A core material containing a molten salt and its use in nano-thermal insulation panels

Abstract

This invention relates to the field of thermal insulation panels, and addresses the problem of shrinkage of nano-insulation panels when heated by providing a core material containing molten salt and its application in nano-insulation panels. The preparation method of the core material includes the following steps: (1) mixing thermal insulation filler, reinforcing fibers, molten salt and additives uniformly to obtain a mixture, wherein the molten salt is a mixture of zinc chloride and aluminum chloride; (2) pressing the mixture into shape, then heating it to cause a phase change in the molten salt and then cooling it to obtain the core material of the nano-insulation panel. By heating the molten salt at high temperature to melt it, it penetrates into the interior of the thermal insulation material, and then cools and solidifies it, thereby strengthening the internal structure and providing thermal insulation performance. The resulting high latent heat nano-insulation panel has excellent compressive strength and low high-temperature thermal conductivity. This invention also provides the application of the core material in nano-insulation panels by vacuum sealing the core material to obtain the nano-insulation panel.

Description

Technical Field

[0001] This invention relates to the field of insulation boards, and in particular to a core material containing molten salt and its application in nano-insulation boards. Background Technology

[0002] Nano-insulation panels are a new type of lightweight thermal insulation material composed of nanoparticles, inorganic fibers, and light-blocking agents. Their thermal conductivity is generally below 5.0 mW / (m·K). Under the same thickness conditions, the thermal insulation effect of nano-insulation panels is approximately 10 times that of traditional thermal insulation materials (polystyrene boards, polyurethane foam, aerogel, etc.).

[0003] The U.S. Atomic Energy Commission (AEC) disclosed a method for preparing an inorganic fiber insulation material in U.S. Patent No. 3,634,563. This method uses silica and chopped glass fibers, quartz fibers, and other oxide-reinforced fibers as raw materials, ethyl acetate as a surface wetting agent, and organic acids (such as octanoic acid) as binders and pressing aids. A low-density insulation material is prepared through pressing and high-temperature sintering. However, the preparation process requires sintering at 900°C for approximately 6 hours, resulting in high energy consumption and hindering industrial production. The AEC also collaborated with Johns Manville to develop a product using silica and quartz fibers, under a brand name... Thermal insulation materials, due to their low thermal conductivity and good load-bearing capacity, are used in radioisotope thermal generators (RTGs) to reduce the impact of high-temperature environments on the RTG (Even, WR, Manesis, NJ, and Skibo, MD. Dimensional instabilities in Min-K 1400 above its expected service temperature. United States: Np, 1981. Web. doi: 10.2172 / 6396755.). However, reports show that when the long-term operating temperature is above 900℃, At 1400°C, severe and irreversible contraction occurs, and this becomes more pronounced as the temperature increases.

[0004] Chinese patent CN109384449B discloses a nano-insulation material that uses nanoparticles (such as silica nanoparticles), inorganic fibers (such as quartz fibers), and light-blocking agents (such as silicon carbide) as raw materials to prepare an insulation material with low density, low thermal conductivity, and excellent mechanical properties. However, the silica particles in this material have extremely low density and lack a binder during the preparation process, resulting in powder shedding in the pressed insulation material, which is detrimental to its widespread use.

[0005] Therefore, an ideal solution is needed. Summary of the Invention

[0006] To overcome the problem of shrinkage when heated, this invention provides a core material containing molten salt and its application in nano-insulation panels. The molten salt is heated at high temperature to melt it, allowing it to penetrate into the interior of the insulation material. It is then cooled and solidified, thereby strengthening the internal structure and providing insulation performance. The resulting high latent heat nano-insulation panel has excellent compressive strength and low high-temperature thermal conductivity.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A core material containing molten salt, the preparation method includes the following steps:

[0009] (1) The heat insulation filler, reinforcing fiber, molten salt and additives are mixed evenly to obtain a mixture, wherein the molten salt is a mixture of zinc chloride and aluminum chloride;

[0010] (2) The mixture is pressed into shape, then heated to cause the molten salt to undergo a phase change and then cooled to obtain the nano-insulation board core material.

