A breathable and moisture-permeable nanofiber fabric and its preparation method

Abstract

This invention provides a breathable and moisture-permeable nanofiber fabric and its preparation method, belonging to the field of fabric technology. The method includes the following steps: Step S1, preparing an electrospinning solution; Step S2, preparing a polytetrafluoroethylene (PTFE) porous nanofiber membrane; Step S3, preparing a modified PTFE porous nanofiber membrane; Step S4, layering from top to bottom in the following order: nylon 66, TPU hot melt adhesive mesh, modified PTFE porous nanofiber membrane, TPU hot melt adhesive mesh, and polyester, then feeding them into a lamination device for lamination. After lamination, the fabric is laid flat, cooled, and shaped to obtain the breathable and moisture-permeable nanofiber fabric. This invention enables the nanofiber fabric to maintain high breathability and moisture permeability while improving its durability.

Description

Technical Field

[0001] This invention relates to the field of fabric technology, specifically to a breathable and moisture-permeable nanofiber fabric and its preparation method. Background Technology

[0002] Currently, breathable and moisture-permeable fabrics used in clothing, outdoor protection, and functional workwear often employ a composite structure of "fabric / membrane / fabric." The membrane layer primarily includes hydrophilic polyurethane membranes, microporous polytetrafluoroethylene membranes, and electrospun nanofiber membranes. Microporous membranes typically achieve waterproofing and windproofing by having pore sizes smaller than the liquid water permeation threshold, while utilizing a pore network to facilitate air and water vapor exchange. Hydrophilic membranes, on the other hand, achieve moisture permeability through the adsorption-diffusion mechanism of water molecules by polymer segments. To meet abrasion resistance and mechanical requirements, the membrane layer is usually laminated with fabrics such as nylon and polyester using hot melt adhesive films, hot melt adhesive powders, or dotted adhesives to form a processable and wearable multi-layered structure.

[0003] However, existing technologies still have shortcomings in synergistically improving air permeability and durability. For low surface energy materials such as PTFE, the membrane surface is highly inert and has poor wettability. Conventional hydrophilic treatments (such as dipping in hydrophilic agents, coating with hydrophilic polymers, simple surface oxidation, or adsorption finishing) are prone to insufficient bonding and poor wash and abrasion resistance. Furthermore, liquid-phase coating or thick coating treatments can easily form a continuous cover on the microporous surface, causing local blockage of the pores and resulting in a significant decrease in air permeability and moisture permeability. For electrospun nanofiber membranes, although they have the advantages of high specific surface area and potential high flux, their pore structure and mechanical stability are very sensitive to subsequent heat treatment, lamination temperature and pressure, and adhesive layer penetration. They are prone to pore collapse, uncontrolled pore size distribution, or a decrease in effective porosity after composite formation, which in turn leads to moisture permeability reduction, increased stuffiness, and insufficient service life. In addition, sweat salts, sebum and particulate pollution have an amplifying effect on pore wall wetting and mass transfer. If the pore wall interface does not have a stable hydration layer or anti-fouling properties, the fabric will often become "clogged" and its performance will decline after repeated wear and washing, making it difficult to maintain stable breathability and moisture permeability for a long time.

[0004] Therefore, there is a need to provide a breathable and moisture-permeable nanofiber fabric and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0005] In view of this, the present invention provides a breathable and moisture-permeable nanofiber fabric and its preparation method, which can improve the durability of the nanofiber fabric while maintaining high breathability and moisture permeability.

[0006] To achieve the above objectives, the present invention provides a method for preparing a breathable and moisture-wicking nanofiber fabric, comprising the following steps:

[0007] Step S1: Slowly add polyethylene glycol to deionized water, heat and stir until dissolved, cool down, add ammonium bicarbonate, stir evenly, slowly add polytetrafluoroethylene aqueous dispersion, then add anhydrous ethanol, let stand to degas, filter, and obtain electrospinning stock solution.

[0008] Step S2: Fix the release paper on the ground collector, use the electrospinning solution to perform electrospinning to obtain the precursor membrane. After electrospinning, under nitrogen protection, heat up and sinter, then cool to obtain a polytetrafluoroethylene porous nanofiber membrane.

[0009] Step S3: The inner surface of the polytetrafluoroethylene porous nanofiber membrane is treated with oxygen plasma, and then chemical vapor deposition is performed using glycidyl methacrylate, ethylene glycol dimethacrylate and DTBP under nitrogen protection. After deposition, the membrane is washed and dried to obtain the modified polytetrafluoroethylene porous nanofiber membrane.

[0010] Step S4: Lay out the following layers from top to bottom in the following order: Nylon 66, TPU hot melt adhesive mesh, modified polytetrafluoroethylene porous nanofiber membrane, TPU hot melt adhesive mesh, and polyester. Then, put them into a lamination equipment for lamination. After lamination, lay them flat to cool and shape them to obtain a breathable and moisture-permeable nanofiber fabric.

