A tobacco-free aluminum inner liner paper base paper with humidity control function

Abstract

The present invention provides a tobacco-free aluminum inner liner paper base paper with a humidity adjustment function, belonging to the technical field of paper base materials. The inner liner paper base paper includes a composite fiber layer and a dynamic humidity adjustment layer. Among them, the composite fiber layer includes bleached kraft bamboo pulp, bleached kraft softwood pulp, bleached kraft hardwood pulp, and hydroxyapatite ultra-long nanowires; the dynamic humidity adjustment layer includes carboxymethyl cellulose, sepiolite nanoparticles, and carboxylated nanofibrillated cellulose. The diameter of the hydroxyapatite ultra-long nanowires is 1 to 100 nm, and the length is 10 μm to 5 mm. The relative molecular mass of the carboxymethyl cellulose is 90,000 to 300,000. The particle size of the sepiolite nanoparticles is 50 to 300 nm. The diameter of the carboxylated nanofibrillated cellulose is 10 to 100 nm, the length is 0.1 to 2 mm, and the carboxyl content is 0.5 to 2.0 mmol / g. This inner liner paper base paper utilizes hydroxyapatite ultra-long nanowires with a high aspect ratio and high hydroxyl content and sepiolite nanoparticles with a multi-level nanoporous structure to achieve a dynamic moisture absorption and desorption response to changes in the local microenvironment humidity.

Description

Technical Field

[0001] The present invention belongs to the technical field of paper-based materials, and particularly relates to a lining paper-based paper for cigarette packaging with a dynamic humidity control function and a corresponding preparation method thereof. Background Art

[0002] With the improvement of people's requirements for the smoking quality and tar reduction and harm reduction of cigarettes (cigarettes), higher and higher requirements are put forward for the materials (tobacco, cigarette packaging materials, etc.) involved in finished cigarettes and each processing link. Among them, due to its special porous fiber structure, the water content of tobacco is extremely susceptible to environmental factors, and the level of water content is directly related to the sensory evaluation quality of cigarettes. When the moisture content of the cut tobacco is too high, its burning speed slows down accordingly. At the same time, there is a large amount of water vapor in the incompletely burned flue gas, resulting in the inability to fully release chemical components, ultimately causing the loss of cigarette aroma. Moreover, the cut tobacco with a high moisture content is prone to mildew, and the sensory evaluation quality drops sharply. On the contrary, when the moisture content of the cut tobacco is too low, the burning speed of the cigarette is relatively fast during the burning process, resulting in too high a temperature of the burning flue gas, which has an adverse effect on a series of chemical reactions such as pyrolysis, distillation, volatilization, and synthesis. As a result, the flue gas of the cigarette burning has a strong smell, is highly irritating, and the generated flue gas is dry, pungent, and throat-irritating, making it difficult to be accepted by people. Therefore, an appropriate moisture content plays a crucial role in the quality of cigarettes.

[0003] The moisture content of the cut tobacco is directly related to the moisture retention performance of cigarettes. The moisture retention performance of cigarettes has an important impact on the aroma, smoking quality, and physical properties of cigarettes. Cigarette packaging materials (mainly including transparent paper, carton packaging board, and lining paper) endow cigarette products with aesthetic and barrier properties, and can build a relatively stable external environment for cigarettes, reducing the changes in moisture and aroma of cigarettes. Among them, the cigarette lining paper, as a paper-based packaging material between the packaged cigarette and the cigarette pack small box, plays roles such as aroma preservation, moisture retention, and light shielding for cigarettes, and can prevent cigarette mildew and aroma dissipation, and is an important cigarette packaging material. However, the cigarette barrier packaging material cannot effectively solve the problem of continuous constant humidity of cigarettes after the cigarette packaging is opened. Moreover, there are large differences in temperature and humidity between the north and south regions of our country, and cigarette products are easily affected by the regional environment, resulting in phenomena such as moisture loss, moisture absorption, and even yellow spot mildew. The existing cigarette lining paper for cigarette packs is generally made by laminating the base paper with aluminum foil or vacuum aluminizing. During production, packaging, and subsequent circulation, there will be adverse phenomena such as fast flue gas dissipation and poor aroma preservation performance, and it will also cause a large amount of waste of metallic aluminum. The aluminum-containing lining paper cannot be naturally degraded after being discarded and is difficult to recycle, bringing serious pollution to the environment. In addition, due to the reasons of the papermaking process and material composition of the existing cigarette lining paper base paper, there are problems such as stiffness, high content of fine components, and insufficient surface denseness of the paper, resulting in incomplete adhesion when it is laminated with the barrier coating, so that the produced aluminum-free cigarette lining paper cannot meet the use requirements.

[0004] According to the latest literature retrieval and patent novelty search, there are few reports on the aluminum-free inner liner paper base paper for cigarettes with humidity regulation function and its preparation method. Several patents related to this topic have their respective defects and deficiencies. For example, the patent "Production Method of Aluminum-Free Inner Liner Paper Base Paper for Cigarettes" with the patent number CN106320061B only introduces a production method for the base paper suitable for producing aluminum-free inner liner paper. However, the base paper obtained according to this production method does not have the humidity regulation function, and strong acid treatment is used in the production process, which poses potential safety hazards during production; the patent "A Cigarette Inner Liner Paper and Its Manufacturing Method and Application" with the patent number CN114775331B introduces a cigarette inner liner paper with a certain humidity regulation function, but the humidity regulation material used is inorganic diatomaceous earth, and the humidity regulation performance is limited. Moreover, the manufactured cigarette inner liner paper is only suitable for compounding with aluminum foil or achieving the barrier function of the cigarette inner liner paper through aluminized film, which does not meet the environmental protection requirements; the patent "A Humidity Absorption Equilibrium Cigarette Inner Liner Paper and Its Preparation Method" with the patent number CN114086429B introduces a preparation method with a complex process, and resin materials such as polyurethane and photoinitiators are required. Not only does it pose environmental protection hazards, but the photoinitiator that plays the humidity regulation function curing on the surface of the base paper will affect the softness of the cigarette inner liner paper, thus posing challenges to the subsequent cigarette box packaging preparation system; the patent "A Cigarette Inner Liner Paper with Moisture Retention, Aroma Preservation and Quality Preservation Functions and Its Manufacturing Method" with the patent number CN109403148A introduces a cigarette inner liner paper with a certain moisture retention function, but a vacuum aluminized layer is required to achieve the barrier function, and the humidity regulation material used requires a relatively high hot melt temperature to achieve, which limits its application to a certain extent. In addition, there is a type of ceramic-coated inner liner paper, which has a certain humidity regulation effect, but organic synthetic adhesives are required when coating the clay on the surface of the inner liner paper. Such adhesives have good film-forming properties, seriously affecting the porosity of the clay coating, thus hindering the exertion of the humidity regulation ability of the clay.

