Hydrophobically modified lignin-containing nanocellulose and methods of making and using the same

Abstract

The application belongs to the technical field of nanocellulose preparation, and particularly relates to a hydrophobically modified nanocellulose containing lignin as well as a preparation method and application thereof, and comprises the following steps: adding potassium hydrogen persulfate to a bio-chemical mechanical pulp, treating at 80-100 DEG C for 1-5h to obtain a pulp containing lignin; washing the pulp, and then performing mechanical treatment and homogenization treatment to obtain nanocellulose containing lignin; and reacting the nanocellulose containing lignin and octadecylamine in an alcohol solution, with a reaction temperature of 55-65 DEG C and a reaction time of 2-6h to obtain the hydrophobically modified nanocellulose containing lignin. The application realizes the hydrophobic functionalization of nanocellulose while regulating the content of lignin, effectively improves the utilization rate of the bio-chemical mechanical pulp, improves the product quality of the nanocellulose containing lignin, and enhances the cleanness of the production process.

Description

Technical Field

[0001] This invention belongs to the field of nanocellulose preparation technology, specifically relating to a hydrophobically modified lignin-containing nanocellulose, its preparation method, and its application. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Nanocellulose, with its high strength, high specific surface area, and biodegradability, can be used in packaging materials, composite materials, biomedicine, electronic energy, and environmental protection. Lignin possesses ultraviolet absorption and antioxidant properties; when nanocellulose contains lignin, it can improve the material's resistance to ultraviolet radiation, aging, heat, and its water and oxygen barrier properties. However, excessive lignin content can have more negative effects, such as reducing the binding force between lignin and nanocellulose, leading to decreased mechanical properties and uneven texture.

[0004] Furthermore, the abundance of hydroxyl groups on the surface of nanocellulose gives it excellent hydrophilicity, resulting in poor compatibility with non-polar materials and affecting the properties of composite materials. Moreover, this hydrophilicity limits the application of nanocellulose in waterproofing, packaging, and hydrophobic drug carriers.

[0005] Existing methods for preparing nanocellulose generally use fully bleached pulp as raw material. The bleaching process requires the use of irritating chemicals for pulping and bleaching, which not only reduces the environmental friendliness of nanocellulose products but also leads to a decrease in their yield. If unbleached raw materials are used, non-cellulose components (such as hemicellulose and lignin) in the raw materials are difficult to remove, resulting in nanocellulose products with high non-cellulose content, making them difficult to apply in practice. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a hydrophobically modified lignin-containing nanocellulose, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a method for preparing hydrophobically modified lignin-containing nanocellulose, comprising the following steps: Add potassium persulfate to biochemical mechanical pulp and treat at 80-100℃ for 1-5 hours to obtain lignin-containing pulp; The pulp was washed and then subjected to mechanical and homogenization processes to obtain lignin-containing nanocellulose. The lignin-containing nanocellulose and octadecylamine were reacted in an alcohol solution at a temperature of 55-65℃ for 2-6 hours to obtain hydrophobically modified lignin-containing nanocellulose.

[0008] Secondly, the present invention provides a hydrophobically modified lignin-containing nanocellulose, which is prepared by the aforementioned preparation method.

[0009] Thirdly, the present invention provides the application of the hydrophobically modified lignin-containing nanocellulose in hydrophobic membrane materials.

[0010] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows: This invention first prepares poplar biochemical mechanical pulp using a bio-enzymatic assisted process, which significantly reduces chemical usage and energy consumption, making it more economical than traditional methods. Compared to chemical pulp, biochemical mechanical pulp retains more lignin and hemicellulose. This not only helps maintain fiber integrity during the production of lignin-containing nanocellulose but also improves the overall performance of the final product. Furthermore, biochemical mechanical pulp provides ideal conditions for fiber dissociation, thereby contributing to improved yield and quality of lignin-containing nanocellulose.

[0011] This invention uses potassium persulfate as a chemical treatment reagent, which is characterized by high stability, low toxicity, and low cost. It can selectively decompose lignin, hemicellulose, and the amorphous regions of cellulose, thereby achieving effective control over lignin-containing nanocellulose components and obtaining target products with different lignin contents. The potassium persulfate oxidation method has significant advantages in cellulose treatment. This method is simple to operate, safe and economical, easily scaled up for commercial use, and has low environmental risk.

[0012] The preparation process of this invention integrates two key steps: potassium persulfate oxidation and octadecylamine modification. Potassium persulfate treatment not only precisely controls the lignin content but also generates the desired carboxyl groups on the nanocellulose, laying the foundation for the direct grafting of hydrophobicity with octadecylamine, thus eliminating the need for a separate oxidation pretreatment. This achieves the direct and efficient preparation of lignin-containing hydrophobic nanocellulose from raw materials. This material can be used to prepare waterproof materials, packaging materials, and hydrophobic drug carriers.

