Method for regulating and controlling moisture absorption and desorption characteristics and softness of reconstituted tobacco through sodium carboxymethyl cellulose

Abstract

The invention discloses a method for regulating and controlling moisture absorption and desorption characteristics and softness of reconstituted tobacco through sodium carboxymethyl cellulose, which comprises the following steps: mixing sodium carboxymethyl cellulose (CMC-Na) with tobacco stem / tobacco powder mixed slurry in a pulping stage based on a paper-making method reconstituted tobacco production process; or CMC-Na is added in a spraying mode after a reconstituted tobacco substrate is formed and dip-coated with tobacco coating liquid, the pulp fiber form can be actively optimized by regulating and controlling the concentration and the adding proportion of the CMC-Na solution, the pulp retention rate is increased, and meanwhile the moisture absorption and desorption characteristics of reconstituted tobacco and the paper base softness are precisely regulated and controlled. An existing production line does not need to be transformed, operation is easy and convenient, the method is suitable for industrial production, on the premise that the quality stability of the reconstituted tobacco is guaranteed, smoke irritation can be effectively reduced, the oral cavity moist feeling is enhanced, and the physical performance and sensory quality of the reconstituted tobacco are cooperatively improved.

Description

Technical Field

[0001] This invention belongs to the field of reconstituted tobacco paper-based sheets, specifically involving a method for regulating the moisture absorption and desiccation properties and softness of reconstituted tobacco leaves using sodium carboxymethyl cellulose (CMC-Na). Background Technology

[0002] Papermaking tobacco sheets (reconstituted tobacco leaves) are an important product for achieving efficient utilization of tobacco raw materials in the cigarette industry. They are made from waste materials such as tobacco stems and tobacco dust generated during cigarette production, through core processes such as extraction and concentration, pulping and papermaking, coating and flavoring, and high-temperature drying. They have significant application value in the field of tobacco resource recycling.

[0003] Currently, several technical challenges remain to be addressed in the production and quality control of reconstituted tobacco. Firstly, regarding physical properties and processing adaptability, some reconstituted tobacco leaf substrates exhibit poor matching between water absorption and dehydration processes, leading to insufficient softness and poor water retention in the finished sheets. This negatively impacts subsequent shredding efficiency and the quality of finished cigarettes. Additionally, some products suffer from poor color uniformity and insufficient physical toughness, affecting product consistency. Secondly, in terms of intrinsic quality and sensory experience, some reconstituted tobacco leaves exhibit a pronounced woody aroma, insufficient smoke harmony, and a need for improved mouthfeel. Further optimization of sensory quality is required to meet the formulation requirements of cigarette products. Thirdly, the moisture adsorption and desorption process of tobacco is present throughout the entire cigarette production process, including tobacco leaf conditioning, re-drying, fermentation, vacuum rehumidification, leaf moistening and feeding, stem steaming, shredding, leaf storage, and shredding. Precisely controlling the dynamic moisture characteristics of reconstituted tobacco leaves to adapt to the process requirements of each production stage remains a key technical focus and challenge within the industry.

[0004] To address these issues, the industry has explored various technologies. Regarding raw material and fiber optimization, existing technologies introduce waste burlap sacks and other materials as added fiber raw materials, improving raw material utilization while enhancing the physical properties of reconstituted tobacco leaves (CN104223344B). Other technologies partially replace traditional wood pulp, hemp pulp, and other added fibers with natural sepiolite inorganic fibers, reducing the amount of added fibers used while optimizing paper base forming performance (CN107898000A). In the extraction and component regulation stages, related technologies utilize methods such as ion-exchange membrane separation and electrodialysis to selectively regulate components such as anions, heavy metal ions (e.g., Zn, Cu, Cr, Cd), nitrosamines (TSNA), and nitrates in reconstituted tobacco extracts. This aims to reduce the content of harmful components and improve intrinsic quality (CN103082394A, CN104351943B, CN105029670B, CN105124741B, CN105124742B, CN105124743B). Simultaneously, a dynamic gradient pH three-stage countercurrent extraction process is applied to enhance extraction efficiency and the retention rate of effective components (CN107048465B). Regarding quality evaluation and stability control, a batch-to-batch reconstituted tobacco quality stability evaluation method based on thermogravimetric (TG) curves has been established, providing technical support for product consistency management (CN108061691B).