[0011] Aqueous dispersions of polytetrafluoroethylene (PTFE) provide the solid phase PTFE particles for film formation. However, the PTFE aqueous dispersion system itself lacks chain entanglement and viscoelasticity, making it prone to atomization, fiber breakage, and discontinuous deposition during direct electrospinning. Polyethylene glycol (PEG), on the other hand, can significantly improve the system's viscosity and chain entanglement, giving the PTFE-containing dispersion system the viscoelasticity required for sustainable jetting. This facilitates the formation of a continuous and uniform fibrous deposition structure during electrospinning, reducing dripping, splashing, and beading defects. Simultaneously, PEG can melt and migrate during subsequent heat treatment, gradually removing it and promoting the formation and retention of interconnected pores in the fiber stacking structure. This increases the porosity and specific surface area of ​​the nanofiber membrane, thus facilitating the transfer of air and water vapor. Furthermore, ammonium bicarbonate can act as a gas-emission pore-forming agent. During heating, it decomposes to produce and release gas, promoting the formation of more open interconnected pore structures in the nanofiber membrane and reducing localized densification, thereby improving the air permeability and moisture permeability of the nanofiber fabric.

[0012] After electrospinning, the precursor membrane is first heated to degas, allowing ammonium bicarbonate to fully decompose and release gas. This also promotes the discharge of residual volatile components, which is beneficial for forming open interconnected pores and reducing the probability of closed pores during subsequent sintering and densification. This improves the air and moisture permeability of the polytetrafluoroethylene porous nanofiber membrane and reduces defects. Then, the temperature is raised further for sintering, allowing the polytetrafluoroethylene particles to form a continuous skeleton structure. This promotes higher strength and wear resistance of the polytetrafluoroethylene porous nanofiber membrane, thus achieving a balance between strength improvement and pore structure preservation.

[0013] By treating the inner side of the polytetrafluoroethylene porous nanofiber membrane with oxygen plasma, the surface can be cleaned, slightly etched, and oxygen-containing active groups / sites can be introduced without significantly blocking the pores. This improves the surface energy and wettability, providing a basis for film adhesion and reaction initiation sites for subsequent vapor deposition reaction layers, and enhancing the coating's adhesion strength and durability. Furthermore, by treating only the inner side and retaining the hydrophobicity of the outer side, a unidirectional mass transfer characteristic of being hydrophilic on the inside and hydrophobic on the outside is constructed.

[0014] Using glycidyl methacrylate and ethylene glycol dimethacrylate as reactants and DTBP as an initiator, chemical vapor deposition preferentially deposits the material on the pore wall surface of polytetrafluoroethylene porous nanofiber membranes, rather than filling the pore volume with a gel-like / gel-like substance. Therefore, the impact on pore size and pore connectivity is significantly less than that of liquid phase dip coating or coating methods. The epoxy groups of glycidyl methacrylate can provide chemical anchors for subsequent reactions, while ethylene glycol dimethacrylate can provide crosslinking points, enabling the deposited layer to form a three-dimensional crosslinked network. This stabilizes the spatial distribution of epoxy groups brought by glycidyl methacrylate and inhibits chain segment migration and swelling, achieving a synergistic effect of high reactivity and low pore blockage risk, thus improving water resistance, abrasion resistance, and wash resistance.

[0015] Nylon 66, as the outer fabric, provides abrasion resistance, tear resistance, and protection, reducing mechanical damage caused by direct exposure of the membrane layer and improving the overall durability of the fabric. Polyester, as the inner fabric, provides dimensional stability and wearing comfort, and can also serve as an inner moisture diffusion layer, working synergistically with the hydrophilic pore walls on the inner side of the modified polytetrafluoroethylene porous nanofiber membrane to improve the feeling of dryness. This forms a functional gradient structure where the outer side remains hydrophobic and the inner pore walls are hydrophilic, allowing the fabric to significantly improve moisture permeability and long-term stability while maintaining breathability.

[0016] Preferably, in step S1, the heating and stirring temperature is 50-60℃, and the time is 2-4h; the concentration of the polytetrafluoroethylene aqueous dispersion is 55-65wt%; the electrospinning solution includes the following components in parts by weight: 50-80 parts of deionized water, 4-6 parts of polyethylene glycol, 90-110 parts of polytetrafluoroethylene aqueous dispersion, and 15-25 parts of anhydrous ethanol.

[0017] Preferably, in step S2, the electrospinning voltage is 14-17kV, the spraying distance is 14-16cm, and the single needle flow rate is 0.4-0.6mL / h.

[0018] Preferably, in step S2, the density of the precursor film is 6-8 g / m³. 2 The sintering temperature is 360-370℃, and the time is 12-18 minutes.

[0019] Preferably, in step S3, the oxygen flow rate of the oxygen plasma treatment is 30-45 sccm, the power is 100-150 W, the pressure is 40-70 Pa, and the time is 60-90 s.

[0020] By controlling the time, power, and pressure of plasma treatment, the surface energy and wettability of the inner side of the polytetrafluoroethylene porous nanofiber membrane can be improved, while avoiding overtreatment that could lead to pore wall embrittlement or pore size loss.

[0021] Preferably, in step S3, the flow rate of glycidyl methacrylate is 1.6-2.4 sccm, the flow rate of ethylene glycol dimethacrylate is 0.18-0.25 sccm, the flow rate of DTBP is 0.7-0.85 sccm, and the flow rate of N2 is 3-4 sccm.

[0022] Preferably, in step S3, the deposition rate is 15-20 nm / min, the temperature is 200-240 °C, and the deposition thickness is 25-35 nm.

