Preparation method of heating cigarette tobacco sheet with high heat-conducting property as well as product and application of heating cigarette tobacco sheet

Abstract

The invention relates to a preparation method of a heating cigarette tobacco sheet with high thermal conductivity and a product and application thereof, and the preparation method comprises the following steps: dispersing boron nitride nanowires and / or boron nitride nanotubes in water, and carrying out ultrasonic treatment to obtain a boron nitride dispersion liquid; mixing the tobacco raw material subjected to low-temperature plasma treatment with the dispersion liquid, carrying out vacuum stirring treatment, and then unloading vacuum to normal pressure to obtain a tobacco treatment object; mixing the tobacco pulp with an adhesive, an atomizing agent, water and optional flavors and fragrances to obtain tobacco pulp; carrying out roll forming on the tobacco slurry on a tobacco sheet substrate material to form a sheet blank; and then carrying out drying treatment to obtain the product. The tobacco sheet can solve the problems that an existing heat-not-burn cigarette is poor in heat conductivity, uneven in heating, low in smoke release rate and insufficient in fragrance release, and the smoking experience of a user is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of tobacco products, and relates to a method for preparing heated cigarette tobacco sheets, a product thereof, and an application thereof, and in particular to a method for preparing heated cigarette tobacco sheets with high thermal conductivity, a product thereof, and an application thereof. Background Art

[0002] Heat-not-burn (HNB) cigarettes generate smoke by heating reconstituted tobacco. The smoke is primarily derived from atomized glycerin / propylene glycol and flavors. Because the heating temperature is below 500°C, far lower than that of traditional cigarettes, the smoke contains significantly fewer harmful chemicals and biotoxicity than traditional tobacco.

[0003] However, existing heat-not-burn cigarettes present numerous challenges. The low thermal conductivity of the smoke-generating substrate, coupled with limitations such as the area of the heating components, hinders heat transfer and uneven heating of the tobacco core, leading to slow smoke release and insufficient flavor release, negatively impacting the sensory quality of the cigarette. Therefore, improving the thermal conductivity of the smoke-generating substrate is crucial.

[0004] Prior art solutions use thermally conductive additives (such as boron nitride and aluminum oxide). For example, patent CN112352997A discloses an optimized roller-pressed heat-not-burn tobacco preparation method. This method uses a thermally conductive additive consisting of at least one of silicon carbide powder, boron nitride powder, aluminum oxide powder, and magnesium oxide powder, enabling rapid heat transfer to the interior of the heat-not-burn tobacco. However, these methods utilize conventional boron nitride and aluminum oxide powders, which are limited in thermal conductivity by particle size and morphology, and thus fail to fully utilize the high thermal conductivity potential of boron nitride and aluminum oxide. Furthermore, these thermally conductive additives are often applied as a surface coating of mixed powders, which can lead to uneven distribution and localized overheating, and the coating process is complex.

[0005] Therefore, attention should be paid to how to solve the problems of poor thermal conductivity and uneven heating of existing heat-not-burn cigarettes, which lead to slow smoke release rate and insufficient flavor release, and improve the smoking experience. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing heated cigarette tobacco sheets, a product thereof, and applications thereof. Specifically, it aims to provide a method for preparing heated cigarette tobacco sheets with high thermal conductivity, a product thereof, and applications thereof. This tobacco sheet can address the problems of existing heat-not-burn cigarettes, such as poor thermal conductivity, uneven heating, slow smoke release, and insufficient flavor release, thereby enhancing the user's smoking experience.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a tobacco sheet for heating cigarettes with high thermal conductivity, the method comprising the following steps:

[0009] (1) dispersing boron nitride nanowires and / or boron nitride nanotubes in water and performing ultrasonic treatment to obtain a boron nitride dispersion;

[0010] (2) mixing the tobacco raw material treated with low-temperature plasma with the dispersion obtained in step (1), performing vacuum stirring treatment, and then releasing the vacuum to normal pressure to obtain a processed tobacco material; and then mixing with an adhesive, an atomizer, water, and optional flavors and fragrances to obtain a tobacco slurry;

[0011] (3) Roll-forming the tobacco slurry obtained in step (2) on a tobacco sheet base material to form a sheet embryo; and then performing a drying process to obtain the high thermal conductivity heated cigarette tobacco sheet.

