Smoke cooling composite aerogel for heating cigarettes as well as preparation method and application of smoke cooling composite aerogel

Abstract

The invention discloses smoke cooling composite aerogel for heating cigarettes as well as a preparation method and application of the smoke cooling composite aerogel, and belongs to the technical field of heating cigarette cooling materials. The preparation method provided by the invention comprises the following steps: performing ultrasonic stripping dispersion on graphite oxide and aramid fibers in water to obtain a graphene oxide / aramid nanofiber dispersion liquid, adding ascorbic acid, and then performing heating reduction and standing to obtain hydrogel; carrying out freeze drying to obtain reduced graphene oxide / aramid nanofiber aerogel; mixing the reduced graphene oxide / aramid nanofiber aerogel with eicosane under a heating condition, standing at a constant temperature, and cooling to obtain the composite material. When the smoke cooling composite aerogel is used for heating a cooling section of a cigarette, smoke can be effectively cooled, the final smoke outlet temperature is reduced to 50 DEG C or below, and the smoking experience of a user is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat-not-burn cigarette cooling materials, and particularly relates to a smoke cooling composite aerogel for heat-not-burn cigarettes, a preparation method thereof, and an application thereof. Background Art

[0002] The information disclosed in the background art of the present invention is only intended to increase the understanding of the overall background of the present invention, and does not necessarily be regarded as an admission or imply in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] A heat-not-burn cigarette is a tobacco product that generates smoke by heating rather than burning tobacco, also known as a heat-not-burn cigarette, which mainly includes three parts: a tobacco section, a cooling section, and a cellulose acetate filter section. The heat-not-burn cigarette uses sealed heating instead of cigarette burning to distill and crack tobacco components to release smoke, greatly reducing the harm to smokers. However, the amount of smoke released and the smoke concentration of heat-not-burn cigarettes are relatively low, reducing the sensory experience of consumers. To improve the taste of the inhaled smoke, heat-not-burn cigarettes are generally shorter in length. The shorter cigarette length greatly shortens the smoke passage, resulting in an increase in the sensory temperature of the mainstream smoke reaching the oral cavity. Consumers will have a certain burning sensation when smoking heat-not-burn cigarettes, thus causing certain damage to the consumer's oral cavity, trachea, etc., seriously affecting the smoking experience of heat-not-burn cigarettes. Therefore, the cooling treatment of the mainstream smoke temperature has become the key to the research and development of heat-not-burn cigarettes.

[0004] Regarding the research on the cooling of the mainstream smoke of heat-not-burn cigarettes, most of them are achieved by adding phase change materials, heat conduction materials, or a composite material of both, so as to absorb and conduct the high heat released during the cigarette heating process to achieve the cooling effect. However, due to the problem of loose structure caused by the stacking and enrichment of materials, the cooling and interception effects are limited, and the draw resistance is relatively large, which is difficult to meet the development needs of heat-not-burn cigarettes.

[0005] Therefore, how to provide a smoke cooling material for heat-not-burn cigarettes with good cooling effect and small draw resistance is an urgent problem to be solved. Summary of the Invention

[0006] In view of this, the present invention provides a smoke cooling composite aerogel for heat-not-burn cigarettes, a preparation method thereof, and an application thereof. The smoke cooling composite aerogel for heat-not-burn cigarettes provided by the present invention has a good cooling effect, good structural stability, and small draw resistance, and can greatly improve the smoking experience of users.

[0007] In the first aspect, the present invention provides a preparation method of a smoke cooling composite aerogel for heat-not-burn cigarettes, including the following steps:

[0008] Ultrasonically exfoliating and dispersing graphite oxide and aramid fiber in water to obtain a graphene oxide / aramid nanofiber dispersion;

[0009] Ascorbic acid is added to the graphene oxide / aramid nanofiber dispersion, and then heated and reduced. After cooling, reduced graphene oxide / aramid nanofiber hydrogel is obtained; after freeze-drying, reduced graphene oxide / aramid nanofiber aerogel is obtained.