[0005] Therefore, developing cigarette packaging materials with continuous dynamic humidity regulation function to slow down the moisture exchange between cigarettes and the environment, especially after the cigarette pack is opened, maintaining the moisture content of cigarettes to make them have stable sensory qualities and smoking experiences, and at the same time developing a base paper that is soft, has a low content of fine components, and a dense surface structure to meet the process requirements of subsequent aluminum-free cigarette inner liner paper, and producing aluminum-free cigarette inner liner paper with dynamic humidity regulation function, safety, environmental protection and meeting the needs of personalized products has become an urgent problem to be solved in the tobacco industry. Summary of the Invention

[0006] In view of the defects and deficiencies of the existing technology, the present invention provides a tobacco-free aluminum inner liner paper base paper with a humidity adjustment function. On the one hand, this inner liner paper base paper has good softness, high surface strength (no linting or powdering), and a dense surface structure (high tightness and smoothness), thus meeting the production process requirements of subsequent tobacco-free aluminum inner liner paper. On the other hand, it can autonomously regulate the humidity of the microenvironment inside the cigarette packaging box through the functions of water locking and moisturizing and water drainage and moisture release according to the humidity changes in the storage environment, achieving the purpose of constant humidity and quality preservation after the cigarette packaging box is unsealed, and thus controlling the tobacco humidity within a reasonable range.

[0007] To achieve the above object, the present invention provides a tobacco-free aluminum inner liner paper base paper with a humidity adjustment function. The tobacco-free aluminum inner liner paper base paper includes a composite fiber layer and a dynamic humidity adjustment layer. Among them, the components of the composite fiber layer include three pulp fibers, namely bleached sulfate bamboo pulp, bleached sulfate softwood pulp, and bleached sulfate hardwood pulp, and an inorganic synthetic fiber - hydroxyapatite ultra-long nanowire. The components of the dynamic humidity adjustment layer include carboxymethyl cellulose, sepiolite nanoparticles, and carboxylated nanofibrillated cellulose.

[0008] The present invention utilizes nanoscience and technology and innovatively proposes to use an inorganic nano-biological material, hydroxyapatite ultra-long nanowires, as a humidity-adjusting material and a reinforcing material for the composite fiber layer of the aluminum-free inner liner paper base paper for cigarettes. By virtue of the extremely high proportion of hydroxyl groups on the surface of the hydroxyapatite ultra-long nanowires and the nano-porous network structure formed by the intertwining and winding of the nanowires, the present invention provides multi-level binding sites for the adsorption of water molecules. Moreover, since the adsorption of water molecules by the formed nano-porous network structure is physical adsorption and is extremely sensitive to the surrounding vapor pressure (humidity) (when the surrounding humidity is high, the nano-porous structure will adsorb more water molecules; when the surrounding humidity is low, affected by the vapor pressure, it will release water molecules to the surrounding), the dynamic response and regulation of the local humidity can be achieved. Therefore, by virtue of the excellent moisture absorption and release performance of the hydroxyapatite ultra-long nanowires, the present invention realizes the dynamic humidity-adjusting performance of the aluminum-free inner liner paper base paper for cigarettes proposed by the present invention. In addition, in the traditional papermaking process, an organic polymer (generally a non-degradable polymer substance) needs to be added as a reinforcing aid to improve the strength performance of the paper sheet structure formed by the intertwining of pulp fibers. In the present invention, by virtue of the hydroxyl groups rich on the surface of the hydroxyapatite ultra-long nanowires, the pulp fibers also rich in hydroxyl groups are bridged through hydrogen bond binding; at the same time, by using the high specific surface area and high aspect ratio of the hydroxyapatite ultra-long nanowires, the pulp fibers are wound, kinked, bundled, etc. through physical actions to increase the binding area between the pulp fibers, thereby enhancing the binding strength between the pulp fibers and realizing the improvement of the strength performance of the aluminum-free inner liner paper base paper for cigarettes proposed by the present invention. The pulp fibers generally used in the existing inner liner paper base paper for cigarettes are bleached sulfate softwood pulp and bleached sulfate hardwood pulp. The present invention uses bleached sulfate bamboo pulp to replace part of the bleached sulfate hardwood pulp. On the one hand, the good hygroscopicity of bamboo fibers is utilized, and on the other hand, the relatively high aspect ratio of bamboo fibers is used to enhance the strength performance of the inner liner paper base paper for cigarettes.

[0009] In the present invention, the sepiolite nanoparticles are a kind of self-made inorganic nanoparticles, which are developed according to the demand characteristics of the tobacco-free aluminum inner liner paper-based paper for dynamic humidity adjustment performance and surface strength performance. Natural sepiolite has excellent moisture absorption and desorption performance due to its rich porous structure, but its application on the surface of paper-based materials is very limited. In the present invention, natural sepiolite is used as the raw material, and through multi-stage physical and mechanical grinding means, the size and crystal form of sepiolite are precisely controlled to prepare nanoscale sepiolite particles. The nanoscale sepiolite particles have a nano-pore channel structure with a high aspect ratio, and at the same time have high crystal strength and high interfacial activity. In order to improve the surface strength of the tobacco-free aluminum inner liner paper-based paper and retain a relatively high porosity on the surface of the base paper (the dynamic humidity adjustment performance requires a multi-level pore structure to achieve), the present invention innovatively proposes to use carboxylated nanocellulose fibers as the nano-scale adhesive for the dynamic humidity adjustment layer of the tobacco-free aluminum inner liner paper-based paper. And through the high-pressure homogenization treatment of sepiolite nanoparticles and carboxylated nanocellulose, the effective loading of sepiolite nanoparticles inside and between carboxylated nanocellulose fibers is realized. The present invention utilizes the good film-forming property and moisture absorption property of carboxymethyl cellulose, the good moisture absorption and desorption property of sepiolite nanoparticles, the good loading property and bonding effect of carboxylated nanocellulose fibers to achieve the dynamic moisture absorption and desorption performance and good surface strength of the dynamic humidity adjustment layer of the tobacco-free aluminum inner liner paper-based paper.

