Highly heat-conductive, anti-permeation and mechanically durable cigarette paper and preparation method thereof

Abstract

The application discloses a high-thermal-conductivity, anti-permeation and mechanically durable cigarette paper and a preparation method thereof. Under the synergistic stabilization of dispersants, emulsifiers and modifiers, the amorphous aggregation of nanosheets can be effectively weakened, and the dispersion stability between the nanosheets and the mixed fiber matrix can be improved. The water absorption and swelling and fine fiberization of fibers are generated by treating the fibers in water through mechanical action, so that the specific surface area of the fibers is increased, a large number of hydroxyl groups are generated on the surface of the fibers, the loose connection of hydrogen bonds of fiber-water-fiber is formed through the dipole water and the fibers, and the physical properties of the paper are improved. The content of the amino modifier on the surface of the nanosheets is adjusted to realize the regulation of the positive charge on the surface of the nanosheets, the layer-by-layer assembly of the nanosheets is realized through the charge interaction between the fibers and the nanosheets, the interface structure with the ordered stacking of the nanosheets is constructed, and the mechanical properties of the composite cigarette paper and the thermal conductivity of the matrix are greatly enhanced.

Description

Technical Field

[0001] This invention relates to a type of cigarette paper with high thermal conductivity, impermeability, and mechanical durability, and its preparation method. Background Technology

[0002] Unlike traditional cigarettes, heated cigarettes typically use a heat source to heat the tobacco-producing material, generating an aerosol with a tobacco flavor. This process does not require the tobacco to burn. The tobacco-producing material is usually tobacco sheet, and to increase the amount of smoke and enhance the product experience, large amounts of smoke-producing agents such as glycerol and propylene glycol are often added. These smoke-producing agents generally have strong hygroscopic properties, easily absorbing moisture from the air. During long-term storage, the liquid in the tobacco-producing material of heated cigarettes can easily seep through the cigarette paper, causing yellow spots and other colored blemishes on the cigarette surface, affecting the product's appearance. Furthermore, during cigarette processing and smoking, there are often issues such as slow paper burning and paper breakage.

[0003] To address the aforementioned issues, there is an urgent need to develop novel heated cigarette paper that meets the requirements of high thermal conductivity, impermeability, and mechanical durability. Two-dimensional materials are nanomaterials with a sheet-like morphology, ranging in size from hundreds of nanometers to tens of micrometers or even larger in lateral dimensions, but with a thickness of only one or a few atomic layers. Compared to bulk materials, electrons in two-dimensional materials are confined within a two-dimensional structure. This unique structural feature endows them with a variety of unconventional physicochemical properties, and they have been applied in numerous research fields. Summary of the Invention

[0004] This invention aims to provide a high thermal conductivity, impermeability, and mechanical durability cigarette paper and its preparation method. The method for preparing a cellulose / two-dimensional layered nanosheet composite cigarette paper with controllable two-dimensional nanosheet size, good dispersion stability, and high degree of composite between cellulose and two-dimensional layered nanosheets achieves in-situ composite of fibers with two-dimensional layered nanosheets.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by the present invention includes the following steps:

[0006] Step 1: Add the chopped fibers to an aqueous solution containing emulsifier, adjust the temperature to 20℃~70℃, soak for 0.5h~24h, then wash repeatedly with deionized water 3 times, and finally store in a vacuum oven at 80℃~120℃ for 0.5h~24h for later use.

[0007] After storing the microfiber in a vacuum oven for 0.5–6 hours, heat-treat it at 100℃–180℃ for 0.5–24 hours under a vacuum of 0.2 MPa–5 MPa. Then, place the heat-treated microfiber in a homogenizer and add deionized water, where the mass of microfiber is 0.5%–10% of the total mass of deionized water; the mass of emulsifier is 5%–10% of the total mass of deionized water. Homogenize at 5000–25000 rpm for 0.5–60 minutes to loosen the pulp; then beat it for 0.5–60 minutes to obtain microfiber pulp. Filter and dry the pulp to obtain microfiber pulp meal.

[0008] The total ionized water refers to the total amount of ionized water added in batches throughout the entire invention process.

[0009] Step 2: Add two-dimensional layered nanosheets to a modified solvent, and sonicate to obtain a uniform dispersion of two-dimensional layered nanosheets. Then, add an amino modifier, adjust the temperature to 30℃~60℃, and react for 0.5h~72h. After purification and drying, amino-modified two-dimensional layered nanosheets are obtained. The mass amount of the two-dimensional layered nanosheets is 0.05%~3.0% of the mass amount of the modified solvent, and the mass amount of the amino modifier is 0.1%~50.0% of the mass amount of the two-dimensional layered nanosheets.

