WO2023060977A1

WO2023060977A1 - Porous carbon heating body and preparation method therefor, electrically heated atomization core, and electronic cigarette

Info

Publication number: WO2023060977A1
Application number: PCT/CN2022/107169
Authority: WO
Inventors: 于杰; 林梓家; 李振伟; 苑甫; 王恩哥
Original assignee: 松山湖材料实验室
Priority date: 2021-10-12
Filing date: 2022-07-21
Publication date: 2023-04-20
Also published as: CN113796588A

Abstract

A porous carbon heating body and a preparation method therefor, an electrically heated atomization core, and an electronic cigarette, which belong to the technical field of electronic cigarettes. A plurality of through holes are formed in the porous carbon heating body (130), a plurality of blind holes are formed in the wall of each through hole, and the hole diameter of the through hole is larger than that of the blind hole. The hole diameter of the through hole is on or below the micron scale, and the hole diameter of the blind hole is on the nanoscale. By means of the cooperation between the through holes having a hole diameter on or below a micron scale and the blind holes having a hole diameter on a nanoscale, the heating body is allowed to further have a certain liquid locking capability, such that e-liquid leakage is prevented, and dry burning caused by insufficient infiltration of an e-liquid is prevented. Moreover, the heating body is made of porous carbon, and the whole heating body emits heat in a homogeneous mode, such that the temperature uniformity is improved, and a local overheating phenomenon and material cracking caused by thermal shock are avoided; and the carbon material has a high infrared radiance (＞90%), high radiation heat penetrability and high electrothermal conversion efficiency (＞90%), is more energy-saving and efficient, and is beneficial to the miniaturization of equipment.

Description

Porous carbon heating element and preparation method thereof, electric heating atomizing core and electronic cigarette

Cross References to Related Applications

This application claims the priority of the Chinese patent application with the application number 202111186121.6 and the title "porous carbon heating element and its preparation method, electric heating atomizing core and electronic cigarette" submitted to the State Intellectual Property Office of China on October 12, 2021 , the entire contents of which are incorporated in this application by reference.

technical field

The present application relates to the technical field of electronic cigarettes, and in particular to a porous carbon heating element and a preparation method thereof, an electric heating atomizing core and an electronic cigarette.

Background technique

With the generalization of the global tobacco control trend, new tobacco products have gradually become an important development direction of the tobacco industry because of their advantages in reducing harmful components, and e-cigarettes have become one of the hot spots of new tobacco products in the world.

The core component of the electronic cigarette is the atomizing core. After more than ten years of development, the atomizing core has experienced three generations of technological evolution. The first-generation technology is glass fiber rope outsourcing heating wire, which has been eliminated due to the problems of easy generation of floc, easy powder loss, and uneven heating. The second-generation technology is the resistance wire cotton core, which has the advantages of large oil storage capacity, good oil conductivity, and dense smoke volume, but there are also obvious disadvantages, such as the cotton core is not resistant to high temperature, easy to dry burning, and the resistance wire heats the e-liquid. Uneven, easy to produce burnt smell, loose cotton core structure, poor liquid locking ability, easy to leak oil, and large atomized molecular particles. The third generation technology is a ceramic atomizing core, which has the advantages of small atomized particles, delicate taste, good consistency, and is not prone to oil leakage and burning.

At present, the ceramic atomizing core has a tendency to gradually replace the resistance wire cotton core, but there are still defects in the ceramic atomizing core. Its preparation method is usually to embed alloy heating wire, heating sheet, and metal mesh inside or on the surface of porous ceramics, or in The heating circuit is printed on the surface of the porous ceramic, and the alloy wire or metal printed circuit usually accounts for a small volume. The ceramic material itself as the main part of the atomizing core does not generate heat, but relies on the conduction heat of the resistance to heat the e-liquid, so there is an obvious temperature difference. Uniformity, when the pumping volume is large and the infiltration of e-liquid is insufficient, the metal wire will be overheated locally and produce burnt smell, while the ceramic substrate is low in temperature and the atomization effect is insufficient; and because the thermal expansion coefficients of metal and ceramics are inconsistent, in Cracking occurs under prolonged thermal shock.

Contents of the invention

Aiming at the deficiencies of related technologies, the embodiment of the present application provides a porous carbon heating element, an electric heating atomizing core and an electronic cigarette. Carbon materials are used as the heating element of the electric heating atomizing core in the electronic cigarette, and the heating effect is good.

Some embodiments of the present application provide a porous carbon heating element. The interior of the porous carbon heating element has a plurality of through holes, and the wall of each through hole may be provided with a plurality of blind holes, and the diameter of the through holes may be larger than that of the blind holes. aperture. The aperture of the through hole may not be larger than the micron scale, and the aperture of the blind hole may be of the nanometer scale.

In this application, the setting of multiple through-holes with a diameter not larger than the micron level can make the oil absorption effect of the heating element better, and the through-holes cooperate with the blind holes with a diameter of nanometer level, so that the heating element still has a certain lock. Liquid capacity, not only prevents oil leakage but also prevents dry burning due to insufficient infiltration of e-liquid. At the same time, the material of the heating element is porous carbon, and the overall homogeneous heat generation of the heating element improves the temperature uniformity and avoids the material cracking caused by local overheating and thermal shock; and the carbon material has a high infrared radiation rate (>90%), The penetration of radiant heat is high, the electrothermal conversion efficiency is high (>90%), and it is more energy-saving and efficient, which is beneficial to the miniaturization of equipment.

In some embodiments of the present application, the aperture of the through hole may be 200-1000nm, the aperture of the blind hole may be 10-100nm, the depth of the blind hole may be 10-100nm, and the porosity of the porous carbon heating element may be 60 %-90%. It can make the oil absorption ability of the porous carbon heating element stronger and the liquid locking ability better. Moreover, the porous carbon heating element has high porosity, large specific surface area, large oil absorption capacity, and small atomized particles, which ensures a delicate taste and a dense smoke volume.

