Thin film heater with curved surface shape and preparation method thereof

Abstract

The present application discloses a thin film heater with a curved surface shape and a preparation method thereof, wherein a silver nanowire functional body is arranged on the surface of a base device, the silver nanowire functional body includes multiple silver nanowire layers, the silver nanowire layers include silver nanowires arranged in parallel, the outer surface of the multiple silver nanowire layers is provided with a wrapping layer formed by active metal oxide nanoparticles, and the multiple silver nanowire layers are stacked; the thin film heater with a curved surface shape provided by the present invention and a preparation method thereof, the silver nanowires in the silver nanowire layer are arranged in parallel, the wire-wire nodes are few, the light transmission characteristics are enhanced, and the active metal oxide nanoparticles modify the wire-wire nodes between the silver nanowires and wrap the silver nanowires, so that the wire-wire nodes between the silver nanowires are in close contact, thereby reducing the node resistance.

Description

Technical Field

[0001] The present invention relates to the field of thin film heaters, and in particular to a thin film heater with a curved surface shape and a preparation method thereof. Background Art

[0002] Transparent heaters (THs) refer to visually transparent (conductive layer transparent) heating devices. When current flows through the transparent conductive layer, heat is generated due to the Joule heating effect. Transparent heaters have the advantages of high heat generation rate, low voltage, low thermal inertia, and environmental value. Transparent heaters can be used in smart windows, deicing, defogging, displays in extremely cold areas, thermotherapy pads, sensors and other device structures. They are worthy of promotion and have become one of the fastest growing markets. Especially in the field of inorganic materials such as electrothermal ceramics or glass, they can achieve functions such as disinfection and heat preservation of ceramics or glassware, which upgrades the traditional ceramic industry and increases the added value of products, thus having significant research and application significance.

[0003] The first generation of THs technology is based on transparent conductive oxides (TCOs), such as indium tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide, as the conductive layer materials of THs. However, due to the brittleness of TCOs and their low optical transmittance in the near-infrared spectrum, the demand for a new generation of THs with better optical transparency, conductivity, and flexibility has arisen.

[0004] Silver nanowire transparent conductive films (AgNWs-TCFs) offer high electrical conductivity, high light transmittance, low haze, low-temperature deposition, strong substrate bonding, and high thermal conductivity, making them particularly advantageous as transparent heaters. Patent CN104053256A utilizes silver nanowires synthesized by a low-temperature liquid phase method, coating the transparent conductive film with a molding process. This process utilizes a mature and commercially available conductive polymer to improve heating uniformity, and a thin protective film is obtained by liquid-phase coating with an inexpensive organic polymer film. However, the resulting film exhibits poor transmittance, the cost of sputtered electrodes is high, the contact resistance of adhesive electrodes is high, and the film is unsuitable for curved, electrically heated ceramic tableware and tea sets.

[0005] The main problems with silver nanowire-based transparent thin-film heaters currently fabricated by spin coating, blade coating, and spray coating methods include weak bonding between the silver nanowires in the resulting conductive network, high contact resistance, uneven resistance distribution, and low failure voltage. Furthermore, the weak bonding between the silver nanowires and the substrate makes them more susceptible to corrosion in the natural environment, resulting in deteriorated conductivity and transmittance of the overall conductive network. Furthermore, spin coating and blade coating are not suitable for curved substrates. Finding a method to improve these deficiencies would be of great value for upgrading the traditional ceramic industry. Summary of the Invention

[0006] The main purpose of the present invention is to provide a thin film heater with a curved surface shape and a preparation method thereof, aiming to solve the problems in the silver nanowire conductive network, such as weak bonding between silver nanowires, high contact resistance, uneven resistance distribution, and low failure voltage; weak bonding between silver nanowires and the substrate, which is more susceptible to environmental corrosion, resulting in deterioration of the conductivity and transmittance of the overall conductive network, and difficulty in processing on a curved substrate device.

[0007] To achieve the above-mentioned object, a first aspect of the present invention is to provide a thin film heater having a curved surface, for bonding to a surface of a base device, comprising:

[0008] A silver nanowire functional body is disposed on the surface of the base device, the silver nanowire functional body comprising a wrapping layer and a plurality of silver nanowire layers, the silver nanowire layers comprising silver nanowires arranged in parallel, the wrapping layer formed of active metal oxide nanoparticles being disposed on the outer surface of the plurality of silver nanowire layers as a whole, wherein the plurality of silver nanowire layers are stacked;

[0009] The waterproof packaging layer is combined with the outer side of the silver nanowire functional body.

[0010] Furthermore, the silver nanowires in the silver nanowire layer have an average diameter of 10 to 60 nm and an average length of 10 to 60 μm.

[0011] Furthermore, there are a plurality of silver nanowire layers, and the silver nanowire groups in adjacent silver nanowire layers are arranged in parallel or perpendicularly.

