Preparation method of super-thick cylindrical aerogel composite material

Abstract

The invention belongs to the field of aerogel composite materials, and particularly relates to a preparation method of a super-thick cylindrical aerogel composite material. The axial thickness of the aerogel composite material is greater than 10mm. The preparation method comprises the following steps: (1) preparing a porous wet gel composite material; the porous wet gel composite material comprises a wet gel composite material matrix and through holes formed in the wet gel composite material matrix; (2) a supporting object is stuffed into the through hole, the supporting object is of a communicating hole structure, then the wet gel composite material stuffed with the supporting object is subjected to supercritical drying, then the supporting object is taken out, and the super-thick cylindrical aerogel composite material is obtained through post-processing. According to the preparation method of the super-thick cylindrical aerogel composite material, the wet gel composite material is supported by the support with the communicating holes during supercritical drying, the drying degree of supercritical drying can be effectively improved through the communicating hole structure, and the shapes of the holes are kept.

Description

Technical Field

[0001] The invention belongs to the field of aerogel composite materials, and in particular relates to a method for preparing an ultra-thick cylindrical aerogel composite material. Background Art

[0002] Aerogel is a solid material with a nanoporous three-dimensional network structure. It is considered to be the lowest density solid substance in the world. It has extremely high porosity, extremely low density, high specific surface area, and ultra-high pore volume ratio. Therefore, it is widely used in space exploration, flame retardancy and heat insulation, energy storage, adsorption, catalysis, sensing and many other fields.

[0003] Aerogel composite materials are materials with excellent performance formed by in-situ compounding of aerogel and fiber felt and other substrates. In addition to having low thermal conductivity, they also have good tensile strength and hydrophobicity. They are ideal thermal insulation materials for new energy vehicles and various industrial equipment.

[0004] The preparation of aerogel composite materials generally includes the steps of substrate and glue preparation, dipping, aging, hydrophobic modification, supercritical drying, etc. The Chinese invention patent application with application publication number CN116043540A discloses a method for rapid modification and preparation of ultra-thin aerogel composite materials, which uses wet glass fiber surface felt, basalt surface felt, ceramic fiber felt, etc. as substrates, and prepares ultra-thin aerogel composite materials by substrate dipping, aging, hydrophobic modification, and supercritical drying.

[0005] In the process of drying wet gel into aerogel, the vaporization and release of the internal liquid solvent causes the gel structure to bear huge capillary stress. The supercritical drying process eliminates the gas-liquid interface through supercritical fluid, so it is currently the most ideal aerogel drying method. However, the current supercritical drying method is only applicable to aerogel materials with conventional thickness, that is, less than 10mm thick. When preparing ultra-thick substrate aerogel composites, supercritical drying is inefficient and difficult to dry completely. Summary of the invention

[0006] The invention provides a method for preparing an ultra-thick cylindrical aerogel composite material, which solves the problems of long drying time and incomplete drying when preparing an aerogel material with a thickness greater than 10 mm by supercritical drying.

[0007] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0008] A method for preparing an ultra-thick cylindrical aerogel composite material, wherein the axial thickness of the aerogel composite material is greater than 10 mm, and the preparation is carried out by a method comprising the following steps:

[0009] (1) preparing a wet gel composite material with holes; the wet gel composite material with holes comprises a wet gel composite material matrix and through holes opened in the wet gel composite material matrix;

[0010] (2) inserting a support into the through hole, wherein the support has a connected pore structure, and then supercritically drying the wet gel composite material plugged with the support, and then taking out the support, and then post-processing to obtain an ultra-thick cylindrical aerogel composite material.

[0011] The method for preparing the ultra-thick cylindrical aerogel composite material of the present invention uses a support with interconnected holes to support the wet gel composite material during supercritical drying. The interconnected hole structure can effectively improve the drying degree of supercritical drying and maintain the shape of the holes.

[0012] After supercritical drying, post-processing such as cutting is performed with the through-hole as the center to obtain an ultra-thick cylindrical aerogel composite material.

[0013] Preferably, the wet gel composite material with holes is in sheet form and has a plurality of through holes. In this way, since the wet gel composite material with holes has a plurality of through holes penetrating the two sides of the sheet, a plurality of products can be obtained accordingly, which can improve production efficiency and product consistency.

[0014] Preferably, the through hole has a diameter of 1 to 5 cm. For ultra-thick cylindrical aerogel composite materials with a diameter of 1 to 5 cm, it is difficult to produce and it is even more difficult to obtain a completely dried product, so the applicability of the method can be better reflected.

