A method for preparing a three-dimensional fiber fabric-silica aerogel composite material

Abstract

The application provides a preparation method of a three-dimensional fiber fabric-silica aerogel composite material, which comprises the following steps: mixing tetraethyl orthosilicate, ethanol, water and hydrochloric acid as a precursor, and dropping an alkaline catalyst to prepare a silica sol; placing a three-dimensional glass long fiber fabric obtained by braiding glass fibers in a mold, injecting the prepared silica sol into the three-dimensional glass long fiber fabric, and stopping until the liquid surface of the silica sol is parallel to or slightly lower than the upper surface of the three-dimensional glass long fiber fabric, so that the three-dimensional glass long fiber fabric is filled with the silica sol; placing the three-dimensional glass long fiber fabric filled with the silica sol to obtain a fabric composite material gel, adding ethanol into the mold for solvent replacement, and obtaining the three-dimensional fiber fabric-silica aerogel composite material after supercritical drying. The preparation method is simple, does not need complicated steps and materials, and the obtained three-dimensional fiber fabric-silica aerogel composite material has better heat insulation performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aerogel preparation, and particularly relates to a preparation method of a three-dimensional fiber fabric-silica aerogel composite material. BACKGROUND

[0002] The rapid development of high-end equipment manufacturing represented by transportation has a huge demand for interior structure, heat insulation, flame-retardant and heat-insulating composite materials.

[0003] With the development of science and technology, various new thermal insulation materials emerge in an endless stream. Glass fiber is a high-performance inorganic material with excellent mechanical properties, corrosion resistance, high temperature resistance and good insulation. It is usually used as a reinforcing material in composite materials. The three-dimensional glass fiber fabric is a heat-insulating material made of a three-dimensional fabric structure, which combines the high temperature resistance and excellent heat-insulating performance of glass fiber, increases the voids and bulkiness between fibers, and further improves the heat-insulating performance. It is widely used in building insulation, high-temperature equipment insulation, thermal industrial equipment insulation, aerospace, automobile and train insulation and other fields.

[0004] On the other hand, common fiber-resin composite materials have the advantages of high strength, lightweight, one-piece molding and the like. However, the thermal conductivity of the composite material is still high, and it is still difficult to meet the thermal insulation requirements in some places. Other glass fiber composite materials may contain various organic materials, which can cause flammability and fire. At present, researchers generally add flame retardants to glass fiber composite materials to improve the flame retardant performance of glass fiber reinforced composite materials. For example, a Chinese patent with the application number 201310251615.7 and the name "antistatic flame-retardant glass fiber plastic" discloses an antistatic flame-retardant glass fiber plastic, which improves the flame-retardant performance of the glass fiber plastic by adding a halogen-free flame retardant in the material. However, there are very few studies on directly improving the structure of glass fiber by compounding inorganic thermal insulation materials, and then improving the flame-retardant performance of glass fiber reinforced composite materials.

[0005] Aerogel is a material that has excellent insulation, heat insulation and flame retardant effects at the same time, and has a special pore size structure. As a thermal insulation material, it also has good compression performance and can be used as a buffer material between the battery cells to adapt to the expansion and contraction changes of the battery cells during charging and discharging. Due to its extremely low volume energy density, it is widely used in high-end technical fields such as aerospace and military industry. With its outstanding thermal insulation performance and the realization of industrialization in China, it has gradually entered the civilian market. In addition to power batteries, aerogel can also be applied to the overall structure of the automobile, such as the roof, door frame, engine cover, etc., which can play a role in heat preservation and energy saving and emission reduction in the vehicle cabin, and the space occupied by aerogel in the vehicle can be greatly reduced compared to ordinary materials.

[0006] Silica aerogel, as a kind of lightweight nano-porous material with excellent fireproof and thermal insulation performance, is the most mature product in production technology and commercial application at present. The two materials of three-dimensional glass fiber fabric and silica aerogel are compounded, and the silica aerogel is embedded in the three-dimensional fiber fabric, so that the thermal insulation performance and other characteristics of the material itself can be improved. With the continuous growth of raw material production capacity and the help of cost reduction measures, the three-dimensional fiber fabric-silica aerogel composite material is expected to accelerate the replacement of traditional thermal insulation materials due to its excellent performance and light structure, and is expected to be applied to more fields. SUMMARY

[0007] In order to solve the problems in the prior art, the application provides a preparation method of a three-dimensional fiber fabric-silica aerogel composite material, which can guarantee the high-temperature resistance, thermal insulation performance and flame retardant performance of the glass fiber composite material when the heat is too large, improve the thermal insulation performance of the glass fiber material, and reduce the damage of the thermal environment to the glass fiber composite material itself.

