A silica aerogel / glass fiber composite mat and its preparation method

Abstract

This invention discloses a silica aerogel / glass fiber composite felt and its preparation method. The method includes: 1. Modification treatment of the glass fiber felt; 2. Preparation of a composite silica source hydrolysate; 3. Preparation of a silica wet gel-glass fiber felt composite; 4. Preparation of the silica aerogel / glass fiber composite felt. This invention, by treating the glass fiber felt with oxygen plasma and modifying it with a silane coupling agent, endows it with a large number of reactive C=C sites, thereby chemically bonding it with silica aerogel, improving the bonding strength between the two and avoiding the "powdering" phenomenon of traditional aerogel composite felts. Combined with the use of Soxhlet extraction for solvent replacement, the solvent replacement efficiency is significantly improved and the cost is greatly reduced, achieving cost reduction and efficiency improvement. The composite felt prepared by this invention has excellent thermal insulation and temperature resistance properties, and is suitable for applications in construction, pipelines, industrial furnaces, and new energy vehicles.

Description

Technical Field

[0001] This invention belongs to the field of aerogel composite material technology, specifically relating to a silica aerogel / glass fiber composite mat and its preparation method. Background Technology

[0002] Silica aerogel is a three-dimensional network of nanoporous materials with low thermal conductivity and density, high porosity and specific surface area, and resistance to high and low temperatures. It is widely used in military, aerospace, and construction industries. However, existing silica aerogel felts suffer from poor bonding between the aerogel and fiber felt, leading to powder shedding and severely impacting the aerogel felt's performance.

[0003] Currently, aerogel-inorganic fiber mat composites suffer from severe powder shedding and high preparation costs, hindering their large-scale application. The powder shedding problem is caused by insufficient adhesion between the aerogel and the fiber mat, as well as the aerogel's inherent insufficient mechanical strength. Chinese patent CN116024811A discloses a method for preparing nanofiber-reinforced aerogel-inorganic fiber composites, which uses plasma generated by inert gas to bombard the fibers, increasing surface roughness and forming a carbon-containing opacifier layer, thus strengthening the adhesion between the aerogel and the fiber. However, this method essentially relies on physical bonding, limiting its potential for improvement. In contrast, chemically bonding aerogel to glass fiber mat results in higher bonding strength and better stability.

[0004] Atmospheric pressure drying offers significant advantages in terms of low cost. However, to maintain the porous structure of aerogels, the wet gel composite material must undergo water washing, solvent replacement, and surface modification before drying. Traditional long-duration, multiple-soaking processes require large amounts of organic solvents, increasing production costs and reducing aerogel preparation efficiency. Therefore, new technologies are urgently needed to reduce costs and increase efficiency, with the recycling of organic solvents being key. Soxhlet extraction allows for solvent recycling. Specifically, the wet gel composite material is placed in a Soxhlet extractor, solvent is added to the bottom flask and heated. The solvent gas evaporates upwards, condenses, and flows back into the extractor. When its volume exceeds the siphon capacity, the solvent flows back to the bottom flask, and the cycle repeats. Utilizing its automatic extraction characteristic, the wet gel composite material is washed, replaced, and surface modified, avoiding multiple solvent changes. This significantly reduces solvent consumption and manual operation, greatly improving production efficiency and lowering manufacturing costs. Chinese patent CN105377758A, "Preparation Method of Hydrophobic Silica Aerogel," proposes using Soxhlet extraction to prepare silica aerogels. This method uses CO2 and dimethyl ether gases to circulate the wet gel under low pressure, simultaneously extracting the solvent and drying it. However, this method requires additional pressure control and pumping systems, increasing manufacturing costs. In contrast, using traditional Soxhlet extraction for wet gel pretreatment avoids significant equipment investment, making it more suitable for large-scale production and widespread application of aerogels. However, its drawback is that the impurity removal efficiency decreases with increasing extraction cycles. For example, when alcohol replaces water, it carries back a large amount of water from the wet gel when flowing back from the extractor to the bottom flask. Subsequent evaporation brings the water back to the extractor, weakening the alcohol replacement effect. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing silica aerogel / glass fiber composite mat. This method involves treating the glass fiber mat with oxygen plasma and modifying it with a silane coupling agent, enabling it to chemically bond with silica aerogel, thereby improving the bonding strength between the two and solving the problem of severe powder shedding in traditional aerogel composite mats. Simultaneously, an improved Soxhlet extraction method is used for solvent replacement, significantly improving the solvent replacement efficiency, greatly increasing the preparation efficiency of the composite mat, and reducing production costs.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing silica aerogel / glass fiber composite mat, characterized in that the method includes the following steps:

[0007] Step 1: Modification of glass fiber mat: First, the glass fiber mat is treated with oxygen plasma, and then modified with a silane coupling agent containing carbon-carbon double bonds to obtain modified glass fiber mat.

