Silicone rubber window panes

Abstract

An energy efficient lightweight, ultra-clear, window pane comprising silicone rubber, and more specifically, optical liquid silicone rubber and its use in an insulating glass unit or an insulating retrofit window system that installs over existing glass window frames and is capable of delivering >R-10 thermal insulation performance with multiple pane-glazing. The insulating retrofit window system comprises at least one pane, and preferably at least two or more panes, which are silicone rubber (LSR) films with low e-coatings on one or both sides of the LSR films that are held in a rigid frame with an air gap between adjacent films.

Description

[0001] SILICONE RUBBER WINDOW PANES

[0002] Relationship to Other Application

[0003] This application claims the benefit of the filing date of United States Provisional Patent Application Serial Number 63 / 616,466 filed on December 29, 2023. The disclosure in this provisional patent application is incorporated herein by reference, in its entirety for all purposes.

[0004] Background of the Invention

[0005] FIELD OF THE INVENTION

[0006] This invention relates generally to a window pane assembly, and more particularly, to an improved retrofit window insulation system having improved thermal and physical properties.

[0007] DESCRIPTION OF THE PRIOR ART

[0008] Storm windows have been used for decades and typically comprise a single sheet of glass in a frame that can be installed over, or in, an existing window frame. Storm windows provide some insulating effect but fall far short of the newer, more energy efficient systems that have been developed over the last decade.

[0009] Glass is still the preferred material used in the industry for insulating panes. However, glass is brittle (breakable) and heavy. Single pane, or multi-pane, designs have been developed using low emissivity (low-e) coated glass. Low-E coatings have been developed to minimize the amount of ultraviolet and infrared light that can pass through glass without compromising the amount of visible light that is transmitted. This significantly improves the insulating quality of the coated glass.

[0010] In a standard double panel insulating glass unit (IGU), there are two glass panes that are separated by a peripheral spacer which creates an insulating air space. It is known to fill the gap between panes with noble gas for even better insulation. However, gas-filled units are subject to leakage over time. In addition, multi pane windows are subject to moisture condensation. Further, when sun shines on the system, the temperature in the gap can damage the window.

[0011] As an alternative to glass as the glazing, polymers, such as thermoplastic acrylics, polycarbonates, polyesters, polyurethanes (TPU), and polyethylene terephthalate (PET), have been used. However, these polymers do not pass standard window covering flame tests. It is also known to use ethylene tetrafluoroethylene (ETFE), which is a copolymerof ethylene and tetrafluoroethylene, in architectural applications. While ETFE is self-extinguishing, it is extremely expensive and hazy.

[0012] Alternatively, clear liquid silicone rubber materials such as those used for light guides, automotive headlamps, and lenses for LED street lights are UL certified for fire performance, aesthetically attractive, good weathering and toughness, and raw material costs that are lower than ETFE. However, it has not previously been known to use this material in a window pane.

[0013] Summary of the Invention

[0014] The Mackinac Technology Company, Grand Rapids, MI (herein "Mackinac") has developed energy efficient retrofit window insulation systems set to be marketed under the trademark WEMS as a retrofit energy management system for windows. WEMS™ units are capable of delivering >R-10 thermal insulation performance.

[0015] A retrofit window insulation system in accordance with the invention has two primary components, the pane assembly and the casing structure. The pane assembly consists of a liquid silicone rubber sheet or film that is bonded to a rigid metal, fiberglass, polymer, or wooden frame.

[0016] Prior art panes typically consist of glass, polymer film, or a combination of one or more layers of glass and / or polymer. In a WEMStmunit, the polymer pane is made by tensioning a flexible polymer sheet or film across a rigid frame structure to make a pane assembly. Optionally, a low-e coating can be applied to one or both sides of the polymer, preferably the low-e coating developed by Mackinac, which is color neutral and achieves greater than 90% visible light transmittance with good low-e performance in the long wave infrared (heat) region. The assembly is porous for air pressure equalization and mitigation of moisture condensation. The rigid frame is installed in a casing structure which may be, for example, a stainless steel frame that is flat or generally C-Channel-shaped to support the pane assembly. A gasket creates a seal around the perimeter of the WEMStmunit. As a retrofit system, the entire unit is then installed in, over, or onto, an existing window frame.

