Silicon dioxide aerogel heat insulation composite material and preparation method thereof

Abstract

The invention relates to a silicon dioxide aerogel heat insulation composite material and a preparation method thereof, and relates to the technical field of silicon dioxide aerogel composites.The preparation method comprises the following steps that a silicon source, absolute ethyl alcohol and water are subjected to an acidic hydrolysis reaction, and hydrolysate is obtained; adjusting the pH value of the hydrolysate to be neutral by adopting ammonia water, adding amino silicon oil, and then continuously adjusting the pH value to be alkaline for condensation reaction to obtain wet gel; carrying out aging and absolute ethyl alcohol replacement on the wet gel, and then putting the wet gel into a trimethylchlorosilane solution to carry out first modification, so as to obtain first wet gel; and placing the first wet gel in an aromatic ring-containing isocyanate-terminated compound solution for second modification to obtain a second wet gel, and the like. The silicon dioxide aerogel heat insulation composite material provided by the invention has excellent high-temperature resistance, heat insulation performance, mechanical properties and the like, can meet the use requirements in certain specific high-temperature environments, and makes up for the defects of the existing silicon dioxide aerogel.

Description

Technical Field

[0001] The invention relates to the technical field of thermal insulation materials, and in particular to a silica aerogel thermal insulation composite material and a preparation method thereof. Background Art

[0002] Silica aerogel, with its unique nanoporous structure, exhibits excellent thermal insulation and lightweight properties, which makes it have a wide range of application potential in aerospace, building insulation, new energy and other high-tech and livelihood fields. At present, the sol-gel method is the mainstream technology for preparing silica aerogel. The process covers the process from selecting precursors (such as silicon alkoxides such as methyl orthosilicate and ethyl orthosilicate), through hydrolysis and polycondensation reaction to form wet gel, and then to a series of fine steps such as subsequent aging, washing, replacement and drying, and finally obtaining high-performance silica aerogel products.

[0003] However, although the existing silica aerogels have shown impressive performance under normal temperature conditions, their performance is often greatly reduced under high temperature conditions, which greatly limits their application in certain specific high-temperature fields. Specifically, the nanoporous structure of silica aerogels in the prior art is easily destroyed under high temperature conditions, resulting in a generally high average linear shrinkage rate. The instability of this structure not only affects the performance of the material, such as thermal insulation, but also shortens the service life of the material. This has, to a certain extent, hindered the further application and promotion of silica aerogels in higher temperatures and harsher environments.

[0004] Therefore, in response to the above problems, it is particularly important to develop a silica aerogel insulating composite material with excellent high temperature resistance, thermal stability and thermal insulation performance, which is of great significance for promoting the advancement of silica aerogel technology and expanding its application fields. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a silica aerogel thermal insulation composite material and a preparation method thereof.

[0006] In a first aspect, the present invention provides a method for preparing a silica aerogel thermal insulation composite material, the preparation method comprising the following steps:

[0007] The silicon source, anhydrous ethanol and water are subjected to an acidic hydrolysis reaction to obtain a hydrolyzate;

[0008] The pH of the hydrolyzate is adjusted to neutral with aqueous ammonia and amino silicone oil is added, and then the pH is further adjusted to alkaline for condensation reaction to obtain a wet gel;

[0009] The wet gel is aged and replaced with anhydrous ethanol, and then placed in a trimethylsilyl chloride solution for a first modification to obtain a first wet gel;

[0010] placing the first wet gel in a solution of an aromatic ring-containing terminal isocyanate compound for second modification to obtain a second wet gel;

[0011] The second wet gel is placed in anhydrous ethanol for cleaning and then dried to obtain the silica aerogel thermal insulation composite material.

[0012] Furthermore, the working condition parameters of the acidic hydrolysis reaction include: the molar ratio of the silicon source, the anhydrous ethanol and the water is (1-2):(10-17):(3-7), the pH of the acidic hydrolysis reaction is adjusted to 2-4 by acid, the acid includes oxalic acid, and the acidic hydrolysis reaction time is 2-3 hours; the pH of the condensation reaction is 9-10.

[0013] Furthermore, the molar ratio of the silicon source to the amino silicone oil is 1:(1-2).

