Enamel-based heater and preparation method thereof

Abstract

The invention discloses an enamel-based heater and a preparation method thereof, and relates to the field of heaters, and the enamel-based heater comprises an insulated enamel substrate; the carbon-based nano composite heating layer is formed on the surface of the enamel substrate and comprises a one-dimensional carbon nano material for electrifying to generate heat; the thin film covering layer is adhered and fixed on the surface, deviating from the enamel substrate, of the carbon-based nano composite heating layer through an adhesive film; the functional paint layer is located on the surface of the side, away from the carbon-based nano composite heating layer, of the film covering layer; wherein the thin film covering layer, the adhesive film and the functional paint layer are at least used for improving the insulation protection performance and the weather resistance of the enamel-based heater. According to the invention, whole-surface heating can be realized, and the temperature rising speed can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of heaters, and more particularly to an enamel-based heater and a method for preparing the same. Background Technology

[0002] Current electric heaters generally use metal resistance wires (such as nickel-chromium alloy) as heating elements, supported and insulated by mica sheets or ceramic tubes, and encased in a metal shell. Some high-end products use positive temperature coefficient (PTC) ceramic heating elements or thick-film circuit technology. For traditional heaters using metal resistance wires or ceramic heating elements, due to the limitations of the heating materials, there is a problem of thermal response lag, and the heating time is generally relatively slow (greater than 30 seconds). Summary of the Invention

[0003] In view of the above problems, this application provides an enamel-based heater and its preparation method to improve the heating rate of the heater. The specific solution is as follows:

[0004] The first aspect of this application provides an enamel-based heater, comprising:

[0005] Insulating enamel substrate;

[0006] A carbon-based nanocomposite heating layer is formed on the surface of an enamel substrate, the carbon-based nanocomposite heating layer comprising one-dimensional carbon nanomaterials for generating heat by electricity.

[0007] A thin film covering layer is bonded to the surface of the carbon-based nanocomposite heating layer facing away from the enamel substrate by an adhesive film.

[0008] The functional coating layer is located on the side of the thin film covering layer that is away from the carbon-based nanocomposite heating layer.

[0009] Among them, the thin film covering layer, the adhesive film, and the functional paint layer are used to improve the insulation protection performance and weather resistance of the enamel-based heater.

[0010] Optionally, in the above-mentioned enamel-based heater, the carbon-based nanocomposite heating layer is a heating coating formed on the surface of the enamel substrate;

[0011] The slurry of the heating coating includes a uniformly mixed conductive heating material, adhesive material, functional filler, solvent, and dispersant;

[0012] One-dimensional carbon nanomaterials are used as conductive heating materials to provide conductive heating pathways;

[0013] The adhesive phase material is used to bond the heating coating to the surface of the enamel substrate;

[0014] Functional fillers are used to improve the thermal conductivity of the heating coating;

[0015] Solvents are used to adjust the viscosity and film-forming properties of the slurry;

[0016] Dispersants are used to improve the dispersion stability of slurries.

[0017] Optionally, in the above-mentioned enamel-based heater, the mass percentage of the conductive heating material is 30wt%~40wt%;

[0018] The adhesive material accounts for 20wt%~25wt% of the total mass.

[0019] The functional filler has a mass percentage of 5wt%~10wt%;

[0020] The solvent content is 25 wt% to 35 wt% by mass.

[0021] The mass percentage of the dispersant is 1 wt% to 3 wt%.

[0022] Optionally, in the above-mentioned enamel-based heater, the one-dimensional carbon nanomaterial includes at least one of carbon nanotubes mixed with carbon nanoribbons;

[0023] Adhesive materials include siloxane resins or inorganic silicates;

[0024] Functional fillers include nano-titanium dioxide or nano-silicon carbide;

[0025] Solvents include alcohol ether solvents;

[0026] Dispersants include anionic dispersants.

[0027] Optionally, in the above-mentioned enamel-based heater, the coefficients of thermal expansion of the enamel substrate, the carbon-based nanocomposite heating layer, the adhesive film, the thin film covering layer, and the functional paint layer increase sequentially.

[0028] Optionally, in the above-mentioned enamel-based heater, the coefficient of thermal expansion of the thin film covering layer and the adhesive film is greater than that of the carbon-based nanocomposite heating layer, and the thin film covering layer and the adhesive film are also used to improve the thermal stress buffering performance of the enamel-based heater.

[0029] Optionally, in the above-mentioned enamel-based heater, the adhesive film includes a polyimide-fluorocarbon copolymer adhesive film;

[0030] The film coating layer includes at least one of polyimide, ethylene-tetrafluoroethylene copolymer and high-temperature resistant polyester.

[0031] Optionally, in the above-mentioned enamel-based heater, the functional coating layer includes:

[0032] Primer layer, located on the surface of the thin film cover layer, is used for directional reflection of infrared radiation;

[0033] The topcoat layer, located on the surface of the primer layer, serves as an outer protective layer for enamel-based heaters.

[0034] Optionally, in the above-mentioned enamel-based heater, the primer layer includes oriented flake aluminum powder, which is used to directionally reflect infrared radiation.

[0035] Optionally, in the above-mentioned enamel-based heater, the primer layer includes a uniformly mixed siloxane-modified polyester varnish and flake aluminum powder;

[0036] The mass percentage of flake aluminum powder is 8 wt% to 12 wt%.

