A gel for a cigarette filter and a method for preparing the same

Abstract

The present application relates to the technical field of material preparation, and discloses a gel for cigarette filter and a preparation method thereof.The gel for cigarette filter is a core-shell structure with hybrid aerogel particles as the core, a composite gel layer wrapped outside the core, and essence microcapsules loaded in the core and the composite gel layer, wherein the hybrid aerogel is based on nanocellulose as a matrix and nanosilica as a loading material, the composite gel layer is an N-hydroxymethyl acrylamide / gelatin / methyl cellulose composite, and the essence microcapsules are based on liquid essence as a capsule core and modified cyclodextrin as a capsule skin.The gel for cigarette filter can reduce the influence on the pressure drop of the cigarette filter rod to a certain extent under the condition of the same flavoring effect, thereby ensuring the smoking experience of the cigarette.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, and in particular to a gel for cigarette filters and its preparation method. Background Technology

[0002] As people's living standards continue to improve, their demands for innovation in cigarette products are also increasing. In recent years, the variety of tobacco products has become increasingly rich, and the demand for functional filters has become more standardized. To improve the smoking quality of tobacco products, flavoring is usually added to tobacco leaves or cigarette materials to enhance aroma and quality. Currently, cigarette flavoring mainly includes two methods: flavoring during combustion and flavoring during retention. Flavoring during combustion mainly involves adding flavoring to the tobacco leaves in the cigarette blend or coating the cigarette paper. This enhances aroma or improves the smoking quality of cigarettes by participating in the combustion process and is suitable for non-volatile flavorings or fragrances. Flavoring during retention of the filter mainly involves adding flavoring particles, flavoring threads, flavor capsules, and flavoring to the forming paper coating in the filter section. The flavorings added in this way do not participate in the high-temperature combustion of cigarettes and are suitable for volatile flavorings or fragrances.

[0003] Currently, only flavored filter sticks and flavor capsule filter sticks are widely used by cigarette manufacturers. While flavored filter sticks have the advantage of being able to load different types of flavorings, they also suffer from problems such as low flavor loading capacity, easy loss of aroma components, and unstable flavor enhancement effects. Flavor capsule filter sticks, on the other hand, have the advantages of increasing flavor loading capacity and enhancing flavor retention, but they also have limitations on the flavor loading capacity and higher costs. Gel flavoring, as a new flavoring method, has the advantages of relatively high flavor loading capacity and good sustained-release properties, and therefore, research on it is increasing.

[0004] Existing gel flavoring methods mostly involve applying the gel to cigarette paper or loading it onto the filter rod fiber bundle. In order to ensure the flavor enhancement effect, a relatively large amount of gel is often required. This can cause the gel to clog the gaps between the filter rod fiber bundle, resulting in an increase in the pressure drop of the filter rod and affecting the user's smoking experience. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a gel for cigarette filters and a method for preparing the same, which requires only a smaller amount of gel to achieve the same flavor enhancement effect, thereby reducing the impact on the pressure drop of the cigarette filter rod to a certain extent and thus ensuring the smoking experience of cigarettes.

[0006] The present invention solves the above-mentioned technical problems through the following technical means:

[0007] A gel for cigarette filters, the gel having a core-shell structure with hybrid aerogel particles as the core and a composite gel layer surrounding the core, the core also loading flavor microcapsules, and the composite gel layer loading flavor.

[0008] Furthermore, the hybrid aerogel uses nanocellulose as the matrix and nanosilica as the loading material, and the composite gel layer is an N-hydroxymethylacrylamide / gelatin / methylcellulose composite.

[0009] Furthermore, the flavor microcapsules use liquid flavor as the core and modified cyclodextrin as the capsule shell.

[0010] Furthermore, the preparation method of the flavor microcapsules is as follows: the flavor is stirred and dissolved in anhydrous ethanol to obtain a flavor solution. Modified cyclodextrin is added to deionized water, heated to 60-70℃, and ultrasonically dissolved to obtain a modified cyclodextrin solution. The flavor solution is added dropwise to the modified cyclodextrin solution, the temperature is lowered to 45-50℃, and the reaction is carried out with stirring for 4-6 hours until precipitation occurs. The temperature is then lowered to 30-40℃, and the mixture is kept warm and solidified for 20-24 hours. Finally, the mixture is transferred to a spray dryer for spray drying to obtain flavor microcapsules.