[0012] The present invention also provides a method for preparing a thin film heater having a curved surface shape, comprising:

[0013] S1. preparing a silver nanowire dispersion in a thick state, wherein the silver nanowire dispersion in a thick state is determined by rheological property testing. If the viscosity coefficient of the silver nanowire dispersion first increases and then decreases over time, it is in a thick state;

[0014] S2, placing the substrate into a concentrated silver nanowire dispersion, driving the silver nanowire dispersion to complete a preset rotation state, forming a wet film of the silver nanowire dispersion on the substrate, and then removing the substrate and drying it to obtain a silver nanowire layer;

[0015] S3, completing the silver nanowire layer preparation process for a preset number of times, thereby obtaining a silver nanowire functional body;

[0016] S4, processing a wrapping layer on the outer surface of the nanowire functional body, wherein the wrapping layer is a layer structure formed by active metal oxide nanoparticles;

[0017] S5. Processing a waterproof packaging layer on the outer side of the silver nanowire functional body.

[0018] Furthermore, the preset rotation state includes an early low-speed stirring process of 400-600 rpm and a later high-speed stirring process of 1000-1200 rpm. The stirring intensity during the high-speed stirring process is 2 to 3 times that of the low-speed stirring process. During the low-speed stirring process, the silver nanowire dispersion is in a laminar state.

[0019] Furthermore, the preset number of times in step S3 is greater than or equal to two times, and the angle of the base device is adjusted so that the silver nanowires between adjacent silver nanowire layers are arranged at an angle of 30 to 90 degrees.

[0020] Furthermore, the step S2 includes:

[0021] Place the substrate into the concentrated silver nanowire dispersion and use a magnetic stirrer to drive the silver nanowires to disperse.

[0022] The nanowire dispersion liquid is rotated at a low speed of 400-600 rpm for 8 seconds, and then at a high speed of 1000-1200 rpm for 30 seconds to complete the preset rotation state. After a wet film of the silver nanowire dispersion liquid is formed on the substrate, the substrate is taken out and dried to obtain a silver nanowire layer.

[0023] Furthermore, the silver nanowires dispersed in the silver nanowire dispersion have an average diameter of 10 to 60 nm and an average length of 10 to 60 μm, and the mass concentration of the silver nanowires in the silver nanowire dispersion is 1.0 to 4.0 mg / ml.

[0024] 0 Further, in step S4, the processing method of the wrapping layer is magnetron sputtering.

[0025] Furthermore, the waterproof encapsulation layer 300 includes a waterproof layer and an encapsulation layer attached to the outer surface of the waterproof layer. In the step S5, the waterproof layer is processed by coating and then drying, and the encapsulation layer is processed by magnetron sputtering.

[0026] The beneficial effects of the present invention are: 5(1) The directional arrangement of AgNWs in the present invention as a conductive layer can effectively reduce the square resistance of the thin film heater and has good transparency.

[0027] (2) The present invention controls the magnetron sputtering process to modify the wire-wire junctions between silver nanowires and wrap the silver nanowires with active metal oxide nanoparticles sputtered from the metal oxide target.

[0028] The surface makes the wire-wire nodes between the silver nanowires in close contact, further reduces the node resistance, improves the uniformity of the resistance distribution, and on the other hand can improve the weather resistance of the silver nanowire conductive layer.

[0029] (3) The present invention adopts a method of testing the rheological properties of the dispersion to quantitatively define the viscosity of the silver nanowire dispersion, providing operability for the prerequisite of preparing a transparent conductive film with directional arrangement of silver nanowires.

[0030] (4) The present invention uses the shear force generated by the rotation of the dispersion to prepare a transparent conductive film of directionally arranged silver nanowires on the surface of a curved substrate. The method has strong operability and the preparation method is compatible with industrialization.

[0031] (5) The present invention adopts a waterproof oxidation reaction protective layer composed of a waterproof layer and a metal oxide encapsulation layer, so that the electric heating performance of the electric heating ceramic tableware and tea set will not deteriorate for a long time.

[0032] (6) The heater of the present invention has a simple structure and a simple preparation process, which is conducive to large-scale production; it has the advantages of a load voltage of less than 7V, a fast heating rate, high heating efficiency, and high safety, while not affecting the original pattern and color of the base device. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is an analysis of the rheological properties of silver nanowire dispersions of different concentrations of the present invention;

[0034] Figure 2 is a schematic cross-sectional view of a thin film heater having a curved surface according to a second embodiment of the present invention;

[0035] Figure 3 The second embodiment of the present invention is a load stability analysis of a thin film heater with a curved surface on a substrate.

[0036] Figure 4 The light transmittance analysis of the thin film heater having a curved surface shape according to the second embodiment of the present invention is as follows;

[0037] Figure 5 This is a weather resistance analysis of a thin film heater having a curved surface shape according to a second embodiment of the present invention;

[0038] Figure 6 This is a conceptual diagram of the manufacturing process of a thin film heater with a curved surface shape according to the third embodiment of the present invention.

[0039] Figure 7 FIG. 1 is a scanning electron microscope analysis of a thin film heater with a curved surface according to the third embodiment of the present invention.

