JP3755809B2 - Radio wave permeable exterior part and manufacturing method thereof - Google Patents

Description

【００２９】
一方、外面被覆板２にポリメチルペンテン（ＴＰＸ）、背面被覆板３にポリフェニレンエーテル（ＰＰＥ）を使用した場合には、比誘電率の差が０．４以上であり、界面での屈折・反射が大きいため、満足な電波透過性を得ることはできなかった。
ちなみに、比誘電率が近い組み合わせであれば、比誘電率の数値自体が小さい材料の方が電波の屈折・反射が少なく、より望ましい。例えば、前記した材料のように、比誘電率の値が４以下、より望ましくは３以下の材料を組み合わせれば、車両用レーダとして使用されているミリ波レーダに対し、実用上満足な電波強度を確保することが出来る。
なお、比誘電率の測定方法は、自由空間法、特に透過係数から割り出す方法により測定した。
【００３０】
外面被覆板２の外面側表面はシリコン系の撥水処理がなされている。このため、エンブレムについた雨滴は粒状になり、車両の走行時は盛り上がった外表面形状と相俟って雨滴が表面から吹き飛ばされて流れるようになっている。なお、前記撥水処理に代えて、外面被覆板２の材質自体として撥水性のあるものを使用することによっても同様の効果を奏することができる。
【００３１】
金属膜４はインジウムを蒸着して形成された薄膜であり、エンブレムのマークを金属光沢をもってデザインするためのものである。金属膜４をインジウムにより構成したのは、現在知られている金属の中で、ミリ波の透過性が最も良いのがインジウムであるからである。金属膜４の膜厚は、インジウムを使用する場合０．０３μｍ以上、０．０７μｍ以下であるのが望ましい。これは、インジウムの膜厚が０．０３μｍより薄くなると、可視光を十分に反射せず、金属光沢が弱くなってしまい、一方、０．０７μｍより厚くなると、ミリ波の透過性が悪化するからである。さらには、製造上の誤差を考慮すると、０．０４μｍ〜０．０６μｍの間で膜厚を設定するのがより望ましい。
なお、測定に使用した周波数は７６．５ＧＨｚ（波長約４ｍｍ）であった。また、金属膜４に使用する金属は、インジウムに限らず、クロム、錫、アルミニウム、金等も使用することができるが、電波の透過性が良い金属ほど好ましい。
【００３２】
ちなみに、本発明者の研究によれば、前記膜厚で電波の透過性が変化するのは、次のような理由によると考えられる。図３はインジウム蒸着膜のＳＥＭ(Scanning Electron Microscopy)画像のスケッチである。図３において、符号１０が示す領域はインジウムの微細な結晶を示し、符号１１が示す領域は、インジウムの結晶間の隙間を示す。即ち、符号１１の境界により隔てられている符号１０部分は電気的に絶縁されていると考えられる。図３に示すように、（ａ）の０．０６μｍの膜厚までは、インジウム蒸着膜が島状の組織として形成されるのに対し、（ｂ）の膜厚０．０８μｍ、（ｃ）の膜厚０．１μｍの厚さになると、各島が連結した組織となり、電波が透過した時に高周波電流が蒸着膜内に流れ、ロスを生じると考えられる。
【００３３】
黒色塗膜５は、一般的に使用されるアクリル系塗料等を使用することができる。黒色塗膜５は、金属膜４を意匠面で引き立たせるためのものである。色は黒色に限らず、数多くの色彩を使用することができ、さらには塗膜を省略することもできる。例えば、接着剤層６の色彩を見せることにより、黒色塗膜５を廃止することもできる。また、接着剤層６及び背面被覆板３を濃色又は無色の透明な樹脂を使用することにより、内部のレーダ装置を隠しつつ深みのある意匠を実現することもできる。一方、黒色塗膜５を形成させた場合には、背面被覆膜３は外部から見えないので、有色であっても無色であってもどちらでもよい。また、樹脂本来の色彩のまま使用して、樹脂の着色を省略し、樹脂の選択次第でコストの低下を図ることもできる。
なお、黒色塗膜５は、厚さが金属膜４に比較しても薄いので、電波の透過性に対する影響は無視することができる。
【００３４】
接着剤層６は、外面被覆板２と背面被覆板３を貼り合わせるために使用される。例えば、ゴム系の接着剤や両面テープを使用することができる。
なお、接着剤層６は金属ではなく、厚さも薄いため、電波の透過性能にはほとんど影響を与えない。
【００３５】
マスキング塗膜９は、エンブレム１の製造工程で必要であったものであり、一般的なマスキング塗料を使用することが出来る。マスキング塗膜９は、厚さが薄く、金属ではないことから電波の透過性能には影響を与えない。
【００３６】
以上のような構成により、内面から外面へ、又は外面から内面へ通過するレーダの電波は、低減衰量で透過することができる。即ち、外面被覆板２にポリカーボネート（ＰＣ）、背面被覆板３にシンジオタクチックポリスチレンを使用し、両者を接着剤によって接着したため、両者の間での電波の屈折・反射が起こりにくく、良好な電波透過性能を確保することができる。
また、前記構成において、背面被覆板３を外面被覆板２と同じものを使用すれば、電波の屈折・反射を最小限にすることができ、さらに良好な電波透過性能を確保することができる。例えば、外面被覆板２及び背面被覆板３の両方にポリメタクリル酸メチル（ＰＭＭＡ）を使用するような場合が考えられる。
【００３７】
次に、前記した電波透過性外装部品である自動車のエンブレムの製造方法について説明する。
図４は、本実施の形態の自動車のエンブレムの製造方法を示す図である。なお、図４においては、自動車のエンブレムの一部断面のみを示している。
まず、外面被覆板２を透明なポリカーボネート（ＰＣ）により、背面被覆板３をシンジオタクチックポリスチレンによりそれぞれ別個に成形する。
その際外面被覆板２は、エンブレムの内部になる面（以下、「外面被覆板の内部面」という）において、金属光沢を持たせる部分を一段低くして凹部２ａにして成形する。背面被覆板３の外面被覆板２に接着される面（以下、「背面被覆板の内部面」という）は、外面被覆板２の内部面と相補する形状に成形される。但し、接着剤で外面被覆板２と、背面被覆板３の間を充填するように製造する場合には、背面被覆板３の内部面は必ずしも外面被覆板２の内部面と相補する形状でなくても良い。この場合、接着剤として、外面被覆板２や背面被覆板３と、比誘電率が略同一なものを選択するのが望ましい。なお、背面被覆板３の外表面となる面は電波の不要な散乱を防止するため、平面もしくはなだらかな曲面、望ましくは曲率半径１４０ｍｍ以上に成形される。
【００３８】
次に、図４（ａ）に示すように、外面被覆板２の内部面全面にインジウムを使用して金属膜４を蒸着により約０．０５μｍの厚さで堆積させる。
次に、図４（ｂ）に示すように、外面被覆板２の内部面の凹部２ａにマスキング塗料を滴下してマスキング塗膜９を形成させる。金属光沢を残したい部分は前記したように一段低くして凹部２ａとしているので、マスキング塗料の滴下量を適切に設定することにより、マスキング工程の自動化も容易である。
