Low-voltage-driven high-safety electrothermal composite film and preparation method thereof

Abstract

The invention relates to the field of electric heating devices, and discloses a low-voltage-driven high-safety electric heating composite film which comprises a first metal electrode layer, a second metal electrode layer and a polymer composite material layer arranged between the two metal electrode layers. The polymer composite material layer comprises directionally arranged magnetic glass short fiber particles, and the magnetic glass short fiber particles are used for preventing the two metal electrode layers from being in contact to form a short circuit; the magnetic glass short fiber particle is of a three-layer core-shell structure, the inner core layer is a glass short fiber particle, the middle layer is a nickel metal layer, and the outer shell layer is an insulating layer. The high-safety electrothermal composite film disclosed by the invention is provided with the conductive particle layer, shows good supporting performance and strength, effectively reduces the risk of short circuit, improves the safety and prolongs the service life. Compared with a low-voltage ultrathin electrothermal film, the directionally arranged magnetic glass short fiber particles can increase conductivity, physical support and heat, reduce the risk of short circuit, and have high practical value and wide application prospect.

Description

Technical Field

[0001] The invention relates to the field of electric heating devices, and in particular to a low-voltage driven high-safety electric heating composite film and a preparation method thereof. Background Art

[0002] Electric heating materials are usually divided into metal, inorganic non-metal, and organic composite. Traditional metal electric heating materials have high density, easy corrosion, poor bending resistance, and produce inductive effect under the action of external electric field, resulting in low electric heating efficiency and large power loss. Inorganic non-metal electric heating materials are heavy, rigid, fragile, difficult to shape, and expensive. These shortcomings seriously restrict the application of metal and inorganic non-metal electric heating materials in some specific scenarios.

[0003] The electrothermal composite film is based on polymer materials as the main structure, and conductive materials are distributed in the polymer materials to form a continuous electronic conduction network. When under the action of an external directional electric field, it can convert electrical energy into thermal energy in the form of Joule heat. Due to its polymer film properties, the electrothermal composite film has the characteristics of flexibility, lightness, and good corrosion resistance. In addition, it has strong processability, outstanding electrothermal efficiency, and a certain positive temperature coefficient (PTC) effect. It has strong applicability in the fields of medical health, home heating, petrochemicals, etc.

[0004] Generally speaking, the key performance parameters of the electrothermal composite membrane include surface resistance, electric heating performance, thermal conductivity, heating rate, insulation strength, thickness, dielectric strength, operating temperature, etc. In addition to its intrinsic material properties, the key factors that determine the performance of the electrothermal composite membrane are also important electrode arrangement, such as electrode spacing, contact and bonding between the electrode and the conductive film layer, electrode structure, etc. In order to reduce the external applied voltage of the electrothermal composite membrane, sandwich symmetrical electrodes are usually used, that is, the two electrodes are distributed on both sides of the polymer conductive film layer. However, since the distance between the two electrodes is only tens to hundreds of microns, this electrode arrangement has a greater short-circuit risk, especially when working at higher temperatures, the polymer material between the electrodes is easy to soften, which increases the probability of short-circuit failure, causing device failure at the least and fire accidents at the worst. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a low-voltage driven high-safety electric heating composite membrane and a preparation method thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a low-voltage driven high-safety electrothermal composite membrane, comprising a first metal electrode layer, a second metal electrode layer and a polymer composite material layer arranged between the two metal electrode layers; the polymer composite material layer comprises directionally arranged magnetic glass short fiber particles, and the magnetic glass short fiber particles are used to prevent the two metal electrode layers from contacting and forming a short circuit; the magnetic glass short fiber particles are a three-layer core-shell structure, the inner core layer is glass short fiber particles, the middle layer is a nickel metal layer, and the outer shell layer is an insulating layer.

[0007] Furthermore, the magnetic glass short fiber particles are 400-1000 mesh particle powder; the nickel metal layer is achieved by chemical plating and has a thickness of 0.1-2 μm; the insulating layer is one or more of polystyrene or polyethylene terephthalate and has a thickness of 0.1-1 μm.

