A cold-insulating material and its preparation method and application

Abstract

The present invention discloses a cold-insulating material, its preparation method and application. The cold-insulating material includes a metal film and a fluorocarbon resin-based fiber membrane loaded thereon. The fluorocarbon resin-based fiber membrane has a porosity of 55% to 85% and a thickness of 5 to 75 μm. The preparation method comprises: using a spinning solution made of a fluorocarbon resin-based polymer, a two-component solvent, and water as a raw material, and loading it on the surface of the metal film by electrostatic spinning. Compared with conventional graded porous radiation cooling films, the cold-insulating material of the present invention has the advantages of high reflectivity to full-band sunlight, excellent flexibility, and long service life. It is a new type of composite cold-insulating material with excellent cold-insulating effect. It can be widely used to ensure that the internal space of the cold-insulating system maintains a long-term low-temperature state. It has high use value and good application prospects. The preparation method of the present invention has the advantages of simple process, convenient operation, mild production conditions, etc., and can achieve low-cost, large-scale preparation, facilitating the industrial application of cold-insulating materials.

Description

Technical Field

[0001] The invention belongs to the technical field of cold-insulating and heat-insulating materials, and relates to a cold-insulating material and a preparation method and application thereof. Background Art

[0002] The cold insulation system is an important component of structures such as atmospheric ammonia storage tanks, liquefied natural gas storage tanks, low-temperature grain warehouses, and cold chain transport vehicles. The cold insulation performance of the cold insulation system not only directly affects energy consumption, but also concerns safety. Considering that most of these structures are used outdoors, in order to achieve optimal cold insulation performance, in addition to fixing insulation materials with low thermal conductivity and high and low temperature stability on the inside of the tank or compartment, it is also necessary to wrap or coat the outside with insulation materials. Most of these materials are white, with the purpose of reducing the absorption of solar energy by the entire structure. Currently, the commonly used methods are to apply white insulation paint or wrap with tin foil and aluminum foil. Although these materials are low in cost, easy to construct, and can partially block the entry of solar heat, their effectiveness is limited.

[0003] Daytime radiative cooling technology is a method that exchanges radiant energy with the cold outer space while preventing solar radiation from entering the object to be cooled. When used in conjunction with active refrigeration, it can significantly reduce the energy consumption required for active refrigeration, thereby reducing the negative impact on the environment. It has now become an emerging research hotspot. In order to achieve absolute cooling below ambient temperature, daytime radiative cooling technology requires that the material have strict spectral selectivity, that is, it has strong radiation ability only in the atmospheric window band of 8 to 13 μm to achieve sufficient dissipation of internal heat, and has strong reflection ability in the solar light band of 0.3 to 2.5 μm to prevent the entry of solar heat. In order to achieve the above spectral selectivity, researchers have developed and reported a series of radiative cooling materials and devices based on metamaterials, and have achieved certain cooling effects in outdoor cooling performance tests. Among them, polymer membranes based on disordered porous structures have been studied in depth because of their potential for large-scale preparation. However, existing radiative cooling polymer porous membranes are mainly aimed at the cooling needs of objects or spaces at room temperature. If the temperature of the application scenario is significantly lower than 25°C, the spectral behavior of the material should be adjusted accordingly. First of all, of course, the cold insulation material is required to strongly reflect sunlight, but requiring the material to have strong infrared absorption and radiation capabilities in the range of 8 to 13 μm is obviously unreasonable, because this will cause the extremely cold space to quickly absorb the surrounding infrared thermal radiation, thereby weakening the cold insulation ability. Therefore, to meet the cooling needs of extremely cold outdoor spaces during the day, the cold insulation material must change from strict spectral selective radiation to efficient reflection of all wavelengths of incident light, including sunlight and infrared heat, to achieve the purpose of blocking all external heat. Obviously, almost all current radiative cooling materials do not meet this requirement, and even run counter to this requirement. In addition, existing radiative cooling materials have significant absorption in the ultraviolet band, which not only reduces the material's overall reflectivity of sunlight, but also causes ultraviolet aging problems, significantly shortening its service life. In addition, radiation cooling materials often must be of sufficient thickness to achieve multiple backscattering of incident sunlight in order to obtain a sufficiently high reflectivity. However, thick conventional radiation cooling materials are not suitable for cold preservation because most radiation cooling materials have high infrared absorption / radiation characteristics at the window. As a result, the thicker the material, the stronger the absorption of infrared heat. At the same time, the increase in thickness will sacrifice the flexibility of the material, making the processability of the radiation cooling material significantly worse. In addition, the porosity of the graded porous radiation cooling film prepared by conventional phase separation method, template method and other methods is limited. Therefore, it mainly relies on increasing the thickness of the porous film to achieve its high reflectivity of sunlight. Only with sufficient thickness can multiple backscattering of incident sunlight be achieved to obtain a sufficiently high reflectivity. However, this will cause the graded porous radiation cooling film to have defects such as heavy weight and poor flexibility, and is not suitable for covering or setting on the surface of cold preservation equipment.Therefore, obtaining a cold-insulating material with high reflectivity to full-band sunlight, excellent flexibility and long service life is of great significance for improving the cold-insulating performance of the cold-insulating system. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a cold-insulating material with high reflectivity to full-band sunlight, excellent flexibility and long service life, as well as a preparation method and application thereof, in response to the deficiencies in the prior art.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A cold-insulating material comprises a metal film and a fluorocarbon resin-based fiber membrane, wherein the fluorocarbon resin-based fiber membrane is loaded on the metal film; the porosity of the fluorocarbon resin-based fiber membrane is 55% to 85%; and the thickness of the fluorocarbon resin-based fiber membrane is 5 μm to 75 μm.

[0007] The above-mentioned cold-insulating material is further improved in that the fluorocarbon resin-based fiber membrane is a porous membrane composited with fluorocarbon resin-based fibers; the diameter of the fluorocarbon resin-based fibers is distributed between 50 nm and 1.8 μm.

[0008] The above-mentioned cold-insulating material is further improved, wherein the pore size distribution of the fluorocarbon resin-based fiber membrane is between 0.1μm and 7μm; the thickness of the metal film is between 4μm and 100μm; and the metal film is one of aluminum foil and tin foil.

