Solar mirrors and methods of making solar mirrors having improved properties

Solar mirrors and methods of making solar mirrors with improved properties

[0001] This application is titled "Solar Mirrors and Methods of Making Solar Mirrors with Improved Characteristics", the filing date is July 14, 2016, the international application number is PCT/US2016/042181, and the national application number is 201680053848.8 divisional application of a PCT application.

[0002] Announcement of Government Support

[0003] This invention was made with government support under Contract No. DE-FC36-08GO18033 awarded by the U.S. Department of Energy. The United States Government may have certain rights in this invention.

[0004] Cross-references to related applications

This application claims the priority of U.S. Provisional Patent Application Serial No. 62/219,386 entitled "SOLAR MIRRORS AND METHODS OF MAKING SOLAR MIRRORS HAVING IMPROVED SELECTED PROPERTIES" submitted on September 16, 2015. The entire contents of U.S. Provisional Patent Application Serial No. 62/219,386 are incorporated herein by reference.

Technical field

[0006] The present application relates to articles for reflecting electromagnetic energy, particularly for reflecting electromagnetic energy emitted by the sun. Such articles include, but are not limited to, solar mirrors, and the present invention relates to methods of making solar mirrors with improved physical properties such as, but not limited to, spectral properties to increase the useful life and performance of the solar mirror.

[0007] Currently Available Technologies

[0008] As understood by those skilled in the field of solar mirrors, solar power is becoming a more commercially acceptable and economically viable energy source. By way of example and not limitation of the invention, a known application is the use of solar mirrors to concentrate sunlight for generating electricity. As used herein, the term "sunlight" means electromagnetic energy emitted by the sun. Solar mirrors with high solar radiation reflectivity are used in Concentrated Solar Thermal Power (CSTP) facilities. Several different mirror geometries are used for these applications. One system uses curved parabolic solar mirrors to focus solar energy onto tubes positioned along the focal line. The heat transfer medium in the tubes carries the absorbed thermal energy to a power station where it is used to generate electricity. Another system uses a solar tower in which solar mirrors reflect sunlight and focus it onto receiving surfaces on the tower. Heat generated by focused sunlight is transferred to a working fluid such as sodium, and the heated working fluid is used to generate electricity.

[0009] Another application of such mirrors is for "concentrated photovoltaics" (CPV). In this application, mirrors focus or concentrate sunlight onto photovoltaic (PV) devices, thereby improving the energy output of each device.

[0010] In these systems, and as discussed above, it is desirable for the mirror to reflect as much sunlight as possible. It is also desirable that the mirror have a commercial life as long as possible to preclude frequent mirror changes. Mirrors with reflective surfaces are used to reflect solar energy to a focal point allowing the device to convert sunlight or solar energy into electrical energy and/or thermal energy. In the practice of one non-limiting embodiment, a solar mirror includes a glass substrate having a first major surface and an opposing second major surface. The first major surface is designated to face the solar light source, and the opposing second major surface of the glass substrate faces away from the solar light source. In this non-limiting example, a reflective coating is applied to the first major surface of the substrate. In another non-limiting embodiment of the invention, a reflective coating is applied to the second major surface of a light-transmissive or transparent substrate. In the following discussion, a solar reflective coating is applied to the second major surface of a transparent substrate. The second major surface faces away from the source of sunlight or solar energy.

[0011] As further understood by those skilled in the art of solar mirror technology, it is desirable to maximize the amount of sunlight reflected from the solar mirror and to maximize the useful service life of the solar mirror. The percent reflectance of sunlight from a solar mirror is equal to the irradiance of sunlight reflected from the solar mirror divided by the irradiance of sunlight incident on the solar mirror. Reflectance may be measured in any convenient manner, such as, but not limited to, in the practice of the invention the reflectance of sunlight is measured using a spectrophotometer.

[0012] Disclosed herein are methods and articles for increasing the percent reflectance of sunlight from solar mirrors and increasing the useful life of solar energy.

Contents of the invention

[0013] The present invention relates to an article for reflecting solar energy, the article including, inter alia, a substrate having a first surface and an opposing second surface, and a solar reflective coating. The solar reflective coating particularly includes: a first metallic solar reflective film, which is also referred to as a "first metal film" below, the first metallic film having a first surface and an opposite second surface; a second metallic solar reflective film. a film, which is also referred to below as a "second metal film", said second metal film having a first surface and an opposite second surface; and a separator layer or separator film having a first surface and an opposite second surface. surface, wherein the first surface of the separation film is above the second surface of the first metal film, and the first surface of the second metal film is above the second surface of the separation film, wherein , the first surface of the first metal film is above the second surface of the substrate and attached to the second surface of the substrate.

The present invention further relates to an article for reflecting solar energy, the article having in particular a coating stack having in particular a solar reflective film and a metal oxide film, the coating stack being applied to glass on the major surface of the substrate; and a polymeric envelope over the outer wall surface of the coating stack, over the second surface of the protective outer coating, and over the peripheral edge of the coated article, The encapsulation includes, but is not limited to, a base layer, a top layer, and metallic zinc flakes in the base layer.

[0015] The above article further includes a marginal edge portion of the top of the coating stack and an outer wall of the coating stack covered with a base layer, and the base layer defines an uncoated area on the top surface of the coating stack, and the top layer overlays The uncoated areas of the top surface of the coating stack and the base layer.

The invention further relates to an article for reflecting solar energy, said article inter alia comprising a coating stack fixed to a major surface of a glass substrate, said coating stack comprising a solar reflective layer , wherein a surface of the coating stack spaced apart from the substrate is electrically conductive, and a polymeric encapsulation is over the outer wall surface of the coating stack, the encapsulation comprising a top layer, the top layer being electrodeposited (also Known as "electrophoresis") to the outer surface of the coating stack, where the base layer of the encapsulation utilizes metallic zinc flakes.

Description of the drawings

[0017] Figure 1 is a cross-sectional view of a prior art solar mirror showing a solar reflective coating.

[0018] FIG. 2 is an isometric view of a prior art formed solar mirror showing an enlarged view of solar rays incident on the concave surface of the solar mirror.

[0019] Figure 3 is a view similar to that of Figure 1 showing a solar mirror of the present invention having a solar reflective coating of the present invention.

[0020] FIG. 4 is a view similar to that of FIG. 3 illustrating another non-limiting embodiment of the solar reflective coating of the present invention.

[0021] FIG. 5 is a view similar to that of FIG. 1 illustrating another prior art embodiment of a solar mirror with additional coatings, with cross-section hatching not shown in FIG. 5 for clarity. .

[0022] Figure 6 is a view similar to that of Figure 5 illustrating the solar reflective coating of the present invention with additional coatings and films of Figure 5, with cross-section shading not shown in Figure 6 for clarity. Wire.

[0023] FIG. 7 is a graph illustrating the solar weighted Rg reflectance ("SpEx WIRg") approximately excluding specular reflection for prior art solar mirrors and the mirror of the present invention.

[0024] Figure 8 is a diagram illustrating the approximate specular-exclusion solar energy of samples 3a and 4a with their coatings in a deposited, non-heated condition and samples 3b and 4b with their coatings in a deposited, heated condition. Graph of reflectance weighted Rg "SpEx WIRg").

[0025] Figures 9-13 are views similar to that of Figure 3 illustrating a non-limiting embodiment of an enclosure having an enclosure in accordance with the teachings of the present invention.

[0026] Figure 14 is an isometric view of a planar solar reflector incorporating features of the present invention.

[0027] FIG. 15 is a view taken along the line of FIG. 14.

Detailed ways

[0028] As used herein, spatial or directional terms, such as, "left," "right," "in," "out," "upper," "lower," and similar terms, relate to the present invention as described in the appended As shown in the picture. It is to be understood, however, that the invention may assume various alternative orientations, and therefore these terms are not to be considered limiting. Additionally, as used herein, all numbers expressing dimensions, physical characteristics, processing parameters, amounts of starting materials, reaction conditions and similar parameters used in this document and the claims will be understood in all cases to be understood by the term " About" was modified. Therefore, unless otherwise stated, The numerical values set forth in the following text and claims may vary depending on the desired properties sought to be obtained by the invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical value should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Furthermore, all ranges disclosed herein should be understood to include the beginning and ending range values and any and all subranges subsumed therein. For example, a stated range of "1 to 10" shall be deemed to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges ending with a minimum value of 10 Starting with a value of 1 or greater and ending with a maximum value of 10 or less, for example, 1 to 3.3, 4.7 to 7.5, 5.5 to 10 and similar values. Additionally, as used herein, the terms "formed on," "deposited on," "disposed on" mean formed, deposited, or disposed on a surface on, but not necessarily in direct contact with the surface. For example, a coating "formed over a substrate" does not exclude the presence of one or more other coatings or films of the same or different composition between the formed coating and the substrate.

[0029] As used herein, the term "polymer" or "polymerized" includes oligomers, homopolymers, copolymers, and terpolymers, e.g., composed of two or more types of monomers or Polymers formed from polymers. The term "ultraviolet region" or "ultraviolet radiation" means electromagnetic energy having a wavelength in the range of 100 nanometers (hereinafter "nano" is also referred to as "nm") to less than 380 nm. The term "visible light region" or "visible light" refers to electromagnetic radiation having a wavelength in the range of 380 nm to 780 nm. The term "infrared region" or "infrared radiation" refers to electromagnetic radiation having wavelengths in the range from greater than 780 nm to 100,000 nm. Furthermore, parameters such as "visible light transmittance" and "visible light reflectance" and similar parameters are those determined using conventional methods. Those skilled in the art will understand that properties such as visible light transmission or visible light reflectance may vary based on the physical dimensions (eg, thickness) of the article being tested. Therefore, any comparisons of the present invention should be made on equivalent

Calculate the thickness.

Before discussing several non-limiting embodiments of the present invention, it will be understood that, as the invention is capable of other embodiments, the invention is not limited in its application to the specific non-limiting embodiments shown and discussed herein. Details of limiting examples. Further, other terminology used herein to discuss the invention is for purposes of description and is not limiting. Furthermore, similar reference numbers indicate similar elements in the following discussion unless otherwise indicated.

[0031] Non-limiting embodiments of the invention relate to solar mirrors. As can be appreciated, the solar mirror may be a planar solar mirror, such as, but not limited to, the prior art planar solar mirror 5 (Fig. 1) and/or the planar solar mirror 7 (Fig. 3) incorporating features of the present invention, or a solar mirror. The mirror may be a shaped solar mirror, such as, but not limited to, a shaped solar mirror 9 having a concave surface 10 and an opposing convex surface 11 (Fig. 2) and disclosed in U.S. Published Patent Application 2010/0242953 (hereinafter also referred to as " Pub. '953"). The entire contents of Pub '953 are hereby incorporated by reference.

[0032] Non-limiting embodiments of the present invention are discussed with reference to reflection of electromagnetic radiation, such as, but not limited to, electromagnetic waves having wavelengths in the range of 300 nm to 2500 nm. As used herein, the term "reflective article" refers to any article, such as, but not limited to, configured to reflect electromagnetic radiation, such as ultraviolet radiation, visible radiation, and/or infrared radiation, for example, for use in concentrated solar power generation. The "solar mirror" in the system. However, it should be understood that embodiments of the present invention are not limited to use with solar mirrors, but may be practiced with articles in other fields, such as, but not limited to, laminated or non-laminated of residential mirrors and/or commercial mirrors and/or windows and/or reflectors for use in optical systems (e.g., video projectors or optical scanners), to name a few. Therefore, it should be understood that the specifically disclosed exemplary embodiments are merely introduced to explain the general concepts of the invention and that the invention is not limited to these specific exemplary embodiments.

[0033] Non-limiting embodiments of the invention to be discussed herein include, but are not limited to (A) solar reflective coatings with improved optics and stability; and (B) encapsulated coating stacks of solar mirrors to Increase the useful life of solar mirrors. In the following discussion, coating stacks for solar mirrors are vacuum deposited solar reflective films, layers, and coatings using magnetron sputtering. However, the invention is not limited thereto and the invention may be implemented by means of any type of deposited film, layer and/or coating such as a chemical vapor deposition coating process. It will be understood that embodiments of the invention are presented in separately identified sections for the purpose of understanding non-limiting embodiments of the invention, and there is no suggestion in one form or another that embodiments of the invention are independent and unique. As will be appreciated, the non-limiting embodiments of the invention may be used alone or in combination with each other.

Solar reflective coatings with improved optics and stability

[0035] This non-limiting embodiment of the present invention provides a solar reflective coating and a method for applying a solar reflective coating to a substrate to provide improved optical and thermal stability compared to prior art solar mirrors. Sexy solar mirrors. The prior art solar mirror 5 shown in FIG. 1 includes a substrate or ply 12 having a first or outer major surface 14 and an opposite second or inner major surface 16 . The solar mirror 9 shown in Figure 2 has a solar reflective concave surface 10 that faces the sun 20 to reflect solar energy to a focal point 21. In the following discussion, the first major or outer surface 14 of the substrate 12 and the concave or outer surface 10 of the solar mirror 9 are designated as facing incident radiation, for example, the sun 20 (only the sun is shown in FIG. 2 20), and the second surface 16 of the substrate 12 and the convex surface 11 of the solar mirror 9 face the opposite direction of the incident radiation. Continuing with reference to FIG. 1 , surface 16 of substrate 12 is designated to support a prior art solar reflective coating 22 as shown in FIG. 1 . Optionally, a base layer 24 is provided between the reflective coating 22 and the surface 16 of the laminate 12 . Over the solar reflective coating 22 is applied a protective coating 25 discussed in detail below.