[0008] Furthermore, the polymer composite material layer also includes a polymer matrix, a carbon conductive material and an additive; the polymer matrix is ​​one or more of polyethylene oxide, polydimethylsiloxane, thermoplastic polyurethane elastomer, polyethersulfone resin, polyvinylidene fluoride, and polymethyl methacrylate; the carbon conductive material is one or more of carbon nanotubes, carbon fibers, graphite, acetylene black, and graphene; the additive is one or more of a coupling agent, a defoaming agent, a leveling agent, and a surfactant.

[0009] Furthermore, the thickness of the polymer composite material layer is 20 to 150 μm.

[0010] In a second aspect, the present invention provides a method for preparing a low-voltage driven high-safety electric heating composite membrane, characterized in that it comprises the following steps: Chemical nickel plating of glass staple particles; The nickel-plated glass short fiber particles are coated with an insulating layer to prepare magnetic glass short fiber particles; Dissolve 20 to 50 parts of polymer matrix in 300 to 600 parts of polymer matrix solvent, heat and stir at 60 to 80° C. for 4 to 5 hours, then add carbon conductive material, magnetic glass short fiber particles, and additives in sequence, and continue to stir at 70 to 80° C. for 4 to 5 hours to evenly disperse all materials to form conductive ink; The prepared conductive ink is coated on the surface of the copper foil or aluminum foil current collector, and then a vertical magnetic field is applied to the coating layer, and a drying process is performed under the action of the magnetic field to obtain a polymer composite material layer; Conductive copper tape or conductive aluminum tape is attached to the surface of the polymer composite material layer as the first metal electrode layer and the second metal electrode layer.

[0011] Furthermore, the chemical nickel plating process comprises the following steps: The glass short fiber particles are placed in an acetone solution for degreasing and cleaning, and then washed with distilled water, filtered and dried; the degreasing glass short fiber particles are immersed in a silane coupling agent solution with a concentration of 0.2-0.5%, immersed for 5-15 minutes, filtered and dried; the glass short fiber particles are immersed in a nitric acid solution with a concentration of 35%-55% for roughening and etching treatment, the time is 10-20 minutes, and the treatment temperature is 40-50°C; the roughened and etched glass short fiber particles are placed in a mixed solution of 10-15g / L tin chloride and 20-25g / L hydrochloric acid for sensitization treatment, the time is 5-10 minutes; the sensitized glass The short fiber particles are placed in a mixed solution of 0.5-1g / L lead chloride and 7-12g / L HCl for activation treatment for 5-20min; nickel chloride is dissolved in distilled water, and added to the sodium citrate solution after it is completely dissolved, and stirred evenly, and the sodium hypophosphite solution is slowly added to the above sodium citrate solution, diluted with distilled water, and the pH is adjusted to 3-5 with hydrochloric acid; the activated glass short fiber particles are placed in the plating solution for chemical nickel plating, the plating temperature is 40-60℃, the plating time is 1-2h, and the nickel plating process needs to be stirred; the nickel-plated glass short fiber particles are filtered out, washed with distilled water, and dried at 60-100℃ for 1h.

[0012] Furthermore, the insulating layer coating comprises the following steps: Dissolve 1 to 10 parts of polystyrene or polyethylene terephthalate in 50 to 100 parts of an insulating layer organic solvent, and heat and stir to completely dissolve it; place the nickel-plated glass short fiber particles in the above solvent and stir for 10 to 20 minutes; remove the organic solvent by spray drying to obtain nickel-plated magnetic glass short fiber particles coated with an insulating layer, and further dry them at 60 to 160°C; wherein the insulating layer organic solvent is one or more of xylene, N,N-dimethylformamide, chloroform, o-chlorophenol, and trifluoroacetic acid.

[0013] Furthermore, the polymer matrix solvent is one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and isopropanol.

[0014] Furthermore, the intensity of the magnetic field is 0.4-0.8T.

