TWI829147B - Low thermal conductivity and low-k dielectric aerogel composites and preparation method therefor - Google Patents

Abstract

The present invention discloses an aerogel material with low thermal conductivity, low dielectric constant (low-D _K) and low dielectric-loss (low-D _F) and preparation method therefor. The method comprises steps of: (1) mix and hydrolysis, (2) dispersion and condensation, (3) molding, and (4) drying. The prepared fiber/aerogel composite is further processed by steps of: (5) containing or immersion in a polymer solution, (6) solvent drying and (7) crosslinking or solidifying to obtain a polymer/fiber/aerogel composite featuring high strength, low thermal conductivity, low- D _Kand low- D _F. The method provided by the present invention does not involve highly conductive solvents or additives, and a highly porous structure is formed so that the dielectric constant and dielectric loss of polymer/fiber/aerogel composite are significantly reduced, suitable for 5G communications, microwave circuits, protection and insulation for electric vehicle lithium battery modules.

Description

Electrogel composite material with both low heat transfer and low dielectric properties and preparation method thereof

The present invention relates to an airgel composite material, and in particular to an airgel/fiber/polymer composite material having low thermal conductivity coefficient, low dielectric constant and low dielectric loss, and a preparation method thereof.

It is known that the dielectric properties of applied materials gradually decrease as the internal porosity of the material increases. Therefore, airgel materials and related composite materials will become low dielectric applications required for 5G fast transmission and lithium battery module safety protection. product. As we all know, aerogel is a porous material with a three-dimensional network structure, a porosity higher than 80% (or even higher than 95%), and a low density (about 0.005 to 0.2g/cm ³ ) , high specific surface area (500 to 2000m ² /g), low thermal conductivity (k=15 to 40mW/mk) and low dielectric properties (D _K =1.3 to 2.5), low dielectric loss (D _F <0.003 or less) These characteristics make aerogel or its composite materials a material required for fast transmission of low-dielectric technology, signal transmission of electric self-driving cars, and safety protection of lithium battery modules.

Since airgel or its composite materials have a large amount of porosity and extremely low density, they are of considerable value in applications with low dielectric properties such as high thermal insulation, high fire resistance, low signal transmission resistance, and high resistance to electrical shock. In the process of gradually moving towards the 5G era and electric vehicles or electric self-driving cars, the application of high-frequency transmission urgently requires low dielectric constant (D _K <2.5), low signal loss (D _F <0.003) and high electric resistance Impact and other dielectric materials. In basic material theory, the internal porosity of the material will significantly reduce the electronic and electric transmission properties. Therefore, the higher the porosity in the structure of inorganic materials or organic materials, the lower their dielectric properties will be. For this reason, 5G high-frequency applications and electric self-driving cars require porous materials as the main substrate.

According to Japanese Patent Publication No. 8-228105, a method of manufacturing a semiconductor device is disclosed. In this method, a wet glue film is formed on a substrate, and the solvent containing the wet glue film is evaporated through supercritical and subcritical drying procedures to form an airgel film. The prepared dry airgel film still maintains the network structure of the wet airgel film and is a porous material with high porosity and low dielectric constant. Accordingly, aerogel can be used as a new material for dielectric layers and insulating inner layers. However, using supercritical or subcritical drying processes in the transistor structure manufacturing process will lead to disadvantages such as complicated procedures and expensive equipment investment.

"Supercritical drying" means that water and organic solvents are in a supercritical state under high temperature and high pressure, so that the organic solvent and water have gas-liquid mixing properties at the same time, and the solvent is directly vaporized and dried in the supercritical state. Therefore, the remaining solvent in the network structure can be removed under supercritical conditions without shrinkage of the wet glue. However, in the preparation of transistor structures, the time from solution preparation to coating of low-dielectric films varies. In addition, during the condensation process of aerogel solutions, silica molecules will immediately aggregate and condense, resulting in aerogel formation. The viscosity of a solution increases with time. When spin coating is performed at a fixed rate, the film thickness on the substrate will also increase. In the same way, the coating thickness of the transistor thin film structure will have different thicknesses as the process time increases, so it is impossible to prepare a high-quality transistor thin film structure.

The traditional preparation method of aerogel is the sol-gel synthesis method, which mainly mixes precursors such as alkoxysilane, methyl n-silicate or water glass with a large amount of organic mixed solvents, and then adds an acid catalyst. To carry out hydrolysis reaction (hydrolysis). After the hydrolysis reaction takes a certain period of time, an alkali catalyst is added to carry out the condensation reaction. During the condensation reaction, a sol will gradually be formed, and the molecules in the sol will continue to react and bond, gradually forming a semi-solid polymer gel. . Then, after a period of aging, the gel forms a stable three-dimensional network structure. Finally, hydrophobic solvents such as n-butanol, n-hexanol, n-hexane or cyclohexane are used for solvent replacement, and then the solvent in the airgel structure is extracted and dried using supercritical drying technology. Traditional process technology not only consumes a large amount of expensive organic solvents and supercritical equipment, but also requires long-term solvent replacement with hydrophobic solvents. Therefore, the preparation of aerogels is costly and time-consuming.

On the other hand, the preparation method of hydrophobic aerogels also adopts the sol-gel synthesis method, which mainly consists of methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES). After the silicon alkoxide precursor is mixed with an organic solvent, an alkali catalyst is added to perform a hydrolysis reaction. After the hydrolysis reaction for a certain period of time, the condensation reaction will occur. During the condensation reaction, a sol will gradually form. The molecules in the sol will continue to react and bond, gradually forming a semi-solid polymer gel. After aging for a period of time, solvent replacement such as isopropyl alcohol, acetone, n-hexane or cyclohexane is used for two to three days to form a stable three-dimensional network structure of the hydrophobic gel. Finally, the solvent in the airgel structure is dried using normal pressure drying technology to obtain a porous dry airgel block. The production process of hydrophobic aerogels also requires a large amount of expensive organic solvents, and requires a long period of solvent replacement with alcohols or alkanes, so the preparation is time-consuming and costly.

Since the process technology used in the above-mentioned aerogel preparation method requires the use of a large amount of hydrophobic solvents; organic solvents such as alkanes, multiple solvent replacements are performed for two to three days, and then drying using supercritical drying technology or normal pressure and high temperature This technology prevents the airgel structure from shrinking or cracking due to the surface tension of water molecules during the normal pressure drying process. However, multiple hydrophobic solvent replacement technologies and supercritical drying technologies are time-consuming and expensive, which is not conducive to the competitiveness of airgel mass production and future applications.

According to U.S. Invention Patent Publication No. US8,945,677B2, it discloses "the use of low-K dielectric materials to manufacture electronic equipment." It mainly uses low-dielectric materials (including polyimide aerogels) to manufacture electronic equipment and semiconductor components. and methods. This patent provides a method for manipulating the properties of dielectric materials and affecting the overall dielectric properties of a system. Specifically, a polyimide acid presol, a catalyst and a polar solvent are mixed to form a sol mixture layer, and then the sol components are cross-linked to form a wet gel material, and a supercritical fluid is used to remove the solvent to form a polyimide gas. Gel film. This technology was used to combine it with a polyimide airgel film on the surface of a nonporous, low-K template substrate. This patent uses low-K dielectric materials to manufacture electronic devices and uses supercritical fluid technology to remove solvents in multiple steps through pressure circulation. The overall technology is time-consuming and costly. The process takes too long and is not cost-effective.

According to the mainland invention patent publication number CN102044525A, which discloses "low-K dielectric layer structure, semiconductor device structure and formation method", it mainly uses silicon dioxide aerogel to form a low-K dielectric layer structure. This patent provides a semiconductor device structure and a formation method thereof. The formation method includes: providing a substrate, a first dielectric layer and an etching barrier layer are formed on the substrate, and the first dielectric layer and the etching barrier layer are both formed with openings. Filled with metal as a plug; a sacrificial oxide layer is formed on the etching barrier layer and the plug; an opening is formed in the sacrificial oxide layer, and metal is filled in the opening to form an interconnection structure, wherein this interconnection structure is electrically connected to the plug plug; selectively remove the sacrificial oxide layer to form gaps between the interconnection structures; and form silicon dioxide aerogel as a low-K dielectric layer in the gaps between the interconnection structures. This patent uses a low-K dielectric layer structure and utilizes tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS) as the material structure. In addition, its drying uses multiple steps of normal temperature or supercritical fluid technology to prepare low-dielectric films. The overall technology is time-consuming and costly. The process takes too long and is not cost-effective.

According to Chinese invention patent publication number CN105189104A, it discloses "airgel insulating panels and their manufacturing", which mainly uses polyimide airgel to prepare insulating panels, which can be used in laminated panels for aerospace applications. The panel includes a polyimide airgel surface layer and a reflective protective layer on the surface layer. The manufacturing process of polyimide aerogel in this patent includes: (a) polymerizing a mixture of dianhydride and diamine monomer in a bipolar alkaline solvent (DMAc or NMP) to form a polyimide solution; (b) Polyamic acid solution glue is cast in fiber wadding; (c) uses chemical imidization reaction to use acetic anhydride and pyridine gel polyamic acid solution; (d) uses CO ₂ supercritical or sub-supercritical drying technology to remove The solvent in the gel is used to form fiber/polyimide airgel composite materials. The overall technology is time-consuming and costly. The process takes too long and is not cost-effective and competitive.

