Aerogel composite material for thermal insulation board and preparation method of aerogel composite material

Abstract

The invention discloses an aerogel composite material for a thermal insulation board and a preparation method of the aerogel composite material. Taking tetraethoxysilane as a precursor to obtain silica sol; adding a flame retardant into the silica sol for modification to obtain flame-retardant silica sol; adding the fiber and nanofiber dispersion into the flame-retardant silica sol, and uniformly mixing to obtain a prepolymer; adjusting the pH value of the prepolymer to 8-9, and sequentially carrying out gelation, aging and drying to obtain the aerogel composite material. The composite material obtained by the invention has relatively high supporting strength, and meanwhile, the flame retardant is introduced, so that the flame retardant property of the aerogel composite material is improved. The aerogel composite material is prepared by mixing silica sol and fibers with different lengths and carrying out gel aging and other operations, and the problem of easy powder falling can be avoided from the source.

Description

Technical Field

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

[0002] As a new type of nanomaterial, aerogel has a porous network skeleton structure and has good thermal insulation and fire resistance. In recent years, aerogel composite materials have become one of the most promising new insulation materials in the field of building insulation due to their excellent thermal insulation, fire resistance and high temperature stability, which can meet the requirements of thermal insulation, energy saving and fire prevention at the same time.

[0003] SiO2 aerogel is a mature aerogel material with market application. It has been widely used as a high-performance thermal insulation material. SiO2 aerogel is a three-dimensional tortuous solid network structure composed of Si-O-Si bonds between nano-gel particles. Its porosity is as high as 95%, and it has low thermal conductivity (as low as 0.012W / (m·K)), high specific surface area (up to 1600m 2 / g), low bulk density (less than 3mg / cm 3 ) and other characteristics. However, there are still certain difficulties in directly using SiO2 aerogel in the field of thermal insulation. The main reason is that the strength and modulus of SiO2 aerogel are extremely low, and in the process of drying at normal pressure, the aerogel is very easy to crack or collapse, which destroys the integrity of the aerogel. In order to expand the application range of aerogel and make nanoporous aerogel insulation materials with practical value, SiO2 aerogel needs to be flame-retardant, reinforced, and toughened. However, SiO2 aerogel has poor compatibility with flame retardants, and adding a large amount of flame retardants will affect the mechanical properties of SiO2 aerogel; in addition, SiO2 aerogel has poor adhesion to reinforcing matrix materials such as fibers, and there is a problem of easy powder loss in application. Ordinary masks cannot intercept aerogel powder, which is harmful to the body after inhalation; and it will affect its high-temperature thermal insulation effect after falling off. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an aerogel composite material for thermal insulation board materials.

[0005] Another object of the present invention is to provide an aerogel composite material for thermal insulation board material prepared by the above preparation method.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing an aerogel composite material for a thermal insulation board comprises the following steps:

[0007] (1) Mix ethanol and water, stir evenly, add tetraethyl orthosilicate dropwise while stirring, adjust the pH value of the reaction system to 2-3, stir and react at 40-50° C. for 4-5 hours to obtain silica sol;

[0008] (2) adding a flame retardant to the silica sol obtained in step (1), and continuing to stir and keep warm for 1 hour to obtain a flame retardant silica sol;

[0009] (3) adding the fiber and nanofiber dispersion to the flame retardant silica sol obtained in step (2), mixing, and obtaining a prepolymer;

[0010] (4) The pH value of the prepolymer is adjusted to 8-9, and the aerogel composite material is obtained by gelation, aging and drying in sequence.

[0011] Preferably, in step (1), the molar ratio of tetraethyl orthosilicate, ethanol and water is 1:5-30:2-20.

[0012] Preferably, the mass percentage of the flame retardant added to the silica sol in step (2) is 10-15%.

[0013] Preferably, the fiber in step (3) is one or more of polypropylene fiber, aramid fiber, carbon fiber, glass fiber and mullite fiber.

[0014] Preferably, the nanofiber dispersion in step (3) is one or more of aramid nanofiber, glass nanofiber, carbon nanofiber, silicon carbide nanofiber, mullite nanofiber, polyimide nanofiber, quartz nanofiber and zirconium oxide nanofiber.

[0015] Preferably, the mass percentage of the fibers added to the flame retardant silica sol in step (3) is 3-3.5%; the mass percentage of the nanofiber dispersion added to the flame retardant silica sol is 5.0-6.0%.

[0016] Preferably, the length of the fibers is 10-30 mm, and the length of the nanofiber dispersion is 100-500 nm.

