Ultra-light and ultra-thin nano-composite thermal fabric as well as preparation and application thereof

Abstract

The invention provides an ultra-light and ultra-thin nano-composite thermal fabric as well as preparation and application thereof, and belongs to the technical field of thermal insulation nano-materials. The preparation method comprises the following steps: mixing a polymer, aerogel and an organic solvent, and carrying out electrostatic spinning on an obtained spinning solution by using a sea-island electrospinning method to obtain a silicon-based aerogel and electrostatic spinning nanofiber composite membrane; the composite film and the lining cloth with the adhesive points are subjected to hot-pressing compounding, and the aerogel-compounded electric spinning nanofiber anti-dusting fabric is obtained. The heat conductivity coefficient of the aerogel compounded electro-spinning nanofiber anti-dusting fabric prepared by the preparation method disclosed by the invention is 0.06-0.07 W.m <-1 >. K <-1 >; at the same low temperature, the heat preservation duration is in positive correlation with the film thickness and / or gram weight, the fabric can be customized according to requirements so as to save the cost, and the temperature range of a heat preservation application environment is-20 DEG C to-80 DEG C; the preparation method has the advantages of powder falling prevention, simple process and high efficiency, and shows a good application prospect in the field of novel thermal insulation materials used in an extremely low-temperature environment.

Description

Technical Field

[0001] This invention relates to an ultra-lightweight and thin nanocomposite thermal insulation fabric, its preparation and application; it belongs to the technical field of new thermal insulation materials. Background Technology

[0002] The heat transfer mechanisms between the human body, clothing, and the environment mainly include four modes: convection (skin to fiber, fiber to air), conduction (fiber to fiber), radiation (skin to fiber, fiber to air), and evaporation. When the pore size between fibers is less than 1 mm, the contributions of convection and radiation are negligible in low-temperature environments. The thermal conductivity of still air is close to 24 mW / (m·K), far lower than that of fiber polymers and composite materials. Therefore, the thermal conductivity of porous textiles with a high still air content is crucial for their heat retention effect.

[0003] The three-dimensional open network structure of aerogels endows them with a porous structure, with porosity ranging from 80% to 99.8% and pore size from 1 to 100 nm. They also possess extremely low thermal conductivity (as low as 0.013 W / (m·K)) and ultra-high specific surface area (500–1200 m²). 2 Porous materials, with their ability to adsorb and store large amounts of still air (g), possess significant potential for applications in thermal insulation. Mechanistically, the total heat transfer of porous materials is related to their effective thermal conductivity, encompassing gas conduction, solid conduction, convection, and radiation modes.

[0004] In the field of thermal insulation described in this application, the contributions of convection and radiation are negligible. At room temperature and pressure, gas conduction is the primary contributor to the effective thermal conductivity of aerogels, mainly depending on the pore size and mean free path (i.e., the average distance traveled by gas molecules between collisions) of the porous structure, and also influenced by the density and specific surface area of ​​the porous material. At room temperature and pressure, the mean free path of air molecules is 50 nm. The pore size is smaller than the mean free path of air molecules, which leads to a significant reduction in heat conduction from the gas, thus contributing to the thermal insulation effect.

[0005] The average pore size of the silica-based aerogel is 30–40 nm, the SiO2 mass fraction is above 85%, and the density is 0.012–0.100 g / cm³. 3 Theoretically, this meets the characteristics of thermal insulation materials. Since heat conduction in solids is primarily phonon transport, the thermal conductivity can be reduced through phonon scattering at the interface (or interfacial thermal resistance). Nanostructures and nanoporous structures have a positive effect on reducing heat conduction in solids; therefore, aerogels with extremely rich nanoporous structures also demonstrate their beneficial effects.

[0006] However, the high brittleness and poor plasticity of aerogel materials greatly limit their direct application in textiles. Currently, commonly used processing methods mainly include integral gel molding and physical doping, the latter further divided into thermal bonding and coating methods. However, composite fiber fabrics prepared using existing techniques mainly suffer from severe dust shedding and insufficient mechanical properties.