[0015] Preferably, the support is cylindrical corresponding to the through hole structure, and a plurality of holes are formed on the wall of the cylindrical support. With the cylindrical support design, the holes on the wall and the central hole of the cylindrical support form a large interconnected hole structure, which is more conducive to supercritical drying, and the cylindrical support is lighter in weight, which is more advantageous in material transportation. The specific form of the cylinder depends on the shape of the through hole, and can be circular, square or other special-shaped structures.

[0016] Further preferably, the through hole is circular, the cylindrical support is a round tube, and a plurality of holes are opened on the tube wall of the round tube. The cylindrical object in the form of a circular through hole and a round tube is suitable for most products, and the design form is the simplest and most effective.

[0017] Preferably, the preparation of the porous wet gel composite material includes: first opening a hole on the substrate, then inserting a removable object into the hole, and then performing wet gel compounding to form a wet gel composite material, and then removing the removable object to form the through hole to obtain the porous wet gel composite material. Although the porous wet gel composite material can be prepared by first preparing a wet gel composite material and then opening the hole, the overall processability, ease of operation, and hole opening effect are not as good as the above design. With the above design, the removable object can prevent the formation of wet gel at the hole position, which minimizes the interference with the formation process of the wet gel, and is conducive to obtaining a structurally stable aerogel composite material.

[0018] Preferably, the removable object is cylindrical in shape corresponding to the structure of the hole. The cylindrical removable object has good matching performance with the substrate, is light in weight, and is easy to move in accordance with the material.

[0019] Further preferably, the hole on the substrate is circular, and the cylindrical removable object is a round tube. The design of the circular hole and the round tube (the tube wall of the round tube has no hole) is simple and effective, and is suitable for most products.

[0020] Preferably, the aerogel material comprises a substrate, and the substrate is selected from melamine foam, preoxidized silk felt, ceramic fiber felt or glass fiber felt. The above felt-type substrates have low cost and good overall composite effect.

[0021] Preferably, the thickness of the substrate is 20 mm to 40 mm. Generally speaking, a substrate thickness of 20 mm to 40 mm can meet product requirements, and the product structure and dimensional stability are good. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the distribution of holes on the ultra-thick substrate in Example 1 of the present invention;

[0023] Among them, 1-substrate, 2-hole. DETAILED DESCRIPTION

[0024] Cylindrical aerogel composite materials are one of the important types of aerogel materials on the market. The present invention proposes a technical solution for first preparing layered aerogels and then quickly preparing such products by cutting. The technical solution does not require complex mold design and has the advantages of high production efficiency and good process adaptability.

[0025] When designing the above process, it is necessary to first prepare a thicker layered aerogel (the thickness of the layered aerogel is used as the axial thickness of the cylindrical aerogel composite material). However, when preparing thicker layered aerogel, supercritical drying takes a long time and incomplete drying is more prominent. Once incomplete drying occurs, it will directly affect the thermal insulation performance of the aerogel itself.

[0026] The present invention provides a method for preparing an ultra-thick cylindrical aerogel composite material, which uses a support to maintain the wet gel structure during wet gel molding, and uses the interconnected pore characteristics to promote the discharge of solvent from multiple dimensions during supercritical drying, thereby achieving an improvement in the degree of drying.

[0027] Considering the convenience and reliability of the preparation process, holes are first punched on the ultra-thick substrate, and then removable objects are stuffed into the holes to avoid blocking the holes on the wet gel composite substrate. After the wet gel is composited, the removable objects are replaced with a support with interconnecting holes, and then the subsequent supercritical drying process is carried out. Supercritical drying uses CO2 supercritical drying, which is common in the field of aerogel preparation.

[0028] Here, the thickness of the substrate is generally above 10 mm, for example, 20 to 40 mm.

[0029] It is an existing technology to compound wet gel on a substrate, which generally includes steps such as dipping and aging. Whether to perform further hydrophobic modification can be determined according to the situation and needs.

[0030] The implementation process of the present invention is described in detail below with reference to specific embodiments.

[0031] The specific embodiment of the preparation method of the ultra-thick cylindrical aerogel composite material of the present invention is as follows:

[0032] The method for preparing the ultra-thick cylindrical aerogel composite material of this embodiment comprises the following steps:

[0033] (1) Melamine foam is used as the substrate, the thickness of the substrate is 40 mm, and holes 2 are punched on the substrate 1 in a row and column pattern, and the hole diameter is 1 cm, such as Figure 1 shown.

[0034] A circular tube with the same diameter as the hole (without a hole on the tube wall) is placed in the hole, and then placed in a dipping container containing glue liquid for dipping, and then aged and hydrophobically modified to obtain a wet gel composite material.

