A conductive heating plate for a hair straightener and its preparation process

Abstract

The present invention provides a conductive heating plate for a hair straightener and its preparation process, belonging to the technical field of the preparation of conductive heating plates; the preparation process includes the following steps: preparation of a graphene composite mixture; preparation of modified doped three-dimensional boron nitride; preparation of a thermal insulation layer; preparation of a heat insulation layer; preparation of a conductive heating plate. The present invention prepares a conductive heating plate by sequentially arranging a ceramic substrate, a thermal insulation layer, a graphene composite heating layer, a conductive layer, and a heat insulation layer from bottom to top. During the frequent heating and cooling cycles of the hair straightener, the graphene composite heating layer can maintain its performance unchanged and will not affect the heating effect due to material aging or performance attenuation. As the outermost layer of the conductive heating plate, the heat insulation layer can block the heat generated by the heating element and effectively prevent the heat from being transferred to parts such as the shell and handle of the hair straightener.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive heating plate preparation, and particularly relates to a conductive heating plate for a hair straightener and its preparation process. Background Art

[0002] With the continuous improvement of people's requirements for personal image and hair styling, the hair straightener, as a commonly used hair styling tool, has been widely used in the market. Its working principle is mainly to generate heat through a conductive heating plate and use the heat to change the shape of the hair, thereby achieving the straight hair effect.

[0003] In the prior art, the heating elements in the conductive heating plates of hair straighteners are usually mostly ceramic heating elements and PTC heating elements. The ceramic heating element shows a relatively fast heating rate. Generally, it can make the surface temperature of the clamping plate reach about 200 degrees in 30 seconds to 45 seconds, which can quickly meet the straight hair requirement. However, the ceramic heating element is sintered at a high temperature above 1000 degrees. Once the circuit loses control, its temperature will quickly exceed 300 degrees, easily burning out the plastic material fixing the heating plate and causing the heating plate to fall off. The PTC heating element has a slower heating rate to 200 degrees, generally taking about one and a half to two minutes, and during use, it cannot continuously maintain a relatively high temperature like the ceramic heating element. Therefore, the effect of straightening hair is relatively poor. Moreover, in the existing hair straighteners, the heating rate of the heating element becomes slower during frequent use, so it requires a longer time for preheating, affecting the user experience.

[0004] Therefore, we propose a conductive heating plate for a hair straightener and its preparation process, aiming to solve the problems existing in the application of the existing heating elements in hair straighteners, such as the slower heating rate and the easy burning out of the plastic material fixing the heating plate. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a conductive heating plate for a hair straightener and its preparation process.

[0006] A preparation process of a conductive heating plate for a hair straightener includes the following steps:

[0007] S1: Preparation of graphene composite mixture

[0008] Using polyvinyl alcohol, sodium carboxymethyl cellulose and sodium dodecylbenzenesulfonate as the mixture, and then adding a conductive dispersion liquid prepared from onion carbon, modified graphene oxide and polyacrylonitrile, and mixing them to prepare a graphene composite mixture;

[0009] S2: Preparation of modified doped three-dimensional boron nitride

[0010] Three-dimensional boron nitride is prepared using sodium chloride as a template, and the three-dimensional boron nitride is modified with a silane coupling agent and then further modified by plasma carbon doping to obtain modified and doped three-dimensional boron nitride;

[0011] S3: Preparation of the thermal conductive and insulating layer

[0012] Using modified nano-aluminum oxide and modified and doped three-dimensional boron nitride as thermal conductive fillers, 4,4'-diaminodiphenyl ether and pyromellitic dianhydride are then added to prepare a spinning solution for electrospinning to obtain a thermal conductive and insulating spinning film, which is then impregnated in a reaction glue solution composed of 4,4'-diaminodiphenyl ether, N,N'-dimethylacetamide solution and pyromellitic dianhydride, and finally vacuum dried to obtain a thermal conductive and insulating film, which is the thermal conductive and insulating layer;

[0013] S4: Preparation of the heat insulating and insulating layer

[0014] Using benzoxazine monomer, ZIF-L powder and tetraethyl orthosilicate as raw materials to prepare a heat insulating and insulating gel, which is the heat insulating and insulating layer;

[0015] S5: Preparation of the conductive heating plate

[0016] Using a graphene composite mixture to prepare a graphene composite heating layer, and stacking a ceramic substrate, a thermal conductive and insulating layer, a graphene composite heating layer, a conductive layer and a heat insulating and insulating layer in sequence from bottom to top and pressing them with a press to obtain a conductive heating plate.

[0017] Furthermore, the preparation of the graphene composite mixture in step S1 specifically includes the following steps:

[0018] S1.1: Add 2-3 parts by weight of polyvinyl alcohol and 0.3-0.5 parts by weight of sodium carboxymethylcellulose to 80-100 parts by weight of deionized water, and then add 0.2-0.3 parts by weight of sodium dodecylbenzenesulfonate, and stir and mix at 80-85 °C for 2-3 h to obtain a mixed solution;

[0019] S1.2: Add 2-3 parts by weight of onion carbon and 5-8 parts by weight of modified graphene oxide to 50-60 parts by weight of N,N-dimethylformamide, ultrasonically mix at room temperature for 30-40 min, and then add 12-15 parts by weight of polyacrylonitrile, and stir and mix at 60-65 °C for 24-25 h to obtain a conductive dispersion;

[0020] S1.3: Add the conductive dispersion to the mixed solution, stir and mix at 70-75 °C for 6-8 h, and then cool and let stand for 24-25 h to obtain a graphene composite mixture.

[0021] Furthermore, the preparation of the modified and doped three-dimensional boron nitride in step S2 specifically includes the following steps:

[0022] S2.1: Add 12 - 13 parts by weight of saturated sodium chloride to 20 - 22 parts by weight of alcohol, then carry out vacuum filtration and drying to obtain micron-sized sodium chloride crystals. Mix 10 - 12 parts by weight of the micron-sized sodium chloride crystals with 2 - 3 parts by weight of boron trioxide and place them in an alumina crucible. Then place the alumina crucible in a tube furnace, introduce argon, and heat it to 500 - 520 °C at a rate of 10 - 12 °C / min;

[0023] S2.2: After reaching 500 - 520 °C, turn off the argon, introduce ammonia gas, continue heating to 700 - 720 °C, keep the temperature for 20 - 30 min, then heat it again to 1100 - 1200 °C, keep the temperature for 10 - 20 min. After cooling to room temperature, wash the obtained precipitate with deionized water, then carry out vacuum filtration and drying, and dry it at 60 - 65 °C for 10 - 12 h to obtain three-dimensional boron nitride;

[0024] S2.3: Add 3 - 5 parts by weight of the three-dimensional boron nitride to 10 - 12 parts by weight of absolute ethanol, stir at 50 - 60 °C under ultrasonic conditions and at 5000 - 6000 r / min for 20 - 30 min, then add 0.2 - 0.3 parts by weight of a 20 - 30 wt% aqueous solution of silane coupling agent KH560, continue stirring for 40 - 50 min, then place it in an oven and dry it at 60 - 70 °C, grind and pulverize to obtain silane coupling agent-modified three-dimensional boron nitride;

[0025] S2.4: Place the silane coupling agent-modified three-dimensional boron nitride in a plasma reaction device, evacuate to -2800 kPa to -3000 kPa, then introduce ethylene and nitrogen to -2000 kPa to -2200 kPa, then evacuate again to -2800 kPa to -3000 kPa and introduce ethylene and nitrogen to -1300 kPa to -1500 kPa, and finally evacuate again to -2800 kPa to -3000 kPa. Carry out plasma discharge at a voltage of 28 - 30 kV and a frequency of 9 - 10 kHz for 15 - 20 min to obtain modified doped three-dimensional boron nitride.