[0007] Therefore, providing an ultra-lightweight and thin nanocomposite thermal insulation fabric and its preparation and application, which utilizes irregular structure electrospinning technology to form aerogel nanoparticles in a nanofiber structure in one step and form a textile fabric in one step, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention:

[0008] The purpose of this invention is to provide an ultra-lightweight and thin nanocomposite thermal insulation fabric and its preparation and application. By using irregular structure electrospinning technology, aerogel nanoparticles are woven into the nanofiber structure and the textile fabric is formed in one step, overcoming the main technical problems of serious powder shedding and the need to further improve the mechanical properties of traditional aerogel felts or their composite fiber fabrics in the prior art.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0010] An ultra-lightweight nanocomposite thermal insulation fabric is characterized in that the fabric consists of a three-layer structure, with the inner and outer layers being knitted or woven linings with micro-adhesive dots; and the middle layer being a thermal insulation layer.

[0011] Preferably, the thickness of the insulation layer is 70-200 μm, and it is composed of silicon-based aerogel nanoparticles and electrospun nanofibers.

[0012] Preferably, the thickness of the insulation layer is 70–80 μm and the weight is 70–80 g / cm³. 2 .

[0013] Preferably, in the thermal insulation layer, the aerogel mass is 40-50 wt% of the polymer mass, the diameter of the selected nanofibers is matched with the pore size of the aerogel, the composite nanofibers are irregularly interwoven to form a complex three-dimensional network structure, and the silicon-based aerogel nanoparticles are coated on the surface of the nanofibers and / or embedded in the surface and / or interior of the nanofibers, which can effectively prevent the nanoparticles from falling off and form a powder-proof fabric.

[0014] The above-mentioned method for preparing ultra-lightweight and thin nanocomposite thermal insulation fabric includes the following steps:

[0015] S1: Mix the polymer and organic solvent at room temperature, and stir magnetically until homogeneous to obtain a polymer solution;

[0016] S2: Add the silicon-based aerogel powder to the polymer solution of S1, and stir magnetically until homogeneous to obtain the spinning solution;

[0017] S3: The spinning solution obtained in S2 is loaded into an island-type spinneret or a sea-type spinneret for electrospinning to obtain a silicon-based aerogel and electrospinned nanofiber composite membrane in one step.

[0018] S4: The silicon-based aerogel prepared in S3 and the electrospun nanofiber composite membrane are sandwiched in the middle of the adhesive-dot lining. The four sides of the lining are longer than the fiber composite membrane. The adhesive dots of the two linings are attached to the membrane respectively. The lining with adhesive dots is hot-pressed and bonded around the edges to obtain an ultra-lightweight and thin nanocomposite thermal insulation fabric.

[0019] Preferably, in S1, the polymer includes, but is not limited to, one or a mixture of two of polyacrylonitrile (PAN) and polyamide 6 (PA6) in any proportion.

[0020] Preferably, in S1, the organic solvent is N,N-dimethylformamide (DMF).

[0021] A mixture of one or two of the following in any proportion: formic acid, etc.

[0022] Preferably, in S1, the mass ratio of the polymer to the organic solvent is 1:7 to 1:8.

[0023] Preferably, in S2, the average pore size of the silicon-based aerogel is 30-40 nm, the SiO2 mass fraction is above 85%, and the density is 0.012-0.100 g / cm³. 3 .

[0024] Preferably, in S3, the diameter of the nanofibers in the silicon-based aerogel and electrospun nanofiber composite membrane is 20-120 nm, ensuring that the fiber inside the thickest single fiber can accommodate a maximum of three aerogel particles and a minimum of two-thirds of the aerogel particles.

[0025] Preferably, in S3, the diameter of the finest single fiber in the silicon-based aerogel and electrospun nanofiber composite membrane is greater than two-thirds of the average pore size of the aerogel, and the diameter of the thickest single fiber is three times the average pore size of the aerogel, thereby giving the composite fabric the property of preventing powder shedding.

[0026] Preferably, in S3, the parameters of the electrospinning include: a positive and negative voltage difference of 20-22kV, an injection pump feed rate of 0.3-0.5mL / h, a roller rotation speed of 90-100rpm / min, and a receiving distance of 15-18cm.

[0027] Preferably, in S2, the mass fraction of the silica-based aerogel in the spinning solution within the island-type spinneret is 1.5 wt% to 5.7 wt%.

[0028] Preferably, in S2, the mass fraction of the silica-based aerogel in the spinning solution within the sea-type spinneret is 5.7 wt% to 6.5 wt%.

[0029] Preferably, in step S4, the silicon-based aerogel and electrospun nanofiber composite film is placed in the middle of the adhesive-dot lining. The four sides of the lining are 1-2 cm longer than the composite film. The adhesive dots of the two linings are respectively attached to the composite film. Hot pressing is performed within a 2.5-4 cm range around the edges of the adhesive-dot lining, and no hot pressing is performed in other areas.

