Preparation method of durable antibacterial hydrophobic paper based on combination of in-pulp self-assembly and surface photopolymerization

Abstract

The invention discloses a preparation method of durable antibacterial hydrophobic paper based on combination of in-pulp self-assembly and surface photopolymerization. The method comprises the following steps: firstly, adding nanocellulose into a dispersible solvent, and stirring for a period of time to obtain a nanocellulose suspension; dissolving a quaternary ammonium salt monomer, an organosilane monomer, a cross-linking agent and a photoinitiator in a polymerizable solvent to obtain a quaternary ammonium salt-organosilane solution; then, mixing the obtained nanocellulose suspension with a quaternary ammonium salt-organosilane solution, and then adding the mixture into paper pulp to prepare a special spraying solution; and finally, spraying the special spraying liquid on the surface of a base material, synchronously irradiating a spraying area with ultraviolet light in a nitrogen atmosphere, forming a coating on the surface of the base material to obtain the base material with the coating, and finally performing specific drying treatment on the base material with the coating to prepare the durable antibacterial hydrophobic paper. The hydrophobic paper prepared by the method is extremely durable in performance, and the production process is high in integration level.

Description

Technical Field

[0001] This invention belongs to the field of functional paper product manufacturing and surface modification technology. Specifically, it describes an antibacterial and hydrophobic paper with quaternary ammonium salt and organosilanes bifunctional groups prepared by photo-initiated spraying polymerization technology, and its preparation method. The paper surface achieves efficient and long-lasting antibacterial and hydrophobic properties through the combination of hydrogen bonding, photo-initiated polymerization and spraying technology. Background Technology

[0002] The inherent hydrophilicity and organic properties of paper also bring two significant drawbacks: First, paper is easily wetted and penetrated by liquid water, which leads to a sharp decline in its mechanical strength and limits its application in fields such as moisture-proof packaging and outdoor signage; second, the cellulose fibers and the moisture on their surface become a breeding ground for the growth and reproduction of microorganisms (such as bacteria and mold).

[0003] To overcome these shortcomings, researchers have developed various paper modification technologies. Currently, the mainstream methods include surface coating and impregnation. For example, coating paper with hydrophobic agents (such as paraffin wax or fluorocarbons) can impart a certain degree of water resistance, but these coatings often have poor mechanical stability, are easily worn off, and may affect the paper's breathability and feel. In terms of antibacterial properties, impregnation or the addition of inorganic antibacterial agents (such as silver nanoparticles) or organic antibacterial agents (such as quaternary ammonium salts) are commonly used. However, these methods have significant drawbacks: inorganic antibacterial agents are expensive and may be biotoxic; while small-molecule organic antibacterial agents, especially quaternary ammonium salts, although highly efficient in antibacterial activity, have weak binding to paper fibers and are easily lost during washing or use, leading to rapid degradation of antibacterial performance and poor durability.

[0004] Existing technologies typically address only one of the hydrophobic or antibacterial issues, making it difficult to efficiently and persistently integrate both functions. Simply physically mixing hydrophobic and antibacterial agents before coating often results in poor performance due to poor compatibility or functional interference. Furthermore, traditional thermosetting processes are energy-intensive and unsuitable for heat-sensitive paper substrates. Summary of the Invention

[0005] To overcome the limitations of existing technologies, this invention provides a method for preparing durable antibacterial and hydrophobic paper based on the combined use of in-slurry self-assembly and surface photopolymerization. By precisely controlling the composition and process parameters of the functional spraying liquid, molecular pre-assembly is achieved through hydrogen bonding, followed by photo-initiated polymerization to construct a stable cross-linked network, and finally, heat treatment to strengthen interfacial bonding. The resulting product exhibits excellent antibacterial properties (antibacterial rate ≥ 99.0%) and hydrophobicity (contact angle ≥ 140°), and its performance is long-lasting and durable. This invention's process is environmentally friendly and efficient, suitable for large-scale production.

[0006] This invention combines ingenious molecular design (hydrogen bond pre-assembly) with advanced process technology (photo-initiated polymerization + spraying) to successfully prepare functional paper with many advantages such as high efficiency antibacterial properties, strong hydrophobicity, high durability, environmental protection and energy saving. Its comprehensive performance far exceeds that of existing technologies, and it has extremely high market application value and promotion prospects.