[0026] Furthermore, in step S2.4, the weight ratio of ethylene to nitrogen is 1 - 2:25.

[0027] Furthermore, the preparation of the thermal conductive insulating layer in step S3 specifically includes the following steps:

[0028] S3.1: Add 0.02 - 0.05 parts by weight of silane coupling agent KH550 to 100 - 120 parts by weight of ethanol, then add glacial acetic acid dropwise to adjust the pH value to 3 - 4. After hydrolysis for 20 - 30 min, add 2 - 3 parts by weight of nano-aluminum trioxide, ultrasonically mix for 1 - 2 h, and stir for 2 - 3 h in a water bath at 70 - 80 °C. After filtration, wash with absolute ethanol 2 - 3 times, and dry to obtain modified nano-aluminum trioxide;

[0029] S3.2: Add 0.2 - 0.3 parts by weight of modified nano-aluminum trioxide and 0.5 - 0.7 parts by weight of modified doped three-dimensional structure boron nitride to 20 - 30 parts by weight of N,N'-dimethylacetamide solution, ultrasonically stir and mix for 8 - 10 h. Under a nitrogen atmosphere, add 1 - 2 parts by weight of 4,4'-diaminodiphenyl ether, stir and mix for 20 - 30 min, then add pyromellitic dianhydride in three portions under ice bath conditions, each time adding 0.3 - 0.5 parts by weight of pyromellitic dianhydride, stir and mix for 20 - 30 min to obtain a spinning solution. Electrospinning is carried out at a spinning voltage of 20 - 22 kV, a receiving distance of 20 - 22 cm, and a pushing speed of 0.8 - 0.9 mm / min to obtain a thermally conductive and insulating spun film;

[0030] S3.3: Dissolve 2 - 3 parts by weight of 4,4'-diaminodiphenyl ether in 50 - 60 parts by weight of N,N'-dimethylacetamide solution, then add 2 - 3 parts by weight of pyromellitic dianhydride, react for 4 - 5 h to obtain a reaction adhesive solution. Immerse the thermally conductive and insulating spun film in the reaction adhesive solution for 4 - 5 h, then carry out vacuum drying to obtain a thermally conductive and insulating film, which is the thermally conductive and insulating layer.

[0031] Furthermore, the preparation of the heat insulation and insulation layer in step S4 specifically includes the following steps:

[0032] S4.1: Add 4 - 5 parts by weight of zinc nitrate hexahydrate and 16 - 18 parts by weight of 2-methylimidazole to 500 - 520 parts by weight of deionized water respectively, stir and mix to dissolve for 4 - 5 h to obtain a zinc nitrate hexahydrate solution and a 2-methylimidazole solution;

[0033] S4.2: Add the zinc nitrate hexahydrate solution to the 2-methylimidazole solution, continue to stir and mix for 4 - 5 h, then centrifuge at 8000 - 9000 r / min, filter to obtain a precipitate, wash the precipitate with deionized water and then dry to obtain ZIF-L powder;

[0034] S4.3: Add 2 - 3 parts by weight of benzoxazine monomer into 60 - 70 parts by weight of N,N - dimethylformamide solution. After stirring and dissolving, add 2 - 3 parts by weight of hydrochloric acid solution with a concentration of 2 mol / L, stir and mix for 10 - 12 min. Then add 12 - 15 parts by weight of tetraethyl orthosilicate, continue to stir and mix for 20 - 30 min. Finally, add 0.2 - 0.5 parts by weight of ZIF - L powder, and disperse it by ultrasonic for 1 - 2 h to obtain a heat - insulating and insulating gel solution;

[0035] S4.4: Inject the heat - insulating and insulating gel solution into a polypropylene tank to seal the gel. The gel time is 7 - 8 h, then age for 48 - 50 min. Finally, perform solvent replacement and atmospheric drying to obtain a heat - insulating and insulating gel, which is the heat - insulating and insulating layer.

[0036] Further, the preparation of the conductive heating plate in step S5 specifically includes the following steps:

[0037] S5.1: Form a composite film by electrospinning the graphene composite mixture. In electrospinning, the distance between the needle tip and the collecting device is 15 - 18 cm, the voltage is 15 - 16 kV, and the injection speed is 0.5 - 0.8 mm / min. Then heat the composite film at 280 - 300 °C for 2 - 3 h, and then keep it at 700 - 800 °C for 10 - 12 min in a nitrogen atmosphere to obtain a graphene composite heating layer;

[0038] S5.2: Use an etching machine to etch the designed circuit onto the conductor circuit layer. Then print the cured electronic paste onto the circuit of the conductor circuit layer, and cure it at 180 - 200 °C for 10 - 20 min to form a conductive layer. Stack the ceramic substrate, heat - conducting and insulating layer, graphene composite heating layer, conductive layer, and heat - insulating and insulating layer in order from top to bottom, and press them with a press to obtain a composite board. The pressing temperature is controlled at 300 - 320 °C to obtain a conductive heating plate.

[0039] Further, the ceramic substrate in step S5.2 is one of an alumina ceramic substrate and a aluminum nitride ceramic substrate.

[0040] Further, the conductor circuit layer in step S5.2 is made of one of copper, aluminum, copper foil, and aluminum foil materials.

[0041] A conductive heating plate for a hair straightener is prepared by the preparation process of a conductive heating plate for a hair straightener described in any one of the above.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] 1. The present invention prepares a conductive heating plate by sequentially arranging a ceramic substrate, a thermally conductive insulating layer, a graphene composite heating layer, a conductive layer, and a heat insulating insulating layer from bottom to top. During the frequent heating and cooling cycles of the hair straightener, the graphene composite heating layer can maintain its performance unchanged and will not affect the heating effect due to material aging or performance attenuation. As the outermost layer of the conductive heating plate, the heat insulating insulating layer can block the heat generated by the heating element, effectively preventing the heat from being transferred to parts such as the housing and handle of the hair straightener. During the operation of the hair straightener, it can concentrate the heat in the heating plate area, improve the utilization efficiency of heat, reduce energy waste, and at the same time, it can also prevent the user from being scalded when touching the overheated part during the operation of the hair straightener, improving the safety and comfort of the hair straightener.

