A micro-nanofiber membrane, a preparation method and application thereof

Abstract

This invention provides a micro / nanofiber membrane, its preparation method, and its applications. The micro / nanofiber membrane of this invention is formed by interweaving submicron and nanofibers, wherein the submicron and nanofibers are polyamide 6 fibers. The membrane contains an aqueous fluorinated material and an inorganic conductive agent. The larger micro / nanofibers, due to their increased diameter, have a larger cross-sectional area, thereby increasing their ability to withstand external forces and enhancing their mechanical properties. The microporous structure created by the finer nanofibers effectively prevents the permeation of liquid water, while these micropores are small enough to allow water vapor to pass through, ensuring good air permeability and moisture permeability. Therefore, the micro / nanofiber membrane possesses a micro / nanostructure that promotes thermal and moisture balance, endowing the fiber membrane with excellent mechanical properties. Its small and numerous pores also enhance liquid repellency and air permeability. This invention also provides a method for preparing the micro / nanofiber membrane and its applications.

Description

Technical Field

[0001] This invention belongs to the field of fiber membrane technology, specifically relating to a micro / nanofiber membrane, its preparation method, and its application. Background Technology

[0002] Traditional cooling systems such as air conditioners and fans account for approximately 20% of total electricity consumption. These systems also emit significant amounts of greenhouse gases, exacerbating global warming. This massive energy consumption stems from inefficient energy use. Traditional cooling systems like air conditioners and fans can only regulate the temperature of the entire building space, while the human body requires a smaller temperature regulation area, leading to energy waste. Furthermore, traditional cooling systems are only suitable for indoor environments and cannot be applied to outdoor environments.

[0003] Compared to traditional space cooling, radiative cooling technology relies primarily on specific materials and structural designs with high solar reflectivity and high infrared emissivity to optimize surface radiation characteristics. This maximizes the resistance to solar energy absorption, resulting in radiative heat dissipation exceeding solar absorption, allowing heat to be released into the environment in the form of radiation, thus achieving a cooling effect. Therefore, imbuing fabrics with radiative cooling properties can not only regulate the wearer's body heat but also, by applying the cooling system to the outdoor environment, gradually replace traditional space cooling technologies, contributing to energy conservation and mitigating the greenhouse effect. People working outdoors need to maintain thermal comfort and avoid the effects of harsh environments. Waterproof and breathable fabrics not only resist rain and effectively prevent moisture penetration but also possess excellent breathability, allowing sweat to evaporate, keeping the body dry and comfortable. This avoids the stuffy environment caused by trapped sweat, which can lead to heatstroke, heat exhaustion, itchy skin, and infections. By combining radiative cooling and waterproof / breathable properties into the same fabric, it can effectively cope with hot environments in high temperatures and keep dry in humid environments, offering multifunctional wearing advantages and promoting health and comfort during activities. In related technologies, coated textiles with passive radiative cooling function are prepared by dissolving polyvinylidene fluoride-hexafluoropropylene copolymer, polydimethylsiloxane, polymethyl methacrylate, etc., in an organic solvent, adding nano-silica as a pore-forming agent, and stirring evenly to obtain a dispersion. This dispersion is then poured onto a template with micron-level protrusions on its surface, and a substrate is attached to the dispersion to prepare a coating substrate. Finally, the pore-forming agent is removed from the prepared coating substrate to obtain the coated textile. This technology only coats the surface of cotton or nylon fabric with a radiative cooling dispersion. With repeated use, the coating will inevitably wear down, reducing its radiative cooling performance and durability. Other researchers have prepared waterproof and breathable TPU composite films using self-made devices. First, turn on the heating device; after the temperature reaches the set temperature, turn on the motor and feed TPU into the hopper. The TPU flows forward under the action of the screw until it reaches the annular melt flow channel inside the nozzle. Turn on the hot air gun and introduce hot air into the central air inlet of the nozzle; ensure that the melt flows steadily into the spinning box. In the box, the melt is filtered and pressed into the porous spinneret to be sprayed out as a fine melt stream. Then, it is quickly condensed into fibers by the cold air blown out by the temperature-controlled air box. This technology mainly turns thermoplastic polyurethane into a melt for spinning, which belongs to melt spinning.

[0004] Currently, commercially available functional fabrics suffer from drawbacks such as overly complex preparation methods, high costs, environmental pollution, and poor durability. Therefore, there is an urgent need to develop a novel nanofiber membrane that can not only address personal thermal comfort issues but also provide waterproof and breathable properties, thereby ensuring thermal and moisture comfort for the human body. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a micro / nanofiber membrane that can promote thermal and moisture balance, endow the fiber membrane with excellent mechanical properties, and whose small and numerous pore structure can also enhance liquid repellency and air permeability.

[0006] The present invention also provides a method for preparing micro / nanofiber membranes.

[0007] The present invention also provides a functional garment prepared from a micro / nanofiber membrane.

[0008] A first aspect of the present invention provides a micro / nanofiber membrane, the micro / nanofiber membrane being formed by interweaving submicron-sized fibers and nano-sized fibers, wherein an aqueous fluorinated material and an inorganic conductive agent are distributed in the micro / nanofiber membrane.

[0009] One of the technical solutions of the present invention concerning micro / nanofiber membranes has at least the following beneficial effects:

[0010] The micro / nanofiber membrane of this invention possesses a micro / nanostructure. The larger micro / nanofibers, due to their increased diameter, have a larger cross-sectional area, thereby increasing their ability to withstand external forces and enhancing their mechanical properties. The microporous structure created by the finer nanofibers effectively prevents the permeation of liquid water, while these micropores are small enough to allow water vapor to pass through, ensuring good air permeability and moisture permeability. Therefore, the micro / nanofiber membrane, with its micro / nanostructure, promotes thermal and moisture balance, endows the fiber membrane with excellent mechanical properties, and its small and numerous pores also enhance liquid repellency and air permeability.

