Antibacterial silicon nitride fiber composite material and preparation method and application thereof

Abstract

The application discloses an antibacterial silicon nitride fiber composite material and a preparation method and application thereof, belongs to the technical field of silicon nitride composite materials, and is prepared by preparing a pretreated fiber base material, preparing modified alpha-phase silicon nitride powder, preparing a composite bonding solution, preparing a composite slurry, padding, and cross-linking to obtain the antibacterial silicon nitride fiber composite material. The antibacterial silicon nitride fiber composite material prepared by the application has excellent and long-acting and stable antibacterial and antiviral performances, high-efficiency bacteriostasis is realized by virtue of the synergistic effect of the antibacterial performance of alpha-phase silicon nitride and the nano antibacterial component, and the combination firmness of the antibacterial component and the base material is improved by optimizing the composite process, so that excellent antibacterial effect can be maintained after long-term use.

Description

Technical Field

[0001] This invention relates to the field of silicon nitride composite materials technology, specifically to an antibacterial silicon nitride fiber composite material, its preparation method, and its application. Background Technology

[0002] Silicon nitride, as a high-performance non-oxide ceramic material, has been applied in fields such as biomedical implants. Its good biocompatibility has been verified through long-term practice, which provides important support for the applicant to explore new application directions of this material.

[0003] In recent years, the demand for efficient, safe, and long-lasting antimicrobial materials has become increasingly urgent in fields such as personal protective equipment, medical environmental consumables, and air filtration systems. Existing antimicrobial materials have significant shortcomings. Organic antimicrobial agents have poor stability, short duration of action, and may lead to drug resistance. Metal-based antimicrobial materials (such as copper and silver) pose a risk of biotoxicity, are prone to oxidation and failure, and are costly. Traditional inorganic materials generally face problems such as insufficient antimicrobial activity and poor compatibility with substrates, making it difficult to balance practical performance and safety, and failing to meet the stringent requirements of high-end protective scenarios.

[0004] Related research (Heath et al., 2025, DOI: 10.3389 / fmicb.2025.1637848) shows that silicon nitride undergoes surface hydrolysis when exposed to humid environments such as water vapor, releasing active nitrogen-based substances that can disrupt the structure and metabolic processes of viruses and other microorganisms, demonstrating antimicrobial potential. This study also confirmed that among the two main crystal configurations of silicon nitride, α-phase silicon nitride exhibits superior antimicrobial activity, and its biocompatibility has been further validated through clinical applications such as FDA-approved spinal fusion implants. It has no significant biotoxicity and offers a greater safety advantage compared to traditional metal-based antimicrobial materials.

[0005] However, the above studies have only preliminarily confirmed the antimicrobial potential of silicon nitride. In practical applications, it still faces many unresolved technical bottlenecks. When silicon nitride powder is combined with fiber materials, problems such as insufficient durability and inadequate release of antimicrobial activity may occur, making it difficult for the protective effect and durability of the composite material to meet the actual use requirements.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] To address the aforementioned shortcomings of existing technologies, this invention provides a method for preparing an antibacterial silicon nitride fiber composite material, comprising the following steps:

[0008] S1: The polylactic acid fiber is completely immersed in an aqueous sodium hydroxide solution and stirred. After rinsing, it is dried to obtain the pretreated fiber substrate.

[0009] S2: Add α-phase silicon nitride powder to a mixed solvent to prepare a suspension, add silane coupling agent, stir and centrifuge, collect the lower solid powder, and dry to obtain modified α-phase silicon nitride powder;

[0010] S3: Weigh polyvinyl alcohol and chitosan and add them to water. Stir to obtain a binding solution. Add a mixture of nano zinc oxide and nano titanium dioxide to the binding solution and continue stirring to obtain a composite binding solution.

[0011] S4: Mix modified α-phase silicon nitride powder and composite binder solution at a mass ratio of 4-8:3, add dispersant, stir and ultrasonically cycle 3-4 times, and then filter to obtain composite slurry;

[0012] S5: Impregnate the pretreated fiber substrate in the composite slurry and dry it to obtain the baked composite material;

[0013] S6: The baked composite material is immersed in a dialdehyde xylose aqueous solution for crosslinking. After crosslinking is completed, it is rinsed and dried to obtain an antibacterial silicon nitride fiber composite material.

