Silica aerogel composite thermal insulation material and preparation method thereof

Abstract

This invention relates to the field of materials, specifically to a silica aerogel composite thermal insulation material and its preparation method. This silica aerogel composite thermal insulation material is prepared using silica aerogel, phenolic resin, nano-zirconia grafted material, and locust bean gum grafted material as main raw materials, and n-pentane, UV-327, hexamethylenetetramine, and antioxidant 1010 as auxiliary materials. By adding nano-zirconia grafted material and locust bean gum grafted material to the silica aerogel material, the prepared silica aerogel composite material possesses excellent thermal insulation performance, flame retardant performance, and toughening effect, solving the comprehensive requirements of toughness and flame retardancy for various application scenarios of silica aerogel composite materials, and expanding its application market.

Description

Technical Field

[0001] This invention relates to the field of materials, specifically to a silica aerogel composite thermal insulation material and its preparation method. Background Technology

[0002] The core components of composite thermal insulation materials include a thermal insulation functional phase, a structural reinforcement phase, and a functional modification phase. By combining the advantages of different materials, it not only retains high thermal insulation efficiency but also compensates for the shortcomings of single thermal insulation materials. It also possesses outstanding characteristics such as a wide temperature range and strong environmental adaptability, making it widely used in building materials, industrial pipelines, new energy, aerospace transportation, and special consumer applications. While phenolic resin has significant advantages in thermal insulation performance, its molecular structure and manufacturing process limit its ability to adapt to extreme flame-retardant scenarios and balance the challenges of toughening modification.

[0003] Silica aerogel, as the thermal insulation functional phase in composite thermal insulation materials, has great application potential in the field of thermal insulation. Prepared via the sol-gel method, silica aerogel constructs a unique nanoporous network structure, thus endowing it with high specific surface area, high porosity, low density, and low thermal conductivity. However, traditional aerogel preparation processes have significant limitations: they are complex, require high-quality raw materials, and are expensive. This problem severely restricts the large-scale production and commercialization of aerogel materials. Currently, cost reduction is mainly achieved through three aspects: First, replacing organosilicon sources with inorganic silicon sources. Inorganic silicon sources such as water glass are cheaper, but may lead to high impurity content and cumbersome post-processing steps. Second, using atmospheric pressure drying reduces energy consumption. Due to capillary forces, the aerogel structure collapses, leading to performance degradation. Therefore, low-surface-tension solvents are needed for solvent replacement before atmospheric pressure drying, which increases raw material and time costs. Simultaneously, reducing silicon source concentration can reduce raw material costs; however, lower silicon content inevitably leads to a decrease in the overall performance of the product.

[0004] To further expand the application boundaries of silica aerogel composite insulation materials, research and development should focus on the synergistic advancement of performance optimization and cost control. Flame retardant modification and toughening reinforcement are two particularly significant innovations. However, toughening and flame retardancy often present technical contradictions. Introducing organic components for toughening sacrifices flame retardancy; conversely, adding inorganic flame retardants to improve flame retardancy can lead to increased material brittleness due to particle agglomeration. Currently, the toughness and flame retardancy of silica aerogel composite materials are insufficient to meet the comprehensive material requirements of complex scenarios.

[0005] Therefore, it is of great significance to develop a low-cost, flame-retardant, and toughened silica aerogel composite thermal insulation material. Summary of the Invention

[0006] The purpose of this invention is to provide a silica aerogel composite thermal insulation material and its preparation method.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A silica aerogel composite thermal insulation material comprises the following components by weight: 70-100 parts phenolic resin, 4-7 parts silica aerogel, 10-15 parts nano-zirconia graft, 15-20 parts locust bean gum graft, 1-3 parts UV-327, 10-12 parts hexamethylenetetramine, 3-4 parts dimethyl silicone oil, 2-3 parts n-pentane, and 1-2 parts antioxidant 1010.

[0009] Furthermore, the preparation method of the silica aerogel includes the following steps:

[0010] Step SSS1: Add tetraethyl orthosilicate and alkaline silica sol to ethanol and aqueous solution, add dilute hydrochloric acid to adjust pH to 2-3, react at 50-60℃ for 5-6 hours, add 10-20% sodium hydroxide aqueous solution to adjust pH to 8-10, stir evenly, cool to 40-45℃, immerse glass fiber mat in it, wait for gelation, and obtain gelled glass fiber mat;

[0011] Step SSS2: The gel glass fiber mat is soaked in anhydrous ethanol for aging at a temperature of 40-60℃ for 10-18 hours to obtain aged gel glass fiber mat.

