Silicon nitride reinforced composite antibacterial material and preparation method and application thereof

Abstract

The application discloses a kind of silicon nitride reinforced composite antibacterial material and preparation method, application, belong to silicon nitride composite material technical field, including fiber base material composite pretreatment, modified alpha phase silicon nitride powder preparation, composite bonding solution preparation, composite slurry preparation, composite and post-processing.The application is realized by modified alpha phase silicon nitride powder and nano boron nitride cooperation ultraviolet shielding effect, reduce the damage of internal antibacterial component to ultraviolet light;With the reasonable proportion of polyvinyl alcohol, chitosan and poly-N-isopropyl acrylamide in composite bonding solution, strengthen the bonding strength and interface stability, inhibit the shedding and activity attenuation of antibacterial component under ultraviolet irradiation, combined with secondary padding and crosslinking post-processing process to improve material structure density, enhance the ability of material to resist ultraviolet aging.

Description

Technical Field

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

[0002] Against the backdrop of continuously escalating demands for public health security and daily protection, antimicrobial materials, as a class of functional materials capable of inhibiting or killing microorganisms and blocking the spread of pathogens, have been widely used in various fields such as medical protection, food contact, air purification, and household products. Silicon nitride, as a high-performance inorganic non-metallic material, possesses inherent advantages such as high temperature resistance, strong chemical stability, and excellent biocompatibility. Furthermore, it inherently possesses potential antimicrobial properties. Introducing it as a functional component into antimicrobial materials provides a highly promising research direction for the development of high-performance antimicrobial materials.

[0003] Although existing technologies have solved problems such as poor stability, potential toxicity, and weak binding of antibacterial components in traditional antibacterial materials, the activity of antibacterial components is easily affected by environmental factors and decays in strong ultraviolet radiation scenarios during long-term outdoor use, making it difficult for the materials to maintain a stable antibacterial effect during long-term use.

[0004] While existing technologies have improved upon the low bonding strength and poor chemical stability of traditional antibacterial materials, successfully resolving short-term toxicity concerns and the risk of detachment, they still have significant shortcomings when facing complex natural environments, especially the harsh conditions of long-term strong ultraviolet radiation. Under strong outdoor ultraviolet conditions, existing antibacterial materials are highly susceptible to photoaging, which not only manifests as material embrittlement but also directly leads to irreversible degradation of antibacterial function. High-energy ultraviolet radiation accelerates the physicochemical interactions between the antibacterial agent and the matrix interface, potentially causing the decomposition of antibacterial active groups and the dissolution of antibacterial ions. Over time, the effective antibacterial components on the material surface gradually deplete or lose activity, resulting in a significant decrease in its ability to inhibit and kill bacteria, fungi, and other microorganisms.

[0005] Based on this, the present invention designs a silicon nitride-reinforced composite antibacterial material, its preparation method, and its application to solve the above problems. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a method for preparing a silicon nitride-reinforced composite antibacterial material, comprising the following steps:

[0007] S1. Pretreatment of fiber-based composite material;

[0008] Polylactic acid-polycaprolactone blended fiber was selected as the substrate. It was first immersed in a composite aqueous solution of sodium hydroxide and potassium dihydrogen phosphate and stirred. After rinsing, it was immersed in a carboxymethyl chitosan aqueous solution. After standing, it was taken out and dried to obtain the pretreated fiber substrate.

[0009] S2. Preparation of modified α-phase silicon nitride powder;

[0010] Take α-phase silicon nitride powder, add it to a mixed solvent to prepare a suspension; add a composite silane coupling agent to the suspension and stir; add nano boron nitride and continue stirring, centrifuge, collect the lower solid powder, and dry to obtain modified α-phase silicon nitride powder;

[0011] S3. Preparation of composite adhesive solution;

[0012] Polyvinyl alcohol and chitosan were added to deionized water and stirred until completely dissolved to obtain a basic adhesive solution; a composite antibacterial agent was added, followed by poly-N-isopropylacrylamide, and the mixture was stirred to obtain a composite adhesive solution.

[0013] S4. Preparation of composite slurry;

[0014] Modified α-phase silicon nitride powder was mixed with a composite binder solution, a composite dispersant was added, the mixture was stirred, ultrasonically dispersed, and then filtered to obtain a composite slurry.

[0015] S5. Composite;

[0016] The pretreated fiber substrate is first impregnated and dried, and then impregnated and dried a second time to obtain a preliminary composite substrate;

[0017] S6. Post-processing;

[0018] The preliminary composite substrate was immersed in a dialdehyde xylose aqueous solution for crosslinking. After crosslinking was completed, it was rinsed, dried, and cooled to obtain a silicon nitride-reinforced composite antibacterial material.

[0019] Furthermore, S1 specifically involves selecting polylactic acid-polycaprolactone blended fibers with a mass ratio of 5-7:3-5 as the substrate. The fibers are first completely immersed in a composite aqueous solution of 0.2-0.6 wt% sodium hydroxide and 0.1-0.3 wt% potassium dihydrogen phosphate, stirred at 180-280 r / min for 15-35 min at 30-55℃, and rinsed with deionized water until neutral. Then, the fibers are immersed in a 0.5-1.2 wt% carboxymethyl chitosan aqueous solution, kept at a constant temperature of 28-38℃ for 20-40 min, and then dried in a forced-air drying oven at 65-90℃ for 3-7 h to obtain the pretreated fiber substrate.

