Electric heating film and equipment

Abstract

The utility model discloses an electric heating film and equipment. The electric heating film comprises a substrate layer, a conductive layer and an oxygen isolation layer which are arranged in sequence, the conductive layer comprises a metal nanowire layer, a two-dimensional graphite material layer and a nano metal oxide layer, and the two-dimensional graphite material layer is arranged on the side, away from the substrate layer, of the metal nanowire layer; the nanometer metal oxide layer is arranged on the side, close to the substrate layer, of the metal nanowire layer, or the nanometer metal oxide layer is arranged on the side, close to the salt isolation layer, of the two-dimensional graphite material layer. A metal nanowire layer is introduced according to a specific space sequence, and a two-dimensional graphite material is filled between networks of metal nanowires, so that a stable and effective composite conductive network is formed. In addition, the nano metal oxide layer with unique size effect and interface characteristics is added, more heat transmission channels are provided by utilizing the small size, large specific surface area, a large number of interfaces and high permeability of the nano metal oxide layer, and the heat conduction efficiency and the uniform stability of the electric heating film are improved.

Description

Technical Field

[0001] This application relates to the technical field of electrothermal films, and particularly to electrothermal films and devices. Background Art

[0002] Currently, indium tin oxide is used as the conductive material in common transparent conductive films on the market. However, its brittleness and the scarcity of indium hinder its application in flexible electronic products. Currently, transparent conductive materials that can replace indium tin oxide on the market include carbon nanotubes, graphene, conductive polymers, metal grids, and metal nanowires, etc. However, there are still a series of problems in attaching the conductive material to a flexible transparent substrate, and it is difficult to simultaneously achieve high thermal stability, low film resistance, and high light transmittance. Summary of the Invention

[0003] This application aims to solve at least one of the technical problems existing in the prior art. For this purpose, this application provides an electrothermal film and a device.

[0004] In a first aspect of this application, there is provided an electrothermal film, which includes a base layer, a conductive layer, and an oxygen isolation layer arranged in sequence. The conductive layer includes a metal nanowire layer, a two-dimensional graphite material layer, and a nano metal oxide layer. The two-dimensional graphite material layer is on the side of the metal nanowire layer away from the base layer; the nano metal oxide layer is on the side of the metal nanowire layer close to the base layer, or the nano metal oxide layer is on the side of the two-dimensional graphite material layer close to the oxygen isolation layer.

[0005] The electrothermal film according to the embodiments of this application has at least the following beneficial effects:

[0006] Due to the confinement effect of the graphite material with a two-dimensional sheet structure, its in-plane thermal and electrical conductivity is very strong, but the weak inter-sheet interaction restricts the exertion of these properties. The metal nanowire layer is introduced in a specific spatial order, and the two-dimensional graphite material is filled between the networks of metal nanowires, thereby forming a stable and effective composite conductive network. In addition, a nano metal oxide layer with unique size effects and interfacial characteristics is added, and its small size, large specific surface area, a large number of interfaces, and high transmittance provide more heat transfer channels, improving the thermal conductivity efficiency and uniform stability of the electrothermal film. The setting of the oxygen isolation layer can further protect the antioxidant effect of the metal nanowire layer and improve the thermal stability of the electrothermal film.

[0007] In some embodiments of this application, the metal nanowire layer is any one of a gold nanowire layer, a silver nanowire layer, and a copper nanowire layer.

[0008] In some embodiments of this application, the two-dimensional graphite material layer is any one of a graphene material layer and a graphdiyne material layer.

[0009] In some embodiments of the present application, the nano metal oxide layer is any one of a nano zinc oxide layer and a nano aluminum oxide layer.

[0010] In some embodiments of the present application, the base layer is a polyethylene terephthalate layer.

[0011] In some embodiments of the present application, the oxygen barrier layer is a polyvinyl alcohol layer.

[0012] In some embodiments of the present application, the conductive layer is further connected to an electrode.