[0030] Preferably, in S4, the hot pressing is performed using a household iron at a high temperature setting for a hot pressing time of 0.5 to 1.5 minutes.

[0031] This invention provides an ultra-lightweight and thin nanocomposite thermal insulation fabric obtained by the above preparation method.

[0032] This invention provides the application of the above-mentioned ultra-lightweight and thin nanocomposite thermal insulation fabric in the field of thermal insulation.

[0033] Beneficial effects:

[0034] This invention combines silicon-based aerogel nanoparticles with electrospun nanofibers to obtain a silicon-based aerogel and electrospun nanofiber composite film; then, it is heat-pressed and bonded to a lining with adhesive dots to obtain an ultra-lightweight and thin nanocomposite thermal insulation fabric.

[0035] This invention introduces electrospun nanofibers into silicon-based aerogel nanoparticles to form a complex three-dimensional nanofiber network structure. The silicon-based aerogel nanoparticles coat and / or embed on the surface and / or inside the nanofibers, effectively preventing nanoparticle shedding. This allows the silicon-based aerogel-electrospun nanofiber composite film to maintain good thermal insulation properties. The lining with adhesive dots exhibits a certain rigidity, and after bonding with the silicon-based aerogel-electrospun nanofiber composite film, the mechanical properties of the aerogel fabric can be further improved. Therefore, this invention combines electrospinning, island-of-sea electrospinning, and hot-press bonding processes, combining the advantages of silicon-based aerogel and electrospun nanofibers such as lightness, warmth, softness, and porosity. The resulting ultra-thin nanocomposite thermal insulation fabric has a thermal conductivity of 0.06–0.07 W·m. -1 ·K -1 .

[0036] This invention yields an ultra-lightweight and thin nanocomposite thermal insulation fabric with a composite nanofiber membrane thickness of 70–80 μm and a basis weight of 70–80 g / cm³. 2Under certain conditions, when the composite nanofiber fabric wraps the protected item and places it in a cold environment of -20℃ for 3.5 hours, -30℃ for 2 hours, -40℃ for 2 hours, -50℃ for 2 hours, -60℃ for 1 hour, -70℃ for 1 hour, and -80℃ for 1 hour, the protected item can still maintain a relatively suitable temperature. The composite film can provide good thermal insulation performance. Under the same low temperature conditions, the insulation time is positively correlated with the film thickness and / or basis weight. The fabric thickness can be customized proportionally according to the needs to save costs. The application low temperature range is -20℃ to -80℃.

[0037] This invention prepares ultra-lightweight and thin nanocomposite thermal insulation fabric using advanced island electrospinning technology. This preparation method has the advantages of preventing powder shedding, simple process, and high efficiency, and shows excellent application prospects in the field of thermal insulation. It can be used to make all electronic products that use existing lithium-ion batteries, such as mobile phone bags, computer bags, iPad bags, and power bank bags. It can be used in extremely cold climates or in low-temperature environments in winter in some regions to ensure the battery life and normal operation of lithium-ion batteries in 3C electronic products.

[0038] The ultra-thin nanocomposite thermal insulation fabric prepared by this invention, which is synergistically optimized with organic and inorganic nanomaterials, has advantages such as high porosity, good mechanical properties, and thermal insulation performance. It solves, to a certain extent, the problems of powder shedding, low strength, and poor mechanical properties of traditional aerogel composite fiber fabrics. Depending on the different needs of use, it can be used as a fabric interlayer for independent bags, as a dedicated fabric interlayer for placing mobile phones or other items in any shopping bag or clothing pocket, or as a thermal interlayer for any clothing, such as down jackets, professional Antarctic expedition clothing, disposable medical protective clothing, etc., or as a thermal cover interlayer for buildings, electric vehicles, electric bicycles, etc.

