Flexible composite multilayer high-temperature-resistant thermal insulation material and preparation method thereof

Abstract

This invention relates to a flexible composite multilayer thermal insulation material and its preparation method, belonging to the field of functional composite materials technology. The flexible composite multilayer thermal insulation material prepared by this invention includes an ablation-resistant layer and a thermal insulation layer at both ends, and an internal thermal expansion layer. The ablation-resistant layer is a high-temperature resistant fiber fabric. The thermal expansion layer is prepared by uniformly mixing protein, thermally expandable graphite material, and deionized water, and then extruding the protein fibers using a one-step method. The high-temperature resistant fibers are wound around the surface of the protein fibers to form a core-sheath composite yarn. The yarn foams and expands when heated, increasing the overall structural density. The honeycomb structure inside the yarn has good mechanical properties. The thermal insulation layer is a fiber-reinforced aerogel material, forming a heat-resistant and thermally insulating organic whole with more reliable mechanical stability and safety, while also possessing excellent heat resistance, thermal insulation, and load-bearing capacity.

Description

Technical Field

[0001] This invention relates to the field of functional composite materials technology, and in particular to a flexible composite multilayer thermal insulation material and its preparation method. Background Technology

[0002] High-performance fiber fabrics are among the textile composite materials that have attracted much attention in recent years. Due to their advantages such as good temperature resistance, high strength, high modulus, good impact resistance, and strong design flexibility, they are widely used in aerospace, military, automotive, and construction fields. Currently, new aerospace vehicles, represented by flexible thermal protection layers on the leeward side of aerospace vehicles and flexible thermal protection systems for variable-configuration spacecraft, have created an urgent need for flexible integrated thermal protection materials and structures.

[0003] For high-temperature resistant insulation materials, the thickness should be no less than 10mm. However, single-layer fabrics rarely achieve this thickness. Currently, traditional methods often use fabric layering to increase the overall thickness, with layers connected by stitching. However, this method damages the original structure during connection, thus affecting insulation performance. Chinese patent CN202210610438.6 uses a coating method, applying aerogel to a flexible fiber membrane and allowing it to stand for a period of time to obtain a fiber composite gel membrane. This membrane has some insulation effect, but its strength is low during use, making it prone to breakage. Chinese patent CN202210248870.5 involves sewing continuous ceramic fiber yarn through the insulation fabric using high-toughness sewing thread, bending and stretching the high-toughness thread, and knotting the fiber yarn at both ends to connect the layers. However, the sewing thread and ceramic fiber thread have different energy efficiency, damaging the original insulation structure and reducing the insulation effect. Chinese patent CN20182207615.5 describes a panel with an inner panel covered with a heat-insulating non-woven fabric and aramid woven fabric. This provides good heat insulation, and the panel's wavy structure reduces heat convection. Through layered insulation, a heat-insulating effect is achieved. However, using aramid alone may cause the internal heat-insulating non-woven fabric to overheat, preventing heat transfer to higher points and potentially leading to melting and deformation, thus affecting the overall performance. Chinese patent CN202211528394.9 describes a composite material with ablation-resistant and heat-insulating sections at both ends and a transition section in the middle. It is composed of a composite phosphate matrix combined with quartz fiber braid and low-density carbon fiber braid. This composite material has a gradient density structure, forming a heat-resistant and heat-insulating organic whole. However, the composite phosphate matrix is ​​pressure-impregnated with the fibers, resulting in uneven distribution and making impregnation and curing difficult to control.

[0004] Therefore, it is necessary to design an improved flexible composite multilayer thermal insulation material to solve the above problems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a flexible composite multilayer thermal insulation material and its preparation method. A schematic diagram of the structure of the flexible composite multilayer thermal insulation material provided by this invention is shown below. Figure 1 As shown.