[0023] By controlling the thickness of the deposited layer within the nanometer range, the chemical properties of the pore walls can be altered without causing blockage of the pores. This allows for the maintenance of pore connectivity and air and moisture permeability to the greatest extent possible while achieving a stable reaction interface.

[0024] Preferably, in step S3, after deposition, a taurine solution is uniformly coated and heated for reaction; the taurine solution is prepared by dissolving taurine in deionized water and adjusting the pH to 8.8-9.2; the heating reaction temperature is 55-65℃ and the time is 1-2h.

[0025] Taurine solution reacts with the deposited layer under alkaline conditions, causing epoxy ring opening and forming covalent bonds, which stably grafts taurine groups onto the pore wall surface. The strong hydrophilic sulfonic acid groups contained in taurine can significantly improve the adsorption capacity of the pore wall for water, allowing the transfer of water in the channels of the modified polytetrafluoroethylene porous nanofiber membrane to be accelerated through the "adsorption-diffusion-desorption" mechanism, which is especially beneficial for improving the moisture permeation rate in high humidity environments on the human body side.

[0026] Preferably, in step S4, the lamination temperature is 125-135℃, the pressure is 0.1-0.12MPa, and the time is 10-12s; the thickness of nylon 66 is 0.12-0.16mm, the thickness of TPU hot melt adhesive mesh is 40-50μm, the thickness of modified polytetrafluoroethylene porous nanofiber membrane is 22-28μm, and the thickness of polyester is 0.2-0.3mm.

[0027] Short-duration, moderate temperature-pressure lamination can form a discrete adhesive network, which is less likely to block the membrane pores over a large area than continuous adhesive films. It can balance adhesion and pore retention, and avoid excessive penetration of adhesive into the pores, which would reduce the breathability and moisture permeability of the fabric.

[0028] To achieve the above objectives, the present invention also provides a breathable and moisture-permeable nanofiber fabric prepared by the above-described method for preparing breathable and moisture-permeable nanofiber fabric.

[0029] The breathable and moisture-permeable nanofiber fabric prepared by the method of the present invention has improved durability while maintaining high breathability and moisture permeability.

[0030] The above-described technical solution of the present invention has at least the following beneficial effects:

[0031] 1. The continuous skeleton structure formed by polytetrafluoroethylene particles promotes higher mechanical strength, folding resistance and abrasion resistance of polytetrafluoroethylene porous nanofiber membranes, thus achieving a balance between strength improvement and pore structure preservation; polyethylene glycol and ammonium bicarbonate can promote the formation of more open interconnected pore structures in nanofiber membranes, reduce local densification of the structure, thereby improving the air permeability and moisture permeability of nanofiber fabrics.

[0032] 2. Through chemical vapor deposition, the cross-linked coating formed by glycidyl methacrylate and ethylene glycol dimethacrylate can be preferentially deposited on the pore wall surface of polytetrafluoroethylene porous nanofiber membranes instead of filling the pore volume with gel-like / gel-like substances. Therefore, the impact on pore size and pore connectivity is significantly less than that of liquid phase dip coating or coating methods.

[0033] 3. Through deposition modification, the modified polytetrafluoroethylene porous nanofiber membrane forms a functional gradient structure in which the outer side remains hydrophobic and the inner pore wall is hydrophilic, thereby significantly improving the moisture permeability and durability of the nanofiber fabric while maintaining air permeability. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0035] In the following examples, the molecular weight of the polyethylene glycol is 5 × 10⁻⁶. 5 This is a commercially available product.

[0036] Example 1

[0037] Slowly add 5g of polyethylene glycol to 60g of deionized water, place in a 55℃ water bath and stir magnetically for 3h until completely clear. Cool the solution to room temperature, add 4g of ammonium bicarbonate while stirring, and continue stirring for 8min to suspend it evenly. Slowly add 100g of 60wt% polytetrafluoroethylene aqueous dispersion in 5 portions, stirring for 30min each time. Then add 20g of anhydrous ethanol, continue stirring for 10min, let stand to degas for 15min, filter, and obtain the electrospinning solution.

[0038] Release paper was fixed on a grounded collector, and electrospinning was performed using the electrospinning solution. The parameters were set as follows: voltage 15kV, spray distance 15cm, single-needle flow rate 0.5mL / h, and the precursor membrane density was controlled to reach 7g / m³. 2 Remove the precursor membrane, let it stand for 10 minutes, dry it at 80℃ for 30 minutes, heat it to 220℃ at a rate of 3℃ / min, release the gas for 40 minutes, raise the temperature to 365℃ under nitrogen protection, sinter it for 15 minutes, and cool it to obtain a polytetrafluoroethylene porous nanofiber membrane.

[0039] Dissolve 5g of taurine in 500mL of deionized water and adjust the pH to 9 to obtain a taurine solution.

[0040] The inner surface of a polytetrafluoroethylene (PTFE) porous nanofiber membrane was treated with oxygen plasma at a flow rate of 35 sccm, a power of 125 W, a pressure of 55 Pa, and a time of 75 s. Then, glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were deposited under nitrogen protection via chemical vapor deposition. The flow rates of glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were 2 sccm, 0.2 sccm, 0.75 sccm, and 3.5 sccm, respectively. The reaction was carried out at 220 °C with a deposition rate of 20 nm / min and a coating thickness of 30 nm. After deposition, a taurine solution was uniformly coated, heated to 60 °C, and reacted for 1.5 h. The membrane was then washed and dried to obtain the modified PTFE porous nanofiber membrane.