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this does not imply any limitation on the scope of protection of the present invention. Attached Figure Description

[0040] Figure 1 This is a scanning electron microscope image of the aerogel composite nanofiber membrane in Example 1 of the present invention;

[0041] Figure 2 This is a schematic diagram of the cross-sectional structure of the composite fabric in Embodiment 1 of the present invention;

[0042] Figure 3 This is a schematic diagram of the distribution of aerogel on nanofibers in Example 1 of the present invention;

[0043] Figure 4-1This is a schematic diagram of the top cross-section of the island nozzle in Embodiment 1 of the present invention; wherein, a, b, and c are island-shaped needles, and d is a sea-shaped needle;

[0044] Figure 4-2 This is a longitudinal cross-sectional schematic diagram of the island nozzle in Embodiment 1 of the present invention; wherein, a, b, and c are island-shaped nozzles, and d is a sea-shaped nozzle;

[0045] Figure 5 The results of thermal insulation performance tests at different ultra-low temperatures are shown for the film thickness of 75 μm in Example 2 of this invention. Detailed Implementation

[0046] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0047] In this invention, the polymer includes, but is not limited to, one or both of polyacrylonitrile (PAN) and polyamide 6 (PA6); when the polymer is two of the above, this invention does not have a special limitation on the ratio of different types of polymers, and can be adjusted according to needs.

[0048] In this invention, the organic solvent is one or two of N,N-dimethylformamide (DMF), formic acid, etc. When the organic solvent is two of the above, this invention does not have a special limitation on the ratio of different types of organic solvents, and can be adjusted according to actual needs.

[0049] In this invention, the polymer is preferably dissolved in an organic solvent and then magnetically stirred at room temperature for 0.5–1 hour to obtain a polymer solution. Silicon-based aerogel powder is then added to the polymer solution and magnetically stirred at room temperature for 8–12 hours to obtain a spinning solution. This invention does not impose any particular limitation on the stirring process; the solution can be stirred until it is uniform and transparent according to procedures well known in the art.

[0050] In this invention, the preferred parameters for electrospinning include: a spinning positive and negative voltage difference of 20–22 kV, an injection pump feed rate of 0.3–0.5 mL / h, a roller rotation speed of 90–100 rpm / min, a receiving distance of 15–18 cm, and an aerogel mass fraction of 1.5 wt%–5.7 wt% in the island-type channel electrospinning solution and 5.7 wt%–6.5 wt% in the sea-type channel electrospinning solution.

[0051] After obtaining the silicon-based aerogel and electrospun nanofiber composite film, the present invention performs hot pressing composite of the silicon-based aerogel and electrospun nanofiber composite film and a lining with adhesive dots to obtain an ultra-lightweight and thin nanocomposite thermal insulation fabric.

[0052] The present invention preferably first prepares a spinning solution with a relatively small polymer diameter, then prepares a composite membrane of silicon-based aerogel and electrospun nanofibers by sea-type or island-type electrospinning method, and then heat-presses it with a lining with adhesive dots to obtain an ultra-lightweight and thin nanocomposite thermal insulation fabric.

[0053] This invention does not impose any special limitations on other preparation conditions for the silicon-based aerogel and electrospun nanofiber composite membrane; it can be prepared according to processes well known in the art. In the embodiments of this invention, the polymer in the polymer solution is preferably polyacrylonitrile.

[0054] In this invention, the mass ratio of the polymer to the organic solvent is preferably 1:7 to 1:8, more preferably 1:7 to 1:7.4, and even more preferably 1:7.3 to 1:7.4.

[0055] In this invention, the silicon-based aerogel has an average pore size of 30–40 nm, a SiO2 mass fraction of 85% or more, and a density of 0.012–0.100 g / cm³. 3 The diameter of the electrospun nanofibers is 20–120 nm.

[0056] In this invention, the mass fraction of silicon-based aerogel in the spinning solution of the island-type spinneret is 1.5wt% to 5.7wt%, and the mass fraction of silicon-based aerogel in the spinning solution of the sea-type spinneret is 5.7wt% to 6.5wt%.

[0057] After completing the hot-press bonding process, the material is cooled to room temperature to obtain an ultra-lightweight and thin nano-composite thermal insulation fabric.

[0058] The present invention provides the preparation method described in the above technical solution to obtain an ultra-lightweight and thin nanocomposite thermal insulation fabric.

[0059] This invention provides the application of the aforementioned ultra-thin nanocomposite thermal insulation fabric in the field of thermal insulation. Applied according to methods well-known in the art, this invention can be used as a functional thermal insulation composite fabric for manufacturing mobile phone bags, laptop bags, iPad bags, power bank bags, and other electronic products using existing lithium-ion batteries. It is suitable for use in extremely cold climates or low-temperature winter environments in some regions to ensure the battery life and normal operation of lithium-ion batteries in 3C electronic products. Application scenarios include use as a fabric interlayer in independent bags, as a dedicated fabric interlayer for placing mobile phones or other items in any bag or clothing pocket, as a thermal interlayer in any garment, such as down jackets, professional Antarctic expedition suits, disposable medical protective clothing, etc., or as a thermal cover interlayer in buildings, electric vehicles, electric bicycles, etc.