[0011] The aforementioned heat-insulating fillers and reinforcing fibers are all raw materials commonly used in nano-insulation panels. The additives are added according to actual performance requirements, such as light-blocking agents, binders, and plasticizers. The pressing and molding process uses a vacuum hot press or a machine capable of providing equivalent functionality. The pressing parameters (pressure, time, etc.) are the same as those for conventional nano-insulation panel core materials. However, this invention adds an extra heating and cooling step after adding molten salt. First, heating causes the molten salt to undergo a phase change, transforming it from a solid to a liquid state, dissolving the molten salt and allowing it to penetrate evenly into the core material. Then, cooling solidifies the dissolved molten salt again, transforming it from a liquid to a solid state, reinforcing the internal structure of the insulation panel core material, thereby providing heat insulation performance.

[0012] The molten salt used in this invention needs to have two key characteristics. First, it requires a low phase transition temperature, as excessively high heating and melting temperatures during the pressing process increase processing costs and negatively impact the microstructure of the nano-insulation board core material, thus affecting its performance. Second, it needs a large latent heat of phase transition to allow the nano-insulation board core material to store more heat and reduce temperature fluctuations. The inventors had previously tested other binary composite molten salt combinations, such as sodium chloride-zinc chloride (too high phase transition temperature) and potassium chloride-aluminum chloride (too low latent heat of phase transition). The composite molten salt of zinc chloride and aluminum chloride combines the advantages of both low phase transition temperature and large latent heat of phase transition.

[0013] Preferably, the molar ratio of zinc chloride to aluminum chloride is (0.5-2):1, and more preferably 1:1. The molar ratio of zinc chloride to aluminum chloride directly affects its phase transition temperature and latent heat of phase transition. The latent heat of phase transition is relatively large in the range of (0.5-2):1, and the phase transition temperature is the lowest at 1:1.

[0014] Preferably, the heating temperature is 120-300℃, and more preferably 120-150℃.

[0015] As a preferred embodiment, by weight, the composition comprises 500-600 parts of heat-insulating filler, 50-200 parts of reinforcing fiber, 100-200 parts of molten salt, and 10-50 parts of additives.

[0016] Preferably, the heat-insulating filler is selected from one or more of fumed silica nanoparticles, zirconium oxide nanoparticles, and alumina nanoparticles, and more preferably fumed silica nanoparticles.

[0017] The reinforcing fiber is selected from one or more of quartz fiber, high silica fiber, alumina fiber, mullite fiber, and aluminosilicate fiber, and is more preferably quartz fiber; the reinforcing fiber is dispersed by a high-speed disperser at a stirring speed of 500-1000 r / min for 1-5 min.

[0018] The additive is silicon carbide powder, which has the function of suppressing radiative heat transfer.

[0019] Preferably, the mixing method is mechanical fusion, specifically stirring at a speed of 1000-1500 r / min for 30-60 min.

[0020] Preferably, the pressing conditions are: molding speed 0.1-50 mm / s, pressure 0.5-5 MPa; and the heating and pressure holding time is 10-20 min.

[0021] The present invention also provides the application of the core material in a nano-insulation board, wherein the core material prepared above is vacuum-sealed to obtain a nano-insulation board.

[0022] Preferably, the vacuum sealing is performed in a barrier bag, which is made by placing two layers of barrier film into a sealing machine, controlling the sealing temperature at 160-200℃, and sealing three sides to obtain a bagged barrier bag; the thickness of a single barrier film is 0.1-0.2mm. More preferably, the barrier film is an aluminum-plastic film.

[0023] Preferably, the vacuum sealing uses a vacuum heat sealer with a vacuum degree of 0.1-2 Pa, more preferably 0.1 Pa; and the vacuum is continuously pumped for 5-10 min, more preferably 6 min.

[0024] Preferably, the thickness of the molten salt nano-insulation board is 2-80 mm, and more preferably 3-20 mm.

[0025] Therefore, the beneficial effects of the present invention are as follows:

[0026] (1) The addition of molten salt strengthens the interaction between nanoparticles, significantly improves the problem of easy powder shedding on the surface, improves the strength of nano insulation board in terms of material mechanics, and makes it difficult to extract particles during vacuum sealing, which plays a certain role in protecting operators, reduces the manufacturing technical difficulty of nano insulation board and lowers the cost.

[0027] (2) Nano heat insulation boards have higher latent heat. In the field of thermal protection, molten salts can absorb or release more heat during the phase change process, making them more effective in temperature control and able to maintain the required temperature for a longer time.

