Signal-friendly metal surface

Abstract

The present disclosure relates to a coated article and a method for preparing the same. The coated article includes a metal layer, and the metal layer carries a frequency selective surface configured to reduce attenuation of an electrical communication frequency signal transmission.

Description

Technical Field

[0001] Priority Documents This application claims priority to Australian Provisional Patent Application No. 2022901475, entitled "COATED ARTICLES WITH A LOW-E COATING AND / OR A HARD COAT", filed on May 31, 2022, the entire content of which is incorporated herein by reference.

[0002] The present disclosure generally relates to coated articles and methods of preparing the same. In certain forms, the present disclosure relates to coated articles comprising a metal layer and having signal-friendly transmission at telecommunications frequencies and methods of preparing the same.

Background Art

[0003] Low-emissivity (low-E) coatings comprise a stack of high thin films that reflect solar infrared radiation and allow a portion of visible light to pass through. Low-E coatings find use in architectural glass, automotive windows, and solar collectors due to their excellent energy-saving performance. By way of example, the ability of a low-e article (such as a window) to reflect solar infrared radiation significantly reduces the temperature inside a building in summer and maintains the heat inside the building in winter, thus minimizing the use of air conditioning and heating systems, respectively. Furthermore, their high transmittance in the visible range significantly contributes to reducing the need for artificial lighting during the day.

[0004]

[0005] ​In the case of architectural windows, the most commonly used coatings are low-E coatings. These reflect heat due to their metal content and are highly transparent, but are made in a rather complex structure that typically includes more than 20 layers and 10 different materials, resulting in an expensive manufacturing process. Furthermore, commercially available low-E coatings have durability problems due to corrosion in the IR reflective layer, which is usually made of silver (Ag), and are therefore often placed in the cavity between double-pane windows to protect against weathering.

[0006] Conventionally, in the automotive industry, glass plates with an adhesive window tint consisting of one or more PET sheets containing carbon, ceramic nanoparticles, or dark dyes have been used to darken the windows and block IR radiation from the sun. However, these tints absorb rather than reflect IR radiation. This means that the absorbed radiation is re-radiated into the vehicle by conduction and convection and thus does not protect the vehicle from heat. Furthermore, they exhibit a low visible transmittance for efficient heat blocking and are therefore not suitable for public transportation vehicles or the front glass of vehicles.

[0007] Another drawback of existing low-E coatings is that the thin metal layer attenuates microwave and high-frequency signals, especially in the high-frequency range such as 5G wireless signals (600 MHz to 100 GHz). For example, if a vehicle is equipped with a metal-based low-E window, it acts as a Faraday cage, reflecting or dramatically attenuating useful telecommunication signals. With the evolution of wireless devices, it is also important to have strong and stable signal strength inside buildings. The attenuation of signals through objects is also measured by the shielding effect (SE). The shielding effect is defined as the logarithm of the ratio of the magnitude of the incident electric field to the magnitude of the transmitted electric field and is expressed in decibels (dB). 0 dB means no attenuation. For example, in public transportation, the current strategy for amplifying signals is the installation of repeater devices. However, this type of device only amplifies the selected frequency and needs to be replaced when the communication standard is changed. These are expensive and energy-consuming. Another option is the use of ultra-wideband antennas, but their performance depends on the mounting position on the vehicle body, and their efficiency can be drastically reduced depending on the distance between the metal window and the antenna. Antennas can also be integrated into heated windows. However, these only cover the FM / TV range (50 to 800 MHz). The latest integrated window antennas can cover 4G LTE signals and low-frequency 5G signals, but these also need to be replaced when the communication standard is changed.

[0008] Articles having a low-E coating (e.g., windows and doors) tend to be exposed to harsh and extreme conditions in actual use, and thus weather resistance, robustness, and durability are important.

[0009] There is still a need for coated articles and methods of preparing the same that can mitigate or reduce one or more of the above problems. In other words, it would be desirable for the coated article to have a simplified low-cost structure while maintaining a visible light transmittance and IR radiation reflectance equivalent to existing commercial products. Additionally or alternatively, it would be desirable for the coated article to have a lower attenuation of signal transmission at electrical communication frequencies. Additionally or alternatively, it would be desirable for the coated article to have improved durability, abrasion resistance, and weather resistance. SUMMARY OF THE INVENTION

[0010] According to a first aspect, there is provided a coated article comprising a metal layer, wherein the metal layer carries a frequency selective surface configured to reduce attenuation of electrical communication frequency signal transmission.

[0011] In some embodiments, the metal layer is a metal IR reflective layer within a low-E coating included in the coated article.

[0012] In some embodiments, the frequency selective surface includes a periodic pattern selected from the group consisting of a periodic hexagonal lattice, a periodic square lattice, a periodic triangular lattice, a periodic circular lattice, a periodic kagome lattice and / or an aperiodic pattern such as a Penrose tiling.

[0013] In some embodiments, the periodic pattern of the frequency selective surface has a unit cell dimension of less than about 2 mm, such as less than about 1 mm, and an aperture line width of about 5 μm to about 60 μm, such as about 30 μm to about 60 μm. In some further embodiments, the periodic pattern of the frequency selective surface has a unit cell dimension of about 0.5 mm and an aperture line width of about 50 μm. In still further embodiments, the frequency selective surface includes a periodic hexagonal lattice having a unit cell dimension of about 0.5 mm and an aperture line width of about 50 μm.

[0014] In some embodiments, the telecommunications frequency is for fifth generation (5G) communication. In some further embodiments, the attenuation of the telecommunications frequency signal transmission is reduced from about 30 dB to about 1 dB as compared to a coated article in which the metal layer does not carry a frequency selective surface.

[0015] In some embodiments, the metal layer comprises silver (Ag), gold (Au), copper (Cu), aluminum (Al), zinc (Zn), niobium (Nb), titanium nitride (TiN), Ag / Au alloy, Ag / Cu alloy, Ag / Al alloy, NbN x , NbCr, NbCrN x and / or NbZrO x and the like. Silver (Ag), gold (Au) or copper (Cu) may be particularly suitable for the metal IR reflective layer. In some further embodiments, the low-E coating comprises one metal layer. In still further embodiments, the metal layer has a thickness of about 5 nm to about 25 nm, preferably about 10 nm to about 20 nm.