[0044] 2. The present invention adds a conductive dispersion liquid to the mixed liquid and then performs electrospinning. Polyvinyl alcohol and sodium carboxymethyl cellulose can adjust the viscosity of the graphene composite mixed liquid, contribute to the formation of fibers during the electrospinning process, and can evenly distribute graphene and onion carbon in the polyacrylonitrile carbonized fibers, avoiding performance unevenness caused by local agglomeration. In a high-temperature nitrogen environment, polyacrylonitrile is carbonized to form a carbonaceous structure. After doping with onion carbon and graphene, it forms a complex three-dimensional network structure with the carbonaceous structure. The carbonized polyacrylonitrile, onion carbon, and graphene cooperate with each other, providing more transmission channels and scattering centers for electrons, enabling electrons to move more efficiently in three-dimensional space, thereby reducing the migration resistance of electrons, improving the overall electrical conductivity, and then accelerating the heating speed.

[0045] 3. The present invention prepares three-dimensional boron nitride with a three-dimensional structure through a sodium chloride template, modifies it with a silane coupling agent and performs carbon doping. Compared with the traditional two-dimensional structure, the three-dimensional structure can provide more heat conduction paths. After carbon doping, on the one hand, the introduction of carbon atoms will form new heat conduction channels in the boron nitride lattice and enhance the heat conduction ability of the original channels. On the other hand, after carbon atoms enter the boron nitride lattice, they will interact with boron atoms and nitrogen atoms, changing the scattering mechanism of lattice vibration, reducing phonon scattering, increasing the mean free path of phonons for heat transfer, and then increasing the thermal conductivity. Moreover, the arrangement of aluminum and oxygen atoms in the crystal structure of the modified nano-aluminum oxide is beneficial to the transmission of phonons, and the three-dimensional structure of boron nitride provides a multi-directional propagation path for phonons. The combination of the two greatly improves the heat conduction efficiency, thus effectively improving the heat conduction efficiency and achieving the effect of rapid heating.

[0046] 4. In the thermal conductive insulating layer of the present invention, the surface properties of the nano-aluminum trioxide and three-dimensional structure boron nitride modified by the silane coupling agent are changed, reducing the surface charge active sites and lowering the conductivity of the material. At the same time, during the preparation process, the polyimide network structure formed by the reaction of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride wraps around the thermal conductive fillers, further enhancing the insulation performance. The polyimide network structure has a high resistivity and can effectively prevent the movement of electrons, thus achieving a good electrical insulation effect. When impregnated with the reaction adhesive solution and dried, the polymer in the reaction adhesive solution further fills the voids between the fibers and undergoes a cross-linking reaction with the fibers, forming a more compact and solid structure, thereby improving the structural stability of the thermal conductive insulating layer.

[0047] 5. In the preparation of the heat insulating and insulating layer of the present invention, the heat insulating and insulating gel is prepared by polymerizing benzoxazine monomers and hydrolyzing tetraethyl orthosilicate and then adding ZIF-L powder. The polymer and network structure formed after the polymerization of benzoxazine monomers and the hydrolysis of tetraethyl orthosilicate itself have certain heat insulation properties and can block the conduction of heat. The ZIF-L powder has a special microporous structure, and its pore size can effectively limit the thermal motion of gas molecules, reducing the heat transfer through gas convection and conduction. The ZIF-L powder has physical adsorption or chemical bonding with the polymer molecular chains, enhancing the internal interaction force of the gel. The ZIF-L powder is dispersed in the polymer and network structure, increasing the tortuosity of the heat propagation path, thereby further enhancing the heat insulation ability of the entire gel system, enabling the prepared heat insulating and insulating layer to better block the diffusion of heat inside the hair straightener, reducing the heat dissipation to the external environment, improving the thermal efficiency of the hair straightener, reducing the waste of energy, and also preventing adverse effects such as scalding the user due to overheating. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings incorporated herein and constituting a part of the specification illustrate embodiments of the present invention and, together with the specification, are further used to explain the principles of the present invention and enable those skilled in the relevant art to implement and use the present invention.

[0049] Figure 1 It is a process flow chart of the preparation of a conductive heating plate for a hair straightener adopted in an embodiment of the present invention.

[0050] Figure 2 It is a schematic structural diagram of a conductive heating plate for a hair straightener of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] The preparation process of a conductive heating plate for a hair straightener provided by the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. At the same time, it should be noted here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments. For some well-known technologies, those skilled in the art can also adopt other alternative methods for implementation; moreover, the accompanying drawings are only for more specifically describing the embodiments and are not intended to specifically limit the present invention.

[0052] Example 1

[0053] A preparation process of a conductive heating plate for a hair straightener, as Figure 1 - Figure 2 shown, includes the following steps:

[0054] S1: Preparation of graphene composite mixture

[0055] S1.1: Add 2 parts by weight of polyvinyl alcohol and 0.3 parts by weight of sodium carboxymethylcellulose to 80 parts by weight of deionized water, then add 0.2 parts by weight of sodium dodecylbenzenesulfonate, and stir and mix at 80 °C for 2 h to obtain a mixture;

[0056] S1.2: Add 2 parts by weight of onion carbon and 5 parts by weight of modified graphene oxide to 50 parts by weight of N,N-dimethylformamide, ultrasonically mix at room temperature for 30 min, then add 12 parts by weight of polyacrylonitrile, and stir and mix at 60 °C for 24 h to obtain a conductive dispersion;

[0057] S1.3: Add the conductive dispersion to the mixture, stir and mix at 70 °C for 6 h, then cool and let stand for 24 h to obtain a graphene composite mixture;

[0058] S2: Preparation of modified doped three-dimensional boron nitride

[0059] S2.1: Add 12 parts by weight of saturated sodium chloride to 20 parts by weight of alcohol, then perform vacuum filtration and drying to obtain micron-sized sodium chloride crystals. Mix 10 parts by weight of the micron-sized sodium chloride crystals with 2 parts by weight of boron trioxide and place them in an alumina crucible. Then place the alumina crucible in a tube furnace, introduce argon, and heat to 500 °C at a rate of 10 °C / min;

[0060] S2.2: After reaching 500 °C, close the argon, introduce ammonia gas, continue heating to 700 °C, hold for 20 min, then heat again to 1100 °C, hold for 10 min. After cooling to room temperature, wash the obtained precipitate with deionized water, then perform vacuum filtration and drying, and dry at 60 °C for 10 h to obtain three-dimensional boron nitride;

[0061] S2.3: Add 3 parts by weight of three-dimensional boron nitride to 10 parts by weight of absolute ethanol, stir at 5000 r / min under ultrasonic conditions at 50 °C for 20 min, then add 0.2 parts by weight of 20 wt% aqueous solution of silane coupling agent KH560, continue stirring for 40 min, then place in an oven and dry at 60 °C, grind and pulverize to obtain silane coupling agent-modified three-dimensional boron nitride;