[0060] Example 1

[0061] This embodiment 1 provides a method for preparing a thermal insulation nanofiber membrane of polyacrylonitrile (PAN) nanofibers loaded with aerogel nanoparticles, including:

[0062] 1) Preparation of island-type channel electrospinning solution

[0063] At room temperature, polyacrylonitrile (PAN) nanoparticles and N,N-dimethylformamide (DMF) solvent in a mass ratio of 1:7 were weighed and magnetically stirred for 0.5 h until the solution was uniform and clear to obtain a spinning solution; aerogel nanoparticles with a mass fraction of 1.5% were added and stirring was continued for 8 h until the solution was clear and transparent.

[0064] 2) Preparation of sea-type channel electrospinning solution

[0065] At room temperature, polyacrylonitrile (PAN) nanoparticles and N,N-dimethylformamide (DMF) solvent in a mass ratio of 1:7 were weighed and magnetically stirred for 0.5 h until the solution was uniform and clear to obtain a spinning solution; aerogel nanoparticles with a mass fraction of 5.7% were added and stirring was continued for 8 h until the solution was clear and transparent.

[0066] 3) Island-type electrospinning to prepare composite nanofiber membranes

[0067] Under normal temperature and pressure, with a relative humidity of 30%, and using smooth fabric of 30cm*30cm or larger as the receiving substrate, this system is designed for applications requiring 2 hours of warmth retention. The spinning solution volume is 20mL, the film thickness is 50μm, the positive and negative voltage difference during spinning is 20kV, and the injection pump speed is 0.3mL·h. -1 The drum speed is 90 rpm / min and the receiving distance is 15 cm. Based on this solution volume and film thickness, the film area can be increased proportionally.

[0068] like Figure 1 The image shown is a scanning electron microscope image of the aerogel composite nanofiber membrane in Example 1 of the present invention. The composite nanofibers in the aerogel composite nanofiber membrane prepared by the present invention are irregularly interwoven to form a complex three-dimensional network structure. The silicon-based aerogel nanoparticles are coated on the surface of the nanofibers and / or embedded in the surface and / or interior of the nanofibers.

[0069] Example 2

[0070] This embodiment 2 provides a method for preparing a thermal insulation nanofiber membrane of polyacrylonitrile (PAN) nanofibers loaded with aerogel nanoparticles, including:

[0071] 1) Preparation of island-type channel electrospinning solution

[0072] At room temperature, polyacrylonitrile (PAN) nanoparticles and N,N-dimethylformamide (DMF) solvent in a mass ratio of 1:7.5 were weighed and magnetically stirred for 0.5 h until the solution was uniform and clear to obtain a spinning solution; aerogel nanoparticles with a mass fraction of 3.6% were added and stirring was continued for 8 h until the solution was clear and transparent;

[0073] 2) Preparation of sea-type channel electrospinning solution

[0074] At room temperature, polyacrylonitrile (PAN) nanoparticles and N,N-dimethylformamide (DMF) solvent in a mass ratio of 1:7.5 were weighed and magnetically stirred for 0.5 h until the solution was uniform and clear to obtain a spinning solution; aerogel nanoparticles with a mass fraction of 6.1% were added and stirring was continued for 8 h until the solution was clear and transparent.

[0075] 3) Preparation of composite nanofiber membranes by marine electrospinning

[0076] Under normal temperature and pressure, with a relative humidity of 30%, and using smooth fabric of 30cm*30cm or larger as the receiving substrate, this application aims to meet the requirement of 2 hours of warming function. The spinning solution volume is 20mL, the film thickness is 75μm, the positive and negative voltage difference during spinning is 22kV, and the injection pump speed is 0.5mL·h. -1 The drum speed is 100 rpm / min and the receiving distance is 18 cm. Based on this solution volume and film thickness, the film area can be increased proportionally.

[0077] Example 3

[0078] This embodiment 3 provides a method for preparing a thermal insulation nanofiber membrane of polyamide 6 (PA6) nanofibers loaded with aerogel nanoparticles, comprising:

[0079] 1) Preparation of island-type channel electrospinning solution

[0080] At room temperature, polyamide 6 (PA6) nanoparticles and formic acid solvent in a mass ratio of 1:8 were weighed and magnetically stirred for 0.5 h until the solution was uniform and clear to obtain a spinning solution; aerogel nanoparticles with a mass fraction of 5.7% were added and stirring was continued for 8 h until the solution was clear and transparent.

