Aerogel atomization core, preparation method therefor and electronic cigarette

Abstract

The present application relates to the technical field of electronic cigarettes, and in particular relates to an aerogel atomization core, a preparation method therefor, and an electronic cigarette. The preparation method of the aerogel atomization core comprises the following steps: molding a slurry containing a silicon source, a carbon source and a thickening agent, to prepare a green body; sintering the green body, to prepare a silicon nitride fiber aerogel matrix; forming a carbon coating on the surface and interior of the silicon nitride fiber aerogel matrix by means of chemical vapor infiltration, to prepare an inorganic fiber aerogel; and forming a heating layer on the inorganic fiber aerogel, to prepare the aerogel atomization core. The preparation method provided by the present application can not only avoid the use of large amounts of organic solvents, resulting in extremely low environmental pollution, but also produces an aerogel atomization core having high mechanical strength, high porosity, large pore size, and fast oil guiding, exhibiting excellent oil guiding and atomization performance, thereby effectively improving the usage performance of an electronic cigarette.

Description

Aerogel atomizing core and its preparation method and electronic cigarette

[0001] Related applications

[0002] This application claims priority to Chinese patent application filed on August 28, 2024, application number 2024111933523, entitled "Aerogel Atomizing Core and Preparation Method Thereof and Electronic Cigarette", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the technical field of electronic cigarettes, and in particular to an aerogel atomizing core, its preparation method, and an electronic cigarette. Background Technology

[0004] Electronic cigarettes are electronic products that heat e-liquid to produce an aerosol with a specific aroma. They are popular among consumers due to their advantages such as no secondhand smoke, no odor, and reduced intake of harmful substances. An electronic cigarette consists of components including a cartridge containing e-liquid, a mouthpiece, an atomizer coil, and a power source. The atomizer coil, as the core component, directly affects the user experience.

[0005] Currently, the main material for atomizer cores is organic cotton. However, organic cotton is prone to decomposition at high temperatures, producing harmful substances that affect user health. Therefore, there is a need to find a high-temperature resistant, non-toxic, and highly efficient atomizer core material. Aerogel materials, due to their high porosity, low density, and high specific surface area, are widely used in heat insulation, sound absorption, and adsorption, making them an ideal material for atomizer core preparation. However, aerogel atomizer cores prepared using traditional methods suffer from various problems, including small pore size, slow oil conduction, insufficient atomization volume, insufficient strength, and easy powder shedding. Summary of the Invention

[0006] According to various embodiments of this application, an aerogel atomizing core, a method for preparing the same, and an electronic cigarette are provided.

[0007] The above-mentioned objective of this application is achieved through the following technical solution:

[0008] In a first aspect, this application provides a method for preparing an aerogel atomizing core, comprising the following steps:

[0009] A slurry containing silicon source, carbon source and thickener is subjected to molding treatment to prepare a green body;

[0010] The green body is sintered to prepare a silicon nitride fiber aerogel matrix;

[0011] Inorganic fiber aerogels are prepared by forming a carbon coating on the surface and interior of the silicon nitride fiber aerogel matrix using a chemical vapor impregnation method.

[0012] A heating layer is formed on the inorganic fiber aerogel to prepare an aerogel atomizing core.

[0013] In one embodiment, the green blank is subjected to sintering treatment, including the following steps:

[0014] In a nitrogen atmosphere, the green body is sintered once to cause the silicon source and the carbon source to undergo a carbothermic reduction reaction and generate silicon nitride nanofibers in situ, thus preparing an intermediate.

[0015] The intermediate is subjected to a secondary sintering process in an air atmosphere to prepare the silicon nitride fiber aerogel matrix.

[0016] In one embodiment, the sintering temperature of the first sintering process is 1400℃~1700℃, and the holding time is 0.5h~24h.

[0017] In one embodiment, the sintering temperature of the first sintering process is 1400℃~1700℃, and the holding time is 0.5h~20h.

[0018] In one embodiment, the sintering temperature of the secondary sintering treatment is 600℃~1100℃, and the holding time is 0.1h~6h.

[0019] In one embodiment, the silicon source includes one or more of silicon powder, silicon carbide powder, silicon nitride powder, silicon dioxide powder, molybdenum disilicide powder, and silica sol.

