Silica aerogel composite thermal insulation material and preparation method thereof

Abstract

The invention relates to the field of materials, in particular to a silicon dioxide aerogel composite thermal insulation material and a preparation method thereof. The silicon dioxide aerogel composite thermal insulation material is prepared by taking silicon dioxide aerogel, phenolic resin, a nano zirconium oxide graft and a locust bean gum graft as main raw materials and taking n-pentane, UV-327, hexamethylenetetramine and an antioxidant 1010 as auxiliary materials. The nano zirconium oxide graft and the locust bean gum graft are added into the silicon dioxide aerogel material, so that the prepared silicon dioxide aerogel composite material has excellent heat-insulating property, flame-retardant property and toughening effect, and the comprehensive requirements of the use scene of the silicon dioxide aerogel composite material on toughness and flame retardance are met; and the application market is expanded.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of materials, in particular to a silica aerogel composite thermal insulation material and a preparation method thereof. BACKGROUND

[0002] The core composition of the composite thermal insulation material includes a thermal insulation functional phase, a structural reinforcing phase and a functional modification phase. By means of the integration of the advantages of different materials, it not only retains high thermal insulation efficiency, but also makes up for the shortcomings of single thermal insulation material performance, and has outstanding characteristics such as wide temperature resistance range and strong environmental adaptability, and is widely used in building materials, industrial pipelines, new energy, aerospace transportation and special fields of people's livelihood. Although phenolic resin as a thermal insulation material has obvious advantages in thermal insulation performance, it still has obvious shortcomings in the balance of flame retardant performance in extreme scene adaptability and toughening modification due to its own molecular structure and preparation process.

[0003] As the thermal insulation functional phase of the composite thermal insulation material, silica aerogel has great application potential in the field of thermal insulation. Silica aerogel is prepared by sol-gel method, and a unique nano-porous network structure is formed, which gives high specific surface area, high porosity, low density and low thermal conductivity. However, the traditional preparation process of aerogel has obvious limitations. Not only is the process complex, but also the raw material requirements are high and the cost is high. This problem seriously restricts the large-scale production and commercialization of aerogel materials. At present, cost reduction is mainly realized in three aspects. First, replace the organic silicon source with inorganic silicon source. Inorganic silicon sources such as water glass have low cost, but may bring problems such as high impurity content and complicated post-processing steps. Second, reduce energy consumption by using atmospheric drying. Due to the existence of capillary force, the structure of aerogel collapses and the performance decreases, so a low surface tension solvent is needed for solvent replacement before atmospheric drying, which increases the cost of raw materials and time cost. At the same time, the cost of raw materials can be reduced by reducing the silicon source concentration, but the reduction of silicon content will inevitably lead to the decline of the overall performance of the product.

[0004] In order to further expand the application boundary of silica aerogel composite thermal insulation material, the research and development direction should focus on the synergistic promotion of performance optimization and cost control. Among them, the two major innovations of flame retardant modification and toughening reinforcement have great practical significance. However, there is often a technical contradiction between toughening and flame retardant. If organic components are introduced for toughening, the flame retardancy will be sacrificed. If inorganic flame retardant is added to improve the flame retardancy, the brittleness of the material will be further increased due to the agglomeration of the flame retardant particles. At present, the toughness and flame retardancy of silica aerogel composite material are difficult to meet the comprehensive needs of materials in complex scenarios.

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

[0006] The application aims to provide a silica aerogel composite thermal insulation material and a preparation method thereof.

[0007] The application aims to provide a silica aerogel composite thermal insulation material and a preparation method thereof. The silica aerogel composite thermal insulation material comprises the following components in parts by weight: 70-100 parts of phenolic resin, 4-7 parts of silica aerogel, 10-15 parts of nano zirconium oxide graft, 15-20 parts of locust bean gum graft, 1-3 parts of UV-327, 10-12 parts of hexamethylenetetramine, 3-4 parts of dimethyl silicone oil, 2-3 parts of n-pentane, and 1-2 parts of antioxidant 1010.

