Self-protecting silver nanowire heating element and its applications

Abstract

The present invention discloses a self - protecting silver nanowire heating element and its application. The self - protecting silver nanowire heating element includes a silver nanowire transparent conductive film, a protective glue layer and a transparent cover plate. The silver nanowire transparent conductive film includes a transparent substrate and a silver nanowire layer which are stacked. The protective glue layer is annularly laminated on the silver nanowire transparent conductive film, and iron - aluminum intermetallic compound powder is distributed in the protective glue layer. The transparent cover plate is covered on the protective glue layer, and a hollow area is formed among the silver nanowire layer, the protective glue layer and the transparent cover plate. The iron - aluminum intermetallic compound powder contained in the protective glue layer of the present invention can react with water vapor and oxygen inhaled from the external environment, and the generated gas can fill the constructed hollow area. The gas forms a positive pressure in the hollow area, so as to use this positive pressure to prevent external water vapor and oxygen from entering.

Description

Technical Field

[0001] The present invention relates to the technical field of heaters, and more particularly to a self-protecting silver nanowire heating element and its application. Background Art

[0002] Silver nanowire transparent conductive films have excellent optoelectronic properties. Moreover, due to the simple preparation process, easy realization of large-area film formation, and bendable and non-fragile characteristics of silver nanowire transparent conductive films, they have gradually become substitutes for ITO films. However, since silver nanowire transparent conductive films are extremely sensitive to water vapor and oxygen, when water vapor and oxygen come into contact with silver nanowire transparent conductive films, it will cause the silver nanowire transparent conductive films to fail. Especially when silver nanowire transparent conductive films are applied in the field of heaters, they are more likely to accelerate the failure of silver nanowire transparent conductive films under higher DC voltages, resulting in a very low service life of the heaters.

[0003] To solve this problem, the prior art usually uses a protective layer to isolate external water vapor and oxygen. However, due to the existing preparation process of the protective layer or the material properties of the protective layer, only partial blocking can be achieved. As the use time prolongs or when used in coastal environments, etc., some water vapor and oxygen will still be inhaled, resulting in the failure of silver nanowire transparent conductive films. Summary of the Invention

[0004] Aiming at the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a self-protecting silver nanowire heating element and its application.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a self-protecting silver nanowire heating element, comprising:

[0006] A silver nanowire transparent conductive film, the silver nanowire transparent conductive film comprising a transparent substrate and a silver nanowire layer arranged in a stacked manner;

[0007] A protective glue layer, annularly laminated on the silver nanowire transparent conductive film, and iron-aluminum intermetallic compound powder is distributed in the protective glue layer;

[0008] A transparent cover plate, covering the protective glue layer, and a hollow area is formed between the silver nanowire layer, the protective glue layer and the transparent cover plate.

[0009] In one embodiment, the protective glue layer is laminated on the silver nanowire layer.

[0010] In one embodiment, at least part of the protective glue layer surrounds the silver nanowire layer and is laminated on the transparent substrate.

[0011] In one embodiment, at least part of the protective glue layer is laminated on the silver nanowire layer and extends towards the hollow area.

[0012] In one embodiment, the outer edge of the protective glue layer is flush with the outer edge of the transparent substrate.

[0013] In one embodiment, the thickness of the protective glue layer is set to be 50 μm - 80 μm.

[0014] In one embodiment, the iron-aluminum intermetallic compound powder is selected from iron tri-aluminum powder and / or iron aluminide powder.

[0015] In one embodiment, the particle size of the iron-aluminum intermetallic compound powder is 20 nm - 50 nm.

[0016] In one embodiment, the mass fraction of the iron-aluminum intermetallic compound powder in the protective glue layer is 9% - 17%.

[0017] The present invention also discloses that the self-protecting silver nanowire heating element as described above is used as a window of a camera.