[0005] While existing technologies have made progress in raw material optimization, component regulation, and quality evaluation, there are still technological gaps in the precise control of key performance characteristics. On the one hand, there is limited research on the synergistic regulation of the dynamic moisture absorption and desiccation characteristics of reconstituted tobacco leaves and the softness of the paper base, especially lacking systematic solutions for targeted optimization of such performance through natural, non-toxic additives. On the other hand, existing research on additives mainly focuses on improving single performance characteristics and has not yet formed an integrated technical path that takes into account moisture control, softness enhancement, and sensory quality optimization. Therefore, developing reconstituted tobacco leaf performance regulation methods that are adaptable to industrial production and can precisely control additive application parameters (type, concentration, addition ratio, and process) is of great significance for solving current problems in the physical properties and sensory quality of products and improving the adaptability to production and processing. Summary of the Invention

[0006] To address the current technical problems of mismatch between the moisture absorption and desiccation properties of reconstituted tobacco leaves and processing requirements, insufficient softness of the finished product, poor water retention and moisturizing effects, and the need to improve oral moistness in sensory experience, this invention provides a method for regulating the moisture absorption and desiccation properties and softness of reconstituted tobacco leaves using sodium carboxymethyl cellulose (CMC-Na). Specifically, this method aims to: precisely control the dynamic moisture adsorption-desorption process of reconstituted tobacco leaves by directionally controlling the application method (mixing and homogenizing or secondary spraying) and addition parameters of CMC-Na, thus solving the problem of poor compatibility between water absorption and dehydration in production; optimize the fiber morphology of tobacco pulp by utilizing CMC-Na, reducing the proportion of fine fibers and increasing the average fiber length, thereby improving the physical structure of the reconstituted tobacco leaf base and enhancing the softness and processing compatibility of the finished product; and enhance the water retention and moisturizing effect of reconstituted tobacco leaves by leveraging the natural water-retention properties of CMC-Na, while reducing smoke irritation and optimizing oral moistness, achieving a synergistic improvement in physical properties and sensory quality.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The method for regulating the moisture absorption and desiccation properties and softness of reconstituted tobacco leaves by CMC-Na provided by this invention is based on the papermaking process for reconstituted tobacco leaves. It achieves regulation of the moisture absorption and desiccation properties and softness of reconstituted tobacco leaves through two independent CMC-Na addition processes. The specific scheme is as follows: Option 1: CMC-Na-slurry mixing and homogenization process This process involves mixing CMC-Na with tobacco stem / dust mixture during the pulping stage, and optimizing fiber morphology and CMC-Na dispersion uniformity through multi-stage pulping. The specific steps are as follows: Step 1, raw material grading and grinding: tobacco stems are ground twice in sequence by a primary grinding machine and a secondary grinding machine; tobacco dust is ground once separately by a secondary grinding machine.

[0008] Step 2, Slurry Mixing and CMC-Na Addition: The refined tobacco stem slurry and tobacco dust slurry are pumped from the storage tank to the mixing tank for initial mixing. The resulting tobacco stem / tobacco dust mixed slurry is then pumped to the homogenizer. CMC-Na solution is added to the homogenizer according to a preset ratio. The homogenizer is used to refine the tobacco stem / tobacco dust / CMC-Na mixed slurry three times to ensure that CMC-Na is fully integrated with the slurry, thereby obtaining the tobacco stem / tobacco dust / CMC-Na mixed slurry.

[0009] Step 3, Shaping and Drying: After the tobacco stem / tobacco dust / CMC-Na mixed slurry is formed by mesh fabric, it is successively dehydrated by Yankee cylinder vacuum negative pressure and high temperature to obtain reconstituted tobacco leaf substrate; the reconstituted tobacco leaf substrate is then dipped in tobacco coating liquid and dehydrated again at high temperature to finally obtain finished reconstituted tobacco leaf sheet.