次に、同図（ｃ）に示すように、外面被覆板２の内部面全体をエッチングすることにより、マスキング塗膜９を形成した部分以外の金属膜４を除去する。
次に、同図（ｄ）に示すように、外面被覆板２の内部面全面に黒色の塗料で吹付け塗装を行い、黒色塗膜５を形成する。
次に、同図（ｅ）に示すように、外面被覆板２の内部面全面にゴム系の接着剤６を塗布した後、背面被覆板３を貼り合わせる。この際、接着剤は流動性を有するので、外面被覆板２と背面被覆板３の寸法差から生じる隙間を埋め、気泡が生じるのを防ぐことができる。
【００３９】
以上の工程の後、接着剤層６が乾燥したならば、本発明の電波透過性外装部品である自動車用エンブレム１が完成する。本発明の電波透過性外装部品の製造方法においては、該マスキングを施す部分を凹部となるように外面被覆板２を形成しているので、マスキング塗料を一定量滴下するという簡易な工程でマスキングを行うことを実現している。さらに、金属膜４を残したい部分にマスキングを施しているので、シール状のマスキングを１つずつ剥がす必要がない。従って、複数個の部品を１度にエッチングし、容易に大量生産することができるので、電波透過性外装部品の製造費のコストダウンを図ることができる。
【００４０】
以上、本発明の実施の形態について説明したが、本発明は前記実施の形態には制限されない。
即ち、実施の形態においては、一例として自動車のエンブレムを電波透過性外装部品とする場合について述べたが、自動車のエンブレム以外にも、例えば、フロントグリル自体、スクーターのボディー前面の意匠部分等でも実施することができる。
【００４１】
【発明の効果】
以上詳述した通り、本発明の請求項１では、従来必要であったマスキング工程を廃止することにより、電波透過性外装部品の製造コストを低下させることができる。
【００４２】
また、本発明の請求項２によれば、外面被覆板及び背面被覆板の形状誤差を許容できて、電波透過性外装部品の製造コストを低下させることができるとともに、電波透過性能を高めることができる。
【００４３】
また、本発明の請求項３によれば、金属光沢部分の背景を与えて、意匠性を高めることができる。
【００４４】
また、本発明の請求項４によれば、外面被覆板と背面被覆板の材料として、比誘電率が近いものを使用することにより、外面被覆板と背面被覆板の間の電波の屈折・反射を最小限にして、金属光沢の意匠を有する電波透過性外装部品において、電波透過性能を高めることができる。
【００４５】
また、本発明の請求項５によれば、外面被覆板と背面被覆板を構成する材料の比誘電率を４以下として、自動車用レーダとして使用されているミリ波レーダに対し、実用上差支えない電波強度を確保した電波透過性外装部品とすることができる。
【００４６】
さらに、本発明の請求項６のような外面被覆板と背面被覆板の材料の組み合わせにより、屈折・反射による電波強度の減衰を抑えることができる。
【００４７】
また、本発明の請求項７のように外面被覆板の表面に撥水処理をすることにより、雨滴による電波強度の減衰を防止することができる。
【００４８】
また、本発明の請求項８によれば、外面被覆板と内面被覆板の材料を同じくすることで、外面被覆板と背面被覆板の間での電波の屈折・反射を最小限にすることができ、電波の透過性能を高めることができる。
【００４９】
また、本発明の請求項９によれば、金属光沢を呈しつつ、ミリ波レーダの外装部品として必要な電波透過性能を確保することが出来る。
【図面の簡単な説明】
【図１】本発明の電波透過性外装部品の断面図である。
【図２】本発明の電波透過性外装部品の一例である自動車用エンブレムの斜視図である。
【図３】インジウム蒸着膜の組織を示す図であり、（ａ）が膜厚０．０６μｍの場合、（ｂ）が膜厚０．０８μｍの場合、（ｃ）が膜厚０．１μｍの場合である。
【図４】本発明の電波透過性外装部品の製造方法を示す図であり、（ａ）が金属蒸着膜形成工程、（ｂ）がマスキング工程、（ｃ）がエッチング工程、（ｄ）が塗装工程、（ｅ）が背面被覆板貼り付け工程である。
【図５】従来のレーダの被覆用外装部品の製造方法を示す図であり、（ａ）がマスキング工程、（ｂ）が塗装工程、（ｃ）がマスキング剥離工程、（ｄ）がインジウム蒸着工程である。
【図６】従来のレーダの被覆用外装部品の製造方法を示す図であり、（ｅ）がコーティング工程、（ｆ）が保護シート貼り付け工程、（ｇ）が二次モールド工程である。
【符号の説明】
１…エンブレム（電波透過性外装部品）、２…外面被覆板、３…背面被覆板、４…金属膜、５…黒色塗膜、６…接着剤層、９…マスキング塗膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exterior part of a device that uses radio waves, such as a communication device and a radio wave radar, and a method for manufacturing the same, and more particularly, a radio wave permeable exterior component that has a metallic luster design inside and has excellent radio wave permeability, and It relates to the manufacturing method.
[0002]
[Prior art]
Generally, antennas that transmit and receive radio waves, such as communication devices and radars, are given priority in function, and the antenna body and surrounding structure are rarely restricted in design. For example, a rod antenna having an exposed antenna shape is used as an antenna for an automobile radio or the like.
By the way, depending on the mounting position of the antenna, it may be desired to hide the antenna. For example, an obstacle in front of an automobile, a radar that measures the distance between vehicles, and the like are preferably provided at the center of the front of the automobile in order to exhibit its performance. In such a case, an antenna is generally attached in the vicinity of the front grille of the automobile, but it is desirable to make the antenna as invisible as possible from the design surface.