[0037] Optionally, in the above-mentioned enamel-based heater, the dry film thickness of the primer layer is 10μm~15μm, the surface energy is less than 25Mn / m, and the emissivity across the entire wavelength band is greater than 0.9.

[0038] Optionally, in the above-mentioned enamel-based heater, the topcoat includes aliphatic polyurethane varnish;

[0039] The aliphatic polyurethane varnish contains polytetrafluoroethylene powder and nano-alumina powder.

[0040] Optionally, in the above-mentioned enamel-based heater, the mass percentage of polytetrafluoroethylene powder is 1 wt% to 2 wt%.

[0041] The mass percentage of nano-alumina powder is 2wt%~3wt%.

[0042] Optionally, in the above-mentioned enamel-based heater, the dry film thickness of the topcoat layer is 5μm~10μm, the gloss is greater than 90°, and the hardness is not less than 3H.

[0043] Optionally, in the above-mentioned enamel-based heater, the long axis of the one-dimensional carbon nanomaterial is parallel to the surface of the enamel substrate along a predetermined direction.

[0044] A second aspect of this application provides a method for preparing any of the above-mentioned enamel-based heaters, comprising:

[0045] A carbon-based nanocomposite heating layer is formed on the surface of an insulating enamel substrate. The carbon-based nanocomposite heating layer includes a one-dimensional carbon nanomaterial for generating heat by applying electricity.

[0046] A thin film covering layer is fixed by bonding an adhesive film to the surface of a carbon-based nanocomposite heating layer.

[0047] A functional paint layer is formed on the surface of the thin film coating;

[0048] Among them, the thin film covering layer, the adhesive film, and the functional paint layer are used to improve the insulation protection performance and weather resistance of the enamel-based heater.

[0049] Optionally, in the above preparation method, the thin film covering layer is fixed by bonding an adhesive film to the surface of the carbon-based nanocomposite heating layer, including:

[0050] An adhesive film and a thin film covering layer are sequentially applied to the carbon-based nanocomposite heating layer;

[0051] The thin film covering layer is bonded to the surface of the carbon-based nanocomposite heating layer using a vacuum hot pressing process.

[0052] By employing the above technical solution, the enamel-based heater and its preparation method provided in this application use an enamel substrate as the main mechanical support for the heater. Compared to the mica flakes or ceramic materials used in conventional heaters, the enamel substrate has good mechanical strength and is less prone to microcracks. Furthermore, the carbon-based nanocomposite heating layer in the enamel-based heater generates heat through the application of one-dimensional carbon nanomaterials. These one-dimensional carbon nanomaterials have good electrical conductivity and can achieve full-surface heating along with the carbon-based nanocomposite heating layer that covers the entire enamel substrate, effectively improving the heating rate. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0054] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0055] Figure 1 This is a schematic diagram of the structure of an enamel-based heater provided in an embodiment of this application;

[0056] Figure 2 This is a schematic diagram of another enamel-based heater provided in an embodiment of this application;

[0057] Figure 3 for Figure 2 A schematic diagram showing the arrangement of electrodes on the surface of an enamel-based heater.

[0058] Figure 4A schematic diagram of the structure of another enamel-based heater provided in the embodiments of this application;

[0059] Figure 5 A schematic diagram of the structure of another enamel-based heater provided in the embodiments of this application;

[0060] Figure 6 This is a schematic flowchart illustrating a method for preparing an enamel-based heater according to an embodiment of this application.

[0061] The annotations in the attached figures are explained as follows:

[0062] Enamel substrate 100, carbon-based nanocomposite heating layer 101, adhesive film 102, thin film covering layer 103, functional paint layer 104, primer layer 1041, topcoat layer 1042, electrode 105, power contact terminal 106, flake aluminum powder 107. Detailed Implementation

[0063] The embodiments of this application will now be clearly and completely described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0064] Conventional heaters typically employ metal resistance wires or ceramic heating elements with a positive temperature coefficient for heating. However, these technologies are limited by their materials and structures, resulting in not only thermal response lag, leading to long heating times and slow heating rates, but also poor surface temperature uniformity (local temperature differences can reach ±15℃), making the internal insulation structure susceptible to microcracks under thermal shock, causing corrosion of metal components, and leading to peeling of the outer protective layer.

[0065] For conventional heaters using metal resistance wires, the high heat capacity of metal materials results in slow heating, making rapid start-up and shutdown and precise temperature control impossible. Furthermore, the metal resistance wire winding process leads to uneven heat distribution, making them prone to thermal stress fatigue. The inorganic insulating layer, such as ceramic or mica sheets, which serves as the main support, is susceptible to cracking under thermal shock, causing a drop in breakdown voltage (less than 2kV / mm) and posing a risk of arcing.

[0066] Conventional heaters typically use a metal substrate, which is prone to pitting corrosion in high-temperature and high-humidity environments (humidity greater than 80% RH), leading to a decrease in insulation resistance (less than 1 MΩ). Conventional heaters often use an organic paint layer as a surface protective layer for the metal substrate. However, there is a mismatch in the coefficients of thermal expansion between the organic paint layer and the metal substrate, which can easily cause the paint layer to peel off after thermal cycling.

[0067] In view of this, embodiments of this application provide an enamel-based heater, comprising:

[0068] Insulating enamel substrate;

[0069] A carbon-based nanocomposite heating layer is formed on the surface of an enamel substrate, the carbon-based nanocomposite heating layer comprising one-dimensional carbon nanomaterials for generating heat by electricity.

