A flexible nano-thermal insulation material, and a preparation method and application thereof

Abstract

The application provides a flexible nano thermal insulation material and a preparation method and application thereof. The preparation method of the flexible nano thermal insulation material comprises the following steps: mixing a low-thermal-conductivity powder, a fiberizable adhesive and optional additives, ball-milling to obtain flocculation, and rolling the flocculation into a film-shaped flexible nano thermal insulation material. The application utilizes the fibrils formed by the fiberizable adhesive to crosslink and fix the low-thermal-conductivity powder, and the flexible film is formed after rolling. Therefore, the pore structure of the low-thermal-conductivity powder itself is maintained without introducing the adhesive with high thermal conductivity for forming, so that the low thermal conductivity of the powder itself is retained while good processing formability is achieved. The flexible nano thermal insulation material prepared by the application has excellent flexibility, thermal insulation performance and certain tensile and compressive performance, and can be widely applied to the fields of aerospace, construction engineering, shipbuilding, automobile manufacturing and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal insulation materials, in particular to a flexible nano-thermal insulation material and a preparation method and application thereof. BACKGROUND

[0002] At present, for thermal insulation materials, nano-thermal insulation materials have the advantages of light weight, high temperature resistance, high porosity, and ultra-low thermal conductivity, etc. due to the pore size being smaller than the average free path of air molecules (≤70 nm), and are an ideal thermal insulation material, and are widely used in aerospace, national defense, chemical industry, metallurgy, electric power, transportation, etc.

[0003] Nano-thermal insulation materials can be divided into aerogel thermal insulation materials and nano-powder-based composite thermal insulation materials. Aerogel is a gel material with gas as the dispersion medium, which has ultra-light mass, low refractive index, low elastic modulus and ultra-low apparent thermal conductivity. However, the preparation of bulk aerogel has high cost, complex process, long preparation period, and the problem of high brittleness, which usually needs to be combined with fiber materials to enhance the mechanical properties. For example, Aspen Aerogels Inc. in the United States has published ceramic fiber felt composite silica aerogel composite materials in U.S. Patents 7078359B2, 6989132B2, 7399439B2, 7780890B2, 9181486B2, etc., with a room temperature thermal conductivity as low as 0.014 W / (m·K). Chinese Patent CN117303381B discloses a green preparation process of silica aerogel, and CN117779446A discloses a preparation method of a high-compressive-strength fireproof and thermal insulation aerogel gasket for power battery cells. However, the nano-aerogel composite thermal insulation material prepared has the disadvantages of dust falling off and high brittleness of the composite felt. In order to solve this problem, researchers use coating packaging to solve the problem, but this also increases the complexity and cost of the preparation process. For example, Ganyi City Fanyi Yihui Composite Material Co., Ltd. has developed a pre-oxidized aerogel felt packaged by coating, which solves the problems of dust falling off and brittleness of the felt. However, the pre-oxidized aerogel felt has insufficient temperature resistance and is not suitable for use in high-temperature environments. CN118308008A discloses a packaging coating for a fireproof and thermal insulation aerogel gasket for power battery cells and its application. The use of an alicyclic epoxy fireproof coating to package the aerogel thermal insulation gasket can make the ceramic fiber aerogel gasket have better low-temperature flexibility, prevent dust from falling off, and have sufficient flame retardancy and high-temperature resistance. However, the manufacturing process of high-quality silica aerogel composite materials requires the use of CO2 supercritical drying equipment, which requires a large fixed asset investment in manufacturing equipment and has high manufacturing costs.

[0004] While the nano-powder-based composite thermal insulation material is prepared by using nano-silica aerogel powder or fumed silica powder as the base material, adding reinforcing material, adhesive and other additives under dry conditions, and then uniformly mixing and pressing, the material obtained by pressing usually has high density and poor flexibility, which limits the actual application. Meanwhile, this kind of material needs further high-temperature sintering to eliminate the influence of the adhesive. For example, the Johns-Manville Company discloses in US Patent No. 2811457 that the high-efficiency thermal insulation material is obtained by using silica aerogel powder or fumed silica powder, metal zirconium powder, asbestos and phenolic resin as raw materials, uniformly mixing, and then sintering at 650 DEG C. The Johns-Manville Company has registered the material under the trademark of min-K. The US Atomic Energy Commission discloses in US Patent No. 3634563 the formula and process of the optimized min-K material, which uses fumed silica, rutile titanium dioxide or silicon carbide sunscreen, and short inorganic fibers as raw materials, mixes, adds ethyl acetate and octanoic acid, beats, volatilizes the solvent, and then presses to form, and further sintered at 900 DEG C to obtain lightweight porous nano thermal insulation material. CN118061611A and CN112140659A disclose a flexible nano thermal insulation felt and a preparation method thereof. The flexible nano thermal insulation felt obtained by a multi-layer sewing process has a core material containing hydrophilic fumed silica, micrometer-sized silicon carbide or titanium dioxide infrared sunscreen, and short glass fibers or ceramic fibers for toughening. However, this kind of material still has the problems of dust falling off and high brittleness of the board.