[0035] The gel solution is composed of ethyl orthosilicate, anhydrous ethanol and deionized water in a mass ratio of 16:50:8, the pH is adjusted to 2-3 with concentrated hydrochloric acid, and hydrolysis is carried out at 45°C for 8 hours to obtain a hydrolyzate; then, a 4wt% NaHCO3 solution of 20% of the mass of the hydrolyzate is added, and after the gel is allowed to stand, the wet gel is obtained by aging at 65°C for 12 hours.

[0036] The hydrophobic modification liquid is a 4 wt % trimethylchlorosilane ethanol solution. The hydrophobic modification can be completed by soaking in the hydrophobic modification liquid at 65° C. for more than 6 hours.

[0037] In other implementations of this embodiment, a cylinder can be used to replace the above-mentioned round tube, which can play a role basically the same as that of the round tube. In addition, the size of the aperture can be adjusted according to actual needs, for example, it can be 2cm, 3cm, 4cm, 5cm, etc.

[0038] (2) Take out the round tube (without holes on the tube wall), put in the round tube with holes on the tube wall, and then perform CO2 supercritical drying. After supercritical drying, cut along the axial direction according to the number of holes to obtain an ultra-thick cylindrical aerogel composite material corresponding to the number of holes.

[0039] The ultra-thick cylindrical aerogel composite material can be applied to the field of electronic cigarettes and has a good heat insulation effect.

[0040] In other implementations of this embodiment, a cylinder with a foam porous structure can be used to replace the above perforated round tube. The foam porous structure has excellent interconnected pore characteristics and is also conducive to the supercritical drying process. The substrate can be a conventional substrate such as ceramic fiber felt, and the substrate thickness can be 20 mm.

[0041] In contrast, if there is no hole opening and the process of using a round tube, the main product problems are: low drying efficiency, and the center part is difficult to dry, and the drying degree can only reach 60-80%.

[0042] If you only open a hole without using a round tube, the round hole will be obviously deformed, shrinking inward or becoming elliptical, and cannot be applied to actual production.

Claims

1. A method for preparing an ultra-thick cylindrical aerogel composite material, characterized in that: The aerogel composite material has an axial thickness greater than 10 mm and is prepared by a method comprising the following steps: (1) preparing a wet gel composite material with holes; the wet gel composite material with holes comprises a wet gel composite material matrix and through holes opened in the wet gel composite material matrix; (2) inserting a support into the through hole, wherein the support has a connected pore structure, and then supercritically drying the wet gel composite material plugged with the support, and then taking out the support, and then post-processing to obtain an ultra-thick cylindrical aerogel composite material.

2. The method for preparing the ultra-thick cylindrical aerogel composite material according to claim 1, characterized in that: The porous wet gel composite material is in sheet form and has a plurality of through holes.

3. The method for preparing the ultra-thick cylindrical aerogel composite material according to claim 1 or 2, characterized in that: The diameter of the through hole is 1 to 5 cm.

4. The method for preparing the ultra-thick cylindrical aerogel composite material according to claim 1, characterized in that: The support is cylindrical corresponding to the through hole structure, and a plurality of holes are opened on the cylinder wall of the cylindrical support.

5. The method for preparing the ultra-thick cylindrical aerogel composite material according to claim 4, characterized in that: The through hole is circular, the cylindrical support is a circular tube, and a plurality of holes are opened on the tube wall of the circular tube.

6. The method for preparing the ultra-thick cylindrical aerogel composite material according to claim 1, characterized in that: The preparation of the porous wet gel composite material includes: firstly opening a hole on a substrate, then inserting a removable object into the hole, then performing wet gel compounding to form a wet gel composite material, and then removing the removable object to form the through hole to obtain the porous wet gel composite material.

7. The method for preparing the ultra-thick cylindrical aerogel composite material according to claim 6, characterized in that: The removable object is in a cylindrical shape corresponding to the structure of the hole.

8. The method for preparing the ultra-thick cylindrical aerogel composite material according to claim 7, characterized in that: The holes on the substrate are circular and the cylindrical removable object is a round tube.

9. The method for preparing the ultra-thick cylindrical aerogel composite material according to claim 1 or 6, characterized in that: The aerogel material comprises a substrate, and the substrate is selected from melamine foam, pre-oxidized silk felt, ceramic fiber felt or glass fiber felt.

10. The method for preparing the ultra-thick cylindrical aerogel composite material according to claim 9, characterized in that: The thickness of the substrate is 20 mm to 40 mm.

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