[0014] Furthermore, S1 specifically involves: completely immersing polylactic acid fibers in a 0.1-0.5 wt% sodium hydroxide aqueous solution, stirring at 25-50℃ for 10-30 min, repeatedly rinsing with deionized water until neutral, and drying in a 60-85℃ forced-air drying oven for 2-6 h to obtain a pretreated fiber substrate.

[0015] Furthermore, S2 specifically involves: taking α-phase silicon nitride powder and adding it to a mixed solvent of deionized water and ethanol at a volume ratio of 1:1-3 to prepare a suspension of 5-12 wt%. Then, adding 0.5-2.0% of a silane coupling agent (based on the mass of the α-phase silicon nitride powder) to the suspension, stirring at 150-250 r / min for 30-60 min at 30-50℃, centrifuging at 3000-6000 r / min for 8-10 min, collecting the lower solid powder layer, and drying it in an oven at 80-110℃ for 4-8 h to obtain modified α-phase silicon nitride powder.

[0016] Furthermore, the silane coupling agent is composed of N-phenyl-3-aminopropyltrimethoxysilane and bis-(3-(triethoxysilane)propyl)-tetrasulfide in a mass ratio of 3-4:2.

[0017] Furthermore, S3 specifically involves: adding polyvinyl alcohol and chitosan to deionized water at a mass ratio of 3:1-6, stirring at 200-300 r / min at 70-90℃ until completely dissolved, to obtain a 3-8 wt% adhesive solution; adding a mixture of nano zinc oxide and nano titanium dioxide at a total mass of 2.5-4% to the adhesive solution, and continuing to stir for 30-60 min to obtain a composite adhesive solution.

[0018] Furthermore, the mass ratio of the nano zinc oxide to the nano titanium dioxide is 3:1-3.

[0019] Furthermore, S4 specifically involves mixing modified α-phase silicon nitride powder and composite binder solution at a mass ratio of 4-8:3, adding dispersant at 0.1-0.5% of the total mass of composite binder solution, stirring at 200-400 r / min for 1-2 h, ultrasonically dispersing at 150-300 W for 20-40 min, cycling 3-4 times, and then filtering with a 100-200 mesh screen to obtain the composite slurry.

[0020] Furthermore, S5 specifically involves: immersing the pretreated fiber substrate into the composite slurry using an impregnation equipment at a pressure of 0.1-0.3 MPa and a speed of 0.5-2.0 m / min; after impregnation, pre-drying it in an 80-100℃ forced-air drying oven for 1-3 hours, and then baking it in an oven at 100-120℃ for 2-4 hours to obtain the baked composite material.

[0021] An antibacterial silicon nitride fiber composite material prepared according to the preparation method described above.

[0022] An application of the aforementioned antibacterial silicon nitride fiber composite material in the preparation of antiviral / antibacterial protective products, air purification materials, and food contact antibacterial materials.

[0023] Compared with the prior art, the beneficial effects of this invention are as follows:

[0024] 1. The antibacterial silicon nitride fiber composite material prepared by this invention has excellent antibacterial and antiviral properties and is stable for a long time. The active nitrogen substances (such as amino and imino groups) generated by the hydrolysis of α-phase silicon nitride in a humid environment can precisely destroy the integrity of microbial cell membranes and nucleic acid metabolism processes. Nano-ZnO / TiO2 generates hydroxyl radicals through photocatalysis, which attack microbial protein and enzyme systems. Both achieve dual antibacterial effect by destroying structure and blocking metabolism, resulting in an antibacterial rate of over 99% and antiviral activity against H1N1 and SARS-CoV-2 exceeding 99.5%, achieving highly efficient antibacterial effect.

[0025] Silane coupling agents (N-phenyl-3-aminopropyltrimethoxysilane and bis-(3-(triethoxysilane)propyl)-tetrasulfide in a 3-4:2 ratio) modify the surface of α-phase silicon nitride powder, reducing particle surface energy and preventing agglomeration.Figure 4 Verification showed that the modified particles were evenly dispersed, ensuring full contact between the antibacterial components and the bonding system. Xylaldehyde dialdehyde, as a crosslinking agent, formed stable covalent bonds between the aldehyde group and the hydroxyl group of polyvinyl alcohol and the amino group of chitosan, fixing the antibacterial components on the substrate surface. After 80 standard washes, the antibacterial rate was still ≥95%, which ensured that the excellent antibacterial effect could be maintained even after long-term use.