[0010] Step 3: Add chopped fibers and ultrafine fiber pulp to a fiber dissociator containing deionized water and a dispersant, and mix evenly. The mass ratio of chopped fibers to ultrafine fiber pulp is 1:1 to 9:1. The mass amount of dispersant is 0.5% to 12% of the total mass of the mixed fibers (chopped fibers and ultrafine fiber pulp). The mass amount of two-dimensional layered nanosheets is 0.05% to 10% of the total mass of the mixed fibers. The rotation speed of the dissociator is 800 rpm to 8000 rpm. After dissociation for 0.5 min to 60 min, a uniformly dispersed ultrafine fiber mixed slurry is obtained.

[0011] Step 4: The microfiber mixed slurry is directly wet-formed on a paper forming machine, with a web concentration of 0.01%–2%. The resulting microfiber mixed base paper is dried in a forced-air oven at 110℃ for 3 hours to obtain the microfiber mixed base paper. The paper basis weight is controlled at 30–60 g / m². 2 The base paper is then hot-pressed on a hot roll mill at a temperature of 200℃ to 350℃, a pressure of 0.1MPa to 2MPa, and a roll speed of 0.01 to 1m / min. The composite cigarette paper is obtained by hot-pressing 1 to 3 times.

[0012] In step (1) of this invention, the chopped fibers are selected from at least one of the following: pine fiber, cypress fiber, fir fiber, poplar fiber, eucalyptus fiber, willow fiber, Chinese mahogany fiber, acacia fiber, bamboo fiber, reed fiber, stalk fiber, bagasse fiber, wheat straw fiber, cotton fiber, agave fiber, banana leaf fiber, sugarcane leaf fiber, and grass fiber.

[0013] In step (1) of this invention, the emulsifier is selected from at least one of the following: Tween series emulsifiers, OP series emulsifiers, MOA series emulsifiers, alkyl sulfonate emulsifiers, alkylbenzene sulfonate emulsifiers, alkyl sulfate emulsifiers, alkyltrimethylammonium halide emulsifiers, and betaine emulsifiers. The Tween series emulsifier can be one or a combination of several of Tween-20, Tween-40, Tween-60, or Tween-80; the OP series emulsifier can be one or a combination of several of OP-7, OP-10, OP-15, or OP-20; and the MOA series emulsifier can be one or a combination of several of MOA-3, MOA-7, and MOA-9. The alkyl sulfonate emulsifier can be R7-SO3M, where R7 is a C12-C20 aliphatic chain and M is Na. + or K + Alkylbenzene sulfonate emulsifiers can be R8-C6H4-SO3M, where R8 is a C10-C18 aliphatic chain and M is Na. + or K + Alkyltrimethylammonium halide emulsifier is R9N + (CH3)3X - Where R9 is a C12–C20 aliphatic chain, and X is Cl or Br; the betaine emulsifier can be carboxylic acid betaine (R 10 N + (CH3)2CH2COO - , where R 10 (C12-C18 aliphatic chains), sulfonyl betaine (R) 11 N + (CH3)2CH2CH2SO3 - Or R 12 N + (CH3)2CH2CH2CH2SO3 - , where R 11 and R 12 (Aliphatic chains of C12 to C18).

[0014] In step (1) of this invention, the microfiber is selected from at least one of the following: kenaf fiber, hemp fiber, jute fiber, ramie fiber, flax fiber, acetate fiber, polyvinyl alcohol fiber, etc.

[0015] In step (2) of this invention, the two-dimensional layered nanosheets are selected from at least one of the following: flake vermiculite, molybdenum disulfide, flake magnesium oxide, flake zinc oxide, hexagonal boron nitride, and flake graphite.

[0016] In step (2) of the present invention, the average lateral size of the two-dimensional layered nanosheets is between 300 nm and 2500 nm. Considering the dispersion effect of cellulose and nanosheets, as a preferred embodiment, the average lateral size of the amino-modified two-dimensional layered nanosheets is between 500 nm and 800 nm.

[0017] In step (2) of this invention, considering the dispersibility and modification efficiency of the two-dimensional layered nanosheets in the modifying solvent, the preferred mass amount of the two-dimensional layered nanosheets is 0.1% to 2.5% of the mass amount of the modifying solvent. The preferred mass amount of the amino modifier is 0.5% to 20.0% of the mass amount of the two-dimensional layered nanosheets.

[0018] In step (2) of this invention, the modified solvent is selected from at least one of the following: ethanol, isopropanol, water, and dimethyl sulfoxide. Considering environmental protection and food safety issues, the modified solvent is preferably at least one of ethanol and water.

[0019] In step (2) of this invention, the amino modifier is selected from at least one of the following: urea, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, polyethyleneimine, glycine, alanine, leucine, valine, tryptophan, serine, glutamine, threonine, asparagine, tyrosine, and aspartic acid.

[0020] Considering the modification efficiency and reactivity of the nanosheet surface, the amino modifier is preferably selected from at least one of the following: urea, 3-aminopropyltrimethoxysilane, 3-aminopropylethoxysilane, tryptophan, glutamine, tyrosine, and aspartic acid.

[0021] In step (2) of this invention, taking into account the dispersion ability of modified two-dimensional layered nanosheets in the fiber matrix, the adhesive properties of cellulose, and the thermal conductivity and mechanical strength of cellulose, the preferred mass amount of amino-modified nanosheets is 0.5% to 10% of the mass amount of mixed fibers.