[0020] In one embodiment, the carbon source includes one or more of carbon powder, graphite powder, and carbon fiber.

[0021] In one embodiment, the thickener includes one or more of sol, cellulose, cellulose derivatives, starch, and polymethyl methacrylate.

[0022] In one embodiment, the molar ratio of silicon to carbon in the slurry is 1:(1 to 10).

[0023] In one embodiment, the molding process includes one or more of room temperature pressure molding, hot die casting, and injection molding.

[0024] In one embodiment, the chemical vapor impregnation method includes the following steps:

[0025] The silicon nitride fiber aerogel matrix is ​​subjected to chemical vapor impregnation in an atmosphere containing volatile organic compounds to form a carbon coating on and inside the silicon nitride fiber aerogel matrix.

[0026] In one embodiment, the volatile organic compound includes one or more of methane, ethane, propane, ethylene, acetylene, and propylene.

[0027] In one embodiment, the atmosphere containing volatile organic compounds further contains a carrier gas, and the flow rate ratio of the volatile organic compounds to the carrier gas is 1:(0.5 to 5).

[0028] In one embodiment, the conditions for the chemical vapor impregnation treatment include: a pressure of 100 Pa to 10000 Pa, a temperature of 600 °C to 1300 °C, and a time of 0.5 h to 12 h.

[0029] In one embodiment, the thickness of the carbon coating is 1 nm to 500 nm.

[0030] In a second aspect, this application provides an aerogel atomizing core, which is prepared using the aerogel atomizing core preparation method described above.

[0031] In one embodiment, the porosity of the aerogel atomizing core is 50% to 98%.

[0032] In one embodiment, the pore size of the aerogel atomizing core is 5μm to 50μm.

[0033] In one embodiment, the bulk density of the aerogel atomizing core is 5 mg / cm³. 3 ~5000mg / cm 3 .

[0034] In a third aspect, this application provides an electronic cigarette, including an aerogel atomizing core as described above. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the disclosed drawings without creative effort.

[0036] Figure 1 is a schematic flowchart of a method for preparing an aerogel atomizing core according to one or more embodiments;

[0037] Figure 2 is a SEM image of the aerogel atomizing core prepared in Example 1. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] To facilitate understanding of this application, the following detailed description is provided in conjunction with specific embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0041] In this application, "and / or" means any and all combinations of one or more of the related listed items. "At least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two, three, etc., unless otherwise expressly and specifically defined. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.

[0042] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0043] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0044] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0045] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0046] In this application, room temperature refers to indoor temperature, normal temperature, or general temperature. Generally, room temperature can be any of the following temperature ranges: 23℃±2℃, 25℃±5℃, or 20℃±5℃.

[0047] Inorganic fiber aerogel materials are aerogel materials that use inorganic nanofibers as building blocks and form a three-dimensional porous network structure through the interlocking of these nanofibers. Due to their excellent mechanical properties and chemical stability, they are considered ideal atomizing core materials. However, traditional aerogel atomizing core preparation methods usually require the use of large amounts of organic solvents, which is not only costly but also causes serious environmental pollution. Some reports have described using physical or chemical methods to mix tetraethyl orthosilicate with anhydrous ethanol and water, employing sol-gel methods and supercritical drying to prepare silica aerogel atomizing cores. Aerogel materials prepared by this method are prone to brittleness and fracture, making assembly difficult, and they easily shed powder. Furthermore, their pore size is nanoscale; although this results in high porosity and high oil absorption, the small pore size leads to slow oil conduction speed, resulting in insufficient vapor production.

[0048] Based on this, the first aspect of this application provides a method for preparing an aerogel atomizing core, in order to solve various problems of aerogel atomizing cores prepared by traditional methods, such as small pore size, slow oil conduction, insufficient atomization amount, insufficient strength, and easy powder shedding.

