Method for preparing aerogel fibers

Abstract

This application discloses a method and application of aerogel fiber. The method includes mixing a solvent and a polymer material to form a spinning solution, using airflow spinning technology to drive the spinning solution with a high-speed airflow to form a jet, and forming a gel fiber through sol-gel conversion, and then performing solvent replacement on the gel fiber and drying to prepare aerogel fiber. The method of preparing aerogel fiber by airflow spinning provided by this application does not have high requirements for the gelation process of aerogel material, and if a spinning solution that meets the rheological conditions is obtained, aerogel fiber can be prepared by this method, avoiding the impact of insufficient gelation process on fiber performance, and at the same time improving the production efficiency of aerogel fiber and greatly simplifying the process. The prepared aerogel fiber has a unique porous structure, high specific surface area, high porosity, certain spinnability and excellent skeletal structure stability, and can be applied in fields such as spinning.

Description

Technical Field

[0001] (Related Application) This application claims priority based on the Chinese patent application with application number 202310054875.9 and invention title "Method for Preparing and Using Aerogel Fibers", filed on February 3, 2023.

[0002] (Technical Field) This application relates to aerogel materials, and in particular, to a novel method for preparing and using aerogel fibers, belonging to the technical fields of nanometer porous materials and functional fibers.

Background Art

[0003] Fiber materials have become important materials in human production and life as human culture and science and technology have developed and advanced together. The emergence of synthetic fibers has changed the way of life of humans for thousands of years when there were only natural fiber materials such as cotton, hemp, wool, and silk, liberated productivity, greatly improved the quality of human life, and is an important achievement in the development of human science and technology. After about 180 years of energetic development, synthetic fibers have gone through the initial stage of rapid expansion and have come to pursue a sophisticated development stage of high quality, high performance, and cost-effectiveness. The focus of synthetic fiber development has also shifted from the exploration of new fiber materials to the exploration of new fiber structures. Representatives of new structure fibers include profile fibers, ultra-fine fibers, and multi-layer structured functional fibers.

[0004] Aerogel materials are novel porous materials with a three-dimensional nano-network structure, possessing structural characteristics such as high porosity, high specific surface area, and ultra-low density. Their unique structure results in unique properties such as low thermal conductivity, low dielectric constant, low refractive index, and high acoustic impedance. Since the preparation of aerogel in 1931, aerogel materials have shown great potential for applications in fields such as thermal insulation, aerospace, energy storage and thermal management, adsorption and catalysis, and sound insulation. Introducing the nanoporous network structure of aerogel materials into fibrous materials should significantly improve the thermal insulation performance of the fibers, bringing new properties and application directions to fibrous materials. However, due to the poor mechanical properties of aerogel materials, there have been few reports of commercial applications in the form of aerogel powder, blocks, aerogel composites, or small amounts of aerogel film, nor have there been many reports of the preparation and application of aerogel fibers. The inventors of this application have invented a technique for preparing polyamide aerogel fibers by wet spinning and have obtained approval (Patent Document 1). However, in practical application, they have found that the complex mesoporous structure inside the aerogel fibers often impairs their structure and performance due to the complex spinning, weaving, and other processing techniques required to prepare the aerogel fibers as fabrics. Therefore, the inventors of this application sought an aerogel fiber preparation technique that would allow the aerogel fibers to be directly applied as products, bypassing complex processing, in order to preserve the structure and properties of the aerogel fibers to the greatest extent possible.

[0005] Blow spinning is a novel nonwoven fabric technology. Existing reports of blow spinning specifically describe a method that uses a high-speed airflow to act on a spinning solution, forming a polymer jet while simultaneously volatilizing the solvent in the solution. Finally, continuous fibers are formed using a collection device. The resulting fiber form is either floc or nonwoven fabric, which can be directly applied as a functional material. Typically, a blow spinning apparatus combines a high-pressure gas source for supplying gas and a syringe pump for pumping the polymer solution to form a stable jet injection device. Blow spinning offers unique advantages in nanofiber preparation, including simple preparation equipment, a safe preparation process, and high preparation speed—more than 10 times faster than conventional electrostatic spinning (Non-Patent Literature 1)—making it highly suitable for large-scale production. The resulting products are in the form of floc or nonwoven fabric, and can be directly applied as products without destructive processing, which is precisely what is lacking in existing aerogel fiber preparation technologies. However, existing air-flow spinning technologies often use low-boiling point solvents, and the action of the airflow causes a large amount of solvent to volatilize in the spinning solution, leading to the precipitation of polymers and the formation of fibers (Non-Patent Documents 2 and 3). The fibers prepared by this method currently reported are dense, non-porous precipitated fibers. In the process of preparing aerogel fibers, it is necessary to avoid the generation of precipitates as much as possible in order to form homogeneous and stable gel fibers, and air-flow spinning technology cannot be directly applied to the preparation of aerogel fibers.