[0008] Further, the preparation method of the silica aerogel comprises the following steps. Step SSS1: tetraethyl orthosilicate and alkaline silica sol are added into an ethanol and water solution, dilute hydrochloric acid is added to adjust the pH to 2-3, reaction is carried out at 50-60 DEG C for 5-6 h, 10-20% sodium hydroxide aqueous solution is added to adjust the pH to 8-10, stirring is uniformly carried out, the temperature is reduced to 40-45 DEG C, glass fiber felt is soaked in the solution, gel is waited for, and gel glass fiber felt is prepared; Step SSS2: the gel glass fiber felt is aged in anhydrous ethanol, the aging temperature is 40-60 DEG C, and the aging time is 10-18 h, and aged gel glass fiber felt is prepared; Step SSS3: hexamethyldisilazane, anhydrous ethanol and gel are uniformly mixed, the temperature is increased to 50-60 DEG C, the aged gel glass fiber felt is soaked in the solution, soaking is carried out for 14-16 h, the felt is taken out, supercritical drying is carried out, and silica aerogel is prepared.

[0009] Further, in step SSS1, the mass concentration of the dilute hydrochloric acid is 5-8%.

[0010] Through the above technical scheme, tetraethyl orthosilicate is hydrolyzed into silanol under acidic conditions, and the silanol reacts with silica in the alkaline silica sol to form a silicon aldehyde condensate, the glass fiber felt is used as a carrier for impregnation, the gel is formed in situ on the surface and inside of the felt, the wet gel is obtained, the gel is aged in anhydrous ethanol, and finally the silanization reaction is carried out between the gel and hexamethyldisilazane to introduce hydrophobic groups, so that the product is prevented from being affected in heat conduction and other properties after water absorption, the service life is prolonged, and the silica aerogel is prepared.

[0011] Further, the preparation method of the locust bean gum graft comprises the following steps. Step S1: the locust bean gum is placed in a reactor, N,N-dimethylformamide and deionized water are added, zirconium phosphate and a catalyst are added while stirring, the temperature is increased to 70-75 DEG C, stirring reaction is carried out for 1-2 h, the reaction is completed, the solvent is removed under reduced pressure, and the locust bean gum intermediate is prepared by drying. Step S2: Put guanine into dimethyl sulfoxide, stir evenly, add locust bean gum intermediate, heat to 90-100℃, stir for 40-50min, reaction is completed, remove the solvent under reduced pressure, dry to obtain locust bean gum graft.

[0012] Further, in step S1, the catalyst is p-toluenesulfonic acid.

[0013] The phenolic resin has weak flame retardant performance, which limits its use scene, and therefore it is necessary to add a flame retardant to modify the silica aerogel composite. The three elements of combustion are combustible, fire source and combustion-supporting agent. The surface of the combustible can be covered to block the transmission of oxygen and heat, thereby achieving the effect of flame retardation. The traditional "three-source" carbon-forming flame retardant is physically mixed, and the components are not uniformly dispersed in the material. Some areas cannot effectively form a flame-retardant carbon layer, and the reaction is slow. When facing high-temperature flames, the barrier layer may not be formed in time to be ignited. The hydroxyl group on the locust bean gum reacts with the phosphoric acid group on the zirconium phosphate to produce a locust bean gum intermediate. The phosphoric acid group on the locust bean gum intermediate reacts with the amino group on the guanine to produce a locust bean gum graft. Compared with the prior art, the locust bean gum is a natural plant and belongs to a renewable resource. It is biodegradable after burning or being discarded, has good compatibility and processability, and has a lower production cost than synthetic carbon sources. It is suitable for large-scale industrial application and has a cost advantage, and meets the development trend of "green flame retardant". Guanine can be obtained by biological fermentation or plant extraction, which meets the requirements of environmentally friendly flame retardants. Guanine contains a large amount of N elements, and releases non-toxic gases such as ammonia and nitrogen gas after burning. Through the dual mechanisms of gas phase dilution and catalytic carbonization, the prepared flame retardant has superior performance.

[0014] In a high-temperature environment, the locust bean gum as a carbon source will be converted into a carbon layer structure under the action of an acidic catalyst, which can block the transmission of oxygen and heat and achieve the effect of flame retardation. Zirconium phosphate is the main acid source. Zirconium phosphate releases acidic catalysts during pyrolysis, which induces the formation of a carbon layer on the locust bean gum. These acids can cover the surface of the machine and prevent the transmission of heat. Zirconium elements also act as catalysts, which can react faster and reduce the release of smoke. Guanine releases non-toxic gases at high temperatures, which reduces the oxygen concentration and prevents the spread of flames. Finally, the acid source, carbon source and gas source are tightly combined at the molecular level through chemical grafting, which can quickly trigger a synergistic reaction without relying on physical diffusion, thereby improving the flame retardant efficiency and performance.