[0070] A thin film covering layer is bonded to the surface of the carbon-based nanocomposite heating layer facing away from the enamel substrate by an adhesive film.

[0071] The functional coating layer is located on the side of the thin film covering layer that is away from the carbon-based nanocomposite heating layer.

[0072] Among them, the thin film covering layer, the adhesive film, and the functional paint layer are used to improve the insulation protection performance and weather resistance of the enamel-based heater.

[0073] In the enamel-based heater provided in this application embodiment, an enamel substrate is used as the main mechanical support for the heater. Compared to the mica flakes or ceramic materials used in conventional heaters, the enamel substrate has good mechanical strength and is less prone to micro-cracks. Furthermore, the carbon-based nanocomposite heating layer in the enamel-based heater generates heat through the application of one-dimensional carbon nanomaterials. These one-dimensional carbon nanomaterials have excellent electrical conductivity and can achieve full-surface heating along with the carbon-based nanocomposite heating layer that covers the entire enamel substrate. This effectively improves the heating rate and solves the problem of slow thermal response in conventional heaters, enabling second-level rapid start-up and heating.

[0074] One-dimensional carbon nanomaterials also have highly efficient electrothermal conversion characteristics with extremely low energy loss, which can reduce losses in the power transmission process and increase the thermoelectric conversion efficiency from the traditional 85% to 98% or more, meeting the GB / T 7287 standard and achieving the green and low-carbon goal of saving more than 25%.

[0075] The enamel substrate exhibits good mechanical stability and reliability, and is not prone to microcracks under thermal shock, ensuring a breakdown voltage of not less than 5 kV / mm, meeting the ASTM D149 standard. Furthermore, the enamel substrate and functional coating of the enamel material possess excellent weather resistance, significantly improving the heater's environmental tolerance and effectively preventing the penetration of corrosive media. After aging for 1000 hours at 85℃ / 85%RH, the insulation resistance remains greater than 1000 MΩ.

[0076] The heat source area of ​​a conventional metal resistance wire is only the area where the metal resistance wire is located. On the plane where the supporting substrate is located, the heating process of the heater needs to achieve lateral heat conduction based on thermal conduction, resulting in poor surface temperature uniformity. The carbon-based nanocomposite heating layer covering the entire surface can directly achieve uniform heating of a large area on the plane where the enamel substrate is located, achieving uniform surface heating. It can control the surface temperature difference within ±2℃, solving the problems of uneven heat source distribution and temperature distribution.

[0077] Enamel-based heaters can also optimize the thermal expansion coefficients of each layer to make the thermal expansion coefficients of different layer structures compatible, thereby enhancing the bonding force between different layer structures. This overcomes the problem of film interface peeling caused by thermal expansion coefficient mismatch, enabling the film interface bonding performance to withstand 500 thermal cycling tests at 40℃~200℃, meeting ISO 2409 standard to achieve level 0 adhesion, with no metal fatigue source and a theoretical calculated life of over 50,000 hours.

[0078] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0079] refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of an enamel-based heater provided in an embodiment of this application. The enamel-based heater shown includes:

[0080] Insulating enamel substrate 100;

[0081] A carbon-based nanocomposite heating layer 101 is formed on the surface of an enamel substrate 100. The carbon-based nanocomposite heating layer 101 includes a one-dimensional carbon nanomaterial for generating heat by electricity.

[0082] A thin film covering layer 103 is bonded and fixed to the surface of the carbon-based nanocomposite heating layer 101 facing away from the enamel substrate 100 by an adhesive film 102.

[0083] Functional coating layer 104 is located on the side of the thin film covering layer 103 facing away from the carbon-based nanocomposite heating layer 101.

[0084] Among them, the thin film covering layer 103, the adhesive film 102, and the functional paint layer 104 are used to improve the insulation protection performance and weather resistance of the enamel-based heater.

[0085] In the enamel-based heater provided in this application embodiment, an enamel substrate 100 is used as the main mechanical support for the heater. Compared with the support structure of mica flakes or ceramic materials used in conventional heaters, the enamel substrate 100 has good mechanical strength and is not prone to microcracks.

[0086] One-dimensional carbon nanomaterials possess low thermal inertia, enabling rapid conversion of electrical energy into heat. Upon energization, they can achieve rapid heating within 3 seconds, effectively improving the heating rate and solving the problem of slow thermal response in conventional heaters, achieving second-level rapid start-up and heating. Furthermore, one-dimensional carbon nanomaterials exhibit highly efficient electrothermal conversion characteristics with extremely low energy loss, reducing losses during power transmission. This increases the thermoelectric conversion efficiency from the traditional 85% to 98% or higher, meeting the GB / T 7287 standard and achieving a green and low-carbon goal of over 25% energy savings.

[0087] In the enamel-based heater, the carbon-based nanocomposite heating layer 101 generates heat through the application of one-dimensional carbon nanomaterials. These one-dimensional carbon nanomaterials possess excellent electrical conductivity and can achieve full-surface heating as the carbon-based nanocomposite heating layer 101 covers the entire surface of the enamel substrate 100. Optionally, the carbon-based nanocomposite heating layer 101 with good adhesion stability can be directly formed on the surface of the enamel substrate 100 using a spraying process. Compared to conventional point-like or filamentous heating elements, the full-surface covered carbon-based nanocomposite heating layer 101 can directly achieve uniform heating over a large area of ​​the enamel substrate 100, achieving uniform surface heating. This allows the surface temperature difference to be controlled within ±2℃, solving the problems of uneven heat source distribution and temperature distribution.