[0015] Furthermore, the drying treatment under the action of the magnetic field is horizontally placed in a forced air oven at 80 to 110° C. for 6 to 12 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects: In the first aspect, the present invention realizes the electric heating function through two layers of metal electrode layers and directional magnetic glass fiber particles, while using polymer composite materials to quickly accumulate heat, and also uses the mechanical strength of the glass fiber itself to enhance the internal support and stability of the electric heating composite film; the inner core is glass fiber, which provides structural strength and stability; the middle layer is nickel metal, which gives magnetism, facilitates directional arrangement in the magnetic field, and increases conductivity; the outer shell is an insulating layer to prevent short circuit caused by direct contact between particles, and protect the nickel metal layer from environmental corrosion. In addition, the magnetic glass fiber particles have a three-layer core-shell structure, and the nickel plating layer can improve the conductivity and heating capacity, increase the corrosion resistance of the glass fiber particles, and improve the hardness and wear resistance; the insulating layer can isolate the current and prevent the electric heating film electrodes, which are only hundreds of microns apart, from forming a short circuit due to overheating or external factors due to long-term use.

[0017] Furthermore, the mesh size of 400 to 1000 ensures good particle fineness of the glass staple fibers, ensures uniform distribution of the particles in the composite material and good filling effect, while avoiding the degradation of mechanical properties due to particle agglomeration; the nickel metal layer thickness of 0.1 to 2 μm is moderate, which not only ensures conductivity but also avoids the problems of increased cost and insufficient adhesion; the insulating layer thickness of 0.1 to 1 μm provides sufficient insulating performance, further enhancing the safety of the electric heating composite film.

[0018] Furthermore, the addition of polymer matrix, carbon conductive materials and additives optimizes the overall performance of the composite material. A variety of high-performance polymers, such as polyethylene oxide, polydimethylsiloxane, etc., are selected to meet different mechanical, thermal and electrical performance requirements; high conductive materials such as carbon nanotubes and graphite are added to form a conductive network to improve the heating efficiency and uniformity of the electric heating film; the addition of additives such as coupling agents and defoaming agents helps to improve the processing properties of the composite material and the performance stability of the final product.

[0019] Furthermore, the thickness range of 20 to 150 μm ensures that the electrothermal composite film has sufficient strength while maintaining good flexibility. At the same time, this thickness range reduces the driving voltage, making the electrothermal composite film suitable for a variety of application scenarios.

[0020] On the other hand, the present invention provides a detailed and systematic preparation method, which realizes the efficient preparation of the electrothermal composite film through chemical nickel plating, insulation layer coating, conductive ink preparation, coating and drying, and ensures the good combination between the glass short fiber particles and the polymer composite material layer and the metal electrode layer. A uniform and dense nickel metal layer is formed on the surface of the glass short fiber particles, laying the foundation for the subsequent insulation layer coating and magnetic oriented arrangement; a layer of insulating material is coated on the surface of the glass short fiber particles after nickel plating, which effectively prevents the short circuit problem caused by direct contact between particles, while maintaining the magnetic properties of the particles.

[0021] Furthermore, these steps ensure that the surface of the glass staple particles is uniformly plated with a layer of nickel, thereby improving its conductivity, hardness and corrosion resistance to ensure the best nickel plating effect.

[0022] Furthermore, the coating of the insulating layer further enhances the safety of the electrothermal composite film and prevents direct contact between the metal electrode layers. At the same time, the uniformity and thickness of the insulating layer are also effectively controlled.

[0023] Furthermore, these solvents can dissolve the polymer matrix well and form a good dispersion system with other ingredients, ultimately improving the film-forming properties.

[0024] Furthermore, the magnetic field strength of 0.4 to 0.8 T plays an important role in the coating process. It determines the arrangement effect of the magnetic glass short fiber particles in the polymer composite material layer, thereby improving the conductivity, physical support and mechanical strength of the electric heating composite film. After applying the conductive ink, a vertical magnetic field is applied to align the magnetic glass short fiber particles under the action of the magnetic field, which helps to improve the heating efficiency and uniformity of the electric heating film. At the same time, drying under the action of the magnetic field helps to maintain the oriented arrangement state of the particles.