[0016] In some embodiments, the coated article comprises a low-E coating supported by a substrate, and the low-E coating comprises, in order from the substrate outward, a dielectric layer, a protective layer, a metal IR reflective layer as a metal layer, a protective layer, and a dielectric layer.

[0017] In some embodiments, the substrate of the coated article is substantially made of a plastic or glass that can be flexible or rigid. In some specific embodiments, the plastic used for the substrate is selected from the group consisting of polycarbonate, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, polyamide, polyester, polyester carbonate, polyethersulfone, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene terephthalate glycol (PETG), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polymethyl methacrylate (PMMA), and polyetherimide. In some further embodiments, the glass used for the substrate is selected from the group consisting of borosilicate glass, flat glass, quartz glass, and soda lime (float) glass. In a specific embodiment, the coated article has no interplate space, and the low-E coating is applied to at least a part of the surface of the substrate exposed to the use environment. In some further embodiments, the substrate for the coated article has a thickness of about 0.4 cm to about 0.5 cm.

[0018] According to a second aspect, there is provided a method for reducing the attenuation of electrical communication frequency signal transmission of a coated article including a metal layer, the method including creating a frequency selective surface on the metal layer.

[0019] In some embodiments, the metal layer is a metal IR reflective layer within a low-E coating included in the coated article.

[0020] In some embodiments, the frequency selective surface includes a periodic pattern selected from the group consisting of a periodic hexagonal lattice, a periodic square lattice, a periodic triangular lattice, a periodic circular lattice, a periodic kagome lattice, and / or an aperiodic pattern such as a Penrose tiling.

[0021] In some embodiments, the periodic pattern of the frequency selective surface has a unit cell dimension of less than about 2 mm, such as less than about 1 mm, and an aperture line width of about 5 μm to about 60 μm, such as about 30 μm to about 60 μm. In some further embodiments, the periodic pattern of the frequency selective surface has a unit cell dimension of about 0.5 mm and an aperture line width of about 50 μm. In some further embodiments, the periodic pattern is a periodic hexagonal lattice and has a unit cell dimension of about 0.5 mm and an aperture line width of about 50 μm.

[0022] In some embodiments, the telecommunications frequency is for fifth generation (5G) communication. In some further embodiments, the attenuation of the telecommunications frequency signal transmission is reduced from about 30 dB to about 1 dB as compared to a coated article in which the metal IR reflective layer does not carry the frequency selective surface.

[0023] In some embodiments, an area of less than about 25% of the metal layer is removed to create the frequency selective surface on the metal layer. In some further embodiments, an area of less than about 20% of the metal layer is removed to create the frequency selective surface on the metal layer. In some further embodiments, an area of less than about 10% of the metal layer is removed to create the frequency selective surface on the metal layer. In still further embodiments, an area of about 5% to about 10% of the metal layer is removed to create the frequency selective surface on the metal layer.

[0024] In some embodiments, a frequency selective surface is created on a metal layer by laser etching or photolithography. In some further embodiments, one or more stacks are laser etched to create a frequency selective surface on a metal layer, and the one or more stacks are selected from a stack of substrate / metal layer, a stack of substrate / protective layer / metal layer, a stack of substrate / dielectric layer / protective layer / metal layer, a stack of substrate / dielectric layer / protective layer / metal layer / protective layer, a stack of substrate / metal layer / substrate, a stack of substrate / protective layer / metal layer / substrate, a stack of substrate / dielectric layer / protective layer / metal layer / substrate, and a stack of substrate / dielectric layer / protective layer / metal layer / protective layer / substrate. In still further embodiments, in the case of laser etching, a laser beam enters from either side of the stack to form a frequency selective surface on the metal layer. In still further embodiments, laser etching is performed on a multi-plate window including a metal layer (e.g., one or more metal layers) to form a frequency selective surface on the metal layer.

[0025] According to a third aspect, there is provided the use of a coated article prepared according to the first aspect or in accordance with the second aspect in an automobile or a building.

[0026] Embodiments of the present invention will be described with reference to the accompanying drawings.

Brief Description of the Drawings

[0027]

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DETAILED DESCRIPTION OF THE INVENTION

[0028] Aspects of the present disclosure arise from the inventors' research on multifunctional coating articles that can have a simple structure, be durable, visually transparent, reflect thermal energy, be efficient for 5G communication, and be abrasion and weather resistant. The coating articles can be widely applied to automotive vehicles and buildings, such as glass windows for energy conservation and efficient signal transmission.

[0029] As used herein, the term "low emissivity (low-E)" refers to a surface condition that emits low levels of radiant heat energy and can have an emissivity value of about 0.04 < ε < about 0.4. This ε means that the coating article can reflect at least about 60% to a maximum of about 96% of the ultraviolet and infrared light incident thereon.

[0030] As used herein, the term "IR reflection" means the ability to reflect infrared (IR) radiation, particularly near-IR and mid-IR radiation.

[0031] As used herein, the term "telecommunication frequency" includes signals from about 600 MHz to about 100 GHz, particularly signals for 5G communication that enable a larger bandwidth, higher data rate, lower latency, and increased capacity on the network, but is not limited thereto.

[0032] The term "frequency selective surface (FSS)" refers to a periodic resonant pattern designed on a coating that selectively enables or prevents the transmission of electromagnetic waves. For this purpose, frequency selective surfaces are particularly used to reduce the attenuation of telecommunication frequency signal transmission.

[0033] As used herein, the term "unit cell" with respect to a frequency selective surface refers to the basic shape that forms a periodic pattern.

[0034] As used herein, the terms "oxide", "nitride", and "oxynitride" include various stoichiometries and, unless otherwise specified, include all possible stoichiometries.

[0035] In the chemical formula of the compounds disclosed herein, the symbols "x" or "y" represent the number of atoms of the corresponding element.