[0062] S2.4: Place the silane coupling agent-modified three-dimensional boron nitride in a plasma reaction device, evacuate to -2800 kPa, then introduce ethylene and nitrogen to -2000 kPa, then evacuate again to -2800 kPa and introduce ethylene and nitrogen to -1300 kPa, and finally evacuate again to -2800 kPa, perform plasma discharge at 28 kV voltage and 9 kHz frequency for 15 min to obtain modified doped three-dimensional boron nitride, and the weight ratio of ethylene to nitrogen is 1:25;

[0063] S3: Preparation of thermal conductive insulating layer

[0064] S3.1: Add 0.02 parts by weight of silane coupling agent KH550 to 100 parts by weight of ethanol, then dropwise add glacial acetic acid to adjust the pH value to 3, hydrolyze for 20 min, then add 2 parts by weight of nano-aluminum trioxide, ultrasonically mix for 1 h, and stir in a 70 °C water bath for 2 h, filter and wash with absolute ethanol 2 times, and dry to obtain modified nano-aluminum trioxide;

[0065] S3.2: Add 0.2 parts by weight of modified nano-aluminum trioxide and 0.5 parts by weight of modified doped three-dimensional boron nitride to 20 parts by weight of N,N'-dimethylacetamide solution, ultrasonically stir and mix for 8 h, under a nitrogen atmosphere, add 1 part by weight of 4,4'-diaminodiphenyl ether, stir and mix for 20 min, then add pyromellitic dianhydride in three portions under ice bath conditions, 0.3 parts by weight of pyromellitic dianhydride each time, stir and mix for 20 min, then obtain a spinning solution, and perform electrospinning at a spinning voltage of 20 kV, a receiving distance of 20 cm, and a pushing speed of 0.8 mm / min to obtain a thermal conductive insulating spun film;

[0066] S3.3: Dissolve 2 parts by weight of 4,4'-diaminodiphenyl ether in 50 parts by weight of N,N'-dimethylacetamide solution, then add 2 parts by weight of pyromellitic dianhydride, react for 4 h to obtain a reaction adhesive solution, immerse the thermal conductive insulating spun film in the reaction adhesive solution for 4 h, then perform vacuum drying to obtain a thermal conductive insulating film, which is the thermal conductive insulating layer;

[0067] S4: Preparation of heat insulating insulating layer

[0068] S4.1: Add 4 parts by weight of zinc nitrate hexahydrate and 16 parts by weight of 2-methylimidazole to 500 parts by weight of deionized water respectively, stir and mix to dissolve for 4 h to obtain a zinc nitrate hexahydrate solution and a 2-methylimidazole solution;

[0069] S4.2: Add the zinc nitrate hexahydrate solution to the 2-methylimidazole solution, continue to stir and mix for 4 h, then centrifuge at 8000 r / min, filter to obtain a precipitate, wash the precipitate with deionized water and then dry to obtain ZIF-L powder;

[0070] S4.3: Add 2 parts by weight of benzoxazine monomer to 60 parts by weight of N,N-dimethylformamide solution, stir to dissolve, then add 2 parts by weight of hydrochloric acid solution with a concentration of 2 mol / L, stir and mix for 10 min, then add 12 parts by weight of tetraethyl orthosilicate, continue to stir and mix for 20 min, and finally add 0.2 parts by weight of ZIF-L powder, ultrasonically disperse for 1 h to obtain a heat-insulating and insulating gel solution;

[0071] S4.4: Inject the heat-insulating and insulating gel solution into a polypropylene tank to seal the gel, the gel time is 7 h, then age for 48 min, and finally carry out solvent replacement and atmospheric drying to obtain a heat-insulating and insulating gel, which is the heat-insulating and insulating layer;

[0072] S5: Preparation of the conductive heating plate

[0073] S5.1: Form a composite film by electrospinning the graphene composite mixture. In electrospinning, the distance between the needle tip and the collecting device is 15 cm, the voltage is 15 kV, and the injection speed is 0.5 mm / min. Then heat the composite film at 280 °C for 2 h, and then keep it at 700 °C for 10 min in a nitrogen atmosphere to obtain a graphene composite heating layer;

[0074] S5.2: Use an etching machine to etch the designed circuit onto the conductor circuit layer, then print the cured electronic paste onto the circuit of the conductor circuit layer, cure at 180 °C for 10 min to form a conductive layer, stack the ceramic substrate, the heat-conducting and insulating layer, the graphene composite heating layer, the conductive layer and the heat-insulating and insulating layer in sequence from top to bottom and press them with a press to obtain a composite board. The pressing control temperature is 300 °C to obtain a conductive heating plate.

[0075] Example 2

[0076] A preparation process of a conductive heating plate for a hair straightener, as Figure 1 - Figure 2 shown, includes the following steps:

[0077] S1: Preparation of the graphene composite mixture

[0078] S1.1: Add 2 parts by weight of polyvinyl alcohol and 0.3 parts by weight of sodium carboxymethylcellulose to 80 parts by weight of deionized water, then add 0.2 parts by weight of sodium dodecylbenzenesulfonate, and stir and mix at 85 °C for 3 h to obtain a mixed solution;

[0079] S1.2: Add 2 parts by weight of onion carbon and 5 parts by weight of modified graphene oxide to 50 parts by weight of N,N-dimethylformamide, ultrasonically mix at room temperature for 40 min, then add 12 parts by weight of polyacrylonitrile, and stir and mix at 65 °C for 25 h to obtain a conductive dispersion;

[0080] S1.3: Add the conductive dispersion to the mixed solution, stir and mix at 75 °C for 8 h, then cool and let stand for 25 h to obtain a graphene composite mixed solution;

[0081] S2: Preparation of modified doped three-dimensional boron nitride

[0082] S2.1: Add 12 parts by weight of saturated sodium chloride to 20 parts by weight of alcohol, then perform vacuum filtration and drying to obtain micron-sized sodium chloride crystals. Mix 10 parts by weight of the micron-sized sodium chloride crystals with 2 parts by weight of boron trioxide and place them in an alumina crucible. Then place the alumina crucible in a tube furnace, introduce argon, and heat to 520 °C at a rate of 12 °C / min;

[0083] S2.2: After reaching 520 °C, turn off the argon, introduce ammonia gas, continue heating to 720 °C, hold for 30 min, heat again to 1200 °C, hold for 20 min. After cooling to room temperature, wash the obtained precipitate with deionized water, then perform vacuum filtration and drying, and dry at 65 °C for 12 h to obtain three-dimensional boron nitride;