[0015] Further, the preparation method of the nano zirconium oxide graft includes the following steps: Step SS1: Put nano zirconium oxide into toluene, ultrasonic dispersion for 10-20 min, add terephthalic acid and p-toluenesulfonic acid, heat, stir for 1-2 h, filter, dry to obtain nano zirconium oxide intermediate; Step SS2: Add nano zirconium oxide intermediate into dimethyl sulfoxide, add amino-terminated polyether and base catalyst under nitrogen protection, heat to 160-170 DEG C, stir for 7-8 h, cool to room temperature, filter, dry to obtain nano zirconium oxide grafting product.

[0016] Further, in step SS1, the heating temperature is 95-100 DEG C.

[0017] Further, in step SS2, the base catalyst is triethylamine.

[0018] Further, in step SS2, the drying temperature is 50-60 DEG C.

[0019] Through the above technical scheme, the hydroxyl group on the nano zirconium oxide reacts with the carboxyl group on the terephthalic acid to obtain the nano zirconium oxide intermediate, and the carboxyl group on the nano zirconium oxide intermediate acylates the amino group on the amino-terminated polyether to obtain the nano zirconium oxide grafting product.

[0020] A preparation method of a silica aerogel composite thermal insulation material, comprising the following steps: Step A: Mix silica aerogel, phenolic resin, nano zirconium oxide grafting product, locust bean gum grafting product, UV-327, antioxidant 1010, and dimethyl silicone oil in a mixing tank to obtain a mixture; Step B: Add n-pentane into the mixture, stir for 5-10 min, add hexamethylenetetramine and stir uniformly to obtain a treated material; Step C: Pour the treated material into a mold, and foam at 80-85 DEG C for 5-10 min to obtain the silica aerogel composite thermal insulation material.

[0021] The present application has the following advantages: (1) The locust bean gum grafting product prepared in the present application is crosslinked with the silica aerogel, so that the prepared silica aerogel composite thermal insulation material has excellent flame retardant performance.

[0022] (2) The core of nano zirconium oxide toughening is stress-induced phase change toughening, which hinders the further expansion of cracks by stress-induced phase change, disperses energy through micro-cracks and crack deflection, and finally realizes the synergy of strength and toughness, but is prone to agglomeration, so that the toughening effect is weakened, through the grafting of amino polyether, the nano zirconium oxide can be wrapped and entangled, and is not prone to agglomeration and easy to fall off, and the ether bond is easy to rotate, which gives the molecular chain flexibility and can stretch and deform under stress to absorb energy, wherein the cyclic structure on terephthalic acid can enhance the mechanical properties, so that the prepared silica aerogel composite material has excellent mechanical properties.

[0023] (3) The application uses silica sol as a silicon source, compared with water glass, reduces the process of removing sodium ions, shortens the whole process time, simplifies the process flow, uses cheap silica sol to partially or completely replace organic silicon sources such as methyl silicate and ethyl silicate, reduces the cost, and is suitable for large-scale industrial production.

[0024] Of course, implementing any product of the present application does not necessarily require achieving all the advantages described above at the same time. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] Embodiment 1

[0027] A preparation method of a silica aerogel composite thermal insulation material comprises the following steps: Step A: 4 parts of silica aerogel, 70 parts of phenolic resin, 10 parts of nano zirconium oxide grafting, 15 parts of locust bean gum grafting, 1 part of UV-327, 1 part of antioxidant 1010, and 3 parts of dimethyl silicone oil are added into a mixing tank in proportion by weight and uniformly mixed to prepare a mixture; Step B: 2 parts of n-pentane are added into the mixture, stirred for 10 min, and 10 parts of hexamethylenetetramine are added and uniformly stirred to obtain a treated material; Step C: The treated material is poured into a mold and foamed at 85 DEG C for 10 min to obtain a silica aerogel composite thermal insulation material.