[0013] This invention achieves hydrophobic functionalization of nanocellulose while controlling lignin content, effectively improving the utilization rate of biochemical mechanical pulp and enhancing the product quality of lignin-containing nanocellulose (hydrophobic properties (water contact angle), heat resistance (initial pyrolysis temperature and maximum decomposition temperature), ultraviolet blocking properties (UVA and UVB blocking rates), and the controllability of lignin content). This method avoids the use of halogen-containing strong oxidizing systems, reduces the generation of harmful byproducts, and improves raw material utilization, reduces chemical consumption and wastewater treatment burden by retaining lignin, thereby enhancing the greenness and cleanliness of the production process. Detailed Implementation

[0014] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0015] To address the technical problems existing in the background art, the present invention provides a method for preparing hydrophobically modified lignin-containing nanocellulose, comprising the following steps: Add potassium persulfate to biochemical mechanical pulp and treat at 80-100℃ for 1-5 hours to obtain lignin-containing pulp; The pulp was washed and then subjected to mechanical and homogenization processes to obtain lignin-containing nanocellulose. The lignin-containing nanocellulose and octadecylamine were reacted in an alcohol solution at a temperature of 55-65℃ for 2-6 hours to obtain a hydrophobically modified lignin-containing nanocellulose slurry.

[0016] Potassium persulfate can selectively decompose lignin, hemicellulose, and amorphous regions of cellulose in biochemical mechanical pulp, thereby achieving effective control over lignin-containing nanocellulose components and obtaining target products with different lignin contents. Potassium persulfate treatment can generate carboxyl groups on the surface of nanocellulose, laying the foundation for the subsequent direct grafting hydrophobication reaction of octadecylamine, eliminating the need for a separate oxidation pretreatment step, and realizing the direct and efficient preparation of lignin-containing hydrophobic nanocellulose from raw materials.

[0017] Mechanical processing (such as stirring) can initially deagglomerate the fiber bundles in the slurry, while homogenization (such as high-pressure homogenization) further breaks down the fibers through high pressure to form nanocellulose, ensuring that the product reaches the nanoscale.

[0018] The potassium persulfate treatment stage generates carboxyl groups on the surface of nanocellulose. These carboxyl groups serve as active reaction sites, providing a chemical basis for subsequent grafting with octadecylamine, eliminating the need for additional oxidative pretreatment. Octadecylamine is a long-chain aliphatic amine with a molecular structure containing a hydrophilic amino group and a hydrophobic octadecyl alkyl chain. In an alcohol solvent, the carboxyl groups on the nanocellulose surface undergo an amidation reaction with the amino group of octadecylamine, covalently grafting the octadecylamine molecule onto the nanocellulose surface. After grafting, the abundant hydrophilic hydroxyl groups originally present on the nanocellulose surface are replaced by the hydrophobic long-chain alkyl groups of octadecylamine. Through van der Waals interactions, the long-chain alkyl groups form a hydrophobic layer on the material surface, significantly reducing surface energy and thus endowing the nanocellulose with hydrophobic properties.

[0019] Octadecylamine is insoluble in water but soluble in ethanol, while lignin-containing nanocellulose exhibits better reactivity in water. Therefore, the reaction is carried out in an ethanol solution.

[0020] In some embodiments, the amount of potassium persulfate used is 1~4 g / g oven-dry pulp.

[0021] In some embodiments, when treated with potassium persulfate, the solid-liquid ratio in the system is 1:15-25 g / mL.

[0022] In some embodiments, potassium persulfate is added to the biochemical mechanical slurry and treated at 85-95°C for 2-4 hours.

[0023] In some embodiments, the preparation method of the biochemical mechanical pulp is to pre-steam the wood, extrude it, treat it with hot alkali, treat it with cellulase, refine it with high concentration and beat it.

[0024] Preferably, the wood is poplar.

[0025] Preferably, the solid-liquid ratio of the pre-steam treatment is 1:4-8 g / mL, the treatment temperature is 9-100℃, and the treatment time is 30-50 min.

[0026] Preferably, the compression ratio of the extrusion is 1:3-5.

[0027] Preferably, during the hot alkaline treatment, the mass fraction of sodium hydroxide is 2-5%, the solid-liquid ratio is 1:3-5 g / mL, the treatment temperature is 90-100℃, and the treatment time is 30-50 min.

[0028] Preferably, the enzyme used in the cellulase treatment is cellulase, the amount of cellulase used is 10-30 U / g, the buffer solution is a citrate-sodium citrate solution with a pH of 5-6, the solid-liquid ratio is 1:3-6 g / mL, the treatment temperature is 50-60℃, and the treatment time is 40-60 min.

[0029] Preferably, the high-consistency pulping speed is 3000~3500 rpm, the first pulping gap is 0.4-0.6mm, and the second pulping gap is 0.1-0.3mm.

[0030] The rotation speed can be 3000 rpm, 3100 rpm, 3200 rpm, 3300 rpm, 3400 rpm, or 3500 rpm; the gap of the first stage of grinding can be 0.4 mm, 0.5 mm, or 0.6 mm; and the gap of the second stage of grinding can be 0.1 mm, 0.2 mm, or 0.3 mm.

[0031] Preferably, the beating degree of the pulping treatment is 40±2 °SR, such as 40°SR, 41°SR or 42°SR.

[0032] In some embodiments, the slurry is washed and then subjected to mechanical and homogenization processes. The washed slurry is neutral and is washed with hot water and room temperature water, respectively.

[0033] Hot water (typically above 60°C) increases the solubility of residual chemicals in the pulp, such as unreacted potassium persulfate, lignin degradation products, and hemicellulose fragments, accelerating their desorption from the fiber surface. This results in a more thorough removal of reaction byproducts and unreacted reagents. Following hot water washing, rinsing with room temperature water avoids the potential impact of high temperatures on the nanocellulose structure, such as excessive swelling or lignin re-adsorption. Simultaneously, by gradually lowering the system temperature, the pulp pH is precisely adjusted to neutral.