[0010] Under heating conditions, the reduced graphene oxide / aramid nanofiber aerogel is mixed with eicosane and kept at a constant temperature and left standing, and then cooled to obtain the product.

[0011] Preferably, in the step of ultrasonically exfoliating and dispersing graphite oxide and aramid fibers in water, the dosage ratio of graphite oxide, aramid fibers and water is 30 mg:(5 - 20) mg:(10 - 30) mL; the mass ratio of graphite oxide and ascorbic acid is 3:(15 - 25).

[0012] Preferably, the preparation method of the graphite oxide is: treating graphite successively with concentrated sulfuric acid and potassium permanganate, then reacting in an aqueous hydrogen peroxide solution, and washing until neutral to obtain graphite oxide.

[0013] Preferably, in the ultrasonically exfoliating and dispersing step, the ultrasonic power is 200 - 300 W, and the ultrasonic time is 2 - 8 h.

[0014] Preferably, the temperature of the heating reduction is 40 - 60 °C, and the time of the heating reduction is 36 - 48 h.

[0015] Preferably, after the step of obtaining the reduced graphene oxide / aramid nanofiber hydrogel, a dialysis step is further included.

[0016] Preferably, the mass ratio of the reduced graphene oxide / aramid nanofiber aerogel to eicosane is 1:(5 - 12).

[0017] Preferably, in the step of mixing the reduced graphene oxide / aramid nanofiber aerogel with eicosane under heating conditions and keeping at a constant temperature and left standing, the heating conditions are 70 - 90 °C, and the time of keeping at a constant temperature and left standing is 1 - 2 h.

[0018] In the second aspect, the present invention provides a composite aerogel for reducing the temperature of the mainstream smoke of a heated cigarette prepared by the above preparation method.

[0019] In the third aspect, the present invention provides the application of the above composite aerogel for reducing the temperature of the mainstream smoke of a heated cigarette, and the application is adding the composite aerogel for reducing the temperature of the mainstream smoke of a heated cigarette to the temperature reduction section of the heated cigarette.

[0020] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0021] The present invention uses an aerogel composed of reduced graphene oxide and aramid nanofibers to physically adsorb eicosane phase change material, thereby preparing a composite aerogel with good flue gas cooling performance. Among them, reduced graphene oxide has good thermal conductivity, which can quickly conduct the heat of the flue gas to the eicosane in the aerogel. The phase change temperature of eicosane is lower than the temperature of the flue gas, so it can effectively absorb heat during the phase change process, thereby reducing the temperature of the flue gas and avoiding adverse effects on users caused by too high flue gas temperature. The introduction of aramid nanofibers can not only play a good role in regulating and stabilizing the pore structure of the aerogel itself, improve the structural stability of the material, and then ensure an appropriate draw resistance during the suction process. Therefore, when the flue gas cooling composite aerogel of the present invention is used in the cooling section of a heated cigarette, it can effectively cool the flue gas, reduce the final flue gas outlet temperature to below 50°C, and greatly improve the user's suction experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments and descriptions thereof of the invention are used to explain the invention and do not constitute an improper limitation of the invention. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 are the X-ray diffraction patterns of the rGO@ANFs@EI composite aerogel and graphene oxide (GO), reduced graphene oxide (rGO), and aramid nanofibers (ANFs) in the examples and comparative examples of the present invention;

[0024] Figure 2 are the scanning electron microscope pictures of the aerogel materials prepared in Comparative Example 2, 3 and Examples 1, 2 of the present invention. Among them, (a) is Comparative Example 2, (b) is Example 2, (c) is Example 1, and (d) is Comparative Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0025] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0026] The present invention provides a method for preparing a flue gas cooling composite aerogel for a heated cigarette, comprising the following steps:

[0027] Ultrasonically exfoliate and disperse graphite oxide and aramid fiber in water to obtain a graphene oxide / aramid nanofiber dispersion;

[0028] Ascorbic acid is added to the graphene oxide / aramid nanofiber dispersion, and then heated for reduction, and then cooled to obtain a reduced graphene oxide / aramid nanofiber hydrogel; and then freeze-dried to obtain a reduced graphene oxide / aramid nanofiber aerogel;

[0029] The reduced graphene oxide / aramid nanofiber aerogel is mixed with eicosane under heating conditions, allowed to stand at a constant temperature, and then cooled to obtain the aerogel.