[0022] In step (3) of this invention, the dispersant is selected from at least one of the following: polyethylene oxide, polyacrylamide, polyvinyl alcohol, sodium lignosulfonate, maleic anhydride-styrene copolymer, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, gelatin, and sodium alginate.

[0023] In step (3) of the present invention, considering the adhesion strength between cellulose and two-dimensional nanosheets, the dispersant is preferably selected from at least one of the following: polyvinyl alcohol, sodium lignosulfonate, maleic anhydride-styrene copolymer, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, gelatin, and sodium alginate.

[0024] In step (3) of the present invention, considering the air permeability of the paper, the mass of the dispersant is preferably 3% to 8% of the total mass of the mixed fibers.

[0025] In step (4) of the present invention, considering the tensile strength of cigarette paper, the pulp concentration on the wire is preferably 0.05% to 1.5%.

[0026] In step (4) of the present invention, considering the transparency of the paper, the hot pressing temperature is preferably 260℃~320℃, the hot pressing pressure is preferably 0.5MPa~1.2MPa, and the roller speed is preferably 0.1~0.5m / min.

[0027] In this invention, the amylation modification of two-dimensional layered nanosheets is used to improve the surface charge and steric hindrance effect of the nanosheets, promote the dispersion of the nanosheets in the fiber matrix, and also endow the nanosheets with the ability to assemble through layer-by-layer interfaces, enabling the nanosheets to access the hybrid network of cellulose through multiple hydrogen bonds, and improving the thermal interface bonding strength between the fiber matrix and the nanosheets.

[0028] Through in-depth research, the inventors discovered that the synergistic stabilizing effect of dispersants, emulsifiers, and modifiers can effectively weaken the amorphous aggregation of nanosheets and improve the dispersion stability between nanosheets and the mixed fiber matrix. By using chopped fibers and ultrafine fibers in water as a medium, and through mechanical processes, the fibers absorb water, swell, and become finer, thereby increasing the specific surface area of ​​the fibers and generating a large number of hydroxyl groups on the fiber surface. These hydroxyl groups form loose fiber-water-fiber bonds with the fibers via dipole water, improving the physical properties of the paper. In this process, the positive charge on the nanosheet surface is controlled by adjusting the content of amino modifiers. Through the charge interaction between the fibers and nanosheets, the nanosheets are assembled layer by layer, constructing an interface structure with ordered stacking of nanosheets, significantly enhancing the mechanical properties of the composite cigarette paper and the thermal conductivity of the matrix.

[0029] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0030] Aminolation modification of the surface of two-dimensional layered nanosheets is used to regulate their surface charge characteristics and endow them with reactive capabilities. Within the framework of interfacial assembly technology of cellulose macromolecules, in-situ composite of nanosheets and cellulose matrix is ​​achieved through multiple hydrogen bonds and electrostatic interactions, efficiently preparing cellulose / two-dimensional layered nanosheet composite cigarette paper with thermal and mechanical properties. The advantages of this method are: (1) Surface aminolation modification of two-dimensional layered nanosheets can improve the dispersion uniformity of two-dimensional layered nanosheets in the fiber matrix and endow them with the ability to participate in interfacial assembly; (2) The formulation design of cellulose / two-dimensional layered nanosheets is diverse, the preparation process is simple, and it is easy to implement industrially; (3) Through the effective composite of cellulose and two-dimensional layered nanosheets, the material is endowed with excellent thermal and mechanical properties, making it more valuable for high-end fields such as military industry, electronic components, and automobiles. Attached Figure Description

[0031] Figure 1 These are scanning electron microscope (SEM) images of the composite cigarette paper of Comparative Example 1 (left) and the composite cigarette paper of Example 2 of the present invention. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0033] This invention proposes using two-dimensional layered nanosheets as a functional component. Through in-situ modification of the two-dimensional nanosheets, surface amino functional groups are introduced, enhancing surface activity and promoting the dispersion of the two-dimensional nanosheets in water and the formation of hydrogen bonds between fibers. By subjecting the modified two-dimensional layered nanosheets to a dispersion of ultrafine fibers through pulping, papermaking, and hot pressing, high thermal conductivity, impermeability, and mechanical durability of cigarette paper is achieved. The van der Waals forces between the nanosheets and the improved surface charge characteristics enhance the dispersion uniformity of the nanosheets in water and the fiber matrix. Furthermore, the nanosheets participate in the formation of a cellulose thermally conductive network through layer-by-layer self-assembly, thereby endowing the cigarette paper with excellent thermal conductivity, impermeability, and mechanical properties.