[0041] From top to bottom, the following layers are laid out in sequence: 0.14mm thick nylon 66, 45μm thick TPU hot melt adhesive mesh, 25μm thick modified polytetrafluoroethylene porous nanofiber membrane (the outer side is unmodified, and the inner side is modified), 45μm thick TPU hot melt adhesive mesh, and 0.25mm thick polyester. The layers are then fed into a laminating machine for lamination at a set temperature of 130℃, a pressure of 0.11MPa, and a time of 11s. After lamination, the layers are laid flat to cool and set, resulting in a breathable and moisture-permeable nanofiber fabric.

[0042] Example 2

[0043] Slowly add 6g of polyethylene glycol to 80g of deionized water, place in a 60℃ water bath and stir magnetically for 2 hours until completely clear. Cool the solution to room temperature, add 5g of ammonium bicarbonate while stirring, and continue stirring for 8 minutes to suspend it evenly. Slowly add 90g of 65wt% polytetrafluoroethylene aqueous dispersion in 5 portions, stirring for 40 minutes each time. Then add 25g of anhydrous ethanol and continue stirring for 10 minutes. Let stand for 20 minutes to remove bubbles, filter, and obtain the electrospinning solution.

[0044] Release paper was fixed on a grounded collector, and electrospinning was performed using the electrospinning solution. The parameters were set as follows: voltage 14kV, spray distance 14cm, single-needle flow rate 0.4mL / h, and the precursor membrane density was controlled to reach 6g / m³. 2 Remove the precursor membrane, let it stand for 10 minutes, dry it at 80℃ for 30 minutes, heat it to 220℃ at a rate of 4℃ / min, release the gas for 40 minutes, raise the temperature to 370℃ under nitrogen protection, sinter it for 12 minutes, and cool it to obtain a polytetrafluoroethylene porous nanofiber membrane.

[0045] Dissolve 10g of taurine in 500mL of deionized water and adjust the pH to 9.2 to obtain a taurine solution.

[0046] The inner surface of a polytetrafluoroethylene porous nanofiber membrane was treated with oxygen plasma at a flow rate of 45 sccm, a power of 150 W, a pressure of 40 Pa, and a time of 80 s. Then, glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were deposited under nitrogen protection via chemical vapor deposition. The flow rates of glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were 2.4 sccm, 0.25 sccm, 0.85 sccm, and 4 sccm, respectively. The reaction was carried out at 240 °C with a deposition rate of 15 nm / min and a coating thickness of 30 nm. After deposition, a taurine solution was uniformly coated, heated to 55 °C, and reacted for 2 h. The membrane was then washed and dried to obtain the modified polytetrafluoroethylene porous nanofiber membrane.

[0047] From top to bottom, the following layers are laid out in sequence: 0.12mm thick nylon 66, 40μm thick TPU hot melt adhesive mesh, 28μm thick modified polytetrafluoroethylene porous nanofiber membrane (the outer side is unmodified, and the inner side is modified), 40μm thick TPU hot melt adhesive mesh, and 0.3mm thick polyester. The layers are then fed into a laminating machine for lamination at a set temperature of 135℃, a pressure of 0.1MPa, and a time of 10s. After lamination, the layers are laid flat to cool and set, resulting in a breathable and moisture-permeable nanofiber fabric.

[0048] Example 3

[0049] Slowly add 4g of polyethylene glycol to 50g of deionized water, place in a 50℃ water bath and stir magnetically for 4h until completely clear. Cool the solution to room temperature, add 3g of ammonium bicarbonate while stirring, and continue stirring for 8min to suspend it evenly. Slowly add 110g of 55wt% polytetrafluoroethylene aqueous dispersion in 5 portions, stirring for 20min each time. Then add 15g of anhydrous ethanol, continue stirring for 10min, let stand to degas for 10min, filter, and obtain the electrospinning solution.

[0050] Release paper was fixed on a grounded collector, and electrospinning was performed using the electrospinning solution. The parameters were set as follows: voltage 17kV, spray distance 16cm, single-needle flow rate 0.6mL / h, and the precursor membrane density was controlled to reach 8g / m³. 2 Remove the precursor membrane, let it stand for 10 minutes, dry it at 80℃ for 30 minutes, heat it to 220℃ at a rate of 2℃ / min, release the gas for 40 minutes, raise the temperature to 360℃ under nitrogen protection, sinter it for 18 minutes, and cool it to obtain a polytetrafluoroethylene porous nanofiber membrane.

[0051] Dissolve 8g of taurine in 500mL of deionized water and adjust the pH to 8.8 to obtain a taurine solution.

[0052] The inner surface of a polytetrafluoroethylene porous nanofiber membrane was treated with oxygen plasma at a flow rate of 30 sccm, a power of 100 W, a pressure of 70 Pa, and a time of 60 s. Then, glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were deposited under nitrogen protection via chemical vapor deposition. The flow rates of glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were 1.6 sccm, 0.18 sccm, 0.7 sccm, and 3 sccm, respectively. The reaction was carried out at 200 °C with a deposition rate of 20 nm / min and a coating thickness of 25 nm. After deposition, a taurine solution was uniformly coated, heated to 65 °C, and reacted for 1 h. The membrane was then washed and dried to obtain the modified polytetrafluoroethylene porous nanofiber membrane.