[0036] The solar mirror 7 of the invention shown in Figure 3 includes a substrate or laminate 12 having a third

One major surface 14 is the outer major surface and an opposite second major surface 16 is the inner major surface. The solar reflective coating 27 of the present invention is applied over the surface 29 of the underlayer 24 when the underlayer is present, and the solar reflective coating 27 of the present invention is applied over the surface 16 of the substrate 12 when the underlayer is not present. , and the protective coating 25 is applied over the solar reflective coating 27 . In the following discussion, the first major surface 14 of the solar mirror 7 is designed to face the incident radiation, i.e., the sun, and the second surface 16 of the substrate 12 faces the opposite direction of the incident radiation and is designated to support the present invention. Solar reflective coating27. Continuing to refer to Figure 3, the solar mirror 7 of the present invention includes a solar reflective coating 27 having two sub-layers 28a, 28b separated by a separation layer 30. Shown in Figure 4 is a solar mirror 26 of the present invention that includes three sub-layers, eg three sub-layers 28a, 28b and 28c separated by separation films or media 30a and 30b to reduce crystal growth. The solar reflective coating 27 of the present invention is discussed in greater detail below.

[0037] In the broad practice of the present invention, substrate or laminate 12 may comprise any desired material having any desired characteristics. For example, when the first major surface 14 of the laminate 12 faces incident radiation, such as the sun 20 (only the sun 20 is shown in FIG. 3 ), the substrate or second major surface 16 of the laminate 12 supports or carries a solar reflective coating. sub-layers 28 and spacer layers 30, such as, but not limited to, sub-layers 28a and 28b. Laminate 12 is preferably transparent or translucent to visible light. The term "transparent" means having a transmittance of greater than 0% up to 100% in a desired wavelength range, eg, visible light. Alternatively, the laminate 12 may be translucent. "Translucent" means allowing the transmission of electromagnetic radiation (eg, visible light), but diffusing or scattering that radiation. Examples of suitable materials for laminate 12 include, but are not limited to, thermoplastic, thermoset, or elastomeric polymeric materials, glass, Ceramics and metals or metal alloys and combinations, compositions or mixtures thereof. Specific examples of suitable materials include, but are not limited to, plastic substrates (e.g., acrylic polymers, e.g., polyacrylates; polyalkyl methacrylates, e.g., polymethyl methacrylate, polyethyl methacrylate , polymethylacrylate and similar; polyurethane; polycarbonate; polypropylene terephthalate, e.g., polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate Glycol esters and the like; silicone-containing polymers; or copolymers of any of the monomers used to prepare these, or any mixtures thereof); ceramic substrates; glass substrates; or any of the above A mixture or composition. For example, laminate 12 may include conventional soda-lime silicate glass, borosilicate glass, or leaded glass. The glass can be clear glass. The term "clear glass" means non-tinted or untinted glass. Alternatively, the glass may be opaque, tinted or otherwise colored glass. The glass may be annealed or heat treated glass. As used herein, the term "heat treated" means heat tempered, heat bent, Heat strengthened or laminated. The glass may be any type of glass, e.g., conventional float glass, and may be any composition having any optical properties, e.g., any of visible light transmittance, ultraviolet transmittance, infrared transmittance, and/or total solar transmittance. value. Although not limited to the present invention, examples of suitable glasses for substrate or laminate 12 are described in U.S. Patent Nos. 4,746,347; 4,792,536; 5,030,593; 5,030,594; 5,240,886; 5,385,872; and 5,393,593. The substrate or laminate 12 may be of any desired size, such as length, width, shape, or thickness. In an exemplary embodiment, the first layer 12 may have a thickness greater than 0 up to 25 mm (1.00 inches), for example, a thickness of 1 mm to 10 mm, for example, a thickness of 1 mm to 5 mm, for example, a thickness less than 4 mm, For example, a thickness of 3mm to 3.5mm, for example, a thickness of 3.2mm. Additionally, the laminate 12 may have any desired shape, such as a planar shape, a curved shape, a parabolic shape, or the like. Furthermore, when one or more primary reflective coatings, such as reflective coating 27, rest on the second major surface 16 of the solar mirror, the laminate 12 may include, but is not limited to, one or more materials, i.e., the The material exhibits a low absorptivity of electromagnetic radiation for electromagnetic radiation in the region or regions of electromagnetic radiation expected to be reflected.

[0038] In a non-limiting embodiment of the present invention, the laminate 12 may have high visible light transmittance at a reference wavelength of 550 nanometers (nm) and a reference thickness of 3.2 mm. The term "higher visible light transmission" means that the visible light transmission at 550 nm is greater than or equal to 85% at a reference thickness of 3.2 mm for laminates, e.g., greater than or equal to

87%, for example, greater than or equal to 90%, for example, greater than or equal to 91%, for example, greater than or equal to 92%, for example, greater than or equal to 93%, for example, greater than or equal to 95%. Particularly useful glasses for practicing the present invention are disclosed in U.S. Patent Nos. 5,030,593 and 5,030,594. Non-limiting examples of glasses that may be used to practice the present invention include, but are not limited to, Starphire.RTM, Solarphire.RTM, Solarphire.RTM.PV, Solargreen.RTM, Solextra.RTM, GL-20.RTM, GL-35. TM, Solarbronze.RTM, CLEAR and Solargray.RTM glasses, all of which are commercially available from PPG Industries, Pittsburgh, PA.

[0039] As will be understood by those skilled in the art, the laminate 12 (see Figures 1 and 3) is transparent when the laminate 12 is positioned between the sun 20 and the reflective coating 22, and when the reflective coating is positioned between Between the sun 20 and the laminate, the laminate may be opaque or transparent.

Referring to Figure 3, in another non-limiting embodiment of the present invention, a layer 24 or primer is provided between sub-layer 28b of the solar reflective coating 18 and the second major surface 16 of the laminate 12. Layer 24 or bottom layer 24. The base coat 24 is preferably deposited using a vacuum-based process immediately prior to depositing the vacuum deposited silver (Ag) reflective coating 27 without breaking the vacuum, thereby providing an uncontaminated surface to receive the solar reflective coating 27 . Primer coating 24 may provide a stronger or more durable interface between ply 12 and reflective coating 27 . The base coating 24 may include, but is not limited to, one or more materials selected such that the interface between the base coating 24 and the solar reflective coating 27 is smaller than the interface between the laminate 12 and the primary reflective coating 27 . The interface is more mechanically, chemically and/or environmentally stable. Furthermore, basecoat 24 may serve as a diffusion barrier to exchange of elements between laminate 12 and reflective coating 27 (e.g., sodium migrates away from glass laminate 12 into one or more overlay coatings or Migration of metals such as silver from the reflective coating 27 to the glass) may occur, inter alia, as a result of subjecting the coated article to elevated temperatures, for example for bending or thermal strengthening.

[0041] Additionally or alternatively, basecoat 24 may provide a smoother or planar surface upon which an overcoat, such as solar reflective coating 27, is deposited. Examples of materials suitable for base coat 24 include, but are not limited to, inorganic materials, such as, but are not limited to, light-transmissive low-absorption dielectrics, such as metal oxides, metal nitrides, and/or combinations thereof, metal oxides, and/or Compositions or mixtures of metal nitrides. Examples of suitable metal oxides include alumina, silica, titanium dioxide, alumina, zinc oxide, zinc stannate, tin dioxide or mixtures or combinations thereof. Other examples for base layer 24 include one or more layers of silicon dioxide and/or silicon nitride, or combinations thereof. In one non-limiting example, the base coat or base layer 24 includes, but is not limited to, titanium dioxide. Primer coating 24 may be of any composition or thickness to provide sufficient functionality to the article (eg, mechanical, chemical, passivation, planarization, adhesion, diffusion barrier properties, environmental durability enhancement, optical enhancement). In a specific embodiment in which the base coating 24 is titanium dioxide, the base coating 24 has a thickness in the range of 0.1 nm to 5 nm, such as 0.1 nm to 3 nm, such as 0.5 nm to 3 nm, such as 1 nm to 3 nm. 3nm, for example, 0.5nm to 2nm, for example, 1nm to 2nm, for example, 1.5nm to 2nm, for example, 1.8nm.

[0042] With reference to Figures 3 and 4 as appropriate, in a preferred practice of the invention, sub-layer 28b of the solar reflective coating 27 of the solar mirror 7 (Figure 3) and the solar reflective coating of the solar mirror 26 (Figure 4) Sublayer 28c of 27 is formed over at least a portion of the second major surface 16 of the substrate 12, eg, over at least a portion of the underlying layer 24, if present. Optionally, a protective coating 25 is provided over at least a portion of the solar reflective coating 27 . Although in the illustrative embodiment shown in FIGS. 3 and 4 , the bottom layer 24 , the solar reflective coating 27 and the protective coating 25 are formed over the second major surface 16 of the substrate 12 , it should be understood that , at least some of the coatings may alternatively be formed over the first major surface 14 of the substrate 12 . Selection of materials for the solar mirrors 7 and 26 of the present invention, such as, but not limited to, the material of the substrate 12 and in particular the material of the optional base or base coat 24 serving as a barrier coating for the solar reflective coating 27, and materials for protective coating 25 are also discussed in U.S. Patent No. 8,445,098 ("Patent '098"), which is hereby incorporated by reference, and

and was deemed unnecessary for further discussion.

[0043] For ease of reference to coatings or films, coatings or films are discussed as individual coatings and films, for example, but not limited to the present invention, the individual films of the solar mirror 7 of the invention shown in Figure 3 are the bottom layer 24, The solar reflective coating 27 including the sub-layers 28a and 28b and the separation film 30 and the protective film 25 are shown in Figure 3. The respective films of the solar mirror 26 of the invention shown in Figure 4 are the base layer 24, the reflective coating 27 including the sub-layers 28a to 28c and the separation films 30a to 30b, and the protective film 25, as shown in Figure 4. Optionally, the films of solar mirror 26 shown in FIG. 4 may be collectively referred to as coating stack 34. For the prior art solar mirror 5 shown in Figure 1, the respective films of the prior art solar mirror 5 shown in Figure 1 are the bottom layer 24, the solar reflective coating 22 and the protective film 25, as shown in Figure 1 As shown in , they may optionally be referred to as prior art coating stacks 35 .

Referring back to FIGS. 3 and 4 as desired, the solar reflective coating 27 is formed over at least a portion of the second major surface 16, for example, over at least a portion of the base coat 24, if present. . The solar reflective coating 27 of the present invention includes, but is not limited to, two or more sub-layers 28, such as sub-layers 28a and 28b in Figure 3 and sub-layers 28a to 28c in Figure 4. In the preferred practice of the invention, component sublayer 28 is one or more solar reflective materials that reflect a portion of the electromagnetic spectrum. In one non-limiting embodiment of the present invention, solar reflective coating 28 includes, but is not limited to, radiation reflective metal sublayers 28a and 28b or 28a and 28b and 28c, and the like. Examples of suitable reflective metals for sublayer 28 of solar reflective coating 27 include, but are not limited to, metallic silver, aluminum, gold, copper, platinum, iridium, osmium, palladium, nickel, alumina, or other noble metals and alloys, mixtures thereof , blends thereof or combinations thereof. In a non-limiting embodiment of the present invention, the solar reflective coating 27 includes but is not limited to a metallic silver sub-layer 28 such that the thickness of the solar reflective coating 27 is in the range of 50 nm to 500 nm, preferably 100 nm. The solar reflective coating 27 of Figure 4 may be deposited to a thickness such that the solar mirrors 7 and 26 have any particular desired level of reflectivity within the desired range of electromagnetic radiation to be reflected. Sub-layer 28a, 27 of solar reflective coating 27 28b and 28c may be deposited to a thickness sufficient to render solar reflective coating 27 opaque within a desired wavelength range, such as visible light. Solar reflective coating 27 may be particularly useful in reflecting visible and infrared solar energy. In one specific non-limiting embodiment of the invention, solar reflective coating 27 is deposited by a conventional sputtering process, as described in greater detail below. In another non-limiting embodiment of the invention, the coating stack 32 of the solar mirror 7 may include, but is not limited to, a "high reflector" having multiple alternating films of high and low refractive index materials, As is known in the art, see, for example, Figure 11 and the discussion of Figure 11 for additional membranes.

The protective coating 25 assists in protecting the underlying layers of coatings and/or films of the coating stack 32 of the solar mirror 7 shown in FIG. 3 and the coating stack 34 of the solar mirror 26 shown in FIG. 4 , respectively. Mechanical and chemical attack during manufacturing, storage, shipping, handling, handling and/or during the service life of the mirror in the field. The protective coating 25 also helps protect the underlying layer from the ingress of liquid water, water vapor and other environmental solid, liquid or gaseous contaminants. The protective coating 25 may be an oxygen barrier coating to prevent or reduce the transfer of ambient oxygen into the underlying layer during subsequent processing, such as during heating or bending. Protective coating 25 may be any desired material or mixture of materials, such as, but not limited to, one or more inorganic materials. In an exemplary embodiment, protective coating 25 may include a layer having one or more metal oxide materials such as, but not limited to, aluminum, silicon, or alloys thereof, blends thereof, oxides of their compositions and/or mixtures thereof. For example, protective coating 25 may be a single coating containing an oxide deposited by sputtering a sputter target containing silicon and aluminum at 0 wt. % to 100wt.% aluminum and/or 100wt., % to 0.% silicon, for example, 1wt.% to 99wt.% aluminum and 99wt. % to 1wt·% silicon, for example, 5wt·% to 95wt·% aluminum and 95wt·% to 5wt·% silicon, for example, 10wt·% to 90wt·% aluminum and 90wt·% to 10wt· earth· % of silicon, for example, 15wt% to 90wt, % of aluminum and 85wt, % to 10wt of earth. % of silicon, for example,

50wt.% to 75wt.% aluminum and 50wt.% to 250wt.% silicon, for example, 50wt.% to 700wt.% aluminum and 50wt.% to 30wt.% silicon, for example, 35wt.% to 100 wt.% aluminum and 65 wt.% to 0 wt.% silicon, for example, 70 wt.% to 90 wt.% aluminum and 30 wt.% to 100 wt.% silicon, for example, 75 wt.% to 85 wt.% aluminum and 25 wt.% to 15 wt.% silicon, for example, 88 wt.% aluminum and 12 wt.% silicon, for example, 65 wt.% to 75 wt.% aluminum and 35 wt.% to 25 wt.% silicon, for example, 70 wt. . % aluminum and 30 wt. % silicon, for example, 60 wt. % to less than 75 wt. % aluminum and greater than 25 wt.% to 40 wt.% silicon. In a specific non-limiting example, protective coating 23 includes an oxide deposited by sputtering a sputter target containing 40 wt.% to 15 wt.% aluminum and 60 wt.% to 85 wt.% silicon, for example, 85 wt.% silicon and 15 wt.% aluminum. Other materials, such as aluminum, chromium, hafnium, yttrium, nickel, boron, phosphorus, titanium, alumina and/or their oxides, may also be present, for example to adjust the refractive index of the protective coating 25 . In a non-limiting example, the refractive index of the protective coating 25 may be in the range of 1 to 3, such as 1 to 2, such as 1.4 to 2, such as 1.4 to 1.8.