[0011] Furthermore, the inlet air temperature of the spray dryer is 85-90℃, and the outlet air temperature is 40-45℃.

[0012] Furthermore, the preparation method of the modified cyclodextrin is as follows: cyclodextrin is dissolved in N,N-dimethylformamide by stirring, maleic anhydride is added, and under nitrogen protection, the temperature is raised to 80-85℃ and stirred for 10-12 hours. After the reaction is completed, it is cooled to room temperature, chloroform is added to precipitate the solid, which is then filtered. The solid is washed three times each with anhydrous acetone and anhydrous ethanol, and after vacuum drying, it is dispersed in toluene solution. Under nitrogen protection, it is ultrasonically dispersed, and polyethylene glycol monomethyl ether and triethylamine are added. The reaction is carried out at 100-105℃ for 24 hours. After the reaction is completed, it is centrifuged, and the solid is washed three times each with anhydrous toluene and anhydrous ethanol. It is then dialyzed in a dialysis bag for 48 hours. After dialysis is completed, the modified cyclodextrin is obtained by vacuum drying.

[0013] Furthermore, the present invention also discloses a method for preparing the above-mentioned gel for cigarette filters, wherein the method for preparing the gel specifically includes the following steps:

[0014] S1: Add nanofibers to an alkaline mixed solution and stir until completely dissolved. Centrifuge at 1000 r / min to remove air bubbles to obtain a nanocellulose solution. Add nano silica powder to the nanocellulose solution, disperse ultrasonically, heat to 90-95℃, keep warm and stir for 5-8 min, stop heating, continue stirring and cool naturally to 40-50℃, add fragrance microcapsules, disperse ultrasonically, continue stirring and cool to room temperature, let stand for 12 h, soak the product in deionized water for 2-3 days, changing the water every 12 h, take it out and place it in a freeze dryer to dry, crush and sieve to obtain core particles;

[0015] S2: Dissolve N-hydroxymethylacrylamide in a 2 mol / L sodium hydroxide solution, mix well, add gelatin, stir for 20-30 min, add methylcellulose, continue stirring for 10-15 min, add core particles, stir well, then add polyvinyl alcohol, ammonium persulfate, and N,N-methylenebisacrylamide in sequence, and continue stirring for 3-4 h. Soak the reactants in deionized water for 2-3 days, then soak them in fragrance solution for 6-12 h before removing them.

[0016] Furthermore, the alkaline mixed solution is a mixture of sodium hydroxide and urea, wherein the mass ratio of sodium hydroxide to urea is 1:(1.2-1.5).

[0017] Furthermore, the mass ratio of N-hydroxymethylacrylamide, gelatin, and methylcellulose is 1:(0.8-1):(1.5-2).

[0018] The beneficial effects of this invention are:

[0019] 1. The present invention provides a gel for cigarette filters. Structurally, it uses a hybrid aerogel as the core, surrounded by a composite gel layer. The internal hybrid aerogel has a porous structure, is lighter, and can hold more flavor microcapsules compared to hydrogels, thus facilitating flavor release during inhalation. However, the core hybrid aerogel lacks adhesive properties, posing a risk of drifting with the smoke if used directly. Therefore, by surrounding the core with a gel layer, it can adhere to the filter tow, providing a limiting effect. Furthermore, the composite gel layer... The compound also contains flavorings. On the one hand, while maintaining the same flavor enhancement effect, only a smaller amount of gel needs to be added, which can reduce the impact on the pressure drop of the filter rod. On the other hand, in actual application, under the action of smoke, the flavorings in the composite gel layer evaporate first. As the vaping process progresses, the flavoring microcapsules inside the core break down and release the flavorings. This ensures that the flavoring concentration in the smoke remains basically stable throughout the vaping process. Furthermore, different flavorings can be used in the composite gel layer and the core, making the entire vaping process more layered and providing a better experience.