[0028] The preparation method of the silica aerogel comprises the following steps: Step SSS1: 10 ml of ethyl orthosilicate and 5 ml of basic silica sol were added to a solution of 20 ml of ethanol and 10 ml of water, 5% dilute hydrochloric acid was added to adjust the pH to 2, and the mixture was reacted at 60 DEG C for 6 h, 20% sodium hydroxide aqueous solution was added to adjust the pH to 10, and the mixture was stirred uniformly and cooled to 45 DEG C, 2 g of glass fiber felt was soaked in the mixture, and a gel was prepared by waiting for the gelation, thereby obtaining a gel glass fiber felt; Step SSS2: 2 g of the gel glass fiber felt was soaked in 20 ml of anhydrous ethanol for aging, the aging temperature was 60 DEG C, and the aging time was 18 h, thereby obtaining an aged gel glass fiber felt; Step SSS3: 10 ml of hexamethyldisilazane, 10 ml of anhydrous ethanol and 12 g of the gel were mixed uniformly, the temperature was raised to 55 DEG C, 2 g of the aged gel glass fiber felt was soaked in the mixture for 16 h, and the soaked glass fiber felt was taken out and subjected to supercritical drying, thereby obtaining a silica aerogel.

[0029] The basic silica sol was purchased from Kowin Silicon Products Co., Ltd., and the product model was JN-1430-A1; the mass fraction of silica in the basic 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 ≤9 mPa·s, and the average particle size of the silica was 10-15 nm.

[0030] The preparation method of the locust bean gum graft includes the following steps: Step S1: 5 g of locust bean gum was weighed and placed in a reactor, 20 ml of N,N-dimethylformamide and 70 ml of deionized water were added, 1.5 g of zirconium phosphate and 0.3 g of p-toluenesulfonic acid were added while stirring, the temperature was raised to 70 DEG C, and the mixture was stirred and reacted for 2 h; after the reaction was completed, the solvent was removed under reduced pressure, and the mixture was dried to obtain a locust bean gum intermediate; Step S2: 3.5 g of guanine was weighed and placed in 80 ml of dimethyl sulfoxide, the mixture was stirred uniformly, 2 g of the locust bean gum intermediate was added, the temperature was raised to 100 DEG C, and the mixture was stirred and reacted for 40 min; after the reaction was completed, the solvent was removed under reduced pressure, and the mixture was dried to obtain a locust bean gum graft.

[0031] The preparation method of the nano zirconium oxide graft includes the following steps: Step SS1: 5 g of nano zirconium oxide was weighed and placed in toluene, and ultrasonic dispersion was performed for 20 min; 1.5 g of terephthalic acid and 0.5 g of p-toluenesulfonic acid were added, the temperature was raised to 100 DEG C, and the mixture was stirred and reacted for 2 h; the mixture was filtered and dried to obtain a nano zirconium oxide intermediate; Step SS2: 5.5 g of the nano zirconium oxide intermediate was weighed and added to 100 ml of dimethyl sulfoxide, 2.5 g of an amino-terminated polyether and 0.4 g of triethylamine were added under nitrogen protection, the temperature was raised to 160 DEG C, and the mixture was stirred and reacted for 7 h; after the reaction was completed, the mixture was cooled to room temperature, filtered and dried to obtain a nano zirconium oxide graft.

[0032] Example 2

[0033] A preparation method of a silica aerogel composite thermal insulation material includes the following steps: Step A: 5 parts of silica aerogel, 75 parts of phenolic resin, 12 parts of nano zirconium oxide 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 are added into a mixing tank according to the weight fraction, and uniformly mixed to prepare a mixture; Step B: 2.5 parts of n-pentane are added into the mixture, stirred for 10 min, and 11 parts of hexamethylenetetramine are added and uniformly stirred to obtain a treated material; Step C: The treated material is poured into a mold, foamed at 85°C for 10 min, and a silica aerogel composite thermal insulation material is obtained.

[0034] The preparation methods of the silica aerogel, nano zirconium oxide graft, and locust bean gum graft are the same as those in Example 1.