[0003]
As a solution to this problem, for example, there are inventions described in Japanese Patent Application Laid-Open Nos. 2000-49522 and 2000-159039. In these inventions, an automotive emblem or front grille is used as an exterior part for covering a radar device, and a metal layer is provided inside the exterior part for covering, thereby providing a design with a metallic luster and a radar. The function to protect the device is realized. In addition, this exterior part for covering has a function of receiving the radio wave of the internal radar device and emitting it to the outside, and also has a function of receiving the radio wave returned from the detected object and sending the radio wave to the radar device. Is functioning as
[0004]
Moreover, the exterior parts for coating | cover which have a metallic luster inside the conventional automotive radar were manufactured in the following processes.
5 and 6 are diagrams showing a process for manufacturing a sheathing exterior component for a conventional automotive radar.
As shown in FIG. 5A, first, a clear layer 101 to be an outer surface of an emblem is formed, and a seal-like masking 102 is manually attached to an inner surface 101a of a portion constituting a design with metallic luster. In addition, masking is not affixed about the inner surface 101b which comprises the background which does not exhibit metallic luster.
Next, as shown in FIG. 5B, the coating film 103 is formed by spraying a dark paint. Here, the dark color paint is used in order to enhance the design of the metallic luster part.
Next, as shown in FIG. 3C, the masking 102 is peeled off to expose the surface of the clear layer 101 that expresses metallic luster.
Next, as shown in FIG. 4D, indium is vapor-deposited to form a metallic luster layer 104.
Next, as shown in FIG. 6E, in order to protect the metallic luster layer 104 from heat during the secondary molding, the entire metallic luster layer 104 is coated with a silicon resin 105 or the like.
Next, as shown in FIG. 5F, a protective sheet 106 made of polyimide or the like is attached to the corners in order to prevent deformation of the shape during secondary molding.
Next, as shown in FIG. 5G, acrylonitrile / styrene / acrylic acid ester copolymer (ASA) 107 and the like are secondarily molded to complete.
[0005]
[Problems to be solved by the invention]
However, the exterior parts of the radar apparatus having a metallic luster need to be difficult to attenuate the intensity of the radio wave in order to prevent the radar apparatus from erroneously receiving the radio wave. That is, in order to prevent the attenuation of the radio wave in the exterior part itself, it is necessary to minimize the refraction and reflection of the radio wave between the materials and between the metal films, and it is also necessary to minimize the attenuation of the radio wave due to raindrops.
