Aerogel blanket and method of making same

Abstract

The application relates to the field of thermal insulation materials, in particular to an aerogel felt and a preparation method thereof, which comprises the following steps: S1, mixing modified fibers with a length of 5-13 cm, aerogel powder and a light shielding agent to obtain composite fibers; S2, carding the composite fibers into a net, and pre-needling to form a thin net tire; and S3, stacking the thin net tire and needling to form an aerogel felt. The preparation method of the aerogel felt is simple in steps, low in cost, high in production efficiency and suitable for continuous production. Through modification of the fibers, the binding force between the aerogel, the light shielding agent and the fibers can be enhanced, so that the aerogel felt powder drop rate is effectively reduced, and the thermal insulation performance and service life of the aerogel felt are guaranteed. The aerogel felt prepared by the preparation method has good thermal insulation performance and small density.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials, and in particular to an aerogel felt and its preparation method. Background Technology

[0002] Aerogel is a nanoscale porous solid material formed by replacing the liquid phase in a gel with gas through a sol-gel method and a specific drying process. It possesses advantages such as extremely low density, high specific surface area, and high porosity, making it widely used as a thermal insulation material in various fields. However, pure aerogel suffers from low strength; therefore, the industry typically uses fiber materials combined with aerogel to form aerogel felts to meet application requirements.

[0003] Traditional aerogel felt preparation mainly employs an in-situ composite method, where the aerogel precursor undergoes a series of steps including sol-gel reaction, solution fractionation and replacement, surface modification, and drying to generate aerogel in situ within the fiber felt. This method requires sophisticated equipment and involves complex processes, resulting in low aerogel yields and high production costs. This limits its ability to achieve continuous production and its widespread application in the broader civilian sector. Summary of the Invention

[0004] To address the shortcomings of the complex in-situ composite method, this invention provides a method for preparing aerogel mats, comprising the following steps:

[0005] S1. Modified fibers with a length of 5-13 cm are mixed with aerogel powder and a light-blocking agent to obtain composite fibers;

[0006] S2. The composite fibers are combed into a web and pre-needled to form a thin web;

[0007] S3. The thin mesh is stacked and then needle-punched and shaped by pressure roller to obtain aerogel felt.

[0008] Furthermore, in step S1, the method for preparing the modified fiber is as follows: first, the fiber is pretreated, the modifier is dissolved in a solvent to form a modifier solution, and then the pretreated fiber and the modifier solution are stirred at 25-100°C for 5-30 minutes to obtain mixture A, and then dried to obtain the modified fiber; the pretreatment is heat treatment.

[0009] The pretreatment is a heat treatment, with a temperature of 150–450°C and a treatment time of 10–120 min.

[0010] Furthermore, the drying process is carried out using hot rollers, hot air, infrared radiation, or hot plates.

[0011] Furthermore, the mass ratio of the modifier to the fiber is (0.1-0.3):1.

[0012] Furthermore, the modifier is a mixture of γ-methacryloyloxypropyltrimethoxysilane and polyvinyl alcohol, and the molar ratio of the two is (0.5-1.2):1;

[0013] Furthermore, the solvent is ethanol and / or water;

[0014] Furthermore, the fibers are organic fibers and / or inorganic fibers. It is understood that organic fibers include, but are not limited to: ultra-high molecular weight polyethylene fibers, polypropylene fibers, polyamide fibers, polyetherimide fibers, polyacrylonitrile fibers, PET fibers, cotton fibers, hemp fibers, soybean fibers, and bamboo fibers; inorganic fibers include, but are not limited to: carbon fibers, basalt fibers, glass fibers, ceramic fibers, alumina fibers, high-silica fibers, magnesium oxide fibers, and silicon carbide fibers.

[0015] When the fiber is an inorganic fiber, the pretreatment of the fiber also includes etching with acid or alkali. Specifically, the fiber is soaked in an acidic or alkaline solution with a concentration of 0.01 to 1 mol / L at a temperature of 25 to 100°C for 0.5 to 7 hours, and then rinsed with distilled water. The acidic solution is hydrochloric acid or sulfuric acid solution, and the alkaline solution is sodium hydroxide solution.

[0016] By pretreatment, organic fibers are exposed to hydroxyl groups, and inorganic fibers are attached to the surface of hydroxyl groups. This ensures that the silicon-oxygen bonds in the modifier can react with the hydroxyl groups to form "silicon-oxygen-silicon" bonds, thereby achieving fiber surface modification.