[0017] In accordance with the present invention, the polymer film in the pane assembly comprises a silicone rubber sheet or film which is attached to, or held in, a rigid frame. In a preferred embodiment, the silicone rubber is a liquid silicone rubber, and preferably an optically-clear liquid silicone rubber, also known as an optical liquid silicone rubber. As used herein, the term "optically clear" means up to less than 10% haze, and preferably less than <5% haze, and more preferably < 1% haze. The transparency of these materials is >90%, and is typically 94% or higher in the visible range.

[0018] Optically-clear liquid silicone rubber (LSR) is lighter in weight, more flexible, and more resistant to mechanical stress compared to typical glasses, such as borosilicate or soda-lime. Compared to other polymers, such as acrylic, polycarbonate, or PET, it is also fire resistant inasmuch as it passes UL testing for fire. Liquid silicone rubber has low viscosity in its uncured state so it is moldable by a variety of techniques, including injection molding and can be subjected to higher temperatures than plastics. When cured, it is flexible and does not creep like plastics when in tension on frame. Other properties that make liquid silicone rubber an attractive material for window panes include, that it is chemical-resistant, nonyellowing, has higher stability against UV radiation, and has excellent weatherability.

[0019] The following are specific examples of liquid silicone rubber polymers that are suitable for use in constructing window panes and the pane assemblies of a WEMStmunit in accordance with the invention. These liquid silicone rubber products which can be purchased commercially and used in the practice of the invention include, without limitation, SiloprentmLSR 7080J from Momentive Performance Materials, Inc., Niskayuna, NY; LumisiltmLR 7601 Series, Wacker Chemie AG, Munich, DE; SilastictmMS1002, MS1003, and MS4002, Dow Chemical Company, Midland, MI; Shin-Etsu, Tokyo, Japan, KE-2061 and KEG-2000-70; NuSi I® Liquid Rubber Silicones from Nusil Technology, LLC, Carpenteria, CA and liquid silicone rubberfrom Shanghai You Fine New Material Technology Co., Ltd., Shanghai, CN.

[0020] As used herein, the terms "sheet" and "film" refer to thin flat materials, the difference between films and sheets being due to their thickness. A film is thinner with thicknesses of 0.25 mm whereas a sheet is thicker. According to ASTM Standard Terminology Relating to Plastics (D883-23), a film typically measures less than 0.25 mm (0.01 inches) and a sheet exceeds 0.25 mm in thickness, with some reaching several centimeters.

[0021] The liquid silicone rubber sheets or films as used in the present invention have thicknesses that range from about 125 pm to greater than 10 mm with low haze (< 1%).

[0022] Liquid silicone rubber products are sold as two components, A and B, one of which contains a catalyst which is typically platinum. When components A and B are mixed, typically in a 1 : 1 ratio according to manufacturers instructions, they cure into a solid product. Heat is typically applied to initiate curing and vulcanize the material. Ideally, the cured material will retain its optical and mechanical stability up to at least about 350°C (greater than 600°F).

[0023] When set, liquid silicone rubbers have a hardness ranging from about 20A (soft) to 90A (firm). The LumisiltmLR 7601 Series, for example, has a Shore A hardness from 50 to almost 80. The density of the optically-clear liquid silicone rubber is lower than glass, ranging from about 1.1 to 2.3 g / cm3, making sheets or films of liquid silicone rubber a lightweight product.

[0024] In products where superior insulating ability is desired, the liquid silicone rubber sheets or film(s) provide a substrate for the deposition of a low-e coating which is required to achieve the desired energy performance. The low-e coating can be applied on one or both sides of the liquid silicone rubber sheet or film. As used herein, the term "low-e polymer film," or its equivalent, refers to the low-e coated polymer, which in this case is a low-e coated liquid silicone rubber.

[0025] The low-e coating, may be a transparent conductive metal oxide (TCO), such as Indium Tin Oxide (ITO), Zinc Oxide (ZnO), Aluminum Zinc Oxide (AZO), Tin Oxide (SnO2), Cadmium Oxide (CdO), and Gallium Oxide (GaO). Other low-e coatings, as known in the art, include silver, or stacked layers (e.g., SiOxNy). Low-e coatings are highly reflective to infrared heat energy (>3000 nm) but transparent to visible light (400-700 nm). As used in the examples herein, a preferred low-e coating which is color neutral and achieves greater than 90% visible light transmittance with good low-e performance in the long wave infrared (heat) region and was developed by Mackinac. Such coating, which is described more completely hereinbelow, can consist of a three-layer optical stack with layer thicknesses ranging from 1 nm to 1000 nm.