In addition, in the conventional method for manufacturing an exterior part of a radar device as described above, since a secondary mold is used, bubbles may be generated at the interface between the outer cover plate and the inner cover plate. In some cases, there is a problem that the radio wave transmission performance deteriorates. Furthermore, when water enters the bubble portion, the radio wave transmission performance is further reduced.
In addition, when a secondary mold is used, it is necessary to put a cover plate on the outer surface exactly in the mold of the secondary mold, so that the shape accuracy of the outer cover plate is required to be high. Moreover, since it is also necessary to affix a heat resistant film such as polyimide for preventing deformation on the surface of the outer cover plate, the cost tends to increase. Furthermore, since the materials of the outer cover plate and the rear cover plate must be different in order to prevent deformation during secondary molding, radio waves are likely to be reflected at the interface between the outer cover plate and the rear cover plate. The radio wave transmission performance may deteriorate.
[0006]
Accordingly, an object of the present invention is to solve the above-described problems and to provide a radio wave transmissive exterior component having a good radio wave transmission property while having a design with a metallic luster.
It is another object of the present invention to provide a low-cost manufacturing method for radio wave permeable exterior parts having the above-mentioned performance.
[0007]
[Means for Solving the Problems]
  In order to solve the problem,According to a first aspect of the present invention, in the method for manufacturing a radio wave permeable exterior component, a first outer covering plate is formed which is made of a radio wave transmissive and transparent material and has a concave portion with a flat bottom surface in a portion to be given a metallic luster. A step, a second step of forming a metal film on the inner surface of the outer cover plate, a third step of dropping and applying a masking paint to a portion where the metal film is left and having a metallic luster, and other than the masking paint part by etching And a fourth step of removing the metal film, and a fifth step of laminating a back cover plate made of a radio wave transmitting material on the inner surface of the outer cover plate.
[0008]
  With such a manufacturing method, it is not necessary to apply a seal-like masking before forming a metal vapor deposition film, which was necessary in the manufacturing process of the radio wave transmitting exterior component. On the other hand, it is possible to efficiently mask by applying a masking paint to the portion where the metallic luster remains.
[0009]
  In claim 2 of the present invention,The method of manufacturing a radio wave transmitting exterior component according to claim 1, wherein the back cover plate is laminated by attaching the back cover plate to the outer cover plate with an adhesive member.
[0010]
  Such a method eliminates the need for a heat resistant film such as polyimide that is attached to the outer cover plate, which is necessary in the manufacturing method using the conventional secondary mold, and can reduce the manufacturing cost. Further, there is no generation of bubbles between the outer cover plate and the rear cover plate that may occur during the secondary molding, and good radio wave transmission performance can be ensured. Furthermore, the flexibility of the adhesive member can absorb the shape error between the outer cover plate and the rear cover plate, and it is not necessary to fit the outer cover plate into the mold for the secondary mold. The shape error of the outer surface covering plate can be allowed, and the cost can be reduced.
[0011]
  Further, in claim 3 of the present invention,In the method for manufacturing a radio wave transmitting exterior component according to claim 1 or 2, the interior surface of the outer cover plate is coated after the fourth step and before the fifth step.
[0012]
  By such a method, a color irrespective of the color of the material of the back cover plate can be given as the background of the metallic luster portion, so that the design of the radio wave transmitting exterior component can be improved. In particular, the design of the metallic luster portion can be enhanced by using a dark color such as black as the background.
[0013]
  Moreover, Claim 4 of this inventionThe radio wave permeable exterior component according to claim 1, wherein the radio wave transmissive exterior component is manufactured by the method of manufacturing a radio wave transmissive exterior component according to any one of claims 1 to 3. In an exterior part for a vehicle comprising an outer surface covering plate made of a material, a metal film formed on an inner surface of the outer surface covering plate, and a rear surface covering plate made of a radio wave transmitting material, the outer surface covering The relative dielectric constants of the material constituting the plate and the back cover plate are substantially the same.
[0014]
  In general, at the interface of different materials, the greater the difference in relative permittivity between materials, the easier the refraction and reflection of radio waves. Therefore, in the present invention, the radio wave transmitting exterior component is configured using an outer surface coating plate and a rear surface coating plate having substantially the same relative dielectric constant. In addition, “substantially the same” in the claims means a case where the relative dielectric constant difference is approximately 0.2 or less.
  By doing in this way, the refraction | bending and reflection of the electromagnetic wave between an outer surface coating plate and a back surface coating plate can be minimized, and the electromagnetic wave transmission performance of an electromagnetic wave permeable exterior component can be improved.
[0015]
  Further, in claim 5 of the present invention,5. The radio wave transmitting exterior component according to claim 4, wherein each of the materials constituting the outer cover plate and the rear cover plate has a relative dielectric constant of 4 or less.
[0016]
  In general, the higher the relative dielectric constant of the material, the more intense the refraction and reflection of radio waves. Therefore, in the present invention, by using a material having a relative dielectric constant of 4 or less as the outer surface coating plate and the rear surface coating plate, the radio wave intensity that can be practically used compared to the millimeter wave radar currently used as a vehicle radar. Is secured.
