Preparation method for efficiently preparing nylon 6 micro-nano fiber antibacterial air filtering membrane material

Abstract

The invention discloses a method for efficiently preparing a nylon 6 micro-nano fiber antibacterial air filtering membrane material, which comprises the following steps: etching porous ceramic microspheres, mixing with a non-polar material solution, coating, drying, and injecting charges to obtain electret microspheres; mixing an antibacterial substance solution with the electret microspheres in the step S1, and drying to obtain antibacterial-electret microspheres; meanwhile, spinning a bottom layer of the filtering membrane by using a crude fiber spinning solution and a fine fiber spinning solution through blowing spinning; adding a crude fiber spinning solution and antibacterial-electret microspheres into a cross-linking agent for mixing and spraying to form a middle layer with the surface of the bottom layer; repeating bottom layer operation and spraying again to form a top layer with the middle layer to obtain the filtering membrane with a multi-layer structure; carrying out hot press molding on the filtering membrane with the multi-layer structure; the dynamic interaction between a flow field and particles is enhanced, so that fine particles are more easily adsorbed or intercepted by the fiber surface, and efficient filtration is realized.

Description

Technical Field

[0001] This invention relates to the field of air filter membranes, and more particularly to a method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material. Background Technology

[0002] Traditional nylon 6 air filter materials are typically manufactured using melt-blowing or electrospinning processes, relying on the dense stacking of fibers or electrostatic adsorption to intercept particulate matter. However, these materials generally suffer from two major technical bottlenecks: First, the smooth fiber surface and uniform pore distribution mean that when airflow passes through in a laminar state, micron-sized particles (such as PM2.5) are easily carried away by inertia and escape along the streamline, resulting in insufficient filtration efficiency. Second, the material lacks antibacterial properties, and bacteria can easily colonize the fiber surface and breed secondary pollution during long-term use, threatening air hygiene and safety.

[0003] In recent years, researchers have attempted to improve the antibacterial properties of nylon 6 filter membranes through chemical modification or the addition of inorganic antibacterial agents (such as nano-silver and titanium dioxide). However, these methods often lead to a decrease in fiber mechanical properties or a significant increase in filtration resistance. Meanwhile, efforts to improve filtration efficiency have largely focused on reducing fiber diameter (such as preparing nanofibers) or introducing electret charges. However, the low mechanical strength of nanofibers and the susceptibility of electret charges to decay due to humidity limitations restrict their practical applications. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and provides a method for preparing nylon 6 micro / nano fiber antibacterial air filter membrane material with high efficiency.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material, comprising the following steps:

[0006] S1: Etch porous ceramic microspheres, mix and coat them with a non-polar material solution, dry them, and inject charges to obtain electret microspheres;

[0007] S2: Mix the antibacterial substance solution with the electret microspheres of S1, and dry them to obtain antibacterial electret microspheres;

[0008] S3: A coarse fiber spinning solution is prepared by mixing a coarse fiber material with a diameter >10μm that can cross-link with hydrogen bonds with an antibacterial material, and a fine fiber spinning solution is prepared by mixing an ultrafine fiber as a skeleton with a material that enhances conductivity.

[0009] S4: Simultaneously, the bottom layer of the filter membrane is spun using both coarse fiber spinning solution and fine fiber spinning solution through air blowing spinning; the coarse fiber spinning solution and antibacterial electret microspheres are mixed with a crosslinking agent and sprayed onto the surface of the bottom layer to form an intermediate layer; the bottom layer operation is repeated and sprayed again to form the top layer with the intermediate layer, thus obtaining a multi-layer filter membrane.

[0010] S5: Hot pressing is performed on the multi-layer filter membrane.

[0011] In a preferred embodiment of the present invention, in S1, the etching is performed using a laser etching machine with a power of 45-55W and a scanning speed of 8-12mm / s to etch pyramid-shaped protrusions on the surface of porous ceramic microspheres. The non-polar material solution is specifically a solution of either polypropylene or polytetrafluoroethylene dissolved in toluene at a concentration of 9-11wt%, a temperature of 55-65℃, and a time of 3-5h.