In some embodiments of the present application, the through holes may include meandering through holes, and a plurality of meandering through holes may pass through. The zigzag through hole and the blind hole can form a zigzag porous structure and a multi-level pore structure with alternate distribution of large and small pores. This structure enhances the capillary force of the material for oil absorption, and improves the oil absorption speed and liquid locking ability.

Other embodiments of the present application provide a method for preparing a porous carbon heating element, which may include: forming a porous carbon matrix with a plurality of through holes inside. A plurality of blind holes are formed on the hole walls of the through holes.

Multiple through holes and blind holes can be formed, so that the heating element has better oil absorption and liquid locking capabilities, which not only prevents oil leakage, but also prevents dry burning due to insufficient infiltration of e-liquid. At the same time, the material of the heating element is porous carbon, and the overall homogeneous heat generation of the heating element improves the temperature uniformity and avoids the material cracking caused by local overheating and thermal shock; and the carbon material has a high infrared radiation rate (>90%), The penetration of radiant heat is high, the electrothermal conversion efficiency is high (>90%), and it is more energy-saving and efficient, which is beneficial to the miniaturization of equipment.

In some embodiments of the present application, the method of forming a porous carbon matrix with multiple through holes inside can be selected from: carbon fiber needle punching molding method, polymer pore-forming carbonization molding method, carbon fiber and polymer mixed pore-forming carbonization molding method Any one of the porous template vapor deposition molding methods.

In some embodiments of the present application, the method of forming a plurality of blind holes on the wall of the through hole may be a chemical vapor deposition method or a gas activation method. The chemical vapor deposition method is to prepare blind holes through the method of adding materials, and the gas activation method is to prepare blind holes through the method of subtracting materials. Both of them can prepare nano-scale blind holes to achieve a good oil locking effect, and to a certain extent avoid Occurrence of oil spills.

In some embodiments of the present application, the carbon fiber needle punching method may include: impregnating carbon fibers in a polymer solution, filtering and placing them in needle punching equipment for needle punching, or first carbon fibers are needle punched and then dipped in In the polymer solution, heat treatment is carried out after draining; wherein, the conditions of heat treatment are: inert gas protection, the temperature is 500-1500 ℃; wherein, the polymer is polyacrylonitrile, polyimide, polycarbonate, poly One or more of aryl acetylene, phenolic resin, epoxy resin, pitch.

In some embodiments of the present application, the polymer pore-forming carbonization molding method may include: drying and curing the solution containing the polymer and the pore-forming agent, and then performing heat treatment; wherein, the conditions of the heat treatment are: inert gas protection, temperature 500-1500°C, the mass ratio of polymer to pore-forming agent is (95:5)-(60:40); among them, the polymer is polyacrylonitrile, polyimide, polycarbonate, polyarylene , phenolic resin, epoxy resin, pitch, one or more; the pore-forming agent is one or more of ammonium bicarbonate, ammonium nitrate, starch, glucose, polyvinylpyrrolidone, polyvinyl butyral.

In some embodiments of the present application, the pore-forming carbonization molding method of mixing carbon fibers and polymers may include: dispersing carbon fibers, polymers, and pore-forming agents in the same solution, and performing heat treatment after molding; wherein, the conditions of heat treatment are : Inert gas protection, the temperature is 500-1500 ° C, the mass ratio of carbon fiber, polymer and pore-forming agent is (80-40): (80-40): (20-5); wherein, the polymer is polypropylene One or more of nitrile, polyimide, polycarbonate, polyarylene, phenolic resin, epoxy resin, asphalt; pore forming agent is ammonium bicarbonate, ammonium nitrate, starch, glucose, polyvinylpyrrolidone , one or more of polyvinyl butyral.

In some embodiments of the present application, the porous template vapor deposition molding method may include: using a porous metal as a template, using hydrocarbon gas as a carbon source, performing vapor deposition, and then removing the porous metal template by acid washing; wherein, the vapor deposited The temperature is 800-1500°C, and the time is 1-8h.

In some embodiments of the present application, the chemical vapor deposition method may include: placing the porous carbon substrate in a heating furnace, feeding an inert gas as a protective gas, raising the temperature to 1000-1500°C, feeding hydrogen and methane, and performing treatment1 -8h, making graphene nanosheets grow on the hole walls of the porous carbon matrix, and the graphene nanosheets overlap to form blind holes.

Graphene nanosheets are evenly grown on the surface of the hole wall of the porous carbon matrix by the above chemical vapor deposition method, and the graphene nanosheets are overlapped with each other to form a blind hole structure for oil locking.

In some embodiments of the present application, the gas activation method may include: placing the porous carbon substrate in a heating furnace, passing an inert gas as a protective gas, raising the temperature to 1000-1500°C, passing water vapor and/or carbon dioxide, and performing treatment 1-3h, so that blind holes are formed on the pore walls of the porous carbon matrix.

Through the above gas activation method, the carbon on the pore wall surface of the porous carbon matrix can be converted into gas by reacting with water vapor or carbon dioxide, thereby forming blind pores on the surface of the porous carbon matrix.

Some other embodiments of the present application provide an electrically heated atomizing core. The electrically heated atomizing core may include two electrodes and the above-mentioned porous carbon heating element, and the two electrodes may be respectively fixed at both ends of the porous carbon heating element.