[0020] 2. The present invention provides a gel for cigarette filters. In terms of materials, a hybrid aerogel is prepared by using nanocellulose and nanosilica as raw materials. The raw materials are widely available and environmentally friendly. Nanosilica has good thermal conductivity, which can transfer the heat of the smoke to the flavor microcapsules in a timely manner during the inhalation process. The composite gel layer uses N-hydroxymethylacrylamide, gelatin, and methylcellulose as raw materials, ammonium persulfate as an initiator, and N,N-methylenebisacrylamide as a crosslinking agent. Polyvinyl alcohol is also added to work synergistically with the crosslinking agent N,N-methylenebisacrylamide to promote the formation of secondary micro-crosslinks during the gel formation process, forming a rich network structure and increasing the adhesion between the gel and the filter tow.

[0021] 3. The flavor microcapsules of the present invention use modified cyclodextrin as the capsule shell. By grafting polyethylene glycol monomethyl ether onto the cyclodextrin, the cyclodextrin acquires thermosensitive properties, which ultimately makes the capsule shell thermosensitive. During inhalation, the capsule can rupture in time under the action of smoke to release the flavor. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention discloses a gel for cigarette filters. The gel has a core-shell structure with hybrid aerogel particles as the core and a composite gel layer surrounding the core. The core also contains flavor microcapsules, and the composite gel layer contains flavoring. The hybrid aerogel uses nanocellulose as the matrix and nano-silica as the loading material. The composite gel layer is an N-hydroxymethylacrylamide / gelatin / methylcellulose complex. The flavor microcapsules use liquid flavoring as the core and modified cyclodextrin as the capsule shell. The specific preparation method is as follows:

[0024] Example 1

[0025] Preparation of modified cyclodextrin

[0026] Cyclodextrin was weighed and dissolved in 6 times its mass of N,N-dimethylformamide. Maleic anhydride of equal mass of cyclodextrin was added. The mixture was heated to 80°C under nitrogen protection and stirred for 11 hours. After the reaction was completed, the mixture was cooled to room temperature. Trichloromethane of equal volume to N,N-dimethylformamide was added to precipitate the solid. The solid was filtered and washed three times each with anhydrous acetone and anhydrous ethanol. After vacuum drying at 50°C, the solid was dispersed in toluene solution at a solid-liquid ratio of 15 g / L. After ultrasonic dispersion under nitrogen protection, polyethylene glycol monomethyl ether (PEG) of 1 / 3 mass of cyclodextrin and triethylamine of 0.1 mass of PEG monomethyl ether were added. The mixture was reacted at 105°C for 24 hours. After the reaction was completed, the solid was centrifuged and washed three times each with anhydrous toluene and anhydrous ethanol. The solid was placed in a dialysis bag and dialyzed with deionized water for 48 hours. After dialysis, the solid was vacuum dried to obtain modified cyclodextrin.

[0027] Preparation of flavor microcapsules

[0028] The fragrance was dissolved in anhydrous ethanol by stirring to obtain a 50 wt% fragrance solution. Modified cyclodextrin was added to deionized water at a mass ratio of 1:15 and 10:1. The mixture was heated to 70°C and ultrasonically dissolved to obtain a modified cyclodextrin solution. The fragrance solution was added dropwise to the modified cyclodextrin solution, and the temperature was lowered to 50°C. The mixture was kept warm and stirred for 4 hours until precipitation occurred. The temperature was then lowered to 40°C and kept warm for 20 hours to solidify. The mixture was then transferred to a spray dryer and spray dried at an inlet air temperature of 85°C and an outlet air temperature of 45°C to obtain fragrance microcapsules.