[0011] Waterborne fluorinated materials contain fluorocarbon segments, which are highly hydrophobic, making the material surface less susceptible to water contact. Simultaneously, the migration and enrichment of fluorine into the nanofiber membrane surface reduces the surface energy, meaning lower surface tension and increased hydrophobicity. This results in water droplets forming a smoother shape on the surface, making them less prone to adsorption or penetration, thus enhancing hydrophobic properties. Compared to alkane and siloxane segments, fluorocarbon segments exhibit superior hydrophobicity. Furthermore, in fluorocarbon segments, fluorine atoms have higher electronegativity than carbon atoms, resulting in stronger polarity. This strengthens intermolecular forces and reduces intermolecular distance, leading to improved radiative heat transfer. Fluorocarbon segments also possess high reflectivity, enhancing heat dissipation and improving radiative cooling effects.

[0012] Inorganic conductive agents increase the charge density and conductivity of the solution during the micro / nanofiber membrane fabrication process, thereby generating excellent tensile strength. This excellent tensile strength enables the generation of fine nanofibers from the polymer fluid jet. As the spinning time increases, the fine nanofibers eventually accumulate to form an interconnected "web".

[0013] According to some embodiments of the present invention, the submicron-sized fiber may be polyamide 6 fiber.

[0014] According to some embodiments of the present invention, the nanofibers may be polyamide 6 fibers.

[0015] Polyamide 6 is a material with high solar reflectivity and excellent infrared transmittance. It possesses high solar reflectivity and infrared emissivity not found in other materials, enabling it to radiate infrared radiation from the human body to outer space to the maximum extent possible, thus achieving a cooling effect. The demand for smart fabrics that can automatically regulate temperature and adapt to climate change is growing, and the use of polyamide 6 fibers meets this need.

[0016] According to some embodiments of the present invention, the water-based fluorinated material includes at least one of C8 waterproofing agent and C6 waterproofing agent.

[0017] According to some embodiments of the present invention, the waterborne fluorinated material includes at least one of fluorinated acrylic resin, perfluorooctyl ethyl acrylate, and (N-methylperfluorohexylsulfonamide) ethyl acrylate.

[0018] According to some embodiments of the present invention, the inorganic conductive agent includes at least one selected from silver nitrate, tetrabutylammonium chloride, dodecyltrimethylammonium bromide, magnesium chloride, and lithium chloride.

[0019] According to some embodiments of the present invention, the diameter of the submicron fiber is 130 nm to 190 nm.

[0020] According to some embodiments of the present invention, the diameter of the submicron fiber can be any value of 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, or a range of any two.

[0021] According to some embodiments of the present invention, the diameter of the nanofiber is 35 nm to 55 nm.

[0022] According to some embodiments of the present invention, the diameter of the nanofiber can be any value of 35nm, 40nm, 45nm, 50nm, 55nm, or a range of any combination thereof.

[0023] A second aspect of the present invention provides a method for preparing the aforementioned micro / nanofiber membrane, comprising the steps of preparing a high-concentration spinning solution and a low-concentration spinning solution respectively, and forming the micro / nanofiber membrane by electrospinning.

[0024] One technical solution of the present invention relating to the preparation method of micro / nanofiber membranes has at least the following beneficial effects:

[0025] The micro / nanofiber membrane prepared by the method of this invention possesses a micro / nanostructure. The high concentration of the spinning solution results in higher viscosity, which slows down the stretching speed of the fibers during stretching, thus increasing the fiber diameter. The increased diameter of the coarser fibers increases their cross-sectional area, thereby enhancing their ability to withstand external forces and improving their mechanical properties. Adding a certain amount of inorganic substances to the low-concentration spinning solution increases the charge density and conductivity of the solution, resulting in excellent tensile strength. This excellent tensile strength generates fine nanofibers from the polymer fluid jet. As the spinning time increases, these fine nanofibers accumulate to form an interconnected "web." The microporous structure created by these fine nanofibers effectively prevents the penetration of liquid water, while the pores are small enough to allow water vapor to pass through, ensuring good air and moisture permeability. Therefore, fibers with a micro / nanostructure promote thermal and moisture balance, endow the fiber membrane with excellent mechanical properties, and their numerous small pores also enhance liquid repellency and air permeability.

[0026] This invention prepares a fiber membrane with both radiative cooling and waterproof / breathable properties by formulating different concentrations of alcohol-soluble polyamide 6 (PA6) (high-concentration spinning solution and low-concentration spinning solution), adding water-based fluorine-containing materials and inorganic conductive agents, and using electrospinning technology (i.e., spinning with high-concentration and low-concentration spinning solutions simultaneously). This results in the formation of micro- and nano-structured fibers, namely, coarser fibers and finer mesh fibers.

[0027] Compared with the existing melting method, the present invention can dissolve the raw materials in ethanol to prepare the spinning solution, and use electrospinning technology to prepare the fiber membrane. The fiber membrane prepared by electrospinning technology has the characteristics of small fiber diameter, large specific surface area, porosity, light weight and excellent mechanical properties. The fiber membrane with radiation cooling and waterproof and breathable properties can be made in one step. The process is simple and the operation is simple, which greatly improves the production efficiency and enables mass production.

[0028] Compared with existing technologies, this invention prepares fiber membranes by formulating a spinning solution and using electrospinning technology. It utilizes the high solar reflectance and high infrared emission characteristics of polyamide 6 and the fluorocarbon segments in water-based fluorinated materials to enhance heat dissipation, thereby achieving radiative cooling performance and thus exhibiting better durability.

[0029] The preparation method of the present invention does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are readily available, the production cost is low, and it is easy to industrialize.

[0030] According to some embodiments of the present invention, the high-concentration spinning solution contains 14wt% to 15wt% of alcohol-soluble polyamide 6 and 3wt% to 9wt% of the aqueous fluorinated material.