[0018] The self-protecting silver nanowire heating element of the present invention constructs a hollowed-out area through the protective glue layer. At the same time, the iron-aluminum intermetallic compound powder contained in the protective glue layer can react with water vapor and oxygen inhaled from the external environment to generate metal compounds such as aluminum oxide and iron oxide and gases such as hydrogen. Among them, the generated gas can fill the hollowed-out area and form a positive pressure in the hollowed-out area, so that this positive pressure can be used to prevent continuous entry of external water vapor and oxygen, effectively blocking the continuous damage of external water vapor and oxygen to the silver nanowire layer and extending the service life of the self-protecting silver nanowire heating element; in addition, for metal materials, heat transfer depends on electron conduction, and the aluminum oxide and iron oxide generated by the reaction remain in the protective glue layer, which just helps to improve the electrical conductivity of the protective glue layer, so the overall heat transfer of the self-protecting silver nanowire heating element can be improved.

[0019] In addition, the self-protecting silver nanowire heating element forms a hollow structure in the central area by only sealing the glue around, which can avoid the influence of the protective glue layer on the light transmittance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 It is a schematic cross-sectional structure diagram of the self-protecting silver nanowire heating element of the present invention;

[0022] Figure 2It is a schematic cross-sectional structure diagram of the transparent cover plate exceeding the protective adhesive layer in the present invention;

[0023] Figure 3 It is a schematic cross-sectional structure diagram of the gas-filled hollow area formed after the protective adhesive layer reacts with water and oxygen in the present invention;

[0024] Figure 4 It is a schematic cross-sectional structure diagram of the protective adhesive layer surrounding the silver nanowire layer and laminated on the transparent substrate in the present invention;

[0025] Figure 5 It is a schematic cross-sectional structure diagram of the protective adhesive layer laminated on the silver nanowire layer and extending into the hollow area in the present invention;

[0026] Figure 6 It is a schematic structure diagram of the rectangular self-protective silver nanowire heating element in the present invention;

[0027] Figure 7 It is a schematic structure diagram of the circular self-protective silver nanowire heating element in the present invention.

[0028] In the figure: 10, transparent cover plate; 11, hollow area; 20, protective adhesive layer; 30, silver nanowire transparent conductive film; 31, silver nanowire layer; 32, transparent substrate. Detailed implementation manners

[0029] For the convenience of understanding the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments or examples and are not intended to limit the present invention.

[0031] See Figures 1 to 7 As shown: The present invention discloses a self-protective silver nanowire heating element, and the self-protective silver nanowire heating element includes a silver nanowire transparent conductive film 30, a protective adhesive layer 20 and a transparent cover plate 10.

[0032] Among them, the silver nanowire transparent conductive film 30 includes a transparent substrate 32 and a silver nanowire layer 31 which are stacked. The silver nanowire layer 31 generates heat when energized to achieve stable conductive and heat generation performances of the silver nanowire transparent conductive film 30. The transparent substrate 32 is made of materials such as polyarylether nitrile (PEN), polyethylene terephthalate (PET), glass, etc., and is preferably made of polymer materials such as PEN and PET, which can make the silver nanowire transparent conductive film 30 flexible. The transparent substrate 32 and the silver nanowire layer 31 have good light transmittance and can be applied to transparent film heaters.

[0033] In the self-protecting silver nanowire heating element of the present invention, the protective glue layer 20 is annularly laminated on the silver nanowire transparent conductive film 30, and the transparent cover plate 10 is covered on the protective glue layer 20, and a hollow area 11 is formed among the silver nanowire layer 31, the protective glue layer 20 and the transparent cover plate 10. At the same time, iron-aluminum intermetallic compound powder is also distributed in the protective glue layer 20.

[0034] With such a setting, the iron-aluminum intermetallic compound powder contained in the protective glue layer 20 can react with water vapor and oxygen inhaled from the external environment to generate metal compounds such as aluminum oxide and iron oxide and gases such as hydrogen. Among them, the generated gas can fill the hollow area 11 and form a positive pressure in the hollow area 11, so that this positive pressure can be used to avoid continuous entry of external water vapor and oxygen, effectively blocking the continuous damage of external water vapor and oxygen to the silver nanowire layer 31, and further being able to better protect the silver nanowire transparent conductive film 30 and make the service life of the self-protecting silver nanowire heating element longer; in addition, for metal materials, heat transfer depends on electron conduction, and the aluminum oxide and iron oxide generated by the reaction remain in the protective glue layer 20, which just helps to improve the conductivity of the protective glue layer 20, so the overall heat transfer of the self-protecting silver nanowire heating element can be improved.