[0014] Furthermore, the preparation method of the amino silicone oil comprises the following process:

[0015] The terminal hydroxyl silicone oil, the amino coupling agent and the alkaline catalyst in a molar ratio of (2-2.3):1:(0.01-0.05) are uniformly stirred, and then reacted at a constant temperature of 80-85° C. with stirring for 2-3 hours to obtain a mixture;

[0016] The mixture is heated to 105-110°C and then vacuumed. When the system viscosity is 4-6×10 3 mPa·s, stop evacuating, cool to room temperature, and obtain the amino silicone oil;

[0017] The terminal hydroxyl silicone oil includes WS62M from Wacker of Germany; the amino coupling agent is N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; and the alkaline catalyst includes potassium hydroxide.

[0018] Furthermore, the silicon source includes at least one of methyl orthosilicate and ethyl orthosilicate; the aromatic ring-containing terminal isocyanate compound includes at least one of toluene diisocyanate, diphenylmethane diisocyanate and naphthyl diisocyanate.

[0019] Furthermore, the property parameters of the trimethylsilyl chloride solution include: the solvent is n-hexane, and the volume ratio of the trimethylsilyl chloride to the n-hexane is 1:(5-10); the property parameters of the aromatic ring-containing terminal isocyanate compound solution include: the solvent is n-hexane, and the mass volume ratio of the aromatic ring-containing terminal isocyanate compound to the n-hexane is (10-20):1 in g / L.

[0020] Furthermore, the working condition parameters of the first modification include: in g / mL, the weight ratio of the wet gel to the trimethylsilyl chloride solution is a mass volume ratio of 1:(10-20), the temperature is 30-40°C, and the time is 1-2 hours; the working condition parameters of the second modification include: in g / mL, the weight ratio of the first wet gel to the terminal isocyanate compound solution is a mass volume ratio of 1:(20-30), the temperature is 30-40°C, and the time is 60-90 minutes.

[0021] Furthermore, the aging working condition parameters include: temperature of 45 to 55° C., time of 35 to 55 hours; and the drying method includes normal pressure drying.

[0022] In a second aspect, the present invention provides a silica aerogel thermal insulation composite material, wherein the silica aerogel thermal insulation composite material is prepared by the preparation method of the silica aerogel thermal insulation composite material described in any one of the first aspects.

[0023] The above technical solution provided by the embodiment of the present invention has at least the following advantages compared with the prior art:

[0024] The embodiment of the present invention provides a silica aerogel thermal insulation composite material and a preparation method thereof. The silica aerogel thermal insulation composite material provided by the present invention introduces amino silicone oil to participate in the condensation reaction during the preparation process of silica aerogel to obtain amino-modified silica wet gel; subsequently, a first modification is performed in a trimethylchlorosilane solution, and the trimethylchlorosilane can react with the hydroxyl group on the surface of the gel to form a hydrophobic siloxy bond, thereby improving the hydrophobicity and chemical stability of the material; and a second modification is performed in a terminal isocyanate compound solution containing an aromatic ring, and the amino group reacts quickly with the terminal isocyanate group to form a urea bond, and an aromatic ring structure is introduced to further enhance the thermal stability of the material, and finally a multi-cross-linked silica aerogel thermal insulation composite material is obtained, which significantly improves its high temperature resistance, thermal insulation performance, mechanical properties, etc., thereby meeting the use requirements in certain specific high temperature environments and making up for the shortcomings of existing silica aerogels. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0027] Figure 1 A schematic flow chart of a method for preparing a silica aerogel thermal insulation composite material provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0030] In a first aspect, the present invention provides a method for preparing a silica aerogel thermal insulation composite material, such as Figure 1 As shown, the preparation method comprises the following steps:

[0031] The silicon source, anhydrous ethanol and water are subjected to an acidic hydrolysis reaction to obtain a hydrolyzate;

[0032] The pH of the hydrolyzate is adjusted to neutral with aqueous ammonia and amino silicone oil is added, and then the pH is further adjusted to alkaline for condensation reaction to obtain a wet gel;

[0033] The wet gel is aged and replaced with anhydrous ethanol, and then placed in a trimethylsilyl chloride solution for a first modification to obtain a first wet gel;

[0034] placing the first wet gel in a solution of an aromatic ring-containing terminal isocyanate compound for second modification to obtain a second wet gel;

[0035] The second wet gel is placed in anhydrous ethanol for cleaning and then dried to obtain the silica aerogel thermal insulation composite material.