[0009] As a general technical concept, the present invention also provides a method for preparing a cold-insulating material, comprising the following steps:

[0010] (1) mixing a fluorocarbon resin-based polymer and a two-component solvent, and stirring until completely dissolved to obtain a fluorocarbon resin-based polymer solution; the two-component solvent is a mixed solvent of acetone and a non-volatile organic solvent; the mass ratio of the acetone to the non-volatile organic solvent is 0.25 to 4:1;

[0011] (2) mixing the fluorocarbon resin-based polymer solution obtained in step (1) with water and stirring to obtain a spinning solution;

[0012] (3) electrospinning is performed using the spinning solution obtained in step (2) as a raw material, so that the fiber film is deposited on the surface of the metal film, and dried to obtain a thin radiation cooling film.

[0013] The above preparation method is further improved, in step (1), the mass ratio of the fluorocarbon resin-based polymer to the two-component solvent is 1 to 2:10; the fluorocarbon resin-based polymer is at least one of polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride, and polytetrafluoroethylene; and the non-volatile organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0014] The above preparation method is further improved in that, in step (2), the mass ratio of water to the two-component solvent is ≤1:10.

[0015] The above preparation method is further improved in that in step (2), the mass ratio of water to the two-component solvent is 0.1 to 1:10.

[0016] The above preparation method is further improved in that in step (1), the stirring is carried out at a temperature of 25°C to 80°C.

[0017] The above preparation method is further improved in that, in step (2), the stirring is carried out at a temperature of 25°C to 80°C; and the stirring time is ≥10 min.

[0018] The above preparation method is further improved, in which, in step (3), an electrospinning machine is used for electrospinning; the process conditions of the electrospinning are: a spinning temperature of 15°C to 35°C, a spinning humidity of 20% to 60%, a propulsion speed of the spinning solution of 0.6mL / h to 2mL / h, a distance between the spinneret and the collecting plate of 12cm to 30cm, a spinning voltage of 8kV to 12kV, and a drum collector speed of 50rpm to 500rpm.

[0019] The above-mentioned preparation method is further improved, wherein the cold insulation material includes a metal film and a fluorocarbon resin-based fiber membrane, and the fluorocarbon resin-based fiber membrane is loaded on the metal film; the porosity of the fluorocarbon resin-based fiber membrane is 55% to 85%; the thickness of the fluorocarbon resin-based fiber membrane is 5μm to 75μm; the fluorocarbon resin-based fiber membrane is a porous membrane composited by fluorocarbon resin-based fibers; the diameter of the fluorocarbon resin-based fibers is distributed between 50nm and 1.8μm; the pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.1μm and 7μm; the thickness of the metal film is 4μm to 100μm; the metal film is one of aluminum foil and tin foil.

[0020] As a general technical concept, the present invention also provides an application of the above-mentioned cold-insulating material or the cold-insulating material prepared by the above-mentioned preparation method, wherein the application is to cover the cold-insulating material on the surface of the substrate, or to arrange the cold-insulating material on the outside of the substrate.

[0021] The above application is further improved, wherein the substrate includes one of a normal pressure ammonia storage tank, a liquefied natural gas storage tank, a grain depot, an oil depot, a cold chain transport vehicle, a pipeline, and an insulated box.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] (1) In view of the shortcomings of existing radiation cooling materials, such as difficulty in achieving high reflection of full-band sunlight, easy absorption of ultraviolet light, medium-wave infrared, and long-wave infrared heat, and large thickness, which lead to defects such as difficulty in achieving cold preservation effect, poor workability, and short service life, the present invention provides a cold preservation material, including a metal film and a fluorocarbon resin-based fiber membrane, wherein the fluorocarbon resin-based fiber membrane is loaded on the metal film, wherein the porosity of the fluorocarbon resin-based fiber membrane is 55% to 85%, and the thickness of the fluorocarbon resin-based fiber membrane is 5μm to 75μm. Compared with conventional polymer films, the fluorocarbon resin-based fiber membrane used in the present invention can rely on the rich pore structure between fibers to achieve the reflection of sunlight, and the fibers with a smooth surface and a diameter comparable to the reflected light can further improve the film's reflection of full-band sunlight and effective reflection of medium-wave infrared. The existence of this double reflection structure determines that the fluorocarbon resin-based fiber membrane composed of fibers in the present invention can exhibit sunlight reflection performance comparable to or even better than other porous materials at an extremely thin thickness. Specifically, the fluorocarbon resin-based fiber membrane of the present invention can efficiently reflect solar ultraviolet rays, visible light, and near-infrared rays in the range of 350 to 2500 nm, preventing the sun's heat from accumulating on the surface of the shielded object and causing temperature rise. It can also efficiently reflect medium-wave infrared in the band of 2.5 to 8 μm and long-wave infrared in the band of 8 to 25 μm to prevent infrared heat radiated from the surrounding environment from entering the low-temperature box, thereby avoiding rapid temperature rise inside it, and can also further isolate it with the help of the polymer's own low thermal conductivity and the porous structure between the fibers. The conduction of heat energy from the outside to the inside, the three major effects ensure the cold-keeping performance of the material, and can ensure a lasting low-temperature state in the internal space of the object even when the atmospheric temperature is very high. At the same time, since the fluorocarbon resin-based fiber membrane of the present invention can effectively reflect ultraviolet light, it can not only effectively avoid the defect of poor cold-keeping effect caused by the metal film absorbing ultraviolet light, but also effectively prevent ultraviolet light aging of the fluorocarbon resin-based fiber membrane and the metal film, which is beneficial to improving the service life of the fluorocarbon resin-based fiber membrane and the metal film. On this basis, by loading a fluorocarbon resin-based fiber membrane with a thickness of 5μm to 75μm on the metal film, the best match between the fluorocarbon resin-based fiber membrane and the metal film can be achieved, thereby further improving the reflectivity of the metal film to infrared heat, so that the mutual promotion between the fluorocarbon resin-based fiber membrane and the metal film can be utilized to jointly reflect sunlight, and rely on the metal film to reflect all infrared heat, ultimately making the cold-keeping material able to achieve efficient reflection of full-band sunlight and ensure that the interior of the object exhibits excellent cold-keeping effect.Compared with the existing conventional graded porous radiation cooling film, the cold insulation material of the present invention can achieve high reflection of sunlight while being thinner, and thus has lighter weight and better flexibility. It has the advantages of high reflectivity of full-band sunlight, excellent flexibility, and long service life. It is a new type of composite cold insulation material with excellent cold insulation effect. It can be widely used to ensure that the internal space of the cold insulation system maintains a long-term low temperature state. It has high use value and good application prospects.