[0036] Disclosed herein are coated articles comprising a low-E coating supported by a substrate, the low-E coating comprising a metallic IR reflecting layer, a protective layer in contact with the metallic IR reflecting layer, and a dielectric layer. The composition of the disclosed coated articles can be selected to be transparent, which may be desirable in the automotive, transportation or construction industries.

[0037] For this purpose, a coated article comprising a low-E coating can have an emissivity ε of about 0.04 < ε < about 0.4. Further, the coated article may have a visible transmittance of greater than about 60%, preferably greater than about 70%, more preferably greater than about 80%, and / or an IR reflectance of greater than about 60%, preferably greater than about 70%. The low-E coating can have a total thickness of about 90 nm to about 120 nm, for example 110 nm. Transmittance (%T) and reflectance (%R) are measured with a Cary 5000 spectrophotometer (Agilent Technologies) between 380 nm and 3300 nm. Visible solar weighted transmittance (%T VIS ) and IR solar weighted reflectance (%R IR ) are calculated according to Equations 1 and 2, respectively.

Equation

Equation

[0038] The low-E coatings disclosed herein can be applied directly or indirectly onto a variety of substrates that can be substantially made from plastic or glass. When the coated article is used as a window in a building or a vehicle, the substrate is preferably transparent and can have desirable optical quality and impact resistance. The substrate may be colored (e.g., green, gray, or blue). The plastic substrate used may be rigid or flexible. For example, the low-E coatings disclosed herein may be applied onto a flexible plastic substrate for window tinting. Examples of suitable plastic substrates include, but are not limited to, polycarbonate, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, polyamide, polyester, polyester carbonate, polyethersulfone, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene terephthalate glycol (PETG), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polymethyl methacrylate (PMMA), and polyetherimide. Examples of glass substrates include, but are not limited to, borosilicate glass, flat glass, quartz glass, and soda lime (float) glass. Rigid glass substrates are well-known, but it is also possible for the glass substrate to be flexible, for example, Corning® Willow® Glass manufactured by Corning Inc., Corning, USA. Polycarbonate is a very robust plastic, naturally transparent, and can be a preferred option for replacing glass. A suitable example is Makrolon® AR polycarbonate commercially available from the Covestro Group. The substrates used can be of various thicknesses and can be about 0.4 cm to 0.5 cm thick.

[0039] It will be understood that the low-E coating may be applied to one or both sides of the substrate. In certain embodiments, in the case of a double-glazed window, the low-E coating is applied to the inner side of each glass pane. Coated articles comprising the low-E coatings and hard coats disclosed herein advantageously have high abrasion resistance and corrosion resistance, which enables the application of the low-E coating to at least a portion of the surface of the substrate exposed to the use environment and eliminates the need to dispose it between window glass panes. In other words, the coated article need not have a space between the window glass panes. The low-E coating reduces the amount of solar heat passing through the coated article (e.g., window) and maintains the interior cooler without impairing the amount of visible light transmitted. When the internal thermal energy attempts to escape to the colder exterior in winter, the low-E coating reflects the heat back inside, thereby reducing the radiative heat loss through the coated article. One or more layers within the low-E coating can be applied onto the substrate using methods known in the art. An example of such method is physical vapor deposition (PVD), which includes, but is not limited to, magnetron sputtering, electron beam evaporation, and thermal evaporation.

[0040] The low-E coating includes one or more metallic IR reflecting layers. Generally, the metallic IR reflecting layers include silver (Ag), aluminum (Al), copper (Cu), zinc (Zn), niobium (Nb), titanium nitride (TiN), Ag / Au alloy, Ag / Cu alloy, Ag / Al alloy, NbN x , NbCr, NbCrN x , NbZrO xIt may contain and / or consist of any reflective metal such as gold (Au). Preferably, silver (Ag) is used for one or more metal IR reflective layers because it is relatively achromatic. The thickness of the metal IR reflective layer can be selected to achieve the desired reflection of IR radiation and visible transmittance. On the other hand, the reflective layer is expected to be thin enough to allow visible light to pass through to provide good transmittance. On the other hand, the emissivity of a metal IR reflective layer (such as an Ag layer) tends to decrease with a decrease in sheet resistance. Therefore, in order to obtain a low emissivity, the sheet resistance of one or more IR reflective layers (such as Ag layers) must be as low as possible, which means as thick as possible. A thicker IR reflective layer may be beneficial for thermal performance, but it may result in higher cost and longer time for fabricating the metal IR reflective layer. In use, the thickness of the IR reflective layer can be from about 5 nm to about 25 nm, more preferably from about 10 nm to about 20 nm. If desired, two or three metal IR reflective layers can be used. These are called double or triple reflective low-E coatings. The more reflective layers (e.g., Ag layers) there are, the higher the visible transmittance and IR reflectivity will be.

[0041] The metal IR reflective layer can be applied using methods known in the art including but not limited to magnetron sputtering deposition and thermal decomposition processes. In certain embodiments, the IR reflective layer may be sputtered (e.g., at about 3000 W) from a cathode of the required metal onto a protective layer or a dielectric layer on a substrate in an inert atmosphere. An IR reflective layer fabricated by magnetron sputtering deposition generally functions better with respect to solar control and reduction of heat transfer through windows than an IR reflective layer fabricated by a thermal decomposition process.

[0042] Apply various protective layers on each metal IR reflective layer to provide immediate protection against plasma attack when sputtering one or more dielectric layers thereon, or against O2, O, H2O, and Na +Each metal IR reflective layer can be provided with immediate protection from the spread of aggressive species such as. Also, the protective layer desirably has good adhesion to the metal IR reflective layer and allows for good transmission of visible light. Metals, alloys, silicides, nitrides, or any other suitable material to achieve the desired effect can be used. For example, the protective layer includes, but is not limited to, nickel-chromium alloy (NiCr), NiCrO x 、NiCrN x 、NiCrO x N y 、Ni x Ti y O z 、Ni, Cr, CrN x 、NiO x 、Ti, TiO x 、NbO x 、ZnO, Al2O3, ZnAlO x or may include or consist of any combination thereof. Nickel-chromium alloy (NiCr) includes, but is not limited to, NiCr (80 / 20 wt%), NiCr (70 / 30 wt%), NiCr (60 / 40 wt%), and NiCr (50 / 50 wt%). In some situations, the protective layer can also function as an adhesive layer and / or a nucleation layer. For all embodiments herein, each protective layer can be in a thickness range of about 1 nm to about 5 nm, preferably about 1 nm to about 3 nm or about 2 nm to about 3 nm. Thicker protective layers can contribute to durability. If the protective layer is too thin, it is likely to be discontinuous and unable to cover the metal IR reflective layer, thus having no effect of providing sufficient protection. In some embodiments, it is preferred to have protective layers on both sides of the IR reflective layer. However, it is possible to have a protective layer on only one side of the IR reflective layer. In a preferred embodiment, the protective layer includes NiCr. More preferably, protective layers made of NiCr are provided on both sides of the IR reflective layer.