[0040] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0041] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] Those skilled in the art will understand that, unless otherwise stated, the singular forms "a", "an", "said", "above", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the stated features, integers, steps, operations, elements, units, modules, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, units, modules, components, and / or groups thereof. The term "and / or" used herein includes all or any units and all combinations of one or more associated listed items.

[0043] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0044] The present invention provides a thin film heater having a curved surface, which is used to be bonded to the surface of a base device 100, comprising:

[0045] A silver nanowire functional body 200 is disposed on the surface of the base device 100. The silver nanowire functional body 200 includes a wrapping layer 211 and multiple silver nanowire layers 210. The silver nanowire layers 210 include silver nanowires arranged in parallel. The outer surface of the multiple silver nanowire layers 210 is provided with the wrapping layer 211 formed of active metal oxide nanoparticles. The multiple silver nanowire layers 210 are stacked.

[0046] A waterproof encapsulation layer 300 is formed on the outside of the silver nanowire functional body 200 and is a waterproof organic layer 310 formed by spin coating and a metal oxide encapsulation layer 320 formed by magnetron sputtering;

[0047] The electrode layer 400 is prepared by evaporating a metal film and is located on the outside of the waterproof packaging layer 300. In different embodiments, the electrode layer 400 can be processed in various ways.

[0048] In the existing technology, the main problems of silver nanowire-based transparent thin film heaters prepared by common methods such as spin coating, scraping, and spraying are that the bonding force between the silver nanowires in the prepared silver nanowire conductive network is weak, there is a high contact resistance, uneven resistance distribution, and a low failure voltage; the bonding force between the silver nanowires and the substrate is weak, and the silver nanowires are more susceptible to corrosion in the natural environment, resulting in deterioration of the conductivity and transmittance of the overall conductive network, and the spin coating and scraping methods are not suitable for substrate devices with curved surfaces.

[0049] In the present invention, the silver nanowire layer 210 includes silver nanowires arranged in parallel. Due to this parallel arrangement, the silver nanowires are arranged more regularly, with fewer wire-to-wire junctions and enhanced light transmission. Active metal oxide nanoparticles modify the wire-to-wire junctions between the silver nanowires and encapsulate the silver nanowires, ensuring close contact between the wire-to-wire junctions and further reducing junction resistance. The active metal oxide can be ZnO or SnO2, for example. The number of silver nanowire layers 210 is not limited to one, and the arrangement of the silver nanowires in each silver nanowire layer 210 is not limited to parallel. The term "parallel arrangement" within the silver nanowire layer 210 refers to the tendency of the numerous silver nanowires within the silver nanowire layer 210 to be arranged in parallel, and is not limited to being completely parallel, which is not achievable in practice. The waterproof encapsulation layer 300 isolates the silver nanowire functional body 200 from the external environment, reducing environmental interference with the silver nanowire functional body 200 and ensuring long-term degradation of the thin film heater's electrical and thermal performance. It also enhances the bonding between the silver nanowire functional body 200 and the base device 100. The electrode layer 400 can be formed by evaporating a metal thin film.

[0050] In summary, the silver nanowires in the silver nanowire layer 210 are arranged in parallel, with fewer wire-wire junctions and enhanced light transmittance. The active metal oxide nanoparticles modify the wire-wire junctions between the silver nanowires and wrap the silver nanowires, so that the wire-wire junctions between the silver nanowires are in close contact, thereby reducing the node resistance. The waterproof encapsulation layer 300 serves to separate the silver nanowire functional body 200 from the external environment, thereby reducing interference from the external environment on the silver nanowire functional body 200. It can also enhance the bonding effect between the silver nanowire functional body 200 and the base device 100, thereby preventing the electrothermal performance of the thin film heater from degrading over a long period of time.

[0051] In one embodiment, the silver nanowires in the silver nanowire layer 210 have an average diameter of 10 to 60 nm and an average length of 10 to 60 μm.

[0052] In this embodiment, the size characteristics of the silver nanowires have good electrical and thermal properties, and in the process of preparing the suspension, good dispersion effect and viscosity characteristics can be achieved, which will be described in detail in the subsequent preparation method examples.

[0053] In one embodiment, there are multiple silver nanowire layers 210 , and the silver nanowire groups in adjacent silver nanowire layers 210 are arranged in parallel or perpendicular to each other.

[0054] Without the wrapping layer 211, the silver nanowire layer 210 has many junctions between wires, resulting in high contact resistance, uneven resistance distribution, and weak bonding between the silver nanowires, which can also lead to low failure voltage. In the present invention, the silver nanowire layer 210 includes a group of silver nanowires arranged in parallel. Due to the parallel arrangement, the silver nanowires are arranged more regularly, with fewer wire-to-wire junctions, and enhanced light transmission properties. Active metal oxide nanoparticles modify the wire-to-wire junctions between the silver nanowires and wrap the silver nanowires, ensuring close contact between the wire-to-wire junctions and further reducing junction resistance. Due to these improved properties, the number of silver nanowire layers 210 can be increased to increase the overall thickness of the silver nanowire functional body 200. It is even possible to arrange the silver nanowires in adjacent silver nanowire layers 210 at perpendicular angles, thereby improving the bonding between the silver nanowire layers 210 and ensuring electrical performance.

