Antibacterial nonwoven fabric of nanocellulose loaded with nanosilver, method of preparation and use

Abstract

The application provides an antibacterial non-woven fabric loaded with nanocellulose and nanosilver, a preparation method and an application, and relates to the technical field of non-woven fabrics. The application discloses a kind of nanocellulose load nanosilver antibacterial non-woven fabric, preparation method and use, including: in the surface of non-woven fabric, nanocellulose solution is sprayed, or non-woven fabric is soaked in nanocellulose solution;Non-woven fabric is taken out, and the surface of non-woven fabric is sprayed with nanosilver precursor solution, or it is soaked in nanosilver precursor solution;Non-woven fabric is taken out after being soaked in reduction solution, and then dried to obtain the antibacterial non-woven fabric. Simple dipping or spraying and similar coating methods are used to form negatively charged nanocellulose on the surface of non-woven fabric, and further silver ion modification is completed through electrostatic interaction. In-situ reduction of silver ions loaded on the surface of non-woven fabric effectively prevents the agglomeration of silver nanoparticles obtained by reduction, ensures the uniform distribution of silver nanoparticles on the surface of non-woven fabric, and solves the technical problems of uneven distribution and easy agglomeration of silver nanoparticles on the surface of non-woven fabric in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of antibacterial and disinfection materials technology, and relates to an antibacterial nonwoven fabric with nanocellulose loaded with nanosilver, its preparation method and uses. Background Technology

[0002] Nonwoven fabrics are characterized by low cost, fast production, and wide application, and are widely used in various fields of production and daily life. In particular, there is a significant demand for nonwoven fabrics with antibacterial properties in many fields, especially in the development of hygiene and care products. Inorganic silver, with its broad-spectrum antibacterial properties, can be used in the development of antibacterial materials. Various forms of silver inorganic materials, such as silver ions and nano-silver, have been applied in the production of antibacterial nonwoven fabrics.

[0003] CN104131457A discloses a method for preparing antibacterial nonwoven fabric. The preparation process involves first preparing an impregnation solution, then immersing the nonwoven fabric in the impregnation solution for a padding process, and finally drying to obtain the final product. The components of the impregnation solution, by weight ratio, include: 3-7 parts of nano-silver sol, 2-5 parts of acrylic acid, 0.01-0.1 parts of PEG-400, 0.01-0.1 parts of PVP, and 100 parts of water, wherein the combined components of PEG-400 and PVP are 0.1 parts. However, the impregnation solution composition is complex and only applicable to the padding process.

[0004] CN111411513A discloses an antibacterial nonwoven fabric with modified acrylic fiber as the matrix. The modified acrylic fiber is impregnated in a silver antibacterial solution. After impregnation, the fabric is placed in a water bath and shaken. It is then removed, washed, and air-dried to obtain the antibacterial nonwoven fabric with chelated silver atoms. However, the pre-preparation of the silver antibacterial solution during the process can easily lead to the aggregation of silver atoms, resulting in a decrease in the antibacterial effect.

[0005] CN116676715A discloses a silver ion physically adsorbed spunlace nonwoven fabric, its preparation method, and its application. The method involves preparing a nonwoven fabric by spunlace technology using a mixture of modified adsorbent viscose fibers (obtained through cationic modification) and conventional viscose fibers, and then spraying silver ion antibacterial agents onto the upper and lower surfaces. The modified adsorbent viscose fibers are used in a range of 5%-100%, while the conventional viscose fibers are used in a range of 0%-95%. The amount of silver ion antibacterial agent added per ton of silver ion physically adsorbed spunlace nonwoven fabric is 0.5%-2%. However, the above production process is complex, requires heating, and has high energy consumption.

[0006] Nanocellulose materials have good biocompatibility and possess a large number of hydroxyl and carboxyl groups, which can be used to modify various substrates or load functional substances. They also have advantages such as large specific surface area and high crystallinity, and have great potential application value in the fields of papermaking, cosmetics, hygiene and care product production and development, and biomedicine. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide an antibacterial nonwoven fabric loaded with nano-cellulose and nano-silver, its preparation method, and its applications. A negatively charged nano-cellulose coating is formed on the surface of the nonwoven fabric using a simple coating method such as dip-coating or spraying. The nano-cellulose material can be modified on the nonwoven fabric through various groups such as hydrogen bonds and hydroxyl groups. Subsequently, a nano-silver precursor solution is dip-coated or sprayed, and further silver ion modification is achieved through electrostatic interaction, resulting in silver ions being loaded onto the nano-cellulose coating. The silver ions loaded on the nonwoven fabric surface are then reduced in situ by immersion in a reducing solution, effectively preventing the aggregation of the reduced silver nanoparticles. This significantly improves the utilization efficiency and modification stability of the nano-silver precursor solution, ensuring that the silver nanoparticles are uniformly distributed on the nonwoven fabric surface. This solves the technical problems of uneven distribution and easy aggregation of silver nanoparticles on the nonwoven fabric surface in existing technologies.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing an antibacterial nonwoven fabric supported on nanocellulose and nanosilver, the preparation method comprising:

[0010] (I) Spray a nano-cellulose solution onto the surface of the nonwoven fabric, or immerse the nonwoven fabric in a nano-cellulose solution;

[0011] (II) Take out the nonwoven fabric obtained in step (I), spray the surface of it with nano silver precursor solution, or immerse it in nano silver precursor solution;

[0012] (III) After taking out the nonwoven fabric obtained in step (II), immerse it in a reducing solution to reduce the nano-silver precursor to silver nanoparticles; then freeze-dry or heat-dry to obtain the antibacterial nonwoven fabric.

[0013] Silver nanoparticles are nanoparticles with a large specific surface area and small particle size. They can rapidly adsorb onto the surface of bacterial cell membranes and penetrate into the bacterial cell interior. On one hand, silver nanoparticles interact with large molecular compounds containing sulfur and phosphorus (such as nucleic acids, RNA, and DNA) within bacterial cells, causing deformation of the bacterial DNA molecular structure, inhibiting bacterial self-replication, and affecting normal bacterial physiological functions (such as respiratory, digestive, and excretory functions), making it difficult for bacteria to develop resistance. On the other hand, silver nanoparticles interact with sulfhydryl groups in proteins, forming sulfates that inhibit protein synthesis, thereby reducing the activity of sulfhydryl enzymes, interfering with bacterial metabolism, and inducing bacterial death. After the bacteria are killed, the silver nanoparticles are released from the bacterial cells. These released silver nanoparticles can then bind to other bacterial cells, thus achieving sustained bactericidal effects. However, silver nanoparticles are prone to aggregation, which can affect the effective exertion of their antibacterial properties.

[0014] Nanocellulose is a natural biomass polymer with high hydrophilicity, excellent biocompatibility, and mechanical properties. This invention employs simple dipping or spraying methods to form a negatively charged nanocellulose coating on the surface of nonwoven fabric. Nanocellulose can be modified on the nonwoven fabric through various functional groups such as hydrogen bonds and hydroxyl groups. Subsequently, a nano-silver precursor solution is dipped or sprayed, further modifying the silver ions through electrostatic interactions, allowing silver ions to be loaded onto the nanocellulose coating. Immersion in a reducing solution allows for in-situ reduction of the silver ions loaded on the nonwoven fabric surface, effectively preventing the aggregation of the reduced silver nanoparticles. This significantly improves the utilization efficiency and modification stability of the nano-silver precursor solution, ensuring uniform distribution of silver nanoparticles on the nonwoven fabric surface. This solves the technical problems of uneven distribution and easy aggregation of silver nanoparticles on the nonwoven fabric surface in existing technologies, thereby effectively improving the antibacterial and bacteriostatic capabilities of the nonwoven fabric.