[0030] The present invention firstly uses ultrasound to mechanically exfoliate and disperse graphite oxide and aramid fibers, thereby obtaining a graphene oxide / aramid nanofiber dispersion, which will have a certain impact on the structure of the aerogel. In order to obtain a three-dimensional, porous, lightweight composite aerogel, the graphene oxide and aramid nanofibers must be mixed before a subsequent reduction process, otherwise it is difficult to achieve the preparation of a uniform aerogel.

[0031] The present invention uses ascorbic acid as a green reducing agent to partially reduce graphene oxide, and the obtained reduced graphene oxide has better thermal conductivity and can quickly conduct smoke heat, thereby facilitating rapid cooling of smoke. The present invention mixes reduced graphene oxide / aramid nanofiber aerogel with eicosane under heating conditions, and during constant temperature standing, eicosane enters the reduced graphene oxide / aramid nanofiber aerogel through capillary action, and after cooling, eicosane solidifies, thereby obtaining a smoke cooling composite aerogel for heating cigarettes.

[0032] The present invention uses eicosane (n-eicosane) with a low melting point as a phase change material, which has the characteristics of high latent heat of phase change, low supercooling, good chemical stability and thermal stability, and its phase change temperature is suitable for the temperature range of the smoke of the heated cigarette passing through the cooling section. However, the thermal conductivity of eicosane is low, so the present invention introduces a three-dimensional, lightweight, porous structure of reduced graphene oxide / aramid nanofiber aerogel as a skeleton. On the one hand, the porous structure of the aerogel can effectively wrap and carry eicosane, and increase the contact area between the smoke and eicosane. On the other hand, the high thermal conductivity of reduced graphene oxide promotes the rapid absorption of smoke heat by eicosane, so that the heat of the smoke is rapidly reduced. The introduction of aramid nanofibers can play a good role in regulating and stabilizing the pore structure of the aerogel, and can ensure that the heated cigarette has a lower draw resistance when used, and improve the user's suction experience. The above-mentioned substances used in the present invention have good safety and stability, and will not produce harmful substances when used in the cooling section, avoiding adverse effects on the human body.

[0033] In the step of ultrasonically exfoliating and dispersing graphite oxide and aramid fiber in water according to the present invention, the dosage ratio of graphite oxide, aramid fiber and water is 30 mg : (5 - 20) mg : (10 - 30) mL; an appropriate mass ratio can ensure that the formed aerogel has a good pore structure and excellent thermal conductivity. The mass ratio of the graphite oxide and ascorbic acid is 3 : (15 - 25).

[0034] In the present invention, the preparation method of the graphite oxide is as follows: graphite is successively treated with concentrated sulfuric acid and potassium permanganate, and then reacted in an aqueous hydrogen peroxide solution, and washed to neutrality to obtain graphite oxide. Graphite oxide can also be prepared by other methods in the art, or can be purchased, and the present invention does not make special restrictions on this. In the present invention, before the step of ultrasonically exfoliating and dispersing, it is preferred to grind the graphite oxide to facilitate the preparation of graphene oxide by ultrasonically exfoliating and dispersing.

[0035] In the present invention, in the step of ultrasonically exfoliating and dispersing, the ultrasonic power is 200 - 300 W, and the ultrasonic time is 2 - 8 h, more preferably 3 - 7 h, and further preferably 4 - 6 h. If the ultrasonic time is too short, it will lead to uneven dispersion, too large size of graphene oxide, uneven internal structure of the aerogel material, thereby affecting the adsorption of eicosane, and there is also a risk of eicosane leakage. On the one hand, too long ultrasonic time will lead to too high energy consumption, and on the other hand, it will lead to too small pore size of the formed aerogel, resulting in an increase in suction resistance and a decline in the user experience.