[0017]
  Further, in claim 6 of the present invention,The radio wave transmitting exterior component according to claim 5, wherein the outer cover plate is made of polycarbonate (PC) or polymethyl methacrylate (PMMA), and the back cover plate is syndiotactic polystyrene or polyphenylene ether (PPE) or It is characterized by being composed of polyvinyl chloride (PVC) or acrylonitrile / butadiene / styrene copolymer (ABS).
[0018]
  In the material grade used by the inventors in the present invention, the relative dielectric constant of polycarbonate (PC) used for the outer cover plate in the above configuration is 2.8, and the relative dielectric constant of polymethyl methacrylate (PMMA) is 2.7. The relative dielectric constant of syndiotactic polystyrene used for the back cover plate is 2.9, the relative dielectric constant of polyphenylene ether (PPE) is 2.7, the relative dielectric constant of polyvinyl chloride (PVC) is 2.9, acrylic The relative dielectric constant of the nitrile / butadiene / styrene copolymer (ABS) was 2.7. Therefore, refraction and reflection of radio waves can be effectively suppressed by such a combination of materials.
[0019]
  Further, in claim 7 of the present invention,The radio wave transmitting exterior component according to any one of claims 4 to 6, wherein a surface of the outer cover plate is subjected to a water repellent treatment.
[0020]
  Moisture such as raindrops causes the radio field intensity to be attenuated. In particular, if water adheres to the entire surface through which radio waves pass, such as the outer surface of radio wave transmitting exterior parts, the radio field intensity is attenuated by about 5 dB. End up. On the other hand, in a state where moisture is sparsely attached in the form of water droplets, radio wave attenuation does not occur as in the case of adhesion on the entire surface. Therefore, by performing water-repellent treatment on the surface of the outer cover plate on which raindrops may adhere, the raindrops will adhere at least sparsely, and a reduction in radar performance can be prevented.
  For the same reason, the same effect can be obtained by adopting a configuration in which the material of the outer cover plate itself is a material having water repellency.
[0021]
  Further, in claim 8 of the present invention,The radio wave transmitting exterior component according to any one of claims 4, 5, and 7, wherein the back cover plate is made of the same material as the outer cover plate.
[0022]
  If the back cover plate is made of the same material as the external cover plate, the refraction and reflection of radio waves between the external cover plate and the back cover plate can be minimized, and the radio wave transmission performance can be improved. In order to use the same material, the secondary mold is not used, and if the back cover plate is attached to the outer cover plate with an adhesive, it can be molded without deformation.
[0023]
  Further, in claim 9 of the present invention,The radio wave transmitting exterior component according to any one of claims 4 to 8, wherein the metal film is made of indium and has a thickness of 0.03 μm or more and 0.07 μm or less. .
[0024]
  As described above, indium is used as the metal film, and the film thickness is set to 0.03 μm or more, so that the visible light is sufficiently reflected to exhibit a metallic luster, and the thickness is set to 0.07 μm or less. The radio wave transmission performance required as an exterior part can be ensured.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partial cross-sectional view of a radio wave permeable exterior component of the present invention, and FIG. 2 is an external perspective view of an automobile emblem that is an example of the radio wave transmissive exterior component of the present invention.
As shown in FIG. 2, the emblem 1 which is a radio wave transmitting exterior component according to the present invention has a silver mark on a black background, the surface is covered with transparent polycarbonate (PC), and the center is slightly It has a raised outer surface shape. The silver mark swells slightly outside the black background. FIG. 1 is a cross-sectional view showing a part of the black and silver portions.
As shown in FIG. 1, the emblem 1 has an outer surface covering plate 2 positioned on the outer surface side of the vehicle body, a rear surface covering plate 3 positioned on the inner surface side, and a metallic luster formed in a recess on the inner surface side of the outer surface covering plate 2. Adhesion for bonding the metal film 4 to be presented, the masking coating film 9 positioned on the back surface of the metal film 4, the black coating film 5 formed on the inner surface side of the masking coating film 9, and the outer coating plate 2 and the rear coating plate 3 It is comprised from the adhesive bond layer 6 which is a member.
[0026]
The outer surface covering plate 2 is formed by molding a transparent polycarbonate (PC), and plays a role of improving the design of the emblem 1 by covering the outside of the emblem 1 with a transparent layer.
The back cover plate 3 is formed by syndiotactic polystyrene, and serves to prevent unnecessary scattering of radio waves on the inner surface by making the inside of the emblem 1 a flat surface.