[0046] In one non-limiting embodiment of the invention, protective coating 25 includes, but is not limited to, a combination of silica and aluminum oxide. The protective coating 25 may be sputtered from two cathodes (eg, one cathode of silicon and one cathode of aluminum) or from a single cathode containing both silicon and aluminum. The silicon aluminum oxide protective coating 25 can be written as: Si . sub.xAI. sub.1-xO.sub.1.5+x/2, where x can vary from greater than 0 to less than 1. In a specific non-limiting embodiment of the present invention, the protective coating 25 may be a silicon aluminum oxide coating (Si.sub.xAI.sub.1 xO.sub.1.5+x/2), which has The thickness is in the range of 5 nm to 5000 nm, for example, 5 nm to 1000 nm, for example, 10 nm to 100 nm, for example, 10 nm to 50 nm, for example, 10 nm to 40 nm, for example, 20 nm to 30 nm, for example, 25 nm. Additionally, protective coating 25 may be of non-uniform thickness. The term "non-uniform thickness" means that the thickness of the protective coating 25 may vary over a given unit area, for example, the protective coating 25 may have high and low points or areas. In another non-limiting example, the protective coating 25 includes, but is not limited to, a silicon aluminum oxide coating or a mixture, composition, alloy or blend of silicon dioxide and aluminum oxide, for example, 85 wt. silicon oxide and 15 wt.% aluminum oxide, and having a thickness in the range of 10 nm to 500 nm, for example, 20 nm to 300 nm, for example, 50 nm to 300 nm, for example, 50 nm to 200 nm, for example, 50 nm to 150 nm, For example, 50 nm to 120 nm, for example, 75 nm to 120 nm, for example, 75 nm to 100 nm. In specific non-limiting embodiments, the protective coating 25 may have a thickness of at least 50 nm, such as at least 75 nm, such as at least 100 nm, such as at least 110 nm, such as at least 120 nm, such as at least 150 nm, such as at least 200nm.

[0047] In another non-limiting embodiment of the invention, the protective coating 25 includes, but is not limited to, silicon dioxide having a thickness in the range of 10 nm to 100 nm, for example, 10 nm to 80 nm, for example, 20 nm. to 80nm, for example, 30nm to 70nm, for example, 40nm to 60nm, for example, 50nm. In yet another non-limiting embodiment, the protective coating 25 includes, but is not limited to, silicon dioxide having a thickness in the range of 10 nm to 500 nm, such as 10 nm to 400 nm, such as 20 nm to 300 nm, such as 50 nm. to 200 nm, for example, 75 nm to 150 nm, for example, 75 nm to 120 nm.

[0048] In another non-limiting embodiment of the present invention, the protective coating 25 may comprise a multi-layer structure, for example, a first layer with at least one second layer formed over the first layer. In a specific non-limiting example, the first layer may include, but is not limited to, aluminum oxide or a mixture, composition, blend or alloy including aluminum oxide and silica. For example, the first layer may include, but is not limited to, silicon aluminum oxide deposited by sputtering a sputter target having greater than 5 wt.% aluminum, for example, greater than 10 wt.% aluminum, for example, Greater than 15wt.% aluminum, for example, greater than 30wt.% aluminum, for example, greater than 40wt.% aluminum, for example, 50wt.% to 60wt.% aluminum, for example, in the range of 70wt.% to 1000±.% aluminum and 40 wt.% to 0 wt.% silicon, for example, greater than 90 wt.% aluminum, for example, greater than 95 wt.% aluminum. In one non-limiting example, the first layer is all or substantially all aluminum oxide. In a non-limiting example, the first layer may have a thickness in the range of greater than 0 nm to 1 micron, for example, 5 nm to 10 nm, for example, 10 nm to 25 nm,

For example, 10nm to 15nm. The second layer may comprise silica or a mixture, composition, blend or alloy comprising silica and alumina. For example, the second layer may comprise silicon aluminum oxide deposited by sputtering a sputter target having greater than 40 wt.% silicon, for example, greater than 50 wt.% silicon, for example, greater than 60 wt.% silicon. % silicon, for example, greater than 70 wt.% silicon, for example, greater than 80 wt.% silicon, for example, in the range of 80 wt.% to 90 wt.% silicon and 10 wt.% to 20 wt.% aluminum, for example, 85wt.% silicon and 15wt.% aluminum. In a non-limiting embodiment, the second layer may have a thickness in the range of greater than 0 nm to 2 microns, such as 5 nm to 500 nm, such as 5 nm to 200 nm, such as 10 nm to 100 nm, such as 30 nm to 50 nm. , for example, 35nm to 40nm. In another non-limiting embodiment, the second layer may have a thickness in the range of greater than 0 nm to 1 micron, for example, 5 nm to 10 nm, for example, 10 nm to 25 nm, For example, 10nm to 15nm. In another non-limiting example, protective coating 25 may be a bilayer formed from a metal oxide containing layer (eg, a first layer containing silicon dioxide and/or aluminum oxide) Formed over another metal oxide-containing layer (eg, a second layer containing silica and/or aluminum oxide), wherein the two components of the dual-layer protective coating have different chemical compositions. The individual layers of multilayer protective coating 25 may be of any desired thickness. Non-limiting examples of suitable protective coatings 25 are described, for example, in U.S. Patent Serial Nos. 10/007,382; 10/133,805; 10/397,001; 10/422,094; 10/422,095; and 10/422,096, which are incorporated by reference. Here it is. [0049] Comparing the solar mirrors 7 and 26 of the present invention shown in Figures 3 and 4 respectively with the prior art solar mirror 5 shown in Figure 1, the differences that are of interest to this discussion are those of the prior art. The solar reflective coating 22 of the solar mirror 5 and the solar reflective coating 27 of the solar mirrors 7 and 26 of the present invention. More specifically, the substrate 12, base layer 24 and protective coating 25 of the prior art solar mirror 5 shown in Figure 1 and those of the solar mirrors 7 and 26 shown in Figures 3 and 4 respectively are similar. , if not exactly the same. Based on the above, it can be understood that the difference between the solar mirrors of the prior art and the solar mirrors of the present invention is the solar reflective coating. More specifically, the prior art solar reflective coating 22 is a single piece of solar reflective film 22, for example, a single silver (Ag) film, while the solar reflective coating 27 of the present invention includes solar reflective films separated by a separation layer 30 or Sublayer 28.

[0050] In the following discussion, reference is made to a non-limiting embodiment of the solar reflective coating 27 of the solar mirror 7 of the present invention (see Figure 3). However, this discussion also applies to the non-limiting embodiment of the solar reflective coating 27 of the solar mirror 26 of the present invention (see Figure 4) unless otherwise noted. Referring to Figures 3 and 4 as needed, 27 of the solar reflective coating of the present invention has a separation layer 30 between sub-layers 28a and 28b (see Figures 1 and 3) and between sub-layers 28a, 28b and 28c. Separating layers 30a and 30b (Fig. 4). Referring to Figure 4, surface 38 of spacer layer 30a may be in surface contact with adjacent surfaces 40 of sub-layers 28a or 28b and 28c, if present, or may be between surface 38 of spacer layer 30 and surfaces 40 of sub-layers 28a and 28b. There is a coating or film between them. Without limiting the scope of the invention, a non-limiting embodiment of the invention may contemplate a solar mirror 7 having a solar reflective coating 27 which 27 has two solar reflective sub-layers 28a and 28b (Fig. 3) separated by separation layers 30a (Fig. 3) and 30b (Fig. 4) and 28c (Fig. 4). In the practice of the present invention, the surface 40 of the sublayer 28a is in surface contact with or on the adjacent surface 38 of the separation layer 30, and the surface 40 of the sublayer 28b is in surface contact with the surface 38 of the separation layer 30. touch. Nonetheless, the present invention contemplates having additional coatings between the surfaces 40 of the sub-layers 28a and 28b of the solar reflective coating 27 and the surfaces 38 of the separation films 30a and 30b, respectively, as shown in FIG. 4 . This non-limiting embodiment of the invention is discussed in more detail below.

[0051] Practice of the present invention provides solar mirrors 7 and 26 that perform at elevated temperatures (e.g., 1180°F to 1200°F) in a temperature range suitable for high temperature heat treatment of glass. Optically more stable, the high-temperature heat treatment of the glass is, for example, thermal tempering, thermal strengthening or thermal bending of the glass. Additionally, solar reflective coating 27 can be used across the electromagnetic spectrum

A range of solar reflectance or solar transmittance is present in one or more regions of interest within (e.g., ultraviolet, visible, near-infrared, far-infrared, microwave, radio waves, etc.). For example, and without limitation, solar mirrors 7 and 26 (see Figures 3 and 4, respectively) may have a phase phase at a wavelength of 550 nm with one or more silver layers 28a, 28b (Figure 3) and 28c (Figure 4). At least 85% of the "visible light" reflectivity, such as at least 90%, such as at least 95% of the visible light reflection. [0052] Practice of the present invention mitigates the potential reduction in specular reflectivity of solar mirrors of the present invention, such as, but not limited to, solar mirrors 7 and 26 of FIGS. 26 is achieved by the amount of light reflected non-specularly (i.e. diffusely).

[0053] To illustrate the benefits of the present invention, the term "reflectivity including specular reflection" is adopted to mean that all specular and non-specular reflections (ie, diffusion) contribute to the reflectivity of the mirror. Typically, one seeks to minimize the amount of reflectance that excludes specular reflection (ie, diffusion) in order to maximize the specular reflectance of the mirror. Reflectance including specular reflection (which includes both specular and non-specular components) and its components excluding specular reflection can be measured using a commercially available spectrophotometer. The instrument used to do this is the Hunter Ultrascan PRO Spectrophotometer. The measured wavelength range is 350nm to 1000nm. The reflectance measured by the instrument on the glass side (i.e., the energy incident on the uncoated surface of the specimen) containing specular reflection is tabulated as the percentage of incident light that is specularly and non-specularly reflected Ground reflection versus wavelength. Similarly, the reflectance of the glass side excluding specular reflection measured by the instrument is tabulated as the percentage of incident light that is non-specularly reflected for the wavelength. The tabulated value of reflectance excluding specular reflections can be weighted by the solar irradiance function and numerically integrated to produce a single number which we refer to as "solar-weighted glass side reflectance excluding specular reflections" (this article is often cited Referred to as "SpEx WIRg"), where "WIR" means "weighted integrated reflectance (solar)", "SpEx" means "specular reflection excluded", and the "g" subscript indicates that light energy is incident on the glass side of the solar mirror 7 (i.e., an uncoated surface). For solar mirror applications, the surface or surfaces intended to receive the flux of reflected sunlight are called the "receivers." It is typically expected that specular reflections will be excluded Solar weighted glass side reflectance (SpEx WIRg) is minimized because any light energy reflected non-specularly from the solar mirror is not intercepted by the surface of the receiver, thereby constituting a loss of usable incident solar energy.

[0054] Two samples were prepared for comparison. Sample 1 is a prior art solar mirror shown in FIG. 5 and designated by numeral 70, and Sample 2 is a non-limiting example of an inventive solar mirror shown in FIG. 6 and designated by numeral 72. Example. Referring to Figure 5, the prior art solar mirror 70 (sample 1) includes:

1. A low-iron glass substrate 12 of the type sold by PPG Industries under the registered trademark SOLARPHIRE PV, having a nominal thickness of 3.2 millimeters ("mm");

2. A titanium dioxide (TiO2) base coating or base layer 74 having a thickness of 2 nm applied to the surface 16 of the glass substrate 12 by MSVD;

3. A solar reflective coating 22 of silver "Ag" having a thickness of 100 nm applied on the TiO2 basecoat film 74 by MSVD;

4. Ti(Ox) "base" or "barrier" or "barrier" layer 76, having a thickness of 2.5 nm, which is applied on the Ag film 22 by MSVD;

An oxide film of 5.52 wt.% Zn and 48 wt.% Sn ("Zn52-Sn48 oxide") topcoat 78 having a thickness of 140 nm; said oxide is also known as zinc stannate (Zn2SnO4), the top coating 78 is applied by MSVD on the Ti (Ox) "base" layer 76;

6. 850,% 51 and 150,% 41 oxide (085R115") aluminosilicate film 25, also known as permanent protective overcoat "PPO"), said film having 75nm thickness, which is applied on the "Zn52-Sn48 Oxide" film

78; ("Si85-Al15) aluminosilicate film 80 is applied over "Zn52-Sn48" topcoat film 78.