[0031] According to some embodiments of the present invention, the concentration of alcohol-soluble polyamide 6 in the high-concentration spinning solution can be any value or a range formed by any combination of 14.1 wt%, 14.2 wt%, 14.3 wt%, 14.4 wt%, 14.5 wt%, 14.6 wt%, 14.7 wt%, 14.8 wt%, 14.9 wt%, and 15 wt%.

[0032] According to some embodiments of the present invention, the concentration of the aqueous fluorinated material in the high-concentration spinning solution can be any value or a range formed by any two of the following: 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%.

[0033] According to some embodiments of the present invention, the low-concentration spinning solution contains 4 wt% to 5 wt% of alcohol-soluble polyamide 6, 3 wt% to 9 wt% of the aqueous fluorinated material and 1 wt% to 2 wt% of the inorganic conductive agent.

[0034] According to some embodiments of the present invention, the concentration of alcohol-soluble polyamide 6 in the low-concentration spinning solution can be any value or a range formed by any combination of 4.1wt%, 4.2wt%, 4.3wt%, 4.4wt%, 4.5wt%, 4.6wt%, 4.7wt%, 4.8wt%, 4.9wt%, and 5wt%.

[0035] According to some embodiments of the present invention, the concentration of the aqueous fluorinated material in the low-concentration spinning solution can be any value or a range formed by any two of the following: 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%.

[0036] According to some embodiments of the present invention, the concentration of the inorganic conductive agent in the low-concentration spinning solution can be any value or a range formed by any combination of 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, and 2wt%.

[0037] Low-concentration spinning solutions are used to spin fine fibers with smaller diameters. Inorganic conductive agents are added to the low-concentration spinning solution to increase its charge density and conductivity, generating excellent tensile strength during electrospinning and further forming fine fibers. High-concentration spinning solutions produce larger diameter fibers; the combination of both is necessary to form a micro / nanostructured fiber membrane. Therefore, inorganic conductive agents can only be added to low-concentration spinning solutions.

[0038] According to some embodiments of the present invention, the voltage in the electrospinning process can be 25kV to 30kV.

[0039] According to some embodiments of the present invention, the infusion rate in the electrospinning process can be 1.8 mL / h to 2 mL / h.

[0040] According to some embodiments of the present invention, in the electrospinning, the receiving distance during spinning can be 14cm to 16cm.

[0041] According to some embodiments of the present invention, the spinning temperature during electrospinning can be 25°C to 27°C.

[0042] According to some embodiments of the present invention, the relative humidity during electrospinning can be 40% to 50%.

[0043] According to some embodiments of the present invention, the solvent in the high-concentration spinning solution and the low-concentration spinning solution may be anhydrous ethanol.

[0044] According to some embodiments of the present invention, the preparation method of micro / nanofiber membranes may be as follows:

[0045] S1. Prepare a high-concentration spinning solution by mixing 14wt% to 15wt% alcohol-soluble polyamide 6 and 3wt% to 9wt% aqueous fluorinated material in a solvent.

[0046] S2. Prepare a low-concentration spinning solution by mixing 4wt% to 5wt% alcohol-soluble polyamide, 3wt% to 9wt% aqueous fluorinated material, and 1wt% to 2wt% inorganic substance in a solvent.

[0047] S3. Using glossy paper as the receiving substrate for electrospinning, the mixed solution is spun onto the glossy paper by electrospinning to obtain a nanofiber membrane with radiation cooling properties and waterproof and breathable properties.

[0048] S4. Remove the prepared fiber membrane and place it in an 80℃ drying oven for 2 hours to remove residual solvent, thus obtaining a nanofiber membrane with radiation cooling and waterproof and breathable properties.

[0049] A third aspect of the present invention provides a functional garment prepared from the micro / nanofiber membrane of the present invention.

[0050] One of the technical solutions of this invention concerning functional clothing has at least the following beneficial effects:

[0051] Excellent mechanical properties: The micro-nano structured fiber membrane is made up of submicron and nano-sized fibers interwoven together, which increases the load-bearing capacity and durability of the fiber membrane, enabling it to exhibit excellent mechanical properties when subjected to external forces.

[0052] Waterproof and breathable properties: The micro / nanofiber membrane contains water-based fluorinated materials, which improves the material's hydrophobicity, causing water droplets to form a smooth shape on the surface, thus enhancing waterproof performance. At the same time, the microporous structure generated by the nanofibers effectively prevents the penetration of liquid water, yet is small enough to allow water vapor to pass through, ensuring breathability.

[0053] Radiative cooling effect: The micro / nanofiber membrane contains fluorocarbon segments, which have high reflectivity and can enhance the heat dissipation of the material, thereby improving the radiative cooling effect. In addition, the polarity of the fluorocarbon segments and the reduction of the intermolecular distance can also improve the radiative heat transfer performance.

[0054] Improved electrical conductivity: The addition of inorganic conductive agents improves the electrical conductivity of micro / nanofiber membranes, which helps to enhance the tensile strength and stability of the fiber membranes, making them more suitable for the preparation of various functional garments.

[0055] In summary, functional garments made from the aforementioned micro / nanofiber membranes may possess a variety of beneficial effects, such as waterproofing and breathability, radiative cooling, excellent mechanical properties, and improved electrical conductivity, making them promising for applications in outdoor sports, protective clothing, and other fields. Detailed Implementation

[0056] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0057] In a first aspect, some embodiments of the present invention provide a micro / nanofiber membrane, which is formed by interweaving submicron-sized and nano-sized fibers, and contains an aqueous fluorinated material and an inorganic conductive agent.

[0058] It is understood that the micro / nanofiber membrane of the present invention possesses a micro / nanostructure. The larger micro / nanofibers, due to their increased diameter, have a larger cross-sectional area, thereby increasing their ability to withstand external forces and enhancing their mechanical properties. The microporous structure created by the finer nanofibers effectively prevents the permeation of liquid water, while these micropores are small enough to allow water vapor to pass through, ensuring good air permeability and moisture permeability. Therefore, the micro / nanofiber membrane possesses a micro / nanostructure that promotes thermal and moisture balance, endowing the fiber membrane with excellent mechanical properties. Its small and numerous pores also enhance liquid repellency and air permeability.