[0008] The technical problem of the application is solved by adopting the following technical scheme:

[0009] The application aims to provide a preparation method of a three-dimensional fiber fabric-silica aerogel composite material, which is characterized by comprising the following steps:

[0010] Mixing tetraethyl orthosilicate, ethanol, water and hydrochloric acid as a precursor, and dropping an alkaline catalyst to prepare silica sol;

[0011] The three-dimensional glass long fiber fabric obtained by weaving glass fibers is placed flat in a mold, the prepared silica sol is injected into the three-dimensional glass long fiber fabric, until the liquid surface of the silica sol is parallel or slightly lower than the upper surface of the three-dimensional glass long fiber fabric, so that the three-dimensional glass long fiber fabric is filled with silica sol;

[0012] The three-dimensional glass long fiber fabric filled with silica sol is placed to obtain a fabric composite gel, ethanol is added to the mold for solvent replacement, and a three-dimensional fiber fabric-silica aerogel composite material is obtained after supercritical drying.

[0013] Further, the molar ratio of the tetraethyl orthosilicate, ethanol, water and hydrochloric acid is 1:(20-30):(4-5):10 -4 .

[0014] Further, the alkaline catalyst is ammonia water.

[0015] Further, the molar ratio of the tetraethyl orthosilicate and the alkaline catalyst is 1:0.05-0.25.

[0016] Further, the three-dimensional glass long fiber fabric is obtained by mechanically weaving the glass fiber continuous raw filaments or long fiber raw filaments.

[0017] Further, the stitching needle distance is 1-1.5 mm, the thickness of the three-dimensional glass long fiber fabric is 4-15 m, and the stitching line distance is 1-10 mm during weaving.

[0018] Further, before standing, the three-dimensional glass long fiber fabric injected with the silica sol is subjected to pressure in the thickness direction.

[0019] Further, the pressure applied is 0-0.1 MPa.

[0020] Further, the standing aging time is 24-48 h, and the temperature is room temperature. Preferably, the standing aging time is 24 h, and the temperature is 26 DEG C.

[0021] Further, the solvent replacement time is 12-24 h. Preferably, the solvent replacement time is 12 h.

[0022] Further, the supercritical drying conditions are as follows: ethanol is selected as the supercritical drying medium, the drying temperature is 260-270 DEG C, the holding time is 2-4 h, and the pressure is 8-12 MPa.

[0023] Compared with the prior art, the beneficial technical effects of the present application are as follows:

[0024] The preparation method of the present application is simple, does not require complicated steps and materials, and the obtained three-dimensional fiber fabric-silica aerogel composite material has better heat insulation performance. The preparation method of the present application is helpful to increase the high-temperature stability of the three-dimensional glass fiber woven product by compounding silica aerogel in the three-dimensional fiber woven product, not only improves the use strength and temperature, but also the method process is simple, the equipment requirement is low, improves the production efficiency of the composite material, and is beneficial to large-scale production. The obtained three-dimensional fiber fabric-silica aerogel composite material not only improves the use strength and temperature of the material, but also the obtained composite material aerogel has low density, and is a kind of heat conduction coefficient extremely low heat insulation material which can be applied to high-temperature field.

[0025] In the sol-gel process, the present application ensures the uniform dispersion of the sol by applying simple physical pressure, increases the bonding force between the fiber and the sol, and avoids the problem that the gel composite material is split before drying due to the tension of the fiber itself.

[0026] The present application has the advantages of simple process, low cost, controllable reaction conditions, preparation of different three-dimensional fiber fabric-silica aerogel composite materials by selecting different material proportions of sol precursors and parameters of three-dimensional fiber fabric, adaptability to mold preparation requirements, and complete satisfaction of the usability of special-shaped product in the heat insulation field by controlling the appropriate magnification of the mold.

[0027] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, and to be implemented in accordance with the content of the specification, and in order to make the above content and purposes, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described below. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a schematic diagram of the three-dimensional fiber fabric and various parameters in the preparation method of the three-dimensional fiber fabric-silica aerogel composite material of the present application.

[0029] Figure 2 It is a photo before and after supercritical drying in the preparation method of the three-dimensional fiber fabric-silica aerogel composite material of the present application.