[0006] There are no existing technical reports on the preparation of aerogel fibers using airflow spinning technology. For the practical application of aerogel fibers, development is needed to solve a series of problems related to their molding and processing. From this perspective, we are filing this application. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Chinese Patent Application Publication No. 110468461 Specification [Non-patent literature]

[0008] [Non-Patent Document 1] Nano Lett, 2021, 21(12): 5116-5125 [Non-Patent Document 2] Reviews of Modern Physics, 2020, 92(3):035004 [Non-Patent Document 3] ACS Applied Materials & Interfaces, 2016, 8(51): 34951-34963 [Overview of the project] [Problems that the invention aims to solve]

[0009] The main objective of this application is to provide aerogel fibers and a method for preparing them in order to overcome the shortcomings of the prior art.

[0010] Another object of this application is to provide applications for the aerogel fibers. [Means for solving the problem]

[0011] To achieve the above-mentioned objectives of the invention, the technical solutions adopted in this application include the following:

[0012] The embodiments of this application provide a method for preparing aerogel fibers, and this method is Mixing a solvent and polymer material to form a spinning solution, By employing airflow spinning technology, the spinning solution is driven by a high-speed airflow to form a jet, and gel fibers are formed through sol-gel conversion. This includes preparing aerogel fibers by performing solvent replacement on the gel fibers and then drying them.

[0013] The embodiments of this application provide aerogel fibers prepared by the preparation method described above.

[0014] Furthermore, the aerogel fiber is a porous material with a porosity of 60% to 99% and a specific surface area of 10 to 2000 m 2 / g. The diameter of the aerogel fiber is 100 μm or less, and the aspect ratio of the aerogel fiber exceeds 100.

[0015] The embodiments of the present application provide applications of the aerogel fiber in high-tech industrial fields such as spinning, chemical industry, environment or energy.

Advantages of the Invention

[0016] Compared with the prior art, the present application has the following advantages.

[0017] 1) Different from the harsh gel control of the conventional method, the method for preparing aerogel fibers by air jet spinning provided by the present application does not require high requirements for the gelation process of the aerogel material. A spinning solution that meets the rheological conditions can be obtained, and aerogel fibers can be prepared by this method, avoiding the influence on fiber performance due to insufficient gelation process. The prepared aerogel fibers have a unique three-dimensional porous network structure, extremely low thermal conductivity, high specific surface area, high porosity, certain spinnability and excellent stability of the skeleton structure, and can be applied in fields such as spinning.

[0018] 2) The method for preparing aerogel fibers by air jet spinning provided by the present application solves the influence on the performance of aerogel fibers by the existing technology that requires destructive post-processing, and at the same time improves the production efficiency of aerogel fibers, generally greatly simplifies the process, and has extremely high potential for industrial application.

Brief Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the attached drawings that need to be used in the description of the embodiments or the prior art are briefly described below. Obviously, the attached drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these attached drawings without creative labor.

[0020] [Figure 1] This is an optical micrograph of the aerogel fiber obtained in Example 1 of the present application. [Figure 2] This is a physical diagram of the aerogel fiber obtained in Example 1 of the present application. [Figure 3] This is an adsorption / desorption isotherm diagram of nitrogen for the aerogel fiber obtained in Example 1 of the present application. [Figure 4] This is a SEM photograph of the aerogel fiber obtained in Example 2 of the present application.

Mode for Carrying Out the Invention

[0021] In view of the deficiencies of the prior art, the inventors of the present application have, through long-term research and numerous practices, proposed a technical solution for the present application, mainly providing a method for preparing aerogel fibers by novel air-jet spinning.

[0022] The inventors of the present application have found that in existing aerogel fiber preparation technologies, post-processing such as spinning and knitting is required for aerogel fiber filaments. From the perspective of the complex mesoporous structure inside the aerogel fibers, textiles prepared by complex processing technologies such as spinning and knitting of aerogel fibers tend to have damaged structures and performances. Therefore, the present application improves the air-jet spinning technology, retains the technical feature of forming a jet flow by air draft, combines the sol-gel conversion process, enables air-jet spinning to obtain stable and uniform gel fibers, and further obtains aerogel fibers by drying technical means. The aerogel products obtained by this technology can be directly applied in the forms of non-woven fabrics, flocks, etc. without damaging the structure of the aerogel fibers during processing.