[0026] 2. The antibacterial silicon nitride fiber composite material prepared by this invention has high biosafety and does not release toxic ions. The polyvinyl alcohol and chitosan in the bonding system are natural or synthetic biocompatible polymers. The degradation products are carbon dioxide and water, with no residual pollution. No organic solvents or heavy metal catalysts are used throughout the process. The material extract has been tested and meets the level 0 non-toxic standard. It is suitable for medical protection, food contact and other scenarios, and has no potential toxicity hazards.

[0027] 3. This invention optimizes the substrate pretreatment process and composite process. Polyvinyl alcohol provides good film-forming properties and flexibility, while chitosan enhances bonding strength and antibacterial auxiliary effect. The two are fully dissolved to form a uniform adhesive solution, which not only ensures the firm adhesion of the antibacterial components, but also avoids the problem of material embrittlement or easy deformation. The step-by-step baking process of "80-100℃ pre-baking + 100-120℃ baking" removes moisture first to prevent the slurry from flowing, and then promotes bonding and cross-linking reaction through high temperature. This makes the material have both excellent tensile strength and good flexibility, which meets the needs of protective equipment, air purification materials and other products to resist deformation and friction during use. The mechanical properties are stable and reliable. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0029] Figure 1 The infrared spectrum of the antibacterial silicon nitride fiber composite material prepared in Example 4 of this invention;

[0030] Figure 2 The image shows the XRD pattern of the antibacterial silicon nitride fiber composite material prepared in Example 4 of this invention.

[0031] Figure 3 Thermogravimetric analysis diagram of the antibacterial silicon nitride fiber composite material prepared in Example 4 of the present invention;

[0032] Figure 4 This is an electron microscope image of the modified α-phase silicon nitride powder prepared in Example 1 of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] Example 1: This example discloses a method for preparing an antibacterial silicon nitride fiber composite material, including the following steps:

[0035] S1: The polylactic acid fiber was completely immersed in a 0.1wt% sodium hydroxide aqueous solution, stirred at 25°C for 10 min, rinsed repeatedly with deionized water until neutral (pH=7±0.5), and dried in a 60°C forced-air drying oven for 2 h to obtain the pretreated fiber substrate.

[0036] S2: Take α-phase silicon nitride powder and add it to a mixed solvent of deionized water and ethanol with a volume ratio of 1:1 to prepare a 5wt% suspension. Add 0.5% of silane coupling agent (made of N-phenyl-3-aminopropyltrimethoxysilane and bis-(3-(triethoxysilane)propyl)-tetrasulfide with a mass ratio of 3:2) to the suspension. Stir at 150 r / min for 30 min at 30℃, centrifuge at 3000 r / min for 8 min, collect the lower solid powder, and dry it in an oven at 80℃ for 4 h to obtain modified α-phase silicon nitride powder.

[0037] Figure 4 The image shows a scanning electron microscope (SEM) image of the modified α-phase silicon nitride powder (5000x magnification, scale bar 5 μm). The modified α-phase silicon nitride powder exists as independent, dispersed particles without large-area agglomerates, and the particles are uniform in size and regularly distributed. This confirms the modification effect of the silane coupling agent (a combination of N-phenyl-3-aminopropyltrimethoxysilane and bis-(3-(triethoxysilane)propyl)-tetrasulfide) in step S2. The coupling agent reduces the surface energy of the silicon nitride powder through surface modification, thus inhibiting the agglomeration tendency between particles.

[0038] S3: Polyvinyl alcohol (PVA-203) and chitosan were added to deionized water at a mass ratio of 3:1 and stirred at 200 r / min at 70℃ until completely dissolved to obtain a 3wt% adhesive solution. A mixture of nano zinc oxide and nano titanium dioxide (mass ratio of nano zinc oxide and nano titanium dioxide of 1:1) was added to the adhesive solution at a mass ratio of 2.5% of its total mass and stirred for 30 min to obtain a composite adhesive solution.

[0039] S4: Mix the modified α-phase silicon nitride powder and the composite binder solution at a mass ratio of 4:3, add a dispersant (lignin sulfonate) at 0.1% of the total mass of the composite binder solution, stir at 200 r / min for 1 h, then ultrasonically disperse at 150 W for 20 min, cycle 3 times, and filter with a 100-200 mesh screen to obtain the composite slurry;

[0040] S5: The pretreated fiber substrate is immersed in the composite slurry at 0.1 MPa and 0.5 m / min through an impregnation equipment. After impregnation, it is pre-dried in an 80℃ forced-air drying oven for 1 hour, and then baked in a 100℃ oven for 2 hours to obtain the baked composite material.