[0034] Preferably, the mechanical treatment is mechanical stirring, and the stirring speed is 10000-12000 r / min.

[0035] Preferably, the homogenization process is performed using a homogenizer, and the homogenization pressure is 100-150 MPa, such as 100 MPa, 105 MPa, 110 MPa, 115 MPa, 120 MPa, 125 MPa, 130 MPa, 135 MPa, 140 MPa, 145 MPa or 150 MPa.

[0036] In some embodiments, when lignin-containing nanocellulose and octadecylamine are reacted in an alcohol solvent, the mass ratio of lignin-containing nanocellulose to octadecylamine is 0.8-1.5:0.8-1.5, preferably 1:1.

[0037] Preferably, the alcohol solution is a mixture of alcohol and water, wherein the mass fraction of alcohol is 30%-60%, such as 30%, 40%, 50% or 60%.

[0038] More preferably, the alcohol is ethanol, methanol, isopropanol or n-butanol.

[0039] In some embodiments, the method further includes the step of preparing a hydrophobic film from the hydrophobically modified lignin-containing nanocellulose slurry.

[0040] Preferably, the hydrophobically modified lignin-containing nanocellulose slurry is vacuum filtered, and then the hydrophobically modified lignin-containing nanocellulose film obtained by vacuum filtration is flattened using a filter membrane and dried to obtain a hydrophobic film.

[0041] Secondly, the present invention provides a hydrophobically modified lignin-containing nanocellulose, which is prepared by the aforementioned preparation method.

[0042] Thirdly, the present invention provides the application of the hydrophobically modified lignin-containing nanocellulose in hydrophobic membrane materials.

[0043] The specific implementation of the present invention will be further described below with reference to the embodiments, but the implementation of the present invention is not limited to the scope shown in the embodiments.

[0044] All materials involved in the examples are commercially available. The cellulase is from Shandong Longket Enzyme Preparation Co., Ltd., and its enzyme activity is 80,000 U / mL.

[0045] This invention does not impose any special restrictions on the type or source of poplar wood raw materials used. The following example uses poplar wood from Jining, Shandong, which has a cellulose content of 44.58%, a hemicellulose content of 25.91%, and a lignin content of 24.15%.

[0046] Example 1 (1) Poplar wood is subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-concentration grinding and pulping treatment to obtain poplar biochemical mechanical pulp.

[0047] The pre-steaming treatment has a solid-liquid ratio of 1:6 g / mL, a treatment temperature of 95℃, and a treatment time of 40 min. The extrusion process is carried out immediately after the pre-steaming treatment, using a screw extruder with a compression ratio of 1:4. The amount of sodium hydroxide used in the hot alkaline treatment was 4%, the solid-liquid ratio was 1:4 g / mL, and the treatment temperature and time were 95℃ and 40 min, respectively. The enzyme treatment was cellulase treatment, with an enzyme dosage of 20 U / g, and the treatment buffer was a citrate-sodium citrate solution with a pH of 5.5, a solid-liquid ratio of 1:5 g / mL, and a treatment temperature and time of 55℃ and 50 min. The high-consistency polishing pulp has a rotation speed of 3500 rpm, and the gaps between the two polishing sections are 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0048] (2) Potassium persulfate was added to the poplar chemimechanical pulp obtained in step (1) for treatment. The amount of potassium persulfate was 1 g / g of oven-dry pulp, the solid-liquid ratio was 1:20 g / mL, the treatment temperature was 90℃, and the treatment time was 4 h.

[0049] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0050] (4) The slurry obtained in step (3) is mechanically treated and homogenized in a mixer equipped with a mixing cup for 15 min. The mixing speed is 12000 r / min to initially separate the fibers. Then, the homogenizer is used for two homogenization treatments at a homogenization pressure of 120 MPa.

[0051] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to hydrophobic treatment by octadecylamine at a dosage of 1 g / g of lignin-containing nanocellulose. The reaction is carried out in 50% ethanol aqueous solution with a solid-liquid ratio (the solid-liquid ratio refers to the ratio of the dry raw material mass to the reaction solution volume) of 1:10 g / mL. The treatment temperature is 60℃ and the treatment time is 4 h to obtain lignin-containing hydrophobic nanocellulose.

[0052] (6) The lignin-containing hydrophobic nanocellulose obtained in step (5) was subjected to film formation treatment, and the lignin-containing nanocellulose was vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film.

[0053] Then, the lignin-containing hydrophobic nanocellulose membrane is sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain the hydrophobic membrane.

[0054] Results: The obtained lignin-containing nanocellulose had a cellulose content of 69.70%, a lignin content of 15.46%, a hemicellulose content of 10.48%, a crystallinity of 38.02%, an initial decomposition temperature of 316.12℃, and a maximum weight loss rate temperature of 364.15℃; the obtained hydrophobic film had a water contact angle of 121.18°, a UVA blocking rate of 100%, and a UVB blocking rate of 100%.

[0055] Example 2 (1) Poplar wood is subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-concentration grinding and pulping treatment to obtain poplar biochemical mechanical pulp.