[0008] Step 2: Preparation of composite silicon source hydrolysate: Prepare tetraethyl orthosilicate hydrolysate and silicon source B hydrolysate separately, then add silicon source B hydrolysate dropwise to tetraethyl orthosilicate hydrolysate, and then add photoinitiator to obtain composite silicon source hydrolysate;

[0009] Step 3: Preparation of silica wet gel-glass fiber mat composite: The modified glass fiber mat obtained in step 1 is impregnated in the composite silicon source hydrolysate obtained in step 2, and a click chemical reaction is carried out under ultraviolet light. Then, ammonia water is added to obtain silica wet gel-glass fiber mat composite.

[0010] Step 4: Preparation of silica aerogel / glass fiber composite mat: The silica wet gel-glass fiber mat composite obtained in step 3 is placed in a Soxhlet extractor, and a desiccant is added to the bottom flask of the Soxhlet extractor. Then, ethanol and n-hexane are added for solvent replacement, and the mixture is dried under normal pressure to obtain silica aerogel / glass fiber composite mat.

[0011] This invention first uses oxygen plasma to hydroxylate glass fiber mat, increasing the number of hydroxyl active sites on the surface of the glass fiber mat. Then, it uses a silane coupling agent containing carbon-carbon double bonds for C=C graft modification, providing reactive C=C sites for the next step of chemical bonding with silica. The modified glass fiber mat is then impregnated in a composite silicon source hydrolysate for reaction, and ammonia is added to achieve gelation, obtaining a silica wet gel-glass fiber mat composite. The silica wet gel-glass fiber mat composite is placed in a Soxhlet extractor, and a desiccant is added to the bottom flask. Then, ethanol and n-hexane are added sequentially for solvent displacement. During the displacement process, the solvent added to the flask evaporates into gas upon heating, and flows upward through condensation and reflux into the extractor to displace the composite. When the volume of the displacement liquid is greater than the siphon volume of the Soxhlet extractor, the solvent carries the displaced water back to the bottom flask, while the desiccant removes the water in time, ensuring that only solvent flows into the extractor during the next evaporation cycle. This significantly improves the solvent displacement effect and reduces costs while increasing efficiency.

[0012] The above-mentioned method for preparing a silica aerogel / glass fiber composite mat is characterized in that the silane coupling agent containing carbon-carbon double bonds in step one is γ-methacryloyloxypropyltrimethoxysilane KH570, and the mass ratio of KH570 to the oxygen plasma-treated glass fiber mat is 1:4~5, and the modification treatment temperature is 55℃ and the time is 2h.

[0013] The above-mentioned method for preparing a silica aerogel / glass fiber composite mat is characterized in that the oxygen plasma treatment in step one has a power of 10W~30W and a time of 1min~2min.

[0014] The method for preparing a silica aerogel / glass fiber composite mat described above is characterized in that the hydrolysis time for preparing the tetraethyl orthosilicate hydrolysate in step two is 5h~7h, and the hydrolysis time for preparing the silicon source B hydrolysate is 1h.

[0015] The above-mentioned method for preparing a silica aerogel / glass fiber composite mat is characterized in that, in step two, the silicon source B in the silicon source B hydrolysate is γ-mercaptopropyltrimethoxysilane KH590, and the molar ratio of KH590 to tetraethyl orthosilicate (TEOS) in the tetraethyl orthosilicate hydrolysate is 0.1~0.3:1; the photoinitiator is type 1173 photoinitiator, and the added mass is 2% of the mass of silicon source B.

[0016] The method for preparing a silica aerogel / glass fiber composite mat described above is characterized in that the wavelength of ultraviolet light irradiation in step three is 365 nm.

[0017] The method for preparing the above-mentioned silica aerogel / glass fiber composite mat is characterized in that the light intensity of the click chemical reaction in step three is 50 mW / cm. 2 The time is 120 minutes.

[0018] The method for preparing a silica aerogel / glass fiber composite mat described above is characterized in that, in step four, the volume ratio of the silica wet gel-glass fiber mat composite to the siphon volume of the Soxhlet extractor does not exceed 0.47:1, the absorbent is silica gel, and the mass of the silica gel is 1.5 to 3.5 times the mass of water in the silica wet gel-glass fiber mat composite; the volume ratio of the added ethanol to the siphon volume of the Soxhlet extractor is 1 to 2:1, and the volume of added n-hexane is 4.5 times the volume of the silica wet gel-glass fiber mat composite.