[0049] Please refer to Figure 1, which is a flowchart illustrating a method for preparing an aerogel atomizing core according to one or more embodiments. It should be understood that although the steps in the flowchart shown in Figure 1 are displayed sequentially as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be performed in other orders. Moreover, at least some of the steps in Figure 1 may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be performed at different times, and their execution order is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps. In some embodiments, the method for preparing an aerogel atomizing core includes the following steps:

[0050] S100: A slurry containing silicon source, carbon source and thickener is shaped to prepare a green body;

[0051] S200: Sintering the green body to prepare silicon nitride fiber aerogel matrix;

[0052] S300: Inorganic fiber aerogel is prepared by forming a carbon coating on the surface and inside of a silicon nitride fiber aerogel matrix through chemical vapor impregnation.

[0053] S400: A heating layer is formed on inorganic fiber aerogel to prepare an aerogel atomizing core.

[0054] This application involves molding a slurry containing a silicon source, a carbon source, and a thickener to obtain a green body. Inorganic fiber growth technology is then employed to generate a large number of silicon nitride nanofibers in situ during high-temperature sintering, forming a silicon nitride fiber aerogel matrix with a three-dimensional porous network structure. Simultaneously, a carbon coating is formed on the surface and interior of the silicon nitride fiber aerogel matrix through chemical vapor deposition (CVD), which increases the diameter of the silicon nitride nanofibers and creates fixed nodes between them, thereby enhancing mechanical strength. Compared to traditional methods, the aerogel atomizing core preparation method provided in this application not only avoids the use of large amounts of organic solvents, resulting in extremely low environmental pollution, but also produces an aerogel atomizing core with advantages such as high mechanical strength, high porosity, large pore size, and fast oil conduction, exhibiting excellent atomization performance and effectively improving the user experience of electronic cigarettes.

[0055] The preparation method of the aerogel atomizing core is described in steps below.

[0056] S100: A slurry containing silicon source, carbon source and thickener is shaped to prepare a green body.

[0057] Optionally, the silicon source includes one or more of silicon (Si) powder, silicon carbide (SiC) powder, silicon nitride (Si3N4) powder, silicon dioxide (SiO2) powder, molybdenum disilicide (MoSi2) powder, and silica sol, and may further be silicon powder.

[0058] Optionally, the carbon source includes one or more of carbon powder, graphite powder, and carbon fiber, and is further optionally carbon powder.

[0059] Optionally, the thickener includes one or more of sol, cellulose, cellulose derivatives, starch and polymethyl methacrylate (PMMA), and is further optionally cellulose.

[0060] Understandably, sols include one or more of silica sols, alumina sols, titanium sols, and zirconium sols. Silica sols can be used simultaneously as both a silicon source and a thickener. Cellulose derivatives refer to products formed after the hydroxyl groups in cellulose molecules undergo esterification or etherification reactions. They can be divided into three main categories: cellulose ethers, cellulose esters, and cellulose ether esters. Common cellulose derivatives include: methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropyl methylcellulose, carboxymethylcellulose, cellulose nitrate, cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose sulfonate, cellulose nitrate, cellulose acetate, cellulose acetate butyrate, and cellulose xanthate, etc. Cellulose, cellulose derivatives, starch, and PMMA are mainly used as thickeners, but can also be used as carbon sources.

[0061] In this application, silicon sources are selected from raw materials such as silicon powder and silicon carbide powder, carbon sources are selected from raw materials such as carbon powder and graphite powder, and thickeners are selected from raw materials such as cellulose and starch. All raw materials are inexpensive, which helps to reduce the production cost of aerogel atomizing cores.

[0062] Optionally, the particle size of the silicon source, carbon source, and thickener can each be independently 10 mesh to 200 mesh, for example 10 mesh, 20 mesh, 40 mesh, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh, or 200 mesh.

[0063] Understandably, mesh size is a unit used to measure particle size. 10 mesh corresponds to a pore size of approximately 2000 μm, and 200 mesh corresponds to a pore size of approximately 74 μm. That is, the particle sizes of silicon source, carbon source, and thickener are each independently between 74 μm and 2000 μm, for example, 74 μm, 100 μm, 150 μm, 200 μm, 400 μm, 600 μm, 800 μm, 1000 μm, 1200 μm, 1400 μm, 1600 μm, 1800 μm, or 2000 μm.