[0020] Furthermore, S2 specifically involves: taking α-phase silicon nitride powder and adding it to a mixed solvent of deionized water and ethylene glycol at a volume ratio of 1:1.5-4 to prepare a suspension of 6-14 wt%; adding a composite silane coupling agent accounting for 0.8-2.5% of the mass of α-phase silicon nitride powder to the suspension, and stirring at 180-280 r / min for 40-70 min at 35-55℃; adding nano boron nitride accounting for 1.0-3.0% of the mass of α-phase silicon nitride powder, continuing to stir for 30-50 min, centrifuging at 3500-6500 r / min for 10-15 min, collecting the lower solid powder, and drying it in an oven at 85-115℃ for 5-9 h to obtain modified α-phase silicon nitride powder.

[0021] Furthermore, the composite silane coupling agent is obtained by compounding N-phenyl-3-aminopropyltrimethoxysilane, bis-(3-(triethoxysilane)propyl)-tetrasulfide and γ-methacryloyloxypropyltrimethoxysilane in a mass ratio of 4-6:2:1-3.

[0022] Furthermore, S3 specifically involves: taking polyvinyl alcohol and chitosan in a mass ratio of 3-4:1-2, adding them to deionized water, and stirring at 220-320 r / min at 75-95℃ until completely dissolved to obtain a 4-9 wt% basic adhesive solution; adding 3.0-5.0% of the total mass of the basic adhesive solution to the solution of a composite antibacterial agent, and then adding 0.3-0.8% of the total mass of the basic adhesive solution of poly-N-isopropylacrylamide, and stirring at 200-300 r / min at 40-60℃ for 40-70 min to obtain a composite adhesive solution.

[0023] Furthermore, the composite antibacterial agent is obtained by compounding nano zinc oxide, nano titanium dioxide and nano silver-doped montmorillonite in a mass ratio of 2-3:1-2:1, with the amount of nano silver doping being 0.3-0.8% of the mass of montmorillonite.

[0024] Furthermore, S4 specifically involves: mixing modified α-phase silicon nitride powder with the composite binder solution at a mass ratio of 3-6:3, adding a composite dispersant accounting for 0.2-0.7% of the total mass of the composite binder solution, wherein the composite dispersant is a mixture of lignin sulfonate and polyethylene glycol at a mass ratio of 2-4:1, stirring at 250-450 r / min for 1.5-3 h, then ultrasonically dispersing at 200-350 W for 25-45 min, repeating this stirring-ultrasonic process 4-6 times, and then filtering with a 150-250 mesh filter to obtain the composite slurry.

[0025] Furthermore, S5 specifically involves: first, immersing the pretreated fiber substrate in the composite slurry for the first impregnation using an impregnation and padding equipment at parameters of 0.15-0.35 MPa and 0.8-2.5 m / min, and then pre-drying it in a forced-air drying oven at 85-105℃ for 1.5-3.5 hours; then, secondly impregnating the pre-dried substrate in the composite slurry at parameters of 0.2-0.4 MPa and 0.6-2.2 m / min, and then drying it in an oven at 105-125℃ for 3-5 hours to obtain the preliminary composite substrate.

[0026] A silicon nitride-reinforced composite antibacterial material prepared using the aforementioned method.

[0027] The application of the aforementioned silicon nitride-reinforced composite antibacterial material in the preparation of antiviral / antibacterial protective products, air purification materials, and food contact antibacterial materials.

[0028] Compared with the prior art, the beneficial effects of this invention are as follows:

[0029] 1. The nano-boron nitride of this invention has an intrinsic wide bandgap characteristic of approximately 5.9 eV and strong absorption capacity for ultraviolet light; the α-phase silicon nitride modified with a composite silane coupling agent forms Si–O–C bonds on its surface (infrared spectrum at 1240 cm⁻¹). -1 (As confirmed by characteristic peaks), this group can form hydrogen bond coupling with the B–N facet of h-BN, forming a stable structure and constructing an ultraviolet barrier, significantly reducing the penetration and damage of ultraviolet light to the antibacterial components inside the material; in the composite bonding solution, the hydroxyl groups of polyvinyl alcohol, the amino groups of chitosan, and the amide bonds of poly-N-isopropylacrylamide interact to form a stable interfacial bonding state, greatly improving the bonding strength and interfacial stability, effectively inhibiting the shedding and activity decay of antibacterial components under ultraviolet irradiation, and the combination of secondary impregnation and cross-linking post-treatment processes improves the material's structural density and enhances the material's ability to resist ultraviolet aging.

[0030] 2. This invention uses polylactic acid-polycaprolactone blended fibers as the substrate, which undergo surface activation treatment with a composite aqueous solution of sodium hydroxide and potassium dihydrogen phosphate. Then, the hydroxyl and amino groups of carboxymethyl chitosan form intermolecular forces with the substrate, significantly improving the surface affinity of the substrate. During the preparation of the composite slurry, a composite dispersant composed of lignin sulfonate and polyethylene glycol, combined with a stirring-ultrasonic circulation process, effectively breaks up particle agglomeration, ensuring uniform dispersion of modified α-phase silicon nitride powder and antibacterial components in the slurry. Through the bonding effect of COC bonds and Si-OC bonds in the bonding system, a stable bond is achieved between the reinforcing phase, the antibacterial phase, and the substrate. This not only maintains stable initial tensile strength and elongation at break but also preserves excellent mechanical properties after long-term UV aging, avoiding performance degradation caused by a loose internal structure.