[0010] Preferably, in the composite fiber layer of the tobacco-free aluminum inner liner paper-based paper with humidity adjustment function, the mass percentages of the three pulp fibers of bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp can be (10-20)%:(40-80)%:(10-25)%.

[0011] Preferably, in the composite fiber layer of the tobacco-free aluminum inner liner paper-based paper with humidity adjustment function, the addition amount of the hydroxyapatite ultra-long nanowires is 50-400 g / kg of dry pulp fibers (including the three pulp fibers of bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp).

[0012] Preferably, in the composite fiber layer of the tobacco-free aluminum inner liner paper-based paper with humidity adjustment function, the diameter of the hydroxyapatite ultra-long nanowires is 1-100 nm and the length is 10 μm-5 mm. The three pulp fibers of bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp adopt a mixed pulping treatment process, and the Schopper-Riegler beating degree of the mixed pulp fibers after pulping is 25-60°SR.

[0013] Preferably, in the dynamic humidity adjustment layer of the aluminum-free inner liner paper base paper for cigarettes with humidity adjustment function, the mass percentage content of the carboxymethyl cellulose is 50-90%, the mass percentage content of the sepiolite nanoparticles is 10-30%, and the mass percentage content of the carboxylated nanofibrillated cellulose is 5-20%.

[0014] Preferably, in the dynamic humidity adjustment layer of the aluminum-free inner liner paper base paper for cigarettes with humidity adjustment function, the relative molecular mass of the carboxymethyl cellulose is 90,000-300,000, the degree of substitution (DS) is 0.7-1.2, the diameter of the carboxylated nanofibrillated cellulose is 10-100 nm, the length is 0.1-2 mm, and the carboxyl content is 0.5-2.0 mmol / g.

[0015] Preferably, in the dynamic humidity adjustment layer of the aluminum-free inner liner paper base paper for cigarettes with humidity adjustment function, the particle size of the sepiolite nanoparticles is 50-300 nm, and the preparation method of the sepiolite nanoparticles includes:

[0016] (1) After washing and purifying and removing slag from natural sepiolite, a sepiolite suspension with a mass concentration of 50-70% is prepared, placed in a planetary mill and ground for 1-3 h, and the rotation speed of the mill is 200-1000 r / min;

[0017] (2) After adding sodium polyacrylate dispersant to the initially ground sepiolite suspension, the mass concentration of the suspension is adjusted to 40-80%, the addition amount of the sodium polyacrylate dispersant is 2-7 g / kg of absolute dry sepiolite, and then it is placed in a nano mill and ground for 2-5 h, and the rotation speed of the nano mill is 500-1200 r / min;

[0018] (3) After the sepiolite suspension treated by the nano mill is concentrated, it is then obtained by freeze-drying treatment to obtain sepiolite nanoparticles.

[0019] Preferably, the preparation steps of the aluminum-free inner liner paper base paper for cigarettes with humidity adjustment function include:

[0020] (1) Bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp are broken into a mixed pulp suspension with a mass concentration of 3-6% according to a certain mass percentage, and after beating treatment, a certain Schopper-Riegler beating degree is achieved;

[0021] (2) After adding hydroxyapatite ultra-long nanowires to the above-mentioned mixed pulp fiber suspension after beating according to a certain mass percentage, the mixed suspension is diluted to a mass concentration of 0.2-1%, and after mechanical stirring, vacuum filtration forming, pressing and drying, a fiber composite layer of the aluminum-free inner liner paper base paper for cigarettes is obtained;

[0022] (3) Mix sepiolite nanoparticles and carboxylated nanocellulose into a suspension with a mass concentration of 0.5 - 2% according to a certain mass percentage, and then process it through a high-pressure homogenizer with a homogenization pressure of 50 - 200 MPa for 3 - 6 times;

[0023] (4) Add carboxymethyl cellulose to the above-mentioned homogenized suspension according to an addition ratio of 50 - 90% by mass percentage of carboxymethyl cellulose in the dynamic humidity adjustment layer. Then, dilute it to a mass concentration of 0.2 - 1% to obtain a composite coating solution;

[0024] (5) Through one of the coating processes such as bar coating, curtain coating, or knife coating, and using the single-sided coating method, transfer the above composite coating solution onto the fiber composite layer of the aluminum-free inner liner paper base paper for cigarettes. After drying, obtain the aluminum-free inner liner paper base paper for cigarettes including a fiber composite layer and a dynamic humidity adjustment layer;

[0025] Preferably, the basis weight of the composite fiber layer of the aluminum-free inner liner paper base paper for cigarettes with humidity adjustment function is 55 - 65 g / m 2 , and the coating amount of the dynamic humidity adjustment layer of the aluminum-free inner liner paper base paper for cigarettes with humidity adjustment function is 0.5 - 2 g / m 2 .

[0026] The aluminum-free inner liner paper base paper for cigarettes with humidity adjustment function provided by the present invention utilizes hydroxyapatite ultra-long nanowires with high aspect ratio, high specific surface area, and high hydroxyl content in the composite fiber layer (through intermolecular hydrogen bonding and physical entanglement in chemistry to form an ordered, intertwined, porous three-dimensional network structure and good flexibility) and sepiolite nanoparticles with an innovative multi-level nanoporous structure in the dynamic humidity adjustment layer to achieve a dynamic moisture absorption - desorption response to local microenvironmental humidity changes. At the same time, relying on the excellent moisture absorption performance of the organic humidity adjustment material - carboxymethyl cellulose in the dynamic humidity adjustment layer, the excellent moisture desorption performance of the inorganic humidity adjustment material - hydroxyapatite ultra-long nanowires in the fiber composite layer and the inorganic humidity adjustment material - sepiolite nanoparticles in the dynamic humidity adjustment layer, and using the synergistic mechanism of the organic - inorganic composite humidity adjustment system in the multiple cycles of moisture absorption - desorption behavior, the continuous and stable dynamic humidity adjustment performance of the aluminum-free inner liner paper base paper for cigarettes is realized to adapt to the complex humidity environment changes in subsequent multiple unpacking scenarios during actual cigarette packaging. In addition, for the aluminum-free inner liner paper base paper for cigarettes with humidity adjustment function provided by the present invention, adopting the process of single-sided coating of the dynamic humidity adjustment layer can, on the one hand, effectively exert the humidity adjustment function of the hydroxyapatite ultra-long nanowires in the composite fiber layer, and on the other hand, maintain the reactivity and wettability of one side of the composite fiber layer, making it suitable for the requirements of subsequent aluminum-free barrier coating process BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1The structural schematic diagram of the aluminum-free inner liner paper base paper for cigarettes with humidity control function according to the present invention is shown.

