Laminate

Abstract

To provide a laminate that can improve an external appearance while securing electromagnetic wave transmissivity.SOLUTION: A vehicle component 13 is applied to a vehicle 11 on which a millimeter-wave radar device 12 that sends and receives a millimeter-wave is mounted, is arranged ahead a transmission direction of a millimeter-wave in the millimeter-wave radar device 12, and transmits the millimeter-wave. The vehicle component 13 comprises a synthetic-resin substrate layer 14, and a color-developing layer 16 in which metal filler is dispersed on a coating film. The color-developing layer 16 has millimeter-wave transmissivity and has a dielectric constant of 4.0 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate that transmits electromagnetic waves. [Background technology]

[0002] Conventionally, a vehicle part as disclosed in Patent Document 1 has been known as an example of a laminate. Such a vehicle part has a substrate and a coating film. From the viewpoint of ensuring the electromagnetic wave permeability of the vehicle part, it is considered preferable that the relative dielectric constants of the substrate and the coating film are equal and are 3.0 or less. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4158646 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned vehicle parts, if electromagnetic wave permeability is ensured by adding a metallic filler to the coating film and setting the relative dielectric constant of the coating film to 3.0 or less, the filler content in the coating film will be insufficient, which will result in a coating film that does not have sufficient metallic luster, potentially resulting in a poor appearance. [Means for solving the problem]

[0005] Various aspects of the laminate for solving the above problems will be described below. [Embodiment 1] A laminate that transmits electromagnetic waves, comprising a base layer made of synthetic resin and a coloring layer containing a metal filler, wherein the coloring layer is electromagnetically transparent and has a relative dielectric constant of 4.0 or greater.

[0006] The inventors of the present application discovered that there is a positive linear relationship between the amount of filler contained in the color-forming layer [(weight of filler contained in the color-forming layer / total weight of the color-forming layer after drying) × 100%] and the relative dielectric constant of the color-forming layer. Therefore, according to the above configuration, by setting the relative dielectric constant of the color-forming layer, which has electromagnetic wave transparency, to 4.0 or more, the filler content of the color-forming layer increases, thereby improving the appearance. Therefore, the appearance can be improved while maintaining electromagnetic wave transparency.

[0007] [Aspect 2] The laminate according to [Aspect 1], wherein the thickness of the color-developing layer is in the range of 3 μm to 75 μm. According to the above configuration, by setting the thickness of the coloring layer to 75 μm or less, sufficient electromagnetic wave transparency can be ensured even when a coloring layer with a relative dielectric constant of 4.0 or more is used. On the other hand, by setting the thickness of the coloring layer to 3 μm or more, the coloring of the coating film is ensured, so a good appearance can be maintained. Therefore, a good appearance can be maintained while ensuring sufficient electromagnetic wave transparency.

[0008] [Aspect 3] The laminate according to [Aspect 2], characterized in that the amount of the filler contained in the color-forming layer is 2.0% or more, and the relative dielectric constant of the color-forming layer is 8.0 or more. According to the above configuration, by setting the amount of filler contained in the color-forming layer to 2.0% or more and the relative dielectric constant of the color-forming layer to 8.0 or more, the amount of filler contained in the color-forming layer can be further increased, which contributes to further improving the appearance. [Effects of the Invention]

[0009] The present invention has the effect of improving the appearance while ensuring electromagnetic wave transparency. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view illustrating a vehicle component according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram of a coloring layer in a vehicle part. [Figure 3]1 is a graph showing the relationship between the amount of aluminum and the relative dielectric constant in coloring layers A to E. [Figure 4] 10 is a graph showing the results of calculating the relationship between the thickness of the base layer and the attenuation of transmitted millimeter waves in a vehicle component having a coloring layer A and a vehicle component having a coloring layer E. [Figure 5] 10 is a graph showing the results of a comparison of the amount of attenuation of millimeter waves when the thickness of the base layer is optimized and when the thickness of the base layer is not optimized, for a vehicle part having a coloring layer A and a vehicle part having a coloring layer E. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment in which the laminated body is embodied in a vehicle part will be described below with reference to the drawings. In the following description, the forward direction of the vehicle will be referred to as the front, and the reverse direction will be referred to as the rear. As shown in Fig. 1, a millimeter-wave radar device 12 for forward monitoring, which is an example of a radar device that transmits and receives electromagnetic waves, is mounted at the front end of a vehicle 11. The millimeter-wave radar device 12 has the function of transmitting millimeter waves, which are electromagnetic waves, toward the front outside the vehicle and receiving millimeter waves reflected by objects outside the vehicle. Millimeter waves are radio waves with a wavelength of 1 mm to 10 mm and a frequency of 30 GHz to 300 GHz.