[0041] S6: The baking composite material was immersed in a 5wt% xylose dialdehyde aqueous solution and crosslinked at 25℃ for 10 min. After crosslinking, it was rinsed with deionized water, dried in a 60℃ forced-air drying oven for 2 h, and naturally cooled to room temperature to obtain the antibacterial silicon nitride fiber composite material.

[0042] Example 2: This example discloses a method for preparing an antibacterial silicon nitride fiber composite material, including the following steps:

[0043] S1: The polylactic acid fiber was completely immersed in a 0.5wt% sodium hydroxide aqueous solution, stirred at 50℃ for 30 min, rinsed repeatedly with deionized water until neutral (pH=7±0.5), and dried in an 85℃ forced-air drying oven for 6 h to obtain the pretreated fiber substrate.

[0044] S2: Take α-phase silicon nitride powder and add it to a mixed solvent of deionized water and ethanol with a volume ratio of 1:3 to prepare a 12wt% suspension. Add 2.0% of silane coupling agent (made of N-phenyl-3-aminopropyltrimethoxysilane and bis-(3-(triethoxysilane)propyl)-tetrasulfide with a mass ratio of 4:2) to the suspension. Stir at 250 r / min for 60 min at 50 °C, centrifuge at 6000 r / min for 10 min, collect the lower solid powder, and dry it in an oven at 110 °C for 8 h to obtain modified α-phase silicon nitride powder.

[0045] S3: Polyvinyl alcohol and chitosan were added to deionized water at a mass ratio of 3:6 and stirred at 300 r / min at 90℃ until completely dissolved to obtain an 8wt% adhesive solution. A mixture of nano zinc oxide and nano titanium dioxide (mass ratio of nano zinc oxide and nano titanium dioxide of 3:1) was added to the adhesive solution at a mass ratio of 4% of its total mass. Stirring was continued for 60 min to obtain a composite adhesive solution.

[0046] S4: Mix the modified α-phase silicon nitride powder and the composite binder solution at a mass ratio of 8:3, add dispersant (sodium polycarboxylate) at 0.5% of the total mass of the composite binder solution, stir at 400 r / min for 2 h, then ultrasonically disperse at 300 W for 40 min, cycle 4 times, and then filter with a 100-200 mesh screen to obtain the composite slurry;

[0047] S5: The pretreated fiber substrate is immersed in the composite slurry at 0.3 MPa and 2.0 m / min through an impregnation equipment. After impregnation, it is pre-dried in a 100℃ forced-air drying oven for 3 hours and then baked in a 120℃ oven for 4 hours to obtain the baked composite material.

[0048] S6: The baking composite material was immersed in a 9wt% xylose dialdehyde aqueous solution and crosslinked at 40℃ for 20 min. After crosslinking, it was rinsed with deionized water, placed in an 80℃ forced-air drying oven for 4 h, and naturally cooled to room temperature to obtain the antibacterial silicon nitride fiber composite material.

[0049] Example 3: This example discloses a method for preparing an antibacterial silicon nitride fiber composite material, including the following steps:

[0050] S1: The polylactic acid fiber was completely immersed in a 0.35wt% sodium hydroxide aqueous solution, stirred at 34℃ for 22min, rinsed repeatedly with deionized water until neutral (pH=7±0.5), and dried in a 74℃ forced-air drying oven for 4h to obtain the pretreated fiber substrate.

[0051] S2: Take α-phase silicon nitride powder and add it to a mixed solvent of deionized water and ethanol with a volume ratio of 1:2.4 to prepare an 8wt% suspension. Add 1.2% of silane coupling agent (made of N-phenyl-3-aminopropyltrimethoxysilane and bis-(3-(triethoxysilane)propyl)-tetrasulfide with a mass ratio of 3:2) to the suspension. Stir at 180 r / min for 46 min at 44 °C, centrifuge at 4600 r / min for 9 min, collect the lower solid powder, and dry it in an oven at 96 °C for 6 h to obtain modified α-phase silicon nitride powder.

[0052] S3: Polyvinyl alcohol and chitosan were added to deionized water at a mass ratio of 3:3 and stirred at 240 r / min at 82℃ until completely dissolved to obtain a 5.6 wt% binder solution. A mixture of nano zinc oxide and nano titanium dioxide (mass ratio of nano zinc oxide to nano titanium dioxide of 3:2) was added to the binder solution at a mass ratio of 3.2% and stirred for 47 min to obtain a composite binder solution.