The above-mentioned porous carbon heating element is used in the electric heating atomizing core, and through the cooperation of through holes and blind holes of different apertures, the oil absorption effect of the heating element can be improved, and the through hole is matched with the blind hole with a diameter of nanometers, which can The heating element has a certain ability to lock liquid, which not only prevents oil leakage but also prevents dry burning due to insufficient infiltration of e-liquid. At the same time, the porous carbon homogeneous heating atomizing core is the overall homogeneous heating. The entire atomizing core can be used as the oil absorption part and the atomization part. The temperature uniformity is high, and there is no local overheating phenomenon. The material can realize synchronous heating while absorbing oil. Atomization, fast atomization speed, large amount of smoke and controllable suction. At the same time, the porous carbon homogeneous heating atomizing core has good stability, good thermal shock resistance, and is not prone to cracking and other failure behaviors.

In some embodiments of the present application, the electrode and the porous carbon heating element may be fixed by means of welding, riveting, conductive paste layer, elastic clamping or pressure clamping. The fixing effect between the electrode and the porous carbon heating element can be improved.

In some embodiments of the present application, the electrodes may be one of graphite electrodes, nickel electrodes, copper electrodes, iron electrodes, aluminum electrodes, silver electrodes and gold electrodes.

In some embodiments of the present application, the electrodes may be porous metal electrodes. The electrode will not block the oil absorption of the porous carbon heating element at the electrode connection, and the atomized smoke particles can escape from the electrode connection, which not only increases the liquid absorption and guiding part of the porous carbon heating element, but also increases the atomization surface, improving overall material utilization.

In some embodiments of the present application, the electrode may be one of porous nickel, porous copper, porous iron, porous aluminum, and porous silver.

In some embodiments of the present application, the porous carbon heating element may be one of cuboid, polygonal prism, and prism.

In some embodiments of the present application, at least one surface of the porous carbon heating element may be an oil-absorbing surface. By penetrating the surface of the porous carbon heating element, the liquid absorption effect of the electric heating atomizing core can be improved.

In some embodiments of the present application, the porous carbon heating element may include a heating atomizing part and a liquid absorbing and guiding part connected to each other, and an electrode is fixed at the junction of the heating atomizing part and the liquid absorbing and guiding part. Both the liquid absorbing part and the atomizing part are made of porous carbon material, which can make the oil absorbing and guiding effect of the atomizing core better, and can atomize well.

In some embodiments of the present application, the length of the outer contour of the porous carbon heating element can be 3-15 mm, the width can be 1-5 mm, and the height can be 0.5-2 mm; the distance between the two electrodes can be 3-15 mm. 15mm. It can make the atomizing core heat evenly and avoid excessive or small resistance.

In some embodiments of the present application, the electrically heated atomizing core may further include two conducting conductors, and one conducting conductor may be connected to one electrode. It is convenient to connect the atomizing core to an external power supply.

In some embodiments of the present application, the electric conductor may be one of metals such as silver, copper, iron, aluminum, nickel, and zinc.

In some embodiments of the present application, the conductive conductor and the electrode may be connected by welding, riveting or pressure connection.

Some further embodiments of the present application provide an electronic cigarette, which may include the above-mentioned electrically heated atomizing core.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, so It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is a schematic structural diagram of an electrically heated atomizing core provided in an embodiment of the present application;

Fig. 2 is a partial cross-sectional view of the electrically heated atomizing core provided by the embodiment of the present application;

Fig. 3 is the 10K times scanning electron microscope photomicrograph of the porous carbon heating element provided by the embodiment of the present application;

Fig. 4 is a 40K magnification scanning electron micrograph of the porous carbon heating element provided in the embodiment of the present application.

Icons: 110-electrode; 120-electric conductor; 130-porous carbon heating element; 131-liquid suction and guiding part; 132-heating atomization part.

Detailed ways

In the related technology, the ceramic in the ceramic atomizing core does not generate heat itself, but the metal resistance in the ceramic atomizing core heats up to heat the e-liquid, so there is obvious temperature inhomogeneity. When the oil infiltration is insufficient, there will be local overheating of the metal wire and a burnt smell, while the temperature of the ceramic substrate is low and the atomization effect is insufficient. And because the thermal expansion coefficients of metal and ceramics are inconsistent, cracking will occur under long-term thermal shock.

The embodiment of the present application provides a new electric heating atomizing core, which uses a new heating element and can improve some problems of the ceramic atomizing core. In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the present application are described clearly and completely below.

Fig. 1 is a schematic structural diagram of an electrically heated atomizing core provided in an embodiment of the present application; Fig. 2 is a partial cross-sectional view of an electrically heated atomizing core provided in an embodiment of the present application. Please refer to FIG. 1 and FIG. 2 , the electric heating atomizing core may include two electrodes 110 and a porous carbon heating element 130 , and the two electrodes 110 may be respectively fixed at both ends of the porous carbon heating element 130 . Wherein, the interior of the porous carbon heating element 130 may have a plurality of through holes, and the wall of each through hole may be provided with a plurality of blind holes, and the diameter of the through holes may be larger than that of the blind holes. The aperture of the through hole may not be larger than the micron scale, and the aperture of the blind hole may be of the nanometer scale.

The arrangement of a plurality of through-holes with a diameter not larger than the micron level can make the oil absorption effect of the heating element better, and the combination of the through-hole and the blind hole with a diameter of nanometer can make the heating element have a certain liquid-locking ability, both Prevent oil leakage and prevent dry burning due to insufficient infiltration of e-liquid. At the same time, the material of the heating element is porous carbon, and the overall homogeneous heat generation of the heating element improves the temperature uniformity and avoids the material cracking caused by local overheating and thermal shock; and the carbon material has a high infrared radiation rate (>90%), The penetration of radiant heat is high, the electrothermal conversion efficiency is high (>90%), and it is more energy-saving and efficient, which is beneficial to the miniaturization of equipment.

