Ionically conductive tobacco sheet, method for its production and use

Abstract

The application provides an ion conductive tobacco sheet, a preparation method and application thereof, and belongs to the technical field of tobacco sheet for heated cigarettes. The ion conductive tobacco sheet uses conventional auxiliary materials widely used in tobacco sheet production, such as sodium carboxymethyl cellulose and potassium citrate, as ion conductive functional components, constructs an ion conductive network based on the directional migration of sodium ions and potassium ions, and gives the tobacco sheet a new conductive / thermal conductive function. The conductive mechanism of the tobacco sheet is ion conduction, which is fundamentally different from the electronic conduction of the existing technology using carbon-based materials or metal materials as conductive media. The application does not introduce any external conductive fillers such as carbon nanotubes and metal nanowires, the material system is safe and reliable, the ion conduction and moisture retention functions are naturally synergistic, and an electric resistance gradient distribution can be formed along the length direction of the sheet to further improve the energy efficiency. Tests show that the surface resistivity of the tobacco sheet is adjustable between 10 3 ~10 7 Ω / sq.

Description

Technical Field

[0001] This invention belongs to the field of heated cigarette tobacco sheet technology, specifically relating to an ion-conductive tobacco sheet, its preparation method and application, and particularly to an ion-conductive tobacco sheet, its preparation method and its application in reducing the energy consumption of heated cigarette devices. Background Technology

[0002] Currently, heated cigarettes require dedicated electric heating devices, but existing devices generally have high energy consumption and a limited number of uses after a single charge, which restricts the convenience and sustainability of use for consumers.

[0003] To reduce energy consumption and improve heat utilization efficiency, existing technologies mainly adopt the following two strategies:

[0004] Firstly, the thermal conductivity of tobacco sheets can be improved by adding highly thermally conductive fillers, allowing heat to be transferred to the interior of the tobacco more quickly and evenly. For example, carbon-based thermally conductive fillers such as graphene can be incorporated into the coating liquid of tobacco sheets, and the thermal conductivity of the sheets can be improved by using homogenization emulsification technology; or the high thermal and electrical conductivity of carbon nanotubes can be utilized to modify the surface of tobacco sheets by electrostatic spraying technology to enhance their thermal and electrical conductivity; or a slurry method can be used to add binders, tobacco powder, and thermally conductive materials to the tobacco sheet pulp to prepare thermally conductive tobacco sheets.

[0005] Secondly, the tobacco sheet itself can be made conductive to facilitate auxiliary heating. For example, existing technology discloses a conductive tobacco shred, which uses tobacco leaves or tobacco sheets as a substrate, and applies conductive adhesive to the surface through impregnation, spraying, or printing. The conductive material is selected from silver nanowires, copper nanowires, carbon nanotubes, graphene, etc., with a loading of 10~100 mg / m³. 2 The aim is to enable the tobacco to generate its own heat and improve the heat utilization rate.

[0006] However, the above technical solution has the following drawbacks:

[0007] (1) The conductivity mechanism is electronic conductivity. Whether it is carbon-based materials such as graphene and carbon nanotubes, or metallic materials such as silver nanowires and copper nanowires, their conductivity depends on the directional migration of free electrons inside. The dispersion and uniformity of such electronically conductive materials in tobacco sheets are difficult to guarantee, which can easily lead to local uneven conductivity and hot spot concentration problems.

[0008] (2) New substances from non-tobacco systems need to be introduced. Conductive fillers such as carbon nanotubes, silver nanowires, and copper nanowires are not conventional excipients in tobacco sheet production, and their introduction will add an extra burden of safety assessment. The inhalation toxicity of carbon nanotubes has long been a concern in academia, and the safety of metal nanowires also lacks sufficient evidence, thus increasing the difficulty for such technologies to pass regulatory approval.

[0009] (3) The addition of conductive fillers may affect the processing performance and sensory quality of tobacco sheets. High amounts of inorganic conductive fillers will reduce the flexibility and tensile strength of the sheets, which is not conducive to subsequent shredding and rolling processes; at the same time, the fillers themselves or their pyrolysis products may bring off-flavors and interfere with the natural aroma of tobacco.

[0010] (4) Existing solutions mostly focus on conductivity, while neglecting the synergistic effect with moisture retention. During storage and use, heated cigarettes are prone to drying out of the tobacco sheets. Moisture loss leads to a decrease in aerosol release, further affecting the user experience.