[0043] Known methods, such as sputtering deposition and thermal evaporation, can be used to apply a protective layer onto a substrate. When a protective layer of NiCr is used, the protective layer is preferably sputtered (e.g., at about 700 W) onto a metallic IR reflective layer and deposited, for example, from a DC (direct current) target. When a protective layer of ZnO is used, the protective layer can be fabricated by arc plasma deposition using an evaporated zinc source with a plasma containing stoichiometrically excess oxygen.

[0044] The dielectric layer of the low-E coating serves an anti-reflection function and increases the transmittance of the entire coated article. It also provides protection to one or more layers beneath it. If necessary, the low-E coating may include one or more dielectric layers. In some embodiments, two or more consecutive dielectric layers are used.

[0045] The one or more dielectric materials used for the dielectric layer are not particularly limited. Most commonly used dielectric materials, such as oxides, nitrides, oxynitrides, or combinations thereof, can be considered for the purposes of the present disclosure. It is also possible to dope the dielectric material with a suitable material such as Al or stainless steel. Factors including the refractive index n, the transparent region, the availability of deposition methods, and cost-effectiveness can be considered when selecting a suitable dielectric material. Other considerations such as compatibility with other materials and thermal stability can also be determining factors. Materials suitable for the dielectric layer include TiO2, Ta2O5, Nb2O5, ZrO2, ZnO, ZnS, ZnSe, HfO2, LaTiO3, Al2O3, La2O3, Y2O3, Gd2O3, Sc2O3, Si3N4 and SiAlO x N y including SiO2, Al-doped SiO2, LiF, MgF2, Na3AlF6, SnO2, indium tin oxide (ITO), Al-doped zinc oxide (AZO), WO3, SiO x N yIt may include one or more selected from. For the purpose of high transmittance and refractive index, the protective layer preferably contains or consists of TiO2, Nb2O5 and / or Ta2O5. If desired, a dielectric layer of SiO2 or Al-doped SiO2 can also function as an adhesive layer.

[0046] Generally, the thickness of each dielectric layer is adjusted to reduce internal and external reflectance so that the light transmittance is high, for example, exceeding 60%. The thickness of each dielectric layer may vary from about 25 nm to about 45 nm. However, it is recommended that the thickness of each dielectric layer on the IR reflective layer be within the range of about 30 nm to about 40 nm.

[0047] The dielectric layer used herein can be deposited by methods known in the art such as high-frequency magnetron sputtering, DC magnetron sputtering, reactive pulse magnetron sputtering, thermal evaporation, electron beam evaporation, ion beam sputtering, and atomic layer deposition. The choice of deposition method can depend on the material to be deposited and the expected optical properties. In some embodiments, when a dielectric layer containing TiO2 and / or a dielectric layer containing SiO2 is deposited, magnetron sputtering is employed (for example, about 3000 W or 3800 W for TiO2, about 2000 W for SiO2), and the layer is prepared by sputtering a Ti or Si target in oxygen.

[0048] In some embodiments, a metal IR reflective layer is sandwiched between two adjacent protective layers, each of the protective layers contains or consists of NiCr and has a thickness of less than about 5 nm, and the metal IR reflective layer contains or consists of Ag and has a thickness of about 20 nm.

[0049] In some embodiments, the coated article disclosed herein includes a low-E coating supported by a substrate, the low-E coating including, in order from the substrate outward, a dielectric layer comprising or consisting of TiO2, a protective layer comprising or consisting of NiCr, a metallic IR reflecting layer comprising or consisting of Ag, a protective layer comprising or consisting of NiCr, and a dielectric layer comprising or consisting of TiO2. Optionally, a dielectric layer / adhesion layer comprising or consisting of SiO2 or Al-doped SiO2 is added on the outermost TiO2-containing or TiO2-comprising dielectric layer further from the substrate.

[0050] More specifically, the coated article may include a low-E coating supported by a substrate, the low-E coating including, in order from the substrate outward, a dielectric layer of TiO2 that is about 25 nm to about 45 nm, a protective layer of NiCr that is less than about 5 nm, a metallic IR reflecting layer of Ag that is about 10 nm to about 20 nm, a protective layer of NiCr that is less than about 5 nm, and a dielectric layer of TiO2 that is about 25 nm to about 45 nm. In yet further embodiments, the coated article includes a low-E coating supported by a substrate, the low-E coating including, in order from the substrate outward, a dielectric layer of TiO2 that is about 40 nm, a protective layer of NiCr(80 / 20) that is less than about 5 nm, a metallic IR reflecting layer of Ag that is about 20 nm, a protective layer of NiCr(80 / 20) that is less than about 5 nm, and a dielectric layer of TiO2 that is about 40 nm. In yet further embodiments, the coated article includes a low-E coating directly supported by a substrate, the low-E coating including, in order from the substrate outward, a dielectric layer of TiO2 that is about 40 nm, a protective layer of NiCr(80 / 20) that is less than about 5 nm, a metallic IR reflecting layer of Ag that is about 20 nm, a protective layer of NiCr(80 / 20) that is less than about 5 nm, a dielectric layer of TiO2 that is about 40 nm, and a dielectric layer / adhesion layer of SiO2 or Al-doped SiO2 that is about 10 nm, comprising or consisting of these.