[0056] The pre-steaming treatment has a solid-liquid ratio of 1:6 g / mL, a treatment temperature of 95℃, and a treatment time of 40 min. The extrusion process is carried out immediately after the pre-steaming treatment, using a screw extruder with a compression ratio of 1:4. The amount of sodium hydroxide used in the hot alkaline treatment was 4%, the solid-liquid ratio was 1:4 g / mL, and the treatment temperature and time were 95℃ and 40 min, respectively. The enzyme treatment was cellulase treatment, with an enzyme dosage of 20 U / g, and the treatment buffer was a citrate-sodium citrate solution with a pH of 5.5, a solid-liquid ratio of 1:5 g / mL, and a treatment temperature and time of 55℃ and 50 min. The high-consistency polishing slurry has a rotation speed of 3000 rpm, and the gaps between the two polishing sections are 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0057] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 1.5 g / g of oven-dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0058] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0059] (4) The slurry obtained in step (3) is subjected to mechanical treatment and homogenization in a mixer equipped with a mixing cup for 15 min. The mixing speed is 12000 r / min to initially separate the fibers. Then, the homogenizer is used for two homogenization treatments at a pressure of 120 MPa.

[0060] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to hydrophobic treatment by octadecylamine at a dosage of 1 g / g of lignin-containing nanocellulose. The reaction is carried out in 50% ethanol solvent with a solid-liquid ratio of 1:10 g / mL, a treatment temperature of 60℃, and a treatment time of 4 h to obtain hydrophobic lignin-containing nanocellulose.

[0061] (6) The hydrophobic lignin-containing nanocellulose obtained in step (5) is subjected to film formation treatment, and the lignin-containing nanocellulose is vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film was prepared. Then, the lignin-containing nanocellulose film was sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain a hydrophobic film.

[0062] Results: The obtained lignin-containing nanocellulose had a cellulose content of 75.29%, a lignin content of 10.45%, a hemicellulose content of 10.14%, a crystallinity of 39.15%, an initial decomposition temperature of 318.55℃, a maximum weight loss rate temperature of 363.81℃, a water contact angle of 118.93°, a UVA blocking rate of 100%, and a UVB blocking rate of 100%.

[0063] Example 3 (1) Poplar wood is subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-concentration grinding and pulping treatment to obtain poplar biochemical mechanical pulp.

[0064] The pre-steaming treatment has a solid-liquid ratio of 1:6 g / mL, a treatment temperature of 95℃, and a treatment time of 40 min. The extrusion process is carried out immediately after the pre-steaming treatment, using a screw extruder with a compression ratio of 1:4. The amount of sodium hydroxide used in the hot alkaline treatment was 4%, the solid-liquid ratio was 1:4 g / mL, and the treatment temperature and time were 95℃ and 40 min, respectively. The enzyme treatment was cellulase treatment, with an enzyme dosage of 20 U / g, and the treatment buffer was a citrate-sodium citrate solution with a pH of 5.5, a solid-liquid ratio of 1:5 g / mL, and a treatment temperature and time of 55℃ and 50 min. The high-consistency polishing slurry has a rotation speed of 3300 rpm, and the gaps between the two polishing sections are 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0065] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 2 g / g of oven-dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0066] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0067] (4) The slurry obtained in step (3) is mechanically treated and homogenized. It is processed in a mixer equipped with a mixing cup for 15 min at a stirring speed of 12000 r / min to initially separate the fibers. Then, it is homogenized twice using a homogenizer at a pressure of 120 MPa.

[0068] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to hydrophobic treatment by octadecylamine at a dosage of 1 g / g of lignin-containing nanocellulose. The reaction is carried out in 50% ethanol solvent with a solid-liquid ratio of 1:10 g / mL, a treatment temperature of 60℃, and a treatment time of 4 h to obtain hydrophobic lignin-containing nanocellulose.

[0069] (6) The hydrophobic lignin-containing nanocellulose obtained in step (5) is subjected to film formation treatment, and the lignin-containing nanocellulose is vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film was prepared. Then, the lignin-containing nanocellulose film was sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain a hydrophobic film.

[0070] Results: The obtained lignin-containing nanocellulose had a cellulose content of 78.01%, a lignin content of 6.63%, a hemicellulose content of 10.40%, a crystallinity of 44.83%, an initial decomposition temperature of 321.55℃, a maximum weight loss rate temperature of 363.41℃, a water contact angle of 116.43°, a UVA blocking rate of 99.98%, and a UVB blocking rate of 99.99%.

[0071] Example 4 (1) Poplar wood is subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-concentration grinding and pulping treatment to obtain poplar biochemical mechanical pulp.

[0072] The pre-steaming treatment has a solid-liquid ratio of 1:6 g / mL, a treatment temperature of 95℃, and a treatment time of 40 min.

[0073] The extrusion process is carried out immediately after the pre-steaming treatment, using a screw extruder with a compression ratio of 1:4.

[0074] The amount of sodium hydroxide used in the hot alkaline treatment was 4%, the solid-liquid ratio was 1:4 g / mL, and the treatment temperature and time were 95℃ and 40 min, respectively.

[0075] The enzyme treatment was cellulase treatment, with an enzyme dosage of 20 U / g. The treatment buffer was a citric acid-sodium citrate solution with a pH of 5.5 and a solid-liquid ratio of 1:5 g / mL. The treatment temperature and time were 55℃ and 50 min, respectively.

[0076] The high-consistency polishing slurry has a rotation speed of 3200 rpm, and the gaps between the two polishing sections are 0.5 mm and 0.2 mm, respectively.