In order to make the porous carbon heating element 130 have better oil absorption and oil conduction effects, better lock oil and avoid oil leakage. The diameter of the through hole may be 200-1000 nm, the diameter of the blind hole may be 10-100 nm, and the depth of the blind hole may be 10-100 nm.

It should be noted that the number of through holes can be multiple, and the apertures of multiple through holes need not be limited to be the same. The apertures of the through holes can be the same or different. Different positions of the same through hole may have different hole diameters, which is not limited in this application.

The number of blind holes can be multiple, and the apertures of multiple blind holes do not need to be limited to be consistent. The apertures of blind holes can be the same or different, and the apertures of blind holes can all reach the nanometer level; the depth of multiple blind holes It does not need to be limited to be consistent, the depths of the blind holes may be the same or different, and the depths of the blind holes may all reach the nanometer level.

Optionally, the through holes may include meandering through holes, and a plurality of meandering through holes may pass through. The zigzag through hole and the blind hole can form a zigzag porous structure and a multi-level pore structure with alternate distribution of large and small pores. This structure enhances the capillary force of the material for oil absorption, and improves the oil absorption speed and liquid locking ability.

Wherein, all through holes may be zigzag through holes, or some through holes may be zigzagging through holes; all through holes may be connected to each other, or some through holes may be connected to each other, which is not limited in this application.

Optionally, the porosity of the porous carbon heating element 130 may be 60%-90%. The porous carbon heating element 130 has a high porosity, a large specific surface area, a large oil absorption capacity, and small atomized particles, which ensures a delicate taste and a dense smoke volume.

In this application, the porous carbon heating element 130 may be one of cuboid, polygonal prism, and prism. The heating element can also be in other shapes. After the porous carbon heating element 130 cooperates with the two electrodes 110, the obtained electrically heated atomizing core can also be one of cuboid, polygonal prism, and prism.

Optionally, the length of the outer contour of the porous carbon heating element may be 3-15 mm, the width may be 1-5 mm, and the height may be 0.5-2 mm; the distance between the two electrodes may be 3-15 mm. It can make the atomizing core heat evenly and avoid excessive or small resistance. It should be noted that although the length, width, and height are recorded here, it does not limit the porous carbon heating element to a cuboid structure, but only roughly describes its external dimensions.

Please continue to refer to FIG. 1 and FIG. 2 , the electrode 110 can be a block structure, and the two electrodes 110 can be respectively arranged at both ends of the porous carbon heating element 130 , and are basically in contact with the porous carbon heating element 130 . The electrode 110 may be a porous metal electrode 110 . The electrode 110 will not block the oil absorption of the porous carbon heating element 130 at the connection of the electrode 110, and the atomized smoke particles can escape from the connection of the electrode 110, which not only increases the oil absorption surface of the porous carbon heating element 130 but also increases the atomization surface , improve the overall material utilization.

In the present application, the electrodes may be one of graphite electrodes, nickel electrodes, copper electrodes, iron electrodes, aluminum electrodes, silver electrodes and gold electrodes. Optionally, the electrode may be a porous metal electrode 110, and the porous metal electrode may be one of porous nickel, porous copper, porous iron, porous aluminum, and porous silver.

In this application, in order to improve the fixing effect between the electrode 110 and the porous carbon heating element 130 , the electrode 110 and the porous carbon heating element 130 can be fixed through an electroconductive paste layer. In other embodiments, the two ends of the porous carbon heating element 130 may also be fixed by means of welding, riveting, elastic clamping or pressure clamping.

In the present application, an electrifying conductor 120 (for example, an electrifying wire) may also be connected to the electrode 110 so as to be electrified with an external power source. Optionally, the current conducting conductor 120 may be one of metals such as silver, copper, iron, aluminum, nickel, and zinc. The current conducting conductor 120 can be fixed on the electrode 110 by welding. In other embodiments, the electrodes 110 and the current conductors 120 may also be connected by riveting or pressure connection.

The porous carbon heating element 130 provided by the present application may include a liquid-absorbing liquid-guiding part 131 and a heating atomizing part 132 connected to each other. Homogeneous heating, the entire atomizing core can be used as the oil absorption part and the atomization part, the temperature uniformity is high, there is no local overheating phenomenon, the material absorbs oil and can realize synchronous heating and atomization at the same time, the atomization speed is fast, the amount of smoke is large and The suction is controllable. At the same time, the porous carbon homogeneous heating atomizing core has good stability, good thermal shock resistance, and is not prone to cracking and other failure behaviors.

Optionally, at least one surface of the porous carbon heating element 130 may be an oil-absorbing surface, and by penetrating through the surface of the porous carbon heating element, the liquid-absorbing effect of the electrically heated atomizing core can be improved.

In other embodiments, the heating and atomizing part 132 may also be a porous carbon heating element, the liquid absorption and guiding part 131 may be a porous ceramic material, and the porous ceramic and porous carbon may be connected by bonding or embedding.

The above-mentioned electric heating atomizing core can be used to prepare electronic cigarettes, and the heating method of the electric heating atomizing core can be carbon material infrared radiation heating, which has high penetration of infrared radiation, high efficiency and uniformity of heating e-liquid, and is more energy-saving , high efficiency, and conducive to the miniaturization of atomization equipment.

After introducing the electric heating atomizing core, the preparation method of the electric heating atomizing core is introduced below, and the preparation method may include:

S110, preparing a porous carbon heating element 130.

S111, forming a porous carbon matrix having a plurality of through holes inside. The forming method can be any one of: carbon fiber needle punching molding method, polymer pore-forming carbonization molding method, carbon fiber and polymer mixed pore-forming carbonization molding method and porous template vapor deposition molding method.

Optionally, the carbon fiber needle punching method may include: immersing the carbon fiber in a polymer solution, filtering it and then placing it in a needle punching device for needle punching, or first performing needle punching on the carbon fiber and then immersing it in the polymer solution, After draining, heat treatment is carried out; wherein, the conditions of heat treatment are: inert gas protection, and the temperature is 500-1500°C.