[0051] The frequency selective surface on the metal IR reflective layer is used to enhance the transmission of electrical communication frequencies through the coated article. The frequency selective surface can have a periodic pattern such as a periodic triangular lattice, a periodic square lattice, a periodic hexagonal lattice, a periodic circular lattice, or a periodic kagome lattice (see FIG. 3). Additionally or alternatively, the frequency selective surface may have an aperiodic pattern such as a Penrose tiling. The frequency selective characteristics can be adjusted by changing the geometric shape and geometric parameters (such as unit cell dimensions and aperture line widths) of the periodic pattern to achieve the desired signal transmission at a specific operating frequency. The frequency selective surface used for this purpose can advantageously reduce the attenuation of signal transmission at electrical communication frequencies from about 30 dB to about 1 dB when compared to a coated article where the metal IR reflective layer does not carry the frequency selective surface.

[0052] As used herein, the unit cell dimension refers to the dimension of the unit cell that reflects periodicity, and the aperture line width means the width of the ablated path. Taking the periodic hexagonal lattice as an example, the unit cell dimension is represented by the length of the diagonal (e.g., see FIG. 2). In the case of a periodic square lattice, the unit cell dimension is represented by the diagonal of the square. In the case of a periodic ring lattice, the unit cell dimension is represented by the diameter. Preferably, the aperture line width is small enough so that the optical contrast is not visible to the naked eye.

[0053] Frequency selective surfaces can be fabricated by laser etching. For this purpose, one or more stacks can be laser etched to create a frequency selective surface on a metal layer, and the stack can be selected from a stack of substrate / metal layer, a stack of substrate / protective layer / metal layer, a stack of substrate / dielectric layer / protective layer / metal layer, a stack of substrate / dielectric layer / protective layer / metal layer / protective layer, a stack of substrate / metal layer / substrate, a stack of substrate / protective layer / metal layer / substrate, a stack of substrate / dielectric layer / protective layer / metal layer / substrate, and a stack of substrate / dielectric layer / protective layer / metal layer / protective layer / substrate. In the case of laser etching, a laser beam can enter from any suitable side of the coated article to create a frequency selective surface on the metal layer. As shown in FIG. 9, the laser beam can enter from the substrate side of the coated article or from the side opposite to the substrate of the coated article. This enables laser etching of a fully assembled multilayer window including a metal layer, thereby creating a frequency selective surface on the metal layer. If necessary, a laser scribed grid can be utilized in the fabrication. By way of example, a stack of substrate / dielectric layer / protective layer / metal IR reflective layer / protective layer is etched by a pulsed Nd:YAG laser, and then one or more layers such as another dielectric layer and an outermost hard coat are grown on the protective layer. In some embodiments, a stack of substrate / dielectric layer / protective layer / metal IR reflective layer is laser etched to create a frequency selective surface. The laser parameters can be optimized to etch only the metal IR layer without reaching the substrate. Alternatively, photolithography may be considered to create a frequency selective surface. For example, a UV photolithography process can be performed to transfer a pattern from a mask on a photoresist (photosensitive material), followed by a wet etching process to create a frequency selective surface. By ablating only a small percentage (e.g., 5% to 10% of the layer surface area) of the area of the IR reflective layer, the heat reflective properties and high transmittance of the coated article are maintained while allowing the passage of electrical communication frequencies.

[0054] In some embodiments, the periodic pattern of the frequency selective surface has a unit cell dimension of less than about 2 mm, such as less than 1 mm, and an aperture line width of about 5 μm to about 60 μm, such as about 30 μm to about 60 μm, such as 50 μm. The periodic pattern of the frequency selective surface may desirably have a unit cell dimension of about 0.5 mm and an aperture line width of about 50 μm. In a preferred embodiment, the periodic pattern of the frequency selective surface is a periodic hexagonal lattice. More preferably, the diagonal of the hexagon is about 0.5 mm and the aperture line width is about 50 μm.

[0055] The inventors have found that a hard coat can be provided as the outermost layer to protect the underlying layer in order to improve the durability of the coated article (particularly with respect to abrasion resistance and weather resistance). This enables the coated article to be applied to automotive, medical and architectural uses. For this purpose, various abrasion-resistant hard coats based on polysiloxane may be considered, which can typically be applied with a thickness of about 5 μm to about 6 μm. In some embodiments, the abrasion-resistant hard coat based on polysiloxane can be prepared from a thermosetting liquid polysiloxane nanocomposite hard coat resin containing silica nanoparticles such as CRYSTALCOAT™ MP-101 commercially available from SDC TECHNOLOGIES ASIA PACIFIC, PTE. LTD. If necessary, an adhesion layer may be applied on the low-E coating before applying the hard coat, and the adhesion layer can be made of materials known in the art, such as SiO2 or Al-doped SiO2. When an adhesion layer of SiO2 or Al-doped SiO2 is employed, the thickness of the adhesion layer can be about 10 nm to about 100 nm, preferably about 10 nm. The polysiloxane-based hard coat can be applied using a dip coating method or a flow coating method. In the case of dip coating, the substrate is coated before being thermally cured.

[0056] In the absence of a hard coat, a coated article including a low-E coating can be placed in the cavity of a multi-pane window so as to be isolated from the atmosphere.

[0057] One or more other layers may also be present in the coated articles disclosed herein. In some situations, instead of a hard coat, the coated article may include, as the outermost layer, an overcoat made of, for example, SiO2 to achieve improved durability.

[0058] A method for reducing the attenuation of electrical communication frequency signal transmission of a coated article is also disclosed herein. It will be understood that the coated article includes a metal layer and the method includes creating a frequency selective surface on the metal layer. The metal layer can be a metal IR reflective layer within a low-E coating included in the coated article. The coated article and the frequency selective surface can be designed and fabricated with reference to the above discussion.

[0059] In some situations, the coated articles according to the present disclosure can effectively reflect infrared light or heat, pass 5G signals while being highly transparent, which makes the coated articles useful for windows such as in public transportation and buildings. Also, the coated articles according to the present disclosure can have a simplified design compared to existing commercially available products (in particular, having a relatively small number of coating layers, about 5 to 7 layers in some situations). The coated articles according to the present disclosure enable the application of a low-E coating to at least a part of the surface of a substrate exposed to the use environment (i.e., facing the atmosphere), and can eliminate the need to dispose the low-E coating between glass plates.