[0081] 2) Preparation of sea-type channel electrospinning solution

[0082] At room temperature, polyamide 6 (PA6) nanoparticles and formic acid solvent in a mass ratio of 1:8 were weighed and magnetically stirred for 0.5 h until the solution was uniform and clear to obtain a spinning solution; aerogel nanoparticles with a mass fraction of 6.5% were added and stirring was continued for 8 h until the solution was clear and transparent.

[0083] 3) Preparation of composite nanofiber membranes by marine electrospinning

[0084] Under normal temperature and pressure, with a relative humidity of 30%, and using smooth fabric of 30cm*30cm or larger as the receiving substrate, this application aims to meet the requirement of 2 hours of warming function. The spinning solution volume is 20mL, the film thickness is 80μm, the positive and negative voltage difference during spinning is 22kV, and the injection pump speed is 0.5mL·h. -1 The drum speed is 100 rpm / min and the receiving distance is 18 cm. Based on this solution volume and film thickness, the film area can be increased proportionally.

[0085] Performance testing of the composite nanofiber membrane prepared in this embodiment

[0086] like Figure 5 The image shows the thermal insulation performance test of the composite nanofiber membrane with a thickness of 75 μm prepared in Example 2 of the present invention under different ultra-low temperatures.

[0087] By comparing and analyzing the temperature retention data of human body composition simulation liquid at various test temperatures, the thermal insulation effect of nanofiber composite materials of each thickness was evaluated.

[0088] Test method:

[0089] To evaluate the thermal insulation performance of nanofiber composites of different thicknesses in low-temperature environments (-20℃ to -80℃), the study mainly examined the thermal insulation effect of nanofiber composites on human body composition simulation fluid. By comparing and analyzing the temperature retention data of human body composition simulation fluid at various test temperatures, the thermal insulation effect of nanofiber composites of each thickness was evaluated, and the performance differences under different temperature conditions were explored. The research results will help determine which thickness of nanofiber composite is most suitable for thermal insulation applications in low-temperature environments.

[0090] Specific test conditions:

[0091] (1) Ambient temperature: Set an ultra-low temperature gradient from -20℃ to -80℃, with a temperature interval of 10℃. The ambient temperature must be kept stable at each temperature (fluctuation within ±1℃).

[0092] (2) Sample specifications: The composite nanofiber membrane was cut to a uniform size (e.g., 10cm×10cm), and each test was repeated 3 times;

[0093] (3) Protected object: Use a human body composition simulation solution prepared with 70% water, 20% bone, 7% blood plasma and 3% inorganic salts, and put it into a container of the same size (such as a 50mL cylindrical plastic container);

[0094] (4) Instruments and equipment: Ultra-low temperature test chamber (model DW-86L51J, Qingdao Haier Biomedical), handheld thermal imager (model HM-TPH21Pro-3AQF, Hangzhou Microfilm Software);

[0095] (5) Test duration: The test shall be conducted for no less than 1.5 hours under each temperature gradient until the temperature of the protected object is below -30℃ or the temperature change tends to stabilize.

[0096] Thermal insulation performance tests were conducted on nanofiber composites with different numbers of layers to evaluate their protective effect against human body composition simulation liquid under extreme low temperature conditions.

[0097] Main experimental steps:

[0098] (1) Prepare a single-layer nanofiber membrane. Use a temperature-controlled low-temperature test chamber and an ultra-low-temperature test chamber respectively. Set the experimental temperature range to -20℃ to -80℃. The temperature inside the test chamber can be adjusted and monitored by an external control system.

[0099] (2) Prepare human body composition simulation solution to fill the insulated test container;

[0100] (3) Wrap a single layer of nanofiber composite material around a container containing human component simulation liquid, and place the wrapped human component simulation liquid in a low-temperature test chamber for testing at temperatures ranging from -20℃ to -80℃. The testing method is as follows: after the sample has stabilized in the low-temperature environment for 0.5h, the test begins. Every 0.5h, a handheld thermal imager is used to measure the temperature of the human component simulation liquid and the surface temperature of the sample. If the temperature of the low-temperature test chamber rises during the test, the timing should be stopped only after the temperature drops to the test temperature. The test ends when the temperature of the human component simulation liquid no longer changes or changes only slightly.