[0015] This invention utilizes an in-situ reduction method to reduce silver ions immobilized within the porous structure of nanocellulose into silver nanoparticles, which are then loaded onto the surface of a nonwoven fabric. Because the nanocellulose molecular chains contain numerous hydroxyl groups, they carry a large negative charge in water, exhibiting a strong adsorption effect on silver ions in silver nitrate solution. Therefore, it can serve as a matrix for loading silver ions, acting as a silver ion stabilizer. Furthermore, the three-dimensional porous network structure of nanocellulose provides abundant channels to act as a microreactor for synthesizing silver nanoparticles and inhibiting their aggregation, achieving both fixation and dispersion of the silver nanoparticles. Simultaneously, the network structure of nanocellulose effectively prevents the in-situ generated silver nanoparticles from detaching, thereby significantly enhancing the antibacterial properties of the antibacterial nonwoven fabric. This invention leverages the unique antibacterial and bactericidal properties and broad-spectrum antibacterial activity of silver nanoparticles to prepare an antibacterial nonwoven fabric with excellent antibacterial capabilities.

[0016] The carboxylic acid groups in nanocellulose combine with silver ions, allowing the silver ions to be adsorbed onto the nanocellulose structure. The resulting antibacterial composite film exhibits a low silver release rate, resulting in a sustained-release effect of the silver nanoparticles. This low release level of silver nanoparticles achieves continuous bactericidal and bacteriostatic effects without toxicity to human cells. Therefore, the antibacterial nonwoven fabric prepared by this invention allows for the attachment and growth of epidermal cells without cytotoxicity, and possesses anti-inflammatory and wound-healing properties. Furthermore, the abundant three-dimensional porous network structure of cellulose demonstrates excellent air permeability and liquid absorption capacity, providing absorption channels for wound exudates. Therefore, the antibacterial nonwoven fabric prepared using this invention not only has significant antibacterial capabilities but also promotes wound healing when used as a wound dressing, demonstrating its potential applications in wound care.

[0017] The antibacterial nonwoven fabric prepared by this invention possesses the dual properties of nanocellulose and silver nanoparticles. Through the synergistic effect and complementary advantages of the two, the antibacterial performance and applicability of the nonwoven fabric can be significantly improved. Specifically, nanocellulose can improve the aggregation phenomenon of silver nanoparticles, solving the problems of easy aggregation and poor interfacial compatibility of silver nanoparticles, maximizing the antibacterial properties of silver nanoparticles, and achieving a long-lasting and stable antibacterial capability of the antibacterial nonwoven fabric. Furthermore, nanocellulose itself has good film-forming properties, serving as a carrier for silver nanoparticles, and can form a smooth, transparent, and well-compatible antibacterial composite film on the surface of the nonwoven fabric. In addition, nanocellulose can also improve the water absorption and skin-friendliness of the nonwoven fabric. Simultaneously, the entire production process does not require the use of toxic or harmful chemical reagents, the process is simple and environmentally friendly, and suitable for large-scale industrial promotion.

[0018] As a preferred technical solution of the present invention, in step (I), the nanocellulose solution includes any one or a combination of at least two of the following: cellulose nanocrystal aqueous solution, cellulose nanofiber aqueous solution, phosphorylated nanofiber crystal aqueous solution, or phosphorylated cellulose nanofiber aqueous solution.

[0019] Nanocellulose possesses chemically active hydroxyl groups on its surface, making it easy to modify and surface-modify. Chemical modification can yield a series of modified nanocellulose, nanocellulose derivatives, and copolymers, such as phosphorylated cellulose nanofibers, phosphorylated nanofiber crystals, carboxylated cellulose nanofibers, carboxylated nanofiber crystals, carboxymethyl cellulose nanofibers, and carboxymethyl nanofiber crystals. Chemical modification can significantly improve the physical properties of nanocellulose, such as solubility, dispersibility, rheological properties, and stability. It also facilitates the formation of non-covalent or covalent nanobonded surfaces with silver nanoparticles, providing a carrier and sites for the nucleation reaction of metallic silver, allowing silver to easily nucleate and grow into silver nanoparticles on the nanocellulose surface. Furthermore, the introduction of polar functional groups such as carboxyl groups into the surface of chemically modified nanocellulose increases the negative charge content, further enhancing the electrostatic repulsion between silver nanoparticles and preventing aggregation.

[0020] The reduction reaction of silver ions on the surface of nanocellulose depends not only on the reducing solution but also on the OH groups adsorbed on the nanocellulose surface. - Related, firstly Ag + The silver nitrate solution diffuses onto the surface of the nanocellulose molecules and reacts with the OH groups enriched on the surface of the nanocellulose molecules. - The reaction produces silver oxide, which reacts with the reducing solution during stirring to gradually precipitate metallic silver. As the reduction reaction continues, the metallic silver aggregates to form silver nanoparticles.

[0021] To help those skilled in the art better and more fully realize the technical solutions provided by this invention, the present invention provides the following optional methods for modifying and preparing cellulose nanofibers:

[0022] For example, phosphorylated cellulose nanofibers can be prepared by the following method:

[0023] (1) Weigh out cellulose raw materials, phosphate and urea respectively according to the molar ratio of 1:(0.5-2):(3-7), dissolve phosphate and urea in deionized water by ultrasonication, and adjust the pH of the solution to an acidic range of 3-4.5. Among them, deionized water is weighed according to the mass ratio of cellulose raw materials to deionized water of 1:(2.5-8).

[0024] (2) The cellulose raw material is fully immersed in the phosphorylation reagent solution. The pressure of 0.1-0.4 MPa is applied by an air compressor pump to fully immerse the cellulose raw material and effectively compact it. The cellulose raw material is then subjected to a hot soaking pretreatment at 60-95℃ for 10-180 min. The cellulose raw material after hot soaking pretreatment is dried at 70-110℃ to constant weight and then further heated to 140-165℃ for curing for 10-90 min to complete the phosphorylation modification chemical reaction.

[0025] (3) After washing and purifying the phosphorylated cellulose slurry with water, it is homogenized 5-15 times under a pressure of 70-100MPa using mechanical processing equipment such as a high-pressure homogenizer to obtain high charge density phosphorylated cellulose nanofibers.

[0026] For example, carboxylated cellulose nanofibers can be prepared by the following method:

[0027] (1) A reaction solution is prepared by mixing pulp, 2,2,6,6-tetramethylpiperidine-N-oxy radical, sodium bromide and sodium hypochlorite. The concentration of pulp in the reaction solution is 10-30 g / L, the concentration of 2,2,6,6-tetramethylpiperidine-N-oxy radical is 0.2-0.4 g / L, the concentration of sodium bromide is 1-3 g / L and the concentration of sodium hypochlorite is 100-130 g / L.

[0028] (2) Adjust the pH of the reaction solution to 9-11 and carry out the oxidation reaction at 28-35℃ for 1-2 hours. After the reaction is completed, wash the reaction product to obtain carboxylated cellulose.

[0029] (3) The carboxylated cellulose is homogenized under high pressure at 200-1000 bar for 2-10 times to achieve fiber nano-sizing and obtain carboxylated nanocellulose.