[0024] (2) In view of the fact that the existing graded porous radiation cooling films are difficult to achieve high reflection of full-band sunlight, easily absorb ultraviolet light, medium-wave infrared, long-wave infrared heat, and are thick, and thus lead to defects such as difficulty in achieving cooling effect, poor processability, and short service life, the present invention creatively proposes a method for preparing cooling materials, which is prepared by electrospinning. By optimizing the components of the spinning solution, a fiber material with a diameter comparable to the wavelength of the reflected light, a smooth surface, and high toughness can be prepared, and then these fibers can be used to composite into a thin fiber film with rich porous structure, thereby ensuring that the fiber film is thin, light, and has high tensile strength. The method significantly improves the reflective performance of the fiber film to sunlight, and eventually forms a cold-insulating material with high reflectivity to sunlight of the entire band. Specifically: fluorocarbon resin-based polymer is used as raw material. It is a semi-crystalline polymer. When precipitated from a solvent, it is easy to crystallize. Therefore, it is easier to achieve high reflectivity of the film material to sunlight of the entire band by regulating the morphology and crystal form of the polymer fiber; on this basis, the morphology and crystal form of the polymer fiber are effectively regulated by optimizing the formula of the spinning solution. By dissolving the fluorocarbon resin-based polymer in a two-component solvent composed of acetone and an organic solvent that is not easily decomposed, acetone can be used to dilute the concentration of the spinning solution and reduce the viscosity of the spinning solution. At the same time, acetone is used to The rapid volatilization of acetone causes the polymer concentration in the spinning solution with low viscosity to increase sharply after contact with air, thereby forming a high-concentration jet during the jet injection process, which is conducive to obtaining thicker (larger diameter) fibers. The fiber diameter becomes thicker, the defects become fewer, and its strength can be improved. However, the rapid volatilization of acetone also increases the viscosity of the spinning solution and the spinning cost, which is not conducive to the stability of the spinning flow, and the surface of the obtained fiber is not smooth enough. Based on this, in the present invention, water is also added to the fluorocarbon resin-based polymer solution. Under the synergistic effect of water and acetone, fibers with comparable diameter and smooth surface can be obtained without excessively increasing the concentration and dosage of the polymer. The addition of water not only reduces the amount of polymer used but also destroys the thermodynamically metastable state of the spinning solution when the acetone evaporates, causing the spinning solution to become unstable and undergo phase separation, thereby accelerating the coagulation of the polymer in the jet. This not only helps to obtain dense fibers but also prevents the polymer from having time to arrange itself regularly, which helps to reduce the crystallinity of the fibers and thus improve the deformability of the molecular chains. Macroscopically, this is manifested as improved toughness. Therefore, the introduction of water effectively solves the problem of difficulty in obtaining smooth and flat coarse fibers from high-concentration spinning solutions. Furthermore, the present invention optimizes the mass ratio of acetone to the non-volatile organic solvent in the two-component solvent to 0.25~4:1, by optimizing the content of acetone in the two-component solvent, not only the spinnability of the spinning solution can be improved, which is beneficial to converting high-concentration spinning solution into smooth and thick fibers, but also the coagulation rate of the spinning solution can be effectively regulated, which is beneficial to the formation of semi-dry fibers, and the semi-dry fibers are disorderly stacked on the surface of the metal film to form a loose structure with high porosity, so that a porous film with rich pores between fibers can be stably loaded on the metal film, thereby not only improving the toughness of the fiber membrane by increasing the porosity of the material, but also achieving high reflectivity of the film under the premise of thin thickness, and then ensuring that the film is light and thin. It also has excellent thermal insulation and cooling properties, and finally obtains a cold-keeping material with high reflectivity of full-band sunlight. In particular, when the ratio of acetone in the two-component solvent is too low (e.g., less than 1:4), the acetone volatilization has little effect on improving the viscosity of the spinning solution. In this case, the low viscosity of the spinning solution makes it difficult to form a normal jet, and droplets still exist when it reaches the collector, resulting in problems such as poor spinnability, excessively fine fibers, and droplet accumulation. When the ratio is too high (greater than 4:1), the resulting fibers become significantly thicker, and the spinning solution can rapidly solidify at the outlet, blocking the pipeline. Compared with other preparation technologies, the present method for preparing graded porous radiative cooling fiber films based on electrospinning technology can achieve low-cost, large-scale production. It also has the advantages of simple process, convenient operation, and mild production conditions, facilitating the industrial application of cold insulation materials.

[0025] (3) The viscosity of the spinning solution plays a decisive role in the uniformity of electrospinning. In addition to the "solvent and polymer type", factors affecting the viscosity of the spinning solution also include the concentration of the polymer in the spinning solution and the amount of water added. Based on this, the preparation method of the present invention optimizes the mass ratio of the fluorocarbon resin-based polymer to the two-component solvent to 1-2:10. By optimizing the concentration of the fluorocarbon resin-based polymer in the spinning solution, the spinning stability can be improved and smooth and coarse fibers can be obtained. If the polymer concentration is too low, it is easy to cause the viscosity of the spinning solution to be low, making it difficult to form a normal jet. When it reaches the collector, there are still droplets, resulting in poor spinnability, too thin fibers, droplet accumulation and other problems. If the polymer concentration is too high, it will seriously affect the uniformity and surface smoothness of the fiber, and will cause the spinning solution to flow poorly, thereby blocking the pipeline. At the same time, the present invention also optimizes the mass ratio of water to the two-component solvent to ≤ 1:10, specifically, the mass ratio of water to the two-component solvent is 0.1 to 1:10, thereby improving the smoothness of the fiber surface and controlling the crystallinity of the fiber. If the water content is too low, the improvement effect is not obvious, while when the ratio of water to the two-component solvent is too high (greater than 1:10), it will cause thermodynamic instability in the spinning solution, induce phase separation prematurely, and form a polymer-rich phase, which manifests as a sharp increase in viscosity and difficulty in spinning.

[0026] (4) In the preparation method of the present invention, the process conditions of electrospinning are also optimized, which can assist in regulating the morphology and porosity of the fiber to meet the reflection requirements of the incident light, and can also help improve the mechanical properties of the fiber.