[0025] Furthermore, the drying process is carried out in a blast oven at 80-110°C for 6-12 hours under the action of a magnetic field, which ensures that the solvent in the polymer composite layer is completely volatilized, and the magnetic glass short fiber particles can be shaped after being arranged by the magnetic field, thereby improving the performance in subsequent use. At the same time, this drying method also helps to maintain the flatness and uniformity of the electric heating composite film. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are only for explanation purposes and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes to help understand the present invention and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 This is a schematic structural diagram of a low-voltage driven high-safety electric heating composite membrane in Example 1; Figure 2 This is a heating curve of a low-voltage driven high-safety electric heating composite membrane in Example 1; Figure 3 The current value and the number of bends of a low-voltage driven high-safety electrothermal composite membrane in Examples 1 and 2 and the comparative example; Among them, 1. a first metal electrode layer; 2. a polymer composite material layer; 3. magnetic glass short fiber particles; 4. a second metal electrode layer. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0028] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0030] Embodiment 1: Example 1 provides a low-voltage driven high-safety electric heating composite membrane and a preparation method thereof, and the following are the specific steps.

[0031] The chemical nickel plating process includes the following steps: 101: Place 0.2 g of glass fiber particles in 4 ml of acetone solution to remove oil and wash, then wash with distilled water, filter and dry in an air-dried oven at 80 °C for 1 h; 102: Immerse the degreased glass short fiber particles in a 0.5% silane coupling agent solution for 15 minutes, filter and dry in an 80°C forced air oven for 1 hour; 103: Immerse the glass short fiber particles in a 35% nitric acid solution for roughening and etching for 20 minutes at a temperature of 50°C; 104: The roughened and etched glass fiber particles are placed in a 10g / L tin chloride (SnCl 2 ) and 20g / L hydrochloric acid (HCl) mixed solution for sensitization for 10min; 105: The sensitized glass fiber particles were placed in 0.5g / L lead chloride (PdCl 2) and 7g / L HCl mixed solution for activation treatment for 20 min; 106: Prepare chemical nickel plating solution: Dissolve nickel chloride (NiCl 2 ), add it to the sodium citrate solution after it is completely dissolved, stir evenly, and add sodium hypophosphite (NaH 2 PO 2 ) solution is slowly added to the above sodium citrate solution, diluted with distilled water, and the pH is adjusted to 3 with hydrochloric acid; 107: Plating the activated glass fiber particles in a plating solution for chemical nickel plating at a temperature of 60° C. for 1 h, with stirring required during the nickel plating process; 108: Filter out the nickel-plated glass fiber particles, wash with distilled water, and dry at 80°C for 2 hours.

[0032] The insulation layer coating includes the following steps: 201: Dissolve 0.1 g of polystyrene (PS) in 3 g of trifluoroacetic acid, heat and stir at 80 °C for 5 h to completely dissolve it; 202: placing the nickel-plated glass fiber particles in the above solvent and stirring for 10 minutes; 203: Removal of organic solvents by spray drying, with an inlet air temperature of 150°C, an exhaust air temperature of 100°C, and an air volume of 20 L / h −1 , nickel-plated glass fiber particles with polystyrene (PS) coating were obtained, and further dried at 80° C. Such chemical nickel plating treatment ensures good bonding between the glass fiber particles and the nickel metal layer.

[0033] The steps to prepare conductive ink include: 301: Dissolve 1 g of thermoplastic polyurethane elastomer (TPU) in 4 g of N-methylpyrrolidone (NMP) and heat and stir at 60 °C for 5 h; 302: Then, 1 g of graphite, 0.2 g of carbon nanotubes, 0.1 g of 1000 mesh magnetic glass short fiber particles 3, and 0.06 g of siloxane coupling agent were added in sequence, and stirring was continued at 70° C. for 3 h to make all the materials evenly dispersed.

[0034] The coating and orientation of magnetic glass staple fibers include the following steps: 401: The prepared conductive ink is coated on the surface of the copper foil current collector, and then a magnetic field with a vertical strength of 0.4 T is applied to the coating layer, and a drying treatment is performed under the action of the magnetic field. The drying temperature is 80° C. and the time is 12 hours to obtain a polymer composite material structure body.

[0035] The magnetic field strength of 0.4 T plays a key role in the coating process, not only facilitating the directional arrangement of the magnetic glass fiber particles 3, but also improving the overall performance and stability of the electrothermal composite film. This magnetic field treatment may also improve the microstructure of the polymer composite layer 2 to a certain extent, further improving its performance.

[0036] The drying temperature is 80°C and the time is 12 hours. Such medium-high temperature and long-term drying treatment ensures that the solvent in the polymer composite material layer 2 is completely volatilized, avoiding performance degradation and safety hazards in subsequent use. This drying method not only helps to maintain the flatness and uniformity of the electrothermal composite film, but also improves its overall quality and reliability. In addition, the appropriate drying temperature and time also help to optimize the thermal stability and service life of the electrothermal composite film.