[0064] Optionally, the molar ratio of silicon to carbon in the green body is 1:(1 to 10), for example 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, and further optionally 1:(3 to 5).

[0065] During sintering, if the reaction conditions are different, some carbon sources may undergo side reactions and be lost, resulting in insufficient reaction of the silicon powder. Therefore, by appropriately increasing the amount of carbon source, the possible losses of carbon source and incomplete reaction of silicon source can be compensated for.

[0066] Optionally, the dispersion medium in the slurry includes one or more of water, methanol, ethanol, and isopropanol, and more preferably water. The water can be selected from one or more of tap water, deionized water, pure water, ultrapure water, distilled water, and reverse osmosis water. Using tap water helps reduce costs, while using deionized water or pure water helps improve the quality of the aerogel material.

[0067] Optionally, the solid content of the slurry is 50% to 90%, for example 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%.

[0068] Optionally, the solid content of the green body is 60% to 99%, for example 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99%.

[0069] Optionally, the molding process includes one or more of room temperature pressure molding, hot die casting, and injection molding, and may further be room temperature pressure molding.

[0070] S200: Sintering the green body to prepare a silicon nitride fiber aerogel matrix.

[0071] Optionally, the green body is sintered, including the following steps:

[0072] S210: In a nitrogen atmosphere, the green body is sintered once to cause the silicon source and carbon source to undergo a carbothermic reduction reaction and generate silicon nitride nanofibers in situ, thus preparing an intermediate.

[0073] S220: The intermediate is subjected to a secondary sintering process in an air atmosphere to prepare a silicon nitride fiber aerogel matrix.

[0074] This application employs a primary sintering process in a nitrogen atmosphere, which generates silicon-containing and carbon-containing gases from the silicon and carbon sources in the green body at high temperatures. A carbothermic reduction reaction occurs between these gases, resulting in the in-situ formation of a large number of Si3N4 nanofibers. These Si3N4 nanofibers interlock to form an intermediate with a three-dimensional porous network structure. A secondary sintering process in an air atmosphere removes any residual unreacted materials (such as excess carbon source or thickener) from the intermediate, thereby obtaining a pure Si3N4 fiber aerogel matrix.

[0075] Optionally, the sintering temperature for the single sintering process is 1400℃~1700℃, and the holding time is 0.5h~24h. As an example, the sintering temperature for the single sintering process can be 1400℃, 1450℃, 1500℃, 1550℃, 1600℃, 1650℃, or 1700℃, and the holding time can be 0.5h, 1h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, or 24h. Further, the sintering temperature for the single sintering process is 1400℃~1700℃, and the holding time is 0.5h~20h.

[0076] Optionally, the sintering temperature for the secondary sintering treatment is 600℃~1100℃, and the holding time is 0.1h~6h. As an example, the sintering temperature for the secondary sintering treatment can be 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, or 1100℃, and the holding time can be 0.1h, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, or 6h.

[0077] Optionally, the silicon nitride nanofibers in the silicon nitride fiber aerogel matrix meet the following conditions: (1) the diameter is 50nm to 500nm, for example 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm or 500nm, and further optionally 198nm to 230nm; (2) the length is ≥10μm, for example 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm or 100μm, and further optionally 12μm to 36μm.

[0078] Optionally, the bulk density of the silicon nitride fiber aerogel matrix is ​​1000 mg / cm³. 3 ~10000mg / cm 3 For example, 1000mg / cm 3 2000mg / cm 3 3000mg / cm 3 4000mg / cm 3 5000mg / cm 3 6000mg / cm 3 7000mg / cm 3 8000mg / cm 3 9000mg / cm 3 Or 10000mg / cm 3 .

[0079] Compared with aerogel materials prepared by traditional methods, the silicon nitride fiber aerogel matrix prepared by this application through molding and sintering processes not only has high porosity and large pore size, but also higher strength.

[0080] S300: Inorganic fiber aerogels are prepared by forming a carbon coating on the surface and inside of a silicon nitride fiber aerogel matrix through chemical vapor impregnation.

[0081] Optionally, the chemical vapor impregnation method includes the following steps: subjecting a silicon nitride fiber aerogel matrix to chemical vapor impregnation in an atmosphere containing volatile organic compounds to form a carbon coating on and inside the silicon nitride fiber aerogel matrix.