[0023] Hereinafter, this technical solution, its implementation process, principle, etc. will be further interpreted and explained.

[0024] One aspect of the embodiment of the present application provides a method for preparing aerogel fibers, and this method includes mixing a solvent and a polymer material to form a spinning solution, By employing airflow spinning technology, the spinning solution is driven by a high-speed airflow to form a jet, and gel fibers are formed through sol-gel conversion. This includes preparing aerogel fibers by performing solvent replacement on the gel fibers and then drying them.

[0025] In some specific embodiments, the aerogel fiber preparation method mainly comprises the following three steps: 1) Airflow spinning step: A sol (i.e., spinning solution) with certain rheological properties is prepared, and the spinning solution is driven with a high-speed airflow to form a stable jet (also called "sol fibers"). 2) Dynamic sol-gel conversion step: The sol jet is converted into a gel while moving to form gel fibers. 3) Special drying step: After solvent replacement, a special drying technique is applied to the gel fibers to convert them into aerogel fibers with minimal or no shrinkage.

[0026] In some embodiments, the spinning solution includes a sol, a semigel, or a high-viscosity solution.

[0027] Furthermore, the viscosity range of the spinning solution is 80 to 4000 cp, and the concentration is 0.1 to 30 wt%.

[0028] In some embodiments, the main components of the spinning solution include an organic solvent and a polymer material. Here, the solvent includes, but is not limited to, one or more combinations of non-volatile DMF, DMSO, NMP, water, and substances with similar properties. This application ensures that, by using a non-volatile solvent, the resulting fibers are gel fibers and that the gel fibers do not shrink, compared to other volatile solvents.

[0029] Furthermore, the polymer material may include natural polymers and / or synthetic polymer materials, and is preferably one or more of the following polymers: polyamide (e.g., terephthaloyl-p-phenylenediamine), polyester (e.g., poly(methyl methacrylate), poly(dimethyl terephthalate), etc.), cellulose (e.g., hydroxycellulose), polyolefin polymer materials (e.g., poly(vinyl alcohol)), polysiloxane, etc., but is not limited to these.

[0030] In some embodiments, the airflow spinning technique refers to a method of using a high-speed airflow to act on a spinning fluid to form a polymer jet, and forming the jet into continuous gel fibers in flight, or forming continuous semi-gel fibers on a collection device and then forming gel fibers.

[0031] In some embodiments, the airflow spinning technique in the preparation method specifically employs a spinneret as the spinning fluid outlet, with a spinning hole opening number of 1 to 500, and a diameter of 0.07 to 3 mm. In the airflow spinning technique, airflow passages are established around the spinning holes, and the airflow sufficiently drafts the spinning fluid (i.e., spinning sol) to form a jet.

[0032] Here, the airflow is dry air or a mixed airflow of dry air and water vapor (i.e., gel factor), the atmospheric pressure is 0.1 to 5 MPa, the water vapor used includes one or more combinations of water vapor, alcohol vapor, hydrochloric acid, ammonia gas, acetone vapor, or other organic solvent water vapor, and the volume ratio of water vapor in the mixed airflow is 0 to 60%.

[0033] In some embodiments, the preparation method specifically includes autonomously converting the jet into a sol-gel during flight, or causing sol-gel conversion by the spinning solution (i.e., spinning sol) coming into contact with water vapor as a gel factor dispersed in the jet flight space, or forming gel fibers by sol-gel conversion after the spinning solution jet arrives at the receiving device through one of the following: impregnation, irradiation, or heating.

[0034] Furthermore, the impregnation time is generally 3 hours or less until a complete gel is formed. The irradiation is performed using ultraviolet light, requires no power, and the irradiation time is 3 hours or less until a complete gel is formed. The heating temperature is 80°C or higher, and the temperature is maintained for 3 hours or less.

[0035] In some embodiments, the solvent used in the solvent substitution includes one or more combinations of water, tertiary butanol, ethanol, acetone, hexane, etc., and the number of solvent substitutions is 3 to 8.