[0036] The embodiment of the present invention provides a method for preparing a silica aerogel thermal insulation composite material, wherein amino silicone oil is introduced into the silica aerogel preparation process to participate in the condensation reaction, so as to obtain an amino-modified silica wet gel; subsequently, a first modification is performed in a trimethylchlorosilane solution, wherein the trimethylchlorosilane can react with the hydroxyl group on the surface of the gel to form a hydrophobic siloxy bond, thereby improving the hydrophobicity and chemical stability of the material; and a second modification is performed in a terminal isocyanate compound solution containing an aromatic ring, wherein the amino group reacts rapidly with the terminal isocyanate group to form a urea bond, and an aromatic ring structure is introduced to further enhance the thermal stability of the material, thereby finally obtaining a multi-cross-linked silica aerogel thermal insulation composite material, which significantly improves its high temperature resistance, thermal insulation performance, mechanical properties, etc., thereby meeting the use requirements in certain specific high temperature environments and making up for the shortcomings of existing silica aerogels.

[0037] In some specific embodiments, the concentration of the aqueous ammonia is 20-30% by volume.

[0038] In some specific embodiments, the working condition parameters of the acidic hydrolysis reaction include: the molar ratio of the silicon source, the anhydrous ethanol and the water is (1-2):(10-17):(3-7), the acidic hydrolysis reaction pH is adjusted to 2-4 with acid, the acid includes oxalic acid, and the molar concentration of oxalic acid is 0.1-5 mol / L; the acidic hydrolysis reaction time is 2-3 hours; the pH of the condensation reaction is 9-10.

[0039] In some specific embodiments, the molar ratio of the silicon source to the amino silicone oil is 1:(1-2), preferably 1:1.5.

[0040] In some specific embodiments, the preparation method of the amino silicone oil comprises the following process:

[0041] The terminal hydroxyl silicone oil, the amino coupling agent and the alkaline catalyst in a molar ratio of (2-2.3):1:(0.01-0.05) are uniformly stirred, and then reacted at a constant temperature of 80-85° C. with stirring for 2-3 hours to obtain a mixture;

[0042] The mixture is heated to 105-110°C and then vacuumed. When the system viscosity is 4-6×10 3 mPa·s, stop evacuating, cool to room temperature, and obtain the amino silicone oil;

[0043] The terminal hydroxyl silicone oil includes WS62M from Wacker of Germany; the amino coupling agent is N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; and the alkaline catalyst includes potassium hydroxide.

[0044] In some specific embodiments, the silicon source includes at least one of methyl orthosilicate and ethyl orthosilicate; the aromatic ring-containing terminal isocyanate compound includes at least one of toluene diisocyanate, diphenylmethane diisocyanate and naphthyl diisocyanate.

[0045] In some specific embodiments, the property parameters of the trimethylsilyl chloride solution include: the solvent is n-hexane, and the volume ratio of the trimethylsilyl chloride to the n-hexane is 1:(5-10); the property parameters of the aromatic ring-containing terminal isocyanate compound solution include: the solvent is n-hexane, and the mass volume ratio of the aromatic ring-containing terminal isocyanate compound to the n-hexane is (10-20):1 in g / L.

[0046] In some specific embodiments, the working condition parameters of the first modification include: in g / mL, the weight ratio of the wet gel to the trimethylsilyl chloride solution is a mass volume ratio of 1:(10-20), the temperature is 30-40°C, and the time is 1-2 hours; the working condition parameters of the second modification include: in g / mL, the weight ratio of the first wet gel to the terminal isocyanate compound solution is a mass volume ratio of 1:(20-30), the temperature is 30-40°C, and the time is 60-90 minutes.

[0047] In some specific embodiments, the aging working condition parameters include: a temperature of 45 to 55° C. and a time of 35 to 55 hours; and the drying method includes normal pressure drying.

[0048] In a second aspect, based on the same inventive concept, the present invention provides a silica aerogel thermal insulation composite material, wherein the silica aerogel thermal insulation composite material is prepared by the preparation method of the silica aerogel thermal insulation composite material described in any one of the first aspects.