[0053] S4: The modified α-phase silicon nitride powder and the composite binder solution are mixed at a mass ratio of 6.7:3. A dispersant (composed of lignin sulfonate and sodium polycarboxylate in a mass ratio of 1:3) is added at 0.3% of the total mass of the composite binder solution. The mixture is stirred at 280 r / min for 2 h and then ultrasonically dispersed at 210 W for 32 min. After 4 cycles, the mixture is filtered through a 100-200 mesh screen to obtain the composite slurry.

[0054] S5: The pretreated fiber substrate is immersed in the composite slurry at 0.2 MPa and 1.2 m / min through an impregnation equipment. After impregnation, it is pre-dried in an 88℃ forced-air drying oven for 2 hours and then baked in a 108℃ oven for 3 hours to obtain the baked composite material.

[0055] S6: The baked composite material was immersed in an 8.2wt% xylose dialdehyde aqueous solution and crosslinked at 33℃ for 17 min. After crosslinking, it was rinsed with deionized water, dried in a 72℃ forced-air drying oven for 3 h, and naturally cooled to room temperature to obtain the antibacterial silicon nitride fiber composite material.

[0056] Example 4: This example discloses a method for preparing an antibacterial silicon nitride fiber composite material, comprising the following steps:

[0057] S1: The polylactic acid fiber was completely immersed in a 0.42wt% sodium hydroxide aqueous solution, stirred at 44℃ for 16min, rinsed repeatedly with deionized water until neutral (pH=7±0.5), and dried in a 66℃ forced-air drying oven for 5h to obtain the pretreated fiber substrate.

[0058] S2: Take α-phase silicon nitride powder and add it to a mixed solvent of deionized water and ethanol with a volume ratio of 1:1.7 to prepare a 10wt% suspension. Add 1.7% of silane coupling agent (made of N-phenyl-3-aminopropyltrimethoxysilane and bis-(3-(triethoxysilane)propyl)-tetrasulfide with a mass ratio of 3.3:2) to the suspension. Stir at 210 r / min for 56 min at 48℃, centrifuge at 5200 r / min for 10 min, collect the lower solid powder, and dry it in an oven at 108℃ for 7 h to obtain modified α-phase silicon nitride powder.

[0059] S3: Polyvinyl alcohol and chitosan were added to deionized water at a mass ratio of 3:5.2 and stirred at 280 r / min at 77℃ until completely dissolved to obtain a 7.2 wt% binder solution. A mixture of nano zinc oxide and nano titanium dioxide (mass ratio of nano zinc oxide and nano titanium dioxide of 1:1) was added to the binder solution at a mass ratio of 3.8% and stirred for 56 min to obtain a composite binder solution.

[0060] S4: The modified α-phase silicon nitride powder and the composite binder solution were mixed at a mass ratio of 5.2:3. A dispersant (composed of lignin sulfonate and sodium polycarboxylate in a mass ratio of 1:1) was added at 0.4% of the total mass of the composite binder solution. The mixture was stirred at 340 r / min for 2 h and then ultrasonically dispersed at 180 W for 27 min. After 4 cycles, the mixture was filtered through a 100-200 mesh screen to obtain the composite slurry.

[0061] S5: The pretreated fiber substrate is immersed in the composite slurry at 0.1 MPa and 1.5 m / min through an impregnation equipment. After impregnation, it is pre-dried in a 96℃ forced-air drying oven for 3 hours and then baked in a 114℃ oven for 2 hours to obtain the baked composite material.

[0062] S6: The baking composite material was immersed in a 6.8wt% xylose dialdehyde aqueous solution and crosslinked at 37℃ for 14 min. After crosslinking, it was rinsed with deionized water, dried in a 66℃ forced-air drying oven for 2 h, and naturally cooled to room temperature to obtain the antibacterial silicon nitride fiber composite material.

[0063] Comparative Example 1: The difference between this comparative example and Example 4 is that the polylactic acid fiber was not pretreated.

[0064] Comparative Example 2: The difference between this comparative example and Example 4 is that the amount of silane coupling agent added in S2 is 5% of the mass of α-phase silicon nitride powder.

[0065] Comparative Example 3: The difference between this comparative example and Example 4 is that the mass ratio of nano zinc oxide to nano titanium dioxide in S3 is 3:7.

[0066] Comparative Example 4: This comparative example differs from Example 4 in that the mixture of nano zinc oxide and nano titanium dioxide accounts for 8% of the total mass of the binder solution.