[0007] The technical solution adopted in this invention is as follows: I. A method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization The preparation method of the present invention includes the following steps: (1) At a certain temperature, a certain amount of nanocellulose is added to a dispersible solvent and stirred for a period of time to obtain a nanocellulose suspension; specifically, at 0-90℃, a certain amount of nanocellulose is added to a dispersible solvent and stirred at 200-1000 rpm for 1-48 hours to obtain a nanocellulose suspension.

[0008] Among them, nanocellulose is nanocellulose and its derivatives, specifically at least one of the following polymers: cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), regenerated nanocellulose (RNCs), and bacterial cellulose (BC); the dispersible solvent is at least one of the following solvents: water, dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF); in step (1), the mass ratio of nanocellulose to the dispersible solvent is 1 wt%-15 wt%.

[0009] (2) Dissolve a certain amount of quaternary ammonium salt monomer, organosilane monomer, crosslinking agent and photoinitiator in a polymerizable solvent to obtain a quaternary ammonium salt-organosilane solution.

[0010] The quaternary ammonium salt monomer is a quaternary ammonium salt containing at least one long-chain alkyl group; the organosilane monomer is one of hexadecyltrimethoxysilane (C16-TMS), (meth)acryloyloxypropyltrimethoxysilane (KH-570), vinyltrimethoxysilane (A-171), (3-glycidyl ether oxypropyl)trimethoxysilane (KH-560), and n-octyltriethoxysilane (OTES); the crosslinking agent is at least one of N,N′-methylenebisacrylamide (MBA), ethylene glycol dimethacrylate (EGDMA), polyethylene glycol diacrylate (PEGDA), pentaerythritol tetraacrylate (PETTA), and trimethylolpropane triacrylate (TMPTA); the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methyl-1- The polymerizable solvent is at least one of phenyl-1-propanone, 2,2-dimethoxy-2-phenylacetophenone (DMPA), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), and benzotriazole (BTA); the polymerizable solvent is at least one of water, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), methanol, ethanol, isopropanol, acetone, ethyl acetate, and toluene; the quaternary ammonium salt monomer accounts for 2wt%-15wt% of the quaternary ammonium salt-organosilane solution by mass, the organosilane monomer accounts for 5wt%-15wt% of the quaternary ammonium salt-organosilane solution by mass, the crosslinking agent accounts for 0.1-5wt% of the quaternary ammonium salt-organosilane solution by mass, and the photoinitiator accounts for 0.1-5wt% of the quaternary ammonium salt-organosilane solution by mass; the long-chain alkyl quaternary ammonium salt is a quaternary ammonium salt with a carbon chain length greater than C8.

[0011] In practice, the quaternary ammonium salt monomer is an amphiphilic polymerizable quaternary ammonium salt with a hydrophobic long-chain alkyl group (carbon chain length ≥ C8). Its structure is usually formed by replacing a short-chain alkyl group (such as methyl group) with a long-chain alkyl group on a quaternary ammonium salt core similar to DMC.

[0012] (3) The nanocellulose suspension obtained in step (1) and the quaternary ammonium salt-organosilane solution obtained in step (2) are mixed and then added to the pulp in a certain proportion to obtain a special spraying liquid; specifically, the nanocellulose suspension obtained in step (1) and the quaternary ammonium salt-organosilane solution obtained in step (2) are mixed in a mass ratio of 4:1 to 8:1 to obtain quaternary ammonium silanized nanocellulose, and then the quaternary ammonium silanized nanocellulose is added to the pulp in a mass ratio of 2-10 wt% to obtain a special spraying liquid.

[0013] (4) The special spraying liquid prepared in step (3) is sprayed onto the surface of the substrate, and the sprayed area is simultaneously irradiated with ultraviolet light under a nitrogen atmosphere so that the spraying solution undergoes a photopolymerization reaction on the surface of the substrate and forms a coating on the surface of the substrate, thereby obtaining a substrate with a coating. Finally, the substrate with the coating is subjected to a specific drying treatment to prepare durable antibacterial hydrophobic paper. The substrate is an untreated raw paper blank.