[0010] Option 2: CMC-Na secondary coating process This process involves adding CMC-Na via spraying after the reconstituted tobacco substrate is formed and coated with tobacco coating liquid. The specific steps are as follows: Step 1: Raw Material Pulping and Substrate Forming: Tobacco stems are pulverized twice, first by a primary pulverizer and then by a secondary pulverizer; tobacco dust is pulverized once, separately by a secondary pulverizer. The pulverized tobacco stem slurry and tobacco dust slurry are pumped from storage tanks to mixing tanks for initial mixing, then pumped to homogenizers for a third pulverization to obtain a tobacco stem / tobacco dust mixed slurry. This tobacco stem / tobacco dust mixed slurry is then formed using a mesh fabric, dehydrated under vacuum in a Yankee cylinder, and dehydrated at high temperature to obtain reconstituted tobacco leaf substrates.

[0011] Step 2, Coating and CMC-Na Spraying: The reconstituted tobacco substrate is dipped in tobacco coating liquid to form reconstituted tobacco sheet; CMC-Na solution is sprayed onto the surface of the sheet according to a preset ratio.

[0012] Step 3, Finished product drying: The reconstituted tobacco flakes coated with CMC-Na undergo a high-temperature dehydration process to remove excess moisture and fix the CMC-Na distribution, resulting in the finished reconstituted tobacco flakes.

[0013] In both of the above schemes, the mass concentration of CMC-Na solution is uniformly controlled at 0.1% - 1%, and the addition ratio is controlled at 0.1‰ - 10‰ (in Scheme 1, it is calculated as the percentage of CMC-Na mass in the oven-dry mass of the tobacco stem / tobacco dust mixture, and in Scheme 2, it is calculated as the percentage of CMC-Na mass in the oven-dry mass of the reconstituted tobacco leaf sheet).

[0014] By conducting single-factor experiments (such as adjusting the concentration or addition ratio of CMC-Na) or multi-factor orthogonal experimental design, the moisture absorption and desiccation characteristics and softness of reconstituted tobacco leaves can be precisely controlled, thereby achieving targeted optimization of the water retention and moisturizing effect.

[0015] The beneficial effects of this invention are reflected in: 1. This invention designs a dual-path addition process for CMC-Na, involving "mixing and homogenizing the pulp + secondary coating." This process can be directly integrated into industrial production without requiring equipment modifications to existing reconstituted tobacco production lines. Through flexible combinations of solution concentrations of 0.1% - 1% and addition ratios of 0.1‰ - 10‰, combined with single-factor / multi-factor orthogonal experimental design, the dynamic moisture adsorption-desorption performance of reconstituted tobacco can be actively and in real-time controlled. This achieves a balance between ease of operation and production adaptability, providing a feasible technical solution for targeted optimization of reconstituted tobacco performance.

[0016] 2. This invention can significantly optimize the fiber morphology of the pulp, greatly reducing the proportion of fine fibers and significantly increasing the average fiber length, thereby improving pulp retention and substrate wet strength. The improved substrate wet strength can fundamentally reduce the frequency of paper breaks during production, ensuring production continuity and effectively improving production efficiency. Simultaneously, the superior fiber morphology and substrate performance lay a solid foundation for subsequent processing of reconstituted tobacco (such as shredding and rolling), optimizing substrate quality.

[0017] 3. Through the water-retention properties and fiber regulation effects of CMC-Na, the moisture absorption and desiccation characteristics and paper base softness of reconstituted tobacco leaves can be precisely controlled according to actual application needs, ensuring stable and controllable water retention and moisturizing effects. At the same time, the introduction of CMC-Na can effectively reduce the irritation of smoke and significantly improve the oral moistness, achieving a synergistic upgrade of the physical properties (softness, water retention) and sensory quality (smoke, moistness) of reconstituted tobacco leaves, meeting the diversified and high-standard requirements of different cigarette formulations for sheet quality. Attached Figure Description

[0018] Figure 1 A schematic diagram illustrating the application of the CMC-Na secondary coating process to reconstitute tobacco leaf sheets.

[0019] Figure 2 The physicochemical properties of reconstituted tobacco leaves without CMC-Na application treatment are as follows: (a) fiber morphology distribution characteristics of reconstituted tobacco leaves; (b) average fiber length of reconstituted tobacco leaves; (c) dynamic moisture absorption and desiccation characteristics of reconstituted tobacco leaves under the process of increasing and decreasing relative humidity gradients of 20% - 80% - 20% (±10%); and (d) softness of reconstituted tobacco leaves.