According to the Mainland China Invention Patent Publication No. CN108203516A, it discloses a "method for preparing cross-linked polyimide aerogels", which mainly adopts a sol-gel method, which includes: (a) a mixture of dianhydride and diamine monomer in Polymerize in a bipolar alkaline solvent (DMAc or NMP) to form a polyamide solution; (b) Cast the polyamide solution into fiber wadding; (c) Use chemical imidization reaction using acetic anhydride and pyridine gel Polyamide solution; (d) use supercritical or sub-supercritical CO ₂ drying technology to remove the solvent in the gel to form fiber/polyamide aerogel composites. The overall technology is also time-consuming and costly , the manufacturing process takes too long and is not cost-effective and competitive.

In traditional manufacturing porous aerogel technology, the sol-gel reaction process requires the addition of a large amount of organic solvents, acid and alkali ions, and the use of surfactants or other additives in order to obtain a complete aerogel material. However, in subsequent processes It is necessary to use a long period of solvent replacement or use deionized water to rinse the airgel material to maintain the stability of the airgel structure during the drying process to prepare products with appropriate low dielectric properties; in addition, the use of ultra-high dielectric properties Critical or sub-supercritical CO ₂ drying technology can effectively prepare high-quality aerogel materials by removing the solvent from the gel.

In addition, polyimide solution combined with supercritical or sub-supercritical CO ₂ drying technology is used to remove the solvent in the polyimide gel to prepare pure polyimide aerogels or fibers/polymers with a large pore structure. However, the dielectric constant of polyimide aerogels prepared by related technologies cannot be significantly reduced below 2.8, and its dielectric loss is still maintained above 0.003. This is due to the chemical structure of polyimide. It contains a large number of dipolar structures and hydrophilic groups, so the dielectric constant or dielectric loss of the material cannot be significantly reduced even after complete cross-linking and solidification.

According to the "low dielectric aerogel and its preparation method" technology disclosed by the applicant in Taiwan Invention Patent Application No. 110106194, rapid condensation technology is used to reduce the shrinkage rate of block aerogel preparation, and there is no need to The airgel wet glue can be quickly prepared with a complete gel structure by soaking it in a solvent and replacing it with an organic solvent. This prior technology is controlled rapid gel technology to control the structure of the airgel, and then rinse it with deionized water to remove charged ions in the structure to reduce ion accumulation during subsequent applications. Therefore, this prior technology removes steps such as solvent replacement and supercritical drying technology of wet gel films in the overall process, and surprisingly can obtain a porous low-dielectric film within a few minutes to tens of minutes of aging. Subsequently, during the preparation process, the airgel composite is compounded with a polymer solution (such as polyimide, epoxy resin or polyphenylene ether, etc.) to prepare a high-strength and porous airgel/polymer composite. Material. However, this previous technology requires the use of deionized water to rinse the airgel structure with charged ions, which also wastes a lot of process time and generates a large amount of washing wastewater.

Therefore, in order to improve the shortcomings of the past low dielectric electrogel product manufacturing process and to mass-produce high-purity (low impurity content) low dielectric electrogel composite materials, the improved preparation technology provided by the present invention can easily prepare low dielectric loss ( D _F <0.003) airgel composite; then compound the airgel composite with polymer solution (such as polyimide, epoxy resin or polyphenylene ether, etc.) to form a porous airgel/polymer composite Material. Here, the mixing ratio of airgel and various polymer solutions can control the strength, dielectric constant and dielectric loss of the airgel/polymer composite material. Related products can be used in materials required for 5G fast transmission, electric self-driving signal transmission, and lithium battery module safety protection and fire prevention. In addition, the present invention can also improve the shortcomings in the preparation of the previous technology, such as: low dielectric structure unevenness of semiconductor devices, low dielectric constant or low dielectric loss of airgel is not significantly reduced, and the application of supercritical drying technology Difficulties in the preparation of integrated circuits and other issues.

The present invention provides a low heat transfer and low dielectric electrogel material and a preparation method thereof. The first embodiment of the present invention includes: (1) mixed hydrolysis step: adding a siloxane to an ethanol aqueous solution before The body is stirred and mixed to form a mixed solution, wherein the siloxane precursor includes a siloxane compound and a hydrophobic modified siloxane compound or a combination thereof, and then an acid catalyst is added to the mixed solution to perform a hydrolysis reaction. ; (2) Condensation and dispersion step: add a dispersion aqueous solution to the mixed solution and stir rapidly to disperse the condensation solution in the aqueous solution. The dispersion solution includes an alkali catalyst to perform a condensation reaction to form a sol solution; (3 ) Molding step: Inject the sol solution into a model to promote further condensation of the sol solution to form a solid aerogel wet glue network structure; in addition, the sol solution can also be injected into a fiber-containing material model to promote the sol solution Further condensation in a fiber-containing material model forms a solid aerogel wet glue structure such as fiber-containing material; (4) Drying step: dry the solid aerogel structure at a drying temperature under normal pressure. In order to obtain a structurally uniform electrogel composite material with both low heat transfer and low dielectric, the drying temperature ranges from 60 to 150°C.

Further, in the above preparation method, the drying step includes: a solvent vaporization step: placing the solid aerogel structure in an azeotropic temperature environment containing an alcohol-water mixed solution, so that the solid aerogel structure is A large amount of alcohol-water mixed solution is quickly azeotropically vaporized to distill and dry the alcohol-water mixed solution. The vaporization temperature is 60 to 110°C; and the solvent bumping step: adjust the drying temperature of the dry aerogel structure to The solvent bumping temperature causes the remaining alcohol-water mixed solvent inside the dry aerogel to rapidly boil to form a positive pressure. The generation of this positive pressure inside the airgel structure is used to inhibit the shrinkage of the aerogel during drying. , and use the positive pressure inside the airgel structure to generate a large number of nanometer to submicron-sized micropores in the airgel structure, and the burst temperature is 110 to 150°C.

The preparation method of the electrogel material with both low heat transfer and low dielectric provided by the present invention does not involve the use of hydrophobic organic solvents such as toluene, hexane, etc., and a sol-gel with a very small acid and alkali ion concentration is used in the preparation. Using synthetic technology, high purity, low heat transfer and low dielectric loss aerogel composite materials can be prepared without adding additives such as surfactants, especially without the need for multiple substitutions of hydrophobic organic solvents.

In addition, in order to further improve the structural strength of the low heat transfer and low dielectric aerogel composite material to enhance the back-end applicability of the product; in some embodiments, in the molding step, the condensation dispersed aerogel solution is injected into One contains fiber mats, fiber paper, fiber blankets or fiber boards and other base materials; under this condition, the airgel molecules in the condensation dispersed airgel solution will first be adsorbed on the fiber surface, and stack with each other into a three-dimensional gas during the condensation process The gel network structure is used to form a solid aerogel/fiber molding body that is stable and contains a large amount of fibers, and in the subsequent drying step, an aerogel/fiber composite membrane or composite plate with low heat transfer and low dielectric is formed.

Furthermore, in the mixed hydrolysis step (1), when the content ratio of the acid catalyst in the mixed solution is higher, the hydrolysis rate is faster, but a large amount of acid ions will produce ionic conductivity under the action of an electric field, so The dielectric constant and dielectric loss of the airgel structure will be significantly improved; relatively, the lower the acid catalyst content ratio, the slower the overall hydrolysis rate. Therefore, the present invention improves the efficiency by reducing the acid catalyst content and increasing the process temperature. The hydrolysis rate of trace acid ions can significantly reduce the overall content of added acid ions; on the other hand, siloxane compounds and hydrophobized siloxane compounds will produce a large amount of alcohol molecules during the hydrolysis process, so during the hydrolysis In the process, deionized water is used to replace organic solvents such as ammonia or alkanes, thereby reducing the addition of organic solvents such as ammonia or alkanes. In addition to reducing the impact of organic solvents such as ammonia or alkanes on the dielectric properties of the aerogel, it can also It reduces the hazards of organic solvent treatment in the manufacturing process and also reduces the overall aerogel preparation cost.

Further, in (2) the condensation and dispersion process, under the promotion of the alkali catalyst aqueous solution, the siloxane molecules or hydrophobic siloxane molecules of the hydrolysis solution are rapidly stirred by the emulsifier or homogenizer, and the hydrolyzed siloxane Molecules or hydrophobic siloxane molecules will form nanometer to sub-micrometer molecular droplets dispersed in the aqueous solution.

Further, in the forming step (3), when the condensation dispersion solution has not undergone a condensation reaction, the hydrolyzed siloxane molecules and hydrophobic siloxane molecules at the nanometer level to the submicron level are mixed and dispersed. Inject into a molded film to form a molded structure with a specific appearance, such as film, sheet, or plate in various appearances; after a few minutes, the siloxane molecules and hydrophobic molecules in the nanometer to submicron molecular droplets Catalyzed by the repulsive force of water, the flexible siloxane molecules accelerate their aggregation and combination to form a three-dimensional siloxane network aerogel wet glue structure; in (3) the forming step, the nano-scale to sub-micron In the molecular droplets, the initial structural size of the siloxane molecules can be controlled at about 5 to 10 nanometers, and then the airgel wet glue molecules are further stacked to form larger aggregates and interconnected to form a three-dimensional network structure. , to form a stable semi-solidified aerogel wet glue structure containing a large amount of alcohol-aqueous solution.