[0077] The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0078] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 2.5 g / g of oven-dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0079] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0080] (4) The slurry obtained in step (3) is subjected to mechanical treatment and homogenization in a mixer equipped with a mixing cup for 15 min. The mixing speed is 12000 r / min to initially separate the fibers. Then, the homogenizer is used for two homogenization treatments at a pressure of 120 MPa.

[0081] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to hydrophobic treatment by octadecylamine at a dosage of 1 g / g of lignin-containing nanocellulose. The reaction is carried out in 50% ethanol solvent with a solid-liquid ratio of 1:10 g / mL, a treatment temperature of 60℃, and a treatment time of 4 h to obtain hydrophobic lignin-containing nanocellulose.

[0082] (6) The hydrophobic lignin-containing nanocellulose obtained in step (5) is subjected to film formation treatment, and the lignin-containing nanocellulose is vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film was prepared. Then, the lignin-containing nanocellulose film was sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain a hydrophobic film.

[0083] Results: The obtained lignin-containing nanocellulose had a cellulose content of 80.07%, a lignin content of 4.67%, a hemicellulose content of 9.75%, a crystallinity of 47.66%, an initial decomposition temperature of 323.89℃, a maximum weight loss rate temperature of 362.93℃, a water contact angle of 115.70°, a UVA blocking rate of 99.93%, and a UVB blocking rate of 99.99%.

[0084] Example 5 (1) Poplar wood is subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-concentration grinding and pulping treatment to obtain poplar biochemical mechanical pulp.

[0085] The pre-steaming treatment has a solid-liquid ratio of 1:6 g / mL, a treatment temperature of 95℃, and a treatment time of 40 min.

[0086] The extrusion process is carried out immediately after the pre-steaming treatment, using a screw extruder with a compression ratio of 1:4.

[0087] The amount of sodium hydroxide used in the hot alkaline treatment was 4%, the solid-liquid ratio was 1:4 g / mL, and the treatment temperature and time were 95℃ and 40 min, respectively.

[0088] The enzyme treatment was cellulase treatment, with an enzyme dosage of 20 U / g. The treatment buffer was a citric acid-sodium citrate solution with a pH of 5.5 and a solid-liquid ratio of 1:5 g / mL. The treatment temperature and time were 55℃ and 50 min, respectively.

[0089] The high-consistency pulp has a rotation speed of 3500 rpm, and the gaps between the two pulp sections are 0.5 mm and 0.2 mm, respectively.

[0090] The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0091] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 3 g / g of oven-dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0092] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0093] (4) The slurry obtained in step (3) is subjected to mechanical treatment and homogenization in a mixer equipped with a mixing cup for 15 min. The mixing speed is 12000 r / min to initially separate the fibers. Then, the homogenizer is used for two homogenization treatments at a pressure of 120 MPa.

[0094] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to hydrophobic treatment by octadecylamine at a dosage of 1 g / g of lignin-containing nanocellulose. The reaction is carried out in 50% ethanol solvent with a solid-liquid ratio of 1:10 g / mL, a treatment temperature of 60℃, and a treatment time of 4 h to obtain hydrophobic lignin-containing nanocellulose.

[0095] (6) The hydrophobic lignin-containing nanocellulose obtained in step (5) is subjected to film formation treatment, and the lignin-containing nanocellulose is vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film was prepared. Then, the lignin-containing nanocellulose film was sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain a hydrophobic film.

[0096] Results: The obtained lignin-containing nanocellulose had a cellulose content of 82.21%, a lignin content of 3.44%, a hemicellulose content of 8.92%, a crystallinity of 68.01%, an initial decomposition temperature of 325.20℃, a maximum weight loss rate temperature of 361.70℃, a water contact angle of 113.33°, a UVA blocking rate of 99.89%, and a UVB blocking rate of 99.98%.

[0097] Example 6 (1) Poplar wood was subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-consistency grinding, and pulping treatment to obtain poplar biochemical mechanical pulp. The pre-steaming treatment was carried out immediately after the pre-steaming treatment using a screw extruder with a compression ratio of 1:4. The hot alkali treatment used 4% sodium hydroxide, with a solid-liquid ratio of 1:4 g / mL, and the treatment temperature and time were 95℃ and 40min. The enzyme treatment was cellulase treatment with an enzyme dosage of 20 U / g, and the buffer solution was a pH 5.5 citric acid-sodium citrate solution with a solid-liquid ratio of 1:5 g / mL, and the treatment temperature and time were 55℃ and 50min. The high-consistency grinding was carried out at a speed of 3500 rpm, with the two grinding stages having gaps of 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0098] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 3.5 g / g dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0099] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0100] (4) The slurry obtained in step (3) is subjected to mechanical treatment and homogenization in a mixer equipped with a mixing cup for 15 min. The mixing speed is 12000 r / min to initially separate the fibers. Then, the homogenizer is used for two homogenization treatments at a pressure of 120 MPa.

[0101] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to hydrophobic treatment by octadecylamine at a dosage of 1 g / g of lignin-containing nanocellulose. The reaction is carried out in 50% ethanol solvent with a solid-liquid ratio of 1:10 g / mL, a treatment temperature of 60℃, and a treatment time of 4 h to obtain hydrophobic lignin-containing nanocellulose.

[0102] (6) The hydrophobic lignin-containing nanocellulose obtained in step (5) is subjected to film formation treatment, and the lignin-containing nanocellulose is vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film was prepared. Then, the lignin-containing nanocellulose film was sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain a hydrophobic film.