[0036] In the present invention, the temperature of the thermal reduction is 40 - 60 °C, and the time of the thermal reduction is 36 - 48 h. During the thermal reduction process, the oxygen-containing functional groups in the graphite oxide are removed, the conjugated structure begins to reconnect and expand again, and the carbon atoms will form a more complete conjugated system through rehybridization and other means, so that the graphene oxide gradually returns to a structure similar to graphene, improving its crystallinity and thermal conductivity.

[0037] In the present invention, after the step of obtaining the reduced graphene oxide / aramid nanofiber hydrogel, a dialysis step is further included. The dialysis process is to remove the unreacted ascorbic acid. The pore size of the dialysis bag used for dialysis is more than 10000 D, and the dialysis time is 4 - 7 days.

[0038] In the present invention, the mass ratio of the reduced graphene oxide / aramid nanofiber aerogel to eicosane is 1 : (5 - 12). The reduced graphene oxide / aramid nanofiber aerogel is immersed in eicosane. An appropriate mass ratio can ensure that the obtained composite aerogel has a good cooling effect, reducing the final flue gas temperature to below 50 °C.

[0039] In the present invention, in the step of mixing reduced graphene oxide / aramid nanofiber aerogel with eicosane under heating conditions and then keeping the temperature constant and standing still, the heating conditions are 70 - 90 °C, which is above the melting point of eicosane. Eicosane enters the aerogel in liquid form under capillary action. The time for keeping the temperature constant and standing still is 1 - 2 h to enable eicosane to enter the aerogel for storage.

[0040] The present invention also provides a composite aerogel for reducing the temperature of mainstream smoke of heated tobacco products prepared by the above preparation method.

[0041] The present invention also provides an application of the above composite aerogel for reducing the temperature of mainstream smoke of heated tobacco products. The application is to add the composite aerogel for reducing the temperature of mainstream smoke of heated tobacco products to the temperature reduction section of the heated tobacco product.

[0042] The technical solution of the present invention will be further described below in conjunction with specific embodiments. The present invention places no special restrictions on the sources of the reagents used in the following examples, and commercially available products well-known to those skilled in the art can be used.

[0043] In the following examples, the preparation method of graphite oxide powder is as follows: Take 1.5 g of graphite and add it to concentrated sulfuric acid (200 mL). Heat and stir the above mixed reactants using a water bath. The heating temperature is 50 °C, the stirring speed is 600 rpm, and the stirring duration is 1 h. Then add 9 g of potassium permanganate and continue to heat and stir using a water bath. The heating temperature is 90 °C, the stirring speed is 600 rpm, and the stirring duration is 3 h. Then add 200 mL of deionized water and 15 mL of 30% hydrogen peroxide for reaction. Finally, wash with deionized water until neutral to obtain graphite oxide powder. Grind the obtained graphite oxide powder using an agate mortar for 1 h and set aside.

[0044] Example 1

[0045] This example provides a preparation method of a composite aerogel rGO@ANFs@EI for reducing the temperature of mainstream smoke.

[0046] (1) Weigh 30 mg of the ground graphite oxide powder and 10 mg of aramid fiber using a balance, pour them into a measuring cup containing 20 mL of deionized water, and use an ultrasonic cell disruptor to ultrasonically exfoliate and disperse them. The ultrasonic power is 250 W, and the ultrasonic duration is 6 h to obtain a reduced graphene oxide / aramid nanofiber dispersion.

[0047] (2) Add 0.2 g of ascorbic acid to the reduced graphene oxide / aramid nanofiber dispersion in step (1), then raise the temperature to 50 °C and react for 48 h. Cool to room temperature to obtain a reduced graphene oxide / aramid nanofiber hydrogel. Use a dialysis bag with a pore size of 10000 D and dialyze it in deionized water for 5 days, during which the water outside the dialysis bag is changed several times. After pre-freezing and freeze-drying, a reduced graphene oxide / aramid nanofiber aerogel is obtained.

