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 atomization core, preparation method thereof and electronic cigarette

[0001] Related applications

[0002] The present application claims priority to the Chinese patent application No. 2024111933523, filed on August 28, 2024, and entitled "Aerogel atomization core, preparation method thereof and electronic cigarette", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of electronic cigarettes, and in particular to an aerogel atomization core, a preparation method thereof and an electronic cigarette. BACKGROUND

[0004] An electronic cigarette is an electronic product that generates an aerosol with a specific odor by atomizing tobacco tar through heating, and is favored by a large number of consumers due to its advantages of no second-hand smoke, no smoke odor, and reduced intake of harmful substances. An electronic cigarette includes a tobacco pipe for containing tobacco tar, a mouthpiece, an atomization core, and a power source, etc. The atomization core is a core component of the electronic cigarette, and its performance directly affects the use effect of the electronic cigarette.

[0005] At present, the main material of the atomization core is organic cotton. However, organic cotton is prone to decomposition at high temperatures, generating harmful substances and affecting user health, and thus a high-temperature-resistant, non-toxic, and efficient atomization core material needs to be found. Aerogel material is widely used in heat insulation, sound absorption, adsorption, etc. due to its high porosity, low density, and high specific surface area, and is an ideal material for preparing an atomization core. However, the aerogel atomization core prepared by a traditional method has various problems such as small pore size, slow oil guiding, insufficient atomization amount, insufficient strength, and easy powdering. SUMMARY

[0006] According to various embodiments of the present application, an aerogel atomization core, a preparation method thereof and an electronic cigarette are provided.

[0007] The above object of the present application is achieved by the following technical solutions:

[0008] In a first aspect of the present application, a preparation method of an aerogel atomization core is provided, including the following steps:

[0009] Performing a molding treatment on a slurry containing a silicon source, a carbon source and a thickening agent to prepare a green body;

[0010] Performing a sintering treatment on the green body to prepare a silicon nitride fiber aerogel matrix;

[0011] Forming a carbon coating layer on the surface and inside of the silicon nitride fiber aerogel matrix by a chemical vapor immersion method to prepare an inorganic fiber aerogel;

[0012] Forming a heating layer on the inorganic fiber aerogel to prepare an aerogel atomization core.

[0013] In one of the embodiments, the green body is subjected to a sintering process, including the following steps:

[0014] In a nitrogen atmosphere, the green body is subjected to a first sintering process to cause a carbothermal reduction reaction between the silicon source and the carbon source and in-situ generate silicon nitride nanofibers, to prepare an intermediate;

[0015] In an air atmosphere, the intermediate is subjected to a second sintering process to prepare the silicon nitride fiber aerogel matrix.

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

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

[0018] In one of the embodiments, the sintering temperature of the second sintering process is 600-1100℃, and the holding time is 0.1-6h.

[0019] In one of the embodiments, 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 of the embodiments, the carbon source includes one or more of carbon powder, graphite powder, and carbon fiber.

[0021] In one of the embodiments, the thickening agent includes one or more of sol, cellulose, cellulose derivative, starch, and polymethyl methacrylate.

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

[0023] In one of the embodiments, the forming process includes one or more of normal-temperature pressure forming process, hot-pressing casting forming process, and injection molding process.

[0024] In one of the embodiments, the chemical vapor infiltration method includes the following steps:

[0025] In an atmosphere containing volatile organic matter, the silicon nitride fiber aerogel matrix is subjected to a chemical vapor infiltration process to form a carbon coating layer on the surface and inside of the silicon nitride fiber aerogel matrix.

[0026] In one of the embodiments, the volatile organic compounds include one or more of methane, ethane, propane, ethylene, acetylene and propylene.

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

[0028] In one of the embodiments, the chemical vapor infiltration treatment is performed under the conditions of a pressure of 100 Pa-10000 Pa, a temperature of 600℃-1300℃ and a time of 0.5 h-12 h.

[0029] In one of the embodiments, the carbon coating layer has a thickness of 1 nm-500 nm.