[0006] The material of this invention is first woven using textile equipment, employing shallow cross-linking, shallow cross-linking, corner interlocking, or through-corner interlocking structures. The woven body uses 200tex-450tex yarns with heat-insulating properties, consisting of one or more of quartz fiber, alumina fiber, and silicon carbide fiber, which are combined with protein fibers to form a core-sheath composite structure yarn. After composite weaving, and then hot-rolled and set, an ablation-resistant layer and a heat-expanding layer are obtained. A water-based SiO2 sol, TiO2 sol, and ammonia are mixed at a volume ratio of 1:0.1:0.008 and stirred at room temperature (20°C) for 3 minutes to obtain a water-based SiO2-TiO2 sol. The prepared water-based SiO2-TiO2 sol was frozen in a Dewar flask with liquid nitrogen, and then pulverized using a high-speed multi-functional pulverizer to obtain a fine, ice-like freeze gel. This gel was then transferred to a freeze dryer for drying, yielding aerogel powder. Solvents and surfactants were added, and the mixture was stirred to completely wet the fragments, creating an aerogel slurry. A thermoplastic polymer was mixed with the aerogel slurry, and after plasma treatment, it was processed into needle-punched nonwoven fabric. Finally, through hot pressing and lamination with a thermally expanded layer, a flexible, multi-layered, high-temperature resistant thermal insulation material was formed.

[0007] This invention overcomes the problems of damage to the braided structure during the stitching process of multi-layer insulation in the prior art, as well as the problem of interlayer separation during use.

[0008] This invention is achieved through the following technical solution:

[0009] The first objective of this invention is to provide a method for preparing a flexible composite multilayer thermal insulation material, comprising the following steps:

[0010] S1. High-temperature resistant fibers are wound around the surface of keratin fibers to form a core-sheath composite yarn.

[0011] S2. The heat insulation yarn is woven with the core-sheath composite structure yarn obtained in step S1 to obtain an ablation-resistant layer and a thermal expansion layer.

[0012] S3. The thermoplastic polymer is mixed with aerogel slurry and then plasma treated to prepare a nonwoven fabric layer.

[0013] S4. The thermally expanded layer obtained in step S2 and the non-woven fabric layer obtained in step S3 are hot-pressed to obtain a flexible composite multilayer thermal insulation material.

[0014] In one embodiment of the present invention, in step S1, the keratin fibers are prepared by the following method:

[0015] Keratin is mixed and ground with expandable graphite. Dispersant, additives and water are added and the grinding continues until the surface is fluid. The mixture is stirred to obtain a mixed slurry. The mixed slurry is then spun into keratin fibers by a one-step extrusion method.

[0016] In one embodiment of the present invention, the stirring is first carried out at a speed of 200 rpm to 300 rpm for 0.5 h to 1 h, and then stirred at a speed of 300 rpm to 500 rpm for 1.5 h to 2 h.

[0017] In one embodiment of the present invention, the mass ratio of the dispersant to keratin is 1 to 3:100; the mass ratio of the additive to keratin is 0.001 to 0.005:1.

[0018] In one embodiment of the present invention, in step S1, the ratio of the number of high-temperature resistant fibers to the number of keratin fibers is 8:1 to 2:1.

[0019] In one embodiment of the present invention, the dispersant is a 1% (w / w) aqueous solution of polyvinyl alcohol; the additive is a 1M hydrochloric acid solution.

[0020] In one embodiment of the present invention, in step S1, the high-temperature resistant fiber is selected from one or more of quartz fiber, alumina fiber and silicon carbide fiber.

[0021] In one embodiment of the present invention, in step S2, the heat-insulating yarn is selected from one or more of quartz fiber, alumina fiber, and silicon carbide fiber; the weaving method is one or more of shallow cross-linking, shallow cross-linking, corner interlocking, and through-corner interlocking.

[0022] In one embodiment of the present invention, in step S3, the thermoplastic polymer is polyester and / or polyamide.

[0023] In one embodiment of the present invention, in step S3, the aerogel slurry is prepared by the following method:

[0024] (1) Mix water-based SiO2 sol, TiO2 sol and catalyst to obtain water-based SiO2-TiO2 sol;

[0025] (2) Freeze the water-based SiO2-TiO2 sol obtained in step (1) to obtain a freeze gel, pulverize and dry it to obtain aerogel powder;

[0026] (3) The aerogel powder obtained in step (2) is mixed with ethanol and cationic surfactant to obtain the aerogel slurry.