[0049] The silica aerogel thermal insulation composite material provided in the embodiment of the present invention is realized based on the preparation method of the silica aerogel thermal insulation composite material described in any one of the first aspects, and therefore has at least the beneficial effects of the silica aerogel thermal insulation composite material described in any one of the first aspects, which will not be described one by one here.

[0050] It should be noted that the component raw materials involved in the silica aerogel insulation composite material and the preparation method thereof provided in the embodiments of the present invention, unless otherwise specified or specifically described, can be directly commercially available products or homemade using existing public preparation methods; at the same time, the steps and parameters involved, unless otherwise specified or specifically described, can be carried out according to the existing processing technology of silica aerogel insulation composite materials or directly using existing equipment, and the present invention document will not describe them one by one.

[0051] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0052] Example 1

[0053] This example provides a silica aerogel thermal insulation composite material, and the preparation method of the silica aerogel thermal insulation composite material comprises the following steps:

[0054] Step (1): subjecting a silicon source, anhydrous ethanol and water to an acidic hydrolysis reaction to obtain a hydrolyzate; wherein the silicon source is methyl orthosilicate; the working condition parameters of the acidic hydrolysis reaction include: a molar ratio of the silicon source, the anhydrous ethanol and the water is 1.5:14:5, an acid is used to adjust the pH of the acidic hydrolysis reaction to 2.6, the acid is oxalic acid, and the acidic hydrolysis reaction time is 2.5 hours;

[0055] Step (2): adjusting the pH of the hydrolyzate obtained in step (1) to neutral with aqueous ammonia and adding amino silicone oil, and then continuing to adjust the pH to 9 for condensation reaction to obtain a wet gel; wherein the preparation method of the amino silicone oil comprises the following process: uniformly stirring the terminal hydroxyl silicone oil, amino coupling agent and alkaline catalyst in a molar ratio of 2.1:1:0.03, and then stirring and reacting at a constant temperature of 82°C for 2.5 hours to obtain a mixture; heating the mixture to 108°C, and then evacuating the mixture; when the system viscosity is 5×10 3 mPa·s, the vacuum was stopped, and the mixture was cooled to room temperature to obtain the amino silicone oil; the terminal hydroxy silicone oil included WS62M from Wacker of Germany; the amino coupling agent was N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; the alkaline catalyst was potassium hydroxide; the molar ratio of the silicon source to the amino silicone oil was 1:1.5;

[0056] Step (3): the wet gel obtained in step (2) is aged at 50° C. for 40 hours, replaced with anhydrous ethanol twice, and then placed in a trimethylchlorosilane solution for a first modification to obtain a first wet gel; wherein the property parameters of the trimethylchlorosilane solution include: the solvent is n-hexane, and the volume ratio of the trimethylchlorosilane to the n-hexane is 1:10; the working condition parameters of the first modification include: in g / mL, the weight ratio of the wet gel to the trimethylchlorosilane solution is a mass volume ratio of 1:15, the temperature is 35° C., and the time is 1.5 hours;

[0057] Step (4): placing the first wet gel obtained in step (3) in a terminal isocyanate compound solution containing an aromatic ring for second modification to obtain a second wet gel; wherein the property parameters of the terminal isocyanate compound solution containing an aromatic ring include: the solvent is n-hexane, the mass volume ratio of the terminal isocyanate compound containing an aromatic ring to the n-hexane is 15:1 in g / L, and the terminal isocyanate compound containing an aromatic ring is naphthyl diisocyanate; the working condition parameters of the second modification include: in g / mL, the mass volume ratio of the first wet gel to the terminal isocyanate compound solution is 1:25, the temperature is 35°C, and the time is 75 minutes;

[0058] Step (5): The second wet gel obtained in step (4) is washed in anhydrous ethanol, and then dried at 65° C. under normal pressure for 24 hours to obtain the silica aerogel thermal insulation composite material.