[0030] In the second aspect of the present application, an aerogel atomization core is provided, which is prepared by the method for preparing an aerogel atomization core as described above.

[0031] In one of the embodiments, the aerogel atomization core has a porosity of 50%-98%.

[0032] In one of the embodiments, the aerogel atomization core has a pore size of 5 μm-50 μm.

[0033] In one of the embodiments, the aerogel atomization core has a bulk density of 5 mg / cm 3 -5000 mg / cm 3 .

[0034] In the third aspect of the present application, an electronic cigarette is provided, which includes the aerogel atomization core as described above. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of the disclosed drawings.

[0036] Fig. 1 is a flowchart of a method for preparing an aerogel atomization core according to one or more embodiments;

[0037] Fig. 2 is an SEM image of the aerogel atomization core prepared in Example 1. DETAILED DESCRIPTION

[0038] With reference to the drawings and the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative effort belong to the scope of the present application.

[0039] In order to facilitate the understanding of the present application, the present application will be further described in detail in combination with specific embodiments. However, the present application can be implemented in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[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 in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0041] In the present application, the meaning of "and / or" is any and all combinations of one or more relevant listed items. The meaning of "at least one" is more than one, such as one, two, and more than two. The meaning of "a plurality of" or "several" is at least two, such as two, three, and the like, unless otherwise specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, and the like, unless otherwise specifically defined.

[0042] When a numerical range is disclosed in the present application, the above range is considered to be continuous and includes the minimum value and the maximum value of the range, as well as every value between the minimum value and the maximum value. Further, when the range refers to an integer, every integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed in the present application should be understood to include any and all sub-ranges incorporated therein.

[0043] If not specifically stated, all steps of the present application can be performed in sequence or randomly. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

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

[0045] The temperature parameters in the present application, unless otherwise specified, allow for constant temperature treatment, but also allow for fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations are allowed within a range of, for example, ±5°C, ±4°C, ±3°C, ±2°C, ±1°C.

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

[0047] Inorganic fiber aerogel material is an aerogel material with inorganic nanofiber as building block and three-dimensional porous network structure formed by interlocking of inorganic nanofiber. Due to its excellent mechanical properties and chemical stability, it is considered as an ideal atomization core material. However, the traditional aerogel atomization core preparation method usually needs to use a large amount of organic solvent, which not only has high cost, but also causes serious environmental pollution. It has been reported that tetraethyl orthosilicate is mixed with anhydrous ethanol and water by physical or chemical method, and silica aerogel atomization core is prepared by sol-gel method and supercritical drying method. The aerogel material prepared by this method is easy to break, which is not conducive to assembly, and is easy to fall off; moreover, the pore size is nanoscale, although the porosity is high and the oil absorption capacity is high, the small pore size makes the oil guiding speed very slow, which will lead to serious shortage of smoke.

[0048] Based on this, the first aspect of the present application provides a preparation method of aerogel atomization core to solve various problems of the aerogel atomization core prepared by the traditional method, such as small pore size, slow oil guiding, insufficient atomization, insufficient strength, easy to fall off and the like.

[0049] Please refer to FIG. 1, which is a flowchart of the preparation method of aerogel atomization core according to one or more embodiments. It should be understood that although each step in the flowchart shown in FIG. 1 is displayed in sequence according to the indication of the arrow, these steps are not necessarily executed in the order indicated by the arrow. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and they can be executed in other orders. Moreover, at least part of the steps in FIG. 1 can include multiple sub-steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence is not necessarily sequential, but can be executed alternately or alternately with at least part of other steps or sub-steps or stages of other steps. In some embodiments, the preparation method of aerogel atomization core comprises the following steps:

[0050] S100: performing a forming treatment on a slurry containing a silicon source, a carbon source and a thickening agent to prepare a green body;

[0051] S200: performing a sintering treatment on the green body to prepare a silicon nitride fiber aerogel matrix;

[0052] S300: forming a carbon coating layer on the surface and inside of the silicon nitride fiber aerogel matrix through a chemical vapor phase impregnation treatment to prepare an inorganic fiber aerogel;

[0053] S400: forming a heating layer on the inorganic fiber aerogel to prepare an aerogel atomization core.

