Hot air nonwoven fabric with long-acting antibacterial function and preparation method thereof

Abstract

The application discloses hot air non-woven fabric with long-acting antibacterial function and a preparation method thereof, and belongs to the technical field of functional non-woven fabric. The hot air non-woven fabric takes ES fiber with a skin-core structure as a three-dimensional fluffy framework, the skin layer of the ES fiber is polyethylene, and the core layer is polyester; fluorosilane coupling agent composite antibacterial microcapsules are distributed in-situ inside and on the surface of the polyethylene skin layer, the core layer of the fluorosilane coupling agent composite antibacterial microcapsules is composed of long-chain alkyl dimethyl benzyl quaternary ammonium salt and polyhexamethylene biguanide hydrochloride, and the microcapsule surface is modified by the fluorosilane coupling agent, and then the microcapsule is fixed on the polyethylene skin layer through a double locking structure of physical anchoring and chemical covalent bonding. The application is a non-release type contact sterilization, the antibacterial rate of the three kinds of bacteria is all greater than or equal to 90% after washing 50 times according to the AATCC 61-2A standard, meanwhile, the inherent fluffy and soft characteristics of the ES fiber are completely reserved, and the application is suitable for medical dressings, maternal and infant hygiene materials and disposable wiping cloths.

Description

Technical Field

[0001] This invention belongs to the field of functional nonwoven fabric technology, specifically relating to a hot-air nonwoven fabric with long-lasting antibacterial function and its preparation method. The nonwoven fabric uses fluorosilane-modified chitosan-sodium tripolyphosphate dual antibacterial component microcapsules confined and loaded into the ES fiber polyethylene skin layer, possessing a physical and covalent dual locking structure and non-release long-lasting washable antibacterial properties. Background Technology

[0002] Hot-air nonwoven fabrics are formed by melt bonding ES fiber sheaths with polyethylene, resulting in a fluffy, soft texture and excellent breathability. They are widely used in medical dressings, baby hygiene products, and disposable wipes. However, conventional hot-air nonwoven fabrics lack antibacterial properties and are prone to bacterial and fungal growth after absorbing water, posing a risk of cross-infection. Currently, mainstream long-lasting antibacterial modification solutions in the industry all have irreconcilable shortcomings, including publicly disclosed microcapsule composite fiber patents. 1. Post-treatment impregnation / spraying antibacterial solution: The antibacterial agent only relies on physical adsorption to adhere to the fiber surface, without chemical bond binding. After washing, the antibacterial rate quickly drops below 70%, and free antibacterial agent continues to precipitate, posing a risk of skin irritation. 2. Direct blending of inorganic antibacterial agents into spinning: Inorganic particles such as silver and zinc oxide are prone to agglomeration, which leads to increased spinning breakage rate and particle defects on the fabric surface; long-term migration of heavy metals poses a risk of bioaccumulation, while hard particles increase fiber rigidity and reduce the bulkiness of the finished product. 3. Direct blending and spinning of common organic antibacterial agents: without microencapsulation, small molecule quaternary ammonium salts and biguanides are prone to volatilization and decomposition during high-temperature melt spinning. Long-term storage will cause white crystals to precipitate on the fiber surface, and the water wash resistance is extremely poor. 4. Reference document CN2025113595418 discloses a composite fiber in which antibacterial microcapsules are added to the polyester core layer. The antibacterial microcapsules are placed in the polyester core layer, and only a small amount of antibacterial auxiliaries are added to the outer layer. The spinning temperature of the polyester core layer is as high as 280℃. At this high temperature, the microcapsule wall material is prone to high-temperature pyrolysis and failure. The microcapsules are deeply buried in the fiber core, making it difficult for them to come into contact with external microorganisms. Moreover, there is no covalent modification of fluorosilane on the surface of the microcapsules. It relies solely on physical blending. The antibacterial components are easily lost during water washing. After 50 washes according to GB / T 20944.3 (this standard is relatively lower than the requirements of AATCC 61-2A), the antibacterial rate is about 83.0%-92.1%, and the antibacterial efficiency is greatly reduced. At the same time, the addition of rigid microcapsules to the core layer will destroy the fluffy support structure of the fiber, and the softness of the finished product will be significantly reduced.

