Graphene composite antibacterial non-woven fabric and preparation method thereof

Abstract

The application discloses a graphene composite antibacterial non-woven fabric and a preparation method thereof, and belongs to the technical field of non-woven fabric preparation. The non-woven fabric is prepared from one or both of polypropylene and polylactic acid as a base material, and is composed of 70-90 parts of the base material, 0.5-3 parts of modified graphene, 1-5 parts of an environment-friendly antibacterial agent, 2-6 parts of a compatilizer and 1-4 parts of an auxiliary agent according to mass fraction; the modified graphene is prepared by improved Hummers method, reduced by ascorbic acid and modified by KH-550; the non-woven fabric has a three-layer gradient antibacterial structure, and the modified graphene and the environment-friendly antibacterial agent in the middle antibacterial layer are added in an amount of 0.5-1 mass part higher than that in the surface layer and the bottom layer. The application further provides two preparation methods of melt spinning and melt blowing, which are suitable for existing equipment without modification, can produce the product with uniform dispersion of graphene, firm combination of the graphene and the base material, excellent long-acting antibacterial property, good mechanical and air permeability, can be mass-produced and are suitable for high-end fields such as medical health and infant care.

Description

Technical Field

[0001] This invention relates to the field of nonwoven fabric preparation technology, and in particular to a graphene composite antibacterial nonwoven fabric and its preparation method. Background Technology

[0002] Nonwoven fabrics are widely used in medical and health, home care, industrial filtration, food packaging and other fields due to their advantages such as lightweight, breathability, easy processing and controllable cost. Among them, antibacterial properties have become the core upgrade direction of nonwoven fabrics in the downstream market. In particular, the medical and health and infant care fields have put forward higher requirements for the antibacterial long-term effect, safety, breathability and mechanical properties of nonwoven fabrics.

[0003] Graphene, as a novel two-dimensional carbon nanomaterial, possesses excellent mechanical, antibacterial, biocompatibility, and chemical stability properties. Its antibacterial mechanism includes mechanical damage, oxidative stress, and phospholipid extraction, resulting in highly efficient antibacterial activity without the risk of developing drug resistance. Compared to traditional silver-based and quaternary ammonium salt antibacterial agents, it offers advantages such as no residue, environmental friendliness, and long-lasting stability, making it a preferred material for modifying functional nonwoven fabrics. Graphene combined with silver ions can achieve synergistic antibacterial effects, further enhancing the overall efficacy. Graphene-composite antibacterial nonwoven fabrics have become a hot research topic in the industry.

[0004] However, existing graphene composite antibacterial nonwoven fabric preparation technologies face several bottlenecks: First, graphene has poor dispersibility, and in the spinning composite method, graphene easily agglomerates, leading to uneven antibacterial effects. In the surface coating method, graphene has weak adhesion to the substrate, is easily detached, has poor long-term antibacterial effect, and its effectiveness diminishes significantly after washing. Second, graphene has poor compatibility with mainstream substrates such as polypropylene and polylactic acid, easily clogging the spinneret and affecting production continuity, and the nonwoven fabric has insufficient mechanical properties. Third, the antibacterial system is singular, and traditional silver-based antibacterial agents have heavy metal residues and oxidation issues. The problems include: discoloration issues, the tendency of quaternary ammonium salt antibacterial agents to develop resistance, making them unsuitable for high-end applications; low adaptability of preparation processes, such as electrospinning and modification with complex silane coupling agents, resulting in low yields and high costs, requiring significant modifications to existing equipment and hindering large-scale production; poor functional compatibility, with upgrades to antibacterial functions often leading to a decrease in air permeability, failing to balance practicality; the use of toxic reducing agents and heavy metal antibacterial agents in some technologies, posing environmental and safety hazards; and high raw material costs, low process efficiency, and insufficient economic viability for mass production.

[0005] In existing technologies, the preparation of graphene composite antibacterial nonwoven fabrics mainly falls into two categories: spinning composite method and surface coating method. Other methods include graphene-loaded silver ions and modification with traditional antibacterial agents, but all suffer from the aforementioned drawbacks. For example, the surface coating method is simple, but graphene is prone to detachment and has poor air permeability; the spinning composite method offers excellent long-lasting antibacterial effects, but graphene is prone to agglomeration and equipment modification costs are high; graphene-loaded silver ion technology provides good synergistic antibacterial effects, but the process is complex and silver ions are easily oxidized; traditional silver-based and quaternary ammonium salt antibacterial agent modification schemes are difficult to meet high-end safety and environmental protection requirements. Furthermore, existing graphene dispersion and composite molding technologies are mostly suitable for nylon and polyester substrates, with insufficient compatibility with polypropylene and polylactic acid substrates, and do not balance antibacterial and air permeability properties.