[0054] The present application performs a forming treatment on a slurry containing a silicon source, a carbon source and a thickening agent to prepare a green body, and uses inorganic fiber growth technology to enable the silicon source and the carbon source in the green body to generate a large amount of silicon nitride nanofiber in situ during a high-temperature sintering process, thereby forming a silicon nitride fiber aerogel matrix with a three-dimensional porous network structure. At the same time, a carbon coating layer is formed on the surface and inside of the silicon nitride fiber aerogel matrix through a chemical vapor phase impregnation treatment, which can increase the diameter of the silicon nitride nanofiber and form fixed nodes between the silicon nitride nanofibers, thereby achieving the effect of enhancing the mechanical strength. Compared with traditional methods, the preparation method of the aerogel atomization core provided by the present application not only avoids the use of a large amount of organic solvents and has extremely low environmental pollution, but also has the advantages of high mechanical strength, high porosity, large pore size and fast oil conductivity, and exhibits excellent atomization performance, thereby effectively improving the use effect of the electronic cigarette.

[0055] The preparation method of the aerogel atomization core is described below in a step-by-step manner.

[0056] S100: performing a forming treatment on a slurry containing a silicon source, a carbon source and a thickening agent 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 is further optionally 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 thickening agent includes one or more of sol, cellulose, cellulose derivative, starch and polymethyl methacrylate (PMMA), and is further optionally cellulose.

[0060] It can be understood that the sol includes one or more of a silica sol, an aluminum sol, a titanium sol, and a zirconium sol, wherein the silica sol can be used as a silicon source and a thickening agent at the same time. The cellulose derivative refers to a product after esterification or etherification reaction of a hydroxyl group in a cellulose molecule, and can be divided into three categories of cellulose ether, cellulose ester, and cellulose ether ester. Common cellulose derivatives include methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, nitrocellulose, cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, sulfonic acid cellulose, cellulose nitrate, cellulose acetate, cellulose acetate butyrate, and cellulose xanthate. Cellulose, cellulose derivatives, starch, and PMMA are mainly used as thickening agents, and can also be used as carbon sources.

[0061] In the present application, the silicon source is selected from silicon powder, silicon carbide powder and the like, the carbon source is selected from carbon powder, graphite powder and the like, and the thickening agent is selected from cellulose, starch and the like. All raw materials are low in price, which is conducive to reducing the production cost of the aerogel atomization core.

[0062] Alternatively, the particle size of the silicon source, the carbon source, and the thickening agent is 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] It can be understood that the mesh number is a unit for measuring the particle size, 10 mesh corresponds to a pore size of about 2000 μm, and 200 mesh corresponds to a pore size of about 74 μm, that is, the particle size of the silicon source, the carbon source, and the thickening agent is independently 74 μm to 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] Alternatively, the molar ratio of the silicon element and the carbon element in the green body is 1:(1-10), 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 alternatively 1:(3-5).

[0065] In the sintering process, if the reaction conditions are different, part of the carbon source will cause side reactions and result in loss, which leads to insufficient reaction of the silicon powder. Therefore, by appropriately increasing the amount of the carbon source, the loss of the carbon source and the insufficient reaction of the silicon source can be compensated.

[0066] Optionally, the dispersion medium in the slurry comprises one or more of water, methanol, ethanol and isopropanol, and further optionally 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, and the use of tap water is advantageous in reducing cost, and the use of deionized water or pure water is advantageous in improving 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 forming process comprises one or more of room temperature pressure forming process, hot-pressing casting forming process and injection molding process, and further optionally the room temperature pressure forming process.

[0070] S200: performing a sintering process on the green body to prepare a silicon nitride fiber aerogel matrix.