[0005] In order to solve the problems of the traditional nano thermal insulation material, such as poor mechanical properties, easy dust falling off and high preparation cost, a new method for preparing the nano thermal insulation material is needed, which is intrinsically flexible and has no dust falling off. The present application provides a method for preparing a flexible nano porous thermal insulation material based on a fiberizable adhesive to bond low thermal conductivity powder. The fiber network formed by the adhesive is used for powder forming, the overall preparation process is simple and easy to scale production, and the problems of poor mechanical properties and easy dust falling off of the traditional material are overcome. SUMMARY

[0006] The present application provides a flexible nano thermal insulation material and a preparation method and application thereof, which solves the defects of the prior art, such as easy dust falling off, poor mechanical properties or high preparation cost, and realizes the low-cost preparation of high-performance flexible nano thermal insulation material.

[0007] In a first aspect, the present application provides a preparation method of a flexible nano thermal insulation material, which comprises: mixing low thermal conductivity powder, fiberizable adhesive and optional additives, ball-milling to obtain flocculation, and then rolling the flocculation into a thin film of the flexible nano thermal insulation material.

[0008] This invention utilizes a fiber network formed during ball milling using a fibrous binder to bond stacked low thermal conductivity material powder, forming a flexible film under roller pressing. Since the main component of the flexible film is low thermal conductivity powder, the forming process does not damage the porous structure of the powder itself, thus maintaining the low thermal conductivity of the powder material. Simultaneously, the binder exists in the form of nanofibers, which do not clog the porous structure and therefore do not require sintering for removal. This preparation process requires no solvents, is simple, and the resulting product has strong plasticity, and the product does not suffer from problems such as easy dust shedding or insufficient mechanical properties.

[0009] Furthermore, the low thermal conductivity powder accounts for 85% to 95% of the mass, and the fibrous adhesive accounts for 1% to 10% of the mass. The flexible nano-insulation material of the present invention uses low thermal conductivity powder as the main component, and the amount of fibrous adhesive used is such that it can bond the low thermal conductivity powder together.

[0010] In this invention, the low thermal conductivity powder is selected from fumed silica powder, silica aerogel powder, alumina aerogel powder, zirconia aerogel powder, vermiculite powder, perlite powder, nano-carbon black, carbon aerogel powder, graphene oxide, carbon nanotubes, and C. 60 One or more of fullerenes.

[0011] In the above scheme, when the low thermal conductivity powder is a carbon-based material such as nano-carbon black, the resulting product is a carbon-based flexible nanoporous thermal insulation material. This material has broad application prospects in fields such as wave-absorbing heat insulation inside the nose cone of hypersonic weapons and ultra-high temperature thermal protection systems for advanced weapon systems.

[0012] In this invention, the fiber-forming adhesive is selected from one or more of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and hexafluoropropylene-tetrafluoroethylene copolymer. In some embodiments of this invention, the fiber-forming adhesive is selected from polytetrafluoroethylene.

[0013] To further improve the performance of flexible nanomaterials for thermal insulation, the formulation includes additives. These additives include one or more of infrared shading agents, reinforcing chopped inorganic fibers, or whiskers. The infrared shading agent accounts for 1% to 5% of the mass, and the reinforcing chopped inorganic fibers or whiskers also account for 1% to 5% of the mass. Adding the infrared shading agent suppresses high-temperature infrared radiation, thereby reducing the thermal conductivity, while adding the reinforcing chopped inorganic fibers or whiskers improves the dimensional stability of the material at high temperatures.

[0014] Specifically, the infrared shielding agent is selected from one or more of silicon carbide powder, rutile titanium dioxide, anatase titanium dioxide, boron carbide powder, zircon powder, zircon powder, etc.