[0067] Characterization example: The antibacterial silicon nitride fiber composite material prepared in Example 4 was subjected to infrared, XRD and thermogravimetric analysis.

[0068] (1) Infrared characterization experiment;

[0069] Infrared spectrum as shown Figure 1 As shown, α-phase silicon nitride at 930-950 cm⁻¹ -1 A strong absorption peak appears, corresponding to the stretching vibration of the Si-N bond; the characteristic peak of silicon nitride is in the 480-520 cm⁻¹ range. -1 The appearance of a weak absorption peak corresponds to the bending vibration of the Si-N bond, proving that the modified α-phase silicon nitride powder was successfully composited.

[0070] Nano zinc oxide at 420-450cm -1 The presence of characteristic absorption peaks corresponds to the stretching vibrations of the Zn-O bond; nano-titanium dioxide exhibits absorption peaks in the 500-650 cm⁻¹ range.-1 The broad absorption peaks correspond to the vibrations of the Ti-O bonds, and the two peaks partially overlap, which together confirms the effective incorporation of the nano-antibacterial components.

[0071] Polyvinyl alcohol at 3200-3500cm -1 A broad and strong absorption peak appears, corresponding to the stretching vibration of the OH bond; 2850-2950 cm⁻¹ -1 The peak range is for the stretching vibrations of CH bonds (methyl, methylene); 1080-1150 cm⁻¹ -1 The peak represents the stretching vibration of the COC bond;

[0072] The characteristic peak of chitosan is the stretching vibration of the NH bond (amino group) at 3200-3500 cm⁻¹. -1 The peak overlaps with the stretching vibration peak of the OH bond in polyvinyl alcohol; 1630-1650 cm⁻¹ -1 It is an amide I band (C=O stretching vibration), 1550-1580 cm. -1 It is an amide II band (NH bending vibration);

[0073] Polylactic acid substrate at 1730-1750cm -1 A strong absorption peak appears, corresponding to the stretching vibration of the ester group (C=O); 1050-1180 cm⁻¹ -1 The peak represents the stretching vibration of the CO bond.

[0074] (2) XRD characterization experiment;

[0075] XRD diagram as follows Figure 2 As shown, the core α-phase silicon nitride, as the main antibacterial component of the composite material, exhibits the highest diffraction peak intensity and sharpest peak shape. The characteristic diffraction angles (2θ) and corresponding crystal planes are as follows: 2θ=16.7°, crystal plane (100); 2θ=21.2°, crystal plane (101); 2θ=25.0°, crystal plane (110); 2θ=27.8°, crystal plane (102); 2θ=33.3°, crystal plane (111); 2θ=36.9°, crystal plane (201); 2θ=43.6°, crystal plane (210); 2θ=52.2°, crystal plane (211).

[0076] The characteristic diffraction angles and corresponding crystal planes of the nano-antibacterial component ZnO are as follows: 2θ=31.6°, crystal plane (100); 2θ=34.5°, crystal plane (002); 2θ=36.1°, crystal plane (101); 2θ=47.3°, crystal plane (102); 2θ=56.7°, crystal plane (110); 2θ=62.9°, crystal plane (103); 2θ=67.7°, crystal plane (112).

[0077] The characteristic diffraction angles and corresponding crystal planes of the nano-antibacterial component TiO2 are as follows: 2θ=25.3°, crystal plane (101); 2θ=37.8°, crystal plane (004); 2θ=48.0°, crystal plane (200); 2θ=53.9°, crystal plane (105); 2θ=55.0°, crystal plane (211); 2θ=62.7°, crystal plane (204); 2θ=68.8°, crystal plane (116); 2θ=70.3°, crystal plane (220).

[0078] (3) Thermogravimetric analysis experiment;

[0079] Thermogravimetric analysis results are as follows Figure 3 As shown, below 200℃, the composite material only shows a small mass loss (2.31%), corresponding to the volatilization of surface adsorbed water and residual solvent; in the 200-350℃ range, a slow mass loss (7.58%) occurs, mainly due to the decomposition of low molecular weight components in the bonding system; in the 350-500℃ range, the main mass loss peak (43.26%) appears, corresponding to the thermal decomposition of polylactic acid matrix and bonding system; after 600℃, the residual mass ratio stabilizes at around 30%, mainly due to the residue of inorganic antibacterial components (silicon nitride, zinc oxide, titanium dioxide).