Furthermore, in order to improve the structural strength of the electrogel composite material with both low heat transfer and low dielectric, in the (3) molding step, the hydrolyzable siloxane molecules and hydrophobicity of the nanoscale to submicron scale can be further The mixed dispersion solution of siloxane molecules is dropped into a model containing a large number of fiber materials, such as fiber mats, fiber papers, fiber blankets or fiber boards; under this condition, the nanoscale to submicron scale hydrolyzed silica The airgel molecules in the mixed dispersion solution of alkane molecules and hydrophobic siloxane molecules will first be adsorbed on the surface of the fiber, and catalyzed by the repulsive force of water, they will accelerate their aggregation and combination to form a three-dimensional siloxane network and form a stable And it contains a large amount of solid aerogel/fiber moldings such as fibers, and in the subsequent drying step, an aerogel/fiber composite membrane or composite plate with both low heat transfer and low dielectric is formed; further, in (3) In the molding step, the mixed dispersion solution of hydrolyzed siloxane molecules and hydrophobic siloxane molecules can be injected into the fiber-containing structure using impregnation technology, pressure suction technology, spraying, mist spraying, or vacuum adsorption technology for compounding. processing.

Further, in the drying step (4), after the solid airgel wet glue structure is stabilized, the alcohol-containing aqueous solution inside the airgel wet glue structure is evaporated at the drying temperature under normal pressure environment; in the present invention In some embodiments, the (4) drying step also includes (4-1) a solvent vaporization step and (4-2) a solvent bumping step; during the (4-1) solvent vaporization step, the solid-like aerogel is wetted The alcohol-water solution contained in the gel structure vaporizes rapidly at the azeotropic temperature and dries; in (4-2) solvent bumping step, adjust the temperature of the nearly dry airgel to a bumping temperature so that the airgel contained inside A trace amount of alcohol aqueous solution produces rapid boiling. At this bumping temperature, the alcohol aqueous solution contained in the airgel structure generates a positive pressure inside the airgel. This positive pressure can inhibit the shrinkage or collapse of the airgel structure during the drying process. behavior.

Furthermore, in order to improve the disadvantages of the internationally disclosed polyimide aerogel process being time-consuming, high cost and using supercritical or sub-supercritical CO ₂ drying technology, the present invention uses simple technology to produce pure aerogel or aerogel/fiber Composite materials, and then use impregnation or spraying technology to infiltrate polymer solutions such as polyimide into pure airgel sheets or airgel/fiber composite materials, followed by solvent drying and cross-linking or curing processes, and can prepare gas Gel composite polymer/airgel composite material or airgel composite polymer/fiber/airgel composite material, the overall process technology is simple, low cost and does not require the use of supercritical or sub-supercritical CO ₂ drying technology.

Therefore, in the second embodiment of the present invention, the preparation method of the airgel composite material further includes: (5) impregnating the polymer solution step: preparing a polymer solution, and adding the polymer solution to the airgel composite material. Inject the low heat transfer and low dielectric aerogel material for impregnation, so that the polymer solution can evenly penetrate into the internal pores of the airgel to form an airgel composite containing the polymer solution; wherein the polymer solution contains Polymer materials and mixed solvents, the polymer materials include thermosetting polymers, thermoplastic polymers, liquid crystal polymers or combinations thereof; and (6) solvent drying step: place the airgel composite containing the polymer solution on a high At a temperature above the boiling point of the solvent of the molecular solution, the internal solvent of the airgel composite containing the polymer solution is vaporized, and the polymer is coated on the surface of the airgel mesh skeleton or fiber surface. The drying temperature of the solvent is between 60 to 115°C; where the polymer solution is a thermoplastic polymer, which can be solidified and formed after the solvent is vaporized and dried to obtain a thermoplastic polymer/aerogel composite material with high strength, low heat transfer and low dielectric or a thermoplastic polymer with high thermoplasticity. Molecule/fiber/aerogel composite material; wherein, the polymer solution is a thermosetting polymer. After the solvent is vaporized and dried, it is then molded at a high-temperature cross-linking curing temperature; the above process technology can obtain both high strength and low heat Thermoset polymer/aerogel composite materials or thermoplastic polymer/fiber/aerogel composite materials with low dielectric properties.

Furthermore, the polymer solution is a thermosetting polymer including epoxy plastic ester, polyimide, polyphenylene ether, polyphenylene mercaptan, polysulfone, polyphenolic plastic ester, polymelamine-formaldehyde plastic ester or a combination thereof.

Further, the polymer solution is a thermoplastic polymer including polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, polyamide, polyamide ester, polyester or a combination thereof.

In the aforementioned step (5) of impregnating the polymer solution, after the aerogel material with both low heat transfer and low dielectric strength forms an airgel composite material or an airgel/fiber composite material with appropriate strength, the polymer solution is Inject into the airgel material, so that the polymer chains can evenly penetrate into the internal pores of the airgel material with the solvent, so that it forms an airgel composite material or airgel/fiber composite material containing a polymer solution; and in ( 6) In the solvent drying step, the polymer solution in the airgel composite material or airgel/fiber composite material will first go through a liquid-solid phase separation process to form a solvent-rich phase and a The solvent rich in the polymer phase, and the solvent rich in the solvent phase will gradually vaporize during the phase separation; on the other hand, the polymer chains in the polymer rich phase will be preferentially covered on the airgel skeleton or fiber surface, and then in the air A polymer film is formed on the surface of the gel skeleton or fiber structure.

Furthermore, based on the overall polymer solution, the concentration of the polymer material is between 0.01 and 80.0wt%; among them, the lower the concentration of the polymer material, the better the efficiency of the polymer material penetrating into the internal pores of the airgel. The prepared The higher the pore content of polymer/aerogel composites or polymer/fiber/aerogel composites that have both low heat transfer and low dielectric properties, the more superior their low heat transfer and low dielectric properties are; in contrast, the polymer/fiber/aerogel composite has better properties. The higher the material concentration, the higher the content of polymer material coated inside the silicon-based aerogel. The prepared polymer/airgel composite material or polymer/fiber/airgel composite material has both low heat transfer and low dielectric properties. The higher the polymer content inside the material, the better the product strength; therefore, the concentration of the added polymer solution can be used to control both low heat transfer and low dielectric polymer/airgel composite or airgel composite Materials: Dielectric properties and strength of polymer/fiber/airgel composite materials, the optimized polymer solution concentration is between 5.0 and 30.0wt%.

In the above (6) solvent drying step, when the polymer material is a thermoplastic polymer, such as polyethylene, polyester or polyamide, the solvent drying is completed. After that, a high-strength, high-toughness, lightweight and low-dielectric thermoplastic polymer/aerogel composite material or polymer/fiber/aerogel composite material can be formed; specifically, for example: polyethylene, PE), polypropylene (PP), polycarbonate (PC), polyamide (PA), polyesteramide (PEA), polyester (Polyethylene terephthalate, PET), or polyethylene Polytetrafluoroethylene (PTFE) or a combination thereof; on the contrary, when the polymer material is a thermosetting polymer (Thermal setting polymer), such as epoxy resin, polyimide, polyphenylene ether, in (6) After the solvent drying step is completed, proceed to (7) cross-linking and curing step to obtain a thermosetting polymer/aerogel composite material or thermosetting polymer/ Fiber/aerogel composites. Specifically, for example, epoxy resin (Epoxy), polyimide (PI), polyetherimine (PEI), polyphenylene oxide (PPO), polyphenylene sulfide (Polyphenylene) sulfide (PPS), polyetherketone liquid crystal polymer (Polyetherketone, PEK), polyetheretherketone liquid crystal polymer (Polyetheretherketone, PEEK) or a combination thereof.

In the above (6) solvent drying step, the organic solvent inside the polymer-containing airgel composite material with both low heat transfer and low dielectric is vaporized, causing the polymer-containing solution airgel composite material to gradually dry. The solvent drying temperature depends on the boiling point of the mixed solvent of the polymer solution; in some embodiments, the mixed solvent is ethanol, and its solvent drying temperature is 60 to 75°C; in other embodiments, the mixed solvent is butanone, which The solvent drying temperature is 80 to 90°C; therefore, the airgel composite material containing the polymer solution obtained after drying will not be deformed due to a large number of bubbles generated by excessive drying temperature.

Furthermore, in the above (6) solvent drying step, when the polymer solution is a thermosetting polymer solution, then after the solvent is dried, it further includes (7) cross-linking and curing step: a cross-linking and curing temperature of a specific thermosetting polymer. Under this condition, the thermosetting polymer chains and the thermosetting polymer chains and the airgel molecules undergo cross-linking reactions and are combined and solidified. If the thermosetting polymer is epoxy, the cross-linking curing temperature is 175 to 200°C, preferably 185 to 190°C; on the other hand, when the thermosetting polymer is polyimide, the crosslinking curing temperature is 175 to 200°C, preferably 185 to 190°C. The cross-linking curing temperature is 120 to 325°C, preferably a series of cross-linking curing temperatures of 120, 200, 260 to 325°C. In some embodiments, the highest cross-linking curing temperature is 320 to 325°C; in this (7 ) In the cross-linking and curing step, at a specific cross-linking temperature, the polymer chains covering the airgel network skeleton undergo cross-linking reactions with each other, so that between the polymer chains, or between the polymer and the airgel A cross-linking reaction occurs between the glue molecules to form a three-dimensional network structure. Therefore, after the cross-linking is solidified, the polymer will be cross-linked to obtain a polymer with high heat resistance, high strength, lightweight and low dielectric properties. Airgel composites or polymer/fiber/aerogel composites.