[0012] The preparation method adopted by the present invention is to use boron nitride nanowires (or nanotubes) as a thermal conductive agent, and utilize its long thread structure to construct an efficient thermal conductive network, which significantly enhances the heat conduction path; secondly, the boron nitride nanowires (or nanotubes) are ultrasonically pre-dispersed before use to avoid the agglomeration of the nanowires and achieve uniform dispersion of the boron nitride nanowires (or nanotubes) in the tobacco matrix, which is more beneficial to the improvement of thermal conductivity; thirdly, the tobacco raw material is subjected to low-temperature plasma pre-activation treatment, and vacuum stirring treatment is first performed during the composite process with the boron nitride nanowires (or nanotubes), which can enhance the full infiltration of the boron nitride nanowires (or nanotubes) and tobacco fibers, making it easier to embed into the porous structure of the tobacco fibers. When the stirring environment is restored to normal pressure, the boron nitride nanowires (or nanotubes) are firmly embedded in the tobacco fibers, ensuring that the thermal conductive network is continuous and uniform, improving heat transfer efficiency, and also contributing to the stability of heated cigarette tobacco sheets. Finally, it is applied to tobacco products, making the heating of tobacco products more balanced, conducive to the stable release of smoke volume and flavor components, and improving the smoking experience.

[0013] Preferably, the boron nitride nanowires or boron nitride nanotubes have an aspect ratio of no less than 20, such as 20, 30, 50, 70, 80, 100, 120, 140, 150, 160, 170, 180, and the like. Other specific values within this numerical range are also possible and are not further detailed here. Within this numerical range, increasing the aspect ratio helps enhance the heat conduction path and improve heat transfer efficiency.

[0014] Preferably, the diameter of the boron nitride nanowires or boron nitride nanotubes is independently selected from 10-50 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.; the length is independently selected from 1-20 μm, for example, 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, etc.; other specific point values within this numerical range can be selected, and they will not be repeated here.

[0015] Preferably, a biocompatible dispersant is further added to the boron nitride dispersion.

[0016] Further adding a biocompatible dispersant to the dispersion liquid in conjunction with ultrasonic treatment can improve the dispersion uniformity of boron nitride nanowires (or nanotubes) in the tobacco matrix, which is also more beneficial to improving thermal conductivity.

[0017] Preferably, the biocompatible dispersant includes any one of chitosan, sodium alginate, hyaluronic acid, and polyvinyl pyrrolidone, or a combination of at least two thereof.

[0018] Preferably, the amount of the biocompatible dispersant is 0.5-3% of the total amount of boron nitride nanowires and / or boron nitride nanotubes, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc. Other specific values within this numerical range can be selected and will not be repeated here.

[0019] Preferably, the concentration of the boron nitride nanowires and / or boron nitride nanotubes in water is 0.5-20%, for example, 0.5%, 1%, 3%, 5%, 6%, 8%, 10%, 15%, 20%, etc. Other specific values within this numerical range can be selected and will not be repeated here.

[0020] Preferably, the power of the ultrasonic treatment is 200-500W, for example, 200W, 250W, 300W, 350W, 400W, 450W, 500W, etc.; the time is 10-30min, for example, 10min, 15min, 20min, 25min, 30min, etc.; other specific point values within this numerical range can be selected, and they will not be repeated here.

[0021] Preferably, the ultrasonic treatment is followed by high-speed shearing treatment.

[0022] Preferably, the rotation speed of the high-speed shear treatment is 5000-10000 rpm, for example, 5000 rpm, 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 10000 rpm, etc.; the time is 5-15 min, for example, 5 min, 7 min, 8 min, 10 min, 12 min, 15 min, etc.; other specific point values within this numerical range can be selected, and they will not be repeated here.

[0023] As a more preferred solution, ultrasonic treatment combined with high-speed shearing treatment is used to disperse boron nitride nanowires (or nanotubes) in water. Compared with a single ultrasonic treatment method or a single shearing treatment method with longer time and higher power, it is more beneficial to improving the thermal conductivity of the product.