[0013] In some embodiments of the present application, the thickness of the electrothermal film is 1 μm to 1 cm.

[0014] In some embodiments of the present application, the thickness of the base layer is 1 μm to 1 mm.

[0015] In a second aspect of the present application, there is provided a method for preparing an electrothermal film, which is prepared according to any one of the foregoing preparation methods.

[0016] In a third aspect of the present application, there is provided a method for preparing an electrothermal film, the method comprising the following steps;

[0017] Coating a metal nanowire slurry on the base layer to form a first composite substrate containing a wet film of metal nanowires;

[0018] Coating a two-dimensional graphite material slurry on the first composite substrate to form a second composite substrate containing a wet film of two-dimensional graphite materials;

[0019] Coating a nano metal oxide slurry on the second composite substrate to form a third composite substrate containing a wet film of nano metal oxides;

[0020] Annealing the third composite substrate to form a fourth composite substrate;

[0021] Coating an oxygen barrier layer slurry on the fourth composite substrate to make an electrothermal film.

[0022] In a third aspect of the present application, there is also provided a method for preparing an electrothermal film, the method comprising the following steps;

[0023] Coating a nano metal oxide slurry on the base layer to form a first composite substrate containing a wet film of nano metal oxides;

[0024] Coating a metal nanowire slurry on the first composite substrate to form a second composite substrate containing a wet film of metal nanowires;

[0025] Coating a two-dimensional graphite material slurry on the second composite substrate to form a third composite substrate containing a wet film of two-dimensional graphite materials;

[0026] Anneal the third composite substrate to form a fourth composite substrate;

[0027] Coat an oxygen barrier layer slurry on the fourth composite substrate to make an electrothermal film.

[0028] In a fourth aspect of the present application, a device is provided, and the device includes the aforementioned electrothermal film.

[0029] In the solution of the embodiment of the present application, through the combination of silver nanowires and graphdiyne, the optoelectronic properties, chemical stability and flexibility of the thin film are improved. The electrothermal film can be used at a low voltage (within DC 12V), and the amount of nano silver wires can be reduced, further reducing the haze and increasing the light transmittance of the heating film. The visible light transmittance of the electrothermal film can be less than 4%, and the near-infrared transmittance can reach more than 85%. It has the advantages of uniform heat inside the heating surface, resistance to bending, safety and reliability, fast heating rate, long service life, etc., and has good application prospects in the fields of medical devices, surveillance cameras, near-infrared sensors, new energy, etc. The spin coating process is adopted during the preparation process, which simplifies the preparation process and improves the production efficiency.

[0030] The electrothermal film provided by the embodiment of the present application is directly adhered to the surface of the object to be heated, and the thermal response speed is extremely fast. It can reach a very high temperature in dozens of seconds, and concentrate the thermal energy on the frost or fog on the object, with low energy loss, thus greatly improving the working efficiency and reducing the power consumption.

[0031] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0032] Figure 1 It is a schematic structural diagram of the electrothermal film in an embodiment of the present application.

[0033] Figure 2 It is a schematic structural diagram of the electrothermal film in another embodiment of the present application.

[0034] Figure 3 It is a partial schematic diagram of the electrothermal film and the substrate composite in an embodiment of the present application.

[0035] Figure 4 It is the temperature shown by the infrared thermometer when the electrothermal film in an embodiment of the present application is heating.

[0036] Figure 5 It is the temperature shown by the infrared thermometer when the electrothermal film in another embodiment of the present application is heating.

[0037] Reference numerals: base layer 100, conductive layer 200, metal nanowire layer 210, two-dimensional graphite material layer 220, nano metal oxide layer 230, oxygen isolation layer 300, electrode 400, substrate 500. Detailed implementation manners

[0038] The following will clearly and completely describe the concept and technical effects generated by this application in combination with the embodiments, so as to fully understand the purpose, features and effects of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments of this application, other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of this application.