[0020] Figure 3 The physicochemical properties of reconstituted tobacco leaves after CMC-Na was added to the tobacco stem / tobacco dust mixture at a ratio of 3‰ in Example 1 are as follows: (a) fiber morphology distribution characteristics of reconstituted tobacco leaves; (b) average fiber length of reconstituted tobacco leaves; (c) dynamic moisture absorption and desiccation characteristics of reconstituted tobacco leaves; and (d) softness of reconstituted tobacco leaves.

[0021] Figure 4 The physicochemical properties of reconstituted tobacco leaves after CMC-Na was added to the tobacco stem / tobacco dust mixture at a ratio of 6‰ in Example 2 are as follows: (a) fiber morphology distribution characteristics of reconstituted tobacco leaves; (b) average fiber length of reconstituted tobacco leaves; (c) dynamic moisture absorption and desiccation characteristics of reconstituted tobacco leaves; and (d) softness of reconstituted tobacco leaves.

[0022] Figure 5The physicochemical properties of reconstituted tobacco leaves after CMC-Na was added to the tobacco stem / tobacco dust mixture at a ratio of 9‰ in Example 3 are as follows: (a) fiber morphology distribution characteristics of reconstituted tobacco leaves; (b) average fiber length of reconstituted tobacco leaves; (c) dynamic moisture absorption and desiccation characteristics of reconstituted tobacco leaves; and (d) softness of reconstituted tobacco leaves.

[0023] Figure 6 The physicochemical properties of reconstituted tobacco leaves after CMC-Na was applied to the reconstituted tobacco leaf sheets twice at a ratio of 3‰ in Example 4 are as follows: (a) is the dynamic moisture absorption and desiccation properties of the reconstituted tobacco leaves; (b) is the softness of the reconstituted tobacco leaves.

[0024] Figure 7 The physicochemical properties of reconstituted tobacco leaves after CMC-Na was applied to the reconstituted tobacco leaf sheets twice at a ratio of 6‰ in Example 5 are as follows: (a) is the dynamic moisture absorption and desiccation properties of the reconstituted tobacco leaves; (b) is the softness of the reconstituted tobacco leaves.

[0025] Figure 8 The physicochemical properties of reconstituted tobacco leaves after CMC-Na was applied to the reconstituted tobacco leaf sheets twice at a ratio of 9‰ in Example 6 are as follows: (a) is the dynamic moisture absorption and desiccation properties of the reconstituted tobacco leaves; (b) is the softness of the reconstituted tobacco leaves. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The following embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. Those skilled in the art can easily rearrange or add steps to the methods described in this specification, but this still falls within the protection scope of this specification.

[0027] Example 1 This embodiment is based on the papermaking process for reconstituted tobacco leaves, and uses Scheme 1 (CMC-Na-pulp mixing and homogenization process) to prepare finished sheets. The specific operation is as follows: Step 1: Grading and grinding of raw materials The tobacco stems are refined twice, first in a primary refiner and then in a secondary refiner; the tobacco dust is refined once, separately in a secondary refiner. The operating parameters for the primary refiner are: power 99 kW, pulp concentration 3.8%, total pulp flow rate 1400 L / min, and pulp-to-return ratio 2:1. The operating parameters for the secondary refiner are: power 94 kW, pulp concentration 3.5%, total pulp flow rate 1200 L / min, and pulp-to-return ratio 1:1.

[0028] Step 2: Slurry mixing and CMC-Na addition After grinding, the tobacco stem slurry and tobacco dust slurry are pumped from storage tanks to mixing tanks for preliminary mixing to form a tobacco stem / tobacco dust mixed slurry. The tobacco stem / tobacco dust mixed slurry is then pumped to a homogenizer, and a 0.5% CMC-Na solution is added at a ratio of 3‰ (based on the percentage of CMC-Na mass to the oven-dry mass of the mixed slurry). The homogenizer operating parameters are set as follows: power 94 kW, slurry concentration 3.2%, total slurry flow rate 1200 L / min, and slurry output to reflux ratio 3:1. The tobacco stem / tobacco dust / CMC-Na mixed slurry is ground three times, and real-time sampling is performed on the production line to ensure that CMC-Na is fully integrated with the slurry.