[0012] Step SSS3: Mix hexamethyldisilazane, anhydrous ethanol and gel evenly, heat to 50-60℃, immerse the aged gel glass fiber mat in it for 14-16 hours, take it out and perform supercritical drying to obtain silica aerogel.

[0013] Furthermore, in step SSS1, the mass concentration of the dilute hydrochloric acid is 5-8%.

[0014] Through the above technical solution, tetraethyl orthosilicate is hydrolyzed into silanol under acidic conditions, which undergoes silaldehyde condensation with silica in alkaline silica sol. Glass fiber mat is used as a carrier for impregnation, and gel is formed in situ on its surface and inside to obtain wet gel. After aging in anhydrous ethanol, it finally undergoes a silanization reaction with hexamethyldisilazane to introduce hydrophobic groups, prevent the product from absorbing water and affecting its thermal conductivity and other properties, and extend its service life, thus obtaining silica aerogel.

[0015] Furthermore, the preparation method of the locust bean gum graft includes the following steps:

[0016] Step S1: Place locust bean gum in a reactor, add N,N-dimethylformamide and deionized water, add zirconium phosphate and catalyst while stirring, heat to 70-75℃, stir and react for 1-2 hours. After the reaction is completed, remove the solvent under reduced pressure and dry to obtain locust bean gum intermediate.

[0017] Step S2: Guanine is placed in dimethyl sulfoxide and stirred evenly. Locust bean gum intermediate is added, and the temperature is raised to 90-100℃. The mixture is stirred for 40-50 minutes. After the reaction is completed, the solvent is removed under reduced pressure and dried to obtain locust bean gum graft.

[0018] Furthermore, in step S1, the catalyst is p-toluenesulfonic acid.

[0019] The flame-retardant properties of phenolic resin, as described above, are weak, limiting its application scenarios. Therefore, flame retardants are needed to modify silica aerogel composites for flame retardancy. The three elements of combustion are combustible material, ignition source, and oxidizer. Flame retardancy can be achieved by covering the surface of the combustible material to block oxygen and heat transfer. Traditional "three-source" charring flame retardants, through physical mixing, result in uneven dispersion of components within the material. Some areas fail to effectively form a flame-retardant char layer, and the reaction rate is slow. When exposed to high-temperature flames, the char layer may not form in time before ignition. This invention involves esterifying the hydroxyl groups on locust bean gum with the phosphate groups on zirconium phosphate to obtain a locust bean gum intermediate. The phosphate groups on the locust bean gum intermediate then undergo an acid-base neutralization reaction with the amino groups on guanine to obtain a locust bean gum graft. Using locust bean gum and guanine as carbon and gas sources, compared with existing technologies, locust bean gum, as a natural plant, is a renewable resource and can be biodegraded after combustion or disposal. It also has good compatibility and processability, and its production cost is lower than that of synthetic carbon sources, making it suitable for large-scale industrial applications with cost advantages, which is in line with the development trend of "green flame retardant". Guanine can be obtained through bio-fermentation or plant extraction, which meets the requirements of environmentally friendly flame retardants. It contains a large amount of nitrogen element, and releases non-toxic gases such as ammonia and nitrogen after combustion. Through the synergistic effect of gas phase dilution and catalytic char formation, the prepared flame retardant has superior performance.

[0020] In high-temperature environments, locust bean gum, acting as a carbon source, transforms into a char layer structure under the action of an acidic catalyst. This structure isolates oxygen and heat transmission, achieving a flame-retardant effect. Zirconium phosphate serves as the primary acid source. During pyrolysis, zirconium phosphate releases an acidic catalyst, inducing the formation of a char layer from the locust bean gum. This acidity coats the surface of the material, preventing heat transfer. Zirconium also acts as a catalyst, accelerating the reaction and reducing smoke release. Guanine releases non-toxic gases at high temperatures, reducing oxygen concentration and preventing flame spread. Finally, a chemical grafting method tightly binds the acid source, carbon source, and gas source at the molecular level, rapidly triggering a synergistic reaction without relying on physical diffusion, thus improving flame-retardant efficiency and performance.

