.

3. The metallic effect pigment composition according to claim 1, characterized in that, The aluminum powder pigment has a solid content of 65%-75% and a D50 of 5-30 μm.

4. A metallic effect coating with good radar transmittance, characterized in that, The raw materials used to form the coating include: Film-forming resin, and The metallic effect pigment composition as described in any one of claims 1-3.

5. The metallic effect coating according to claim 4, characterized in that, The raw material contains 1-7 wt% of the metallic effect pigment composition by weight percentage.

6. A metallic effect coating with good radar transmittance, characterized in that, It is prepared from the metallic effect coating as described in claim 4 or 5.

7. The metallic effect coating according to claim 6, characterized in that, The dry film thickness of the coating is 10-18 μm.

8. The use of the metallic effect coating as described in claim 4 or 5 for forming a coating film with good radar transmittance on a plastic substrate.

9. The use according to claim 8, characterized in that, The plastic substrate is a plastic substrate for automotive plastic parts or smart devices.

10. The use according to claim 9, characterized in that, The aforementioned automotive plastic component is a car bumper.

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