[0084] S2.3: Add 3 parts by weight of three-dimensional boron nitride to 10 parts by weight of absolute ethanol, stir at 60 °C under ultrasonic conditions and 6000 r / min for 30 min, then add 0.2 parts by weight of a 20 wt% aqueous solution of silane coupling agent KH560, continue stirring for 50 min, then place in an oven and dry at 70 °C, grind and pulverize to obtain silane coupling agent-modified three-dimensional boron nitride;

[0085] S2.4: Place the silane coupling agent-modified three-dimensional boron nitride in a plasma reaction device, evacuate to -3000 kPa, then introduce ethylene and nitrogen to -2200 kPa, then evacuate again to -3000 kPa and introduce ethylene and nitrogen to -1500 kPa, and finally evacuate again to -3000 kPa. Perform plasma discharge at 30 kV voltage and 10 kHz frequency for 20 min to obtain modified doped three-dimensional boron nitride, and the weight ratio of ethylene to nitrogen is 1:25;

[0086] S3: Preparation of heat-conducting insulating layer

[0087] S3.1: Add 0.02 parts by weight of silane coupling agent KH550 to 100 parts by weight of ethanol, then add glacial acetic acid dropwise to adjust the pH value to 3. After hydrolysis for 30 min, add 2 parts by weight of nano-aluminum oxide, ultrasonically mix for 2 h, and stir at 80 °C in a water bath for 3 h. After filtration, wash with absolute ethanol three times and dry to obtain modified nano-aluminum oxide;

[0088] S3.2: Add 0.2 parts by weight of modified nano-aluminum oxide and 0.5 parts by weight of modified doped three-dimensional structure boron nitride to 20 parts by weight of N,N'-dimethylacetamide solution, ultrasonically stir and mix for 10 h. Under a nitrogen atmosphere, add 1 part by weight of 4,4'-diaminodiphenyl ether, stir and mix for 30 min, then add pyromellitic dianhydride in three portions under ice bath conditions, 0.3 parts by weight of pyromellitic dianhydride each time, stir and mix for 30 min to obtain a spinning solution. Electrospinning is carried out at a spinning voltage of 22 kV, a receiving distance of 22 cm, and a pushing speed of 0.9 mm / min to obtain a thermally conductive and insulating spun film;

[0089] S3.3: Dissolve 2 parts by weight of 4,4'-diaminodiphenyl ether in 50 parts by weight of N,N'-dimethylacetamide solution, then add 2 parts by weight of pyromellitic dianhydride and react for 5 h to obtain a reaction adhesive solution. Immerse the thermally conductive and insulating spun film in the reaction adhesive solution for 5 h, then carry out vacuum drying to obtain a thermally conductive and insulating film, which is the thermally conductive and insulating layer;

[0090] S4: Preparation of the heat-insulating and insulating layer

[0091] S4.1: Add 4 parts by weight of zinc nitrate hexahydrate and 16 parts by weight of 2-methylimidazole to 500 parts by weight of deionized water respectively, stir and mix to dissolve for 5 h to obtain a zinc nitrate hexahydrate solution and a 2-methylimidazole solution;

[0092] S4.2: Add the zinc nitrate hexahydrate solution to the 2-methylimidazole solution, continue to stir and mix for 5 h, then centrifuge at 9000 r / min, filter to obtain a precipitate, wash the precipitate with deionized water and then dry to obtain ZIF-L powder;

[0093] S4.3: Add 2 parts by weight of benzoxazine monomer to 60 parts by weight of N,N-dimethylformamide solution, stir to dissolve and then add 2 parts by weight of hydrochloric acid solution with a concentration of 2 mol / L, stir and mix for 12 min, then add 12 parts by weight of tetraethyl orthosilicate, continue to stir and mix for 30 min, and finally add 0.2 parts by weight of ZIF-L powder, ultrasonically disperse for 2 h to obtain a heat-insulating and insulating gel solution;

[0094] S4.4: Inject the heat-insulating and insulating gel solution into the polypropylene tank to seal the gel. The gel time is 8 h, then age for 50 min, and finally perform solvent replacement and atmospheric drying to obtain the heat-insulating and insulating gel, which is the heat-insulating and insulating layer.

[0095] S5: Preparation of the conductive heating plate

[0096] S5.1: Form a composite film by electrospinning the graphene composite mixture. In electrospinning, the distance between the needle tip and the collection device is 18 cm, the voltage is 16 kV, and the injection speed is 0.8 mm / min. Then heat the composite film at 300 °C for 3 h, and then keep it at 800 °C for 12 min in a nitrogen atmosphere to obtain the graphene composite heating layer.

[0097] S5.2: Etch the designed circuit onto the conductor circuit layer with an etching machine. Then print the cured electronic paste onto the circuit of the conductor circuit layer and cure it at 200 °C for 20 min to form the conductive layer. Stack the ceramic substrate, the thermal insulation layer, the graphene composite heating layer, the conductive layer, and the heat-insulating and insulating layer in sequence from top to bottom and press them with a press to obtain a composite board. The pressing temperature is controlled at 320 °C to obtain the conductive heating plate.

[0098] Example 3

[0099] A preparation process of a conductive heating plate for a hair straightener, as Figure 1 - Figure 2 shown, includes the following steps:

[0100] S1: Preparation of the graphene composite mixture

[0101] S1.1: Add 3 parts by weight of polyvinyl alcohol and 0.5 parts by weight of sodium carboxymethylcellulose to 100 parts by weight of deionized water, then add 0.3 parts by weight of sodium dodecylbenzenesulfonate, and stir and mix at 80 °C for 2 h to obtain a mixture.

[0102] S1.2: Add 3 parts by weight of onion carbon and 8 parts by weight of modified graphene oxide to 60 parts by weight of N,N-dimethylformamide, ultrasonically mix at room temperature for 30 min, then add 15 parts by weight of polyacrylonitrile, and stir and mix at 60 °C for 24 h to obtain a conductive dispersion.

[0103] S1.3: Add the conductive dispersion to the mixture, stir and mix at 70 °C for 6 h, then cool and let it stand for 24 h to obtain the graphene composite mixture.

[0104] S2: Preparation of the modified doped three-dimensional structure boron nitride

[0105] S2.1: Add 13 parts by weight of saturated sodium chloride to 22 parts by weight of alcohol, then perform vacuum filtration and drying to obtain micron-sized sodium chloride crystals. Mix 12 parts by weight of the micron-sized sodium chloride crystals with 3 parts by weight of boron trioxide and place them in an alumina crucible. Then place the alumina crucible in a tube furnace, introduce argon, and heat it to 500 °C at a rate of 10 °C / min.

[0106] S2.2: After reaching 500 °C, turn off the argon, introduce ammonia gas, continue heating to 700 °C, hold for 20 min, heat again to 1100 °C, hold for 10 min. After cooling to room temperature, wash the obtained precipitate with deionized water, then perform vacuum filtration and drying, and dry at 60 °C for 10 h to obtain three-dimensional boron nitride.