[0031] 3. This invention leverages the synergistic effect of nano-zinc oxide, nano-titanium dioxide, and nano-silver-doped montmorillonite in the composite antibacterial agent to exert a multi-faceted antibacterial mechanism, significantly enhancing the inhibitory effect against common bacteria and fungi. Simultaneously, the antibacterial components achieve uniform dispersion and firm adhesion through a bonding system, forming a stable structure together with the substrate and reinforcing phase. Its surface-active groups can interact with viral envelope proteins, giving the material excellent inhibitory activity against influenza A virus H1N1, SARS-CoV-2, etc., broadening the application range of the material in antiviral / antibacterial protective products, air purification materials, and food contact antibacterial materials. Attached Figure Description

[0032] 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.

[0033] Figure 1 This is an electron microscope image of the modified α-phase silicon nitride powder prepared in Example 1 of the present invention;

[0034] Figure 2 The infrared spectrum of the silicon nitride-reinforced composite antibacterial material prepared in Example 4 of this invention is shown below.

[0035] Figure 3 The image shows the XRD pattern of the silicon nitride-reinforced composite antibacterial material prepared in Example 4 of this invention.

[0036] Figure 4 The thermogravimetric analysis diagram is shown for the silicon nitride-reinforced composite antibacterial material prepared in Example 4 of this invention. Detailed Implementation

[0037] 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.

[0038] Example 1: This example provides a method for preparing a silicon nitride-reinforced composite antibacterial material, including the following steps:

[0039] S1. Pretreatment of fiber-based composite material;

[0040] Polylactic acid-polycaprolactone blended fibers (mass ratio 7:5) were selected as the substrate. The fibers were first completely immersed in a composite aqueous solution of 0.6 wt% sodium hydroxide and 0.3 wt% potassium dihydrogen phosphate, stirred at 280 r / min for 35 min at 55 °C, and rinsed with deionized water until neutral (pH=7±0.5). Then, the fibers were immersed in a 1.2 wt% carboxymethyl chitosan aqueous solution, kept at 38 °C for 40 min, and then dried in a 90 °C forced-air drying oven for 7 h to obtain the pretreated fiber substrate.

[0041] S2. Preparation of modified α-phase silicon nitride powder;

[0042] Take α-phase silicon nitride powder and add it to a mixed solvent of deionized water and ethylene glycol with a volume ratio of 1:4 to prepare a 14wt% suspension. Add 2.5% of a composite silane coupling agent (N-phenyl-3-aminopropyltrimethoxysilane, bis-(3-(triethoxysilane)propyl)-tetrasulfide and γ-methacryloyloxypropyltrimethoxysilane in a mass ratio of 6:2:3) to the suspension and stir at 280 r / min for 70 min at 55 °C. Add 3.0% of nano boron nitride (particle size 500 nm) with a mass ratio of α-phase silicon nitride powder and continue stirring for 50 min. Centrifuge at 6500 r / min for 15 min, collect the lower solid powder, and dry it in an oven at 115 °C for 9 h to obtain modified α-phase silicon nitride powder.

[0043] Figure 1 The image shows a scanning electron microscope (SEM) image of the modified α-phase silicon nitride powder (magnification 10,000x, scale bar 2μm). The powder is spherical or irregularly shaped, with particle diameters ranging from several hundred nanometers to about 1μm. It exhibits good size uniformity, with no obvious oversized agglomerates and excellent dispersion, indicating that the surface modification effect of the composite silane coupling agent effectively reduces the tendency of adsorption and agglomeration between particles. In addition, due to the adhesion of nano-boron nitride to the surface of the α-phase silicon nitride powder, the particle surface has a slightly raised, rough texture.

[0044] S3. Preparation of composite adhesive solution;

[0045] Polyvinyl alcohol (PVA-203) and chitosan were mixed in a mass ratio of 4:2 and added to deionized water. The mixture was stirred at 320 r / min at 95°C until completely dissolved to obtain a 9 wt% basic adhesive solution. 5.0% of the total mass of the basic adhesive solution was added to this solution of a composite antibacterial agent (a mixture of nano-zinc oxide, nano-titanium dioxide, and nano-silver-doped montmorillonite in a mass ratio of 3:2:1, with the nano-silver doping amount being 0.8% of the montmorillonite mass). Then, 0.8% of the total mass of the basic adhesive solution was added to the mixture. The mixture was stirred at 300 r / min at 60°C for 70 min to obtain a composite adhesive solution.

[0046] S4. Preparation of composite slurry;

[0047] Modified α-phase silicon nitride powder and composite binder solution were mixed at a mass ratio of 6:3. A composite dispersant (a mixture of lignin sulfonate and polyethylene glycol 400 at a mass ratio of 4:1) was added, accounting for 0.7% of the total mass of the composite binder solution. The mixture was first stirred at 450 r / min for 3 h, and then ultrasonically dispersed at 350 W for 45 min. This stirring-ultrasonic process was repeated 6 times. The mixture was then filtered through a 250 mesh screen to obtain a uniform and stable composite slurry.

[0048] S5. Composite;

[0049] The pretreated fiber substrate was first impregnated with the composite slurry at a pressure of 0.35 MPa and a speed of 2.5 m / min using an impregnation and padding equipment. It was then pre-dried in a 105℃ forced-air drying oven for 3.5 h. The pre-dried substrate was then impregnated with the composite slurry a second time at a pressure of 0.4 MPa and a speed of 2.2 m / min and dried in a 125℃ oven for 5 h to obtain the preliminary composite substrate.

[0050] S6. Post-processing;

[0051] The preliminary composite substrate was immersed in a 7wt% xylose dialdehyde aqueous solution and crosslinked at 45℃ for 25 min. After crosslinking, it was rinsed 5 times with deionized water and dried in an 85℃ forced-air drying oven for 6 h. After natural cooling to room temperature, silicon nitride reinforced composite antibacterial material was obtained.