[0030] For example, carboxymethyl cellulose nanofibers can be prepared by the following method:

[0031] (1) Soak the cellulose raw material in the reaction solvent, add 40-60wt% alkali solution to the raw material, and carry out the first alkalization reaction at 15-78℃ for 1-4 hours; then adjust the temperature to 20-37℃ and add 10-60wt% chloroacetic acid solution, and carry out the first etherification reaction at 60-82℃ for 1-4 hours to obtain the reaction solution;

[0032] (2) After an interval of 0.5-1 hour, add 40-60wt% alkali solution to the reaction solution and carry out a second alkalization reaction at 15-78℃ for 1-4 hours. Then adjust the temperature to 20-37℃ and add 10-60wt% chloroacetic acid solution. Carboxymethyl cellulose is then carried out a second etherification reaction at 60-82℃ for 1-4 hours.

[0033] (3) Disperse carboxymethyl cellulose in deionized water to form a 0.5-4% carboxymethyl cellulose suspension. Homogenize the carboxymethyl cellulose suspension under high pressure at 200-1000 bar 2-10 times to achieve fiber nano-sizing and obtain carboxymethyl cellulose nanofibers.

[0034] It is understood that the preparation methods of various cellulose nanofibers specified above are all optional solutions and do not constitute a further limitation on the technical solution of the present invention. Cellulose nanofibers prepared by other disclosed existing technologies or undisclosed new technologies are also used in the present invention and fall within the protection scope and disclosure scope of the present invention.

[0035] In some preferred embodiments, the mass fraction of the nanocellulose solution is 0.1-1.5 wt%, for example, it may be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, or 1.5 wt%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 0.25-0.5 wt%.

[0036] As the mass fraction of the nanocellulose solution increases, the average particle size of the generated silver nanoparticles decreases. During the reduction process of silver ions, nanocellulose plays a certain role in protecting, stabilizing, and uniformly dispersing the silver nanoparticles, inhibiting excessive aggregation and growth. When the mass fraction of the nanocellulose solution is too high, a large amount of nanocellulose will coat the surface of the reduced silver nanoparticles, resulting in an increase in the average particle size of the silver nanoparticles.

[0037] Silver nanoparticles carry a negative charge on their surface due to the -OH and -COOH functional groups in the nanocellulose coating. These functional groups ionize to form -O- and -COO-, resulting in the negative charge. When the mass fraction of the nanocellulose solution is below 0.1 wt%, the amount of nanocellulose added is small, leading to fewer ionizable hydroxyl groups on the surface of the silver nanoparticles. This results in a lower negative charge density and weaker electrostatic repulsion between the nanoparticles, ultimately causing them to become unstable and easily aggregate. When the mass fraction of the nanocellulose solution is in the range of 0.25-0.5 wt%, the silver nanoparticles loaded on the nonwoven fabric surface have suitable volume and charge properties. The surface of the silver nanoparticles has the most ionizable hydroxyl groups. The deprotonation of these hydroxyl groups increases the negative charge density on the surface of the silver nanoparticles, resulting in strong electrostatic repulsion between the nanoparticles. This leads to the most stable state and makes aggregation extremely difficult. Furthermore, within this mass fraction range, the appropriate particle size of the silver nanoparticles allows them to adsorb more nanocellulose molecules to form a protective layer, and even to form multiple nanocellulose molecular protective layers.

[0038] When the mass fraction of the nanocellulose solution is in the range of 0.5-1.5 wt%, the presence of more nanocellulose provides end-capping stabilization, resulting in smaller particle size and a greater number of silver nanoparticles. Consequently, the positive charge on the surface of the silver nanoparticles is weakened, reducing the deprotonation ability of the hydroxyl groups of the nanocellulose attached to the surface of the silver nanoparticles. Therefore, the negative charge on the surface of the silver nanoparticles is weakened, and the electrostatic repulsion between the silver nanoparticles is reduced compared to the range of 0.25-0.5 wt%.

[0039] When the mass fraction of the nanocellulose solution is below 0.25 wt%, the low nanocellulose content on the nonwoven fabric surface leads to insufficient repulsive force between silver nanoparticles, making them prone to aggregation. When the mass fraction of the nanocellulose solution further decreases to below 0.1 wt%, the nanocellulose content on the nonwoven fabric surface cannot meet the requirements for further modification of silver nanoparticles. When the mass fraction of the nanocellulose solution exceeds 1.5 wt%, the excessive nanocellulose loading on the nonwoven fabric surface creates steric hindrance, limiting the growth of silver nanoparticles. This results in excessively small particle size, small surface area, and weak surface electronegativity of the silver nanoparticles. Consequently, the surface of the silver nanoparticles has a limited capacity to accommodate nanocellulose molecules, and the negative charge density distributed on the surface of the silver nanoparticles actually decreases with increasing mass fraction of the nanocellulose solution.

[0040] As a preferred technical solution of the present invention, in step (I), the soaking time is 0.25-2h, for example, it can be 0.25h, 0.3h, 0.5h, 0.6h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h or 2.0h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 0.5-1h.

[0041] This invention specifically limits the soaking time of nonwoven fabric in nanocellulose solution to 0.25-2 hours, preferably 0.5-1 hour. Within this range, the nanocellulose in the nanocellulose solution can be effectively utilized. When the soaking time of nonwoven fabric is less than 0.5 hours, the loading of nanocellulose deposited on the surface of the nonwoven fabric is small and insufficient to limit the aggregation of silver nanoparticles. When the soaking time is further shortened to less than 0.25 hours, the loading of nanocellulose on the surface of the nonwoven fabric is small due to insufficient modification time, which is insufficient to meet the subsequent loading requirements of silver ions. When the soaking time of nonwoven fabric is greater than 1 hour, the loading efficiency of nanocellulose decreases. When the soaking time is further extended to more than 2 hours, the loading of nanocellulose on the surface of the nonwoven fabric has reached saturation, and further extending the soaking time cannot increase the loading of nanocellulose on the surface of the nonwoven fabric.

[0042] In some preferred embodiments, the spraying pressure is 0.4-0.6 MPa, for example, 0.4 MPa, 0.42 MPa, 0.44 MPa, 0.46 MPa, 0.48 MPa, 0.5 MPa, 0.52 MPa, 0.54 MPa, 0.56 MPa, 0.58 MPa or 0.6 MPa, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0043] In some preferred embodiments, the spray width on the nonwoven fabric surface is 10-20cm, for example, it can be 10cm, 11cm, 12cm, 13cm, 14cm, 15cm, 16cm, 17cm, 18cm, 19cm or 20cm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0044] In some preferred embodiments, the spray flow rate is 40-100 L / min, for example, it can be 40 L / min, 45 L / min, 50 L / min, 55 L / min, 60 L / min, 65 L / min, 70 L / min, 75 L / min, 80 L / min, 85 L / min, 90 L / min, 95 L / min or 100 L / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0045] In some preferred embodiments, the spraying time is 1-5 min, for example, it can be 1.0 min, 1.5 min, 2.0 min, 2.5 min, 3.0 min, 3.5 min, 4.0 min, 4.5 min or 5.0 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0046] As a preferred technical solution of the present invention, in step (II), the nano-silver precursor solution includes an aqueous solution of silver nitrate.

[0047] In the antibacterial nonwoven fabric prepared by this invention, silver nanoparticles exhibit good antibacterial properties, inhibiting a large number of pathogens such as bacteria, viruses, yeasts and fungi without causing drug resistance in microorganisms.