[0037] Attaching the metal electrode layers 1 and 4 includes the following steps: 501 : Attaching conductive copper tapes to the upper and lower surfaces of the polymer composite material structure body as the first metal electrode layer 1 and the second metal electrode layer 4 .

[0038] The structure diagram of a low-voltage driven high-safety electric heating composite membrane obtained in Example 1 is as follows Figure 1 As shown, it includes a first metal electrode layer 1, a second metal electrode layer 4 and a polymer composite material layer 2 arranged between the two metal electrode layers; the polymer composite material layer 2 has a thickness of 20 μm and includes magnetic glass short fiber particles 3 arranged in a directional manner, and the magnetic glass short fiber particles 3 are used to prevent the two metal electrode layers from contacting to form a short circuit; the magnetic glass short fiber particles 3 are a three-layer core-shell structure, the inner core layer is glass short fiber particles, the middle layer is a nickel metal layer with a thickness of 0.1 μm, and the outer shell layer is an insulating layer with a thickness of 0.1 μm. The present invention realizes the electric heating function through two metal electrode layers 1 and 4 and the directional arrangement of magnetic glass short fiber particles 3, and utilizes the mechanical strength of the glass short fiber itself to enhance the internal support and stability of the electric heating composite film; the magnetic glass short fiber particles 3 have a three-layer core-shell structure, the nickel plating layer can improve the conductivity and heating capacity, increase the corrosion resistance of the glass short fiber particles, and improve the hardness and wear resistance; the insulating layer can isolate the current and prevent the electric heating film electrodes that are only hundreds of microns apart from being connected through the magnetic glass short fiber particles 3 to form a short circuit. The heating curve of the electrothermal composite film under 3V DC voltage is as follows Figure 2 As shown, the temperature reached 63°C.

[0039] Embodiment 2: Example 2 provides a low-voltage driven high-safety electric heating composite membrane and a preparation method thereof, and the following are the specific steps.

[0040] The chemical nickel plating process includes the following steps: 101: Place 0.2 g of 400 mesh glass fiber particles in 6 ml acetone solution to remove oil and wash, then wash with distilled water, filter and dry in an 80°C forced air oven for 1 h; 102: Immerse the degreased glass short fiber particles in a 0.2% silane coupling agent solution for 5 minutes, filter and dry in an 80°C forced air oven for 2 hours; 103: Immerse the glass short fiber particles in a nitric acid solution with a concentration of 55% for roughening and etching treatment for 10 minutes at a treatment temperature of 40°C; 104: The roughened and etched glass fiber particles are placed in a 15g / L tin chloride (SnCl 2 ) and 25g / L hydrochloric acid (HCl) mixed solution for sensitization for 5min; 105: The sensitized glass fiber particles were placed in 1g / L lead chloride (PdCl 2 ) and 12g / L HCl mixed solution for activation treatment for 5min; 106: Prepare chemical nickel plating solution: Dissolve nickel chloride (NiCl 2 ), add it to the sodium citrate solution after it is completely dissolved, stir evenly, and add sodium hypophosphite (NaH 2 PO 2 ) solution is slowly added to the above sodium citrate solution, diluted with distilled water, and the pH is adjusted to 5 with hydrochloric acid; 107: The activated glass short fiber particles are placed in a plating solution for chemical nickel plating at a plating temperature of 40°C for 2 hours. The nickel plating process requires stirring. The nickel-plated glass short fiber particles are filtered out, washed with distilled water, and dried at 100°C for 1 hour.

[0041] The nickel metal layer has a thickness of 2 μm.

[0042] The insulation layer coating includes the following steps: 201: Dissolve 0.2 g of polyethylene terephthalate (PET) in 3 g of N,N-dimethylformamide (DMF), heat and stir at 70 °C for 3 h to completely dissolve it; 202: placing the nickel-plated glass fiber particles in the above solvent and stirring for 20 minutes; 203: Removal of organic solvents by spray drying, with an inlet air temperature of 160°C, an exhaust air temperature of 120°C, and an air volume of 20 L / h −1 , nickel-plated glass staple particles coated with polystyrene (PS) were obtained, and further dried at 60°C.

