First surface decoration element

Abstract

The present invention is directed to a decorative vehicle element comprising a substrate, preferably radio wave transparent, having a first surface on a first side and a second surface on a second side, and a first surface decorative coating, preferably radio wave transparent, on the substrate, wherein the decorative coating comprises a decorative layer made of a metal or made of an alloy containing a metal, as well as to a radar system including a radio wave transmitter, a radio wave receiver, and a decorative element, particularly a radome.

Description

Technical Field

[0001]

[0001] The present invention relates to an element, in particular a radome, comprising a decorative first surface coating. In particular, the element is useful for automotive applications, and thus the first surface coating needs to meet the severe wear and toughness requirements required for external automotive parts, while at the same time being sufficiently radio wave transmissive in the case of a radome to allow for minimally attenuated transmission of the radio wave frequencies used in a RADAR (Radio Detection and Ranging) system. Furthermore, the element must be visually appropriate for the desired purpose.

Background Art

[0002]

[0002] Since the beginning of the automotive industry, decorative elements have been used in vehicles. Furthermore, since their development in the early 20th century, RADAR (Radio Detection and Ranging) systems have evolved and been miniaturized, and as a result, they are now integrated into various everyday devices. One common use of radar is in driver assistance systems in vehicles. Radar is used in various warning systems, semi-autonomous systems, and autonomous systems within a vehicle. Such systems include proximity detection, inter-vehicle distance control, collision avoidance, and blind spot detection that can be used for parking assistance. Furthermore, radar, in combination with LIDAR (Light Illuminating Detection and Ranging), provides a detection system developed for autonomous and semi-autonomous vehicles.

[0003]

[0003] A radar system functions based on the fact that the irradiation radio wave (radar signal) emitted from a transmitter is reflected or scattered by a solid object. These reflected radar waves are then generally detected by a receiver close to the transmitter, enabling the radar system to detect an object. Typically, radio waves are reflected when traveling between media with different electrical conductivities. As such, a radar system is particularly effective in detecting conductive materials such as metals. However, this presents a problem when attempting to develop radar-compliant materials with a metallic appearance.

[0004]

[0004] In the case of a radome, it is not desirable to see the system behind the decorative element, such as a radar system, from the outside, and since the system, particularly a radar system, needs to be protected from environmental damage, a system such as a radar system is typically located behind a decorative element, particularly a radome. A radome is an example of a decorative element in the form of a protective cover that is substantially radio wave transmissive and thus does not substantially attenuate radio wave signals. Suitable materials for providing a radome include synthetic polymers (such as plastics) that are electrically insulating. However, the integration of such plastic elements, particularly radomes, has been difficult to achieve when a metallic finish is desired. Typical metallic finishes, such as a chrome film on plastic, reflect radio wave signals and are thus not suitable for use in a radome.

[0005]

[0005] Conventionally, in the context of automobiles, radar transmitters and receivers are positioned at the front of the vehicle, above or on the upper part of the vehicle front grille. There is an increasing market demand for multiple radar-based systems within the vehicle, including Blind-Spot Detection (BSD), Lane-Change Assist (LCA), Front / Rear Cross-Traffic Alert (F / RCTA), Autonomous Emergency Braking (AEB), and Adaptive Cruise Control (ACC). This has spurred the need for positioning radar transmitters and sensors at many different locations on the vehicle, such as behind the fascia including bumpers and body panels. There is a need for suitable components that can be used in the automotive exterior and are radar-compliant.

[0006]

[0006] Conventional body parts are not ideal domes for use with radar systems. Metal body panels are not radar-compliant, and thus, the radar system needs to be positioned behind a radio wave-transmissive substrate such as a plastic panel. However, many plastics used to fabricate body panels contain fillers such as talc and carbon, which significantly attenuate the radar. Often, this is due to designs that make the vehicle visible to other radar systems. Even when the substrate is radio wave-transmissive, the topcoat layer of paint affects radar transmission. The popular paint and basecoat metallic components containing effect pigments also affect the radar transmissivity of the panel. Furthermore, many of the design constraints of the vehicle's exterior panels are determined by factors that are unrelated to and, in some cases, contradictory to optimal radar efficiency. Therefore, it may be desirable to provide radar-compliant trims that constitute only a small part of the vehicle's appearance and can act as domes for underlying radar systems. In some cases, it is desirable for these trim elements to have a metallic appearance.

[0007] Technologies and systems have been developed to provide plastic elements with a metallic appearance, such as domes. However, all of these technologies and systems require complex layering of substrates sandwiched between layers of metallic appearance.

[0008]

[0008] One example includes U.S. Patent Application No. US2017 / 0057424 A1, which utilizes a nanolayer film stack that does not contain metal components. Such complex film stacks need to be protected from the external environment because they are susceptible to surface scratches. The use of such complex films, as well as the multiple layers required to provide backing and protection for the films, results in significant production costs and time, as well as several quality control issues and failure points. Other domes utilize complex combinations of films, paints, welded metals, and complex thermal masking, which also results in high production times and costs.

[0009]

[0009] EP1560288 describes an alternative means for providing a dome with visually metallic-like parts. This document discloses the deposition of a thin film of tin and / or an alloy of tin onto a transparent substrate. The substrate is then overlaid with a further opaque backing plate that is actually adhered to the front layer. However, the use of adhesives can increase production complexity and cost, and result in parts that are susceptible to delamination between the first and second layers. This can result in radio wave attenuation and inaccuracies in radar systems.

[0010]

[0010] Most elements in the market with a metallic appearance, particularly domes, include a first surface protection polymer that is adhered over a decorative coating or film, thereby confining it within the polymer layer. This serves to provide the element, particularly the dome, with a uniform thickness and, importantly, protects the decorative coating or film from the external environment. However, such methods are not suitable for providing larger decorative parts such as body panels.

[0011]

[0011] Decorative trims and plastic bumpers are not suitable for being formed of a plurality of plastic layers as has been proposed for such elements, particularly dome badges. Thus, there is a need to provide a metallic appearance automotive panel and trim having a radio-transparent decorative coating that is sufficiently robust and to provide a simplified production process.

[0012]

[0012] The above discussion of the background art is included to explain the context of the present invention. It should not be construed as an admission that any of the materials referred to were publicly available, known, or part of common general knowledge at the priority date of any one of the claims.

Summary of the Invention

Means for Solving the Problems

[0013]

[0013] The present invention provides a decorative element, particularly a dome, comprising a substrate that preferably has radio transparency and has a first surface on a first side and a second surface on a second side, and a first surface decorative coating that preferably has radio transparency on the substrate, the decorative coating including a decorative layer made of metal or an alloy containing metal. As a result, the present invention provides a decorative element, particularly a dome, having a preferably radio-transparent decorative coating on an outer surface of the element, unlike current decorative elements that typically include a plastic cover layer to protect the decorative coating.

[0014]

[0014] The simplified element with the first surface coating, particularly the dome, allows for more design freedom to provide a wider range of components that can be used in various situations. The decorative element can be used, in particular, as at least one handle, at least one control panel, at least one door handle, at least one trim, at least one decorative strip, at least one decorative panel, at least one decorative cover, at least one mirror surface, and / or at least one door wave element. Particularly with respect to a vehicle, the element, particularly the dome, is mainly limited to the central front position of the vehicle. However, in order to provide driver assistance, semi-autonomous and autonomous capabilities, it is desired to provide a 360° radar detection range of the vehicle. For example, by providing a trim that is radar-transparent and has a metallic appearance around the vehicle, the radar system can be positioned at various locations on the vehicle without compromising the appearance of the vehicle. Such radar-transparent trim is not possible using the prior art for providing a dome that uses a decorative layer sandwiched between two substrate layers.

[0015]

[0015] To enable use as a dome, the decorative coating must minimally attenuate or reflect radio wavelength electromagnetic frequencies (radio waves) while substantially absorbing or reflecting electromagnetic radiation within the visible spectrum. This can be achieved by providing one or more electrically insulated or non-conductive metal thin film layers, or one or more metal alloy layers.

[0016]

[0016] To provide a non-conductive alloy containing a metal, it is preferably to contain a semimetal. Thus, in some embodiments, the metal alloy further contains a semimetal. Preferred semimetals include germanium and / or silicon.

[0017] In embodiments where the alloy of the metal contains germanium, the concentration of germanium is preferably at least 25 wt% germanium, or at least 40 wt% germanium, or at least 45 wt% germanium, or at least 50 wt% germanium, or at least 55 wt% germanium. Such concentrations provide an optimal visual appearance and sufficiently low radio wave attenuation or reflection.