[0021] Furthermore, the preparation method of the nano-zirconia graft includes the following steps:

[0022] Step SS1: Place nano-zirconia in toluene, ultrasonically disperse for 10-20 min, add terephthalic acid and p-toluenesulfonic acid, heat, stir and react for 1-2 h, filter, and dry to obtain nano-zirconia intermediate;

[0023] Step SS2: Add the nano-zirconia intermediate to dimethyl sulfoxide, add terminal amino polyether and alkaline catalyst under nitrogen protection, heat to 160-170℃, stir for 7-8 hours, after the reaction is completed, cool to room temperature, filter, and dry to obtain nano-zirconia graft.

[0024] Furthermore, in step SS1, the heating temperature is 95-100℃.

[0025] Furthermore, in step SS2, the alkaline catalyst is triethylamine.

[0026] Furthermore, in step SS2, the drying temperature is 50-60°C.

[0027] Using the above technical solution, the hydroxyl groups on nano-zirconia react with the carboxyl groups on terephthalic acid to obtain nano-zirconia intermediates, and the carboxyl groups on nano-zirconia intermediates undergo an acylation reaction with the amino groups on the terminal amino polyether to obtain nano-zirconia grafts.

[0028] A method for preparing a silica aerogel composite thermal insulation material includes the following steps:

[0029] Step A: Add silica aerogel, phenolic resin, nano-zirconia graft, locust bean gum graft, UV-327, antioxidant 1010 and dimethyl silicone oil to a mixing tank and mix evenly to obtain a mixture.

[0030] Step B: Add n-pentane to the mixture and stir for 5-10 minutes. Then add hexamethylenetetramine and stir until homogeneous to obtain the treated material.

[0031] Step C: Pour the treated material into a mold and foam it at 80-85℃ for 5-10 minutes to obtain silica aerogel composite thermal insulation material.

[0032] The beneficial effects of this invention are:

[0033] (1) The cross-linking of the locust bean gum graft prepared by the present invention with silica aerogel results in the silica aerogel composite thermal insulation material having excellent flame retardant properties.

[0034] (2) The core of nano-zirconia toughening is stress-induced phase transformation toughening. Stress-induced phase transformation hinders further crack propagation, and energy is dispersed by microcracks and crack deflection, ultimately achieving strong and tough synergy. However, it is prone to agglomeration, which weakens the toughening effect. By grafting end amino polyether, nano-zirconia can be wrapped and encased, making it less prone to agglomeration and detachment. Furthermore, the ether bond is easy to rotate, giving the molecular chain flexibility, which can be stretched and deformed under stress to absorb energy. The cyclic structure on terephthalic acid can enhance mechanical properties, resulting in the prepared silica aerogel composite material having excellent mechanical properties.

[0035] (3) The present invention uses silica sol as silicon source. Compared with water glass, it reduces the sodium ion removal process, shortens the overall process time, simplifies the process flow, and uses inexpensive silica sol to partially or completely replace organosilicon sources such as methyl silicate and ethyl silicate, thereby reducing costs and making it suitable for large-scale industrial production.

[0036] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] A method for preparing a silica aerogel composite thermal insulation material includes the following steps:

[0040] Step A: According to the weight fraction, add 4 parts of silica aerogel, 70 parts of phenolic resin, 10 parts of nano-zirconia graft, 15 parts of locust bean gum graft, 1 part of UV-327, 1 part of antioxidant 1010 and 3 parts of dimethyl silicone oil into a mixing tank and mix evenly to obtain a mixture.

[0041] Step B: According to the weight fraction, add 2 parts of n-pentane to the mixture, stir for 10 minutes, add 10 parts of hexamethylenetetramine and stir evenly to obtain the treated material;

[0042] Step C: Pour the treated material into a mold and foam it at 85°C for 10 minutes to obtain silica aerogel composite thermal insulation material.

[0043] The preparation method of the silica aerogel includes the following steps:

[0044] Step SSS1: Add 10ml of tetraethyl orthosilicate and 5ml of alkaline silica sol to 20ml of ethanol and 10ml of aqueous solution, add 5% dilute hydrochloric acid to adjust the pH to 2, react at 60℃ for 6h, add 20% sodium hydroxide aqueous solution to adjust the pH to 10, stir evenly, cool to 45℃, immerse 2g of glass fiber mat in it, wait for gelation, and obtain gelled glass fiber mat;

[0045] Step SSS2: Soak 2g of gel glass fiber mat in 20ml of anhydrous ethanol for aging at 60℃ for 18h to obtain aged gel glass fiber mat.