[0039] The embodiments of this application are described in detail below. The described embodiments are exemplary and are only used to explain this application, and should not be construed as a limitation of this application.

[0040] In the description of this application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, exceeding, etc. are understood as not including the number itself, and above, below, within, etc. are understood as including the number itself. If there is a description of first and second, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0041] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0042] In the description of this application, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0043] Reference Figure 1, which shows the structure of the electrothermal film provided by the embodiments of the present application. It includes a base layer 100, a conductive layer 200, and an oxygen barrier layer 300 arranged in sequence. The conductive layer 200 specifically includes a metal nanowire layer 210, a two-dimensional graphite material layer 220, and a nano metal oxide layer 230. Among them, the electrothermal film refers to a thin film that can quickly heat up to a set temperature and generate thermal radiation to the outside when powered on. The overall thickness of the electrothermal film can be, for example, 1μm to 1cm, such as 1μm, 2μm, 3μm, 5μm, 10μm, 20μm, 30μm, 50μm, 100μm, 200μm, 300μm, 500μm, 1mm, 2mm, 3mm, 5mm, 1cm.

[0044] In some embodiments, the base layer is a flexible base layer. In some embodiments, the base layer includes a polymer as the base material. The polymer serving as the base layer includes, for example, at least one polymer material such as polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polyimide, polymethyl methacrylate, etc. In some specific embodiments, the thickness of the base layer is 1μm to 1mm, such as 1μm, 2μm, 3μm, 5μm, 10μm, 20μm, 30μm, 50μm, 100μm, 200μm, 300μm, 500μm, 1mm. In some specific embodiments, the visible light transmittance of the base layer is 50% or less, such as 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less. In some specific embodiments, the infrared light transmittance of the base layer is 50% or more, such as 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more. In some specific embodiments, the infrared light transmittance of the base layer is the near-infrared light transmittance, specifically referring to the light transmittance in the wavelength band of 750 - 2500nm. In some specific embodiments, the infrared light transmittance of the base layer is measured by the light transmittance of any wavelength within the 750 - 2500nm band, such as by the light transmittance of the wavelengths 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm, 1100nm, 1200nm, 1300nm, 1400nm, 1500nm, 1600nm, 1700nm, 1800nm, 1900nm, 2000nm, 2100nm, 2200nm, 2300nm, 2400nm, 2500nm.

[0045] In some of these embodiments, the metal nanowire layer is a metal nanowire layer formed by nanowires of at least one metal such as gold, silver, copper, etc. In some of these embodiments, the metal nanowire layer includes at least one of a gold nanowire layer, a silver nanowire layer, and a copper nanowire layer. In some specific embodiments, the metal nanowire layer is at least one of a gold nanowire layer, a silver nanowire layer, and a copper nanowire layer. Among them, the crystal structures and lattice constants of gold nanowires and silver nanowires are similar, and their conductivity and light transmittance are similar. Therefore, the application of gold nanowires and silver nanowires in the metal nanowire layer has a similar improvement in aspects such as the sheet resistance and light transmittance of the electrothermal film. However, the cost of gold nanowires is higher than that of silver nanowires. The crystal structures of copper nanowires and silver nanowires are similar, but there are differences in lattice constants. Copper nanowires mainly grow along the

[110] crystal direction, resulting in the most unsaturated bonds and the highest surface energy on this crystal plane. Therefore, its chemical stability is poor, it is easy to oxidize and the conductivity decreases, and the light transmittance is relatively weak. Therefore, in some specific embodiments, the metal nanowire layer is a silver nanowire layer.