[0082] Understandably, Chemical Vapor Infiltration (CVI) is an important process for surface modification of materials. In CVI treatment, a gaseous precursor containing the target element is introduced into a reaction chamber. Under certain temperature and pressure conditions, the gaseous precursor is deposited on the surface or pores of the material through a chemical reaction, thereby improving the strength and toughness of the material.

[0083] Understandably, volatile organic compounds (VOCs) refer to organic compounds with high vapor pressure and high volatility at room temperature and pressure. During the CVI process, VOCs decompose and deposit a carbon coating on and inside the silicon nitride fiber aerogel matrix, effectively enhancing the mechanical strength of the inorganic fiber aerogel. Furthermore, compared to low-density aerogel materials prepared by conventional methods, the silicon nitride fiber aerogel matrix of this application has a high density of silicon nitride nanofibers. After CVI reinforcement treatment, a more significant strengthening effect can be achieved, resulting in higher mechanical strength for the inorganic fiber aerogel.

[0084] Optionally, the volatile organic compounds include one or more of methane, ethane, propane, ethylene, acetylene, and propylene, and may further be methane.

[0085] Optionally, the atmosphere containing volatile organic compounds also contains a carrier gas, which includes one or more of helium, neon, argon and xenon, and is further optionally argon.

[0086] The flow rate ratio of volatile organic compounds (VOCs) to carrier gas is 1:(0.5–5), for example, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, or 1:5. The flow rate of VOCs is 0.001 mL / min to 1 mL / min, and the flow rate of carrier gas is 0.1 mL / min to 1000 mL / min.

[0087] Optionally, the pressure of the chemical vapor impregnation treatment is 100 Pa to 10000 Pa, for example, 100 Pa, 200 Pa, 500 Pa, 1000 Pa, 5000 Pa, or 8000 Pa, and further optionally, 1000 Pa. The temperature of the chemical vapor impregnation treatment is 600 °C to 1300 °C, for example, 600 °C, 650 °C, 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, 950 °C, 1200 °C, or 1300 °C. The time of the chemical vapor impregnation treatment is 0.5 h to 12 h, for example, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 5 h, or 10 h.

[0088] Optionally, the thickness of the carbon coating is 100nm to 1000nm, such as 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm, and further optionally 407nm to 672nm.

[0089] S400: A heating layer is formed on inorganic fiber aerogel to prepare an aerogel atomizing core.

[0090] Alternatively, methods for forming a heating layer on inorganic fiber aerogel include printing a resistive paste, sputtering a resistive layer, or attaching a heating mesh.

[0091] In a second aspect, this application provides an aerogel atomizing core, which is prepared using the aerogel atomizing core preparation method described above.

[0092] Optionally, the porosity of the aerogel atomizing core is 50% to 98%, such as 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 98%, and more preferably 78.9% to 85.9%.

[0093] Optionally, the pore size of the aerogel atomizing core is 5μm to 50μm, such as 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm or 50μm, and further optionally 6μm to 23μm.

[0094] Optionally, the aerogel atomizing core has a bulk density of 5 mg / cm³. 3 ~5000mg / cm 3 For example, 5mg / cm 3 50mg / cm 3 100mg / cm 3 200mg / cm 3 500mg / cm 3 1000mg / cm 3 2000mg / cm 33000mg / cm 3 4000mg / cm 3 Or 5000mg / cm 3 A further option is 390 mg / cm³. 3 ~710mg / cm 3 .

[0095] Optionally, the compressive strength of the aerogel atomizing core is 0.1 MPa to 100 MPa, for example 0.1 MPa, 1 MPa, 5 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa or 100 MPa, and further optionally 4 MPa to 6 MPa.

[0096] The aerogel atomizing core provided in this application features high porosity, large pore size, and uniform pore size distribution. Its porosity is adjustable within the range of 50% to 98%, and its pore size is adjustable within the range of 5μm to 50μm. Furthermore, it exhibits high mechanical strength and demonstrates excellent oil conduction, atomization, and safety performance, thereby effectively enhancing the user experience. In addition, the aerogel atomizing core can be manufactured in block, film, fiber, or other pre-defined shapes to meet diverse application requirements. Overall, the aerogel atomizing core of this application possesses advantages such as superior product performance, simple manufacturing process, low cost, strong environmental friendliness, and diverse product shapes.