[0024] Preferably, the tobacco raw material includes 100-200 mesh tobacco powder, such as 100 mesh, 120 mesh, 140 mesh, 150 mesh, 160 mesh, 180 mesh, 200 mesh, etc. Other specific point values within this numerical range can be selected and will not be described here one by one.

[0025] Preferably, the power of the low-temperature plasma treatment is 50-100W, for example, 50W, 60W, 70W, 80W, 90W, 100W, etc.; the gas pressure is 20-30Pa, for example, 20Pa, 22Pa, 25Pa, 28Pa, 30Pa, etc.; the time is 1-3min, for example, 1min, 1.5min, 2min, 2.5min, 3min, etc.; the temperature is 30-60℃, for example, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, etc.; other specific point values within this numerical range can be selected, and they will not be repeated here.

[0026] Preferably, the dispersion in step (2) is 3-15% of the mass of the tobacco raw material, for example, 3%, 5%, 7%, 8%, 10%, 12%, 13%, 14%, 15%, etc. Other specific values within this numerical range can be selected and will not be repeated here.

[0027] Preferably, the temperature of the vacuum stirring treatment is 50-70°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, etc.; the time is 20-40min, for example, 20min, 25min, 30min, 35min, 40min, etc.; other specific point values within this numerical range can be selected, and they will not be repeated here.

[0028] Preferably, in step (2), the mass ratio of the tobacco treated material, adhesive, atomizer and water is (25-50):(0.5-5):(20-40):(5-40).

[0029] Among them, the specific point values in (25-50) can be selected from 25, 28, 30, 35, 40, 45, 50, etc.; the specific point values in (0.5-5) can be selected from 0.5, 1, 2, 2.5, 3, 3.5, 4, 5, etc.; the specific point values in (20-40) can be selected from 20, 22, 24, 25, 26, 27, 28, 30, 33, 37, 40, etc.; the specific point values in (5-40) can be selected from 5, 10, 15, 20, 25, 30, 35, 40, etc.; other specific point values within this numerical range can be selected, and they will not be listed here one by one.

[0030] Preferably, the adhesive comprises any one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, dextrin, modified starch, guar gum, xanthan gum, and sodium alginate, or a combination of at least two thereof.

[0031] Preferably, the aerosol agent comprises glycerol and / or propylene glycol.

[0032] Preferably, the raw material for preparing the tobacco sheet base material is selected from natural long fiber base materials.

[0033] Preferably, the natural long fiber substrate includes any one of cotton fiber, hemp fiber, bamboo fiber or wood pulp fiber, or a combination of at least two of them.

[0034] Preferably, the tobacco sheet base material is further pretreated as follows before rolling:

[0035] The dispersion obtained in step (1) is sprayed or soaked on the surface, and then vacuum dried.

[0036] As a more preferred technical solution, pre-spraying or impregnating the tobacco sheet base material with a boron nitride nanowire (or nanotube) dispersion can further improve the overall thermal conductivity of the sheet.

[0037] Preferably, the surface density of the sheet body prepared in step (3) is in the range of 50-300 g / m 2 , for example 50g / m 2 , 80g / m 2 , 100g / m 2 , 150g / m 2 , 200g / m 2 , 250g / m 2 , 300g / m 2 Etc. Other specific point values within this numerical range can be selected and will not be described here one by one.

[0038] Preferably, the drying treatment in step (3) adopts a gradient drying method, including: first vacuum drying at 40-50°C (for example, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, etc.) for 1-2h (for example, 1h, 1.2h, 1.5h, 1.8h, 2h, etc.), and then heating to 60-80°C (for example, 60°C, 65°C, 70°C, 75°C, 80°C, etc.) for 4-6h (for example, 4h, 4.5h, 5h, 5.5h, 6h, etc. Other specific point values within this numerical range can be selected and will not be repeated here.

[0039] In a second aspect, the present invention provides a tobacco sheet for heating cigarettes with high thermal conductivity, prepared according to the preparation method described in the first aspect.