[0011] In summary, existing technologies still struggle to balance conductivity uniformity, safety, processability, and moisture retention requirements, necessitating the exploration of more comprehensive solutions. Summary of the Invention

[0012] In view of this, the purpose of this invention is to provide an ion-conductive tobacco sheet, its preparation method, and its application. This invention develops a tobacco sheet technology solution that does not rely on external electronic conductive fillers, makes full use of existing commonly used tobacco sheet excipients, and has both conductive and moisturizing functions.

[0013] To achieve this objective, the present invention adopts the following technical solution:

[0014] In a first aspect, the present invention provides an ion-conductive tobacco sheet, comprising a tobacco substrate and an ion-conductive functional component loaded on the tobacco substrate. The ion-conductive functional component comprises at least one ionizable alkali metal salt and at least one ionic polymeric material; the ionizable alkali metal salt and the ionic polymeric material form an ion-conductive network in the tobacco substrate.

[0015] Preferably, the ionizable alkali metal salt is selected from potassium citrate and / or potassium chloride.

[0016] Preferably, the ionic polymer material is selected from sodium carboxymethyl cellulose and / or sodium alginate.

[0017] Preferably, the content of the ionic polymer material is 8-25% of the total mass of the tobacco sheet.

[0018] Preferably, the content of the ionizable alkali metal salt is 3-12% of the total mass of the tobacco sheet.

[0019] Preferably, the degree of substitution of the sodium carboxymethyl cellulose is 0.7 to 1.2.

[0020] Preferably, the tobacco substrate comprises tobacco raw material and added fibers.

[0021] Preferably, the tobacco raw material is selected from at least one of tobacco powder, tobacco stem powder or tobacco dust, and the mass content of the tobacco raw material in the tobacco sheet is 50-80%.

[0022] Preferably, the added fiber is selected from at least one of wood pulp fiber, hemp pulp fiber or cotton pulp fiber, and the added fiber has a mass content of 5-25% in the tobacco sheet.

[0023] Preferably, the tobacco substrate is also loaded with an atomizing agent.

[0024] Preferably, the atomizing agent is selected from propylene glycol and / or glycerol; the content of the atomizing agent is 10-30% of the total mass of the tobacco sheet.

[0025] Preferably, the room temperature surface resistivity of the ion-conductive tobacco sheet is 10⁻⁶. 3 ~10 7 Ω / sq.

[0026] Secondly, the present invention provides a method for preparing the above-mentioned ion-conductive tobacco sheet, comprising the following steps:

[0027] S1: Provides the slurry for tobacco substrate;

[0028] S2: The slurry of tobacco substrate, ionizable alkali metal salt and ionic polymer material are mixed evenly and then formed to obtain ion-conductive tobacco sheet.

[0029] Preferably, the preparation method further includes step S3: coating the coating liquid containing the atomizing agent onto the thin film obtained in step S2 and drying it.

[0030] Thirdly, the present invention provides a heated cigarette, including the ion-conductive tobacco sheet involved in the above-mentioned technical solution.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention provides an ion-conductive tobacco sheet. The tobacco sheet uses conventional excipients widely used in tobacco sheet production, such as sodium carboxymethyl cellulose (CMC-Na) and potassium citrate, as ion-conductive functional components to construct an ion-conductive network based on the directional migration of sodium ions (Na⁺) and potassium ions (K⁺), endowing the tobacco sheet with novel electrical and thermal conductivity. The conductivity mechanism of this tobacco sheet is ion-conduction, fundamentally different from the electronic conductivity of existing technologies that use carbon-based or metallic materials as conductive media. This invention does not introduce any external conductive fillers such as carbon nanotubes or metal nanowires, ensuring a safe and reliable material system. Furthermore, the ion-conduction and moisturizing functions are naturally synergistic, and a resistance gradient distribution can be formed along the length of the sheet to further improve energy efficiency.

[0033] Tests showed that the surface resistivity of the tobacco sheet was 10. 3 ~10 7 Adjustable between Ω and sq. Detailed Implementation

[0034] The technical solution 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.

[0035] In a first aspect, the present invention provides an ion-conductive tobacco sheet, comprising a tobacco substrate and an ion-conductive functional component loaded on the tobacco substrate.

[0036] In this invention, the ion-conductive functional component comprises at least one ionizable alkali metal salt and at least one ionic polymer material; the ionizable alkali metal salt and the ionic polymer material form an ion-conductive network in the tobacco substrate; the conductivity mechanism of the ion-conductive tobacco sheet is ion conductivity, that is, conductivity is achieved through the directional migration of alkali metal cations in the tobacco substrate matrix.