[0052] Example 2: This example provides a method for preparing a silicon nitride-reinforced composite antibacterial material, including the following steps:

[0053] S1. Pretreatment of fiber-based composite material;

[0054] Polylactic acid-polycaprolactone blended fibers (mass ratio 5:3) were selected as the substrate. The fibers were first completely immersed in a composite aqueous solution of 0.2 wt% sodium hydroxide and 0.1 wt% potassium dihydrogen phosphate, stirred at 180 r / min for 15 min at 30 °C, and rinsed with deionized water until neutral (pH=7±0.5). Then, the fibers were immersed in a 0.5 wt% carboxymethyl chitosan aqueous solution, kept at a constant temperature of 28 °C for 20 min, and then dried in a 65 °C forced-air drying oven for 3 h to obtain the pretreated fiber substrate.

[0055] S2. Preparation of modified α-phase silicon nitride powder;

[0056] Take α-phase silicon nitride powder and add it to a mixed solvent of deionized water and ethylene glycol with a volume ratio of 1:1.5 to prepare a 6wt% suspension. Add 0.8% of a composite silane coupling agent (N-phenyl-3-aminopropyltrimethoxysilane, bis-(3-(triethoxysilane)propyl)-tetrasulfide and γ-methacryloyloxypropyltrimethoxysilane in a mass ratio of 4:2:1) to the suspension and stir at 180 r / min for 40 min at 35 °C. Add 1.0% of nano boron nitride with a mass ratio of 1.0% of the α-phase silicon nitride powder and continue stirring for 30 min. Centrifuge at 3500 r / min for 10 min, collect the lower solid powder, and dry it in an oven at 85 °C for 5 h to obtain modified α-phase silicon nitride powder.

[0057] S3. Preparation of composite adhesive solution;

[0058] Polyvinyl alcohol (PVA-203) and chitosan were mixed in a mass ratio of 3:1 and added to deionized water. The mixture was stirred at 220 r / min at 75°C until completely dissolved to obtain a 4 wt% basic adhesive solution. 3.0% of the total mass of the basic adhesive solution was added to this solution of a composite antibacterial agent (a mixture of nano-zinc oxide, nano-titanium dioxide, and nano-silver-doped montmorillonite in a mass ratio of 2:1:1, with the nano-silver doping amount being 0.3% of the montmorillonite mass). Then, 0.3% of the total mass of the basic adhesive solution of poly-N-isopropylacrylamide was added. The mixture was stirred at 200 r / min at 40°C for 40 min to obtain a composite adhesive solution.

[0059] S4. Preparation of composite slurry;

[0060] Modified α-phase silicon nitride powder and composite binder solution were mixed at a mass ratio of 3:3. A composite dispersant (a mixture of lignin sulfonate and polyethylene glycol 200 at a mass ratio of 2:1) was added, accounting for 0.2% of the total mass of the composite binder solution. The mixture was first stirred at 250 r / min for 1.5 h, and then ultrasonically dispersed at 200 W for 25 min. This stirring-ultrasonic process was repeated 4 times. The mixture was then filtered through a 150-mesh filter to obtain a uniform and stable composite slurry.

[0061] S5. Composite;

[0062] The pretreated fiber substrate is first impregnated with the composite slurry at a pressure of 0.15 MPa and a speed of 0.8 m / min using an impregnation and padding equipment. It is then pre-dried in an 85°C forced-air drying oven for 1.5 h. The pre-dried substrate is then impregnated with the composite slurry a second time at a pressure of 0.2 MPa and a speed of 0.6 m / min and then dried in an oven at 105°C for 3 h to obtain the preliminary composite substrate.

[0063] S6. Post-processing;

[0064] The preliminary composite substrate was immersed in a 3wt% xylose dialdehyde aqueous solution and crosslinked at 30℃ for 15 min. After crosslinking, it was rinsed three times with deionized water, placed in a 70℃ forced-air drying oven for 3 h, and naturally cooled to room temperature to obtain a silicon nitride reinforced composite antibacterial material.

[0065] Example 3: This example provides a method for preparing a silicon nitride-reinforced composite antibacterial material, including the following steps:

[0066] S1. Pretreatment of fiber-based composite material;

[0067] Polylactic acid-polycaprolactone blended fibers (mass ratio 5.8:4.2) were selected as the substrate. They were first completely immersed in a composite aqueous solution of 0.5wt% sodium hydroxide and 0.2wt% potassium dihydrogen phosphate, stirred at 200r / min for 30min at 40℃, and rinsed with deionized water until neutral (pH=7±0.5). Then, they were immersed in a 0.8wt% carboxymethyl chitosan aqueous solution, kept at a constant temperature of 30℃ for 35min, and then dried in a 70℃ forced-air drying oven for 4h to obtain the pretreated fiber substrate.

[0068] S2. Preparation of modified α-phase silicon nitride powder;

[0069] Take α-phase silicon nitride powder and add it to a mixed solvent of deionized water and ethylene glycol with a volume ratio of 1:3 to prepare an 8wt% suspension. Add 1.2% of a composite silane coupling agent (N-phenyl-3-aminopropyltrimethoxysilane, bis-(3-(triethoxysilane)propyl)-tetrasulfide and γ-methacryloyloxypropyltrimethoxysilane in a mass ratio of 5.2:2:2.2) to the suspension and stir at 240 r / min for 60 min at 40 °C. Add 1.7% of nano boron nitride with a mass ratio of 1.7% of the α-phase silicon nitride powder and continue stirring for 45 min. Centrifuge at 5000 r / min for 15 min, collect the lower solid powder, and dry it in an oven at 100 °C for 6 h to obtain modified α-phase silicon nitride powder.