[0048] In some preferred embodiments, the mass fraction of the nano-silver precursor solution is 0.1-1.5 wt%, for example, it can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, or 1.5 wt%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 0.8-1 wt%.

[0049] After nonwoven fabric is soaked in silver nitrate solution, silver nanoparticles can enter the interior of the nanocellulose through the pores of the three-dimensional network structure and bind to the nanocellulose through electrostatic interactions. Simultaneously, because the polar hydroxyl and ether groups of nanocellulose have multi-electron oxygen atoms, they can act as active reaction centers to react with silver ions to form silver oxide. Subsequently, soaking in a reducing solution allows the silver oxide to undergo a reduction reaction, being reduced back to silver nanoparticles. Due to the three-dimensional porous network structure of nanocellulose, the nanoscale pores can act as nanoreactors for the formation and growth of silver nanoparticle nuclei, while the pore structure can strictly limit the excessive growth of silver nanoparticle nuclei.

[0050] As the mass fraction of the silver nanoparticle precursor solution increases, the antibacterial properties of the prepared antibacterial nonwoven fabric exhibit a trend of first increasing and then decreasing. This is related to the crystal formation process of silver nanoparticles, which involves crystal nucleation and growth. By controlling the balance between the nucleation rate and growth rate, the morphology and size of the crystals can be adjusted. When the growth rate is relatively high and the nucleation rate is relatively low, smaller silver nanoparticles can be generated. With increasing mass fraction of the silver nanoparticle precursor solution, the nucleation rate of the silver nanoparticles is higher while the growth rate is lower, resulting in smaller crystal particle sizes. When the mass fraction of the silver nanoparticle precursor solution is too high, the yield of silver nanoparticles is too high and the crystal size is too small. At this point, the silver nanoparticles are prone to aggregation, thus affecting the antibacterial ability of the antibacterial nonwoven fabric.

[0051] This invention specifically limits the mass fraction of the nano-silver precursor solution to 0.1-1.5 wt%, preferably 0.8-1 wt%, within which the silver nanoparticles have suitable particle size and loading. When the mass fraction of the nano-silver precursor solution is below 0.8 wt%, the loading efficiency of the silver nanoparticles decreases due to the low silver ion content in the nano-silver precursor solution; when the mass fraction of the nano-silver precursor solution is further reduced to below 0.1 wt%, the loading of silver nanoparticles on the surface of the nonwoven fabric is too low, failing to meet the antibacterial requirements of the antibacterial nonwoven fabric; when the mass fraction of the nano-silver precursor solution is above 1 wt%, the silver nanoparticle loading is excessive but the particle size is small, making aggregation easy; when the mass fraction of the nano-silver precursor solution is further increased to above 1.5 wt%, the silver nanoparticles are extremely prone to aggregation, exceeding the antibacterial requirements of the antibacterial nonwoven fabric, resulting in raw material waste.

[0052] As a preferred technical solution of the present invention, in step (II), the soaking time is 0.25-2h, for example, it can be 0.25h, 0.3h, 0.5h, 0.6h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h or 2.0h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 0.5-0.75h.

[0053] This invention specifically limits the soaking time of nonwoven fabric in the nano-silver precursor solution to 0.25-2 hours, preferably 0.5-0.75 hours. Within this range, high-efficiency loading of silver nanoparticles can be achieved. When the soaking time of the nonwoven fabric is less than 0.5 hours, the silver nanoparticles cannot be fully loaded onto the surface of the nonwoven fabric due to the short modification time. When the soaking time is further shortened to less than 0.25 hours, the loading amount of silver nanoparticles is low and cannot meet the antibacterial requirements of the antibacterial nonwoven fabric. When the soaking time of the nonwoven fabric is greater than 0.75 hours, the silver ion content in the nano-silver precursor solution decreases as the loading of silver nanoparticles proceeds, resulting in a decrease in silver ion modification efficiency and a slowdown in growth rate. When the soaking time is further extended to more than 2 hours, the silver ion content in the nano-silver precursor solution further decreases, and the loading process of silver nanoparticles basically stops. Further extending the soaking time cannot increase the loading amount of silver nanoparticles on the surface of the nonwoven fabric.

[0054] In some preferred embodiments, the spraying pressure is 0.4-0.6 MPa, for example, 0.4 MPa, 0.42 MPa, 0.44 MPa, 0.46 MPa, 0.48 MPa, 0.5 MPa, 0.52 MPa, 0.54 MPa, 0.56 MPa, 0.58 MPa or 0.6 MPa, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0055] In some preferred embodiments, the spray width on the nonwoven fabric surface is 10-20cm, for example, it can be 10cm, 11cm, 12cm, 13cm, 14cm, 15cm, 16cm, 17cm, 18cm, 19cm or 20cm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0056] In some preferred embodiments, the spray flow rate is 40-100 L / min, for example, it can be 40 L / min, 45 L / min, 50 L / min, 55 L / min, 60 L / min, 65 L / min, 70 L / min, 75 L / min, 80 L / min, 85 L / min, 90 L / min, 95 L / min or 100 L / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0057] In some preferred embodiments, the spraying time is 1-5 min, for example, it can be 1.0 min, 1.5 min, 2.0 min, 2.5 min, 3.0 min, 3.5 min, 4.0 min, 4.5 min or 5.0 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0058] As a preferred technical solution of the present invention, in step (III), the mass fraction of the reducing solution is 0.1-1.5 wt%, for example, it can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, or 1.5 wt%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] In some preferred embodiments, the reducing solution comprises an aqueous solution of sodium borohydride and / or an aqueous solution of citric acid.

[0060] As a preferred technical solution of the present invention, in step (III), the soaking time is 5-60 min, for example, it can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 10-20 min.

[0061] In some preferred embodiments, the nonwoven fabric is stirred during the soaking process at a speed of 200-1500 r / min, for example, 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min or 1500 r / min, but not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 500-800 r / min.

[0062] In some preferred embodiments, the heating and drying temperature is 50-150°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, with 80-120°C being the preferred temperature.

[0063] Different drying methods result in different microstructures of the composite antibacterial layer on the surface of the antibacterial nonwoven fabric. This invention preferably uses freeze-drying, which directly freezes and sublimates the water within the composite antibacterial layer formed on the nonwoven fabric surface into water vapor. Freeze-drying causes less damage to the microstructure of nanocellulose, preserving its three-dimensional porous network structure to a greater extent. The resulting composite antibacterial layer possesses a relatively complete three-dimensional porous network structure, allowing silver nanoparticles to adhere more uniformly within the pores. Compared to freeze-drying, heating drying causes greater damage to the microstructure of nanocellulose, leading to the collapse and destruction of the three-dimensional porous network structure, which is detrimental to the uniform dispersion of silver nanoparticles.

[0064] It should be noted that in the preparation method provided by this invention, the coating of the nonwoven fabric surface with nano-cellulose and silver particle precursors can be achieved by spraying or dipping, either entirely by spraying or entirely by dipping, or a combination of both. For example, the nano-cellulose solution can be dip-coated while the nano-silver precursor solution is sprayed; or the nano-cellulose solution can be sprayed while the nano-silver precursor solution is dip-coated. All combinations of the four coating methods listed above can achieve the technical effects claimed by this invention. Specifically:

[0065] In a first optional example, the method for preparing the antibacterial nonwoven fabric of nanocellulose loaded with nanosilver provided by the present invention specifically includes the following steps:

[0066] (1) Soak the nonwoven fabric in a 0.1-1.5 wt% nanocellulose solution for 0.25-2 h; then take out the nonwoven fabric and soak it in a 0.1-1.5 wt% silver nitrate aqueous solution for 0.25-2 h;

[0067] (2) After taking out the non-woven fabric obtained in step (1), soak it in a 0.1-1.5wt% reducing solution for 5-60 minutes. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 200-1500r / min to reduce the nano silver precursor to silver nanoparticles. Then, after taking out the non-woven fabric, dry it at 50-150℃ to obtain the antibacterial non-woven fabric.