[0097] In a third aspect, this application provides an electronic cigarette, including an aerogel atomizing core as described above.

[0098] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.

[0099] Example 1

[0100] The preparation method of the aerogel atomizing core in this embodiment is as follows:

[0101] (1) Preparation of green body: Under the conditions of argon protection, pressure of 1 atm and temperature of 25°C, silicon source, carbon source, thickener and deionized water are mixed at a mixing speed of 500 rpm and a mixing time of 30 min to obtain slurry; the slurry is subjected to room temperature pressure molding treatment to obtain green body with solid content of 76%.

[0102] The silicon source is silicon powder with a purity of 99.9% and a particle size of 100 mesh.

[0103] The carbon source is carbon powder with a purity of 99.9% and a particle size of 200 mesh;

[0104] The thickener is made of cellulose with a purity of 99.9% and a particle size of 200 mesh.

[0105] The resistivity of deionized water is 18.2 MΩ·cm;

[0106] The mass ratio of silicon source, carbon source, thickener and deionized water is 1:5:2:2.5, and the molar ratio of carbon element to silicon element is 1:5.

[0107] (2) First sintering treatment: The green blank is placed in a high-temperature furnace and protected by nitrogen gas. The temperature is raised to 1500℃ at a heating rate of 5℃ / min and held for 2 hours to allow the silicon source, carbon source and thickener in the green blank to undergo carbothermic reduction reaction and grow Si3N4 nanofibers in situ. After cooling with the furnace, the intermediate is obtained.

[0108] (3) Secondary sintering treatment: The intermediate is placed in a muffle furnace and heated to 800°C at a heating rate of 5°C / min in an air atmosphere. It is held for 2 hours to remove the residual unreacted carbon source and other raw materials in the intermediate. After cooling in the furnace, silicon nitride fiber aerogel matrix is ​​obtained.

[0109] (4) Chemical vapor impregnation treatment: The silicon nitride fiber aerogel matrix is ​​placed in a chemical vapor impregnation furnace with methane as the precursor at a flow rate of 0.01 mL / min and argon as the carrier gas at a flow rate of 10 mL / min. The chemical vapor impregnation is carried out for 2 hours at a temperature of 800℃ and a pressure of 1 atm to form a carbon coating on the surface and inside of the silicon nitride fiber aerogel matrix. After cooling in the furnace, the matrix is ​​removed to obtain inorganic fiber aerogel.

[0110] (5) Preparation of aerogel atomizing core: Cut inorganic aerogel fibers into cuboids with a length of 9mm, a width of 4mm and a thickness of 2mm, and then print heating circuits or attach heating electrodes on the surface of the cuboids to obtain the aerogel atomizing core.

[0111] Example 2

[0112] The difference between this embodiment and Embodiment 1 is that the carbon source is graphite powder with a purity of 99.9% and a particle size of 200 mesh.

[0113] Example 3

[0114] The difference between this embodiment and Embodiment 1 is that the silicon source is silicon carbide powder with a purity of 99.9% and a particle size of 100 mesh.

[0115] Example 4

[0116] The difference between this embodiment and Embodiment 1 is that the thickener used is starch with a purity of 99.9% and a particle size of 200 mesh.

[0117] Example 5

[0118] The difference between this embodiment and Embodiment 1 is that the mass ratio of silicon source, carbon source, thickener and deionized water is 1:3:1:0.5, and the molar ratio of carbon element to silicon element is 1:3.

[0119] Example 6

[0120] The difference between this embodiment and embodiment 1 is that the temperature of the first sintering treatment in step (2) is 1700℃ and the holding time is 0.5h.

[0121] Example 7

[0122] The difference between this embodiment and embodiment 1 is that the temperature of the first sintering treatment in step (2) is 1400℃ and the holding time is 20h.

[0123] Example 8

[0124] The difference between this embodiment and embodiment 1 is that the temperature of the chemical vapor impregnation treatment in step (4) is 1000℃ and the holding time is 0.5h.