[0029] Preparation of gels for cigarette filters

[0030] S1: Take nanocellulose and add it to an alkaline mixed solution with a mass of 10 times that of nanocellulose. The alkaline mixed solution is a mixed solution obtained by dissolving sodium hydroxide and urea in deionized water. The mass ratio of sodium hydroxide to urea is 1:1.4, and the mass fraction of sodium hydroxide in the alkaline mixed solution is 7%. After stirring until completely dissolved, centrifuge at 1000 r / min to remove air bubbles to obtain a nanocellulose solution. Add 0.2 times the mass of nanocellulose nanosilica powder to the nanocellulose solution, disperse it ultrasonically, heat it to 95℃, keep it at that temperature and stir for 6 min, stop heating, continue stirring and cool it naturally to 50℃, add 1 / 2 times the mass of nanosilica powder fragrance microcapsules, disperse it ultrasonically, continue stirring and cool it to room temperature, let it stand for 12 h, soak the product in deionized water for 2-3 days, changing the water every 12 h, take it out and put it in a freeze dryer to dry, crush it, and sieve it to obtain core particles.

[0031] S2: Dissolve N-hydroxymethylacrylamide in 22 times its mass of a 2 mol / L sodium hydroxide solution. After mixing thoroughly, add gelatin and stir for 20-30 minutes. Then add methylcellulose. The mass ratio of N-hydroxymethylacrylamide, gelatin, and methylcellulose is 1:1:1.5. Continue stirring for 10 minutes. Add 0.5 times its mass of core particles of N-hydroxymethylacrylamide and stir thoroughly. Then add polyvinyl alcohol, ammonium persulfate, and N,N-methylenebisacrylamide in sequence. The mass ratio of N-hydroxymethylacrylamide, polyvinyl alcohol, ammonium persulfate, and N,N-methylenebisacrylamide is 1:0.1:0.1:0.4. Continue stirring and react for 4 hours. Soak the resulting reactant in deionized water for 2-3 days, then soak it in a fragrance solution for 6-12 hours before removing it.

[0032] Example 2

[0033] Preparation of modified cyclodextrin

[0034] Cyclodextrin was weighed and dissolved in 8 times its mass of N,N-dimethylformamide. Maleic anhydride of equal mass of cyclodextrin was added. The mixture was heated to 85°C under nitrogen protection and stirred for 12 hours. After the reaction was completed, the mixture was cooled to room temperature. Trichloromethane of equal volume to N,N-dimethylformamide was added to precipitate the solid. The solid was filtered and washed three times each with anhydrous acetone and anhydrous ethanol. After vacuum drying at 50°C, the solid was dispersed in toluene solution at a solid-liquid ratio of 12 g / L. After ultrasonic dispersion under nitrogen protection, polyethylene glycol monomethyl ether (PEG) of 1 / 3 mass of cyclodextrin and triethylamine of 0.1 mass of PEG monomethyl ether were added. The mixture was reacted at 100°C for 24 hours. After the reaction was completed, the solid was centrifuged and washed three times each with anhydrous toluene and anhydrous ethanol. The solid was placed in a dialysis bag and dialyzed with deionized water for 48 hours. After dialysis, the solid was vacuum dried to obtain modified cyclodextrin.

[0035] Preparation of flavor microcapsules

[0036] The fragrance was dissolved in anhydrous ethanol by stirring to obtain a 45 wt% fragrance solution. Modified cyclodextrin was added to deionized water at a mass ratio of 1:10 and 9:1. The mixture was heated to 60°C and ultrasonically dissolved to obtain a modified cyclodextrin solution. The fragrance solution was added dropwise to the modified cyclodextrin solution, and the temperature was lowered to 45°C. The mixture was kept warm and stirred for 6 hours until precipitation occurred. The temperature was then lowered to 30°C and kept warm for 22 hours to solidify. The mixture was then transferred to a spray dryer and spray dried at an inlet air temperature of 85°C and an outlet air temperature of 40°C to obtain fragrance microcapsules.