[0036] Specifically, if vacuum freeze-drying is used for the subsequent drying process, solvent substitution may be carried out using water, tertiary butanol, or a mixture of water and tertiary butanol (for example, a 25% aqueous solution of tertiary butanol); if supercritical drying is used for the subsequent drying process, solvent substitution may be carried out using ethanol, acetone, or a combination of ethanol and acetone; and if atmospheric pressure drying is used for the subsequent drying process, solvent substitution may be carried out using hexane.

[0037] In some embodiments, the drying process may employ one or more combinations of supercritical drying technology, vacuum freeze-drying technology, atmospheric pressure drying technology, etc.

[0038] Furthermore, the supercritical drying process includes obtaining aerogel fibers by replacing the organic solvent inside the gel fibers with a supercritical fluid under supercritical conditions. Here, the supercritical fluid includes, but is not limited to, one or more combinations of supercritical CO2, supercritical methanol, and supercritical ethanol.

[0039] Furthermore, the vacuum freeze-drying process involves freezing and crystallizing the gel fibers at a low temperature (-10°C to -20°C) for 8 to 24 hours, and then sublimating them under conditions of a cold trap temperature of -80 to -45°C and a vacuum of less than 0.1 kPa to obtain aerogel fibers.

[0040] Furthermore, the atmospheric pressure drying process includes obtaining aerogel fibers by directly removing the organic solvent from within the gel fibers under atmospheric pressure conditions.

[0041] In summary, the air-flow spinning method for preparing aerogel fibers provided in this application is a universal method. Unlike the harsh gel control requirements of conventional methods, it does not impose high demands on the gelation process of the aerogel material, and it is possible to obtain a spinning solution that satisfies rheological conditions. This method allows for the preparation of aerogel fibers and avoids the impact on fiber performance due to insufficient gelation. At the same time, this method solves the impact on aerogel fiber performance of prior art that requires destructive post-processing, improves the production efficiency of aerogel fibers, and overall significantly simplifies the process, making it highly applicable to industry.

[0042] Another aspect of the embodiments of this application further provides aerogel fibers prepared by the preparation method described above.

[0043] In some embodiments, the main material of the aerogel fibers is a natural polymer or synthetic polymer material, preferably including, but not limited to, one or more combinations of polyamide, cellulose, polyether, polyolefin polymer material, graphene, carbon nanotube, silicon dioxide, etc.

[0044] Furthermore, the aerogel fibers are distributed macroscopically in the form of a network or aggregates, and the aerogel fibers are a porous material, with this network consisting of microporous pores with a diameter of 2 nm or less, mesoporous pores with a diameter of 2 to 50 nm, and macroporous pores with a diameter of 50 nm or more.

[0045] Furthermore, the porosity of the aerogel fibers is 60% to 99%, and the specific surface area is 10 to 2000 m². 2 The aerogel fiber is 100 μm or less in diameter and has an aspect ratio greater than 100.

[0046] Compared to wet spinning preparation, the aerogel fibers obtained in this application have the advantages of improved preparation efficiency and a significant reduction in fiber diameter, resulting in softer fibers with an optimized feel, making them better applicable in the spinning field.

[0047] As described above, the aerogel fiber is a porous fiber and has characteristics such as a high specific surface area, high porosity, extremely low thermal conductivity, certain spinnability, and excellent skeletal structure stability, making it applicable to fields such as spinning.

[0048] Another aspect of the embodiments of this application further provides applications for the aerogel fibers, which can be applied to high-tech industrial fields such as spinning, chemical industry, environment, or energy.

[0049] The technical solution of this application will be described in more detail below by several embodiments, in conjunction with the accompanying drawings. However, the selected embodiments are used solely for the purpose of interpreting the technical solution of this application and are not intended to limit the scope of this application. Accordingly, the details of the specific functions disclosed herein should not be construed as limiting, but rather as a basis for the claims and as a representative basis for teaching those skilled in the art to actually employ the invention differently in any appropriately detailed embodiment.

[0050] [Example 1] (1) Terephthaloyl-p-phenylenediamine is dissolved in DMSO, and the concentration is adjusted so that the viscosity is 1000 cp to prepare the spinning solution, which has a concentration of 3.8 wt%. (2) The spinning solution is pumped to the spinning nozzle using a pressure pump, the number of spinning holes is 10, the diameter of the spinning holes is 0.3 mm, a mixed vapor of dry air and ethanol vapor is used as the gas source, the airflow valve is opened to form a high-pressure airflow, and the volume ratio of dry air to ethanol vapor is adjusted to 4:1 and the total pressure to 1.3 MPa until a stable jet is formed, and the jet autonomously undergoes sol-gel conversion during flight to form gel fibers. (3) The gel fibers described above are subjected to solvent replacement, the replacement solvent being water, and the number of replacements being 6. (4) After freezing the hydrogel fibers at -12°C for 8 hours, place them in a vacuum freeze-dryer and sublimate them under conditions of a cold trap temperature of -80°C and a vacuum of less than 0.1 kPa until no solvent components remain in the fibers. Refer to Figure 1 for an optical microscope image of the obtained aerogel fibers, Figure 2 for a physical image, Figure 3 for a BET test image of the obtained aerogel fibers, and Table 1 for other parameters.