[0059] Example 2

[0060] This example provides a silica aerogel thermal insulation composite material, and the preparation method of the silica aerogel thermal insulation composite material comprises the following steps:

[0061] Step (1): subjecting a silicon source, anhydrous ethanol and water to an acidic hydrolysis reaction to obtain a hydrolyzate; wherein the silicon source is tetraethyl orthosilicate; the working condition parameters of the acidic hydrolysis reaction include: a molar ratio of the silicon source, the anhydrous ethanol and the water is 2:17:7, an acid is used to adjust the pH of the acidic hydrolysis reaction to 2.2, the acid is oxalic acid, and the acidic hydrolysis reaction time is 2 hours;

[0062] Step (2): adjusting the pH of the hydrolyzate obtained in step (1) to neutral with aqueous ammonia and adding amino silicone oil, and then continuing to adjust the pH to 9 for condensation reaction to obtain a wet gel; wherein the preparation method of the amino silicone oil comprises the following steps: uniformly stirring the terminal hydroxyl silicone oil, amino coupling agent and alkaline catalyst in a molar ratio of 2.3:1:0.05, and then stirring and reacting at a constant temperature of 80°C for 3 hours to obtain a mixture; heating the mixture to 108°C, and then evacuating the mixture; when the system viscosity is 4×10 3 mPa·s, the vacuum was stopped, and the mixture was cooled to room temperature to obtain the amino silicone oil; the terminal hydroxy silicone oil included WS62M from Wacker of Germany; the amino coupling agent was N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; the alkaline catalyst was potassium hydroxide; the molar ratio of the silicon source to the amino silicone oil was 1:1;

[0063] Step (3): the wet gel obtained in step (2) is aged at 50° C. for 40 hours, replaced with anhydrous ethanol twice, and then placed in a trimethylchlorosilane solution for a first modification to obtain a first wet gel; wherein the property parameters of the trimethylchlorosilane solution include: the solvent is n-hexane, and the volume ratio of the trimethylchlorosilane to the n-hexane is 1:5; the working condition parameters of the first modification include: in g / mL, the weight ratio of the wet gel to the trimethylchlorosilane solution is a mass volume ratio of 1:10, the temperature is 30° C., and the time is 2 hours;

[0064] Step (4): placing the first wet gel obtained in step (3) in a terminal isocyanate compound solution containing an aromatic ring for second modification to obtain a second wet gel; wherein the property parameters of the terminal isocyanate compound solution containing an aromatic ring include: the solvent is n-hexane, the mass volume ratio of the terminal isocyanate compound containing an aromatic ring to the n-hexane is 10:1 in g / L, and the terminal isocyanate compound containing an aromatic ring is toluene diisocyanate; the working condition parameters of the second modification include: in g / mL, the mass volume ratio of the first wet gel to the terminal isocyanate compound solution is 1:25, the temperature is 35°C, and the time is 75 minutes;

[0065] Step (5): The second wet gel obtained in step (4) is washed in anhydrous ethanol, and then dried at 65° C. under normal pressure for 24 hours to obtain the silica aerogel thermal insulation composite material.

[0066] Example 3

[0067] This example provides a silica aerogel thermal insulation composite material, and the preparation method of the silica aerogel thermal insulation composite material comprises the following steps:

[0068] Step (1): subjecting a silicon source, anhydrous ethanol and water to an acidic hydrolysis reaction to obtain a hydrolyzate; wherein the silicon source is tetraethyl orthosilicate; the working condition parameters of the acidic hydrolysis reaction include: a molar ratio of the silicon source, the anhydrous ethanol and the water is 1:10:3, an acid is used to adjust the pH of the acidic hydrolysis reaction to 2.8, the acid is oxalic acid, and the acidic hydrolysis reaction time is 3 hours;

[0069] Step (2): adjusting the pH of the hydrolyzate obtained in step (1) to neutral with aqueous ammonia and adding amino silicone oil, and then continuing to adjust the pH to 9 for condensation reaction to obtain a wet gel; wherein the preparation method of the amino silicone oil comprises the following process: uniformly stirring the terminal hydroxyl silicone oil, amino coupling agent and alkaline catalyst in a molar ratio of 2.3:1:0.05, and then stirring and reacting at a constant temperature of 80°C for 3 hours to obtain a mixture; heating the mixture to 108°C, and then evacuating the mixture; when the system viscosity is 6×103 mPa·s, the vacuum was stopped, and the mixture was cooled to room temperature to obtain the amino silicone oil; the terminal hydroxy silicone oil included WS62M from Wacker of Germany; the amino coupling agent was N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; the alkaline catalyst was potassium hydroxide; the molar ratio of the silicon source to the amino silicone oil was 1:1;