[0026] Low-e coating can be accomplished in a batch-type vacuum deposition machine, a semi-continuous roll-to-roll machine, or preferably with a continuous high-volume in-line coating machine, as is known to those of skill in the art.

[0027] Metal oxide low-e coatings typically benefit from higher than room temperature deposition temperatures, and / or high-temperature annealing, which could damage thermoplastic polymers as used in the art. However, liquid silicone rubbers can withstand higher deposition temperatures (from 100°C to 350°C). Higher deposition temperatures can result in a better quality metal oxide coatings.

[0028] In order to achieve superior adherence of the low-e coating on the surface of the liquid silicone rubber sheet or film and to avoid tearing and cracking of the coating, it may be desirable or necessary to modify the surface properties. This can be accomplished by several means, including but not limited to, applying a thin layer of another polymer having a Young's modulus that is higher than the Young's modulus of the liquid silicone rubberto the surface of the liquid silicone rubber sheet or film.

[0029] This intermediate polymerserves as a "buffer" between the soft liquid silicone rubber and the harder first layer of the low-e coating. In some instances, the so- called buffer can be an inorganic material, such as a thin layer of a malleable or semi-malleable metal, such as aluminum, or an oxide, such as zinc oxide.

[0030] It is also known to irradiate the surface with UV and Vacuum UV (VUV) light. In particular, we have found that irradiating the surface of optical silicone rubber sheets with VUV in a spectral range of less than 300 nm, and preferably at wavelengths of in the range of between 100 nm and 200 nm, and preferably at wavelengths of 127 nm and / or 185 nm and / or 254 nm, achieves the desired objective.

[0031] While not wishing to be bound by theory, it is believed, based on IR spectra, that the VUV irradiation photochemically induces conversion of methylsilane groups on the poly(dimethylsiloxanes) comprising the liquid silicone rubbers to silanol groups. This results in a thin surface layer that has more glass-like properties.

[0032] Incorporating liquid silicone rubber into a retrofit window insulation system is a completely different technology from the current state-of-the-art insulating glass units and secondary glazing. Instead of sealed, noble gas-filled units, WEMS™ units are air-filled with multilayered radiant barriers. Using liquid silicone rubber, and particularly optical liquid silicone rubber, to make clear panes for a window product is unprecedented and has many advantages over the currently used storm windows made of glass and / or known polymers. For example, glass is heavy and brittle. However, if the glass pane is made thinner, it breaks easily. Polymers burn whereas silicone rubber is UL-Certified for fire performance. Silicone rubber is UV-stable, and lightweight. It has been shown that WEMS™ units can withstand explosive blasts and hurricane-force winds (see, co-pending International Patent Application No. US-2023-0084137 laid open on March 16, 2023). Moreover, if the WEMS™ units are placed on the exterior of the existing windows, softer surface could reduce impact fatalities for birds.

[0033] Optional features can be added to the unit to improve functionality and customer appeal. The units can be made compatible with operable windows. Mechanical shading, such as louvers, can be added to provide controllable daylight redirection, reduced glare, control over solar heating, and privacy The louvers can be filled with phase change materials (PCMs) for thermal storage. An internal LED fixture can direct light to reflective shade surface and illuminate an entire room to add aesthetic appeal an value. The casing can be configured to include a solar cell and battery to operate the shading, lighting, and thermal storage.

[0034] These features are described more completely in co-pending International Application No. PCT / US24 / 31160 filed on May 24, 2024, and laid open on November 28, 2024 as International Publication No. WO 2024-243579, the disclosure of which is incorporated herein.

[0035] Brief Description of the Drawing

[0036] Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the annexed drawing, in which:

[0037] Fig. 1 is a schematic representation perspective view of a pane assembly for a retrofit window insulation system in accordance with the present invention;

[0038] Fig. 2 is an exploded view of the retrofit window insulation system; and

[0039] Fig. 3 is a side-sectional view of a triple pane insulating glass unit (IGU) in accordance with the present invention.