[0015] Furthermore, when the flexible nano-insulating material is applied in high-temperature scenarios, the particle size of the infrared light-blocking agent has certain requirements. Specifically, it can be designed according to the following rules:

[0016] According to Wien's displacement law, the wavelength λ at which the energy density of infrared radiation emitted by a high-temperature blackbody or graybody heat source reaches its maximum is... * The temperature T of the heat source satisfies (λ) * / m)×(T / K)=b=0.002897. The particle size of the infrared shielding agent should be slightly larger than λ according to D50. * （T） The principle of selection is as follows. When the particle size of the infrared shielding agent is too small (e.g., <1μm), the infrared radiation from the heat source can directly penetrate the heat insulation layer, and it will not be able to shield the infrared heat radiation.

[0017] The reinforcing chopped inorganic fibers or whiskers are selected from one or more of chopped glass fibers, aluminum silicate fibers, brucite fibers, sepiolite fibers, and aluminum silicate whiskers.

[0018] In the preparation method of the present invention, the rotation speed and time of the ball milling step need to be adjusted according to the raw material ratio. The rotation speed must ensure that the fiberizable binder is fully sheared and stretched without being over-fiberized and unable to be further processed. Otherwise, the resulting product will have many through cracks in the thickness direction and poor heat insulation effect.

[0019] In some embodiments of the present invention, the ball mill operates at a speed of 300-500 rpm for 10-15 minutes. Further, the ball milling process uses 5mm diameter agate balls, with the balls and material added at a mass ratio of 5:1. The hopper is filled to 50%-70% capacity. After mixing at 300-500 rpm for 10-15 minutes, the powder is sieved through a 20-mesh sieve and collected.

[0020] In some embodiments of the present invention, the rolling process employs a multi-stage double-roller system, with the roller spacing of each stage decreasing according to a certain roller spacing d, where d ranges from 0.1 to 0.8 mm, preferably 0.5 mm. Each stage of double-rollers is symmetrically arranged along a centerline, and each stage of rollers has the same roller length and linear velocity. During the rolling process, multiple stages and multiple rolling passes are required to ensure that the fiberizable binder is fully sheared and stretched to form long, thin fibers, which bind the powder in the mixture. Simultaneously, pre-designed product parameters (such as density and thickness) must also be considered. In some embodiments, when the low thermal conductivity powder is selected as hydrophilic fumed silica powder, its surface is rich in hydroxyl groups, and the intermolecular hydrogen bonds further enhance the adhesion of the powder.

[0021] Secondly, the present invention provides a flexible nano-insulation material prepared by the above-described preparation method.

[0022] The flexible nano-insulation material provided by the present invention has a density of 150–400 mg / cm³. 3 The apparent thermal conductivity at room temperature is 20–50 mW / (m·K).

[0023] The flexible nano-insulation material provided by the present invention has a porous structure of the low thermal conductivity powder itself and a channel structure formed by the accumulation of solid raw material particles, with an average pore size of 16-20 nm.

[0024] Thirdly, the present invention provides the application of the above-mentioned flexible nano-insulation material in the fields of heat insulation and heat preservation.

[0025] Because the flexible nano-insulation material prepared by this invention has excellent flexibility, insulation properties and certain tensile and compressive properties, it can be used as a heat insulation and heat preservation material and is widely used in aerospace, construction engineering, shipbuilding, automobile manufacturing, industrial production and other fields.

[0026] Fourthly, the present invention also provides a flexible nano-insulation felt, the raw materials of which include low thermal conductivity powder, fiberizable binder, hydrated salt phase change material, low-temperature melting glass powder and optional additives.

[0027] Preferably, the additive includes one or more of the following: infrared shading agent, reinforcing short-cut inorganic fibers or whiskers, and carbonates.

[0028] More preferably, by mass percentage, the raw materials of the flexible nano-insulation felt include 60-65% low thermal conductivity powder, 1-10% fiberizable binder, 15-25% hydrated salt phase change material, 1-5% low-temperature melting glass powder, 1-5% infrared shading agent, 1-5% chopped inorganic fibers or whiskers for reinforcement, and 1-5% carbonate.

[0029] The hydrated salt phase change material can be selected from nano-magnesium hydroxide powder, nano-aluminum hydroxide powder, sepiolite fiber powder, brucite fiber powder, Na2B4O7·10H2O, Na2B4O7·5H2O, and aluminum tripolyphosphate (AlH2P3O). 10 One or more of the following: ·2H2O.

[0030] The low-temperature molten glass powder can be bismuth-based glass powder or high-alkali glass powder.