[0048] (3) Keep 10 mg of reduced graphene oxide / aramid nanofiber aerogel and 90 mg of eicosane standing at a constant temperature of 80 °C for 2 h, and then cool to room temperature to obtain the composite aerogel rGO@ANFs@EI for reducing the temperature of the smoke of heated cigarettes.

[0049] Example 2

[0050] This example provides a preparation method of the composite aerogel rGO@ANFs@EI for reducing the temperature of the smoke.

[0051] (1) Weigh 30 mg of ground graphite oxide powder and 10 mg of aramid fiber with a balance, pour them into a measuring cup containing 20 mL of deionized water, and use an ultrasonic cell disruptor to ultrasonically exfoliate and disperse them. The ultrasonic power is 250 W and the ultrasonic time is 4 h to obtain a graphene oxide / aramid nanofiber dispersion.

[0052] (2) Add 0.2 g of ascorbic acid to the graphene oxide / aramid nanofiber dispersion in step (1), then raise the temperature to 50 °C and react for 48 h, cool to room temperature, and let it stand to obtain a reduced graphene oxide / aramid nanofiber hydrogel; use a dialysis bag with a pore size of 10000 D and dialyze it in deionized water for 5 days, and change the water outside the dialysis bag several times during this period; obtain the reduced graphene oxide / aramid nanofiber aerogel through pre-freezing and freeze-drying.

[0053] (3) Keep 10 mg of reduced graphene oxide / aramid nanofiber aerogel and 90 mg of eicosane standing at a constant temperature of 80 °C for 2 h, and then cool to room temperature to obtain the composite aerogel rGO@ANFs@EI for reducing the temperature of the smoke of heated cigarettes.

[0054] Example 3

[0055] This example provides a preparation method of the composite aerogel rGO@ANFs@EI for reducing the temperature of the smoke.

[0056] (1) Weigh 30 mg of ground graphite oxide powder and 10 mg of aramid fiber with a balance, pour them into a measuring cup containing 20 mL of deionized water, and use an ultrasonic cell disruptor to ultrasonically exfoliate and disperse them. The ultrasonic power is 250 W and the ultrasonic time is 6 h to obtain a graphene oxide / aramid nanofiber dispersion.

[0057] (2) Add 0.2 g of ascorbic acid to the graphene oxide / aramid nanofiber dispersion in step (1), then raise the temperature to 50 °C and react for 48 h, cool to room temperature, and let it stand to obtain a reduced graphene oxide / aramid nanofiber hydrogel; use a dialysis bag with a pore size of 10000 D and dialyze it in deionized water for 5 days, and change the water outside the dialysis bag several times during this period; obtain the reduced graphene oxide / aramid nanofiber aerogel through pre-freezing and freeze-drying.

[0058] (3) 10 mg of reduced graphene oxide / aramid nanofiber aerogel and 120 mg of eicosane were kept at a constant temperature of 80 °C for 2 h and then cooled to room temperature to obtain the flue gas cooling composite aerogel rGO@ANFs@EI for heated cigarettes.

[0059] Comparative Example 1

[0060] Compared with Example 1, the difference in this comparative example is that no aramid fiber is added in this comparative example.

[0061] Comparative Example 2

[0062] Compared with Example 1, the difference in this comparative example is that the sonication time in this comparative example is 2 h.

[0063] Comparative Example 3

[0064] Compared with Example 1, the difference in this comparative example is that the sonication time in this comparative example is 8 h.

[0065] Comparative Example 4

[0066] Compared with Example 1, the difference in this comparative example is that the addition amount of aramid fiber in this comparative example is 50 mg.

[0067] Comparative Example 5

[0068] Compared with Example 1, the difference in this comparative example is that the addition amount of eicosane in this comparative example is 30 mg.