[0125] Comparative Example 1

[0126] This comparative example uses a traditional method to prepare the aerogel matrix. The specific steps are as follows: tetraethyl orthosilicate is mixed with anhydrous ethanol and water in a certain proportion, stirred evenly, hydrolyzed with acid, and then alkali is added to obtain silica gel. After that, supercritical drying is performed to obtain the silica aerogel matrix.

[0127] After obtaining the silica aerogel matrix, chemical vapor impregnation was performed according to step (4) of Example 1 and a heating layer was prepared according to step (5) to obtain the aerogel atomizing core.

[0128] Comparative Example 2

[0129] The preparation method of the aerogel atomizing core in this comparative example is as follows:

[0130] (1) Preparation of slurry: Prepare slurry according to step (1) of Example 1, without molding.

[0131] (2) Sintering treatment: Perform a first sintering treatment according to step (2) of Example 1, and a second sintering treatment according to step (3) of Example 1 to obtain silicon nitride fiber powder.

[0132] (3) Molding process: Pour silicon nitride fiber powder into a mold and press it at room temperature to obtain silicon nitride fiber aerogel matrix.

[0133] (4) Chemical vapor impregnation treatment: Same as step (4) in Example 1.

[0134] (5) Preparation of aerogel atomizing core: Same as step (5) in Example 1.

[0135] Comparative Example 3

[0136] The difference between this comparative example and Example 1 is that the chemical vapor impregnation treatment in step (4) was not performed.

[0137] Comparative Example 4

[0138] The difference between this comparative example and Example 1 is that no thickener was added in step (1).

[0139] Test case

[0140] The aerogel atomizing cores prepared in each embodiment and comparative example were subjected to the following tests:

[0141] (1) Morphological characterization: The micromorphology of silicon nitride fiber aerogel matrix and aerogel atomization core was observed by scanning electron microscopy (SEM). The length and diameter of silicon nitride nanofibers in silicon nitride fiber aerogel matrix and aerogel atomization core were recorded. The thickness of carbon coating was also calculated. The results are shown in Table 1 and Figure 2.

[0142] (2) Bulk density and porosity: The bulk density and porosity of the aerogel atomizing core were measured using a density and porosity tester, and the results are shown in Table 2. The porosity test method was based on the national standard JIS R1634-1998, and the porosity of the aerogel atomizing core was determined according to Archimedes' water displacement method.

[0143] (3) Aperture: Using a pore size tester, the aerogel atomizing core was first evacuated and then placed in the tooling. Argon gas was introduced and the pore size of the aerogel atomizing core was calculated by the system by monitoring the gas pressure and the amount of gas passing through the sample. The results are shown in Table 2.

[0144] (4) Mechanical strength: Referring to the national standard GB / T 1041-2008, the compressive stress-strain curve of the aerogel atomizing core was measured using a mechanical testing machine, and the compressive strength of the aerogel atomizing core was calculated. The results are shown in Table 2.

[0145] (5) Liquefaction performance: Internal standard tests were conducted using e-liquid. A mixture of glycerol (VG) and propylene glycol (PG) was placed in a container at a volume ratio of 1:1. A sponge was placed in the container with its height above the liquid level. The porous substrate was placed parallel to the sponge, and the timing was started until the e-liquid rose from the bottom of the sample to the top surface of the sample through capillary action. The time taken for the e-liquid to rise from the bottom of the sample to the top surface was measured. Three samples were tested for each formulation of each example, and the average value was calculated.

[0146] (6) Atomization performance: The total particulate matter (TPM) generated by the aerogel atomizing core during atomization was measured using an oil-conducting test device and a suction resistance meter. The results are shown in Table 2. The higher the TPM value, the better the atomization performance of the aerogel atomizing core.

[0147] As shown in Figure 2 and Table 1, compared with Comparative Examples 1-4, the silicon nitride nanofibers in the aerogel atomizing cores prepared in Examples 1-8 have a larger diameter before and after CVI treatment, and the thickness of the resulting carbon coating is also significantly higher. This is beneficial to improving the mechanical strength and safety of the aerogel atomizing core.