[0080] Experiment Example 1: Antiviral activity detection;

[0081] The antiviral activity of the antibacterial silicon nitride fiber composite material prepared in this invention was tested according to ISO 18184:2019 "Determination of antiviral activity of textiles".

[0082] The samples were cut into 2.5cm × 2.5cm pieces and sterilized with ultraviolet light for 30 minutes for later use. The control group was prepared by cutting unmodified blank substrate (pure polylactic acid sheet) into the same size and sterilizing it in the same way.

[0083] Virus strains (two groups in total): (1) Influenza A virus H1N1 strain; host cells: MDCK cells (canine kidney epithelial cells), which were cultured in DMEM medium containing 10% fetal bovine serum to the logarithmic growth phase after resuscitation;

[0084] (2) SARS-CoV-2 strain, host cell: Vero cells (African green monkey kidney cells), after resuscitation, cultured in DMEM medium containing 10% fetal bovine serum to the logarithmic growth phase;

[0085] The virus strain was inoculated into a host cell monolayer (T25 culture flask) and cultured in a 37°C, 5% CO2 incubator. When the cytopathic effect (CPE) reached more than 70%, the virus fluid was harvested.

[0086] The initial viral titer was determined by plaque assay, and the viral solution was diluted to the initial 1gTCID using maintenance medium (DMEM containing 2% fetal bovine serum). 50 The viral working solution was obtained with a concentration of 6.49 g / mL.

[0087] Add 0.2 mL of viral working solution to each sample, spread them, and incubate them at 37°C and 5% CO2 for 24 h. Then recover the viral solution. Perform 10-fold serial dilutions on the recovered viral solution. In a 96-well cell plate, seed each well with 100 μL of logarithmic-phase MDCK cell suspension (1 × 10⁻⁶ cells). 5 (cells / mL), culture for 24 hours until a cell monolayer forms;

[0088] Discard the culture medium in each well, add 100 μL of diluted virus solution to each well, and set up 3 replicates for each dilution; calculate the median tissue culture infectious dose (TCID) of the virus for each group using the Reed-Muench method. 50 ), and convert it to a logarithmic value (lgTCID) 50 / mL);

[0089] Calculate the antiviral activity value and antiviral activity (%).

[0090]

[0091]

[0092] The results are shown in Table 1:

[0093] Table 1. Results of antiviral activity assays for Examples 1-4 and Comparative Examples 1-4

[0094]

[0095] As shown in the table above, the antibacterial silicon nitride fiber composite material prepared in the embodiments of the present invention has an antiviral activity of over 99.5% against both influenza A virus H1N1 and SARS-CoV-2; the antiviral activity of each comparative example is slightly reduced.

[0096] Experimental Example 2: The average antibacterial rate (%) of the antibacterial silicon nitride fiber composite material prepared by the present invention was tested according to GB / T 21510-2024. The results were taken as the average antibacterial rate of Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 25922), and Candida albicans (ATCC 10231).

[0097] Experimental Example 3: Following the method of GB / T 12490-2014, the antibacterial silicon nitride fiber composite material prepared in this invention was subjected to 80 standard washes, and the steps of Experimental Example 1 were repeated to detect the average antibacterial rate (%) after washing.

[0098] Experimental Example 4: The cytotoxicity level of the antibacterial silicon nitride fiber composite material extract prepared in this invention was tested according to GB / T 16886.5-2017 (Level 0: non-toxic, Level 1: slightly toxic, Level 2: mildly toxic, Level 3: moderately toxic, Level 4: severely toxic).

[0099] Experimental Example 5: The breaking strength and elongation at break of the antibacterial silicon nitride fiber composite material prepared according to GB / T 3923.1-2013 were tested.

[0100] The results are shown in Table 2:

[0101] Table 2. Detection results of Examples 1-4 and Comparative Examples 1-4

[0102]

[0103] As shown in the table above, the antibacterial silicon nitride fiber composite material prepared by this invention has significant core advantages, with an antibacterial rate of ≥99%, an antibacterial rate of ≥95% after 80 washes, and all of them are grade 0 non-toxic. The tensile strength and elongation at break remain stable, and the overall performance is excellent.

[0104] Pretreatment of polylactic acid fibers can improve the mechanical properties of materials. Excessive addition of silane coupling agents has no significant effect on performance improvement. When the ratio of nano zinc oxide to nano titanium dioxide deviates from the range of 3:1-3 or the amount of mixture added exceeds the range of 2.5-4%, the antibacterial durability will be significantly reduced.