[0053] From top to bottom, the following layers are laid out in sequence: 0.16mm thick nylon 66, 50μm thick TPU hot melt adhesive mesh, 22μm thick modified polytetrafluoroethylene porous nanofiber membrane (the outer side is unmodified, and the inner side is modified), 50μm thick TPU hot melt adhesive mesh, and 0.2mm thick polyester. The layers are then fed into a laminating machine for lamination at a set temperature of 125℃, a pressure of 0.12MPa, and a time of 12s. After lamination, the layers are laid flat to cool and set, resulting in a breathable and moisture-permeable nanofiber fabric.

[0054] Example 4

[0055] Slowly add 5g of polyethylene glycol to 70g of deionized water and stir magnetically in a 55℃ water bath for 2.5h until completely clear. Cool the solution to room temperature and add 4.5g of ammonium bicarbonate while stirring. Continue stirring for 8min to suspend the solution evenly. Slowly add 105g of 60wt% polytetrafluoroethylene aqueous dispersion in 5 portions and stir for 25min. Then add 20g of anhydrous ethanol and stir for 10min. Let stand for 15min to remove bubbles and filter to obtain the electrospinning solution.

[0056] Release paper was fixed on a grounded collector, and electrospinning was performed using the electrospinning solution. The parameters were set as follows: voltage 16kV, spray distance 15cm, single-needle flow rate 0.5mL / h, and the precursor membrane density was controlled to reach 6.5g / m³. 2 Remove the precursor membrane, let it stand for 10 minutes, dry it at 80℃ for 30 minutes, heat it to 220℃ at a rate of 3℃ / min, release the gas for 40 minutes, raise the temperature to 365℃ under nitrogen protection, sinter it for 15 minutes, and cool it to obtain a polytetrafluoroethylene porous nanofiber membrane.

[0057] Dissolve 5g of taurine in 500mL of deionized water and adjust the pH to 8.8 to obtain a taurine solution.

[0058] The inner surface of a polytetrafluoroethylene (PTFE) porous nanofiber membrane was treated with oxygen plasma at a flow rate of 35 sccm, a power of 100 W, a pressure of 60 Pa, and a time of 90 s. Then, glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were deposited under nitrogen protection via chemical vapor deposition. The flow rates of glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were 1.9 sccm, 0.18 sccm, 0.7 sccm, and 3 sccm, respectively. The reaction was carried out at 200 °C with a deposition rate of 15 nm / min and a coating thickness of 35 nm. After deposition, a taurine solution was uniformly coated, heated to 65 °C, and reacted for 1.5 h. The membrane was then washed and dried to obtain the modified PTFE porous nanofiber membrane.

[0059] From top to bottom, the following layers are laid out in sequence: 0.15mm thick nylon 66, 45μm thick TPU hot melt adhesive mesh, 24μm thick modified polytetrafluoroethylene porous nanofiber membrane (the outer side is unmodified, and the inner side is modified), 40μm thick TPU hot melt adhesive mesh, and 0.3mm thick polyester. The layers are then fed into a laminating machine for lamination at a set temperature of 130℃, a pressure of 0.11MPa, and a time of 11s. After lamination, the layers are laid flat to cool and set, resulting in a breathable and moisture-permeable nanofiber fabric.

[0060] Example 5

[0061] Slowly add 4g of polyethylene glycol to 50g of deionized water, place in a 50℃ water bath and stir magnetically for 4h until completely clear. Cool the solution to room temperature, add 3g of ammonium bicarbonate while stirring, and continue stirring for 8min to suspend it evenly. Slowly add 110g of 55wt% polytetrafluoroethylene aqueous dispersion in 5 portions, stirring for 20min each time. Then add 15g of anhydrous ethanol, continue stirring for 10min, let stand to degas for 10min, filter, and obtain the electrospinning solution.

[0062] Release paper was fixed on a grounded collector, and electrospinning was performed using the electrospinning solution. The parameters were set as follows: voltage 17kV, spray distance 16cm, single-needle flow rate 0.6mL / h, and the precursor membrane density was controlled to reach 8g / m³. 2 Remove the precursor membrane, let it stand for 10 minutes, dry it at 80℃ for 30 minutes, heat it to 220℃ at a rate of 2℃ / min, release the gas for 40 minutes, raise the temperature to 360℃ under nitrogen protection, sinter it for 18 minutes, and cool it to obtain a polytetrafluoroethylene porous nanofiber membrane.

[0063] Dissolve 8g of taurine in 500mL of deionized water and adjust the pH to 8.8 to obtain a taurine solution.

[0064] The inner surface of a polytetrafluoroethylene (PTFE) porous nanofiber membrane was treated with oxygen plasma at a flow rate of 35 sccm, a power of 125 W, a pressure of 55 Pa, and a time of 75 s. Then, glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were deposited under nitrogen protection via chemical vapor deposition. The flow rates of glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were 2 sccm, 0.2 sccm, 0.75 sccm, and 3.5 sccm, respectively. The reaction was carried out at 220 °C with a deposition rate of 20 nm / min and a coating thickness of 30 nm. After deposition, a taurine solution was uniformly coated, heated to 60 °C, and reacted for 1.5 h. The membrane was then washed and dried to obtain the modified PTFE porous nanofiber membrane.