[0040] Detailed Description

[0041] Mackinac has made silicone rubber sheets or films for WEMStmunits by applying a low-e coating to commercially available transparent, calendared silicone rubber sheets. Low-e coatings can be applied in a batch-type vacuum deposition machine, or preferably with a semi-continuous high-volume coating machine, as is known to those of skill in the art. However, due to fillers used in calendared silicone sheet products, calendared silicone sheet products can have high haze.

[0042] Mackinac has discovered that using low haze optical liquid silicone rubber to make sheets or films for the WEMStmunits of the present invention has enabled the manufacture of large dimension silicone rubber panes in custom sizes by several techniques, including injection molding and a vacuum press compression molding, as will be described hereinbelow. Ideally, the dimensions of the polymer sheets or films for glazing would range from 12 inches x 12 inches (30 cm x 30 cm) to 4m x 4m for windows and building and architectural uses. Thicknesses between 125 microns to 10 mm.

[0043] As indicated above, liquid silicone rubber products are sold as two components, A and B, one of which contains a catalyst. When components A and B are mixed, typically in a 1: 1 ratio, according to manufacturer instructions, they cure into a solid product. Heat is applied to vulcanize, the material.

[0044] There are at least four methods of making liquid silicone rubber sheets or films that can be used in the practice of the invention.

[0045] (1) knife coating

[0046] Liquid silicone rubber components are applied to a substrate (typically PET) and leveled by a metering blade to achieve the desired thickness. However, this process does not produce defect-free films. Entrapped bubbles and surface defects make knife coated films problematic for window products.

[0047] (2) injection molding (under vacuum)

[0048] Since liquid silicone rubber is supplied as two liquid components, it can be injection molded. The two components must be carefully metered and thoroughly mixed without entrapping air or gases before injecting the mixed resin into a mold under vacuum. The pot life for mixed LSR is several days, or even weeks, so there is plenty of time for molding. After molding, the LSR is vulcanized at temperatures ranging from 100°C to 350° C for times ranging from 1 to 90 minutes. After vulcanizing is complete, the material can be cooled and removed from the mold.

[0049] Limworks, LLC, Jenison, MI has a proprietary liquid silicone rubber injection molding technology, covered by, inter alia, US Patent Nos. 10,239,246 and 11,110,636; and EP3265288.

[0050] Samples of liquid silicone rubber sheets comprising Dow's SilastictmMS1002 liquid silicone rubber were successfully manufactured by the Limworks process using a molding temperature of 110° C with an initial cure in about 6-7 minutes.

[0051] (3) vacuum pressing

[0052] In order to make an optically-clear film by a vacuum press compression molding process, the liquid silicone rubber components are metered, mixed, and placed on a smooth substrate, or platen, such as a sheet of glass or a stainless steel foil. A vacuum is applied. A second platen is placed on top of the first platen and the silicone rubber mixture is pressed togetherto achieve the desired thickness. The result is a smooth, transparent sheet or film of liquid silicone rubber which, when removed from the platen, that can be used as a pane in the retrofit insulating window unit of the present invention.

[0053] (4) a hybrid between injection molding and vacuum pressing known as injection compression molding. Liquid silicone rubber sheets and films comprising SilastictmMS1002 and MS4002 from Dow Chemical Company; SiloprentmLSR 7080J from Momentive Performance Materials, Inc.; and NuSil® from Nusil Technology, LLC , Carpenteria, CA were successfully manufactured by injection molding and vacuum pressing processes as described above.

[0054] After the cured and / or vulcanized liquid silicone rubber sheet or film is formed, an optional buffer or reinforcing layer may be deposited on the surface of the sheet or film to improve mechanical and surface properties. This is particularly advantageous if a low-e coating is to be deposited on the liquid silicone rubber sheet or film. In the case of an inorganic low-e coating material, such as a multilayer silicon oxynitride (SiOxNy) stack, it is important that the low-e material adheres well to the polymer substrate.

[0055] In one example, the buffer layer is a thin layer of another polymer having a Young's modulus that is higher than the Young's modulus of the liquid silicone rubber to the surface of the liquid silicone rubber sheet or film. The Young's modulus of silicone rubber 2 MPa which is very low. Young's modulus of Mackinac's low e-coating is about 200-279 GPa. Ideally, the buffer layer would have a Young's modulus which is in the high megapascals (MPa).