[0012] In a preferred embodiment of the present invention, in S1, the coating rotation speed is 1800-2200 rpm, the time is 25-35 s, and the thickness is 1-5 μm; the drying temperature is 79-81℃, and the time is 1-3 h; the charge injection specifically involves placing the product in a corona device with a voltage of 10-20 kV, an electrode spacing of 3-7 cm, and a time of 28-32 s.

[0013] In a preferred embodiment of the present invention, in step S2, the antibacterial substance solution is specifically a mixture of one of silver nitrate, copper sulfate, and zinc sulfate with one of the reducing agents polyvinylpyrrolidone, ferrous sulfide, and oxalic acid. The molar concentration of the antibacterial substance solution is 0.05-0.15 mol / L, the concentration of the reducing agent is 0.8-1.2%, the reduction reaction temperature is 59-61℃, and the time is 1-3 h; the drying temperature is 55-65℃.

[0014] In a preferred embodiment of the present invention, in step S3, the coarse fiber material is selected from nylon 6, polypropylene or polycarbonate, and the antibacterial material is selected from sulfonated graphene-supported silver nanoparticles, zinc oxide nanoparticles or copper nanoparticles. The mixing parameters are: the concentration of coarse fiber material is 10-20 wt%, the concentration of antibacterial material is 0.5-1.5 wt%, the mixing temperature is 75-85℃, and the mixing time is 5-7 h.

[0015] In a preferred embodiment of the present invention, in step S3, the ultrafine fiber is specifically a material with a diameter of 200 nm-1 μm, and the ultrafine fiber is specifically one of polyacrylonitrile, polyurethane or polyvinyl alcohol. The conductive reinforcing material is specifically one of carboxylated multi-walled carbon nanotubes, carbon nanofibers or titanium dioxide nanotubes. The fine fiber spinning solution is specifically prepared by dissolving the ultrafine fiber with dimethylformamide, the resulting solution concentration is 5-15 wt%, adding 1-3 wt% of the conductive reinforcing material and 0.1-1 wt% of silver nanoparticles, and mixing them, and then ultrasonically dispersing at 45-55°C for 1-3 h.

[0016] In a preferred embodiment of the present invention, in S4, the bottom layer blowing spinning air pressure is 0.1-0.5MPa, the receiving distance is 10-20cm, and the fibers are arranged in the 0° direction with a spacing of 200-500μm.

[0017] In a preferred embodiment of the present invention, in S4, the intermediate layer coarse fiber spinning solution and the fine fiber spinning solution are mixed in a volume ratio of 1-3:1 and arranged in a 90° direction.

[0018] In a preferred embodiment of the present invention, in S4, the top layer and the bottom layer are symmetrically arranged and have the same process.

[0019] In a preferred embodiment of the present invention, in step S5, the hot pressing temperature is 80-120°C, the pressure is 2-4 MPa, and the time is 2-7 min.

[0020] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0021] (1) This invention provides a method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material. A micron-level rough structure, such as a pyramid or honeycomb morphology, is constructed on the surface of porous ceramic microspheres using laser etching technology. This surface irregularity disrupts the laminar flow state of the airflow, inducing the formation of local turbulence. The turbulent disturbance forces particles to deviate from their original streamline trajectories, increasing the probability of random collisions with the filter medium surface (such as fibers or microspheres). This technique effectively solves the problem of particle inertial escape caused by laminar flow dominance in traditional filter materials, significantly improving the capture capacity for micron- and submicron-sized particles. By enhancing the dynamic interaction between the flow field and particles, fine particles are more easily adsorbed or intercepted by the fiber surface, thereby achieving highly efficient filtration.

[0022] (2) This invention provides a method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material. By employing a multi-layered, orthogonally stacked fiber structure, the adjacent fiber layers are arranged at 90° intervals, forming a three-dimensional cross-linked porous network. When dust-laden airflow passes through, the movement path of the particles is deflected multiple times due to the changing direction of the fiber layers, transforming from a traditional linear penetration path to a complex path of repeated turns. This geometric design significantly extends the movement distance and residence time of particles within the filter medium, forcing multiple collisions between particles and fibers, thereby increasing the interception probability. This technology overcomes the bottleneck of short paths and limited collision opportunities in traditional single-layer or parallel-arranged structures, especially achieving a significant improvement in the interception efficiency of ultrafine particles. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a flowchart of a preferred embodiment of the present invention;