[0035] Example 3

[0036] A preparation method of a silica aerogel composite thermal insulation material includes the following steps: Step A: 7 parts of silica aerogel, 100 parts of phenolic resin, 15 parts of nano zirconium oxide 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 are added into a mixing tank according to the weight fraction, and uniformly mixed to prepare a mixture; Step B: 3 parts of n-pentane are added into the mixture, stirred for 10 min, and 12 parts of hexamethylenetetramine are added and uniformly stirred to obtain a treated material; Step C: The treated material is poured into a mold, foamed at 85°C for 10 min, and a silica aerogel composite thermal insulation material is obtained.

[0037] The preparation methods of the silica aerogel, nano zirconium oxide graft, and locust bean gum graft are the same as those in Example 1.

[0038] Comparative Example 1 A preparation method of a silica aerogel composite thermal insulation material includes the following steps: Step A: 75 parts of phenolic resin, 12 parts of nano zirconium oxide 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 are added into a mixing tank according to the weight fraction, and uniformly mixed to prepare a mixture; Step B: 2.5 parts of n-pentane was added into the mixed material according to the weight fraction, stirred for 10 min, 11 parts of hexamethyl tetramine was added and stirred uniformly to obtain a treated material; Step C: The treated material was poured into a mold and foamed at 85°C for 10 min to obtain a silica aerogel composite thermal insulation material.

[0039] The preparation method of the nano zirconium oxide graft and the locust bean gum graft was the same as that of Example 1.

[0040] Comparative Example 2 A preparation method of a silica aerogel composite thermal insulation material includes the following steps: Step A: 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 were added into a mixing tank and mixed uniformly to obtain a mixed material according to the weight fraction; Step B: 2.5 parts of n-pentane was added into the mixed material according to the weight fraction, stirred for 10 min, 11 parts of hexamethyl tetramine was added and stirred uniformly to obtain a treated material; Step C: The treated material was poured into a mold and foamed at 85°C for 10 min to obtain a silica aerogel composite thermal insulation material.

[0041] The preparation method of the silica aerogel and the locust bean gum graft was the same as that of Example 1.

[0042] Comparative Example 3 A preparation method of a silica aerogel composite thermal insulation material includes the following steps: Step A: 5 parts of silica aerogel, 75 parts of phenolic resin, 12 parts of nano zirconium oxide graft, 2 parts of UV-327, 1.5 parts of antioxidant 1010, and 3.5 parts of dimethyl silicone oil were added into a mixing tank and mixed uniformly to obtain a mixed material according to the weight fraction; Step B: 2.5 parts of n-pentane was added into the mixed material according to the weight fraction, stirred for 10 min, 11 parts of hexamethyl tetramine was added and stirred uniformly to obtain a treated material; Step C: The treated material was poured into a mold and foamed at 85°C for 10 min to obtain a silica aerogel composite thermal insulation material.

[0043] The preparation method of the silica aerogel and the nano zirconium oxide graft was the same as that of Example 1.

[0044] Comparative Example 4 A preparation method of a silica aerogel composite thermal insulation material includes the following steps: Step A: 75 parts of phenolic resin, 2 parts of UV-327, 1.5 parts of antioxidant 1010, and 3.5 parts of dimethyl silicone oil were added into a mixing tank according to the weight fraction and mixed uniformly to prepare a mixture; Step B: 2.5 parts of n-pentane were added into the mixture, stirred for 10 min, and 11 parts of hexamethylenetetramine were added and stirred uniformly to obtain a treated material; Step C: The treated material was poured into a mold and foamed at 85℃ for 10 min to obtain a silica aerogel composite thermal insulation material.

[0045] Test Example The silica aerogel composite thermal insulation materials prepared in the examples and comparative examples of the present application were made into samples conforming to the test specifications, and the samples were tested for thermal conductivity according to GB / T 3399-1982, tested for flame retardant grade according to UL-94, tested for water absorption according to GB / T 8810-2005, and tested for tensile properties according to GB / T 1040.2-2022.