[0068] In a second optional example, the method for preparing the antibacterial nonwoven fabric of nanocellulose loaded with nanosilver provided by the present invention specifically includes the following steps:

[0069] (1) Spray 0.1-1.5wt% nanocellulose solution onto the surface of nonwoven fabric; then continue to spray 0.1-1.5wt% silver nitrate aqueous solution onto its surface. The spraying pressure is 0.4-0.6MPa, the spraying width on the nonwoven fabric surface is 10-20cm, the spraying flow rate is 40-100L / min, and the spraying time is 1-5min.

[0070] (2) After taking out the non-woven fabric obtained in step (1), soak it in a 0.1-1.5wt% reducing solution for 5-60 minutes. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 200-1500r / min to reduce the nano silver precursor to silver nanoparticles. Then, after taking out the non-woven fabric, dry it at 50-150℃ to obtain the antibacterial non-woven fabric.

[0071] In a third optional example, the method for preparing the antibacterial nonwoven fabric of nanocellulose loaded with nanosilver provided by the present invention specifically includes the following steps:

[0072] (1) Soak the nonwoven fabric in a 0.1-1.5wt% nanocellulose solution for 0.25-2h; then take out the nonwoven fabric and spray a 0.1-1.5wt% silver nitrate aqueous solution on its surface. The spraying pressure is 0.4-0.6MPa, the spraying width on the nonwoven fabric surface is 10-20cm, the spraying flow rate is 40-100L / min, and the spraying time is 1-5min.

[0073] (2) After taking out the non-woven fabric obtained in step (1), soak it in a 0.1-1.5wt% reducing solution for 5-60 minutes. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 200-1500r / min to reduce the nano silver precursor to silver nanoparticles. Then, after taking out the non-woven fabric, dry it at 50-150℃ to obtain the antibacterial non-woven fabric.

[0074] In a fourth optional example, the method for preparing the antibacterial nonwoven fabric of nanocellulose loaded with nanosilver provided by the present invention specifically includes the following steps:

[0075] (1) Spray 0.1-1.5wt% nanocellulose solution onto the surface of nonwoven fabric. The spraying pressure is 0.4-0.6MPa, the spraying width on the surface of nonwoven fabric is 10-20cm, the spraying flow rate is 40-100L / min, and the spraying time is 1-5min; then immerse the nonwoven fabric in 0.1-1.5wt% silver nitrate aqueous solution for 0.25-2h.

[0076] (2) After taking out the non-woven fabric obtained in step (1), soak it in a 0.1-1.5wt% reducing solution for 5-60 minutes. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 200-1500r / min to reduce the nano silver precursor to silver nanoparticles. Then, after taking out the non-woven fabric, dry it at 50-150℃ to obtain the antibacterial non-woven fabric.

[0077] In a second aspect, the present invention provides an antibacterial nonwoven fabric of nanocellulose loaded with nanosilver, wherein the antibacterial nonwoven fabric is prepared by the preparation method described in the first aspect.

[0078] As a preferred technical solution of the present invention, the antibacterial nonwoven fabric has an inhibition rate of >99% against Escherichia coli and an inhibition rate of >99% against Staphylococcus aureus.

[0079] Thirdly, the present invention provides the use of the antibacterial nonwoven fabric of nanocellulose loaded with nanosilver as described in the second aspect, wherein the antibacterial nonwoven fabric is used as the surface layer of wet wipes, dry cotton wipes, baby care products or feminine care products.

[0080] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0081] Silver nanoparticles are nanoparticles with a large specific surface area and small particle size. They can rapidly adsorb onto the surface of bacterial cell membranes and penetrate into the bacterial cell interior. On one hand, silver nanoparticles interact with large molecular compounds containing sulfur and phosphorus (such as nucleic acids, RNA, and DNA) within bacterial cells, causing deformation of the bacterial DNA molecular structure, inhibiting bacterial self-replication, and affecting normal bacterial physiological functions (such as respiratory, digestive, and excretory functions), making it difficult for bacteria to develop resistance. On the other hand, silver nanoparticles interact with sulfhydryl groups in proteins, forming sulfates that inhibit protein synthesis, thereby reducing the activity of sulfhydryl enzymes, interfering with bacterial metabolism, and inducing bacterial death. After the bacteria are killed, the silver nanoparticles are released from the bacterial cells. These released silver nanoparticles can then bind to other bacterial cells, thus achieving sustained bactericidal effects. However, silver nanoparticles are prone to aggregation, which can affect the effective exertion of their antibacterial properties.

[0082] Nanocellulose is a natural biomass polymer with high hydrophilicity, excellent biocompatibility, and mechanical properties. This invention employs simple dipping or spraying methods to form a negatively charged nanocellulose coating on the surface of nonwoven fabric. Nanocellulose can be modified on the nonwoven fabric through various functional groups such as hydrogen bonds and hydroxyl groups. Subsequently, a nano-silver precursor solution is dipped or sprayed, further modifying the silver ions through electrostatic interactions, allowing silver ions to be loaded onto the nanocellulose coating. Immersion in a reducing solution allows for in-situ reduction of the silver ions loaded on the nonwoven fabric surface, effectively preventing the aggregation of the reduced silver nanoparticles. This significantly improves the utilization efficiency and modification stability of the nano-silver precursor solution, ensuring uniform distribution of silver nanoparticles on the nonwoven fabric surface. This solves the technical problems of uneven distribution and easy aggregation of silver nanoparticles on the nonwoven fabric surface in existing technologies, thereby effectively improving the antibacterial and bacteriostatic capabilities of the nonwoven fabric.

[0083] This invention utilizes an in-situ reduction method to reduce silver ions immobilized within the porous structure of nanocellulose into silver nanoparticles, which are then loaded onto the surface of a nonwoven fabric. Because the nanocellulose molecular chains contain numerous hydroxyl groups, they carry a large negative charge in water, exhibiting a strong adsorption effect on silver ions in silver nitrate solution. Therefore, it can serve as a matrix for loading silver ions, acting as a silver ion stabilizer. Furthermore, the three-dimensional porous network structure of nanocellulose provides abundant channels to act as a microreactor for synthesizing silver nanoparticles and inhibiting their aggregation, achieving both fixation and dispersion of the silver nanoparticles. Simultaneously, the network structure of nanocellulose effectively prevents the in-situ generated silver nanoparticles from detaching, thereby significantly enhancing the antibacterial properties of the antibacterial nonwoven fabric. This invention leverages the unique antibacterial and bactericidal properties and broad-spectrum antibacterial activity of silver nanoparticles to prepare an antibacterial nonwoven fabric with excellent antibacterial capabilities.