[0037] S1: Take nanocellulose and add it to an alkaline mixed solution with a mass of 15 times that of nanocellulose. The alkaline mixed solution is a mixed solution obtained by dissolving sodium hydroxide and urea in deionized water. The mass ratio of sodium hydroxide to urea is 1:1.5, and the mass fraction of sodium hydroxide in the alkaline mixed solution is 6%. After stirring until completely dissolved, centrifuge at 1000 r / min to remove air bubbles to obtain a nanocellulose solution. Add 0.12 times the mass of nanocellulose nanosilica powder to the nanocellulose solution, disperse it by ultrasonication, heat it to 95℃, keep it at that temperature and stir for 5 min, stop heating, continue stirring and cool it naturally to 45℃, add 1 / 2 times the mass of nanosilica powder flavor microcapsules, disperse it by ultrasonication, continue stirring and cool it to room temperature, let it stand for 12 h, soak the product in deionized water for 2-3 days, changing the water every 12 h, take it out and put it in a freeze dryer to dry, crush it, and sieve it to obtain core particles.

[0038] S2: Dissolve N-hydroxymethylacrylamide in 20 times its mass of a 2 mol / L sodium hydroxide solution. After mixing thoroughly, add gelatin and stir for 20-30 minutes. Then add methylcellulose, with a mass ratio of N-hydroxymethylacrylamide, gelatin, and methylcellulose of 1:1:2. Continue stirring for 12 minutes. Add core particles with a mass ratio of 0.3 times that of N-hydroxymethylacrylamide and stir thoroughly. Then add polyvinyl alcohol, ammonium persulfate, and N,N-methylenebisacrylamide in sequence, with a mass ratio of N-hydroxymethylacrylamide, polyvinyl alcohol, ammonium persulfate, and N,N-methylenebisacrylamide of 1:0.1:0.12:0.3. Continue stirring and react for 3 hours. Soak the resulting reactant in deionized water for 2-3 days, then soak it in a fragrance solution for 6-12 hours before removing it.

[0039] Example 3

[0040] Preparation of modified cyclodextrin

[0041] Cyclodextrin was weighed and dissolved in 5 times its mass of N,N-dimethylformamide. Maleic anhydride of equal mass of cyclodextrin was added. The mixture was heated to 85°C under nitrogen protection and stirred for 10 hours. After the reaction was completed, the mixture was cooled to room temperature. Trichloromethane of equal volume to N,N-dimethylformamide was added to precipitate the solid. The precipitate was filtered, and the solid was washed three times each with anhydrous acetone and anhydrous ethanol. After vacuum drying at 50°C, the solid was dispersed in toluene solution at a solid-liquid ratio of 13 g / L. After ultrasonic dispersion under nitrogen protection, polyethylene glycol monomethyl ether (PEG) of 1 / 3 mass of cyclodextrin and triethylamine of 0.1 mass of PEG monomethyl ether were added. The mixture was reacted at 105°C for 24 hours. After the reaction was completed, the solid was centrifuged and washed three times each with anhydrous toluene and anhydrous ethanol. The solid was placed in a dialysis bag and dialyzed with deionized water for 48 hours. After dialysis, the solid was vacuum dried to obtain modified cyclodextrin.

[0042] Preparation of flavor microcapsules

[0043] The fragrance was dissolved in anhydrous ethanol by stirring to obtain a 50 wt% fragrance solution. Modified cyclodextrin was added to deionized water at a mass ratio of 1:12 and 8:1. The mixture was heated to 65°C and ultrasonically dissolved to obtain a modified cyclodextrin solution. The fragrance solution was added dropwise to the modified cyclodextrin solution, and the temperature was lowered to 45°C. The mixture was kept warm and stirred for 5 hours until precipitation occurred. The temperature was then lowered to 30°C and kept warm for 24 hours to solidify. The mixture was then transferred to a spray dryer and spray dried at an inlet air temperature of 90°C and an outlet air temperature of 45°C to obtain fragrance microcapsules.