[0034] Example 1:

[0035] 336.6g of pine fiber and 5.035g of sodium dodecylbenzenesulfonate were added to 95g of water, and the temperature was adjusted to 40℃ for 4 hours. The mixture was then rinsed three times with deionized water and finally stored in a vacuum oven at 110℃ for 3 hours. 37.4g of flax fiber was stored in a vacuum oven for 6 hours, then heat-treated at 150℃ for 2 hours under a negative pressure of 0.8MPa. The heat-treated flax fiber was then placed in a homogenizer and homogenized at 20,000 rpm for 15 minutes to loosen it. It was then beaten for 30 minutes to obtain ultrafine fiber pulp, which was filtered, dried, and used to obtain ultrafine fiber pulp.

[0036] 10g of flake vermiculite (550nm transverse dimension) was added to 769g of ethanol and ultrasonically treated to obtain a uniform flake vermiculite dispersion. Then, 0.13g of urea was added, and the mixture was reacted at 55℃ for 12h. After purification and drying, amino-modified flake vermiculite was obtained. 336.6g of pine fiber and 37.4g of flax fiber pulp were added to a fiber dissociator containing 4.86g of polyacrylamide and deionized water, and mixed evenly. The mass ratio of pine fiber to flax fiber pulp was 9:1. The dissociator rotated at 3000rpm, and after dissociation for 20min, a uniformly dispersed fiber mixture was obtained.

[0037] The above pulp was directly wet-formed on a paper forming machine with a web concentration of 0.05%. The formed mixed fiber base paper was then dried in a forced-air oven at 110°C for 3 hours to obtain mixed microfiber base paper. The paper basis weight was controlled at 40 g / m². 2 The base paper is then hot-pressed on a hot roller mill at a temperature of 265°C, a pressure of 0.5 MPa, and a roller speed of 0.3 m / min. The composite cigarette paper is obtained by hot-pressing 1 to 3 times.

[0038] The tensile strength of the composite cigarette paper was determined according to GB / T12914-2018, and the thermal conductivity was determined according to GB / T42483-2023. The air permeability was evaluated by measuring the glycerol contact angle of the cigarette paper samples using a contact angle meter. Before testing, all cigarette paper samples were equilibrated for 4 hours at a temperature of (22±1)℃ and a relative humidity of (60±3)%. The thermal conductivity of the composite cigarette paper was 3.9 W / (m·K), the contact angle was 48°, and the tensile strength was 0.37 kN·m. -1 It has excellent thermal conductivity, impermeability and mechanical properties.

[0039] Comparative Example 1:

[0040] 336.6g of pine fiber and 5.035g of sodium dodecylbenzenesulfonate were added to 95g of water, and the temperature was adjusted to 40℃ for 4 hours. The mixture was then rinsed three times with deionized water and finally stored in a vacuum oven at 110℃ for 3 hours. 37.4g of flax fiber was stored in a vacuum oven for 6 hours, then heat-treated at 150℃ for 2 hours under a negative pressure of 0.8MPa. The heat-treated flax fiber was then placed in a homogenizer and homogenized at 20,000 rpm for 15 minutes to loosen it. It was then beaten for 30 minutes to obtain ultrafine fiber pulp, which was filtered, dried, and used to obtain ultrafine fiber pulp.

[0041] 336.6g of pine fiber and 37.4g of flax fiber pulp were added to a fiber dissociator containing 4.86g of polyacrylamide and deionized water and mixed evenly. The mass ratio of pine fiber to flax fiber pulp was 9:1. The speed of the dissociator was 3000rpm. After dissociation for 20min, a uniformly dispersed fiber mixture was obtained.

[0042] The above pulp was directly wet-formed on a paper forming machine with a web concentration of 0.05%. The formed mixed fiber base paper was then dried in a forced-air oven at 110°C for 3 hours to obtain mixed microfiber base paper. The paper basis weight was controlled at 40 g / m². 2 The base paper is then hot-pressed on a hot roller mill at a temperature of 265°C, a pressure of 0.5 MPa, and a roller speed of 0.3 m / min. The composite cigarette paper is obtained by hot-pressing 1 to 3 times.

[0043] The same sample processing conditions and testing methods as in Example 1 were used. The composite cigarette paper had a thermal conductivity of 0.06 W / (m·K), a contact angle of 30°, and a tensile strength of 0.12 kN·m. -1 It has almost no thermal conductivity and poor impermeability and mechanical properties.

[0044] Comparative Example 2:

[0045] 336.6g of pine fiber and 5.035g of sodium dodecylbenzenesulfonate were added to 95g of water, and the temperature was adjusted to 40℃ for 4 hours. The mixture was then rinsed three times with deionized water and finally stored in a vacuum oven at 110℃ for 3 hours. 37.4g of flax fiber was stored in a vacuum oven for 6 hours, then heat-treated at 150℃ for 2 hours under a negative pressure of 0.8MPa. The heat-treated flax fiber was then placed in a homogenizer and homogenized at 20,000 rpm for 15 minutes to loosen it. It was then beaten for 30 minutes to obtain ultrafine fiber pulp, which was filtered, dried, and used to obtain ultrafine fiber pulp.