[0084] The carboxylic acid groups in nanocellulose combine with silver ions, allowing the silver ions to be adsorbed onto the nanocellulose structure. The resulting antibacterial composite film exhibits a low silver release rate, resulting in a sustained-release effect of the silver nanoparticles. This low release level of silver nanoparticles achieves continuous bactericidal and bacteriostatic effects without toxicity to human cells. Therefore, the antibacterial nonwoven fabric prepared by this invention allows for the attachment and growth of epidermal cells without cytotoxicity, and possesses anti-inflammatory and wound-healing properties. Furthermore, the abundant three-dimensional porous network structure of cellulose demonstrates excellent air permeability and liquid absorption capacity, providing absorption channels for wound exudates. Therefore, the antibacterial nonwoven fabric prepared using this invention not only has significant antibacterial capabilities but also promotes wound healing when used as a wound dressing, demonstrating its potential applications in wound care.

[0085] The antibacterial nonwoven fabric prepared by this invention possesses the dual properties of nanocellulose and silver nanoparticles. Through the synergistic effect and complementary advantages of the two, the antibacterial performance and applicability of the nonwoven fabric can be significantly improved. Specifically, nanocellulose can improve the aggregation phenomenon of silver nanoparticles, solving the problems of easy aggregation and poor interfacial compatibility of silver nanoparticles, maximizing the antibacterial properties of silver nanoparticles, and achieving a long-lasting and stable antibacterial capability of the antibacterial nonwoven fabric. Furthermore, nanocellulose itself has good film-forming properties, serving as a carrier for silver nanoparticles, and can form a smooth, transparent, and well-compatible antibacterial composite film on the surface of the nonwoven fabric. In addition, nanocellulose can also improve the water absorption and skin-friendliness of the nonwoven fabric. Simultaneously, the entire production process does not require the use of toxic or harmful chemical reagents, the process is simple and environmentally friendly, and suitable for large-scale industrial promotion. Attached Figure Description

[0086] Figure 1 The process flow diagrams for preparing the antibacterial nonwoven fabrics provided in Examples 1-21 of this invention are shown below.

[0087] Figure 2 Optical images of Escherichia coli colony culture on antibacterial nonwoven fabric provided in Embodiment 3 and Comparative Example 1 of the present invention;

[0088] in, Figure 2 (a) An optical image of Escherichia coli colony culture on the antibacterial nonwoven fabric provided in Example 3. Figure 2 (b) Optical images of Escherichia coli colony culture for the provided antibacterial nonwoven fabric comparative example 1;

[0089] Figure 3 These are optical images of Staphylococcus aureus colony cultures obtained from the antibacterial nonwoven fabrics provided in Embodiment 3 and Comparative Example 1 of the present invention.

[0090] in, Figure 3(a) An optical image of Staphylococcus aureus colony culture of the antibacterial nonwoven fabric provided in Example 3. Figure 3 (b) Optical images of Staphylococcus aureus colony culture on the antibacterial nonwoven fabric provided in Comparative Example 1. Detailed Implementation

[0091] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0092] Example 1

[0093] This embodiment provides a method for preparing an antibacterial nonwoven fabric of nanocellulose loaded with nanosilver, such as... Figure 1 As shown, the preparation method includes the following steps:

[0094] (1) Soak the nonwoven fabric in a 0.1 wt% aqueous solution of cellulose nanofibers for 2 hours; then take out the nonwoven fabric and soak it in a 0.1 wt% aqueous solution of silver nitrate for 2 hours;

[0095] (2) After taking out the non-woven fabric obtained in step (1), soak it in a 0.1wt% sodium borohydride aqueous solution for 60 min. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 200 r / min to reduce silver nitrate to silver nanoparticles. Then, the non-woven fabric is taken out and dried at 50°C to obtain the antibacterial non-woven fabric.

[0096] Example 2

[0097] This embodiment provides a method for preparing an antibacterial nonwoven fabric of nanocellulose loaded with nanosilver, such as... Figure 1 As shown, the preparation method includes the following steps:

[0098] (1) The nonwoven fabric was soaked in a 0.25wt% aqueous solution of cellulose nanocrystals for 1 hour; then the nonwoven fabric was taken out and soaked in a 0.8wt% aqueous solution of silver nitrate for 0.75 hours.

[0099] (2) After taking out the non-woven fabric obtained in step (1), soak it in a 0.25wt% sodium borohydride aqueous solution for 20 minutes. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 500r / min to reduce silver nitrate to silver nanoparticles. Then, the non-woven fabric is taken out and dried at 80℃ to obtain the antibacterial non-woven fabric.

[0100] Example 3

[0101] This embodiment provides a method for preparing an antibacterial nonwoven fabric of nanocellulose loaded with nanosilver, such as... Figure 1 As shown, the preparation method includes the following steps:

[0102] (1) The nonwoven fabric was soaked in a 0.4wt% aqueous solution of phosphorylated nanofiber crystals for 0.7h; then the nonwoven fabric was taken out and soaked in a 0.9wt% aqueous solution of silver nitrate for 0.6h;

[0103] (2) After taking out the non-woven fabric obtained in step (1), soak it in a 0.4wt% sodium borohydride aqueous solution for 15 minutes. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 600r / min to reduce silver nitrate to silver nanoparticles. Then, the non-woven fabric is taken out and dried at 100℃ to obtain the antibacterial non-woven fabric.

[0104] Example 4

[0105] This embodiment provides a method for preparing an antibacterial nonwoven fabric of nanocellulose loaded with nanosilver, such as... Figure 1 As shown, the preparation method includes the following steps:

[0106] (1) The nonwoven fabric was soaked in a 0.5 wt% aqueous solution of phosphorylated cellulose nanofibers for 0.5 h; then the nonwoven fabric was taken out and soaked in a 1 wt% aqueous solution of silver nitrate for 0.5 h;

[0107] (2) After taking out the non-woven fabric obtained in step (1), soak it in a 0.6wt% citric acid aqueous solution for 10 minutes. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 800r / min to reduce silver nitrate to silver nanoparticles. Then, the non-woven fabric is taken out and dried at 120℃ to obtain the antibacterial non-woven fabric.

[0108] Example 5

[0109] This embodiment provides a method for preparing an antibacterial nonwoven fabric of nanocellulose loaded with nanosilver, such as... Figure 1 As shown, the preparation method includes the following steps:

[0110] (1) The nonwoven fabric was soaked in a 1.5wt% aqueous solution of carboxylated cellulose nanofibers for 0.25h; then the nonwoven fabric was taken out and soaked in a 1.5wt% aqueous solution of silver nitrate for 0.25h.

[0111] (2) After taking out the non-woven fabric obtained in step (1), soak it in a 1.5wt% citric acid aqueous solution for 5 minutes. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 1500r / min to reduce silver nitrate to silver nanoparticles. Then, the non-woven fabric is taken out and dried at 150℃ to obtain the antibacterial non-woven fabric.

[0112] Example 6

[0113] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nano-cellulose and nano-silver. The difference from Example 3 is that the mass fraction of the cellulose nanofiber aqueous solution in step (1) is adjusted to 0.2wt%, while other operating parameters are exactly the same as in Example 3.

[0114] Example 7

[0115] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nano-cellulose and nano-silver. The difference from Example 3 is that the mass fraction of the cellulose nanofiber aqueous solution in step (1) is adjusted to 0.25 wt%, while other operating parameters are exactly the same as in Example 3.

[0116] Example 8

[0117] This embodiment provides a method for preparing an antibacterial nonwoven fabric loaded with nano-cellulose and nano-silver. The difference from Example 3 is that the mass fraction of the cellulose nanofiber aqueous solution in step (1) is adjusted to 0.5 wt%, while other operating parameters are exactly the same as in Example 3.