[0018]

[0018] Particularly to minimize radio wave attenuation and reflection, the decorative layer must be provided as a thin film. Thus, in some embodiments, the decorative layer is at most 100 nm thick, or at most 50 nm thick, or at most 40 nm thick, or 10 nm - 40 nm thick, or 20 nm - 40 nm thick, or 25 nm - 35 nm thick, or approximately 30 nm thick.

[0019]

[0019] Various metals can be used for the deposition of the metal layer or for the metal components of the alloy containing the metal. In some embodiments, the metal layer consists of a metal selected from the group of indium or tin. In some embodiments, the alloy contains a metal selected from the group of aluminum, silver, tin, indium, or chromium.

[0020]

[0020] Suitable radio wave transmissive alloys can include germanium and aluminum and optionally silicon, or germanium and silicon, or germanium and silver and optionally silicon, or germanium and indium and optionally silicon, or aluminum and germanium and / or silicon, or chromium and germanium and / or silicon.

[0021]

[0021] The inventors have confirmed that when providing a first surface decorative coating, it is advantageous to control the residual stress of the decorative coating. Without being bound by theory, it has been confirmed that it is important that the residual stress of the decorative coating is within a desired range compliant with the substrate (preferably, a synthetic polymer substrate).

[0022]

[0022] It has been confirmed that a first surface decorative element, particularly a radome, will exhibit sufficient toughness in a durability test when the overall residual stress of the preferably radio-transparent decorative coating is -120 MPa or more, or -50 MPa or more, or -40 MPa or more. More preferably, the overall residual stress of the preferably radio-transparent decorative coating is neutral (0 MPa) or tensile (>0 MPa).

[0023]

[0023] In an embodiment of a decorative coating where the decorative layer is aluminum and germanium, the net residual stress is preferably -120 MPa or more, preferably -50 MPa or more. In an embodiment of a preferably radio-transparent decorative coating where the decorative layer is chromium and germanium, the net residual stress is preferably -70 MPa or more, preferably up to +170 MPa.

[0024]

[0024] The residual stress of the decorative layer can be modified to some extent by modifying the deposition parameters and the thickness of the layer. However, additional layers such as a dielectric layer or a hard coat layer can be provided, whereby the overall residual stress of the decorative coating can be further modified within a desired range. These coatings, particularly the dielectric layer, can also preferably modify the optical properties and visual appearance of the radio-transparent decorative coating.

[0025] As a result, in some embodiments, the first surface decoration element, particularly the radome, includes a plurality of layers. In some embodiments, the plurality of layers of the decorative coating includes a stress control layer and / or a bonding layer. The location of the stress control layer in the multi-layer decorative coating can be any suitable location. However, in some embodiments, the stress control layer is preferably provided between the radio-transparent substrate and the decorative layer. Alternatively, or additionally, the stress control layer can be provided on a first side surface of the decorative layer. The stress control layer and / or the bonding layer can include at least one metal, at least one metal alloy, and / or at least one dielectric material.

[0026] In some embodiments where the preferably radio-transparent decorative coating comprises a plurality of layers, the preferably radio-transparent decorative coating includes at least one dielectric layer in addition to the decorative layer. In some embodiments, this dielectric layer is provided between the decorative layer and the preferably radio-transparent substrate. In some further embodiments, the plurality of layers of the preferably radio-transparent decorative coating includes at least one decorative layer between at least two dielectric layers. In some embodiments, the preferably radio-transparent decorative coating includes a plurality of dielectric layers and / or a plurality of decorative layers. Preferably, the dielectric layers and the decorative layers are alternating.

[0027] Preferred deposition methods that can be used to apply one or more layers of the preferably radio-transparent decorative coating to the substrate can be selected from any physical vapor deposition system. Such systems can include thermal evaporation, electron beam evaporation (with or without ion beam assistance), sputter deposition, pulsed laser deposition, electrohydrodynamic deposition, and cathodic arc deposition. Additionally, the surface of the preferably radio-transparent substrate can first be treated prior to deposition to improve the adhesion between the decorative layer and the substrate. In some embodiments, the surface treatment can be selected from plasma discharge, corona discharge, glow discharge, and UV radiation.

[0028]

[0028] In some embodiments, preferably the radio - transparent decorative coating can be adjusted to achieve a desired stress window by optimizing one or more deposition parameters of the layer. These parameters include sputtering power, gas pressure, gas dopants (such as nitrogen), and coating thickness. The stress can also be adjusted by introducing a thermal stress component by substrate heating or by performing a pretreatment immediately prior to the deposition of the layer or preferably the radio - transparent decorative coating.

[0029]

[0029] Means for measuring the residual stress within the decorative coating or within an individual layer are known in the art. For example, the decorative coating can be placed on a glass slide, and this glass slide can be placed within a stress - measuring device (such as Sigma Physik SIG - 500SP) before and after the deposition of the layer or coating.

[0030]

[0030] The residual stress can be corrected by the deposition of a layer of material that, when deposited, generates a desired level of stress to compensate for the inherent residual stress of the decorative layer. Suitable materials include SiO x 、SiO x N y 、CrN x 、NbO x 、TaO x 、and ZrO x , where both x and y are preferably between 0.1 and 2.0. In some embodiments including a dielectric layer, the dielectric layer is SiO x or silicon dioxide. Such a layer can preferably be used to control the overall stress of the radio - transparent decorative coating and can also affect its visual properties depending on the positioning of the layer within the preferably radio - transparent decorative coating.

[0031]

[0031] Thus, when it is necessary to change the desired optical effect of the decorative layer, it is clear that accompanying changes are likely to be required in one or more additional layers of the decorative coating in order to ensure that the overall residual stress of the decorative coating is maintained within the desired window.

[0032]

[0032] The provision of an element, particularly a preferably radio-transparent decorative coating on the first surface of the radome, exposes the preferably radio-transparent decorative coating to the external environment. This results in the preferably radio-transparent decorative coating being exposed to various conditions such as UV light, temperature limits, rain, dust, mud, and various chemicals. Further, in applications such as external automotive trim, the decorative element, particularly the radome, is further exposed to flying objects such as rock chips. Thus, the preferably radio-transparent decorative coating of the element, particularly the radome, needs to be tough enough to be used in such an environment. To improve the toughness of the preferably radio-transparent decorative coating, in some embodiments, the preferably radio-transparent decorative coating may include at least one protective hard coat layer. Typically, this is the top layer of the preferably radio-transparent decorative coating and thus protects the underlying layers. However, in some embodiments, there may be additional capping layers that provide properties such as hydrophobicity, hydrophilicity, oleophobicity, lipophilicity, and oil repellency, or combinations thereof. The protective hard coat layer may add optical features to the decorative element. In particular, the protective hard coat layer may include at least partially a light scattering additive in order to further affect the appearance of the decorative element in a desired manner.

[0033]

[0033] Furthermore, the hard coat layer can function as a bonding layer or a stress control layer within a multi-layer, preferably radio-transparent decorative coating. As a result, in some embodiments, the preferably radio-transparent decorative coating includes a hard coat layer between the decorative layer and the preferably radio-transparent substrate. Preferably, the decorative coating includes a hard coat layer provided on a first surface of the preferably radio-transparent substrate. In some embodiments, the hard coat layer is between the decorative coating and the preferably radio-transparent substrate (however, it may not be in direct contact with the preferably radio-transparent substrate).

[0034]

[0034] Without being bound by theory, the hard coat layer likely improves the bonding of subsequent layers (such as the decorative layer) to the underlying layer or preferably radio-transparent substrate and helps control the differential stress between the layers and preferably the overall residual stress of the radio-transparent decorative coating.

[0035]

[0035] Additional layers can be at the interface between the hard coat layer applied to the first surface of the preferably radio-transparent substrate and the decorative layer. In some embodiments, a dielectric layer is provided between the decorative layer and the protective hard coat.

[0036]

[0036] Suitable materials for providing the hard coat layer are known in the art. For example, the hard coat layer can include one or more wear-resistant layers including materials selected from the group consisting of organosilicon, acrylic, urethane, melamine, and amorphous SiOxCyHz.

[0037] As discussed above, it is advantageous to preferably keep the residual stress of the radio wave transmissive decorative coating within an optimal range of -120 MPa or more, or -70 MPa or more, or -50 MPa or more, or -40 MPa or more. Since the protective hard coat layer can affect the overall residual stress of the decorative coating, in some embodiments, preferably the overall residual stress of the radio wave transmissive decorative coating is measured with the protective hard coat. In some embodiments, the overall residual stress is measured without the protective hard coat.