[0037] Ionic polymers, such as CMC-Na, form the main body and structural framework for the ionic conductive network. If the content is too low, the conductive network will be discontinuous; if the content is too high, it acts as a strong hygroscopic agent, causing the flakes to quickly absorb large amounts of moisture from the air and become sticky. Ionizable alkali metal salts, such as potassium citrate, play a dual role: they are both auxiliary conductive ion sources and functional additives. If the content is too low, the improvement in conductivity is not significant; if the content is too high, it may interfere with the formation of the conductive network and damage its own conductive network.

[0038] Therefore, in some preferred embodiments of the present invention, the content of the ionic polymeric material is 8-25% of the total mass of the tobacco sheet, such as 8%, 10%, 12%, 15%, 18%, 20%, 22%, or 25%. The content of the ionizable alkali metal salt is 3-12% of the total mass of the tobacco sheet, such as 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, or 12%.

[0039] Specifically, in some embodiments of the present invention, the ionizable alkali metal salt is selected from potassium citrate and / or potassium chloride, preferably potassium citrate.

[0040] In some embodiments of the present invention, the ionic polymer material is selected from sodium carboxymethyl cellulose and / or sodium alginate, preferably sodium carboxymethyl cellulose. For sodium carboxymethyl cellulose, if the degree of substitution is too low, the ionic conductivity and water solubility of the CMC-Na molecule will significantly decrease. When the substitution is too high, the hydrophilicity of CMC-Na will be too strong, leading to problems such as uncontrolled hygroscopicity and deterioration of process operability. Therefore, the present invention optimizes the degree of substitution of the sodium carboxymethyl cellulose to be 0.7~1.2, such as 0.7, 0.8, 0.9, 1.0, 1.1, or 1.2.

[0041] In some embodiments of the present invention, the tobacco substrate comprises tobacco raw material and added fibers. The tobacco raw material is selected from at least one of tobacco powder, tobacco stem powder, or tobacco dust, and the mass content of the tobacco raw material in the tobacco sheet is 50-80%, such as 50%, 55%, 60%, 65%, 70%, 75%, or 80%, etc.; the added fibers are selected from at least one of wood pulp fiber, hemp pulp fiber, or cotton pulp fiber, and the mass content of the added fibers in the tobacco sheet is 5-25%, such as 5%, 10%, 15%, 20%, or 25%, etc.

[0042] In some preferred embodiments of the present invention, the tobacco substrate is further loaded with an atomizing agent. The atomizing agent is selected from propylene glycol and / or glycerol; the content of the atomizing agent is 10-30% of the total mass of the tobacco sheet, such as 10%, 15%, 20%, 25%, or 30%.

[0043] The present invention also provides a method for preparing the above-mentioned ion-conductive tobacco sheet, comprising the following steps:

[0044] S1: Provides the slurry for tobacco substrate;

[0045] S2: The slurry of tobacco substrate, ionizable alkali metal salt and ionic polymer material are mixed evenly and then formed to obtain ion-conductive tobacco sheet.

[0046] Specifically, step S1 involves mixing tobacco raw materials and added fibers in a certain proportion, and adding water to prepare a slurry with a concentration of 3-8 wt%, preferably 4-6 wt%, of tobacco substrate.

[0047] Then, according to the present invention, the slurry of tobacco substrate, ionizable alkali metal salt and ionic polymer material are mixed evenly and then formed to obtain ion-conductive tobacco sheet.

[0048] In some embodiments of the present invention, sodium carboxymethyl cellulose and potassium citrate are preferably added to the slurry of the tobacco substrate obtained in step S1 and stirred evenly; the amount of sodium carboxymethyl cellulose added is 8-25% of the total mass of solids in the tobacco slurry, and the amount of potassium citrate added is 3-12% of the total mass of solids in the tobacco slurry. Then, the obtained slurry is formed by papermaking or thick slurry forming to obtain tobacco substrate, with the basis weight controlled at 60-150 g / m³. 2 Preferably 90~120 g / m 2 .

[0049] In some preferred embodiments of the present invention, the preparation method further includes step S3: coating the coating liquid containing the atomizing agent onto the sheet obtained in step S2, and drying it. The drying is preferably performed to a moisture content of 8-15%, such as 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%.