[0035] Preferably, the iron-aluminum intermetallic compound powder is selected from iron tri-aluminum powder and / or iron aluminide powder, and the iron tri-aluminum powder and the iron aluminide powder chemically react with water vapor and / or oxygen. Specifically, the iron tri-aluminum powder and the iron aluminide powder chemically react with water vapor to produce gas and metal oxide; or, the iron tri-aluminum powder and the iron aluminide powder chemically react with oxygen to produce gas and metal oxide; or, the iron tri-aluminum powder and the iron aluminide powder chemically react with both water vapor and oxygen to produce gas and metal oxide, and the generated gas enters the hollow area 11, thereby increasing the air pressure in the hollow area 11 to form a positive air pressure, and the generated metal oxide remains in the protective glue layer 20 to increase the conductivity of the protective glue layer 20.

[0036] Preferably, the particle size of the iron-aluminum intermetallic compound powder is 20 nm - 50 nm, which is beneficial for the iron-aluminum intermetallic compound powder to react better with water vapor and oxygen, and also beneficial for the dispersion of the iron-aluminum intermetallic compound powder in the protective glue layer 20.

[0037] It should be further emphasized that as the use time prolongs, if the gas in the hollow area 11 leaks and the positive pressure environment gradually disappears, at this time, if there is still unreacted iron-aluminum intermetallic compound powder in the protective glue layer 20, it can still react with the water vapor and oxygen inhaled from the external environment to generate metal compounds such as aluminum oxide and iron oxide and gases such as hydrogen, so that the positive pressure is re-formed in the hollow area 11. Therefore, it can be cycled in turn to extend the service life of the self-protective silver nanowire heating element.

[0038] Preferably, the mass fraction of the iron-aluminum intermetallic compound powder in the protective glue layer 20 is 9% - 17%, so that there is more sufficient iron-aluminum intermetallic compound to react with oxidation and water vapor, and the service life of the self-protective silver nanowire heating element is extended.

[0039] In addition, the transparent cover plate 10 is covered on the protective glue layer 20 and is glued to the silver nanowire transparent conductive film 30 through the protective glue layer 20 to form an integral body. The overall processing technology is simple and the structure is ingenious to form a hollow hollow area 11. And the surrounding sealing glue method adopted by the protective glue layer 20 forms a hollow area 11 in the central area of the silver nanowire transparent conductive film 30, and this hollow area 11 can avoid affecting the light transmittance of the self-protective silver nanowire heating element.

[0040] There are many ways for the protective glue layer 20 to be annularly laminated on the silver nanowire transparent conductive film 30, such as Figures 1 to 3 As shown, the protective glue layer 20 is laminated on the silver nanowire layer 31. Therefore, the protective glue layer 20 directly covers at least part of the surface of the silver nanowire layer 31. In this embodiment, the protective glue layer 20 is annularly laminated on one side surface of the silver nanowire transparent conductive film 30, the transparent cover plate 10 is covered on the protective glue layer 20, and a hollow area 11 is formed between the silver nanowire transparent conductive film 30, the protective glue layer 20 and the transparent cover plate 10. The self-protective silver nanowire heating element adopts the silver nanowire transparent conductive film 30, which has low cost and is simple to prepare. The protective glue layer 20 can connect the silver nanowire transparent conductive film 30 and the transparent cover plate 10, avoid the silver nanowire transparent conductive film 30 from being affected by the external water and oxygen environment, and improve the service life of the silver nanowire transparent conductive film 30. Preferably, the outer edge of the protective glue layer 20 is flush with the outer edge of the silver nanowire transparent conductive film 30.