[0071] Optionally, the sintering process on the green body comprises the following steps:

[0072] S210: performing a first sintering process on the green body in a nitrogen atmosphere, so that the silicon source and the carbon source in the green body generate a silicon-containing gas and a carbon-containing gas at high temperature, and the silicon-containing gas and the carbon-containing gas generate a large amount of Si3N4 nanofibers in situ through a carbothermal reduction reaction, and the Si3N4 nanofibers are interlaced with each other to form an intermediate body having a three-dimensional porous network structure.

[0073] S220: performing a second sintering process on the intermediate body in an air atmosphere to prepare a silicon nitride fiber aerogel matrix.

[0074] The present application generates a silicon-containing gas and a carbon-containing gas from the silicon source and the carbon source in the green body at high temperature through a first sintering process in a nitrogen atmosphere, and the silicon-containing gas and the carbon-containing gas generate a large amount of Si3N4 nanofibers in situ through a carbothermal reduction reaction, and the Si3N4 nanofibers are interlaced with each other to form an intermediate body having a three-dimensional porous network structure. The second sintering process in an air atmosphere can remove residual unreacted raw materials (such as excess carbon source or thickening agent) in the intermediate body, thereby obtaining a pure Si3N4 fiber aerogel matrix.

[0075] Optionally, the sintering temperature of the first sintering process is 1400°C to 1700°C, and the holding time is 0.5h to 24h. As an example, the sintering temperature of the first sintering process can be 1400°C, 1450°C, 1500°C, 1550°C, 1600°C, 1650°C, or 1700°C, and the holding time can be 0.5h, lh, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, or 24h. Further, the sintering temperature of the first sintering process is 1400°C to 1700°C, and the holding time is 0.5h to 20h.

[0076] Optionally, the sintering temperature of the second sintering process is 600°C to 1100°C, and the holding time is 0.1h to 6h. As an example, the sintering temperature of the second sintering process can be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, or 1100°C, and the holding time can be 0.1h, 0.5h, lh, 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 satisfy the following conditions: (1) the diameter is 50nm to 500nm, for example, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, or 500nm, further optionally 198nm to 230nm; (2) the length is ≥10μm, for example, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, or 100μm, further optionally 12μm to 36μm.

[0078] Optionally, the silicon nitride fiber aerogel matrix has a bulk density of 1000mg / cm 3 to 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 the aerogel material prepared by the traditional method, the silicon nitride fiber aerogel body prepared by the shaping treatment and the sintering treatment has high porosity, large pore size and high strength.

[0080] S300: forming a carbon coating on the surface and inside of the silicon nitride fiber aerogel body by chemical vapor infiltration treatment, and preparing the inorganic fiber aerogel.

[0081] Optionally, the chemical vapor infiltration method comprises the following steps: performing chemical vapor infiltration treatment on the silicon nitride fiber aerogel body in an atmosphere containing volatile organic compounds to form a carbon coating on the surface and inside of the silicon nitride fiber aerogel body.

[0082] It can be understood that chemical vapor infiltration (CVI) is an important process for surface modification of materials. In the CVI process, a gaseous precursor containing target elements is introduced into a reaction chamber, and under certain temperature and pressure conditions, the gaseous precursor is deposited on the surface or pores of the material through chemical reaction, thereby improving the strength and toughness of the material.

[0083] It can be understood that volatile organic compounds (VOCs) refer to organic compounds with high vapor pressure and easy volatilization at normal temperature and pressure. In the CVI process, volatile organic compounds are decomposed and deposited to form a carbon coating on the surface and inside of the silicon nitride fiber aerogel body, thereby effectively enhancing the mechanical strength of the inorganic fiber aerogel. In addition, compared with the low-density aerogel material prepared by the traditional method, the silicon nitride fiber aerogel body of the present application has high-density silicon nitride nanofibers, and after the strengthening treatment by CVI, more significant strengthening effect can be achieved, and the mechanical strength of the inorganic fiber aerogel is higher.

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

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

[0086] The flow ratio of the volatile organic compounds to the 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. Among them, the flow rate of the volatile organic compounds is 0.001 mL / min-1 mL / min, and the flow rate of the carrier gas is 0.1 mL / min-1000 mL / min,

[0087] Optionally, the pressure of the chemical vapor immersion 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 immersion treatment is 600℃ to 1300℃, for example, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1200℃, or 1300℃. The time of the chemical vapor immersion treatment is 0.5h to 12h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 5h, or 10h.