[0040] In a third aspect, the present invention provides a use of the high thermal conductivity heated cigarette tobacco sheet described in the second aspect in the preparation of tobacco products.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The preparation method adopted by the present invention is to use boron nitride nanowires (or nanotubes) as a thermal conductive agent, and utilize its long thread structure to construct an efficient thermal conductive network, which significantly enhances the heat conduction path; secondly, the boron nitride nanowires (or nanotubes) are ultrasonically pre-dispersed before use to avoid the agglomeration of the nanowires and achieve uniform dispersion of the boron nitride nanowires (or nanotubes) in the tobacco matrix, which is more beneficial to the improvement of thermal conductivity; thirdly, the tobacco raw material is subjected to low-temperature plasma pre-activation treatment, and vacuum stirring treatment is first performed during the composite process with the boron nitride nanowires (or nanotubes), which can enhance the full infiltration of the boron nitride nanowires (or nanotubes) and tobacco fibers, making it easier to embed into the porous structure of the tobacco fibers. When the stirring environment is restored to normal pressure, the boron nitride nanowires (or nanotubes) are firmly embedded in the tobacco fibers, ensuring that the thermal conductive network is continuous and uniform, improving heat transfer efficiency, and also contributing to the stability of heated cigarette tobacco sheets. Finally, it is applied to tobacco products, making the heating of tobacco products more balanced, conducive to the stable release of smoke volume and flavor components, and improving the smoking experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a scanning electron microscope image of the boron nitride nanowires in Example 1 (scale is 1 μm);

[0044] Figure 2 This is a scanning electron microscope image of the boron nitride nanowires in Example 1 (the scale is 50 nm). DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0046] The boron nitride nanowires involved in the following content are all purchased from the Taobao store "Enterprise and School Scientific Research Powder Research Institute" with the model number "boron nitride nanowires"; the boron nitride nanotubes are all purchased from Zhejiang Yamei Nano Technology Co., Ltd. with the model number "boron nitride nanotubes"; the boron nitride powders are all purchased from Shanghai Maclean Biochemical Technology Co., Ltd. with the model number "boron nitride 768557"; the polyvinyl pyrrolidone is all purchased from Shanghai Maclean Biochemical Technology Co., Ltd. with the model number P816205; the carboxymethyl cellulose is all purchased from Shanghai Maclean Biochemical Technology Co., Ltd. with the model number C804618; and the tobacco raw materials are all self-produced raw materials.

[0047] Example 1

[0048] This embodiment provides a tobacco sheet for heating cigarettes with high thermal conductivity, and the preparation method thereof is as follows:

[0049] (1) Boron nitride nanowires with a diameter of 20 nm and a length of 1 μm (aspect ratio 50) were dispersed in deionized water to a final concentration of 10%. Ultrasonic treatment was performed at a power of 400 W for 25 min to obtain a boron nitride dispersion (the scanning electron microscope image of which is shown in FIG). Figure 1 and Figure 2 shown);

[0050] (2) The tobacco raw material was crushed into 100 mesh and subjected to low-temperature plasma treatment at a power of 70 W, a pressure of 25 Pa, a time of 2 min, and a temperature of 50°C;

[0051] (3) mixing the tobacco raw material treated with low-temperature plasma with the dispersion obtained in step (1) (in an amount of 5% of the mass of the tobacco raw material), and subjecting the mixture to a vacuum stirring treatment at 60° C. for 30 minutes, and then releasing the vacuum to normal pressure to obtain a processed tobacco material; and then mixing the mixture with an adhesive (carboxymethyl cellulose), an atomizer (glycerol), water, and a tobacco flavoring in a ratio of 40%:3%:35%:20%:2% to obtain a tobacco slurry;

[0052] (4) The tobacco slurry obtained in step (2) was rolled onto a tobacco sheet substrate (0.1 mm thick long-fiber cotton) to form a sheet body (surface density of 150 g / m 2 ); and then drying, first vacuum drying at 40 ° C for 2h, and then heating to 60 ° C and vacuum drying for 5h to obtain the high thermal conductivity heated cigarette tobacco sheet.