Wherein, the carbon fiber can be one or both of chopped carbon fiber and continuous carbon fiber. The polymer can be one or more of polyacrylonitrile, polyimide, polycarbonate, polyarylene, phenolic resin, epoxy resin, and asphalt.

For example: immerse carbon fibers in polyvinyl alcohol aqueous solution, stir and disperse evenly, filter and place in acupuncture equipment for acupuncture treatment to obtain carbon fiber block solids (or place carbon fibers in acupuncture equipment for acupuncture treatment) treatment, and then soaked in polyvinyl alcohol aqueous solution, drained to obtain carbon fiber block solid), placed in an oven to dry, after removing the solvent, the resulting solid was placed in a heating furnace, nitrogen gas was introduced as a protective gas, and the temperature was raised to 1200- Heat treatment is carried out at 1400° C., and the holding time is 60-120 minutes to obtain a porous carbon matrix with a zigzag through-hole structure.

Optionally, the polymer pore-forming carbonization molding method may include: drying and curing the solution with the polymer and the pore-forming agent and then heat treatment; wherein, the conditions of the heat treatment are: inert gas protection, the temperature is 500-1500°C , the mass ratio of polymer to pore-forming agent is (95:5)-(60:40).

Wherein, the polymer in the polymer pore-forming carbonization molding method can be one or more of polyacrylonitrile, polyimide, polycarbonate, polyaryleacetylene, phenolic resin, epoxy resin, and asphalt; The pore agent can be one or more of ammonium bicarbonate, ammonium nitrate, starch, glucose, polyvinylpyrrolidone, and polyvinyl butyral.

For example: dissolve the polymer in a solvent, add a pore-forming agent for mixing, and mix uniformly to obtain a mixed solution (disperse the polymer and the pore-forming agent in the same solution at the same time to obtain a mixed solution), and place the mixed solution in the mold , and then put it into an oven, process it at a temperature of 300-400°C, and keep it for more than 30 minutes (for example: 60-120 minutes). During the heat preservation process, the solvent in the mold volatilizes, the pore-forming agent decomposes, and forms A polymeric solid with a porous structure. Put the polymer solid in a heating furnace, feed nitrogen gas as a protective gas, heat up to 1200-1400°C for carbonization, and hold the temperature for 60-120min to obtain a porous carbon matrix.

Optionally, the carbon fiber and polymer mixed pore-forming carbonization molding method may include: dispersing carbon fiber, polymer, and pore-forming agent in the same solution, and performing heat treatment after molding; wherein, the conditions of heat treatment are: inert gas protection, The temperature is 500-1500° C., and the mass ratio of carbon fiber, polymer and pore former is (80-40):(80-40):(20-5).

Wherein, the carbon fiber in the carbon fiber and polymer mixed pore-forming carbonization molding method can be one or both of chopped carbon fiber and continuous carbon fiber. The polymer can be one or more of polyacrylonitrile, polyimide, polycarbonate, polyarylene, phenolic resin, epoxy resin, asphalt; the pore-forming agent can be ammonium bicarbonate, ammonium nitrate, One or more of starch, glucose, polyvinylpyrrolidone, and polyvinyl butyral.

For example, disperse carbon fibers in a solvent, add polymer powder, stir and dissolve at 80-100°C to obtain a mixed solution A, then take a pore-forming agent and dissolve it in a solvent, stir and dissolve at room temperature to obtain a solution B, Mix A and B liquids and stir them evenly, then pour them into a cuboid mold, place them in an oven to dry, remove the solvent, put the obtained solids in a heating furnace, pass in nitrogen gas as a protective gas, and heat up to 1200-1400°C for heat treatment , the holding time is 60-120min, and a porous carbon matrix with a tortuous through-pore structure is obtained.

Optionally, the porous template vapor deposition molding method may include: using porous metal as a template, hydrocarbon gas as a carbon source, performing vapor deposition, and then removing the porous metal template by pickling; wherein, the temperature of vapor deposition is 800-1500 ℃, the time is 1-8h. The porous metal can be porous nickel or porous copper, and the hydrocarbon gas can be methane or acetylene.

For example: use nickel foam as a template, place nickel foam in a chemical vapor deposition furnace, heat up to 1000-1200°C, pass through acetylene for carbon deposition, cool down after 60-120min, cool to room temperature and soak the resulting solid in hydrochloric acid , removing the foamed nickel template to obtain a porous carbon matrix with a tortuous through-pore structure.

S112, forming a plurality of blind holes on the wall of the through hole. Its formation method can be: chemical vapor deposition method or gas activation method. The chemical vapor deposition method is to prepare blind holes through the method of adding materials, and the gas activation method is to prepare blind holes through the method of subtracting materials. Both of them can prepare nano-scale blind holes to achieve a good oil locking effect, and to a certain extent avoid Occurrence of oil spills.

In one embodiment, the chemical vapor deposition method may include: placing the porous carbon substrate in a heating furnace, feeding an inert gas (for example: argon) as a protective gas, raising the temperature to 1000-1500°C, feeding hydrogen and methane, The treatment is carried out for 1-8 hours, so that graphene nanosheets grow on the hole walls of the porous carbon matrix, and the graphene nanosheets are overlapped to form blind holes. Graphene nanosheets are uniformly grown on the surface of the hole wall of the porous carbon matrix, and the graphene nanosheets are overlapped with each other to form a blind hole structure for oil locking.

In another embodiment, the gas activation method may include: placing the porous carbon substrate in a heating furnace, passing an inert gas (for example: argon) as a protective gas, raising the temperature to 1000-1500 ° C, passing water vapor and/or Carbon dioxide, treated for 1-3 hours, can make the carbon on the surface of the hole wall of the porous carbon matrix react with water vapor or carbon dioxide and convert it into gas, thereby forming blind pores on the surface of the porous carbon matrix.