Referring to Figure 6, the solar mirror 72 (sample 2) of the present invention includes but is not limited to:

1. A low-iron glass substrate 12 of the type sold by PPG Industries under the registered trademark SOLARPHIRE PV, having a nominal thickness of 3.2 millimeters (mm);

2. Titanium dioxide (TiO2) undercoat film 74, having a thickness of 2 nanometers, applied to the glass substrate by MSVD

12 surface 16;

3. A sub-layer 28b of silver (Ag) film 27, having a thickness of 50 nm, which is applied on TiO2 film 74;

4. A first separation film 82 of Ti (Ox) having a thickness of 1.3 nm is applied on the sublayer 28b of the Ag (50 nm) film;

5. Zn2SnO4 second separation film 84, which has a thickness of 3.5nm on the separation Ti(Ox) film 82;

6. A silver (Ag) coated silver sub-layer 28a having a thickness of 50 nanometers (nm) is applied on the Zn2SnO4 second separation film 84;

7. Ti(Ox) "base" or "barrier" or "barrier" layer 76 having a thickness of 2.5 nm on Ag sub-layer 28a;

8. An oxide film of 52 wt.% Zn and 48 wt.% Sn "Zn52-Sn48 oxide") top coating 84 having a thickness of 140 nm; said oxide is also known as zinc stannate (Zn2SnO4), the topcoat 84 is applied by MSVD on the Ti (Ox) "base" layer 76;

9. 85wt.% Si and 15wt.% Al oxide "Si85-Al15 oxide") aluminum silicate film (PPO film)

25, which has a thickness of 75 nm, was applied on a Zn52 "Sn48" oxide film.

[0071] The Ti(Ox) film 76 used for solar mirrors 70 and 72 does not have a sub-number because titanium (Ti) is deposited as metallic titanium within the vacuum system and reacts with oxygen as the coating process continues. Have a chemical reaction. After the coating deposition is completed, the titanium (Ti) has been completely oxidized or almost completely oxidized. In the as-deposited state, the titanium is not fully oxidized, and any remaining TiOx metallic titanium is expected to be fully oxidized by subsequent high-temperature heat treatment (eg, thermal tempering, thermal strengthening, thermal bending).

[0072] Figure 7 is a graph illustrating approximate exclusion of specular reflection inferred using spectral R reflectance data from 350 nm to 1000 nm for an experimental solar mirror coating with and without the solar reflective coating 27 of the present invention. The solar reflective coating 27 of the present invention has separate layers 82 and 84 and sub-layers 28a and 28b. As can be appreciated from the above discussion, the coating stack 86 of the prior art solar mirror 70 and the coating stack 88 of the solar mirror 72 of the present invention are nominally identical except that the prior art solar mirror 70 utilizes a monolithic Ag membrane 22 and the solar mirror 72 of the present invention has in addition to the separation layers 82 and 84 in the coating stack 88 of the solar mirror 72 of the present invention. The left side of the graph shows the solar-weighted glass-side reflectance excluding specular reflections for both solar mirrors 70 and 72 in their as-deposited/non-heat-treated condition. The right side of the graph shows the solar-weighted glass side reflectance excluding specular reflections for both solar mirrors 70 and 72 after heat treatment to simulate thermal tempering. Considering the left side of the graph, the column on the far left is the data for the solar mirror 70 without the separator films 82 and 84 of the present invention, and the column immediately to the right is for the solar mirror with the separator films 82 and 84 of the present invention. 72 data. As can be seen from FIG. 7 , the solar-weighted glass side reflectance excluding specular reflections of both solar mirrors 70 and 72 is similar in both the as-deposited/non-thermal treated state. Considering the right side of the graph of Figure 7, the column on the far right is the data for the solar mirror 72 with the separation films 82 and 84 of the present invention, and the column immediately to the left is for the separation films 82 and 84 without the present invention. Data of solar mirror 70. As can be seen in Figure 8, after heat treatment to simulate thermal tempering, the solar weighted glass side reflectance of solar mirror 72 excluding specular reflection: (a) is the same as the SpEx WIRg of solar mirror 72 in its as-deposited state value class

similar, and (b) is lower than the value of SpEx WIRg of the solar mirror 70 after the solar mirror 70 has been subjected to heat treatment. As now understood, it is typically desirable to minimize SpEx WIRg for solar mirror applications.

[0073] The information of Figure 7 demonstrates that prior art solar mirrors and solar mirrors of the present invention have approximately the same level of reflectivity excluding specular reflection in their as-deposited state, but have significant differences when heat treated. Specifically, in the as-deposited/non-thermal treated state, the prior art coated substrate 12 (solar mirror 70) and the inventive coated substrate 12 (solar mirror 72) exhibit relatively Little haze/no haze in terms of reflectivity in the qualitative visual evaluation described when viewing solar mirrors 70 and 72 under incandescent floodlight illumination.

[0074] In addition, the "truncated" (350 nm to 1000 nm) inferred (solar) weighted specular excluded reflectance SpEx WIRg of the solar mirrors 70 and 72 in their as-deposited/non-thermal treated state is at It is similar at about 0.09% to 0.1%. After thermal treatment to simulate thermal tempering, the reflectance of the solar-weighted Rg excluding specular reflections of the prior art solar mirror 70 exhibits an approximately 3-fold increase to SpEx WIRg ~0.33%, while the reflectance of the inventive solar mirror 72 Shows only a slight increase to SpEx WIRg ~0.13% (see Figure 7).

[0075] FIG. 7 thus illustrates one benefit of using the spacer layer of the present invention, namely the ability to suppress an increase in the reflectance of the solar weighted Rg excluding specular reflection (SpEx WIRg) immediately following a high temperature thermal treatment. Here, we refer to the SpEx WIRg value measured immediately after/shortly after the high temperature thermal tempering heat treatment, without significant additional aging at room temperature or other temperatures, as in "time zero SpEx WIRg" . In addition, the terms "haze", "non-specular", "WIRg reflectance excluding specular reflection" and "SpEx WIRg" are sometimes used in conjunction.

[0076] Another feature of the solar reflective coatings of the present invention improves the thermal stability of heat treated mirrors aged at elevated temperatures. Experiments were performed at a temperature of 150°C over a period of greater than 10,000 hours to simulate the performance of a prior art solar mirror (Fig. 3) and a solar mirror of the present invention (Fig. 4). Referring to Figure 5, Sample 3 includes but is not limited to:

1. SOLARPHIRE PV glass substrate 12 having a nominal thickness of 3.2 mm;

2. TiO2 film 74, which has a thickness of 2 nm, is applied on the surface 16 of the substrate 12 facing away from incident light, such as but not limited to the sun 20 (see Figure 2);

3. A silver (Ag) film 22 having a thickness of 100 nanometers (nm) is applied to the film 74 of TiO2;

4. Inconel 600 corrosion resistance enhanced and UV absorbing film 90, which has a thickness of (30nm), is applied on

On the Ag silver film 22, Inconel 600 is shown in phantom and only in Figure 5;

5. Ti(Ox) "base" (or "barrier" or "barrier") layer 76 (~2.5 nm) on Inconel 600 layer 90; [0082] 6.52 wt.% Zn and a 48 wt. % Sn oxide film ("Zn52-Sn48 oxide") topcoat 78 having a thickness of (140nm) on the Ti(Ox) "base" layer 76; and

7. Permanent protective outer coating 25 having a thickness of (75nm) on the "Zn52-Sn48 oxide) topcoat 78.

[0084] Sample 4 is a solar mirror of the present invention and is similar to solar mirror 72 shown in FIG. 6 . More specifically, Sample 4 has:

1. SOLARPHIRE PV glass substrate 12 having a nominal thickness of 3.2 mm;

2. TiO2 film 74 having a thickness of 2 nm on the main surface 16 of the substrate 12 facing away from incident light, such as, but not limited to, the sun 20 (see Figure 3);

3. The first silver (Ag) sub-layer 28b of the silver (Ag) solar reflective coating 27 has a thickness of 50 nm on the TiO film 74;

4. A first Ti(Ox) separation film 82 having a thickness of about 1 nm on the Ag sublayer 28b having a thickness of 50 nm;

5. A second separation film comprising an oxide of 52 wt.% Zn and 48 wt.% Sn ("Zn52"Sn48 oxide")

CN 113683315 Β

84. The oxide is also called zinc stannate (Zn2SnO4); the second separation oxide film 84 of Zn52-Sn48 has a thickness of about 1 nm on the first Ti (Ox) separation film 82;

6. The second sub-layer Ag film 28a has a thickness of 50 nm on the first Ti (Ox) separation film 82;

7. Incosil 600 corrosion resistance enhanced and UV absorbing layer (not shown) having on second Ag sub-layer 28a

30nm thickness;

8. Ti(Ox) "base" (or "barrier" or "barrier") layer 76 having ~

2.5nm thickness;

9. An oxide film of 52 wt.% Zn and 48 wt.% Sn ("Zn52-Sn48 oxide") topcoat 78, which is

140nm thickness on Ti (Ox) "base" 76; and

10. Permanent Protective Overcoat (PPO) 25 having a thickness of 75 nm on Zn52-Sn48 oxide topcoat 78.

It should be noted that sample 4 has two separation films 82 and 84 between the two layers (see the two separation films shown in Figure 6), and the separation film 84 is titanium oxide or titanium suboxide film that functions similarly to the Ti(Ox) film 76 of the solar mirror 72 shown in Figure 6. The thickness of the separation layer is the total thickness of the separation film between layers of solar reflective coatings (such as, but not limited to, 28a and 28b). For example, but not limited to the present invention, the thickness of the separation layer between layers 28a and 28b including separation films 82 and 84 of Sample 4 is approximately 2 nm.

[0096] The use of enhanced corrosion resistance and UV absorbing layers, such as Incosil 600 film 90, is not limited to the invention and is an optional feature of the invention. The corrosion resistance enhancing and UV absorbing layer (hereinafter also referred to as the "corrosion resistant absorbing layer") provides various benefits, such as corrosion inhibition and UV shielding benefits. Furthermore, the corrosion-resistant absorber layer may provide a certain amount of reflection of electromagnetic energy that may allow for a thinner primary reflective layer such as, but not limited to, a silver film. The corrosion-resistant absorbent layer 90 may also provide mechanical and/or chemical protection to underlying coatings. The corrosion-resistant absorbent layer may be disposed beneath, beneath, or between one or more coatings. The layer is, for example, one or more solar reflective layers 27 or topcoat 78 (described above). Examples of suitable materials for use in the corrosion-resistant absorbent layer include, but are not limited to, elemental metals and alloys of two or more metallic elements that are of the periodic table of elements. Members of Groups 2 through 16, including but not limited to silver and silver-containing alloys, ferrous alloys and ferrous alloys (e.g., stainless steel), aluminum and aluminum-containing alloys, copper and copper-containing alloys, chromium and chromium-containing alloys, titanium and titanium-containing alloys , brass (for example, marine brass (alloys of Cu, Zn, and Sn), naval brass (Zn, Sn, and Alloys of Cu) and aluminum brass alloys (alloys of Cu, Zn and A1), diamond and alloys containing diamond (e.g. alloys of diamond and nickel), zinc and alloys containing zinc, tin and alloys containing tin, aluminum and alloys containing Copper alloys, molybdenum and molybdenum-containing alloys, bustard and molybdenum-containing alloys, aluminum and mixed gold-containing alloys, indium and indium-containing alloys, lead and lead-containing alloys, materials and material-containing alloys. Specific non-limiting examples include corrosion-resistant metals and metal alloys including, but not limited to, silver and silver-containing alloys (e.g., Nickel 200), Inco silver alloys (e.g., Inco silver 600 and Inco silver Alloy 625), stainless steels (e.g., Stainless Steel 304 and Stainless Steel 316), Monel® alloys (e.g., Monel 400), Hastelloy® alloys, diamond and diamond-containing alloys (e.g., Stellite® alloys), Inko alloys (e.g., Inco Alloy 0276 and Incoalloy 020), Incoloy® alloys (Incoloy 800 and Incoloy 825), copper and copper-containing alloys (e.g., brass, especially marine brass (approximately 59% copper, 40% zinc and 1% tin) and naval brass (approximately 69% copper , 30% zinc and 1% tin)), silicon and silicon-containing alloys, titanium and titanium-containing alloys, and aluminum and aluminum-containing alloys (for example, aluminum 6061). If present, the one or more anti-corrosion coatings 90 may have any desired thickness. In certain non-limiting embodiments, the corrosion-resistant absorber layer may have a thickness in a range, but not limited to, Inm to 500 nm, such as Inm to 400 nm, such as Inm to 300 nm, such as Inm To 200nm, for example, Inm to 100nm, for example to 100nm, for example, 20nm to 100nm, for example, 30nm to 100nm, for example, 40nm to 100nm, for example, 50nm to 100nm, for example, 20nm to

40nm, for example, 30nm to 40nm, for example, 30nm to 35nm.

[0097] Corrosion-resistant absorbent layers are well known in the art and further discussion is deemed unnecessary. A more detailed discussion of corrosion-resistant absorbent layers may be found at column 9, line 45 through column 11, line 2 of U.S. Patent No. 8445,098, the entire contents of which is hereby incorporated by reference.

Figure 8 shows samples 3a and 4a when the coating is in a deposited, non-heated condition and when the coating is in a deposited, heated condition, i.e. maintained at 150 degrees C (heated). Plot of approximate solar weighted Rg reflectance (SpEx WIRg) excluding specular reflection for samples 3b and 4b. For clarity, Sample 3a is designed to be heat treated at time zero to simulate a prior art solar mirror after thermal tempering (hereinafter referred to as "heated"); Sample 3b is designed to be in its as-deposited state (also referred to as "heated"). referred to as a prior art solar mirror in its as-deposited state ("unheated" and/or "deposited state"); Sample 4a is designed to be a solar mirror of the present invention in its as-deposited state ("unheated and/or deposited state") mirror, and Sample 4b was designed to be a solar mirror of the invention after heat treatment at time zero to simulate thermal tempering (also known as "heated").