[0056] As specific examples, some liquid silicone rubber samples were coated with a solvent-based product by Dow Chemical Company, specifically DOWSIL™ 1-2577 Conformal Coating and DOWSIL™ EG-1200 Gel. Wacker Chemie AG has similar products under the Lumisil and SilGel brands, specifically, Lumisil 100; Lumisil 102; Lumisil 102FC; Lumisil 105; and SilGel 612 PT.

[0057] In another example, the buffer layer is an inorganic material, such as a thin layer of a malleable or semi-malleable metal, such as aluminum, or oxide, such as zinc oxide. Mackinac has achieved acceptable results with a thin layer of aluminum ranging from 1 nm to 50nm to retain acceptable transparency.

[0058] In yet another preferred example, liquid silicone rubber sheet or film is irradiated with light in the ultraviolet (UV) spectral range of 100 nm to 300 nm as disclosed in Dolle, eta / ., Near-Surface and Bulk Modification of Silicone Rubber under UV- and Vacuum UV-Irradiation Using Excimer and Hg Lamps, ACS Omega 2024, 9, 45000-45010. Dolle , et al. treated the liquid silicone rubber surface to reduce dust attraction and facilitate cleaning without affecting the optical properties of the liquid silicone rubber. As a specific example, Dolle , et al., irradiated a sample of Si lastictmMS1002, having a thickness of 2.7mm and a diameter of 31 mm with a mercury (Hg) lamp, emission wavelength from 185-254 nm. The penetration depth of the light is affected by the emission wavelength so that a different result was achieved with 254, 185, and 172 nm irradiation. UV light at 185 can penetrate only a few micrometers into the silicone rubber thereby imparting glass-like properties to the topmost surface. UV light at 172 nm penetrates less than a micrometer. However, UV light at 254 nm can penetrate several millimeters into the silicone substrate. These results were confirmed with surface-sensitive measurement techniques, such as x- ray photoelectron (XPS) spectroscopy or attenuated total reflectance (ATR) spectroscopy.

[0059] The foregoing treatments can be used to prepare the surface of the liquid silicone rubber sheet or film to reduce cracking of a low-e coating for superior optical and aesthetic properties in a window pane or WEMStmunit.

[0060] The liquid silicone rubber sheets or films used in the practice of the present invention can endure higher temperatures than previously used polymers, such as polycarbonate and ETFE. This enables ITO deposition, for example, at elevated temperatures which may also improve the electrical properties of this transparent conductive oxide. For reference, ITO deposition on soda lime glass is typically done at up to ~250-300 °C.

[0061] In an example of an insulating liquid silicone rubber sheet or film for a window pane or pane assembly, a three-layer optical stack consisting of silicon oxynitride (SiOxNy), transparent conductive oxide (TOO), and metal oxides and / or ceramic oxides, such as silicon dioxide (SiO2) ortitanium dioxide (TiO2), is deposited on a liquid silicone rubber sheet or film as the substrate.

[0062] The three-layer design [air / Low / TCO / Medium / Substrate / ...] allows low-e control by the transparent conductive oxide (TCO) and its thickness. Each material has a different refractive index (n) from Low to Medium to High as shown in Table 1 below. In a specific example, the Low-index material (SiO2) has n ~ 1.45, the Medium-index material (SiOxNy) has n ~ 1.71, and the high-index material (ITO) has n ~ 2.00. Anti-reflection (AR) is controlled by use of Low and Medium index layers.

[0063] Table 1

[0064] *DLC:F is a fluorinate Diamond-Like Carbon material as described in detail in USPN 10,435,567

[0065] The WEMStmunits may have optical stacks on both sides of the liquid silicone rubber substrate. A mirror image, designated Stack-B, is placed on the other side of the substrate [air / Low / TCO / Medium / Substrate / Medium / TCO / Low / air] = [Stack-A / substrate / Stack-B] . Of course, the stacks on sides A and B may have slight differences, for example, in their materials and / or in their layer thicknesses. Mackinac has achieved transmittance [Rvis] less than 1% (0.007) over a broad spectral range with this arrangement. The low-e coating described in this example has an emissivity of 0.17.

[0066] The color of the resulting pane can be controlled by slight adjustments to the Low and Medium thicknesses. Color under reflection can be controlled from orange to bluish tints, to perfect color neutrality. Color under transmission is a very stable from a very light yellow to very light greenish tint.

[0067] The two primary components of the retrofit window insulation system 10, 10' of the present invention are the pane assembly 20 (Fig. 1) and the casing structure 30 (Fig. 2) which is configured to hold one or more pane assemblies.