[0041] Such as Figure 4As shown, in another embodiment, at least a part of the protective glue layer 20 surrounds the silver nanowire layer 31 and is laminated on the transparent substrate 32. Then, the silver nanowire layer 31 is located within the surrounding area of the protective glue layer 20, thereby preventing the edges of the silver nanowire layer 31 from being exposed to the air and further reducing the influence of oxygen and water vapor on the silver nanowire layer 31.

[0042] Preferably, the protective glue layer 20 is laminated on the transparent substrate 32, and the transparent cover plate 10 is disposed on the protective glue layer 20. The silver nanowire layer 31 is located within the surrounding area of the protective glue layer 20, and the thickness of the protective glue layer 20 is greater than that of the silver nanowire layer 31, so that a hollow area 11 exists between the silver nanowire layer 31 and the transparent cover plate 10.

[0043] Furthermore, as Figure 5 shown, at least a part of the protective glue layer 20 is laminated on the silver nanowire layer 31 and extends into the hollow area 11, so that the protective glue layer 20 covers the surface of the silver nanowire layer 31, expanding the bonding area between the protective glue layer 20 and the silver nanowire layer 31. In this embodiment, not only the outer periphery of the silver nanowire layer 31 is covered by the protective glue layer 20, but also a part of the top surface of the silver nanowire layer 31 is simultaneously covered by the protective glue layer 20, which can not only increase the bonding area between the protective glue layer 20 and the silver nanowire layer 31, but also improve the performance of isolating the silver nanowire layer 31 from water and oxygen, and a positive pressure is formed in the hollow area 11 when the protective glue layer 20 reacts with water and oxygen.

[0044] Preferably, the outer edge of the protective glue layer 20 is flush with the outer edge of the transparent substrate 32, and the protective glue layer 20 extends from the edge of the silver nanowire transparent conductive film 30 towards the center direction, so that the protective glue layer 20 has a good bonding area with the silver nanowire transparent conductive film 30 and can also have good sealing performance. Preferably, the extension length of the protective glue layer 20 from the edge of the silver nanowire transparent conductive film 30 towards the center direction is balanced to keep the angular sealing dimensions in all directions balanced. Optionally, as Figure 6 shown, the self-protective silver nanowire heating element is set as a rectangular structure, and the protective glue layer 20 is a rectangular ring structure. Among them, the width of the protective glue layer 20 in the long side direction of the silver nanowire transparent conductive film 30 is greater than or equal to the width in the short side direction. Optionally, as Figure 7 shown, the self-protective silver nanowire heating element is set as a circular structure, and the protective glue layer 20 is a circular ring structure surrounding the self-protective silver nanowire heating element.

[0045] In an optionally implemented embodiment, the thickness of the protective glue layer 20 is set to 50 μm - 80 μm to control the presence of a hollowed-out area 11 within the self-protective silver nanowire heating element, while also avoiding the influence of the self-protective silver nanowire heating element on the light-transmitting performance in the hollowed-out area 11. The protective glue layer 20 forms the hollowed-out area 11 in the central area of the self-protective silver nanowire heating element only by sealing the glue around the perimeter, which can avoid the influence of adhesives such as glue on the light transmittance of the self-protective silver nanowire heating element, and the overall light transmittance is good.

[0046] During use, usually the transparent cover plate 10 is the plane where the self-protective silver nanowire heating element contacts the outside world, and external light enters through transmission by the transparent cover plate 10. Correspondingly, the transparent cover plate 10 is made of a light-transmitting material so that the self-protective silver nanowire heating element has good light transmittance. For example, the transparent cover plate 10 is a plate-like structural member made of glass, transparent plastic material, resin material, or other transparent materials. Preferably, the transparent cover plate 10 is set as glass.

[0047] Preferably, the transparent cover plate 10 is a flat plate-like structure, and its outer contour can be set as a rectangular, circular, semi-circular, or other shaped plate-like member to cover the outer surface of the self-protective silver nanowire heating element on one side. In one embodiment, as Figure 2 shown, the edge of the transparent cover plate 10 is greater than or equal to the edge of the protective glue layer 20.