[0053] Example 2

[0054] This embodiment provides a tobacco sheet for heating cigarettes with high thermal conductivity, and the preparation method thereof is as follows:

[0055] (1) Boron nitride nanowires (25 nm in diameter and 1 μm in length, aspect ratio 40) were dispersed in deionized water to a final concentration of 15% and ultrasonically treated at a power of 300 W for 30 min to obtain a boron nitride dispersion;

[0056] (2) The tobacco raw material was crushed into 150 mesh and subjected to low-temperature plasma treatment at a power of 90 W, a pressure of 30 Pa, a time of 1 min, and a temperature of 50°C;

[0057] (3) mixing the tobacco raw material treated with low-temperature plasma with the dispersion obtained in step (1) (in an amount of 5% of the mass of the tobacco raw material), and performing vacuum stirring treatment at a temperature of 70° C. for 20 minutes, and then releasing the vacuum to normal pressure to obtain a tobacco processed material; and then mixing with an adhesive (carboxymethyl cellulose), an atomizer (propylene glycol), water, and a tobacco flavor in a ratio of 45%:4%:30%:19%:2% to obtain a tobacco slurry;

[0058] (4) The tobacco slurry obtained in step (2) was rolled onto a tobacco sheet substrate (0.1 mm thick long-fiber cotton) to form a sheet body (surface density of 150 g / m 2 ); and then drying, first vacuum drying at 50 ° C for 1h, and then heating to 70 ° C and vacuum drying for 4h to obtain the high thermal conductivity heated cigarette tobacco sheet.

[0059] Example 3

[0060] This embodiment provides a tobacco sheet for heating cigarettes with high thermal conductivity, and the preparation method thereof is as follows:

[0061] (1) Boron nitride nanotubes (25 nm in diameter and 1 μm in length, aspect ratio 40) were dispersed in deionized water to a final concentration of 10% and ultrasonically treated at a power of 500 W for 10 min to obtain a boron nitride dispersion;

[0062] (2) The tobacco raw material was crushed into 100 mesh and subjected to low-temperature plasma treatment at a power of 60 W, a pressure of 20 Pa, a time of 3 min, and a temperature of 50°C;

[0063] (3) mixing the tobacco raw material treated with low-temperature plasma with the dispersion obtained in step (1) (in an amount of 5% of the mass of the tobacco raw material), and performing vacuum stirring treatment at a temperature of 50° C. for 40 minutes, and then releasing the vacuum to normal pressure to obtain a tobacco processed material; and then mixing with an adhesive (carboxymethyl cellulose), an atomizer (propylene glycol), water, and a tobacco flavor in a ratio of 45%:2%:30%:21%:2% to obtain a tobacco slurry;

[0064] (4) The tobacco slurry obtained in step (2) was rolled onto a tobacco sheet substrate (0.1 mm thick long-fiber cotton) to form a sheet body (surface density of 150 g / m 2 ); and then drying, first vacuum drying at 40 ° C for 2h, and then heating to 80 ° C and vacuum drying for 4h to obtain the high thermal conductivity heated cigarette tobacco sheet.

[0065] Example 4

[0066] This embodiment provides a high thermal conductivity heated cigarette tobacco sheet, the preparation method of which differs from that of Example 1 only in that: in step (1), boron nitride nanowires are dispersed in a polyvinyl pyrrolidone aqueous solution with a mass concentration of 1.5%, and other conditions remain the same.

[0067] Example 5

[0068] This embodiment provides a high thermal conductivity heated cigarette tobacco sheet. The preparation method thereof differs from that of Example 1 only in that, after the ultrasonic treatment in step (1), a high-speed shear treatment is performed. The speed of the high-speed shear treatment is 8000 rpm and the time is 10 minutes. The power of the ultrasonic treatment is reduced to 200 W and the time is 15 minutes. All other conditions remain the same.

[0069] Example 6

[0070] This embodiment provides a high thermal conductivity tobacco sheet for heating cigarettes. The preparation method thereof differs from that of Example 1 only in that the tobacco sheet base material (0.1 mm thick long-fiber cotton) in step (4) is also pretreated as follows: the dispersion liquid of step (1) is evenly sprayed on its surface (the spraying amount is 20 μL / cm 2 ), vacuum drying, pressure 0.1 MPa. Other conditions remained the same.

[0071] Example 7

[0072] This embodiment provides a high thermal conductivity heated cigarette tobacco sheet, the preparation method of which differs from that of Example 1 only in that the boron nitride nanowires in step (1) have a diameter of 20 nm and a length of 2 μm (aspect ratio of 100). Other conditions remain the same.