[0070] Step (3): the wet gel obtained in step (2) is aged at 50° C. for 40 hours, replaced with anhydrous ethanol twice, and then placed in a trimethylchlorosilane solution for a first modification to obtain a first wet gel; wherein the property parameters of the trimethylchlorosilane solution include: the solvent is n-hexane, and the volume ratio of the trimethylchlorosilane to the n-hexane is 1:5; the working condition parameters of the first modification include: in g / mL, the weight ratio of the wet gel to the trimethylchlorosilane solution is a mass volume ratio of 1:10, the temperature is 30° C., and the time is 2 hours;

[0071] Step (4): placing the first wet gel obtained in step (3) in a terminal isocyanate compound solution containing an aromatic ring for second modification to obtain a second wet gel; wherein the property parameters of the terminal isocyanate compound solution containing an aromatic ring include: the solvent is n-hexane, the mass volume ratio of the terminal isocyanate compound containing an aromatic ring to the n-hexane is 10:1 in g / L, and the terminal isocyanate compound containing an aromatic ring is diphenylmethane diisocyanate; the working condition parameters of the second modification include: in g / mL, the mass volume ratio of the first wet gel to the terminal isocyanate compound solution is 1:25, the temperature is 35°C, and the time is 75 minutes;

[0072] Step (5): The second wet gel obtained in step (4) is washed in anhydrous ethanol, and then dried at 65° C. under normal pressure for 24 hours to obtain the silica aerogel thermal insulation composite material.

[0073] Comparative Example 1

[0074] This example provides a silica aerogel thermal insulation composite material and a preparation method thereof, which is different from Example 1 only in that the terminal isocyanate compound containing an aromatic ring is adjusted to a terminal isocyanate compound having no aromatic ring in the side chain (specifically hexamethylene diisocyanate); the remaining steps and parameters are the same.

[0075] Comparative Example 2

[0076] This example provides a silica aerogel thermal insulation composite material and a preparation method thereof, which is different from Example 1 only in that the amino coupling agent is adjusted to γ-piperazinepropylmethyldimethoxysilane; the remaining steps and parameters are the same.

[0077] Test Case

[0078] In this example, the performance of the silica aerogel thermal insulation composite materials obtained in the above Examples 1 to 3 and Comparative Examples 1 to 2 was tested.

[0079] High temperature resistance test method: The silica aerogel thermal insulation composite material sample is placed in a high temperature environment of 1000°C for 2 hours, and then the average linear shrinkage (%) of the silica aerogel thermal insulation composite material sample is measured and calculated. The lower the average linear shrinkage (%), the better the high temperature resistance performance. The test results are shown in Table 1.

[0080] Table 1

[0081] Test samples Average linear shrinkage (%) Example 1 3.8 Example 2 9.1 Example 3 7.6 Comparative Example 1 27.4 Comparative Example 2 16.2

[0082] It can be seen from Table 1 that, compared with Comparative Examples 1 to 2, the silica aerogel thermal insulation composite material provided by the embodiment of the present invention has a lower average linear shrinkage in a 1000°C environment (all lower than 10%), and the lowest can reach 3.8%, and has excellent high temperature stability.

[0083] In addition, the present invention also tests the thermal insulation performance and mechanical properties of the silica aerogel thermal insulation composite materials obtained in Examples 1 to 3. The test results are shown in Table 2.

[0084] Table 2

[0085] Test samples Thermal conductivity (W / m·k) Compressive strength(Mpa) Example 1 0.0138 0.98 Example 2 0.0146 0.79 Example 3 0.0143 0.84

[0086] It can be seen from Table 2 that the silica aerogel thermal insulation composite material provided by the embodiment of the present invention has excellent thermal insulation performance and mechanical properties.

[0087] In summary, the embodiment of the present invention provides a silica aerogel thermal insulation composite material and a preparation method thereof. In the preparation process of the silica aerogel, amino silicone oil is introduced to participate in the condensation reaction to obtain an amino-modified silica wet gel; subsequently, a first modification is performed in a trimethylchlorosilane solution, and the trimethylchlorosilane can react with the hydroxyl group on the surface of the gel to form a hydrophobic siloxy bond, thereby improving the hydrophobicity and chemical stability of the material; and a second modification is performed in a terminal isocyanate compound solution containing an aromatic ring, and the amino group reacts rapidly with the terminal isocyanate group to form a urea bond, and an aromatic ring structure is introduced to further enhance the thermal stability of the material, and finally a multi-cross-linked silica aerogel thermal insulation composite material is obtained, which significantly improves its high temperature resistance, thermal insulation performance, mechanical properties, etc., thereby meeting the use requirements in certain specific high temperature environments and making up for the shortcomings of existing silica aerogels.