[0101] Example 4

[0102] The silicon-based aerogel and electrospun nanofiber composite membrane prepared in Example 1 were sandwiched between adhesive-dot linings. The four sides of the linings were longer than the fiber composite membrane. The adhesive dot sides of the two linings were attached to the membrane. The linings were then heat-pressed together around the edges to obtain an ultra-thin nanocomposite thermal insulation fabric. The silicon-based aerogel and electrospun nanofiber composite membrane were placed in the middle of adhesive-dot linings. The four sides of the linings were 1.5 cm longer than the composite membrane. The adhesive dot sides of the two linings were attached to the composite membrane. The linings were then heat-pressed together within a 3 cm radius around the edges. Other areas were not heat-pressed. A household iron was used at a high temperature for 1.0 min.

[0103] (1) Raw material preparation

[0104] Composite membrane: The silicon-based aerogel and electrospun nanofiber composite membrane prepared in Example 1 was cut to a fixed size (e.g., 20cm × 30cm) to ensure a smooth and undamaged surface;

[0105] Adhesive-coated backing fabric: Select a thin, lightweight polyester hot melt adhesive backing fabric (0.1mm thick). Cut two pieces of backing fabric, each 1.5cm longer and wider than the composite film (e.g., composite film 20cm×30cm, backing fabric 23cm×33cm). Adhesive dots density: 10-15 dots / cm. 2 (Diameter 0.5-1mm);

[0106] (2) Stacking order

[0107] Lay the first lining fabric flat (adhesive dots facing up), place the composite film in the center, and ensure that the distance between the four sides of the composite film and the four sides of the lining fabric is 1.5cm; cover the composite film with the second lining fabric (adhesive dots facing down), press lightly to adhere, and avoid air bubbles or misalignment.

[0108] (3) Hot pressing bonding

[0109] Hot-pressed area: Only the 1.5cm edge area of ​​the lining extending beyond the composite film is hot-pressed; the area in the middle covering the composite film is not hot-pressed (to prevent damage to the composite film structure).

[0110] Equipment and parameters: Laboratory-grade household steam iron (high temperature setting 150-180℃), industrial-grade flatbed hot press (160±5℃); Pressure: iron pressing naturally (5-10N), hot press 0.3-0.5MPa; Time: hot press each edge area for 1.0-1.5min to ensure the adhesive dots are completely melted;

[0111] (4) Cooling and molding

[0112] After hot pressing, transfer to a room temperature silicone pad and allow to cool naturally for 30 minutes. After the adhesive has cured, trim the rough edges to obtain the finished product.

[0113] This invention involves mixing a polymer, aerogel, and an organic solvent, and then electrospinning the resulting spinning solution using a sea-type or island-type electrospinning method to obtain a silicon-based aerogel-electrospun nanofiber composite membrane. The composite membrane is then hot-pressed with a backing fabric containing adhesive dots to obtain an aerogel-composite electrospun nanofiber anti-dust fabric. The thermal conductivity of the aerogel-composite electrospun nanofiber anti-dust fabric prepared by this invention is 0.06–0.07 W·m. -1 ·K -1 At the same low temperature, the insulation time is positively correlated with the film thickness and / or weight. Fabrics can be customized according to needs to save costs. The temperature range of the insulation application environment is -20℃ to -80℃. This preparation method has the advantages of preventing powder shedding, simple process and high efficiency, and shows good application prospects in the field of new thermal insulation materials for use in extreme low temperature environments.

[0114] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An ultra-lightweight and thin nano-composite thermal insulation fabric, characterized in that, The fabric consists of a three-layer structure: the inner and outer layers are knitted or woven interlinings with tiny adhesive dots; the middle layer is a thermal insulation layer.

2. The ultra-lightweight and thin nanocomposite thermal insulation fabric as described in claim 1, characterized in that, The insulation layer has a thickness of 70–200 μm and is composed of silicon-based aerogel nanoparticles and electrospun nanofibers.

3. The ultra-lightweight and thin nanocomposite thermal insulation fabric as described in claim 1, characterized in that, The insulation layer has a thickness of 70–80 μm and a weight of 70–80 g / cm³. 2 .