[0105] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an antibacterial silicon nitride fiber composite material, characterized in that, Includes the following steps: S1: The polylactic acid fiber is completely immersed in an aqueous sodium hydroxide solution and stirred. After rinsing, it is dried to obtain the pretreated fiber substrate. S2: Add α-phase silicon nitride powder to a mixed solvent to prepare a suspension. Add 0.5-2.0% (by mass of α-phase silicon nitride powder) of silane coupling agent to the suspension, stir, centrifuge, collect the lower solid powder, and dry to obtain modified α-phase silicon nitride powder. The silane coupling agent is composed of N-phenyl-3-aminopropyltrimethoxysilane and bis-(3-(triethoxysilane)propyl)-tetrasulfide in a mass ratio of 3-4:

2. S3: Weigh polyvinyl alcohol and chitosan and add them to water, stir to obtain a binding solution, add 2.5-4% of the total mass of a mixture of nano zinc oxide and nano titanium dioxide to the binding solution, and continue stirring to obtain a composite binding solution; the mass ratio of nano zinc oxide and nano titanium dioxide is 3:1-3; S4: Mix modified α-phase silicon nitride powder and composite binder solution at a mass ratio of 4-8:3, add dispersant, stir and ultrasonically cycle 3-4 times, and then filter to obtain composite slurry; S5: Impregnate the pretreated fiber substrate in the composite slurry and dry it to obtain the baked composite material; S6: The baked composite material is immersed in a dialdehyde xylose aqueous solution for crosslinking. After crosslinking is completed, it is rinsed and dried to obtain an antibacterial silicon nitride fiber composite material.

2. The method for preparing the antibacterial silicon nitride fiber composite material according to claim 1, characterized in that, S1 specifically involves: completely immersing polylactic acid fibers in a 0.1-0.5 wt% sodium hydroxide aqueous solution, stirring at 25-50℃ for 10-30 minutes, rinsing repeatedly with deionized water until neutral, and drying in a 60-85℃ forced-air drying oven for 2-6 hours to obtain a pretreated fiber substrate.

3. The method for preparing the antibacterial silicon nitride fiber composite material according to claim 1, characterized in that, S2 is specifically as follows: Take α-phase silicon nitride powder and add it to a mixed solvent of deionized water and ethanol with a volume ratio of 1:1-3 to prepare a suspension of 5-12 wt%. Add 0.5-2.0% of silane coupling agent by mass of α-phase silicon nitride powder to the suspension, stir at 150-250 r / min for 30-60 min at 30-50℃, centrifuge at 3000-6000 r / min for 8-10 min, collect the lower solid powder, and dry it in an oven at 80-110℃ for 4-8 h to obtain modified α-phase silicon nitride powder.

4. The method for preparing the antibacterial silicon nitride fiber composite material according to claim 1, characterized in that, S3 is specifically as follows: Polyvinyl alcohol and chitosan are added to deionized water at a mass ratio of 3:1-6, and stirred at 200-300 r / min at 70-90℃ until completely dissolved to obtain a 3-8 wt% adhesive solution. A mixture of nano zinc oxide and nano titanium dioxide with a total mass of 2.5-4% is added to the adhesive solution, and stirring is continued for 30-60 min to obtain a composite adhesive solution.

5. The method for preparing the antibacterial silicon nitride fiber composite material according to claim 1, characterized in that, S4 specifically involves mixing modified α-phase silicon nitride powder and composite binder solution at a mass ratio of 4-8:3, adding dispersant at 0.1-0.5% of the total mass of composite binder solution, stirring at 200-400 r / min for 1-2 h, ultrasonically dispersing at 150-300 W for 20-40 min, cycling 3-4 times, and then filtering with a 100-200 mesh screen to obtain the composite slurry.

6. The method for preparing the antibacterial silicon nitride fiber composite material according to claim 1, characterized in that, S5 specifically involves: immersing the pretreated fiber substrate into the composite slurry using a padding device at 0.1-0.3 MPa and 0.5-2.0 m / min; after padding, pre-drying in an 80-100℃ forced-air drying oven for 1-3 hours, and then baking in an 100-120℃ oven for 2-4 hours to obtain the baked composite material.

7. An antibacterial silicon nitride fiber composite material prepared by any one of claims 1-6.

8. The application of the antibacterial silicon nitride fiber composite material according to claim 7 in the preparation of antiviral / antibacterial protective products and air purification materials.

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