[0048] Preferably, the preparation method of the self-protective silver nanowire heating element of the present invention includes the following steps:

[0049] Provide a protective glue slurry, and the protective glue slurry includes resin and iron-aluminum intermetallic compound powder;

[0050] Under a protective atmosphere, apply the protective glue slurry around the silver nanowire transparent conductive film 30 to form an annular slurry layer, and then cover the transparent cover plate 10 on the annular slurry layer. After curing, a self-protective silver nanowire heating element is obtained. When covering the transparent cover plate 10, a hollowed-out area is formed between the silver nanowire layer 31, the annular slurry layer, and the transparent cover plate 10.

[0051] In order to make the iron-aluminum intermetallic compound powder mix evenly in the protective glue slurry, the protective glue slurry of the present invention is preferably prepared by the following method:

[0052] Under a protective atmosphere, first mix the iron-aluminum intermetallic compound powder with a surfactant and perform ball milling. After the ball milling is completed, add it to the resin and continue ball milling. After ball milling evenly, a protective glue slurry is obtained.

[0053] Among them, the mass ratio of the iron-aluminum intermetallic compound powder to the surfactant is 10:1 - 15:1, and the surfactant is selected from one of sodium dodecyl sulfate, ammonium dodecyl sulfate, and sodium bis(laureth-7) citrate.

[0054] In the protective glue paste, the resin is selected from at least one of bisphenol resin, silicone resin, polyimide or polyurethane, and the mass fraction of the resin in the protective glue paste is preferably 70%-75%.

[0055] In addition, a curing agent and / or a curing accelerator can be selectively added according to the curing ability of the protective paste. Among them, the curing agent is selected from at least one of phthalic anhydride, tetrahydrophthalic anhydride, and polyazelaic anhydride, and the mass fraction of the curing agent in the protective glue paste is 11%-13%; the curing accelerator is selected from at least one of 2-ethyl-4-methylimidazole or 2,4,5-tris(dimethylaminomethyl)phenol, and the mass fraction of the curing accelerator in the protective glue paste is 1%-2%.

[0056] In the preparation method, the protective atmosphere can be selected from atmospheres such as argon and nitrogen, mainly to prevent the powder of iron-aluminum intermetallic compound from reacting with oxygen and water vapor in advance.

[0057] The present invention also provides a use of the self-protective silver nanowire heating element as a window of a camera. It can not only achieve a fast and uniform surface heating effect, endow the camera window with excellent defogging and defrosting functions, solve problems such as unclear captured images caused by window fogging and frosting, but also has a long service life, making the camera particularly suitable for environments such as coastal areas.

[0058] Hereinafter, the self-protective silver nanowire heating element and its application will be further described through the following specific examples.

[0059] Example 1:

[0060] Under argon protection, 0.93 g of iron-aluminum alloy powder with a particle size of 20 nm is mixed with 0.07 g of sodium dodecyl sulfate and ball-milled for 2 h to ensure sufficient and uniform mixing, obtaining a first mixture. Then, under argon protection, the first mixture is added to 7.5 g of epoxy resin, and ball-milled for another 60 min for sufficient and uniform mixing. After taking it out, 1.3 g of phthalic anhydride and 0.2 g of 2-ethyl-4-methylimidazole are added, and stirred and dispersed under argon protection to obtain a protective glue paste.

[0061] Under argon protection, the protective glue paste is coated around the silver nanowire transparent conductive film by screen printing to form an annular paste layer on the silver nanowire layer with a thickness of 75 μm. Then, a transparent cover plate is covered on the annular paste layer. After covering the transparent cover plate, a hollow area is formed between the silver nanowire layer, the annular paste layer and the transparent cover plate.

[0062] Finally, it is placed in an incubator and cured at 160 °C for 60 min to obtain a self-protective silver nanowire heating element.

[0063] The sheet resistance of the silver nanowire transparent conductive film selected in this embodiment is 30 Ω / sq. After the self-protected silver nanowire heating element of this embodiment is powered on at DC 12V under double 85 conditions, it can reach 650 h.