[0068] Referring to Fig. 1, each pane assembly 20 consists, at minimum, of a polymer film 11 bonded to the front-facing surface 13 of a rigid frame 12. Rigid frame 12 can be formed of a high strength polymer, illustratively pultruded fiberglass. In an alternative, and preferred embodiment, the frame structure is made of metal, such as steel. The steel or stainless-steel frames and casings can be made by roll forming or with a press brake. In other preferred embodiments, stock metal tubing or custom roll-formed profiles may be used.

[0069] In a typical embodiment, the rigid frame 12 has two pairs of frame profile sections 15, 15' of unequal lengths that form a rectangle. The frame profile sections have a front-facing surface 13 and back-facing surface 14 and a thickness (t) as measured front to back. Rigid frame 20 is sized to fit within casing structure 30 (see, Fig. 2) or to be directly attached to a pre-existing window frame or surrounding wall.

[0070] In some embodiments, a second polymer film (not shown) is bonded to the rear-facing surface 14 of rigid frame 12 or to a second frame (not shown). The thickness (t) of rigid frame 12 advantageously separates the two films to form an air gap. If more than two films are desired, more pane assemblies 20 can be used. Again, the thicknesses of the rigid frames form an air gap between the films in adjacent pane assemblies. For optimal thermal performance, the preferred air gap width is between about 19mm to 23mm, and most preferably about 21mm.

[0071] The polymer film(s) used in the pane assemblies of the present invention are transparent and provide a substrate for the deposition of a low emissivity (low-e) coating. In accordance with the invention disclosed herein, the polymer film is an optically-clear liquid silicone rubber. Preferably the silicone rubber film acts as a substrate for the application of a low-e coating on one or both sides of the film.

[0072] In some embodiments, the retrofit window insulation system 10 of the present invention comprises a single pane assembly or multiple stacked pane assemblies of the type shown in Fig. 1. In other embodiments, the pane assembly or assemblies are held in a casing structure.

[0073] Fig. 2 is a fully exploded view of retrofit window insulation system 10' showing two pane assemblies 20, 20' being installed in casing structure 30. Casing structure 30 comprises a horizontal header 31 (top), two vertical supports 32 and 33, and a horizontal support 34 (bottom) which form, in this case, a rectangular structure which supports the pane assemblies 20, 20'. The interior surfaces of the aforementioned elements comprising the casing structure 30 have grooves 37 and 38 configured to receive the two pane assemblies. Of course, a retrofit window insulation system 10' that is configured to hold more than two pane assemblies would have additional grooves.

[0074] Fig. 3 is a side-sectional view of a triple pane Insulating Glass Unit(IGU) utilizing the principles of the present invention. Referring to Fig. 3, Insulating Glass Unit (IGU) 50 comprises a pair of glass panes 40 and 40' held in spaced apart relation by foam spacer(s) 42. Central pane 41 can be thin glass (e.g., glass having a thickness of 0.7mm) ora liquid silicone rubber sheet orfilm in accordance with this invention. In this embodiment, the external glass panes, which are flat glass or polymer sheets having a front-facing, or exterior surface, and an opposing interiorfacing surface. In this example, the interior-facing surfaces 43 and 43' of glass panes 40 and 40' have low e-coatings 45 and 45'. Ideally, the spacer provides air gaps 46 and 46' between the panes of about 19mm to 23mm, and most preferably about 21mm. This unit can also be sealed and filled with Argon, which of course, require narrower gaps. In another example, central pane 41 can have a low-e coating on one or both sides.

[0075] Although the invention has been described in terms of specific embodiments and applications, persons skilled in the art can, in light of this teaching, generate additional embodiments without exceeding the scope or departing from the spirit of the claimed invention. Accordingly, it is to be understood that the drawing and description in this disclosure are proffered to facilitate comprehension of the invention, and should not be construed to limit the scope thereof. Moreover, the technical effects and technical problems in the specification are exemplary and are not limiting. The embodiments described in the specification may have other technical effects and can solve other technical problems.

[0076] Additional disclosure that may be helpful in an understanding of the invention can be found in Applicant's co-pending applications, specifically international patent application No. PCT / US2021 / 43343 laid-open on December 23, 2021 as WO 2021 / 25808 and U.S. Serial No. 17 / 876,999 filed on July 29, 2022 and published on March 16, 2023 as US-2023-0084137; the disclosures of which is incorporated herein.