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

[0089] S400: forming a heating layer on the inorganic fiber aerogel to prepare an aerogel atomization core.

[0090] Optionally, the method of forming a heating layer on the inorganic fiber aerogel comprises printing a resistive paste, sputtering a resistive layer, or attaching a heating mesh.

[0091] In a second aspect, the application provides an aerogel atomization core prepared by the method described above.

[0092] Optionally, the porosity of the aerogel atomization core is 50% to 98%, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 98%, and further optionally 78.9% to 85.9%.

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

[0094] Optionally, the bulk density of the aerogel atomization core is 5mg / cm 3 to 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 3, 3000 mg / cm 3 , 4000 mg / cm 3 or 5000 mg / cm 3 , further optionally 390 mg / cm 3 ~ 710 mg / cm 3 .

[0095] Optionally, the compression strength of the aerogel atomization core is 0.1 MPa ~ 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, further optionally 4 MPa ~ 6 MPa.

[0096] The aerogel atomization core provided in the present application has the characteristics of high porosity, large pore size and uniform pore size distribution, the porosity thereof is adjustable within the range of 50% ~ 98%, the pore size is adjustable within the range of 5 μm ~ 50 μm, and the mechanical strength is high, which can exhibit excellent oil guiding performance, atomization performance and safety performance, thereby effectively improving the user's experience. In addition, the aerogel atomization core can also be made into blocks, films, fibers or other pre-set shapes, which can meet different application requirements. Overall, the aerogel atomization core of the present application has the advantages of excellent product performance, simple preparation process, low manufacturing cost, strong environmental protection and diversified product shapes.

[0097] In a third aspect, the present application provides an electronic cigarette comprising the aerogel atomization core as described above.

[0098] The following will be further described in combination with specific examples and comparative examples. The raw materials involved in the following specific examples and comparative examples, if not specifically stated, can be sourced from the market. The instruments used, if not specifically stated, can be sourced from the market. The processes involved, if not specifically stated, are conventionally selected by those skilled in the art.

[0099] Example 1

[0100] The preparation method of the aerogel atomization core of the present example is as follows:

[0101] (1) Preparation of green body: under the conditions of argon protection, pressure of 1 atm and temperature of 25℃, mix the silicon source, carbon source, thickening agent and deionized water, the mixing speed is 500 rpm, and the mixing time is 30 min, to obtain a slurry; the slurry is subjected to normal temperature pressure forming treatment to obtain a green body with a 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 thickening agent is cellulose with a purity of 99.9% and a particle size of 200 mesh;

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

[0106] The mass ratio of the silicon source, the carbon source, the thickening agent and the deionized water is 1:5:2:2.5, and the molar ratio of carbon elements and silicon elements is 1:5.

[0107] (2) One sintering treatment: the green body is placed in a high-temperature furnace, nitrogen is introduced for protection, the temperature is raised to 1500℃ at a rate of 5℃ / min, and the temperature is kept for 2h, so that the silicon source, the carbon source and the thickening agent in the green body perform carbothermic reduction reaction and in-situ growth of Si3N4 nanofiber, and the intermediate is obtained after cooling in the furnace.

[0108] (3) Secondary sintering treatment: the intermediate is placed in a muffle furnace, the temperature is raised to 800℃ in an air atmosphere at a rate of 5℃ / min, and the temperature is kept for 2h to remove the residual unreacted carbon source and other raw materials in the intermediate, and the silicon nitride fiber aerogel matrix is obtained after cooling in the furnace.

[0109] (4) Chemical vapor immersion treatment: the silicon nitride fiber aerogel matrix is placed in a chemical vapor immersion furnace, methane is used as the precursor, the flow rate of methane is 0.01 mL / min, argon is used as the carrier gas, the flow rate of argon is 10 mL / min, the chemical vapor immersion is carried out at a temperature of 800℃ and a pressure of 1 atm for 2 hours, a carbon coating is formed on the surface and inside of the silicon nitride fiber aerogel matrix, and the inorganic fiber aerogel is obtained after cooling in the furnace and taking out.