[0003] 5. Commercially available microcapsule blended fibers: Most use gelatin and gum arabic as wall materials, with a heat resistance temperature below 160℃, making them unsuitable for high-temperature processing of polyethylene melt granulation and spinning; the core material only encapsulates a single antibacterial component without synergistic bactericidal design; without fluorosilane interface modification, the microcapsules have poor compatibility with polyolefins, making them prone to fiber breakage during spinning; during washing, water seeps into the capsule, causing swelling and leakage of antibacterial agents, making them a release-type antibacterial system.

[0004] Existing technologies cannot simultaneously meet the five core performance requirements: ① ≥90% inhibition rate against three types of pathogenic bacteria after 50 washes according to AATCC 61-2A standard; ② High biocompatibility with no antibacterial component analysis; ③ Complete retention of the high bulkiness and softness of hot-air nonwoven fabric; ④ Microcapsules that can withstand the high temperatures of polyethylene spinning without rupture; ⑤ Long-term stable fixation of antibacterial components through chemical bonds. To address these technical problems, this invention provides a complete, scalable technical solution. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing antibacterial hot-air nonwoven fabrics, such as easy loss of antibacterial components, risk of antibacterial release, stiff finished product feel, microcapsules' inability to withstand high temperatures, and failure of antibacterial properties under load on the core layer. It provides a hot-air nonwoven fabric with long-lasting antibacterial function and its preparation method. This nonwoven fabric can achieve broad-spectrum non-release contact sterilization, long-lasting antibacterial effect after 50 washes according to AATCC 61-2A standard, and fully retains the fluffy and soft properties of the substrate. The entire process of this invention can be directly adapted to existing continuous production lines for hot-air nonwoven fabrics.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a hot-air nonwoven fabric with long-lasting antibacterial function, which is formed by interweaving ES fibers with a core-sheath structure to form a three-dimensional fluffy skeleton. The ES fiber sheath is polyethylene and the core layer is polyester. Fluorosilane coupling agent composite antibacterial microcapsules are distributed in situ inside and on the surface of the polyethylene sheath. "In situ distribution" means that the microcapsules are synchronously and uniformly dispersed during the polyethylene melt spinning stage and form covalent bonds with the polyethylene in situ, without the need for post-dip or post-spray antibacterial treatment of the finished product.

[0007] Fluorosilane coupling agent composite antibacterial microcapsules encapsulate two antibacterial active ingredients, long-chain alkyl dimethyl benzyl quaternary ammonium salt and polyhexamethylene biguanide hydrochloride, with chitosan-sodium tripolyphosphate ion gel wall material. After the surface of the microcapsules is modified with fluorosilane coupling agent, they are fixed to the polyethylene skin through a dual locking structure of physical anchoring and chemical covalent bonding.

[0008] Furthermore, the wall material is prepared by iontophoresis of chitosan and sodium tripolyphosphate at a mass ratio of 4-6:1, and the mass ratio of long-chain alkyl dimethyl benzyl quaternary ammonium salt to polyhexamethylene biguanide hydrochloride in the core material is 40-60:5-10; the particle size of the fluorosilane coupling agent composite antibacterial microcapsules is controlled to be 50-300 nm, and the mass of the wall material accounts for 10%-30% of the total mass of the microcapsules.

[0009] The surface of the microcapsules is grafted with a fluorosilane coupling agent, and the amount of the coupling agent added is 1% to 3% of the solid content of the microcapsules.

[0010] Fluorosilane-modified composite antibacterial microcapsules are embedded in the polyethylene skin to form a physical anchor, and the fluorosilane groups cross-link with the polyethylene molecular chain to form chemical covalent bonds, thus constructing a dual locking system. (1) Physical anchoring: The molten polyethylene completely encapsulates and embeds the fluorosilane-modified composite antibacterial microcapsules. Relying on the spatial limitation of the polymer matrix, the microcapsules are not easy to peel off during friction and washing. (2) Chemical covalent bonding: Fluorosilane acts as a bridging molecule, forming molecular-level cross-links between the microcapsule and the polyethylene molecular chain. Even after long-term water washing and repeated friction, the microcapsule remains stably bound to the inside of the skin. Both are indispensable. If the covalent modification of fluorosilane is cancelled, the antibacterial rate of the physically mixed sample will be greatly reduced after multiple water washings.