[0029] Step 3: Shaping and Drying After the tobacco stem / tobacco dust / CMC-Na mixed slurry is formed by mesh fabric, it is successively dehydrated by vacuum negative pressure (-3 kPa) and high temperature dehydration (120℃) in a Yankee cylinder to obtain reconstituted tobacco leaf substrate. After the reconstituted tobacco leaf substrate is dipped in tobacco coating liquid (38% coating rate), it is dehydrated again at high temperature (130℃) to obtain finished reconstituted tobacco leaf sheets containing CMC-Na.

[0030] The reconstituted tobacco flakes obtained in this embodiment were subjected to performance testing, with reconstituted tobacco leaves without CMC-Na treatment used as a control sample (the preparation steps were the same as those for reconstituted tobacco flakes containing CMC-Na, except that the concentration of the CMC-Na solution was set to 0). The test results are as follows (see Figure 2 and Figure 3 ): 1. Fiber morphology optimization: Compared with reconstituted tobacco flakes without CMC-Na treatment, the proportion of fine fibers in the CMC-Na-treated reconstituted tobacco flakes prepared in this embodiment decreased from 0.218 to 0.157, and the average fiber length increased from 0.703 to 1.386, with significant improvement in fiber dispersion and regularity.

[0031] 2. Moisture absorption and desiccation characteristics: The reconstituted tobacco leaf sheets containing CMC-Na prepared in this embodiment had a moisture absorption mass of 6.18 mg during the process of increasing humidity gradient from 20% to 80% (+10%) (the moisture absorption mass of the reconstituted tobacco leaf sheets without CMC-Na treatment was 5.2 mg), and a desiccation mass of 6.18 mg during the process of decreasing humidity gradient from 80% to 20% (-10%), with the desiccation and moisture absorption in balance.

[0032] 3. Improved softness: Compared with reconstituted tobacco sheets without CMC-Na treatment, the fiber softness of the reconstituted tobacco substrate prepared in this embodiment increased from 31.94 to 51.64, and the substrate softness increased from 2.5 to 2.9.

[0033] The above results indicate that adding 3‰ CMC-Na using a flexible homogenization process can regulate the dynamic moisture adsorption and desorption capacity of the paper base and improve the softness of reconstituted tobacco leaves.

[0034] Example 2 This embodiment prepares reconstituted tobacco flakes containing CMC-Na using the same process as in Example 1, the only difference being that the CMC-Na addition ratio is 6‰ in step 2.

[0035] The reconstituted tobacco flakes obtained in this embodiment were subjected to the following performance tests, and the test results are as follows (see...). Figure 4 ): Fiber morphology optimization: The proportion of fine fibers in the reconstituted tobacco leaf sheets containing CMC-Na prepared in this embodiment was 0.155%, which was significantly lower than that of the control sample, and the average fiber length was 1.423, which was significantly higher than that of the control sample.

[0036] Moisture absorption and desiccation characteristics: During the process of increasing humidity gradient from 20% to 80% (+10%), the moisture absorption mass of the CMC-Na-containing sheet prepared in this embodiment is 7.25 mg; during the process of decreasing humidity gradient from 80% to 20% (-10%), the desiccation mass is 6.35 mg. The desiccation amount is lower than the moisture absorption amount, and the water retention and moisturizing effect is significant.

[0037] Improved softness: The fiber softness of the reconstituted tobacco substrate prepared in this embodiment increased from 31.94 to 63.07, and the substrate softness increased from 2.5 to 4.6.

[0038] Sensory quality: The reconstituted tobacco flakes containing CMC-Na prepared in this embodiment have significantly reduced smoke irritation and significantly enhanced oral moistness, resulting in a better overall sensory experience than reconstituted tobacco flakes without CMC-Na treatment.

[0039] The above results indicate that adding 6‰ CMC-Na using a flexible homogenization process can effectively regulate the dynamic moisture adsorption and desorption capacity of the paper base and improve the softness of reconstituted tobacco leaves.

[0040] Example 3 This embodiment prepares reconstituted tobacco flakes containing CMC-Na using the same process as in Example 1, the only difference being that the CMC-Na addition ratio is 9‰ in step 2.