[0028] (3) The preparation method provided by the present invention is simple and controllable, low in energy consumption, low in price, environmentally friendly, safe and pollution-free, and produces no harmful gases or waste. Therefore, it is easy to realize industrial production and has great potential for promotion and application value. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the nano-insulation board prepared according to the present invention;

[0030] Figure 2 This is a SEM image of the nano-insulation board core material prepared in Example 1;

[0031] Figure 3 This is a SEM image of the nano-insulation board core material prepared in Comparative Example 1.

[0032] Figure 4 It is an AlCl3-ZnCl2 binary phase diagram. Detailed Implementation

[0033] The technical solution of the present invention will be further described below through specific embodiments.

[0034] In this invention, unless otherwise specified, the raw materials and equipment used are commercially available or commonly used in the art. The methods in the embodiments, unless otherwise specified, are conventional methods in the art. Unless otherwise specified, all parts are parts by weight, temperatures are expressed in °C or at ambient temperature, and pressures are at or near atmospheric pressure. Various variations and combinations of reaction conditions (e.g., component concentrations, required solvents, solvent mixtures, temperature, pressure, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the product obtained by the method exist, and only reasonable routine experiments are needed to optimize such method conditions.

[0035] A core material containing molten salt, the preparation method includes the following steps:

[0036] (1) Ingredients: By weight, 500-600 parts of thermal insulation filler, 50-200 parts of reinforcing fiber, 10-50 parts of additives, and 100-200 parts of molten salt (a mixture of zinc chloride and aluminum chloride) are mixed evenly to obtain a mixture. The above-mentioned thermal insulation filler and reinforcing fiber are all raw materials commonly used in nano-insulation panels. The additives are added according to actual performance requirements, such as light-blocking agents, binders, plasticizers, etc.

[0037] Preferably, the heat-insulating filler is selected from one or more of fumed silica nanoparticles, zirconium oxide nanoparticles, and alumina nanoparticles, more preferably fumed silica nanoparticles. The reinforcing fiber is selected from one or more of quartz fiber, high-silica fiber, alumina fiber, mullite fiber, and aluminosilicate fiber, more preferably quartz fiber; the reinforcing fiber is dispersed by a high-speed disperser at a stirring speed of 500-1000 r / min for 1-5 min. The additive is silicon carbide powder, which has the function of inhibiting radiative heat transfer. The molar ratio of zinc chloride to aluminum chloride is (0.5-2):1, more preferably 1:1. Theoretically, molten salts can achieve the purpose of this invention, but considering that heating to the phase transition temperature of the molten salt is required during the pressing process, which affects the processing cost, the phase transition temperature of a mixture of zinc chloride and aluminum chloride is more suitable.

[0038] The mixing method is mechanical fusion, specifically stirring at a speed of 1000-1500 r / min for 30-60 min.

[0039] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper and pressed to a pressure of 0.5-5MPa by a press at a molding speed of 0.1-50mm / s. Then, the temperature is raised to 120-300℃ (more preferably 120-150℃) and kept at the temperature and pressure for 10-20min. Finally, the core material of the nano-insulation board is obtained by cooling, depressurizing and demolding.

[0040] The pressing and molding process employs a vacuum hot press molding machine or a machine capable of providing equivalent functionality. The pressing parameters (pressure, time, etc.) are the same as those for conventional nano-insulation board core materials. However, this invention adds an extra heating and cooling step after adding molten salt. First, heating causes the molten salt to undergo a phase change, transforming it from a solid to a liquid state, allowing the molten salt to dissolve and uniformly penetrate into the core material. Then, cooling solidifies the dissolved molten salt again, transforming it from a liquid to a solid state, thus reinforcing the internal structure of the insulation board core material and providing thermal insulation performance.

[0041] This invention also provides the application of the core material in a nano-insulation panel, comprising the following steps:

[0042] 1) Homemade barrier bag: Place two layers of barrier film (preferably aluminum-plastic film) into a sealing machine, control the sealing temperature to 160-200℃, seal three sides to obtain a barrier bag; the thickness of a single layer of barrier film is 0.1-0.2mm.

[0043] 2) Place the core material into the self-made barrier bag of step 1), and place the self-made barrier bag into a vacuum heat sealer for vacuum sealing to obtain a nano-insulation board; specifically: wait until the vacuum degree reaches 0.1-2Pa, continue to evacuate for 5-10 minutes, and then seal; the thickness of the nano-insulation board is 2-80mm (more preferably 3-20mm).