[0014] Specifically, the special spraying liquid prepared in step (3) is added to the inner shell channel of the coaxial spray gun, and nitrogen gas is introduced into the outer layer channel of the coaxial spray gun. Then, the special spraying liquid and nitrogen gas are sprayed onto the substrate simultaneously using the coaxial spray gun, and the sprayed area is irradiated with ultraviolet light while spraying until the spraying is completed, so that the spraying solution undergoes a photopolymerization reaction on the substrate surface and forms a coating on the substrate surface to obtain a substrate with a coating. Finally, the substrate with the coating is subjected to a specific drying treatment to obtain durable antibacterial hydrophobic paper.

[0015] In specific implementation, the special spraying liquid obtained in step (3) is applied vertically and uniformly to the paper base surface through a coaxial spray gun; and during the spraying process, the spraying liquid undergoes a photopolymerization reaction to form an organic-inorganic hybrid composite coating on the paper base surface. The ultraviolet light angle is adjusted to 30-100° and the light source is fixed in the spraying area until the coating is evenly distributed and of moderate thickness. The coaxial spray gun is perpendicular to the paper surface, and the ultraviolet curing device is irradiated in the spraying area by adjusting the angle to achieve simultaneous spraying and photo-induced polymerization. The amount of spraying is controlled until the paper surface is evenly moistened but not dripping.

[0016] The pressure range of the outer channel of the coaxial spray gun is 0.1-8 MPa, the main wavelength of the ultraviolet light is 365 nm, and the intensity range of the ultraviolet light is 100-400 mW / cm². The specific drying method is at least one of vacuum oven drying, atmospheric pressure oven drying, room temperature drying, freeze drying, and supercritical drying.

[0017] II. A durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization The above-described preparation method was used to prepare a durable antibacterial hydrophobic paper based on the combination of in-pulp self-assembly and surface photopolymerization.

[0018] III. Applications of Durable Antibacterial Hydrophobic Paper Based on the Combined Use of In-Pulp Self-Assembly and Surface Photopolymerization Applications of durable antibacterial hydrophobic paper in high-end packaging materials, medical protective equipment, and archival materials.

[0019] This invention combines ingenious molecular design (hydrogen bond pre-assembly) with advanced process technology (photo-initiated polymerization + spraying) to successfully prepare functional paper with many advantages such as high efficiency antibacterial properties, strong hydrophobicity, high durability, environmental protection and energy saving. Its comprehensive performance far exceeds that of existing technologies, and it has extremely high market application value and promotion prospects.

[0020] This invention discloses a method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization. First, a bifunctional nanocellulose solution stably grafted with quaternary ammonium salt and organosilicon through hydrogen bonding is prepared and compounded with polymerizable monomers, photoinitiator pulp, etc., to form a special spraying liquid with high solids content and photocurability. Finally, the spraying liquid is applied to the substrate surface through photoinitiated spraying polymerization technology, and an organic-inorganic hybrid composite coating is instantly formed under synchronous ultraviolet light irradiation. The coating has a chemical cross-linked polymer as the backbone and bifunctional materials as functional enhancement points. By precisely controlling the composition and process parameters of the functional spraying liquid, such as the types of polymer raw materials and polymerizable solvents, the addition ratio of quaternary ammonium silanized nanocellulose in the pulp, the concentration of photoinitiator solution, light intensity, and photoinitiation distance, the structure and performance of the antibacterial hydrophobic paper can be adjusted.

[0021] The antibacterial hydrophobic paper prepared using the method of this invention exhibits an inhibition rate of over 99.0% against both *Escherichia coli* and *Staphylococcus aureus*, with a water contact angle greater than 140°. This method represents a leap from surface modification to bulk phase construction in functional paper production, resulting in extremely durable products with a high degree of process integration. This method combines the functional stability of filler methods with the strong bonding of photopolymerization methods, producing antibacterial hydrophobic paper with superior performance (antibacterial inhibition rate ≥99.0%, water contact angle ≥140°). ° It has excellent durability and is particularly suitable for high-end packaging, medical protection, and archive preservation.