[0038]

[0038] The radio wave transmissive substrate for the decorative coating is sufficiently radio wave transmissive and can be any suitable substrate that is suitable for the intended purpose of the element, particularly the dome. However, preferably, the radio wave transmissive substrate is acrylonitrile - ethylene - styrene (AES), acrylonitrile - butadiene - styrene (ABS), acrylonitrile - styrene - acrylate (ASA), polyamide (PA), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), poly(methyl methacrylate) (PMMA), polyoxymethylene (POM), polypropylene (PP), polyurethane (PU), polyvinyl chloride (PVC), high flow AES, acrylonitrile - (ethylene - propylene - diene) - styrene (AEPDS), a mixture of thermoplastic polymers, or a PC - ABS blend thermoplastic, etc., a synthetic polymer. In some embodiments, the radio wave transmissive substrate is preferably polycarbonate or polypropylene.

[0039]

[0039] Radio waves can be significantly attenuated by water, particularly ice, which can condense on the element, particularly the dome, under cold conditions. This is particularly widely recognized when the element, particularly the dome, is used to provide an external panel of a vehicle. Therefore, to remove ice from the element, particularly the dome, and enable optimal functionality, some embodiments of the decorative element of the present invention, particularly the dome, include a heating element.

[0040]

[0040] In a preferred form, the heating element includes a resistance wire. The resistance wire can be used to provide Joule heat. When an electric current flows through the resistance wire, the temperature of the wire rises, thereby providing heat. The amount of heat generated is proportional to the product of the resistance of the wire and the square of the current. Preferably, the wire is provided or formed within a polymer such that the heating element comprises a circuit that can be formed within the polymer. The polymer can be a separate film, and the heating element is formed into the polymer film. This film can then be provided preferably between a radio-transparent substrate and preferably a radio-transparent decorative coating. As a result, the heating element is preferably protected from the environment by the radio-transparent decorative coating but is close to the surface to effect rapid ice removal.

[0041]

[0041] In the case of an element in the form of a radome such as a radio-transparent substrate, the polymer providing the film for the heating element needs to be radio-transparent. As such, the polymer film can be made from any compliant polymer such as those used for radio-transparent substrates. Thus, the polymer for the film can be selected from acrylonitrile - ethylene - styrene (AES), acrylonitrile - butadiene - styrene (ABS), acrylonitrile - styrene - acrylate (ASA), polyamide (PA), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), poly(methyl methacrylate) (PMMA), polyoxymethylene (POM), polypropylene (PP), polyurethane (PU), polyvinyl chloride (PVC), high flow AES, acrylonitrile-(ethylene - propylene - diene)-styrene (AEPDS), a mixture of thermoplastics, or a PC - ABS blend thermoplastic. In some embodiments, the polymer film is polycarbonate or polypropylene. Indeed, in some embodiments, the heating element is preferably provided on a radio-transparent substrate.

[0042]

[0042] To be suitable for use as a radome, the decorative element of the present invention need not be completely radio wave transmissive and can thus have an acceptable level of radio wave attenuation. In some particular embodiments, the decorative radome has a radio wave signal attenuation of less than 4 dB (bidirectional), or less than 2 dB (unidirectional), or more preferably less than 2 dB (bidirectional), or less than 1.5 dB, preferably less than 1 dB (unidirectional) across the signal path within the frequency range of 20 - 81 GHz, or 76 - 81 GHz, or 76 - 77 GHz, or when the frequency is about 77 GHz, or about 79 GHz, or about 81 GHz.

[0043]

[0043] To achieve sufficient radio wave transmissivity, the decorative layer made of metal or an alloy containing metal must not be substantially conductive. As a result, in some embodiments, the decorative layer has a sheet resistance greater than 10 6 ohms per square (Ω / □).

[0044]

[0044] The optimal thickness of the radio wave transmissive substrate can affect the attenuation of the passing radio waves. Since the decorative radome of the present invention can be used with a radar system that emits frequencies in the range of 76 - 81 GHz, the optimal thickness of the polycarbonate substrate is a multiple of about 1.15 mm. Thus, in some embodiments, the thickness of the radio wave transmissive substrate is about 1.15 mm, 2.3 mm, or 2.45 mm. In some embodiments, especially for use with vehicles, the radio wave transmissive substrate is 2 mm - 2.6 mm thick. This thickness also provides advantages in terms of weight, cost, formability, and toughness among several design considerations.

[0045]

[0045] The present invention further provides a radar system including a radio wave transmitter, a radio wave receiver, and a decorative radome as described herein. The optimal thickness of the radio wave transmissive substrate depends on the wavelength of the radio waves emitted from the radio wave transmitter and the relative permittivity of the substrate. Thus, in some embodiments, the thickness of the radio wave transmissive substrate of the radome is

[0046] [Number]

[0047] is a multiple of, and λi is the wavelength of the radio wave transmitted from the radio transmitter passing through the substrate. Preferably, the radio transmitter transmits radio waves at a frequency of 20-81 GHz, or 76-81 GHz, or 76-77 GHz, or about 77 GHz, or about 79 GHz, or about 81 GHz.

[0048]

[0046] Certain embodiments are illustrated by the following figures. It should be understood that the following description is for the purpose of illustrating certain embodiments only and is not intended to be limiting with respect to the description.

Brief Description of the Drawings

[0049]

Figure 1

[0047] A diagram illustrating an embodiment of a decorative element of the present invention, particularly a radome, showing that radio waves (long diagonal lines) can pass through the radome while at the same time showing reflection of visible light (short diagonal lines) from the decorative layer.

Figure 2

[0048] A diagram illustrating an embodiment of a decorative element of the present invention, particularly a radome, including an upper coating that scatters visible light (short diagonal lines) to provide a satin appearance.

Figure 3

[0049] A diagram illustrating an embodiment of a decorative element of the present invention, particularly a radome, including an intermediate dielectric layer between the substrate and the decorative layer.

Figure 4

[0050] A diagram illustrating an embodiment of a decorative element of the present invention, particularly a radome, including dielectric layers above and below the decorative layer.

Figure 5

[0051] A diagram illustrating an embodiment of a decorative element of the present invention, particularly a radome, including a multi-stack decorative coating with multiple decorative layers and multiple dielectric layers.

Figure 6

[0052] A diagram illustrating an embodiment of a decorative element of the present invention, particularly a radome, preferably including a heating element between a radio wave transmissive substrate and the decorative layer.

Figure 7

[0053] A diagram illustrating a radar system including a radio transmitter / receiver and an element in the form of a radome according to the present invention.

Figure 8

[0054] A diagram illustrating the measured change in the attenuation of 77 GHz radio waves through uncoated polycarbonate as a result of the change in polycarbonate thickness.

Figure 9

[0055] A diagram illustrating the average attenuation of radio waves in the 76 - 77 GHz and 79 - 81 GHz bands across polycarbonate with thicknesses of 2 mm (A) and 2.3 mm (B).

Figure 10

[0056] A diagram illustrating the measured change in the attenuation of 77 GHz radio waves through coated polycarbonate compared to uncoated polycarbonate as a result of the change in polycarbonate thickness.

Figure 11

[0057] A diagram illustrating the measured CIELAB color of elements with a gloss coating and a satin coating, particularly a radome.

Mode for Carrying Out the Invention

[0050]

[0058] Throughout this specification, references to layers are made in relation to a plastic substrate and in relation to each other. Thus, the following terms are used to define the spatial relationship of the coatings in relation to the substrate and the spatial relationship between the layers included in the coatings.

[0051]

[0059] The "first side" is understood to be the side of the substrate, coating, or a particular layer that faces away from the radio wave transmitting or receiving device during use. As such, the first side is the side facing the external environment. In the context of a vehicle, this is the side visible from outside the vehicle.

[0052]

[0060] The "second side" shall be understood as the side opposite to the first side. In the context of use, this is the side facing the radio wave transmitting device or the receiving device. Typically, the second side is not visible when the element, particularly the radome, is in use.

[0053]

[0061] The "first surface" shall be understood to refer to the surface on the first side of the substrate, coating, or designated layer.

[0062] The "second surface" shall be understood to refer to the surface on the second side of the substrate, coating, or designated layer.

[0054]

[0063] The term "reflective" (without modifiers such as "radio wave") typically refers to the reflection of visible light within the nanometer wavelength and the frequency range of 400 - 800 THz.