[0030] Figure 3 It is a thermal insulation test diagram of the material of Example 1 (SA-Fibers) and Comparative Example 1 (Fibers) in the preparation method of the three-dimensional fiber fabric-silica aerogel composite material of the present application.

[0031] Figure 4 It is a photo before and after thermal insulation of the material of Example 2 and Comparative Example 1 in the preparation method of the three-dimensional fiber fabric-silica aerogel composite material of the present application. DETAILED DESCRIPTION

[0032] The technical scheme of the present application will be further described in detail below in combination with the drawings and specific examples. It should be understood that the following examples are only illustrative and explanatory of the present application, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above content of the present application is covered within the scope intended to be protected by the present application.

[0033] In addition, unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or prepared by existing methods.

[0034] Example 1:

[0035] A preparation method of a three-dimensional fiber fabric-silica aerogel composite material, the steps are as follows:

[0036] (1) Tetraethyl orthosilicate, anhydrous ethanol, deionized water, hydrochloric acid (mass fraction of 0.05wt%) are mixed in a molar ratio of 1:25:4:10 -4 Stir at room temperature until uniform, then seal and stand at room temperature after stirring, obtain silica sol precursor; drop in ammonia-ethanol diluent (tetraethyl orthosilicate: ammonia water = 1:0.05), stir uniformly to obtain silica sol.

[0037] (2) Using glass fiber, selecting the stitching needle distance of 1 mm, the fiber felt thickness of 4 m, the stitching row distance of 5 mm, and producing by mechanical weaving process to obtain the three-dimensional fiber fabric (as shown in FIG. 1), cutting the three-dimensional fiber fabric into a square of about 4.5 cm long and about 4.5 cm wide according to the mold, trimming the uneven fibers at the edges, and then laying the three-dimensional fiber fabric in the mold; Figure 1

[0038] (3) Slowly injecting the prepared silica sol into the laid three-dimensional fiber fabric to fill the gaps in the three-dimensional fiber fabric with silica sol, and the height of the sol surface is parallel to the upper surface of the three-dimensional fiber fabric. A 4.5*4.5 cm flat plate is applied to the surface, a fixed pressure is applied to the flat plate, and the gel composite material is obtained by sol-gel through standing;

[0039] (4) Aging the above three-dimensional fiber fabric-silica aerogel composite material at room temperature for 24 h, and replacing the solvent with ethanol for 1-2 times.

[0040] (5) Placing it in a high-pressure reaction kettle for supercritical drying, using ethanol as the medium for supercritical drying, controlling the ethanol pressure at 8-10 MPa, controlling the temperature at 270°C, and supercritical drying for 2 h to obtain the three-dimensional fiber fabric-silica aerogel composite material.

[0041] Examples 2-6:

[0042] The preparation process of Examples 2-6 is the same as that of Example 1, and the difference from Example 1 is that the stitching needle distance, the stitching row distance, and the fiber felt thickness are different. The stitching needle distance, the stitching row distance, and the fiber felt thickness of Examples 1-6 are shown in Table 1.

[0043] Table 1: Parameters of three-dimensional fiber fabric of each example

[0044] Stitch needle distance (mm) Felt thickness (m) Stitch row distance (mm) Example 1 1 4 5 Example 2 1 5 5 Example 3 1 6 5 Example 4 1 8 5 Example 5 1 15 1 Example 6 1.5 10 10

[0045] Example 7:

[0046] The difference from Example 1 is that the molar ratio of tetraethyl orthosilicate, anhydrous ethanol, and deionized water in the silica sol precursor of Example 1 is adjusted to 1:30:5.

[0047] Example 8:

[0048] The difference from Example 7 is that the thickness of the fiber felt is adjusted to 5 m.

[0049] Example 9:

[0050] The difference from Example 7 is that the thickness of the fiber felt is adjusted to 6 m.

[0051] Example 10:​

[0052] The difference from Example 7 is that the thickness of the fiber felt is adjusted to 8m.

[0053] Example 11:

[0054] The difference from Example 7 is that the thickness of the fiber felt is adjusted to 15m, and the stitching row spacing is adjusted to 1mm.

[0055] Comparative Example 1:

[0056] The glass long fibers are directly mechanically woven to produce a three-dimensional fiber fabric by selecting a stitching needle spacing of 1mm, a fiber felt thickness of 5m, and a stitching row spacing of 5mm. The three-dimensional fiber fabric is cut into a square of about 4.5cm long and about 4.5cm wide according to a mold, and the fibers at the edges are trimmed to be neat.