[0041] The reconstituted tobacco flakes obtained in this embodiment were subjected to the following performance tests, and the test results are as follows (see...). Figure 5 ): Fiber morphology optimization: The proportion of fine fibers in the CMC-Na reconstituted tobacco flakes prepared in this embodiment was 0.159, which was significantly lower than that of the control sample, and the average fiber length was 1.386, which was significantly higher than that of the control sample.

[0042] Moisture absorption and desiccation characteristics: During the process of increasing humidity gradient from 20% to 80% (+10%), the moisture absorption mass of the CMC-Na-containing sheet prepared in this embodiment was 6.97 mg; during the process of decreasing humidity gradient from 80% to 20% (-10%), the desiccation mass was 7.39 mg, and the desiccation amount was higher than the moisture absorption amount.

[0043] Improved softness: The fiber softness of the reconstituted tobacco substrate prepared in this embodiment increased from 31.94 to 41.81, and the substrate softness increased from 2.5 to 4.1.

[0044] The above results indicate that adding 9‰ CMC-Na using a flexible homogenization process can regulate the dynamic moisture adsorption and desorption capacity of the paper base and improve the softness of reconstituted tobacco leaves.

[0045] Example 4 This embodiment is based on the papermaking reconstituted tobacco production process, and uses Scheme 2 (CMC-Na secondary coating process) to prepare finished sheets. The specific operation is as follows: Step 1: Raw material grinding and substrate molding The tobacco stems are refined twice, first in a primary refiner and then in a secondary refiner; the tobacco dust is refined once, separately in a secondary refiner. The operating parameters for the primary refiner are: power 99 kW, pulp concentration 3.8%, total pulp flow rate 1400 L / min, and pulp-to-return ratio 2:1. The operating parameters for the secondary refiner are: power 94 kW, pulp concentration 3.5%, total pulp flow rate 1200 L / min, and pulp-to-return ratio 1:1.

[0046] After grinding, the tobacco stem pulp and tobacco dust pulp are pumped from storage tanks to mixing tanks for initial mixing, and then pumped to a homogenizer for three grinding processes (homogenizer parameters: power 94 kW, pulp concentration 3.2%, total flow rate 1200 L / min, pulp output to reflux ratio 3:1) to obtain a mixed tobacco stem / dust pulp. After being formed by mesh fabrication, the mixed pulp undergoes sequential Yankee cylinder vacuum dewatering (-3 kPa) and high-temperature dewatering (120℃) processes to obtain reconstituted tobacco leaf substrate.

[0047] Step 2, Coating and CMC-Na Spraying Reconstituted tobacco leaf substrates are coated with tobacco coating solution (38% coating rate) to form reconstituted tobacco leaf sheets; such as Figure 1 As shown, an array jet spraying device (7 nozzles per row, nozzle width 5 mm, nozzle distance from reconstituted tobacco sheet 20 cm) was used to uniformly spray a 0.5% CMC-Na solution onto the sheet surface at a 3‰ addition ratio (calculated as the percentage of CMC-Na mass to the oven-dry mass of the reconstituted tobacco sheet). The jet spraying volume was adjusted in real time to ensure uniform coverage.

[0048] Step 3: Drying the finished product The reconstituted tobacco flakes coated with CMC-Na are subjected to a high-temperature dehydration process (130℃) to remove excess moisture and fix the distribution of CMC-Na, resulting in finished reconstituted tobacco flakes containing CMC-Na.

[0049] The reconstituted tobacco flakes obtained in this embodiment were subjected to performance testing, and the test results are as follows (see...). Figure 6 ): Fiber morphology optimization: Compared with reconstituted tobacco flakes without CMC-Na treatment, the proportion of fine fibers in the CMC-Na-treated reconstituted tobacco flakes prepared in this embodiment decreased from 0.218 to 0.157, and the average fiber length increased from 0.703 to 1.386, with significant improvement in fiber dispersion and regularity.

[0050] Improved softness: The fiber softness of the CMC-Na reconstituted tobacco sheet prepared in this embodiment increased from 31.94 to 49.34, and the sheet softness increased from 3.1 to 9.6, optimizing the physical feel and processing adaptability.