[0107] S2.3: Add 5 parts by weight of the three-dimensional boron nitride to 12 parts by weight of absolute ethanol, stir at 50 °C under ultrasonic conditions and 5000 r / min for 20 min, then add 0.3 parts by weight of a 30 wt% aqueous solution of silane coupling agent KH560, continue stirring for 40 min, then place it in an oven and dry at 60 °C, grind and crush to obtain silane coupling agent-modified three-dimensional boron nitride.

[0108] S2.4: Place the silane coupling agent-modified three-dimensional boron nitride in a plasma reaction device, evacuate to -2800 kPa, then introduce ethylene and nitrogen to -2000 kPa, then evacuate again to -2800 kPa and introduce ethylene and nitrogen to -1300 kPa, and finally evacuate again to -2800 kPa. Perform plasma discharge at a voltage of 28 kV and a frequency of 9 kHz for 15 min to obtain modified doped three-dimensional boron nitride. The weight ratio of ethylene to nitrogen is 2:25.

[0109] S3: Preparation of the thermal conductive insulating layer

[0110] S3.1: Add 0.05 parts by weight of silane coupling agent KH550 to 120 parts by weight of ethanol, then add glacial acetic acid dropwise to adjust the pH value to 4, hydrolyze for 20 min, then add 3 parts by weight of nano-aluminum trioxide, ultrasonically mix for 1 h, and stir in a 70 °C water bath for 2 h. After filtration, wash with absolute ethanol twice, and dry to obtain modified nano-aluminum trioxide.

[0111] S3.2: Add 0.3 parts by weight of modified nano-aluminum trioxide and 0.7 parts by weight of modified doped three-dimensional boron nitride into 30 parts by weight of N,N'-dimethylacetamide solution, ultrasonically stir and mix for 8 h. Under a nitrogen atmosphere, add 2 parts by weight of 4,4'-diaminodiphenyl ether, stir and mix for 20 min. Then, add pyromellitic dianhydride in three portions under ice bath conditions, 0.5 parts by weight of pyromellitic dianhydride each time, stir and mix for 20 min each time to obtain a spinning solution. Electrospinning is carried out at a spinning voltage of 20 kV, a receiving distance of 20 cm, and a pushing speed of 0.8 mm / min to obtain a thermally conductive and insulating spun film;

[0112] S3.3: Dissolve 3 parts by weight of 4,4'-diaminodiphenyl ether in 60 parts by weight of N,N'-dimethylacetamide solution, then add 3 parts by weight of pyromellitic dianhydride and react for 4 h to obtain a reaction adhesive solution. Immerse the thermally conductive and insulating spun film in the reaction adhesive solution for 4 h, and then carry out vacuum drying to obtain a thermally conductive and insulating film, which is the thermally conductive and insulating layer;

[0113] S4: Preparation of the heat-insulating and insulating layer

[0114] S4.1: Add 5 parts by weight of zinc nitrate hexahydrate and 18 parts by weight of 2-methylimidazole into 520 parts by weight of deionized water respectively, stir and mix to dissolve for 4 h to obtain a zinc nitrate hexahydrate solution and a 2-methylimidazole solution;

[0115] S4.2: Add the zinc nitrate hexahydrate solution into the 2-methylimidazole solution, continue to stir and mix for 4 h, then centrifuge at 8000 r / min, filter to obtain a precipitate, wash the precipitate with deionized water and then dry to obtain ZIF-L powder;

[0116] S4.3: Add 3 parts by weight of benzoxazine monomer into 70 parts by weight of N,N-dimethylformamide solution, stir to dissolve and then add 3 parts by weight of hydrochloric acid solution with a concentration of 2 mol / L, stir and mix for 10 min, then add 15 parts by weight of tetraethyl orthosilicate, continue to stir and mix for 20 min, and finally add 0.5 parts by weight of ZIF-L powder, ultrasonically disperse for 1 h to obtain a heat-insulating and insulating gel solution;

[0117] S4.4: Inject the heat-insulating and insulating gel solution into a polypropylene tank to seal the gel, the gel time is 7 h, then age for 48 min, and finally carry out solvent replacement and atmospheric drying to obtain a heat-insulating and insulating gel, which is the heat-insulating and insulating layer;

[0118] S5: Preparation of the conductive heating plate

[0119] S5.1: Form a composite film by electrospinning the graphene composite mixture. During electrospinning, the distance between the needle tip and the collection device is 15 cm, the voltage is 15 kV, and the injection speed is 0.5 mm / min. Then heat the composite film at 280 °C for 2 h, and then keep it at 700 °C for 10 min in a nitrogen atmosphere to obtain a graphene composite heating layer;

[0120] S5.2: Use an etching machine to etch the designed circuit onto the conductor circuit layer. Then print the cured electronic paste onto the circuit of the conductor circuit layer and cure it at 180 °C for 10 min to form a conductive layer. Stack the ceramic substrate, thermal insulation layer, graphene composite heating layer, conductive layer, and heat insulation layer in sequence from top to bottom and press them with a press to obtain a composite board. The pressing temperature is controlled at 300 °C to obtain a conductive heating board.

[0121] Comparative Example 1

[0122] Compared with Example 1, the difference in Comparative Example 1 is that in Comparative Example 1, the graphene composite heating layer is replaced with a pure graphene layer, and the conductive heating board is prepared with the remaining steps unchanged, denoted as Comparative Example 1.

[0123] Comparative Example 2

[0124] Compared with Example 1, the difference in Comparative Example 2 is that in Comparative Example 2, the onion carbon in step S1.2 is removed, and the conductive heating board is prepared with the remaining steps unchanged, denoted as Comparative Example 2.

[0125] Comparative Example 3

[0126] Compared with Example 1, the difference in Comparative Example 3 is that in Comparative Example 3, step S2.4 is removed, and the modified doped three-dimensional structure boron nitride in step S3.2 is replaced with silane coupling agent modified three-dimensional structure boron nitride, and the conductive heating board is prepared with the remaining steps unchanged, denoted as Comparative Example 3.

[0127] Comparative Example 4

[0128] Compared with Example 1, the difference in Comparative Example 4 is that in Comparative Example 4, the modified doped three-dimensional structure boron nitride in steps S2 and S3.2 is removed, and the conductive heating board is prepared with the remaining steps unchanged, denoted as Comparative Example 4.

[0129] Comparative Example 5

[0130] Compared with Example 1, the difference in Comparative Example 5 is that in Comparative Example 5, step S2 is removed, and the modified doped three-dimensional structure boron nitride in step S3.2 is replaced with conventional silane coupling agent KH560 modified nano boron nitride, and the conductive heating board is prepared with the remaining steps unchanged, denoted as Comparative Example 5.

[0131] Comparative Example 6

[0132] Compared with Example 1, the difference in Comparative Example 6 is that in Comparative Example 6, the modified nano-aluminum trioxide in step S3.1 and step S3.2 is removed, and the remaining steps remain unchanged to prepare the conductive heating plate, which is denoted as Comparative Example 6.