[0073] Example 8

[0074] This embodiment provides a high thermal conductivity heated cigarette tobacco sheet, the preparation method of which differs from that of Example 1 only in that the boron nitride nanowires in step (1) have a diameter of 60 nm and a length of 1 μm (aspect ratio less than 20). Other conditions remain the same.

[0075] Example 9

[0076] This embodiment provides a high thermal conductivity heated cigarette tobacco sheet, the preparation method of which differs from that of Example 1 only in that the final concentration of boron nitride nanowires in water in step (1) is 5%, and other conditions remain the same.

[0077] Example 10

[0078] This embodiment provides a high thermal conductivity heated cigarette tobacco sheet. The preparation method thereof differs from that of Example 1 only in that the low-temperature plasma treatment in step (2) is performed at a power of 40 W, a pressure of 25 Pa, a time of 5 minutes, and a temperature of 50° C. Other conditions remain the same.

[0079] Example 11

[0080] This embodiment provides a high thermal conductivity heated cigarette tobacco sheet. The preparation method thereof differs from that of Example 1 only in that the low-temperature plasma treatment in step (2) is performed at a power of 120 W, a pressure of 25 Pa, a time of 1 min, and a temperature of 50° C. Other conditions remain the same.

[0081] Comparative Example 1

[0082] This comparative example provides a heated cigarette tobacco sheet. The preparation method thereof differs from that of Example 1 only in that: Step (1) boron nitride nanowires (aspect ratio 50) with a diameter of 20 nm and a length of 1 μm are dispersed in deionized water to a final concentration of 10%, and subjected to a high-speed shearing treatment at a speed of 8000 rpm for 25 minutes to obtain a boron nitride dispersion. All other conditions remain the same.

[0083] Comparative Example 2

[0084] This comparative example provides a heated cigarette tobacco sheet. The preparation method thereof differs from that of Example 1 only in that the tobacco raw material is not subjected to low-temperature plasma treatment in step (2), and in step (3), the tobacco raw material is pulverized to 100 mesh and then mixed with the dispersion obtained in step (1) (in an amount of 5% by mass of the tobacco raw material). All other conditions remain the same.

[0085] Comparative Example 3

[0086] This comparative example provides a heated cigarette tobacco sheet. The preparation method thereof differs from that of Example 1 only in that the tobacco raw material is not subjected to low-temperature plasma treatment in step (2), and low-temperature plasma treatment is performed after the drying treatment in step (4). The treatment is performed at a power of 70 W, a pressure of 25 Pa, a time of 2 minutes, and a temperature of 50° C. All other conditions remain the same.

[0087] Comparative Example 4

[0088] This comparative example provides a heated cigarette tobacco sheet. The preparation method thereof differs from that of Example 1 only in that, in step (3), the tobacco raw material treated with low-temperature plasma is uniformly mixed with the dispersion obtained in step (1) (in an amount of 5% by mass of the tobacco raw material), and the vacuum stirring followed by release to atmospheric pressure is omitted. All other conditions remain the same.

[0089] Comparative Example 5

[0090] This comparative example provides a heated cigarette tobacco sheet, the preparation method of which differs from that of Example 1 only in that: in step (1), the boron nitride nanowires are not dispersed, and in step (3), the tobacco raw material treated with low-temperature plasma is mixed with the boron nitride nanowires (in the same amount as in Example 1), and other conditions remain the same.

[0091] Comparative Example 6

[0092] This comparative example provides a heated cigarette tobacco sheet, the preparation method of which differs from that of Example 1 only in that the boron nitride nanowires with a diameter of 20 nm and a length of 1 μm are replaced with ordinary boron nitride powder of the same mass (particle size of about 150 μm), while all other conditions remain the same.