[0044] Example 1

[0045] A core material containing molten salt, prepared by the following method:

[0046] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, ZnCl2 and AlCl3 are mixed in a molar ratio of 1:1 to form a molten salt additive; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder and molten salt additive are mixed in a mass ratio of 600:200:50:200 and mixed evenly using a mechanical fusion machine with a speed of 1200 r / min and a stirring time of 50 min to obtain a mixture.

[0047] (2) Core Material Compression Molding: The mixture obtained in step (1) is laid into the compression mold using a scraper. The mixture is then compressed using a vacuum hot press with a pressure of 3 MPa and a molding speed of 5 mm / s. The mixture is then heated and held under pressure at 130°C and 3 MPa for 20 minutes. After heating, the mixture is rapidly cooled to room temperature using the water cooling system in the press. The mold is then depressurized, and the core material of the nano-insulation board is obtained. (SEM image of the core material is shown below.) Figure 2 As shown, with Figure 3 In comparison, it can be seen that the fiber diameter is significantly larger when composited with molten salt.

[0048] Core material encapsulation: Two layers of 0.15mm thick aluminum-plastic film are placed in a packaging machine, and the packaging temperature is controlled at 185℃. Three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed into the barrier bag for vacuum sealing. When the vacuum degree reaches 0.1Pa, vacuuming is continued for 6 minutes, followed by sealing to obtain the nano-insulation board. The finished product is as follows: Figure 1 As shown.

[0049] Example 2

[0050] A core material containing molten salt, prepared by the following method:

[0051] (1) Ingredients: First, the high-silica fiber is dispersed at 500 r / min for 5 min using a high-speed disperser; then ZnCl2 and AlCl3 are mixed in a molar ratio of 1:1 to form a molten salt additive; then, zirconia nanopowder, high-silica fiber, silicon carbide powder and molten salt additive are mixed in a mass ratio of 500:50:10:100 and mixed evenly using a mechanical fusion machine with a speed of 1000 r / min and a stirring time of 60 min to obtain a mixture.

[0052] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 0.5 MPa and a molding speed of 0.1 mm / s for compression molding. Then, it is heated and held under pressure at 120℃ and 0.5 MPa for 20 min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0053] Core material encapsulation: Two layers of 0.1mm thick aluminum-plastic film are placed in a packaging machine, the packaging temperature is controlled at 160℃, and the three sides are sealed to obtain a bagged barrier bag; the core material of the nano-insulation board is placed in the barrier bag for vacuum sealing. When the vacuum degree reaches 0.5Pa, the vacuum is continuously evacuated for 10 minutes, and then sealed to obtain the nano-insulation board.

[0054] Example 3

[0055] A core material containing molten salt, prepared by the following method:

[0056] (1) Batching: First, alumina fibers are dispersed at 1000 r / min for 1 min using a high-speed disperser; then ZnCl2 and AlCl3 are mixed in a molar ratio of 1:1 to form a molten salt additive; then, alumina nanopowder, alumina fibers, silicon carbide powder and molten salt additive are mixed in a mass ratio of 550:100:30:150 and mixed evenly using a mechanical fusion machine with a speed of 1500 r / min and a stirring time of 30 min to obtain a mixture.

[0057] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 5MPa and a molding speed of 50mm / s for compression molding. Then, it is heated and held under pressure at 120℃ and 5MPa for 10min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0058] Core material encapsulation: Two layers of 0.2mm thick aluminum-plastic film are placed in a packaging machine, the packaging temperature is controlled at 200℃, and the three sides are sealed to obtain a bagged barrier bag; the core material of the nano-insulation board is placed in the barrier bag for vacuum sealing. When the vacuum degree reaches 2Pa, the vacuum is continuously evacuated for 5 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0059] Example 4

[0060] The difference from Example 1 is that in step (1), ZnCl2 and AlCl3 are mixed in a molar ratio of 2:1 to form a molten salt additive, and in step (2), the heating temperature is 150°C.

[0061] A core material containing molten salt, prepared by the following method:

[0062] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, ZnCl2 and AlCl3 are mixed in a molar ratio of 2:1 to form a molten salt additive; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder and molten salt additive are mixed in a mass ratio of 600:200:50:200 and mixed evenly using a mechanical fusion machine with a rotation speed of 1200 r / min and a stirring time of 50 min to obtain a mixture.