[0088] The enamel substrate 100 is made of inorganic enamel material, which has good mechanical stability and reliability, good resistance to thermal shock, and is not prone to microcracks under thermal shock. It can ensure that the breakdown voltage is not less than 5 kV / mm, which meets the ASTM D149 standard.

[0089] Furthermore, the enamel substrate 100 and the functional paint layer 104 have good weather resistance, which can greatly improve the environmental tolerance of the heater and effectively prevent the penetration of corrosive media. After aging test at 85℃ / 85%RH for 1000h, the insulation resistance is still greater than 1000MΩ.

[0090] The functional coating layer 104 has a low surface energy, which can further improve its performance in isolating it from external environmental corrosion. The composite film structure formed by the adhesive film 102, the thin film covering layer 103, and the functional coating layer 104 can achieve multi-layer protection. The composite film structure can effectively protect the carbon-based nanocomposite heating layer 101, achieve a good sealing effect on the carbon-based nanocomposite heating layer 101, effectively prevent external water and oxygen erosion, and improve the stability of the carbon-based nanocomposite heating layer 101. The composite film structure can also improve the insulation of the carbon-based nanocomposite heating layer 101 in high-temperature and high-humidity environments, and significantly improve the overall breakdown voltage. The composite film structure also has good thermal stress absorption capacity, avoiding the problem of insulation material failure under thermal shock.

[0091] Optionally, the thin film covering layer 103 can be bonded and fixed to the surface of the carbon-based nanocomposite heating layer 101 using a vacuum hot-pressing process via an adhesive film 102. This achieves bubble-free bonding and fixation of the thin film covering layer 103, resulting in excellent sealing and effectively preventing external water and oxygen corrosion. Combined with the good weather resistance of the enamel substrate 100 and the functional paint layer 104, the stability of the carbon-based nanocomposite heating layer 101 in high-temperature and high-humidity environments can be effectively guaranteed.

[0092] refer to Figure 2 , Figure 2 This is a schematic diagram of another enamel-based heater provided in an embodiment of this application. Figure 3 for Figure 2 The diagram shows the arrangement of electrodes on the surface of the enamel-based substrate in the enamel-based heater. Based on other embodiments, Figure 2 and Figure 3 In the illustrated configuration, the enamel-based heater further includes an electrode 105, which provides electrical energy to the carbon-based nanocomposite heating layer 101.

[0093] The electrode 105 can be fixed on the surface of the enamel substrate 100, and the carbon-based nanocomposite heating layer 101 directly covers the electrode 105 and is in electrical contact with it.

[0094] Optionally, the electrode 105 can be a flexible conductive strip bonded to the surface of the enamel substrate 100. The flexible conductive strip includes a stacked conductive adhesive layer and a metal layer, where the metal layer can be copper foil. The flexible conductive strip is bonded to the surface of the enamel substrate 100 via the conductive adhesive layer. Compared to conventional rigid electrode structures, the flexible conductive strip can also achieve low-stress contact with the brittle carbon-based nanocomposite heating layer 101, reducing stress and contact resistance between the layer and the layer, enabling uniform current introduction, ensuring uniform surface heating and high current carrying capacity, and achieving rapid heating. The flexible conductive strip allows for more uniform current introduction into the carbon-based nanocomposite heating layer 101, avoiding localized current concentration and thus precisely controlling the surface temperature difference.

[0095] To facilitate connection of electrode 105 to an external power source, electrode 105 is also connected to a power contact terminal 106. In one embodiment, such as... Figure 2 As shown, the enamel substrate 100 has a through hole, and the power contact terminal 106 is electrically connected to the electrode 105 based on the through hole. Alternatively, the power contact terminal 106, which is electrically connected to the electrode 105, can also be led out from the side wall of the enamel-based heater.

[0096] In some embodiments of this application, the carbon-based nanocomposite heating layer 101 is a heating coating formed on the surface of an enamel substrate 100; the slurry of the heating coating includes a uniformly mixed conductive heating material, a binder, a functional filler, a solvent, and a dispersant. One-dimensional carbon nanomaterials serve as the conductive heating material, providing a conductive heating pathway; the binder material adheres the heating coating to the surface of the enamel substrate 100; the functional filler improves the thermal conductivity of the heating coating; the solvent adjusts the viscosity and film-forming properties of the slurry; and the dispersant improves the dispersion stability of the slurry.

[0097] Optionally, a carbon-based nanocomposite heating layer 101 can be formed on the surface of the enamel substrate 100 by a coating process (such as spraying). The preparation process of the carbon-based nanocomposite heating layer 101 is simple, and it can form a stable adhesion with the underlying enamel substrate 100. The sheet resistance of the carbon-based nanocomposite heating layer 101 can be precisely controlled within 50Ω / □~200Ω / □, meeting the ASTM F390 standard test.