[0118] Example 9

[0119] This embodiment provides a method for preparing an antibacterial nonwoven fabric loaded with nano-cellulose and nano-silver. The difference from Example 3 is that the mass fraction of the cellulose nanofiber aqueous solution in step (1) is adjusted to 0.6 wt%, while the other operating parameters are exactly the same as in Example 3.

[0120] Example 10

[0121] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nano-silver from nanocellulose. The difference from Embodiment 3 is that the soaking time of the nonwoven fabric in the aqueous solution of cellulose nanofiber in step (1) is adjusted to 0.4 h, while other operating parameters are exactly the same as in Embodiment 3.

[0122] Example 11

[0123] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nano-silver from nanocellulose. The difference from Embodiment 3 is that the soaking time of the nonwoven fabric in the aqueous solution of cellulose nanofiber in step (1) is adjusted to 0.5h, while other operating parameters are exactly the same as in Embodiment 3.

[0124] Example 12

[0125] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nano-silver from nanocellulose. The difference from Embodiment 3 is that the soaking time of the nonwoven fabric in the aqueous solution of cellulose nanofiber in step (1) is adjusted to 1 hour, while other operating parameters are exactly the same as in Embodiment 3.

[0126] Example 13

[0127] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nano-silver from nanocellulose. The difference from Embodiment 3 is that the soaking time of the nonwoven fabric in the cellulose nanofiber aqueous solution in step (1) is adjusted to 1.2h, while other operating parameters are exactly the same as in Embodiment 3.

[0128] Example 14

[0129] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nanocellulose and nanosilver. The difference from Example 3 is that the mass fraction of silver nitrate aqueous solution in step (1) is adjusted to 0.7wt%, while other operating parameters are exactly the same as in Example 3.

[0130] Example 15

[0131] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nanocellulose and nanosilver. The difference from Example 3 is that the mass fraction of silver nitrate aqueous solution in step (1) is adjusted to 0.8wt%, while other operating parameters are exactly the same as in Example 3.

[0132] Example 16

[0133] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nanocellulose and nanosilver. The difference from Example 3 is that the mass fraction of silver nitrate aqueous solution in step (1) is adjusted to 1 wt%, while other operating parameters are exactly the same as in Example 3.

[0134] Example 17

[0135] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nanocellulose and nanosilver. The difference from Example 3 is that the mass fraction of silver nitrate aqueous solution in step (1) is adjusted to 1.2 wt%, while other operating parameters are exactly the same as in Example 3.

[0136] Example 18

[0137] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nanocellulose and nanosilver. The difference from Example 3 is that the soaking time of the nonwoven fabric in silver nitrate aqueous solution in step (1) is adjusted to 0.4h, while other operating parameters are exactly the same as in Example 3.

[0138] Example 19

[0139] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nanocellulose and nanosilver. The difference from embodiment 3 is that the soaking time of the nonwoven fabric in silver nitrate aqueous solution in step (1) is adjusted to 0.5h, while other operating parameters are exactly the same as in embodiment 3.

[0140] Example 20

[0141] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nanocellulose and nanosilver. The difference from Example 3 is that the soaking time of the nonwoven fabric in silver nitrate aqueous solution in step (1) is adjusted to 0.75h, while other operating parameters are exactly the same as in Example 3.

[0142] Example 21

[0143] This embodiment provides a method for preparing antibacterial nonwoven fabric loaded with nanocellulose and nanosilver. The difference from Example 3 is that the soaking time of the nonwoven fabric in silver nitrate aqueous solution in step (1) is adjusted to 0.8h, while other operating parameters are exactly the same as in Example 3.

[0144] Example 22

[0145] This embodiment provides a method for preparing an antibacterial nonwoven fabric of nanocellulose loaded with nanosilver, such as... Figure 1 As shown, the preparation method includes the following steps:

[0146] (1) The surface of the nonwoven fabric was sprayed with a 0.4wt% phosphorylated nanofiber crystal aqueous solution. The spraying pressure was 0.5MPa, the spraying width on the nonwoven fabric surface was 20cm, the spraying flow rate was 80L / min, and the spraying time was 3min.

[0147] (2) Subsequently, a 0.9wt% silver nitrate aqueous solution was used to spray the surface of the nonwoven fabric. The spraying pressure was 0.5MPa, the spraying width on the nonwoven fabric surface was 20cm, the spraying flow rate was 80L / min, and the spraying time was 3min.

[0148] (3) After taking out the non-woven fabric obtained in step (1), soak it in a 0.4wt% sodium borohydride aqueous solution for 15 minutes. During the soaking process, the non-woven fabric is mechanically stirred at a speed of 600r / min to reduce silver nitrate to silver nanoparticles. Then, the non-woven fabric is taken out and dried at 100℃ to obtain the antibacterial non-woven fabric.

[0149] Comparative Example

[0150] This comparative example provides a method for preparing antibacterial nonwoven fabric. The difference from Example 3 is that the soaking of cellulose nanofiber aqueous solution is omitted in step (1), and the nonwoven fabric is directly soaked in 0.1wt% silver nitrate aqueous solution for 2h. Other operating parameters are exactly the same as in Example 3.

[0151] Table 1 summarizes the main process parameters involved in Examples 1-21.

[0152] Table 1

[0153] Nanocellulose solution mass fraction (wt%) Soaking time in nanocellulose solution (h) Silver nitrate aqueous solution mass fraction (wt%) Immersion time (h) in silver nitrate aqueous solution Example 1 0.1 2 0.1 2 Example 2 0.25 1 0.8 0.75 Example 3 0.4 0.7 0.9 0.6 Example 4 0.5 0.5 1 0.5 Example 5 1.5 0.25 1.5 0.25 Example 6 0.2 0.7 0.9 0.6 Example 7 0.25 0.7 0.9 0.6 Example 8 0.5 0.7 0.9 0.6 Example 9 0.6 0.7 0.9 0.6 Example 10 0.4 0.4 0.9 0.6 Example 11 0.4 0.5 0.9 0.6 Example 12 0.4 1 0.9 0.6 Example 13 0.4 1.2 0.9 0.6 Example 14 0.4 0.7 0.7 0.6 Example 15 0.4 0.7 0.8 0.6 Example 16 0.4 0.7 1 0.6 Example 17 0.4 0.7 1.2 0.6 Example 18 0.4 0.7 0.9 0.4 Example 19 0.4 0.7 0.9 0.5 Example 20 0.4 0.7 0.9 0.75 Example 21 0.4 0.7 0.9 0.8

[0154] The antibacterial nonwoven fabrics prepared in Example 3 and Comparative Example 1 were cultured for Escherichia coli and Staphylococcus aureus, and the results were as follows: Figure 2 and Figure 3 The shown optical images of bacterial colony cultures are from... Figure 2 (a) and Figure 2 (b) The comparison shows that loading nonwoven fabric with nanocellulose followed by silver nanoparticles significantly improves its antibacterial properties against Escherichia coli. Figure 3 (a) and Figure 3 (b) The comparison shows that the nonwoven fabric loaded with nanocellulose first and then loaded with silver nanoparticles has a significantly improved antibacterial performance against Staphylococcus aureus.