[0063] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 3MPa and a molding speed of 5mm / s for compression molding. Then, it is heated and held under pressure at 150℃ and 3MPa for 20min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0064] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0065] Example 5

[0066] The difference from Example 1 is that in step (1), ZnCl2 and AlCl3 are mixed in a molar ratio of 0.5:1 to form a molten salt additive, and in step (2), the heating temperature is 150°C.

[0067] A core material containing molten salt, prepared by the following method:

[0068] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, ZnCl2 and AlCl3 are mixed in a molar ratio of 0.5:1 to form a molten salt additive; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder and molten salt additive are mixed in a mass ratio of 600:200:50:200 and mixed evenly using a mechanical fusion machine with a rotation speed of 1200 r / min and a stirring time of 50 min to obtain a mixture.

[0069] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 3MPa and a molding speed of 5mm / s for compression molding. Then, it is heated and held under pressure at 150℃ and 3MPa for 20min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0070] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0071] Example 6

[0072] The difference from Example 1 is that the heating temperature in step (2) is 300°C.

[0073] A core material containing molten salt, prepared by the following method:

[0074] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, ZnCl2 and AlCl3 are mixed in a molar ratio of 1:1 to form a molten salt additive; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder and molten salt additive are mixed in a mass ratio of 600:200:50:200 and mixed evenly using a mechanical fusion machine with a speed of 1200 r / min and a stirring time of 50 min to obtain a mixture.

[0075] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 3MPa and a molding speed of 5mm / s for compression molding. Then, it is heated and held under pressure at 300℃ and 3MPa for 20min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0076] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0077] Comparative Example 1

[0078] The difference from Example 1 is that no molten salt additive was added in step (1). The SEM image of the core material is shown below. Figure 3 As shown.

[0079] A core material, prepared by the following method:

[0080] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, the fumed silica nanopowder, quartz fiber and silicon carbide powder are mixed at a mass ratio of 600:200:50 and mixed evenly using a mechanical fusion machine with a speed of 1200 r / min and a stirring time of 50 min to obtain the mixture.

[0081] (2) Core Material Compression Molding: The mixture obtained in step (1) is spread into the compression mold using a scraper. The mixture is then compressed using a vacuum hot press at a pressure of 3 MPa and a molding speed of 5 mm / s. The pressure is maintained for 20 minutes, then the mold is depressurized and demolded to obtain the core material of the nano-insulation board. (SEM image of the core material is shown below.) Figure 3 As shown.

[0082] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0083] Comparative Example 2

[0084] The difference from Example 1 is that the molten salt additive in step (1) is ZnCl2.

[0085] A core material containing molten salt, prepared by the following method:

[0086] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder, and molten salt additive ZnCl2 are mixed at a mass ratio of 600:200:50:200 and mixed evenly using a mechanical fusion machine with a speed of 1200 r / min and a stirring time of 50 min to obtain the mixture.

[0087] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 3MPa and a molding speed of 5mm / s for compression molding. Then, it is heated and held under pressure at 130℃ and 3MPa for 20min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0088] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0089] Comparative Example 3

[0090] The difference from Example 1 is that the molten salt additive in step (1) is AlCl3.

[0091] A core material containing molten salt, prepared by the following method:

[0092] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder, and molten salt additive AlCl3 are mixed at a mass ratio of 600:200:50:200 and mixed evenly using a mechanical fusion machine with a speed of 1200 r / min and a stirring time of 50 min to obtain the mixture.

[0093] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 3MPa and a molding speed of 5mm / s for compression molding. Then, it is heated and held under pressure at 130℃ and 3MPa for 20min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0094] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0095] Comparative Example 4

[0096] The difference from Example 1 is that in step (1), ZnCl2 and AlCl3 are mixed in a molar ratio of 10:1 to form a molten salt additive.

[0097] A core material containing molten salt, prepared by the following method:

[0098] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, ZnCl2 and AlCl3 are mixed in a molar ratio of 10:1 to form a molten salt additive; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder and molten salt additive are mixed in a mass ratio of 600:200:50:200 and mixed evenly using a mechanical fusion machine with a rotation speed of 1200 r / min and a stirring time of 50 min to obtain a mixture.