[0098] The heating coating slurry is a multiphase composite slurry, which can be prepared by spraying. The conductive heating material, as the core conductive heating phase material, provides a low-resistance conductive path, achieving efficient electrothermal conversion, while also giving the carbon-based nanocomposite heating layer 101 a negative temperature coefficient self-limiting characteristic. The binder material, as the binder phase material, can bond the one-dimensional carbon nanomaterials, enhancing the adhesion between the carbon-based nanocomposite heating layer 101 and the enamel substrate 100, and improving the stability of the film layer under thermal cycling. Functional fillers can regulate the thermal conductivity of the film layer, suppress local hot spots, and assist in optimizing the infrared radiation band. Solvents are used to adjust the viscosity and film-forming properties of the slurry, ensuring a uniform film layer free of pinholes after spraying. Dispersants are used to prevent the agglomeration of one-dimensional carbon nanomaterials, ensuring the dispersion stability of the slurry, thereby improving the resistance uniformity of the carbon-based nanocomposite heating layer 101.

[0099] Among them, the carbon-based nanocomposite heating layer 101 has a negative temperature coefficient self-limiting characteristic, and its temperature coefficient of resistance RCR can be equal to -0.05% / ℃. It can achieve power regulation and can automatically form a high resistance zone under abnormal temperature conditions, effectively suppressing local overheating and having inherent safety characteristics.

[0100] In some embodiments of this application, based on the above embodiments, the mass percentage of the conductive heating material is 30wt%~40wt%; the mass percentage of the adhesive material is 20wt%~25wt%; the mass percentage of the functional filler is 5wt%~10wt%; the mass percentage of the solvent is 25wt%~35wt%; and the mass percentage of the dispersant is 1wt%~3wt%. The carbon-based nanocomposite heating layer 101 prepared based on the slurry composition provided in this application has good uniform conductivity, adhesion stability, and...

[0101] Optionally, the one-dimensional carbon nanomaterial includes at least one of carbon nanotubes and carbon nanoribbons; the binder includes siloxane resin or inorganic silicate; the functional filler includes nano-titanium dioxide or nano-silicon carbide; the solvent includes alcohol ether solvents; and the dispersant includes anionic dispersants.

[0102] The long axis of the one-dimensional carbon nanomaterial is parallel to the surface of the enamel substrate 100 along a set direction, which can maximize the high axial thermal conductivity of the one-dimensional carbon nanomaterial and achieve efficient heat conduction and uniform heat distribution.

[0103] Taking carbon nanotubes as an example, one-dimensional carbon nanomaterials exhibit anisotropy. One-dimensional carbon nanomaterials have extremely high thermal conductivity along their long axis, parallel to their length. This is because the atomic structure of one-dimensional carbon nanomaterials is highly ordered along this axis, allowing phonons (the main carriers of heat conduction) to travel unimpeded. However, the thermal conductivity of one-dimensional carbon nanomaterials is lower perpendicular to their length, as phonons are easily scattered in this direction, resulting in higher thermal resistance. Therefore, one-dimensional carbon nanomaterials have extremely high thermal conductivity along their long axis. When the long axis of the one-dimensional carbon nanomaterial is parallel to the surface of the enamel substrate 100 along a predetermined direction, the parallel-arranged one-dimensional carbon nanomaterials can fully utilize their high thermal conductivity advantage.

[0104] Along the thickness direction of the carbon-based nanocomposite heating layer 101, the carbon-based nanocomposite heating layer 101 includes a first sub-layer and a second sub-layer stacked together, both of which include one-dimensional carbon nanomaterials. The long axis of the one-dimensional carbon nanomaterials in the first sub-layer is parallel to a first direction, and the long axis of the one-dimensional carbon nanomaterials in the second sub-layer is parallel to a second direction. The first and second directions intersect and are both parallel to the plane of the enamel substrate 100. Thus, when the long axis of the one-dimensional carbon nanomaterials in the same sub-layer is parallel to the surface of the enamel substrate 100 along a predetermined direction, the parallel arrangement of the one-dimensional carbon nanomaterials can leverage their high thermal conductivity. The intersection of the long axes of the one-dimensional carbon nanomaterials in the first and second sub-layers allows the one-dimensional carbon nanomaterials in the two sub-layers to intersect into a mesh structure, further improving heating efficiency and temperature uniformity.

[0105] In some embodiments of this application, the coefficients of thermal expansion of the enamel substrate 100, the carbon-based nanocomposite heating layer 101, the adhesive film 102, the thin film covering layer 103, and the functional paint layer 104 increase sequentially. This allows for a gradual variation in the coefficients of thermal expansion of different layers in the enamel-based heater, enhancing the bonding force between them. This overcomes the problem of film interface peeling caused by mismatch in coefficients of thermal expansion, enabling the film interface bonding performance to withstand 500 thermal cycling tests at 40℃~200℃, meeting ISO 2409 standard and achieving Grade 0 adhesion.

[0106] Optionally, the coefficient of thermal expansion of the thin film covering layer 103 and the adhesive film 102 is greater than that of the carbon-based nanocomposite heating layer 101. The thin film covering layer 103 and the adhesive film 102 are also used to improve the thermal stress buffering performance of the enamel-based heater, which can better buffer the internal thermal stress of the heater and effectively prevent the film peeling problem.

[0107] In some embodiments of this application, the glass transition temperature (Tg) of the adhesive film 102 is higher than 300°C, so that the adhesive film 102 can be laminated with the lower carbon-based nanocomposite heating layer 101 and the upper thin film covering layer 103 through a vacuum hot pressing process to achieve a bubble-free (bubble rate <0.1%) composite lamination, thereby achieving excellent interlayer adhesion and reliable sealing effect, effectively preventing interlayer peeling and water vapor penetration. The adhesive film 102 includes a polyimide-fluorocarbon copolymer adhesive film; the thin film covering layer 103 includes at least one of polyimide (PI), ethylene-tetrafluoroethylene copolymer (ETFE), and high-temperature resistant polyester (PET). Optionally, the thickness of the adhesive film 102 can be 0.05 mm to 0.2 mm.