S120, preparing an electrically heated atomizing core.

S121 , fixing the electrode 110 on the porous carbon heating element 130 . Optionally, the porous metal electrode 110 can be respectively fixed on both sides of the porous carbon heating element 130 by means of conductive paste, and the conductive paste is coated on both ends of the porous carbon heating element 130, and then the electrode 110 is fixed on it. Wherein, the conductive paste can be high temperature resistant conductive silver paste, such as one of sintered silver paste, gold paste, platinum paste, and graphene paste.

The two sides of the porous carbon heating element 130 can be metallized so as to be connected to the wires. At the same time, the porous metal electrode 110 is used to increase the liquid-absorbing and liquid-conducting part 131 and the atomizing surface of the porous carbon heating element 130, which improves the overall material performance. utilization rate.

S122 , fixing the conducting conductor 120 on the electrode 110 . The current conducting conductor 120 can be fixed on the porous metal electrode 110 by welding. Wherein, the welding solder can be selected from high temperature resistant solder, such as one of silver brazing solder and zinc-aluminum-silver-copper alloy solder. The purpose of this step is to extend the metal electrode 110 so as to be connected to the positive and negative poles of the battery to realize battery power supply.

The effect of the electric heating atomizing core provided by this application can be at least as follows:

(1), the setting of a plurality of through-holes with apertures not greater than micron order can make the oil absorption effect of the porous carbon heating element 130 better, and the through-holes cooperate with blind holes with an aperture of nanometer order to make the porous carbon heating element The 130 also has a certain ability to lock liquid, which not only prevents oil leakage but also prevents dry burning due to insufficient infiltration of e-liquid.

(2) Tortuous porous structure and multi-level pore structure (larger through holes and smaller blind holes) with alternating distribution of large and small holes, this structure enhances the capillary force of the material for oil absorption, improves the oil absorption speed and liquid locking ability .

(3), the porous metal electrode 110 is connected with the porous carbon heating element 130, and the oil absorption of the porous carbon heating element 130 will not be blocked at the connection of the electrode 110, and the smoke particles after atomization can escape from the connection of the electrode 110, which increases the The oil-absorbing surface of the porous carbon heating element 130 increases the atomization surface, which improves the utilization rate of the overall material.

(4) The porous carbon heating body is homogeneously heated as a whole, and the entire heating body can be used as the oil absorption part and the atomization part, with high temperature uniformity and no local overheating phenomenon. The material can realize synchronous heating and atomization while absorbing oil. The atomization speed is fast, the amount of smoke is large, and the suction is controllable. At the same time, the porous carbon heating element 130 has good stability, good thermal shock resistance, and is not prone to cracking and other failure behaviors.

(5), the material of the heating body is porous carbon, the overall homogeneous heating of the heating body improves the temperature uniformity, avoids the material cracking caused by local overheating and thermal shock; and the carbon material has a high infrared radiation rate (> 90% ), high penetration of radiant heat, high electrothermal conversion efficiency (>90%), high efficiency and uniformity of heating e-liquid, more energy saving and high efficiency, and is conducive to the miniaturization of atomization equipment.

In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased from the market.

An embodiment of the present application provides a preparation method of an electrically heated atomizing core, the preparation method may include the following steps:

(1) Disperse chopped carbon fibers with a length of about 5cm and a diameter of about 5um in dimethylformamide solvent, add polyacrylonitrile powder, stir and dissolve at 80°C to obtain a mixed solution A, and then dissolve starch in In dimethyl sulfoxide solvent, stir and dissolve at room temperature to obtain solution B, wherein the mass ratio of carbon fiber, polyacrylonitrile, and starch is 50:30:20, mix A and B liquids and stir them evenly, then pour them into a cuboid Place the solid in a mold and dry it in an oven. After removing the solvent, put the obtained solid in a heating furnace, and pass nitrogen gas as a protective gas, heat up to 1200°C for heat treatment, and hold for 60 minutes to obtain a porous carbon matrix with a tortuous through-pore structure. .

(2) Continue to feed hydrogen and methane into the heating furnace for chemical vapor deposition, wherein the flow ratio of hydrogen and methane is 10:1, and the holding time is 6 hours, so that the surface of the porous carbon substrate is evenly distributed with vertical graphene nanometers Sheets, graphene nanosheets are overlapped to form a tiny blind hole structure, and a porous carbon heating element is obtained.

(3), cutting the porous carbon heating element into a cuboid of 8mm × 6mm × 5mm, using sintered conductive silver paste to adhere two porous nickel electrode sheets with a size of 6mm × 5mm on the two faces of the porous carbon heating element, Sintering is carried out at 500°C; finally, the electric conductor is welded on the porous nickel electrode with silver brazing material to obtain an electric heating atomizing core.

Fig. 3 is a 10K times scanning electron microscope photo of the porous carbon heating element provided in the example of the present application; Fig. 4 is a 40K times scanning electron microscope photo of the porous carbon heating element provided in the example of the present application. It can be seen from Figure 3 and Figure 4 that vertical graphene nanosheets are evenly distributed on the surface of the porous carbon matrix, and the graphene nanosheets overlap each other to form a tiny blind hole structure. The size of the blind holes on the carbon fiber surface is about 50nm.

According to the nitrogen isotherm adsorption-desorption curve test, the specific surface area of the porous carbon heating element provided in this embodiment is 226 m ² /g, and the porosity is 87%.