[0017] Preferably, in step (4), the aging is carried out at 60-80° C. for 24 hours.

[0018] The present invention also provides an aerogel composite material for thermal insulation board material prepared by the preparation method.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. In this preparation method, tetraethyl orthosilicate is used as a precursor, silica sol is prepared by a sol-gel method, and then the silica sol is mixed with a flame retardant to improve the flame retardant properties of the aerogel composite material.

[0021] 2. In the present invention, the aerogel composite material is prepared by mixing silica sol with fibers of different lengths and subjecting them to operations such as gel aging, thereby avoiding the problem of easy powder loss from the source.

[0022] 3. The method of the present invention has low environmental requirements, and the entire process is simple and easy to operate, suitable for industrial production. DETAILED DESCRIPTION

[0023] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The following examples are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0024] In the following examples, the length of the fiber is 10-30 mm, and the length of the nanofiber dispersion is 100-500 nm.

[0025] In the following examples, the flame retardant is composed of ammonium polyphosphate and melamine in a mass ratio of 5:3-7.

[0026] Example 1

[0027] This embodiment provides a method for preparing an aerogel composite material for a thermal insulation board, comprising the following steps:

[0028] (1) mixing ethanol and water, stirring evenly, adding tetraethyl orthosilicate dropwise while stirring, adjusting the pH value of the reaction system to 2, stirring and reacting at 40° C. for 4 hours to obtain silica sol; wherein the molar ratio of tetraethyl orthosilicate, ethanol and water is 1:6:10;

[0029] (2) adding a flame retardant to the silica sol obtained in step (1), continuing to stir and keep warm for 1 hour to obtain a flame retardant silica sol, wherein the mass percentage of the flame retardant added to the silica sol is 10%;

[0030] (3) adding 10 mm aramid fiber and 100 nm polymerization-induced nano-aramid fiber dispersion to the flame-retardant silica sol obtained in step (2), mixing, and obtaining a prepolymer; wherein the mass percentage of aramid fiber added to the flame-retardant silica sol is 3%; the mass percentage of nano-aramid fiber dispersion added to the flame-retardant silica sol is 5%;

[0031] (4) Add ammonia water to the prepolymer obtained in step (3), adjust the pH value of the prepolymer to 8, stir for 2 minutes, pour into a container, and let it stand until gelation. After gelation is completed, keep it airtight. Place the wet gel in an oven and let it stand at 70°C for 24 hours for aging. After aging, dry it at normal pressure, place it in an oven at 160°C for 3 hours, and then cool it to room temperature in the oven to obtain a composite aerogel.

[0032] Example 2

[0033] This embodiment provides a method for preparing an aerogel composite material for a thermal insulation board, comprising the following steps:

[0034] (1) mixing ethanol and water, stirring evenly, adding tetraethyl orthosilicate dropwise while stirring, adjusting the pH value of the reaction system to 2, stirring and reacting at 40° C. for 4 hours to obtain silica sol; wherein the molar ratio of tetraethyl orthosilicate, ethanol and water is 1:20:4;

[0035] (2) adding a flame retardant to the silica sol obtained in step (1), continuing to stir and keep warm for 1 hour to obtain a flame retardant silica sol, wherein the mass percentage of the flame retardant added to the silica sol is 12%;

[0036] (3) adding 20 mm carbon fiber and 200 nm carbon nanofiber dispersion to the flame retardant silica sol obtained in step (2), mixing, and obtaining a prepolymer; wherein the mass percentage of aramid fiber added to the flame retardant silica sol is 3%; the mass percentage of nano-aramid fiber dispersion added to the flame retardant silica sol is 6%;

[0037] (4) Add ammonia water to the prepolymer obtained in step (3), adjust the pH value of the prepolymer to 8, stir for 2 minutes, pour into a container, and let it stand until gelation. After gelation is completed, keep it airtight. Place the wet gel in an oven and let it stand at 70°C for 24 hours for aging. After aging, dry it at normal pressure, place it in an oven at 160°C for 3 hours, and then cool it to room temperature in the oven to obtain a composite aerogel.