[0110] (5) Preparation of aerogel atomization core: the inorganic aerogel fiber is cut into a cuboid with a length of 9mm, a width of 4mm and a thickness of 2mm, then a heating circuit is printed on the surface of the cuboid or a heating electrode sheet is attached, and the aerogel atomization core is obtained.

[0111] Example 2

[0112] The difference between this embodiment and Example 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 Example 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 thickening agent 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 the silicon source, the carbon source, the thickening agent and the deionized water is 1:3:1:0.5, and the molar ratio of the carbon element and the silicon element is 1:3.

[0119] Example 6

[0120] The difference between this embodiment and embodiment 1 is that the temperature of the one-time sintering treatment in step (2) is 1700°C, 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 one-time sintering treatment in step (2) is 1400°C, 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 immersion treatment in step (4) is 1000°C, and the holding time is 0.5h.

[0125] Comparative Example 1

[0126] In this comparative example, the aerogel matrix is prepared by a traditional method. The specific steps are as follows: a certain proportion of tetraethyl orthosilicate, anhydrous ethanol and water are mixed and stirred uniformly, acid hydrolysis is performed, and then base is added to obtain a silica gel, followed by supercritical drying to obtain a silica aerogel matrix.

[0127] After the silica aerogel matrix is prepared, the chemical vapor immersion treatment according to step (4) of embodiment 1 and the preparation of the heat generating layer according to step (5) are performed to obtain an aerogel atomization core.

[0128] Comparative Example 2

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

[0130] (1) Preparation of slurry: the slurry is prepared according to step (1) of embodiment 1, and no molding treatment is performed.

[0131] (2) Sintering treatment: one-time sintering treatment is performed according to step (2) of embodiment 1, and two-time sintering treatment is performed according to step (3) of embodiment 1 to obtain a silicon nitride fiber powder;

[0132] (3) Molding treatment: the silicon nitride fiber powder is poured into a mold, and cold pressing is performed using a press to obtain a silicon nitride fiber aerogel matrix.

[0133] (4) Chemical vapor infiltration treatment: same as step (4) of Example 1.

[0134] (5) Preparation of aerogel atomization core: same as step (5) of Example 1.

[0135] Comparative Example 3

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

[0137] Comparative Example 4

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

[0139] Test Example

[0140] The aerogel atomization cores prepared in each example and each comparative example are tested as follows:

[0141] (1) Morphology characterization: The micro-morphology of the silicon nitride fiber aerogel matrix and the aerogel atomization core is observed by scanning electron microscopy (SEM), and the length and diameter of the silicon nitride nanofibers in the silicon nitride fiber aerogel matrix are recorded, the length and diameter of the silicon nitride nanofibers in the aerogel atomization core are recorded, and the thickness of the carbon coating is 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 atomization core are measured by a density and porosity tester, the results are shown in Table 2. Among them, the test method of porosity refers to the national standard JIS R1634-1998, and the porosity of the aerogel atomization core is determined according to the Archimedes drainage method.

[0143] (3) Pore size: The aerogel atomization core is first vacuumed, then put into a tooling, and then argon gas is passed through, by monitoring the data such as the pressure of the gas and the amount of gas passing through the sample, the pore size of the aerogel atomization core is calculated by the system, 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 atomization core is measured by a mechanical testing machine, and the compressive strength of the aerogel atomization core is calculated, the results are shown in Table 2.

[0145] (5) Oil guiding performance: Internal standard test was performed using tobacco tar, and a mixed solvent 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, and the height of the sponge was higher than the liquid level. A porous substrate was placed parallel to the sponge, and the time taken for the tobacco tar to rise from the bottom surface of the sample to the upper surface of the sample by capillary force was measured. Three samples were tested for each example formulation, and the average value was obtained.