Another embodiment of the present application will be described below, which is an improvement on the basis of the above-mentioned one embodiment. The difference between this other embodiment and the above-mentioned one embodiment is that: in step (1), the Chopped carbon fibers with a length of about 5cm and a diameter of about 5um are impregnated in a polyvinyl alcohol aqueous solution, stirred and dispersed evenly, filtered and placed in acupuncture equipment for acupuncture treatment to obtain carbon fiber block solids, which are dried in an oven and removed. After solvent, the obtained solid was placed in a heating furnace, nitrogen gas was introduced as a protective gas, the temperature was raised to 1200°C for heat treatment, and the holding time was 60 minutes to obtain a porous carbon matrix with a zigzag through-pore structure.

According to the nitrogen isotherm adsorption-desorption curve test, the specific surface area of the porous carbon heating element provided in this embodiment is 180 m ² /g, and the porosity is 90%.

Another embodiment of the present application will be described below, which is an improvement on the basis of the above-mentioned one embodiment. The difference between this another embodiment and the above-mentioned one embodiment is that: in step (1), the Dissolve polyamic acid in dimethylacetamide solvent, stir until the solution is clear, then add ammonium bicarbonate and mix evenly at high speed, pour the resulting mixed solution into a cuboid mold, place it in an oven, and carry out imidization reaction at 350°C. Insulated for 60 minutes, the reaction process is accompanied by solvent volatilization and ammonium bicarbonate decomposition, and a porous polyimide solid is obtained, wherein the mass ratio of polyamic acid to ammonium bicarbonate is 90:10; continue to place the polyimide solid in In the heating furnace, nitrogen gas was introduced as a protective gas, and the temperature was raised to 1200°C for carbonization, and the holding time was 60 minutes to obtain a porous carbon matrix.

According to the nitrogen isotherm adsorption-desorption curve test, the specific surface area of the porous carbon heating element provided in this embodiment is 215 m ² /g, and the porosity is 78%.

Another embodiment of the present application will be described below, which is an improvement made on the basis of the above-mentioned one embodiment. The difference between this yet another embodiment and the above-mentioned one embodiment is that in step (1), Foamed nickel is used as a template, put the foamed nickel in a chemical vapor deposition furnace, heat up to 1000°C, pass through acetylene for carbon deposition, cool down after 60 minutes, soak the obtained solid in hydrochloric acid after cooling to room temperature, remove the foamed nickel template, and obtain Porous carbon matrix with tortuous through-pore structure.

According to the nitrogen isotherm adsorption-desorption curve test, the specific surface area of the porous carbon heating element provided in this embodiment is 160 m ² /g, and the porosity is 70%.

Another embodiment of the present application will be described below. This yet another embodiment is an improvement on the basis of the above-mentioned one embodiment. The difference between this yet another embodiment and the above-mentioned one embodiment is: step (2) , continue to feed water vapor and carbon dioxide gas into the heating furnace, and perform gas activation for 2 hours, which can make the carbon on the surface of the hole wall of the porous carbon matrix react with water vapor or carbon dioxide and convert it into gas, thereby forming blind pores on the surface of the porous carbon matrix , to obtain a porous carbon heating element.

According to the nitrogen isotherm adsorption-desorption curve test, the specific surface area of the porous carbon heating element provided in this embodiment is 198 m ² /g, and the porosity is 75%.

A preparation method of an electrically heated atomizing core according to a comparative example will be described below, and the preparation method of this comparative example may include the following steps:

(2), cutting the porous carbon substrate into a cuboid of 8 mm × 6 mm × 5 mm, using sintered conductive silver paste to adhere two porous nickel electrode sheets with a size of 6 mm × 5 mm on the two faces of the porous carbon heating element, Sintering is carried out at 500°C; finally, the electric conductor is welded on the porous nickel electrode with silver brazing material to obtain an electric heating atomizing core.

According to the nitrogen isotherm adsorption-desorption curve test, the specific surface area of the porous carbon heating element provided in the comparative example is 50 m ² /g, and the porosity is 63%.

The embodiments described above are some of the embodiments of the present application, but not all of them. The detailed description of the embodiments of the application is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

Industrial Applicability

The application discloses a porous carbon heating element and a preparation method thereof, an electric heating atomizing core and an electronic cigarette. The interior of the porous carbon heating element has a plurality of through holes, and the hole wall of each through hole is provided with a plurality of blind holes, and the diameter of the through holes is larger than that of the blind holes. The pore diameter of the through hole is not larger than the micrometer level, and the pore diameter of the blind hole is nanometer level. Through the cooperation of through-holes with apertures not larger than micron-scale and blind holes with apertures of nano-scale, the heating element can still have a certain liquid-locking ability, which not only prevents oil leakage, but also prevents dry burning due to insufficient infiltration of e-liquid. At the same time, the material of the heating element is porous carbon, and the overall homogeneous heat generation of the heating element improves the temperature uniformity and avoids the material cracking caused by local overheating and thermal shock; and the carbon material has a high infrared radiation rate (>90%), The penetration of radiant heat is high, the electrothermal conversion efficiency is high (>90%), and it is more energy-saving and efficient, which is beneficial to the miniaturization of equipment.

In addition, it can be understood that the porous carbon heating element and its preparation method, the electric heating atomizing core and the electronic cigarette of the present application are reproducible and can be applied in various industrial applications. For example, the porous carbon heating element of the present application and its preparation method can be applied to the field of electronic cigarettes.