[0017] The modifier is a mixture of γ-methacryloxypropyltrimethoxysilane and polyvinyl alcohol. γ-methacryloxypropyltrimethoxysilane and polyvinyl alcohol undergo a copolymerization reaction, providing excellent adhesion and durability.

[0018] Before modifying the fiber, the preferred method also includes opening the fiber, specifically: taking the fiber filament cake and cutting it to obtain short-cut fibers with a length of 5 to 13 cm, and then opening it through an opening machine.

[0019] Furthermore, the diameter of the fiber is 4–13 μm.

[0020] Furthermore, the aerogel powder is one or more of SiO2 aerogel powder, Al2O3 aerogel powder, TiO2 aerogel powder, ZrO aerogel powder, SiC aerogel powder, and carbon aerogel powder.

[0021] Furthermore, the light-blocking agent is one or more of TiO2, SiC, BN, ZrSO4, K2Ti6O3, Fe3O4, carbon black, and graphite.

[0022] Furthermore, the particle size of the aerogel powder and the opacifier is 10–80 μm.

[0023] Furthermore, in step S1, the mass ratio of the modified fiber, aerogel powder, and opacifier is (50-90):(5-35):(0.1-5).

[0024] Furthermore, in step S2, the areal density of the thin mesh tire is 30–200 g / m². 2 .

[0025] Furthermore, between steps S2 and S3, step S21 is also included: uniformly sprinkling aerogel powder and / or opacifier on the surface and inside of the thin mesh.

[0026] Preferably, the aerogel powder and opacifier are applied by spraying the aerogel powder and opacifier onto the top of the thin mesh fabric using an electrostatic powder spray gun, and then drawing the aerogel powder and opacifier from the top into the thin mesh fabric through negative pressure suction at the bottom of the thin mesh fabric.

[0027] Preferably, the amount of aerogel powder used is 0.5% to 35% of the mass of the modified fiber, and the amount of light-blocking agent used is 0.1% to 15% of the mass of the modified fiber.

[0028] Using an electrostatic spray gun to spray aerogel powder and / or opacifier, the electrostatic spray gun imparts an effective and sufficient negative charge to the powder particles, ensuring that the powder has an adsorption force on the fibers and reducing powder loss during the spraying process.

[0029] By sprinkling aerogel powder and / or light-blocking agent on the surface and inside of the thin mesh, the aerogel powder and / or light-blocking agent fill the gaps in the thin mesh, thereby improving the thermal insulation performance of the aerogel felt.

[0030] Preferably, in step S2, the combing and web forming process uses a single-layer or double-layer web laying method;

[0031] In step S3, the thin mesh tire has 2 to 30 layers, and the thickness of each layer is 1 to 10 mm.

[0032] In step S3, the acupuncture includes pre-puncture, main puncture, and compound acupuncture.

[0033] In step S3, the pressure roller is shaped using a hot pressure roller with a heating temperature of 10 to 500°C.

[0034] The present invention also provides an aerogel felt, which is prepared by the above-described preparation method.

[0035] Compared with the prior art, the preparation method of aerogel felt provided by the present invention is simple, low-cost, and highly efficient, and is suitable for continuous production. By modifying the fibers, the bonding force between the aerogel and the light-blocking agent and the fibers can be enhanced, thereby effectively reducing the powder shedding rate of the aerogel felt and ensuring the thermal insulation performance and service life of the aerogel felt. The aerogel felt prepared by this method has good thermal insulation performance and low density. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This invention provides a method for preparing aerogel mat, comprising the following steps:

[0038] S1. Modified fibers with a length of 5-13 cm are mixed with aerogel powder and a light-blocking agent to obtain composite fibers;

[0039] S2. The composite fibers are carded into a web and pre-needled to form a thin web;

[0040] S3. After stacking the thin mesh, needle punch it into shape, and then press it with a roller to shape it, thus obtaining aerogel felt.