[0031] The purpose of designing the above components is to ensure that, in high-temperature applications, after the fiberizable binder in the flexible nano-insulation felt is completely decomposed, the glass powder or hydrated salt phase change material that melts at low temperatures can continue to play a bonding role at high temperatures. This allows the insulation felt to still have sufficient mechanical properties when the operating temperature is ≥500℃, and to become ceramic at even higher temperatures (≥800℃) to act as a flame barrier.

[0032] Furthermore, the carbonate is a carbonate powder that undergoes an endothermic chemical reaction at high temperatures and releases flame-retardant CO2 gas, such as nano-Li2CO3, Na2CO3, CaCO3, etc.

[0033] The selection range for low thermal conductivity powders, fiberizable binders, infrared shading agents, and short-cut inorganic fibers or whiskers for reinforcement is the same as described above.

[0034] The low thermal conductivity powder is selected from fumed silica powder, silica aerogel powder, alumina aerogel powder, zirconia aerogel powder, vermiculite powder, perlite powder, nano-carbon black, graphene oxide, carbon nanotubes, carbon aerogel powder, and C. 60 One or more of fullerenes.

[0035] The fiber-forming adhesive is selected from one or more of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and hexafluoropropylene-tetrafluoroethylene copolymer. In some embodiments of the present invention, the fiber-forming adhesive is selected from polytetrafluoroethylene.

[0036] The infrared shielding agent is selected from one or more of the following: silicon carbide powder, rutile titanium dioxide, anatase titanium dioxide, boron carbide powder, zircon powder, zircon powder, etc.

[0037] The reinforcing chopped inorganic fibers or whiskers are selected from one or more of chopped glass fibers, aluminum silicate fibers, brucite fibers, sepiolite fibers, and aluminum silicate whiskers.

[0038] The present invention also provides a method for preparing the above-mentioned flexible nano-insulation felt, comprising: mixing raw materials other than the fiberizable adhesive evenly, mixing the resulting material with the fiberizable adhesive and ball milling to obtain flocculent material, and then kneading the flocculent material and rolling it to obtain the flexible nano-insulation felt.

[0039] The mixing process utilizes a rubber internal mixer at 10-30 rpm for 5-10 minutes. The purpose of this mixing process is to bind loose, sheet-like materials into a cohesive mass.

[0040] Furthermore, the present invention can also be used to prepare multilayer nano-flexible thermal insulation felt.

[0041] Specifically, the flexible nano-insulation material or flexible nano-insulation felt of the present invention, infrared reflective screens (copper-plated polyimide film, gold-plated polyimide film, aluminum foil, stainless steel foil, etc.) and / or long fiber woven mesh fabric (quartz fiber mesh fabric, glass fiber mesh fabric, basalt fiber mesh fabric, ramie fiber mesh fabric, flax fiber mesh fabric, bamboo fiber mesh fabric, reed fiber mesh fabric, etc.) that provide mechanical reinforcement are alternately laid layer by layer. The outermost layer uses high-temperature resistant ceramic fiber fabric or high-temperature alloy fiber fabric, and high-temperature resistant ceramic fiber sewing thread is used for quilting. Finally, a heat control coating / fireproof coating and an anti-icing and anti-oil coating are sprayed on the outermost layer of the product to obtain a multi-layer nano-flexible insulation felt product.

[0042] These products have broad application prospects in fields such as satellite thermal protection, auxiliary power units for aerospace vehicles, flight or critical data recorders, thermal management of bleed air and de-icing pipelines, and detachable insulation sleeves for industrial equipment.

[0043] Fifthly, as an application of flexible nano-insulation materials, the present invention provides a fireproof and heat-insulating gasket between battery cells, using the aforementioned flexible nano-insulation material as the core material.

[0044] Specifically, using flexible nano-insulating materials as the core material, and vacuum hot-pressing encapsulation with PET or PI film, a fireproof and heat-insulating gasket between power / energy storage battery cells is obtained.

[0045] Typical gasket density is 0.33 ± 0.02 g / cm³. 3 For applications involving fireproof and heat-insulating gaskets for power batteries, the mainstream thickness requirements for fireproof and heat-insulating gaskets between power battery cells are 1mm and 2mm.

[0046] Sixthly, as an application of flexible nano-insulation material, the present invention provides an insulated pipe shell, which uses the above-mentioned flexible nano-insulation material as the interlayer between the inner tube and the outer tube.

[0047] Specifically, a multi-layer flexible nano-insulation material shell can be wound between two parallel steel pipes to manufacture insulated pipelines for offshore crude oil transportation.