[0070] S3. Preparation of composite adhesive solution;

[0071] Polyvinyl alcohol (PVA-203) and chitosan were mixed in a mass ratio of 3.2:1.5 and added to deionized water. The mixture was stirred at 280 r / min at 80°C until completely dissolved to obtain a 5 wt% basic adhesive solution. Then, 5.0% of the total mass of the basic adhesive solution was added to the solution of a composite antibacterial agent (a mixture of nano-zinc oxide, nano-titanium dioxide, and nano-silver-doped montmorillonite in a mass ratio of 2.6:1.3:1, with the nano-silver doping amount being 0.5% of the montmorillonite mass). Finally, 0.7% of the total mass of the basic adhesive solution was added to the solution of poly(N-isopropylacrylamide). The mixture was stirred at 240 r / min at 48°C for 50 min to obtain a composite adhesive solution.

[0072] S4. Preparation of composite slurry;

[0073] Modified α-phase silicon nitride powder and composite binder solution were mixed at a mass ratio of 5:3. A composite dispersant (a mixture of lignin sulfonate and polyethylene glycol 400 at a mass ratio of 2:1) was added, accounting for 0.7% of the total mass of the composite binder solution. The mixture was first stirred at 300 r / min for 2 h, and then ultrasonically dispersed at 300 W for 40 min. This stirring-ultrasonic process was repeated 5 times. The mixture was then filtered through a 200-mesh filter to obtain a uniform and stable composite slurry.

[0074] S5. Composite;

[0075] The pretreated fiber substrate is first impregnated with the composite slurry at a pressure of 0.20 MPa and a speed of 1.5 m / min using an impregnation and padding equipment. It is then pre-dried in a 90℃ forced-air drying oven for 1.5 h. The pre-dried substrate is then impregnated with the composite slurry a second time at a pressure of 0.4 MPa and a speed of 2.2 m / min and then dried in a 115℃ oven for 5 h to obtain the preliminary composite substrate.

[0076] S6. Post-processing;

[0077] The preliminary composite substrate was immersed in a 5 wt% xylose dialdehyde aqueous solution and crosslinked at 40°C for 20 min. After crosslinking, it was rinsed 5 times with deionized water, placed in an 80°C forced-air drying oven for 5 h, and naturally cooled to room temperature to obtain a silicon nitride reinforced composite antibacterial material.

[0078] Example 4: This example provides a method for preparing a silicon nitride-reinforced composite antibacterial material, including the following steps:

[0079] S1. Pretreatment of fiber-based composite material;

[0080] Polylactic acid-polycaprolactone blended fibers (mass ratio 5:4) were selected as the substrate. The fibers were first completely immersed in a composite aqueous solution of 0.3wt% sodium hydroxide and 0.2wt% potassium dihydrogen phosphate, stirred at 220r / min for 20min at 47℃, and rinsed with deionized water until neutral (pH=7±0.5). Then, the fibers were immersed in a 0.8wt% carboxymethyl chitosan aqueous solution, kept at 32℃ for 25min, and then dried in an 88℃ forced-air drying oven for 6h to obtain the pretreated fiber substrate.

[0081] S2. Preparation of modified α-phase silicon nitride powder;

[0082] Take α-phase silicon nitride powder and add it to a mixed solvent of deionized water and ethylene glycol with a volume ratio of 1:2.6 to prepare an 8wt% suspension. Add 2.1% of a composite silane coupling agent (a mixture of N-phenyl-3-aminopropyltrimethoxysilane, bis-(3-(triethoxysilane)propyl)-tetrasulfide and γ-methacryloyloxypropyltrimethoxysilane in a mass ratio of 6:2:1.5) to the suspension and stir at 190 r / min for 50 min at 50 °C. Add 1.6% of nano boron nitride with a mass ratio of 1.6% of the α-phase silicon nitride powder and continue stirring for 40 min. Centrifuge at 5000 r / min for 15 min, collect the lower solid powder, and dry it in a 90 °C oven for 8 h to obtain modified α-phase silicon nitride powder.

[0083] S3. Preparation of composite adhesive solution;

[0084] Polyvinyl alcohol (PVA-203) and chitosan were mixed in a mass ratio of 3:2 and added to deionized water. The mixture was stirred at 300 r / min at 90°C until completely dissolved to obtain a 5 wt% basic adhesive solution. 4.6% of the total mass of the basic adhesive solution was added to this solution of a composite antibacterial agent (a mixture of nano-zinc oxide, nano-titanium dioxide, and nano-silver-doped montmorillonite in a mass ratio of 2.7:1:1, with the nano-silver doping amount being 0.5% of the montmorillonite mass). Then, 0.6% of the total mass of the basic adhesive solution was added to the mixture. The mixture was stirred at 280 r / min at 54°C for 60 min to obtain a composite adhesive solution.

[0085] S4. Preparation of composite slurry;

[0086] Modified α-phase silicon nitride powder and composite binder solution were mixed at a mass ratio of 5:3. A composite dispersant (a mixture of lignin sulfonate and polyethylene glycol 400 at a mass ratio of 2:1) was added, accounting for 0.4% of the total mass of the composite binder solution. The mixture was first stirred at 300 r / min for 2 h, and then ultrasonically dispersed at 300 W for 40 min. This stirring-ultrasonic process was repeated 6 times. The mixture was then filtered through a 200-mesh filter to obtain a uniform and stable composite slurry.