[0025] Figure 2 This is a microstructure diagram of a preferred embodiment of the present invention. Detailed Implementation

[0026] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0028] As shown in the figure, a method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material includes the following steps:

[0029] S1: Etch porous ceramic microspheres, mix and coat them with a non-polar material solution, dry them, and inject charges to obtain electret microspheres;

[0030] In this invention, in step S1, the etching is performed using a laser etching machine with a power of 45-55W and a scanning speed of 8-12mm / s, etching pyramid-shaped protrusions on the surface of porous ceramic microspheres. The non-polar material solution is specifically made by dissolving either polypropylene or polytetrafluoroethylene in toluene at a concentration of 9-11wt%, a temperature of 55-65℃, and a time of 3-5h.

[0031] In this invention, in step S1, the coating rotation speed is 1800-2200 rpm, the time is 25-35 s, and the thickness is 1-5 μm; the drying temperature is 79-81℃, and the time is 1-3 h; the charge injection specifically involves placing the product in a corona device with a voltage of 10-20 kV, an electrode spacing of 3-7 cm, and a time of 28-32 s.

[0032] It should be noted that core-shell electret microspheres are constructed through surface roughening and non-polar material coating. First, laser etching (power 45-55W, scanning speed 8-12mm / s) is used to form pyramidal protrusions on the surface of porous ceramic microspheres. At the molecular level, the high-energy photons of the laser bombard the SiO2 lattice on the ceramic surface, leading to localized melting and solidification, forming a micron-scale rough structure (5-20μm in height). This rough surface can induce a turbulent boundary layer in hydrodynamics, increasing the collision frequency between particles and microspheres. Subsequently, a polypropylene (PP) or polytetrafluoroethylene (PTFE) solution (concentration 9-11wt%) is coated, and an electret layer with a thickness of 1-5μm is formed by spin coating (1800-2200rpm). The non-polar molecular chains of PP (-CH2-CH2- repeating units) are dissolved in toluene solvent and uniformly encapsulate the ceramic microspheres through van der Waals forces, forming a dense non-polar shell after solidification. The low dielectric constant of nonpolar materials (PP dielectric constant approximately 2.2-2.6) effectively suppresses charge migration, providing a stable matrix for subsequent charge injection. Corona charging (voltage 10-20kV) generates high-energy electrons by ionizing air, which penetrate the PP layer and are trapped at trap sites in its molecular chains (such as grain boundary defects or side chain groups), forming a stable electrostatic field with a surface potential of 1-2kV. This electrostatic field exerts a long-range adsorption effect on charged particles (such as PM2.5 with a charge of approximately 10⁻¹⁸-10⁻¹⁷C) through Coulomb forces, thereby improving filtration efficiency.

[0033] S2: Mix the antibacterial substance solution with the electret microspheres of S1, and dry them to obtain antibacterial electret microspheres;

[0034] In this invention, in step S2, the antibacterial substance solution is specifically selected from silver nitrate, copper sulfate, and zinc sulfate, and mixed with a reducing agent from polyvinylpyrrolidone, ferrous sulfide, and oxalic acid. The molar concentration of the antibacterial substance solution is 0.05-0.15 mol / L, the concentration of the reducing agent is 0.8-1.2%, the reduction reaction temperature is 59-61℃, and the time is 1-3 h; the drying temperature is 55-65℃.

[0035] It should be noted that silver nanoparticles (Ag NPs) were loaded onto the surface of the microspheres via a chemical reduction method. Silver nitrate solution (0.05-0.15 mol / L) was mixed with polyvinylpyrrolidone (PVP), and the pyrrolidone ring of PVP was linked to Ag via a NO polar group. + Formation of coordinate bonds, reducing Ag + Reduction potential. When heated to 60℃, the hydroxyl group (-OH) of PVP acts as a reducing agent to reduce Ag. + Restored to Ag 0 This forms Ag NPs with a particle size of 10-50 nm. The antibacterial mechanism of Ag NPs involves the release of Ag. + By binding to the thiol groups (-SH) of bacterial cell membranes, Ag NPs disrupt membrane permeability and inhibit enzyme activity. Simultaneously, the plasmon resonance effect of Ag NPs (absorption peak at approximately 400 nm) generates reactive oxygen species (ROS), further killing microorganisms. The surface roughness of the microspheres (Ra≈5-20 μm) increases the adhesion area of ​​Ag NPs (3-5 times higher than smooth surfaces), resulting in a coverage rate >90%. A drying temperature of 55-65℃ regulates the shrinkage rate of the PVP molecular chains, preventing Ag NP aggregation and maintaining nanoscale dispersion.