[0099] In their as-deposited (i.e., non-heat treated) state, Sample 3a and Sample 4a exhibit relatively low SpEx WIRg values as a function of aging time. In contrast, after heat treatment at time zero to simulate thermal tempering, Sample 3b (prior art) exhibits a rapid increase in SpEx WIRg at a relatively short (e.g., 10 hours to 100 hours) aging time and in The increase becomes more gradual at longer aging times, as shown in Figure 8 by curve 3b. In contrast, heat-treated sample 4b exhibits a lower SpEx WIRg than heat-treated sample 3b at aging times greater than approximately 10 hours, and only gradually increases with aging time, thereby implying that heat-treated sample 4b has a lower SpEx WIRg than heat-treated sample 3b. Sample 3b is inherently more thermally stable. Furthermore, it is noted that throughout most of the aging of the sample at 150°C, the SpEx WIRg value of heat treated sample 4b is similar to the SpEx WIRg value of samples 3a and 4a in their as-deposited state.

[0100] From the above discussion, the benefits and limitations of the solar reflective coating 27 of the present invention including two or more layers 28a and 28b can now be understood. In a preferred practice of the invention, separation film 30 (Fig. 3) and separation films 82 and 84 (Fig. 6) are less than 5% of the thickness of the solar reflective film. It is assumed that the separation film is a material that prevents or destroys the crystal growth of silver; smaller silver crystallites are expected to scatter light less strongly than larger silver crystallites. Thus, a coating with a solar reflective coating containing smaller silver crystallites is expected to exhibit lower haze and lower excluded specular reflected solar energy than a coating with a solar reflective coating containing larger silver crystallites. Weighted glass side reflectance (SpEx WIRg). Materials that may be used for the separation membrane may include, but are not limited to, oxides of metals, such as, but not limited to, oxides of Ti, Sn, Zn, and combinations thereof. However, if desired, a metal such as titanium can be used as the spacer layer, but such metallic materials will tend to be absorptive and therefore reduce the overall level of solar reflectivity.

[0101] In this embodiment of the invention, the solar reflective coating 27 may be any material that reflects solar energy, such as, but not limited to, gold, silver, aluminum, copper, platinum, osmium, iridium, tungsten, alumina, palladium, or other Precious metals and their compositions, alloys, mixtures and/or blends. Solar reflective coating 27 may have two films 28a and 28b of the same material, for example, silver films 28a and 28b, or may have two films 28a and 28b of different materials, for example, a film or sub-layer 28a of silver and gold. Film or sublayer 28b. The solar reflective layer may include two films with the same thickness or two films with different thicknesses. Furthermore, the solar reflective coating 27 may have more than two films. For example, the solar reflective coating may include three, four, five or more films between adjacent solar reflective films. Has one or more separate layers.

[0102] The present invention is not limited to the thickness of the one or more spacer layers, however, in the practice of the present invention, spacer layer 30 has a thickness sufficient to inhibit thermally excited crystal growth of layers such as, but not limited to, layer 28a. and 28b, for example, such thermally induced crystal growth may occur when the coated article is used at ambient or elevated temperatures. By way of illustration and without limitation, a prior art solar reflective coating 22 (see Figure 1) has a thickness of 100 nm

The silver coating, and may include silver crystallites ranging in size from greater than zero up to the full thickness of solar reflective layer 22 (100 nm in this example). In contrast, the solar reflective coating 27 of the present invention (see Figure 3) has a solar reflective coating comprising two layers, such as but not limited to the present invention, each having a silver layer 28a with a thickness of 50 nm and 28b. Thus, layer 28a may comprise silver crystallites in a range from just greater than zero up to the full thickness of silver layer 28a (which is only 50 nm in this example). Similarly, layer 28b may include silver crystallites in a range from just greater than zero up to the full thickness of silver layer 28b (only 50 nm in this example). The thickness of the separation film 30 is selected to cooperate with the films, coatings and layers of the coating stack to provide the optical properties of the solar mirror (eg, spectral reflectance). In a non-limiting embodiment of the present invention, the separation film 30 has a thickness in the range of greater than 0 nm to 5 nm.

[0103] In addition, the present invention is not limited to the optical properties of the solar mirror, however, in a preferred practice of the present invention, solar energy passes through the substrate 12, through the films of the coating stack to reflect solar energy from the solar reflective film 27 to the selected A certain position to act on the reflected solar energy.

[0104] In a specific embodiment, layers 28a and 28b of reflective coating 27 are silver films each having a thickness in the range of 1 nm to 150 nm, for example, 2 nm to 125 nm. , such as 25nm to 150nm, such as 50nm to 100nm, such as 100nm to 200nm, such as 100nm to 150nm, such as 110nm to 140nm, such as 120nm to such as 140nm, such as 128nm to 132nm. In another specific embodiment, the reflective coating 27 includes metallic silver having a thickness in the range of 1 nm to 500 nm, such as 50 nm to 500 nm, such as 50 nm to 300 nm, such as 50 nm to 200 nm. , for example 50nm to 150nm, for example 70nm to 150nm, for example 90nm to 120nm, for example 90nm to 130nm, for example 90nm to 100nm, for example 90nm to 95nm. In a preferred practice of the invention, silver layers 28a and 28b have a thickness in the range of 25 nm to 75 nm, with the range preferably being 40 nm to 60 nm, for example, 50 nm.

In a non-limiting embodiment of the present invention, the thickness of the layers 28a and 28b of the solar reflective film 27 of FIG. 3, such as but not limited to the silver film having the separation layer 30, is designed to have a desired design thickness. The solar mirror of a single solar reflective film is determined as is currently done in the art. The calculated thickness of the solar reflective layer is divided by the number of solar reflective films to be used. For example, for two solar reflective films, the thickness of the reflective layer is divided by 2. For three solar reflective films, the thickness of the reflective layer is divided by Divide by 3, and so on.

[0106] With continued reference to Figure 3, the surface 16 of the substrate 12 designated as facing away from the sun 20 (see Figure 2) is coated with TiO₂Layer 24, a first sub-layer 28b of silver reflective coating 27 is applied on the TiO₂Over films 24 (Fig. 3), 74 (Fig. 6), a separator film 30 is applied over a layer 28b of silver, a layer 28a of coating 27 is applied over the separator layer 30, and a protective coating 25 is applied above layer 28a. As can be appreciated, the invention is not limited to the coatings discussed herein, and any combination of coatings may be used in the practice of the invention, such as, but not limited to, the coatings for solar mirrors disclosed in Pat '098.

[0107] The equipment used to coat the substrate 12 is not limited to the present invention and may include any type of equipment known in the art to apply coatings and films to the substrate and to each other, such as, but not limited to MSVD and coating vapor deposition.

[0108] From the above discussion, the benefits and limitations of the solar reflective coating of the present invention can now be understood. More specifically, the separation film is a material that can be deposited over a layer of solar reflective coating, including the solar reflective film, eg, layers 28a and 28b, to inhibit the growth of silver crystallites. In the practice of the present invention, the thickness of the separation layer 30 is in the range of 0.005% to 10% of the thickness of the solar reflective film 27, preferably, in the range of 0.05% to 7.5% of the thickness of the solar reflective film 27, and more Preferably, it is in the range of 0.5% to 5% of the thickness of the solar reflective film 27, and most preferably in the range of 1.0% to 4% of the thickness of the solar reflective film 27, which includes the sub-layers 28a and 28b. Materials that may be used include, but are not limited to, oxides of metals, such as, but are not limited to, oxides of Ti, Sn, Zn, and combinations thereof. However, if desired, a metal such as titanium can be used as the separation film, but this metal material

CN 113683315 Β

The material will tend to absorb solar energy that passes through the substrate and coated base paper, and therefore can reduce the overall level of solar reflectance.

[0109] Encapsulated coating stack for solar mirrors to increase useful life of solar mirrors

In the above discussion of solar mirrors, the solar mirrors are such as but not limited to solar mirrors 5 (Fig. 1), solar mirrors 7 (Fig. 3), solar mirrors 26 (Fig. 4), solar mirrors 70 (Fig. 5) and solar mirrors 72 (Fig. 6), reference permanent protective outer coating ("PP0") 25. PPO protects coating stacks 35, 32, 34, 86, and 88 between surface 16 of substrate 12 and the corresponding PPO layer of coating stack 32 (Figs. 1, 2, 4, 5, and 6, respectively) ) membrane. For example, but not limited to the present invention, the pp0 coating 25 of the solar mirror 26 of Figure 4 protects the surface 89 of the sub-layer 28a of the solar reflective coating 28 from chemical and mechanical damage during handling and transportation of the solar mirror.

[0111] Shown in Figures 9 and 10, respectively, are non-limiting embodiments of solar mirrors 100 and 102 of the present invention having an outer envelope 104 and a pPO coating 25 of the present invention. Generally, the solar mirror 100 shown in FIG. 9 includes a coating stack 35 on the inner surface 16 of the substrate 12 and an envelope 104 covering the outer wall 106 and top surface 108 of the coating stack 35 . Generally, the solar mirror 102 shown in FIG. 10 includes a coating stack 32 applied to the inner surface 16 of the substrate 12 and an envelope 104 covering the outer wall 110 and top surface 112 of the coating stack 32 .

[0112] As understood by those skilled in the art, solar reflective coatings, especially those employing one or more silver layers, are useful in environments where solar mirrors are used, such as in outdoor environments where solar mirrors are used. environments and are susceptible to mechanical damage and/or environmental degradation/corrosion. In the practice of the present invention, the encapsulant for the second surface solar mirror is transparent because the source of solar energy faces the surface 16 of the substrate 12, while the first surface solar reflective solar mirror has a surface facing the solar energy. Surface 14 of the source substrate. In other words, the envelope 104 covering the coating stacks 32 and 35 of the first surface mirror is transparent because the envelope 104 is within the optical path of incident and reflected light. The envelope 104 covering the coating stacks 32 and 35 of the second surface mirror is opaque because the envelope 104 is not in the optical path of the incident and reflected light. The primary durability screening for solar mirrors with encapsulation over the coating stack is generally accepted as the copper salt accelerated acetic salt spray test ("CASS"). The CASS test is well known in the art and further discussion of the CASS test is not deemed necessary.

[0113] In addition to the encapsulation that failed the CASS test, another drawback to currently available encapsulation is the use of lead (Pb") based corrosion inhibitors in order to adequately protect the underlying Ag-based reflective coating from due to corrosion/degradation and loss of reflectivity. In recent years, since the deployment of "high-Pb" encapsulants, the emerging concentrated solar power (CSP) industry has favored having reduced amounts of Pb and preferably essentially no lead (W ) encapsulation, for example, consider the disclosure in U.S. Patent No. 8445,098 (which U.S. Patent is incorporated herein by reference). Continuing to refer to Figures 9 and 10 as needed, in one non-limiting embodiment of the present invention, the encapsulant 104 completely covers the top surfaces 108 and 112 of the coating stacks 32 and 35 of the solar mirrors 102 and 100, respectively. and extends toward surface 14 of substrate 12 across surface 16 of substrate 12 and is secured to a peripheral side or edge 114 of substrate 12 as shown in FIGS. 9 and 10 . In one non-limiting embodiment of the invention, the top surfaces 108 and 112 of the coating stacks 35 and 32 may be completely covered by the encapsulant 104, as shown in Figures 9 and 10, or the coating stack 35 The marginal edge portions of the outer surfaces 108 and 112 of the and 32 may be covered by an enclosure, as will be discussed below. By way of interest and without limiting the present invention, experimental prior art encapsulations are available from the Finzi Group (headquartered in Tribbiano, Italy) and sold under the registered trademark SolaHux®.

[0114] With continued reference to Figures 9 and 10, the encapsulation 104 of the present invention includes a base or base layer 120 that is applied over and/or coated over the outer wall 116 and top surface 108 of the coating stack 35. A topcoat 122 is applied over the bottom layer 120 of the enclosure 104 over the outer wall 110 and top surface 112 of the layer stack 32 and over the peripheral side 114 of the substrate 12 . in this hair

In one non-limiting example, the encapsulation includes a base layer 120 having the ingredients and amounts listed in Table 1, and a top coating 122 having the ingredients and amounts listed in Table 2. Ingredients and amounts listed.

Suitable methods of applying the encapsulant include, but are not limited to: (1) curtain coating, (2) spray coating, (3) flow coating, (4) draw-down coating, and (5) electrolysis Curtain coating, as disclosed, for example, but not limited to, U.S. Patent No. 8557,099 (which patent is incorporated herein by reference). In one non-limiting embodiment of the present invention, the preferred method of applying encapsulant 104 is curtain coating. Base coating 120 and top coating 122 of encapsulant 104 are applied such that their geometric thicknesses in their cured state (i.e., after thermal curing of the encapsulant) are approximately 1 mil (0.001 inch = 25.4 mm). However, a certain range of thicknesses for each base coating 120 and top coating 122 is acceptable, such as, but not limited to, a range of 0.9 mils to 1.5 mils.