[0069] Test Example

[0070] 1. X-ray diffraction pattern:

[0071] Figure 1 X-ray diffraction patterns of graphene oxide (GO), reduced graphene oxide (rGO), aramid nanofibers (ANFs), and rGO@ANFs@EI composite aerogel. For the GO sample, there is a strong diffraction peak at 10.8°, corresponding to the (001) crystal plane, proving the successful synthesis of graphene oxide; the diffraction peaks of rGO are located at about 23.6° and 43.1°, corresponding to the (002) and (100) crystal planes, indicating that GO is reduced to rGO; the diffraction peaks of aramid nanofibers are located at about 20.6° and 23.0°, corresponding to the (110) and (200) crystal planes; the diffraction peaks of eicosane (EI) are at 2θ = 10.3°, 13.7°, 17.3°, 19.6°, 20.8°, 23.0, 24.3°, 35.0°, and 44.3°, etc. Since the peak intensities of rGO and ANF are weak and are masked by the strong diffraction peaks of eicosane after mixing, the diffraction peaks of the composite aerogels prepared in Examples 1-3 and Comparative Examples 1-6 are basically unchanged.

[0072] 2. Pore structure and pore size determination:

[0073] Figure 2 The ad in the figure are scanning electron microscope images of the composite aerogel materials prepared in Comparative Example 2, Example 2, Example 1 and Comparative Example 3, respectively. It can be seen that the ultrasonic time has a significant effect on the structure of the aerogel material. When the ultrasonic time is 2h ( Figure 2 a), the pore size is larger and uneven; when the ultrasonic time reaches 8h ( Figure 2 In d), the pore size is smaller and more uniform.

[0074] By Nano Measurer TM The average pore diameters of the aerogels of Examples 1 to 3 and Comparative Examples 1 to 5 were measured, as shown in Table 1.

[0075] Table 1 Average pore size of aerogels in Examples 1 to 3 and Comparative Examples 1 to 5

[0076] Number Average pore diameter (μm) Number Average pore diameter (μm) Example 1 2.8 Comparative Example 2 12.9 Example 2 4.5 Comparative Example 3 1.8 Example 3 2.7 Comparative Example 4 2.2 Comparative Example 1 4.0 Comparative Example 5 3.2

[0077] 3. Determination of mechanical properties and thermal conductivity:

[0078] The compressive strength of the aerogels of Examples 1 to 3 and Comparative Examples 1 to 5 was measured by a universal testing machine, and the thermal conductivity of the aerogels of Examples 1 to 3 and Comparative Examples 1 to 5 was measured by a thermal conductivity tester. The results are shown in Table 2.

[0079] Table 2 Mechanical properties and thermal conductivity of aerogels of Examples 1 to 3 and Comparative Examples 1 to 6

[0080]

[0081] 4. Heated cigarette smoking simulation:

[0082] Accurately weigh 20 mg of the smoke cooling composite aerogel rGO@ANFs@EI of Examples 1 to 3 and the aerogel of Comparative Examples 1 to 6, and add them to the cooling section of the heated cigarette. The NHI600 cigarette utensil adaptability experimental device was used to measure the smoke temperature of the cigarette. A linear smoking machine was used to collect the smoke of the heated cigarette on the Cambridge filter. The collection procedure of the smoking machine was: bell-shaped puff curve, puff capacity 55 mL, puff time 2 s, puff interval 30 s, puff number 8, trigger number 3 times, trigger time 0.2 s, trigger interval 0.2 s; the resistance to draw was measured using a comprehensive test bench. The test results are shown in Table 3.

[0083] Table 3 Smoke temperature and draw resistance of composite aerogel cigarettes of Examples 1 to 3 and Comparative Examples 1 to 6

[0084]

[0085] Note: *No aerogel means no aerogel is added during the temperature reduction stage, and the same applies hereinafter.

[0086] For the heated tobacco products filled with rGO@ANFs@EI composite aerogel, first of all, as the mechanical dissociation time prolongs, the flue gas temperature gradually decreases, while the draw resistance of the heated tobacco products gradually increases; furthermore, when the addition amount of eicosane is excessive, although the reduction of the flue gas temperature is achieved, the draw resistance is very high; finally, the addition of aramid fibers can enhance the strength of the composite aerogel, which can ensure the stability of the pore structure of the composite aerogel to a certain extent. When added in an appropriate amount, the draw resistance is relatively low, but when no aramid fibers are added or added in an excessive amount, it will seriously affect the draw resistance. When added in an excessive amount, it will also lead to poor thermal conductivity of the composite aerogel, resulting in poor temperature reduction effect. As can be seen from Table 1, the cigarette sticks containing the composite aerogel of the examples have relatively low flue gas temperature and draw resistance.