4. The ultra-lightweight and thin nanocomposite thermal insulation fabric as described in claim 1, characterized in that, In the insulation layer, the aerogel has a mass of 40-50 wt% of the polymer mass. The diameter of the selected nanofibers is matched with the pore size of the aerogel. The composite nanofibers are irregularly interwoven to form a complex three-dimensional network structure. Silicon-based aerogel nanoparticles are coated on the surface of the nanofibers and / or embedded in the surface and / or interior of the nanofibers.

5. A method for preparing the ultra-lightweight and thin nanocomposite thermal insulation fabric according to any one of claims 1-4, comprising the following steps: S1: Mix the polymer and organic solvent at room temperature, and stir magnetically until homogeneous to obtain a polymer solution; S2: Add the silicon-based aerogel powder to the polymer solution of S1, and stir magnetically until homogeneous to obtain the spinning solution; S3: The spinning solution obtained in S2 is loaded into an island-type spinneret or a sea-type spinneret for electrospinning to obtain a silicon-based aerogel and electrospinned nanofiber composite membrane in one step. S4: The silicon-based aerogel prepared in S3 and the electrospun nanofiber composite membrane are sandwiched in the middle of the adhesive-dot lining. The four sides of the lining are longer than the fiber composite membrane. The adhesive dots of the two linings are attached to the membrane respectively. The lining with adhesive dots is hot-pressed and bonded around the edges to obtain an ultra-lightweight and thin nanocomposite thermal insulation fabric.

6. The method for preparing the ultra-lightweight and thin nanocomposite thermal insulation fabric as described in claim 5, characterized in that, In S1, the polymer includes, but is not limited to, one or a mixture of two of polyacrylonitrile and polyamide 6 in any proportion; the organic solvent is one or a mixture of two of N,N-dimethylformamide and formic acid in any proportion; the mass ratio of the polymer to the organic solvent is 1:7 to 1:

8.

7. The method for preparing the ultra-lightweight and thin nanocomposite thermal insulation fabric as described in claim 5, characterized in that, In S2, the average pore size of the silicon-based aerogel is 30–40 nm, the SiO2 mass fraction is above 85%, and the density is 0.012–0.100 g / cm³. 3 The mass fraction of silica-based aerogel in the spinning solution of the island-type spinneret is 1.5 wt% to 5.7 wt%; the mass fraction of silica-based aerogel in the spinning solution of the sea-type spinneret is 5.7 wt% to 6.5 wt%.

8. The method for preparing the ultra-lightweight and thin nanocomposite thermal insulation fabric as described in claim 5, characterized in that, In S3, the diameter of the nanofibers in the silicon-based aerogel and electrospun nanofiber composite membrane is 20–120 nm, ensuring that the thickest single fiber can accommodate a maximum of three aerogel particles and a minimum of two-thirds of the aerogel particles within its diameter direction. The diameter of the thinnest single fiber in the silicon-based aerogel and electrospun nanofiber composite membrane is greater than two-thirds of the average pore size of the aerogel, and the diameter of the thickest single fiber is three times the average pore size of the aerogel. The electrospinning parameters include: a spinning positive and negative voltage difference of 20–22 kV, and an injection pump propulsion speed. 0.3-0.5 mL / h, roller speed 90-100 rpm / min, receiving distance 15-18 cm; In S4, the silicon-based aerogel and electrospun nanofiber composite membrane is placed in the middle of the adhesive-dot lining, the four sides of the lining are 1-2 cm longer than the composite membrane, the adhesive dot sides of the two linings are respectively attached to the composite membrane, and hot pressing is performed within 2.5-4 cm of the perimeter of the adhesive-dot lining, and no hot pressing is performed in other areas; In S4, the hot pressing is performed using a household iron at high temperature, and the hot pressing time is 0.5-1.5 min.

9. The application of the ultra-thin nanocomposite thermal insulation fabric as described in any one of claims 1-4 in terms of thermal insulation.

10. The application of the ultra-lightweight nanocomposite thermal insulation fabric as described in claim 9 in terms of thermal insulation, used to make mobile phone bags, computer bags, iPad bags or power bank bags, electronic products using existing lithium-ion batteries, for use in extremely cold climates or low-temperature environments in winter in some areas; used as a fabric interlayer for independent bags, or as a fabric interlayer for a dedicated position for placing mobile phones attached to any commodity bag or clothing pocket, or as a thermal interlayer for any clothing, such as down jackets, professional Antarctic expedition clothing, disposable medical protective clothing, or thermal cover interlayer for buildings, electric vehicles, and electric bicycles.

Images