[0046] 3.37 g of flaky vermiculite (lateral dimension 550 nm) was added to 259 g of ethanol and ultrasonically treated to obtain a uniform flaky vermiculite dispersion. Then, 0.13 g of urea was added, and the mixture was reacted at 55 °C for 12 h. After purification and drying, amino-modified flaky vermiculite was obtained. 336.6 g of pine fiber and 37.4 g of flax fiber pulp were added to a fiber dissociator containing 4.86 g of polyacrylamide and deionized water, and mixed evenly. The mass ratio of pine fiber to flax fiber pulp was 9:1. The dissociator rotated at 3000 rpm, and after dissociation for 20 min, a uniformly dispersed fiber mixture was obtained.

[0047] The above pulp was directly wet-formed on a paper forming machine with a web concentration of 0.05%. The formed mixed fiber base paper was then dried in a forced-air oven at 110°C for 3 hours to obtain mixed microfiber base paper. The paper basis weight was controlled at 40 g / m². 2 The base paper is then hot-pressed on a hot roller mill at a temperature of 265°C, a pressure of 0.5 MPa, and a roller speed of 0.3 m / min. The composite cigarette paper is obtained by hot-pressing 1 to 3 times.

[0048] The same sample processing conditions and testing methods as in Example 1 were used. The composite cigarette paper has a thermal conductivity of 3.2 W / (m·K), a contact angle of 45°, and a tensile strength of 0.32 kN·m. -1 It has excellent thermal conductivity, impermeability and mechanical properties.

[0049] Example 2:

[0050] 270.1g of bamboo fiber and 8.04g of Tween 20 were added to 120g of water, and the temperature was adjusted to 50℃ for 2 hours. The mixture was then rinsed three times with deionized water and finally stored in a vacuum oven at 105℃ for 5 hours. 101.3g of cellulose acetate was stored in a vacuum oven for 6 hours, then heat-treated at 160℃ for 1 hour under a negative pressure of 1.2MPa. The heat-treated cellulose acetate was then placed in a homogenizer and homogenized at 18000rpm for 20 minutes to loosen the pulp. It was then beaten for 25 minutes to obtain ultrafine fiber pulp, which was filtered, dried, and used to obtain ultrafine fiber pulp.

[0051] 12g of flake magnesium oxide (340nm transverse dimension) was added to 800g of water and ultrasonically treated to obtain a uniform flake magnesium oxide dispersion. Then, 1.04g of 3-aminopropyltrimethoxysilane was added, and the mixture was reacted at 40℃ for 18h. After purification and drying, amino-modified flake magnesium oxide was obtained. 270.1g of bamboo fiber and 101.3g of cellulose acetate pulp were added to a fiber dissociator containing 13.7g of sodium lignosulfonate and deionized water, and mixed evenly. The mass ratio of bamboo fiber to cellulose acetate pulp was 8:3. The dissociator rotated at 5000rpm, and after 7min of dissociation, a uniformly dispersed fiber mixture was obtained.

[0052] The above pulp was directly wet-formed on a paper forming machine with a web concentration of 0.08%. The formed mixed fiber base paper was then dried in a forced-air oven at 105°C for 5 hours to obtain mixed microfiber base paper. The paper basis weight was controlled at 42 g / m². 2 The base paper is then hot-pressed on a hot roller mill at a temperature of 280°C, a pressure of 0.3 MPa, and a roller speed of 0.5 m / min. The composite cigarette paper is obtained by hot-pressing 1 to 3 times.

[0053] The same sample processing conditions and testing methods as in Example 1 were used. The composite cigarette paper had a thermal conductivity of 4.5 W / (m·K), a contact angle of 50°, and a tensile strength of 0.43 kN·m. -1 It has excellent thermal conductivity, impermeability and mechanical properties.

[0054] Example 3:

[0055] Add 9.52g of asparagus fiber and 8.5g of OP-10 to 100g of water, adjust the temperature to 50℃, soak for 2 hours, then rinse repeatedly with deionized water 3 times, and finally store in a vacuum oven at 105℃ for 5 hours for later use. Store 4.08g of hemp fiber in a vacuum oven for 6 hours, then heat-treat at 160℃ for 1 hour under a negative pressure of 1.2MPa. After heat-treating, place the hemp fiber in a homogenizer. Homogenize at 18000rpm for 20 minutes to loosen the fibers; then beat for 25 minutes to obtain ultrafine fiber pulp. Filter, dry, and obtain ultrafine fiber pulp.

[0056] 0.5 g of boron nitride (lateral dimension 630 nm) was added to 71.4 g of water and ultrasonically treated to obtain a uniform boron nitride dispersion. Then, 0.083 g of 3-aminopropyltriethoxysilane was added, and the mixture was reacted at 40 °C for 18 h. After purification and drying, amino-modified boron nitride was obtained. 9.52 g of asparagus fiber and 4.08 g of hemp fiber pulp were added to a fiber dissociator containing 13.7 g of sodium lignosulfonate and deionized water, and mixed evenly. The mass ratio of asparagus fiber to hemp fiber pulp was 7:3. The dissociator rotated at 5000 rpm, and after 5 min of dissociation, a uniformly dispersed fiber mixture was obtained.