[0087] 5. Evaluation of puffing of heated tobacco products:

[0088] Accurately weigh 20 mg of the flue gas temperature reduction composite aerogel rGO@ANFs@EI of Examples 1 to 3 and the aerogel of Comparative Examples 1 to 6, and add them to the temperature reduction stage of the heated tobacco products. Place the obtained heated tobacco products in a constant temperature and humidity box at a temperature of 22 ± 1 °C and a relative humidity of 60 ± 3% for 48 h of equilibration. Organize a panel of 7 professional personnel to conduct sensory evaluation of the above-mentioned heated tobacco products according to the cigarette sensory evaluation standard of GB / T 5604.4-2005. The results are shown in Table 4.

[0089] Table 4 Evaluation of the heated tobacco products of Examples 1 to 3 and Comparative Examples 1 to 6

[0090]

[0091]

[0092] As can be seen from Table 4, the cigarette sticks filled with the composite aerogel of the examples show the highest scores, all higher than 90, belonging to high-quality products, indicating that the composite aerogel of the present invention can not only effectively reduce the flue gas temperature but also further play the role of balancing the flue gas.

[0093] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a composite aerogel for cooling smoke for heating cigarettes, characterized in that: The steps include: Ultrasonic exfoliation and dispersion of graphene oxide and aramid fiber in water to obtain graphene oxide / aramid nanofiber dispersion; Ascorbic acid is added to the graphene oxide / aramid nanofiber dispersion, and then heated for reduction, and after standing, a reduced graphene oxide / aramid nanofiber hydrogel is obtained; after freeze drying, a reduced graphene oxide / aramid nanofiber aerogel is obtained; The reduced graphene oxide / aramid nanofiber aerogel is mixed with eicosane under heating conditions, allowed to stand at a constant temperature, and then cooled to obtain the aerogel.

2. The preparation method according to claim 1, characterized in that In the step of ultrasonically exfoliating and dispersing graphite oxide and aramid fiber in water, the amount ratio of graphite oxide, aramid fiber and water is 30 mg: (5-20) mg: (10-30) mL; the mass ratio of the graphite oxide to ascorbic acid is 3: (15-25).

3. The preparation method according to claim 1, characterized in that: The preparation method of the graphite oxide is as follows: graphite is treated with concentrated sulfuric acid and potassium permanganate in sequence, then reacted in a hydrogen peroxide aqueous solution, and washed to neutrality to obtain the graphite oxide.

4. The preparation method according to claim 1, characterized in that: In the ultrasonic stripping and dispersing step, the ultrasonic power is 200 to 300 W, and the ultrasonic time is 2 to 8 hours.

5. The preparation method according to claim 1, characterized in that: The temperature of the heating reduction is 40-60° C., and the time of the heating reduction is 36-48 hours.

6. The preparation method according to claim 1, characterized in that: After the step of obtaining the reduced graphene oxide / aramid nanofiber hydrogel, the method further includes a dialysis step.

7. The preparation method according to claim 1, characterized in that: The mass ratio of the reduced graphene oxide / aramid nanofiber aerogel to eicosane is 1:(5-12).

8. The preparation method according to claim 1, characterized in that: In the step of mixing the reduced graphene oxide / aramid nanofiber aerogel with eicosane under heating conditions and standing at a constant temperature, the heating conditions are 70 to 90° C. and the constant temperature standing time is 1 to 2 hours.

9. The smoke cooling composite aerogel for heating cigarettes prepared by the preparation method according to any one of claims 1 to 8.

10. The use of the smoke cooling composite aerogel for heating cigarettes as claimed in claim 9, characterized in that: The application is to add the smoke cooling composite aerogel for heated cigarettes into the cooling section of the heated cigarettes.

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