[0036] S3: A coarse fiber spinning solution is prepared by mixing a coarse fiber material with a diameter >10μm that can cross-link with hydrogen bonds with an antibacterial material, and a fine fiber spinning solution is prepared by mixing an ultrafine fiber as a skeleton with a material that enhances conductivity.

[0037] In this invention, in step S3, the coarse fiber material is selected from one of nylon 6, polypropylene or polycarbonate, and the antibacterial material is one of one of sulfonated graphene-supported silver nanoparticles, zinc oxide nanoparticles or copper nanoparticles. The mixing parameters are: the concentration of coarse fiber material is 10-20 wt%, the concentration of antibacterial material is 0.5-1.5 wt%, the mixing temperature is 75-85℃, and the mixing time is 5-7 h.

[0038] In this invention, in step S3, the ultrafine fiber is specifically a material with a diameter of 200nm-1μm, and the ultrafine fiber is specifically one of polyacrylonitrile, polyurethane or polyvinyl alcohol. The conductive reinforcing material is specifically one of carboxylated multi-walled carbon nanotubes, carbon nanofibers or titanium dioxide nanotubes. The fine fiber spinning solution is specifically prepared by dissolving the ultrafine fiber with dimethylformamide, the resulting solution concentration is 5-15wt%, adding 1-3wt% of the conductive reinforcing material and 0.1-1wt% of silver nanoparticles, and mixing them, and then ultrasonically dispersing them at 45-55℃ for 1-3h.

[0039] It should be noted that the coarse fiber spinning solution uses nylon 6 (PA-6) as the matrix (concentration 10-20 wt%). The amide groups (-NHCO-) ​​in its molecular chain are bonded to sulfonated graphene (-SO3H) through hydrogen and ionic bonds, forming a three-dimensional network structure. The negative charge repulsion of the sulfonate groups inhibits interchain crystallization of PA-6, resulting in fiber diameters >10 μm and porosity exceeding 85%. The fine fiber spinning solution uses a composite of polyacrylonitrile (PAN) and carboxylated multi-walled carbon nanotubes (MWCNTs). The cyano groups (-CN) of PAN and the -COOH groups of MWCNTs form a conductive pathway (conductivity >10⁻³ S / cm) through dipole-dipole interactions. The axial orientation of MWCNTs (ultrasonic dispersion at 45-55℃) enhances the fiber's mechanical strength (tensile strength increased by 40% to 25-30 MPa). When 0.1-1wt% Ag NPs are added, they disperse with the cyano groups of PAN through coordination to form antibacterial-conductive bifunctional fibers.

[0040] S4: Simultaneously, the bottom layer of the filter membrane is spun using both coarse fiber spinning solution and fine fiber spinning solution through air blowing spinning; the coarse fiber spinning solution and antibacterial electret microspheres are mixed with a crosslinking agent and sprayed onto the surface of the bottom layer to form an intermediate layer; the bottom layer operation is repeated and sprayed again to form the top layer with the intermediate layer, thus obtaining a multi-layer filter membrane.

[0041] In this invention, in step S4, the bottom layer air blowing and spinning pressure is 0.1-0.5 MPa, the receiving distance is 10-20 cm, and the fibers are arranged in a 0° direction with a spacing of 200-500 μm; in step S4, the middle layer coarse fiber spinning solution and fine fiber spinning solution are mixed in a volume ratio of 1-3:1 and arranged in a 90° direction; in step S4, the top layer and the bottom layer are symmetrically arranged and have the same process.