[0006] Therefore, developing a graphene composite antibacterial nonwoven fabric that is compatible with existing production equipment, has uniform graphene dispersion, long-lasting antibacterial safety, balances mechanical and breathability properties, and can be mass-produced, as well as its preparation method, has become an urgent problem to be solved in the industry. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a graphene composite antibacterial nonwoven fabric and its preparation method, thereby solving problems such as uneven graphene dispersion, weak bonding with the substrate, poor long-term antibacterial effect, and low process adaptability. The resulting product has both high-efficiency antibacterial properties and excellent mechanical and breathable properties. The process is compatible with existing equipment, safe and environmentally friendly, and cost-controllable, enabling large-scale mass production and meeting the application needs of high-end fields.

[0008] The technical solution adopted by this invention to solve its technical problem is: a graphene composite antibacterial nonwoven fabric, using one or two of polypropylene and polylactic acid as the base material, and composed of the following components by mass: 70-90 parts of base material, 0.5-3 parts of modified graphene, 1-5 parts of environmentally friendly antibacterial agent, 2-6 parts of compatibilizer, and 1-4 parts of auxiliary agent; wherein the modified graphene is graphene oxide prepared by the modified Hummers method, which is subsequently reduced by ascorbic acid and coupled with a silane coupling agent. The modified graphene, prepared by KH-550 modification, has a sheet diameter of 5–10 μm and a thickness of 8–15 nm. This modified graphene exhibits excellent dispersibility and good compatibility with the substrate, effectively preventing agglomeration. Its dispersion stability is improved by more than 60% compared to unmodified graphene. The nonwoven fabric has a three-layer gradient antibacterial structure, including a surface layer, a middle antibacterial layer, and a bottom layer. All three layers are prepared from the same components, with the middle antibacterial layer containing 0.5–1 part by weight more modified graphene and environmentally friendly antibacterial agent than the surface and bottom layers. The surface and bottom layers have a looser fiber arrangement, ensuring the nonwoven fabric's breathability and surface softness, while the middle antibacterial layer has a denser fiber arrangement, enhancing the antibacterial effect and longevity, thus achieving a balance between antibacterial performance and breathability / softness.

[0009] Preferably, the melt index of polypropylene in the substrate is 10-30 g / 10 min, and the melting point of polylactic acid is 150-170 °C. When the substrate is a composite of polypropylene and polylactic acid, the mass ratio of the two is 1:1. Both are commonly used raw materials for nonwoven fabric production, are easy to obtain, have controllable costs, and are suitable for melt spinning and meltblown processes.

[0010] Preferably, the environmentally friendly antibacterial agent is at least one of tea polyphenols and honeysuckle extract, or a chitosan quaternary ammonium salt with a molecular weight of 50,000 to 100,000. It has no heavy metal residue, is non-irritating, and forms a synergistic antibacterial system with graphene, thus broadening the antibacterial range. Among them, the chitosan quaternary ammonium salt has high antibacterial activity and good compatibility with the substrate, which can avoid the oxidation and discoloration problem of traditional silver-based antibacterial agents.

[0011] Preferably, the compatibilizer is polypropylene grafted with maleic anhydride or polylactic acid grafted with maleic anhydride, with a grafting rate of 0.5-2%, which can effectively improve the compatibility of graphene, antibacterial agent and substrate, promote uniform dispersion of each component, avoid delamination and agglomeration during spinning, and ensure the mechanical properties of nonwoven fabric.

[0012] Preferably, the auxiliary agent is composed of the following components by mass: 0.3-1 parts antioxidant, 0.5-2 parts dispersant, and 0.2-1 parts antistatic agent; the antioxidant is antioxidant 1010, which can prevent the substrate from degrading during spinning; the dispersant is zinc stearate, which can improve the dispersion uniformity of each component; the antistatic agent is polyethylene glycol type antistatic agent, which is suitable for medical and health applications. The above auxiliary agents are all commonly used raw materials in nonwoven fabric production.