[0012] As described above, the millimeter-wave radar device 12 transmits millimeter waves toward the front of the vehicle 11, and therefore the transmission direction of millimeter waves by the millimeter-wave radar device 12 is a direction from the rear to the front of the vehicle 11. The front in the transmission direction of millimeter waves roughly coincides with the front of the vehicle 11, and the rear in the transmission direction of millimeter waves roughly coincides with the rear of the vehicle 11. For this reason, in the following description, the front in the transmission direction of millimeter waves will be simply referred to as "front," "front," etc., and the rear in the transmission direction of millimeter waves will simply be referred to as "rear," "rear," etc.

[0013] <Vehicle parts 13> 1, a substantially plate-shaped vehicle component 13, which is an example of a laminate that transmits millimeter waves (electromagnetic waves), is disposed in front of the millimeter-wave radar device 12. The vehicle component 13 is formed, for example, by an emblem, a front grille, a front bumper, or the like of the vehicle 11. The vehicle component 13 is disposed in an upright position with its front surface facing forward of the vehicle 11 and its rear surface facing rearward of the vehicle 11. The front surface of the vehicle component 13 constitutes the design surface of the vehicle component 13.

[0014] The vehicle part 13 includes a base layer 14 made of synthetic resin, a primer layer 15 provided on the front surface of the base layer 14, a color-developing layer 16 provided on the front surface of the primer layer 15, and a clear coat layer 17 provided on the front surface of the color-developing layer 16. The primer layer 15 is formed of a coating film for undercoating. The clear coat layer 17 is formed of a colorless and transparent coating film for topcoating.

[0015] <Base material layer 14> 1, the base layer 14 is formed into a plate shape by, for example, injection molding using a synthetic resin material that is permeable to millimeter waves (electromagnetic waves). The synthetic resin material used to form the base layer 14 may be transparent or opaque.

[0016] Examples of synthetic resin materials used to form the base layer 14 include polypropylene (PP) resin, polycarbonate (PC) resin, acrylonitrile-butadiene-styrene copolymer (ABS) resin, acrylonitrile-ethylene-propylene-diene-styrene (AES) resin, polymethyl methacrylate (PMMA) resin, acrylonitrile-styrene-acrylate copolymer (ASA) resin, and PMMA resin containing ASA resin.

[0017] <Coloring layer 16> As shown in FIG. 2, the coloring layer 16 is formed by dispersing a plurality of metallic (in this example, aluminum) fillers 18 in an intermediate coating film 19. That is, the coloring layer 16 contains a plurality of metallic fillers 18. Gaps are formed between the fillers 18. This allows the coloring layer 16 to transmit millimeter waves (electromagnetic waves). The coloring layer 16 is set to have a relative dielectric constant of 4.0 or higher.

[0018] The thickness of the coloring layer 16 is preferably set in the range of 3 μm to 75 μm. The thickness of the coloring layer 16 is more preferably set in the range of 5 μm to 75 μm. If the thickness of the coloring layer 16 is less than 3 μm, the coloring of the coating film 19 that constitutes the coloring layer 16 may be insufficient. On the other hand, if the thickness of the coloring layer 16 exceeds 75 μm, the millimeter wave transmittance of the coloring layer 16 may be reduced.

[0019] 3, the inventors of the present application discovered that there is a positive linear relationship between the amount of aluminum, which is the amount of filler 18 contained in color-forming layer 16, and the relative dielectric constant of color-forming layer 16. The amount of aluminum (amount of filler 18) contained in color-forming layer 16 is expressed as [(weight of aluminum (filler 18) contained in color-forming layer 16 / total weight of color-forming layer 16 after drying) × 100%].

[0020] 3 is a graph showing the relationship between the amount of aluminum and the relative dielectric constant for each of five types of coloring layers A to E (coloring layers 16) having coating films 19 of different colors. The graph in FIG. 3 shows that there is a positive linear relationship between the amount of aluminum contained in the coloring layer 16 and the relative dielectric constant of the coloring layer 16.