[0042] It should be noted that the bottom layer uses air-blown spinning (air pressure 0.1-0.5 MPa) to arrange coarse / fine fibers at 0°. The micron-sized pores (1-3 μm) of the coarse fibers (PA-6) reduce the initial pressure drop to 45-60 Pa, while the nano-sized pores (0.3-1 μm) of the fine fibers (PAN@MWCNTs) capture ultrafine particles through Brownian motion. The middle layer is sprayed with a coarse fiber spinning solution containing antibacterial electret microspheres (volume ratio 1-3:1), and the 90° orthogonal arrangement creates a three-dimensional interwoven network of pore channels, extending the particle path (increasing the path length by 2-3 times). The hydroxyl groups of the crosslinking agent (such as PVA) form hydrogen bonds with the amide groups of PA-6, while the vinyl alcohol segments of PVA are bonded to the PP electret layer through van der Waals forces, resulting in an interlayer shear strength of 8-12 MPa. The top layer symmetrically replicates the structure of the bottom layer, suppressing interlayer stress concentration through thermodynamic equilibrium.

[0043] S5: Hot pressing is performed on the multi-layer filter membrane.

[0044] In this invention, in step S5, the hot pressing temperature is 80-120℃, the pressure is 2-4MPa, and the time is 2-7min.

[0045] It should be noted that hot pressing (80-120℃, 2-4MPa, 2-7min) optimizes the interface through molecular chain movement and rearrangement. The glass transition temperature (Tg≈50℃) of PA-6 is surpassed at this temperature, causing partial melting of molecular chain segments and forming an interpenetrating network with the PAN cyano groups of the adjacent layer (Tg≈85℃). Pressure drives further orientation of MWCNTs along the fiber axis, improving the connectivity of the conductive network (resistivity decreases to 10). 2 (Ω·cm). Simultaneously, hot pressing promotes the embedding of Ag NPs into the fiber surface (embedding depth approximately 10-50 nm), preventing detachment and maintaining long-lasting antibacterial properties. This process regulates the porosity to 75-85%, balancing filtration efficiency (>99.97%) with pressure drop (<120 Pa).

[0046] Example 1

[0047] In the preparation of core-shell electret microspheres, a 50W laser was used to etch porous ceramic microspheres (100μm in diameter) at a scanning speed of 10mm / s and an etching depth of 15μm, forming pyramidal protrusions with a substrate side length of 10μm and a height of 15μm. The laser energy melted and recrystallized the SiO2 lattice, increasing the surface roughness (Ra) to 8-10μm and inducing localized turbulence in the airflow (Reynolds number Re≈200), increasing the probability of particle collisions by 20%. Subsequently, polypropylene (PP) was dissolved in toluene at a concentration of 10wt%, and a 3μm thick coating layer was formed by spin coating at 2000rpm, followed by vacuum drying at 80℃ for 2h. After corona charging (voltage 15kV, time 30s), the surface potential reached 1.5kV. The nonpolar -CH2-CH2- segments of PP suppressed charge dissipation, resulting in a charge half-life >200 days and an electrostatic field (E≈1.5×10⁻⁶). 6 The V / m) improves the long-range adsorption efficiency of charged PM2.5 by 18%.

[0048] Antibacterial modification was achieved by reacting silver nitrate (0.1 mol / L) with polyvinylpyrrolidone (PVP, 1 wt%) at 60 °C for 2 h. The NO coordination groups of PVP controlled the formation of Ag NPs with a particle size of 20-30 nm and a coverage rate >95%. The Ag NPs were embedded in the rough structure of the microsphere surface through van der Waals forces, and the dissolution rate remained stable at 0.12 μg / cm³. 2 • h, 24h inhibition rate > 99.5% (Escherichia coli).

[0049] In the preparation of the two-component spinning solution, nylon 6 (PA-6) was dissolved in formic acid at a concentration of 15 wt%, and mixed with 1 wt% sulfonated graphene-supported silver nanoparticles. The sulfonate groups (-SO3H) formed a hydrogen bond network with the amide groups (-NHCO-) ​​of PA-6, inhibiting the regular arrangement of molecular chains, reducing the crystallinity to 28%, and achieving a porosity of 88%. Polyacrylonitrile (PAN) and carboxylated multi-walled carbon nanotubes (MWCNTs, 2 wt%) were ultrasonically dispersed in DMF at 50 °C for 2 h. The axial orientation of MWCNTs was >90%, the fiber conductivity increased to 1.8 × 10⁻³ S / cm, and the tensile strength reached 29.5 MPa.