[0011] After testing, the finished product showed an inhibition rate of ≥90% against Escherichia coli, Staphylococcus aureus, and Candida albicans after 50 washes according to AATCC 61-2A standard; no antibacterial activity was observed after 24 hours of soaking in physiological saline; and the fluffiness was ≥25cm. 3 / g.

[0012] In a preferred embodiment, the long-chain alkyl dimethyl benzyl quaternary ammonium salt is selected from at least one of dodecyl dimethyl benzyl quaternary ammonium salt, hexadecyl dimethyl benzyl quaternary ammonium salt, etc.

[0013] In the preferred embodiment, the ES fiber has a fineness of 1.5–3D, a length of 38 mm, and a core-sheath ratio of 50:50; the nonwoven fabric has a surface density of 20–35 g / m². 2 Loftiness ≥ 25cm 3 / g.

[0014] Secondly, the present invention provides a method for preparing the above-mentioned hot air nonwoven fabric, comprising the following steps: a) Preparation of fluorosilane-modified composite antibacterial microcapsules and antibacterial masterbatch for skin layer: A chitosan aqueous solution with a concentration of 0.5–10 wt% was prepared and mixed with sodium tripolyphosphate at a mass ratio of 1:(4–6) to obtain a chitosan-sodium tripolyphosphate reaction solution. Long-chain alkyl dimethyl benzyl quaternary ammonium salt and polyhexamethylene biguanide hydrochloride were added to the chitosan-sodium tripolyphosphate reaction solution and subjected to constant temperature stirring at a reaction temperature of 30–50℃ and pH=4–6 for 25–35 min to obtain a core-shell microcapsule suspension with dual antibacterial components. A fluorosilane coupling agent accounting for 1%–3% of the solid content of the microcapsules was added to the suspension and surface grafting was completed by stirring at 50–70℃. After centrifugation, washing with ethanol, and low-temperature freeze drying, fluorosilane-modified composite antibacterial microcapsules were obtained. The fluorosilane-modified composite antibacterial microcapsules and polyethylene chips were melt-blended with a twin-screw extruder at a mass ratio of 1:(5–9) and extruded and granulated at 185–195℃ to obtain an antibacterial masterbatch for use only in skin spinning. b) Spinning of antibacterial ES fiber with sheath and core: Antibacterial ES fiber is prepared using the antibacterial masterbatch obtained in step a) as the sole raw material for the sheath and polyester chips as the raw material for the core. c) Hot air bonding molding: Antibacterial ES fibers are opened, combed and laid into a uniform fiber web, and hot air at 135-145℃ penetrates and heat-bonds them to obtain a hot air nonwoven fabric semi-finished product. d) Finishing after online corona activation: The semi-finished hot air nonwoven fabric is continuously surface activated by an 8-12kW corona equipment at a linear speed of 60-80m / min to enhance the interfacial bonding force between the microcapsules and polyethylene. After cooling, winding, and slitting, the long-lasting antibacterial hot air nonwoven fabric is obtained.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. Fluorosilane-modified composite antibacterial microcapsules are embedded in the polyethylene sheath to form physical confinement. Fluorosilane forms irreversible covalent crosslinks between the microcapsules and polyethylene, resulting in a synergistic effect of dual confinement. Multiple control experiments have demonstrated that neither fluorosilane modification nor changes to the microcapsule loading position can achieve the long-term antibacterial rate of ≥90% after 50 washes, thus fundamentally solving the problem of rapid failure of traditional antibacterial nonwoven fabrics after washing.

[0016] 2. By encapsulating two differentiated bactericidal components, long-chain alkyl dimethyl benzyl quaternary ammonium salt and polyhexamethylene biguanide hydrochloride, within heat-resistant microcapsules, the biocompatibility is significantly improved compared to core-layer microcapsules and direct co-release formulations. While quaternary ammonium salts and polyhexamethylene biguanide are common antibacterial substances, using a single ingredient alone cannot achieve the multiple effects of long-lasting water resistance, non-release, and high bulkiness. This invention creatively encapsulates both antibacterial agents within high-temperature ionogel microcapsules. The long-chain alkyl dimethyl benzyl quaternary ammonium salt disrupts the cell membrane structure of pathogenic bacteria, while polyhexamethylene biguanide hydrochloride blocks microbial nucleic acid metabolism. The combined bactericidal mechanisms result in an initial antibacterial rate of nearly 99%. The dual-locking structure restricts the outward migration of antibacterial molecules. No antibacterial activity was detected after 24 hours of saline immersion, classifying it as a non-release contact bactericidal material. Skin irritation testing shows a level 0 rating, with no free antibacterial agent coming into contact with the human body, making it suitable for medical wound dressings and maternal and infant hygiene materials. The dual antibacterial components work synergistically to kill bacteria through non-release contact, thus resolving the safety hazards associated with the release of conventional antibacterial agents.