[0022] The beneficial effects of this invention are: (1) Strong functional durability and firm bonding: This is the most significant advantage of this invention. The functional molecules of traditional functional paper are easily detached due to friction or washing, resulting in a rapid decline in performance. This invention uses a triple stabilization mechanism of "hydrogen bond pre-assembly + photopolymerization covalent cross-linking + heat treatment interface strengthening" to firmly fix the functional groups to the paper fibers through chemical bonds. This allows the prepared antibacterial and hydrophobic paper to maintain a high level of antibacterial rate and hydrophobic angle even after multiple washes or frictions, achieving excellent durability.

[0023] (2) High efficiency and environmentally friendly process: This invention abandons the traditional high-energy-consuming and high-polluting process. Its core photo-initiated polymerization process can be completed in just a few minutes at room temperature, reducing energy consumption by more than 60.0% compared with the traditional thermosetting process. At the same time, the spraying technology used can achieve precise and uniform application of raw materials, avoiding the waste and unevenness problems of the impregnation method. The entire process mainly uses water and ethanol as solvents, with low VOC emissions, which is a fast, energy-saving and environmentally friendly green production technology.

[0024] (3) Excellent synergistic effect of dual functions and superior performance: This invention does not simply physically mix antibacterial and hydrophobic functions, but through molecular design, the two functional monomers form a unified covalent network after polymerization, achieving a synergistic effect of "1+1>2". The quaternary ammonium salt component provides efficient and long-lasting contact antibacterial ability (antibacterial rate >99.0%), while the organosilane component constructs a stable low surface energy hydrophobic layer (water contact angle >135°). The synergistic effect of these two functions not only prevents droplet wetting and microbial attachment, but also rapidly kills contact microorganisms, and the comprehensive protective effect far exceeds that of single-function or simple composite products. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the continuous production equipment described in this invention.

[0026] Figure 2 This is a schematic diagram illustrating the formation mechanism of the quaternary ammonium salt-organosilanes bifunctional nanocellulose filler of the present invention. Detailed Implementation

[0027] The present invention will be described in more detail through the following embodiments, but the embodiments do not constitute a limitation of the present invention.

[0028] The embodiments of the present invention are as follows: Example 1

[0029] Substrate used: paper pulp fiber.

[0030] Materials selected: Nanocellulose crystals (NCC), quaternary ammonium salt monomer: methacryloyloxyethyltrimethylammonium chloride (DMC, 80.0% aqueous solution), organosilane monomer: methacryloyloxypropyltrimethoxysilane (KH-570), photoinitiator: 2-hydroxy-2-methyl-1-phenyl-1-propanone (Darocur 1173), solvent: anhydrous ethanol (analytical grade), deionized water.

[0031] This method involves ultrasonically dispersing nanocellulose crystals (NCC) for 30 minutes to obtain a uniform nanocellulose suspension. 13 wt% of a quaternary ammonium monomer (DMC, providing antibacterial properties), 11 wt% (meth)acryloyloxypropyltrimethoxysilane (KH-570), 0.3 wt% crosslinking agent (BP), and 0.5 wt% photoinitiator (Darocur 1173) are dissolved in a water / ethanol mixture. The quaternary ammonium salt-organosilane solution and the modified nanocellulose dispersion are then mixed to prepare quaternary ammonium silanized nanocellulose. The quaternary ammonium silanized nanocellulose is added at 2 wt% to pulp to prepare a special spraying solution. Simultaneous free radical copolymerization is carried out under UV light (100 mW / cm²) and nitrogen protection at a distance of 5 cm between the spraying equipment and the substrate. After the reaction, freeze-drying is performed, successfully synthesizing a photocurable copolymer with both antibacterial and hydrophobic functions. This product can be used to construct durable bifunctional materials with high antibacterial properties.

[0032] Examples 2-5 The addition ratios of quaternary ammonium silanized nanocellulose in the pulp were 4 wt%, 6 wt%, 8 wt%, and 10 wt%, respectively, with the other conditions being the same as in Example 1.

[0033] test Quaternary ammonium silanized nanocellulose addition ratio Antibacterial rate (%) Contact angle (°) Example 1 2 wt% 99.0% 140 Example 2 4 wt% 99.0% 139 Example 3 6 wt% 99.3% 143 Example 4 8 wt% 99.0% 140 Example 5 10 wt% 99.1% 140 Examples 6-9 Replace (meth)acryloyloxypropyltrimethoxysilane (KH-570) in the water / ethanol mixed solvent with: hexadecyltrimethoxysilane (C16-TMS), vinyltrimethoxysilane (A-171), (3-glycidyl etheroxypropyl)trimethoxysilane (KH-560), and n-octyltriethoxysilane (OTES) in sequence. All other conditions are the same as in Example 1.