[0064] References to radio waves throughout this specification typically refer to frequencies in the range of 10 MHz to 3000 GHz. In preferred embodiments, and in the context of automobiles, the frequencies are typically 1000 MHz to 100 GHz. In some specific embodiments related to radomes for vehicles, the frequencies are 21 GHz to 81 GHz, or about 24 GHz to about 79 GHz, or about 77 GHz to about 79 GHz, or about 24 GHz, about 77 GHz, or about 79 GHz. Even more preferred frequencies are in the range of about 1575 MHz ± 200 MHz. In this context, the use of "about" does not exclude an explicit limitation to the specified band (e.g., 24 GHz), but anticipates the typical bandwidth spread used in applications such as automotive radar systems. These bandwidths are known in the art; see, for example, Hasch et al., "Millimeter-Wave Technology for Automotive Radar Sensors in the 77 GHz Frequency Band", IEEE Transactions on Microwave Theory and Techniques (Volume: 60, Issue: 3, March 2012).

[0055]

[0065] When the terms "transparent" and "opaque" are used without a qualifying phrase (such as "radio wave" or "radar"), they refer to being visually transparent or opaque, and thus are references to the transmission or absorption of visible light as defined above.

[0056]

[0066] As discussed above, the decorative element of the present invention, particularly the radome, comprises a first surface coating which is a coating on the first side and in contact with the first surface of the substrate. The first surface coating may include a plurality of "stacked" layers, each layer having a first surface and a second surface, the first surface of one layer abutting the second surface of the layer above it, and the layer above it itself having a first surface. As a result, the use of the terms "first side", "second side", "first surface", and "second surface" needs to be read and interpreted in the relative context in which they are used.

[0057]

[0067] The decorative element according to the present invention, particularly the radome (1), is illustrated in FIGS. 1 to 6 and comprises a preferably radio wave transmissive substrate (2) having a first surface (3) on a first side and a second surface (4) on a second side, and a preferably radio wave transmissive decorative coating (5) on the first surface (3) of the preferably radio wave transmissive substrate (2), the preferably radio wave transmissive decorative coating (5) preferably comprising a decorative layer (6) made of metal or an alloy containing metal.

[0058]

[0068] As illustrated in FIGS. 1 and 2, while enabling radio waves to cross the element, particularly the radome (long dashed line), a part of the visible light (short dashed line) is reflected from the decorative layer (6) such that the appearance of the element, particularly the radome (1), is colored or reflective.

[0059] Radio wave transmissive substrate

[0069] This element of the invention, in particular the radome (1), is for use in the intended radio wave path of a transmitter and / or receiver for a wireless communication system or a radar system, and as such, the design of such an element, in particular the radome, can be determined by its intended use. As a result, the selection of the material for the radio wave transmissive substrate (2) will be partially determined by design considerations, which is not based solely on the degree of radio wave transmissivity, such as robustness, formability, resistance to extreme temperatures, and cost. As such, the radio wave transmissive substrate (2) can be any substrate that attenuates the desired radio wave frequencies to an acceptable level for the desired application. As will be understood, all substrates will attenuate and reflect radio waves to some extent.

[0060]

[0070] However, in some embodiments of the invention, the substrate is a polymer, preferably a synthetic polymer. As is understood in the art, radio wave transmissive substrates typically exhibit resistance to electrical conductivity (i.e., are insulating or dielectric). Suitable polymers for the substrate (2) include, but are not limited to, acrylonitrile - ethylene - styrene (AES), acrylonitrile - butadiene - styrene (ABS), acrylonitrile - styrene - acrylate (ASA), polyamide (PA), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), poly(methyl methacrylate) (PMMA), polyoxymethylene (POM), polypropylene (PP), polyurethane (PU), polyvinyl chloride (PVC), high flow AES, acrylonitrile-(ethylene - propylene - diene)-styrene (AEPDS), mixtures of thermoplastic plastics, or PC - ABS blend thermoplastic plastics. In some embodiments, the radio wave transmissive substrate (2) will be formed of polycarbonate or polypropylene.

[0061] Decorative coating

[0071] The decorative layer (6) of the decorative coating (5) is preferably a reflective layer and preferably comprises any suitable metal or alloy containing metal that provides the desired reflectivity or appearance while being radio - transmissive. In some embodiments, the metal forming the decorative layer (6) is a transition metal. In some embodiments, the metal forming the decorative layer (6) is indium or tin.

[0062]

[0072] In some embodiments where the decorative layer (6) is an alloy containing metal, the alloy comprises a metal selected from the group consisting of aluminum, tin, indium, or chromium. In some embodiments, the decorative layer (6) comprises a semi - metal. The semi - metals include silicon, boron, germanium, arsenic, antimony, and / or tellurium. In particularly preferred embodiments, the semi - metal is germanium or silicon. In the most preferred embodiments, the semi - metal is germanium. Suitable semi - metal / metal alloys include germanium and aluminum and / or silicon, or germanium and silicon, or germanium and silver and optionally silicon, or germanium and indium and optionally silicon, or chromium and germanium and / or silicon. In some obvious embodiments, the alloy does not contain silicon and aluminum.

[0063]

[0073] In embodiments where the metal alloy contains germanium, the concentration of germanium can be at least 25 wt% germanium, or at least 40 wt% germanium, or at least 45 wt% germanium, or at least 50 wt% germanium, or at least 55 wt% germanium.

[0064]

[0074] Methods for providing thin film layers such as a decorative layer (6) made of metal or an alloy containing metal are known in the art. However, preferably, the decorative layer (6) is deposited by physical vapor deposition (PVD). Suitable PVD methods can include magnetron sputtering and evaporation which can be resistive thermal evaporation or electron beam evaporation. In some embodiments, the decorative layer (6) is additionally or alternatively deposited by magnetron sputtering and / or reactive sputtering, preferably involving the use of reactive gases and / or monomers, in particular to create the decorative layer (6) in the form of a compound.

[0065]

[0075] In some embodiments, the decorative coating (5) includes a plurality of layers with the decorative layer (6) in contact with one or more additional layers. In some embodiments, the plurality of layers of the decorative coating (5) includes a bonding layer. Typically, the bonding layer will contact the substrate directly and thus form the first layer within the multi-layer stack. For example, a hard coat layer (7) can be provided on the first surface (3) of the substrate (2) before the addition of further layers within the decorative coating. Such a hard coat layer (7) acts to improve the bonding strength of the decorative layer (6) to the substrate (2) and thus reduce the likelihood of peeling of the coating (5) from the substrate (2). The hard coat (7) can also preferably affect the overall residual stress of the radio-transparent decorative layer (5) and as such can act, at least in part, as a stress control layer.

[0066]

[0076] In some embodiments, the preferably radio-transparent decorative coating (5) includes a stress control layer which can be below or above the preferably radio-transparent decorative layer (6). Thus, as illustrated in FIGS. 1, 2, 4, 5, and 6, the stress control layer (8) is on the first side (preferably the first surface) of the decorative layer (6).

[0067]

[0077] In some embodiments, as illustrated in FIGS. 4 and 5, the preferably radio-transparent decorative coating may include a stress control layer (8) under the decorative layer (6). In these embodiments, the stress control layer (8) is preferably between the radio-transparent substrate and the decorative layer (6). The stress control layer may preferably be positioned on top of the hard coat (7) on the first surface (3) of the radio-transparent substrate (2) and under the decorative layer (6).

[0068]

[0078] In some embodiments, the plurality of layers of the preferably radio-transparent decorative coating (5) includes at least one dielectric layer, which in this illustrated embodiment is the stress control layer (8). However, the dielectric layer may also modify the visual properties of the decorative coating (5). This is particularly relevant in embodiments with multiple decorative layers (6) or a top dielectric layer (8) (FIGS. 1, 2, 4, 5, and 6). Suitable dielectrics for thin film deposition are known in the art and include oxides such as hafnium dioxide (HfO2), aluminum oxide (Al2O3), zirconium dioxide (ZrO2), titanium dioxide (TiO2), and silicon dioxide (SiO2). In a preferred form, the dielectric layer is silicon dioxide (SiO2).

[0069]

[0079] In some embodiments, the preferably radio-transparent decorative coating (5) includes at least one layer (6) made of a metal or an alloy containing a metal between at least two dielectric layers (8) (see FIGS. 4 and 5). Additionally, in the embodiment illustrated in FIG. 5, the decorative coating (5) includes two decorative layers (6) sandwiched between alternating dielectric layers (8). These multilayer stacks preferably enable the adjustment of the radio-transparent decorative coating (5), including its color and residual stress.