[0055] In one embodiment, the waterproof encapsulation layer 300 is composed of a waterproof layer 310 and an encapsulation layer 320 , wherein the waterproof layer 310 is formed by spin coating a layer of organic waterproof material, and the encapsulation layer 320 is formed by magnetron sputtering a layer of metal oxide.

[0056] The function of the encapsulating waterproof layer 300 is to isolate the silver nanowire functional body 200 from the external environment, reducing external interference with the silver nanowire functional body 200; it also enhances the bonding between the silver nanowire functional body 200 and the base device 100. In this embodiment, the waterproof layer 310 can be made of polyethylene oxide, polyethersulfone, polyimide, polyester, etc., and the encapsulating layer 320 can be made of aluminum oxide, zirconium oxide, silicon oxide, etc. It should be noted that the waterproof layer 310 is simple to manufacture and acts as a buffer for the encapsulating layer 320. The encapsulating layer 320 also provides excellent hygienic conditions and service conditions.

[0057] The present invention also provides a method for preparing a thin film heater having a curved surface shape, comprising:

[0058] S1. preparing a silver nanowire dispersion in a thick state, wherein the silver nanowire dispersion in a thick state is determined by rheological property testing. If the viscosity coefficient of the silver nanowire dispersion first increases and then decreases over time, it is in a thick state;

[0059] S2. Placing the substrate 100 into the concentrated silver nanowire dispersion and driving the silver nanowire dispersion to complete a preset rotation state. After a wet film of the silver nanowire dispersion is formed on the substrate 100, the substrate 100 is removed and dried to obtain the silver nanowire layer 210. The preset rotation state is: initially stirring with a low speed of 400-600 rpm for 8 seconds, followed by stirring with a high speed of 1000-1200 rpm for 30 seconds.

[0060] S3, completing the silver nanowire layer 210 preparation process for a preset number of times, thereby obtaining the silver nanowire functional body 200;

[0061] S4, processing a wrapping layer 211 on the outer surface of the nanowire functional body, wherein the wrapping layer 211 is a layer structure formed by active metal oxide nanoparticles;

[0062] S5. Processing a waterproof encapsulation layer 300 on the outer side of the silver nanowire functional body 200. The waterproof encapsulation layer 300 consists of a waterproof layer 310 and an encapsulation layer 320. The waterproof layer 310 is formed by spin coating an organic waterproof material, and the encapsulation layer 320 is formed by magnetron sputtering a layer of metal oxide.

[0063] In the present invention, the dispersion medium for the silver nanowire dispersion can be an organic solvent such as an alcohol or ketone, or a polar aqueous dispersion medium. However, alcohol or ketone organic solvents are preferred, as they provide better dispersion of the silver nanowires. The substrate 100 can be thoroughly cleaned in various polar and non-polar solvents to ensure surface cleanliness. In practice, the substrate 100 can be ultrasonically treated in acetone, ethanol, and deionized water to complete the cleaning process. The present invention imposes specific restrictions on the concentration of the silver nanowire dispersion; during the shear coating process, the rotational state of the silver nanowire dispersion is also subject to corresponding restrictions. Experimental verification shows that, due to the prominent steric hindrance effect of a concentrated silver nanowire dispersion, when stirred, the silver nanowires exhibit a significant directional alignment effect in the direction of the silver nanowire dispersion's rotational speed. Specifically, a concentrated silver nanowire dispersion is used. Compared to a diluted or semi-diluted silver nanowire dispersion that has not yet reached a concentrated state, in the concentrated silver nanowire dispersion, the silver nanowires in the silver nanowire dispersion are regularly arranged in the direction of the entire silver nanowire dispersion's rotational flow in order to reduce the steric hindrance effect. During implementation, the appropriate concentration characterization method for the silver nanowire dispersion can be to conduct a rheological property study on silver nanowire dispersions of different concentrations to analyze and obtain a silver nanowire dispersion of an appropriate concentration. Figure 1, which shows the time evolution of the liquid viscosity coefficient of silver nanowire dispersions of different concentrations. Curve A shows a monotonically decreasing evolution of the liquid viscosity coefficient over time, representing a semi-diluted silver nanowire dispersion. Curves B, C, and D show an initial increase and then a decrease in the liquid viscosity coefficient over time, representing a concentrated silver nanowire dispersion. Of course, after conducting preliminary rheological property studies, the silver nanowire dispersion of the appropriate concentration can be prepared during the production process. During the shear coating process, the silver nanowire dispersion needs to be stirred. Internal friction in the dispersion causes the silver nanowires to align in the direction of the rotational speed. The shear force generated by the high-speed rotation causes the aligned silver nanowires in the dispersion to assemble onto the surface of the substrate 100. The magnetic stirring speed is 400-1200 rpm.