[0017] 3. The polyester core layer is free of rigid microcapsule fillers, fully maintaining the three-dimensional, fluffy support framework of the ES fibers. Compared to samples with microcapsules added to the core layer, the finished product of this invention exhibits a more than 30% increase in bulkiness, and the fiber softness is not significantly different from that of blank unmodified hot-air nonwoven fabric. This overcomes the defects of fiber stiffening and decreased bulkiness caused by inorganic blending and surface grafting processes. If microcapsules are added to the core layer or blended with all fibers, fiber rigidity increases, and the product's bulkiness and softness decrease significantly.

[0018] 4. The chitosan-sodium tripolyphosphate iontophoresis gel wall material has a heat resistance of ≥200℃, and is combined with a fluorosilane hydrophobic protective layer. The capsules remain intact throughout the granulation and spinning process, preventing antibacterial agent volatilization and loss. It exhibits a low spinning breakage rate, a fabric surface free of particle defects, and stable mechanical properties in the finished product, superior to commercially available gelatin-based microcapsule systems. This invention achieves simultaneous compliance with three key indicators: a stable antibacterial rate of ≥90% after 50 washes, no release of antibacterial components (non-release type), and a bulkiness of ≥25cm. 3 The three indicators ( / g) must be achieved simultaneously, which cannot be satisfied by existing publicly available solutions.

[0019] 5. The fiber combing, hot air bonding, and corona activation processes in the preparation method of this invention are all mature and commonly used equipment in the industry. Only two pre-processing steps, microcapsule preparation and antibacterial masterbatch granulation, are added. There is no need for large-scale modification of existing hot air nonwoven fabric production lines. The equipment investment increment is small and it is suitable for large-scale industrial production. The long-lasting antibacterial performance is achieved by combining two-component antibacterial microcapsules → fluorosilane interface covalently modified skin layer masterbatch → core fiber skin layer directional loading → physical and chemical dual locking long-term fixation → non-release contact sterilization. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the fluorosilane-modified composite antibacterial microcapsule loaded with antibacterial ES fiber according to the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the fluorosilane coupling agent composite antibacterial microcapsule of the present invention.

[0022] Figure 3 This is a schematic diagram of the complete preparation method of one embodiment of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be described in detail below with reference to the embodiments. The embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0024] This invention utilizes a fluorosilane coupling agent with dual functionalities: the silanol terminals bond to the polar groups on the surface of chitosan microcapsules, while the fluoroalkyl terminals undergo interfacial crosslinking with the nonpolar molecular chains of polyethylene during melt processing, forming irreversible covalent bonds. Simultaneously, the fluorosilane constructs a dense hydrophobic protective layer on the outer layer of the microcapsules, preventing water penetration into the capsule interior during washing and avoiding swelling and cracking of the wall material, thus reducing antibacterial agent leakage at its source. Using microcapsules alone, adding fluorosilane alone, or replacing other types of coupling agents cannot achieve the comprehensive effect of long-lasting water resistance. Conventional aminosilanes and titanates can only achieve simple dispersion of microcapsules in a polymer matrix and cannot form stable covalent bonds with polyethylene.

[0025] In this invention, the polyethylene sheath spinning temperature is only 190°C, which is lower than the heat resistance limit of the microcapsules. Confining the microcapsules within the polyethylene sheath helps maintain the integrity of the capsule structure. If added to the core layer, the high temperature of the polyester core layer at 280°C would directly damage the microcapsule wall material, causing the antibacterial agent to completely fail. The microcapsules are concentrated in the fiber surface area, allowing microorganisms to directly contact the antibacterial functional groups, resulting in a much higher contact sterilization efficiency than the microcapsule design with the core layer deeply buried. In addition, the polyester core layer does not contain any rigid microcapsules, thus maintaining the three-dimensional fluffy support structure of the ES fiber. If microcapsules are added to the core layer, the fiber rigidity increases significantly, and the fluffiness of the finished product decreases.