[0108] The adhesive film 102 exhibits excellent elasticity, with an elongation at break exceeding 200%. By bonding and fixing the highly elastic adhesive film 102 with the carbon-based nanocomposite heating layer 101 and the thin film covering layer 103, thermal stress can be effectively absorbed, increasing the overall structure's thermal cycle life from the traditional 200 cycles to over 1000 cycles. Simultaneously, the adhesive film 102 also possesses excellent adhesion and density, providing sufficient interlayer sealing, as described below, thus eliminating the need for additional edge seals.

[0109] refer to Figure 4 , Figure 4 This is a schematic diagram of another enamel-based heater provided in the embodiments of this application. Based on other implementations, Figure 4 In the enamel-based heater shown, the carbon-based nanocomposite heating layer 101 is exposed around the perimeter of the upper surface of the enamel substrate 100, and the adhesive film 102 also covers this perimeter. As described above, the vacuum hot-pressing process not only bonds the thin film covering layer 103 to the carbon-based nanocomposite heating layer 101 with the adhesive film, but also bonds the perimeter of the upper surface of the enamel substrate 100 to the thin film covering layer 103, thereby achieving encapsulation and protection of the perimeter of the carbon-based nanocomposite heating layer 101. This provides all-around encapsulation and protection for the carbon-based nanocomposite heating layer 101 without the need for additional edge sealing structures.

[0110] refer to Figure 5 , Figure 5 This is a schematic diagram of another enamel-based heater provided in the embodiments of this application. Based on other implementations, Figure 5In the enamel-based heater shown, the functional paint layer 104 includes: a primer layer 1041, which is located on the surface of the thin film cover layer 103 and is used for directional reflection of infrared radiation; and a topcoat layer 1042, which is located on the surface of the primer layer 1041 and is used as an outer protective layer for the enamel-based heater.

[0111] Optionally, the primer layer 1041 includes oriented flake aluminum powder 107, which is used to form oriented radiation channels to orientedly reflect infrared radiation.

[0112] Optionally, the primer layer 1041 comprises a uniformly mixed siloxane-modified polyester varnish and flake aluminum powder 107; wherein the flake aluminum powder accounts for 8 wt% to 12 wt% of the total mass. The siloxane-modified polyester varnish can reduce the surface energy of the flake aluminum powder 107, enhance its adhesion to the underlying thin film capping layer 103, and facilitate the directional arrangement of the flake aluminum powder 107 to form the desired directional radiation channels. When the flake aluminum powder accounts for 8 wt% to 12 wt% of the total mass, it facilitates the formation of the desired directional radiation channels.

[0113] The dry film thickness of primer layer 1041 is 10μm~15μm, which meets the ASTM D7091 standard. The surface energy of primer layer 1041 is less than 25Mn / m, which ensures adhesion to the underlying thin film cover layer 103. The emissivity of primer layer 1041 across the entire wavelength range is greater than 0.9, which meets the ASTM C1371 standard.

[0114] In this embodiment, by adjusting the morphology and proportion of each component material in the carbon-based nanocomposite heating layer 101, the carbon-based nanocomposite heating layer 101 can be made to have infrared radiation characteristics in a specific band. The 20wt% flake aluminum powder 107 in the primer layer 1041 of the functional paint layer 104 on the outside of the heater forms a directional radiation channel. The two work together to enhance the radiation intensity in the 8μm~14μm band, and finally achieve far-infrared emission with a peak wavelength of 9.35μm.

[0115] Optionally, the topcoat layer 1042 includes an aliphatic polyurethane varnish; wherein the aliphatic polyurethane varnish uniformly mixes polytetrafluoroethylene (PTFE) powder and nano-alumina powder. The aliphatic polyurethane varnish serves as the film-forming matrix of the topcoat layer, where polyurethane molecules can form good adhesion stability with the underlying structure, making it less prone to peeling. The aliphatic polyurethane varnish also exhibits good weather resistance, effectively preventing moisture intrusion and acid / alkali corrosion. The PTFE powder possesses excellent properties such as high temperature resistance, low coefficient of friction, and chemical corrosion resistance, enabling the topcoat layer 1042 to form a smooth surface barrier, reducing adhesion to the outer surface of the heater, and simultaneously improving the thermal stability of the outer protective layer. The nano-alumina powder possesses excellent properties such as high hardness, high melting point, and high thermal conductivity, which can improve the hardness, wear resistance, thermal stability, and thermal conductivity of the outer protective layer of the heater. Therefore, the aliphatic polyurethane varnish, polytetrafluoroethylene powder, and nano alumina powder in the topcoat layer 1042 work synergistically to give the topcoat layer 1042 excellent high temperature resistance, non-stick properties, wear resistance, corrosion resistance, and thermal stability, meeting the requirements for long-term stable operation of the heater.

[0116] The polytetrafluoroethylene powder accounts for 1 wt% to 2 wt% of the total mass, while the nano-alumina powder accounts for 2 wt% to 3 wt%. When the three components in the topcoat layer 1042 are within the above-mentioned data ranges, they can exert a better synergistic effect and improve the performance of the topcoat layer 1042.