[0046] Step SSS3: Mix 10 ml hexamethyldisilazane, 10 ml anhydrous ethanol and 12 g gel evenly, heat to 55°C, immerse 2 g aged gel glass fiber mat in it, soak for 16 h, take it out and perform supercritical drying to obtain silica aerogel.

[0047] The alkaline silica sol was purchased from Kehan ​​Silicon Products Co., Ltd., product model JN-1430-A1; the mass fraction of silica in the alkaline silica sol was 29-31%, the mass fraction of sodium oxide was ≤0.5%, the pH value was 9.0-10.5, the viscosity was ≤9mPa·s, and the average particle size of silica was 10-15nm.

[0048] The preparation method of the locust bean gum graft material includes the following steps:

[0049] Step S1: Weigh 5g of locust bean gum and place it in a reactor. Add 20ml of N,N-dimethylformamide and 70ml of deionized water. While stirring, add 1.5g of zirconium phosphate and 0.3g of p-toluenesulfonic acid. Heat to 70℃ and stir for 2 hours. After the reaction is complete, remove the solvent under reduced pressure and dry to obtain the locust bean gum intermediate.

[0050] Step S2: Weigh 3.5g of guanine, place it in 80ml of dimethyl sulfoxide, stir well, add 2g of locust bean gum intermediate, heat to 100℃, stir and react for 40min. After the reaction is completed, remove the solvent under reduced pressure and dry to obtain locust bean gum graft.

[0051] The preparation method of the nano-zirconia graft includes the following steps:

[0052] Step SS1: Weigh 5g of nano-zirconia and place it in toluene. Disperse it ultrasonically for 20min. Add 1.5g of terephthalic acid and 0.5g of p-toluenesulfonic acid. Heat to 100℃ and stir for 2h. Filter and dry to obtain nano-zirconia intermediate.

[0053] Step SS2: Weigh 5.5g of nano-zirconia intermediate and add it to 100ml of dimethyl sulfoxide. Under nitrogen protection, add 2.5g of terminal amino polyether and 0.4g of triethylamine, heat to 160℃, stir and react for 7h. After the reaction is completed, cool to room temperature, filter, and dry to obtain nano-zirconia graft.

[0054] Example 2

[0055] A method for preparing a silica aerogel composite thermal insulation material includes the following steps:

[0056] Step A: According to the weight fraction, add 5 parts of silica aerogel, 75 parts of phenolic resin, 12 parts of nano-zirconia graft, 16 parts of locust bean gum graft, 2 parts of UV-327, 1.5 parts of antioxidant 1010 and 3.5 parts of dimethyl silicone oil into a mixing tank and mix evenly to obtain a mixture.

[0057] Step B: According to the weight fraction, add 2.5 parts of n-pentane to the mixture, stir for 10 minutes, add 11 parts of hexamethylenetetramine and stir evenly to obtain the treated material;

[0058] Step C: Pour the treated material into a mold and foam it at 85°C for 10 minutes to obtain silica aerogel composite thermal insulation material.

[0059] The preparation methods for the silica aerogel, nano-zirconia graft, and locust bean gum graft are the same as in Example 1.

[0060] Example 3

[0061] A method for preparing a silica aerogel composite thermal insulation material includes the following steps:

[0062] Step A: According to the weight fraction, add 7 parts of silica aerogel, 100 parts of phenolic resin, 15 parts of nano-zirconia graft, 20 parts of locust bean gum graft, 3 parts of UV-327, 2 parts of antioxidant 1010 and 4 parts of dimethyl silicone oil into a mixing tank and mix evenly to obtain a mixture.

[0063] Step B: According to the weight fraction, add 3 parts of n-pentane to the mixture, stir for 10 minutes, add 12 parts of hexamethylenetetramine and stir evenly to obtain the treated material;

[0064] Step C: Pour the treated material into a mold and foam it at 85°C for 10 minutes to obtain silica aerogel composite thermal insulation material.

[0065] The preparation methods for the silica aerogel, nano-zirconia graft, and locust bean gum graft are the same as in Example 1.