[0013] Preferably, the performance indicators of the nonwoven fabric are: fiber diameter 1-10 μm, porosity 40-60%, thickness 0.1-3.0 mm, density 0.2-0.5 g / cm³, tensile strength 2.5 cN / dtex, elongation at break 20%, air permeability 100 mm / s, and an antibacterial rate of 95% against common pathogens after 50 washes, which meets the test standard of GB / T20944.3.

[0014] This invention also provides a method for preparing modified graphene in the above-mentioned graphene composite antibacterial nonwoven fabric, comprising the following steps: S1. Preparation of graphene oxide: Graphite powder, sodium nitrate, and potassium permanganate are mixed in a mass ratio of 1:0.5:3. 98% concentrated sulfuric acid is added, and the mixture is stirred and reacted at 0-5℃ for 2-3 hours. The temperature is then raised to 35-40℃ and the mixture is stirred and reacted for another 1-2 hours. Deionized water is slowly added, and the temperature is raised to 90-95℃ and the mixture is stirred and reacted for 0.5-1 hours. 30% hydrogen peroxide is added to terminate the reaction. After centrifugation and washing until the pH value is 6-7, the mixture is dried at 60-80℃ for 12-16 hours to obtain graphene oxide powder. This process has low pollution, high yield, and is suitable for large-scale production. S2. Reduction and Modification: Graphene oxide powder is dispersed in deionized water to prepare a suspension of 0.5-2 mg / mL. Ascorbic acid with a mass of 1-2 times that of graphene oxide is added, and the mixture is stirred and reduced at 80-90℃ for 2-3 hours. Then, 5-10% of the graphene mass of silane coupling agent KH-550 is added, and the mixture is ultrasonically dispersed at 60-70℃ and 300-500W for 1-2 hours. After centrifugation and drying at 70-80℃ for 8-10 hours, the modified graphene product is obtained.

[0015] This preparation method uses ascorbic acid as a non-toxic reducing agent to replace traditional toxic reducing agents, making the production process safe and environmentally friendly. At the same time, it combines silane coupling agent modification and ultrasonic dispersion process to completely solve the graphene agglomeration problem and improve its compatibility with the substrate.

[0016] This invention also provides a melt spinning preparation method for the above-mentioned graphene composite antibacterial nonwoven fabric, which is applicable to spunbond nonwoven fabrics, compatible with existing melt spinning and spunbond equipment, and requires no major modifications. The method includes the following steps: S1. Raw material mixing and drying: Weigh each component according to the mass fraction, add it to a high-speed mixer, mix for 15-25 minutes at 80-100℃ and 300-500r / min, and then dry at 100-120℃ for 4-6 hours to remove the moisture from the raw materials and avoid the generation of air bubbles during the spinning process, which would affect fiber forming and product quality. S2. Preparation of spinning masterbatch: The dried mixed raw materials are added to a twin-screw extruder. The extrusion temperature of polypropylene substrate is 170-200℃, and the extrusion temperature of polylactic acid substrate is 160-190℃. The screw speed is 100-150 r / min. After extrusion, the particles are cut into 2-3 mm particles. The particles are dried at 80-100℃ for 2-4 h to obtain spinning masterbatch. Optimizing the screw speed and extrusion temperature can avoid the degradation of raw materials. S3. Melt spinning: The spinning masterbatch is added to the melt spinning machine. The spinning temperature of the polypropylene substrate is 180-210℃, and the spinning temperature of the polylactic acid substrate is 170-200℃. The masterbatch is extruded through a spinneret with a micropore diameter of 0.2-0.5mm and an aspect ratio of 4:1. The spinning speed is 4200-4800m / min to obtain graphene composite antibacterial fiber with a diameter of 2-10m. Optimization of spinneret parameters can avoid clogging of the spinneret orifices during the spinning process. S4. Combing and Web Laying: The composite antibacterial fiber is combed at 40-50℃ and 10-20m / min to remove impurities and comb into single fibers. Then, it is laid in a cross-laying pattern at a speed of 30-45m / min to obtain a fiber web. Cross-laying ensures that the fiber web is uniform and the thickness can be controlled between 0.2 and 3.0mm. S5. Hot pressing: The fiber web is hot pressed at 120-150℃ and 0.3-0.6MPa for 10-20s to obtain a preliminary nonwoven fabric. Optimizing the hot pressing parameters can avoid excessive melting of the fibers, which would reduce the air permeability. S6. Finishing: Cool the pre-formed nonwoven fabric to room temperature, set it at 100-120℃ for 5-10 minutes, cut and inspect to obtain the finished product. The inspection standards comply with GB / T2423.17-2008 (antibacterial properties) and GB / T3923.1-2013 (mechanical properties).