[0103] Results: The obtained lignin-containing nanocellulose had a cellulose content of 83.96%, a lignin content of 2.03%, a hemicellulose content of 8.80%, a crystallinity of 63.54%, an initial decomposition temperature of 325.79℃, a maximum weight loss rate temperature of 359.24℃, a water contact angle of 108.57°, a UVA blocking rate of 99.64%, and a UVB blocking rate of 99.94%.

[0104] Example 7 (1) Poplar wood was subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-consistency grinding, and pulping treatment to obtain poplar biochemical mechanical pulp. The pre-steaming treatment was carried out immediately after the pre-steaming treatment using a screw extruder with a compression ratio of 1:4. The hot alkali treatment used 4% sodium hydroxide, with a solid-liquid ratio of 1:4 g / mL, and the treatment temperature and time were 95℃ and 40min. The enzyme treatment was cellulase treatment with an enzyme dosage of 20 U / g, and the treatment buffer was a pH 5.5 citric acid-sodium citrate solution with a solid-liquid ratio of 1:5 g / mL, and the treatment temperature and time were 55℃ and 50min. The high-consistency grinding was carried out at a speed of 3000 rpm, with the two grinding stages having gaps of 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0105] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 4 g / g of oven-dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0106] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0107] (4) The slurry obtained in step (3) is subjected to mechanical treatment and homogenization in a mixer equipped with a mixing cup for 15 min. The mixing speed is 12000 r / min to initially separate the fibers. Then, the homogenizer is used for two homogenization treatments at a pressure of 120 MPa.

[0108] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to hydrophobic treatment by octadecylamine at a dosage of 1 g / g of lignin-containing nanocellulose. The reaction is carried out in 50% ethanol solvent with a solid-liquid ratio of 1:10 g / mL, a treatment temperature of 60℃, and a treatment time of 4 h to obtain hydrophobic lignin-containing nanocellulose.

[0109] (6) The hydrophobic lignin-containing nanocellulose obtained in step (5) is subjected to film formation treatment, and the lignin-containing nanocellulose is vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film was prepared. Then, the lignin-containing nanocellulose film was sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain a hydrophobic film.

[0110] Results: The obtained lignin-containing nanocellulose had a cellulose content of 85.24%, a lignin content of 0.90%, a hemicellulose content of 8.75%, a crystallinity of 67.44%, an initial decomposition temperature of 326.26℃, a maximum weight loss rate temperature of 357.62℃, a water contact angle of 106.83°, a UVA blocking rate of 97.42%, and a UVB blocking rate of 99.33%.

[0111] Comparative Example 1 The difference from Example 1 is that potassium persulfate is not added in step (2), and the hydrophobic modification step in step (5) is omitted.

[0112] Specifically: (1) Poplar wood was subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-consistency grinding, and pulping treatment to obtain poplar biochemical mechanical pulp. The pre-steaming treatment was carried out immediately after the pre-steaming treatment using a screw extruder with a compression ratio of 1:4. The hot alkali treatment used 4% sodium hydroxide, with a solid-liquid ratio of 1:4 g / mL, and the treatment temperature and time were 95℃ and 40min. The enzyme treatment was cellulase treatment with an enzyme dosage of 20 U / g, and the buffer solution was a pH 5.5 citric acid-sodium citrate solution with a solid-liquid ratio of 1:5 g / mL, and the treatment temperature and time were 55℃ and 50min. The high-consistency grinding was carried out at a speed of 3500 rpm, with the two grinding stages having gaps of 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0113] (2) The poplar chemimechanical pulp obtained in step (1) is subjected to hot water treatment with a solid-liquid ratio of 1:20 g / mL, a treatment temperature of 90℃, and a treatment time of 4 h.

[0114] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0115] (4) The slurry obtained in step (3) is mechanically processed and homogenized in a kitchen mixer equipped with a mixing cup for 15 minutes.

[0116] Results: The product obtained was still a slurry, with fiber widths ranging from 28 μm to 30 μm, which is much larger than the nanoscale. Therefore, it was impossible to obtain lignin-containing nanocellulose.

[0117] Comparative Example 2 The difference from Example 1 is that the hydrophobic modification step (5) is omitted.

[0118] Specifically: (1) Poplar wood was subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-consistency grinding, and pulping treatment to obtain poplar biochemical mechanical pulp. The pre-steaming treatment was carried out immediately after the pre-steaming treatment using a screw extruder with a compression ratio of 1:4. The hot alkali treatment used 4% sodium hydroxide, with a solid-liquid ratio of 1:4 g / mL, and the treatment temperature and time were 95℃ and 40min. The enzyme treatment was cellulase treatment with an enzyme dosage of 20 U / g, and the buffer solution was a pH 5.5 citric acid-sodium citrate solution with a solid-liquid ratio of 1:5 g / mL, and the treatment temperature and time were 55℃ and 50min. The high-consistency grinding was carried out at a speed of 3500 rpm, with the two grinding stages having gaps of 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0119] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 1 g / g of oven-dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0120] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0121] (4) The slurry obtained in step (3) is subjected to mechanical treatment and homogenization in a mixer equipped with a mixing cup for 15 min. The mixing speed is 12000 r / min to initially separate the fibers. Then, the homogenizer is used for two homogenization treatments at a pressure of 120 MPa.

[0122] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to film formation treatment, and vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film was prepared. Then, the lignin-containing nanocellulose film was sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain the film.