[0046] In some of these embodiments, the two-dimensional graphite material layer is a two-dimensional graphite material layer formed by at least one of two-dimensional materials of carbon elements such as graphene and graphdiyne. In some of these embodiments, the two-dimensional graphite material layer includes at least one of a graphene material layer and a graphdiyne material layer. In some specific embodiments, the two-dimensional graphite material layer is any one of a graphene material layer and a graphdiyne material layer. Among them, graphene and graphdiyne are allotropes composed of carbon elements. Their special structures and the connection methods between carbon atoms determine that both have good electrical conductivity and thermal conductivity. The carbon atoms in graphene are connected by covalent bonds, while the carbon atoms in graphdiyne are connected by π bonds to form a π electron cloud, and electrons can freely conduct in GDY, having good electrical conductivity and thermal conductivity.

[0047] In some of these embodiments, the nano metal oxide layer is a nano metal oxide layer formed by at least one of nano zinc oxide and nano aluminum oxide. In some of these embodiments, the nano metal oxide layer includes at least one of a nano zinc oxide layer and a nano aluminum oxide layer. In some of these embodiments, the nano metal oxide layer is any one of a nano zinc oxide layer and a nano aluminum oxide layer. Nano zinc oxide and nano aluminum oxide have good heat conduction performance due to their unique size effect and interface characteristics. Their small size, large specific surface area, and a large number of interfaces provide more heat transfer channels, thus improving the heat conduction efficiency.

[0048] Reference Figure 1 and Figure 2, in some embodiments, the nano-metal oxide layer 230 is on the side of the metal nanowire layer 210 close to the base layer 100, that is, the electrothermal film includes, in sequence, the base layer 100, the nano-metal oxide layer 230, the metal nanowire layer 210, the two-dimensional graphite material layer 220, and the oxygen barrier layer 300. In other embodiments, the nano-metal oxide layer 230 is on the side of the two-dimensional graphite material layer 220 close to the oxygen barrier layer 300, that is, the electrothermal film includes, in sequence, the base layer 100, the metal nanowire layer 210, the two-dimensional graphite material layer 220, the nano-metal oxide layer 230, and the oxygen barrier layer 300.

[0049] Among them, the thermal and electrical conductivity within the sheets of the two-dimensional sheet-structured graphite material is very strong, but the interaction force between the sheets is weak, and the thermal and electrical conductivity is poor. And there is no confinement problem in the metal nanowire layer. Therefore, through the design of the above structure, the nano-metal oxide layer is closer to the base layer than the two-dimensional graphite material layer. In this way, when the two-dimensional graphite material layer is combined with the nano-metal oxide layer, the two-dimensional sheets of the two-dimensional graphite material layer will fill in the metal nanowire network to form an effective composite conductive network. At the same time, the nano-metal oxide for further improving the thermal conductivity performance can be either close to or far from the base layer. The electrothermal film obtained in the above manner can take into account high thermal stability, low film resistance, and high light transmittance.

[0050] In some embodiments, the oxygen barrier layer includes an optional material that can isolate oxygen to avoid oxidation. In some embodiments, the oxygen barrier layer includes an optional material that can isolate oxygen to avoid oxidation. In some embodiments, the oxygen barrier layer includes an optional material that can enhance the adhesion between the base layer and the conductive layer. In some specific embodiments, the raw material of the oxygen barrier layer includes polyvinyl alcohol.

[0051] In some embodiments, referring to Figure 3 , the conductive layer 200 is also connected to an electrode 400. In some specific embodiments, the electrode 400 is made of a conductive paste, such as silver paste. In some embodiments, the electrode 400 is located on the side of the conductive layer 200 away from the base layer 100. Therefore, when the conductive layer includes, in sequence, the metal nanowire layer, the two-dimensional graphite material layer, and the nano-metal oxide layer, the electrode layer is located on the side of the nano-metal oxide layer away from the two-dimensional graphite material layer; when the conductive layer includes, in sequence, the nano-metal oxide layer, the metal nanowire layer, and the two-dimensional graphite material layer, the electrode layer is located on the side of the two-dimensional graphite material layer away from the metal nanowire layer. In some other embodiments, the electrode 400 may be located at other positions of the conductive layer.