[0017] This invention also provides a meltblown preparation method for the above-mentioned graphene composite antibacterial nonwoven fabric, applicable to meltblown nonwoven fabrics, and directly adaptable to existing meltblown equipment, including the following steps: S1. Raw material mixing and drying: Follow step S1 of the melt spinning preparation method described above to ensure that all components are mixed evenly and that moisture is completely removed. S2. Preparation of meltblown spinning solution: The dried mixed raw materials are added to the meltblown extruder and melted and plasticized at 180-220℃ and 80-120r / min. The solution is then quantitatively delivered to the meltblown die by a metering pump at 5-10r / min to obtain the meltblown spinning solution. The metering pump can accurately control the flow rate of the spinning solution to ensure spinning stability. S3. Meltblown molding: The meltblown spinning solution is extruded through a meltblown die head at a temperature of 200-230℃, a hot air temperature of 220-250℃, a hot air speed of 300-500m / min, a spinneret micropore diameter of 0.1-0.3mm, and a receiving distance of 10-20cm to obtain a meltblown graphene composite antibacterial nonwoven fabric with a fiber diameter of 1-5m and a porosity of 50-60%, which improves antibacterial and filtration performance and is suitable for medical mask inner layers, filter materials, and other applications. S4. Finishing: Cool the meltblown nonwoven fabric to room temperature, set it at 90-110℃ for 3-5 minutes, and optionally electret it with 30-50kV voltage for 1-2 seconds to improve its filtration performance. After cutting and inspection, the finished product is obtained, which is suitable for the production needs of medical meltblown fabric.

[0018] Compared with the prior art, the present invention has the following significant advantages: 1. Uniform graphene dispersion and excellent long-lasting antibacterial properties: Graphene oxide is prepared using a modified Hummers method, combined with non-toxic ascorbic acid reduction and modification with silane coupling agent KH-550, and a 300-500W ultrasonic dispersion process. This completely solves the graphene agglomeration problem, achieving uniform dispersion of graphene in the substrate and improving dispersion stability by more than 60%. Simultaneously, a synergistic antibacterial system of graphene and environmentally friendly antibacterial agents is constructed, broadening the antibacterial range. It achieves a 99% antibacterial rate against common pathogens such as Escherichia coli and Staphylococcus aureus, and retains 95% antibacterial rate after 50 water washes, far exceeding existing technologies. This meets the durability requirements of high-end products and is suitable for medical and health, infant care, and other scenarios.

[0019] 2. Good component compatibility and stable mechanical properties: Adding polypropylene grafted with maleic anhydride or polylactic acid grafted with maleic anhydride at a grafting rate of 0.5-2% precisely improves the compatibility between graphene, antibacterial agent and substrate, avoids clogging of spinneret orifices during spinning, and improves production continuity; the prepared nonwoven fabric has a breaking strength of 2.5 cN / dtex and a breaking elongation of 20%, and its mechanical properties are superior to existing graphene composite antibacterial nonwoven fabrics. At the same time, it avoids fiber damage and delamination problems, and is suitable for the production and subsequent processing needs of thin and thick nonwoven fabrics.

[0020] 3. Strong process adaptability and good scalability for mass production: Both melt spinning and meltblown preparation methods are compatible with existing melt spinning, meltblown and spunbond equipment. No major equipment modifications are required. Production can be achieved simply by optimizing process parameters. The process steps are simple and controllable, with high production efficiency and a product yield rate of over 98%, completely solving the technical problem of difficult mass production of existing high-end graphene composite antibacterial nonwoven fabrics.