[0050] The sandwich structure is spun using an air-blowing process (0.3 MPa). The bottom layer consists of coarse fibers (5 μm in diameter) and fine fibers (500 nm in diameter) arranged at 0° with a spacing of 300 μm, resulting in an initial pressure drop of only 55 Pa. The middle layer is sprayed with a PA-6 spinning solution (volume ratio 2:1) containing 30% electret microspheres, with a 90° orthogonal arrangement extending the particle path by 3 times. After PVA crosslinking, the interlaminar shear strength reaches 10 MPa. The top layer replicates the structure of the bottom layer, balancing the stress distribution.

[0051] Hot-pressing (100℃, 3MPa, 5min) partially melts the PA-6 molecular chains, forming a 30nm interpenetrating network with PAN cyano groups, increasing the axial orientation of MWCNTs to 95%. Ag NPs are embedded 20nm deep into the fiber surface, maintaining a 92% antibacterial rate after 100 cycles. The final material achieves a filtration efficiency of 99.98% (0.3μm particles), a pressure drop of 108Pa, and a tensile strength of 29.5MPa, making it suitable for high-end air purification systems.

[0052] Key parameter advantages: The synergistic effect of laser etching power of 50W and scanning speed of 10mm / s enables the microsphere surface roughness (Ra=8-10μm) and turbulence intensity (Re≈200) to achieve the optimal balance, and the particle collision probability is increased by 20% compared with traditional processes, laying the structural foundation for high-efficiency filtration.

[0053] Experiment 1

[0054] The filter membrane prepared in Example 1 above was used as a control group. The laser etching power and scanning speed, as well as the arrangement angle of the intermediate layer, were changed to alter the three-dimensional interlaced pore network structure. Standard particles were uniformly injected into the upstream air duct of the filter using aerosol injection. The uniformity of particle distribution was ensured by using a mixer (such as a Venturi tube). The concentration of particles entering and exiting the filter membrane was recorded, and the filtration efficiency was recorded based on the concentration. See Table 1 for details.

[0055] Table 1

[0056]

[0057] In the above experiments, the influence mechanism of power, scanning speed, and alignment angle on the dust particle capture efficiency can be comprehensively analyzed from the perspective of two core beneficial effects: surface roughening-induced turbulence and orthogonal alignment extending the particle trajectory. First, the synergistic effect of laser etching power (50W) and scanning speed (10mm / s) directly determines the formation quality of the rough structure on the surface of porous ceramic microspheres. When the power is below 50W (such as 45W in experimental group 1), the laser energy is insufficient to fully melt the SiO2 lattice, resulting in insufficient height of the surface pyramid protrusions (e.g., only 5-10μm), and the roughness (Ra≈3-5μm) is significantly lower than that of the control group (Ra≈8-10μm). At this time, the turbulence intensity (Reynolds number Re≈100-150) when the airflow passes through the microsphere surface is insufficient to significantly disturb the particle trajectory. The particle inertial force corresponding to the Stokes number (St≈0.1-0.5) dominates the direction of motion, and the probability of collision between particles and the fiber surface decreases, resulting in a decrease in filtration efficiency from 97.63% in the control group to 94.21%. Conversely, when the power is too high (such as 55W in Experimental Group 2), excessive laser energy can lead to over-melting of the microsphere surface, increasing the side length of the pyramid structure base (e.g., above 20μm). Although the surface roughness increases (Ra≈12μm), the porosity decreases (from 70% to 55%), the airflow channels narrow, and the scale of the turbulent vortex (approximately 10... -4 m) and the range of particle inertial motion (10 -5 The mismatch between the m) and the turbulence actually weakens the perturbation effect of the turbulence on the particles, reducing the filtration efficiency to 94.03%. Therefore, the power parameters need to be precisely matched with the scanning speed (10 mm / s) to ensure the formation of a uniformly distributed pyramid structure during the melt-recrystallization process, which can both induce microscale turbulence (Re≈200) and facilitate Brownian motion (D≈10-11). m 2 ( / s) Enhances diffusion adsorption of 0.3-1μm particles.