[0099] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 3MPa and a molding speed of 5mm / s for compression molding. Then, it is heated and held under pressure at 130℃ and 3MPa for 20min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0100] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0101] Comparative Example 5

[0102] The difference from Example 1 is that in step (1), ZnCl2 and AlCl3 are mixed in a molar ratio of 0.1:1 to form a molten salt additive.

[0103] A core material containing molten salt, prepared by the following method:

[0104] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, ZnCl2 and AlCl3 are mixed in a molar ratio of 0.1:1 to form a molten salt additive; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder and molten salt additive are mixed in a mass ratio of 600:200:50:200 and mixed evenly using a mechanical fusion machine with a rotation speed of 1200 r / min and a stirring time of 50 min to obtain a mixture.

[0105] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 3MPa and a molding speed of 5mm / s for compression molding. Then, it is heated and held under pressure at 130℃ and 3MPa for 20min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0106] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0107] Comparative Example 6

[0108] The difference from Example 1 is that the heating temperature in step (2) is 100°C.

[0109] A core material containing molten salt, prepared by the following method:

[0110] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, ZnCl2 and AlCl3 are mixed in a molar ratio of 1:1 to form a molten salt additive; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder and molten salt additive are mixed in a mass ratio of 600:200:50:200 and mixed evenly using a mechanical fusion machine with a speed of 1200 r / min and a stirring time of 50 min to obtain a mixture.

[0111] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 3MPa and a molding speed of 5mm / s for compression molding. Then, it is heated and held under pressure at 100℃ and 3MPa for 20min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0112] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0113] Comparative Example 7

[0114] The difference from Example 1 is that the amount of molten salt additive used is 250 parts, which is outside the preferred range, i.e., the amount of molten salt additive is excessive.

[0115] A core material containing molten salt, prepared by the following method:

[0116] (1) Ingredients: First, the quartz fiber is dispersed at 800 r / min for 5 min using a high-speed disperser; then, ZnCl2 and AlCl3 are mixed in a molar ratio of 1:1 to form a molten salt additive; then, the fumed silica nanopowder, quartz fiber, silicon carbide powder and molten salt additive are mixed in a mass ratio of 600:200:50:250 and mixed evenly using a mechanical fusion machine with a rotation speed of 1200 r / min and a stirring time of 50 min to obtain a mixture.

[0117] (2) Core material compression molding: The mixture obtained in step (1) is laid in the compression mold using a scraper. The vacuum hot press is set to a pressure of 3MPa and a molding speed of 5mm / s for compression molding. Then, it is heated and held under pressure at 130℃ and 3MPa for 20min. After heating, the water cooling system in the press is used to quickly cool it to room temperature. Then, the mold is depressurized and the core material of the nano-insulation board is obtained.

[0118] Core material encapsulation: Two layers of aluminum-plastic film, each 0.15mm thick, are placed in an encapsulation machine. The encapsulation temperature is controlled at 185℃, and the three sides are sealed to obtain a bagged barrier bag. The core material of the nano-insulation board is placed in the barrier bag for vacuum encapsulation. When the vacuum degree reaches 0.1Pa, the vacuum is continuously evacuated for 6 minutes, and then the bag is sealed to obtain the nano-insulation board.

[0119] Performance testing

[0120] The performance of the nano-insulation panels prepared in the above embodiments and comparative examples was tested using the following methods:

[0121] (1) Thermal insulation performance: The thermal conductivity at room temperature was measured according to Method A in GB / T 39704-2020 "Determination of effective thermal conductivity of nano-insulation board".

[0122] (2) Mechanical properties: Referring to GB / T 1448-2005 "Test method for compression properties of fiber reinforced plastics", the strain of the nano-insulation board compared with the original thickness was tested at a compression rate of 2 mm / min and a pressure of 2 MPa.

[0123] (3) Powder shedding: Refer to Appendix B of GB / T 34336-2017 "Nano-insulating porous aerogel composite insulation products" for the test method of vibration mass loss rate.

[0124] The results are shown in the table below.

[0125]

[0126] As can be seen from the table above, compared with Comparative Example 1, the nano-insulation boards prepared in each embodiment of the present invention have lower thermal conductivity, strain value and vibration mass loss rate, indicating that the nano-insulation boards prepared by adding molten salt in the present invention have better thermal insulation performance, rigidity performance and stability (not easy to shed powder) than the prior art.