[0057] The above-mentioned pulp was directly wet-formed on a paper forming machine with a web concentration of 0.17%. The formed mixed fiber base paper was then dried in a forced-air oven at 105°C for 5 hours to obtain mixed microfiber base paper. The paper basis weight was controlled at 45 g / m². 2 The base paper is then hot-pressed on a hot roller mill at a temperature of 280°C, a pressure of 0.3 MPa, and a roller speed of 0.5 m / min. The composite cigarette paper is obtained by hot-pressing 1 to 3 times.

[0058] The same sample processing conditions and testing methods as in Example 1 were used. The composite cigarette paper had a thermal conductivity of 1.4 W / (m·K), a contact angle of 15°, and a tensile strength of 0.18 kN·m. -1 It has good thermal conductivity, impermeability and mechanical properties.

[0059] Example 4:

[0060] 96.3g of wheat straw fiber and 9.66g of MOA-9 were added to 105g of water, and the temperature was adjusted to 30℃ for 12 hours. The mixture was then rinsed three times with deionized water and finally stored in a vacuum oven at 100℃ for 8 hours. 64.2g of jute fiber was stored in a vacuum oven for 6 hours, then heat-treated at 140℃ for 5 hours under a negative pressure of 0.6MPa. The heat-treated jute fiber was then placed in a homogenizer and homogenized at 22000rpm for 10 minutes to loosen it. It was then beaten for 20 minutes to obtain ultrafine fiber pulp, which was filtered, dried, and used to obtain ultrafine fiber pulp.

[0061] 8g of flake zinc oxide (735nm transverse dimension) was added to 479g of ethanol and ultrasonically treated to obtain a uniform zinc oxide dispersion. Then, 1.792g of tryptophan was added, and the mixture was reacted at 45℃ for 16h. After purification and drying, amino-modified zinc oxide was obtained. 96.3g of wheat straw fiber and 64.2g of jute fiber pulp were added to a fiber dissociator containing 13.6g of hydroxypropyl methylcellulose and deionized water, and mixed thoroughly. The mass ratio of wheat straw fiber to jute fiber pulp was 3:2. The dissociator rotated at 5000rpm, and after 5min of dissociation, a uniformly dispersed fiber mixture was obtained.

[0062] The above-mentioned pulp was directly wet-formed on a paper forming machine with a web density of 1.3%. The formed mixed fiber base paper was then dried in a forced-air oven at 100°C for 8 hours to obtain mixed microfiber base paper. The paper basis weight was controlled at 50 g / m². 2 The base paper is then hot-pressed on a hot roll mill at a temperature of 300°C, a pressure of 0.8 MPa, and a roll speed of 0.6 m / min. The composite cigarette paper is obtained by hot-pressing 1 to 3 times.

[0063] The same sample processing conditions and testing methods as in Example 1 were used. The composite cigarette paper has a thermal conductivity of 1.7 W / (m·K), a contact angle of 34°, and a tensile strength of 0.35 kN·m. -1 It has good thermal conductivity, impermeability and mechanical properties.

[0064] Example 5:

[0065] 79.9g of sugarcane leaf fiber and 7.1g of sodium dodecyl sulfonate were added to 100g of water, and the temperature was adjusted to 50℃ for 15 hours. The mixture was then rinsed three times with deionized water and finally stored in a vacuum oven at 110℃ for 3 hours. 20g of kenaf fiber was stored in a vacuum oven for 6 hours, then heat-treated at 140℃ for 5 hours under a negative pressure of 0.6MPa. The heat-treated kenaf fiber was then placed in a homogenizer and homogenized at 22000rpm for 10 minutes to loosen the fibers. It was then beaten for 15 minutes to obtain ultrafine fiber pulp, which was filtered, dried, and used to obtain ultrafine fiber pulp meal.

[0066] 7.5 g of flake boron nitride (lateral dimension 525 nm) was added to 357 g of water and ultrasonically treated to obtain a uniform flake boron nitride dispersion. Then, 0.39 g of glutamine was added, and the mixture was reacted at 50 °C for 15 h. After purification and drying, amino-modified flake boron nitride was obtained. 79.9 g of sugarcane leaf fiber and 20 g of kenaf fiber pulp were added to a fiber dissociator containing 6.7 g of gelatin and deionized water, and mixed evenly. The mass ratio of sugarcane leaf fiber to kenaf fiber pulp was 4:1. The dissociator rotated at 7500 rpm, and after 3 min of dissociation, a uniformly dispersed fiber mixture was obtained.

[0067] The above pulp was directly wet-formed on a paper forming machine with a web density of 1.5%. The formed mixed fiber base paper was then dried in a forced-air oven at 110°C for 3 hours to obtain mixed microfiber base paper. The paper basis weight was controlled at 55 g / m². 2 The base paper is then hot-pressed on a hot roller mill at a temperature of 300℃, a pressure of 0.8MPa, and a roller speed of 0.8m / min. The composite cigarette paper is obtained by hot-pressing 1 to 3 times.