[0059] Waterborne fluorinated materials contain fluorocarbon segments, which are highly hydrophobic, making the material surface less susceptible to water contact. Simultaneously, the migration and enrichment of fluorine into the nanofiber membrane surface reduces the surface energy, meaning lower surface tension and increased hydrophobicity. This results in water droplets forming a smoother shape on the surface, making them less prone to adsorption or penetration, thus enhancing hydrophobic properties. Compared to alkane and siloxane segments, fluorocarbon segments exhibit superior hydrophobicity. Furthermore, in fluorocarbon segments, fluorine atoms have higher electronegativity than carbon atoms, resulting in stronger polarity. This strengthens intermolecular forces and reduces intermolecular distance, leading to improved radiative heat transfer. Fluorocarbon segments also possess high reflectivity, enhancing heat dissipation and improving radiative cooling effects.

[0060] Inorganic conductive agents increase the charge density and conductivity of the solution during the micro / nanofiber membrane fabrication process, thereby generating excellent tensile strength. This excellent tensile strength enables the generation of fine nanofibers from the polymer fluid jet. As the spinning time increases, the fine nanofibers eventually accumulate to form an interconnected "web".

[0061] In conjunction with the first aspect, in some embodiments of the present invention, the submicron fibers may be polyamide 6 fibers.

[0062] In conjunction with the first aspect, in some embodiments of the present invention, the nanofibers may be polyamide 6 fibers.

[0063] Polyamide 6 is a material with high solar reflectivity and excellent infrared transmittance, capable of maximizing the transmission of infrared radiation from the human body into outer space, thereby achieving a cooling effect. The demand for smart fabrics that can automatically regulate temperature and adapt to climate change is growing, and the use of polyamide 6 fibers meets this need.

[0064] In conjunction with the first aspect, in some embodiments of the present invention, the water-based fluorinated material includes at least one of C8 waterproofing agent and C6 waterproofing agent.

[0065] In conjunction with the first aspect, in some embodiments of the present invention, the waterborne fluorinated material includes at least one of fluorinated acrylic resin, perfluorooctyl ethyl acrylate, and (N-methylperfluorohexylsulfonamide) ethyl acrylate.

[0066] In conjunction with the first aspect, in some embodiments of the present invention, the inorganic conductive agent includes at least one selected from silver nitrate, tetrabutylammonium chloride, dodecyltrimethylammonium bromide, magnesium chloride, and lithium chloride.

[0067] In conjunction with the first aspect, in some embodiments of the present invention, the diameter of the submicron fiber is 130 nm to 190 nm.

[0068] In conjunction with the first aspect, in some embodiments of the present invention, the diameter of the submicron fiber can be any value of 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, or a range of any two of these values.

[0069] In conjunction with the first aspect, in some embodiments of the present invention, the diameter of the nanofibers is 35 nm to 55 nm.

[0070] In conjunction with the first aspect, in some embodiments of the present invention, the diameter of the nanofiber can be any value of 35nm, 40nm, 45nm, 50nm, 55nm, or a range of any two of these values.

[0071] In a second aspect, some embodiments of the present invention provide a method for preparing micro / nanofiber membranes, comprising the steps of preparing high-concentration spinning solutions and low-concentration spinning solutions respectively, and forming micro / nanofiber membranes by electrospinning.

[0072] It is understood that the micro / nanofiber membrane prepared by the method of this invention possesses a micro / nano structure. The high concentration of the spinning solution results in higher viscosity, which slows down the stretching speed of the fibers during stretching, thus increasing the fiber diameter. The increased diameter of the coarser fibers increases their cross-sectional area, thereby increasing their ability to withstand external forces and enhancing their mechanical properties. Adding a certain amount of inorganic substances to the low-concentration spinning solution can increase the charge density and conductivity of the solution, resulting in excellent tensile strength. This excellent tensile strength can generate fine nanofibers from the polymer fluid jet. As the spinning time increases, these fine nanofibers accumulate to form an interconnected "web." The microporous structure generated by these fine nanofibers effectively prevents the penetration of liquid water, while the micropores are small enough to allow water vapor to pass through, ensuring good air permeability and moisture permeability. Therefore, fibers with micro / nano structures can promote thermal and moisture balance, endow the fiber membrane with excellent mechanical properties, and their small and numerous pores can also enhance liquid repellency and air permeability.

[0073] This invention prepares a fiber membrane with both radiative cooling and waterproof / breathable properties by formulating different concentrations of alcohol-soluble polyamide 6 (PA6) (high-concentration spinning solution and low-concentration spinning solution), adding water-based fluorine-containing materials and inorganic conductive agents, and using electrospinning technology (i.e., spinning with high-concentration and low-concentration spinning solutions simultaneously). This results in the formation of micro- and nano-structured fibers, namely, coarser fibers and finer mesh fibers.

[0074] Compared with the existing melting method, the present invention can dissolve the raw materials in ethanol to prepare the spinning solution, and use electrospinning technology to prepare the fiber membrane. The fiber membrane prepared by electrospinning technology has the characteristics of small fiber diameter, large specific surface area, porosity, light weight and excellent mechanical properties. The fiber membrane with radiation cooling and waterproof and breathable properties can be made in one step. The process is simple and the operation is simple, which greatly improves the production efficiency and enables mass production.

[0075] Compared with existing technologies, this invention prepares fiber membranes by formulating a spinning solution and using electrospinning technology. It utilizes the high solar reflectance and high infrared emission characteristics of polyamide 6 and the fluorocarbon segments in water-based fluorinated materials to enhance heat dissipation, thereby achieving radiative cooling performance and thus exhibiting better durability.

[0076] The preparation method of the present invention does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are readily available, the production cost is low, and it is easy to industrialize.

[0077] In conjunction with the second aspect, in some embodiments of the present invention, the high-concentration spinning solution contains 14wt% to 15wt% of alcohol-soluble polyamide 6 and 3wt% to 9wt% of aqueous fluorinated material.