[0041] In step S1, the modified fiber is prepared by: first pretreating the fiber, dissolving the modifier in a solvent to form a modifier solution, then stirring the pretreated fiber and the modifier solution at 25-100°C for 5-30 minutes to obtain mixture A, and drying to obtain the modified fiber;

[0042] The mass ratio of modifier to fiber is (0.1–0.3):1;

[0043] The modifier is a mixture of γ-methacryloxypropyltrimethoxysilane and polyvinyl alcohol, and the molar ratio of the two is (0.5-1.2):1;

[0044] The solvent is ethanol and / or water;

[0045] The fiber is an organic fiber and / or an inorganic fiber;

[0046] The diameter of the fiber is 4–13 μm;

[0047] The aerogel powder is one or more of SiO2 aerogel powder, Al2O3 aerogel powder, TiO2 aerogel powder, ZrO aerogel powder, SiC aerogel powder, and carbon aerogel powder;

[0048] The light-blocking agent is one or more of TiO2, SiC, BN, ZrSO4, K2Ti6O3, Fe3O4, carbon black, and graphite;

[0049] The particle size of the aerogel powder and the light-blocking agent is 10-80 μm;

[0050] In step S1, the mass ratio of the modified fiber, aerogel powder, and opacifier is (50-90):(5-35):(0.1-5);

[0051] In step S2, the areal density of the thin mesh tire is 30-200 g / m². 2 ;

[0052] Between steps S2 and S3, there is also step S21, which involves uniformly sprinkling aerogel powder and / or opacifier on the surface and inside of the thin mesh tire.

[0053] In step S21, the aerogel powder and opacifier are applied by spraying aerogel powder and opacifier onto the top of the thin mesh fabric using an electrostatic powder spray gun, and then drawing the aerogel powder and opacifier from the top into the thin mesh fabric through negative pressure suction at the bottom.

[0054] In step S3, the pressure roller is shaped using a hot pressure roller with a heating temperature of 10 to 500°C.

[0055] The present invention also provides an aerogel felt, which is prepared by the above-described preparation method.

[0056] The present invention provides the following embodiments and comparative examples:

[0057] Example 1

[0058] A method for preparing an aerogel mat includes the following steps:

[0059] S1. Modified fibers with a length of 8 cm and a diameter of 8 μm are mixed with silica aerogel powder and titanium dioxide to obtain composite fibers, wherein the mass ratio of modified fibers to silica aerogel powder and titanium dioxide is 70:25:5.

[0060] S2. The composite fibers are carded into a web and pre-needled to form an areal density of 160 g / m². 2 Thin mesh tires;

[0061] S3. After stacking eight layers of thin mesh, the material is needle-punched and then pressed and shaped by rollers to obtain aerogel felt.

[0062] Example 2

[0063] A method for preparing an aerogel mat includes the following steps:

[0064] S1. Modified fibers with a length of 5 cm and a diameter of 4 μm are mixed with silica aerogel powder and silicon carbide to obtain composite fibers, wherein the mass ratio of modified fibers to silica and silicon carbide is 65:34.9:0.1.

[0065] S2. The composite fibers are carded into a web and pre-needled to form an areal density of 30 g / m². 2 Thin mesh tires;

[0066] S21. Silica aerogel powder and silicon carbide are evenly sprinkled on the surface and inside of the thin mesh, wherein the amount of silica aerogel powder is 5% of the mass of the modified fiber and the amount of silicon carbide is 1% of the mass of the modified fiber.

[0067] S3. After stacking eight layers of thin mesh, the material is needle-punched and then pressed and shaped by rollers to obtain aerogel felt.

[0068] Example 3

[0069] A method for preparing an aerogel mat includes the following steps:

[0070] S1. Modified fibers with a length of 13cm and a diameter of 13μm are mixed with silicon dioxide and silicon carbide to obtain composite fibers, wherein the mass ratio of modified fibers to silicon dioxide and silicon carbide is 75:21:4.

[0071] S2. The composite fibers are carded into a web and pre-needled to form an areal density of 200 g / m². 2 Thin mesh tires;

[0072] S21. Silica aerogel powder and silicon carbide are evenly sprinkled on the surface and inside of the thin mesh, wherein the amount of silica aerogel powder is 2.5% of the mass of the modified fiber and the amount of silicon carbide is 0.5% of the mass of the modified fiber.

[0073] S3. After stacking eight layers of thin mesh, the material is needle-punched and then pressed and shaped by rollers to obtain aerogel felt.