[0028] Figure 2 The scanning electron microscope photograph of a hydroxyapatite ultra-long nanowire is shown.

[0029] Figure 3 The scanning electron microscope photograph of a sepiolite nanoparticle is shown. Specific embodiments

[0030] In the description of the present invention, it should be noted that for those not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0031] The present invention will be further described below in conjunction with the accompanying drawings and the following embodiments to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention. It should be understood that the accompanying drawings and the following embodiments are only used to illustrate the present invention and do not limit the present invention.

[0032] The aluminum-free inner liner paper base paper for cigarettes with humidity control function in one embodiment of the present invention includes a composite fiber layer 2 containing bleached kraft bamboo pulp, bleached kraft softwood pulp, bleached kraft hardwood pulp and hydroxyapatite ultra-long nanowires, and a dynamic humidity control layer 1 containing carboxymethyl cellulose, sepiolite nanoparticles and carboxylated nanofibrillated cellulose fibers.

[0033] In the aluminum-free inner liner paper base paper for cigarettes with humidity control function, three kinds of pulp fibers such as bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp serve as the skeleton support materials of the base paper, and the hydroxyapatite ultra-long nanowires are coated on the three kinds of plant pulp fibers; the sepiolite nanoparticles are adsorbed on the surface of the carboxylated nanofibrillated cellulose fibers, and after drying and forming, the carboxylated nanofibrillated cellulose fibers play a bonding role, so that the sepiolite nanoparticles are uniformly and firmly distributed in the film material solidified from the carboxymethyl cellulose film-forming solution.

[0034] Among them, the diameter of the hydroxyapatite ultra-long nanowires is 1-100 nm and the length is 10 μm-5 mm.

[0035] The hydroxyapatite ultra-long nanowires are used as the humidity control and strengthening functional materials of the base paper composite fiber layer, and the addition amount thereof in the composite fiber layer is 50-400 g / kg of dry pulp fibers, preferably 150-300 g / kg of dry pulp fibers. Within the addition amount range of 50-400 g / kg of dry pulp fibers, the hydroxyapatite ultra-long nanowires can connect the three kinds of pulp fibers by means of winding, coating, bridging, etc., so as to be beneficial to improving the physical and mechanical strength performance of the base paper composite fiber layer.

[0036] The Schopper-Riegler initial beating degree of bleached kraft bamboo pulp is 10-15°SR, and the Schopper-Riegler initial beating degrees of bleached kraft softwood pulp and bleached kraft hardwood pulp are 15-20°SR; the three kinds of pulp fibers are mixed and beaten, and the Schopper-Riegler beating degree of the final mixed fiber pulp is controlled to be 25-60°SR, preferably 40-50°SR.

[0037] The mass percentages of bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp in the composite fiber layer of the aluminum-free inner liner paper for cigarettes with humidity adjustment function are (10-20)%:(40-80)%:(10-25)%, preferably (15-20)%:(60-80)%:(10-15)%.

[0038] The relative molecular mass of carboxymethyl cellulose is 90,000-300,000, and the degree of substitution (DS) is 0.7-1.2.

[0039] As the film-forming material and organic humidity adjustment material of the dynamic humidity adjustment layer of the base paper, the mass percentage content of carboxymethyl cellulose in the dynamic humidity adjustment layer of the aluminum-free inner liner paper for cigarettes with humidity adjustment function is 50-90%, preferably 60-80%. In the range of 50-90% content, carboxymethyl cellulose can form a uniform film on the surface of the composite fiber layer of the base paper.

[0040] The particle size of sepiolite nanoparticles is 50-300 nm, preferably 100-200 nm.

[0041] As the inorganic humidity adjustment material of the dynamic humidity adjustment layer of the base paper, the mass percentage content of sepiolite nanoparticles in the dynamic humidity adjustment layer of the aluminum-free inner liner paper for cigarettes with humidity adjustment function is 10-30%. In the range of 10-30% content, sepiolite nanoparticles can play a role in moisture absorption and moisture release in the dynamic humidity adjustment layer of the base paper.

[0042] The diameter of carboxylated nanocellulose fibers is 10-100 nm, the length is 0.1-2 mm, and the carboxyl content is 0.5-2.0 mmol / g.

[0043] As the green organic adhesive of the dynamic humidity adjustment layer of the base paper, the mass percentage content of carboxylated nanocellulose fibers in the dynamic humidity adjustment layer of the aluminum-free inner liner paper for cigarettes with humidity adjustment function is 5-20%, preferably 10-20%. In the range of 5-20% content, carboxylated nanocellulose fibers evenly and firmly distribute sepiolite nanoparticles in the dynamic humidity adjustment layer of the matrix through chemical hydrogen bond binding and physical adsorption, thereby improving the dynamic humidity adjustment performance of the aluminum-free inner liner paper for cigarettes.

[0044] The basis weight of the composite fiber layer of the aluminum-free cigarette inner liner paper with humidity adjustment function can be selected according to the subsequent process requirements and performance requirements of the aluminum-free cigarette inner liner paper, for example, it is 55-65 g / m 2 。The coating amount of the dynamic humidity adjustment layer of the aluminum-free cigarette inner liner paper with humidity adjustment function can be selected according to needs, for example, it is 0.5-2 g / m 2 。

[0045] The aluminum-free cigarette inner liner paper base paper with humidity adjustment function according to an embodiment of the present invention can be prepared by traditional papermaking process and coating process. The preparation process includes the preparation of the composite fiber slurry of the composite fiber layer, the filtration and forming of the slurry, the pressing and drying of the wet paper sheet, the preparation of the coating liquid (dynamic humidity adjustment layer), the coating of the paper sheet (composite fiber layer), the drying of the coated paper sheet and other processes.

[0046] First, prepare a composite fiber slurry containing three kinds of pulp fibers such as bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp and hydroxyapatite ultra-long nanowires.

[0047] The three kinds of pulp fibers such as bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp of the present invention can be purchased from the market.

[0048] The hydroxyapatite ultra-long nanowires of the present invention can be prepared by solvothermal method, hydrothermal method or any suitable method, as long as the method can prepare the hydroxyapatite ultra-long nanowires. It can be prepared with reference to the published literature reports and the disclosed patent methods. For example, it can be referred to: Zhang G D, Chen J D, Yang S, et al. Materials Letters, 2011, 65: 572-574; Jiang Y Y, Zhu Y J, Chen F, et al. Ceramics International, 2015, 41: 6098-6102; Heng L, Zhu Y J, et al. ChemNanoMat, 2017, 3: 259-268; Patent No.: ZL201310687363.2.