[0065] From top to bottom, the following layers are laid out in sequence: 0.13mm thick Nylon 66, 42μm thick TPU hot melt adhesive mesh, 26μm thick modified polytetrafluoroethylene porous nanofiber membrane (the outer side is unmodified, and the inner side is modified), 48μm thick TPU hot melt adhesive mesh, and 0.25mm thick polyester. The layers are then fed into a laminating machine for lamination at a set temperature of 130℃, a pressure of 0.11MPa, and a time of 11s. After lamination, the layers are laid flat to cool and set, resulting in a breathable and moisture-permeable nanofiber fabric.

[0066] Example 6

[0067] Slowly add 5g of polyethylene glycol to 60g of deionized water, place in a 55℃ water bath and stir magnetically for 3h until completely clear. Cool the solution to room temperature, add 4g of ammonium bicarbonate while stirring, and continue stirring for 8min to suspend it evenly. Slowly add 100g of 60wt% polytetrafluoroethylene aqueous dispersion in 5 portions, stirring for 30min each time. Then add 20g of anhydrous ethanol, continue stirring for 10min, let stand to degas for 15min, filter, and obtain the electrospinning solution.

[0068] Release paper was fixed on a grounded collector, and electrospinning was performed using the electrospinning solution. The parameters were set as follows: voltage 15kV, spray distance 15cm, single-needle flow rate 0.5mL / h, and the precursor membrane density was controlled to reach 7g / m³. 2 Remove the precursor membrane, let it stand for 10 minutes, dry it at 80℃ for 30 minutes, heat it to 220℃ at a rate of 3℃ / min, release the gas for 40 minutes, raise the temperature to 365℃ under nitrogen protection, sinter it for 15 minutes, and cool it to obtain a polytetrafluoroethylene porous nanofiber membrane.

[0069] Dissolve 5g of taurine in 500mL of deionized water and adjust the pH to 8 to obtain a taurine solution.

[0070] The inner surface of a polytetrafluoroethylene porous nanofiber membrane was treated with oxygen plasma at a flow rate of 30 sccm, a power of 100 W, a pressure of 70 Pa, and a time of 60 s. Then, glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were deposited under nitrogen protection via chemical vapor deposition. The flow rates of glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were 1.6 sccm, 0.18 sccm, 0.7 sccm, and 3 sccm, respectively. The reaction was carried out at 200 °C with a deposition rate of 20 nm / min and a coating thickness of 25 nm. After deposition, a taurine solution was uniformly coated, heated to 65 °C, and reacted for 1 h. The membrane was then washed and dried to obtain the modified polytetrafluoroethylene porous nanofiber membrane.

[0071] From top to bottom, the following layers are laid out in sequence: 0.16mm thick nylon 66, 45μm thick TPU hot melt adhesive mesh, 25μm thick modified polytetrafluoroethylene porous nanofiber membrane (the outer side is unmodified, and the inner side is modified), 45μm thick TPU hot melt adhesive mesh, and 0.2mm thick polyester. The layers are then fed into a laminating machine for lamination at a set temperature of 125℃, a pressure of 0.12MPa, and a time of 12s. After lamination, the layers are laid flat to cool and set, resulting in a breathable and moisture-permeable nanofiber fabric.

[0072] Example 7

[0073] Slowly add 5g of polyethylene glycol to 60g of deionized water, place in a 55℃ water bath and stir magnetically for 3h until completely clear. Cool the solution to room temperature, add 4g of ammonium bicarbonate while stirring, and continue stirring for 8min to suspend it evenly. Slowly add 100g of 60wt% polytetrafluoroethylene aqueous dispersion in 5 portions, stirring for 30min each time. Then add 20g of anhydrous ethanol, continue stirring for 10min, let stand to degas for 15min, filter, and obtain the electrospinning solution.

[0074] Release paper was fixed on a grounded collector, and electrospinning was performed using the electrospinning solution. The parameters were set as follows: voltage 15kV, spray distance 15cm, single-needle flow rate 0.5mL / h, and the precursor membrane density was controlled to reach 7g / m³. 2 Remove the precursor membrane, let it stand for 10 minutes, dry it at 80℃ for 30 minutes, heat it to 220℃ at a rate of 3℃ / min, release the gas for 40 minutes, raise the temperature to 365℃ under nitrogen protection, sinter it for 15 minutes, and cool it to obtain a polytetrafluoroethylene porous nanofiber membrane.

[0075] The inner surface of a polytetrafluoroethylene porous nanofiber membrane was treated with oxygen plasma at a flow rate of 30 sccm, a power of 100 W, a pressure of 70 Pa, and a time of 60 s. Then, glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were deposited under nitrogen protection via chemical vapor deposition. The flow rates of glycidyl methacrylate, ethylene glycol dimethacrylate, and DTBP were 1.6 sccm, 0.18 sccm, 0.7 sccm, and 3 sccm, respectively. The reaction was carried out at 200 °C with a deposition rate of 20 nm / min, and the coating thickness was controlled to be 25 nm. After deposition, the membrane was washed and dried to obtain the modified polytetrafluoroethylene porous nanofiber membrane.