Further, in the above preparation method, the siloxane compound includes tetramethoxysilane (TMOS), tetraethoxysilane (TEOS) or a combination thereof; the hydrophobic modified siloxane compound includes methyl Trimethoxysilane (Methyltrimethoxysilane, MTMS), methyltriethoxysilane (MTES) or a combination thereof, wherein, in the overall mixed solution, the siloxane compound and the hydrophobic modified siloxane compound are The content molar ratio ranges from 0:100 mol% to 40:60 mol%; the purpose of adding this hydrophobic modified siloxane compound is to reduce the cracking phenomenon produced by the airgel structure during the drying process, and to reduce the thermal conductivity and its The dielectric constant is to reduce the dielectric loss; on the other hand, the purpose of adding the siloxane compound is to regulate the internal fine structure of the airgel structure and increase the hole structure and porosity in the structure.

Further, in the above preparation method, the ethanol aqueous solution contains ethanol, deionized water, distilled water, double distilled water or a combination thereof.

Furthermore, in the above preparation method, the fiber material includes various types of porous mat-like, paper-like, and other inorganic and organic fibers prepared from glass fiber, ceramic fiber, rock wool fiber, polypropylene fiber, nylon fiber, polyester fiber, etc. Blanket, rope, plate or combination thereof.

Further, in the above preparation method, the concentration of the polymer solution contains 0.01wt% to 80wt% of the polymer solute.

Furthermore, in the above preparation method, the uniform infiltration process of the polymer solution includes pressure suction, impregnation, spraying, injection, perfusion or a combination thereof.

Furthermore, in the above preparation method, the electrogel composite material with both low heat transfer and low dielectric gel has a porous structure, its porosity ranges from 40.0 to 95.0%, and its density ranges from 0.180 to 0.600 g/cm ³ . The electrical constant ranges from 1.20 to 1.87, and its dielectric loss ranges from 0.0026 to 0.0078.

The preparation method provided by the present invention can quickly produce high-strength and low-dielectric loss polymer/aerogel composite materials or polymer/fiber/aerogel composite materials. Low dielectric aerogel materials or aerogel/fiber composite materials are prepared by rapid condensation and dispersion using equipment such as emulsifiers or homogenizers under solvents and low acid and alkali ion concentrations; further, the materials with both low heat transfer and low dielectric properties are Airgel materials or airgel/fiber composites and polymer solutions are uniformly pressed, impregnated and compounded, followed by solvent drying and cross-linking curing to prepare high strength, high toughness, low heat transfer and low dielectric properties. Molecular/aerogel composites or polymer/fiber/aerogel composites, which contain thermoset and thermoplastic polymers.

The preparation method provided by the invention has the following effects:

1. The preparation method provided by the present invention modifies the traditional sol-gel reaction process to prepare aerogel materials with both low heat transfer and low dielectric. No other organic solvents other than alcohols are added in the sol-gel process of aerogels. , surfactants, adhesives and other substances, therefore the content of conductive impurities inside the prepared airgel composite material is significantly reduced, and there is no need to use long-term solvent replacement or use deionized water to flush conductive impurities during the process. The overall process is simple. It is highly safe and has more economical advantages. The batch process speed can be reduced to 12 to 48 hours, or tens to hundreds of micron aerogels and polymer/aerogel composite films or sheets can be prepared in a continuous production manner. etc. to improve production efficiency.

2. In the preparation method provided by the present invention, factors such as the ratio of the siloxane compound and the hydrophobic modified siloxane compound, the dispersion water content, the stirring rate, the content and ratio of the acid catalyst and the alkali catalyst can be used, and then the Easily control the porosity, pore size and dense structure of aerogel materials with low heat transfer and low dielectric properties.

3. In the preparation method provided by the present invention, no organic solvents other than ethanol, such as alkanes, aromatic solvents, or inorganic solvents such as ammonia, are added, and no surfactants, organic adhesives, or inorganic adhesives are added, and acid contact By controlling the solvent and alkali catalyst at very low concentrations, the thermal conductivity and low dielectric properties of the prepared airgel material can be further controlled to improve the practical properties of the airgel composite material.

4. The aerogel material or aerogel/fiber composite material with both low heat transfer and low dielectric prepared by the preparation method of the present invention can further be prepared by pressure impregnation with a polymer solution to prepare a polymer/aerogel composite material or high-polymer composite material. Molecular/fiber/airgel composite materials use various polymer solutions to impregnate and spray to prepare airgel composite materials with high strength, high porosity, low heat transfer and low dielectric.

5. In the preparation method provided by the present invention, in the step of impregnating the polymer solution, the polymer chain uniformly penetrates into the internal pores of the silicon-based airgel material with the solvent, thereby forming an airgel structure and polymer composite to form an aerosol with both low heat transfer and Low dielectric polymer/aerogel composite materials or polymer/fiber/aerogel composite materials; the chemical structure of the polymer and its concentration can be adjusted to achieve control of both low heat transfer and low dielectric aerogel composites The material's strength, durable temperature, bonding with other materials, thermal conductivity coefficient and low dielectric properties; among them, the porosity of the product produced by the preparation method provided by the invention is between 40.0 and 95.0%, and its density Between 0.180 and 0.600 g/cm ³ , its dielectric constant ranges from 1.20 to 1.87, and its dielectric loss ranges from 0.0025 to 0.0085.

Please refer to Figure 1, which is a first embodiment of a method for preparing a low heat transfer and low dielectric electrogel composite material provided by the present invention. The steps include: a mixing and hydrolysis step (S1), a dispersion and condensation step (S2), Forming step (S3) and drying step (S4), wherein:

Mixed hydrolysis step (S1): Add a siloxane precursor to an ethanol aqueous solution to form a mixed solution, wherein the siloxane precursor includes a hydrophobically modified siloxane compound, a siloxane compound or other combination, and then an acid catalyst is added to the mixed solution to perform a hydrolysis reaction; in some embodiments, the siloxane compound (alkoxysilane) includes tetramethoxysilane (TMOS), tetraethoxysilane ( tetraethoxysilane (TEOS) or a combination thereof, the hydrophobic modified siloxane compound includes hydrophobic methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES) or a combination thereof; adding the hydrophobic The purpose of modifying siloxane is to reduce the cracking phenomenon of the airgel structure during the drying process, and the purpose of adding the siloxane is to regulate the internal fine structure of the airgel structure to increase the hole content in the structure; in some embodiments In terms of the overall mixed solution, the total molar content of the siloxane compound and hydrophobic modified siloxane is between 0.5 mol% and 40 mol%, and the molar content of the ethanol aqueous solution is 99.5 mol%. to 60mol%.

In some embodiments, the molar ratio of the siloxane compound and the hydrophobically modified siloxane compound is from 0:100 to 40:60; in a preferred embodiment, the molar ratio of the siloxane compound and the hydrophobically modified siloxane compound is from 0:100 to 40:60. The molar ratio of the alkane compound is 5:95; in the ethanol aqueous solution, the molar ratio of ethanol and water is from 0:100 to 50:50; in a preferred embodiment, the molar ratio of ethanol and water is 15:85.

In the process of fully mixing the siloxane compound or the hydrophobically modified siloxane compound with a large amount of ethanol aqueous solution containing a trace amount of acid catalyst, a hydrolysis reaction (hydrolysis) is performed simultaneously, wherein the solvent of the acid catalyst ethanol aqueous solution includes ( 1) ethanol, and (2) one or a mixture of different compositions of deionized water, treated water, secondary treated water, etc., the total content of the mixture of siloxane and hydrophobic modified siloxane and the content of the acid catalyst The molar ratio is 1:0.01 to 1:0.00005. When the content ratio of the acid catalyst in the mixed solution of siloxane and hydrophobic modified siloxane is higher, the hydrolysis rate is faster; in other words, the acid catalyst The higher the content ratio, the greater the ion content in the overall airgel structure, and the greater the dielectric loss of the airgel will be; in a preferred embodiment, the total of the mixture of siloxane and hydrophobic modified siloxane The molar ratio of the content to the acid catalyst content is 1:0.00014.

Condensation and dispersion step (S2): Add a dispersion aqueous solution to the mixed solution. The dispersion aqueous solution includes an alkali catalyst, and use rapid stirring equipment such as an emulsifier or homogenizer to stir the siloxane and the hydrophobic modified silica at high speed. The alkane molecules are evenly dispersed to form a uniform sol solution; it should be further explained that in the condensation reaction, the condensation reaction temperature, the content of the added deionized water and the stirring rate can be adjusted to adjust the rate of the condensation reaction. The internal aerogel microstructure of the obtained sol solution; the volume ratio of the dispersion solution to the ethanol aqueous solution is from 75:25 to 30:70; in a preferred embodiment, the volume ratio of the dispersion solution to the ethanol aqueous solution is 50 :50.

In the condensation reaction, the increase in temperature helps to significantly shorten the condensation reaction time, that is to say, the gelation time of the airgel is effectively shortened in the dispersion condensation step (S2); wherein, the alkali catalyst and When the acid catalyst content equivalent ratio is 1.0:1.0, the condensation reaction temperature is 20 to 55°C, and the condensation reaction time is 20 to 250 minutes; in some preferred embodiments, the condensation reaction temperature is 25°C, and the condensation reaction time is 25°C. The reaction time is about 220 minutes. When the condensation reaction temperature is 50°C, the condensation reaction time is about 15 minutes.