[0019] In this invention, the siphon volume of the Soxhlet extractor refers to the minimum volume in which liquid is siphoned in the extractor.

[0020] The above-mentioned method for preparing a silica aerogel / glass fiber composite mat is characterized in that, in step four, the heating temperature for solvent replacement by adding ethanol is 80℃~95℃ and the time is 10h~12h, and the heating temperature for solvent replacement by adding n-hexane is 69℃~78℃ and the time is 6h~12h.

[0021] In addition, the present invention also discloses a silica aerogel / glass fiber composite felt, characterized in that it is prepared by the above-described method.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention treats glass fiber mat with oxygen plasma and modifies it with silane coupling agent to give it a large number of reactive C=C sites. This allows it to be chemically bonded to silica aerogel, improving the bonding strength between the two and avoiding the "powdering" phenomenon caused by insufficient adhesion and mechanical strength between glass fiber mat and silica aerogel. This improves the stability of the silica aerogel / glass fiber composite mat and ensures its thermal insulation and temperature resistance performance.

[0024] 2. This invention uses click chemistry reaction as a chemical bonding method for glass fiber mat and silica aerogel. Since the reaction is initiated by ultraviolet light energy, the reaction process is precise and does not introduce additional impurities. The reaction rate is fast and more environmentally friendly.

[0025] 3. This invention uses oxygen plasma treatment instead of traditional chemical etching, which greatly improves processing efficiency and simplifies the process. In addition, this invention uses KH590 as a silicon source, which provides thiol groups for the next click chemical reaction, participates in the C=C double bond reaction, and further improves the bonding strength between the glass fiber mat and the silica wet gel.

[0026] 4. This invention uses Soxhlet extraction to replace the traditional solvent soaking method to perform solvent replacement on the silica wet gel-glass fiber mat composite. By placing a desiccant in the bottom flask to remove the water flowing back during replacement, it ensures that only solvent flows into the extractor during solvent circulation evaporation and replacement. This optimizes the Soxhlet extraction process, significantly improves the solvent replacement efficiency, allows for the recycling of organic solvents, greatly reduces costs, saves preparation time, and achieves cost reduction and efficiency improvement.

[0027] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0028] Example 1

[0029] This embodiment includes the following steps:

[0030] Step 1: Modification of glass fiber mat: First, place 10g of glass fiber mat in an oxygen plasma atmosphere with a power of 10W for 1min of oxygen plasma treatment. Then, slowly dissolve 2g of γ-methacryloyloxypropyltrimethoxysilane KH570 in 98mL of ethanol at room temperature, and add acetic acid to adjust the pH value to 4.0 to obtain a modification solution. Then, immerse the glass fiber mat that has been treated with oxygen plasma in the above modification solution and perform modification treatment at 55℃ for 2h. After that, wash it three times with 450mL of water and once with 150mL of ethanol. Dry it at 60℃ for 4h to obtain modified glass fiber mat.

[0031] Step 2: Preparation of composite silicon source hydrolysate: 25g of tetraethyl orthosilicate, 44g of ethanol and 8.5g of water were mixed evenly at room temperature, and 1mol / L hydrochloric acid was added to adjust the pH to 2.6. After catalytic hydrolysis for 5h, tetraethyl orthosilicate hydrolysate was obtained. 2.35g of γ-mercaptopropyltrimethoxysilane KH590, 14.6g of ethanol and 2.3g of water were mixed evenly, and 0.047g of type 1173 photoinitiator was added. Then, 2mol / L acetic acid was added to adjust the pH to 4.1. After catalytic hydrolysis for 1h, silicon source B hydrolysate was obtained.

[0032] Silicon source B hydrolysate was slowly added dropwise to tetraethyl orthosilicate hydrolysate to obtain composite silicon source hydrolysate;

[0033] Step 3: Preparation of the silica wet gel-glass fiber mat composite: The modified glass fiber mat obtained in Step 1 is impregnated in the composite silica source hydrolysate obtained in Step 2, and a click chemical reaction is carried out under ultraviolet light irradiation at a wavelength of 365 nm and a light intensity of 50 mW / cm². 2 The reaction time was 120 min. After the reaction was completed, 0.5 mol / L ammonia was added to adjust the pH value to 5.9 to complete the gelation and obtain 117.5 mL of silica wet gel-glass fiber mat composite.