[0027] (5) The present invention also provides an application of a cold-insulating material, specifically covering the cold-insulating material on the surface of a substrate, or arranging the cold-insulating material on the outside of the substrate. These substrates include but are not limited to atmospheric ammonia storage tanks, liquefied natural gas storage tanks, grain depots, oil depots, cold chain transport vehicles, pipelines, and insulation boxes. Since the cold-insulating material can achieve high reflection of full-band sunlight and can prevent infrared heat radiated from the surrounding environment from entering the interior of the above-mentioned substrate, it can ensure that the internal space of the above-mentioned substrate maintains a long-term low-temperature state, which can greatly save refrigeration energy consumption, has high use value, and good application prospects. At the same time, due to the excellent flexibility of the cold-insulating material, it can be bent and curled at will, thereby significantly improving the processability of these insulation materials, making them more convenient to use, and helping to increase their service life, and having very high market promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0029] Figure 1 This is an SEM image of the cold-insulating material prepared in Example 1 of the present invention.

[0030] Figure 2 This is a spectrum curve diagram of the cold-insulating material prepared in Example 1 of the present invention.

[0031] Figure 3 This is a diagram showing the outdoor cooling effect of the cooling material prepared in Example 1 of the present invention.

[0032] Figure 4 This is a diagram showing the outdoor cooling effect of the thermal insulation material prepared in Comparative Example 1 of the present invention.

[0033] Figure 5 This is a diagram showing the outdoor cooling effect of the commercially available thermal insulation box in Comparative Example 4 of the present invention.

[0034] Figure 6 This is a diagram showing the outdoor cooling effect of the homemade radiant cooling material in Comparative Example 5 of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.

[0036] In the following examples, unless otherwise specified, all materials and instruments used are commercially available.

[0037] The present invention first dissolves the polymer in a two-component solvent to obtain a uniform mixed solution, then adds water and stirs until uniformly dispersed to form a spinning solution, and then deposits the spinning solution onto the surface of a metal film through an electrospinning machine to obtain a wet film. The wet film evaporates and dries in the air to obtain a cold-insulating material.

[0038] Example 1

[0039] A cold-insulating material comprises a metal film and a fluorocarbon resin-based fiber membrane. The fluorocarbon resin-based fiber membrane is loaded on the metal film. The porosity of the fluorocarbon resin-based fiber membrane is 75%, and the thickness of the fluorocarbon resin-based fiber membrane is 23 μm.

[0040] In this embodiment, the fluorocarbon resin-based fiber membrane is a porous membrane formed by a composite of fluorocarbon resin-based fibers, wherein the diameters of the fluorocarbon resin-based fibers are distributed between 100 nm and 1.5 μm.

[0041] In this embodiment, the fluorocarbon resin-based fiber membrane is a polyvinylidene fluoride-hexafluoropropylene fiber membrane, and the pore size distribution of the fluorocarbon resin-based fiber membrane is between 0.3 μm and 5 μm.

[0042] In this embodiment, the thickness of the metal film is 7 μm, and the metal film is tin foil.

[0043] A method for preparing the above-mentioned cold-insulating material comprises the following steps:

[0044] (1) 15 g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) was added to a two-component solvent of 70 g of acetone and 30 g of N,N-dimethylformamide (DMF), and stirred at 50°C until fully dissolved to obtain a polyvinylidene fluoride-hexafluoropropylene solution.

[0045] (2) 5 g of water was added to the solution obtained in step (1), and the mixture was stirred at 50° C. and 250 rpm for 20 min until fully dispersed to obtain a spinning solution.

[0046] (3) The spinning solution prepared in step (2) is sucked into the syringe, the syringe is fixed to the transmitting end, the electrospinning machine is turned on for electrospinning, and after observing that the spinning is stable, the receiver is opened (before opening, a metal film is wrapped on the surface of the receiver), and the fiber is deposited on the surface of the metal film. After the spinning is completed, the metal film is removed from the receiver and dried naturally at room temperature to obtain a cold-insulating material.

[0047] After testing, the thickness of tinfoil was 7μm and the thickness of fiber membrane was 23μm.

[0048] In step (3), the electrospinning experimental parameters are: relative humidity of 40%, temperature of 25° C., voltage of 10 kV, distance of 15 cm, injection speed of 10 μL / min, and drum collector speed of 100 rpm.

[0049] Figure 1 This is a SEM image of the cold-insulating material obtained in Example 1 of the present invention. Figure 1 As can be seen, the fiber membrane in the cold insulation material produced in Example 1 is composed of stacked fibers and is a porous membrane. The fiber surface is dense, flat, and smooth, with fiber diameters ranging from 100 nm to 1.5 μm. The pore size of the fiber membrane is also between 0.3 μm and 5 μm. This indicates that the fiber surface in this fiber membrane is dense, flat, and smooth, and its diameter is comparable to the wavelength of the reflected light. This allows the fiber membrane to effectively scatter incident sunlight, thereby increasing reflectivity.

[0050] Figure 2 This is a spectrum curve of the cold-insulating material obtained in Example 1 of the present invention. Figure 2 It can be seen that the cold insulation material exhibits a high reflectivity for incident light of 0.3 to 25 μm, especially in the sunlight band. The average reflectivity in the 0.3 to 2.5 μm band is 94.77%, and the average infrared reflectivity in the 2.5 to 8 μm, 8 to 13 μm, and 13 to 25 μm bands is 91.4%, 32.5%, and 60.9%, respectively.

[0051] One application of the cold-insulating material prepared in the present embodiment is to cover the cold-insulating material on the surface of a substrate, wherein the substrate is an insulation box (foam box).

[0052] Figure 3 This is a diagram showing the outdoor cooling effect of the cold-insulating material prepared in Example 1 of the present invention. Figure 3 As can be seen, under direct sunlight, at an ambient temperature of up to 36°C, the insulation material can keep the ice in the foam box from melting for four hours, meaning it retains its ice for four hours, and also keeps the ice pack below 10°C for six hours, meaning it retains its cold for six hours. In comparison, a foam box uncovered by insulation or any other material retains its ice for only 30 minutes and its cold for only five hours.

[0053] In the present invention, the application of cold insulation materials is not limited to covering the surface of the substrate, but the cold insulation materials can also be arranged on the outside of the substrate. At the same time, the substrates involved are not limited to insulation boxes. Other substrates such as atmospheric ammonia storage tanks, liquefied natural gas storage tanks, grain depots, oil depots, cold chain transport vehicles, and pipelines can also use the cold insulation materials of the present invention for cold insulation treatment. The substrates involved are not limited to the above-mentioned ones. Any other substrates that need cold insulation treatment can be treated with the cold insulation materials of the present invention.