[0123] Results: The crystallinity of the obtained lignin-containing nanocellulose was 56.49%, the initial decomposition temperature was 202.84℃, the maximum weight loss rate temperature was 318.72℃, the water contact angle of the obtained film was 88.83°, the UVA blocking rate was 99.98%, and the UVB blocking rate was 100%. Its initial decomposition temperature and maximum weight loss rate temperature were lower than those of Example 1, therefore the thermal stability of this sample was lower than that of Example 1; the contact angle was much smaller than that of Example 1, and less than 90°, indicating it was not a hydrophobic film; the UVA blocking rate was also lower than that of Example 1, and the ultraviolet blocking performance was also worse than that of Example 1.

[0124] Comparative Example 3 The difference from Example 3 is that the hydrophobic treatment step (5) is omitted.

[0125] Specifically: (1) Poplar wood was subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-consistency grinding, and pulping treatment to obtain poplar biochemical mechanical pulp. The pre-steaming treatment had a solid-liquid ratio of 1:6 g / mL, a treatment temperature of 95℃, and a treatment time of 40 min. The extrusion treatment was carried out immediately after the pre-steaming treatment using a screw extruder with a compression ratio of 1:4. The hot alkali treatment used 4% sodium hydroxide, had a solid-liquid ratio of 1:4 g / mL, and a treatment temperature and time of 95℃ and 40 min. The enzyme treatment was cellulase treatment with an enzyme dosage of 20 U / g, and the treatment buffer was a pH 5.5 citric acid-sodium citrate solution with a solid-liquid ratio of 1:5 g / mL, and a treatment temperature and time of 55℃ and 50 min. The high-consistency grinding was carried out at a speed of 3300 rpm, with two grinding intervals of 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0126] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 2 g / g of oven-dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0127] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0128] (4) The slurry obtained in step (3) is mechanically treated and homogenized in a mixer equipped with a mixing cup for 15 minutes to allow the fibers to be initially separated. Then, it is homogenized twice using a homogenizer at a pressure of 120 MPa.

[0129] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to film formation treatment, and vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film was prepared. Then, the lignin-containing nanocellulose film was sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain the film.

[0130] Results: The crystallinity of the obtained lignin-containing nanocellulose was 64.60%, the initial decomposition temperature was 230.68℃, the maximum weight loss rate temperature was 315.67℃, the water contact angle of the obtained film was 78.67°, the UVA blocking rate was 99.81%, and the UVB blocking rate was 99%.

[0131] Comparative Example 4 The difference from Example 5 is that the hydrophobic treatment step (5) is omitted.

[0132] (1) Poplar wood was subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-consistency grinding, and pulping treatment to obtain poplar biochemical mechanical pulp. The pre-steaming treatment was carried out immediately after the pre-steaming treatment using a screw extruder with a compression ratio of 1:4. The hot alkali treatment used 4% sodium hydroxide, with a solid-liquid ratio of 1:4 g / mL, and the treatment temperature and time were 95℃ and 40min. The enzyme treatment was cellulase treatment with an enzyme dosage of 20 U / g, and the buffer solution was a pH 5.5 citric acid-sodium citrate solution with a solid-liquid ratio of 1:5 g / mL, and the treatment temperature and time were 55℃ and 50min. The high-consistency grinding was carried out at a speed of 3500 rpm, with the two grinding stages having gaps of 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0133] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 3 g / g of oven-dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0134] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0135] (4) The slurry obtained in step (3) is mechanically treated and homogenized in a kitchen mixer equipped with a mixing cup for 15 minutes to allow the fibers to be initially separated. Then, it is homogenized twice using a homogenizer at a pressure of 120 MPa.

[0136] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to film formation treatment. The lignin-containing nanocellulose is vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a wet film with a quantitative value of 50 g / m². Then, the lignin-containing nanocellulose film is sandwiched between two filter membranes and flattened, and vacuum dried at 98°C to obtain the film.

[0137] Results: The crystallinity of the obtained lignin-containing nanocellulose was 68.01%, the initial decomposition temperature was 236.79℃, the maximum weight loss rate temperature was 317.85℃, the water contact angle of the obtained film was 72.07°, the UVA blocking rate was 96.05%, and the UVB blocking rate was 99.95%.

[0138] Comparative Example 5 (1) Poplar wood was subjected to pre-steaming treatment, extrusion, hot alkali treatment, cellulase treatment, high-consistency grinding, and pulping treatment to obtain poplar biochemical mechanical pulp. The pre-steaming treatment was carried out immediately after the pre-steaming treatment using a screw extruder with a compression ratio of 1:4. The hot alkali treatment used 4% sodium hydroxide, with a solid-liquid ratio of 1:4 g / mL, and the treatment temperature and time were 95℃ and 40min. The enzyme treatment was cellulase treatment with an enzyme dosage of 20 U / g, and the treatment buffer was a pH 5.5 citric acid-sodium citrate solution with a solid-liquid ratio of 1:5 g / mL, and the treatment temperature and time were 55℃ and 50min. The high-consistency grinding was carried out at a speed of 3000 rpm, with the two grinding stages having gaps of 0.5 mm and 0.2 mm, respectively. The pulping process was performed using a PFI refiner, and the pulp freeness reached 40±2 °SR.

[0139] (2) The poplar chemimechanical pulp obtained in step (1) is treated with potassium persulfate. The amount of potassium persulfate is 4 g / g of oven-dry pulp, the solid-liquid ratio is 1:20 g / mL, the treatment temperature is 90℃, and the treatment time is 4 h.