[0076] From top to bottom, the following layers are laid out in sequence: 0.16mm thick nylon 66, 45μm thick TPU hot melt adhesive mesh, 25μm thick modified polytetrafluoroethylene porous nanofiber membrane (the outer side is unmodified, and the inner side is modified), 45μm thick TPU hot melt adhesive mesh, and 0.2mm thick polyester. The layers are then fed into a laminating machine for lamination at a set temperature of 125℃, a pressure of 0.12MPa, and a time of 12s. After lamination, the layers are laid flat to cool and set, resulting in a breathable and moisture-permeable nanofiber fabric.

[0077] The present invention also includes comparative examples and related experiments.

[0078] Comparative Example 1

[0079] The only difference between Comparative Example 1 and Example 1 is that ammonium bicarbonate is not added in step S1. The other components and preparation methods are the same as in Example 1, and a breathable and moisture-permeable nanofiber fabric is prepared.

[0080] Comparative Example 2

[0081] The difference between Comparative Example 2 and Example 1 is that no modified polytetrafluoroethylene porous nanofiber membrane was prepared. Instead, a polytetrafluoroethylene porous nanofiber membrane was directly used for step S4. The other components and preparation methods were the same as in Example 1, and a breathable and moisture-permeable nanofiber fabric was obtained.

[0082] Comparative Example 3

[0083] The difference between Comparative Example 3 and Example 1 is that chemical vapor deposition is not performed in step S3. Instead, a 1.5 wt% polyvinyl alcohol aqueous solution is used to dip-coat the inner side of the polytetrafluoroethylene porous nanofiber membrane to perform hydrophilic modification. The other components and preparation methods are the same as in Example 1, and a breathable and moisture-permeable nanofiber fabric is prepared.

[0084] Performance testing

[0085] The air permeability of the breathable and moisture-permeable nanofiber fabrics prepared in Examples 1-7 and Comparative Examples 1-3 was tested according to GB / T 5453-1997 "Textiles - Determination of Air Permeability of Fabrics"; the moisture permeability of the breathable and moisture-permeable nanofiber fabrics prepared in Examples 1-7 and Comparative Examples 1-3 was tested according to GB / T 12704.1-2009 "Textiles - Test Methods for Moisture Permeability of Fabrics - Part 1: Moisture Absorption Method"; the moisture permeability was calculated in g / (m³). 2 •24h); The waterproof performance of the breathable and moisture-permeable nanofiber fabrics prepared in Examples 1-7 and Comparative Examples 1-3 was tested according to GB / T 4744-2013 "Test and Evaluation of Waterproof Performance of Textiles - Hydrostatic Pressure Method"; The results of the above tests are shown in Table 1.

[0086] Table 1

[0087]

[0088] As shown in Table 1 above, the air permeability is 38 mm / s for Comparative Example 1 and 65 mm / s for Example 1, representing an improvement of approximately 71.1%; the moisture permeability is 8200 g / (m³) for Comparative Example 1. 2 •24h), Example 1 is 10500g / (m 2 • 24h), an increase of approximately 28.0%, indicating that ammonium bicarbonate helps prevent localized densification of interconnected channels, thus improving the breathability and moisture permeability of the nanofiber fabric; Comparative Example 2 had a moisture permeability of 8600 g / (m²). 2•24h), Example 1 is 10500g / (m 2 (24h) In Example 1, the improvement was about 22.1%, indicating that modification on the inner side of the polytetrafluoroethylene porous nanofiber membrane can promote the improvement of the moisture permeability of the prepared nanofiber fabric. In Comparative Example 3, the air permeability and moisture permeability of the nanofiber fabric prepared were significantly reduced compared with Example 1, but the hydrostatic pressure was improved, indicating that the continuous adhesive layer formed by the polyvinyl alcohol aqueous solution sacrificed the air permeability and moisture permeability of the nanofiber fabric at the cost of pore blockage.

[0089] According to GB / T 21196.2-2007 "Determination of abrasion resistance of fabrics by the Martindale process - Part 2: Determination of specimen breakage", the breathable and moisture-permeable nanofiber fabrics prepared in Examples 1-7 and Comparative Examples 1-3 were subjected to abrasion resistance tests. According to GB / T 8629-2017 "Home washing and drying procedures for textile testing", the breathable and moisture-permeable nanofiber fabrics prepared in Examples 1-7 and Comparative Examples 1-3 were subjected to wash resistance tests. After 20 washes, the air permeability and moisture permeability tests were conducted again, and the retention rate was calculated. The results of the above tests are summarized in Table 2.