[0068] The same sample processing conditions and testing methods as in Example 1 were used. The composite cigarette paper had a thermal conductivity of 2.9 W / (m·K), a contact angle of 40°, and a tensile strength of 0.31 kN·m. -1 It has good thermal conductivity, impermeability and mechanical properties.

[0069] Example 6:

[0070] 14.6g of dragon's beard grass fiber and 10.34g of sodium dodecylbenzenesulfonate were added to 110g of water, and the temperature was adjusted to 35℃ for 24 hours. The mixture was then rinsed three times with deionized water and finally stored in a vacuum oven at 100℃ for 8 hours. 8.7g of hemp fiber was stored in a vacuum oven for 6 hours, then heat-treated at 170℃ for 0.5 hours under a negative pressure of 1.5MPa. The heat-treated hemp fiber was then placed in a homogenizer and homogenized at 15000rpm for 35 minutes to loosen it. It was then beaten for 15 minutes to obtain ultrafine fiber pulp, which was filtered, dried, and used to obtain ultrafine fiber pulp.

[0071] 1.4 g of flake boron nitride (lateral dimension 672 nm) was added to 50 g of ethanol and ultrasonically treated to obtain a uniform flake boron nitride dispersion. Then, 0.51 g of aspartic acid was added, and the mixture was reacted at 35 °C for 24 h. After purification and drying, amino-modified flake boron nitride was obtained. 14.6 g of *Eriocaulon buergerianum* fiber and 8.7 g of hemp fiber pulp were added to a fiber dissociator containing 2.2 g of sodium alginate and deionized water, and mixed evenly. The mass ratio of *Eriocaulon buergerianum* fiber to hemp fiber pulp was 5:3. The dissociator rotated at 7500 rpm, and after 1 min of dissociation, a uniformly dispersed fiber mixture was obtained.

[0072] The above-mentioned pulp was directly wet-formed on a paper forming machine with a web density of 1.73%. The formed mixed fiber base paper was then dried in a forced-air oven at 100°C for 8 hours to obtain mixed microfiber base paper. The paper basis weight was controlled at 58 g / m². 2 The base paper is then hot-pressed on a hot roll mill at a temperature of 305°C, a pressure of 0.2 MPa, and a roll speed of 0.8 m / min. The composite cigarette paper is obtained by hot-pressing 1 to 3 times.

[0073] The same sample processing conditions and testing methods as in Example 1 were used. The composite cigarette paper had a thermal conductivity of 0.8 W / (m·K), a contact angle of 27°, and a tensile strength of 0.15 kN·m. -1 It has poor thermal conductivity, impermeability and mechanical properties.

[0074] The specific parameters of the embodiments of the present invention are shown in Tables 1, 2 and 3 below.

[0075] Table 1

[0076]

[0077] Table 2

[0078]

[0079] Table 3

[0080]

[0081] As can be directly seen from Tables 1, 2, and 3, Example 2 of this invention exhibits the best performance, with a thermal conductivity of 4.5 W / (m·K), a contact angle of 50°, and a tensile strength of 0.43 kN·m⁻¹, thus achieving high thermal conductivity, impermeability, and mechanical durability. From the six examples and two comparative examples, it can be seen that the specific material composition and proportion of the two-dimensional layered nanosheets are particularly important for achieving high thermal conductivity, impermeability, and mechanical durability. Specifically, the ratio of the amino modifier to the mass of the two-dimensional layered nanosheets, the ratio of the modified two-dimensional layered nanosheets to the total fiber mass, and the ratio of the dispersant mass to the total mass of the mixed fibers (chopped fibers and ultrafine fiber pulp) have a significant impact on the thermal conductivity, impermeability, and mechanical durability of the high-performance cigarette paper.

[0082] Furthermore, such as Figure 1 The image shown is a scanning electron microscope (SEM) image of the composite cigarette paper of Comparative Example 1 (left) and the composite cigarette paper of Example 2 of the present invention. Figure 1 The left image shows the surface morphology of cigarette paper prepared from pure fibers, while the right image shows the surface morphology of cigarette paper prepared with modified two-dimensional nanosheets. The white particles in the right image represent the thermally conductive network formed by the two-dimensional nanosheets. Due to the amination modification of the surface, the two-dimensional nanosheets and fibers are efficiently and firmly composited under the influence of charge and van der Waals forces, avoiding the shedding and powdering caused by physical mixing. Furthermore, the resulting micro / nano composite fiber network has significant advantages compared to pure fiber networks: the self-assembled network of two-dimensional layered nanosheets improves the thermal conductivity of the fiber matrix; the introduction and orderly stacking of inorganic components help improve the mechanical properties of the fibers; and the gradient micro / nano structure of the two-dimensional layered nanosheets and fibers helps improve the paper's impermeability.

[0083] The above embodiments of the present invention are illustrative and not limiting. Any changes within the meaning and scope of the claims should be considered to be included within the scope of the claims.