[0048] Seventhly, as an application of flexible nano-insulation materials, the present invention provides a vacuum insulation panel using the aforementioned flexible nano-insulation material as the core material.

[0049] Specifically, the flexible nano-insulation material described above in this invention, combined with a getter and vacuum hot-pressing encapsulation process, can be used to obtain a vacuum insulation panel with a room temperature thermal conductivity as low as 0.004 W / (m·K), which has broad application prospects in ultra-thin energy-saving refrigerators, cold chain logistics vehicle panels, and outdoor communication and power cabinet insulation interlayers.

[0050] This invention provides a flexible nanomaterial for thermal insulation, its preparation method, and its applications. A flexible film is formed by cross-linking and fixing low thermal conductivity powder with fibrils created using a fiberizable binder and then rolling it. This maintains the porous structure of the low thermal conductivity powder itself without introducing a high thermal conductivity binder, thus preserving the powder's low thermal conductivity while maintaining good processability. The flexible nanomaterial for thermal insulation prepared by this invention possesses excellent flexibility, thermal insulation properties, and certain tensile and compressive properties, and can be widely used in aerospace, construction engineering, shipbuilding, and automobile manufacturing. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the multi-stage double-roller system of the roller press used in the preparation process of this embodiment of the invention.

[0052] Figure 2 This is a microstructure diagram of the flexible nano-insulation material provided in Embodiment 2 of the present invention.

[0053] Figure 3 The results are from the hot-table test in Embodiment 6 of the present invention. The front temperature was 1100°C and the sample thickness was 30 mm.

[0054] Figure 4 This is a microstructure diagram of the material provided in Comparative Example 1 of the present invention.

[0055] Figure 5 This is a microstructure diagram of the material provided in Comparative Example 2 of the present invention.

[0056] Figure 6 This is a microstructure diagram of the material provided in Comparative Example 4 of the present invention.

[0057] Figure 7 These are the hot-stage test results of Embodiment 4 and Comparative Example 6 of the present invention. The sample size is 100mm×100mm×2mm.

[0058] Figure 8 The results are the apparent thermal conductivity measurements of the flexible nano-insulation materials provided in different embodiments. The standard for testing apparent thermal conductivity at room temperature is GB / T 10295-2008, and the standard for testing thermal conductivity at high temperature is GJB 10252-2021. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0060] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0061] In the following examples, the PTFE used is Chemours 601X polytetrafluoroethylene manufactured by DuPont.

[0062] The silicon carbide powder used was produced by Beijing Micro-Nano Ultrafine Materials Co., Ltd., type W-3.5, α phase, D50=3.5μm.

[0063] The fumed silica powder used was Wacker N20, with a specific surface area of ​​200 m². 2 / g, hydrophilic.

[0064] The short-cut glass fibers used are 4-6 mm in length and 5-7 μm in diameter, produced by China Jushi.

[0065] The high-shear mixer used was Cyclomix®, manufactured by Hosokawa Micron Co., Ltd. of Japan.

[0066] The ball mill used was the WGM-500L model manufactured by Wuxi Xinyang Equipment Technology Co., Ltd.

[0067] The roller press used in the following embodiments is a multi-stage double-roller system. The roller spacing of each stage decreases by 0.5mm. The double rolls of each stage are symmetrically arranged along a center line. Each stage of the rollers has the same roller length and linear velocity. Its structural schematic diagram is shown below. Figure 1 As shown.

[0068] Example 1

[0069] This embodiment provides a flexible nano-thermal insulation material, the preparation method of which is as follows:

[0070] Silica aerogel powder with a mass ratio of 95:5 was mixed with PTFE, ball-milled at 300 rpm for 8 minutes, and then the flocculent mixture was extruded in a roller press to obtain a density of 200 mg / cm³. 3 The thin film material has an apparent thermal conductivity of 18 mW / (m·K) at room temperature.

[0071] Example 2

[0072] This embodiment provides a flexible nano-thermal insulation material, the preparation method of which is as follows:

[0073] Fumed silica powder with a mass ratio of 95:5 was mixed with PTFE, ball-milled at 300 rpm for 8 minutes, and then the flocculent mixture was extruded in a roller press to obtain a density of 350 mg / cm³. 3The thin film material has an apparent thermal conductivity of 20 mW / (m·K) at room temperature.

[0074] Figure 2 This is a microstructure diagram of the flexible nano-insulation material provided in Example 2.