[0093] Comparative Example 7

[0094] This comparative example provides a heated cigarette tobacco sheet. The preparation method thereof differs from that of Example 1 only in that no heat-conducting auxiliary agent is used. The preparation method is as follows:

[0095] (1) crushing tobacco raw material into 100 mesh, and then mixing with adhesive (carboxymethyl cellulose), atomizer (glycerol), water and tobacco flavor in a ratio of 50%:3%:25%:20%:2% to obtain tobacco slurry;

[0096] (2) The tobacco slurry obtained in step (1) was rolled onto a tobacco sheet substrate (0.1 mm thick long-fiber cotton) (the loading amount on the substrate was 0.5 mg / cm2 based on dry weight). 2 ) to form a sheet embryo; then drying treatment, first vacuum drying at 40 ° C for 2h, then heating to 60 ° C and vacuum drying for 5h to obtain heated cigarette tobacco sheets.

[0097] Test Example 1

[0098] The thermal conductivity coefficients of the tobacco sheets prepared in Examples 1-11 and Comparative Examples 1-7 were measured using a thermal conductivity constant tester (HotDisk TPS2500S, Sweden). The results are shown in Table 1.

[0099] Table 1

[0100]

[0101] As can be seen from the data results in Table 1, compared with Comparative Examples 2-7, the preparation method involved in the present invention uses boron nitride nanowires (or nanotubes) as a thermal conductive additive, and the boron nitride nanowires (or nanotubes) are ultrasonically pre-dispersed before use. The tobacco raw material is subjected to low-temperature plasma pre-activation treatment, and vacuum stirring treatment is performed during the composite process with the boron nitride nanowires (or nanotubes), so that the thermal conductivity of the heated cigarette tobacco sheet is significantly improved.

[0102] By comparing Example 1 with Example 5 and Comparative Example 1, it can be seen that the use of ultrasound combined with high-speed shearing to disperse boron nitride nanowires (or nanotubes) in water is more beneficial to improving the thermal conductivity of the product compared to a single ultrasonic treatment method or a single shear treatment method with longer time and higher power.

[0103] By comparing Example 1 with Example 4, it can be seen that further adding a biocompatible dispersant to the dispersion liquid in conjunction with ultrasonic treatment can improve the dispersion uniformity of boron nitride nanowires (or nanotubes) in the tobacco matrix, which is also more beneficial to improving thermal conductivity.

[0104] By comparing Example 1 with Example 6, it can be seen that pre-spraying or impregnating the tobacco sheet base material with a boron nitride nanowire (or nanotube) dispersion can further improve the thermal conductivity of the entire sheet.

[0105] By comparing Example 1 with Examples 7-8, it can be seen that the aspect ratio of the boron nitride nanowires (or nanotubes) affects the thermal conductivity of the entire sheet to a certain extent, and an aspect ratio of not less than 20 is a more preferred solution.

[0106] By comparing Example 1 with Example 9, it can be seen that when the concentration of boron nitride nanowires decreases, the thermal conductivity decreases, which means that increasing the boron nitride content helps to improve the thermal conductivity of the sheet.

[0107] By comparing Example 1 with Examples 10-11, it can be seen that the process parameters of the low-temperature plasma treatment also affect the overall thermal conductivity of the wafer to a certain extent.

[0108] Test Example 2

[0109] Heat-not-burn (HNB) cigarette samples were made from tobacco sheets prepared using the same manufacturing process as in Example 1, Examples 4-6, and Comparative Example 7. Sensory evaluations were conducted based on five criteria: aroma, smoke yield, draw uniformity, strength, and aftertaste. Each criterion was scored on a scale of 1-10, with 0.5 being the minimum unit. A higher score indicates better sensory quality. The results are shown in Table 2.

[0110] Table 2

[0111] sample aroma Smoke volume Suction uniformity Momentum Aftertaste Total score Example 1 6.5 7.0 6.5 6.5 6.5 33.0 Example 4 6.5 7.5 7.5 6.0 6.0 33.5 Example 5 7.0 7.5 7.5 5.5 6.0 33.5 Example 6 7.5 8.0 7.5 6.0 6.0 35.0 Comparative Example 7 5.5 5.0 5.0 6.5 7.0 29.0

[0112] As can be seen from the data results in Table 2, the preparation method involved in the present invention helps to improve the thermal conductivity of tobacco sheets, can make heat be transferred to the entire sheet more quickly and evenly, help the entire cigarette core to be heated more evenly, can improve the problem of insufficient release of smoke volume and flavor components, and improve the sensory quality of smoking.