[0066] Comparative Example 1

[0067] A method for preparing a silica aerogel composite thermal insulation material includes the following steps:

[0068] Step A: According to the weight fraction, add 75 parts of phenolic resin, 12 parts of nano-zirconia graft, 16 parts of locust bean gum graft, 2 parts of UV-327, 1.5 parts of antioxidant 1010 and 3.5 parts of dimethyl silicone oil into a mixing tank and mix evenly to obtain a mixture.

[0069] Step B: According to the weight fraction, add 2.5 parts of n-pentane to the mixture, stir for 10 minutes, add 11 parts of hexamethylenetetramine and stir evenly to obtain the treated material;

[0070] Step C: Pour the treated material into a mold and foam it at 85°C for 10 minutes to obtain silica aerogel composite thermal insulation material.

[0071] The preparation methods of the nano-zirconia graft and the locust bean gum graft are the same as those in Example 1.

[0072] Comparative Example 2

[0073] A method for preparing a silica aerogel composite thermal insulation material includes the following steps:

[0074] Step A: According to the weight fraction, add 5 parts of silica aerogel, 75 parts of phenolic resin, 16 parts of locust bean gum graft, 2 parts of UV-327, 1.5 parts of antioxidant 1010 and 3.5 parts of dimethyl silicone oil into a mixing tank and mix evenly to obtain a mixture.

[0075] Step B: According to the weight fraction, add 2.5 parts of n-pentane to the mixture, stir for 10 minutes, add 11 parts of hexamethylenetetramine and stir evenly to obtain the treated material;

[0076] Step C: Pour the treated material into a mold and foam it at 85°C for 10 minutes to obtain silica aerogel composite thermal insulation material.

[0077] The preparation methods for the silica aerogel and locust bean gum grafts are the same as in Example 1.

[0078] Comparative Example 3

[0079] A method for preparing a silica aerogel composite thermal insulation material includes the following steps:

[0080] Step A: According to the weight fraction, add 5 parts of silica aerogel, 75 parts of phenolic resin, 12 parts of nano-zirconia graft, 2 parts of UV-327, 1.5 parts of antioxidant 1010 and 3.5 parts of dimethyl silicone oil into a mixing tank and mix evenly to obtain a mixture.

[0081] Step B: According to the weight fraction, add 2.5 parts of n-pentane to the mixture, stir for 10 minutes, add 11 parts of hexamethylenetetramine and stir evenly to obtain the treated material;

[0082] Step C: Pour the treated material into a mold and foam it at 85°C for 10 minutes to obtain silica aerogel composite thermal insulation material.

[0083] The preparation methods for the silica aerogel and nano-zirconia grafts are the same as in Example 1.

[0084] Comparative Example 4

[0085] A method for preparing a silica aerogel composite thermal insulation material includes the following steps:

[0086] Step A: According to the weight fraction, add 75 parts of phenolic resin, 2 parts of UV-327, 1.5 parts of antioxidant 1010 and 3.5 parts of dimethyl silicone oil into a mixing tank and mix evenly to obtain a mixture.

[0087] Step B: According to the weight fraction, add 2.5 parts of n-pentane to the mixture, stir for 10 minutes, add 11 parts of hexamethylenetetramine and stir evenly to obtain the treated material;

[0088] Step C: Pour the treated material into a mold and foam it at 85°C for 10 minutes to obtain silica aerogel composite thermal insulation material.

[0089] Test case

[0090] The silica aerogel composite thermal insulation materials prepared in the embodiments and comparative examples of the present invention were made into samples that meet the test specifications. The thermal conductivity of the samples was tested according to GB / T 3399-1982; the flame retardancy rating of the samples was tested according to UL-94; the water absorption rate of the samples was tested according to GB / T 8810-2005; and the tensile properties of the samples were tested according to GB / T 1040.2-2022.

[0091]

[0092] The data above shows that, compared with Comparative Example 1 and Example 2, the composite thermal insulation material prepared without silica aerogel has a higher thermal conductivity, poor thermal insulation performance, excellent tensile strength, and excellent flame retardant performance; compared with Comparative Example 2 and Example 2, the composite thermal insulation material prepared without nano-zirconia graft has a lower thermal conductivity, excellent thermal insulation performance, poor tensile strength, and excellent flame retardant performance; compared with Comparative Example 3 and Example 2, the composite thermal insulation material prepared without locust bean gum graft has a lower thermal conductivity, excellent thermal insulation performance, excellent tensile strength, and poor flame retardant performance; compared with Comparative Example 4 and Example 2, the composite thermal insulation material prepared without locust bean gum graft, nano-zirconia graft, and silica aerogel has a higher thermal conductivity, poor thermal insulation performance, poor tensile strength, and poor flame retardant performance; the silica aerogel prepared in this invention has thermal insulation properties, the locust bean gum graft has excellent flame retardant properties, and the nano-zirconia graft has excellent mechanical properties.