[0064] Example 2:

[0065] Under argon protection, 0.8 g of iron tri-aluminum alloy powder with a particle size of 50 nm is mixed with 0.1 g of sodium bis(laureth-7) citrate and ball milled for 2 h to ensure thorough mixing to obtain a first mixture. Then, under argon protection, the first mixture is added to 7 g of epoxy resin and ball milled for another 60 min for thorough mixing. After taking it out, 1.1 g of phthalic anhydride and 0.1 g of 2-ethyl-4-methylimidazole are added, and it is stirred and dispersed under argon protection to obtain a protective glue slurry.

[0066] Under argon protection, the protective glue slurry is applied around the silver nanowire transparent conductive film by screen printing to form an annular slurry layer on the silver nanowire layer with a thickness of 70 μm. Then, a transparent cover plate is placed on the annular slurry layer. After placing the transparent cover plate, a hollow area is formed between the silver nanowire layer, the annular slurry layer, and the transparent cover plate.

[0067] Finally, it is placed in an incubator and cured at 160 °C for 60 min to obtain a self-protected silver nanowire heating element.

[0068] The sheet resistance of the silver nanowire transparent conductive film selected in this embodiment is 30 Ω / sq. After the self-protected silver nanowire heating element of this embodiment is placed under double 85 conditions and powered on at DC 12V, it can reach 645 h.

[0069] Comparative Example 1:

[0070] The difference between Comparative Example 1 and Example 1 is only that the protective glue layer uses an equal amount of alumina material instead of the iron tri-aluminum alloy material.

[0071] After the silver nanowire heating element of this comparative example is placed under double 85 conditions and powered on at DC 12V, it only lasts for 300 h.

[0072] Comparative Example 2:

[0073] The difference between Comparative Example 2 and Example 1 is only that an annular slurry layer is formed on the transparent substrate of the silver nanowire transparent conductive film, and then a transparent cover plate is placed. After placing the transparent cover plate, there is no hollow area between the silver nanowire layer, the annular slurry layer, and the transparent cover plate.

[0074] After the silver nanowire heating element of this comparative example is placed under double 85 conditions and powered on at DC 12V, it only lasts for 412 h.

[0075] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0076] The above embodiments only express several implementation manners of the present invention, and the description is relatively specific and detailed, but it cannot be understood as a limitation to the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A self-protecting silver nanowire heating element, characterized in that, Comprising: A silver nanowire transparent conductive film, which includes a transparent substrate and a silver nanowire layer arranged in a stacked manner; A protective glue layer, which is annularly laminated on the silver nanowire transparent conductive film, and iron-aluminum intermetallic compound powder is distributed in the protective glue layer; A transparent cover plate, which is covered on the protective glue layer, and a hollow area is formed among the silver nanowire layer, the protective glue layer and the transparent cover plate.

2. The self-protecting silver nanowire heating element according to claim 1, wherein The protective glue layer is laminated on the silver nanowire layer.

3. The self-protecting silver nanowire heating element according to claim 1, wherein At least part of the protective glue layer surrounds the silver nanowire layer and is laminated on the transparent substrate.

4. The self-protecting silver nanowire heating element according to claim 3, wherein At least part of the protective glue layer is laminated on the silver nanowire layer and extends towards the hollow area.

5. The self-protecting silver nanowire heating element according to any one of claims 1-4, characterized in that, The outer edge of the protective glue layer is flush with the outer edge of the transparent substrate.

6. The self-protecting silver nanowire heating element according to claim 1, wherein, The thickness of the protective glue layer is set to be 50μm - 80μm.

7. The self-protecting silver nanowire heating element according to claim 1, wherein, The iron-aluminum intermetallic compound powder is selected from iron tri-aluminum powder and / or iron aluminide powder.

8. The self-protecting silver nanowire heating element according to claim 1, wherein The particle size of the iron-aluminum intermetallic compound powder is 20nm - 50nm.

9. The self-protecting silver nanowire heating element according to claim 1, wherein, The mass fraction of the iron-aluminum intermetallic compound powder in the protective glue layer is 9% - 17%.

10. A self-protecting silver nanowire heating element as described in any one of claims 1 to 9 is used as a window of a camera.

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