[0064] It should be noted that the number of layers of the silver nanowire layer 210 can be selected according to the use environment. It is precisely because the concentration of the silver nanowire dispersion is limited and the silver nanowire dispersion is stirred during the coating process on the base device 100 that the silver nanowires in the silver nanowire dispersion wet film formed on the base device 100 have a regular arrangement effect, and the silver nanowires in the silver nanowire layer 210 are also arranged in parallel. Ultimately, the complexity of the nodes between the silver nanowires is reduced, the square resistance is low, and the transparency is good.

[0065] Assisted by the wrapping layer 211, the active metal oxide nanoparticles modify the wire-wire junctions between the silver nanowires and wrap the silver nanowires, thereby ensuring close contact between the wire-wire junctions, further reducing junction resistance and improving the uniformity of resistance distribution. Furthermore, this can enhance the weather resistance of the silver nanowires. The active metal oxide can be ZnO or SnO2. The wrapping layer 211 can be processed by magnetron sputtering or vapor deposition.

[0066] In one embodiment, the preset rotation state includes an early low-speed stirring process of 400-600 rpm and a later high-speed stirring process of 1000-1200 rpm. The stirring intensity during the high-speed stirring process is 2 to 3 times that of the low-speed stirring process. During the low-speed stirring process, the silver nanowire dispersion is in a laminar state.

[0067] In this embodiment, low-speed stirring facilitates the bonding of the silver nanowires to the substrate 100. When the silver nanowires have already bonded to the surface of the substrate 100 to a certain extent during low-speed stirring, high-speed stirring further enhances the directional alignment of the silver nanowires in the silver nanowire dispersion. Furthermore, once a certain number of silver nanowires have already been deposited on the substrate 100, even with high-speed stirring of the silver nanowire dispersion, the continued deposition of the silver nanowires on the substrate 100 remains satisfactory. It should be noted that during high-speed stirring, silver nanowires that are less firmly bonded to each other will detach, thereby ensuring, to a certain extent, a good degree of bonding of the silver nanowires on the substrate 100. For example, after using a magnetic stirrer to stir the dispersion at a low speed of 400-600 rpm for 8 seconds, it is then changed to a high speed of 1000-1200 rpm for 30 seconds, and then the base device 100 is taken out and placed on a heating table at 100°C for heat treatment for 15 minutes. After drying, this step is repeated twice to obtain two silver nanowire layers 210. The two silver nanowire layers 210 form the silver nanowire functional body 200.

[0068] In one embodiment, the high-speed stirring process lasts 2 to 20 times longer than the low-speed stirring process.

[0069] In this embodiment, the high-speed stirring process is prolonged so that the silver nanowires arranged in parallel in the silver nanowire layer 210 account for a higher proportion, and ultimately the performance of the thin film heater is better.

[0070] In one embodiment, the step S3 is performed for a preset number of times or more, and the angle of the base device 100 is adjusted so that the silver nanowires between adjacent silver nanowire layers 210 are arranged at an angle of 30 to 90 degrees.

[0071] In the present invention, the silver nanowire layer 210 comprises a group of silver nanowires arranged in parallel. Due to this parallel arrangement, the silver nanowires are more regularly arranged, with fewer wire-to-wire junctions and enhanced light transmission. Furthermore, the active metal oxide nanoparticles modify and encapsulate the wire-to-wire junctions between the silver nanowires, ensuring close contact between the wire-to-wire junctions and further reducing junction resistance. The silver nanowires in adjacent silver nanowire layers 210 are arranged at different angles, ranging from 30 to 90 degrees, to achieve different electrical properties and realize different application functions. These angles can be adjusted by adjusting the coating angle of the substrate apparatus 100.

[0072] In one embodiment, the experimental setting for the time-dependent evolution of the viscosity coefficient of the silver nanowire dispersion is as follows: a rotation speed is initially preset to a higher rotation speed, and finally to the previously preset rotation speed. The ratio of the two high and low rotation speeds in the preset rotation state is 1.1 to 1.3 times, and the duration of the preset rotation state is 5 to 20 minutes.

[0073] In this embodiment, the silver nanowire layers 210 are arranged at different angles to obtain different electrical properties of the silver nanowire functional body 200, which can realize different application functions. For example, when the silver nanowire layers 210 are arranged at zero angle, the ratio of the transverse resistance to the longitudinal resistance reaches the maximum, while when the silver nanowire layers 210 are arranged at a 90-degree angle, the ratio of the transverse resistance to the longitudinal resistance is 0.98-1.1.

[0074] In one embodiment, the silver nanowires dispersed in the silver nanowire dispersion have an average diameter of 10 to 60 nm and an average length of 10 to 60 μm, and the mass concentration of the silver nanowires in the silver nanowire dispersion is 1.0 to 4.0 mg / ml.