[0027] In one embodiment of the present invention, in step (1), the solid content of the water-based SiO2 sol is 2wt% to 35wt%, and the particle size is 2nm to 20nm; the solid content of the TiO2 sol is 5wt% to 22wt%, and the particle size is 3nm to 25nm.

[0028] In one embodiment of the present invention, in step (1), the catalyst is selected from ammonia water; the molar concentration of the catalyst is 0.05 mol / L to 0.35 mol / L.

[0029] In one embodiment of the present invention, in step (2), the pulverization conditions are: the rotation speed of the pulverizer is 500 r / min to 2000 r / min, the pulverization time is 30 min to 90 min, and the diameter of the pulverized aerogel particles is 10 μm to 800 μm.

[0030] In one embodiment of the present invention, in step (3), the cationic surfactant is selected from dialkyl hydroxyethyl methyl sulfate ammonium and / or hexadecyltrimethyl ammonium bromide.

[0031] In one embodiment of the present invention, in step S4, the hot pressing conditions are: temperature of 150℃~230℃, pressure of 5MPa~15MPa, and time of 20min~3h.

[0032] The second objective of this invention is to provide a flexible composite multilayer thermal insulation material prepared by the aforementioned preparation method, wherein the flexible composite multilayer thermal insulation material comprises, from top to bottom, an ablation-resistant layer, a thermal expansion layer, and a thermal insulation layer.

[0033] In one embodiment of the present invention, in step S1, the core-sheath composite yarn is prepared by the following method:

[0034] 1) Grind keratin and expandable graphite to below 800 mesh, add dispersant and additives, add deionized water and continue grinding until flow is observed on the surface;

[0035] 2) Add to a mixing pot and stir at low speed for 0.5h to 1h, then at high speed for 1.5h to 2h. The low speed is 200 rpm and the high speed is 500 rpm to obtain a mixed slurry.

[0036] 3) The mixed slurry is spun into keratin fibers by one-step extrusion, and multiple strands of high-temperature resistant fibers are wound around the surface of the protein fibers to form a core-sheath composite yarn.

[0037] Compared to uncrushed aerogel, this invention reduces the porosity of the aerogel itself and results in a more uniform distribution on the surface of the woven fabric after crushing, increasing the effective contact area with the woven fabric and making fuller use of the effective insulating portion of the aerogel. Adding a cationic surfactant during the preparation of the aerogel solution modifies the aerogel, introducing siloxane bonds and causing a condensation reaction to form silicon-oxygen-silicon bonds. This results in good bonding strength, and the uniform mixing of the crushed aerogel with the thermoplastic polymer reduces the voids between the aerogel particles.

[0038] The technical solution of the present invention has the following advantages compared with the prior art:

[0039] 1. The flexible composite multilayer thermal insulation material provided by this invention achieves multilayer connection through hot pressing, ensuring both strong connection and no impact on the functionality of the structural units. The aerogel thermal insulation composite material has low density and high compressive strength, while the quartz fiber exhibits extremely low linear ablation rate in thermal environments, possessing excellent thermal insulation properties and mechanical properties. The use of foaming materials to thicken the intermediate transition layer yarns and increase the overall structural density further enhances the insulation performance. The yarns have a special multi-pore structure, allowing for a large amount of air storage within the yarns.

[0040] 2. This invention arranges the outermost high-temperature resistant weft yarns of the functional layer of the braided body alternately and interweaves them through high-temperature resistant warp yarns. The weft yarns in the heat-insulating braided body that is resistant to high-temperature erosion adopt a multi-layer structure, which can adjust the number of layers of weft yarns in the middle layer according to different usage environments. The connection method can be used to adapt to different thicknesses, thereby adapting to different usage environments. It fully utilizes the high-temperature resistance of the high-temperature layer material and the high-efficiency heat insulation performance of the low-temperature layer aerogel material, and easily obtains a composite heat insulation material with the best heat insulation performance.

[0041] 3. The multi-layer design satisfies functions such as ablation resistance, load-bearing capacity, and thermal insulation, enabling the back of the material to have low thermal conductivity, improving thermal insulation performance, enhancing fiber-structure compatibility, and ensuring good mechanical strength and abrasion resistance. While further ensuring good thermal insulation performance, this design not only provides excellent assemblability for thermal protection but also allows for dynamic adjustment based on the spatial structure of the surface.