[0070]

[0080] A different visual appearance may be achievable by providing a preferably radio-transparent decorative coating that includes a plurality of stacked layers. Examples of possible multilayer stacks include the following. ·SiO2:AlGe:SiO2:AlGe:SiO2 ·SiO2:CrGe:SiO2:CrGe:SiO2 ·AlGe:SiO2:AlGe:SiO2 ·CrGe:SiO2:CrGe:SiO2 ·AlSi:SiO2:AlSi:SiO2

[0081] Such a visual stack may preferably include a stress control layer to optimize the residual stress of the radio - transmissive decorative coating (5) within a desired window. Preferably, this stress window is - 120 MPa or more, or - 70 MPa or more, or - 50 MPa or more, or - 40 MPa or more. Suitable materials for controlling stress include dielectric layers such as additional silicon dioxide layers, which can be adjusted (e.g., by varying thickness and deposition conditions) to provide the desired stress range without changing the visual appearance of the decorative coating.

[0071] Protective hard coat

[0082] The essential function of the cover element, particularly the radome, is to provide protection for the system, particularly the radar equipment, from the environment. As such, the element, particularly the radome, is susceptible to degradation, wear, and damage. This exposure is further amplified when the element, particularly the radome, is positioned at the front of a vehicle that is routinely exposed to relatively high speeds, abrasion, flying objects, and chemicals used for cleaning.

[0072]

[0083] As a result, in a preferred embodiment of the present invention, the outermost layer of the decorative coating (5) is a protective hard coat (9). In this regard, a coating referred to as a "hard coat" is a coating that is harder and more resilient (e.g., chemically resilient) than the underlying layer, thereby increasing the wear resistance, environmental damage resistance, or chemical resistance of the element, particularly the radome.

[0073]

[0084] As discussed above, the intermediate layer of the decorative coating (5) may also include a hard coat layer (7). This may be a hard coat of the same material or a different material as the protective hard coat (9).

[0074]

[0085] In some embodiments, the hard coat increases the abrasion resistance of the surface. The abrasion resistance can be measured through standard tests such as ASTM F735 "Standard Test Method for Abrasion Resistance of Transparent Plastics and Coatings Using the Oscillatory Sand Method", by means of a Taber abrasion tester, or using known steel wool tests such as ASTM D4060 "Standard Test Method for Abrasion Resistance of Organic Coatings".

[0075]

[0086] The requirement for decorative elements, especially for many automotive exterior parts such as domes, is "chemical resistance", which refers to the ability to withstand exposure to normal solvents such as diesel oil, petroleum, battery acid, brake fluid, antifreeze, acetone, alcohol, automatic transmission fluid, hydraulic fluid, and ammonia-based window cleaners. In this regard, the hard coats (7, 9) are ideally understood to provide such chemical resistance to at least the first surface of the element, especially the dome.

[0076]

[0087] The hard coats (7, 9) are preferably formed from one or more abrasion-resistant layers and may include a primer layer that firmly bonds to the underlying layer and forms a preferred surface for the subsequent upper layer. The primer layer can be provided by any suitable material, for example, an organic resin such as a copolymer of acrylic polymer, acrylic monomer and methacryloxy silane, or a copolymer of methacrylic monomer and acrylic monomer having a benzotriazole group or a benzophenone group. These organic resins can be used alone or in combination of two or more.

[0077]

[0088] The hard coat layer (7, 9) is preferably an organic silicon, acrylic, urethane, melamine, or amorphous SiO x C y H zIt is formed from one or more materials selected from any group.

[0078]

[0089] Commercially available hard coatings include undercoats of Momentive products: PHC-587B, PHC-587C2, PHCXH100P, AS4700F, UVHC 5000 (UV curable), and PR660 (SDC Technologies), followed by two-part products coated with MP101 (SDC Technologies).

[0079]

[0090] Most preferably, the hard coat layers (7, 9) are organic silicon layers, which is due to their excellent abrasion resistance and compatibility with physical vapor deposition films. For example, a hard coat layer containing an organic silicon polymer can be formed from the following compounds: methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltracetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, gamma-chloropropyltrimethoxysilane, gamma-chloropropyltriethoxysilane, gamma-chloropropyltripropoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropyltriethoxysilane, gamma-(beta-glycidoxyethoxy)propyltrimethoxysilane, beta-(26,4-epoxycyclohexyl)ethyltrimethoxysilane, beta-(26,Compounds formed from compounds selected from trialkoxysilanes or triacyloxysilanes such as (4-epoxycyclohexyl)ethyltriethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-meraptopropyltrimethoxysilane, gamma-mercaptopropyltriethoxysilane, N-beta(aminoethyl)-gamma-aminopropyltrimethoxysilane, beta-cyanoethyltriethoxysilane, and the like, and dialkoxysilanes or diacyloxysilanes such as dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, gamma-glycidoxypropylmethyldimethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, gamma-glycidoxypropylphenyldimethoxysilane, gamma-glycidoxypropylphenyldiethoxysilane, gamma-chloropropylmethyldimethoxysilane, gamma-chloropropylmethyldiethoxysilane, dimethyldiacetoxysilane, gamma-methacryloxypropylmethyldimethoxysilane, gamma-methacryloxypropylmethyldiethoxysilane, gamma-mercaptopropylmethyldimethoxysilane, gamma-mercaptopropylmethyldiethoxysilane, gamma-aminopropylmethyldimethoxysilane, gamma-aminopropylmethyldiethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, and the like may be used.,

[0080]

[0091] The hard coat layers (7, 9) can be coated by solvent evaporation following immersion coating in a liquid, or by plasma enhanced chemical vapor deposition (PECVD) with a suitable monomer, flow coating, or spray coating. To improve the abrasion resistance of the hard coats (7, 9), a subsequent coating of the hard coat can preferably be added within 48 hours so as to avoid the aging degradation and contamination of the previous coating.

[0081]

[0092] The thickness of the hard coat layers (7, 9) is preferably selected to assist in providing suitable abrasion resistance or preferably to improve the bonding of subsequent layers to the radio - transmissive substrate (2). Suitable abrasion resistance will be determined by the required application and the user's desires. In some applications, suitable abrasion resistance can be considered to be a Bayer abrasion rate of 5 with respect to an uncoated preferably radio - transmissive substrate (2) (such as polycarbonate), or alternatively, by a Taber abrasion test with less than 15% delta haze (% haze is measured according to ASTM D1003) after testing with a 500 g load and a CS10F wheel for 500 cycles. When these requirements are met and an organosilicon is used as the hard coat layer (7, 9), the thickness of the hard coat is preferably at least 1 μm thick on average and / or has a maximum thickness of 25 μm. In some embodiments, the thickness of the hard coat layer (7) provided on the first surface (3) is from 1 μm to 15 μm. In some embodiments, the thickness of the hard coat layer (7) provided on the first surface (3) is from 2 μm to 10 μm, or from 2 μm to 9 μm. In some embodiments, the thickness of the protective hard coat layer (9) is from 5 μm to 25 μm. In some embodiments, the thickness of the protective hard coat layer (9) is from 8 μm to 20 μm, or from 8 μm to 16 μm.

[0082]

[0093] The protective hard coat (9) can also modify the appearance of the decorative layer (6). As illustrated in FIG. 2, the protective hard coat (9) includes additives to scatter the reflected visible light. As a result, the decorative layer (6) has a "satin" appearance on the outer surface.

[0083]

[0094] A further coating on what is discussed above can be applied to the first surface of the decorative coating (5) to modify the surface properties of the element, particularly the dome (1). For example, the cap layer can also be provided by a material having properties including hydrophobicity, hydrophilicity, oleophobicity, fat solubility, and oil repellency, or combinations thereof.

[0084] Coating residual stress

[0095] The importance of residual stress, the use of interface layers in controlling residual stress, and the determination of residual stress parameters are described in WO2011 / 075796 and U.S. Patent No. US9,176,256 B2, each entitled "PLASTIC AUTOMOTIVE MIRRORS", and each of these is hereby incorporated by reference in its entirety for all purposes.

[0085]

[0096] The interfaces under high stress between the layers of the decorative coating (5) and between the decorative coating (5) and the substrate (2) should ideally be avoided to prevent high stress regions that would be failure points. For example, a compressive layer pulls in one direction against a tensile layer that pulls in the opposite direction, generating interface stress. It has been found that by controlling (reducing) this interface stress, the toughness of the decorative coating (5) can be improved.