[0093] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A silica aerogel composite thermal insulation material, characterized in that, The product comprises the following components by weight: 70-100 parts phenolic resin, 4-7 parts silica aerogel, 10-15 parts nano-zirconia graft, 15-20 parts locust bean gum graft, 1-3 parts UV-327, 10-12 parts hexamethylenetetramine, 3-4 parts dimethyl silicone oil, 2-3 parts n-pentane, and 1-2 parts antioxidant 1010. The preparation method of the locust bean gum graft material includes the following steps: Step S1: Place locust bean gum in a reactor, add N,N-dimethylformamide and deionized water, add zirconium phosphate and catalyst while stirring, heat to 70-75℃, stir and react for 1-2 hours. After the reaction is completed, remove the solvent under reduced pressure and dry to obtain locust bean gum intermediate. Step S2: Guanine is placed in dimethyl sulfoxide and stirred evenly. Locust bean gum intermediate is added, and the temperature is raised to 90-100℃. The mixture is stirred and reacted for 40-50 minutes. After the reaction is completed, the solvent is removed under reduced pressure and dried to obtain locust bean gum graft. The preparation method of the nano-zirconia graft includes the following steps: Step SS1: Place nano-zirconia in toluene, ultrasonically disperse for 10-20 min, add terephthalic acid and p-toluenesulfonic acid, heat, stir and react for 1-2 h, filter, and dry to obtain nano-zirconia intermediate; Step SS2: Add the nano-zirconia intermediate to dimethyl sulfoxide, add terminal amino polyether and alkaline catalyst under nitrogen protection, heat to 160-170℃, stir for 7-8 hours, after the reaction is completed, cool to room temperature, filter, and dry to obtain nano-zirconia graft.

2. The silica aerogel composite thermal insulation material according to claim 1, characterized in that, The preparation method of the silica aerogel includes the following steps: Step SSS1: Add tetraethyl orthosilicate and alkaline silica sol to ethanol and aqueous solution, add dilute hydrochloric acid to adjust pH to 2-3, react at 50-60℃ for 5-6 hours, add 10-20% sodium hydroxide aqueous solution to adjust pH to 8-10, stir evenly, cool to 40-45℃, immerse glass fiber mat in it, wait for gelation, and obtain gelled glass fiber mat; Step SSS2: The gel glass fiber mat is soaked in anhydrous ethanol for aging at a temperature of 40-60℃ for 10-18 hours to obtain aged gel glass fiber mat. Step SSS3: Mix hexamethyldisilazane, anhydrous ethanol and gel evenly, heat to 50-60℃, immerse the aged gel glass fiber mat in it for 14-16 hours, take it out and perform supercritical drying to obtain silica aerogel.

3. The silica aerogel composite thermal insulation material according to claim 2, characterized in that, In step SSS1, the mass concentration of the dilute hydrochloric acid is 5-8%.

4. The silica aerogel composite thermal insulation material according to claim 1, characterized in that, In step S1, the catalyst is p-toluenesulfonic acid.

5. The silica aerogel composite thermal insulation material according to claim 1, characterized in that, In step SS1, the heating temperature is 95-100℃.

6. The silica aerogel composite thermal insulation material according to claim 1, characterized in that, In step SS2, the alkaline catalyst is triethylamine.

7. The silica aerogel composite thermal insulation material according to claim 1, characterized in that, In step SS2, the drying temperature is 50-60℃.

8. A method for preparing the silica aerogel composite thermal insulation material as described in claim 1, characterized in that, Includes the following steps: Step A: Add silica aerogel, phenolic resin, nano-zirconia graft, locust bean gum graft, UV-327, antioxidant 1010 and dimethyl silicone oil to a mixing tank and mix evenly to obtain a mixture. Step B: Add n-pentane to the mixture and stir for 5-10 minutes. Then add hexamethylenetetramine and stir until homogeneous to obtain the treated material. Step C: Pour the treated material into a mold and foam it at 80-85℃ for 5-10 minutes to obtain silica aerogel composite thermal insulation material.

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