[0148] As shown in Table 2, compared with Comparative Examples 1 to 4, the aerogel atomizing cores prepared in Examples 1 to 8 have higher porosity, larger pore size, higher bulk density and higher compressive strength, and exhibit excellent oil conduction and atomization performance.

[0149] Table 1. Silicon nitride nanofibers in the aerogel atomizing core

[0150] Table 2. Performance of Aerogel Atomizing Core

[0151] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0152] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method for preparing an aerogel atomizing core, comprising the following steps: A slurry containing silicon source, carbon source and thickener is subjected to molding treatment to prepare a green body; The green body is sintered to prepare a silicon nitride fiber aerogel matrix; Inorganic fiber aerogels are prepared by forming a carbon coating on the surface and interior of the silicon nitride fiber aerogel matrix using a chemical vapor impregnation method. A heating layer is formed on the inorganic fiber aerogel to prepare an aerogel atomizing core.

2. The method for preparing the aerogel atomizing core as described in claim 1, wherein, The green blank is subjected to sintering treatment, including the following steps: In a nitrogen atmosphere, the green body is sintered once to cause the silicon source and the carbon source to undergo a carbothermic reduction reaction and generate silicon nitride nanofibers in situ, thus preparing an intermediate. The intermediate is subjected to a secondary sintering process in an air atmosphere to prepare the silicon nitride fiber aerogel matrix.

3. The method for preparing the aerogel atomizing core as described in claim 2, wherein, The sintering temperature of the first sintering treatment is 1400℃~1700℃, and the holding time is 0.5h~24h.

4. The method for preparing the aerogel atomizing core as described in claim 3, wherein the sintering temperature of the first sintering treatment is 1400℃~1700℃, and the holding time is 0.5h~20h.

5. The method for preparing the aerogel atomizing core according to any one of claims 2 to 4, wherein, The sintering temperature of the secondary sintering treatment is 600℃~1100℃, and the holding time is 0.1h~6h.

6. The method for preparing the aerogel atomizing core according to any one of claims 1 to 5, wherein, The chemical vapor impregnation method includes the following steps: The silicon nitride fiber aerogel matrix is ​​subjected to chemical vapor impregnation in an atmosphere containing volatile organic compounds to form a carbon coating on and inside the silicon nitride fiber aerogel matrix.

7. The method for preparing the aerogel atomizing core as described in claim 6, wherein, One or more of the following conditions must be met: (1) The volatile organic compounds include one or more of methane, ethane, propane, ethylene, acetylene, and propylene; (2) The atmosphere containing volatile organic compounds also contains a carrier gas, and the flow rate ratio of the volatile organic compounds to the carrier gas is 1:(0.5~5); (3) The conditions for the chemical vapor impregnation treatment include: pressure of 100 Pa to 10000 Pa, temperature of 600 °C to 1300 °C, and time of 0.5 h to 12 h; (4) The thickness of the carbon coating is 1 nm to 500 nm.

8. The method for preparing the aerogel atomizing core according to any one of claims 1 to 7, wherein, One or more of the following conditions must be met: (1) The silicon source includes one or more of silicon powder, silicon carbide powder, silicon nitride powder, silicon dioxide powder, molybdenum disilicide powder, and silica sol; (2) The carbon source includes one or more of carbon powder, graphite powder and carbon fiber; (3) The thickener includes one or more of sol, cellulose, cellulose derivatives, starch and polymethyl methacrylate; (4) The molar ratio of silicon to carbon in the slurry is 1:(1~10); (5) The molding process includes one or more of the following: room temperature pressure molding process, hot die casting process and injection molding process.

9. An aerogel atomizing core, prepared by the aerogel atomizing core preparation method according to any one of claims 1 to 8.

10. The aerogel atomizing core as described in claim 9, wherein, One or more of the following conditions must be met: (1) The porosity of the aerogel atomizing core is 50% to 98%; (2) The pore size of the aerogel atomizing core is 5μm to 50μm; (3) The bulk density of the aerogel atomizing core is 5 mg / cm³. 3 ~5000mg / cm 3 .

11. An electronic cigarette comprising an aerogel atomizing core as described in claim 9 or 10.

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