[0043] The thickness of the insulating layer is 1 μm.

[0044] The steps to prepare conductive ink include: 301: Dissolve 1.5 g of polyvinylidene fluoride (PVDF) in 5 g of N-methylpyrrolidone (NMP) and heat and stir at 80 °C for 4 h; 302: Then, 0.5 g of graphite, 0.2 g of acetylene black, 0.1 g of magnetic glass fiber particles 3, and 0.04 g of siloxane coupling agent were added in sequence, and stirring was continued at 80° C. for 4 h to make all the materials evenly dispersed; The coating and orientation of magnetic glass staple fibers include the following steps: 401: The conductive ink prepared in S3 is coated on the surface of the aluminum foil current collector, and then a magnetic field with a vertical strength of 0.8 T is applied to the coating layer, and a drying treatment is performed under the action of the magnetic field. The drying temperature is 110° C. and the time is 6 hours to obtain a polymer composite material structure body.

[0045] The polymer composite material layer 2 has a thickness of 150 μm.

[0046] Attaching the metal electrode layers 1 and 4 includes the following steps: 501 : Attaching conductive aluminum tapes to the upper and lower surfaces of the polymer composite material structure body as the first metal electrode layer 1 and the second metal electrode layer 4 .

[0047] The low-voltage driven high-safety electrothermal composite membrane obtained in Example 2 can generate heat at a temperature of up to 45° C. at a DC voltage of 2V.

[0048] Embodiment 3: Example 3 provides a low-voltage driven high-safety electric heating composite membrane and a preparation method thereof, and the following are the specific steps.

[0049] The chemical nickel plating process includes the following steps: 101: Place 0.2 g of 600 mesh glass fiber particles in 7.5 ml acetone solution to remove oil and wash, then wash with distilled water, filter and dry in an 80°C forced air oven for 1 h; 102: Immerse the degreased glass short fiber particles in a 0.4% silane coupling agent solution for 10 minutes, filter and dry in an 80°C forced air oven for 3 hours; 103: Immerse the glass short fiber particles in a nitric acid solution with a concentration of 45% for roughening and etching treatment for 15 minutes at a treatment temperature of 45°C; 104: The roughened and etched glass fiber particles are placed in a 12g / L tin chloride (SnCl 2 ) and 22g / L hydrochloric acid (HCl) mixed solution for sensitization for 8min; 105: The sensitized glass fiber particles were placed in 0.7g / L lead chloride (PdCl2 ) and 10g / L HCl mixed solution for activation treatment for 15min; 106: Prepare chemical nickel plating solution: Dissolve nickel chloride (NiCl 2 ), add it to the sodium citrate solution after it is completely dissolved, stir evenly, and add sodium hypophosphite (NaH 2 PO 2 ) solution is slowly added to the above sodium citrate solution, diluted with distilled water, and the pH is adjusted to 4 with hydrochloric acid; 107: The activated glass short fiber particles are placed in a plating solution for chemical nickel plating at a plating temperature of 50°C for 1.5 hours. The nickel plating process requires stirring. The nickel-plated glass short fiber particles are filtered out, washed with distilled water, and dried at 60°C for 1 hour.

[0050] The nickel metal layer has a thickness of 1 μm.

[0051] The insulation layer coating includes the following steps: 201: Dissolve 0.2 g of polyethylene terephthalate (PET) in 3 g of N,N-dimethylformamide (DMF), heat and stir at 70 °C for 3 h to completely dissolve it; 202: placing the nickel-plated glass fiber particles in the above solvent and stirring for 20 minutes; 203: Removal of organic solvents by spray drying, with an inlet air temperature of 160°C, an exhaust air temperature of 120°C, and an air volume of 20 L / h −1 , nickel-plated glass staple particles coated with polystyrene (PS) were obtained, and further dried at 60°C.

[0052] The thickness of the insulating layer is 1 μm.