[0133] Comparative Example 7

[0134] Compared with Example 1, the difference in Comparative Example 7 is that in Comparative Example 7, the ZIF-L powder in steps S4.1 - S4.2 and step S4.3 is removed, and the remaining steps remain unchanged to prepare the conductive heating plate, which is denoted as Comparative Example 7.

[0135] The conductive heating plates prepared in Examples 1 - 3 and Comparative Examples 1 - 7 were assembled into hair straighteners to obtain hair straighteners.

[0136] The measuring end of the thermocouple was closely attached to the surface of the conductive heating plates of the hair straighteners in Examples 1 - 3 and Comparative Examples 1 - 6 to ensure good thermal contact. The wires of the thermocouple were connected to the temperature measuring instrument, and then the displayed temperature value could be read. After that, the hair straightener was plugged in and used. When the temperature value showed 200 °C, the time used was measured, and the average value was taken after measuring three times. The measurement results are shown in Table 1.

[0137] Table 1. Time used when heating Examples 1 - 3 and Comparative Examples 1 - 5 to 200 °C

[0138]

[0139] It can be seen from the data in Table 1 that the data of Comparative Example 1 and Comparative Example 2 are increased compared with those of the examples, indicating that the graphene and onion carbon-doped polyacrylonitrile carbonized fibers can accelerate the heating speed compared with the pure graphene heating layer, and there is no need for preheating to improve the user experience. It can be seen from the data of Comparative Examples 3 - 6 that the carbon-doped three-dimensional structure boron nitride interacts with the modified nano-aluminum trioxide, and the combination of the two greatly improves the thermal conductivity efficiency, thus effectively improving the thermal conductivity efficiency and achieving the effect of rapid temperature rise.

[0140] The hair straighteners assembled in Examples 1 - 3 were subjected to 10 frequent heating and cooling cycles, and then used again. The time used when heating to 200 °C was measured, and the measurement results are shown in Table 2.

[0141] Table 2. Time used when heating Examples 1 - 3 to 160 °C after 10 cycles

[0142]

[0143] It can be seen from the data in Table 2 that during the frequent heating and cooling cycles of the hair straightener, the performance of the conductive heating plate remains unchanged, and a good heating speed can be maintained.

[0144] Press the measuring end of the thermocouple tightly against the surface of the outer shell of the hair straighteners in Examples 1-3 and Comparative Example 7 to ensure good thermal contact. Connect the wires of the thermocouple to a temperature measuring instrument, and then the displayed temperature value can be read. After that, plug in the hair straightener and use it to measure the temperature of the outer shell of the hair straightener during use. Measure three times and take the average value. The measurement results are shown in Table 3.

[0145] Table 3. Outer shell temperature of Examples 1-3 and Comparative Example 7

[0146]

[0147] It can be seen from the data in Table 3 that adding ZIF-L powder can improve the heat insulation ability of the entire gel system.

[0148] Press the measuring end of the thermocouple tightly against the surface of the heat insulation and insulation layer of the conductive heating plate prepared in Examples 1-3 to ensure good thermal contact. Connect the wires of the thermocouple to a temperature measuring instrument, and then the displayed temperature value can be read. After that, heat the conductive heating plate to 350 °C and measure the temperature of the surface of the heat insulation and insulation layer. Measure three times and take the average value. The measurement results are shown in Table 4.

[0149] Table 4. Surface temperature of the heat insulation and insulation layer of Examples 1-3

[0150]

[0151] It can be seen from the data in Table 4 that the heat insulation and insulation layer can achieve a good heat insulation effect. The heat insulation and insulation layer can separate the conductive heating plate from the plastic material that fixes the heating plate, thus avoiding the problem that the temperature of the conductive heating plate is too high and easily burns out the plastic material that fixes the heating plate, resulting in the heating plate falling off.

[0152] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A process for preparing a conductive heating plate for a hair straightener, characterized in that: The steps include: S1: Preparation of graphene composite mixture Polyvinyl alcohol, sodium carboxymethyl cellulose and sodium dodecylbenzene sulfonate are used as a mixed liquid, and then a conductive dispersion prepared by onion carbon, modified graphene oxide and polyacrylonitrile is added, and the graphene composite mixed liquid is prepared after mixing; S2: Preparation of modified doped three-dimensional boron nitride S2.1: 12-13 parts by weight of saturated sodium chloride is added to 20-22 parts by weight of alcohol, and then vacuum filtered and dried to obtain micron sodium chloride crystals, 10-12 parts by weight of micron sodium chloride crystals and 2-3 parts by weight of boron trioxide are mixed and placed in an alumina crucible, and then the alumina crucible is placed in a tube furnace, argon gas is introduced, and heated to 500-520°C at 10-12°C / min; S2.2: After 500-520°C, turn off the argon gas, introduce ammonia, continue heating to 700-720°C, keep warm for 20-30 minutes, heat again to 1100-1200°C, keep warm for 10-20 minutes, cool to room temperature, wash the obtained precipitate with deionized water, then vacuum filter and dry, and dry at 60-65°C for 10-12 hours to obtain three-dimensional boron nitride; S2.3: Add 3-5 parts by weight of three-dimensional boron nitride to 10-12 parts by weight of anhydrous ethanol, stir for 20-30 minutes at 50-60°C under ultrasonic conditions and 5000-6000 r / min, then add 0.2-0.3 parts by weight of 20-30wt% silane coupling agent KH560 aqueous solution, continue stirring for 40-50 minutes, then place in an oven at 60-70°C to dry, grind and crush to obtain silane coupling agent modified three-dimensional boron nitride; S2.4: Place the silane coupling agent modified three-dimensional boron nitride in a plasma reaction device, evacuate to -2800 kPa to -3000 kPa, then introduce ethylene and nitrogen to -2000 kPa to -2200 kPa, then evacuate to -2800 kPa to -3000 kPa again, then introduce ethylene and nitrogen to -1300 kPa to -1500 kPa, and finally evacuate to -2800 kPa to -3000 kPa again, and perform plasma discharge at 28-30 kV voltage and 9-10 kHz frequency for 15-20 min to obtain modified doped three-dimensional boron nitride; S3: Preparation of thermally conductive insulating layer The modified nano-aluminum oxide and the modified doped three-dimensional structured boron nitride are used as thermal conductive fillers, and then 4,4'-diaminodiphenyl ether and pyromellitic anhydride are added to prepare a spinning solution for electrostatic spinning to obtain a thermal conductive insulating spinning membrane, which is then immersed in a reaction glue solution composed of 4,4'-diaminodiphenyl ether, N,N'-dimethylacetamide solution and pyromellitic anhydride, and finally vacuum dried to obtain a thermal conductive insulating film, i.e., a thermal conductive insulating layer; S4: Preparation of thermal insulation layer The thermal insulation gel is prepared by using benzophenone oxadiazine monomer, ZIF-L powder and tetraethyl orthosilicate as raw materials, namely the thermal insulation layer; S5: Preparation of conductive heating plate A graphene composite heating layer is prepared by using a graphene composite mixed liquid, and a ceramic substrate, a thermal conductive insulating layer, a graphene composite heating layer, a conductive layer and a thermal insulating layer are stacked in sequence from bottom to top and pressed with a pressing machine to obtain a conductive heating plate.