[0052] In a second aspect of the present application, a method for preparing an electrothermal film is provided. In some embodiments, the method for preparing the electrothermal film includes the following steps:

[0053] Coat a metal nanowire paste on the base layer to form a first composite substrate containing a wet film of metal nanowires;

[0054] Coat a two-dimensional graphite paste on the first composite substrate to form a second composite substrate containing a wet film of two-dimensional graphite material;

[0055] Coat a nano metal oxide paste on the second composite substrate to form a third composite substrate containing a wet film of nano metal oxide;

[0056] Anneal the third composite substrate to form a fourth composite substrate;

[0057] Coat an oxygen barrier layer paste on the fourth composite substrate to make an electrothermal film.

[0058] In some other embodiments, the preparation method of the electrothermal film includes the following steps:

[0059] Coat a nano metal oxide paste on the base layer to form a first composite substrate containing a wet film of nano metal oxide;

[0060] Coat a metal nanowire paste on the first composite substrate to form a second composite substrate containing a wet film of metal nanowires;

[0061] Coat a two-dimensional graphite material paste on the second composite substrate to form a third composite substrate containing a wet film of two-dimensional graphite material;

[0062] Anneal the third composite substrate to form a fourth composite substrate;

[0063] Coat an oxygen barrier layer paste on the fourth composite substrate to make an electrothermal film.

[0064] In some of these embodiments, the coating methods of the paste when forming the first composite substrate, the second composite substrate, the third composite substrate, and the electrothermal film can be independently selected from at least one of inclined plate coating, curtain coating, slot coating, roller printing, gravure coating, spin coating, etc. In some specific embodiments, the coating methods of the paste when forming the first composite substrate, the second composite substrate, the third composite substrate, and the electrothermal film are spin coating. By spin coating, the nano metal oxide, metal nanowires, two-dimensional graphite material, and oxygen barrier material in the paste are more evenly distributed on the substrate, which is beneficial to the performance of a series of properties such as thermal stability, resistance, and light transmittance.

[0065] In some specific embodiments, the base layer is subjected to plasma surface treatment. By plasma treatment, the wettability and adhesion of the base layer surface can be changed, while avoiding affecting other properties of the base layer.

[0066] In the third aspect of the embodiments of the present application, a heating method for the surface of a device is provided. The heating method includes attaching an electrothermal film to the surface of the device and energizing the conductive layer for heating. Specifically, referring to Figure 3 , the base layer 100 of the electrothermal film is attached to the surface of the substrate 500 of the device to be heated, and then the conductive layer 200 is energized for heating through the electrode 400.

[0067] In some embodiments, the device can be any substance with a certain surface, such as a medical device, a camera, a sensor, a window glass, etc.

[0068] In the fourth aspect of the embodiments of the present application, a device is provided. The device includes the electrothermal film of any of the foregoing. The device can be at least one of a medical device, a camera, a sensor, a window glass, etc., which has a heating requirement.

[0069] Example 1

[0070] This example provides an electrothermal film, and a variety of different solutions are involved in its preparation process, as follows:

[0071] An ethanol solution of silver nanowires (AgNW), the diameter of AgNW is 50 nm, the length is 20 - 60 μm, the original solution concentration of AgNW is 20 mg / mL, and it is diluted 10 times before use.

[0072] An aqueous solution of graphdiyne (GDY), the original solution concentration of GDY is 10 mg / mL, and it is diluted 20 times before use.

[0073] Nanometer zinc oxide (ZnO) is a saturated ethanol solution. Polyvinyl alcohol (PVA) is a saturated aqueous solution.

[0074] The preparation method of the electrothermal film includes the following steps:

[0075] (1) The PET substrate that is opaque to visible light and transparent to near-infrared light (purchased from Dongguan Haiyue Plastic Co., Ltd., model HYM-HS) is set at a power of 600 W in a plasma surface treatment device (PlasmaBeam STANDARD) and subjected to plasma cleaning at a speed of 300 mm / s to change the wettability and adhesion of the PET substrate surface.