[0078] In conjunction with the second aspect, in some embodiments of the present invention, the concentration of alcohol-soluble polyamide 6 in the high-concentration spinning solution can be any value or a range formed by any two of 14.1 wt%, 14.2 wt%, 14.3 wt%, 14.4 wt%, 14.5 wt%, 14.6 wt%, 14.7 wt%, 14.8 wt%, 14.9 wt%, and 15 wt%.

[0079] In conjunction with the second aspect, in some embodiments of the present invention, the concentration of the aqueous fluorinated material in the high-concentration spinning solution can be any value or a range formed by any two of the following: 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, and 9wt%.

[0080] In conjunction with the second aspect, in some embodiments of the present invention, the low-concentration spinning solution contains 4 wt% to 5 wt% of alcohol-soluble polyamide 6, 3 wt% to 9 wt% of aqueous fluorinated material, and 1 wt% to 2 wt% of inorganic conductive agent.

[0081] In conjunction with the second aspect, in some embodiments of the present invention, the concentration of alcohol-soluble polyamide 6 in the low-concentration spinning solution can be any value or a range formed by any two of 4.1wt%, 4.2wt%, 4.3wt%, 4.4wt%, 4.5wt%, 4.6wt%, 4.7wt%, 4.8wt%, 4.9wt%, and 5wt%.

[0082] In conjunction with the second aspect, in some embodiments of the present invention, the concentration of the aqueous fluorinated material in the low-concentration spinning solution can be any value or a range formed by any two of the following: 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, and 9wt%.

[0083] In conjunction with the second aspect, in some embodiments of the present invention, the concentration of the inorganic conductive agent in the low-concentration spinning solution can be any value or a range formed by any two of 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, and 2wt%.

[0084] It should be noted that low-concentration spinning solutions are used to spin fine fibers with smaller diameters. Inorganic conductive agents are added to the low-concentration spinning solution to increase its charge density and conductivity, generating excellent tensile strength during electrospinning and further forming fine fibers. High-concentration spinning solutions produce fibers with larger diameters; the combination of both is necessary to form a micro / nanostructured fiber membrane. Therefore, inorganic conductive agents can only be added to low-concentration spinning solutions.

[0085] In conjunction with the second aspect, in some embodiments of the present invention, the voltage during electrospinning can be 25kV to 30kV.

[0086] In conjunction with the second aspect, in some embodiments of the present invention, the infusion rate during electrospinning can be 1.8 mL / h to 2 mL / h.

[0087] In conjunction with the second aspect, in some embodiments of the present invention, the receiving distance during electrospinning can be 14cm to 16cm.

[0088] In conjunction with the second aspect, in some embodiments of the present invention, the spinning temperature during electrospinning can be 25°C to 27°C.

[0089] In conjunction with the second aspect, in some embodiments of the present invention, the relative humidity during electrospinning can be 40% to 50%.

[0090] In conjunction with the second aspect, in some embodiments of the present invention, the solvent in the high-concentration spinning solution and the low-concentration spinning solution may be anhydrous ethanol.

[0091] In conjunction with the second aspect, in some embodiments of the present invention, the method for preparing the nanofiber membrane may be:

[0092] S1. Prepare a high-concentration spinning solution by mixing 14wt% to 15wt% alcohol-soluble polyamide 6 and 3wt% to 9wt% aqueous fluorinated material in a solvent.

[0093] S2. Prepare a low-concentration spinning solution by mixing 4wt% to 5wt% alcohol-soluble polyamide, 3wt% to 9wt% aqueous fluorinated material, and 1wt% to 2wt% inorganic substance in a solvent.

[0094] S3. Using glossy paper as the receiving substrate for electrospinning, the mixed solution is spun onto the glossy paper by electrospinning to obtain a nanofiber membrane with radiation cooling and waterproof and breathable properties.

[0095] S4. Remove the prepared fiber membrane and place it in an 80℃ drying oven for 2 hours to remove residual solvent, thus obtaining a nanofiber membrane with radiation cooling and waterproof and breathable properties.

[0096] In a third aspect, some embodiments of the present invention provide a functional garment prepared from the micro / nanofiber membrane of the present invention.

[0097] One of the technical solutions of this invention concerning functional clothing has at least the following beneficial effects:

[0098] Excellent mechanical properties: The micro-nano structured fiber membrane is made up of submicron and nano-sized fibers interwoven together, which increases the load-bearing capacity and durability of the fiber membrane, enabling it to exhibit excellent mechanical properties when subjected to external forces.

[0099] Waterproof and breathable properties: The micro / nanofiber membrane contains water-based fluorinated materials, which improves the material's hydrophobicity, causing water droplets to form a smooth shape on the surface, thus enhancing waterproof performance. At the same time, the microporous structure generated by the nanofibers effectively prevents the penetration of liquid water, yet is small enough to allow water vapor to pass through, ensuring breathability.

[0100] Radiative cooling effect: The micro / nanofiber membrane contains fluorocarbon segments, which have high reflectivity and can enhance the heat dissipation of the material, thereby improving the radiative cooling effect. In addition, the polarity of the fluorocarbon segments and the reduction of the intermolecular distance can also improve the radiative heat transfer performance.

[0101] Improved electrical conductivity: The addition of inorganic conductive agents improves the electrical conductivity of micro / nanofiber membranes, which helps to enhance the tensile strength and stability of the fiber membranes, making them more suitable for the preparation of various functional garments.

[0102] In summary, functional garments made from the aforementioned micro / nanofiber membranes may possess a variety of beneficial effects, such as waterproofing and breathability, radiative cooling, excellent mechanical properties, and improved electrical conductivity, making them promising for applications in outdoor sports, protective clothing, and other fields.