Examples

[0060] Fabrication of a Coated Polycarbonate Substrate with a Low-E Coating

[0061] The coated polycarbonate as shown in FIG. 1 is prepared by the following method.

[0062] The Makrolon AR polycarbonate (PC) substrate was washed with a detergent and a non-abrasive sponge, dried with compressed air, and plasma cleaned in an Ar atmosphere for 2 minutes.

[0063] The depositions of TiO2, NiCr, Ag, and Al-doped SiO2 were carried out by a custom in-line magnetron sputtering system. This system uses high-purity tubular sputtering targets (80 cm in height and 7.5 cm in diameter) that rotate during deposition: Ti (99.99 wt% purity), NiCr (80 wt% Ni, 20 wt% Cr), Si (5 wt% Al-doped), and Ag (99.99 wt% purity). The pressure before deposition was 1.5×10 -6 mbar, and each target was pre-sputtered for 4 minutes.

[0064] First, 40 nm of TiO2 was deposited in poison mode using 400 sccm of Ar and 35 sccm of O2 to give a working pressure of 0.00595 mbar. The sputtering power was held at 3800 W, and the carrier speed was 1.04 mm / s.

[0065] Next, less than 5 nm of NiCr was deposited at 700 W with a working pressure of 0.00369 mbar (400 sccm of Ar) and a carrier speed of 39.4 mm / s.

[0066] On top of the NiCr, Ag (20 nm) was sputtered at 3000 W with the same working pressure of 0.00369 mbar and a carrier speed of 21.4 mm / s.

[0067] Again, NiCr (less than 5 nm), then TiO2 (40 nm), were grown on the patterned Ag using the previously defined conditions. 10 nm of Al-doped SiO2 was deposited in a similar poison mode using 400 sccm of Ar and 45 sccm of O2 to give a working pressure of 5.1×10 -3 mbar at 2000 W. The carrier speed was 16.4 mm / s.

[0068] Finally, the stack was dip-coated with a transparent hard coat resin CrystalCoat MP101 (SDC Technologies, solids content 32.5%) consisting of a siloxane matrix embedded with silica nanoparticles using a Qualtech QPI-168 dip coater. A dipping speed of 500 mm / min was used to obtain a hard coat thickness of 5 μm. After dipping, the sample was dried for 30 minutes and then cured in an oven at 130 °C for 1 hour. This process was carried out at a humidity of 25 - 45%.

[0069] Figure 8 shows that the obtained low-E coating has a visible transmittance of about 61% and an IR reflectance of about 64%. Compared with some commercially available low-E coatings, the low-E coating prepared herein not only has a simple low-cost structure but also exhibits equivalent visible light transmittance and equivalent IR radiation reflectance. The visible transmittance and IR reflectance were analyzed using a UV-VIS-NIR spectrophotometer (Cary 5000) manufactured by Agilent Technologies Inc.

[0070] Durability - Abrasion and corrosion of the coated articles prepared above

[0071] For the low-E samples, abrasion tests such as the Bayer test and the Steel Wool test were carried out. The Steel Wool test was performed using a Sutherland® 2000® Rub Tester manufactured by Danilee Co. In the Bayer test, a TABER® Oscillating Abrasion Tester (Model 6100) was used to evaluate the abrasion resistance against fine gravel. In these tests, the higher the abrasion rate, the higher the resistance of the sample. Both tests confirmed the suitability of the coated article as the first window surface due to its high abrasion resistance (Figure 4). Almost no visual changes were observed after the test.

Table 1

[0072] The low-E stack was placed in the corrosion chamber for 1000 hours. After 1000 hours (the time required for a commercially available automotive side mirror), the low-E coating showed almost no change in appearance and provided the same transmittance value. Figure 5a) shows the results of the unprotected stack (without hard coat) after 24 hours and the protected stack after 1000 hours in the corrosion chamber.

[0073] Fabrication of a Coated Polycarbonate Substrate Containing a Low-E Coating with a Frequency Selective Surface on a Metallic IR Reflective Layer by Laser Etching

[0074] The Makrolon AR polycarbonate (PC) substrate was cleaned with a detergent and a non-abrasive sponge, dried with compressed air, and plasma cleaned in an Ar atmosphere for 2 minutes.

[0075] The deposition of TiO2, NiCr, Ag, and Al-doped SiO2 was carried out by a custom in-line magnetron sputtering system. This system uses high-purity tubular sputtering targets (height 80 cm and diameter 7.5 cm) that rotate during deposition: Ti (purity 99.99 wt%), NiCr (80 wt% Ni, 20 wt% Cr), Si (5 wt% Al-doped), and Ag (purity 99.99 wt%). The pressure before deposition was 1.5×10 -6 mbar, and each target was pre-sputtered for 4 minutes.

[0076] First, 40 nm of TiO2 was deposited in poison mode using 400 sccm of Ar and 35 sccm of O2 to give a working pressure of 0.00595 mbar. The sputtering power was held at 3800 W, and the carrier speed was 1.04 mm / sec.

[0077] Next, less than 5 nm of NiCr was deposited at 700 W with a working pressure of 0.00369 mbar (400 sccm of Ar) and a carrier speed of 39.4 mm / sec.

[0078] Ag (20 nm) was sputtered onto NiCr at 3000 W with the same working pressure of 0.00369 mbar and a carrier speed of 21.4 mm / s.

[0079] The frequency selective surface (FSS) is first designed by AutoCAD. The pattern design is saved as a drawing exchange format (DXF) file and then transferred to a laser ablation device. The periodic FSS hexagonal pattern (unit cell 0.5 mm) is ablated and evaporated from the Ag thin film by a Nd:YAG (1064 nm) pulsed laser G8 manufactured by Sei Laser. The pattern is etched at a frequency of 10 kHz at a speed of 100 mm / s and a power of 18 W. These parameters produce an ablation line width of 50 μm. An extraction system is attached to the machine to remove the fumes from the evaporation process.