[0057] Experimental Example:

[0058] The three-dimensional fiber fabric-silica aerogel composite material obtained in Examples 1-6 is treated at 600℃, and the thermal conductivity of the material before and after heat treatment is measured. The measurement results are shown in Table 2.

[0059] Table 2 Thermal conductivity of composite materials of each example

[0060]

[0061] It can be seen that as the thickness of the fiber felt increases, the thermal conductivity of the composite material decreases, and the thermal conductivity of the composite material changes little after heat treatment at 600℃. The surface three-dimensional fiber fabric-silica aerogel composite material still has good heat insulation effect after heat treatment at 600℃.

[0062] The volume density of the three-dimensional fiber and the three-dimensional fiber fabric-silica aerogel composite material obtained in each example is detected, and the detection results are shown in Table 3.

[0063] From Table 3, it can be seen that the volume density of the three-dimensional fiber fabric-silica aerogel composite material prepared by the present application is significantly lower than that of the three-dimensional fiber fabric. It can be seen that the three-dimensional fiber fabric-silica aerogel composite material has better heat insulation performance and has the characteristics of lightweight.

[0064] Table 3 Thermal conductivity of composite materials of each example

[0065]

[0066] Comparative Example 1 and Example 2 are respectively tested for heat insulation at 600℃ for 15min. The material is tested for heat insulation during the test, and the test results are shown in FIGS. 1 and 2. Figure 3 , and the macroscopic comparison before and after the test is shown in FIGS. 1 and 2. Figure 4It can be seen that after 15 minutes of heat insulation test, the maximum value of the cold surface of Comparative Example 1 is 289.1℃, the minimum value is 207.4℃, the steady-state temperature difference between the cold surface and the hot surface is 310.9℃, and after the test, the hot surface is unevenly heated, resulting in material deformation and discoloration; the maximum value of the cold surface of Example 2 is 243.8℃, the minimum value is 193.7℃, the steady-state temperature difference between the cold surface and the hot surface is 356.2℃, and after the test, the hot surface is evenly heated and has no deformation, and the three-dimensional fiber fabric-silica aerogel composite material greatly improves the heat insulation performance of the three-dimensional fiber fabric.

[0067] The above-mentioned embodiment numbers of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0068] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative and not restrictive, and those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, which are all within the protection of the present application.

Claims

1. A method for preparing a three-dimensional fiber fabric-silica aerogel composite material, characterized in that, Includes the following steps: Silica sol was prepared by adding an alkaline catalyst dropwise to a mixture of tetraethyl orthosilicate, ethanol, water, and hydrochloric acid as a precursor. The molar ratio of tetraethyl orthosilicate, ethanol, water, and hydrochloric acid was 1:(20-30):(4-5):

10. -4 ; The three-dimensional glass long fiber fabric woven from glass fiber is laid flat in a mold, and the prepared silica sol is injected into the three-dimensional glass long fiber fabric until the silica sol liquid level is parallel or slightly lower than the upper surface of the three-dimensional glass long fiber fabric, so that the three-dimensional glass long fiber fabric is filled with silica sol. A three-dimensional glass long fiber fabric filled with silica sol was left to stand to obtain a fabric composite material gel. Ethanol was added to the mold for solvent replacement, and after supercritical drying, a three-dimensional fiber fabric-silica aerogel composite material was obtained. The three-dimensional glass long fiber fabric is obtained by mechanically weaving continuous glass fiber filaments or long fiber filaments. The stitch spacing during weaving is 1 to 1.5 mm, the thickness of the three-dimensional glass long fiber fabric is 4 to 15 mm, and the stitch spacing is 1 to 10 mm.

2. The method for preparing a three-dimensional fiber fabric-silica aerogel composite material as described in claim 1, characterized in that: The alkaline catalyst is ammonia.

3. The method for preparing a three-dimensional fiber fabric-silica aerogel composite material as described in claim 1, characterized in that: The molar ratio of tetraethyl orthosilicate to alkaline catalyst is 1:0.05 to 0.

25.

4. The preparation method of the three-dimensional fiber fabric-silica aerogel composite material as described in claim 1, characterized in that: Before settling, pressure is applied along the thickness direction to the three-dimensional glass fiber fabric injected with silica sol.

5. The method for preparing a three-dimensional fiber fabric-silica aerogel composite material as described in claim 1, characterized in that: The conditions for supercritical drying are as follows: ethanol is used as the supercritical drying medium, the drying temperature is 260-270℃, the holding time is 2-4h, and the pressure is 8-12MPa.

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