[0042] 4. Suspending both components in a dispersant system prevents graphite agglomeration and improves component uniformity. During heating, protein denaturation occurs, and in-situ polymerization of organic monomers promotes slurry solidification, giving the ligands a certain strength. Attached Figure Description

[0043] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0044] Figure 1 This is a flowchart of the flexible composite multilayer high-temperature resistant thermal insulation material in this invention;

[0045] Figure 2 This is a front view of high-temperature insulating fiber wrapped around the surface of protein fiber in Embodiment 1 of the present invention;

[0046] Figure 3 This is a side view of high-temperature insulating fiber wrapped around the surface of protein fiber in Embodiment 1 of the present invention;

[0047] Figure 4 This is a schematic diagram of the structure of the braided layer (11) in the flexible composite multilayer high-temperature resistant insulation material in Embodiment 1 of the present invention. Detailed Implementation

[0048] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0049] Example 1

[0050] This embodiment provides a method for preparing a flexible composite multilayer thermal insulation material, including the following steps:

[0051] (1) Grind keratin and expandable graphite to below 800 mesh, add dispersant (1% polyvinyl alcohol aqueous solution) and additive (1M hydrochloric acid solution), add deionized water and continue grinding until surface flow is observed, add to a mixing pot, stir at low speed for 1 hour and then at high speed for 2 hours to obtain a mixed slurry; the speed of low speed stirring is 200 rpm and the speed of high speed stirring is 500 rpm; the mass ratio of dispersant to keratin is 3:100; the mass ratio of additive to keratin is 0.005:1.

[0052] The mixed slurry is spun into keratin fibers using a one-step extrusion process, and then six quartz fibers are wound around the surface of the keratin fibers to form a core-sheath composite yarn, such as... Figure 2 and Figure 3 As shown; a four-layer shallowly cross-linked quartz fiber fabric is obtained by weaving quartz fiber and core-sheath composite yarn (e.g. Figure 4 As shown in the figure, the fibers are then hot-rolled and shaped to obtain an ablation-resistant layer (3 layers of quartz fiber) and a thermal expansion layer (1 layer of core-sheath composite yarn). The ablation-resistant layer is woven from heat-insulating yarn, and the thermal expansion layer is woven from core-sheath composite yarn.

[0053] (2) Commercially available water-based SiO2 sol, TiO2 sol, and ammonia were mixed in a volume ratio of 1:0.1:0.008 and stirred at room temperature (25℃) for 3 min to obtain water-based SiO2-TiO2 sol. The water-based SiO2 sol had a solid content of 5 wt% and an average particle size of 6 nm; the TiO2 sol had a solid content of 10 wt% and an average particle size of 5 nm; and the catalyst ammonia had a molar concentration of 0.05 mol / L.

[0054] The prepared water-based SiO2-TiO2 sol was frozen in a Dewar flask using liquid nitrogen to obtain a cryogel. The completely frozen cryogel was then pulverized using a high-speed multi-functional pulverizer (rotation speed 1000 r / min, pulverization time 60 min, pulverized aerogel particle diameter 200 μm) to obtain a fine, ice-like cryogel. This was then transferred to a freeze dryer for drying, resulting in aerogel powder. Ethanol and dialkyl hydroxyethyl methyl sulfate ammonium were added and mixed to prepare an aerogel slurry. The mixture of polyester and the aerogel slurry was then subjected to plasma treatment and further processed into a needle-punched nonwoven fabric, i.e., a nonwoven layer.

[0055] (3) The heat-expanding layer and the non-woven fabric layer prepared in step (1) are hot-pressed at a temperature of 200℃, a pressure of 10MPa and a time of 3h to obtain a flexible composite multilayer thermal insulation material.

[0056] The flexible composite multilayer high-temperature resistant thermal insulation material prepared in this embodiment was tested according to GB / T10295-2008. The thermal conductivity of the obtained flexible composite multilayer high-temperature resistant thermal insulation material at room temperature is 0.026 W / (m·K), the thermal conductivity at 1000℃ is 0.071 W / (m·K), the back temperature of the fabric at 1000℃ and 600s is 185℃, and the tensile strength of the fabric is 9.6 GPa.