[0021] 4. Safe and environmentally friendly with excellent functional compatibility: Ascorbic acid is selected as a non-toxic reducing agent, combined with environmentally friendly antibacterial agents such as tea polyphenols, honeysuckle extract, and chitosan quaternary ammonium salt. There are no heavy metal residues or toxic substances released, and no pollutants are generated during the production process, which meets environmental protection policies and safety standards for medical and health-grade products. The three-layer gradient antibacterial structure design balances antibacterial effect and breathability. The non-woven fabric has an air permeability of 100mm / s, which is soft and comfortable. It can meet the application scenarios with strict requirements for breathability, such as medical masks and protective clothing, and achieve a synergistic balance of antibacterial, breathable and soft performance.

[0022] 5. Controllable costs and significant cost-performance advantages: Using commonly used raw materials in nonwoven fabric production, optimizing the raw material ratio, avoiding the use of high-priced raw materials such as graphene quantum dots and complex silane coupling agents, reducing raw material procurement costs; simplifying process steps, improving production efficiency, reducing production losses, and reducing the overall production cost by more than 20% compared with existing high-end graphene composite antibacterial nonwoven fabrics, greatly improving the product's cost-performance and helping to seize the high-end nonwoven fabric market.

[0023] 6. Wide product adaptability and high flexibility: Compatible with polypropylene, polylactic acid and composite substrates of the two, the substrate type, the amount of graphene and environmentally friendly antibacterial agent added, the product thickness and size can be flexibly adjusted according to the differentiated needs of downstream customers. It is compatible with two mainstream processes, spunbond and meltblown, and can produce both thin medical meltblown fabric and thick home care spunbond fabric. It can be widely used in medical masks, medical protective clothing, baby diapers, home care products, food packaging and other scenarios, thus broadening the application range of products.

[0024] 7. Strong industrialization feasibility: The raw materials, processes, and equipment of this invention are all compatible with the production conditions of existing nonwoven fabric manufacturers. They can directly utilize the existing raw material procurement channels, production equipment, and technical experience of enterprises to quickly achieve industrialization without large-scale equipment investment and technological transformation. This significantly shortens the R&D and mass production cycle, while also extending the enterprise's functional nonwoven fabric product line and enhancing its core market competitiveness. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the layered structure of the graphene composite antibacterial nonwoven fabric of the present invention.

[0026] In the diagram: 1. Surface layer; 2. Middle antibacterial layer; 3. Bottom layer; 4. Modified graphene particles; 5. Environmentally friendly antibacterial agent particles; 6. Substrate fiber. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] All raw materials used in the embodiments of this invention are conventional commercially available raw materials, and all equipment used are conventional mass production equipment in the field of nonwoven fabric production. Unless otherwise specified, all are existing technologies. The common pathogenic bacteria mentioned in the embodiments mainly refer to Escherichia coli and Staphylococcus aureus. Some embodiments also include Candida albicans. The antibacterial rate test meets the GB / T20944.3 test standard.

[0029] Example 1 (Polypropylene substrate (melt-spun) graphene composite antibacterial spunbond nonwoven fabric): Raw material ratio (by mass parts): 82 parts polypropylene (melt index 20g / 10min), 1.5 parts modified graphene, 3 parts chitosan quaternary ammonium salt (molecular weight 80000), 4 parts polypropylene grafted maleic anhydride (grafting rate 1%), 0.6 parts antioxidant 1010, 1.2 parts zinc stearate, and 0.7 parts polyethylene glycol antistatic agent; the modified graphene sheets have a diameter of 7-9 μm and a thickness of 10-12 nm, and are prepared by the modified Hummers method, ascorbic acid reduction, and modification with silane coupling agent KH-550.

[0030] Preparation steps: The melt spinning method is used for preparation. The specific process parameters are as follows: S1. Raw material mixing and drying: Mix at 90℃ and 400r / min for 20min, then dry at 110℃ for 5h; S2. Preparation of spinning masterbatch: extrusion temperature 185~195℃, screw speed 120r / min, pellet size 2.5mm2.5mm, drying at 85℃ for 3h; S3. Melt spinning: spinning temperature 195~205℃, spinneret micro-orifice diameter 0.3mm, spinning speed 4500m / min, composite antibacterial fiber diameter 5~8m; S4. Carding and web laying: Carding at 45℃ and 15m / min, 40 cross-laying, web laying speed 12m / min, fiber web thickness 1.5mm; S5, Hot pressing: Hot pressing at 135℃ and 0.4MPa for 15s; S6. Finishing: After cooling to room temperature, set at 110℃ for 8 minutes, cut into 1.6m wide strips, and obtain the finished product after passing inspection.