[0051] Moisture absorption and desiccation characteristics: During the process of increasing humidity gradient from 20% to 80% (+10%), the moisture absorption mass of the CMC-Na-containing sheet is 7.18 mg; during the process of decreasing humidity gradient from 80% to 20% (-10%), the moisture desiccation mass is 7.31 mg, and the desiccation amount is higher than the moisture absorption amount.

[0052] The above results indicate that CMC-Na applied in a 3‰ ratio for secondary coating can regulate the dynamic moisture adsorption and desorption capacity of the paper substrate, significantly improving the softness of reconstituted tobacco leaves.

[0053] Example 5 This embodiment prepares reconstituted tobacco flakes containing CMC-Na using the same process as in Example 4, the only difference being that the CMC-Na addition ratio is 6‰ in step 2.

[0054] The performance of the reconstituted tobacco flakes containing CMC-Na obtained in this embodiment was tested, and the test results are as follows (see Figure 7 ): Fiber morphology optimization: The proportion of fine fibers in the reconstituted tobacco leaf sheets containing CMC-Na prepared in this embodiment was 0.155%, which was significantly lower than that of the control sample, and the average fiber length was 1.423, which was significantly higher than that of the control sample.

[0055] Improved softness: The fiber softness of the CMC-Na reconstituted tobacco sheet prepared in this embodiment increased from 31.94 to 60.99, and the sheet softness increased from 3.1 to 14.5, significantly optimizing the physical feel and processing adaptability.

[0056] Moisture absorption and desiccation characteristics: During the process of increasing humidity gradient from 20% to 80% (+10%), the moisture absorption mass of the CMC-Na-containing sheet is 6.94 mg; during the process of decreasing humidity gradient from 80% to 20% (-10%), the moisture desiccation mass is 6.21 mg, and the desiccation amount is lower than the moisture absorption amount.

[0057] The above results indicate that secondary coating with CMC-Na at a ratio of 6‰ can regulate the dynamic moisture adsorption and desorption capacity of the paper substrate, and significantly improve the softness of reconstituted tobacco leaves.

[0058] Example 6 This embodiment prepares reconstituted tobacco flakes containing CMC-Na using the same process as in Example 4, the only difference being that the CMC-Na addition ratio is 9‰ in step 2.

[0059] The performance of the reconstituted tobacco flakes containing CMC-Na obtained in this embodiment was tested, and the test results are as follows (see Figure 8 ): Fiber morphology optimization: The proportion of fine fibers in the CMC-Na reconstituted tobacco flakes prepared in this embodiment was 0.159, which was significantly lower than that of the control sample, and the average fiber length was 1.386, which was significantly higher than that of the control sample.

[0060] Improved softness: The fiber softness of the CMC-Na reconstituted tobacco sheet prepared in this embodiment increased from 31.94 to 40.01, and the sheet softness increased from 3.1 to 13.7, significantly optimizing the physical feel and processing adaptability.

[0061] Moisture absorption and desiccation characteristics: During the process of increasing humidity gradient from 20% to 80% (+10%), the moisture absorption mass of the CMC-Na-containing sheet is 6.77 mg; during the process of decreasing humidity gradient from 80% to 20% (-10%), the moisture desiccation mass is 6.17 mg, and the desiccation amount is lower than the moisture absorption amount.

[0062] The above results indicate that CMC-Na applied in a 9‰ ratio for secondary coating can regulate the dynamic moisture adsorption and desorption capacity of the paper substrate, significantly improving the softness of reconstituted tobacco leaves.

[0063] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for regulating the moisture sorption-desorption characteristics and softness of reconstituted tobacco leaves by sodium carboxymethylcellulose, characterized in that: Based on the production process of reconstituted tobacco leaf by papermaking method, carboxymethyl cellulose sodium (CMC-Na) is mixed with tobacco stem / tobacco dust mixed pulp in the pulp preparation stage to realize the regulation of the moisture absorption and desorption characteristics and softness of the reconstituted tobacco leaf.