[0076] (2) The cleaned PET substrate is placed in a spin coating device, and the ethanol solution of AgNW is dropped, and spin-coated at a speed of 1000 rpm for 5 s. After the solvent volatilizes, the ethanol solution of AgNW is spin-coated continuously until the thickness of the wet film is 50 nm, forming a PET / AgNW wet film.

[0077] (3) Spin-coat and drop an aqueous solution of GDY on the PET / AgNW film at a speed of 1200 rpm for 4 s to make the thickness of the coating 20 nm. Repeat the above steps 3 times to form a PET / AgNW / GDY wet film.

[0078] (4) Drop ZnO ethanol solution on the surface of PET / AgNW / GDY and spin-coat it at a speed of 1000 rpm for 5 s until the thickness of the wet film reaches 20 nm to form a PET / AgNW / GDY / ZnO wet film.

[0079] (5) Anneal the PET / AgNW / GDY / ZnO wet film sample at 120 °C for 20 min to obtain a PET / AgNW / GDY / ZnO thin film.

[0080] (6) Test the transmittance and sheet resistance of the PET / AgNW / GDY / ZnO thin film.

[0081] (7) Screen-print silver paste electrodes at both ends of the PET / AgNW / GDY / ZnO thin film with silver paste.

[0082] (8) Continuously coat a saturated aqueous solution of PVA on the silver paste electrodes and the PET / AgNW / GDY / ZnO thin film. Wait for the water to evaporate to obtain a PET / AgNW / GDY / ZnO / PVA near-infrared transparent electrothermal film.

[0083] Example 2

[0084] This example provides an electrothermal film. The difference from Example 1 is that this electrothermal film is a PET / ZnO / AgNW / GDY / PVA near-infrared transparent electrothermal film, that is, ZnO ethanol solution is first spin-coated on the PET substrate.

[0085] Comparative Example 1

[0086] This comparative example provides an electrothermal film. The difference from Example 1 is that this electrothermal film is a PET / GDY / AgNW / ZnO / PVA near-infrared transparent electrothermal film, that is, the spin-coating order of the AgNW ethanol solution and the GDY aqueous solution is swapped.

[0087] Comparative Example 2

[0088] This comparative example provides an electrothermal film. The difference from Example 1 is that this electrothermal film is a PET / AgNW / ZnO / GDY / PVA near-infrared transparent electrothermal film, that is, the spin-coating order of the ZnO ethanol solution and the GDY aqueous solution is swapped.

[0089] Comparative Example 3

[0090] This comparative example provides an electrothermal film, which is different from Example 1 in that the electrothermal film is a PET / AgNW+ZnO+GDY / PVA near-infrared transparent electrothermal film, that is, a mixed solution of AgNW, ZnO, and GDY is spin-coated on a PET substrate.

[0091] Example 3

[0092] The sheet resistance and light transmittance of the electrothermal films of Examples 1-2 and Comparative Examples 1-3 were measured in step (6) (before printing the silver paste electrode and the PVA oxygen barrier layer) during the preparation process. The specific method is as follows:

[0093] For the sheet resistance, it was measured by the four-probe method. The specific steps are as follows:

[0094] Turn on the power of the four-probe tester. After preheating for 30 minutes, select the "sheet resistance test" mode. Place the thin film sample on the test table, hold the tester, and gently press the 4 probe heads on the sample surface to ensure good contact between the probes and the sample. Wait for a period of time, and the device will automatically calculate and display the sheet resistance value.

[0095] For the light transmittance, the test method is as follows:

[0096] Turn on the power of the light transmittance tester and perform automatic calibration; place the thin film sample in the measurement area of the instrument, ensure that the sample is flat and closely adheres to the measurement area; start the test program, and the instrument will perform a light transmittance test on the thin film, and record the light transmittance test value at a wavelength of 940 nm.