[0049] Figure 2 The scanning electron microscope photograph of a kind of hydroxyapatite ultra-long nanowires prepared according to the above-mentioned literature and patent is shown.

[0050] In the slurry, the mass ratio of the three kinds of pulp fibers of bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp can be (10-20)%:(40-80)%:(10-25)%, and the addition amount of the hydroxyapatite ultra-long nanowires can be 50-400 g / kg of absolute dry pulp fibers.

[0051] In one embodiment, hydroxyapatite ultra-long nanowires are added to three kinds of pulp fiber suspensions that have been pulped and stirred evenly to obtain a composite fiber layer mixed pulp.

[0052] The pulp is formed by draining water. The device used for water drainage and forming can be a Kersey sheet former, a dynamic sheet former, a manual sheet former, etc.

[0053] The formed paper sheet is pressed. The pressing pressure can be 1 - 10 MPa, and the pressing time can be 1 - 20 min.

[0054] After pressing, drying is carried out to obtain a composite fiber layer of aluminu m-free cigarette inner lining paper base paper with humidity control function. The drying temperature can be 70 - 120 °C, and the drying time can be 5 - 150 min.

[0055] Preparation of the coating solution. The self-made sepiolite nanoparticles and carboxylated nanocellulose are formulated into a suspension with a mass concentration of 0.5 - 2% according to the mass percentage (10 - 30)%:(5 - 20)%, and after being processed by a high-pressure homogenizer with a homogenization pressure of 3 - 6 times and 50 - 200 MPa, carboxymethyl cellulose is added to the above-mentioned homogenized suspension according to the addition ratio that the mass percentage content of carboxymethyl cellulose in the coating solution is 50 - 90%, and then the mixed suspension is diluted to 0.1 - 1% to obtain the coating solution for preparing the dynamic humidity control layer.

[0056] The carboxymethyl cellulose, natural sepiolite crude ore, and carboxylated nanocellulose fibers of the present invention can be purchased from the market.

[0057] Coating of the paper sheet. Any one of the coating processes such as a doctor blade, a curtain coating, or a knife coating is selected to transfer the coating solution to one side of the above-mentioned dried paper sheet, and then drying is carried out to obtain the aluminu m-free cigarette inner lining paper base paper with humidity control function. The drying temperature can be 50 - 120 °C, and the drying time can be 1 - 20 min.

[0058] The following further gives examples to illustrate the present invention in detail. It should be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the protection scope of the present invention. The specific process parameters and the like in the following examples are also only an example within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description in this article, rather than being limited to the specific values in the following examples.

[0059] Example 1

[0060] This example provides a preparation method of an aluminu m-free cigarette inner lining paper base paper with humidity control function, and the specific steps are as follows:

[0061] S1: Break down bleached kraft bamboo pulp (initial Schopper-Riegler beating degree: 10°SR), bleached kraft softwood pulp (initial Schopper-Riegler beating degree: 15°SR), and bleached kraft hardwood pulp (initial Schopper-Riegler beating degree: 15°SR) into a mixed pulp suspension with a mass concentration of 3% according to the mass percentage of 10%:65%:25%, and perform mixed grinding treatment to make the Schopper-Riegler beating degree of the mixed pulp fibers reach 40°SR;

[0062] S2: Add hydroxyapatite ultra-long nanowires with a diameter of 10 nm and a length of 30 μm to the above-mentioned ground mixed pulp fiber suspension according to the mass percentage of 150 g / kg of oven-dry pulp fibers. Dilute the mixed suspension with water to a mass concentration of 0.5%. After mechanical stirring and draining and forming on a Kayser sheet former, the formed wet sheet is pressed (pressure: 3 MPa, pressing time: 8 min) and dried (drying temperature: 120 °C, drying time: 5 min) to obtain a composite fiber layer of aluminu m-free cigarette inner liner paper base paper with humidity control function;

[0063] S3: Preparation of sepiolite nanoparticles, through the following steps:

[0064] (1) After washing and purifying and removing slag from natural sepiolite, prepare a sepiolite suspension with a mass concentration of 60%, place it in a planetary mill and grind for 1 h, and the rotational speed of the mill is 1000 r / min;

[0065] (2) Add sodium polyacrylate dispersant to the preliminarily ground sepiolite suspension and adjust the mass concentration of the suspension to 40%. The addition amount of sodium polyacrylate dispersant is 2 g / kg of oven-dry sepiolite, and then place it in a nano mill and grind for 2 h. The rotational speed of the nano mill is 1200 r / min;

[0066] (3) After concentrating the sepiolite suspension treated by the nano mill, perform freeze-drying treatment to obtain sepiolite nanoparticles;

[0067] (4) Measured by a nano particle size tester, the particle size of the sepiolite nanoparticles prepared through the above steps is 105 nm.

[0068] Figure 3 The scanning electron microscope photograph of the sepiolite nanoparticles prepared through the above steps is shown;

[0069] S4: Configure the above-prepared sepiolite nanoparticles and carboxylated nano cellulose fibers into a suspension with a mass concentration of 1% according to the mass percentage of 10%:5%, and then, process it through a high-pressure homogenizer for 3 times with a homogenization pressure of 50 MPa;

[0070] S5: Add carboxymethyl cellulose to the above-mentioned homogenized suspension at an addition ratio of 50% by mass percentage of carboxymethyl cellulose in the dynamic humidity control layer. Then, dilute it with water to a mass concentration of 0.6% to obtain a composite coating solution.

[0071] S6: Adopt the single-sided coating method and select the doctor blade coating process. Transfer the above composite coating solution onto the composite fiber layer of the aluminum-free inner liner paper base for cigarettes with humidity control function, and dry it (the drying temperature is 50 °C and the drying time is 20 min) to obtain the aluminum-free inner liner paper base for cigarettes with humidity control function.

[0072] The application performance of the aluminum-free inner liner paper base for cigarettes with humidity control function prepared in this example is shown in Table 1:

[0073] Table 1. Application performance indicators of the aluminum-free inner liner paper base for cigarettes with humidity control function

[0074]

[0075] The application performance indicators of the aluminum-free inner liner paper base for cigarettes with humidity control function prepared in this example meet the quality requirements of the inner liner paper base. After being tried by the subsequent aluminum-free inner liner paper manufacturers for cigarettes, the feedback results show that compared with the inner liner paper base on the market, the inner liner paper base prepared in Example 1 has better softness, higher surface strength and denser surface structure.