[0050] Testing showed that the room temperature surface resistivity of the ion-conductive tobacco sheet provided by this invention is 10⁻⁶. 3 ~10 7 Ω / sq.

[0051] Finally, the present invention also provides an application of the above-mentioned ion-conductive tobacco sheet in reducing the energy consumption of heated cigarette devices.

[0052] Based on this, the present invention also provides a heated cigarette, which includes the ion-conductive tobacco sheet involved in the above technical solution.

[0053] In some embodiments of the present invention, the heated cigarette includes a filter section, a hollow section, and a tobacco section, wherein the tobacco section contains the ion-conductive tobacco sheet involved in the above-mentioned technical solution.

[0054] This invention does not impose any special restrictions on the filter section and the hollow section; they can be designed according to the technical content known to those skilled in the art.

[0055] To further illustrate the present invention, the following embodiments provide a detailed description. Unless otherwise specified, all experimental materials used in the following embodiments of the present invention are commercially available products.

[0056] Example 1

[0057] The tobacco sheet formulation consists of 65% tobacco powder, 12% wood pulp fiber, 15% CMC-Na (degree of substitution DS=0.9), and 8% potassium citrate. The coating solution comprises 12% glycerin and 8% propylene glycol, resulting in a total atomizing agent content of 15% of the tobacco sheet's mass after coating.

[0058] The preparation method is as follows:

[0059] S1. Mix tobacco powder (200 mesh), added wood pulp fiber (beating degree 25°SR) and water to prepare a tobacco pulp with a concentration of 5 wt%.

[0060] S2. Add CMC-Na powder (DS=0.9, the amount added is 15% of the solid mass of the pulp) and potassium citrate (the amount added is 8% of the solid mass of the pulp) to the tobacco pulp, and mechanically stir for 30 minutes to ensure that CMC-Na is fully dissolved and uniformly dispersed to form a uniform ion-conductive pulp.

[0061] S3. The ion-conductive slurry is formed using an inclined wire paper machine, with the basis weight controlled at 100 g / m². 2 Tobacco substrate was obtained.

[0062] S4. The atomizing agent, namely glycerin and propylene glycol, is mixed evenly and then coated onto the substrate obtained in step S3. The amount of atomizing agent added is 15% based on the mass of the tobacco concentrate. The mixture is dried at 100°C until the moisture content reaches 12%, thus obtaining the ion-conductive tobacco sheet.

[0063] Example 2

[0064] Compared with Example 1, the only difference is the composition of the tobacco sheet formulation: 68% tobacco powder, 15% added wood pulp fiber, 12% CMC-Na (degree of substitution DS=0.9) content, and 5% potassium citrate content. The remaining parameters and steps are consistent with Example 1.

[0065] Example 3

[0066] Compared with Example 1, the only difference is that the degree of substitution (DS) of CMC-Na is adjusted to 1.2, the content remains at 15%, and the potassium citrate content is 8%. All other parameters and steps are the same as in Example 1.

[0067] Comparative Example 1

[0068] Conventional tobacco sheets were prepared using the same process as in Example 1. Specifically, compared to Example 1, the only difference was that the CMC-Na content in the tobacco sheet formulation was 3%, and the potassium citrate content was 0.5%, while the remaining parameters and steps remained the same as in Example 1.

[0069] Comparative Example 2

[0070] Compared with Example 1, the only difference is that the CMC-Na content in the tobacco sheet formulation is 35% and the potassium citrate content is 8%, while the other parameters and steps are the same as in Example 1.

[0071] Comparative Example 3

[0072] Compared with Example 1, the only difference is that the CMC-Na content in the tobacco sheet formulation is 15% and the potassium citrate content is 20%, while the other parameters and steps are the same as in Example 1.

[0073] Performance testing

[0074] (1) The surface resistivity and tensile strength of the sheets prepared in Examples 1-3 and Comparative Examples 1-3 were measured at room temperature. The results are shown in Table 1. The results show that the sheets prepared in Examples 1-3 have high tensile strength, meeting processing requirements, and their surface resistivity is low, indicating that the ion-conducting network was successfully constructed and effectively operated within the tobacco sheet, thereby improving heat utilization efficiency. For Comparative Example 1, which is a conventional tobacco sheet, the lower content of CMC-Na and potassium citrate resulted in a lower conductive network in the sheet, leading to higher surface resistivity. For Comparative Example 2, the higher content of CMC-Na made the conductive network denser, further reducing surface resistivity. However, uncontrolled moisture absorption caused the sheet structure to be completely destroyed, resulting in a sharp decrease in tensile strength and loss of processing feasibility. For Comparative Example 3, the higher content of potassium citrate disrupted the continuity of the CMC-Na network skeleton, increasing surface resistivity.