[0026] This invention achieves non-release contact sterilization. The product has excellent water resistance. After 50 washes according to AATCC 61-2A standard, the antibacterial rate against Escherichia coli, Staphylococcus aureus, and Candida albicans is ≥90%. At the same time, it fully retains the inherent fluffy and soft properties of ES fiber. The process is compatible with existing hot air nonwoven fabric production lines and is suitable for medical dressings, maternal and infant hygiene materials, and disposable wipes.

[0027] Example 1 The preparation method of the hot-air nonwoven fabric with long-lasting antibacterial function in this embodiment includes the following steps: Preparation of S1 antibacterial masterbatch Take 50 parts by weight of hexadecyl dimethyl benzyl quaternary ammonium salt and 8 parts by weight of polyhexamethylene biguanide hydrochloride, add an aqueous solution with a chitosan concentration of 1.5 wt% and a sodium tripolyphosphate / chitosan mass ratio of 1:5; react at 40℃ and pH=5.0 for 30 min to obtain a microcapsule suspension; add 2% by weight of fluorosilane coupling agent of microcapsule solids, stir at 60℃ for 2 h for modification; centrifuge, wash with ethanol, and freeze dry at -40℃ to obtain fluorosilane-modified composite antibacterial microcapsules; blend the fluorosilane-modified composite antibacterial microcapsules with polyethylene chips at a ratio of 1:9, and granulate by twin-screw extrusion at 185-195℃ to obtain a skin-specific antibacterial masterbatch.

[0028] S2 antibacterial ES fiber preparation Using the aforementioned antibacterial masterbatch as the sheath material and polyester chips as the core material, a composite spinning process with a sheath-core mass ratio of 50:50 was carried out. The sheath spinning temperature was 190℃, and the core spinning temperature was 280℃. The spun fiber bundle was stretched, crimped, heat-set, and cut to obtain antibacterial ES fiber with a fineness of 2D and a length of 38mm.

[0029] S3 Hot Air Adhesive Molding Antibacterial ES fibers are prepared by sequentially opening, cross-carding, and uniform web laying to achieve an areal density of 30 g / m². 2 Uniform fiber web; the fiber is fed into a hot air oven, the temperature of the hot bonding section is 138℃, the hot air speed is 1.0m / s, the heat preservation bonding time is 10s, and the non-woven fabric semi-finished product is obtained by relying on the molten bonding of the polyethylene skin layer.

[0030] S4 Online Post-Stun Treatment The nonwoven fabric semi-finished product is continuously passed through a corona activation device with a corona power of 10kW and a device operating line speed of 75m / min; after cooling, traction winding, and longitudinal slitting, the long-lasting antibacterial hot air nonwoven fabric finished product is obtained.

[0031] (5) Performance standard test Antibacterial properties (GB / T 20944.3-2008): 99.1% inhibition rate against Escherichia coli, 99% inhibition rate against Staphylococcus aureus, and 97% inhibition rate against Candida albicans; Wash resistance (AATCC 61-2A, 50 washes): Escherichia coli 99.0%, Staphylococcus aureus 98.8%, Candida albicans 96.5%; Physical properties: Loftiness 28cm 3 / g; Biosafety testing (ISO 10993-10): Skin irritation level 0; Antibacterial release test: After soaking in sterile physiological saline at 37℃ for 24 hours, no antibacterial activity was detected in the soaking solution.

[0032] (6) Verification experiment on non-release antibacterial mechanism Experimental group: The finished product of this embodiment; Control group 1: Conventional impregnation and finishing of antibacterial hot air fabric; Control group 2: Samples without microcapsules, directly blended with antibacterial agents in spinning; Three groups of samples were simultaneously immersed in a shaking solution at 37°C for 24 hours, and the antibacterial activity of the immersion solution was tested. The results showed that the immersion solution in the experimental group had no antibacterial effect, while the immersion solutions in control groups 1 and 2 both showed significant antibacterial activity, proving that the present invention is a non-release contact sterilization system.