In other embodiments, increasing the content of alkali catalyst will also significantly shorten the condensation reaction time, wherein the equivalent ratio of the content of 1.0M alkali catalyst and 1.0M acid catalyst is 0.8:1.0 to 2.0:1.0, and the condensation reaction time is 360 to about 3 minutes; in some embodiments, the content equivalent ratio is 0.8:1.0, and the condensation reaction time is 360 minutes; in other preferred embodiments, the content equivalent ratio is 1.6:1.0, and the condensation reaction time About 10 minutes; it should be further explained that when the content equivalent ratio is less than 1.0:1.0, the condensation reaction time gradually increases, and the dielectric loss of the prepared airgel will decrease significantly; when the content equivalent ratio When the ratio is greater than 1.0:1.0, the condensation reaction time gradually decreases, but the dielectric loss of the prepared airgel will increase significantly due to the ion content; in a preferred embodiment of this implementation, the content volume ratio is 1.2: 1.0.

Molding step (S3): Inject the sol solution into a model to promote further condensation of the sol solution to form a solid aerogel structure, wherein the model includes a molding mold or a molding mold containing fiber material; in this molding step In the process, evenly dispersed siloxane molecules and hydrophobic siloxane molecules are formed through rapid stirring by an emulsifier, etc., and the hydrophobic siloxane molecules accelerate their aggregation and combination with each other under the catalysis of the repulsive force of water to form a three-dimensional siloxane network siloxane gas. Gel molecule aggregates, the initial structural size of siloxane airgel molecules can be controlled at 5 to 10 nanometers, and the initial structures are stacked to form airgel wet glue molecules of about 50 to 100 nanometers, 50 to 100 nanometers The airgel wet glue molecules are further stacked to form larger aggregates, and are interconnected to form a three-dimensional network structure, forming a stable quasi-solid aerogel structure containing a large amount of solvent.

In other embodiments, the sol solution is injected into a model containing a large amount of fibrous materials. The fibrous materials include inorganic fibers or organic fibers in the form of mats, paper, blankets, plates or combinations thereof, and the sol solution is injected into the fibrous materials. Medium; under this condition, siloxane airgel molecules are adsorbed on the fiber surface, and condense and stack on the fiber surface to form 50 to 100 nanometer airgel wet glue molecules, 50 to 100 nanometer airgel wet glue molecules Furthermore, the fibers and fiber structures are stacked to form a three-dimensional airgel network structure, thereby forming a stable semi-solid airgel structure containing a large number of fibers; in this molding step, the sol solution can use impregnation technology, pressure Suction, spraying, perfusion, or vacuum adsorption and other technologies are used to perform composite processing on fiber materials.

In some embodiments, the fiber material includes various types of porous mat-like, paper-like, and carpet-like materials prepared from inorganic and organic fibers such as glass fiber, ceramic fiber, rock wool fiber, polypropylene fiber, nylon fiber, polyester fiber, etc. Shape, rope, plate or combination thereof.

Drying step (S4): Dry the solid aerogel wet gel structure at a high temperature under normal pressure at a drying temperature to obtain a uniform structure with both low heat transfer and low dielectric properties. Gel or aerogel/fiber composite; in some embodiments, the drying temperature ranges from 60 to 150°C.

Further, the drying step includes a solvent vaporization step (S4-1) and a solvent bumping step (S4-2).

Solvent vaporization step (S4-1): Place the quasi-solid aerogel wet glue structure in an environment with a vaporization temperature, and at the same time put the quasi-solid aerogel wet glue structure under a normal pressure state, and use the temperature to let a large amount of solvent containing Alcohols and water molecules are rapidly azeotropically vaporized to dry the alcohols and water molecules in a solid aerogel-like wet glue structure; in some embodiments, the vaporization temperature is 60 to 110°C.

Solvent bumping step (S4-2): Adjust the temperature of the vaporized aerogel containing a trace amount of solvent to the solvent bumping temperature, so that the trace amounts of alcohols and water molecules contained in the airgel composite material will produce a rapid vaporization and bumping phenomenon; In some embodiments, the bumping temperature is 110 to 150°C; it should be further explained that in the high-temperature environment created by the bumping temperature, the bumping phenomenon caused by trace amounts of alcohol and water molecules inside the airgel promotes the A positive pressure is generated inside the gel, which can inhibit the shrinkage or collapse of the airgel structure during the drying process; on the other hand, the positive pressure causes the airgel network structure to expand and create porosity; it is Therefore, this preparation method can be used to prepare low-density and high-porosity aerogels or aerogel/fiber composite materials. The thermal conductivity k of the pure aerogel film or sheet is about 0.013 to 0.018W/mk; air condensation The thermal conductivity property k of glue/fiber film or plate is about 0.022 to 0.032W/mk.

In addition, since no large amounts of organic solvents such as alkanes, aromatic benzene or inorganic solvents such as ammonia are added, and no surfactants are added, the drying process is safer and higher purity aerogel products can be produced. Because the prepared high-porosity airgel material or airgel/fiber composite material does not contain various impurities, the thermal conductivity properties, dielectric constant and dielectric loss of the product are all lower.

Please refer to Figure 2, which is a photo of the appearance of the airgel material and airgel/fiber composite material with both low heat transfer and low dielectric prepared by the aforementioned preparation method. Its appearance is a white thick plate or thin plate structure.

Please refer to Figure 3, which is a scanning electron microscope SEM observation photo of the cross section of a pure aerogel plate with low heat transfer and low dielectric prepared according to the aforementioned preparation method, with a magnification of 3000 times; under electron microscope observation, Its microstructure presents a three-dimensional network agglomerate of spherical aerogels with sizes ranging from submicron to micron. In addition, as can be seen from Figure 3, among the electrogel materials with both low heat transfer and low dielectric In addition to the agglomeration structure of the airgel, it also has a large number of micron to sub-micron pores in series. The pore structure formed by the series connection of these micro-pores gives it low heat transfer and low dielectric properties.

Please refer to Figure 4, which is an SEM scanning electron microscope observation photo of the cross section of an aerogel/fiber composite material with both low heat transfer and low dielectric. The magnification is 250 times. Figure 4 shows that in this embodiment, both The electrogel/fiber composite material with low heat transfer and low dielectric is composed of a large number of sub-micron airgel molecules adsorbed on the surface of the fiber and the pores between the fibers aggregate into a three-dimensional airgel network structure, which is aggregated as a whole. The structure still contains a large number of holes. The relevant holes provide the airgel/fiber composite material with both low heat transfer and low dielectric properties, and the large number of fibers improves the appropriate strength and other properties of the airgel/fiber composite material.

Please refer to Figure 5, which illustrates the specific preparation process of the second embodiment of the present invention, which further utilizes a large amount of polymer solution to impregnate or inject the above-mentioned airgel material or aerogel/ which has both low heat transfer and low dielectric. Fiber composite materials are prepared into high strength, low heat transfer and low dielectric molecule/airgel composite materials or polymer/fiber/airgel composite materials; in the second embodiment, the polymer/airgel composite material The preparation method of gel composite material or polymer/fiber/airgel composite material includes steps: mixing and hydrolysis step (S1”), dispersion and condensation step (S2”), molding step (S3”), and drying step (S4”) , impregnating polymer solution step (S5”), solvent drying step (S6”) and cross-linking curing step (S7”), among which:

Mixed hydrolysis step (S1"): Add a siloxane precursor to an ethanol aqueous solution to form a mixed solution, wherein the siloxane precursor includes a hydrophobically modified siloxane compound, a siloxane compound or Its combination, and then an acid catalyst is added to the mixed solution to perform a hydrolysis reaction, wherein the siloxane compound (alkoxysilane) includes tetramethoxysilane (TMOS), tetraethoxysilane (TEOS) ) or a combination thereof, the hydrophobic modified siloxane compound includes hydrophobic methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES) or a combination thereof; in some embodiments, For the entire mixed solution, the total molar content of the siloxane compound and hydrophobic modified siloxane is between 0.5 mol% and 40 mol%, and the molar content of the ethanol aqueous solution is between 99.5 mol% and 60 mol%. between %.

In some embodiments, the molar ratio of the siloxane compound and the hydrophobically modified siloxane compound is from 0:100 to 40:60; in a preferred embodiment, the molar ratio of the siloxane compound and the hydrophobically modified siloxane compound is from 0:100 to 40:60. The molar ratio of the alkane compound is 5:95; in the ethanol aqueous solution, the molar ratio of ethanol and water is from 0.01:100 to 50:50; in a preferred embodiment, the molar ratio of ethanol and water is 15:85.

In the process of fully mixing the siloxane compound or the hydrophobically modified siloxane compound with a large amount of ethanol aqueous solution containing a trace amount of acid catalyst, a hydrolysis reaction (hydrolysis) is performed simultaneously, wherein the ethanol aqueous solution includes (1) ethanol, and (2) One or a mixture of different compositions of deionized water, treated water, secondary treated water, etc., the molar ratio of the total content of the mixture of siloxane and hydrophobic modified siloxane to the content of the acid catalyst is 1 : 0.01 to 1:0.00005; in a preferred embodiment, the molar ratio of the total content of the mixture of siloxane and hydrophobic modified siloxane to the content of the acid catalyst is 1:0.00014.