[0034] Step 4: Preparation of silica aerogel / glass fiber composite mat: The 117.5 mL silica wet gel-glass fiber mat composite obtained in Step 3 was placed in a Soxhlet extractor with a siphon volume of 250 mL. 16.2 g of silica gel was added to the bottom flask of the Soxhlet extractor. Then, 250 mL of ethanol was used for solvent replacement. The temperature was heated to 80 °C for 12 h. The water in the composite was replaced multiple times with ethanol. Then, 529 mL of n-hexane was used for solvent replacement. The temperature was heated to 69 °C for 12 h. The ethanol remaining in the composite was replaced multiple times with n-hexane. After completion, the composite was placed in a forced-air drying oven and dried at 60 °C and 120 °C for 2 h, respectively, to obtain silica aerogel / glass fiber composite mat.

[0035] Comparative Example 1

[0036] This comparative example includes the following steps:

[0037] Step 1: Modification of glass fiber mat: 2g of γ-methacryloxypropyltrimethoxysilane KH570 was slowly dissolved in 98mL of ethanol at room temperature, and acetic acid was added to adjust the pH to 4.0 to obtain a modification solution. 10g of glass fiber mat was then immersed in the above modification solution and modified at 55℃ for 2h. After that, it was washed three times with 450mL of water and once with 150mL of ethanol. It was then dried at 60℃ for 4h to obtain the modified glass fiber mat.

[0038] Step 2: Preparation of composite silicon source hydrolysate: 25g of tetraethyl orthosilicate, 44g of ethanol and 8.5g of water were mixed evenly at room temperature, and 1mol / L hydrochloric acid was added to adjust the pH to 2.6. After catalytic hydrolysis for 5h, tetraethyl orthosilicate hydrolysate was obtained. 2.35g of γ-mercaptopropyltrimethoxysilane KH590, 14.9g of ethanol and 2.3g of water were mixed evenly, and 0.047g of type 1173 photoinitiator was added. Then, 2mol / L acetic acid was added to adjust the pH to 4.1. After catalytic hydrolysis for 1h, silicon source B hydrolysate was obtained.

[0039] Silicon source B hydrolysate was slowly added dropwise to tetraethyl orthosilicate hydrolysate to obtain composite silicon source hydrolysate;

[0040] Step 3: Preparation of the silica wet gel-glass fiber mat composite: The modified glass fiber mat obtained in Step 1 is impregnated in the composite silica source hydrolysate obtained in Step 2, and a click chemical reaction is carried out under ultraviolet light irradiation at a wavelength of 365 nm and a light intensity of 50 mW / cm². 2 The reaction time was 120 min. After the reaction was completed, 0.5 mol / L ammonia was added to adjust the pH value to 5.9 to complete the gelation and obtain 117.5 mL of silica wet gel-glass fiber mat composite.

[0041] Step 4: Preparation of silica aerogel / glass fiber composite mat: 117.5 mL of the silica wet gel-glass fiber mat composite obtained in Step 3 was placed in a Soxhlet extractor, and 16.2 g of silica gel was added to the bottom flask of the Soxhlet extractor. Then, 250 mL of ethanol was used for solvent replacement, and the temperature was heated to 80 °C for 12 h. The water in the composite was replaced multiple times with ethanol. Then, 450 mL of n-hexane was used for solvent replacement, and the temperature was heated to 69 °C for 12 h. The ethanol remaining in the composite was replaced multiple times with n-hexane. After completion, the composite was placed in a forced-air drying oven and dried at 60 °C and 120 °C for 2 h respectively to obtain silica aerogel / glass fiber composite mat.

[0042] Example 2

[0043] This embodiment includes the following steps:

[0044] Step 1: Modification of glass fiber mat: First, place 10g of glass fiber mat in an oxygen plasma atmosphere with a power of 20W for oxygen plasma treatment for 1.5min. Then, slowly dissolve 2.22g of γ-methacryloyloxypropyltrimethoxysilane KH570 in 97.8mL of ethanol at room temperature, and add acetic acid to adjust the pH value to 4.0 to obtain a modification solution. Then, immerse the glass fiber mat treated with oxygen plasma in the above modification solution and perform modification treatment at 55℃ for 2h. After that, wash it three times with 450mL of water and once with 150mL of ethanol. Dry it at 60℃ for 4h to obtain modified glass fiber mat.