2. The process for preparing a conductive heating plate for a hair straightener according to claim 1, characterized in that: Step S1: Preparation of graphene composite mixed solution, specifically comprising the following steps: S1.1: Add 2-3 parts by weight of polyvinyl alcohol and 0.3-0.5 parts by weight of sodium carboxymethyl cellulose to 80-100 parts by weight of deionized water, and then add 0.2-0.3 parts by weight of sodium dodecylbenzene sulfonate, and stir and mix at 80-85° C. for 2-3 hours to obtain a mixed solution; S1.2: Add 2-3 parts by weight of onion carbon and 5-8 parts by weight of modified graphene oxide to 50-60 parts by weight of N,N-dimethylamide, mix them ultrasonically at room temperature for 30-40 minutes, then add 12-15 parts by weight of polyacrylonitrile, stir and mix at 60-65°C for 24-25 hours to obtain a conductive dispersion; S1.3: Add the conductive dispersion into the mixed solution, stir and mix at 70-75°C for 6-8h, then cool and let stand for 24-25h to obtain a graphene composite mixed solution.

3. The process for preparing a conductive heating plate for a hair straightener according to claim 1, characterized in that: In step S2.4, the weight ratio of ethylene to nitrogen is 1-2:

25.

4. The process for preparing a conductive heating plate for a hair straightener according to claim 1, characterized in that: Step S3: Preparation of the thermally conductive insulating layer, specifically comprising the following steps: S3.1: Add 0.02-0.05 parts by weight of silane coupling agent KH550 to 100-120 parts by weight of ethanol, then add glacial acetic acid to adjust the pH value to 3-4, hydrolyze for 20-30 minutes, add 2-3 parts by weight of nano-alumina, mix by ultrasonic for 1-2 hours, and stir in a water bath at 70-80°C for 2-3 hours, filter, wash with anhydrous ethanol 2-3 times, and dry to obtain modified nano-alumina; S3.2: Add 0.2-0.3 parts by weight of modified nano-aluminum trioxide and 0.5-0.7 parts by weight of modified doped three-dimensional structure boron nitride to 20-30 parts by weight of N, N'-dimethylacetamide solution, and mix under ultrasonic stirring for 8-10 hours. In a nitrogen atmosphere, add 1-2 parts by weight of 4,4'-diaminodiphenyl ether, and mix under stirring for 20-30 minutes. Then, add pyromellitic anhydride three times in an ice bath, adding 0.3-0.5 parts by weight of pyromellitic anhydride each time, and mix under stirring for 20-30 minutes to obtain a spinning solution. Perform electrostatic spinning at a spinning voltage of 20-22 kV, a receiving distance of 20-22 cm, and a push injection speed of 0.8-0.9 mm / min to obtain a thermally conductive insulating spinning membrane; S3.3: Dissolve 2-3 parts by weight of 4,4'-diaminodiphenyl ether in 50-60 parts by weight of N,N'-dimethylacetamide solution, then add 2-3 parts by weight of isophthalic anhydride, react for 4-5 hours to obtain a reaction colloid, immerse the thermally conductive insulating spinning membrane in the reaction colloid for 4-5 hours, and then vacuum dry it to obtain a thermally conductive insulating film, which is the thermally conductive insulating layer.

5. The process for preparing a conductive heating plate for a hair straightener according to claim 1, characterized in that: Step S4: Preparation of the heat-insulating layer, specifically comprising the following steps: S4.1: 4-5 parts by weight of zinc nitrate hexahydrate and 16-18 parts by weight of 2-methylimidazole are added to 500-520 parts by weight of deionized water respectively, and the mixture is stirred and dissolved for 4-5 hours to obtain a zinc nitrate hexahydrate solution and a 2-methylimidazole solution; S4.2: Add the zinc nitrate hexahydrate solution to the 2-methylimidazole solution, continue stirring and mixing for 4-5 hours, then centrifuge at 8000-9000 r / min, filter to obtain a precipitate, wash the precipitate with deionized water and dry to obtain ZIF-L powder; S4.3: Add 2-3 parts by weight of benzoxazine monomer to 60-70 parts by weight of N,N-dimethylformamide solution, stir to dissolve, then add 2-3 parts by weight of 2 mol / L hydrogen chloride solution, stir and mix for 10-12 minutes, then add 12-15 parts by weight of tetraethyl orthosilicate, continue to stir and mix for 20-30 minutes, finally add 0.2-0.5 parts by weight of ZIF-L powder, and ultrasonically disperse for 1-2 hours to obtain a thermal insulation gel solution; S4.4: Inject the thermal insulation gel solution into a polypropylene tank to seal the gel. The gel time is 7-8 hours, followed by aging for 48-50 minutes. Finally, solvent replacement and normal pressure drying are performed to obtain the thermal insulation gel, which is the thermal insulation layer.

6. The process for preparing a conductive heating plate for a hair straightener according to claim 1, characterized in that: Step S5: Preparation of the conductive heating plate, specifically comprising the following steps: S5.1: The graphene composite mixed solution is electrospinned to form a composite film, wherein the distance between the needle tip and the collecting device during electrospinning is 15-18 cm, the voltage is 15-16 kV, and the injection speed is 0.5-0.8 mm / min. The composite film is then heated at 280-300° C. for 2-3 h, and then kept at 700-800° C. for 10-12 min in a nitrogen atmosphere to obtain a graphene composite heating layer; S5.2: Use an etcher to etch the designed circuit onto the conductor circuit layer, then print the cured electronic paste onto the circuit of the conductor circuit layer, and form a conductive layer after curing at 180-200℃ for 10-20min. Stack the ceramic substrate, thermal conductive insulation layer, graphene composite heating layer, conductive layer and thermal insulation layer in sequence from top to bottom and press them with a press to obtain a composite board. The pressing temperature is controlled at 300-320℃ to obtain a conductive heating plate.

7. The process for preparing a conductive heating plate for a hair straightener according to claim 6, characterized in that: The ceramic substrate in step S5.2 is one of an aluminum oxide ceramic substrate and an aluminum nitride ceramic substrate.

8. The process for preparing a conductive heating plate for a hair straightener according to claim 6, characterized in that: In step S5.2, the conductor line layer is made of one of copper and aluminum materials.

9. A conductive heating plate for a hair straightener, characterized in that: The conductive heating plate is prepared by the preparation process of the conductive heating plate for a hair straightener as described in any one of claims 1 to 8.

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