[0031] Application Results: This product is compatible with existing spunbond production lines, ensuring good production continuity, eliminating spinneret clogging, and achieving a product yield of 98.5%. The finished nonwoven fabric has a thickness of 1.5mm, a density of 0.35g / cm³, a tensile strength of 2.8cN / dtex, a breaking elongation of 23%, and an air permeability of 120mm / s, providing softness and comfort. It exhibits an antibacterial rate of 99.3% against Escherichia coli and Staphylococcus aureus, reaching 95.2% after 50 washes. It contains no heavy metal residues and meets the GB / T20944.3-2008 standard. Suitable for use in household care products (such as wet wipes and cloths) and as the inner layer of general medical protective equipment, this product reduces production costs by 22% compared to existing similar products, demonstrating a significant cost-performance advantage.

[0032] Example 2 (Polylactic acid substrate (meltblown) graphene composite antibacterial meltblown nonwoven fabric): Raw material ratio (by mass parts): 78 parts polylactic acid (melting point 160℃), 2 parts modified graphene, 4 parts tea polyphenol antibacterial agent, 5 parts polylactic acid grafted maleic anhydride (grafting rate 1.5%), 0.8 parts antioxidant 1010, 1.5 parts zinc stearate, and 0.7 parts polyethylene glycol antistatic agent; the modified graphene sheet has a diameter of 5-7 μm and a thickness of 8-10 nm, and is prepared by the modified Hummers method, ascorbic acid reduction, and modification with silane coupling agent KH-550.

[0033] Preparation steps: The melt-blown method is used, and the specific process parameters are as follows: S1. Raw material mixing and drying: Mix at 85℃ and 350r / min for 22min, then dry at 105℃ for 4.5h; S2. Preparation of meltblown spinning solution: Extrusion temperature 185~195℃, screw speed 100r / min, metering pump speed 8r / min; S3. Meltblown molding: meltblown die head temperature 210~220℃, hot air temperature 230~240℃, hot air speed 400m / min, spinneret micro-orifice diameter 0.2mm, receiving distance 15cm, meltblown nonwoven fabric fiber diameter 2~4m, porosity 55%; S4. Finishing: After cooling to room temperature, set at 100℃ for 4 minutes, then electrostatically electret at 35kV for 1.5 seconds, cut into 1.2m wide strips, and obtain the finished product after passing inspection.

[0034] Application Results: This product is compatible with existing meltblown production lines, exhibiting good production stability and a product yield rate of 98.2%. The finished nonwoven fabric has a thickness of 0.3mm, a density of 0.25g / cm³, a tensile strength of 2.6cN / dtex, a tensile elongation at break of 21%, an air permeability of 150mm / s, and a filtration efficiency of 95% for 0.3μm particles. It demonstrates an antibacterial rate of 99.5% against Escherichia coli, Staphylococcus aureus, and Candida albicans, achieving an antibacterial rate of 96.1% after 50 washes. It is non-irritating, residue-free, and meets medical-grade product standards. Suitable for the inner layer of medical masks and medical protective clothing, it can completely replace traditional silver-based antibacterial meltblown fabric, effectively avoiding oxidation and discoloration problems, and possesses strong market competitiveness.

[0035] Example 3 (Polypropylene-polylactic acid composite substrate (melt spinning) graphene composite antibacterial nonwoven fabric): Raw material ratio (by mass parts): 40 parts polypropylene (melt index 15g / 10min), 40 parts polylactic acid (melting point 155℃), 1 part modified graphene, 2 parts honeysuckle extract antibacterial agent, 3 parts polypropylene grafted maleic anhydride, 0.5 parts antioxidant 1010, 1 part zinc stearate, 0.5 parts polyethylene glycol antistatic agent; the modified graphene sheet has a diameter of 8-10 μm and a thickness of 12-15 nm, and is prepared by the modified Hummers method, ascorbic acid reduction, and modification with silane coupling agent KH-550.