[0087] S5. Composite;

[0088] The pretreated fiber substrate was first impregnated with the composite slurry at a pressure of 0.35 MPa and a speed of 2.2 m / min using an impregnation and padding equipment. It was then pre-dried in a 95°C forced-air drying oven for 2 hours. The pre-dried substrate was then impregnated with the composite slurry a second time at a pressure of 0.3 MPa and a speed of 1.8 m / min and dried in a 120°C oven for 3 hours to obtain the preliminary composite substrate.

[0089] S6. Post-processing;

[0090] The preliminary composite substrate was immersed in a 5 wt% xylose dialdehyde aqueous solution and crosslinked at 40°C for 20 min. After crosslinking, it was rinsed 5 times with deionized water, placed in a 78°C forced-air drying oven for 5 h, and naturally cooled to room temperature to obtain a silicon nitride reinforced composite antibacterial material.

[0091] Comparative Example 1: The difference between this comparative example and Example 4 is that the substrate used is pure polylactic acid fiber.

[0092] Comparative Example 2: The difference between this comparative example and Example 4 is that no nano-boron nitride was added in S2.

[0093] Comparative Example 3: The difference between this comparative example and Example 4 is that the mass ratio of nano zinc oxide, nano titanium dioxide and nano silver-doped montmorillonite in the composite antibacterial agent is 1:3:4.

[0094] Comparative Example 4: The difference between this comparative example and Example 4 is that in S5, the composite slurry was immersed in only once with parameters of 0.35 MPa and 2.2 m / min, and then dried in a 95°C forced-air drying oven for 5 hours.

[0095] Characterization example: The silicon nitride reinforced composite antibacterial material prepared in Example 4 was subjected to infrared, XRD and thermogravimetric analysis.

[0096] (1) Infrared characterization experiment;

[0097] Infrared spectrum as shown Figure 2 As shown, α-phase silicon nitride at 900-950 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 480-510 cm⁻¹ range. -1 The appearance of a weak absorption peak corresponds to the bending vibration of the Si-N bond;

[0098] 3300-3400cm -1 The presence of broad and strong absorption peaks nearby corresponds to the stretching vibrations of hydroxyl (-OH) and amino (-NH-) groups in polyvinyl alcohol, chitosan, and carboxymethyl chitosan.

[0099] 2850-2950cm -1 The region shows a medium-intensity absorption peak, which is a characteristic peak of the stretching vibration of saturated CH bonds in polylactic acid-polycaprolactone blended fibers and poly-N-isopropylacrylamide.

[0100] 1720-1750cm -1 There is a distinct absorption peak at this point, corresponding to the stretching vibration of the ester group (-COO-) in polylactic acid, polycaprolactone, and carboxymethyl chitosan;

[0101] 1630-1650cm -1The presence of absorption peaks nearby is attributed to the bending vibrations of the amide bonds (-CONH-) in chitosan and the bending vibrations of water adsorbed on the surface of the composite antibacterial agent.

[0102] 1080-1120cm -1 Strong absorption peaks appear in the range, corresponding to the stretching vibrations of silicon nitride (Si-N), nano boron nitride (BN), and COC in polyvinyl alcohol.

[0103] 1240cm -1 The presence of absorption peaks on the left and right corresponds to the stretching vibration of the Si-OC bond in the composite silane coupling agent, confirming the surface modification effect of the coupling agent on silicon nitride powder.

[0104] (2) XRD characterization experiment;

[0105] XRD diagram as follows Figure 3 As shown, the core α-phase silicon nitride, as the main reinforcing and 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=16.5°, crystal plane (100); 2θ=21.0°, crystal plane (101); 2θ=25.1°, crystal plane (110); 2θ=27.6°, crystal plane (102); 2θ=33.4°, crystal plane (111); 2θ=36.8°, crystal plane (201); 2θ=43.5°, crystal plane (210); 2θ=52.3°, crystal plane (211).

[0106] The core reinforcing phase, nano-boron nitride, serves as a key component for UV shielding and structural reinforcement in composite materials. It exhibits high diffraction peak intensity and regular peak shape. The characteristic diffraction angles (2θ) and corresponding crystal planes are as follows: 2θ = 26.7°, crystal plane (002); 2θ = 41.8°, crystal plane (100); 2θ = 50.2°, crystal plane (102); 2θ = 55.2°, crystal plane (004); 2θ = 76.0°, crystal plane (110).

[0107] The antibacterial active component, nano-zinc oxide, exhibits moderate intensity and sharp peak shape in its diffraction peaks. The characteristic diffraction angles (2θ) and corresponding crystal planes are as follows: 2θ = 31.7°, crystal plane (100); 2θ = 34.4°, crystal plane (002); 2θ = 36.2°, crystal plane (101); 2θ = 47.5°, crystal plane (102); 2θ = 56.6°, crystal plane (110); 2θ = 62.8°, crystal plane (103); 2θ = 67.9°, crystal plane (200); 2θ = 69.1°, crystal plane (112).

[0108] The antibacterial active component, nano-titanium dioxide, exhibits moderate diffraction peak intensity and regular peak shape. The characteristic diffraction angles (2θ) and corresponding crystal planes are as follows: 2θ=25.3°, crystal plane (101); 2θ=37.8°, crystal plane (004); 2θ=38.2°, crystal plane (112); 2θ=48.0°, crystal plane (200); 2θ=53.9°, crystal plane (105); 2θ=55.1°, crystal plane (211); 2θ=62.7°, crystal plane (204); 2θ=68.8°, crystal plane (116).