Claims

What is claimed is:

1. A window pane assembly comprising : a liquid silicone rubber sheet or film, said liquid silicone rubber sheet or film being attached to and held in a rigid frame.

2. The window pane assembly of claim 1 wherein the liquid silicone rubber is an optical liquid silicone rubber having a haze of < 10%, preferably <5%, and more preferably < 1%.

3. The window pane assembly of claim 2 herein the optical liquid silicone rubber is selected from the group consisting of SiloprentmLSR 7080J from Momentive Performance Materials, Inc., Niskayuna, NY; LumisiltmLR 7601 Series, Wacker Chemie AG, Munich, DE; SilastictmMS1002, MS1003, and MS4002, Dow Chemical Company, Midland, MI; Shin-Etsu, Tokyo, Japan, KE-2061 and KEG-2000-70; NuSil® Liquid Rubber Silicones from Nusil Technology, LLC, Carpenteria, CA and liquid silicone rubberfrom Shanghai You Fine New Material Technology Co., Ltd., Shanghai, CN.

4. The window pane assembly of claim 2 further comprising a thin layer of another polymer material having a Young's modulus that is higher than the Young's modulus of the liquid silicone rubber deposited on the surface of the liquid silicone rubber.

5. The window pane assembly of claim 1 further comprising : a low e-coating on one or both sides of the liquid silicone rubber sheet orfilm.

6. The window pane assembly of claim 5 wherein the low e-coating contains silver.

7. The window pane assembly of claim 5 wherein the low-e coating contains transparent conducting oxide materials.

8. The window pane assembly of claim 5 wherein the low-e coating is a multiple layer stack consisting of metal oxides and / or ceramic oxides and transparent conducting oxide.

9. The window pane assembly of claim 8 wherein the low-e coating is a multiple layer stack consisting of siliconoxynitride, TCO, and silicon dioxide.

10. The window pane assembly of claim 2 wherein the liquid silicone rubber sheet or film is surface-treated by irradiation with light in the ultraviolet (UV) spectral range of greater than 100 nm and less than 400 nm.

11. The window pane assembly of claim 10 wherein the surface is irradiated in a spectral range of from about 100 nm and 300 nm, and preferably 172 nm, 185 nm, and 254 nm.

12. The window pane assembly of claim 2 further comprising a thin layer of malleable or semi-malleable metal or oxide deposited on the surface of the liquid silicone rubber sheet or film.

13. The window pane assembly of claim 12 wherein the malleable or semi-malleable metal or oxide is selected from the group consisting of aluminum and zinc oxide.

14. A retrofit window insulation system for an existing window frame comprising: at least one pane assembly, said at least one pane assembly having a rigid frame structure having a front surface and a back surface and a thickness (t) as measured front to back, at least one liquid silicone rubber sheet or film bonded to a surface of said rigid frame structure, and a low-e coating on one or both surfaces of the liquid silicone rubber sheet or film to make a low-e coated liquid silicone rubber sheet or film.

15. The retrofit window insulation system of claim 14 wherein there are two low-e coated liquid silicone rubber sheets or films bonded to said rigid frame structure, the second low-e-coated liquid silicone rubber polymer film being bonded to the back surface of said rigid frame structure and the thickness (t) defining an air gap between the two low-e coated liquid silicone rubber sheets or films.

16. The retrofit window insulation system of claim 14 wherein there are two low-e coated liquid silicone rubber sheets or films, each of said low-e coated liquid silicone rubber sheets or filims being bonded to a rigid frame structure, and the thickness (t) defining an air gap between the two low-e coated liquid silicone rubber sheets or films.

17. The retrofit window insulation system of claim 16 wherein the air gap is between about 19mm to 23mm, and most preferably about 21mm.

18. The retrofit window insulation system of claim 14 further comprising: a casing structure, said casing structure being configured to hold one or more pane assemblies and to be attachable to an the existing window frame or a surrounding wall.

19. The retrofit window insulation system of claim 18 wherein said casing is configured to provide an air gap between adjacent pane assemblies.

20. The retrofit window insulation system of claim 14 wherein the liquid silicone rubber is an optical liquid silicone rubber having a haze of < 10%m and preferably <5%, and more preferably < 1%.

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