[0075] Example 3

[0076] This embodiment provides a flexible nano-thermal insulation material, the preparation method of which is as follows:

[0077] Fumed silica powder, silicon carbide powder, and PTFE were mixed in a mass ratio of 90:5:5. After ball milling at 300 rpm for 8 minutes, the flocculent mixture was extruded in a roller press to obtain a density of 350 mg / cm³. 3 The thin film material has an apparent thermal conductivity of 20 mW / (m·K) at room temperature.

[0078] Example 4

[0079] This embodiment provides a flexible nano-thermal insulation material, the preparation method of which is as follows:

[0080] Fumed silica powder, titanium dioxide powder (particle size greater than 1 μm), and PTFE were mixed in a mass ratio of 90:5:5. After ball milling at 300 rpm for 8 minutes, the flocculent mixture was extruded in a roller press to obtain a density of 350 mg / cm³. 3 The thin film material has an apparent thermal conductivity of 22 mW / (m·K) at room temperature.

[0081] Example 5

[0082] This embodiment provides a flexible nano-thermal insulation material, the preparation method of which is as follows:

[0083] Fumed silica powder, chopped glass fiber, silicon carbide powder, and PTFE were mixed in a mass ratio of 89:3:3:5. The fumed silica powder, chopped glass fiber, and silicon carbide powder were placed in the hopper of a high-shear mixer and stirred at 800 rpm for 30 minutes to ensure thorough mixing. Then, PTFE was added and ball-milled at 300 rpm for 10 minutes. The resulting flocculent mixture was extruded in a roller press to obtain a density of 350 mg / cm³. 3 The thin film material has an apparent thermal conductivity of 20 mW / (m·K) at room temperature.

[0084] Example 6

[0085] This embodiment provides a flexible nano-insulation felt, the formulation of which is as follows:

[0086] Fumed silica powder (62%); chopped glass fiber (3%); sepiolite fiber powder (5%); brucite fiber powder (5%); lithium carbonate (5%); borax decahydrate (5%); aluminum tripolyphosphate (5%); Beijing Tianlichuang Glass Technology Co., Ltd. SE-925 bismuth-containing glass powder (1%); Beijing Tianlichuang Glass Technology Co., Ltd. SE905 high-alkali glass powder (1%); silicon carbide powder (3%); PTFE (5%).

[0087] Its preparation method is as follows:

[0088] First, all materials except PTFE are placed in the hopper of a high-shear mixer and stirred at 800 rpm for 30 minutes to ensure thorough mixing. Then, the resulting material is ball-milled with PTFE at 300 rpm for 10 minutes to form a flocculent mixture. This mixture is then placed in a rubber internal mixer and kneaded at 20 rpm for 5 minutes to obtain a second, agglomerated mixture. Under the action of multi-stage roller pressing, a density of 300 mg / cm³ is formed. 3 Thin film materials.

[0089] The flexible nano-insulation felt prepared in this embodiment exhibits a distinct isothermal plateau between 100 and 150°C in the hot-table insulation performance test. Figure 3 As shown, this is a typical characteristic of hydrated salt phase change materials losing their water of crystallization.

[0090] Example 7

[0091] This embodiment provides a carbon-based flexible nano-insulation felt, the formulation of which is as follows:

[0092] Nano carbon black (89%), Jiangxi Black Cat Carbon Black Co., Ltd., HMQ-C10; chopped carbon fiber (3%), chopped length 4~6mm, Zhongfu Shenying SYT50S, the carbon fiber is subjected to surface slurry removal according to the method published in Chinese Invention Patent Application No. 202410776310.6; silicon carbide powder (3%); PTFE (5%).

[0093] Its preparation method is as follows:

[0094] First, all materials except PTFE are placed in the hopper of a high-shear mixer and stirred at 800 rpm for 30 minutes to ensure thorough mixing. Then, the resulting material is ball-milled with PTFE at 300 rpm for 10 minutes to form a flocculent mixture. This mixture is then placed in a rubber internal mixer and kneaded at 20 rpm for 5 minutes to obtain a second, agglomerated mixture. Under the action of multi-stage roller pressing, a density of 300 mg / cm³ is formed. 3 This is a thin film material. It possesses excellent flexibility, thermal insulation properties, and electromagnetic wave absorption capabilities.

[0095] Example 8

[0096] This embodiment provides a flexible nano-insulation felt, the formulation of which is as follows:

[0097] Fumed aluminum oxide powder (65%); sepiolite fiber powder (5%); brucite fiber powder (5%); lithium carbonate (5%); borax decahydrate (5%); aluminum tripolyphosphate (5%); Beijing Tianlichuang Glass Technology Co., Ltd. SE-925 bismuth-containing glass powder (1%); Beijing Tianlichuang Glass Technology Co., Ltd. SE-905 high-alkali glass powder (1%); silicon carbide powder (3%); PTFE (5%).