[0109] (3) Thermogravimetric analysis experiment;

[0110] Thermogravimetric analysis results are as follows Figure 4 As shown, below 200℃, the composite material exhibits a slight mass loss (2.15%), corresponding to the evaporation of physically adsorbed water on the surface and solvents such as ethylene glycol and deionized water remaining from the preparation process; a slow mass loss (6.32%) occurs in the 200-350℃ range, mainly due to the thermal decomposition of poly(N-isopropylacrylamide) oligomers, small side-chain molecules of carboxymethyl chitosan, and low molecular weight fragments of polyvinyl alcohol in the bonding system; a strong mass loss peak (41.18%) appears in the 350-480℃ range, corresponding to... Thermal decomposition of the polylactic acid-polycaprolactone blend matrix backbone, chitosan backbone, and polyvinyl alcohol backbone was accompanied by the decomposition of organic modified groups on the surface of montmorillonite. A small amount of mass loss (13.85%) occurred in the 480-600℃ range, which was due to the complete decomposition of the dialdehyde xylose crosslinking fragments and the organic part of the composite silane coupling agent after crosslinking. After 650℃, the residual mass ratio stabilized at about 36%, mainly due to the residue of stable inorganic components such as α-phase silicon nitride, nano boron nitride, nano zinc oxide, and nano titanium dioxide.

[0111] Experimental Example 1: The initial tensile strength and elongation at break of the silicon nitride reinforced composite antibacterial material prepared according to GB / T 3923.1-2013 were tested.

[0112] Experimental Example 2: The average antibacterial rate (%) of the silicon nitride reinforced composite antibacterial 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).

[0113] Experimental Example 3: The silicon nitride reinforced composite antibacterial material prepared according to this invention was subjected to a 1000-hour accelerated ultraviolet aging test (wavelength 340 nm, irradiance 0.68 W / m²) in accordance with GB / T 16422.3-2022. 2 The breaking strength and elongation at break after aging were tested according to the method of Experimental Example 1; the average antibacterial rate (%) after aging was tested according to the method of Experimental Example 2.

[0114] The results are shown in Table 1:

[0115] Table 1. Detection results of Examples 1-4 and Comparative Examples 1-4

[0116]

[0117] As shown in the table above, the initial tensile strength and elongation at break of the materials in each embodiment remained stable. This invention uses polylactic acid-polycaprolactone blended fiber as the substrate, and through immersion treatment with a composite aqueous solution of sodium hydroxide and potassium dihydrogen phosphate, modification treatment with a carboxymethyl chitosan aqueous solution, and composite treatment with modified α-phase silicon nitride powder and composite adhesive solution, the reinforcing phase, antibacterial phase and adhesive system are firmly bonded to the substrate, thereby ensuring the consistency and stability of the initial mechanical properties and antibacterial properties of the material.

[0118] After 1000 hours of accelerated UV aging test, the mechanical properties and antibacterial properties of the materials in each embodiment did not show significant attenuation and remained at a level similar to the initial state, indicating that the preparation scheme of the present invention has a significant effect on improving the weather resistance of the materials.

[0119] Comparative Example 1, because it did not use polylactic acid-polycaprolactone blended fibers, but only pure polylactic acid fibers as the base material, resulted in a significant decline in mechanical properties after aging.

[0120] Comparative Example 4 did not use the secondary impregnation process specified in this invention, but only completed the composite process through a single impregnation. This resulted in insufficient bonding between the substrate and the composite slurry, insufficient material density, and a significant reduction in fracture strength after aging.

[0121] The composite of modified α-phase silicon nitride powder and nano-boron nitride effectively achieves UV shielding and protection, reducing the damage of UV light to the internal antibacterial components. The addition of polyvinyl alcohol, chitosan, and poly-N-isopropylacrylamide to the composite bonding solution optimizes the bonding strength and interfacial stability, inhibiting the shedding and activity decay of the antibacterial components under UV irradiation. The secondary impregnation and cross-linking post-treatment process further improves the density and integrity of the material structure, enhancing the material's ability to resist UV aging.

[0122] (4) Antiviral activity detection;

[0123] The antiviral activity of the silicon nitride-reinforced composite antibacterial material prepared in this invention was tested according to ISO 18184:2019, "Determination of antiviral activity of textiles".

[0124] 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 (polylactic acid-polycaprolactone blend fiber) into the same size and sterilizing it in the same way.

[0125] Virus strain: (1) Influenza A virus H1N1 strain; host cell: MDCK cells (canine kidney epithelial cells), which were cultured in DMEM medium containing 10% fetal bovine serum to the logarithmic growth phase after resuscitation;

[0126] (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;

[0127] 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.

[0128] 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.

[0129] 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;

[0130] 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);

[0131] Calculate the antiviral activity value and antiviral activity (%).

[0132]

[0133]

[0134] The results are shown in Table 2:

[0135] Table 2. Antiviral activity test results of Examples 1-4 and Comparative Examples 1-4

[0136]

[0137] As shown in the table above, the silicon nitride-reinforced composite antibacterial material prepared in the embodiments of the present invention has an antiviral activity of over 99.6% against both influenza A virus H1N1 and COVID-19; the antiviral activity of each comparative example is slightly reduced.