[0051] [Example 2] (1) Poly(methyl methacrylate) and hydroxycellulose were dissolved in DMF, and the concentration was adjusted to a viscosity of 1000 cp to prepare a spinning solution with a concentration of 5.1 wt%. (2) The spinning solution is pumped to the spinning nozzle using a pressure pump, the number of spinning holes is 1, the diameter of the spinning hole is 0.07 mm, dry air is used as the high-pressure gas source, the airflow valve is opened to form a high-pressure airflow, the dry air pressure is adjusted to 0.1 MPa until a stable jet is formed, and after the jet reaches the surface of the receiving device, it is converted from sol to gel by impregnation (3 hours or less) to form gel fibers. (3) The gel fibers described above are subjected to solvent replacement, the replacement solvent being water, and the number of replacements being 5 times. (4) After freezing the hydrogel fibers at -12°C for 8 hours, place them in a vacuum freeze-dryer and sublimate them under conditions of a cold trap temperature of -45°C and a vacuum of less than 0.1 kPa until no solvent components remain in the fibers. Refer to Figure 4 for SEM images of the obtained aerogel fibers and Table 1 for other parameters.

[0052] [Example 3] (1) Dissolve poly(methyl methacrylate) NMP, adjust the concentration so that the viscosity is 1000 cp, and prepare a spinning solution with a concentration of 4 wt%. (2) The spinning solution is pumped to the spinning nozzle by a pressure pump, the number of spinning holes is 100, the diameter of the spinning holes is 0.5 mm, dry air and hydrochloric acid vapor are used as high-pressure gas sources, the volume ratio of dry air to hydrochloric acid vapor is 2:1, the airflow valve is opened to form a high-pressure airflow, the total pressure is adjusted to 1.9 MPa until a stable jet is formed, and after the jet reaches the surface of the receiving device, it is converted from sol to gel by ultraviolet irradiation (3 hours or less) to form gel fibers. (3) The gel fibers described above were subjected to solvent substitution, the substitution solvent being ethanol, and the number of substitutions being 8. (4) Place the gel fibers in a supercritical CO2 dryer and dry them until no solvent components remain in the fibers. Refer to Table 1 for the parameters of the obtained aerogel fibers.

[0053] [Example 4] (1) Disperse in poly(vinyl alcohol) water, adjust the concentration to form an injectable gel, and use it as a spinning solution. The concentration is 0.1 wt%, and the viscosity is 80 cp. (2) The spinning solution is pumped to the spinning nozzle using a pressure pump, the number of spinning holes is 500, the diameter of the spinning holes is 0.7 mm, a mixed vapor of dry air and acetone vapor is used as the gas source, the airflow valve is opened to form a high-pressure airflow, and the volume ratio of dry air to acetone vapor is adjusted to 4:1 and the total pressure to 1.3 MPa until a stable jet is formed, and after the spinning solution comes into contact with the acetone vapor dispersed in the jet flight space as a gel factor, it undergoes sol-gel conversion to form gel fibers. (3) The gel fibers described above were subjected to solvent substitution, the substitution solvent being tertiary butanol, and the number of substitutions being 3. (4) After freezing the gel fibers at -20°C for 10 hours, place them in a vacuum freeze dryer and sublimate them under conditions of a cold trap temperature of -60°C and a vacuum of less than 0.1 kPa until no solvent components remain in the fibers. Refer to Table 1 for the parameters of the obtained aerogel fibers.