[0074] The modified fibers in Examples 1-3 are prepared as follows: the modifier is dissolved in ethanol to form a modifier solution, and the glass fiber and the modifier solution are stirred at 45°C for 10 minutes to obtain mixture A, which is then dried to obtain the modified fibers; wherein the modifier is a mixture of γ-methacryloyloxypropyltrimethoxysilane and polyvinyl alcohol, and the molar ratio of the two is 1:1, and the mass ratio of the modifier to the glass fiber is 0.2:1;

[0075] In Examples 1-3, the particle size of the aerogel powder and the opacifier is 10-80 μm;

[0076] In Examples 1-3, before modifying the fiber, the fiber is opened, specifically: the fiber filament cake is cut and then opened by an opening machine;

[0077] In Examples 2-3, the method of applying aerogel powder and opacifier in step S21 is as follows: aerogel powder and opacifier are sprayed onto the top of the thin mesh fabric using an electrostatic powder spray gun, and the aerogel powder and opacifier at the top are drawn into the thin mesh fabric by negative pressure suction at the bottom of the thin mesh fabric.

[0078] In Examples 1-3, the pressure roller in step S3 is shaped into a hot pressure roller, and the heating temperature is 200℃.

[0079] Comparative Example 1

[0080] The difference from Example 1 is that the length of the modified fiber is 15 cm, while everything else is the same as in Example 1.

[0081] Comparative Example 2

[0082] Unlike Example 1, the areal density of the thin mesh tire is 20 g / m². 2 Everything else is the same as in Example 1.

[0083] Comparative Example 3

[0084] Unlike Example 1, the areal density of the thin mesh tire is 210 g / m². 2 Everything else is the same as in Example 1.

[0085] Comparative Example 4

[0086] The difference from Example 2 is that the modified fiber is replaced with glass fiber, that is, the modification step of glass fiber is not included, and the rest is the same as Example 2.

[0087] Comparative Example 5

[0088] Unlike Example 2, the particle size of the aerogel powder and the opacifier is 800-1000 μm.

[0089] Comparative Example 6

[0090] Unlike Example 2, the modifier is γ-methacryloyloxypropyltrimethoxysilane.

[0091] Comparative Example 7

[0092] Unlike Example 2, the modifier is polyvinyl alcohol.

[0093] Comparative Example 8

[0094] Unlike Example 2, in step S21, the aerogel powder and opacifier are applied by using a powder applicator to sprinkle the aerogel powder and opacifier onto the thin mesh fabric.

[0095] Comparative Example 9

[0096] Unlike Example 2, step S3 does not include pressure roller shaping.

[0097] The thermal conductivity and vibration mass loss rate of the aerogel felts prepared in the test examples and comparative examples were investigated. The thermal conductivity was measured using a thermal conductivity meter and the heat flow meter method, with the temperature difference between the cold and hot plates not exceeding 30°C. The vibration mass loss rate was measured using a standard motor-driven vibrating screen for 60 minutes (vibration frequency: 1400 times / min, amplitude: 3 mm). The experimental results are shown in Table 1.

[0098] Table 1

[0099]

[0100]

[0101] As can be seen from the test data of Examples 1-3 in Table 1, the aerogel felt provided by the present invention has good thermal insulation performance and low powder shedding rate. By adding aerogel and light-blocking agent to the surface and interior of the thin mesh, the thermal conductivity of the sample can be further reduced, but at the same time, the vibration loss rate will increase. Although the vibration loss rate of the sample has increased, it is clearly within the national standard range (less than or equal to 1%).

[0102] The aerogel felt prepared in Comparative Example 1 has excessively long fibers, which leads to insufficient adhesion between layers during the molding process. It is more prone to delamination than other samples and is not suitable for practical use.

[0103] In Comparative Example 2, the aerogel felt sample was porous due to the low density of the thin mesh surface during the preparation process, which in turn resulted in an excessively high thermal conductivity.

[0104] Comparative Example 3 had an excessively high density of thin mesh tread during the preparation process, which made it more prone to needle breakage during the needle punching process in the molding stage compared to other samples, and the thermal conductivity of the resulting aerogel felt was also too high.

[0105] Comparative Example 4 was prepared by directly mixing the fiber with aerogel powder without modifying the fiber during the preparation process. As a result, there were not enough functional groups on the fiber to bind with the aerogel powder, and the mixture was only a physical mixture. During the preparation of the finished product, there will be a large loss of aerogel powder, and the thermal conductivity of the resulting sample will also be higher. Similarly, because the fiber and aerogel powder are not firmly bonded, the vibration loss rate of the sample will also be high during the vibration loss rate test, exceeding the national standard.

[0106] The test results of Comparative Example 5 show that when the particle size of aerogel powder and opacifier is too large, the adhesion efficiency of the powder to the fiber will decrease, thereby increasing the vibration loss rate of the sample.