[0075] In the embodiments, the rheological properties of the silver nanowires are controlled by limiting their size and volume concentration within the silver nanowire dispersion, i.e., by limiting the concentration conditions where the steric hindrance effect is more pronounced. This results in a more regular alignment of the silver nanowires during stirring of the silver nanowire dispersion. Preferably, the silver nanowire dispersion is prepared using isopropyl alcohol as the solvent, with the silver nanowires having an average diameter of 30 nm and an average length of 20 μm. The silver nanowires are ultrasonically dispersed in the isopropyl alcohol solution at a concentration of 1.5 to 2.5 mg / ml.

[0076] In one embodiment, the wrapping layer 211 in step S4 is processed by magnetron sputtering.

[0077] In this embodiment, the substrate device 100 with the silver nanowire functional body 200 attached was placed in a magnetron sputtering coating machine. The target material used in the experiment was a ZnO ceramic target, the sputtering gas was Ar, the gas flow rate was 30 sccm, the sputtering power was 120 W, the pre-sputtering time was 20 min, the sputtering time was 10 min, and the background pressure in the sputtering chamber was 7.0×10 -4 Pa, and the sputtering pressure is set to 1.0 Pa. Thus, a wrapping layer 211 is processed on the surface of the silver nanowire functional body 200 .

[0078] In one embodiment, the waterproof packaging layer 300 includes a waterproof layer 310 and a packaging layer 320 attached to the outer surface of the waterproof layer 310. In the step S5, the processing method of the waterproof layer 310 is coating and then drying, and the processing method of the packaging layer 320 is magnetron sputtering.

[0079] In this embodiment, the waterproof layer 310 is dried after coating, which makes processing simple and quick; and the encapsulation layer 320 is processed on the surface of the waterproof layer 310 with high quality by magnetron sputtering, ensuring uniformity and transparency.

[0080] In one embodiment, before the step S2, an electrostatic film is formed on the surface of the base tool 100, wherein the electrostatic film is used to form electrostatic attraction with the silver nanowires.

[0081] In this embodiment, the substrate 100 was immersed in a 0.80 mg / ml polyetherimide solution for 20 minutes and then dried to form an electrostatic film. Silver nanowires, due to their nanometer size, possess negative charge. This electrostatic film on the surface of the substrate 100 creates an electrostatic attraction with the silver nanowires, enhancing the silver nanowires' adhesion.

[0082] Example 1

[0083] This embodiment provides a thin film heater with a curved surface and describes a method for manufacturing the same, which includes the following steps:

[0084] (1) Cleaning and hydrophilization of the base device 100: The base device 100 is a glass substrate with a curved surface. According to the conventional cleaning process, it is ultrasonically cleaned in acetone, ethanol, and deionized water for 30 minutes in sequence. After drying, it is placed in a UV ozone cleaning machine and treated at 60°C for 20 minutes to make the surface hydrophilic.

[0085] (2) Preparation of the silver nanowire functional body 200: Silver nanowires with an average diameter of 30 nm and an average length of 20 μm were ultrasonically dispersed in an isopropyl alcohol solution to prepare a silver nanowire dispersion with a concentration of 2.5 mg / ml. 500 ml of the silver nanowire dispersion was poured into a 1000 ml beaker with a diameter of 12.1 cm. At the same time, the glass substrate to be coated was placed in the silver nanowire dispersion and fixed. The dispersion was stirred at a low speed of 400-600 rpm for 8 seconds using a magnetic stirrer, and then at a high speed of 1000-1200 rpm for 30 seconds. The glass substrate coated with the wet film of the silver nanowire dispersion was taken out and placed on a heating table at 100°C for heat treatment for 15 minutes. After drying, this step was repeated twice to obtain two silver nanowire layers 210. The two silver nanowire layers 210 formed the silver nanowire functional body 200.

[0086] (3) Modification of the silver nanowire functional body 200 to set the wrapping layer 211: The glass container coated with the transparent conductive film of silver nanowires arranged in a directional manner was placed in a magnetron sputtering coating machine. The target material used in the experiment was a ZnO ceramic target, the sputtering gas was Ar, the gas flow rate was 30 sccm, the sputtering power was 120 W, the pre-sputtering time was 20 min, the sputtering time was 10 min, and the background pressure in the sputtering chamber was 7.0×10 -4 Pa, set the sputtering pressure to 1.0Pa.

[0087] (4) Preparation of waterproof encapsulation layer 300: A layer of polyimide with a thickness of 0.3-1 μm is coated on the surface of the sample prepared in step (3) as a waterproof layer 310, and then a layer of aluminum oxide encapsulation layer with a thickness of 0.5-1.5 μm is sputtered on the polyimide layer as an encapsulation layer 320.

[0088] Example 2

[0089] This embodiment provides a thin film heater having a curved surface shape and describes a method for manufacturing the same, which includes the following steps:

[0090] (1) Cleaning and hydrophilization treatment of the base utensil 100: The base utensil 100 is a ceramic tableware with a curved surface. According to the conventional cleaning process, it is ultrasonically cleaned in acetone, ethanol, and deionized water for 30 minutes in sequence. After drying, it is placed in a UV ozone cleaning machine and treated at 60°C for 20 minutes to make the surface hydrophilic.