[0088] Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0089] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a silica aerogel thermal insulation composite material, characterized in that: The preparation method comprises the following steps: The silicon source, anhydrous ethanol and water are subjected to an acidic hydrolysis reaction to obtain a hydrolyzate; The pH of the hydrolyzate is adjusted to neutral with aqueous ammonia and amino silicone oil is added, and then the pH is further adjusted to alkaline for condensation reaction to obtain a wet gel; The wet gel is aged and replaced with anhydrous ethanol, and then placed in a trimethylsilyl chloride solution for a first modification to obtain a first wet gel; placing the first wet gel in a solution of an aromatic ring-containing terminal isocyanate compound for second modification to obtain a second wet gel; The second wet gel is placed in anhydrous ethanol for cleaning and then dried to obtain the silica aerogel thermal insulation composite material.

2. The method for preparing the silica aerogel thermal insulation composite material according to claim 1, characterized in that: The working condition parameters of the acidic hydrolysis reaction include: the molar ratio of the silicon source, the anhydrous ethanol and the water is (1-2):(10-17):(3-7), the pH of the acidic hydrolysis reaction is adjusted to 2-4 by acid, the acid includes oxalic acid, and the acidic hydrolysis reaction time is 2-3 hours; the pH of the condensation reaction is 9-10.

3. The method for preparing the silica aerogel thermal insulation composite material according to claim 1, characterized in that: The molar ratio of the silicon source to the amino silicone oil is 1:(1-2).

4. The method for preparing the silica aerogel thermal insulation composite material according to claim 1, characterized in that: The preparation method of the amino silicone oil comprises the following process: The terminal hydroxyl silicone oil, the amino coupling agent and the alkaline catalyst in a molar ratio of (2-2.3):1:(0.01-0.05) are uniformly stirred, and then reacted at a constant temperature of 80-85° C. with stirring for 2-3 hours to obtain a mixture; The mixture is heated to 105-110°C and then vacuumed. When the system viscosity is 4-6×10 3 mPa·s, stop evacuating, cool to room temperature, and obtain the amino silicone oil; The terminal hydroxyl silicone oil includes WS62M from Wacker of Germany; the amino coupling agent is N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; and the alkaline catalyst includes potassium hydroxide.

5. The method for preparing the silica aerogel thermal insulation composite material according to claim 1, characterized in that: The silicon source includes at least one of methyl orthosilicate and ethyl orthosilicate; the aromatic ring-containing terminal isocyanate compound includes at least one of toluene diisocyanate, diphenylmethane diisocyanate and naphthyl diisocyanate.

6. The method for preparing the silica aerogel thermal insulation composite material according to claim 1, characterized in that: The property parameters of the trimethylsilyl chloride solution include: the solvent is n-hexane, and the volume ratio of the trimethylsilyl chloride to the n-hexane is 1:(5-10); the property parameters of the aromatic ring-containing terminal isocyanate compound solution include: the solvent is n-hexane, and the mass volume ratio of the aromatic ring-containing terminal isocyanate compound to the n-hexane is (10-20):1 in g / L.

7. The method for preparing the silica aerogel thermal insulation composite material according to claim 1, characterized in that: The working condition parameters of the first modification include: in g / mL, the weight ratio of the wet gel to the trimethylsilyl chloride solution is a mass volume ratio of 1:(10-20), the temperature is 30-40°C, and the time is 1-2 hours; the working condition parameters of the second modification include: in g / mL, the weight ratio of the first wet gel to the terminal isocyanate compound solution is a mass volume ratio of 1:(20-30), the temperature is 30-40°C, and the time is 60-90 minutes.

8. The method for preparing the silica aerogel thermal insulation composite material according to claim 1, characterized in that: The working condition parameters of the aging process include: a temperature of 45 to 55° C. and a time of 35 to 55 hours; and the drying method includes normal pressure drying.

9. A silica aerogel thermal insulation composite material, characterized in that: The silica aerogel thermal insulation composite material is prepared by the preparation method described in any one of claims 1 to 8.

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