[0098] Its preparation method is as follows:

[0099] First, all materials except the PTFE binder are placed in the hopper of a high-shear mixer and stirred at 800 rpm for 30 minutes to ensure thorough mixing. Then, the first mixture is combined with PTFE and ball-milled at 300 rpm for 10 minutes to form a flocculent mixture. This mixture is then placed in a rubber internal mixer and kneaded at 20 rpm for 5 minutes to obtain a granulated second mixture. Under the action of multi-stage roller pressing, a density of 300 mg / cm³ is formed. 3 Thin film materials.

[0100] Comparative Example 1

[0101] This comparative example provides a porous thin film material, which differs from Example 2 in that the ball milling time is extended to 15 minutes.

[0102] As a result, due to excessively long ball milling time, the obtained product had many through-cracks in the thickness direction, such as... Figure 4 As shown, the product has poor heat insulation performance, with an apparent thermal conductivity of 57 mW / (m·K) at room temperature.

[0103] Comparative Example 2

[0104] This comparative example provides a porous thin film material, which differs from Example 2 in that the ball milling speed is increased to 800 rpm.

[0105] As a result, due to the excessively high ball milling speed, the obtained product had many through-cracks in the thickness direction, such as... Figure 5 As shown, the product has poor heat insulation performance, with an apparent thermal conductivity of 53 mW / (m·K) at room temperature.

[0106] Comparative Example 3

[0107] This comparative example provides a porous thin film material, which differs from Example 2 in that the inter-stage roller gap feed in the multi-stage rolling system is 1 mm / stage.

[0108] As a result, due to the excessive feed amount of the inter-stage roller gap, a large number of through cracks appeared in the thickness direction of the product, and the product was scrap.

[0109] Comparative Example 4

[0110] This comparative example provides a porous thin film material, which differs from Example 1 in that the PTFE content is increased to 15%, that is, fumed silica powder with a mass ratio of 85:15 is mixed with PTFE, and the subsequent steps are the same as in Example 1.

[0111] As a result, due to the excessive PTFE content, some PTFE cannot be completely drawn into fibers under shear force, and instead agglomerates into lumps that block the pore structure, such as... Figure 6 As shown, the obtained product has poor heat insulation performance, with an apparent thermal conductivity of 61 mW / (m·K) at room temperature.

[0112] Comparative Example 5

[0113] This comparative example provides a porous thin film material, which differs from Example 3 in that the content of the infrared shading agent SiC is increased to 10%, that is, fumed silica powder, silicon carbide powder and PTFE are mixed in a mass ratio of 85:10:5, and the subsequent steps are the same as in Example 3.

[0114] As a result, the thermal insulation performance of the product decreased because the apparent density of the product increased, and the solid phase thermal conductivity increased significantly.

[0115] Comparative Example 6

[0116] This comparative example provides a porous thin film material, which differs from Example 4 in that the light-blocking agent used is nano-TiO2 powder with a particle size of 300 nm.

[0117] As a result, the obtained product had no light-blocking effect. Hot-stage testing showed that when one side was heated to 600℃, the temperature on the back of the product reached 330℃, significantly higher than the sample made from micron-sized TiO2 powder. Figure 7 As shown.

[0118] Comparative Example 7

[0119] In Example 3, when the light-blocking agent is SiC with D50=30μm, the heat insulation performance decreases. This is because, compared to SiC with D50=3.5μm, when the addition amount is only 5% by mass, the large-particle light-blocking agent cannot completely cover the entire plane, resulting in light leakage areas. If the amount of SiC is increased, the solid-phase heat conduction will increase significantly.

[0120] Table 1 shows the thermal conductivity of various insulation materials, in W / (m·K). The test standard for room temperature thermal conductivity is GB / T 10295-2008, and the test standard for high temperature thermal conductivity is GJB 10252-2021. Figure 8 Table 1 shows the apparent thermal conductivity of different insulation materials.

[0121] Table 1

[0122]

[0123] Application Example 1: Preparation of VIP Board

[0124] The film obtained in Example 6 was placed in a VIP packaging bag, along with a getter pack. The vacuum device was then turned on and vacuumed continuously for 72 hours. After that, the vacuum needle was removed, and the film was hot-pressed at 110°C to obtain a VIP board with an apparent thermal conductivity of 4 mW / (m·K) at room temperature.