[0090] Table 2

[0091]

[0092] As shown in Table 2, the washability and moisture retention rates are as follows: Comparative Example 2 has a rate of 69.8%, while Example 1 has a rate of 93.3%, with Example 1 being 23.5 percentage points higher. This indicates that the pore walls of the unmodified polytetrafluoroethylene porous nanofiber membrane are more easily blocked after washing, leading to a significant decrease in its moisture permeability. Simultaneously, its abrasion resistance is also significantly reduced, indicating that the modified polytetrafluoroethylene porous nanofiber membrane prepared in this scheme can significantly improve the interlayer bonding and washability / abrasion resistance of the nanofiber fabric, thereby improving the durability of the nanofiber fabric. Comparative Example 3 has a moisture retention rate of 72.6% and an air permeability retention rate of 80.1%, both significantly lower than Example 1. This indicates that the chemical vapor deposition modification of the polytetrafluoroethylene porous nanofiber membrane in this scheme can avoid swelling / migration / cracking caused by liquid phase coatings such as polyvinyl alcohol, thus preventing the deterioration of the air permeability and moisture permeability of the nanofiber fabric.

[0093] The difference between Example 7 and Example 6 is that in Example 7, when preparing the modified polytetrafluoroethylene porous nanofiber membrane, the inner surface of the polytetrafluoroethylene porous nanofiber membrane was not coated with taurine aqueous solution after deposition. As can be seen from the data in Tables 1 and 2, the moisture permeability and moisture permeability retention rate after washing of Example 7 both decreased significantly, indicating that taurine can improve the adsorption capacity of the pore walls of the polytetrafluoroethylene porous nanofiber membrane for water, accelerate moisture transfer, and improve the moisture permeability of the nanofiber fabric.

[0094] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a breathable and moisture-permeable nanofiber fabric, characterized in that, Includes the following steps: Step S1: Slowly add polyethylene glycol to deionized water, heat and stir until dissolved, cool, add ammonium bicarbonate, stir evenly, slowly add polytetrafluoroethylene aqueous dispersion, then add anhydrous ethanol, let stand to remove bubbles, filter, and obtain electrospinning stock solution; the heating and stirring temperature is 50-60℃, and the time is 2-4h; the concentration of polytetrafluoroethylene aqueous dispersion is 55-65wt%; the electrospinning stock solution includes the following components in parts by weight: 50-80 parts deionized water, 4-6 parts polyethylene glycol, 90-110 parts polytetrafluoroethylene aqueous dispersion, and 15-25 parts anhydrous ethanol; Step S2: Fix the release paper onto the grounded collector, and perform electrospinning using the electrospinning solution to obtain a precursor membrane. After electrospinning, sinter under nitrogen protection, and then cool to obtain a polytetrafluoroethylene porous nanofiber membrane; the density of the precursor membrane is 6-8 g / m³. 2 The sintering temperature is 360-370℃, and the time is 12-18 minutes. Step S3: The inner surface of the polytetrafluoroethylene porous nanofiber membrane is treated with oxygen plasma, and then chemical vapor deposition is performed using glycidyl methacrylate, ethylene glycol dimethacrylate and DTBP under nitrogen protection. After deposition, the membrane is washed and dried to obtain the modified polytetrafluoroethylene porous nanofiber membrane. Step S4: Lay out the following layers from top to bottom in the following order: Nylon 66, TPU hot melt adhesive mesh, modified polytetrafluoroethylene porous nanofiber membrane, TPU hot melt adhesive mesh, and polyester. Then, put them into a lamination equipment for lamination. After lamination, lay them flat to cool and shape them to obtain a breathable and moisture-permeable nanofiber fabric.

2. The method for preparing a breathable and moisture-permeable nanofiber fabric according to claim 1, characterized in that, In step S2, the electrospinning voltage is 14-17kV, the spray distance is 14-16cm, and the single needle flow rate is 0.4-0.6mL / h.

3. The method for preparing a breathable and moisture-permeable nanofiber fabric according to claim 1, characterized in that, In step S3, the oxygen flow rate of the oxygen plasma treatment is 30-45 sccm, the power is 100-150W, the pressure is 40-70Pa, and the time is 60-90s.

4. The method for preparing a breathable and moisture-permeable nanofiber fabric according to claim 1, characterized in that, In step S3, the flow rate of glycidyl methacrylate is 1.6-2.4 sccm, the flow rate of ethylene glycol dimethacrylate is 0.18-0.25 sccm, the flow rate of DTBP is 0.7-0.85 sccm, and the flow rate of N2 is 3-4 sccm.

5. The method for preparing a breathable and moisture-permeable nanofiber fabric according to claim 1, characterized in that, In step S3, the deposition rate is 15-20 nm / min, the temperature is 200-240℃, and the deposition thickness is 25-35 nm.

6. The method for preparing a breathable and moisture-permeable nanofiber fabric according to claim 1, characterized in that, In step S3, after deposition, a taurine solution is uniformly coated and heated to react; the taurine solution is prepared by dissolving taurine in deionized water and adjusting the pH to 8.8-9.2; the heating reaction temperature is 55-65℃ and the time is 1-2h.

7. The method for preparing a breathable and moisture-permeable nanofiber fabric according to claim 1, characterized in that, In step S4, the lamination temperature is 125-135℃, the pressure is 0.1-0.12MPa, and the time is 10-12s; the thickness of nylon 66 is 0.12-0.16mm, the thickness of TPU hot melt adhesive mesh is 40-50μm, the thickness of modified polytetrafluoroethylene porous nanofiber membrane is 22-28μm, and the thickness of polyester is 0.2-0.3mm.

8. A breathable and moisture-wicking nanofiber fabric, characterized in that, The breathable and moisture-permeable nanofiber fabric was prepared using the preparation method described in any one of claims 1-7.

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