[0097] The thermal stability of the finished electrothermal films of Examples 1-2 and Comparative Examples 1-3 was detected respectively. The specific method is as follows:

[0098] Connect the electrothermal film to a DC power supply and place it under an infrared thermal imager; set the shooting interval time of the infrared thermal imager to 10 s, and adjust the power supply voltage to 8-12 V; observe and record the temperature change of the electrothermal film during the heating stage (Examples 1-2, heating to 60 °C for 30 s at 8 V, heating to 80 °C for 20 s at 10 V, heating to 95 °C for 20 s at 12 V; Comparative Examples 1-2, heating to 58 °C and 44 °C respectively for 30 s at 8 V, heating to 75 °C and 56 °C respectively for 20 s at 10 V, heating to 90 °C and 72 °C respectively for 20 s at 12 V). Repeat the test, gradually increase the voltage (8 V - 12 V), observe the change trend of the temperature and the required time. If the required time to heat to the same temperature increases by 2 times, it is considered that the thermal stability is poor.

[0099] The detection results of thermal stability, sheet resistance, and light transmittance are shown in the following table.

[0100] Table 1. Detection Results

[0101] Group Thermal stability Sheet resistance (Ω / □) Light transmittance (%) Example 1 OK 50 85 Example 2 OK 50 85 Comparative example 1 OK 57 85 Comparative example 2 OK 88 84 Comparative example 3 NG Non-uniform Non-uniform

[0102] As can be seen from the results in the table, Examples 1 and 2 have good thermal stability, low sheet resistance, and a light transmittance of not less than 85% for near-infrared light. In contrast, in Comparative Example 1, the order of silver nanowires and graphdiyne was swapped, resulting in a significant increase in sheet resistance; in Comparative Example 2, the order of zinc oxide and graphdiyne was swapped, not only causing a very significant increase in sheet resistance but also a decrease in light transmittance; in Comparative Example 3, silver nanowires, graphdiyne, and zinc oxide were mixed and coated, resulting in poor thermal stability and significant non-uniformity in both sheet resistance and light transmittance.

[0103] Regarding the above experimental results, the analysis is as follows:

[0104] Graphdiyne is a graphite material with a two-dimensional sheet structure. The confinement effect it has makes the thermal and electrical conductivity within the sheets very strong, but the interaction force between the two-dimensional sheets is weak, which restricts the exertion of thermal and electrical conductivity. However, silver nanowires do not have the confinement problem. Therefore, the two-dimensional sheets of graphdiyne can be filled between the silver nanowire networks to form an effective composite conductive network. For this reason, considering the relationship with the base layer, a structure with a silver nanowire layer first and then a graphdiyne layer in the stacking order is adopted, so that graphdiyne fills the gaps between the silver nanowires. And nano-zinc oxide can be close to or far from the base layer, thus obtaining the AgNW / GDY / ZnO composite structure of Example 1 or the ZnO / AgNW / GDY composite structure of Example 2.

[0105] For the silver nanowire solution and the graphdiyne solution, their solvents are different, and mixing will cause the AgNW to agglomerate and settle. Even if the same general solvent is used, the difference in their densities may cause them to stratify, so they cannot be used after mixing. Therefore, if a ZnO layer is stacked on a mixed layer of AgNW and GDY, or the three are directly mixed, it will result in the inability to coat a uniform thin film after the material settles, causing non-uniform problems in the thermal stability, chemical stability, mechanical stability, film layer resistance, light transmittance, haze, etc. of the electrothermal film.

[0106] If a structure with ZnO sandwiched in the middle, such as the GDY / ZnO / AgNW or AgNW / ZnO / GDY structure, is adopted, it will cause the AgNW and GDY to not form an effective composite, resulting in a decrease in conductivity. And if, contrary to Example 1, GDY / AgNW / ZnO is stacked adjacent to each other, it will cause the GDY on one side to not be filled into the AgNW network, and the composite performance cannot be fully exerted.