[0107] In Comparative Example 6, the modifier used was only γ-methacryloxypropyltrimethoxysilane, without polyvinyl alcohol undergoing copolymerization with it. Its adhesive force was provided solely by γ-methacryloxypropyltrimethoxysilane as a coupling agent, resulting in an increased vibration loss rate in this sample.

[0108] In Comparative Example 7, the modifier used was only polyvinyl alcohol, and its adhesive force was provided solely by the hydrogen bond interaction between polyvinyl alcohol and the hydroxyl groups in the fiber. Therefore, the vibration loss rate of the sample increased. This shows that γ-methacryloyloxypropyltrimethoxysilane and polyvinyl alcohol are both indispensable in the modifier.

[0109] As can be seen from the test results of Comparative Example 8, since no negative charge is added to the powder particles during the powder spraying process, the powder does not generate an adsorption force on the fiber due to the negative voltage. In addition to powder loss during the sample preparation process, the vibration loss rate of the prepared sample will also increase.

[0110] In Comparative Example 9, since the pressure roller process was not used for shaping, the finished product had an uneven surface compared to other samples. The product layers were not tightly bonded, and the thickness was increased. Due to the looseness of the sample, the thermal conductivity of the sample was higher, and the vibration loss rate of the finished product was also higher.

[0111] It should be noted that the specific parameters or some commonly used reagents in the above embodiments are specific or preferred embodiments under the concept of the present invention, and not limitations thereof; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

[0112] In addition, unless otherwise specified, the raw materials used may be commercially available products in the field or prepared by conventional methods in the field.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an aerogel felt, characterized in that, Includes the following steps: S1. Modified fibers with a length of 5-13 cm are mixed with aerogel powder and a light-blocking agent to obtain composite fibers; S2. The composite fibers are combed into a web and pre-needled to form a thin web; S3. The thin mesh tires are stacked and then needle-punched and shaped by pressure rollers to obtain aerogel felt; In step S1, the modified fiber is prepared by: first pretreating the fiber, dissolving the modifier in a solvent to form a modifier solution, then stirring the pretreated fiber and the modifier solution at 25-100°C for 5-30 minutes to obtain mixture A, and drying to obtain the modified fiber; the pretreatment is heat treatment; the modifier is a mixture of γ-methacryloyloxypropyltrimethoxysilane and polyvinyl alcohol, and the molar ratio of the two is (0.5-1.2):

1.

2. The method for preparing aerogel felt according to claim 1, characterized in that: The mass ratio of the modifier to the fiber is (0.1–0.3):1; And / or, the diameter of the fiber is 4 to 13 μm.

3. The method for preparing aerogel felt according to claim 1, characterized in that: The solvent is ethanol and / or water; And / or, the fiber is an organic fiber and / or an inorganic fiber, and when the fiber is an inorganic fiber, the pretreatment of the fiber also includes etching with acid or alkali.

4. The method for preparing aerogel felt according to claim 1, characterized in that: The aerogel powder is one or more of SiO2 aerogel powder, Al2O3 aerogel powder, TiO2 aerogel powder, ZrO2 aerogel powder, SiC aerogel powder, and carbon aerogel powder; And / or, the light-blocking agent is TiO2, SiC, BN, Zr(SO4)2, K2Ti6O 13 One or more of Fe3O4, carbon black, and graphite.

5. The method for preparing aerogel felt according to claim 1, characterized in that: In step S1, the mass ratio of the modified fiber, aerogel powder, and opaque agent is (50-90):(5-35):(0.1-5).

6. The method for preparing aerogel felt according to claim 1, characterized in that: In step S2, the areal density of the thin mesh tire is 30-200 g / m². 2 .

7. The method for preparing aerogel felt according to claim 1, characterized in that: Between steps S2 and S3, there is also step S21, where aerogel powder and opaque agent are evenly sprinkled on the surface and inside of the thin mesh tire; The aerogel powder and opacifier are applied by spraying the aerogel powder and opacifier onto the top of the thin mesh fabric using an electrostatic powder spray gun, and then drawing the aerogel powder and opacifier from the top into the thin mesh fabric through negative pressure suction at the bottom of the thin mesh fabric.

8. The method for preparing aerogel felt according to claim 1, characterized in that: In step S3, the pressure roller is shaped using a hot pressure roller with a heating temperature of 10 to 500°C.

9. An aerogel felt, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

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