[0033] Figure 1 This is a schematic diagram of the structure of fluorosilane-modified composite antibacterial microcapsules loaded with antibacterial ES fibers according to an embodiment of the present invention. A three-dimensional, fluffy skeleton is formed by interwoven ES fibers with a core-sheath structure. The ES fibers include a polyethylene sheath 2 and a polyester core 1. The ES fiber has fluorosilane coupling agent modified composite antibacterial microcapsules 3 distributed in situ only inside and on the surface of the polyethylene sheath; the fluorosilane coupling agent modified composite antibacterial microcapsules are core-shell structured microcapsules (see...). Figure 2 The microcapsules are prepared using chitosan and sodium tripolyphosphate as wall materials 31, and long-chain alkyl dimethyl benzyl quaternary ammonium salt and polyhexamethylene biguanide hydrochloride as core materials 32, with the surface of the microcapsules modified by a fluorosilane coupling agent. The fluorosilane coupling agent composite antibacterial microcapsules are completely embedded inside the polyethylene shell to form a physical anchoring structure. The fluorosilane groups 33 on the microcapsule surface undergo interfacial crosslinking with the polyethylene molecular chains to form stable chemical covalent bonds, constructing a dual-locking system of physical anchoring A and fluorosilane covalent bonding B.

[0034] Example 2 (1) Preparation of antibacterial masterbatch The following materials were selected: 40 parts by weight of dodecyl dimethyl benzyl quaternary ammonium salt and 10 parts by weight of polyhexamethylene biguanide hydrochloride; the concentration of chitosan aqueous solution was 1 wt%, and the ratio of sodium tripolyphosphate to chitosan was 1:4; the wall material accounted for 20% of the total mass of the microcapsules; the amount of fluorosilane coupling agent added was 1%; the mass ratio of fluorosilane-modified composite antibacterial microcapsules to polyethylene chips was 1:6; the process parameters for iontophoresis, fluorosilane modification, freeze drying, and granulation were the same as in Example 1.

[0035] (2) Fiber and post-processing The mass per unit area of ​​the fiber web has been adjusted to 25 g / m. 2 The hot air bonding temperature is 140℃, and the remaining spinning, corona treatment, and slitting processes are consistent with those in Example 1.

[0036] (3) Performance testing After 50 washes with AATCC 61-2A water, the antibacterial rate of the three target bacterial strains was ≥93%, and the finished product had a fluffiness of 26cm. 3 / g, analyzed from the group without antibiotics after soaking in physiological saline.

[0037] The control group and experimental group had the same experimental conditions. Based on the basic formula of Example 1, only one variable was adjusted in each group, while the rest of the formula, process and testing standards were completely unified; the testing standards were: AATCC 61-2A 50 water washes, GB / T 20944.3 antibacterial test, fluffiness test and 24h physiological saline antibacterial release test.

[0038]

[0039] Comparative experimental conclusions The comparison between the above embodiments and comparative examples shows that, by using only the complete technical solution of this invention (chitosan-sodium tripolyphosphate dual antibacterial microcapsules + fluorosilane covalent surface modification + microcapsule confined cortex loading + online corona activation), the antibacterial rate of ≥90% after 50 water washes, no antibacterial component analysis, and a fluffiness of ≥25cm can be simultaneously achieved. 3 / g These three rigid indicators; any replacement, deletion, or change of the load position of any single technical feature will result in at least one defect: significant reduction in antibacterial performance, antibacterial release, or a stiff feel. Different values ​​within the parameter range of the technical solution disclosed in this invention (such as ES fiber fineness, length, core-sheath mass ratio, nonwoven fabric surface density, hot air velocity, corona linear velocity, quaternary ammonium salt type, etc.) only affect physical indicators and do not affect the long-lasting antibacterial effect.

[0040] Example 3 This embodiment describes the preparation method of hot-air nonwoven fabric with long-lasting antibacterial function (see [link]). Figure 3 ), including the following steps: Preparation of S1 fluorosilane-modified composite antibacterial microcapsules and antibacterial masterbatch for skin layer: Prepare 0.5-10 wt% chitosan aqueous solution, mix sodium tripolyphosphate: chitosan = 1:(4-6), add two antibacterial components, react at 40℃, pH=5, and constant temperature for 30 min to obtain microcapsule suspension; add 1%-3% fluorosilane coupling agent, modify at 60℃ for 2 h; centrifuge, wash with ethanol, and freeze dry at ≤-40℃; blend fluorosilane-modified composite antibacterial microcapsules with polyethylene chips at a ratio of 1:(5-9), and granulate by twin-screw extrusion at 185-195℃ to obtain antibacterial masterbatch for skin layer spinning only.