[0057] Example 2

[0058] (1) Grind keratin and expandable graphite to below 800 mesh, add dispersant (1% polyvinyl alcohol aqueous solution) and additive (1M hydrochloric acid solution), add deionized water and continue grinding until surface flow is observed, add to a mixing pot, stir at low speed for 0.5h, then stir at high speed for 2h to obtain a mixed slurry; the speed of low speed stirring is 200 rpm, and the speed of high speed stirring is 500 rpm; the mass ratio of dispersant to keratin is 2:100; the mass ratio of additive to keratin is 0.004:1.

[0059] The mixed slurry is spun into keratin fibers by a one-step extrusion method. Then, four quartz fibers are wound around the surface of the keratin fibers to form a core-sheath composite yarn. The quartz fibers and the core-sheath composite yarn are woven together to obtain a six-layer shallow cross-bent quartz fiber cloth. After hot rolling and setting, an ablation-resistant layer (4 layers of quartz fiber) and a heat-expanding layer (2 layers of core-sheath composite yarn) are obtained.

[0060] (2) Commercially available water-based SiO2 sol, TiO2 sol, and ammonia were mixed in a volume ratio of 1:0.1:0.008 and stirred at room temperature (25℃) for 3 min to obtain water-based SiO2-TiO2 sol. The water-based SiO2 sol had a solid content of 15 wt% and an average particle size of 8 nm; the TiO2 sol had a solid content of 20 wt% and an average particle size of 25 nm; and the catalyst ammonia had a molar concentration of 0.35 mol / L.

[0061] The prepared water-based SiO2-TiO2 sol was frozen in a Dewar flask using liquid nitrogen to obtain a cryogel. The completely frozen cryogel was then pulverized using a high-speed multi-functional pulverizer (rotation speed 1000 r / min, pulverization time 60 min, pulverized aerogel particle diameter 200 μm) to obtain a fine, ice-like cryogel. This was then transferred to a freeze dryer for drying, resulting in aerogel powder. Ethanol and dialkyl hydroxyethyl methyl sulfate ammonium were added and mixed to prepare an aerogel slurry. The mixture of polyamide and the aerogel slurry was subjected to plasma treatment and then processed into a needle-punched nonwoven fabric, i.e., a nonwoven layer.

[0062] (3) The heat-expanding layer and the non-woven fabric layer prepared in step (1) are hot-pressed at a temperature of 180°C, a pressure of 15MPa and a time of 3h to obtain a flexible composite multilayer thermal insulation material.

[0063] The flexible composite multilayer high-temperature resistant thermal insulation material prepared in this embodiment was tested according to GB / T10295-2008. The thermal conductivity of the obtained flexible composite multilayer high-temperature resistant thermal insulation material at room temperature is 0.017 W / (m·K), the thermal conductivity at 1000℃ is 0.062 W / (m·K), the back temperature of the fabric at 1000℃ and 600s is 145℃, and the tensile strength of the fabric is 10.5 GPa.

[0064] Example 3

[0065] The scheme of the embodiment is similar to that of embodiment 1, except that in step (1), a six-layer shallow cross-linked quartz fiber cloth is prepared, wherein the ablation resistant layer is a 4-layer quartz fiber layer and the thermal expansion layer is a 2-layer core-sheath composite yarn layer.

[0066] The flexible composite multilayer high-temperature resistant thermal insulation material prepared in this embodiment was tested according to GB / T10295-2008. The thermal conductivity of the obtained flexible composite multilayer high-temperature resistant thermal insulation material at room temperature is 0.014 W / (m·K), the thermal conductivity at 1000℃ is 0.040 W / (m·K), the back temperature of the fabric at 1000℃ and 600s is 135℃, and the tensile strength of the fabric is 8.7 GPa.

[0067] Example 4

[0068] The scheme of this embodiment is similar to that of embodiment 1, except that in step (1), quartz fiber is replaced with silicon carbide fiber.