[0054] [Example 5] (1) Poly(vinyl alcohol) and poly(dimethyl terephthalate) are dispersed in DMSO, and the concentration is adjusted to create an injectable gel, forming a spinning solution with a concentration of 15 wt% and a viscosity of 4000 cp. (2) The spinning solution is pumped to the spinning nozzle using a pressure pump, the number of spinning holes is 10, the diameter of the spinning holes is 3 mm, a mixed vapor of dry air and acetone vapor is used as the gas source, the airflow valve is opened to form a high-pressure airflow, the volume ratio of dry air to acetone vapor is adjusted until the proportion of acetone gas reaches 60%, the total pressure reaches 5 MPa and a stable jet is formed, after the jet reaches the surface of the receiving device it is heated to 80°C (maintaining the temperature for 3 hours or less) to perform sol-gel conversion and form gel fibers. (3) The gel fibers described above were subjected to solvent substitution, the substitution solvent being cyclohexane, and the number of substitutions being 6. (4) Dry the gel fibers at 80°C under normal pressure until no solvent components remain. Refer to Table 1 for the parameters of the obtained aerogel fibers.

[0055] [Example 6] (1) Poly(vinyl alcohol) and tetraethyl orthosilicate are dissolved in DMSO, and the concentration is adjusted so that the viscosity is 2000 cp to make a spinning solution, with a concentration of 30 wt%. (2) The spinning solution is pumped to the spinning nozzle by a pressure pump, the number of spinning holes is 100, the diameter of the spinning holes is 0.07 mm, a mixed vapor of dry air and ammonia gas is used as the gas source, the airflow valve is opened to form a high-pressure airflow, the volume ratio of dry air to ammonia gas is adjusted to 1:1 and the total pressure to 1.3 MPa until a stable jet is formed, and the jet is autonomously converted from sol to gel during flight to form gel fibers. (3) The gel fibers described above were subjected to solvent substitution, the substitution solvent being cyclohexane, and the number of substitutions being 5 times. (4) Dry the gel fibers at 80°C under normal pressure until no solvent components remain. Refer to Table 1 for the parameters of the obtained aerogel fibers.

[0056] [Example 7] (1) Terephthaloyl-p-phenylenediamine is dissolved in DMSO, and the concentration is adjusted so that the viscosity is 1000 cp to prepare the spinning solution, which has a concentration of 3.8 wt%. (2) The spinning solution is pumped to the spinning nozzle by a pressure pump, the number of spinning holes is 10, the diameter of the spinning holes is 0.3 mm, a mixture of dry air and water vapor is used as the gas source, the airflow valve is opened to form a high-pressure airflow, and the volume ratio of dry air to water vapor is adjusted so that the proportion of water vapor is 15% and the total pressure is 1.3 MPa until a stable jet is formed, and the jet is autonomously converted from sol to gel in flight to form gel fibers. (3) The gel fibers described above are subjected to solvent replacement, the replacement solvent being water, and the number of replacements being 4. (4) After freezing the hydrogel fibers at -10°C for 24 hours, place them in a vacuum freeze-dryer and sublimate them under conditions of a cold trap temperature of -50°C and a vacuum of less than 0.1 kPa until no solvent components remain in the fibers. Refer to Table 1 for the parameters of the obtained aerogel fibers.

[0057] [Control example 1: Low-boiling point volatile solvent used in the spinning solution] (1) Dissolve poly(vinyl alcohol) and tetraethyl orthosilicate in ethanol, adjust the concentration so that the viscosity is 1500 cp, and prepare the spinning solution. (2) The spinning solution is pumped to the spinning nozzle using a pressure pump, and a mixed vapor of dry air and ammonia gas is used as the gas source. The airflow valve is opened to form a high-pressure airflow, and the ratio of air to ammonia gas is adjusted to 1:1 and the total pressure to 1.3 MPa until a stable jet is formed. (3) The gel fibers are subjected to solvent substitution, the substitution solvent being cyclohexane. (4) Dry the above fibers under normal pressure at 80°C until the solvent components are no longer present. These fibers exhibit significant shrinkage and are tested for non-porous structure; refer to Table 1 for other parameters.

[0058] [Control example 2: No sol-gel process] (1) Dissolve poly(methyl methacrylate) and hydroxycellulose in DMSO, adjust the concentration so that the viscosity is 1000 cp, and prepare the spinning solution. (2) The spinning solution is pumped to the spinning nozzle using a pressure pump, dry air is used as the high-pressure gas source, the airflow valve is opened to form a high-pressure airflow, and the air pressure is adjusted to 0.8 MPa until a stable jet is formed, forming a liquid flow on the surface of the receiving device. (3) The above fibers are subjected to solvent replacement, the replacement solvent being water, (4) The hydrogel fibers described above are frozen at -12°C for 8 hours, then placed in a vacuum freeze-dryer and dried until no solvent components remain in the fibers. These fibers do not form an aerogel pore structure and have an extremely low specific surface area. See Table 1 for other parameters.