2. The method for regulating moisture sorption-desorption properties and softness of reconstituted tobacco leaves by sodium carboxymethyl cellulose according to claim 1, characterized in that, The method comprises the following steps: Step 1, raw material fractionation and pulp preparation The tobacco stem is subjected to secondary pulping by a first pulper and a second pulper in sequence; the tobacco dust is subjected to primary pulping by the second pulper alone; Step 2, pulp mixing and CMC-Na addition The pulp of the tobacco stem and the pulp of the tobacco dust after pulping are pumped from the storage tanks to a mixing tank for preliminary mixing, and the obtained tobacco stem / tobacco dust mixed pulp is pumped to a homogenizer; the CMC-Na solution is added to the homogenizer, and the tobacco stem / tobacco dust / CMC-Na mixed liquid is subjected to three times of pulping by the homogenizer to obtain the tobacco stem / tobacco dust / CMC-Na mixed pulp; Step 3, forming and drying After the tobacco stem / tobacco dust / CMC-Na mixed pulp is formed by the wire cloth, it is subjected to vacuum negative pressure dewatering by a Yankee cylinder and high-temperature dewatering in sequence to obtain a reconstituted tobacco leaf base sheet; after the reconstituted tobacco leaf base sheet is immersed in a tobacco coating solution, it is subjected to high-temperature dewatering again to obtain a finished reconstituted tobacco leaf sheet.

3. The method for regulating moisture sorption-desorption properties and softness of reconstituted tobacco leaves by sodium carboxymethyl cellulose according to claim 2, characterized in that: The mass concentration of the CMC-Na solution is 0.1% to 1%.

4. The method for regulating moisture sorption-desorption properties and softness of reconstituted tobacco leaves by sodium carboxymethyl cellulose according to claim 2, characterized in that: The added mass of the CMC-Na accounts for 0.1‰ to 10‰ of the absolute dry mass of the tobacco stem / tobacco dust mixed pulp. 5.A reconstituted tobacco leaf sheet containing CMC-Na and prepared by the method according to any one of claims 1 to 4.

6. A method for regulating the moisture sorption-desorption characteristics and softness of reconstituted tobacco leaves by sodium carboxymethylcellulose, characterized in that: Based on the production process of reconstituted tobacco leaf by papermaking method, CMC-Na is added by spraying after the reconstituted tobacco leaf base sheet is formed and immersed in a tobacco coating solution to realize the regulation of the moisture absorption and desorption characteristics and softness of the reconstituted tobacco leaf.

7. The method for regulating the hygroscopic and de-hygroscopic properties and softness of reconstituted tobacco leaves by sodium carboxymethyl cellulose according to claim 6, characterized in that, The method comprises the following steps: Step 1, raw material pulping and base sheet forming The tobacco stem is subjected to secondary pulping by a first pulper and a second pulper in sequence; the tobacco dust is subjected to primary pulping by the second pulper alone; the pulp of the tobacco stem and the pulp of the tobacco dust after pulping are pumped from the storage tanks to a mixing tank for preliminary mixing, and then pumped to a homogenizer for three times of pulping to obtain a tobacco stem / tobacco dust mixed pulp; the tobacco stem / tobacco dust mixed pulp is formed by a wire cloth, subjected to vacuum negative pressure dewatering by a Yankee cylinder, and subjected to high-temperature dewatering to obtain a reconstituted tobacco leaf base sheet; Step 2, coating and CMC-Na spraying The reconstituted tobacco leaf base sheet is immersed in a tobacco coating solution to form a reconstituted tobacco leaf sheet; the CMC-Na solution is sprayed on the surface of the sheet; Step 3, finished product drying The reconstituted tobacco leaf sheet after CMC-Na spraying is subjected to high-temperature dewatering to remove excess water and fix the distribution of the CMC-Na, thereby obtaining a finished reconstituted tobacco leaf sheet.

8. The method for regulating the hygroscopic and de-hygroscopic properties and softness of reconstituted tobacco leaves by sodium carboxymethyl cellulose as claimed in claim 7, wherein, The mass concentration of the CMC-Na solution is 0.1% to 1%.

9. The method for regulating the hygroscopic and de-hygroscopic properties and softness of reconstituted tobacco leaves by sodium carboxymethyl cellulose according to claim 8, characterized in that, The added mass of the CMC-Na accounts for 0.1‰ to 10‰ of the absolute dry mass of the reconstituted tobacco leaf sheet. 10.A reconstituted tobacco leaf sheet containing CMC-Na and prepared by the method according to any one of claims 6 to 9.

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