[0069] The flexible composite multilayer high-temperature resistant thermal insulation material prepared in this embodiment was tested according to GB / T10295-2008. The thermal conductivity of the obtained flexible composite multilayer high-temperature resistant thermal insulation material at room temperature is 0.029 W / (m·K), the thermal conductivity at 1000℃ is 0.074 W / (m·K), the back temperature of the fabric at 1000℃ and 600s is 186℃, and the tensile strength of the fabric is 8.3 GPa.

[0070] Example 5

[0071] The scheme of this embodiment is similar to that of embodiment 1, except that in step (1), quartz fiber is replaced with alumina fiber.

[0072] The flexible composite multilayer high-temperature resistant thermal insulation material prepared in this embodiment was tested according to GB / T10295-2008. The thermal conductivity of the obtained flexible composite multilayer high-temperature resistant thermal insulation material at room temperature is 0.021 W / (m·K), the thermal conductivity at 1000℃ is 0.052 W / (m·K), the back temperature of the fabric at 1000℃ and 600s is 153℃, and the tensile strength of the fabric is 8.5 GPa.

[0073] Example 6

[0074] The scheme of this embodiment is similar to that of embodiment 1, except that: in step (4), the hot pressing temperature is 180°C, the time is 2.5h, and the hot pressing pressure is 13MPa.

[0075] The flexible composite multilayer high-temperature resistant thermal insulation material prepared in this embodiment was tested according to GB / T10295-2008. The thermal conductivity of the obtained flexible composite multilayer high-temperature resistant thermal insulation material at room temperature is 0.019 W / (m·K), the thermal conductivity at 1000℃ is 0.065 W / (m·K), the back temperature of the fabric at 1000℃ and 600s is 142℃, and the tensile strength of the fabric is 9.2 GPa.

[0076] Example 7

[0077] The scheme of the embodiment is similar to that of embodiment 1, except that the number of keratin and the number of heat insulation fibers are changed, 6 quartz fibers are wound around the surface of 2 keratin fibers, and the yarn diameter is changed.

[0078] The flexible composite multilayer high-temperature resistant thermal insulation material prepared in this embodiment was tested according to GB / T10295-2008. The thermal conductivity of the obtained flexible composite multilayer high-temperature resistant thermal insulation material at room temperature is 0.025 W / (m·K), the thermal conductivity at 1000℃ is 0.067 W / (m·K), the back temperature of the fabric at 1000℃ and 600s is 172℃, and the tensile strength of the fabric is 11.6 GPa.

[0079] Comparative Example 1

[0080] The scheme of this comparative example is similar to that of Example 1, except that: in step (1), keratin and foamed graphite are not used, and quartz fibers are directly woven into four layers of shallow cross-linked quartz fiber cloth, which is then hot-pressed with non-woven fabric.

[0081] The flexible composite multilayer high-temperature resistant thermal insulation material prepared according to GB / T10295-2008 was tested. The thermal conductivity of the obtained flexible composite multilayer high-temperature resistant thermal insulation material at room temperature was 0.041 W / (m·K), the thermal conductivity at 1000℃ was 0.172 W / (m·K), the back temperature of the fabric at 1000℃ and 600s was 329℃, and the tensile strength of the fabric was 8.6 GPa.

[0082] Comparative Example 2

[0083] The scheme of this comparative example is similar to that of Example 1, except that the aerogel is not pulverized in step (2).

[0084] The flexible composite multilayer high-temperature resistant thermal insulation material prepared according to GB / T10295-2008 was tested. The thermal conductivity of the obtained flexible composite multilayer high-temperature resistant thermal insulation material at room temperature was 0.047 W / (m·K), the thermal conductivity at 1000℃ was 0.134 W / (m·K), the back temperature of the fabric at 1000℃ and 600s was 437℃, and the tensile strength of the fabric was 9.1 GPa.

[0085] Test case

[0086] To compare and illustrate the room temperature thermal conductivity, temperature difference between upper and lower layers measured at 1000℃, and warp fracture strength of the thermal insulation materials prepared in the various embodiments and comparative examples of the present invention, the main test methods are as follows, and the comparison results are shown in Table 1.