[0034] test Types of organosilanes Antibacterial rate (%) Contact angle (°) Example 1 KH-570 99.0% 140 Example 6 C16-TMS 99.0% 135 Example 7 A-171 99.0% 137 Example 8 KH-560 99.0% 135 Example 9 OTES 99.0% 137 Examples 10-12 The ultraviolet light intensities of the ultraviolet irradiation system were 200 mW / cm², 300 mW / cm², and 400 mW / cm², respectively, with the other conditions being the same as in Example 1.

[0035] test Ultraviolet light intensity Antibacterial rate (%) Contact angle (°) Example 1 100 mW / cm² 99.0% 140 Example 10 200 mW / cm² 99.0% 139 Example 11 300 mW / cm² 99.0% 137 Example 12 400 mW / cm² 99.0% 137 Examples 13-15 The photoinitiator accounted for 0.2 wt%, 0.7 wt%, and 1 wt% of the spray liquid, respectively, with the remaining conditions being the same as in Example 1.

[0036] test Photoinitiator addition amount Antibacterial rate (%) Contact angle (°) Example 1 0.5 wt% 99.0% 140 Example 13 0.2 wt% 99.0% 137 Example 14 0.7 wt% 99.0% 138 Example 15 1 wt% 99.0% 138 Examples 16-20 Distance from the spraying equipment to the substrate: 5 cm, 10 cm, 15 cm, 20 cm, 25 cm, with other conditions the same as in Example 1.

[0037] test Distance between spraying equipment and substrate (cm) Antibacterial rate (%) Contact angle (°) Example 1 5 cm 99.0% 140 Example 16 10 cm 99.0% 139 Example 17 15 cm 99.0% 139 Example 18 20 cm 99.0% 140 Example 19 25 cm 99.0% 139 The results show that the addition of quaternary ammonium silanized nanocellulose achieves an ideal balance between strength and functionality, significantly enhancing the mechanical properties and coating stability of the paper while ensuring sufficient functional group loading. KH-570, as an organosilane monomer, with its unique double-bond silane bifunctional structure, copolymerizes with quaternary ammonium salts in photopolymerization to form a robust cross-linked network. Simultaneously, it forms chemical bonds with cellulose and fibers through silane hydrolysis, fundamentally improving the coating's adhesion, durability, and hydrophobicity. The efficient and moderate UV curing process rapidly completes polymerization to improve production efficiency while avoiding over-curing, ensuring uniform cross-linking inside and outside the coating. The photoinitiator effectively initiates the reaction while reducing residue. The spraying distance ensures uniform droplet settling and controllable coating thickness. The synergistic effect of these parameters optimizes the production process, resulting in paper that exhibits excellent and stable comprehensive performance in terms of antibacterial properties, hydrophobicity, durability, and mechanical strength. The static water contact angle of the material can be stably maintained at around 140°, demonstrating excellent hydrophobicity. At the same time, the inhibition rate against Escherichia coli and Staphylococcus aureus is approximately 99.0% or higher, showing significant antibacterial effects.

[0038] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization, characterized in that, Includes the following steps: (1) At a certain temperature, a certain amount of nanocellulose is added to a dispersible solvent and stirred for a period of time to obtain a nanocellulose suspension; (2) Dissolve a certain amount of quaternary ammonium salt monomer, organosilane monomer, crosslinking agent and photoinitiator in a polymerizable solvent to obtain a quaternary ammonium salt-organosilane solution; (3) The nanocellulose suspension obtained in step (1) and the quaternary ammonium salt-organosilane solution obtained in step (2) are mixed and then added to the pulp in a certain proportion to prepare a special spraying liquid; (4) The special spraying liquid prepared in step (3) is sprayed onto the surface of the substrate, and the spraying area is simultaneously irradiated with ultraviolet light under a nitrogen atmosphere so that the spraying solution undergoes a photopolymerization reaction on the surface of the substrate and forms a coating on the surface of the substrate to obtain a substrate with a coating. Finally, the substrate with the coating is subjected to a specific drying treatment to prepare a durable antibacterial hydrophobic paper.