[0045] Step 2: Preparation of composite silicon source hydrolysate: 25g of tetraethyl orthosilicate, 44g of ethanol and 8.5g of water were mixed evenly at room temperature, and 1mol / L hydrochloric acid was added to adjust the pH to 2.6. After catalytic hydrolysis for 6h, tetraethyl orthosilicate hydrolysate was obtained. 4.7g of γ-mercaptopropyltrimethoxysilane KH590, 29.1g of ethanol and 4.6g of water were mixed evenly, and 0.094g of type 1173 photoinitiator was added. Then, 2mol / L acetic acid was added to adjust the pH to 4.1. After catalytic hydrolysis for 1h, silicon source B hydrolysate was obtained.

[0046] Silicon source B hydrolysate was slowly added dropwise to tetraethyl orthosilicate hydrolysate to obtain composite silicon source hydrolysate;

[0047] Step 3: Preparation of the silica wet gel-glass fiber mat composite: The modified glass fiber mat obtained in Step 1 is impregnated in the composite silica source hydrolysate obtained in Step 2, and a click chemical reaction is carried out under ultraviolet light irradiation at a wavelength of 365 nm and a light intensity of 50 mW / cm². 2 The reaction time was 120 min. After the reaction was completed, 0.5 mol / L ammonia was added to adjust the pH value to 5.9 to complete the gelation and obtain 117.5 mL of silica wet gel-glass fiber mat composite.

[0048] Step 4: Preparation of silica aerogel / glass fiber composite mat: The 117.5 mL silica wet gel-glass fiber mat composite obtained in Step 3 was placed in a Soxhlet extractor with a siphon volume of 250 mL. 32.75 g of silica gel was added to the bottom flask of the Soxhlet extractor. Then, 375 mL of ethanol was used for solvent replacement. The temperature was heated to 87.5 °C for 11 h. The water in the composite was replaced multiple times with ethanol. Then, 450 mL of n-hexane was used for solvent replacement. The temperature was heated to 73.5 °C for 9 h. The ethanol remaining in the composite was replaced multiple times with n-hexane. After completion, the composite was placed in a forced-air drying oven and dried at 60 °C and 120 °C for 2 h, respectively, to obtain silica aerogel / glass fiber composite mat.

[0049] Comparative Example 2

[0050] This comparative example includes the following steps:

[0051] Step 1: Modification of glass fiber mat: First, place 10g of glass fiber mat in an oxygen plasma atmosphere with a power of 20W for oxygen plasma treatment for 1.5min. Then, slowly dissolve 2.22g of γ-methacryloyloxypropyltrimethoxysilane KH570 in 97.8mL of ethanol at room temperature, and add acetic acid to adjust the pH value to 4.0 to obtain a modification solution. Then, immerse the glass fiber mat treated with oxygen plasma in the above modification solution and perform modification treatment at 55℃ for 2h. After that, wash it three times with 450mL of water and once with 150mL of ethanol. Dry it at 60℃ for 4h to obtain modified glass fiber mat.

[0052] Step 2: Preparation of composite silicon source hydrolysate: 25g of tetraethyl orthosilicate, 44g of ethanol and 8.5g of water were mixed evenly at room temperature, and 1mol / L hydrochloric acid was added to adjust the pH to 2.6. After catalytic hydrolysis for 6h, tetraethyl orthosilicate hydrolysate was obtained. 4.7g of γ-mercaptopropyltrimethoxysilane KH590, 29.1g of ethanol and 4.6g of water were mixed evenly, and 2mol / L acetic acid was added to adjust the pH to 4.1. After catalytic hydrolysis for 1h, silicon source B hydrolysate was obtained.

[0053] Silicon source B hydrolysate was slowly added dropwise to tetraethyl orthosilicate hydrolysate to obtain composite silicon source hydrolysate;

[0054] Step 3: Preparation of silica wet gel-glass fiber mat composite: The modified glass fiber mat obtained in Step 1 was immersed in the composite silicon source hydrolysate obtained in Step 2 for 120 min, and then 0.5 mol / L ammonia was added to adjust the pH value to 5.9 to complete the gelation and obtain 117.5 mL of silica wet gel-glass fiber mat composite.

[0055] Step 4: Preparation of silica aerogel / glass fiber composite mat: The 117.5 mL silica wet gel-glass fiber mat composite obtained in Step 3 was placed in a Soxhlet extractor with a siphon volume of 250 mL. 32.75 g of silica gel was added to the bottom flask of the Soxhlet extractor. Then, 375 mL of ethanol was used for solvent replacement. The temperature was heated to 87.5 °C for 11 h. The water in the composite was replaced multiple times with ethanol. Then, 450 mL of n-hexane was used for solvent replacement. The temperature was heated to 73.5 °C for 9 h. The ethanol remaining in the composite was replaced multiple times with n-hexane. After completion, the composite was placed in a forced-air drying oven and dried at 60 °C and 120 °C for 2 h, respectively, to obtain silica aerogel / glass fiber composite mat.