[0125] Application Example 2: Sewing Multi-Layer Insulation Felt

[0126] To prepare a multi-layer flexible nano-insulation felt, the flexible nano-insulation material of this invention, an infrared reflective screen (copper-plated polyimide film, gold-plated polyimide film, aluminum foil, stainless steel foil, etc.), and a quartz fiber mesh cloth that provides mechanical reinforcement are alternately laid layer by layer. The outermost layer uses high-temperature resistant alumina ceramic fiber fabric or high-temperature alloy fiber fabric, and high-temperature resistant ceramic fiber sewing thread is used for quilting. Finally, a heat control coating is sprayed on the outermost layer of the product to obtain a multi-layer flexible nano-insulation felt product.

[0127] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0128] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "detailed implementation," or "some specific implementations," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a flexible nano-insulating material, characterized in that, include: Low thermal conductivity powder, fiberizable binder, and additives are mixed, ball-milled to obtain flocculent material, and then the flocculent material is rolled into a thin film with a density of 150–400 mg / cm³. 3 The flexible nano-insulating material; the low thermal conductivity powder is selected from fumed silica powder and / or silica aerogel powder; the additives include infrared light-blocking agents; The low thermal conductivity powder accounts for 85% to 95% of the mass, the fiberizable binder accounts for 1% to 10% of the mass, the infrared shading agent accounts for 1% to 5% of the mass, the ball milling speed is 300 to 500 rpm, and the time is 10 to 15 minutes; the rolling process adopts a multi-stage double-roller system, the roller spacing of each stage of the roller decreases in the range of 0.1-0.8 mm, the double rollers of each stage are symmetrically arranged along a center line, and each stage of the rollers has the same roller length and linear speed.

2. The method for preparing the flexible nano-insulation material according to claim 1, characterized in that, The low thermal conductivity powder also includes alumina aerogel powder, zirconia aerogel powder, vermiculite powder, perlite powder, nano-carbon black, carbon aerogel powder, graphene oxide, carbon nanotubes, and C. 60 One or more of fullerenes; The fiber-forming adhesive is selected from one or more of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and hexafluoropropylene-tetrafluoroethylene copolymer.

3. The method for preparing the flexible nano-insulation material according to claim 1, characterized in that, The additive also includes one or two of the following: chopped inorganic fibers or whiskers for reinforcement, wherein the mass percentage of the chopped inorganic fibers or whiskers for reinforcement is 1% to 5%.

4. A flexible nano-insulation material, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.

5. The flexible nano-insulation material according to claim 4, characterized in that, The apparent thermal conductivity at room temperature is 20–50 mW / (m·K).

6. The flexible nano-insulation material according to claim 4, characterized in that, The flexible nano-insulation material has a porous structure of the low thermal conductivity powder itself and a channel structure formed by the accumulation of solid raw material particles, with an average pore size of 16-20 nm.

7. The application of the flexible nano-insulation material according to any one of claims 4-6 in the field of thermal insulation and heat preservation.

8. A flexible nano-insulation felt, characterized in that, The raw materials are low thermal conductivity powder, fiberizable binder, hydrated salt phase change material, low-temperature melting glass powder, infrared shielding agent, short-cut inorganic fibers or whiskers for reinforcement, and carbonates; the low thermal conductivity powder is selected from fumed silica powder and / or silica aerogel powder. The preparation method of the flexible nano-insulation felt includes: mixing raw materials other than the fiberizable adhesive evenly, mixing the resulting material with the fiberizable adhesive and ball milling to obtain flocculent material, and then kneading the flocculent material and rolling it to obtain the flexible nano-insulation felt. By weight percentage, the raw materials of the flexible nano-insulation felt are 60-65% low thermal conductivity powder, 1-10% fiberizable binder, 15-25% hydrated salt phase change material, 1-5% low-temperature melting glass powder, 1-5% infrared shading agent, 1-5% short-cut inorganic fibers or whiskers for reinforcement, and 1-5% carbonate.

9. A fireproof and heat-insulating gasket between battery cells, characterized in that, The flexible nano-insulation material described in any one of claims 4-6 is used as the core material.

10. A heat-insulating pipe shell, characterized in that, The flexible nano-insulation material described in any one of claims 4-6 is used as a sandwich layer placed between the inner tube and the outer tube.

11. A vacuum insulation panel, characterized in that, The flexible nano-insulation material described in any one of claims 4-6 is used as the core material.

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