[0041] S2 Preparation of antibacterial ES fiber: Using the obtained antibacterial masterbatch as the sole raw material for the sheath layer and polyester chips as the raw material for the core layer, the sheath-core mass ratio is 50:50 for composite spinning. The sheath spinning temperature is 190℃ and the core spinning temperature is 280℃. After stretching, crimping and cutting, antibacterial ES fiber (2D×38mm) is obtained.

[0042] S3 Hot Air Bonding and Molding: Antibacterial ES fibers are opened, combed, and laid into a uniform fiber web. Hot air at 135-145℃ penetrates and heat-bonds the fibers at a speed of 1.0m / s. The bonding and heat preservation time is 8-12s, resulting in a semi-finished hot air nonwoven fabric.

[0043] S4 Online Corona Activation and Finishing: The semi-finished product is processed by an 8-12kW corona equipment at a linear speed of 60-80m / min to enhance the bonding between the microcapsules and polyethylene. After cooling, winding, and slitting, the antibacterial hot air nonwoven fabric is obtained.

[0044] The microcapsules of this invention are suitable for high-temperature melt processing of polyethylene. In the embodiments, the preferred chitosan to sodium tripolyphosphate mass ratio is 1:(4-6), the reaction temperature is 40℃, the pH is 5.0, and the reaction is carried out at a constant temperature for 30 minutes. This precise reaction window can form a dense (uniform and non-porous) and heat-resistant (≥200℃) complete ionogel wall material. Too high or too low pH can easily affect the quality of the wall material, affecting its density and temperature resistance. The capsules are simultaneously encapsulated with two types of antibacterial substances with different bactericidal mechanisms: long-chain alkyl dimethyl benzyl quaternary ammonium salt and polyhexamethylene biguanide hydrochloride. These substances synergistically enhance the broad-spectrum inhibitory effect on bacteria and fungi, achieving synergistic encapsulation of dual antibacterial core materials. At the same time, a low-temperature freeze-drying process is used: the microcapsules are freeze-dried at ≤-40℃ to avoid the wall material cracking and damage caused by conventional hot air drying. This ensures that the microcapsules maintain their complete structure under the conditions of granulation at 185-195℃ and skin spinning at 190℃. They can be directly melt-blended and granulated with polyethylene chips, avoiding the problem of high-temperature processing failure of ordinary commercially available microcapsules.

[0045] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A hot-air nonwoven fabric with long-lasting antibacterial function, characterized in that, A three-dimensional, fluffy skeleton is formed by interwoven ES fibers with a core-sheath structure, wherein the ES fiber sheath is polyethylene and the core layer is polyester; The ES fiber has fluorosilane coupling agent modified composite antibacterial microcapsules distributed in situ only inside and on the surface of the polyethylene skin; the fluorosilane coupling agent modified composite antibacterial microcapsules are core-shell structured microcapsules with chitosan and sodium tripolyphosphate as wall materials, long-chain alkyl dimethyl benzyl quaternary ammonium salt and polyhexamethylene biguanide hydrochloride as core materials, and are obtained by modifying the surface of the microcapsules with fluorosilane coupling agent.

2. The hot-air nonwoven fabric according to claim 1, characterized in that, The wall material is prepared by ion gelation reaction of chitosan and sodium tripolyphosphate at a mass ratio of 4-6:

1. The mass ratio of long-chain alkyl dimethyl benzyl quaternary ammonium salt to polyhexamethylene biguanide hydrochloride in the core material is 40-60:5-10. The particle size of the fluorosilane coupling agent composite antibacterial microcapsules is controlled to be 50-300 nm. The wall material accounts for 10%-30% of the total mass of the microcapsules.

3. The hot-air nonwoven fabric according to claim 1, characterized in that, The outer surface of the microcapsules is modified by grafting with a fluorosilane coupling agent, and the amount of fluorosilane coupling agent added is 1% to 3% of the solid mass of the microcapsules; The fluorosilane coupling agent composite antibacterial microcapsules are completely embedded inside the polyethylene skin to form a physical anchoring structure. The fluorosilane groups on the surface of the microcapsules undergo interfacial cross-linking with the polyethylene molecular chains to form stable chemical covalent bonds, thus constructing a dual locking system of physical anchoring and fluorosilane covalent bonding.