[0113] The applicant declares that the present invention is illustrated by the above-described embodiments, but the present invention is not limited to the above-described embodiments. This does not mean that the present invention must rely on the above-described embodiments in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for raw materials in the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

[0114] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0115] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for preparing tobacco sheets for heating cigarettes with high thermal conductivity, characterized in that: The preparation method comprises the following steps: (1) dispersing boron nitride nanowires and / or boron nitride nanotubes in water and performing ultrasonic treatment to obtain a boron nitride dispersion; (2) mixing the tobacco raw material treated with low-temperature plasma with the dispersion obtained in step (1), performing vacuum stirring treatment, and then releasing the vacuum to normal pressure to obtain a processed tobacco material; and then mixing with an adhesive, an atomizer, water, and optional flavors and fragrances to obtain a tobacco slurry; (3) Roll-forming the tobacco slurry obtained in step (2) on a tobacco sheet base material to form a sheet embryo; and then performing a drying process to obtain the high thermal conductivity heated cigarette tobacco sheet.

2. The preparation method according to claim 1, characterized in that The aspect ratio of the boron nitride nanowires or boron nitride nanotubes is not less than 20; Preferably, the diameter of the boron nitride nanowires or boron nitride nanotubes is independently selected from 10-50 nm, and the length is independently selected from 1-20 μm.

3. The preparation method according to claim 1 or 2, characterized in that A biocompatible dispersant is also added to the boron nitride dispersion; Preferably, the biocompatible dispersant comprises any one of chitosan, sodium alginate, hyaluronic acid, and polyvinyl pyrrolidone, or a combination of at least two thereof; Preferably, the amount of the biocompatible dispersant is 0.5-3% of the total amount of boron nitride nanowires and / or boron nitride nanotubes; Preferably, the concentration of the boron nitride nanowires and / or boron nitride nanotubes in water is 0.5-20%.

4. The preparation method according to any one of claims 1 to 3, characterized in that The power of the ultrasonic treatment is 200-500W, and the time is 10-30min; Preferably, the ultrasonic treatment is followed by a high-speed shearing treatment; Preferably, the rotation speed of the high-speed shearing treatment is 5000-10000 rpm, and the time is 5-15 min.

5. The preparation method according to any one of claims 1 to 4, characterized in that The tobacco raw material includes 100-200 mesh pulverized tobacco; Preferably, the power of the low-temperature plasma treatment is 50-100W, the gas pressure is 20-30Pa, the time is 1-3min, and the temperature is 30-60°C; Preferably, the dispersion in step (2) is 3-15% of the mass of the tobacco raw material; Preferably, the temperature of the vacuum stirring treatment is 50-70° C., and the time is 20-40 minutes.

6. The preparation method according to any one of claims 1 to 5, characterized in that In step (2), the mass ratio of the tobacco treated material, the adhesive, the atomizer and the water is (25-50):(0.5-5):(20-40):(5-40); Preferably, the adhesive comprises any one or a combination of at least two of carboxymethyl cellulose, hydroxypropyl methyl cellulose, dextrin, modified starch, guar gum, xanthan gum, and sodium alginate; Preferably, the aerosol agent comprises glycerol and / or propylene glycol.

7. The preparation method according to any one of claims 1 to 6, characterized in that The raw material for preparing the tobacco sheet base material is selected from natural long fiber base material; Preferably, the natural long fiber substrate comprises any one of cotton fiber, hemp fiber, bamboo fiber or wood pulp fiber, or a combination of at least two thereof; Preferably, the tobacco sheet base material is further pretreated as follows before rolling: The dispersion obtained in step (1) is sprayed or soaked on the surface, and then vacuum dried.

8. The preparation method according to any one of claims 1 to 7, characterized in that The surface density of the sheet body obtained in step (3) is in the range of 50-400 g / m 2 ; Preferably, the drying treatment in step (3) adopts a gradient drying method, including: first vacuum drying at 40-50°C for 1-2 hours, and then heating to 60-80°C and vacuum drying for 4-6 hours.

9. A tobacco sheet for heating cigarettes with high thermal conductivity prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the high thermal conductivity heated cigarette tobacco sheet according to claim 9 in the preparation of tobacco products.

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