[0075] Table 1

[0076]

[0077] (2) The tobacco sheets prepared in Examples 1-3 and Comparative Examples 1-3 were used for cigarette rolling. After rolling, the preheating time of the cigarettes and the number of cigarettes heated in the smoking device were compared and analyzed. The results are shown in Table 2. It can be seen from the results that the sheet of Comparative Example 2 has low tensile strength and is prone to breakage during production, so it cannot be used to roll cigarettes. In addition, the results show that the preheating time and the number of cigarettes heated in Examples 1-3 are significantly improved compared with Comparative Examples 1 and 3. This also shows that the conductive tobacco sheet can be used as an auxiliary heating element to participate in heating, thereby improving the heat utilization efficiency, shortening the preheating time, and reducing the energy consumption of the smoking device battery.

[0078] Table 2

[0079]

[0080] (3) The aerosol main components of the cigarettes rolled in Examples 1-3, Comparative Examples 1 and 3 were determined, and the results are shown in Table 3. The results show that the contents of the main components nicotine, glycerol, and moisture in the aerosol of the cigarettes prepared in Examples 1-3 were significantly higher than those in Comparative Examples 1 and 3. This indicates that the sheet prepared using the method of this patent has higher heat utilization efficiency, and the sheet is heated more evenly during heating, thus releasing the internal components more fully. These three indicators are also important references for evaluating the performance of heated cigarettes.

[0081] Table 3

[0082]

[0083] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ion-conductive tobacco sheet, comprising a tobacco substrate and an ion-conductive functional component loaded on the tobacco substrate, characterized in that, The ion-conducting functional component comprises at least one ionizable alkali metal salt and at least one ionic polymer material; the ionizable alkali metal salt and the ionic polymer material form an ion-conducting network in the tobacco substrate; The ionizable alkali metal salt is selected from potassium citrate and / or potassium chloride; The ionic polymer material is selected from sodium carboxymethyl cellulose and / or sodium alginate.

2. The ion-conductive tobacco sheet according to claim 1, characterized in that, The content of the ionic polymer material is 8-25% of the total mass of the tobacco sheet; The content of the ionizable alkali metal salt is 3-12% of the total mass of the tobacco sheet.

3. The ion-conductive tobacco sheet according to claim 1 or 2, characterized in that, The degree of substitution of the sodium carboxymethyl cellulose is 0.7 to 1.

2.

4. The ion-conductive tobacco sheet according to any one of claims 1 to 3, characterized in that, The tobacco substrate includes tobacco raw materials and added fibers; The tobacco raw material is selected from at least one of tobacco powder, tobacco stem powder, or tobacco dust, and the tobacco raw material accounts for 50-80% of the mass content of the tobacco sheet. The added fiber is selected from at least one of wood pulp fiber, hemp pulp fiber or cotton pulp fiber, and the added fiber has a mass content of 5-25% in the tobacco sheet.

5. The ion-conductive tobacco sheet according to any one of claims 1 to 4, characterized in that, The tobacco substrate is also loaded with an atomizing agent.

6. The ion-conductive tobacco sheet according to claim 5, characterized in that, The atomizing agent is selected from propylene glycol and / or glycerol; the content of the atomizing agent is 10-30% of the total mass of the tobacco sheet.

7. The ion-conductive tobacco sheet according to any one of claims 1 to 6, characterized in that, The room temperature surface resistivity of the ion-conductive tobacco sheet is 10. 3 ~10 7 Ω / sq.

8. A method for preparing an ion-conductive tobacco sheet as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Provides the slurry for tobacco substrate; S2: The slurry of tobacco substrate, ionizable alkali metal salt and ionic polymer material are mixed evenly and then formed to obtain ion-conductive tobacco sheet.

9. The preparation method according to claim 8, characterized in that, The preparation method further includes step S3: coating the thin film obtained in step S2 with a coating liquid containing atomizing agent and drying it.

10. A heated cigarette, characterized in that, The ion-conductive tobacco sheet includes any one of claims 1 to 7 or the ion-conductive tobacco sheet prepared by the preparation method according to claim 8 or 9.

Images