[0086]

[0097] Therefore, the inventors have found that it is preferable to control the internal stress parameters of the decorative coating (5) so that the differential stress is minimized. The inventors have further found that it is preferable to control the internal stress parameters of the decorative coating (5) so that the net residual stress exceeds -120 MPa. In some embodiments, the net residual stress exceeds -70 Mpa, or exceeds -50 Mpa, or exceeds -40 MPa. In some preferred embodiments, the net residual stress is neutral or tensile (i.e., greater than 0 MPa). In particular, for the decorative coating (5) including the decorative layer (6) of aluminum and germanium, the net residual stress exceeds -120 MPa, or exceeds -50 Mpa, or exceeds -40 MPa. In an embodiment of the decorative coating (5) where the decorative layer (6) is chromium and germanium, the net residual stress preferably exceeds -70 Mpa, preferably up to +170 Mpa.

[0087]

[0098] Regarding the ability to control the internal stress parameters, ideally, the stress of the entire coating system will be controlled in both magnitude and mode. The term "residual stress" is taken to mean the combined stress of the plurality of layers forming the decorative coating (5), which may or may not include the protective hard coat (9). In a preferred embodiment, the residual stress is measured or calculated with the protective hard coat (9).

[0088]

[0099] In order to manufacture decorative elements, particularly domes, in a manner that allows control of the measured residual stress within the decorative coating (5), the inventors have determined that it is beneficial to know the stress ranges of the individual layers such that when they are combined, they result in the desired measured residual stress.

[0089] Dome Attenuation and Technical Characteristics

[0100] The decorative radome of the present invention substantially does not attenuate electromagnetic frequencies from 10 MHz to 3000 GHz. Specifically, in some embodiments, the radome has a radar attenuation of less than 2 dB in one direction (4 dB in both directions) across the signal path, preferably less than 1 dB in one direction (2 dB in both directions) across the signal path. Further, the decorative layer (6) comprising a metal or an alloy of metal and semimetal has a sheet resistance greater than 10 6 ohms per square (Ω / □). The surface resistivity of the decorative layer (6) can be determined using the four-point method using a four-point probe according to JIS K7194.

[0090]

[0101] When the radar signal passes through the radome (1), the front and rear surfaces must be parallel or substantially parallel in order to minimize the refraction of the radar signal. Further, there should be no significant change in material density such as gaps, air bubbles, or water ingress inside the radome (1), and the decorative layer (5) should have a uniform thickness.

[0091]

[0102] The radio wave attenuation and reflectivity will be determined by the user's requirements, application, the frequencies used, and the equipment in use. However, in some embodiments, there will be a maximum attenuation of 2 dB in one direction (4 dB in both directions) at specific operating frequencies of 1.575 GHz, 2.0 GHz, and / or 76 - 81 GHz. In some embodiments, there will be an attenuation of less than 2 dB, preferably less than 1.5 dB in one direction, at 1.575 GHz, 2.0 GHz, 24 GHz, 77 GHz, or 79 GHz. In some embodiments, there will be a maximum attenuation of 1 dB in one direction (4 dB in both directions) at specific operating frequencies of 76 - 81 GHz. In some embodiments, there will be an attenuation of less than 1 dB in one direction at 1.575 GHz, 2.0 GHz, 24 GHz, 77 GHz, or 79 GHz.

[0092] Radar system

[0103] In some embodiments, the present invention provides a radar system as illustrated in FIG. 7, including a radio transmitter (10), a radio receiver (10), and a decorative radome (1) as described herein.

[0093]

[0104] The radome (1) can be present within the radio wave path of both the radio receiver and transmitter (which can be integrated into one device), or there can be a radome associated with the transmitter and a separate radome associated with the receiver.

[0094]

[0105] The substrate attenuates the radio wave signal as the radio wave signal passes through the radome (1). A portion of this attenuation is the product of the reflection of the radio wave signal from the first surface (3) of the substrate (2) when the radio wave emitted from the transmitter passes through the radome. As a result, the attenuation due to reflection is determined by the thickness of the substrate (2) (and coating) related to the wavelength of the radio wave signal. The wavelength of the radio wave passing through the substrate varies depending on the relative permittivity of the dielectric of the substrate. Therefore, the substrate thickness providing minimum attenuation is given by the formula

[0095]

Equation

[0096] where m is an integer and λi is the wavelength of the radio wave transmitted from the radio transmitter passing through the substrate, and the radome is designed according to this radio transmitter. As a result, in some embodiments, the thickness of the radome substrate is

[0097]

Equation

[0098] a multiple of.

[0106] Radar systems inside vehicles typically use microwaves to provide line-of-sight detection of objects. Three frequencies that are now often used for automobiles are 24 GHz, 77 GHz, and 79 GHz. In recent years, 77 GHz and 79 GHz have become the dominant frequencies used, because these frequencies provide improved range and resolution compared to the 24 GHz frequency. Specifically, 77 GHz can identify objects with three times higher resolution than 24 GHz while using an antenna size that is three times smaller in height and width (having only one-ninth the area). However, radar systems using frequencies of 1.575 GHz and / or 2.0 GHz are also becoming increasingly common.

[0099]

[0107] Radar systems using 24 GHz can utilize both a narrow band (NB) of 200 MHz from 24.05 GHz to 24.25 GHz and an ultra-wide band (UWB) of 5 GHz from 21.65 GHz to 26.65 GHz.

[0100]

[0108] Due to spectrum regulations and standards developed by the European Telecommunications Standards Institute (ETSI) and the US Federal Communications Commission (FCC), the use of the UWB band will be phased out by 2022 in both Europe and the US (the "sunset date").

[0101]

[0109] 24 GHz NB and UWB have been replaced by frequencies in the 71 - 81 GHz range, where the 76 - 77 GHz range represents long-range radar (LRR) and 77 - 81 GHz represents short-range radar (SRR). The 77 - 81 GHz range provides a sweep bandwidth of up to 4 GHz, which is much larger than the 200 MHz available with 24 GHz NB.

[0102]

[0110] In some embodiments, the radome is designed for or used in a radar system in which the radio transmitter (10) transmits radio waves at frequencies in the range of 20 GHz to 81 GHz. In some embodiments, the radome is designed for or used in a radar system in which the radio transmitter transmits radio waves at a frequency of 76 - 81 GHz or 76 - 77 GHz, or is approximately 77 GHz, or is approximately 79 GHz.

[0103]

[0111] To minimize attenuation, in some embodiments of the decorative radome, the substrate is 2 mm to 2.6 mm thick. In some embodiments, the substrate is approximately 1.15 mm, 2.3 mm, or 2.45 mm thick.

[0104] Heated element, in particular radome

[0112] Radio waves are typically attenuated by water, and in particular by ice. Furthermore, the deposition of water and ice on the surface of the decorative element is undesirable for other reasons, for example for safety and appearance. Therefore, it is desirable to prevent ice formation on the surface of the element, in particular the radome. As a result, as illustrated in FIG. 6, the decorative element of the present invention, in particular the radome (1), includes a layer including a heating element (11).

[0105]

[0113] Suitable heating elements compliant with the use with the element, in particular the radome, are disclosed in DE102014002438A1, DE10156699A1, US20180269569A1, which are hereby incorporated by reference in their entirety for all purposes.

[0106]

[0114] In a preferred embodiment, the heating element (11) comprises a radar-transparent polymer with an embedded resistive wire circuit (12) that can be embedded or molded within a heating element substrate (11) to form a network that substantially covers the element, in particular the radome.

[0107]

[0115] The heating element (11) can be provided by a polymer film that includes a circuit (12) that can preferably be provided between a radio wave transmissive substrate (2) and a decorative coating (5). As such, the polymer film (11) also preferably needs to be radio wave transmissive. Consequently, the polymer film (11) can preferably be made of any suitable polymer disclosed for the radio wave transmissive substrate (2). Thus, the polymer film (11) can be made of a polymer selected from the group including, but not limited to, acrylonitrile - ethylene - styrene (AES), acrylonitrile - butadiene - styrene (ABS), acrylonitrile - styrene - acrylate (ASA), polyamide (PA), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), poly(methyl methacrylate) (PMMA), polyoxymethylene (POM), polypropylene (PP), polyurethane (PU), polyvinyl chloride (PVC), high flow AES, acrylonitrile-(ethylene - propylene - diene)-styrene (AEPDS), a mixture of thermoplastic plastics, or a PC - ABS blend thermoplastic. In some embodiments, the polymer film (11) including the circuit (12) will be formed of polycarbonate or polypropylene.