[0155] Referring to GB-T / 20944.3-2008 Evaluation of Antibacterial Properties of Textiles, the antibacterial rates of the nonwoven fabrics prepared in the examples were tested, and the results are shown in Table 2:

[0156] Table 2

[0157] Escherichia coli inhibition rate (%) Staphylococcus aureus inhibition rate (%) Example 1 95.3 92.4 Example 2 96.7 92.1 Example 3 100 100 Example 4 91.5 93.4 Example 5 94.5 93.7 Example 6 92.4 89.5 Example 7 100 100 Example 8 100 100 Example 9 99.4 99.1 Example 10 94.2 92.5 Example 11 100 100 Example 12 100 100 Example 13 98.9 99.6 Example 14 96.4 97.8 Example 15 100 100 Example 16 100 100 Example 17 99.8 99.3 Example 18 94.2 96.1 Example 19 100 100 Example 20 100 100 Example 21 99.4 98.7 Example 22 100 100 Comparative Example 75.4 72.3

[0158] As can be seen from the test results provided in Examples 1-5, the antibacterial nonwoven fabric prepared by the present invention has a good inhibitory effect on Escherichia coli and Staphylococcus aureus.

[0159] As can be seen from the test data provided in Examples 3 and 6-9, the antibacterial nonwoven fabric obtained by soaking in a 0.1-1.5 wt% nanocellulose solution of the present invention has a better antibacterial effect against Escherichia coli and Staphylococcus aureus; furthermore, the antibacterial nonwoven fabric obtained by soaking in a 0.25-0.5 wt% nanocellulose solution has an even better antibacterial effect against Escherichia coli and Staphylococcus aureus. Therefore, the mass fraction of the nanocellulose solution is preferably 0.1-1.5 wt%, and more preferably 0.25-0.5 wt%.

[0160] As can be seen from the test data provided in Examples 3 and 10-13, the antibacterial nonwoven fabric obtained by the present invention after soaking in nanocellulose solution for 0.25-2 hours has a better antibacterial effect against Escherichia coli and Staphylococcus aureus; furthermore, the antibacterial nonwoven fabric obtained after soaking in nanocellulose solution for 0.5-1 hour has an even better antibacterial effect against Escherichia coli and Staphylococcus aureus. Therefore, the soaking time of the nonwoven fabric in nanocellulose solution is preferably 0.25-2 hours, and more preferably 0.5-1 hour.

[0161] As can be seen from the test data provided in Examples 3 and 14-17, the antibacterial nonwoven fabric obtained by soaking in 0.1-1.5 wt% silver nitrate solution of the present invention has a better antibacterial effect against Escherichia coli and Staphylococcus aureus; furthermore, the antibacterial nonwoven fabric obtained by soaking in 0.8-1 wt% silver nitrate solution has an even better antibacterial effect against Escherichia coli and Staphylococcus aureus. Therefore, the mass fraction of silver nitrate solution is preferably 0.1-1.5 wt%, and more preferably 0.8-1 wt%.

[0162] As can be seen from the test data provided in Examples 3 and 18-21, the antibacterial nonwoven fabric obtained by the present invention after soaking in silver nitrate solution for 0.25-2 hours has a better antibacterial effect against Escherichia coli and Staphylococcus aureus; furthermore, the antibacterial nonwoven fabric obtained after soaking in silver nitrate solution for 0.5-0.75 hours has an even better antibacterial effect against Escherichia coli and Staphylococcus aureus. Therefore, the soaking time of the nonwoven fabric in silver nitrate solution is preferably 0.25-2 hours, and more preferably 0.5-0.75 hours.

[0163] As can be seen from the test data provided in Example 3 and the comparative example, the antibacterial nonwoven fabric prepared in this invention has a better inhibitory effect on Escherichia coli and Staphylococcus aureus compared with the nonwoven fabric directly modified with silver nanoparticles.

[0164] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a nanocellulose-supported nanosilver antibacterial nonwoven fabric, characterized by, The preparation method comprises: (I) spraying a nanocellulose solution on the surface of a non-woven fabric, or immersing the non-woven fabric in the nanocellulose solution; the mass fraction of the nanocellulose solution is 0.1-1.5 wt%, and the immersion time is 0.25-2 h; The nanocellulose solution comprises a phosphonated nanocellulose crystal aqueous solution or a phosphonated cellulose nanofiber aqueous solution; The phosphonated cellulose nanofiber aqueous solution is prepared by the following method: (1) cellulose raw material, phosphate and urea are weighed according to a molar ratio of 1:(0.5-2):(3-7), the phosphate and urea are ultrasonically dissolved in deionized water, and the mass ratio of the cellulose raw material to the deionized water is 1:(2.5-8); (2) the cellulose raw material is immersed in a phosphonated reagent solution, a pressure of 0.1-0.4 MPa is applied, and hot soaking pretreatment is performed at 60-95 ℃ for 10-180 min; the cellulose raw material after the hot soaking pretreatment is dried at 70-110 ℃ until the weight is constant, and then heated to 140-165 ℃ for solidification for 10-90 min; (3) the phosphonated cellulose slurry is washed and purified after adding water, and then homogenized 5-15 times under a pressure of 70-100 MPa; (II) the non-woven fabric obtained in step (I) is taken out, and a nanosilver precursor solution is sprayed on the surface of the non-woven fabric or the non-woven fabric is immersed in the nanosilver precursor solution; the mass fraction of the nanosilver precursor solution is 0.1-1.5 wt%, and the immersion time is 0.25-2 h; (III) the non-woven fabric obtained in step (II) is taken out and immersed in a reducing solution to reduce the nanosilver precursor to silver nanoparticles; then freeze-drying or heating drying is performed to obtain the antibacterial non-woven fabric.

2. The production method according to claim 1, characterized by, In step (I), the spraying pressure is 0.4-0.6 MPa.

3. The preparation method according to claim 1, characterized in that, In step (I), the spraying width on the surface of the non-woven fabric is 10-20 cm.

4. The method of claim 1, wherein, In step (I), the spraying flow rate is 40-100 L / min.

5. The preparation method according to claim 1, characterized in that, In step (I), the spraying time is 1-5 min.

6. The method of claim 1, wherein, In step (II), the nanosilver precursor solution comprises an aqueous silver nitrate solution.

7. The preparation method according to claim 1, characterized in that, In step (II), the spraying pressure is 0.4-0.6 MPa.

8. The method of claim 1, wherein, In step (II), the spraying width on the surface of the non-woven fabric is 10-20 cm.

9. The method of claim 1, wherein, In step (II), the spraying flow rate is 40-100 L / min.

10. The method of claim 1, wherein, In step (II), the spraying time is 1-5 min.

11. The method of claim 1, wherein, In step (III), the mass fraction of the reducing solution is 0.1-1.5 wt%.

12. The method of claim 1, wherein, In step (III), the reducing solution comprises an aqueous sodium borohydride solution and / or an aqueous citric acid solution.

13. The method of claim 1, wherein, In step (III), the immersion time is 5-60 min.

14. The method of claim 1, wherein, In step (III), the non-woven fabric is stirred during the immersion process, and the stirring speed is 200-1500 r / min.

15. The method of claim 1, wherein, In step (III), the heating drying temperature is 50-150 ℃.

16. A nanocellulose supported nanosilver antibacterial nonwoven fabric, characterized by, The antibacterial non-woven fabric is prepared by the preparation method of any one of claims 1 to 15.

17. The antibacterial nonwoven fabric according to claim 16, wherein The antibacterial nonwoven fabric has a bacteria inhibition rate of >99% against Escherichia coli and a bacteria inhibition rate of >99% against Staphylococcus aureus.

18. Use of the nanocellulose supported nanosilver antibacterial nonwoven fabric according to claim 16 or 17, characterized in that, The antibacterial nonwoven fabric is used for the surface layer of a wet wipe, a dry cotton-soft wipe, a baby care product, or a female care product.

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