[0103] Functional clothing can include technical clothing, performance clothing, smart clothing, UV-resistant clothing, waterproof clothing, breathable clothing, windproof clothing, thermal clothing, cold-proof clothing, sportswear, mountaineering clothing, hiking clothing, fitness clothing, cycling clothing, swimming clothing, raincoats, bulletproof vests, heat-insulating clothing, anti-static clothing, and radiation-proof clothing, etc.

[0104] The technical solution of the present invention will be better understood below with reference to specific embodiments.

[0105] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0106] Example 1

[0107] A micro / nanofiber membrane was prepared, and the specific steps are as follows:

[0108] S1: Preparation of high-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and after the alcohol-soluble polyamide 6 is completely dissolved, add water-based fluorinated waterproofing agent. Then mix the two solutions and stir them evenly for 6–10 hours until homogeneous. Ensure that the alcohol-soluble polyamide 6 has a mass fraction of 14 wt%. The mass fraction is 6 wt%.

[0109] S2: Preparation of low-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and add water-based fluorinated waterproofing agent. Add silver nitrate, then mix the two solutions together and stir evenly for 6–10 hours until homogeneous. Ensure the alcohol-soluble polyamide 6 mass fraction is 3 wt%. The mass fraction is 6 wt%, and the mass fraction of silver nitrate is 1 wt%.

[0110] S3: After the spinning solution is completely dissolved, electrospinning is performed: Cut a 60cm×60cm piece of glossy paper as the receiving substrate for electrospinning. Fix the electrospinning solution prepared in steps one and two on the infuser. Fix the low-concentration spinning solution on channels 1, 3, and 5, and fix the high-concentration spinning solution on channels 2 and 4. Finally, the fiber membrane is prepared by electrospinning technology. The spinning voltage is 30kV, the receiving distance is 15cm, the inflation rate is 2mL / h, the temperature is 25℃, and the relative humidity is 45%.

[0111] S4: Remove the prepared fiber membrane and place it in an 80℃ drying oven for 2 hours to remove residual solvent, thus obtaining a membrane with a water pressure resistance of 60.3 kPa and a moisture permeability of 4.58 kg / m³. 2 A fiber membrane with radiative cooling and waterproof / breathable properties, with a solar reflectivity of 90.1%, an infrared emissivity of 86.3%, and a cooling temperature of 3.8℃.

[0112] Example 2

[0113] A micro / nanofiber membrane was prepared, and the specific steps are as follows:

[0114] S1: Preparation of high-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and after the alcohol-soluble polyamide 6 is completely dissolved, add water-based fluorinated waterproofing agent. Then mix the two solutions and stir them evenly for 6–10 hours until homogeneous. Ensure that the alcohol-soluble polyamide 6 has a mass fraction of 14 wt%. The mass fraction is 6 wt%.

[0115] S2: Preparation of low-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and add water-based fluorinated waterproofing agent. Add silver nitrate, then mix the two solutions together and stir evenly for 6–10 hours until homogeneous. Ensure the alcohol-soluble polyamide 6 mass fraction is 3 wt%. The mass fraction is 6 wt%, and the mass fraction of silver nitrate is 1 wt%.

[0116] S3: After the spinning solution is completely dissolved, electrospinning is performed: Cut a 60cm×60cm piece of glossy paper as the receiving substrate for electrospinning. Fix the electrospinning solution prepared in steps one and two on the infuser. Fix the low-concentration spinning solution on channels 1, 3, and 5, and fix the high-concentration spinning solution on channels 2 and 4. Finally, the fiber membrane is prepared by electrospinning technology. The spinning voltage is 30kV, the receiving distance is 15cm, the inflation rate is 2mL / h, the temperature is 25℃, and the relative humidity is 45%.

[0117] S4: Remove the prepared fiber membrane and place it in a 90℃ drying oven for 2 hours to remove residual solvent, thus obtaining a membrane with a water pressure resistance of 59.2 kPa and a moisture permeability of 3.72 kg / m³. 2 A fiber membrane with radiative cooling and waterproof / breathable properties, with a solar reflectivity of 89.3%, an infrared emissivity of 85.3%, and a cooling temperature of 2.9℃.

[0118] Example 3

[0119] A micro / nanofiber membrane was prepared, and the specific steps are as follows:

[0120] S1: Preparation of high-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and after the alcohol-soluble polyamide 6 is completely dissolved, add water-based fluorinated waterproofing agent. Then mix the two solutions and stir them evenly for 6–10 hours until homogeneous. Ensure that the alcohol-soluble polyamide 6 has a mass fraction of 14 wt%. The mass fraction is 6 wt%.

[0121] S2: Preparation of low-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and add water-based fluorinated waterproofing agent. Add silver nitrate, then mix the two solutions together and stir evenly for 6–10 hours until homogeneous. Ensure the alcohol-soluble polyamide 6 mass fraction is 3 wt%. The mass fraction is 6 wt%, and the mass fraction of silver nitrate is 1 wt%.

[0122] S3: After the spinning solution is completely dissolved, electrospinning is performed: Cut a 60cm×60cm piece of glossy paper as the receiving substrate for electrospinning. Fix the electrospinning solution prepared in steps one and two on the infuser. Fix the low-concentration spinning solution on channels 1, 3, and 5, and fix the high-concentration spinning solution on channels 2 and 4. Finally, the fiber membrane is prepared by electrospinning technology. The spinning voltage is 30kV, the receiving distance is 15cm, the inflation rate is 2mL / h, the temperature is 25℃, and the relative humidity is 45%.

[0123] S4: Remove the prepared fiber membrane and place it in a 90℃ drying oven for 2 hours to remove residual solvent, thus obtaining a membrane with a water pressure resistance of 54.3 kPa and a moisture permeability of 3.63 kg / m³. 2 A fiber membrane with radiative cooling and waterproof / breathable properties, with a solar reflectance of 88.6%, an infrared emissivity of 85.2%, and a cooling temperature of 3.0℃.