[0046]

[0047] From the above data, it can be seen that, compared with Example 2, the composite thermal insulation material prepared without adding silica aerogel in Comparative Example 1 has a higher thermal conductivity, poor thermal insulation performance, excellent tensile strength, and excellent flame retardant performance; compared with Example 2, the composite thermal insulation material prepared without adding nano zirconium oxide grafting material in Comparative Example 2 has a lower thermal conductivity, excellent thermal insulation performance, poor tensile strength, and excellent flame retardant performance; compared with Example 2, the composite thermal insulation material prepared without adding locust bean gum grafting material in Comparative Example 3 has a lower thermal conductivity, excellent thermal insulation performance, excellent tensile strength, and poor flame retardant performance; compared with Example 2, the composite thermal insulation material prepared without adding locust bean gum grafting material, nano zirconium oxide grafting material, and silica aerogel in Comparative Example 4 has a higher thermal conductivity, poor thermal insulation performance, poor tensile strength, and poor flame retardant performance; the silica aerogel prepared in the present application has thermal insulation performance, the locust bean gum grafting material has excellent flame retardant performance, and the nano zirconium oxide grafting material has excellent mechanical properties.

[0048] The above content is only an example and description of the concept of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, as long as they do not deviate from the concept of the present application or exceed the scope defined by the present claims, which shall be within the protection scope of the present application.

Claims

1. A silica aerogel composite thermal insulation material, characterized in that: The composition comprises the following components by weight: 70-100 parts of phenolic resin, 4-7 parts of silica aerogel, 10-15 parts of nano-zirconia grafted material, 15-20 parts of locust bean gum grafted material, 1-3 parts of UV-327, 10-12 parts of hexamethylenetetramine, 3-4 parts of dimethyl silicone oil, 2-3 parts of n-pentane, and 1-2 parts of antioxidant 1010; The preparation method of the locust bean gum graft comprises the following steps: Step S1: placing locust bean gum in a reactor, adding N,N-dimethylformamide and deionized water, adding zirconium phosphate and a catalyst while stirring, heating to 70-75°C, stirring and reacting for 1-2 hours, and after the reaction is completed, removing the solvent under reduced pressure and drying to obtain a locust bean gum intermediate; Step S2: placing guanine in dimethyl sulfoxide, stirring evenly, adding locust bean gum intermediate, heating to 90-100° C., stirring and reacting for 40-50 minutes, and after the reaction is completed, removing the solvent under reduced pressure, and drying to obtain a locust bean gum grafted product; The preparation method of the nano zirconium oxide grafted material comprises the following steps: Step SS1: Place nano-zirconia in toluene, ultrasonically disperse for 10-20 minutes, add terephthalic acid and p-toluenesulfonic acid, heat, stir and react for 1-2 hours, filter and dry to obtain a nano-zirconia intermediate; Step SS2: Add the nano-zirconia intermediate to dimethyl sulfoxide, add the amino-terminated polyether and base catalyst under nitrogen protection, heat to 160-170°C, stir and react for 7-8 hours, cool to room temperature, filter and dry to obtain the nano-zirconia grafted product.

2. The silica aerogel composite thermal insulation material according to claim 1, characterized in that: The preparation method of the silica aerogel comprises the following steps: Step SSS1: adding ethyl orthosilicate and alkaline silica sol to ethanol and aqueous solution, adding dilute hydrochloric acid to adjust the pH to 2-3, reacting at 50-60°C for 5-6 hours, adding 10-20% sodium hydroxide aqueous solution to adjust the pH to 8-10, stirring evenly, cooling to 40-45°C, soaking glass fiber mat therein, and waiting for gelation to obtain gel glass fiber mat; Step SSS2: soaking the gel glass fiber mat in anhydrous ethanol for aging at a temperature of 40-60° C. for 10-18 hours to obtain an aged gel glass fiber mat; Step SSS3: Hexamethyldisilazane, anhydrous ethanol and gel are mixed evenly, heated to 50-60° C., and the aged gel glass fiber felt is immersed therein for 14-16 hours. The mixture is taken out and subjected to 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°C.

6. The silica aerogel composite thermal insulation material according to claim 1, characterized in that: In step SS2, the base 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°C.

8. A method for preparing the silica aerogel composite thermal insulation material according to claim 1, characterized in that: The following steps are involved: Step A: adding silica aerogel, phenolic resin, nano-zirconia grafted product, locust bean gum grafted product, UV-327, antioxidant 1010, and dimethyl silicone oil into a mixing tank and mixing them evenly to prepare a mixture; Step B: adding n-pentane to the mixture, stirring for 5-10 minutes, adding hexamethylenetetramine and stirring evenly to obtain a treated material; Step C: pouring the treated material into a mold and foaming it at 80-85° C. for 5-10 minutes to obtain a silica aerogel composite thermal insulation material.

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