[0054] Comparative Example 1

[0055] A method for preparing a heat-insulating material is substantially the same as the method for preparing the cold-insulating material in Example 1, except that there is no tin foil substrate and the thickness of the heat-insulating material is 38 μm.

[0056] The spectral test results show that the thermal insulation material prepared in Comparative Example 1 has an average reflectivity of 65.72% in the 0.3-2.5 μm band, and average infrared reflectivities of 44.9%, 5.5% and 11.4% in the 2.5-8 μm, 8-13 μm and 13-25 μm bands, respectively.

[0057] The heat-insulating material prepared in Comparative Example 1 is covered on the surface of the insulation box (foam box). Figure 4 As shown, under sunlight exposure, when the ambient temperature is as high as 36°C, the insulation material in Comparative Example 1 can keep the ice in the foam box for 35 minutes, which is significantly shorter than that in Example 1. The ice pack can only keep the ice cold for 5 hours below 10°C, which is close to that of an uncovered foam box.

[0058] Comparative Example 2

[0059] A commercially available tin foil, the same as the tin foil used in Example 1.

[0060] The outdoor cooling experiment shows that the tin foil in Comparative Example 2 has an average reflectivity of 88.85% in the 0.3-2.5 μm band, and an average infrared reflectivity of 94%, 96% and 97.7% in the 2.5-8 μm, 8-13 μm and 13-25 μm bands, respectively.

[0061] The outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the tin foil in Comparative Example 2 can keep the ice in the foam box for 3 hours and the cooling time is 5 hours and 20 minutes, which is shorter than that in Example 1.

[0062] Comparative Example 3

[0063] A commercially available aluminum foil insulation film with a thickness of 4 mm.

[0064] Outdoor cooling tests showed that under direct sunlight, at ambient temperatures as high as 36°C, the commercially available aluminum foil insulation film in Comparative Example 3 retained ice for only 2.5 hours. The ice pack, at temperatures below 10°C, maintained ice for only 4 hours and 47 minutes, shorter than that in Example 1. This may be due to the wrinkles on the surface of the commercially available aluminum foil insulation film, which affects its sunlight reflection efficiency, resulting in poorer cooling performance than tinfoil.

[0065] Comparative Example 4

[0066] A commercially available thermal insulation box.

[0067] like Figure 5 As shown, the outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the ice preservation time of the commercially available insulation box in Comparative Example 4 is only maintained for 2 hours, and the cooling time of the ice bag below 10°C is only 3 hours and 5 minutes, which is significantly shorter than that of Example 1.

[0068] Comparative Example 5

[0069] A self-made, excellent spectrally selective radiative cooling material has a remarkable radiative cooling effect on objects and spaces at room temperature. The preparation process for this spectrally selective radiative cooling material is as follows: PVDF-HFP powder, acetone, and water are weighed in a mass ratio of 12:80.5:7.5. The PVDF-HFP and acetone are first mixed and placed in a 50°C water bath, stirred at 150 rpm until the PVDF-HFP powder is completely dissolved. Water is then slowly added with continuous stirring until a colorless, transparent spray solution is formed. The precursor solution is sprayed onto a clean cloth using a spray gun to form a wet film. The vertical distance between the nozzle and the substrate is controlled to be 30 cm, the pressure is controlled to be 4-4.5 MPa, and the movement speed is controlled to be 25 cm / s. After spraying, the wet film is secured with a clamp and placed in a fume hood. After the acetone evaporates naturally, the film is transferred to a vacuum oven at 30°C for 10 hours to remove excess water, thereby obtaining the spectrally selective radiative cooling material.

[0070] The spectral test results show that the radiation cooling material with a thickness of 300 μm prepared in Comparative Example 5 has an average reflectivity of 90.89% in the 0.3-2.5 μm band, and average infrared reflectivities of 53.16%, 5.4%, and 13.84% in the 2.5-8 μm, 8-13 μm, and 13-25 μm bands, respectively.

[0071] like Figure 6 As shown, the outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the ice-keeping time of the radiation cooling material in Comparative Example 5 is only 1 hour, and the cooling time can last for 5 hours and 15 minutes, which is shorter than that of Example 1. This shows that the cooling effect, especially the ice-keeping effect, of the existing spectrally selective radiation cooling material is indeed inferior to that of the fully reflective cooling material.

[0072] Example 2

[0073] A method for preparing a cold-insulating material is substantially the same as the method for preparing the cold-insulating material in Example 1, with the only difference being that the amount of polyvinylidene fluoride-hexafluoropropylene used in step (1) is 18 g.

[0074] The cold insulation material prepared in Example 2 includes a metal film and a fluorocarbon resin-based fiber membrane. The fluorocarbon resin-based fiber membrane is loaded on the metal film. The porosity of the fluorocarbon resin-based fiber membrane is 65%, and the thickness of the fluorocarbon resin-based fiber membrane is 22 μm. The fluorocarbon resin-based fiber membrane is a porous membrane composited with fluorocarbon resin-based fibers, wherein the diameter of the fluorocarbon resin-based fibers is distributed between 200 nm and 1.5 μm. The fluorocarbon resin-based fiber membrane is a polyvinylidene fluoride-hexafluoropropylene fiber membrane, and the pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.3 μm and 3 μm. The thickness of the metal film is 7 μm, and the metal film is tin foil.

[0075] The spectral test results show that the cold insulation material (thickness 29 μm) prepared in Example 2 has an average reflectivity of 94.32% in the 0.3-2.5 μm band, and average infrared reflectivities of 89.3%, 33.5%, and 61.1% in the 2.5-8 μm, 8-13 μm, and 13-25 μm bands, respectively.

[0076] The outdoor cold preservation experiment shows that when the ambient temperature is as high as 36°C under sunlight, the cold preservation material prepared in Example 2 can keep the ice in the foam box for 3.5 hours.

[0077] Example 3

[0078] A method for preparing a cold-insulating material is substantially the same as the method for preparing the cold-insulating material in Example 1, with the only difference being that the amount of water used in step (2) is 7.5 g.