[0027]
The reason why the above-described polycarbonate (PC) and syndiotactic polystyrene are used as the material of the outer cover plate 2 and the rear cover plate 3 is that there is generally a difference in relative permittivity at the interface between different materials. -Since a reflection occurs, a combination of materials having a relatively close relative dielectric constant is selected. In the material grade used by the inventors in the present invention, the relative dielectric constant of polycarbonate (PC) is 2.8, and the relative dielectric constant of syndiotactic polystyrene is 2.9. . Other combinations include polymethyl methacrylate (PMMA) with a relative dielectric constant of 2.7 and syndiotactic polystyrene, or polycarbonate (PC) or polymethyl methacrylate (PMMA) with a relative dielectric constant of 2. .7 in combination with polyphenylene ether (PPE), polyvinyl chloride (PVC) with a relative dielectric constant of 2.9, or acrylonitrile / butadiene / styrene copolymer (ABS) with a relative dielectric constant of 2.7, and A combination of polymethylpentene (TPX) having a relative dielectric constant of around 2.1 and polypropylene (PP) having a relative dielectric constant of 2.2 is conceivable. Like these combinations, when the difference in relative permittivity is approximately up to about 0.2, the refraction and reflection of radio waves at the interface is small and satisfactory radio wave transmission performance is obtained.
The relative dielectric constants of these materials are summarized in Table 1.
[0028]
[Table 1]

[0029]
On the other hand, when polymethylpentene (TPX) is used for the outer cover plate 2 and polyphenylene ether (PPE) is used for the rear cover plate 3, the difference in relative dielectric constant is 0.4 or more, and refraction and reflection at the interface. Therefore, satisfactory radio wave permeability could not be obtained.
Incidentally, if the relative dielectric constants are close to each other, a material having a small relative dielectric constant value itself is more preferable because it causes less radio wave refraction and reflection. For example, if a material having a relative dielectric constant of 4 or less, more preferably 3 or less, such as the above-described material, is combined with a millimeter wave radar used as a vehicular radar, practically satisfactory radio wave intensity Can be secured.
The relative dielectric constant was measured by the free space method, particularly by the method of calculating from the transmission coefficient.
[0030]
The outer surface side surface of the outer surface covering plate 2 is subjected to silicon-based water repellent treatment. For this reason, raindrops attached to the emblem become granular, and raindrops are blown off from the surface and flow together with the raised outer surface shape when the vehicle is running. In addition, it can replace with the said water repellent process, and can show | play the same effect also by using what has water repellency as the material itself of the outer surface coating plate 2. FIG.
[0031]
The metal film 4 is a thin film formed by vapor deposition of indium, and is used for designing the emblem mark with metallic luster. The reason why the metal film 4 is made of indium is that it is indium that has the best millimeter-wave transparency among the currently known metals. The thickness of the metal film 4 is preferably 0.03 μm or more and 0.07 μm or less when indium is used. This is because when the indium film thickness is less than 0.03 μm, the visible light is not sufficiently reflected and the metallic luster is weakened. On the other hand, when the indium film thickness is greater than 0.07 μm, the millimeter wave transmission is deteriorated. It is. Furthermore, in consideration of manufacturing errors, it is more desirable to set the film thickness between 0.04 μm and 0.06 μm.
The frequency used for the measurement was 76.5 GHz (wavelength: about 4 mm). Further, the metal used for the metal film 4 is not limited to indium, but chromium, tin, aluminum, gold, or the like can be used, but a metal having better radio wave permeability is preferable.
[0032]
Incidentally, according to the inventor's research, it is considered that the radio wave permeability changes with the film thickness for the following reason. FIG. 3 is a sketch of an SEM (Scanning Electron Microscopy) image of the deposited indium film. In FIG. 3, a region indicated by reference numeral 10 indicates a fine crystal of indium, and a region indicated by reference numeral 11 indicates a gap between the crystals of indium. That is, it can be considered that the reference numeral 10 separated by the boundary of the reference numeral 11 is electrically insulated. As shown in FIG. 3, the indium vapor-deposited film is formed as an island-like structure up to the film thickness of 0.06 μm in (a), whereas the film thickness of 0.08 μm in (b), When the film thickness is 0.1 μm, the islands are connected to each other, and when radio waves are transmitted, a high-frequency current flows into the deposited film, causing a loss.
[0033]
The black paint film 5 can use acrylic paints generally used. The black coating film 5 is for making the metal film 4 stand out on the design surface. The color is not limited to black, and many colors can be used, and furthermore, the coating film can be omitted. For example, the black coating 5 can be abolished by showing the color of the adhesive layer 6. Further, by using a dark or colorless transparent resin for the adhesive layer 6 and the back cover plate 3, a deep design can be realized while hiding the internal radar device. On the other hand, when the black coating film 5 is formed, the back surface coating film 3 is not visible from the outside, so it may be either colored or colorless. Moreover, it is possible to use the resin in its original color, omit the resin coloring, and reduce the cost depending on the selection of the resin.
In addition, since the thickness of the black coating film 5 is thinner than that of the metal film 4, the influence on the radio wave transmission can be ignored.
[0034]
The adhesive layer 6 is used for bonding the outer cover plate 2 and the back cover plate 3 together. For example, a rubber adhesive or a double-sided tape can be used.
The adhesive layer 6 is not a metal and has a small thickness, so that it hardly affects the radio wave transmission performance.
[0035]
The masking coating film 9 is necessary in the manufacturing process of the emblem 1, and a general masking paint can be used. Since the masking coating film 9 is thin and not a metal, it does not affect the radio wave transmission performance.