[0053] The steps to prepare conductive ink include: 301: 1.6 g of polyethersulfone resin (PES) was dissolved in 7 g of N-methylpyrrolidone (NMP) and heated and stirred at 80 °C for 6 h; 302: Then, 0.4 g of graphite, 0.15 g of acetylene black, 0.1 g of magnetic glass fiber particles 3, and 0.04 g of siloxane coupling agent were added in sequence, and stirring was continued at 80° C. for 6 h to make all the materials evenly dispersed; The coating and orientation of magnetic glass staple fibers include the following steps: 401: The conductive ink prepared in S3 is coated on the surface of the aluminum foil current collector, and then a magnetic field with a vertical strength of 0.6 T is applied to the coating layer, and a drying treatment is performed under the action of the magnetic field. The drying temperature is 95° C. and the time is 9 hours to obtain a polymer composite material structure body.

[0054] The polymer composite material layer 2 has a thickness of 100 μm.

[0055] Attaching the metal electrode layers 1 and 4 includes the following steps: 501 : Attaching conductive copper tape and conductive aluminum tape to the upper and lower surfaces of the polymer composite material structure body as the first metal electrode layer 1 and the second metal electrode layer 4 respectively.

[0056] The low-voltage driven high-safety electrothermal composite membrane obtained in Example 2 can generate heat at a temperature of 55° C. at a DC voltage of 3V.

[0057] Comparative Example: The comparative example provides an electric heating composite film containing magnetic glass short fibers and a preparation method thereof, and the following are the specific steps.

[0058] Preparation of conductive ink: Dissolve 1g of thermoplastic polyurethane elastomer (TPU) in 4g of N-methylpyrrolidone (NMP), heat and stir at 60°C for 5h, then add 1g of graphite, 0.2g of carbon nanotubes, 0.1g of magnetic glass short fiber particles 3, and 0.06g of siloxane coupling agent in sequence, and continue stirring at 70°C for 3h to make all materials evenly dispersed.

[0059] The conductive ink prepared in 101 is coated on the surface of the copper foil current collector, and then dried at a temperature of 80° C. for 12 h to obtain a main body of the polymer composite material structure.

[0060] Conductive copper tapes are attached to the upper and lower surfaces of the polymer composite material structure body as two metal electrodes.

[0061] The two electrothermal composite films obtained in Comparative Example 1 and Example 1 were subjected to a 90° bending experiment under the same voltage working state, and the current value after each bending was recorded. The relationship curve between the current value and the number of bending times is shown in FIG. Figure 3 The results show that the current value of the electrothermal composite membrane prepared in Comparative Example 1 increases rapidly only after being bent 50 times, indicating that structural failure and micro short circuit are prone to occur inside it, while the current value of a low-voltage driven high-safety electrothermal composite membrane in Example 1 tends to remain stable after being bent 200 times.

[0062] Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a disclaimer of such subject matter, nor should it be considered that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

[0063] The above content is a further detailed description of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, they can also make several simple deductions or substitutions, which should be regarded as belonging to the protection scope of the present invention determined by the submitted claims.

Claims

1. A low-voltage driven high-safety electric heating composite membrane, characterized in that: The invention comprises a first metal electrode layer (1), a second metal electrode layer (4) and a polymer composite material layer (2) arranged between the two metal electrode layers; the polymer composite material layer (2) comprises magnetic glass short fiber particles (3) arranged in a direction, and the magnetic glass short fiber particles (3) are used to prevent the two metal electrode layers from contacting and forming a short circuit; the magnetic glass short fiber particles (3) are a three-layer core-shell structure, wherein the inner core layer is glass short fiber particles, the middle layer is a nickel metal layer, and the outer shell layer is an insulating layer.

2. A low-voltage driven high-safety electric heating composite membrane according to claim 1, characterized in that: The magnetic glass short fiber particles (3) are 400-1000 mesh particle powders; the nickel metal layer is achieved by chemical plating and has a thickness of 0.1-2 μm; the insulating layer is one or more of polystyrene or polyethylene terephthalate and has a thickness of 0.1-1 μm.

3. A low-voltage driven high-safety electric heating composite membrane according to claim 1, characterized in that: The polymer composite material layer (2) further comprises a polymer matrix, a carbon conductive material and an additive; the polymer matrix is ​​one or more of polyethylene oxide, polydimethylsiloxane, thermoplastic polyurethane elastomer, polyethersulfone resin, polyvinylidene fluoride, and polymethyl methacrylate; the carbon conductive material is one or more of carbon nanotubes, carbon fibers, graphite, acetylene black, and graphene; and the additive is one or more of a coupling agent, a defoaming agent, a leveling agent, and a surfactant.