[0117] Optionally, the dry film thickness of topcoat layer 1042 is 5μm~10μm, which meets the ASTM D7091 standard. The gloss of topcoat layer 1042 is greater than 90°. By adjusting the proportion of the middle components, topcoat layer 1042 achieves good gloss and reduces surface adhesion. The hardness of topcoat layer 1042 is not less than 3H. By adjusting the mass ratio of nano-alumina powder, topcoat layer 1042 achieves greater hardness, improving surface film strength and reducing the risk of external force damage. Topcoat layer 1042 is easy to repair at room temperature.

[0118] Based on the above embodiments, the enamel-based heater also includes a temperature sensor for detecting the temperature of the enamel-based heater. The temperature sensor is connected to an external temperature control system. When the temperature of the enamel-based heater exceeds a set safety threshold, the temperature control system disconnects the external power supply from the enamel-based heater to form active safety protection. Simultaneously, the negative temperature coefficient of the carbon-based nanocomposite heating layer 101 helps suppress local overheating, providing double protection against potential safety hazards.

[0119] In this embodiment, the carbon-based nanocomposite heating layer 101 generates heat based on one-dimensional carbon nanomaterials. The vibrational and rotational energy levels of the molecules in the one-dimensional carbon nanomaterials are matched with the photon energy of far-infrared wavelengths. When an electric current passes through the carbon-based nanocomposite heating layer 101, electrical energy is converted into electrical energy, which excites the molecules of the one-dimensional carbon nanomaterials to vibrate and radiate electromagnetic waves in the far-infrared band. Furthermore, the flake-like aluminum powder in the primer layer 1041 can be used to create a directional radiation channel, which can screen and enhance the far-infrared band emitted by the carbon-based nanocomposite heating layer 101 and reduce the energy proportion of other bands. Additionally, the high emissivity of the primer layer 1041 (emissivity greater than 0.9 across the entire band) can further improve the emission efficiency of the far-infrared band, achieving far-infrared output with peak wavelengths concentrated in the range of 8μm to 14μm (typical value 9.35μm).

[0120] As described above, in this embodiment, by adjusting the material morphology and proportion in the carbon-based nanocomposite heating layer 101 and utilizing the directional radiation channels formed by the flake aluminum powder in the functional paint layer 104, the carbon-based nanocomposite heating layer 101 can efficiently emit far-infrared electromagnetic waves with peak wavelengths of 8μm to 14μm, increasing the radiation intensity of this band by 40%. Therefore, the enamel-based heater can efficiently emit far-infrared battery waves including 9.35μm, achieving deep and gentle physiotherapy without dust, wind, or heat, and operating quietly without noise pollution.

[0121] In the enamel-based heater provided in this application embodiment, all film layer structures comply with RoHS standards, the materials are recyclable, the overall structure has good flexibility, and it can be used for installation on irregularly shaped objects.

[0122] Based on the enamel-based heater provided in the above embodiments, another embodiment of this application also provides a method for preparing an enamel-based heater, which can be as follows: Figure 6 As shown.

[0123] refer to Figure 6 , Figure 6 This application provides a schematic flowchart of a method for preparing an enamel-based heater, the method of which includes:

[0124] Step S11: A carbon-based nanocomposite heating layer 101 is formed on the surface of an insulating enamel substrate 100. The carbon-based nanocomposite heating layer 101 includes a one-dimensional carbon nanomaterial for generating heat by applying electricity.

[0125] Step S12: The thin film covering layer 103 is bonded and fixed on the surface of the carbon-based nanocomposite heating layer 101 by adhesive film 102;

[0126] Step S13: Form a functional paint layer 104 on the surface of the thin film covering layer 103;

[0127] Among them, the thin film covering layer 103, the adhesive film 102, and the functional paint layer 104 are used to improve the insulation protection performance and weather resistance of the enamel-based heater.

[0128] Optionally, the thin film covering layer 103 is bonded and fixed on the surface of the carbon-based nanocomposite heating layer 101 by means of adhesive film 102, including: first, applying adhesive film 102 and thin film covering layer 103 sequentially on the carbon-based nanocomposite heating layer 101; then, bonding and fixing the thin film covering layer 103 to the surface of the carbon-based nanocomposite heating layer 101 by means of adhesive film 102 through vacuum hot pressing process.

[0129] The preparation methods disclosed in the above embodiments have the same or corresponding beneficial effects as the enamel-based heater embodiments, and will not be repeated here to avoid repetition.

[0130] The various embodiments in this application are described in a progressive, parallel, or combined manner. Each embodiment focuses on its differences from other embodiments, and similar or identical parts between embodiments can be referred to interchangeably. The embodiments provided in this application can be combined with each other without contradiction.

[0131] It should be noted that, in the description of this application, the accompanying drawings and embodiments are illustrative rather than restrictive. The same reference numerals throughout the embodiments identify the same structures. Additionally, for ease of understanding and description, the thicknesses of some layers, films, panels, regions, etc., may be exaggerated in the drawings. It is also understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, the element may be directly on the other element or there may be intermediate elements. Furthermore, "on" means positioning an element on or below another element, but does not inherently mean positioning it above another element according to the direction of gravity.

[0132] The terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the middle.

[0133] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes the aforementioned element.