[0079] The cold insulation material prepared in Example 3 includes a metal film and a fluorocarbon resin-based fiber membrane. The fluorocarbon resin-based fiber membrane is loaded on the metal film. The porosity of the fluorocarbon resin-based fiber membrane is 65%, and the thickness of the fluorocarbon resin-based fiber membrane is 22 μm. The fluorocarbon resin-based fiber membrane is a porous membrane composited with fluorocarbon resin-based fibers, wherein the diameter of the fluorocarbon resin-based fibers is distributed between 400 nm and 1.5 μm. The fluorocarbon resin-based fiber membrane is a polyvinylidene fluoride-hexafluoropropylene fiber membrane, and the pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.4 μm and 3.5 μm. The thickness of the metal film is 7 μm, and the metal film is tin foil.

[0080] The spectral test results show that the cold insulation material (thickness 29 μm) prepared in Example 3 has an average reflectivity of 91.87% in the 0.3-2.5 μm band, and average infrared reflectivities of 84.3%, 33.4%, and 60.9% in the 2.5-8 μm, 8-13 μm, and 13-25 μm bands, respectively.

[0081] The outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the cooling material prepared in Example 3 can keep the ice in the foam box for 3 hours and 20 minutes.

[0082] Example 4

[0083] A method for preparing a cold-insulating material is substantially the same as the method for preparing the cold-insulating material in Example 1, with the only difference being that the amount of water used in step (2) is 2.5 g.

[0084] The cold insulation material prepared in Example 4 includes a metal film and a fluorocarbon resin-based fiber membrane. The fluorocarbon resin-based fiber membrane is loaded on the metal film. The porosity of the fluorocarbon resin-based fiber membrane is 80%, and the thickness of the fluorocarbon resin-based fiber membrane is 25 μm. The fluorocarbon resin-based fiber membrane is a porous membrane composited with fluorocarbon resin-based fibers, wherein the diameter of the fluorocarbon resin-based fibers is distributed between 100 nm and 1 μm. The fluorocarbon resin-based fiber membrane is a polyvinylidene fluoride-hexafluoropropylene fiber membrane, and the pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.8 μm and 7 μm. The thickness of the metal film is 7 μm, and the metal film is tin foil.

[0085] The spectral test results show that the cold insulation material (thickness 32μm) prepared in Example 4 has an average reflectivity of 93.52% in the 0.3-2.5μm band, and average infrared reflectivities of 85.3%, 31.1%, and 59.6% in the 2.5-8μm, 8-13μm, and 13-25μm bands, respectively.

[0086] The outdoor cold preservation experiment shows that when the ambient temperature is as high as 36°C under sunlight, the cold preservation material prepared in Example 4 can keep the ice in the foam box for 3.5 hours.

[0087] Example 5

[0088] A method for preparing a cold-insulating material is substantially the same as the method for preparing the cold-insulating material in Example 1, with the only difference being that the two-component solvent in step (1) is composed of 30 g acetone and 70 g DMF.

[0089] The cold insulation material prepared in Example 5 includes a metal film and a fluorocarbon resin-based fiber membrane. The fluorocarbon resin-based fiber membrane is loaded on the metal film. The porosity of the fluorocarbon resin-based fiber membrane is 70%, and the thickness of the fluorocarbon resin-based fiber membrane is 25 μm. The fluorocarbon resin-based fiber membrane is a porous membrane composited with fluorocarbon resin-based fibers, wherein the diameter of the fluorocarbon resin-based fibers is distributed between 60 nm and 500 nm. The fluorocarbon resin-based fiber membrane is a polyvinylidene fluoride-hexafluoropropylene fiber membrane, and the pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.2 μm and 2 μm. The thickness of the metal film is 7 μm, and the metal film is tin foil.

[0090] The spectral test results show that the cold-insulating material (thickness 32 μm) prepared in Example 5 has an average reflectivity of 91.13% in the 0.3-2.5 μm band, and average infrared reflectivities of 86.2%, 30.5%, and 54.4% in the 2.5-8 μm, 8-13 μm, and 13-25 μm bands, respectively.

[0091] The outdoor cold preservation experiment shows that when the ambient temperature is as high as 36°C under sunlight, the cold preservation material prepared in Example 5 can keep the ice in the foam box for 3 hours.

[0092] Example 6

[0093] A method for preparing a cold-insulating material is substantially the same as the method for preparing the cold-insulating material in Example 1, except that the two-component solvent in step (1) is 30 g of acetone and 70 g of DMF; and the amount of water in step (2) is 7.5 g.

[0094] The cold insulation material prepared in Example 6 includes a metal film and a fluorocarbon resin-based fiber membrane. The fluorocarbon resin-based fiber membrane is loaded on the metal film. The porosity of the fluorocarbon resin-based fiber membrane is 70%, and the thickness of the fluorocarbon resin-based fiber membrane is 23 μm. The fluorocarbon resin-based fiber membrane is a porous membrane composited with fluorocarbon resin-based fibers, wherein the diameter of the fluorocarbon resin-based fibers is distributed between 50 nm and 500 nm. The fluorocarbon resin-based fiber membrane is a polyvinylidene fluoride-hexafluoropropylene fiber membrane, and the pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.1 μm and 1 μm. The thickness of the metal film is 7 μm, and the metal film is tin foil.

[0095] The spectral test results show that the cold-insulating material (thickness 30 μm) prepared in Example 6 has an average reflectivity of 91.89% in the 0.3-2.5 μm band, and average infrared reflectivities of 86.4%, 31.6%, and 58.1% in the 2.5-8 μm, 8-13 μm, and 13-25 μm bands, respectively.

[0096] The outdoor cold preservation experiment shows that when the ambient temperature is as high as 36°C under sunlight, the cold preservation material prepared in Example 6 can keep the ice in the foam box for 3 hours and 10 minutes.

[0097] Example 7

[0098] A method for preparing a cold-insulating material is basically the same as the method for preparing a cold-insulating material in Example 1, with the only difference being that in step (3), the electrospinning experimental parameters are: a distance of 30 cm and a drum collector speed of 400 rpm.

[0099] The cold insulation material prepared in Example 7 includes a metal film and a fluorocarbon resin-based fiber membrane. The fluorocarbon resin-based fiber membrane is loaded on the metal film. The porosity of the fluorocarbon resin-based fiber membrane is 82%, and the thickness of the fluorocarbon resin-based fiber membrane is 26 μm. The fluorocarbon resin-based fiber membrane is a porous membrane composited with fluorocarbon resin-based fibers, wherein the diameter of the fluorocarbon resin-based fibers is distributed between 50 nm and 400 nm. The fluorocarbon resin-based fiber membrane is a polyvinylidene fluoride-hexafluoropropylene fiber membrane, and the pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.1 μm and 2 μm. The thickness of the metal film is 7 μm, and the metal film is tin foil.