[0091] (2) Preparation of the silver nanowire functional body 200: Silver nanowires with an average diameter of 30 nm and an average length of 20 μm were ultrasonically dispersed in an isopropyl alcohol solution to prepare a silver nanowire dispersion with a concentration of 2.5 mg / ml. 500 ml of the silver nanowire dispersion was poured into a 1000 ml beaker with a diameter of 12.1 cm. At the same time, the ceramic tableware and tea set to be coated was placed in the silver nanowire dispersion and fixed. The dispersion was stirred at a low speed of 400-600 rpm for 8 seconds using a magnetic stirrer, and then at a high speed of 1000-1200 rpm for 30 seconds. The ceramic tableware and tea set coated with the silver nanowire dispersion wet film was taken out and placed on a heating table at 100°C for heat treatment for 15 minutes. After drying, this step was repeated twice to obtain two silver nanowire layers 210. The two silver nanowire layers 210 formed the silver nanowire functional body 200.

[0092] (3) Modification of the silver nanowire functional body 200 to set the wrapping layer 211: The glass container coated with the transparent conductive film of silver nanowires arranged in a directional manner was placed in a magnetron sputtering coating machine. The target material used in the experiment was a SnO2 ceramic target, the sputtering gas was Ar, the gas flow rate was 30 sccm, the sputtering power was 120 W, the pre-sputtering time was 20 min, the sputtering time was 10 min, and the background pressure in the sputtering chamber was 7.0×10 -4 Pa, set the sputtering pressure to 1.0Pa.

[0093] (4) Preparation of waterproof encapsulation layer 300: A layer of polyimide with a thickness of 0.3-1 μm is coated on the surface of the sample prepared in step (3) as a waterproof layer 310, and then a layer of aluminum oxide encapsulation layer with a thickness of 0.5-1.5 μm is sputtered on the polyimide layer as an encapsulation layer 320.

[0094] (5) Heater thermal response performance test and load stabilization application: A constant voltage is input through the electrodes 400 on both sides of the heater using lead wires, and the temperature curve over time is recorded. The heater surface temperature is read by an infrared thermometer.

[0095] Reference Figure 2 , is a schematic cross-sectional view of the thin film heater having a curved shape in this embodiment.

[0096] Reference Figure 3 In sub-graphs a and c, the curves marked with circles are the test curves of the samples in this embodiment, while the curves marked with squares are the test curves of the samples without the wrapping layer 211 . Sub-graph b is the test curve of the samples in this embodiment at different voltages.

[0097] In sub-graph a, the horizontal axis is voltage and the vertical axis is current. The test curve of the sample in this embodiment shows that the failure voltage has a significant advantage; in sub-graph b, the temperature under high voltage operation is significantly higher; in sub-graph c, the test curve of the sample without the wrapping layer 211 is relatively stable in the early stage, but fails after about 6 hours, while the test curve of the sample in this embodiment remains stable. Among them, the temperature test graph in sub-graph c shows that the working temperature of the sample without the wrapping layer 211 is nearly 20 degrees lower than the working temperature of the sample in this embodiment; sub-graph d is the actual sample graph.

[0098] refer to Figure 4 , is the transmittance analysis of the thin film heater with a curved shape. The circled curve is the test curve of the sample in this embodiment, which is visible and has good transmittance. However, in other samples, when the concentration of the silver nanowire dispersion continues to increase, the transmittance performance decreases rapidly.

[0099] refer to Figure 5 , where the curve marked with circles is the test curve of the sample in this embodiment, and the curve marked with squares is the test curve of the sample without the wrapping layer 211; the left part graph shows the change in film resistivity over time, and it can be seen that the sample in this embodiment has obvious superiority in antioxidant performance; the side part graph shows the conversion rate of film resistivity with increasing temperature, and the sample in this embodiment has obvious superiority in high temperature resistance.

[0100] Example 3

[0101] This embodiment provides a thin film heater with a curved surface shape and describes its preparation method. Figure 6 This is a conceptual diagram of the steps of this embodiment, and the specific steps include:

[0102] (1) Cleaning and hydrophilization treatment of the base utensil 100: The base utensil 100 is a ceramic tableware with a curved surface. According to the conventional cleaning process, it is ultrasonically cleaned in acetone, ethanol, and deionized water for 30 minutes in sequence. After drying, it is placed in a UV ozone cleaning machine and treated at 60°C for 20 minutes to make the surface hydrophilic. The ceramic tableware is then immersed in a 0.80 mg / ml polyetherimide solution for 20 minutes and then dried.

[0103] (2) Preparation of silver nanowire functional body 200: Silver nanowires with an average diameter of 30 nm and an average length of 20 μm were ultrasonically dispersed in an isopropyl alcohol solution to prepare a silver nanowire dispersion with a concentration of 2.5 mg / ml. 500 ml of the silver nanowire dispersion was poured into a 1000 ml beaker with a diameter of 12.1 cm. The ceramic tableware to be coated was placed in the solution and fixed. The solution was rotated at 500-600 rpm using a magnetic stirrer. Figure 4 As shown, the sample is first shear-coated along the x-axis direction of the ceramic tableware for 10 minutes, then the sample is taken out and rinsed with deionized water. The rinsed substrate is placed on a heating table and heated at 90°C for 10 minutes; then the sample is flipped 90° and the above method is repeated to apply a conductive layer of silver nanowires arranged in a directional manner along the y-axis direction of the ceramic tableware.