[0134] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An enamel-based heater, characterized in that, include: Insulating enamel substrate; A carbon-based nanocomposite heating layer is formed on the surface of the enamel substrate, the carbon-based nanocomposite heating layer comprising a one-dimensional carbon nanomaterial for generating heat by electricity; A thin film covering layer is bonded to the surface of the carbon-based nanocomposite heating layer away from the enamel substrate by an adhesive film. A functional coating layer is located on the side surface of the thin film covering layer that is away from the carbon-based nanocomposite heating layer. The thin film covering layer, the adhesive film, and the functional paint layer are used to improve the insulation and weather resistance of the enamel-based heater.

2. The enamel-based heater according to claim 1, characterized in that, The carbon-based nanocomposite heating layer is a heating coating formed on the surface of the enamel substrate; The slurry of the heating coating includes a uniformly mixed conductive heating material, adhesive material, functional filler, solvent, and dispersant. The one-dimensional carbon nanomaterial serves as the conductive heating material, providing a conductive heating pathway. The adhesive phase material is used to bond the heating coating to the surface of the enamel substrate; The functional filler is used to improve the thermal conductivity of the heating coating; The solvent is used to adjust the viscosity and film-forming properties of the slurry; The dispersant is used to improve the dispersion stability of the slurry.

3. The enamel-based heater according to claim 2, characterized in that, The conductive heating material accounts for 30 wt% to 40 wt% by mass. The adhesive material accounts for 20 wt% to 25 wt% of the total mass. The functional filler has a mass percentage of 5 wt% to 10 wt%. The solvent has a mass percentage of 25 wt% to 35 wt%. The dispersant has a mass percentage of 1 wt% to 3 wt%.

4. The enamel-based heater according to claim 2, characterized in that, The one-dimensional carbon nanomaterial includes at least one of carbon nanotubes and carbon nanoribbons; The adhesive material includes siloxane resin or inorganic silicate; The functional filler includes nano-titanium dioxide or nano-silicon carbide; The solvent includes alcohol ether solvents; The dispersant includes anionic dispersants.

5. The enamel-based heater according to claim 1, characterized in that, The coefficients of thermal expansion of the enamel substrate, the carbon-based nanocomposite heating layer, the adhesive film, the thin film covering layer, and the functional paint layer increase sequentially.

6. The enamel-based heater according to claim 1, characterized in that, The thermal expansion coefficients of the thin film covering layer and the adhesive film are greater than those of the carbon-based nanocomposite heating layer. The thin film covering layer and the adhesive film are also used to improve the thermal stress buffering performance of the enamel-based heater.

7. The enamel-based heater according to claim 6, characterized in that, The adhesive film includes a polyimide-fluorocarbon copolymer adhesive film; The film covering layer includes at least one of polyimide, ethylene-tetrafluoroethylene copolymer and high-temperature resistant polyester.

8. The enamel-based heater according to claim 1, characterized in that, The functional coating layer includes: A primer layer, located on the surface of the thin film cover layer, is used for directional reflection of infrared radiation; A topcoat layer, located on the surface of the primer layer, serves as an outer protective layer for the enamel-based heater.

9. The enamel-based heater according to claim 8, characterized in that, The primer layer includes oriented sheet aluminum powder, which is used to directionally reflect infrared radiation.

10. The enamel-based heater according to claim 9, characterized in that, The primer layer comprises a uniformly mixed siloxane-modified polyester paint and the flake aluminum powder; The mass percentage of the flaky aluminum powder is 8 wt% to 12 wt%.

11. The enamel-based heater according to claim 9, characterized in that, The dry film thickness of the primer layer is 10μm~15μm, the surface energy is less than 25Mn / m, and the emissivity across the entire wavelength band is greater than 0.

9.

12. The enamel-based heater according to claim 8, characterized in that, The topcoat includes an aliphatic polyurethane varnish; The aliphatic polyurethane varnish contains polytetrafluoroethylene powder and nano-alumina powder uniformly mixed in.

13. The enamel-based heater according to claim 12, characterized in that, The polytetrafluoroethylene powder accounts for 1 wt% to 2 wt% of the total mass. The mass percentage of the nano-alumina powder is 2wt% to 3wt%.

14. The enamel-based heater according to claim 12, characterized in that, The dry film thickness of the topcoat layer is 5μm~10μm, the gloss is greater than 90°, and the hardness is not less than 3H.

15. The enamel-based heater according to any one of claims 1-14, characterized in that, The long axis of the one-dimensional carbon nanomaterial is parallel to the surface of the enamel substrate along a predetermined direction.

16. A method for preparing an enamel-based heater as described in any one of claims 1-15, characterized in that, include: A carbon-based nanocomposite heating layer is formed on the surface of an insulating enamel substrate, the carbon-based nanocomposite heating layer comprising a one-dimensional carbon nanomaterial for generating heat by electricity; A thin film covering layer is fixed by bonding an adhesive film to the surface of the carbon-based nanocomposite heating layer. A functional paint layer is formed on the surface of the thin film covering layer; The thin film covering layer, the adhesive film, and the functional paint layer are used to improve the insulation and weather resistance of the enamel-based heater.

17. The preparation method according to claim 16, characterized in that, A thin film covering layer is bonded and fixed to the surface of the carbon-based nanocomposite heating layer by means of an adhesive film, including: The adhesive film and the thin film covering layer are sequentially applied to the carbon-based nanocomposite heating layer. The thin film covering layer is bonded and fixed to the surface of the carbon-based nanocomposite heating layer by the adhesive film through a vacuum hot pressing process.

Images