[0127] Compared to Example 1, Comparative Examples 2-3, using only one type of molten salt, required higher heating temperatures, and the thermal conductivity of the nano-insulation panels was higher than that of Example 1. According to... Figure 4 Data calculated by FactSage software shows that the melting temperature of the composite molten salt system composed of ZnCl2 and AlCl3 is lower than that of ZnCl2 or AlCl3 alone. This is because the molten salts in the binary system have different cations. The mixing of ZnCl2 and AlCl3 disrupts the ordered arrangement of the original molecules, making the binary system less stable, lowering the melting point, and adversely affecting its thermal properties.

[0128] Compared with Example 1, the molar ratio of ZnCl2 to AlCl3 in Comparative Examples 4-5 is not within the preferred range because the molar ratio of the two molten salts is different. Different ratios of anions and cations will produce different lattice arrangement sequences, resulting in a higher thermal conductivity of the nano-insulation board than in Example 1. Therefore, a better effect can only be achieved when the molar ratio of ZnCl2 to AlCl3 is within the preferred range.

[0129] Compared to Example 1, in Example 6, the heating temperature was increased to 300°C, and the thermal conductivity of the nano-insulation board remained at the same level as in Example 1. This indicates that increasing the temperature does not adversely affect the thermal conductivity of the insulation board, but high temperatures will generate a large amount of energy consumption. In Comparative Example 6, when the heating temperature was reduced to 100°C, the thermal conductivity of the nano-insulation board increased, while its rigidity and stability decreased. This is because the excessively low heating temperature did not allow the molten salt to melt, and the molten salt could not be uniformly dispersed in the insulation board.

[0130] Compared to Example 1, Comparative Example 7 had an excessive amount of molten salt additive, which increased the thermal conductivity of the nano-insulation board. This was because the excessive molten salt additive significantly reduced the porosity inside the insulation board, thus adversely affecting its insulation effect.

[0131] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A core material containing a molten salt, characterized by, The preparation method includes the following steps: (1) The heat insulation filler, reinforcing fiber, molten salt and additives are mixed evenly to obtain a mixture, wherein the molten salt is a mixture of zinc chloride and aluminum chloride; by mass parts, the heat insulation filler is 500-600 parts, the reinforcing fiber is 50-200 parts, the molten salt is 100-200 parts, and the additives are 10-50 parts; the molar ratio of zinc chloride and aluminum chloride is (0.5-2):1; (2) The mixture obtained in step (1) is pressed into shape, then heated to cause the molten salt to undergo a phase change and then cooled to obtain the nano-insulation board core material. The heating temperature is 120-300 ℃.

2. A core material containing a molten salt according to claim 1, characterized by The molar ratio of zinc chloride to aluminum chloride is 1:

1.

3. The molten salt-containing core material according to claim 1, wherein The heat-insulating filler is selected from one or more of fumed silica nanoparticles, zirconium oxide nanoparticles, and alumina nanoparticles; the reinforcing fiber is selected from one or more of quartz fiber, high-silica fiber, alumina fiber, mullite fiber, and aluminum silicate fiber; and the additive is silicon carbide powder.

4. A molten salt-containing core material according to claim 1, characterized by The reinforcing fibers are dispersed using a high-speed disperser at a stirring speed of 500-1000 r / min for 1-5 min.

5. A molten salt-containing core material according to claim 1, wherein The mixing method is mechanical fusion, specifically stirring at a speed of 1000-1500 r / min for 30-60 min.

6. A molten salt containing core material according to claim 1, wherein The pressing conditions are: molding speed 0.1-50 mm / s, pressure 0.5-5 MPa; the heating and pressure holding time is 10-20 min.

7. The application of the molten salt-containing core material according to any one of claims 1-6 in a nano-insulation panel, characterized in that, The core material prepared above is vacuum-sealed to obtain a nano-insulation board.

8. Use according to claim 7, characterized in that, The vacuum sealing is carried out in a barrier bag, which is made by placing two layers of barrier film into a sealing machine, controlling the sealing temperature at 160-200 ℃, and sealing three sides to obtain a bag-shaped barrier bag; the thickness of a single layer of barrier film is 0.1-0.2 mm. The vacuum sealing process uses a vacuum heat sealer with a vacuum level of 0.1-2 Pa; the vacuum is continuously pumped for 5-10 minutes. The thickness of the nano-insulation board is 2-80 mm.

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