[0104] (3) Modification of the silver nanowire functional body 200 to set the wrapping layer 211: The ceramic tableware and tea set coated with the transparent conductive film of directional silver nanowires was placed in a magnetron sputtering coating machine. The target material used in the experiment was a SnO2 ceramic target, the sputtering gas was Ar, the gas flow rate was 30 sccm, the sputtering power was 120 W, the pre-sputtering time was 20 min, the sputtering time was 10 min, and the background pressure in the sputtering chamber was 7.0×10 -4 Pa, set the sputtering pressure to 1.0 Pa. Figure 7 , part a shows a scanning electron microscope analysis of the silver nanowire functional body 200 without the wrapping layer 211, while part b shows a scanning electron microscope analysis of the embodiment in which the wrapping layer 211 is SnO2, and it can be seen that its wrapping effect is obvious.

[0105] (4) Preparation of waterproof encapsulation layer 300: A layer of polyimide with a thickness of 0.3-1 μm is coated on the surface of the sample prepared in step (3) as a waterproof layer 310, and then a layer of aluminum oxide encapsulation layer with a thickness of 0.5-1.5 μm is sputtered on the polyimide layer as an encapsulation layer 320.

[0106] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a thin film heater having a curved surface, wherein the thin film heater having a curved surface is used to be bonded to the surface of a substrate, the thin film heater having a curved surface comprising a silver nanowire functional body and a waterproof encapsulation layer; The silver nanowire functional body is arranged on the surface of the base device, and the silver nanowire functional body includes a wrapping layer and multiple silver nanowire layers. The silver nanowire layer includes silver nanowires arranged in parallel, and the outer surface of the multiple silver nanowire layers is provided with the wrapping layer formed by active metal oxide nanoparticles, wherein: Multiple silver nanowire layers are stacked; A waterproof encapsulation layer is bonded to the outer side of the silver nanowire functional body; Characterized in that, the method for preparing a thin film heater having a curved surface shape comprises: S1. preparing a silver nanowire dispersion in a thick state, wherein the silver nanowire dispersion in a thick state is determined by rheological property testing. If the viscosity coefficient of the silver nanowire dispersion first increases and then decreases over time, it is in a thick state; S2, placing the substrate into a concentrated silver nanowire dispersion, driving the silver nanowire dispersion to complete a preset rotation state, forming a wet film of the silver nanowire dispersion on the substrate, and then removing the substrate and drying it to obtain a silver nanowire layer; S3, completing the silver nanowire layer preparation process for a preset number of times, thereby obtaining a silver nanowire functional body; S4, processing a wrapping layer on the outer surface of the silver nanowire functional body, wherein the wrapping layer is a layer structure formed by active metal oxide nanoparticles; S5, processing a waterproof encapsulation layer on the outer side of the silver nanowire functional body; The preset rotation state includes an early low-speed stirring process of 400-600 rpm and a later high-speed stirring process of 1000-1200 rpm. The stirring intensity during the high-speed stirring process is 2 to 3 times that of the low-speed stirring process. During the low-speed stirring process, the silver nanowire dispersion is in a laminar state.

2. The method according to claim 1, characterized in that The silver nanowires in the silver nanowire layer have an average diameter of 10 to 60 nm and an average length of 10 to 60 μm.

3. The method according to claim 1, characterized in that The preset number of times in step S3 is greater than or equal to two times, and the angle of the base device is adjusted so that the silver nanowires between adjacent silver nanowire layers are arranged at an angle of 30 to 90 degrees.

4. The method according to claim 1, wherein The steps of S2 include: The substrate device is placed in a concentrated silver nanowire dispersion, and the silver nanowire dispersion is driven by a magnetic stirrer. After the initial low speed of 400-600 rpm for 8 seconds, a high speed of 1000-1200 rpm is used for 30 seconds to complete the preset rotation state. After a wet film of the silver nanowire dispersion is formed on the substrate device, the substrate device is removed and dried to obtain a silver nanowire layer.

5. The method according to claim 1, wherein The silver nanowires dispersed in the silver nanowire dispersion have an average diameter of 10 to 60 nm and an average length of 10 to 60 μm, and a mass concentration of the silver nanowires in the silver nanowire dispersion is 1.0 to 4.0 mg / ml.

6. The method according to claim 1, characterized in that In step S4, the wrapping layer is processed by magnetron sputtering.

7. The method according to claim 1, characterized in that The waterproof encapsulation layer includes a waterproof layer and an encapsulation layer attached to the outer surface of the waterproof layer. In the step S5, the waterproof layer is processed by coating and then drying, and the encapsulation layer is processed by magnetron sputtering.

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