4. The hot-air nonwoven fabric according to claim 1, characterized in that, The long-chain alkyl dimethyl benzyl quaternary ammonium salt is selected from at least one of dodecyl dimethyl benzyl quaternary ammonium salt and hexadecyl dimethyl benzyl quaternary ammonium salt.

5. The hot-air nonwoven fabric according to claim 1, characterized in that, The ES fiber has a fineness of 1.5-3D, a fiber length of 38mm, and a mass ratio of polyethylene in the outer layer to polyester in the core layer of 50:

50.

6. A method for preparing a hot-air nonwoven fabric with long-lasting antibacterial function as described in any one of claims 1 to 5, characterized in that, It includes the following steps: a) Preparation of fluorosilane-modified composite antibacterial microcapsules and antibacterial masterbatch for skin layer: Prepare an aqueous solution of chitosan with a concentration of 0.5-10 wt%, and mix it with sodium tripolyphosphate at a mass ratio of 1:(4-6) to obtain a chitosan-sodium tripolyphosphate reaction solution; add long-chain alkyl dimethyl benzyl quaternary ammonium salt and polyhexamethylene biguanide hydrochloride into the chitosan-sodium tripolyphosphate reaction solution, and perform ion gelation reaction at a constant temperature of 30-50℃ and pH=4-6 for 25-35 min to obtain a core-shell microcapsule suspension with dual antibacterial components; add 1%-3% of fluorosilane coupling agent by weight of microcapsule solids to the suspension, and stir at 50-70℃ to complete the surface grafting modification; Fluorosilane-modified composite antibacterial microcapsules were obtained by centrifugation, washing with ethanol, and low-temperature freeze-drying. Fluorosilane-modified composite antibacterial microcapsules and polyethylene chips were melt-blended in a mass ratio of 1:(5-9) using a twin-screw extruder and extruded and granulated at 185-195℃ to obtain an antibacterial masterbatch for use only in skin spinning. b) Spinning of antibacterial ES fiber with sheath and core: Antibacterial ES fiber is prepared using the antibacterial masterbatch obtained in step a) as the sole raw material for the sheath and polyester chips as the raw material for the core. c) Hot air bonding molding: Antibacterial ES fibers are opened, combed and laid into a uniform fiber web, and hot air at 135-145℃ penetrates and heat-bonds them to obtain a hot air nonwoven fabric semi-finished product. d) Finishing after online corona activation: The semi-finished hot air nonwoven fabric is continuously surface activated by an 8-12kW corona equipment at a linear speed of 60-80m / min to enhance the interfacial bonding force between the microcapsules and polyethylene. After cooling, winding, and slitting, the long-lasting antibacterial hot air nonwoven fabric is obtained.

7. The preparation method according to claim 6, characterized in that, In step a), the ion gelation reaction is carried out at a constant temperature of 40±0.5℃ and pH=5±0.5 for 30 min, and the freeze-drying temperature is ≤-40℃; in step b), the sheath-core mass ratio is 50:50 for composite spinning, the sheath spinning temperature is 190℃ and the core spinning temperature is 280℃. In step c), the hot air bonding velocity is 0.8–1.2 m / s, and the bonding and heat preservation time is 8–12 s.

8. The preparation method according to claim 6, characterized in that, The hot-air nonwoven fabric, after being washed 50 times according to AATCC 61-2A standard, exhibits an antibacterial rate of ≥90% against Escherichia coli, Staphylococcus aureus, and Candida albicans; no antibacterial activity is released after soaking in sterile physiological saline for 24 hours, indicating it is a non-release contact bactericidal material; the unit area mass of the hot-air nonwoven fabric is 20-35 g / m². 2 Loftiness ≥ 25cm 3 / g.

9. A hot-air nonwoven fabric product, characterized in that, The article is made using the hot-air nonwoven fabric with long-lasting antibacterial function as described in any one of claims 1-5, or by the preparation method described in any one of claims 6-7.

10. The article of claim 9, characterized in that, The products are medical dressings, maternal and infant hygiene materials, and disposable wiping cloths.

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