Claims

1. A method for preparing a high thermal conductivity, impermeable, and mechanically durable cigarette paper, characterized in that... Includes the following steps: Step 1: Add the chopped fibers to an aqueous solution containing an emulsifier and adjust the temperature to 20°C. o C~70 o C, soak for 0.5h to 24h, then rinse repeatedly with deionized water 3 times, and finally rinse at 80°C. o C~120 o Store in a vacuum oven at temperature C for 0.5 to 24 hours for later use; the emulsifier should be used at a rate of 5% to 10% of the total deionized water mass. After storing the microfiber in a vacuum oven for 0.5–6 hours, the temperature is raised to 100°C. o C~180 o Heat treatment at C for 0.5h to 24h under vacuum of 0.2MPa to 5MPa, followed by placing the heat-treated microfibers in a homogenizer and adding deionized water, wherein the mass of microfibers is 0.5% to 10% of the total mass of deionized water; homogenize at 5000 to 25000 rpm for 0.5min to 60min for loosening; then pulping for 0.5min to 60min to obtain microfiber slurry, which is then filtered, dried, and used to obtain microfiber pulp. Step 2: Add the two-dimensional layered nanosheets to the modified solvent, and sonicate to obtain a uniform dispersion of the two-dimensional layered nanosheets. Then add the amino modifier and adjust the temperature to 30°C. o C~60 o React at C for 0.5 h to 72 h, and after purification and drying, amino-modified two-dimensional layered nanosheets are obtained; wherein the mass amount of amino modifier is 0.5% to 20.0% of the mass amount of the two-dimensional layered nanosheets. Step 3: Add the chopped fibers and ultrafine fiber pulp to a fiber dissociator containing deionized water and a dispersant, and mix them evenly. The mass ratio of chopped fibers to ultrafine fiber pulp is 1:1 to 9:

1. The mass amount of dispersant is 0.5% to 12% of the total mass of the mixed fibers. The mass amount of amino-modified two-dimensional layered nanosheets is 2.7% to 10% of the total mass of the mixed fibers. The speed of the dissociator is 800 rpm to 8000 rpm. After dissociation for 0.5 min to 60 min, a uniformly dispersed ultrafine fiber mixed slurry is obtained. The mixed fiber is a pulp of chopped fibers and microfibers; Step 4: The microfiber mixed pulp is directly wet-formed on a paper forming machine, with a web density of 0.01%–2%; the resulting mixed microfiber base paper is dried in a forced-air oven at 110°C. o Bake in an oven at temperature C for 3 hours to obtain the mixed microfiber base paper; the paper weight is controlled at 30-60 g / m². 2 The base paper is then hot-pressed on a hot roll mill at a temperature of 200°C. o C~350 o C; hot pressing pressure is 0.1MPa~2MPa; roller speed is 0.01~1m / min; hot pressing is performed 1~3 times to obtain composite cigarette paper; The chopped fibers are selected from at least one of the following: pine fiber, cypress fiber, fir fiber, poplar fiber, eucalyptus fiber, willow fiber, Chinese mahogany fiber, acacia fiber, bamboo fiber, reed fiber, stalk fiber, bagasse fiber, wheat straw fiber, cotton fiber, agave fiber, banana leaf fiber, sugarcane leaf fiber, and dragon's beard grass fiber. The microfiber is selected from at least one of the following: kenaf fiber, hemp fiber, jute fiber, flax fiber, acetate fiber, and polyvinyl alcohol fiber; The two-dimensional layered nanosheets are selected from at least one of the following: flake vermiculite, molybdenum disulfide, flake magnesium oxide, flake zinc oxide, hexagonal boron nitride, and flake graphite.

2. The method for preparing a high thermal conductivity, impermeable, and mechanically durable cigarette paper according to claim 1, characterized in that, In step 2, the average lateral size of the amino-modified two-dimensional layered nanosheets is between 500 nm and 800 nm.

3. The method for preparing a high thermal conductivity, impermeable, and mechanically durable cigarette paper according to claim 1, characterized in that, In step 2, the mass of the two-dimensional layered nanosheets is 0.05% to 3.0% of the mass of the modified solvent.

4. The method for preparing a high thermal conductivity, impermeable, and mechanically durable cigarette paper according to claim 1, characterized in that, In step 2, the mass of the two-dimensional layered nanosheets is 0.1% to 2.5% of the mass of the modified solvent.

5. The method for preparing a high thermal conductivity, impermeable, and mechanically durable cigarette paper according to claim 1, characterized in that, The amino modifier is selected from at least one of the following: urea, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, polyethyleneimine, glycine, alanine, leucine, valine, tryptophan, serine, glutamine, threonine, asparagine, tyrosine, and aspartic acid.

6. The method for preparing a high thermal conductivity, impermeable, and mechanically durable cigarette paper according to claim 1, characterized in that, The dispersant is selected from at least one of the following: polyethylene oxide, polyacrylamide, polyvinyl alcohol, sodium lignosulfonate, maleic anhydride-styrene copolymer, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, gelatin, and sodium alginate.

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