[0021] 3, it can be seen that the coloring layers A to E all have an aluminum content (amount of filler 18) of 2.0% or more and a relative dielectric constant of 8.0 or more. Therefore, in the vehicle component 13, it is more preferable that the aluminum content of the coloring layer 16 is 2.0% or more and the relative dielectric constant of the coloring layer 16 is 8.0 or more.

[0022] <Setting the Thickness of the Base Layer 14> The thickness of the base material layer 14 in the vehicle part 13 is preferably set in the range of 1.0 mm or more and 2.5 mm or less. The thickness of the base material layer 14 in the vehicle part 13 is more preferably set in the range of 2.0 mm or more and 2.5 mm or less. However, from the viewpoint of improving the millimeter wave transmittance of the vehicle part 13, it is most preferable to optimize the thickness of the base material layer 14 in accordance with the coloring layers A to E (see FIG. 3) used.

[0023] Fig. 4 is a graph showing the results of calculations of the relationship between the thickness of the base layer 14 and the attenuation of millimeter waves transmitted through the vehicle component 13 having the coloring layer A and the vehicle component 13 having the coloring layer E. The graph in Fig. 4 shows that the optimal thickness of the base layer 14 that minimizes the attenuation of millimeter waves in the vehicle component 13 having the coloring layer A is 2.35 mm. The graph in Fig. 4 also shows that the optimal thickness of the base layer 14 that minimizes the attenuation of millimeter waves in the vehicle component 13 having the coloring layer E is 2.10 mm.

[0024] Fig. 5 is a graph showing the results of comparing the amount of attenuation of millimeter waves when the thickness of the base layer 14 is optimized and when the thickness of the base layer 14 is not optimized in each of the vehicle component 13 having the coloring layer A and the vehicle component 13 having the coloring layer E. In Fig. 5, the thickness of the base layer 14 when not optimized is set to 2.5 mm in both the vehicle component 13 having the coloring layer A and the vehicle component 13 having the coloring layer E.

[0025] In addition, in Fig. 5, the thicknesses of the base material layer 14 when optimized for the vehicle component 13 having the coloring layer A and the vehicle component 13 having the coloring layer E are set to 2.35 mm and 2.10 mm, respectively, from the graph in Fig. 4. It can be seen from the graph in Fig. 5 that in both the vehicle component 13 having the coloring layer A and the vehicle component 13 having the coloring layer E, when the thickness of the base material layer 14 is not optimized, the attenuation of the millimeter wave is less than the required value of -0.85 dB, and the required value is not met.

[0026] 5 also shows that in both the vehicle component 13 having the coloring layer A and the vehicle component 13 having the coloring layer E, when the thickness of the base layer 14 is optimized, the attenuation of millimeter waves becomes equal to or greater than the required value of −0.85 dB, thereby satisfying this required value. Therefore, in the vehicle component 13, the attenuation of millimeter waves can be minimized by optimizing the thickness of the base layer 14 according to the selected color of the coating film 19 of the coloring layer 16.

[0027] <Function of vehicle part 13> 1, millimeter waves are transmitted through each layer of the vehicle component 13. The transmitted millimeter waves are reflected by objects ahead of the vehicle 11, including preceding vehicles and pedestrians, and then transmitted again through each layer of the vehicle component 13 to be received by the millimeter wave radar device 12.

[0028] In this case, the coloring layer 16 in the vehicle component 13 has millimeter wave transparency. In addition, since the relative dielectric constant of the coloring layer 16 in the vehicle component 13 is 4.0 or more, the content of the filler 18 in the coloring layer 16 is further increased. This improves the appearance of the vehicle component 13. Therefore, it is possible to ensure millimeter wave transparency in the vehicle component 13 while also improving the appearance.

[0029] The millimeter wave radar device 12 recognizes an object and detects the distance and relative speed between the object and the vehicle 11 based on the transmitted and received millimeter waves. <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved.

[0030] (1) The vehicle component 13 includes a synthetic resin substrate layer 14 and a coloring layer 16 having aluminum filler 18 dispersed in a coating film 19. The coloring layer 16 is millimeter wave transmissive and has a relative dielectric constant of 4.0 or greater.