[0116] Prior to applying encapsulant 104 to the coating stack, such as, but not limited to, coating stack 35 and/or or 32, the coating stack is pre-treated to remove any sharp (i.e., "raw" or "cut") edges of the coating stack, preferably using an abrasive belt or wheel such as The grinding media is passivated or ground. This practice is called "edge-stitching" or simply "stitching." The sharp edges of the reflection-coated substrate are edge-stitched before the encapsulation is applied, ultimately resulting in the finished mirror with the so-called "SP" (stitch-then-paint). The edge-stitching is believed to facilitate the bottom layer 120 of the envelope 104 to "wrap" to the peripheral side 114 of the substrate 12 to a certain extent, thereby limiting the direct exposure of the "sidewalls" of the reflective coating to potential corrosion. Potentially corrosive environmental factors may chemically react with or otherwise degrade the reflective coating 22 and/or one or more layers including Ag or solar reflective layers. The practice of edge-stitching is also considered the removal of some or all of the reflective coating from the extreme edges/peripheries of the coated surface of a substrate on a microscopic scale. This concept is called "micro-edge-deletion" or "micro-deletion". A similar practice is sometimes followed to "edge-remove" Ag-based coatings from the perimeter of coated glass substrates (eg, Ag-based low emissivity and/or solar control coatings). This microscopic edge-removal process involves removing microscopic widths (typically a few millimeters) of coating from the perimeter of the coated substrate. This microscopic edge-deletion helps protect the coating from direct exposure to environmental factors that may corrode or otherwise degrade Ag-based coating 27 (see Figure 10) and coating 22 (see Figure 9). After the edge-stitching step, the reflective coated substrate is thoroughly cleaned and dried in any convenient manner, such as using a flat glass cleaner.

[0117] Before applying the encapsulant 104, a pre-treatment is preferably applied to the outer wall 110 and the top surface 108 of the coating stack 32 and the outer wall 106 and the top surface 108 of the coating stack 35 of the solar mirrors 102 and 100, respectively, in order to Promotes adhesion of the encapsulant to the outer surface of the coating stack. Preferred pretreatments include silane-based chemicals; one suitable composition is 0.15 wt. % gamma-aminopropyltriethoxysilane in deionized (DI) water. The pretreatment chemicals are sprayed onto the outer surfaces or walls 106 and 110 of the coating stacks 25 and 27, the top surfaces 108 and 112, and the exposed surfaces of the substrate 12 and allowed to remain on the surfaces for a dwell time of approximately 30 seconds and then Rinse thoroughly by flushing the surface with deionized water. Immediately following the rinse process, remaining rinse water is sheeted off from the outer surfaces 106 and 110, the top surfaces 108 and 112 of the coating stacks 32 and 35, respectively, and the exposed surface of the substrate 12. Prior to applying the base coating or base coat 120 of the encapsulant 104, the pretreated coating stacks, such as coating stacks 32 and 35, and the substrate 12 are preheated to approximately 150°F (66°C).

A sufficient amount of the base coating 120 chemicals are applied to the outer wall or surface 106 and top surface 108 of the coating stack 35 and to the outer wall or surface 110 and top surface 112 of the coating stack 32 to achieve the desired effect on the finished product. A base coat dry film thickness (DFT) of approximately 1.1 mils (27.94 microns) was achieved. Process parameters for the base coating application process (e.g., width of the aperture of the curtain coater, conveyor line speed of the substrate through the paint curtain, etc.) are typically adjusted empirically to obtain the desired base coating. layer DFT. Immediately following the application of the base coat chemistry, the substrate travels through a "flash section" in which the application continues

Heating is applied to enable solvent to evaporate from the applied liquid-based coating 120 of the encapsulation 104 . A suitable temperature for this "flash section" is about 150°F (66°C). The application of heat in this flash stage also preheats the substrate 12 to prepare it to receive the base coating 120 of the encapsulant 104 . A minimum substrate surface temperature of approximately 120°F (49°C) immediately prior to application of the base coating of the encapsulant is recommended, but not limited to this invention.

[0119] Immediately after removal from the "flash section" for topcoat 122, the coated substrate encapsulation 104 is cured in a suitable ventilated oven, which is designed to Designed for curing polymer coatings/coatings over larger areas of substrates. The typical recommended residence time in the furnace ("ride time") for any given encapsulated substrate is 251 seconds. The recommended exit temperature for the encapsulated surface of the substrate immediately upon exiting the curing oven is approximately 280°F (138°C). After exiting the furnace, the encapsulated reflectively coated solar mirror cools down. Referring to Figures 9 and 10 and without limiting the present invention, the encapsulated reflective coated glass substrate is a finished solar mirror having, but not limited to, the present invention (1) a substrate (eg, glass substrate 12); (2) on the substrate Ag-based double layers 28a and 28b deposited by MSVD on a main surface of the reflective substrate 27, such as but not limited to the surface 16 of the substrate 12; (3) on the Ag-based sublayer Separator layer 30 on 28b; (4) double layer 28a on top of separator film 30; and (5) application to outer wall 106 and top surface 108 of coating stack 35 and MSVD deposited reflective coating outer surface 106 and top surface 108 on or over the base coating 120 of the encapsulant 104 and a top layer 122 applied over the base coating 120 .

[0120] Optionally, the underside 14 of the substrate 12 of the finished solar mirrors 100 and 102 may be cleaned using an acid etching process and rinsed/dried prior to unloading. The purpose of this underside acid etching is to remove any contaminants, especially silver-based contaminants, that may absorb light and thus negatively affect the overall reflectivity of the finished mirror. Ferric chloride (FeCl) in deionized water₃) solution is a suitable underside etchant/cleaner.

[0121] After the entire mirror is exposed to the etchant, the entire mirror is thoroughly rinsed with water to remove all traces of the etchant from the finished mirror, and dried using an air knife or similar device.

[0122] The finished solar mirror of the present invention encapsulated in the manner described above with encapsulant 104 exhibits acceptable adhesion to glass substrate 12 as determined using the ASTM D3359 Crosshatch Adhesion Test; Typical is a crosshatch adhesion rating of "4B" or better. Similarly, mirrors exhibit acceptable levels of cure as determined using the ASTM D5402 solvent rub test; typically 200 double rubs with a xylene-soaked cloth or more without visible degradation of the encapsulant many.

[0123] Unless otherwise noted, in the following discussion of non-limiting examples of the present invention, the above is practiced for preparing coating stacks 32 and 35 for application of the encapsulant 104 prior to application of the encapsulant. method.

[0124] The discussion now relates to a non-limiting embodiment of a solar mirror of the present invention having an encapsulated coated stack such as, but not limited to, coating stack 35 (Fig. 9) and coating stack 32 (Fig. 10). These non-limiting embodiments of the present invention relate to solar mirrors, such as, but not limited to, highly reflective solar mirrors, such as, but not limited to, solar mirrors having coated solar reflective sublayers 28a and 28b separated by a separation medium 30 (Fig. 9) and a solar mirror with a solar reflective coating, such as a solar reflective coating 22 of the type shown and discussed with respect to FIG. 9 . Silver reflective coatings 27 and 22 are highly reflective of solar radiation and are commonly used in concentrated solar thermal power (CSTP) and concentrated photovoltaic (CPV) applications. CSTP/CPV technology is sometimes more commonly referred to as concentrated solar power (CSP) technology. However, it should be understood that the solar mirrors of the present invention may be used in other applications, which generally include but are not limited to display applications, projection applications, lighting applications, entertainment applications, laser applications, directed energy weapon applications, optical applications or employed in Any application of highly reflective articles, or any sub-devices thereof, across the solar wavelength spectrum, or for any application in which the invention described therein exhibits suitable optical properties/performance or other suitable characteristics. As used in this article, height

Reflective solar films, such as but not limited to silver reflective solar films, have solar reflection in the range of 85% to 95%. With continued reference to FIGS. 9 and 10 as appropriate, the encapsulation 104 of the solar mirror 100 (FIG. 9) and/or the solar mirror 102 (FIG. 10) includes, but is not limited to, polyester melamine having a bottom or base layer 120 and/or a top layer 122. Selected ones of layers 120 and 122 have metal resistance enhancing films or particles of Inconel 600, zinc, aluminum, copper, magnesium, or mixtures, alloys or combinations of two or more of the foregoing. In the preferred practice of the invention, the metal of choice is zinc ("Zn") because, in addition to being a resistance-enhancing metal, Zn is a highly conductive metal and can be used in electrodeposition coatings.

[0125] The present invention is not limited to zinc forms, and the present invention contemplates Zn in the form of flakes, powders, and coated MSVD coated films. In the preferred practice of the invention, the Zn is in the form of flakes. Because the encapsulant-coated samples were made with Zn flakes, Zn powder, and Zn film, and Zn flakes are better performers for the electrodeposition of encapsulants, ZnoZn flakes in the form of flakes were chosen by number 124 and is shown only in dashed lines in Figure 11 .

[0126] In the practice of the present invention, the Zn flakes are mixed with the chemistry of the bottom layer 120 and the top layer 122 of the encapsulant 104 when used as a resistance-enhancing metal or sacrificial cathodic protection. When Zn flakes are used to provide resistance-enhancing metal or sacrificial cathodic protection and serve as cathodes for electrode deposition, the Zn flakes are mixed with the chemistry of the base layer 120 of the encapsulant 104 . In the following discussion, Zn flakes are used to provide resistance-enhanced metal or sacrificial cathodic protection and serve as cathodes for electrodeposition; Zn flakes 124 are formulated in a moisture stable binder, polyester melamine, to accompany curtain coatings. cloth application. For a more detailed discussion of Zn flakes in polyester melamine, reference is made to U.S. Published Patent Application No. 2013/0003206 (Publication '206). U.S. Published Patent Application No. 2013/0003206 is incorporated herein by reference.

[0127] In the practice of this embodiment of the invention, a Zn-rich polyester melamine-based topcoat 122 of the encapsulant 104 (Figs. 9 and 10) is used. For certain end-use applications, it may be desirable that the finished solar mirror be subjected to some type of high temperature processing, such as thermal tempering, thermal strengthening, thermal bending, etc. In that event, the reflectively coated substrate is preferably subjected to such high temperature treatment before the encapsulant 104 is applied. Although the coating stack 35 of the solar mirror 100 and the coating stack 32 of the solar mirror 102 may survive high temperature processing, it is anticipated that the polymer-based encapsulant 104 over the coating stacks 35 and/or 32 will not. This kind of processing.

[0128] Shown in FIG. 11 is a non-limiting embodiment of a solar mirror 130. Solar mirror 130 is solar mirror 70 or 72 with enclosure 104 . Unless otherwise noted, the following discussion applies to solar mirror 70 or 72. Continuing with reference to Figure 11, the encapsulation 104 of the present invention includes, but is not limited to, (1) a polyester melamine-based coating 120 impregnated with a metallic corrosion inhibiting pigment 124 (eg, metallic Zn flakes 124) and (2) metal-free Polyester melamine-based topcoat 122 of corrosion inhibiting pigment (eg, metallic Zn flakes 124). Such encapsulation 104 is also referred to herein as a "PEM encapsulation." Solar mirror 130 includes, but is not limited to, MSVD coating stacks 32 and/or 35 having coatings 74, 76, 78, and 25 as described in U.S. Patent No. 6,916,542 (hereinafter also referred to as "Patent '542" ) PPO coating of the type disclosed in 25. The '542 patent is hereby incorporated by reference. In this discussion of non-limiting embodiments of the invention, base coating 120 of PEM encapsulation 104 is applied between layer 25 of PPO (top surfaces 108 and/or 112 of coating stacks 32 and 35 , respectively) on the outer walls 106 and 110 of the coating stacks 32 and 35.

As understood by those skilled in the art, the PPO coating or MSVD film 25 or 80 is non-conductive and the Zn flakes 124 in the base layer 120 of the PEM encapsulant 104 have a dual function, i.e., the PEM encapsulate Zn flakes 124 in base coating 120 of 104 slow corrosion of Ag reflective coatings 22 and 27 by absorbing moisture. More specifically, the Zn flakes 124 absorb moisture passing through the top coating or layer 122 of the PEM envelope 104 into the base coating 120 of the PEM envelope 104 and corrode, after which the moisture moves through the PEM envelope 104 The base coating 122 and erodes the coating stack 32 and/or 35, particularly the Ag reflective coating 28 and/or 220. The second function of the base coating 122 of the PEM envelope 104 is when the electrocoating is applied to the PEM envelope. The base of seal 104

Above layer 120 a cathode is provided. The present invention is not limited to the manner in which the electrocoated top coat 122 is applied, and the top coat 122 of the PEM encapsulant 104 may be applied in the manner disclosed in U.S. Patent Application Publication No. 2013/0003206 (Publication '206"). Publication '206 is incorporated herein by reference.

[0130] A detailed discussion of PEM encapsulation is provided in Publication '206 and U.S. Patent No. 8,557,099 ("Patent '099"). The entire contents of the '206 publication and the '099 patent are incorporated herein by reference.

[0131] Shown in Tables 1 and 2 are formulations of base coat 120 (Table 1) and top coat 122 (Table 2) used in the practice of the present invention as shown in Figure 10 in accordance with the present invention. Encapsulant 104 is shown curtain coated on coating stack 32.

[0132] Table 1 below shows the main ingredients and the general function of each ingredient:

Table 1

<td>Ingredients</td><td>Weight / grams)</td>

<td>Polyester resin</td><td>57.74</td>

<td>Phosphated epoxy resin</td><td>4.41</td>

<td>Melamine</td><td>45.80</td>

<td>Solvent </td><td>127.9</td>

<td>Flow aid</td><td>2.17</td>

<td>Anti-settling agent(6)</td><td>23.18</td>

<td>Catalyst</td><td>1.41</td>

<td>Zinc flake</td><td>381.53</td>

<td>Silane A-187</td><td>5.00</td>

(1) The polyester resin is POLYMAC HS 57-5776 from Momentive Specialty Chemi cals, which has a solid weight of 85 weight percent based on total weight, a hydroxyl value of 178 (based on solid weight), and a hydroxyl equivalent weight of 315 (based on solid weight). weight of solids) and an acid number of 10 (based on weight of solids).