[0036] Preparation steps: The above-described melt spinning method is used for preparation, with the specific process parameters as follows: S1. Raw material mixing and drying: Mix at 88℃ and 380r / min for 18min, then dry at 115℃ for 4h; S2. Preparation of spinning masterbatch: extrusion temperature 175~185℃, screw speed 110r / min, pellet size 2mm2mm, drying at 80℃ for 3.5h; S3. Melt spinning: spinning temperature 185~195℃, spinneret micro-orifice diameter 0.4mm, spinning speed 4300m / min, composite antibacterial fiber diameter 3~6m; S4. Carding and web laying: Carding at 42℃ and 13m / min, cross-laying at 35°C, web laying speed of 10m / min, and web thickness of 0.8mm. S5, Hot pressing: 125℃, 0.35MPa hot pressing for 12s; S6. Finishing: After cooling to room temperature, set at 105℃ for 6 minutes, cut into 2.4m wide strips, and obtain the finished product after passing inspection.

[0037] Application Results: This product is compatible with existing spinning production lines, combining the toughness of polypropylene with the environmental friendliness of polylactic acid. It offers good production continuity and a product yield of 98.7%. The finished nonwoven fabric has a thickness of 0.8mm, a density of 0.3g / cm³, a tensile strength of 2.7cN / dtex, a breaking elongation of 22%, and an air permeability of 130mm / s. Its biodegradability is superior to pure polypropylene-based nonwoven fabrics. It exhibits an antibacterial rate of 99.1% against Escherichia coli and Staphylococcus aureus, reaching 95.5% after 50 washes, and is environmentally friendly with no residue. Suitable for food packaging and infant care products (such as diaper surfaces), this product broadens the environmentally friendly application scenarios of graphene composite antibacterial nonwoven fabrics, aligning with the industry's green development trend.

[0038] The above embodiments are only used to explain the present invention and are not intended to limit the protection of the present invention. Any non-substantial modifications made based on the essential solution of the present invention should fall within the protection scope of the present invention.

Claims

1. A graphene composite antibacterial nonwoven fabric, characterized in that: It uses one or two of polypropylene and polylactic acid as the base material, and is composed of the following components by mass parts: 70-90 parts of base material, 0.5-3 parts of modified graphene, 1-5 parts of environmentally friendly antibacterial agent, 2-6 parts of compatibilizer, and 1-4 parts of auxiliary agent. The modified graphene is graphene oxide prepared by the modified Hummers method, which is then successively reduced by ascorbic acid and modified by silane coupling agent KH-550. Its sheet diameter is 5-10 μm and its thickness is 8-15 nm. The nonwoven fabric has a three-layer gradient antibacterial structure, including a surface layer, a middle antibacterial layer and a bottom layer. The three layers are prepared from the same components, and the amount of modified graphene and environmentally friendly antibacterial agent added in the middle antibacterial layer is 0.5 to 1 part by mass higher than that in the surface layer and the bottom layer.

2. The graphene composite antibacterial nonwoven fabric according to claim 1, characterized in that: The melt index of polypropylene in the substrate is 10-30 g / 10 min, and the melting point of polylactic acid is 150-170 °C; when the substrate is a composite of polypropylene and polylactic acid, the mass ratio of the two is 1:

1.

3. The graphene composite antibacterial nonwoven fabric according to claim 1, characterized in that: The environmentally friendly antibacterial agent is at least one of tea polyphenols and honeysuckle extract, or a chitosan quaternary ammonium salt with a molecular weight of 50,000 to 100,000; the compatibilizer is polypropylene grafted with maleic anhydride or polylactic acid grafted with maleic anhydride, with a grafting rate of 0.5% to 2%.

4. The graphene composite antibacterial nonwoven fabric according to claim 1, characterized in that, The auxiliary agent is composed of the following components by mass: 0.3-1 parts antioxidant, 0.5-2 parts dispersant, and 0.2-1 parts antistatic agent; wherein the antioxidant is antioxidant 1010, the dispersant is zinc stearate, and the antistatic agent is polyethylene glycol type antistatic agent.

5. The graphene composite antibacterial nonwoven fabric according to claim 1, characterized in that, The performance indicators of the nonwoven fabric are as follows: fiber diameter 1-10m, porosity 40-60%, thickness 0.1-3.0mm, density 0.2-0.5g / cm, tensile strength 2.5cN / dtex, tensile elongation at break 20%, air permeability 100mm / s, and antibacterial rate against common pathogens still 95% after 50 washes.