[0036]
With the above configuration, radar radio waves passing from the inner surface to the outer surface or from the outer surface to the inner surface can be transmitted with low attenuation. That is, since polycarbonate (PC) is used for the outer cover plate 2 and syndiotactic polystyrene is used for the rear cover plate 3 and both are bonded with an adhesive, refraction and reflection of radio waves between the two hardly occur and good radio waves are generated. Transmission performance can be ensured.
Further, in the above configuration, if the same back cover plate 3 as the outer cover plate 2 is used, the refraction and reflection of radio waves can be minimized, and better radio wave transmission performance can be ensured. For example, the case where polymethyl methacrylate (PMMA) is used for both the outer surface covering plate 2 and the rear surface covering plate 3 can be considered.
[0037]
Next, a method of manufacturing an automobile emblem that is the above-described radio wave transmitting exterior component will be described.
FIG. 4 is a diagram showing a method for manufacturing an automobile emblem according to the present embodiment. In FIG. 4, only a partial cross section of the emblem of the automobile is shown.
First, the outer cover plate 2 is formed separately from transparent polycarbonate (PC), and the rear cover plate 3 is formed separately from syndiotactic polystyrene.
At that time, the outer surface covering plate 2 is formed into a concave portion 2a by lowering a portion having a metallic luster on the surface that becomes the inside of the emblem (hereinafter referred to as “inner surface of the outer surface covering plate”). A surface of the back cover plate 3 bonded to the outer cover plate 2 (hereinafter referred to as “inner surface of the back cover plate”) is formed in a shape complementary to the inner surface of the outer cover plate 2. However, when manufacturing so that the space between the outer cover plate 2 and the back cover plate 3 is filled with an adhesive, the inner surface of the rear cover plate 3 does not necessarily have a shape complementary to the inner surface of the outer cover plate 2. May be. In this case, it is desirable to select an adhesive having substantially the same dielectric constant as that of the outer cover plate 2 and the rear cover plate 3. In addition, in order to prevent unnecessary scattering of radio waves, the surface serving as the outer surface of the back cover plate 3 is formed to be a flat surface or a gentle curved surface, preferably a curvature radius of 140 mm or more.
[0038]
Next, as shown in FIG. 4A, a metal film 4 is deposited to a thickness of about 0.05 μm by vapor deposition on the entire inner surface of the outer cover plate 2 using indium.
Next, as shown in FIG. 4B, a masking coating 9 is formed by dropping a masking coating into the recess 2 a on the inner surface of the outer cover plate 2. As described above, the portion where the metallic luster is desired to be left is lowered one step to form the recess 2a. Therefore, the masking process can be easily automated by appropriately setting the dropping amount of the masking paint.
Next, as shown in FIG. 2C, the entire inner surface of the outer cover plate 2 is etched to remove the metal film 4 other than the portion where the masking coating film 9 is formed.
Next, as shown in FIG. 3D, the black coating 5 is formed by spraying the entire inner surface of the outer cover plate 2 with a black paint.
Next, as shown in FIG. 5E, after applying a rubber adhesive 6 to the entire inner surface of the outer surface coating plate 2, the back surface coating plate 3 is bonded. At this time, since the adhesive has fluidity, it is possible to fill a gap caused by a dimensional difference between the outer cover plate 2 and the rear cover plate 3 and prevent bubbles from being generated.
[0039]
If the adhesive layer 6 is dried after the above steps, the automobile emblem 1 which is the radio wave transmitting exterior component of the present invention is completed. In the method for manufacturing a radio wave transmitting exterior component according to the present invention, since the outer surface coating plate 2 is formed so that the portion to be masked becomes a recess, masking is performed by a simple process of dropping a certain amount of masking paint. Has realized that to do. Further, since the masking is applied to the portion where the metal film 4 is desired to be left, it is not necessary to remove the seal-like masking one by one. Therefore, since a plurality of parts can be etched at once and mass production can be easily performed, the manufacturing cost of the radio wave transmitting exterior parts can be reduced.
[0040]
As mentioned above, although embodiment of this invention was described, this invention is not restrict | limited to the said embodiment.
That is, in the embodiment, the case where the emblem of the automobile is a radio wave transmissive exterior part is described as an example. However, in addition to the emblem of the automobile, for example, the front grill itself, the design part on the front surface of the scooter body, etc. can do.
[0041]
【The invention's effect】
  As detailed above, in claim 1 of the present invention,By eliminating the masking process that has been necessary in the past, the manufacturing cost of the radio wave transmitting exterior component can be reduced.
[0042]
  According to claim 2 of the present invention,The shape error of the outer cover plate and the back cover plate can be allowed, the manufacturing cost of the radio wave transmitting exterior component can be reduced, and the radio wave transmission performance can be improved.
[0043]
  AlsoClaim 3 of the present inventionAccording to the above, the background of the metallic luster portion can be given and the design can be enhanced.
[0044]
  Moreover, Claim 4 of this inventionAccording to the design of the metallic luster, the refraction and reflection of radio waves between the outer surface coating plate and the rear surface coating plate are minimized by using materials having a close relative dielectric constant as the materials of the outer surface coating plate and the rear surface coating plate. In the radio wave transmitting exterior component having the above, the radio wave transmission performance can be improved.