(2) Phosphated epoxy resin is commercially available from PPG Industries under the trade name HEQ-9346.

(3) Trimeric ratamine is RESIMENE [718], which is available on the market from INEOS Melamines.

(4) The solvent consisted in each case of 20.4% by weight of SOLVESSO 100 (from the company Exxon Mobil), 25.8% by weight of butyl CELLOSOLVE and 53.8% by weight of butanol, based on the total weight of the solvent.

(5) Flow aid consists of the following: AL-61-1477, polyolefin oil (18.4% by weight, commercially available from Shamrock Technologies); AWY-3046, silicone fluid (by weight 27.6% by weight, commercially available from Momentive Performance Materials, Inc.); and RCH-8794, polybutyl acrylate (54.0% by weight, commercially available from E.I. du Pont de Nemours and Company) ), the percentage weight is in each case based on the total weight of the flow aid.

(6) Anti-settling agent consists of: 53.2 weight percent of 8EMOHRSD-2 clay material (available on the market from

Elemintis Specialties), 30.6% by weight of AEROSIL 200 fused silica (commercially available from Evonik Industries) and 4.1% by weight of BYK 410 rheology additive | (commercially available from BYK

Purchased from USA Company), each percentage weight is based on the total weight.

(7) The catalyst is NACURE 2 5 0 0 amine neutralized p-toluenesulfonic acid, which is commercially available from King

Industries bought it.

(8) Zinc sheet 124 has the trade name Z45, which is commercially available from Purity Zinc Metals, and has a length to thickness ratio of 20:1.

The ingredients of Table 1 were mixed using a cowles blade for at least 30 minutes until a Hegman rating of 6.5 (on a scale of 1 to 8) was achieved. The solvent (1:1 mixture by weight of SOLVESSO 100 and butyl CELLOSOLVE) is mixed with the abrasive paste to form a sacrificial cathode coating composition with a viscosity suitable for spray application.

[0145] The sacrificial cathode coating composition was curtain coated over a reflective glass substrate and allowed to flash off at ambient room temperature to remove the solvent. The applied sacrificial cathode coating has a thickness in the range of 1.0 mils to 1.2 mils.

[0146] The polyester melamine coating composition (lead-free) for use as the outer organic polymer coating topcoat 122 of the encapsulant 104 was prepared as shown in Table 2 below:

<td>[0147]</td><td colspan="2">Table 2</td>

<td rowspan="8">[0148]</td><td>Ingredients</td><td>Weight / grams)</td>

<td>Polyester resin</td><td>120.90</td>

<td>Phosphated epoxy resin</td><td>7.97</td>

<td>Melamine</td><td>18.19</td>

<td>Solvent </td><td>38.1</td>

<td>Flow aid</td><td>2.17</td>

<td>Catalyst</td><td>0.47</td>

<td>TiO₂</td><td>89.8</td>

(9) The polyester resin is commercially available from PPG Industries under the trade name HP 73-5480 SP3 and has a solid weight of 65 weight percent based on the total weight, a hydroxyl value (based on solid weight) of 89.2, 628.9 of hydroxyl equivalent weight (based on weight of solids) and an acid number (based on weight of solids) of 3.8.

The ingredients of Table 2 were mixed using a cowles blade for at least 30 minutes until a Hegman rating of 6.5 (on a scale of 1 to 8) was achieved. The solvent (a 1:1 mixture by weight of SOLVESSO 100 and butyl CELLOSOLVE) is mixed with the abrasive paste to form an outer organic polymer coating composition with a viscosity suitable for spray application.

[0151] The lead-free external organic polymer topcoat 122 prepared from the abrasive paste of Table 1 was curtain coated over the previously applied sacrificial cathode coating using a mini curtain coater, i.e., curtain coated Coated on the base coating 120. The sacrificial cathode coating (i.e., base coating 122) and outer organic polymer coating (i.e., top coating 122) are cured together in a Hedinair oven (not shown) at a temperature of 320°F for 4 minutes and 11 seconds . The outer organic polymer coating, topcoat 122, has a thickness of 1 mil (25 microns).

[0152] In one non-limiting embodiment of the invention, the coating process involves cleaning a glass substrate 12 having the dimensions of a 6 inch Pretreat the glass substrate with A1100 silane at a ratio of 25% isopropyl alcohol and 75% water). The glass substrate 12 is then preheated to 150F for 1 minute before applying the base coating 120 (see Figure 11). The glass substrate 120 is then flashed at 150F for approximately 1 minute to remove some of the solvent in the applied base coating 120 and top coating 122 . The composition was then cured together in a Hedinair oven for 3 minutes and 20 seconds. Confirm cure by using &gt;100 double MEK wipes. The sample is then cut to expose the edges and tested in a screening test such as CASS.

CN 113683315 Β

[0153] The base layer 120 and the top layer 122 of the PEM encapsulant 104 are applied on top of the MSVD-deposited solar reflective coating stack 32 or 35 shown in Figure 11. Suitable methods of applying the encapsulant 104 include, but are not limited to: (1) curtain coating, (2) spray coating, (3) flow coating, (4) draw coating, and (5) electric curtain coating. The preferred application method is curtain coating.

[0154] The base coating 120 and top coating 122 of the PEM encapsulation 104 are applied such that their geometric thicknesses in their cured state (i.e., after thermal curing of the encapsulation) are each approximately 1 mil (0.001 inches = 25.4 microns). However, in the practice of this invention, it is contemplated that certain thickness ranges for each layer are acceptable, such as, but not limited to, 0.5 mil to 2 mil.

[0155] Prior to application of pretreatment and encapsulant, any sharp (ie, "raw" or "cut") edges of the reflectively coated substrate are removed and the surface is cleaned as described above.

[0156] Additionally, a pre-treatment is preferably applied to surface 131 of coating 80 prior to application of Pem encapsulant 104. Coating 80 is a protective outer coating used to protect the Si (85%)-Al (15%) oxide layer of solar reflective coating stacks 32 and 35 (see Figure 11). Pretreatment of surface 131 promotes adhesion of Pem encapsulant 104 to surface 131 of coating 80 . The present invention contemplates cleaning the outer surfaces of coating stacks 32 and 35 to enhance adhesion of the coating stacks of solar cell 130 encapsulation 104 to substrate 120 . A detailed discussion of pPO coating 25 is provided in U.S. Patent No. 8,445,098.

[0157] The present invention is not limited to adhesion promoters that may be used in the practice of the invention and any of the known adhesion promoters may be used in the practice of the invention. In a non-limiting example of the invention, preferred pretreatments include, but are not limited to, silane-based chemicals; a suitable composition is 25 wt.% isopropyl alcohol: 75 wt.% deionized water. 5 wt. % gamma-aminopropyltriethoxysilane in the premixed base based on total solution weight; commercially available forms of this silane-based chemical are available from Momentive Corporation or General Electric Corporation to SiIquest® A-1100. The pretreatment chemicals are sprayed onto the coating column or stack 32 and/or 35 and allowed to remain on the surface for a dwell time of 30 seconds before being thoroughly rinsed off by flushing the surface with deionized water. Immediately after the rinsing process, the remaining rinsing water flows down from the coating stack 32 and/or 35 in sheets using an air knife or similar device. The pretreated coating stack is then preheated to approximately 20 CTF (93°C) before applying the PEM-based coating 120 .

[0158] The present invention is not limited to methods of applying PEM-based coating 104 chemicals, and such methods include, but are not limited to, curtain coating, spray coating, flow coating, electrophoretic coating, and draw coating. For application via curtain coating, the Zn-PeM based coating chemistry is approved using a suitable solvent such as 2-butoxyethanol (also known as "butyl cellulose"), xylene, Solves® 100 solvent, similar solvents or combinations thereof to the recommended application viscosity (15-23 seconds, #3 Zahn cup). A sufficient amount of basecoat chemistry is applied to the reflectively coated substrate to achieve a basecoat dry film thickness (DFT) of approximately 1" mil (27.94 microns) on the finished article. Process parameters for the base coating application process (e.g., width of the aperture of the curtain coater, conveyor line speed of the substrate through the paint curtain, etc.) are typically adjusted empirically to obtain the desired base coating. Layer DFT. Immediately following the application of the PEM-based coating chemistry is movement of the substrate through an oven where heat is continuously applied to enable solvent to evaporate from the applied liquid-based coating. The area in which the solvent is removed is called the "flash section" for the sake of clarity.

[0159] The application of heat in the flash stage also preheats the substrate to prepare the substrate to receive the chemicals of the PEM encapsulate 104; immediately prior to applying the topcoat 122 of the PEM encapsulate 104 The previous minimum substrate surface temperature was approximately 120°C. F (49°C) ο

[0160] A variety of methods may be used to apply the PEM topcoat 122 chemistry, including, but not limited to, curtain coating, spray coating, flow coating, and draw coating. For application via a curtain coating process, Acceptable PEM Topcoat Chemistry 122 is prepared using a suitable solvent such as 2-butoxyethanol (also known as "butyl cellulose"), xylene, Solvesso® i00 solvent

agent, similar solvent, or combination thereof to the recommended application viscosity (15-23 seconds, #3 Zahn cup). A sufficient amount of topcoat chemistry is applied to the substrate to achieve a topcoat dry film thickness (DFT) of approximately 1.0 mils (25.4 microns) on the finished article. Process parameters for the topcoat application process (e.g., width of the curtain coater aperture, conveyor line speed of the substrate through the paint curtain, etc.) are typically adjusted empirically to obtain the desired topcoat Layer DFT. Immediately following application of the topcoat chemistry of the ZnPEM encapsulate, the substrate optionally travels through a second "flash section" allowing the solvent to evaporate from the applied liquid topcoat.

[0161] Immediately following any "flash phase" emerging from the topcoat 122 for the PEM encapsulant 104, the coated substrate is cured in a suitable vented oven/oven, the appropriate Ventilated ovens/ovens are designed for curing polymer coatings/coatings over larger areas of substrates. The typical recommended residence time in the oven (also known as the "ride time") for any given substrate coated with PEM encapsulant 104 is approximately 251 seconds. The recommended exit temperature for the encapsulated surface of the substrate immediately upon exiting the curing oven is approximately 280°F (138°C). After exiting the furnace, the encapsulated reflective coated glass is allowed to cool down in preparation for unloading from the manufacturing line. At this point, the solar mirror constitutes the finished mirror, which includes: (1) a substrate (e.g., glass substrate 12), (2) an MSVD-deposited Ag-based reflector on one major surface of the substrate (coated pillar or stack 166) coating, and (B) a PEM encapsulant 104 applied on top of the MSVD deposited reflective coating stack 32 or 35.

[0162] Optionally, the bottom surface of the finished mirror, eg, surface 14 of substrate 12 (see Figure 11), may be cleaned using an acid etching process and rinsed/dried prior to unloading. The finished mirror is then stored and shipped in any usual manner.

[0163] Finished solar mirrors encapsulated with PEM encapsulant 104 in the manner described above exhibit acceptable adhesion to the substrate as determined using the ASTM D3359 Crosshatch Adhesion Test; typically "4B " or better crosshatch adhesion rating. Similarly, mirrors exhibit acceptable levels of cure as determined using the ASTM D5402 solvent rub test; typically 100 double rubs or more of a methyl ethyl ketone soaked cloth without visible degradation of the encapsulant .

Non-limiting Example of the Invention Using PEM Encapsulate on Coating Stack Without PPO Layer

[0165] As will be understood by those skilled in the art, PPO layer 25 of coating stack 32 and/or 35 has a sheet resistance value greater than 1 Megohm/square. As discussed above, for electrodeposited coatings, electrical connection to the outer surface or top of the PPO layer 25 of the coating stack 35 of the solar mirror 100 is accomplished by adding a conductive material to the base layer 120 of the PEM encapsulant 104 surface 108 (see FIG. 9 ) and the outer surface 112 of the coating stack 32 (see FIG. 10 ) that is electrically connected to the PPO layer 25 of the solar mirror 102 . In the practice of the present invention, Zn flakes 124 are added to the base layer 120 of the PEM encapsulant 104 (see Table 1) because, in addition to providing conductivity, zinc is also a metal-resistance enhancing film. Coating stacks 32 and/or 35 without PPO layer 25 have surface 78A of layer 78 available for electrical connection (Fig. 11). Surface 78A is expected to have a sheet resistance value of less than 0.5 Megohm/square. In non-limiting embodiments of the invention discussed below, one or both of the layers 120 and 122 of the PEM encapsulant 104 covering the surface of the coating stacks 32 and/or 35 do not contain lead (see Table 1 and Table 2). Continue to refer to Figure 9 and Figure 9 as needed. 10. Encapsulation 104 of solar mirror 100 (Fig. 9) and/or solar mirror 102 (Fig. 10) includes, but is not limited to, polyester melamine having a bottom or base layer 120 and/or a top layer 122, in layers 120 and 122 Selected layers have metal resistance enhancing films or particles of Inconel 600, zinc, aluminum, copper, magnesium, or mixtures, alloys or combinations of two or more of the foregoing. In a preferred practice of the invention, the metal of choice is zinc because, in addition to being a resistance-enhancing metal, Zn is a highly conductive metal and can be used in electrodeposition coatings. In either case, the absence of the PPO layer 25 allows the level of expensive Zn flakes 124 used in the base layer 120 of the PEM envelope 104 to be reduced by eliminating the PPO layer 23 while maintaining or improving solar reflective surface 22 and/or a cathodic protection level of 27.

As can be appreciated, the formulation for the base layer 120 of the PEM envelope 104 is shown in Table 1 and is used for the PEM envelope

The recipe for the top layer 122 of 104 is shown in Table 2. The presence of Zn flakes 124 listed in Table 1 is optional and discussed in detail below.