[0076] Example 2

[0077] This embodiment provides a method for preparing a tobacco aluminum-free inner liner paper base paper with a humidity adjustment function. The steps are the same as those in Embodiment 1, and the process parameters are different from those in Embodiment 1 in that: bleached kraft bamboo pulp, bleached kraft softwood pulp, and bleached kraft hardwood pulp are broken into a mixed fiber suspension with a mass concentration of 5% according to the mass percentage of 20%:70%:10%. After beating, the Schopper-Riegler beating degree of the mixed pulp fibers is 60°SR; hydroxyapatite ultra-long nanowires with a diameter of 100 nm and a length of 5 mm are added to the mixed pulp fiber suspension according to the mass percentage of 200 g / kg of absolute dry pulp fibers, and then diluted with water to a mass concentration of 0.8%. After mechanical stirring, it is filtered and formed on a dynamic sheet former, and the pressing and drying processes are the same as those in Embodiment 1; the preparation process of sepiolite nanoparticles is the same as that in Embodiment 1, and the process parameters are different from those in Embodiment 1 in that: after adding a sodium polyacrylate dispersant of 4 g / kg of absolute dry sepiolite to the preliminarily ground sepiolite suspension, the mass concentration of the sepiolite suspension is diluted with water to 35% and then ground in a nano grinder for 3 h to obtain sepiolite nanoparticles with a particle size of 60 nm; sepiolite nanoparticles with a particle size of 60 nm and carboxylated nanofibrillated cellulose fibers are configured into a suspension with a mass concentration of 0.7% according to the mass percentage of 30%:20%, and then subjected to high-pressure homogenization treatment with the same process parameters as in Embodiment 1; carboxymethyl cellulose is added to the above-mentioned homogenized suspension according to the addition ratio of 80% of the mass percentage of carboxymethyl cellulose in the dynamic humidity adjustment layer. Then, it is diluted with water to a mass concentration of 0.5% to obtain a composite coating solution.

[0078] The application performance of the tobacco aluminum-free inner liner paper base paper with a humidity adjustment function prepared in this embodiment is shown in Table 2:

[0079] Table 2. Performance indicators of the tobacco aluminum-free inner liner paper base paper with a humidity adjustment function

[0080]

[0081]

[0082] The application performance indicators of the tobacco aluminum-free inner liner paper base paper with a humidity adjustment function prepared in this embodiment meet the quality requirements of the inner liner paper base paper. After being tried by subsequent tobacco aluminum-free inner liner paper manufacturers, the feedback results show that, compared with the inner liner paper base paper on the market, the inner liner paper base paper prepared in this Embodiment 2 has better softness, higher surface strength, and a denser surface structure.

[0083] Embodiment 3

[0084] This embodiment provides a method for preparing a tobacco-aluminum-free inner liner paper base paper with a humidity-adjusting function. The steps are the same as those in Embodiment 1, and the process parameters are different from those in Embodiment 1 in that: bleached kraft bamboo pulp, bleached kraft softwood pulp, and bleached kraft hardwood pulp are broken down into a mixed fiber suspension with a mass concentration of 5% according to the mass percentage of 15%:75%:10%. After beating, the Schopper-Riegler beating degree of the mixed pulp fibers is 50°SR; hydroxyapatite ultra-long nanowires with a diameter of 20 nm and a length of 1 mm are added to the mixed pulp fiber suspension according to the mass percentage of 100 g / kg of oven-dry pulp fibers, and then diluted with water to a mass concentration of 0.5%. After mechanical stirring, it is filtered and formed on a manual sheet former, and the pressing and drying processes are the same as those in Embodiment 1; the preparation process of sepiolite nanoparticles is the same as that in Embodiment 1, and the process parameters are different from those in Embodiment 1 in that: after adding a sodium polyacrylate dispersant of 4 g / kg of oven-dry sepiolite to the preliminarily ground sepiolite suspension, the mass concentration of the sepiolite suspension is diluted with water to 35% and then placed in a nano-grinder for grinding for 5 h to obtain sepiolite nanoparticles with a particle size of 50 nm; sepiolite nanoparticles with a particle size of 50 nm and carboxylated nanofibrillated cellulose fibers are configured into a suspension with a mass concentration of 1% according to the mass percentage of 20%:15% and then subjected to high-pressure homogenization treatment with the same process parameters as in Embodiment 1; carboxymethyl cellulose is added to the above-mentioned homogenized suspension according to the addition ratio of 70% of the mass percentage of carboxymethyl cellulose in the dynamic humidity-adjusting layer. Then, it is diluted with water to a mass concentration of 0.2% to obtain a composite coating solution; the composite coating solution is transferred to one side of the composite fiber layer of the tobacco-aluminum-free inner liner paper base paper by a knife coating process and dried (drying temperature is 100 °C, drying time is 10 min).

[0085] The application performance of the tobacco-aluminum-free inner liner paper base paper with a humidity-adjusting function prepared in this embodiment is shown in Table 3:

[0086] Table 3. Performance indicators of the tobacco-aluminum-free inner liner paper base paper with a humidity-adjusting function

[0087]

[0088] The application performance indicators of the tobacco-aluminum-free inner liner paper base paper with a humidity-adjusting function prepared in this embodiment meet the quality requirements of the inner liner paper base paper. After being tried by subsequent tobacco-aluminum-free inner liner paper manufacturers, the feedback results show that compared with the inner liner paper base paper on the market, the inner liner paper base paper prepared in this Embodiment 3 has better softness, higher surface strength, and a denser surface structure.