[0056] Example 3

[0057] This embodiment includes the following steps:

[0058] Step 1: Modification of glass fiber mat: First, place 10g of glass fiber mat in an oxygen plasma atmosphere with a power of 30W for 2min of oxygen plasma treatment. Then, slowly dissolve 2.5g of γ-methacryloyloxypropyltrimethoxysilane KH570 in 98mL of ethanol at room temperature, and add acetic acid to adjust the pH value to 4.0 to obtain a modification solution. Then, immerse the glass fiber mat that has been treated with oxygen plasma in the above modification solution and perform modification treatment at 55℃ for 2h. After that, wash it three times with 450mL of water and once with 150mL of ethanol. Dry it at 60℃ for 4h to obtain modified glass fiber mat.

[0059] Step 2: Preparation of composite silicon source hydrolysate: 25g of tetraethyl orthosilicate, 44g of ethanol and 8.5g of water were mixed evenly at room temperature, and 1mol / L hydrochloric acid was added to adjust the pH to 2.6. After catalytic hydrolysis for 7h, tetraethyl orthosilicate hydrolysate was obtained. 7.06g of γ-mercaptopropyltrimethoxysilane KH590, 43.65g of ethanol and 6.9g of water were mixed evenly, and 0.14g of type 1173 photoinitiator was added. Then, 2mol / L acetic acid was added to adjust the pH to 4.1. After catalytic hydrolysis for 1h, silicon source B hydrolysate was obtained.

[0060] Silicon source B hydrolysate was slowly added dropwise to tetraethyl orthosilicate hydrolysate to obtain composite silicon source hydrolysate;

[0061] Step 3: Preparation of the silica wet gel-glass fiber mat composite: The modified glass fiber mat obtained in Step 1 is impregnated in the composite silica source hydrolysate obtained in Step 2, and a click chemical reaction is carried out under ultraviolet light irradiation at a wavelength of 365 nm and a light intensity of 50 mW / cm². 2 The reaction time was 120 min. After the reaction was completed, 0.5 mol / L ammonia was added to adjust the pH value to 5.9 to complete the gelation and obtain 117.5 mL of silica wet gel-glass fiber mat composite.

[0062] Step 4: Preparation of silica aerogel / glass fiber composite mat: The 117.5 mL silica wet gel-glass fiber mat composite obtained in Step 3 was placed in a Soxhlet extractor with a siphon volume of 250 mL. 53.9 g of silica gel was added to the bottom flask of the Soxhlet extractor. Then, 500 mL of ethanol was used for solvent replacement. The temperature was 95 °C and the time was 10 h. The water in the composite was replaced multiple times with ethanol. Then, 450 mL of n-hexane was used for solvent replacement. The temperature was 78 °C and the time was 6 h. The ethanol remaining in the composite was replaced multiple times with n-hexane. After completion, the composite was placed in a forced-air drying oven and dried at 60 °C and 120 °C for 2 h, respectively, to obtain silica aerogel / glass fiber composite mat.

[0063] Comparative Example 3

[0064] This comparative example includes the following steps:

[0065] Step 1: Modification of glass fiber mat: First, place 10g of glass fiber mat in an oxygen plasma atmosphere with a power of 30W for 2min of oxygen plasma treatment. Then, slowly dissolve 2.5g of γ-methacryloyloxypropyltrimethoxysilane KH570 in 98mL of ethanol at room temperature, and add acetic acid to adjust the pH value to 4.0 to obtain a modification solution. Then, immerse the glass fiber mat that has been treated with oxygen plasma in the above modification solution and perform modification treatment at 55℃ for 2h. After that, wash it three times with 450mL of water and once with 150mL of ethanol. Dry it at 60℃ for 4h to obtain modified glass fiber mat.

[0066] Step 2: Preparation of composite silicon source hydrolysate: 25g of tetraethyl orthosilicate, 44g of ethanol and 8.5g of water were mixed evenly at room temperature, and 1mol / L hydrochloric acid was added to adjust the pH to 2.6. After catalytic hydrolysis for 7h, tetraethyl orthosilicate hydrolysate was obtained. 7.06g of γ-mercaptopropyltrimethoxysilane KH590, 43.65g of ethanol and 6.9g of water were mixed evenly, and 0.14g of type 1173 photoinitiator was added. Then, 2mol / L acetic acid was added to adjust the pH to 4.1. After catalytic hydrolysis for 1h, silicon source B hydrolysate was obtained.