[0107] Combining the above results, the electrothermal films with the ZnO / AgNW / GDY and AgNW / GDY / ZnO stacking structures in Examples 1 and 2 have the best thermal stability, in-plane sheet resistance, and light transmittance.

[0108] Analyze the above experimental results. For example, Examples 1-2 have lower sheet resistance compared to Comparative Examples 1-2. Therefore, the voltage required to heat the electrothermal film to the same temperature is lower, and it can be used at a low voltage. The composite structure of silver nanowires and graphdiyne has better conductivity than the single silver nanowire structure. Thus, less conductive material is required at the same sheet resistance, so the amount of silver nanowires can be reduced, and the haze can be decreased. In addition, due to the use of a specific substrate material, the visible light transmittance of the electrothermal film can be less than 4%, and it has certain insulation performance, voltage resistance, and durability, thereby protecting the conductive material inside and making the electrothermal film safe and reliable. Moreover, the good conductivity of the conductive material also results in a lower resistance and a faster heating rate.

[0109] Example 4

[0110] The reliability of the electrothermal films obtained in Examples 1-2 was detected respectively. The specific test process and results are as follows:

[0111] Reliability test: The electrothermal film was continuously operated for 1000 hours at a DC voltage of 12V in different working environments, and the changes in resistance value and light transmittance of the electrothermal film before and after operation were detected. Among them, the resistance value is the resistance value between the two terminals of the electrothermal film, and the initial terminal resistance is 20Ω. Among them, different working environments include high temperature and high humidity, simulated outdoor conditions, and indoor environment. Refer to "JG / T 286-2010 Low Temperature Radiation Electrothermal Film".

[0112] Combined with Figure 4 and Figure 5 , the results show that in the high temperature and high humidity environment, the change in the resistance value of the electrothermal film is small (about 10%), the light transmittance has no change, and the heating is uniform. Under simulated outdoor conditions, the change in the resistance value of the electrothermal film is small (about 6%), the light transmittance has no change, and the heating is uniform. Under indoor environmental conditions, the change in the resistance value of the electrothermal film is small (about 5%), the light transmittance has no change, and the heating is uniform.

[0113] The above has described the present application in detail in combination with the embodiments. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the present application. In addition, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

Claims

1. Electric heating film, characterized in that, The invention comprises a base layer, a conductive layer and an oxygen-isolating layer arranged in sequence, wherein the conductive layer comprises a metal nanowire layer, a two-dimensional graphite material layer and a nano-metal oxide layer, wherein the two-dimensional graphite material layer is on a side of the metal nanowire layer away from the base layer; the nano-metal oxide layer is on a side of the metal nanowire layer close to the base layer, or the nano-metal oxide layer is on a side of the two-dimensional graphite material layer close to the oxygen-isolating layer.

2. The electric heating film according to claim 1, characterized in that: The metal nanowire layer is any one of a gold nanowire layer, a silver nanowire layer and a copper nanowire layer.

3. The electric heating film according to claim 1, characterized in that: The two-dimensional graphite material layer is any one of a graphene material layer and a graphyne material layer.

4. The electric heating film according to claim 1, characterized in that: The nano metal oxide layer is any one of a nano zinc oxide layer and a nano aluminum oxide layer.

5. The electric heating film according to claim 1, characterized in that: The base layer is a polyethylene terephthalate layer.

6. The electric heating film according to claim 1, characterized in that: The oxygen barrier layer is a polyvinyl alcohol layer.

7. The electric heating film according to claim 1, characterized in that: The conductive layer is also connected to an electrode.

8. The electric heating film according to claim 1, characterized in that: The thickness of the electric heating film is 1 μm to 1 cm.

9. The electric heating film according to claim 1, characterized in that: The thickness of the base layer is 1 μm to 1 mm.

10. The device, characterized in that The invention comprises the electric heating film according to any one of claims 1 to 7.

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