6. A method for preparing modified graphene in the graphene composite antibacterial nonwoven fabric according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Preparation of graphene oxide: Graphite powder, sodium nitrate, and potassium permanganate are mixed in a mass ratio of 1:0.5:

3. 98% concentrated sulfuric acid is added, and the mixture is stirred at 0-5℃ for 2-3 hours. The temperature is raised to 35-40℃ and the mixture is stirred for another 1-2 hours. Deionized water is slowly added, and the temperature is raised to 90-95℃ and the mixture is stirred for 0.5-1 hours. 30% hydrogen peroxide is added to terminate the reaction. After centrifugation and washing until the pH value is 6-7, the mixture is dried at 60-80℃ for 12-16 hours to obtain graphene oxide powder. S2. Reduction and Modification: Graphene oxide powder is dispersed in deionized water to prepare a suspension of 0.5-2 mg / mL. Ascorbic acid with a mass of 1-2 times that of graphene oxide is added, and the mixture is stirred and reduced at 80-90℃ for 2-3 hours. Then, 5-10% of the graphene mass of silane coupling agent KH-550 is added, and the mixture is ultrasonically dispersed at 60-70℃ and 300-500W for 1-2 hours. After centrifugation and drying at 70-80℃ for 8-10 hours, the modified graphene product is obtained.

7. A melt spinning method for preparing graphene composite antibacterial nonwoven fabric according to any one of claims 1 to 5, applicable to spunbond nonwoven fabric, characterized in that, Includes the following steps: S1. Raw material mixing and drying: Weigh each component according to the mass fraction, add it to a high-speed mixer, mix for 15-25 minutes at 80-100℃ and 300-500r / min, and then dry at 100-120℃ for 4-6 hours to remove the moisture from the raw materials. S2. Preparation of spinning masterbatch: The dried mixed raw materials are added to a twin-screw extruder. The extrusion temperature of polypropylene substrate is 170-200℃, the extrusion temperature of polylactic acid substrate is 160-190℃, the screw speed is 100-150 r / min, and the extruded particles are cut into 2-3 mm particles. The particles are dried at 80-100℃ for 2-4 h to obtain spinning masterbatch. S3. Melt spinning: The spinning masterbatch is added to a melt spinning machine. The spinning temperature of the polypropylene substrate is 180-210℃, and the spinning temperature of the polylactic acid substrate is 170-200℃. The masterbatch is extruded through a spinneret with a micropore diameter of 0.2-0.5mm and an aspect ratio of 4:

1. The spinning speed is 4200-4800m / min to obtain graphene composite antibacterial fiber with a diameter of 2-10m. S4. Carding and web laying: The composite antibacterial fiber is carded at 40-50℃ and 10-20m / min, and then laid in a 30-45 cross pattern at a web laying speed of 8-15m / min to obtain a fiber web. S5. Hot pressing: The fiber web is hot pressed at 120-150℃ and 0.3-0.6MPa for 10-20s to obtain a preliminary nonwoven fabric. S6. Finishing: Cool the pre-formed nonwoven fabric to room temperature, set it at 100-120℃ for 5-10 minutes, and then cut and inspect it to obtain the finished product.

8. A meltblown preparation method for graphene composite antibacterial nonwoven fabric according to any one of claims 1 to 5, applicable to meltblown nonwoven fabric, characterized in that, Includes the following steps: S1. Raw material mixing and drying: Operate according to step S1 of claim 7; S2. Preparation of meltblown spinning solution: The dried mixed raw materials are added to a meltblown extruder and melted and plasticized at 180-220℃ and 80-120r / min. The solution is then quantitatively delivered to the meltblown die by a metering pump at 5-10r / min to obtain the meltblown spinning solution. S3. Meltblown forming: The meltblown spinning solution is extruded through a meltblown die head at a temperature of 200–230°C, a hot air temperature of 220–250°C, a hot air speed of 300–500 m / min, a spinneret micro-orifice diameter of 0.1–0.3 mm, and a receiving distance of 10–20 cm to obtain a meltblown graphene composite antibacterial nonwoven fabric with a fiber diameter of 1–5 μm and a porosity of 50–60%. S4. Finishing: Cool the meltblown nonwoven fabric to room temperature, set it at 90-110℃ for 3-5 minutes, optionally electret it with 30-50kV voltage for 1-2 seconds, and then cut and inspect it to obtain the finished product.

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