[0100] The spectral test results show that the cold-insulating material (thickness 33 μm) prepared in Example 7 has an average reflectivity of 91.23% in the 0.3-2.5 μm band, and average infrared reflectivities of 85.4%, 29.6%, and 54.8% in the 2.5-8 μm, 8-13 μm, and 13-25 μm bands, respectively.

[0101] The outdoor cold preservation experiment shows that when the ambient temperature is as high as 36°C under sunlight, the cold preservation material prepared in Example 7 can keep the ice in the foam box for 3 hours.

[0102] Example 8

[0103] A cold-insulating material is substantially the same as the cold-insulating material in Example 1, except that the thickness of the fiber membrane is 53 μm.

[0104] Spectral test results show that the cold-insulating material (60 μm thick) prepared in Example 8 has an average reflectance of 94.89% in the 0.3-2.5 μm band, and average infrared reflectances of 71.1%, 11.3%, and 23.8% in the 2.5-8 μm, 8-13 μm, and 13-25 μm bands, respectively. This indicates that as the material thickness increases, its spectral behavior changes from total reflection to partial selective absorption / radiation.

[0105] The outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the cooling material prepared in Example 8 can keep the ice in the foam box for 2.5 hours, which is still better than that of Comparative Example 5.

[0106] Example 9

[0107] A method for preparing a cold-insulating material is substantially the same as the method for preparing the cold-insulating material in Example 1, with the only difference being that polyvinylidene fluoride-hexafluoropropylene is replaced with polyvinylidene fluoride in step (1).

[0108] The cold insulation material prepared in Example 9 includes a metal film and a fluorocarbon resin-based fiber membrane. The fluorocarbon resin-based fiber membrane is loaded on the metal film. The porosity of the fluorocarbon resin-based fiber membrane is 72%, and the thickness of the fluorocarbon resin-based fiber membrane is 27 μm. The fluorocarbon resin-based fiber membrane is a porous membrane composited with fluorocarbon resin-based fibers, wherein the diameter of the fluorocarbon resin-based fibers is distributed between 100 nm and 1 μm. The fluorocarbon resin-based fiber membrane is a polyvinylidene fluoride fiber membrane, and the pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.3 μm and 5 μm. The thickness of the metal film is 7 μm, and the metal film is tin foil.

[0109] The spectral test results show that the cold insulation material (thickness 34 μm) prepared in Example 9 has an average reflectivity of 90.12% in the 0.3-2.5 μm band, and average infrared reflectivities of 83.4%, 27.6%, and 49.9% in the 2.5-8 μm, 8-13 μm, and 13-25 μm bands, respectively.

[0110] The outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the cooling material prepared in Example 9 can keep the ice in the foam box for 2 hours and 50 minutes.

[0111] Comparative Example 6

[0112] A method for preparing a heat-insulating material is basically the same as the method for preparing a cold-insulating material in Example 1, except that the two-component solvent in step (1) is changed to a single-component DMF, the amount used is 100 g, and the thickness of the fiber membrane is 28 μm.

[0113] The spectral test results show that the thermal insulation material with a thickness of 35 μm prepared in Comparative Example 6 has an average reflection of 78.12% in the 0.3-2.5 μm band, and average infrared reflectivity of 73.9%, 20.8% and 36.6% in the 2.5-8 μm, 8-13 μm and 13-25 μm bands, respectively.

[0114] The outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the thermal insulation material prepared in Comparative Example 6 can maintain the ice retention time in the foam box for 50 minutes.

[0115] Comparative Example 7

[0116] A method for preparing a heat-insulating material is substantially the same as the method for preparing a cold-insulating material in Example 1, with the only difference being that the two-component solvent in step (1) is composed of 90 g acetone and 10 g NMP.

[0117] As a result, the spinning solution easily clogs the pipes and needles and is not spinnable.

[0118] Comparative Example 8

[0119] A method for preparing a heat-insulating material is substantially the same as the method for preparing a cold-insulating material in Example 1, with the only difference being that no water is added in step (2).

[0120] The spectral test results show that the thermal insulation material with a thickness of 33 μm prepared in Comparative Example 8 has an average reflection of 88.47% in the 0.3-2.5 μm band, and average infrared reflectivity of 82.3%, 29.1% and 44.1% in the 2.5-8 μm, 8-13 μm and 13-25 μm bands, respectively.

[0121] The outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the thermal insulation material prepared in Comparative Example 8 can maintain the ice retention time in the foam box for 2.5 hours.

[0122] Comparative Example 9

[0123] A method for preparing a heat-insulating material is substantially the same as the method for preparing a cold-insulating material in Example 1, except that: the amount of polyvinylidene fluoride-hexafluoropropylene used in step (1) is 21 g; and the amount of water used in step (2) is 1.0 g.

[0124] As a result, the viscosity of the spinning solution was too high, which caused the jet to be unstable and made spinning difficult to complete.

[0125] Comparative Example 10

[0126] A method for preparing a heat-insulating material is substantially the same as the method for preparing a cold-insulating material in Example 1, with the only difference being that the amount of water used in step (2) is 12 g.

[0127] As a result, the spinning solution easily clogs the pipes and needles and is not spinnable.

[0128] Comparative Example 11

[0129] A method for preparing a thermal insulation material is substantially the same as the method for preparing a cold insulation material in Example 1, except that: in step (1), the amount of polyvinylidene fluoride-hexafluoropropylene used is 5 g; the two-component solvent composition is 50 g acetone and 50 g DMF; and no water is added in step (2).

[0130] The spectral test results show that the thermal insulation material with a thickness of 36 μm prepared in Comparative Example 11 has an average reflection of 83.72% in the 0.3-2.5 μm band, and average infrared reflectivity of 74.7%, 28.7% and 37.6% in the 2.5-8 μm, 8-13 μm and 13-25 μm bands, respectively.

[0131] The outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the thermal insulation material prepared in Comparative Example 11 can maintain the ice retention time in the foam box for 1.5 hours.

[0132] Comparative Example 12

[0133] A method for preparing a heat-insulating material is substantially the same as the method for preparing a cold-insulating material in Example 1, except that: the amount of polyvinylidene fluoride-hexafluoropropylene used in step (1) is 5 g; and the two-component solvent composition is 50 g acetone and 50 g DMF.