[0044] S1: Take nanocellulose and add it to an alkaline mixed solution with a mass of 12 times that of nanocellulose. The alkaline mixed solution is a mixed solution obtained by dissolving sodium hydroxide and urea in deionized water. The mass ratio of sodium hydroxide to urea is 1:1.2, and the mass fraction of sodium hydroxide in the alkaline mixed solution is 7%. After stirring until completely dissolved, centrifuge at 1000 r / min to remove air bubbles to obtain a nanocellulose solution. Add 0.15 times the mass of nanocellulose nanosilica powder to the nanocellulose solution, disperse it by ultrasonication, heat it to 90℃, keep it at that temperature and stir for 8 min, stop heating, continue stirring and cool it naturally to 40℃, add 1 / 3 times the mass of nanosilica powder flavor microcapsules, disperse it by ultrasonication, continue stirring and cool it to room temperature, let it stand for 12 h, soak the product in deionized water for 2-3 days, changing the water every 12 h, take it out and put it in a freeze dryer to dry, crush it, and sieve it to obtain core particles.

[0045] S2: Dissolve N-hydroxymethylacrylamide in 25 times its mass of a 2 mol / L sodium hydroxide solution. After mixing thoroughly, add gelatin and stir for 20-30 minutes. Then add methylcellulose. The mass ratio of N-hydroxymethylacrylamide, gelatin, and methylcellulose is 1:0.9:1.8. Continue stirring for 15 minutes. Add 0.4 times its mass of core particles of N-hydroxymethylacrylamide and stir thoroughly. Then add polyvinyl alcohol, ammonium persulfate, and N,N-methylenebisacrylamide in sequence. The mass ratio of N-hydroxymethylacrylamide, polyvinyl alcohol, ammonium persulfate, and N,N-methylenebisacrylamide is 1:0.1:0.11:0.4. Continue stirring and react for 4 hours. Soak the resulting reactant in deionized water for 2-3 days, then soak it in a fragrance solution for 6-12 hours before removing it.

[0046] Comparative Example

[0047] The cigarette filter gel in this comparative example is a conventional flavor-carrying gel, composed of polyethylene glycol as the gelling agent and flavoring. The preparation method is as follows:

[0048] Weigh out polyethylene glycol and add it to a sol container preheated to 65°C. Keep it warm and stir for 20-30 minutes. Add the same fragrance solution as in Example 1 and continue stirring for 10-15 minutes to obtain the fragrance-loaded gel.

[0049] The gels prepared in Examples 1-3 and the comparative example were added to cigarette filter rods to make gel-flavored filter rods. The length of the filter rod was 120 mm and the circumference was 24 mm. The amount of gel added was 1 mg / mm, 2 mg / mm, 3 mg / mm, 4 mg / mm, and 5 mg / mm, respectively. After preparing the samples, the pressure drop of the filter rods was measured. At the same time, the filter rod without gel was used as a blank control. The test results are shown in Table 1.

[0050] Table 1. Pressure drop of filter rod (kPa)

[0051] As can be seen from the data in Table 1, using the gel of the present invention, the impact on the pressure drop of the cigarette filter rod is smaller when the same amount of gel is added.

[0052] The gels prepared in Examples 1-3 and the comparative examples were used to prepare cigarette filter rods at an addition amount of 2 mg / mm. Cigarette samples were then prepared, with cigarettes without added gel serving as a blank control. The evaluation team then conducted sensory evaluations of the prepared cigarette samples according to GB5606.4-2005 "Cigarettes Part 4: Sensory Technical Requirements". The evaluation results are shown in Table 2.

[0053] Table 2 Results of Cigarette Smoking Test

[0054] Sample Pungency Smoke quality Smoke amount Richness Stability Harshness Aftertaste Blank control 8.0 3.5 6.0 3.0 5.0 8.0 3.0 Example 1 3.0 9.0 9.0 8.0 9.0 3.0 5.5 Example 2 3.0 9.0 9.0 8.5 9.0 3.0 5.0 Example 3 3.0 9.0 8.5 8.0 9.0 3.0 6.0 Comparative example 4.0 7.0 7.0 7.5 7.0 4.0 4.0