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

[0147] As can be seen from FIG. 2 and Table 1, compared with Comparative Examples 1-4, the silicon nitride nanofibers in the aerogel atomization cores prepared in Examples 1-8 have a larger diameter before and after CVI treatment, and the thickness of the obtained carbon coating is also significantly higher, which is beneficial to improve the mechanical strength and safety of the aerogel atomization core.

[0148] As can be seen from Table 2, compared with Comparative Examples 1-4, the aerogel atomization cores prepared in Examples 1-8 have higher porosity, larger pore size, higher bulk density and higher compressive strength, and exhibit excellent oil guiding performance and atomization performance.

[0149] Table 1. Silicon nitride nanofibers of aerogel atomization cores

[0150] Table 2. Performance of aerogel atomization cores

[0151] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0152] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of protection of the present application. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A method for preparing an aerogel atomizing core, comprising the following steps: performing a molding treatment on a slurry containing a silicon source, a carbon source and a thickening agent to prepare a green body; performing a sintering treatment on the green body to prepare a silicon nitride fiber aerogel matrix; forming a carbon coating layer on the surface and inside of the silicon nitride fiber aerogel matrix by a chemical vapor infiltration method to prepare an inorganic fiber aerogel; forming a heating layer on the inorganic fiber aerogel to prepare an aerogel atomizing core.

2. The method of making an aerogel atomizing core of claim 1, wherein, The sintering treatment on the green body comprises the following steps: performing a first sintering treatment on the green body in a nitrogen atmosphere to make the silicon source and the carbon source undergo a carbothermic reduction reaction and generate silicon nitride nanofibers in situ to prepare an intermediate; performing a second sintering treatment on the intermediate in an air atmosphere to prepare the silicon nitride fiber aerogel matrix.

3. The method of making an aerogel atomizing core of 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 an aerogel atomizing core according to 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 of making an aerogel atomizing tip of any of claims 2-4, wherein, The sintering temperature of the second sintering treatment is 600℃-1100℃, and the holding time is 0.1h-6h.

6. The method of making an aerogel atomizing tip of any one of claims 1-5, wherein, The chemical vapor infiltration method comprises the following steps: performing a chemical vapor infiltration treatment on the silicon nitride fiber aerogel matrix in a volatile organic-containing atmosphere to form a carbon coating layer on the surface and inside of the silicon nitride fiber aerogel matrix.

7. The method of making an aerogel atomizing core of claim 6 wherein, One or more of the following conditions are met: (1) the volatile organic compound comprises one or more of methane, ethane, propane, ethylene, acetylene and propylene; (2) the volatile organic-containing atmosphere further contains a carrier gas, and the flow ratio of the volatile organic compound to the carrier gas is 1:(0.5-5); (3) the conditions of the chemical vapor infiltration treatment include a pressure of 100Pa-10000Pa, a temperature of 600℃-1300℃, and a time of 0.5h-12h; (4) the thickness of the carbon coating layer is 1nm-500nm.

8. The method of making an aerogel atomizing core according to any one of claims 1 to 7, wherein, One or more of the following conditions are met: (1) the silicon source comprises 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 comprises one or more of carbon powder, graphite powder and carbon fiber; (3) the thickening agent comprises one or more of sol, cellulose, cellulose derivative, starch and polymethyl methacrylate; (4) the molar ratio of silicon element to carbon element in the slurry is 1:(1-10); (5) the molding treatment comprises one or more of normal temperature pressure molding treatment, hot-pressing casting molding treatment and injection molding treatment. 9.An aerogel atomizing core prepared by the method for preparing an aerogel atomizing core according to any one of claims 1-8.

10. The aerogel atomizing tip of claim 9, wherein, One or more of the following conditions are met: (1) the porosity of the aerogel atomizing core is 50%-98%; (2) the pore size of the aerogel atomizing core is 5μm-50μm; (3) the aerogel aerosol core has a bulk density of 5 mg / cm 3 ~ 5000 mg / cm 3 . 11.An electronic cigarette comprising the aerogel atomizing core according to claim 9 or 10.

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