[0140] (3) Wash the slurry from step (2) with hot and room temperature deionized water until the pH is neutral.

[0141] (4) The slurry obtained in step (3) is mechanically treated and homogenized in a kitchen mixer equipped with a mixing cup for 15 minutes to allow the fibers to be initially separated. Then, it is homogenized twice using a homogenizer at a pressure of 120 MPa.

[0142] (5) The lignin-containing nanocellulose obtained in step (4) is subjected to film formation treatment, and vacuum filtered through a water-based microporous filter membrane with a pore size of 0.22 μm to prepare a product with a quantitative value of 50 g / m 2 A wet film was prepared. Then, the lignin-containing nanocellulose film was sandwiched between two filter membranes, flattened, and vacuum dried at 98°C to obtain the film.

[0143] Results: The crystallinity of the obtained lignin-containing nanocellulose was 71.36%, the initial decomposition temperature was 246.78℃, the maximum weight loss rate temperature was 319.52℃, the water contact angle of the obtained film was 59.70°, the UVA blocking rate was 91.17%, and the UVB blocking rate was 99.73%.

[0144] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing hydrophobically modified lignin-containing nanocellulose, characterized in that: Includes the following steps: Add potassium persulfate to biochemical mechanical pulp and treat at 80-100℃ for 1-5 hours to obtain lignin-containing pulp; The pulp was washed and then subjected to mechanical and homogenization processes to obtain lignin-containing nanocellulose. The lignin-containing nanocellulose and octadecylamine were reacted in an alcohol solution at a temperature of 55-65℃ for 2-6 hours to obtain a hydrophobically modified lignin-containing nanocellulose slurry.

2. The method for preparing hydrophobically modified lignin-containing nanocellulose according to claim 1, characterized in that: The dosage of potassium persulfate is 1~4 g / g oven-dry pulp; Alternatively, when treating with potassium persulfate, the solid-liquid ratio in the system should be 1:15-25 g / mL; Alternatively, potassium persulfate can be added to the biochemical mechanical slurry and treated at 85-95℃ for 2-4 hours.

3. The method for preparing hydrophobically modified lignin-containing nanocellulose according to claim 1, characterized in that: The preparation method of the biochemical mechanical pulp is to pre-steam the wood, extrude it, treat it with hot alkali, treat it with cellulase, refine it with high concentration and beat it to obtain the pulp. Preferably, the wood is poplar; Preferably, the solid-liquid ratio of the pre-steam treatment is 1:4-8 g / mL, the treatment temperature is 9-100℃, and the treatment time is 30-50 min; Preferably, the compression ratio of the extrusion is 1:3-5; Preferably, during the hot alkaline treatment, the mass fraction of sodium hydroxide is 2-5%, the solid-liquid ratio is 1:3-5 g / mL, the treatment temperature is 90-100℃, and the treatment time is 30-50 min. Preferably, the enzyme used in the cellulase treatment is cellulase, the amount of cellulase used is 10-30 U / g, the buffer solution is a citrate-sodium citrate solution with a pH of 5-6, the solid-liquid ratio is 1:3-6 g / mL, the treatment temperature is 50-60℃, and the treatment time is 40-60 min. Preferably, the high-consistency pulping speed is 3000~3500 rpm, the first stage pulping gap is 0.4-0.6mm, and the second stage pulping gap is 0.1-0.3mm; Preferably, the beating degree of the pulping treatment is 40±2 °SR.

4. The method for preparing hydrophobically modified lignin-containing nanocellulose according to claim 1, characterized in that: After washing, the pulp is subjected to mechanical and homogenization treatment. The washed pulp is neutral and is washed with hot water and room temperature water respectively. Preferably, the mechanical treatment is mechanical stirring, and the stirring speed is 10000-12000 r / min; Preferably, the homogenization process is performed using a homogenizer, with a homogenization pressure of 100-150 MPa.

5. The method for preparing hydrophobically modified lignin-containing nanocellulose according to claim 1, characterized in that: When lignin-containing nanocellulose and octadecylamine are reacted in an alcohol solvent, the mass ratio of lignin-containing nanocellulose to octadecylamine is 0.8-1.5:0.8-1.5, preferably 1:

1.

6. The method for preparing hydrophobically modified lignin-containing nanocellulose according to claim 5, characterized in that: The alcohol solution is a mixture of alcohol and water, wherein the mass fraction of alcohol is 30%-60%. Preferably, the alcohol is ethanol, methanol, isopropanol or n-butanol.

7. The method for preparing hydrophobically modified lignin-containing nanocellulose according to claim 1, characterized in that: It also includes the step of preparing a hydrophobic film from the hydrophobically modified lignin-containing nanocellulose slurry.

8. The method for preparing hydrophobically modified lignin-containing nanocellulose according to claim 7, characterized in that: The hydrophobically modified lignin-containing nanocellulose slurry was vacuum filtered, and then the hydrophobically modified lignin-containing nanocellulose film obtained by vacuum filtration was flattened using a filter membrane and dried to obtain a hydrophobic film.

9. A hydrophobically modified lignin-containing nanocellulose, characterized in that: It is prepared by any one of the preparation methods described in claims 1-8.

10. The application of the hydrophobically modified lignin-containing nanocellulose of claim 9 in hydrophobic membrane materials.