[0124] Example 4

[0125] A micro / nanofiber membrane was prepared, and the specific steps are as follows:

[0126] S1: Preparation of high-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and after the alcohol-soluble polyamide 6 is completely dissolved, add water-based fluorinated waterproofing agent. Then mix the two solutions and stir them evenly for 6–10 hours until homogeneous. Ensure that the alcohol-soluble polyamide 6 has a mass fraction of 14 wt%. The mass fraction is 6 wt%.

[0127] S2: Preparation of low-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and add water-based fluorinated waterproofing agent. Add silver nitrate, then mix the two solutions together and stir evenly for 6–10 hours until homogeneous. Ensure the alcohol-soluble polyamide 6 mass fraction is 3 wt%. The mass fraction is 6 wt%, and the mass fraction of silver nitrate is 1 wt%.

[0128] S3: After the spinning solution is completely dissolved, electrospinning is performed: Cut a 60cm×60cm piece of glossy paper as the receiving substrate for electrospinning. Fix the electrospinning solution prepared in steps one and two on the infuser. Fix the low-concentration spinning solution on channels 1, 3, and 5, and fix the high-concentration spinning solution on channels 2 and 4. Finally, the fiber membrane is prepared by electrospinning technology. The spinning voltage is 30kV, the receiving distance is 15cm, the inflation rate is 2mL / h, the temperature is 25℃, and the relative humidity is 45%.

[0129] S4: Remove the prepared fiber membrane and place it in a 90℃ drying oven for 2 hours to remove residual solvent, thus obtaining a membrane with a water pressure resistance of 53.6 kPa and a moisture permeability of 3.96 kg / m³. 2 A fiber membrane with radiative cooling and waterproof / breathable properties, with a solar reflectivity of 89.6%, an infrared emissivity of 86.1%, and a cooling temperature of 2.4℃.

[0130] Example 5

[0131] A micro / nanofiber membrane was prepared, and the specific steps are as follows:

[0132] S1: Preparation of high-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and after the alcohol-soluble polyamide 6 is completely dissolved, add water-based fluorinated waterproofing agent. Then mix the two solutions and stir them evenly for 6–10 hours until homogeneous. Ensure that the alcohol-soluble polyamide 6 has a mass fraction of 14 wt%. The mass fraction is 6 wt%.

[0133] S2: Preparation of low-concentration electrospinning solution: Dissolve alcohol-soluble polyamide 6 in ethanol solvent, heat in a water bath at 60°C, and add water-based fluorinated waterproofing agent. Add magnesium chloride, then mix the two solutions together and stir evenly for 6–10 hours until homogeneous. Ensure the alcohol-soluble polyamide 6 mass fraction is 3 wt%. The mass fraction is 6 wt%, and the mass fraction of magnesium chloride is 1 wt%.

[0134] S3: After the spinning solution is completely dissolved, electrospinning is performed: Cut a 60cm×60cm piece of glossy paper as the receiving substrate for electrospinning. Fix the electrospinning solution prepared in steps one and two on the infuser. Fix the low-concentration spinning solution on channels 1, 3, and 5, and fix the high-concentration spinning solution on channels 2 and 4. Finally, the fiber membrane is prepared by electrospinning technology. The spinning voltage is 30kV, the receiving distance is 15cm, the inflation rate is 2mL / h, the temperature is 25℃, and the relative humidity is 45%.

[0135] S4: Remove the prepared fiber membrane and place it in a 90℃ drying oven for 2 hours to remove residual solvent, thus obtaining a membrane with a water pressure resistance of 51.8 kPa and a moisture permeability of 4.23 kg / m³. 2 A fiber membrane with radiative cooling and waterproof / breathable properties, with a solar reflectance of 90.0%, an infrared emissivity of 85.8%, and a cooling temperature of 3.2℃.

[0136] Performance testing:

[0137] The performance of the nanofiber membranes prepared in Examples 1-5 was tested, and the test results are shown in Tables 1 to 3.

[0138] Hydrostatic pressure, as a key indicator of waterproof performance, represents the resistance encountered by water as it permeates the fabric. This test is conducted according to the relevant testing standards of the national standard GB / T4744-2013. The specific steps are as follows: Three 18×18cm square sample fiber membranes are cut from the sample fiber membrane. These are placed on the disc of the hydrostatic pressure tester and covered with a black fabric. The ring is then tightened to compress the fiber membrane. The parameter is set to 6000 Pa / min, and the test is started. The test is stopped when the third water droplet appears on the black fabric. The value is recorded. The fiber membrane is then replaced, and the test is repeated. After the test is completed, the average of the three test results is taken as the hydrostatic pressure resistance value of the fiber membrane.

[0139] The contact angle is the angle between a liquid surface and a solid surface at which they just come into contact. The size of the contact angle reflects the hydrophilicity or hydrophobicity of the fiber membrane. The basic steps of the contact angle test are as follows: Cut the prepared sample into five pieces of fiber membrane slightly smaller than a coverslip and test them five times. Set the contact angle meter to use the seated drop method and select the Young-Laplace equation for the test. Measure the data five times and calculate the average value; this average value is taken as the contact angle data of the fiber membrane of that sample.

[0140] Moisture permeation flux test procedure: First, pour approximately 30 ml of deionized water into the permeation cup. Cut the sample fiber membrane to the same size as the permeation cup, place the fiber membrane on the permeation cup, and secure it with a rubber ring and washer, and then fix it with a nut. After fixing, set the instrument parameters: humidity 50%, constant temperature 38℃, and airflow speed 0.44 m / s. When the humidity and temperature in the constant temperature chamber reach the required levels, place the permeation cup in the chamber and allow it to equilibrate for 1 hour. Then, quickly weigh the permeation cup and record the weight as m1. Immediately place it in the testing instrument for 1 hour of experimentation, and weigh the permeation cup again, recording the weight as m2. Finally, calculate the moisture permeation flux of each fiber membrane using the formula WVT = 24 × Δm / (S × t). (WVT in the formula represents the moisture permeation flux per square meter per day, kg / m²) 2 ·d;S(m 2 The area of ​​the fiber membrane during the test is 0.00283 m². 2 Δm(g) represents the mass difference of the same fiber membrane, and t(h) represents the testing time of the fiber membrane.