[0059] [Table 1]

[0060] As can be seen from Examples 1 to 7, the aerogel fibers obtained by the above technical solutions of this application have a porous structure, high porosity and excellent skeletal structure stability, and are suitable for large-scale production because the preparation process is simple, the reaction conditions are mild and energy consumption is low.

[0061] Furthermore, the inventors of this application have also experimented with other raw materials and conditions described herein, referring to embodiments of Examples 1 to 7, and similarly, aerogel fibers having a unique porous structure and excellent skeletal structure stability can be produced.

[0062] The foregoing describes only some embodiments of this application, and any other modifications or improvements made by those skilled in the art, provided they do not deviate from the original idea of ​​this application, shall all be covered by this application.

[0063] (Note) (Note 1) Mixing a solvent and polymer material to form a spinning solution, By employing airflow spinning technology, the spinning solution is driven by a high-speed airflow to form a jet, and gel fibers are formed through sol-gel conversion. A method for preparing aerogel fibers, characterized by comprising performing solvent replacement on the gel fibers and then drying them to prepare aerogel fibers.

[0064] (Note 2) The preparation method according to Appendix 1, characterized in that the spinning solution contains a sol, a semigel, or a high-viscosity solution, and / or the viscosity of the spinning solution is 80 to 4000 cp and the concentration is 0.1 to 30 wt%.

[0065] (Note 3) The preparation method according to Appendix 1, characterized in that the solvent consists of one or more combinations of DMF, DMSO, NMP, and water.

[0066] (Note 4) The preparation method according to Appendix 1, characterized in that the polymer material consists of a natural polymer and / or a synthetic polymer material, preferably consisting of one or more combinations of polyamide, polyester, cellulose, polyolefin polymer material, and polysiloxane.

[0067] (Note 5) The preparation method according to Appendix 1, characterized in that a spinneret is used as the spinning solution discharge port, the number of spinning holes is 1 to 500, the diameter of the spinning holes is 0.07 to 3 mm, an airflow passage is provided around the spinning holes, the airflow drafts the spinning solution and forms a jet, the airflow is dry air or a mixed airflow of dry air and water vapor, the atmospheric pressure is 0.1 to 5 MPa, and the water vapor consists of one or more of the following: water vapor, alcohol vapor, hydrochloric acid, ammonia gas, and acetone vapor.

[0068] (Note 6) The preparation method according to Appendix 5, characterized in that the volume ratio of water vapor in the mixed gas stream is 0 to 60%.

[0069] (Note 7) The preparation method according to Appendix 1, characterized by comprising: autonomously converting the jet into a sol-gel during flight; converting the spinning solution into a sol-gel by contacting it with water vapor as a gel factor dispersed in the flight space of the jet; or, after the spinning solution jet arrives at the receiving device, converting it into a sol-gel by one of impregnation, irradiation, or heating to form gel fibers.

[0070] (Note 8) The preparation method according to Appendix 7, characterized in that the impregnation time is 3 hours or less, the irradiation is carried out using ultraviolet light, the irradiation time is 3 hours or less, the heating temperature is 80°C or higher, and the temperature is maintained for 3 hours or less.

[0071] (Note 9) The preparation method according to Appendix 1, characterized in that the solvent used in the solvent substitution consists of one or more combinations of water, tertiary butanol, ethanol, acetone, and hexane, and the number of solvent substitutions is 3 to 8 times.

[0072] (Note 10) The preparation method according to Appendix 1, characterized in that the drying treatment is one or more combinations of supercritical drying, vacuum freeze-drying, and atmospheric pressure drying.

[0073] (Note 11) The preparation method according to Appendix 10, wherein the supercritical drying includes replacing the organic solvent inside the gel fibers with a supercritical fluid under a supercritical state to obtain aerogel fibers, and preferably the supercritical fluid consists of one or more combinations of supercritical CO2, supercritical methanol, and supercritical ethanol.

[0074] (Note 12) The preparation method according to Appendix 10, characterized in that the vacuum freeze-drying includes freezing and crystallizing the gel fibers at -10°C to -20°C for 8 to 24 hours, and then sublimating them under conditions of a cold trap temperature of -80 to -45°C and a vacuum of less than 0.1 kPa to obtain aerogel fibers.

[0075] (Note 13) The preparation method according to Appendix 10, characterized in that the atmospheric pressure drying includes directly removing the organic solvent from the gel fibers under atmospheric pressure conditions to obtain aerogel fibers.