[0089] Embodiment 4

[0090] This embodiment provides a method for preparing an aluminum-free inner liner paper base paper for cigarettes with humidity control function. The steps are the same as those in Embodiment 1, and the difference in process parameters from Embodiment 1 lies in that bleached kraft bamboo pulp, bleached kraft softwood pulp, and bleached kraft hardwood pulp are broken into a mixed fiber suspension with a mass concentration of 6% according to the mass percentage of 10%:80%:10%. After beating, the Schopper-Riegler beating degree of the mixed pulp fibers is 55°SR; hydroxyapatite ultra-long nanowires with a diameter of 40 nm and a length of 2 mm are added to the mixed pulp fiber suspension according to the mass percentage of 300 g / kg of oven-dried pulp fibers, and then diluted with water to a mass concentration of 0.5%. After mechanical stirring, filtration and forming, pressing (pressure is 10 MPa, pressing time is 2 min), and drying (drying temperature is 100 °C, drying time is 90 min), a composite fiber layer of an aluminum-free inner liner paper base paper for cigarettes with humidity control function is obtained; sepiolite nanoparticles with a particle size of 60 nm prepared in Embodiment 2 are selected; the sepiolite nanoparticles with a particle size of 60 nm and carboxylated nanocellulose fibers are configured into a suspension with a mass concentration of 1% according to the mass percentage of 25%:20%, and then subjected to high-pressure homogenization treatment with the same process parameters as in Embodiment 1; carboxymethyl cellulose is added to the above-mentioned homogenized suspension according to the addition ratio of 90% of the mass percentage of carboxymethyl cellulose in the dynamic humidity control layer. Then, it is diluted with water to a mass concentration of 0.1% to obtain a composite coating solution; the composite coating solution is transferred to one side of the composite fiber layer of the aluminum-free inner liner paper base paper for cigarettes by a curtain coating process and dried (drying temperature is 120 °C, drying time is 5 min).

[0091] The application performance of the aluminum-free inner liner paper base paper for cigarettes with humidity control function prepared in this embodiment is shown in Table 4:

[0092] Table 4. Performance indicators of the aluminum-free inner liner paper base paper for cigarettes with humidity control function

[0093]

[0094] The application performance indicators of the aluminum-free inner liner paper base paper for cigarettes with humidity control function prepared in this embodiment meet the quality requirements of the inner liner paper base paper. After being tried by subsequent manufacturers of aluminum-free inner liner paper for cigarettes, the feedback results show that compared with the inner liner paper base paper on the market, the inner liner paper base paper prepared in this Embodiment 4 has better softness, higher surface strength, and a denser surface structure.

[0095] Embodiment 5

[0096] This embodiment provides a method for preparing a tobacco aluminum-free inner liner base paper with humidity regulation function. The steps and most of the process parameters are the same as those in Embodiment 1. The differences in the process parameters compared with Embodiment 1 are as follows: The hydroxyapatite ultra-long nanowires are added to the mixed pulp fiber suspension according to the mass percentage of 50 g / kg of the pulp fiber based on the absolute dry weight. The sepiolite nanoparticles with a particle size of 50 nm prepared in Embodiment 3 are selected. The sepiolite nanoparticles and the carboxylated nanocellulose fibers are configured into a suspension with a mass concentration of 2% according to the mass percentage of 30%:5%, and then mixed with carboxymethyl cellulose and diluted to a mass concentration of 1% to obtain a composite coating solution.

[0097] The application performance of the tobacco aluminum-free inner liner base paper with humidity regulation function prepared in this embodiment is shown in Table 5:

[0098] Table 5. Performance indicators of the tobacco aluminum-free inner liner base paper with humidity regulation function

[0099]

[0100]

[0101] The application performance indicators of the tobacco aluminum-free inner liner base paper with humidity regulation function prepared in this embodiment meet the quality requirements of the inner liner base paper. After being tried by the subsequent tobacco aluminum-free inner liner paper manufacturers, the feedback results show that compared with the inner liner base paper on the market, the inner liner base paper prepared in this Embodiment 5 has better softness, higher surface strength and denser surface structure.

[0102] The dynamic humidity regulation performance of the above-mentioned Embodiments 1-5 and three comparative samples purchased from the market was tested and characterized.

[0103] The dynamic humidity regulation performance is characterized by testing the wet capacity, average moisture absorption rate, moisture release amount, and average moisture release rate of the sample. The high-temperature and high-humidity environment selected during the test is 38°C, 90% RH, and the dry environment is 38°C, 20% RH.

[0104] The moisture absorption performance is characterized by testing the wet capacity and average moisture absorption rate of the sample. Wet capacity: Reflects the moisture retention ability of the sample; the larger the value, the better the moisture retention ability; unit: g / g. Average moisture absorption rate: Reflects the ability of the sample to adsorb moisture quickly; the larger the value, the better the moisture absorption response ability of the sample to the high-humidity environment; unit: g / (g·h). The sample is first dried to a constant weight in an oven at 105°C. Then, it is placed in a constant-temperature and constant-humidity box at 38°C, 90% RH and weighed regularly. The experiment is stopped after the sample mass reaches a constant weight, and the mass of the sample at the end of moisture absorption, the absolute dry mass of the sample, and the moisture absorption time are recorded. The wet capacity and average moisture absorption rate are calculated according to the following formulas:

[0105] Moisture capacity = (mass of the sample at the end of moisture absorption - dry mass of the sample) * 100 / dry mass of the sample

[0106] Average moisture absorption rate = moisture capacity * 1000 / moisture absorption time

[0107] The moisture release performance is characterized by testing the moisture release amount and average moisture release rate of the sample. Moisture release amount: It reflects the moisture release ability of the sample; the larger the value, the better the moisture release ability; unit: g / g. Average moisture release rate: It reflects the ability of the sample to release moisture quickly; the larger the value, the better the moisture release response ability of the sample to the dry environment; unit: g / (g·h). The sample is first placed in a constant temperature and humidity container at 38°C and 90% RH to absorb moisture until it reaches a constant weight (obtaining the initial mass of the sample). Then, it is placed in a constant temperature and humidity chamber at 38°C and 20% RH, and the mass of the sample is weighed at regular intervals. The experiment stops after the mass of the sample reaches a constant weight, and the mass of the sample after moisture release and reaching a constant weight, the initial mass of the sample, and the moisture release time are recorded. The moisture release amount and average moisture release rate are calculated according to the following formulas:

[0108] Moisture release amount = (initial mass of the sample - mass of the sample after moisture release and reaching a constant weight) * 100 / mass of the sample after moisture release and reaching a constant weight

[0109] Average moisture release rate = moisture release amount * 1000 / moisture release time

[0110] The test results of Examples 1 - 5 of the present invention and three comparative samples purchased from the market are shown in Table 6:

[0111] Table 6 Test results of the dynamic humidity control performance of Examples 1 - 5 and Comparative Samples 1 - 3

[0112]

[0113]

[0114] Based on Table 6, compared with Comparative Samples 1 - 3 purchased from the market, the values of the moisture capacity and average moisture absorption rate characterizing the moisture absorption performance, and the values of the moisture release amount and average moisture release rate characterizing the moisture release performance in Examples 1 - 5 are much larger. The test results show that Examples 1 - 5 have excellent dynamic humidity control performance, while Comparative Samples 1 - 3 basically do not have the ability of dynamic humidity control. In addition, by comparing the humidity control performance test data of Examples 1 - 5, it is found that there are slight differences in the humidity control performance among the five examples, which are mainly due to the differences in the content and ratio of the organic humidity control materials - hydroxyapatite ultra-long nanowires and carboxymethyl cellulose and the inorganic humidity control material - sepiolite nanoparticles among the implementation schemes. However, these differences have little impact on the humidity control performance of the final aluminum-free inner liner paper-based paper for cigarettes, indicating that the implementation schemes of the present invention have strong operability and are easy to realize large-scale industrial application in the future.