[0067] Silicon source B hydrolysate was slowly added dropwise to tetraethyl orthosilicate hydrolysate to obtain composite silicon source hydrolysate;

[0068] Step 3: Preparation of the silica wet gel-glass fiber mat composite: The modified glass fiber mat obtained in Step 1 is impregnated in the composite silica source hydrolysate obtained in Step 2, and a click chemical reaction is carried out under ultraviolet light irradiation at a wavelength of 365 nm and a light intensity of 50 mW / cm². 2The reaction time was 120 min. After the reaction was completed, 0.5 mol / L ammonia was added to adjust the pH value to 5.9 to complete the gelation and obtain 117.5 mL of silica wet gel-glass fiber mat composite.

[0069] Step 4: Preparation of silica aerogel / glass fiber composite mat: The 117.5 mL silica wet gel-glass fiber mat composite obtained in Step 3 was placed in a beaker containing 250 mL of ethanol and soaked for 10 h. The water in the composite was replaced by ethanol multiple times. Then, it was soaked in 450 mL of n-hexane 4 times, 1.5 h each time, and the ethanol remaining in the composite was replaced by n-hexane multiple times. After completion, the composite was placed in a forced-air drying oven and dried at 60℃ and 120℃ for 2 h respectively to obtain silica aerogel / glass fiber composite mat.

[0070] The performance of the silica aerogel / glass fiber composite mats prepared in Examples 1-3 and Comparative Examples 1-3 of this invention was tested:

[0071] (1) Thermal conductivity test: Three sets (two pieces per set) of silica aerogel / glass fiber composite felt with a size of 30mm×30mm (length×width) were cut and thermal conductivity was tested using the transient hot wire method. Each set of samples was tested three times and the average value was taken. The average value of the thermal conductivity of each sample was taken as the thermal conductivity result, as shown in Table 1 below.

[0072] (2) Powder shedding rate test: The silica aerogel / glass fiber composite felt sample was bent 180° 100 times, and the mass change before and after bending was recorded to calculate the powder shedding rate. Each sample was tested three times and the average value was taken as the powder shedding rate result, as shown in Table 1 below.

[0073]

[0074] As shown in Table 1, the thermal conductivity and dust shedding rate of the silica aerogel / glass fiber composite felts prepared in Examples 1-3 of this invention are lower than those in Comparative Examples 1-3. Specifically, compared to Comparative Example 1, which directly modified the glass fiber felt, Example 1 increased the number of active sites by pre-treating the glass fiber felt with oxygen plasma, thereby improving the bonding strength and reducing dust shedding. Compared to Comparative Example 2, which directly used an impregnation method to composite silica wet gel and glass fiber felt, Example 2 achieved chemical bonding by adding a photoinitiator and conducting a click chemical reaction under ultraviolet light, significantly improving the bonding strength, greatly reducing dust shedding, and enhancing the thermal insulation and temperature resistance of the composite felt. Compared to Comparative Example 3, which used direct immersion for solvent replacement, Example 3 used a Soxhlet extraction method, placing a desiccant in the bottom flask to remove the water from the replacement reflux in a timely manner, improving the replacement effect, enhancing the quality of the composite felt, and significantly improving its thermal insulation and temperature resistance.

[0075] In summary, this invention improves the bonding strength between silica aerogel and glass fiber mat by treating the glass fiber mat with oxygen plasma and modifying it with a silane coupling agent. This avoids the "powdering" phenomenon caused by insufficient adhesion and mechanical strength between the glass fiber mat and silica aerogel. Combined with the Soxhlet extraction method and the use of a water-absorbing agent for full replacement, the thermal insulation performance of the silica aerogel / glass fiber composite mat is effectively guaranteed.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a silica aerogel / glass fiber composite mat, characterized by, The method comprises the following steps: Step one, modification treatment of glass fiber felt: first, the glass fiber felt is treated by oxygen plasma, and then modified by silane coupling agent containing carbon-carbon double bond to obtain modified glass fiber felt; the silane coupling agent containing carbon-carbon double bond is γ-methacryloxypropyl trimethoxysilane KH570; Step two, preparation of composite silicon source hydrolysate: prepare tetraethyl orthosilicate hydrolysate and silicon source B hydrolysate respectively, then drop silicon source B hydrolysate into tetraethyl orthosilicate hydrolysate, and then add photoinitiator to obtain composite silicon source hydrolysate; the silicon source B in the silicon source B hydrolysate is γ-mercaptopropyl trimethoxysilane KH590; Step three, preparation of silica wet gel-glass fiber felt composite: the modified glass fiber felt obtained in step one is immersed in the composite silicon source hydrolysate obtained in step two, and then click chemistry reaction is carried out under ultraviolet light, and then ammonia is added to obtain silica wet gel-glass fiber felt composite; Step four, preparation of silica aerogel / glass fiber composite felt: the silica wet gel-glass fiber felt composite obtained in step three is placed in a Soxhlet extractor, a water absorbing agent is added in the bottom flask of the Soxhlet extractor, and then ethanol and n-hexane are added respectively for solvent replacement, and then normal pressure drying is carried out to obtain silica aerogel / glass fiber composite felt.