[0108]

[0116] Alternatively, the circuit can be embedded or molded into the preferably radio wave transmissive substrate (2) of the element, particularly the dome (1), such that the circuit (12) is preferably provided within the radio wave transmissive substrate (2) without the need for an additional layer.

Example

[0109] Substrate attenuation Substrate thickness

[0117] To assess the impact of the substrate on the attenuation of radio waves in the 76 - 77 GHz band, bare (uncoded) polycarbonate samples at approximately 2, 2.3, 3, 4.5, and 6 mm (actual thicknesses 2.0, 2.33, 2.92, 4.42, and 5.84 mm) were obtained and characterized as per the manufacturer's instructions at a tilt angle of 10 degrees within a Rohde - Schwartz (R&S®) QAR system. The data was analyzed and then the best - fit line was applied to the resulting data. The assumed relative permittivity of polycarbonate at 77 GHz is 2.8.

[0110]

[0118] Different dielectric substrates have different relative permittivities, which results in variations in the wavelength of radio waves across the substrate. Polycarbonate has a relative permittivity (εr) of 2.8 at 77 GHz, and thus the calculated wavelength through the substrate is 2.328 mm.

[0111]

[0119] As seen in Figure 8, the attenuation follows a tilted sine curve, and the attenuation is periodically minimum at substrate thicknesses that are integer multiples of half - wavelength (i.e., 0.5, 1, 1.5, 2, 2.5 times the wavelength of the radio wave through the substrate, etc.), and the maximum attenuation occurs at quarter - wavelengths offset from the minimum values (i.e., 0.75, 1.25, 1.75 times the wavelength of the radio wave through the substrate, etc.). Further, the average attenuation across the sine curve increased as the sheet thickness increased.

[0112]

[0120] From the perspective of other design requirements for radome use in vehicles, the optimal thickness was selected to be 2.3 mm, which provided minimum attenuation as well as appropriate robustness, rigidity, and weight for use as an automotive body part.

[0113] Attenuation of 77 GHz Radio Waves vs 79 GHz Radio Waves

[0121] To measure the attenuation at common radio - wave frequencies used in automotive radar systems, 2 - mm (Figure 9A) and 2.3 - mm (Figure 9B) polycarbonate substrates were characterized as per the manufacturer's instructions across the 76 - 81 GHz frequency range using an R&S® QAR system.

[0114]

[0122] As shown in FIG. 9A, the average attenuation over the 76 - 77 GHz frequency was approximately 117% of the average attenuation over the 76 - 81 GHz frequency when the polycarbonate substrate was 2 mm. By comparison, and as shown in FIG. 9B, the average attenuation over the 76 - 77 GHz frequency was approximately 83% of the average attenuation over the 76 - 81 GHz frequency when the polycarbonate substrate was 2.3 mm. As such, the percentage variation between the 2 mm substrate and the 2.3 mm substrate was 17%, even when the average attenuation over the 76 - 77 GHz frequency was compared to the average attenuation over the 76 - 81 GHz frequency in an opposing direction.

[0115]

[0123] However, the difference in actual attenuation was only 0.06 dB when the substrate was 2.3 mm, compared to 0.14 dB when the substrate was 2 mm. Thus, 2.3 mm appears to be the most suitable choice for use with radar systems that use both the 77 GHz and 79 GHz bands.

[0116] Glossy metallic appearance

[0124] Preferably, a decorative polymer sheet with radio - transparency was prepared with a glossy metallic appearance according to the following protocol.

[0117] Substrate preparation

[0125] The polycarbonate substrate was prepared by applying a base hard - coat layer of Momentive PHC587B using an automatic dip - coating process consisting of detergent washing, rough rinsing, fine rinsing, further fine rinsing, drying, cooling, and then dip - coating and flash - off. The dip - coating process was robot - controlled at a precise removal rate to control the thickness of the hard - coat. The substrate with the first surface hard - coated was left for 10 minutes to evaporate the solvent until the surface was substantially tack - free. Subsequently, the substrate with the first surface coated was cured in a curing oven at 130 °C for 71 minutes to provide the hard - coated substrate.

[0118] Decorative coating

[0126] A decorative coating comprising a layer of aluminum and germanium alloy or indium, and an upper layer of silicon dioxide (SiO2) was deposited according to the following parameters.

[0119]

Table 1

[0120] Protective surface coating - clear hard coat

[0127] To provide a gloss finish and to protect the decorative coating, a protective surface hard coat layer of Momentive PHC587B was applied as the upper (protective hard coat) layer over the decorative coating. This was accomplished by an automated spray coating process within a dedicated thin film coating spray booth. The substrate with the first surface coated was left for 10 minutes to allow the solvent to evaporate until the surface was substantially tack-free. Subsequently, the substrate with the first surface coated was cured in a curing oven at 130 °C for 71 minutes to provide a surface with a protective hard coating.

[0121] Bright satin metallic appearance

[0128] Preferably, a decorative polymer sheet with radio transparency was prepared with a satin metallic appearance according to the following protocol.

[0122] Substrate preparation and decorative coating

[0129] A polycarbonate substrate was provided with a first surface hard coat and a decorative coating comprising a layer of aluminum and germanium alloy or indium and a silicon dioxide layer as presented above for the "gloss metallic appearance".

[0123] Protective surface coating - satin hard coat

[0130] To provide a satin metallic appearance, a protective hard coat containing an additive that results in the diffusion of visible light was applied. Specifically, the following parameters were used.

[0124]

Table 2

[0125] Mechanical tests

[0131] To assess whether the decorated coated elements, especially the radome, are robust enough for automotive purposes, a series of durability tests were performed on samples with a glossy metallic appearance and a satin metallic appearance prepared as described above.

[0126]

[0132] The tests performed and the results are summarized in Table 3 below.

[0127]

Table 3

[0128] Attenuation of the coated substrate

[0133] Polycarbonate sheets of 2.0, 2.3, 2.92, 4.42, and 5.84 mm were coated with either a glossy metallic coating or a satin metallic coating as described above. To evaluate the effect of substrate thickness on the reflection and attenuation of radar singles in the 76 - 77 GHz band, the coated polycarbonate sheets were evaluated in a Rohde - Schwartz (R&S®) QAR system at an inclination angle of 10 degrees. The thickness of the applied decorative coating can be up to 0.03 mm thick and provides a total thickness of 2.03, 2.33, 2.95, 4.45, and 5.87 mm. The results are shown in Table 4 below.

[0129]

Table 4

[0130]

[0134] As can be seen from above, the unidirectional attenuation and reflection of the coated 2.33 mm polycarbonate did not change significantly based on the applied coating. Further, the best thickness was 2.33 mm with attenuations of 1.1 dB and 1.18 dB (gloss, satin), and reflections of 10% and 9% (gloss, satin). Indium is significantly better than aluminum germanium.

[0131]

[0135] The comparative attenuation of the coated and uncoated substrates is illustrated in FIG. 10 (data including the best fit sine curve was generated). As can be seen, the addition of the coating (gloss or satin) increases the attenuation. However, the attenuation at 2.33 mm is still at a level compliant with what is required for automotive radar systems.

[0132] Visual properties

[0136] The 2 millimeter and 2.3 mm polycarbonate substrates were coated to provide a gloss metallic or satin metallic look as described above, and the visual properties at the center of the coated substrates were measured with illuminant A / 2.

[0133]

[0137] The CIELAB color chart measured with illuminant A / 2 is shown in FIG. 11, and the measured values of reflection ("Rsin" including specular reflection and "Rsex" excluding specular reflection) are provided in Table 5 below.

[0134]

Table 5

[0135]

[0138] The reflectivity, including specular and diffuse reflected light (Rsin), was equivalent for both the glossy metallic-looking sample and the satin metallic-looking sample. However, the reflectivity in the 2.3 mm sample was typically higher than that in the 2 mm sample. This is likely an artifact of the coating process as a 2.3 mm sample consisting of a smaller stencil, and as such, the 2.3 mm sample was closer to the sputter target during deposition, compared to a 2 mm sample of A4 size.

[0136]

[0139] All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by the context. The use of any and all examples, or the exemplary language provided herein (e.g., "such as") is for the sole purpose of making the example embodiments more apparent and is not inherently limiting to the scope of the claimed invention. However, such embodiments may be subject to the claimed limitations or, if included within the scope of the claims, may be considered additional features. No language in this specification should be construed as indicating any non-claimed element as essential.