[0031] The inventors of the present application have found that there is a positive linear relationship between the amount of filler 18 contained in the coloring layer 16 [(weight of filler 18 contained in the coloring layer 16 / total weight of the coloring layer 16 after drying) × 100%] and the relative dielectric constant of the coloring layer 16. Therefore, according to the above configuration, by setting the relative dielectric constant of the coloring layer 16, which has millimeter wave transparency, to 4.0 or more, the content of filler 18 in the coloring layer 16 increases, thereby improving the appearance of the vehicle component 13. Therefore, the millimeter wave transparency of the vehicle component 13 can be ensured while improving the appearance of the vehicle component 13. In other words, it is possible to ensure the millimeter wave transparency of the vehicle component 13 while also improving the appearance.

[0032] (2) In the vehicle component 13, the thickness of the coloring layer 16 is in the range of 3 μm to 75 μm. According to the above configuration, by setting the thickness of the coloring layer 16 to 75 μm or less, the millimeter wave transmittance of the vehicle component 13 can be sufficiently ensured even when a coloring layer 16 having a relative dielectric constant of 4.0 or more is used for the vehicle component 13. On the other hand, by setting the thickness of the coloring layer 16 to 3 μm or more, the coloring of the coating film 19 is ensured, so a good appearance can be maintained. Therefore, the millimeter wave transmittance of the vehicle component 13 can be sufficiently ensured while maintaining a good appearance of the vehicle component 13.

[0033] (3) In the vehicle component 13, the amount of filler 18 contained in the coloring layer 16 is 2.0% or more, and the relative dielectric constant of the coloring layer 16 is 8.0 or more. According to the above configuration, by setting the amount of filler 18 contained in the coloring layer 16 to 2.0% or more and setting the relative dielectric constant of the coloring layer 16 to 8.0 or more, it is possible to further increase the amount of filler 18 contained in the coloring layer 16. This can contribute to further improving the appearance of the vehicle component 13.

[0034] <Example of change> The above embodiment can be modified as follows: Furthermore, the above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0035] The coloring layer 16 may be formed from a film of transparent resin mixed with multiple fillers 18 and paint. In this way, the coloring layer 16 can be directly attached to the base layer 14 of the vehicle component 13, eliminating the need for the primer layer 15 and clear coat layer 17.

[0036] The coloring layer 16 may contain a coloring agent such as a dye as appropriate. In the vehicle component 13, the amount of filler 18 contained in the coloring layer 16 does not necessarily have to be 2.0% or more, and the relative dielectric constant of the coloring layer 16 does not necessarily have to be 8.0 or more.

[0037] In the vehicle component 13, the thickness of the coloring layer 16 does not necessarily have to be in the range of 3 μm to 75 μm. The millimeter wave radar device 12 that transmits and receives millimeter waves (electromagnetic waves) for detecting objects outside the vehicle may be a device for monitoring the rear as well as for monitoring the front.

[0038] The radar device may be an infrared radar device that transmits and receives infrared rays (electromagnetic waves). The laminate is not limited to vehicle parts 13, but may also be used for consumer parts. That is, the laminate may be applied to consumer products equipped with a radar device that transmits and receives electromagnetic waves other than the vehicle 11. Examples of such consumer products include automatic cleaning robots, robots for transporting or serving food, drones, etc.

[0039] When the laminate is a consumer part having the same layer structure as the vehicle part 13, it is preferable to set the thickness of the base layer 14 in the range of 1.0 mm or more and 2.5 mm or less, and the thickness of the coloring layer 16 in the range of 3 μm or more and 75 μm or less. [Explanation of symbols]

[0040] 11...Vehicle 12... Millimeter wave radar device as an example of a radar device 13... Vehicle parts as an example of laminates 14...Base material layer 15...Primer layer 16, A~E...Coloring layer 17...Clear coat layer 18...Filler 19...Paint film

Claims

1. A laminate that transmits millimeter waves, The inkjet print head comprises a base layer made of synthetic resin and a color-developing layer containing a metal filler, the color-developing layer is millimeter-wave transparent and has a relative dielectric constant of 4.0 or more; A laminate characterized in that the thickness of the substrate layer is in the range of 1.9 mm or more and 2.3 mm or less.

2. 2. The laminate according to claim 1, wherein the color-developing layer has a thickness in the range of 3 [mu]m to 75 [mu]m.

3. the amount of the filler contained in the color-forming layer is 2.0% or more; 3. The laminate according to claim 2, wherein the color-developing layer has a relative dielectric constant of 8.0 or more.

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