Dispersion condensation step (S2"): Add a dispersion solution including an alkali catalyst to the mixed solution, and use rapid stirring equipment such as an emulsifier or homogenizer to stir the siloxane and hydrophobic modified silicon at high speed. Oxane molecules are uniformly dispersed to form a uniform sol solution; the volume ratio of the dispersion solution to the ethanol aqueous solution is from 75:25 to 30:70; in a preferred embodiment, the volume ratio of the dispersion solution to the ethanol aqueous solution is 50:50.

In some embodiments, when the equivalent ratio of the content of alkali catalyst and acid catalyst is 1.0:1.0, the condensation reaction temperature is 20 to 55°C, and the condensation reaction time is 20 to 250 minutes; in some preferred embodiments , the condensation reaction temperature is 25°C, and the condensation reaction time is about 220 minutes. When the condensation reaction temperature is 50°C, the condensation reaction time is about 25 minutes.

In other embodiments, the equivalent ratio of 1.0M alkali catalyst and 1.0M acid catalyst is 0.8:1.0 to 2.0:1.0, and the condensation reaction time is about 3 to 360 minutes; in some embodiments, the equivalent ratio is 0.8:1.0, and the condensation reaction time is 360 minutes; in other preferred embodiments, the equivalent ratio is 1.6:1.0, and the condensation reaction time is about 10 minutes; in one preferred embodiment of this embodiment, The equivalent number ratio is 1.2:1.0.

Molding step (S3″): Inject the sol solution into a mold to promote further condensation of the sol solution to form a solid aerogel structure. The mold includes a molding mold or a fiber-containing molding mold; in some embodiments, The base material includes a molding mold. In this molding step, uniformly dispersed siloxane molecules are formed through rapid stirring by an emulsifier, and hydrophobic siloxane molecules are accelerated to aggregate and combine with each other under the catalysis of the repulsive force of water to form The three-dimensional siloxane network aggregates through a condensation reaction to form a siloxane airgel molecular aggregate. The initial structural size of the siloxane airgel molecules can be controlled at 5 to 10 nanometers. The initial structure is then stacked to form approximately The airgel wet glue molecules of 50 to 100 nanometers are further stacked to form larger aggregates, and are connected to each other into a three-dimensional network structure to form a stable, large-containing Solvent-like solid aerogel structure.

In some embodiments, the fiber material includes inorganic fibers or organic fibers in the form of mats, paper, blankets, plates or combinations thereof, and the sol solution is injected into the fiber material; under this condition, the siloxane airgel The molecules are adsorbed on the fiber surface and condensed and stacked on the fiber surface to form airgel wet glue molecules of 50 to 100 nanometers. The 50 to 100 nanometer airgel wet glue molecules further stacked between the fibers and the fiber structure to form a three-dimensional The air gel network structure is then formed into a stable semi-solid airgel structure containing a large number of fibers; in this molding step, the sol solution can be applied to the fibers using impregnation technology, pressure suction, spraying, perfusion, or vacuum adsorption. Composite processing is performed on the material.

In some embodiments, the fiber material includes various types of porous mat-like, paper-like, and carpet-like materials prepared from inorganic and organic fibers such as glass fiber, ceramic fiber, rock wool fiber, polypropylene fiber, nylon fiber, polyester fiber, etc. Shape, rope, plate or combination thereof.

Drying step (S4”): Dry the solid aerogel wet gel structure at a high temperature under normal pressure at a drying temperature to obtain a uniform structure with low heat transfer and low media. Electric gel or aerogel/fiber composite material; in some embodiments, the drying temperature ranges from 60 to 150°C.

Further, the drying step includes a solvent vaporization step (S4-1″) and a solvent bumping step (S4-2″), wherein:

Solvent vaporization step (S4-1"): Place the quasi-solid aerogel wet glue structure in an environment with a vaporization temperature, and at the same time make the quasi-solid aerogel wet glue structure under a normal pressure state, and use the temperature to let a large amount of solvent containing The alcohol and water molecules are rapidly azeotropically vaporized to dry the alcohol and water molecules in the wet glue structure of the solid-like aerogel through azeotropic distillation; in some embodiments, the vaporization temperature is 60 to 110°C.

Solvent bumping step (S4-2"): Adjust the temperature of the vaporized aerogel containing trace amounts of solvent to the solvent bumping temperature to cause the trace amounts of alcohols and water molecules contained in the airgel composite to produce a rapid vaporization and bumping phenomenon ; In some embodiments, the bumping temperature is 110 to 150°C; it should be further explained that in the high temperature environment created by the bumping temperature, the bumping phenomenon generated by trace amounts of alcohols and water molecules inside the airgel promotes A positive pressure is generated inside the airgel, which can inhibit the shrinkage or collapse of the airgel structure during the drying process; on the other hand, the positive pressure causes the airgel network structure to expand to create porosity; Therefore, this preparation method can be used to prepare low-density and high-porosity aerogels or aerogel/fiber composite materials. The thermal conductivity k of the pure aerogel film or sheet is about 0.013 to 0.018W/mk; The thermal conductivity property k of the gel/fiber film or sheet is approximately 0.022 to 0.032W/mk.

Impregnating polymer solution step (S5"): Prepare a polymer solution, inject the polymer solution into the airgel material with both low heat transfer and low dielectric for impregnation, so that the polymer solution can evenly penetrate into the internal pores of the airgel To form an airgel composite material containing a polymer solution, wherein the polymer solution includes a polymer material and a mixed solvent. The polymer material includes a thermosetting polymer, a thermoplastic polymer, a liquid crystal polymer or a combination thereof.

Solvent drying step (S6"): Place the airgel composite material containing the polymer solution at a temperature above the boiling point of the solvent of the polymer solution to promote the vaporization of the solvent inside the airgel composite material containing the polymer solution and promote The polymer is coated on the surface of the airgel network skeleton or fiber surface, and the drying temperature of the solvent is between 60 and 115°C.

Specifically, the polymer solution is a thermoplastic polymer, which can be solidified and molded after the solvent is vaporized and dried to obtain a thermoplastic polymer/aerogel composite or thermoplastic polymer/airgel composite material with high strength, low heat transfer, and low dielectric. Fiber/aerogel composite material; wherein, the polymer solution is a thermosetting polymer. After the solvent is vaporized and dried, it is then molded at a high temperature cross-linking curing temperature; the above process technology can obtain high strength, low heat transfer and Low dielectric thermosetting polymer/aerogel composite materials or thermoplastic polymer/fiber/aerogel composite materials.

Further, in the step of impregnating the polymer solution (S5"), after the electrogel material with both low heat transfer and low dielectric gel is dried and formed, the electrogel material with both low heat transfer and low dielectric gel is then impregnated with the polymer solution. Or spray a thin polymer solution, so that the polymer thin solution can evenly penetrate into the internal pores of the airgel material, and further form an airgel composite material containing the polymer solution. The airgel composite containing the polymer solution Materials include polymer solution-containing airgel composite panels or airgel/fiber composite panels.

Furthermore, based on the polymer solution as a whole, the concentration of the polymer material is between 0.01 and 80.0wt%; wherein, the lower the concentration of the polymer material, the better the efficiency of the polymer material penetrating into the internal pores of the airgel. The prepared The higher the pore content of the airgel composite containing the polymer solution, the better the low heat transfer and low dielectric properties; in contrast, the higher the concentration of the polymer material, the polymer material is coated inside the silicon-based aerogel The higher the content, the higher the polymer content inside the prepared airgel composite containing polymer solution, so the better the strength of the product; therefore, the concentration of the polymer-containing solution can be controlled by using the concentration of the added polymer solution. For the dielectric properties and strength of airgel composites, the optimal polymer solution concentration ranges from 5.0 to 30.0wt%.

In the above preparation method, when the polymer material is a thermoplastic polymer, such as polyethylene, polypropylene, polytetrafluoroethylene, etc., after the solvent drying step (S6") is completed, a high polymer material can be formed. Thermoplastic polymer/aerogel composite material or thermoplastic polymer/fiber/aerogel composite material with high strength, high toughness, lightweight and low dielectric; specifically, the thermoplastic polymer includes polyethylene (PE) , polypropylene (PP), polycarbonate (PC), polyamide (PA), polyesteramide (PEA), polyester (Polyethylene terephthalate, PET), polytetrafluoroethylene (Polytetrafluoroethylene, PTFE) or combinations thereof.

In some embodiments, the polymer solution composite processing of low heat transfer and low dielectric electrogel composite materials can be processed using solution injection technology, impregnation technology, pressure suction technology, spraying, perfusion, or vacuum adsorption. Molecular solution composite processing; on the contrary, when the polymer material is a thermosetting polymer (Thermal setting polymer), such as epoxy resin, polyimide, polyphenylene ether, after the solvent drying step (S6") is completed, The cross-linking and curing step (S7”) will obtain a thermosetting polymer/aerogel composite or a thermosetting polymer/fiber/aerogel composite with high heat resistance, high strength, lightweight, low heat transfer and low dielectric Material; specifically, the thermosetting polymer includes epoxy resin (Epoxy), polyimide (PI), polyetherimine (PEI), polyphenylene oxide (PPO), Polyphenylene sulfide (PPS), polyetherketone liquid crystal polymer (Polyetherketone, PEK), polyetheretherketone liquid crystal polymer (Polyetheretherketone, PEEK) or combinations thereof.