[0134] The spectral test results show that the thermal insulation material with a thickness of 41 μm prepared in Comparative Example 12 has an average reflection of 85.13% in the 0.3-2.5 μm band, and average infrared reflectivity of 76.5%, 29.2% and 36.8% in the 2.5-8 μm, 8-13 μm and 13-25 μm bands, respectively.

[0135] The outdoor cooling experiment shows that when the ambient temperature is as high as 36°C under sunlight, the thermal insulation material prepared in Comparative Example 12 can maintain the ice retention time in the foam box for 1 hour and 35 minutes.

[0136] From the above results, it can be seen that compared with the existing conventional graded porous radiation cooling film, the cold insulation material of the present invention can achieve high reflection of sunlight under the premise of thin thickness, thus having lighter weight and more excellent flexibility. It has the advantages of high reflectivity of full-band sunlight, excellent flexibility, and long service life. It is a new type of composite cold insulation material with excellent cold insulation effect. It can be widely used to ensure that the internal space of the cold insulation system maintains a long-term low temperature state. It has high use value and good application prospects. At the same time, compared with other preparation technologies, the method of preparing graded porous radiation cooling fiber film based on electrospinning technology of the present invention can achieve low-cost and large-scale preparation. It also has the advantages of simple process, convenient operation, mild production conditions, etc., which facilitates the industrial application of cold insulation materials.

[0137] The foregoing description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the foregoing embodiment. Any technical solution that falls within the scope of protection of the present invention is within the scope of protection of the present invention. It should be noted that improvements and modifications that can be made by a person skilled in the art without departing from the principles of the present invention are also considered to be within the scope of protection of the present invention.

Claims

1. A cold insulation material, characterized in that: The invention relates to a cold-insulating material comprising a metal film and a fluorocarbon resin-based fiber membrane, wherein the fluorocarbon resin-based fiber membrane is supported on the metal film; the porosity of the fluorocarbon resin-based fiber membrane is 55% to 85%; the thickness of the fluorocarbon resin-based fiber membrane is 5 μm to 75 μm; the diameter of the fluorocarbon resin-based fiber is distributed between 50 nm and 1.8 μm; and the preparation method of the cold-insulating material comprises the following steps: (a) mixing a fluorocarbon resin-based polymer and a two-component solvent and stirring until completely dissolved to obtain a fluorocarbon resin-based polymer solution; the two-component solvent is a mixed solvent of acetone and a non-volatile organic solvent; the mass ratio of the acetone to the non-volatile organic solvent is 0.25 to 4:1; the mass ratio of the fluorocarbon resin-based polymer to the two-component solvent is 1 to 2:10; the non-volatile organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide; and the fluorocarbon resin-based polymer is at least one of polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride, and polytetrafluoroethylene; (b) mixing the fluorocarbon resin-based polymer solution obtained in step (a) with water and stirring to obtain a spinning solution; wherein the mass ratio of the water to the two-component solvent is ≤1:10; (c) electrospinning is performed using the spinning solution obtained in step (b) as a raw material to deposit a fiber film on the surface of the metal film, and drying is performed to obtain a cold-insulating material.

2. The cold insulation material according to claim 1, characterized in that: The pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.1 μm and 7 μm; the thickness of the metal film is 4 μm to 100 μm; and the metal film is one of aluminum foil and tin foil.

3. A method for preparing a cold-insulating material, characterized in that: The following steps are involved: (1) A fluorocarbon resin-based polymer and a two-component solvent are mixed and stirred until completely dissolved to obtain a fluorocarbon resin-based polymer solution; the two-component solvent is a mixed solvent of acetone and a non-volatile organic solvent; the mass ratio of the acetone to the non-volatile organic solvent is 0.25 to 4:1; the mass ratio of the fluorocarbon resin-based polymer to the two-component solvent is 1 to 2:10; the non-volatile organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide; the fluorocarbon resin-based polymer is at least one of polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride, and polytetrafluoroethylene; (2) mixing the fluorocarbon resin-based polymer solution obtained in step (1) with water and stirring to obtain a spinning solution; the mass ratio of the water to the two-component solvent is ≤1:10; (3) Electrospinning is performed using the spinning solution obtained in step (2) as a raw material, so that the fiber membrane is deposited on the surface of the metal film, and dried to obtain a cold-insulating material; the cold-insulating material comprises a metal film and a fluorocarbon resin-based fiber membrane, and the fluorocarbon resin-based fiber membrane is loaded on the metal film; the porosity of the fluorocarbon resin-based fiber membrane is 55% to 85%; the thickness of the fluorocarbon resin-based fiber membrane is 5 μm to 75 μm; the diameter of the fluorocarbon resin-based fiber is distributed between 50 nm and 1.8 μm.

4. The preparation method according to claim 3, characterized in that In step (2), the mass ratio of water to the two-component solvent is 0.1 to 1:

10.

5. The preparation method according to claim 3 or 4, characterized in that In step (1), the stirring is carried out at a temperature of 25°C to 80°C; In step (2), the stirring is carried out at a temperature of 25°C to 80°C; the stirring time is ≥ 10 min; In step (3), electrospinning is performed using an electrospinning machine; the process conditions of the electrospinning are: spinning temperature of 15°C to 35°C, spinning humidity of 20% to 60%, propulsion speed of the spinning solution of 0.6 mL / h to 2 mL / h, the distance between the spinneret and the collecting plate of 12 cm to 30 cm, the spinning voltage of 8 kV to 12 kV, and the rotating speed of the drum collector of 50 rpm to 500 rpm; The pore size of the fluorocarbon resin-based fiber membrane is distributed between 0.1 μm and 7 μm; the thickness of the metal film is 4 μm to 100 μm; and the metal film is one of aluminum foil and tin foil.

6. Use of the cold-insulating material according to claim 1 or 2 or the cold-insulating material prepared by the preparation method according to any one of claims 3 to 5, characterized in that: The application is to cover the surface of the substrate with the cold-insulating material, or to arrange the cold-insulating material on the outside of the substrate.

7. The use according to claim 6, characterized in that The substrate includes one of a normal pressure ammonia storage tank, a liquefied natural gas storage tank, a grain depot, an oil depot, a cold chain transport vehicle, a pipeline, and an insulation box.

Images