[0045]
  According to claim 5 of the present invention,The relative dielectric constant of the material constituting the outer cover plate and the rear cover plate is set to 4 or less, and a radio wave permeable exterior component that secures a radio wave strength that can be practically used for the millimeter wave radar used as an automotive radar. be able to.
[0046]
  furtherClaim 6 of the present inventionBy combining the material of the outer cover plate and the rear cover plate as described above, attenuation of the radio wave intensity due to refraction and reflection can be suppressed.
[0047]
  Moreover, Claim 7 of this inventionAs described above, the water repellent treatment is performed on the surface of the outer cover plate to prevent the attenuation of the radio wave intensity due to raindrops.
[0048]
  According to claim 8 of the present invention,By using the same material for the outer cover plate and the inner cover plate, the refraction and reflection of radio waves between the outer cover plate and the back cover plate can be minimized, and the radio wave transmission performance can be improved.
[0049]
  According to claim 9 of the present invention,While exhibiting a metallic luster, it is possible to ensure the radio wave transmission performance necessary for exterior parts of millimeter wave radar.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a radio wave transmitting exterior component of the present invention.
FIG. 2 is a perspective view of an automobile emblem that is an example of a radio wave transmitting exterior component of the present invention.
FIGS. 3A and 3B are diagrams showing the structure of an indium vapor deposition film. FIG. 3A shows a case where the film thickness is 0.06 μm, FIG. 3B shows a case where the film thickness is 0.08 μm, and FIG. It is.
FIGS. 4A and 4B are diagrams showing a method of manufacturing a radio wave transmitting exterior part according to the present invention, wherein FIG. 4A is a metal vapor deposition film forming step, FIG. 4B is a masking step, FIG. 4C is an etching step, and FIG. Step (e) is a back cover plate attaching step.
FIGS. 5A and 5B are diagrams showing a conventional method for manufacturing an exterior part for covering a radar, wherein FIG. 5A is a masking step, FIG. 5B is a coating step, FIG. 5C is a masking peeling step, and FIG. It is.
FIGS. 6A and 6B are diagrams showing a conventional method for manufacturing a cladding exterior part for a radar, wherein FIG. 6E is a coating process, FIG. 6F is a protective sheet attaching process, and FIG. 6G is a secondary molding process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Emblem (radio wave-permeable exterior component), 2 ... Outer surface coating plate, 3 ... Back surface coating plate, 4 ... Metal film, 5 ... Black coating film, 6 ... Adhesive layer, 9 ... Masking coating film

Claims (9)

A method for manufacturing a radio wave transmitting exterior component comprising the following steps.
(B) Ri Do from the radio wave transmitting and transparent material, the metal film on an inner surface of the first step (b) said outer surface coating plate bottom surface portion to have a metallic luster to mold the outer surface covering plate having a flat recess the removal of the second step (c) third step (d) a metal film other than the masking coating portion by etching is applied dropwise masked paint portion Ru to have a metallic luster leaving a metal film forming the 4 processes (e) 5th process of laminating | stacking the back surface coating board which consists of a radio wave permeable material on the internal surface of the said outer surface coating board Lamination of the back cover plate, method for producing a radio wave transmitting exterior part according to claim 1, characterized in that by attaching the back covering plate by an adhesive member on the outer surface covering plate. The method of manufacturing a radio wave permeable exterior component according to claim 1 or 2 , wherein after the fourth step and before the fifth step, the inner surface of the outer cover plate is coated. A radio wave transmitting exterior component manufactured by the radio wave transmitting exterior component manufacturing method according to any one of claims 1 to 3,
A vehicle exterior component comprising an outer surface covering plate made of a radio wave transmissive and transparent material, a metal film formed on the inner surface of the outer surface covering plate, and a rear surface covering plate made of a radio wave transmissive material. The radio wave permeable exterior component according to claim 1, wherein the materials constituting the outer cover plate and the rear cover plate have substantially the same relative dielectric constant. 5. The radio wave transmitting exterior component according to claim 4 , wherein each of the materials constituting the outer surface covering plate and the rear surface covering plate has a relative dielectric constant of 4 or less. The outer cover plate is made of polycarbonate (PC) or polymethyl methacrylate (PMMA), and the back cover plate is syndiotactic polystyrene or polyphenylene ether (PPE) or polyvinyl chloride (PVC) or acrylonitrile / butadiene / styrene. 6. The radio wave permeable exterior component according to claim 5 , wherein the radio wave permeable exterior component is made of a copolymer (ABS). The radio wave permeable exterior component according to any one of claims 4 to 6 , wherein a surface of the outer surface covering plate is subjected to a water repellent treatment. The rear cover plate is claim 4, characterized in that it consists of the same material as the outer surface covering plate, according to claim 5, a radio wave transmitting exterior part according to any one of claims 7. The radio wave transmitting exterior component according to any one of claims 4 to 8 , wherein the metal film is made of indium and has a thickness of 0.03 µm or more and 0.07 µm or less.

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