[0080] Again, NiCr (less than 5 nm) and then TiO2 (40 nm) were grown on the patterned Ag using the previously defined conditions.

[0081] 10 nm of Al-doped SiO2 was deposited in a similar poisoning mode at 2000 W using 400 sccm of Ar and 45 sccm of O2 giving a working pressure of 5.1x10 -3 mbar. The carrier speed was 16.4 mm / s.

[0082] Finally, the stack was dip-coated with a transparent hard coat resin CrystalCoat MP101 (SDC Technologies, solids content 32.5%) consisting of a siloxane matrix embedded with silica nanoparticles using a Qualtech QPI-168 dip coater. A dipping speed of 500 mm / min was used to obtain a hard coat thickness of 5 μm. After dipping, the sample was dried for 30 minutes and then cured in an oven at 130 °C for 1 hour. This process was carried out at a humidity of 25 - 45%.

[0083] Characteristic Evaluation of Coated Polycarbonate Substrate Containing Low-E Coating with Frequency Selective Surface on Metal IR Reflective Layer

[0084] Figure 7 and the following table provide the characteristics of the coated article having a frequency selective surface and compare it with a plain polycarbonate and a coated article without a frequency selective surface.

Table 2

[0085] The FSS technology has also been applied to fully grown low-E coatings (Figure 2). Before growing the upper TiO2, Al-doped SiO2 and hard coat, the TiO2 / NiCr / Ag / NiCr film was laser-etched in a hexagonal pattern. The transmittance of the resulting low-E coating hardly changed, and the blocked IR light decreased by only 10% (Figure 8).

[0086] Fabrication of Coated Polycarbonate Substrate with Ag Film Supporting Frequency Selective Surface

[0087] A commercially available transparent hard-coated PC (Makrolon® Abrasion Resistance - AR) made by Bayer with dimensions of 100 mm × 100 mm and a thickness of 4.5 mm was used as the substrate. The dielectric constant (permittivity value) of the PC substrate is 2.96 (Technical data sheet, 2023). Before growing the Ag film, the PC substrate was washed with soap, rinsed with reverse osmosis (RO) water, and then plasma-treated for 2 minutes to remove contaminants (Alder et al., 2020). A 10-nm-thick Ag thin film was deposited on the previously cleaned PC substrate using an ion-assisted electron beam evaporation system, Satis Vacuum 725. The substrate was at 1×10 -4It was mounted on a rotating table that moved at 90 rpm, 750 mm above the evaporant, while being subjected to Ar ion bombardment at a pressure of mbar. An Ag pellet (purity 99.99%) manufactured by Kurt J. Lesker Company was placed in a tungsten crucible and evaporated at 1.4 Å / s. A crystal oscillator (Sycon Instruments, STC-2000A) was used to monitor the thickness and deposition rate in real time. The low-e coating consists of several layers, but in this example, only a single thin Ag layer responsible for the signal attenuation of the low-e coating was used to analyze the effect of the pattern.

[0088] Several FSS patterns were designed using AutoCAD 2021 (AutoCAD, 2021) and Solidworks 2019 (SOLIDWORKS, 2019) software. The same software program was used to measure the amount (%) of the metal area removed from the coating. The pattern design was saved as a Drawing Exchange Format (DXF) file and then transferred to a laser ablation device.

[0089] FSS patterns were created using the laser ablation method. Periodic patterns were ablated and evaporated from the Ag thin film by a Nd:YAG (1064 nm) pulsed laser G8 (G8, 2008) manufactured by Sei Laser. The frequency, power, and speed of the ablation process were optimized to avoid damage to the PC substrate and obtain the thinnest possible line width. Therefore, the patterns were etched at a speed of 100 mm / second, a power of 18 W, and a frequency of 10 kHz. With these parameters, an ablation line width of 50 ± 10 μm and a clean ablation area were produced. An extraction system was attached to the machine to remove the fumes from the evaporation process.

[0090] Various FSS patterns having regular polygonal shapes (e.g., triangles, squares, and hexagons) were laser-etched onto an Ag-coated PC substrate. The 5G attenuation values (72 - 82 GHz), optical properties, and morphology of the patterns were analyzed to determine which provided the lowest attenuation without compromising IR reflectivity and visible transmittance. The signal attenuation values (72 - 82 GHz) were measured using an automotive radome tester (R&S® QAR by Rohde & Schwarz).

[0091] Characteristic evaluation of a coated polycarbonate substrate having an Ag coating carrying a frequency selective surface

Table 3

[0092] Fabrication of a coated polycarbonate substrate including a low-E coating having a frequency selective surface on a metal IR reflective layer by a photolithography process

[0093] The following photolithography process is also shown in Figure 10.

[0094] (1) A stack of PC substrate / TiO2 / NiCr / Ag was prepared in the same manner as described for the coated polycarbonate substrate including a low-E coating having a frequency selective surface on a metal IR reflective layer by laser etching.

[0095] (2) A positive photoresist solution (AZ® 1518) was spin-coated onto the film. Then, the sample was cured on a hot plate at 100 °C for 1 minute to crosslink the photoresist (soft bake process). The thickness of the photoresist was approximately 1 μm.

[0096] (3) Using a mask alignment system (EVG (registered trademark) 620), UV light (365 nm) was exposed through a mask having a hexagonal patch pattern (D = 0.5 mm, w = 5 μm). The mask (manufactured by JD Photo Data) consists of soda-lime glass with a chromium pattern on the top, which selectively passed UV light and selectively processed the material. The UV light passing through the mask induced chemical changes in the photoresist and modified the structure.

[0097] (4) A developer (AZ (registered trademark) 726 MIF) was applied to the surface, which dissolved the photoresist regions exposed to UV light and left a hexagonal patch pattern on the photoresist layer.

[0098] (5) To transfer the hexagonal pattern onto the Ag layer, a wet etching technique was used by immersing the sample in an etching solution (ammonium cerium(IV) nitrate - (NH4)2[Ce(NO3)6]) for 1 minute and 30 seconds. The etching solution penetrated into the hexagonal voids and completely removed the Ag layer.