[0137]

[0140] The description provided herein relates to several embodiments that may share common characteristics and features. It should be understood that one or more features of one embodiment may be combinable with one or more features of other embodiments. Additionally, a single feature or combination of features of an embodiment may constitute additional embodiments.

[0138]

[0141] The heading terms used herein are included solely for the ease of reference of the reader and should not be used to limit the subject matter seen throughout the present disclosure or the claims as a whole. The heading terms should not be used to interpret the claims or claim limitations.

[0139]

[0142] Those skilled in the art will understand that the invention described in this specification is subject to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all steps, features, and / or functions individually or collectively mentioned or shown in this specification, as well as any and all combinations of any two or more of the steps or features.

[0140]

[0143] Throughout this specification, unless the context requires otherwise, the terms "comprise", "comprises", or "comprising" and variations thereof are to be understood to imply the inclusion of the stated element or integer or group of elements or integers but not the exclusion of any other element or integer or group of elements or integers.

[0141]

[0144] Also, it should be noted that, as used in this specification, the singular forms "a", "an", and "the" include plural aspects unless the context has already stated otherwise.

[0142] Future patent applications may be filed in Australia or overseas on the basis of, or claiming priority from, this application. It is to be understood that the following provisional patent claims are provided by way of example only and are not intended to limit the scope that may be claimed in any such future application. Also, features may be added to or omitted from the provisional patent claims at a later date so as to further define or redefine the invention.

Claims

1. A radio - transmissive substrate having a first surface on a first side and a second surface on a second side, and A decorative coating on the radio - transmissive first surface of the substrate, the decorative coating comprising a decorative layer made of a metal or an alloy containing a metal, comprising the decorative coating includes a plurality of layers, the plurality of layers of the decorative coating includes a stress - control layer, and the stress - control layer includes at least one dielectric layer, the combined stress of the plurality of layers forming the decorative coating is the overall residual stress of the decorative coating, and the overall residual stress of the decorative coating is neutral or tensile, a decorative vehicle element.

2. The decorative element according to claim 1, wherein the alloy containing the metal further contains a semimetal.

3. The decorative element according to claim 2, wherein the semimetal is germanium or silicon.

4. The decorative element according to claim 3, wherein the alloy containing the metal contains germanium, and the concentration of germanium is at least 25 wt% germanium.

5. The decorative element according to any one of claims 1 - 4, wherein the decorative layer is at most 100 nm thick.

6. The decorative element according to any one of claims 1 - 5, wherein the decorative layer is made of an alloy containing the metal selected from the group consisting of aluminum, tin, indium, silver, or chromium.

7. The decorative element according to claim 1, wherein the decorative layer is made of a metal selected from the group consisting of indium or tin.

8. The decorative element according to claim 1, wherein the plurality of layers of the decorative coating includes a bonding layer, and the bonding layer includes at least one metal, at least one alloy containing the metal, and / or at least one dielectric layer.

9. The decorative element according to claim 8, wherein the stress - control layer is between the substrate and the decorative layer, or the stress - control layer is on the first side of the decorative layer.

10. The decorative element according to any one of claims 1 - 9, wherein the plurality of layers of the decorative coating includes at least one decorative layer between at least two of the dielectric layers.

11. The decorative element according to any one of claims 1 - 10, wherein the decorative coating includes at least one protective hard - coat layer.

12. The decorative element according to claim 11, wherein the protective hard coat layer at least partially includes at least one light-scattering additive.

13. The decorative element according to any one of claims 1 to 12, wherein the decorative coating includes a base hard coat layer provided on the first surface of the substrate.

14. The decorative element according to any one of claims 1 to 13, wherein at least one of the dielectric layers is provided between the decorative layer made of a metal or an alloy containing the metal and the substrate.

15. The decorative element according to claim 13, wherein the base hard coat layer is provided between the decorative layer and the substrate.

16. The decorative element according to claim 11 or 12, wherein the dielectric layer is provided between the decorative layer and the protective hard coat layer.

17. The decorative element according to any one of claims 11, 12, or 16, wherein the protective hard coat layer includes one or more wear-resistant layers made of a material selected from the group consisting of organosilicon, acrylic, urethane, melamine, and amorphous SiOxCyHz.

18. The decorative element according to any one of claims 1, 10, 14, and 16, wherein the dielectric layer is represented by the formula SiO x or is silicon dioxide.

19. The decorative element according to any one of claims 1 to 18, wherein the decorative coating includes a plurality of dielectric layers and / or a plurality of decorative layers made of a metal or an alloy containing the metal.

20. The substrate is selected from the group consisting of acrylonitrile-ethylene-styrene (AES), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylate (ASA), polyamide (PA), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), poly(methyl methacrylate) (PMMA), polyoxymethylene (POM), polypropylene (PP), polyurethane (PU), polyvinyl chloride (PVC), high-flow AES, acrylonitrile-(ethylene-propylene-diene)-styrene (AEPD), a mixture of thermoplastic plastics, or a PC-ABS mixed thermoplastic. The decorative element according to any one of claims 1 to 19.

21. The decorative element is the decorative element according to any one of claims 1 to 20, including a heating element.

22. The heating element is the decorative element according to claim 21, including a resistance wire.

23. The resistance wire is the decorative element according to claim 22, formed within a polymer.

24. The resistance wire is the decorative element according to claim 23, formed within a polymer film that can be provided between the substrate and the decorative coating.

25. The heating element is within a polymer selected from the group consisting of acrylonitrile - ethylene - styrene (AES), acrylonitrile - butadiene - styrene (ABS), acrylonitrile - styrene - acrylate (ASA), polyamide (PA), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), poly(methyl methacrylate) (PMMA), polyoxymethylene (POM), polypropylene (PP), polyurethane (PU), polyvinyl chloride (PVC), high - flow AES, acrylonitrile-(ethylene - propylene - diene)-styrene (AEPD), a mixture of thermoplastic plastics, or a PC - ABS blended thermoplastic, the decorative element according to claim 23 or 24.

26. The heating element is provided within the substrate, the decorative element according to any one of claims 21 to 23.

27. The decorative element has a radio wave signal attenuation of less than 4 dB (bidirectional) and / or less than 1.5 dB (unidirectional) across the signal path, the decorative element according to any one of claims 1 to 26.

28. The decorative element has a radio wave signal attenuation of less than 2 dB (bidirectional) and / or less than 1 dB (unidirectional) across the signal path, the decorative element according to any one of claims 1 to 26.

29. The decorative layer has a sheet resistance greater than 106 ohms per square (Ω / □), the decorative element according to any one of claims 1 to 28.

30. The substrate is 2 mm to 2.6 mm thick, the decorative element according to any one of claims 1 to 29.

31. The substrate is 1.15 mm, 2.3 mm, or 2.45 mm thick, the decorative element according to any one of claims 1 to 29.

32. The decorative element is at least partially formed by at least one dome, at least one handle, at least one control panel, at least one door handle, at least one trim, at least one decorative strip, at least one decorative panel, at least one decorative cover, at least one mirror, and at least one door wave element, according to any one of claims 1 to 31.

33. A radar system comprising a radio transmitter, a radio receiver, and a decorative element according to any one of claims 1 to 32.

34. The thickness of the substrate of the decorative element is 【Number 1】 a multiple of, where λi is the wavelength of the radio wave transmitted from the radio transmitter passing through the substrate, according to the radar system of claim 33.

35. The radio transmitter transmits radio waves at a frequency of 1.575 GHz ± 200 MHz, according to the radar system of claim 33 or 34.

36. The radio transmitter transmits radio waves at a frequency of 2.0 GHz ± 200 MHz, according to the radar system of claim 33 or 34.

37. The radio transmitter transmits radio waves at a frequency of 20 to 81 GHz, according to the radar system of claim 33 or 34.

38. The radio transmitter transmits radio waves at a frequency of 76 to 81 GHz, according to the radar system of claim 33 or 34.

39. The radio transmitter transmits radio waves at a frequency of 76 to 77 GHz, according to the radar system of claim 33 or 34.

40. The radio transmitter transmits radio waves at a frequency of 77 GHz, according to the radar system of claim 33 or 34.

41. The radio transmitter transmits radio waves at a frequency of 79 GHz, according to the radar system of claim 33 or 34.

42. The radio transmitter transmits radio waves at a frequency of 81 GHz, according to the radar system of claim 33 or 34.

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