Furthermore, in this low heat transfer and low dielectric electrogel composite material, when the airgel molecule content is higher or the concentration of the polymer solution is thinner, the internal porosity content of the airgel composite material will be greater, which will As a result, the thermal conductivity, dielectric constant and dielectric loss of the prepared aerogel composite material are lower; therefore, the thermal conductivity and dielectric loss of the aerogel composite material with both low heat transfer and low dielectric properties are lower, and at high frequencies The harder it is to convert electric field energy into heat under certain conditions; on the contrary, the physical properties such as strength, toughness, rigidity, etc. of the prepared electrogel composite material with both low heat transfer and low dielectric properties are worse; on the other hand, under this condition, the In low heat transfer and low dielectric electrogel composite materials, the lower the airgel molecule content, or the higher the concentration and content of the polymer solution, the better the physical and other strength properties of the low heat transfer and low dielectric electrogel composite material. Excellent, but the thermal conductivity, dielectric constant and dielectric loss are higher; therefore, in the preparation method provided by the invention, the airgel composite material can be made by adding the airgel content and the concentration of the impregnated polymer solution. Control of product thermal conductivity and dielectric properties.

In the solvent drying step (S6"), after the aerogel composite material with both low heat transfer and low dielectric is impregnated with the polymer solution, the aerogel containing polymer solution can be processed in a specific high temperature and normal pressure environment. Evaporation of organic solvents inside the composite material; during the drying process, the polymer solution inside the airgel composite containing polymer solution will first undergo liquid-solid phase separation to form a solvent-rich phase and One is rich in polymer phase, and the solvent in the rich solvent phase will gradually vaporize during the phase separation; on the other hand, the polymer chains in the rich polymer phase will be preferentially covered on the surface of the airgel skeleton or fiber, and then A polymer film layer is formed on the surface of the airgel skeleton or fiber structure; in some embodiments, the mixed solvent is ethanol, and the solvent drying temperature is 60 to 75°C; in other embodiments, the mixed solvent is methyl ethyl ketone, The solvent drying temperature is 80 to 90°C, the mixed solvent is toluene, and the solvent drying temperature is 100 to 110°C; therefore, the airgel composite material containing the polymer solution obtained after drying will not be affected by excessive drying temperature. The large number of bubbles produced causes deformation.

In some embodiments, when the polymer solution is a thermosetting polymer, the preparation method further includes a cross-linking and curing step (S7″): performing a cross-linking and curing process between the thermosetting polymer and the airgel molecules at a cross-linking and curing temperature. They combine with each other and solidify under the cross-linking reaction. Among them, when the thermosetting polymer is epoxy resin (Epoxy), the cross-linking curing temperature is 150 to 180°C, preferably 150°C or 180°C; when the thermosetting polymer is polyester Imine (polyimide), the cross-linking and curing temperature is 120 to 325°C, preferably a series of cross-linking and curing temperatures of 120, 180, 260 or 325°C; in the cross-linking and curing step (S7″), At a specific cross-linking curing temperature, the thermosetting polymer molecular chains coated on the airgel network skeleton undergo a cross-linking reaction with the silicon-based airgel molecules; during this cross-linking reaction, the airgel network The polymer chains on the skeleton react chemically with each other, causing a cross-linking reaction between polymers or between polymers and airgel molecules to combine with each other. Therefore, at this cross-linking curing temperature, After polymer cross-linking, a thermosetting polymer/silicon-based airgel composite material with high heat resistance, high strength, lightweight and low dielectric properties will be obtained.

Please refer to Figure 6, which is a general appearance photo of a preferred embodiment of an electrogel composite material with both low heat transfer and low dielectric prepared by the method provided by the present invention. The electrogel composite material with both low heat transfer and low dielectric The electrical gel composite material is a low dielectric polyimide (PI)/airgel composite board or a low dielectric polyimide (PI)/ceramic fiber/airgel composite board.

Please refer to Figure 7, which is a scanning electron microscope (SEM) cross-section of a preferred embodiment of a low heat transfer and low dielectric electrogel composite material prepared according to the method provided by the present invention. Observe the photo with a magnification of 250 times, which shows the fine structure of the prepared porous polyimide/airgel composite plate. It can be seen that the polymer polyimide is coated in the network of the airgel particles. Structurally, a porous polyimide/aerogel composite plate with a uniform appearance structure is formed. code name Density (g/cm ³ ) Thermal conductivity coefficient (W/mk) Test frequency (GHz) D _K value D _F value Pure airgel composite 0.123 0.0249 2 1.326 0.0025 0.123 0.0249 3 1.320 0.0024 0.123 0.0249 5 1.314 0.0026 0.123 0.0249 10 1.315 0.0026 Ceramic fiber/airgel composite 0.204 0.0271 2 1.372 0.0034 0.204 0.0271 3 1.370 0.0034 0.204 0.0271 5 1.351 0.0032 0.204 0.0271 10 1.346 0.0026 PI-15/ceramic fiber/airgel composite 0.366 0.0472 2 1.403 0.0037 0.366 0.0472 3 1.394 0.0037 0.366 0.0472 5 1.380 0.0036 0.366 0.0472 10 1.350 0.0033 PI-20/ceramic fiber/airgel composite 0.461 0.0631 2 1.567 0.0047 0.461 0.0631 3 1.563 0.0046 0.461 0.0631 5 1.548 0.0044 0.461 0.0631 10 1.521 0.0041 PI-30/ceramic fiber/airgel composite 0.538 0.1125 2 1.678 0.0078 0.538 0.1125 3 1.661 0.0077 0.538 0.1125 5 1.655 0.0074 0.538 0.1125 10 1.654 0.0073 PI-50/ceramic fiber/airgel composite 0.678 0.1632 2 1.846 0.0125 0.678 0.1632 3 1.838 0.0121 0.678 0.1632 5 1.812 0.0120 0.678 0.1632 10 1.804 0.0114 PI-80/ceramic fiber/airgel composite N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Table 1

Please refer to Figure 8, which is a scanning electron microscope cross-section of a preferred embodiment of the polyimide/ceramic fiber/airgel composite material with both low heat transfer and low dielectric prepared by the present invention. , SEM) observation photo with a magnification of 1000 times. The photo shows that in a polyimide/ceramic fiber/airgel composite board, the polymer polyimide is coated on the ceramic fiber and airgel network structure. On the surface, polyimide is used to provide adhesion on the ceramic fiber and airgel aggregation structure to prepare a polyimide/ceramic fiber/airgel composite board with high strength, high heat resistance, and low dielectric.

Please refer to Table 1, which illustrates the basic physical properties of the low-dielectric ceramic fiber/airgel composite board prepared by the present invention under impregnation treatment with different polymer solution concentrations; the polyimide concentration is 80wt%, 50wt%, 30wt%, 20wt%, 15wt% polymer solutions impregnated with low dielectric polyimide/ceramic fiber/airgel composites, their codes are respectively PI-80/ceramic fiber/airgel composite material, PI-50/ceramic fiber/aerogel composite material PI-30/ceramic fiber/aerogel composite material, PI-20/ceramic fiber/aerogel composite material, PI-15/ceramic fiber/aerogel composite material Composite materials; in addition, code-named pure airgel composite materials have no added ceramic fibers and have not been impregnated with polymer solutions, while code-named ceramic fiber/airgel composite materials have not been impregnated with polymer solutions.

Table 1 shows that the density of pure airgel composite is 0.123 g/cm ³ , the density of untreated ceramic fiber/airgel composite is about 0.204g/cm ³ , while the density of polyimide/ceramic fiber/ The density of airgel composites increases as the concentration of polyimide polymer solution increases. The densities are respectively 0.366g/cm ³ for PI-15/ceramic fiber/airgel composites and PI-20/ceramic fiber. /Aerogel composite material 0.461 g/cm ³ , PI-30/ceramic fiber/airgel composite material 0.575 g/cm ³ , PI-50/ceramic fiber/airgel composite material 0.678 g/cm ³ ; however, When the concentration of the polyimide solution is increased to about 80wt% (PI-80/ceramic fiber/airgel composite), it is extremely difficult for the polymer solution to penetrate into the airgel, resulting in uneven penetration. In addition, the polyimide solution is extremely difficult to penetrate into the airgel. The viscosity of the imine solution is significantly increased, which can easily cause the airgel sheet to break or the airgel powder to peel off during the processing, causing the airgel sheet to fail to form.

In addition, the thermal conductivity coefficient of pure airgel composite is 0.0249 W/mk, and the thermal conductivity coefficient of ceramic fiber/airgel composite without polymer solution impregnation is 0.0271W/mk. The thermal conductivity coefficient also increases with the increase. The molecular solution concentration increases with the increase, which are 0.0472 W/mk for PI-15/ceramic fiber/airgel composite, 0.0631 W/mk for PI-20/ceramic fiber/airgel composite, and 0.0631 W/mk for PI-30/ceramic fiber/ Airgel composite material 0.1125 W/mk, PI-50/ceramic fiber/airgel composite material 0.1632W/mk; due to the processing of PI-80/ceramic fiber/airgel composite material, the airgel sheet cannot After forming, its thermal conductivity cannot be tested later.