[0087] (1) Thermal conductivity at room temperature: Thermal conductivity at room temperature was tested according to GB / T10295-2008;

[0088] (2) Temperature difference between upper and lower layers measured at 1000℃: The heating plate is placed upright on the table, and a suction fan is used to partially cover the heating plate to raise the temperature of the heating plate to 1000℃. Four temperature sensors (manufactured by Xiamen Yudian Automation Co., Ltd., AI-7048) are placed on the upper and lower layers of the composite material, and the center part is selected as the "sensor test area". One end of the sensor is placed on the top of the composite material, and a single layer of fabric is placed on top. The function of this single layer of fabric is to press down the contact head of the sensor and maintain a certain degree of air permeability. The temperature of the back layer of the composite material is measured at 1000℃.

[0089] (3) Fabric tensile strength: Tensile properties were tested using a tensile strength tester with a 50KN sensor, a clamping distance of 100mm, and a tensile speed of 100mm / min.

[0090] Table 1. Performance test table for composite materials.

[0091]

[0092] As can be seen from Table 1, uniformly coating the pulverized aerogel onto the woven fabric significantly enhances the thermal insulation effect of the flexible composite multilayer thermal insulation material and also improves the tensile strength. Through the combination of the bottom layer and the needle-punched nonwoven fabric, the aerogel layer is more tightly connected to the woven fabric.

[0093] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method of making a flexible composite multilayer insulation material, characterized in that, Includes the following steps: S1. High-temperature resistant fibers are wound around the surface of keratin fibers to form a core-sheath composite yarn. S2. The heat insulation yarn is woven with the core-sheath composite structure yarn obtained in step S1 to obtain an ablation-resistant layer and a thermal expansion layer. S3. The thermoplastic polymer is mixed with aerogel slurry and then plasma treated to prepare a nonwoven fabric layer. S4. Hot-press the thermal expansion layer obtained in step S2 with the non-woven fabric layer obtained in step S3 to obtain a flexible composite multilayer thermal insulation material. In step S1, the keratin fibers are prepared by the following method: Keratin and expandable graphite are mixed and ground together. Dispersant, additives and water are added and grinding is continued until the surface is fluid. The mixture is stirred to obtain a mixed slurry. The mixed slurry is then spun into keratin fibers by a one-step extrusion method. In step S3, the aerogel slurry is prepared by the following method: (1) Mix water-based SiO2 sol, TiO2 sol and catalyst to obtain water-based SiO2-TiO2 sol; (2) Freeze the water-based SiO2-TiO2 sol obtained in step (1) to obtain a gel, pulverize and dry it to obtain aerogel powder; (3) The aerogel powder obtained in step (2) is mixed with ethanol and cationic surfactant to obtain the aerogel slurry.

2. The production method according to claim 1, characterized by, The mass ratio of the dispersant to keratin is 1~3:100; the mass ratio of the additive to keratin is 0.001~0.005:

1.

3. The preparation method according to claim 1, characterized in that, In step S1, the ratio of the number of high-temperature resistant fibers to the number of keratin fibers is 8:1 to 2:

1.

4. The preparation method according to claim 1, characterized in that, In step S4, the hot pressing conditions are: temperature of 150℃~230℃, pressure of 5 MPa~15 MPa, and time of 20 min~3 h.

5. The preparation method according to claim 1, characterized in that, In step (1), the solid content of the water-based SiO2 sol is 2 wt%~35 wt%, and the particle size is 2 nm~20 nm; the solid content of the TiO2 sol is 5 wt%~22 wt%, and the particle size is 3 nm~25 nm.

6. The preparation method according to claim 1, characterized in that, In step (1), the catalyst is selected from ammonia water; the molar concentration of the catalyst is 0.05 mol / L to 0.35 mol / L.

7. The preparation method according to claim 1, characterized in that, In step (2), the pulverization conditions are: the rotation speed of the pulverizer is 500 r / min to 2000 r / min, the pulverization time is 30 min to 90 min, and the diameter of the pulverized aerogel particles is 10 μm to 800 μm.

8. The flexible composite multilayer thermal insulation material prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The flexible composite multilayer thermal insulation material consists of an ablation-resistant layer, a thermal expansion layer, and a non-woven fabric layer from top to bottom.

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