[0076] (Note 14) The aerogel fibers are porous materials with a porosity of 60% to 99% and a specific surface area of ​​10 to 2000 m². 2 The preparation method according to Appendix 1, characterized in that the aerogel fiber is / g, the diameter of the aerogel fiber is 100 μm or less, the aspect ratio of the aerogel fiber is greater than 100, and the internal pore structure of the aerogel fiber consists of microporous pores with a pore diameter of 2 nm or less, mesoporous pores with a pore diameter of 2 to 50 nm, and macroporous pores with a pore diameter of 50 nm or more.

[0077] (Note 15) Applications of aerogel fibers prepared by the preparation method described in any one of Appendix 1 to 14 in the fields of spinning, chemical industry, environment, or energy.

Claims

1. Mixing a solvent and polymer material to form a spinning solution, By employing airflow spinning technology, the spinning solution is driven by a high-speed airflow to form a jet, and gel fibers are formed through sol-gel conversion. This includes preparing aerogel fibers by performing solvent replacement on the gel fibers and then drying them, The viscosity of the spinning solution is 80 to 4000 cp, and the concentration is 0.1 to 30 wt%. The solvent consists of one or more of the following: DMF, DMSO, NMP, and water. The aforementioned polymer material consists of natural polymers and / or synthetic polymer materials. The solvent used in the aforementioned solvent substitution consists of one or more combinations of water, tertiary butanol, ethanol, acetone, and hexane, and the number of solvent substitutions is 3 to 8 times. A spinneret is used as the spinning fluid discharge port, with 1 to 500 spinning holes and a diameter of 0.07 to 3 mm. An airflow passage is provided around the spinning holes, and the airflow drafts the spinning fluid to form a jet. The jet autonomously undergoes sol-gel conversion during flight, or sol-gel conversion is achieved by contacting the spinning fluid with water vapor, which acts as a gel factor dispersed in the flight space of the jet, or, after the spinning fluid jet arrives at the receiving device, sol-gel conversion is achieved by impregnation, irradiation, or heating to form gel fibers. The airflow is dry air or a mixture of dry air and water vapor, the atmospheric pressure is 0.1 to 5 MPa, the water vapor consists of one or more of the following: water vapor, alcohol vapor, hydrochloric acid, ammonia gas, and acetone vapor, the impregnation time is 3 hours or less, the irradiation is carried out using ultraviolet light, the irradiation time is 3 hours or less, the heating temperature is 80°C or higher, and the temperature is maintained for 3 hours or less. The aerogel fibers are porous materials with a porosity of 60% to 99% and a specific surface area of ​​10 to 2000 m². ２ A method for preparing aerogel fibers, characterized in that the aerogel fiber is 100 μm or less in diameter, the aerogel fiber has an aspect ratio greater than 100, and the internal pore structure of the aerogel fiber consists of microporous pores with a pore diameter of 2 nm or less, mesoporous pores with a pore diameter of 2 to 50 nm, and macroporous pores with a pore diameter of 50 nm or more.

2. The preparation method according to claim 1, characterized in that the spinning solution includes a sol, a semigel, or a high-viscosity solution.

3. The preparation method according to claim 1, characterized in that the polymer material consists of one or more combinations of polyamide, polyester, cellulose, polyolefin polymer material, and polysiloxane.

4. The preparation method according to claim 1, characterized in that the volume ratio of water vapor in the mixed gas stream is 0 to 60%.

5. The preparation method according to claim 1, characterized in that the drying treatment is one or more combinations of supercritical drying, vacuum freeze-drying, and atmospheric pressure drying.

6. The preparation method according to claim 5, characterized in that the supercritical drying includes replacing the organic solvent inside the gel fibers with a supercritical fluid under a supercritical state to obtain aerogel fibers.

7. The supercritical fluid is supercritical CO ２ The preparation method according to claim 6, characterized in that it consists of one or more combinations of supercritical methanol and supercritical ethanol.

8. The preparation method according to claim 5, characterized in that the vacuum freeze-drying includes freezing and crystallizing the gel fibers at -10°C to -20°C for 8 to 24 hours, and then sublimating them under conditions of a cold trap temperature of -80 to -45°C and a vacuum of less than 0.1 kPa to obtain aerogel fibers.

9. The preparation method according to claim 5, characterized in that the atmospheric pressure drying includes directly removing the organic solvent from the gel fibers under atmospheric pressure conditions to obtain aerogel fibers.

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