[0138] 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 a silicon nitride-reinforced composite antibacterial material, characterized in that, Includes the following steps: S1. Pretreatment of fiber-based composite material; Polylactic acid-polycaprolactone blended fiber was selected as the substrate. It was first immersed in a composite aqueous solution of sodium hydroxide and potassium dihydrogen phosphate and stirred. After rinsing, it was immersed in a carboxymethyl chitosan aqueous solution. After standing, it was taken out and dried to obtain the pretreated fiber substrate. S2. Preparation of modified α-phase silicon nitride powder; Take α-phase silicon nitride powder, add it to a mixed solvent, and prepare a suspension; A composite silane coupling agent was added to the suspension and stirred; nano-boron nitride was added and stirring continued, centrifuged, the lower solid powder was collected, and dried to obtain modified α-phase silicon nitride powder; the composite silane coupling agent was obtained by compounding N-phenyl-3-aminopropyltrimethoxysilane, bis-(3-(triethoxysilane)propyl)-tetrasulfide and γ-methacryloyloxypropyltrimethoxysilane in a mass ratio of 4-6:2:1-3; S3. Preparation of composite adhesive solution; Polyvinyl alcohol and chitosan were added to deionized water and stirred until completely dissolved to obtain a basic adhesive solution. A composite antibacterial agent was added, followed by poly(N-isopropylacrylamide), and the mixture was stirred to obtain a composite adhesive solution. The composite antibacterial agent was prepared by compounding nano-zinc oxide, nano-titanium dioxide, and nano-silver-doped montmorillonite in a mass ratio of 2-3:1-2:1, with the amount of nano-silver doping being 0.3-0.8% of the mass of montmorillonite. S4. Preparation of composite slurry; Modified α-phase silicon nitride powder was mixed with a composite binder solution, a composite dispersant was added, the mixture was stirred, ultrasonically dispersed, and then filtered to obtain a composite slurry; the composite dispersant was a mixture of lignin sulfonate and polyethylene glycol in a mass ratio of 2-4:

1. S5. Composite; The pretreated fiber substrate is immersed in the composite slurry for one impregnation and then dried, and then impregnated in the composite slurry for a second time and dried to obtain the preliminary composite substrate. S6. Post-processing; The preliminary composite substrate was immersed in a dialdehyde xylose aqueous solution for crosslinking. After crosslinking was completed, it was rinsed, dried, and cooled to obtain a silicon nitride-reinforced composite antibacterial material.

2. The method for preparing the silicon nitride-reinforced composite antibacterial material according to claim 1, characterized in that, S1 specifically involves selecting polylactic acid-polycaprolactone blended fibers with a mass ratio of 5-7:3-5 as the substrate. The fibers are first completely immersed in a composite aqueous solution of 0.2-0.6 wt% sodium hydroxide and 0.1-0.3 wt% potassium dihydrogen phosphate, stirred at 180-280 r / min for 15-35 min at 30-55℃, and then rinsed with deionized water until neutral. Next, the fibers are immersed in a 0.5-1.2 wt% carboxymethyl chitosan aqueous solution, kept at a constant temperature of 28-38℃ for 20-40 min, and then dried in a 65-90℃ forced-air drying oven for 3-7 h to obtain the pretreated fiber substrate.

3. The method for preparing the silicon nitride-reinforced composite antibacterial 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 ethylene glycol with a volume ratio of 1:1.5-4 to prepare a suspension of 6-14 wt%; add 0.8-2.5% of a composite silane coupling agent by mass of α-phase silicon nitride powder to the suspension, and stir at 180-280 r / min for 40-70 min at 35-55℃; add 1.0-3.0% of nano boron nitride by mass of α-phase silicon nitride powder, continue stirring for 30-50 min, centrifuge at 3500-6500 r / min for 10-15 min, collect the lower solid powder, and dry it in an oven at 85-115℃ for 5-9 h to obtain modified α-phase silicon nitride powder.

4. The method for preparing the silicon nitride-reinforced composite antibacterial material according to claim 1, characterized in that, S3 is specifically as follows: Polyvinyl alcohol and chitosan are taken in a mass ratio of 3-4:1-2, added to deionized water, and stirred at 220-320 r / min at 75-95℃ until completely dissolved to obtain a 4-9 wt% basic adhesive solution; 3.0-5.0% of the total mass of the basic adhesive solution is added to the solution as a composite antibacterial agent, and then 0.3-0.8% of the total mass of the basic adhesive solution is added as poly-N-isopropylacrylamide, and stirred at 200-300 r / min at 40-60℃ for 40-70 min to obtain a composite adhesive solution.

5. The method for preparing the silicon nitride-reinforced composite antibacterial material according to claim 1, characterized in that, S4 specifically involves mixing modified α-phase silicon nitride powder with the composite binder solution at a mass ratio of 3-6:3, adding a composite dispersant accounting for 0.2-0.7% of the total mass of the composite binder solution, stirring at 250-450 r / min for 1.5-3 h, then ultrasonically dispersing at 200-350 W for 25-45 min, repeating this stirring-ultrasonic process 4-6 times, and finally filtering with a 150-250 mesh filter to obtain the composite slurry.

6. The method for preparing the silicon nitride-reinforced composite antibacterial material according to claim 1, characterized in that, S5 specifically involves: first, immersing the pretreated fiber substrate in the composite slurry for the first impregnation using an impregnation and padding equipment at parameters of 0.15-0.35 MPa and 0.8-2.5 m / min, and then pre-drying it in a forced-air drying oven at 85-105℃ for 1.5-3.5 hours; then, secondly impregnating the pre-dried substrate in the composite slurry at parameters of 0.2-0.4 MPa and 0.6-2.2 m / min, and then drying it in an oven at 105-125℃ for 3-5 hours to obtain the preliminary composite substrate.

7. A silicon nitride reinforced composite antibacterial material prepared by the preparation method of silicon nitride reinforced composite antibacterial material according to any one of claims 1-6.

8. The application of the silicon nitride reinforced composite antibacterial material as described in claim 7 in the preparation of antiviral / antibacterial protective products and air purification materials.

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