4. A low-voltage driven high-safety electric heating composite membrane according to claim 1, characterized in that: The thickness of the polymer composite material layer (2) is 20 to 150 μm.

5. A method for preparing a low-voltage driven high-safety electric heating composite membrane according to any one of claims 1 to 4, characterized in that: The following steps are involved: Chemical nickel plating of glass staple particles; The nickel-plated glass short fiber particles are coated with an insulating layer to prepare magnetic glass short fiber particles (3); Dissolving 20 to 50 parts of a polymer matrix in 300 to 600 parts of a polymer matrix solvent, and heating and stirring at 60 to 80° C. for 4 to 5 hours, then sequentially adding a carbon conductive material, magnetic glass short fiber particles (3), and an additive, and continuing to stir at 70 to 80° C. for 4 to 5 hours to evenly disperse all the materials, thereby forming a conductive ink; The prepared conductive ink is coated on the surface of the copper foil or aluminum foil current collector, and then a vertical magnetic field is applied to the coating layer, and the coating layer is dried under the action of the magnetic field to obtain a polymer composite material layer (2); Conductive copper tape or conductive aluminum tape is attached to the surface of the polymer composite material layer (2) as the first metal electrode layer (1) and the second metal electrode layer (4).

6. The method for preparing a low-voltage driven high-safety electric heating composite membrane according to claim 5, characterized in that: The chemical nickel plating process comprises the following steps: The glass fiber particles are placed in an acetone solution to remove oil and clean, and then washed with distilled water, filtered and dried; Immerse the degreased glass short fiber particles in a silane coupling agent solution with a concentration of 0.2-0.5% for 5-15 minutes, filter and dry; The glass short fiber particles are immersed in a nitric acid solution with a concentration of 35% to 55% for roughening and etching for 10 to 20 minutes at a temperature of 40 to 50°C; The roughened and etched glass short fiber particles are placed in a mixed solution of 10-15 g / L tin chloride and 20-25 g / L hydrochloric acid for sensitization for 5-10 minutes; The sensitized glass short fiber particles are placed in a mixed solution of 0.5-1 g / L lead chloride and 7-12 g / L HCl for activation for 5-20 minutes; Dissolve nickel chloride in distilled water, add it to the sodium citrate solution after it is completely dissolved, stir evenly, and slowly add the sodium hypophosphite solution to the above sodium citrate solution, dilute it with distilled water, and adjust the pH to 3-5 with hydrochloric acid; The activated glass short fiber particles are placed in a plating solution for chemical nickel plating at a plating temperature of 40 to 60°C for 1 to 2 hours, and the nickel plating process requires stirring; The nickel-plated glass fiber particles are filtered out, washed with distilled water, and dried at 60-100° C. for 1 h.

7. The method for preparing a low-voltage driven high-safety electric heating composite membrane according to claim 5, characterized in that: The insulation layer coating comprises the following steps: Dissolve 1 to 10 parts of polystyrene or polyethylene terephthalate in 50 to 100 parts of an organic solvent for an insulating layer, and heat and stir to completely dissolve; The nickel-plated glass short fiber particles are placed in the above solvent and stirred for 10 to 20 minutes; The organic solvent is removed by spray drying to obtain nickel-plated magnetic glass short fiber particles (3) coated with an insulating layer, and further dried at 60 to 160° C.; wherein the organic solvent of the insulating layer is one or more of xylene, N,N-dimethylformamide, chloroform, o-chlorophenol, and trifluoroacetic acid.

8. The method for preparing a low-voltage driven high-safety electric heating composite membrane according to claim 5, characterized in that: The polymer matrix solvent is one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and isopropanol.

9. The method for preparing a low-voltage driven high-safety electric heating composite membrane according to claim 5, characterized in that: The intensity of the magnetic field is 0.4-0.8T.

10. The method for preparing a low-voltage driven high-safety electric heating composite membrane according to claim 5, characterized in that: The drying treatment under the action of the magnetic field is to place the mixture horizontally in a forced air oven at 80 to 110° C. for 6 to 12 hours.

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