[0058] Secondly, the adjustment of the scanning speed (8 mm / s in experimental group 3 and 12 mm / s in experimental group 4) directly affects the thermal accumulation effect of laser etching. When the scanning speed is reduced to 8 mm / s, the laser's interaction time per unit area is prolonged, causing the local temperature on the microsphere surface to exceed the glass transition temperature of SiO2 (approximately 1200 °C). The molten region expands, the spacing between the pyramidal protrusions decreases (e.g., from 30 μm to 15 μm), and although the surface roughness increases (Ra≈10 μm), the connectivity of the pore structure decreases, and the airflow resistance increases (pressure rise ΔP increases from 108 Pa to 150 Pa). At this point, although the turbulence intensity (Re≈250) is enhanced, the airflow velocity distribution is uneven, and particles are more likely to penetrate directly through the narrow pores due to inertial collisions rather than being captured by turbulent disturbances, resulting in an efficiency reduction to 93.65%. Conversely, when the scanning speed is increased to 12 mm / s, the laser interaction time is too short, resulting in insufficient melting. Only a shallow layer of protrusions (approximately 5 μm in height, Ra ≈ 4 μm) forms on the surface, with weak turbulence (Re ≈ 80). The particle trajectory remains almost laminar, significantly reducing the collision probability and lowering the efficiency to 93.97%. Therefore, the scanning speed must be matched with the power (50 W) to achieve an ideal rough structure through thermodynamic equilibrium, maintaining porosity (approximately 70%) to control pressure drop while simultaneously achieving turbulent disturbance (vortex scale 10). -5 The system covers the inertial motion range of PM2.5 particles (St≈0.3-1) to achieve efficient capture.

[0059] Finally, the orthogonal arrangement angle (0-90-0) between the intermediate and bottom fibers is the core design parameter for extending the particle trajectory. In experimental groups five (0-90-45) and six (0-90-90), the geometric symmetry of the three-dimensional porous network was disrupted after the arrangement angles deviated from the orthogonal structure. Taking the 45° arrangement in experimental group five as an example, the angle between the third fiber layer and the intermediate layer decreased from 90° to 45°, resulting in insufficient path turning angles during airflow (from 90° to 45°), reducing the number of turning points in the particle trajectory (from 3 to 2), and shortening the average residence time from 95ms in the control group to 60ms. According to the Langevin equation, particle displacement (Δx) is proportional to the square root of diffusion time (t) (Δx≈√(2Dt)). The shortened residence time reduces the diffusion distance of 0.3μm particles from 1.4μm to 1.1μm, preventing them from fully approaching the fiber surface, reducing the collision probability, and lowering the efficiency to 92.74%. Although the 90° arrangement in Experiment Group 6 appears to maintain orthogonality, the third and middle layers are aligned (90°), effectively creating two overlapping layers in the same direction. This increases the overlap of the pore network, shortening the effective filtration path length from 320 μm to 200 μm. Particles are more likely to escape along straight channels, reducing efficiency to 93.05%. Therefore, a strictly orthogonal arrangement (0-90-0) forces the airflow direction to deflect by 90° in each layer through three-dimensional staggered pores, extending the particle path length to three times (320 μm vs. 100 μm per layer). Furthermore, the hydrogen bond network (bond energy ≈ 20 kJ / mol) at the interlayer interfaces (such as the PA-6 and PAN crosslinking region) enhances particle adsorption, ultimately achieving a high filtration efficiency of 97.63%.

[0060] The optimized combination of power and scanning speed ensures precise control of the surface roughening structure, while the orthogonal alignment angle maximizes the path extension effect through geometric design. Turbulence induced by the rough surface causes particles to deviate from the mainstream, while the orthogonal structure increases the contact opportunities between particles and fibers by extending the path. The combined effect of these two factors increases the collision probability of 0.3μm particles from 95% in conventional films to 99.97%. Experimental data show that deviations from any parameter (e.g., power ±5W, scanning speed ±2mm / s, angle ±45°) lead to a significant decrease in turbulence intensity or path length, resulting in a 3-5% reduction in efficiency, thus confirming the necessity of synergistic parameter optimization.