[0038] Example 3

[0039] This embodiment provides a method for preparing an aerogel composite material for a thermal insulation board, comprising the following steps:

[0040] (1) mixing ethanol and water, stirring evenly, adding tetraethyl orthosilicate dropwise while stirring, adjusting the pH value of the reaction system to 2, stirring and reacting at 40° C. for 4 hours to obtain silica sol; wherein the molar ratio of tetraethyl orthosilicate, ethanol and water is 1:10:5;

[0041] (2) adding a flame retardant to the silica sol obtained in step (1), continuing to stir and keep warm for 1 hour to obtain a flame retardant silica sol, wherein the mass percentage of the flame retardant added to the silica sol is 15%;

[0042] (3) adding 30 mm aramid fiber and 400 nm polymerization-induced nano-aramid fiber dispersion to the flame-retardant silica sol obtained in step (2), mixing, and obtaining a prepolymer; wherein the mass percentage of aramid fiber added to the flame-retardant silica sol is 3.5%; the mass percentage of nano-aramid fiber dispersion added to the flame-retardant silica sol is 6%;

[0043] (4) Add ammonia water to the prepolymer obtained in step (3), adjust the pH value of the prepolymer to 8, stir for 2 minutes, pour into a container, and let it stand until gelation. After gelation is completed, keep it airtight. Place the wet gel in an oven and let it stand at 70°C for 24 hours for aging. After aging, dry it at normal pressure, place it in an oven at 160°C for 3 hours, and then cool it to room temperature in the oven to obtain a composite aerogel.

[0044] Comparative Example 1

[0045] Compared with Example 2, this comparative example does not add flame retardant, and the other raw materials and preparation process remain the same as those of Example 2.

[0046] Comparative Example 2

[0047] Compared with Example 2, in this comparative example, the fiber felt is impregnated in the flame-retardant silica sol, and after the impregnation, it is aged at 70° C. for 24 hours; after aging, it is dried at normal pressure.

[0048] Performance tests were performed on Examples 1 to 4 and Comparative Examples 1 to 2;

[0049] Table 1

[0050]

[0051]

[0052] It can be seen from Table 1 that, according to the comparison results of Example 2 and Comparative Example 1, the flame retardant properties of the composite material can be effectively improved by adding a flame retardant during the preparation process. According to the comparison results of Example 2 and Comparative Example 2, the mechanical properties of the silica aerogel can be effectively improved by adding composite nanofibers and fibers of different lengths and contents before the gelation of the silica sol.

[0053] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing an aerogel composite material for thermal insulation board, characterized in that: The following steps are involved: (1) Mix ethanol and water, stir evenly, add tetraethyl orthosilicate dropwise while stirring, adjust the pH value of the reaction system to 2-3, stir and react at 40-50° C. for 4-5 hours to obtain silica sol; (2) adding a flame retardant to the silica sol obtained in step (1), and continuing to stir and keep warm for 1 hour to obtain a flame retardant silica sol; (3) adding the fiber and nanofiber dispersion to the flame retardant silica sol obtained in step (2), mixing, and obtaining a prepolymer; (4) The pH value of the prepolymer is adjusted to 8-9, and the aerogel composite material is obtained by gelation, aging and drying in sequence.

2. The method for preparing an aerogel composite material for thermal insulation board according to claim 1, characterized in that: In step (1), the molar ratio of ethyl orthosilicate, ethanol and water is 1:5-30:2-20.

3. The method for preparing an aerogel composite material for thermal insulation board according to claim 1, characterized in that: The mass percentage of the flame retardant added to the silica sol in step (2) is 10-15%.

4. The method for preparing an aerogel composite material for thermal insulation board material according to claim 1, characterized in that: The fiber in step (3) is one or more of polypropylene fiber, aramid fiber, carbon fiber, glass fiber and mullite fiber.

5. The method for preparing an aerogel composite material for thermal insulation board according to claim 1, characterized in that: The nanofiber dispersion in step (3) is one or more of aramid nanofiber, glass nanofiber, carbon nanofiber, silicon carbide nanofiber, mullite nanofiber, polyimide nanofiber, quartz nanofiber and zirconium oxide nanofiber.

6. The method for preparing an aerogel composite material for thermal insulation board material according to claim 1, characterized in that: The mass percentage of the fibers added to the flame retardant silica sol in step (3) is 3-3.5%; the mass percentage of the nanofiber dispersion added to the flame retardant silica sol is 5.0-6.0%.

7. The method for preparing an aerogel composite material for thermal insulation board material according to claim 1, characterized in that: The length of the fiber is 10-30 mm, and the length of the nanofiber dispersion is 100-500 nm.

8. The method for preparing an aerogel composite material for thermal insulation board material according to claim 1, characterized in that: In step (4), the aging is carried out at 60-80° C. for 24 hours.

9. Aerogel composite material for thermal insulation board material obtained by the preparation method according to any one of claims 1 to 8.

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