[0099] (6) After the desired pattern was completed, the remaining photoresist was removed by rinsing with an acetone solution (CH3COCH3). Compressed air was sprayed immediately after rinsing to dry the sample and remove the residues of the etchant or acetone.

[0100] (7) After the patterning process on the Ag layer, the sample was coated with other layers (NiCr / TiO2 / SiO2 / MP101).

[0101] The resulting low-E coating supported by the substrate had a visible transmittance of about 64% and an IR reflectance of about 65%. The 5G attenuation value (72 - 82 GHz) was about 5.7 dB.

[0102] Any reference to prior art in this specification is not an admission or any form of suggestion that such prior art forms part of the common general knowledge, nor should it be construed as such.

[0103] As used in this specification and the following claims, the terms "comprise", "include", and their derivatives (e.g., "comprises", "comprising", "includes", "including") should be interpreted to include the features to which the term refers and not to mean the exclusion of the presence of any additional features, unless specifically stated or implied otherwise.

[0104] In some cases, for the sake of brevity and / or to aid in the understanding of the scope of the disclosure, a single embodiment may combine multiple features. In such cases, it should be understood that these multiple features may be provided separately (in separate embodiments) or in any other suitable combination. Alternatively, if separate features are described in separate embodiments, these separate features may be combined in a single embodiment, unless specifically stated or implied otherwise. This also applies to the claims, which may be amended to include features defined in any other claim. Further, the phrase "at least one" referring to a list of items refers to any combination of those items, including a single item. By way of example, "at least one of a, b, or c" is intended to include a, b, c, a - b, a - c, b - c, and a - b - c.

[0105] Those skilled in the art will understand that the present disclosure is not limited in its use to the specific one or more applications described. The present disclosure is not limited to its preferred embodiments with respect to the specific elements and / or features described herein. The present disclosure is not limited to the one or more disclosed embodiments and can be subject to numerous rearrangements, modifications, and substitutions without departing from the scope described and defined by the following claims.

Claims

1. A coated article comprising a metal layer, wherein the metal layer supports a frequency-selective surface configured to reduce attenuation of telecommunications frequency signal transmission.

2. The coated article according to claim 1, wherein the metal layer is a metal IR reflective layer in the low-E coating contained in the coated article.

3. The coated article according to claim 1, wherein the frequency-selective surface includes a periodic pattern and / or a periodic pattern.

4. The coated article according to claim 3, wherein the periodic pattern is selected from the group consisting of a periodic hexagonal lattice, a periodic square lattice, a periodic triangular lattice, a periodic circular lattice, and a periodic kagome lattice, and the non-periodic pattern is selected from Penrose tiling.

5. The coated article according to any one of claims 1 to 4, wherein the frequency-selective surface includes a periodic pattern having a unit cell dimension of less than about 2 mm and an aperture line width of about 5 μm to about 60 μm, for example, about 30 μm to about 60 μm.

6. The coated article according to claim 5, wherein the frequency-selective surface includes a periodic pattern having a unit cell dimension of about 0.5 mm and an aperture line width of about 50 μm.

7. The coated article according to claim 6, wherein the frequency-selective surface includes a periodic hexagonal grid having a unit cell dimension of about 0.5 mm and an aperture line width of about 50 μm.

8. The coated article according to any one of claims 1 to 4, wherein the telecommunications frequency is for fifth-generation (5G) communication.

9. The coated article according to any one of claims 1 to 4, wherein the attenuation of telecommunications frequency signal transmission is reduced from about 30 dB to about 1 dB when compared to a coated article in which the metal layer does not have a frequency-selective surface.

10. The metal layer is Ag, Al, Cu, Zn, Nb, TiN, Ag / Au alloy, Ag / Cu alloy, Ag / Al alloy, NbN ｘ , NbCr, NbCrN ｘ NbZrO ｘ A coated article according to any one of claims 1 to 4, comprising and / or Au.

11. The coated article according to any one of claims 1 to 4, wherein the metal layer has a thickness of about 5 nm to about 25 nm, preferably about 10 nm to about 20 nm.

12. The coated article according to any one of claims 1 to 4, wherein the coated article comprises a low-E coating supported by a substrate, and the low-E coating comprises, in order from the substrate outward, a dielectric layer, a protective layer, a metallic IR reflective layer, a protective layer, and a dielectric layer.

13. The coated article according to any one of claims 1 to 4, wherein the substrate of the coated article is substantially made of plastic or glass.

14. A method for reducing attenuation of telecommunications frequency signal transmission of a coated article according to claim 1, comprising creating a frequency-selective surface on the metal layer.

15. The method according to claim 14, wherein a frequency-selective surface is created on the metal layer by laser etching or photolithography.

16. The method according to claim 15, wherein one or more stacks are laser-etched to create a frequency-selective surface on the metal layer, and the one or more stacks are selected from the following group: substrate / metal layer stack, substrate / protective layer / metal layer stack, substrate / dielectric layer / protective layer / metal layer stack, substrate / dielectric layer / protective layer / metal layer / protective layer stack, substrate / metal layer / substrate, substrate / protective layer / metal layer / substrate stack, substrate / dielectric layer / protective layer / metal layer / substrate stack, and substrate / dielectric layer / protective layer / metal layer / protective layer / substrate stack.

17. The method according to claim 16, wherein, in the case of laser etching, the laser beam enters from either side of the stack to create a frequency-selective surface on the metal layer.

18. The method according to claim 15, wherein a multiple pane window containing a metal layer is laser-etched to create a frequency-selective surface on the metal layer.

19. The method according to claim 14, wherein an area of ​​approximately 25% or less of the metal layer is removed to create a frequency-selective surface on the metal layer.

20. The method according to claim 14, wherein an area of ​​approximately 20% or less of the metal layer is removed to create a frequency-selective surface on the metal layer.

21. The method according to claim 14, wherein an area of ​​approximately 10% or less of the metal layer is removed to create a frequency-selective surface on the metal layer.

22. Use in automobiles and buildings of a coated article as described in claim 1 or prepared according to claim 14.

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