[0061] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material, characterized in that, Includes the following steps: S1: Etch porous ceramic microspheres, mix and coat them with a non-polar material solution, dry them, and inject charges to obtain electret microspheres; S2: Mix the antibacterial substance solution with the electret microspheres of S1, and dry them to obtain antibacterial electret microspheres; S3: A coarse fiber spinning solution is prepared by mixing a coarse fiber material with a diameter >10μm that can cross-link with hydrogen bonds with an antibacterial material, and a fine fiber spinning solution is prepared by mixing an ultrafine fiber as a skeleton with a material that enhances conductivity. S4: Simultaneously, the bottom layer of the filter membrane is spun using both coarse fiber spinning solution and fine fiber spinning solution through air blowing spinning; the coarse fiber spinning solution and antibacterial electret microspheres are mixed with a crosslinking agent and sprayed onto the surface of the bottom layer to form an intermediate layer; the bottom layer operation is repeated and sprayed again to form the top layer with the intermediate layer, thus obtaining a multi-layer filter membrane. S5: Hot pressing is performed on the multi-layer filter membrane.

2. The method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material according to claim 1, characterized in that: In step S1, the etching is performed using a laser etching machine with a power of 45-55W and a scanning speed of 8-12mm / s. Pyramid-shaped protrusions are etched onto the surface of porous ceramic microspheres. The non-polar material solution is specifically a solution of either polypropylene or polytetrafluoroethylene dissolved in toluene at a concentration of 9-11wt%, a temperature of 55-65℃, and a time of 3-5h.

3. The method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material according to claim 1, characterized in that: In S1, the coating speed is 1800-2200 rpm, the time is 25-35 s, and the thickness is 1-5 μm; the drying temperature is 79-81℃, and the time is 1-3 h; the charge injection is specifically carried out by placing the product in a corona device, with a voltage of 10-20 kV, an electrode spacing of 3-7 cm, and a time of 28-32 s.

4. The method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material according to claim 1, characterized in that: In step S2, the antibacterial substance solution is specifically a mixture of one of silver nitrate, copper sulfate, and zinc sulfate with one of the reducing agents polyvinylpyrrolidone, ferrous sulfide, and oxalic acid. The molar concentration of the antibacterial substance solution is 0.05-0.15 mol / L, the concentration of the reducing agent is 0.8-1.2%, the reduction reaction temperature is 59-61℃, and the time is 1-3 h; the drying temperature is 55-65℃.

5. The method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material according to claim 1, characterized in that: In step S3, the coarse fiber material is selected from nylon 6, polypropylene or polycarbonate, and the antibacterial material is selected from sulfonated graphene supported nano-silver powder, zinc oxide nanoparticles or nano-copper particles. The mixing parameters are: coarse fiber material concentration of 10-20 wt%, antibacterial material concentration of 0.5-1.5 wt%, mixing temperature of 75-85℃, and mixing time of 5-7 h.

6. The method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material according to claim 1, characterized in that: In step S3, the ultrafine fiber is specifically a material with a diameter of 200 nm to 1 μm. The ultrafine fiber is specifically one of polyacrylonitrile, polyurethane, or polyvinyl alcohol. The conductive reinforcing material is specifically one of carboxylated multi-walled carbon nanotubes, carbon nanofibers, or titanium dioxide nanotubes. The fine fiber spinning solution is specifically prepared by dissolving the ultrafine fiber in dimethylformamide to obtain a solution concentration of 5-15 wt%, adding a conductive reinforcing material with a concentration of 1-3 wt% and silver nanoparticles with a concentration of 0.1-1 wt%, and then ultrasonically dispersing the mixture at 45-55°C for 1-3 hours.

7. The method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material according to claim 1, characterized in that: In S4, the bottom layer air blowing and spinning air pressure is 0.1-0.5MPa, the receiving distance is 10-20cm, and the fibers are arranged in the 0° direction with a spacing of 200-500μm.

8. The method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material according to claim 1, characterized in that: In step S4, the intermediate layer coarse fiber spinning solution and fine fiber spinning solution are mixed in a volume ratio of 1-3:1 and arranged in a 90° direction.

9. The method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material according to claim 1, characterized in that: In S4, the top and bottom layers are symmetrically arranged and have the same process.

10. The method for preparing a highly efficient nylon 6 micro / nano fiber antibacterial air filter membrane material according to claim 1, characterized in that: In S5, the hot-pressing temperature is 80-120℃, the pressure is 2-4MPa, and the time is 2-7min.

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