In the following non-limiting embodiment of the present invention, a solar mirror such as, but not limited to, solar mirror 130 of FIG. 11 has a coating stack without PPO layer 25 and has a two-layer encapsulant 104 (see FIG. 11 ). As mentioned above, PPO layer 25 provides chemical and mechanical protection to the film of coating stacks 32 and 35 or to major surface 78A of coating 78. PEM encapsulation 104 provides chemical and mechanical protection to primary surface 75A and coating stacks 32 and 35 in the presence or absence of PPO layer 25 . The protection provided by the PPO layer 25 to the coating stack 32 and/or 35 is now provided by the PEM envelope 104 . More specifically, shown in Figure 11 is a solar mirror 130 having an MSVD coating stack 32 or 35 having layers 24, 76 and 78 and having a solar reflective coating 22 or 27. A base coating 120 of PEM encapsulation 104 with zinc flakes 124 is applied over outer walls 106 and 110 of coating stacks 32 and 35 of reflective article or solar mirror 130 and top surface 78A of layer 78 .

[0168] The Zn flakes 124 in the bottom layer 120 and the top layer 122 of the PEM encapsulation 104 have the function of slowing the corrosion of the Ag layers 27 and/or 22 by absorbing moisture from the atmosphere entering the top layer 122 and the bottom layer 120. More specifically, Zn flakes are used to provide resistance-enhancing metal or sacrificial cathodic protection and serve as cathodes for electrodeposition; Zn flakes 124 are formulated in a moisture stable binder, polyester melamine, to accommodate curtain coating application. For a more detailed discussion of Zn flakes in polyester melamine, reference is made to US Published Patent Application No. 2013/0003206 (Publication '206).

[0169] As can be appreciated, the present invention further contemplates reductions and/or modifications to the solar mirror 130. For example, and without limitation, the bottom layer 120 may have zinc flakes, and the top layer 122 may not contain zinc flakes, as shown in FIG. 11 , or both layers 120 and 122 may not contain zinc flakes, or both layers 120 and 122 may contain zinc flakes. 122 can all have zinc flakes. Encapsulation 104 may have only one layer, which may be of any thickness.

[0170] As can be appreciated, the present invention is contemplated for additional non-limiting embodiments of the present invention by alternating components of the solar mirror 130 shown in FIG. 11 . Unless otherwise stated, modifications to the solar mirror 130 discussed below may be made to the solar mirrors discussed above, such as, but not limited to, solar mirror 5 (Fig. 1), solar mirror 7 (Fig. 3), solar mirror 70 (Fig. 5 ), solar mirror 72 (Fig. 6), solar mirror 100 (Fig. 9), solar mirror 102 (Fig. 10), solar mirror 130 (Fig. 11) and solar mirror 134 (Fig. 13, discussed below).

Non-limiting embodiments of the invention include, but are not limited to:

[0172] Solar mirror A includes, but is not limited to, coating stack 32 or 35; the bottom layer 120 and the top layer 122 of the PEM encapsulation are each free of metal resistance enhancing films or particles, for example, Zn flakes 124. Because surface 78A of coating stack 32 or 35 is electrically conductive, layer 122 can be electrodeposited.

[0173] Solar mirror B includes, but is not limited to, no metal-resistant enhancement film or particles, such as Zn flakes 124, in the bottom layer 120 of the PEM envelope, and a metal-resistant enhancement film in the top layer 122 of the PEM envelope. or particles, for example, Zn flakes 124. Preferably, but not limited to the present invention, layers 120 and 122 of PEM encapsulation may be deposited by electrocoating. Instead of using zinc, the present invention contemplates the use of other metal resistance enhancing films or particles.

[0174] Solar mirror C includes, but is not limited to, metal-resistant enhanced films or particles, eg, Zn flakes 124, in the bottom layer 120 of the PEM envelope and in the top layer 122 of the PEM envelope. Metal resistance enhancing films or particles other than Zn may be used. [0175] Solar mirror D includes metal-resistant enhancing films or particles, such as Zn flakes 124, in the bottom layer 120 of the Zn-PEM encapsulation, and does not include Zn in the top layer 122 of the Zn-PEM encapsulation. Layer 122 may be electrocoated. Metal resistance enhancing films or particles other than Zn may be used in the practice of this invention.

Preferably, but not limited to the present invention, the coating films and layers of solar mirrors A to D may be applied by any suitable coating process including, but not limited to, slot, curtain Coating and/or electrodeposition.

The present invention is not limited to the manner in which the electrocoated topcoat 122 is applied, and the topcoat 122 of the PEM encapsulant 104 may be by a flow coating method as disclosed in U.S. Patent Application Publication No. 2013/0003206 (Publication '206) , said publication is hereby incorporated by reference. As can be appreciated, the addition of Zn flakes 124 to aid in electrocoating adds additional cost to the PEM encapsulation 104 of the coating stack. In another non-limiting embodiment of the invention, reduced use of Zn is provided. Zn flakes 124 are added to the base layer 120 of the PEM encapsulant 104 to provide a conductive surface for electrocoating. Elimination of the PPO layer 25 reduces the amount of metal resistance enhancing film or particles, such as the amount of Zn flakes 124 required in the PEM encapsulation 104, by approximately 50%. The inventive solar mirror 130 shown in Figure 11 now includes a coating stack and a base layer of PEM encapsulant 104 with a reduced amount of Zn. It is extrapolated that the Zn content in this embodiment of the invention may have a 50% reduction in Zn flakes.

In either case, the absence of the insulating PPO layer 25 should also allow the level of expensive Zn flakes in the base coating of the PEM encapsulation to be reduced by eliminating the PPO layer 25 while maintaining (or improving ) level of cathodic protection for silver.

[0179] U.S. Patent No. 8,557,099 (the '099 patent) discloses an apparatus and method for coating reflective articles, such as solar mirrors with electrodeposited coatings.

[0180] Previously, second surface solar mirrors have typically been encapsulated with a two- or even three-layer system that involves first applying a corrosion-resistant base coating followed by a protective topcoat. These coatings can be applied by traditional wet coating methods such as curtain coating.

[0181] If the base coating is conductive, such as, for example, the base coating of the partially organic, metal-containing base coating 120 of the PEM envelope 104, then a top coating, such as but not limited to, is applied to the PEM envelope 104. The topcoat 122 over the base coating 120 may be an electrodeposited topcoat, for example, of the type disclosed in the '099 patent, which provides a number of additional advantages, such as better Uniform thickness control, higher transfer efficiency, less waste, lower VOC content, and more. However, if the top layer of the reflective structure is an insulating material as described in the '099 patent, a conductive base coating is still required in that case to easily perform electrodeposition. If the mirror film is considered such that there is no significant insulating film on the top surface of the coating stack, the mirror can be encapsulated by direct electrodeposition of the electrodeposition coating formulation without the need for a conductive base coating, so The conductive base coating is, for example, but not limited to, the base coating 120 of the encapsulation 104 .

[0182] The single layer PEM encapsulant coating offers significant cost reductions and potential processing advantages, including more flexibility in manufacturing design, e.g., also being able to operate without the need for a base coating application line A cascade electrodeposition coater of the type disclosed in the '099 patent was installed at an MSVD production facility.

[0183] Referring to FIG. 12, a non-limiting embodiment of a solar mirror 150 is shown. Solar mirror 150 includes substrate 12, bottom layer 24, and solar reflective layer 22 or 27. Instead of a conductive envelope, the base coating 120 of the PEM envelope 104 is the solar reflective layer 22 or 27 of the coating stack 32 or 35 without the PPO layer 25. The function of the encapsulant-based coating 120 is replaced by a solar reflective layer 22 or 27 of an electrodeposited encapsulant 152 of the type disclosed in the '099 patent or a coating stack 32 or 35 without a PPO layer 25 .

[0184] The electrodeposited encapsulation 152 of the solar mirror 150 was fabricated and tested and passed the CASS fog test.

Referring to Figure 13, it will now be understood that based on the above, the solar mirror 156 shown in Figure 13 can be reduced to the substrate 12, the bottom layer 24, the solar reflective coating 22 or 27 and the electrodeposited encapsulant 152.

[0186] Non-limiting Example of the Invention Using a Framed PEM Encapsulation on a Coating Stack with a PPO Layer

[0187] The following discussion refers to the solar mirror 160 shown in Figures 14 and 15, however, it will be understood that unless otherwise indicated

However, this discussion can be applied to all solar mirrors discussed in this article. Referring to FIG. 15 , solar mirror 160 includes coating stack 32 or 35 applied to surface 16 of substrate 12 . Coating stacks 32 and 35 each include a bottom layer 24 over surface 16 of substrate 12; a solar reflective coating 27 or 22 over bottom layer 24, a layer 76 over solar reflective coating 27 or 22 and 78, and PPO layer 25 over coatings 76 and 78. As can now be appreciated, to prevent or reduce corrosion of solar reflective coatings 27 and 22 as well as corrosion of other films of coating stacks 32 and 35, the coating stack includes the PPO layer 25 and PEM encapsulation system discussed above.

During the CASS test, it was noted that the location where corrosion of the coating stacks 32 and 35 typically begins at the outer wall 106 of the coating stack 35 and the outer wall 110 of the coating stack 32 and inwards The location of movement rarely begins on the main surface, such as the top surface 108 of the PPO coating 25 . It was concluded that the central portion 164 of the top surface 108 of the PPO layer 25 does not have to be coated with the base layer 120 and zinc flakes 124 of the PEM encapsulation 104 . As can be appreciated, the elimination of the base coating 120 of the PEM envelope 104 over the central portion 164 of the PPO layer 25 and the zinc flakes 124 therein provides significant reductions in material cost and manufacturing time.

[0189] As may be recalled, in the above discussion, the base layer 120 with zinc flakes is applied over the top surface 108 of the PPO layer 25 so that the top layer 122 of the PEM encapsulation 104 can be electrocoated to the PEM encapsulation 120 on the bottom of 104.

[0190] Shown in Figures 14 and 15 is a solar mirror 160. Solar mirror 160 has base coating 120 of PEM envelope 104 on marginal edge 166 of PPO layer 25 and extends over edges or outer walls 110 of coating stacks 32 and 35 . The top coat 122 of the PEM encapsulation 104 is applied over the base layer 120 and over the central portion 164 of the PPO layer 25 . The central portion 164 of the surface of the PPO layer 25 is blocked during application of the Zn-based coating 120 in any convenient manner. Topcoat 122 may be applied by selecting one of the coating processes discussed herein.

Sufficient corrosion protection is obtained by applying the Zn-based coating 120 to the peripheral edges of the coating film and the marginal edges of the PPO film 25 and by applying the top coating 122 over the Zn-based coating and the exposed PPO surface. Protected to pass CASS fog test.

[0192] The present invention is not limited to the width of the Zn-based coating applied to the marginal edges of the PPO layer 25. The samples used for the CASS fog test were 3 feet in length and 2 feet in width. The Zn-based coating 120 on the marginal edge of the PPO layer 25 has a width in the range of 1 cm to 2 cm. Samples passed CASS fog test. Optionally, a topcoat 122 may be applied over the exposed surfaces of the base coating 120 and PPO layer 25 for added protection.

[0193] The width of the base layer 120 covering the marginal edge of the PPO layer 25 is generally in the range of greater than zero to 5 inches, in the range of greater than zero to 4.5 inches, in the range of greater than zero to 4.0 inches, in the range of greater than zero to 3.5 inches, within a range of greater than zero to 3.0 inches, and within a range greater than zero to 2.5 inches.

In another test, two samples of MSVD mirrors approximately 5 inches The center mask is then coated with topcoat 122 by draping. After curing, 1 inch was cut off each side of the sample, leaving a 3 inch area. After 120 hours of CASS fog test exposure, there was no corrosion along any of the cut edges, nor any corrosion on the center of the face protected only by the topcoat of the envelope. In comparison, the samples with the topcoat 122 of the PEM encapsulation 104 but the basecoat 120 without the PEM encapsulation 104 all failed the CASS fog test at 12 hours.

[0195] The advantages of this embodiment of the invention are that (1) compared to the many gallons of coating required to establish a process such as curtain coating for full surface coverage of the outermost sheet, using The anti-corrosion coating is radially/sprayed/printed/electrocoated to cover the edges of the coating stack and the marginal edges of the outermost sheets as disclosed in Patent '099 and Publication '206

or similar methods, (2) only covering a smaller percentage of the mirror area near the edge and greatly reducing material costs, (3) reducing the weight of the solar mirror.

[0196] The present invention may be practiced to make a second surface mirror as described above, but if the protective outer coating is transparent or if the first surface mirror itself is durable enough to survive with only edge protection. The invention may also be practiced to make first surface mirrors. By applying a Zn-based coating (anti-corrosion coating) only to the edges of the mirror, sufficient cathodic protection is obtained to prevent the onset of corrosion, while at the same time it is possible to significantly reduce the cost and weight of a two-layer encapsulation system.

[0197] In discussing a non-limiting example of the present invention, a coating stack is applied to a second surface of a substrate that faces away from the sun. In this way, sunlight passes through the first and second surfaces of the substrate. However, the invention is not limited thereto, and the coating stack with the PEM encapsulant may be mounted on the first surface of the substrate (e.g., by using a transparent encapsulant (e.g., with the color pigment removed from the material of the encapsulant)). the surface facing away from the sun). In this way, solar rays pass through the encapsulation to the solar reflective film and are reflected back through the encapsulation.

[0198] The present invention is not limited to the embodiments of the invention set forth and discussed above, which are presented for illustrative purposes only, and the scope of the invention is limited only by the scope of the following claims and any appended claims, Any additional claims are added to applications that are directly or indirectly related to this application.

CN 113683315 Β