Claims

A porous carbon heating element, wherein the interior of the porous carbon heating element has a plurality of through holes, and a plurality of blind holes are arranged on the wall of each of the through holes, and the diameter of the through holes is larger than that of the blind holes. Aperture diameter of the hole; the aperture diameter of the through hole is not larger than micron order, and the aperture diameter of the blind hole is nanometer order.
The porous carbon heating element according to claim 1, wherein the aperture of the through hole is 200-1000nm, the aperture of the blind hole is 10-100nm, and the depth of the blind hole is 10-100nm, the The porosity of the porous carbon heating element is 60%-90%.
The porous carbon heating element according to claim 2, wherein the through holes include zigzag through holes, and a plurality of zigzag through holes pass through.
A method for preparing the porous carbon heating element according to any one of claims 1 to 3, wherein the method for preparing the porous carbon heating element comprises:

forming a porous carbon matrix having a plurality of said through holes therein;

A plurality of blind holes are formed on the wall of the through hole.
The method for preparing a porous carbon heating element according to claim 4, wherein the method for forming a porous carbon matrix having a plurality of through holes inside is selected from the group consisting of: carbon fiber needle punching molding method, polymer pore-forming carbonization molding method, carbon fiber Any one of the pore-forming carbonization molding method mixed with the polymer and the porous template vapor deposition molding method;

Or/and, the method of forming a plurality of blind holes on the wall of the through hole is chemical vapor deposition or gas activation.
The method for preparing a porous carbon heating element according to claim 5, wherein the carbon fiber needle-punching method comprises: immersing the carbon fiber in a polymer solution, filtering and placing it in an acupuncture device for needle-punching, or first The carbon fiber is impregnated in the polymer solution after needle punching, drained and then heat treated; wherein, the conditions of the heat treatment are: inert gas protection, the temperature is 500-1500 °C; wherein, the polymer is a polymer One or more of acrylonitrile, polyimide, polycarbonate, polyarylene, phenolic resin, epoxy resin, asphalt;

Or, the polymer pore-forming carbonization molding method includes: drying and curing the solution with the polymer and the pore-forming agent and then heat treatment; wherein, the conditions of the heat treatment are: inert gas protection, the temperature is 500-1500 ℃, the mass ratio of the polymer to the pore-forming agent is (95:5)-(60:40); wherein, the polymer is polyacrylonitrile, polyimide, polycarbonate, polyarylene One or more of acetylene, phenolic resin, epoxy resin, asphalt; the pore-forming agent is one of ammonium bicarbonate, ammonium nitrate, starch, glucose, polyvinylpyrrolidone, polyvinyl butyral or several;

Or, the carbon fiber and polymer mixed pore-forming carbonization molding method includes: dispersing carbon fiber, polymer, and pore-forming agent in the same solution, and performing heat treatment after molding; wherein, the conditions of the heat treatment are: inert gas protection , the temperature is 500-1500 ° C, the mass ratio of the carbon fiber, the polymer and the pore-forming agent is (80-40): (80-40): (20-5); wherein, the polymerization The material is one or more of polyacrylonitrile, polyimide, polycarbonate, polyarylene, phenolic resin, epoxy resin, asphalt; the pore-forming agent is ammonium bicarbonate, ammonium nitrate, starch , glucose, polyvinylpyrrolidone, polyvinyl butyral or one or more of them;

Or, the porous template vapor deposition molding method includes: using porous metal as a template, hydrocarbon gas as a carbon source, performing vapor deposition, and then removing the porous metal template by pickling; wherein, the temperature of the vapor deposition is 800- 1500°C, the time is 1-8h.
The method for preparing a porous carbon heating element according to claim 5 or 6, wherein the chemical vapor deposition method comprises: placing the porous carbon substrate in a heating furnace, feeding an inert gas as a protective gas, and raising the temperature to 1000 -1500°C, feed hydrogen and methane, and process for 1-8h, so that graphene nanosheets grow on the hole walls of the porous carbon matrix, and the graphene nanosheets overlap to form the blind holes;

Alternatively, the gas activation method includes: placing the porous carbon substrate in a heating furnace, passing an inert gas as a protective gas, raising the temperature to 1000-1500° C., passing water vapor and/or carbon dioxide, and treating for 1-3 hours, The blind holes are formed on the pore walls of the porous carbon matrix.
An electrically heated atomizing core, wherein the electrically heated atomizing core comprises two electrodes and the porous carbon heating element according to any one of claims 1 to 3, the two electrodes are respectively fixed on the The two ends of the porous carbon heating element.
The electrically heated atomizing core according to claim 8, wherein the electrically heated atomizing core satisfies at least one of the following conditions a-g:

a, the electrode and the porous carbon heating element are fixed by means of welding, riveting, conductive paste layer, elastic clamping or pressure clamping;

b, the electrode is one of graphite electrodes, nickel electrodes, copper electrodes, iron electrodes, aluminum electrodes, silver electrodes and gold electrodes;

c, the porous carbon heating element is one of cuboid, polygonal prism, and truss;

d, at least one surface of the porous carbon heating element is an oil-absorbing surface;

e, the porous carbon heating element includes a heating atomization part and a liquid-absorbing liquid-guiding part connected to each other, and the electrode is fixed at the junction of the heating atomization part and the liquid-absorbing liquid-guiding part;

f, the length of the outer contour of the porous carbon heating element is 3-15 mm, the width is 1-5 mm, and the height is 0.5-2 mm; the distance between the two electrodes is 3-15 mm;

g. The electrically heated atomizing core further includes two conducting conductors, one conducting conductor is connected to one electrode.
The electrically heated atomizing core according to claim 8, wherein the electrode is a porous metal electrode.
The electrically heated atomizing core according to claim 8, wherein the electrode is one of porous nickel, porous copper, porous iron, porous aluminum, and porous silver.
The electrically heated atomizing core according to any one of claims 9 to 11, wherein the current conducting conductor is one of metal silver, copper, iron, aluminum, nickel and zinc.
The electrically heated atomizing core according to any one of claims 9 to 12, wherein the current conducting conductor is connected to the electrode by welding, riveting or pressure connection.
An electronic cigarette, wherein the electronic cigarette comprises the electrically heated atomizing core according to any one of claims 8 to 13.