[0141] UV-Vis-NIR (ultraviolet-visible-near-infrared) reflectance testing is used to measure the reflectance of materials within a specified wavelength range. The testing procedure is as follows: Prepare the sample to be tested, ensuring the surface is clean and flat; start the UV-Vis-NIR reflectance testing instrument for preheating and calibration. Based on the sample characteristics and testing requirements, set the testing parameters, such as wavelength range (0μm~2.5μm) and power density (0W / m³). 2 ·nm~2W / m 2 (nm), etc. Place the sample to be tested into the testing instrument and perform UV-Vis-NIR reflectance testing on the sample according to the set parameters. Record the data during the testing process, including the reflectance variation curve with wavelength.

[0142] Steps for testing infrared emissivity using a Fourier transform infrared spectrometer: Turn on the instrument and ensure it is in normal working order. Prepare the sample to be tested by placing it on the sampling system. Adjust the sample position to ensure full contact between the sample and the light source, ensuring accurate signal acquisition. Start the data acquisition and processing system and enter the spectral acquisition interface. Set the spectral acquisition parameters, including the wavenumber range (7μm~14μm). Finally, click the "Start Acquisition" button; the system will begin acquiring and processing the spectral data.

[0143] The cooling temperature test procedure is as follows: Cut a 5cm×5cm nanofiber membrane, a 5cm×5cm cotton fabric, and a 5cm×5cm electrospun polyurethane fiber membrane (as a control group), place them flat on the human arm, and use an infrared thermal imager to measure the surface temperature of the different fabrics covering the arm and record the temperature difference between the two.

[0144] The mechanical properties of this invention are tested using a tensile strength tester. Twenty 3mm × 40mm pieces of fiber membrane are cut from the sample fiber membrane and clamped between two air valve clamps. The computer testing software is opened, and parameters such as clamping distance, tensile speed, and modulus starting point are adjusted. The test is repeated 20 times, and abnormal data are discarded. Finally, the average strength is obtained. The stress (MPa) of the fiber membrane is calculated using the stress formula.

[0145] Table 1

[0146]

[0147] Table 2

[0148] Solar emissivity (%) Infrared emissivity (%) Example 1 90.1 86.3 Example 2 89.3 85.3 Example 3 88.6 85.2 Example 4 89.6 86.1 Example 5 90.0 85.8

[0149] Table 3

[0150] Stress (MPa) Elongation at break (%) Example 1 16.3 75.5 Example 2 13.5 78.2 Example 3 10.6 83.3 Example 4 12.8 82.2 Example 5 10.3 84.0

[0151] Table 4

[0152] Exposed skin (°C) Cotton fabric (°C) Polyurethane fiber membrane (°C) Example 1 4.6 3.8 3.6 Example 2 3.9 2.9 2.5 Example 3 3.6 3.0 2.8 Example 4 3.2 2.4 2.2 Example 5 3.8 3.2 3.1

[0153] This invention combines radiative cooling and waterproof / breathable properties onto a single nanofiber membrane. Utilizing the high solar reflectivity and high infrared emissivity of alcohol-soluble polyamide 6 (PA6), and the fluorocarbon segments in the water-based fluorinated material, radiative heat transfer is enhanced. This allows the fabric to more effectively release heat from the wearer's body into the environment via radiation, achieving a cooling effect and ensuring thermal comfort. This invention differs from traditional refrigeration systems, providing a cool environment for people working outdoors in extreme weather conditions. It can be applied to outdoor environments, achieving energy conservation and emission reduction goals.

[0154] The nanofiber membrane prepared by this invention possesses a micro-nano structure, consisting of both coarse fibers and fine mesh fibers. The fiber network, formed by the accumulation of numerous fine nanofibers, allows water vapor molecules to pass smoothly from the human body surface to the outside world through the membrane's porous structure, while external liquid water molecules cannot pass through the membrane's pores. Its small and numerous pores also enhance breathability and promote thermal and moisture balance. Furthermore, the coarse fibers endow the fiber membrane with excellent mechanical properties, improving its durability.

[0155] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A micro- and nanofiber membrane, characterized in that, The micro / nanofiber membrane is formed by interweaving polyamide 6 submicron fibers and polyamide 6 nanofibers. The diameter of the polyamide 6 submicron fibers is 130 nm to 190 nm, and the diameter of the polyamide 6 nanofibers is 35 nm to 55 nm. The micro / nanofiber membrane contains aqueous fluorinated materials and inorganic conductive agents. The aqueous fluorinated materials include at least one of perfluorooctyl ethyl acrylate and (N-methylperfluorohexylsulfonamide) ethyl acrylate. The inorganic conductive agents include at least one of silver nitrate, tetrabutylammonium chloride, dodecyltrimethylammonium bromide, magnesium chloride, and lithium chloride.

2. A method for preparing the micro / nanofiber membrane as described in claim 1, characterized in that, The process includes the steps of preparing high-concentration spinning solutions and low-concentration spinning solutions, and forming the micro / nanofiber membrane by electrospinning.

3. The method of claim 2, wherein, The high-concentration spinning solution contains 14wt%~15wt% of alcohol-soluble polyamide 6 and 3wt%~9wt% of the water-based fluorinated material.

4. The method of claim 2, wherein, The low-concentration spinning solution contains 4wt%~5wt% of alcohol-soluble polyamide 6, 3wt%~9wt% of the aqueous fluorinated material, and 1wt%~2wt% of the inorganic conductive agent.

5. The method of claim 2, wherein, The electrospinning parameters include: voltage 25kV~30kV; and / or, injection rate 1.8mL / h~2mL / h; and / or, receiving distance during spinning 14cm~16cm; and / or, temperature during spinning 25℃~27℃; and / or, relative humidity during spinning 40%~50%.

6. A functional garment characterized by It is prepared from the micro / nanofiber membrane described in claim 1.

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