2. The method of claim 1, wherein the silica aerogel / glass fiber composite mat is prepared by the steps of: a) providing a glass fiber mat; b) providing a silica aerogel; c) impregnating the glass fiber mat with the silica aerogel; d) drying the impregnated glass fiber mat; and e) curing the impregnated glass fiber mat. In step one, the mass ratio of KH570 to the glass fiber felt treated by oxygen plasma is 1:4-5, the modification treatment temperature is 55°C, and the treatment time is 2h.

3. The method of claim 1, wherein the silica aerogel / glass fiber composite mat is prepared by the steps of: a) providing a glass fiber mat; b) providing a silica aerogel; c) impregnating the glass fiber mat with the silica aerogel; d) drying the impregnated glass fiber mat; and e) curing the impregnated glass fiber mat. In step one, the power of the oxygen plasma treatment is 10W-30W, and the treatment time is 1min-2min.

4. The method of claim 1, wherein the silica aerogel / glass fiber composite mat is prepared by the steps of: a) providing a glass fiber mat; b) providing a silica aerogel; c) impregnating the glass fiber mat with the silica aerogel; d) drying the impregnated glass fiber mat; and e) curing the impregnated glass fiber mat. In step two, the hydrolysis time for preparing the tetraethyl orthosilicate hydrolysate is 5h-7h, and the hydrolysis time for preparing the silicon source B hydrolysate is 1h.

5. The method of claim 1, wherein the silica aerogel / glass fiber composite mat is prepared by the steps of: a) providing a glass fiber mat; b) providing a silica aerogel; c) impregnating the glass fiber mat with the silica aerogel; d) drying the impregnated glass fiber mat; and e) curing the impregnated glass fiber mat. In step two, the molar ratio of KH590 to tetraethyl orthosilicate TEOS in the tetraethyl orthosilicate hydrolysate is 0.1-0.3:1; the photoinitiator is type 1173 photoinitiator, and the added amount is 2% of the mass of silicon source B.

6. The method of claim 1, wherein the silica aerogel / glass fiber composite mat is prepared by the steps of: In step three, the wavelength of the ultraviolet light is 365nm.

7. The method of claim 1, wherein the silica aerogel / glass fiber composite mat is prepared by the steps of: a) providing a glass fiber mat; b) providing a silica aerogel; c) impregnating the glass fiber mat with the silica aerogel; d) drying the impregnated glass fiber mat; and e) curing the impregnated glass fiber mat. The light intensity for the click chemistry reaction described in step three is 50 mW / cm 2 for 120 min.

8. The method of claim 1, wherein the silica aerogel / glass fiber composite mat is prepared by the steps of: a) providing a glass fiber mat; b) providing a silica aerogel; c) impregnating the glass fiber mat with the silica aerogel; d) drying the impregnated glass fiber mat; and e) curing the impregnated glass fiber mat. In step four, the volume ratio of the silica wet gel-glass fiber felt composite to the siphon volume of the Soxhlet extractor is not more than 0.47:1, the water absorbing agent is silica gel, and the mass of the silica gel is 1.5-3.5 times of the mass of water in the silica wet gel-glass fiber felt composite; the volume ratio of the added ethanol to the siphon volume of the Soxhlet extractor is 1-2:1, and the volume of the added n-hexane is 4.5 times of the volume of the silica wet gel-glass fiber felt composite.

9. The method of claim 1, wherein the silica aerogel / glass fiber composite mat is prepared by the steps of: a) providing a glass fiber mat; b) providing a silica aerogel; c) impregnating the glass fiber mat with the silica aerogel; d) drying the impregnated glass fiber mat; and e) curing the impregnated glass fiber mat. In step four, the heating temperature for solvent replacement by adding ethanol is 80°C-95°C, and the heating time is 10h-12h; the heating temperature for solvent replacement by adding n-hexane is 69°C-78°C, and the heating time is 6h-12h.

10. A silica aerogel / glass fiber composite mat, characterized by, Prepared by the method of any one of claims 1-9.

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