[0115] The present invention has been described in detail by way of preferred embodiments. However, the above-described embodiments merely represent several embodiments of the present invention. Although their descriptions are relatively detailed and specific, they should not be construed as limiting the scope of the present invention patent. It is obvious to those skilled in the art to make additions or changes to each embodiment through the study of the foregoing. The applicant's intention is that all such changes and additions fall within the protection scope of the claims of the present invention. The terms used herein are only for the purpose of explaining and illustrating specific embodiments, and are not intended to limit the present invention. Any modification, deformation, and improvement made without departing from the concept of the present invention fall within the protection scope of the present invention.

Claims

1. A tobacco-free aluminum inner liner paper base paper with a humidity control function, characterized in that, The aluminum-free cigarette inner liner paper base paper with humidity control function comprises a composite fiber layer and a dynamic humidity control layer; wherein, the composite fiber layer is composed of three pulp fibers, namely bleached kraft bamboo pulp, bleached kraft softwood pulp, bleached kraft hardwood pulp, and an inorganic synthetic material, i.e., hydroxyapatite ultra-long nanowires; the dynamic humidity control layer is composed of carboxymethyl cellulose, sepiolite nanoparticles, and carboxylated nanofibrillated cellulose; The preparation method of the aluminum-free cigarette inner liner paper base paper with humidity control function comprises the following steps: S1: Pulverize bleached kraft bamboo pulp, bleached kraft softwood pulp, and bleached kraft hardwood pulp into a mixed pulp suspension with a mass concentration of 3-6%, and conduct beating treatment; S2: After adding hydroxyapatite ultra-long nanowires with an addition amount of 50-400 g / kg of absolute dry pulp fibers in the composite fiber layer to the above-mentioned beaten mixed pulp fiber suspension, dilute the mixed suspension to a mass concentration of 0.2-1%, and obtain the fiber composite layer of the aluminum-free cigarette inner liner paper base paper through mechanical stirring, vacuum filtration and forming, pressing, and drying. Among them, the diameter of the hydroxyapatite ultra-long nanowires is 1-100 nm, and the length is 10 μm-5 mm; S3: Mix sepiolite nanoparticles and carboxylated nanofibrillated cellulose to form a suspension with a mass concentration of 0.5-2%, and conduct treatment with a high-pressure homogenizer at a homogenization pressure of 50-200 Mpa for 3-6 times; S4: Add carboxymethyl cellulose to the above-mentioned homogenized suspension according to the addition ratio of the mass percentage content of carboxymethyl cellulose in the dynamic humidity control layer being 50-90%, and then dilute it to a mass concentration of 0.2-1% to obtain a composite coating solution; S5: Through one of the coating processes of bar coating, curtain coating, or blade coating, transfer the above-mentioned composite coating solution to the fiber composite layer of the aluminum-free cigarette inner liner paper base paper by single-sided coating, and after drying, obtain the aluminum-free cigarette inner liner paper base paper including a fiber composite layer and a dynamic humidity control layer; The preparation method of the sepiolite nanoparticles comprises: (1) After washing and purifying and removing impurities from natural sepiolite, prepare a sepiolite suspension with a mass concentration of 50-70%, place it in a planetary mill and grind for 1-3 h, and the rotation speed of the mill is 200-1000 r / min; (2) Add sodium polyacrylate dispersant to the initially ground sepiolite suspension, and adjust the mass concentration of the suspension to 40-80%. The addition amount of sodium polyacrylate dispersant is 2-7 g / kg of absolute dry sepiolite, and then place it in a nano mill and grind for 2-5 h. The rotation speed of the nano mill is 500-1200 r / min; (3) After concentrating the sepiolite suspension treated by the nano mill, conduct freeze-drying treatment to obtain sepiolite nanoparticles.

2. The tobacco-free aluminum inner liner paper base paper with a humidity adjustment function according to claim 1, characterized in that, In the composite fiber layer, the mass percentage content of the bleached kraft bamboo pulp is 10-20%, the mass percentage content of the bleached kraft softwood pulp is 40-80%, and the mass percentage content of the bleached kraft hardwood pulp is 10-25%.

3. The tobacco-free aluminum inner liner base paper with a humidity adjustment function according to claim 1, characterized in that, The three kinds of pulp fibers, namely bleached kraft bamboo pulp, bleached kraft softwood pulp and bleached kraft hardwood pulp, are treated by a mixed pulping process, and the Schopper-Riegler beating degree of the mixed pulp fibers after pulping is 25-60°SR.

4. The base paper for tobacco use without aluminum inner lining paper with humidity control function according to claim 1, characterized in that, In the dynamic humidity conditioning layer, the mass percentage content of the carboxymethyl cellulose is 50-90%, the mass percentage content of the sepiolite nanoparticles is 10-30%, and the mass percentage content of the carboxylated nanofibrillated cellulose is 5-20%, and the sum of the dosages of the above components is 100%.

5. The base paper for aluminuim-free cigarette inner lining paper with humidity conditioning function according to claim 1, characterized in that, The relative molecular mass of the carboxymethyl cellulose is 90,000-300,000, the degree of substitution (DS) is 0.7-1.2, the average particle size of the sepiolite nanoparticles is 50-300 nm, the diameter of the carboxylated nanofibrillated cellulose is 10-100 nm, the length is 0.1-2 mm, and the carboxyl content is 0.5-2.0 mmol / g.

6. The tobacco-free aluminum inner liner paper base paper with humidity adjustment function according to claim 1, characterized in that, The basis weight of the composite fiber layer of the aluminum-free inner liner paper for cigarettes with humidity control function is 55 to 65 g / m 2 , and the coating amount of the dynamic humidity control layer of the aluminum-free inner liner paper for cigarettes with humidity control function is 0.5 to 2 g / m 2 .

7. A tobacco-free aluminum inner liner paper base paper with humidity conditioning function prepared by the method according to any one of claims 1-6.

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