2. The method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization according to claim 1, characterized in that, The specific steps (1) are as follows: A certain amount of nanocellulose was added to a dispersible solvent under conditions of 0-90℃, and then stirred to obtain a nanocellulose suspension.

3. The method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization according to claim 1, characterized in that: In step (1), the nanocellulose is at least one of the following polymers: cellulose nanocrystals, cellulose nanofibers, regenerated nanocellulose, and bacterial cellulose; the dispersible solvent is at least one of the following solvents: water, dimethyl sulfoxide, and N,N-dimethylformamide; and in step (1), the mass ratio of the nanocellulose to the dispersible solvent is 1 wt%-15 wt%.

4. The method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization according to claim 1, characterized in that: In step (2), the quaternary ammonium salt monomer is a quaternary ammonium salt containing at least one long-chain alkyl group; the organosilane monomer is one of hexadecyltrimethoxysilane, (meth)acryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, (3-glycidyl ether oxypropyl)trimethoxysilane, and n-octyltriethoxysilane; the crosslinking agent is at least one of N,N′-methylenebisacrylamide, ethylene glycol dimethacrylate, polyethylene glycol diacrylate, pentaerythritol tetraacrylate, and trimethylolpropane triacrylate; the photoinitiator is at least one of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 2,2-dimethoxy-2 At least one of phenylacetophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and benzotriazole; the polymerizable solvent is at least one of water, dimethyl sulfoxide, N,N-dimethylformamide, methanol, ethanol, isopropanol, acetone, ethyl acetate, and toluene; the quaternary ammonium salt monomer accounts for 2wt%-15wt% of the quaternary ammonium salt-organosilane solution by mass, the organosilane monomer accounts for 5wt%-15wt% of the quaternary ammonium salt-organosilane solution by mass, the crosslinking agent accounts for 0.1-5wt% of the quaternary ammonium salt-organosilane solution by mass, and the photoinitiator accounts for 0.1-5wt% of the quaternary ammonium salt-organosilane solution by mass; the long-chain alkyl quaternary ammonium salt is a quaternary ammonium salt with a carbon chain length greater than C8.

5. The method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization according to claim 1, characterized in that, The specific steps (3) are as follows: The nanocellulose suspension obtained in step (1) and the quaternary ammonium salt-organosilane solution obtained in step (2) are mixed at a mass ratio of 4:1 to 8:1 to obtain quaternary ammonium silanized nanocellulose. Then, the quaternary ammonium silanized nanocellulose is added to the pulp at 2-10 wt% to prepare a special spraying liquid.

6. The method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization according to claim 1, characterized in that, Step (4) specifically involves: The special spraying liquid and nitrogen gas prepared in step (3) are sprayed onto the substrate simultaneously using a coaxial spray gun. At the same time, the sprayed area is irradiated with ultraviolet light to cause the spraying solution to undergo a photopolymerization reaction on the substrate surface to form a coating, thereby obtaining a substrate with a coating. Finally, a specific drying treatment is performed to obtain the durable antibacterial hydrophobic paper.

7. The method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization according to claim 6, characterized in that: The pressure range of the outer channel of the coaxial spray gun is 0.1-8 MPa, the main wavelength of the ultraviolet light is 365 nm, and the intensity range of the ultraviolet light is 100-400 mW / cm².

8. The method for preparing durable antibacterial hydrophobic paper based on the combined use of in-pulp self-assembly and surface photopolymerization according to claim 6, characterized in that: In step (4), the specific drying is at least one of vacuum oven drying, atmospheric pressure oven drying, room temperature drying, freeze drying, and supercritical drying.

9. A durable antibacterial hydrophobic paper based on a combination of in-pulp self-assembly and surface photopolymerization, characterized in that: It is prepared by any one of the preparation methods described in claims 1-8.

10. The application of a durable antibacterial hydrophobic paper obtained by the preparation method according to any one of claims 1-8, characterized in that: Applications in high-end packaging materials, medical protective equipment, and archival materials.

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