[0055] As can be seen from the data in Table 2, under the same amount of gel added, the gel of the present invention has a better sensory experience when inhaled. Because the gel of the present application has a greater fragrance carrying capacity and a more uniform release under the same amount of addition, it is significantly superior to existing gels in terms of smoke quality, smoke volume and stability.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A method for preparing a gel for cigarette filters, characterized in that, The gel has a core-shell structure with hybrid aerogel particles as the core and a composite gel layer surrounding the core. The core also contains fragrance microcapsules, and the composite gel layer contains fragrance. The preparation method of the gel specifically includes the following steps: S1: Add nanocellulose to an alkaline mixed solution and stir until completely dissolved. Centrifuge at 1000 r / min to remove air bubbles to obtain a nanocellulose solution. Add nano silica powder to the nanocellulose solution, disperse ultrasonically, heat to 90-95℃, keep warm and stir for 5-8 min, stop heating, continue stirring and cool naturally to 40-50℃, add fragrance microcapsules, disperse ultrasonically, continue stirring and cool to room temperature, let stand for 12 h, soak the product in deionized water for 2-3 days, changing the water every 12 h, take it out and place it in a freeze dryer to dry, crush and sieve to obtain core particles; S2: Dissolve N-hydroxymethylacrylamide in a 2 mol / L sodium hydroxide solution, mix well, add gelatin, stir for 20-30 min, add methylcellulose, continue stirring for 10-15 min, add core particles, stir well, then add polyvinyl alcohol, ammonium persulfate, and N,N-methylenebisacrylamide in sequence, and continue stirring for 3-4 h. Soak the reactants in deionized water for 2-3 days, then soak them in fragrance solution for 6-12 h, and then remove them.

2. The method for preparing a gel for cigarette filters according to claim 1, characterized in that, The hybrid aerogel uses nanocellulose as the matrix and nanosilica as the loading material, and the composite gel layer is an N-hydroxymethylacrylamide / gelatin / methylcellulose complex.

3. The method for preparing a gel for cigarette filters according to claim 2, characterized in that, The flavor microcapsules use liquid flavor as the core and modified cyclodextrin as the capsule shell.

4. A method for preparing a gel for cigarette filters according to any one of claims 1-3, characterized in that, The preparation method of the fragrance microcapsules is as follows: Dissolve the fragrance in anhydrous ethanol by stirring to obtain a fragrance solution. Add the modified cyclodextrin to deionized water, heat to 60-70℃, and dissolve by ultrasonication to obtain a modified cyclodextrin solution. Add the fragrance solution dropwise to the modified cyclodextrin solution, cool to 45-50℃, keep warm and stir for 4-6 hours until precipitation occurs, cool to 30-40℃, keep warm and solidify for 20-24 hours, and transfer to a spray dryer for spray drying to obtain fragrance microcapsules.

5. The method for preparing a gel for cigarette filters according to claim 4, characterized in that, The spray dryer has an inlet air temperature of 85-90℃ and an outlet air temperature of 40-45℃.

6. The method for preparing a gel for cigarette filters according to claim 5, characterized in that, The modified cyclodextrin is prepared as follows: cyclodextrin is dissolved in N,N-dimethylformamide by stirring, maleic anhydride is added, and the mixture is heated to 80-85℃ under nitrogen protection and stirred for 10-12 hours. After the reaction is completed, it is cooled to room temperature, chloroform is added to precipitate the solid, which is then filtered. The solid is washed three times each with anhydrous acetone and anhydrous ethanol, dried under vacuum, and dispersed in toluene solution. Under nitrogen protection, it is ultrasonically dispersed, and polyethylene glycol monomethyl ether and triethylamine are added. The mixture is reacted at 100-105℃ for 24 hours. After the reaction is completed, it is centrifuged, and the solid is washed three times each with anhydrous toluene and anhydrous ethanol. It is then dialyzed in a dialysis bag for 48 hours. After dialysis is completed, the modified cyclodextrin is obtained by vacuum drying.

7. The method for preparing a gel for cigarette filters according to claim 1, characterized in that, The alkaline mixed solution is a mixture of sodium hydroxide and urea, wherein the mass ratio of sodium hydroxide to urea is 1:(1.2-1.5).

8. The method for preparing a gel for cigarette filters according to claim 7, characterized in that, The mass ratio of N-hydroxymethylacrylamide, gelatin, and methylcellulose is 1:(0.8-1):(1.5-2).

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