Furthermore, its dielectric properties, including D _K and D _F values, decrease as the test frequency increases. As the test frequency increases from 2GHz to 10GHz, the D _K value of pure airgel sheet decreases from 1.326 to 1.315, and its D _F The value increases from 0.025 to 0.026 as the test frequency increases; the D _K value of the ceramic fiber/airgel composite without polymer solution impregnation decreases from 1.372 to 1.346, and the D _F value increases from approximately 0.0034 dropped to about 0.0026; at the 10GHz test frequency, the D _K and D _F values of the polyimide/ceramic fiber/airgel composite increased as the concentration of the polymer solution increased, and their D _K values were PI-15 respectively. /ceramic fiber/airgel composite 1.350, PI-20/ceramic fiber/airgel composite 1.521, PI-30/ceramic fiber/airgel composite 1.654, PI-50/ceramic fiber/airgel composite Material 1.804; D _F values are PI-15/ceramic fiber/airgel composite material 0.0033, PI-20/ceramic fiber/airgel composite material 0.0041, PI-30/ceramic fiber/airgel composite material 0.0072, PI-30/ceramic fiber/airgel composite material 0.0144; This shows that the ceramic fiber/airgel composite material and the polymer/ceramic fiber/airgel composite material prepared according to the method provided by the present invention are both It has extremely excellent dielectric properties, and its dielectric properties change with the concentration of the impregnated polymer solution. The physical properties of the polymer/ceramic fiber/airgel composite can be controlled through the concentration of the polymer solution.

Based on the above embodiments and examples, the present invention can quickly prepare various low heat transfer and low dielectric electrogel composite materials under normal pressure, including polymer/aerogel composite films, plates or polymer/inorganic Fiber/aerogel composite films and boards; in addition, the preparation method of low heat transfer and low dielectric aerogel composite materials provided by the present invention does not require the addition of a large amount of organic solvents; such as alkanes or aromatic benzene, no need to Lengthy solvent replacement does not require the use of supercritical drying equipment. The overall process is simple and fast, with high process safety and low manufacturing cost.

In summary, the production, application and effects of the present invention should be clearly disclosed. However, the above-mentioned embodiments are only preferred embodiments of the present invention, and should not be used to limit the scope of the present invention. That is, according to the present invention Simple equivalent changes and modifications to the patent scope and invention description are within the scope of the present invention.

(S1): Mixed hydrolysis step (S2): Dispersion and condensation step (S3): Molding step (S4): Drying step (S1”): mixed hydrolysis step (S2”): Dispersion and condensation step (S3”): Forming step (S4”): Drying step (S5”): Step of impregnating polymer solution (S6”): Solvent drying step (S7”): Cross-linking and curing step

Figure 1 is a step flow chart of the first embodiment of the present invention, illustrating the preparation process of the pure aerogel material with both low heat transfer and low dielectric provided by the present invention. Figure 2 is a photo of the appearance of a pure aerogel material and an aerogel/fiber composite material with both low heat transfer and low dielectric prepared according to the first embodiment of the present invention. Figure 3 is an SEM scanning electron microscope observation photograph of the cross section of a pure aerogel plate prepared according to the first embodiment of the present invention, with a magnification of 3000 times. Figure 4 is a SEM scanning electron microscope observation photograph of a cross section of an aerogel/fiber composite material containing a large amount of fibers prepared according to the first embodiment of the present invention, with a magnification of 250 times. FIG. 5 is a step flow chart illustrating the second embodiment of the present invention. Figure 6 is a photo of the appearance of a polymer-containing/airgel composite material with both low heat transfer and low dielectric prepared according to the second embodiment of the present invention. Figure 7 is a cross-sectional SEM scanning electron microscope observation photograph of the low heat transfer and low dielectric/aerogel composite material prepared according to the second embodiment of the present invention, with a magnification of 250 times. Figure 8 is a cross-sectional SEM scanning electron microscope observation photograph of the low heat transfer and low dielectric/aerogel composite material prepared according to the second embodiment of the present invention, with a magnification of 1000 times.

(S1”): mixed hydrolysis step

(S2”): Dispersion and condensation step

(S3”): Forming step

(S4”): Drying step

(S5”): Step of impregnating polymer solution

(S6”): Solvent drying step

(S7”): Cross-linking or curing step

Claims (10)

A method for preparing a low heat transfer and low dielectric electrogel composite material, which includes the following steps: a mixed hydrolysis step: adding a siloxane precursor to an ethanol aqueous solution to form a mixed solution, wherein the siloxane The precursor includes a hydrophobic modified siloxane compound and a siloxane compound, and then an acid catalyst is added to the mixed solution to perform a hydrolysis reaction; the dispersion condensation step: adding a dispersion aqueous solution to the mixed solution, the The dispersed aqueous solution includes an alkali catalyst, and stirring equipment such as an emulsifier is used to uniformly disperse the siloxane molecules and hydrophobic modified siloxane molecules contained in the mixed solution to form a uniform sol solution; forming steps: The sol solution is injected into a model to promote further condensation of the sol solution to form a solid aerogel wet glue structure. The model includes a molding die; the drying step: making the solid aerogel at a drying temperature under normal pressure. The gel wet glue structure is dried to obtain an aerogel material with a uniform structure and both low heat transfer and low dielectric, wherein the drying temperature is between 60 and 150°C; the step of impregnating the polymer solution: preparing a polymer solution, The polymer solution is impregnated into the airgel material with both low heat transfer and low dielectric, so that the polymer chains in the polymer solution can evenly penetrate into the airgel material with both low heat transfer and low dielectric. To form a low heat transfer and low dielectric electrogel material containing a polymer solution, wherein the polymer solution includes: a polymer material, including a thermosetting polymer, and a mixed solvent; the solvent drying step: drying the polymer-containing The low heat transfer and low dielectric electrogel material of the solution vaporizes the mixed solvent at a solvent drying temperature to obtain an airgel network skeleton, wherein: the polymer material is coated on the airgel network skeleton The surface and the solvent drying temperature are between 60 and 115°C; and Cross-linking and curing step: at a specific cross-linking and curing temperature, the molecular chains of the thermosetting polymer contained in the polymer material covering the airgel network skeleton are combined with the airgel network skeleton. The silicon-based aerogel molecules contained in it undergo a cross-linking reaction and combine with each other. Therefore, after the cross-linking curing temperature reaction, the aerogel composite material with both low heat transfer and low dielectric will be obtained. The preparation method as described in claim 1, wherein the drying step sequentially includes: a solvent vaporization step: placing the solid aerogel wet glue structure in an environment with an azeotropic vaporization temperature, so that the solid aerogel The ethanol aqueous solution contained in the wet gel structure is quickly azeotropically vaporized and the ethanol aqueous solution is distilled and dried to obtain a half dry aerogel structure, wherein: the azeotropic vaporization temperature is 60 to 110°C; and the solvent bumping step: Adjust The temperature of the semi-dry airgel structure reaches a bursting temperature, causing trace amounts of solvent and water molecules contained inside the semi-dry airgel structure to rapidly boil and generate a positive vapor pressure, which promotes the semi-dry airgel structure to inhibit drying shrinkage And generate a large number of micropores to obtain the airgel material with both low heat transfer and low dielectric, wherein the burst temperature is 110 to 150°C. The preparation method as described in claim 1, wherein in the cross-linking and curing step: when the thermosetting polymer is epoxy resin (Epoxy), the cross-linking and curing temperature is 150 to 180°C; or when the thermosetting polymer is When using polyimide, the cross-linking curing temperature is 120 to 325°C. The preparation method according to claim 1, wherein the siloxane compound includes tetramethoxysilane (TMOS), tetraethoxysilane (TEOS) or a combination thereof; the hydrophobic modified siloxane The compound includes methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES) or a combination thereof, wherein in the siloxane precursor, the siloxane compound and the hydrophobic modification The content molar ratio of the siloxane compound ranges from 0:100 mol% to 40:60 mol%. The preparation method according to claim 1, wherein the ethanol aqueous solution contains (1) ethanol, and (2) deionized water, distilled water or double distilled water. The preparation method as claimed in claim 1, wherein the forming mold contains a fiber material, and the fiber material includes glass fiber, ceramic fiber, rock wool fiber, polypropylene fiber, nylon fiber or polyester fiber; or the The fiber material is porous mat-like, paper-like, blanket-like, rope-like, plate-like or a combination thereof. The preparation method according to claim 1, wherein the polymer solution contains 0.01wt% to 80wt% of polymer solute. The preparation method according to any one of claims 1 to 7, wherein the thermosetting polymer includes epoxy resin, polyimide, polyetherimide, polyphenylene ether, polyphenylene sulfide, polyetherketone , phenolic plastic ester, polymelamine-formaldehyde plastic ester or a combination thereof; the thermoplastic polymer includes polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, polyamide, polyamide ester, polyester or its combination combination. The preparation method as described in any one of claims 1 to 7, wherein the electrogel composite material with both low heat transfer and low dielectric is a porous structure with a porosity between 40.0 and 95.0% and a density between 40.0% and 95.0%. At 0.180 to 0.600g/cm ³ , the thermal conductivity k of a pure airgel film or plate ranges from 0.013 to 0.018W/mk, its dielectric constant ranges from 1.20 to 1.87, and its dielectric loss ranges from 0.0026 to 0.0078. The preparation method as described in claim 1, wherein the electrogel composite material with both low heat transfer and low dielectric is used for fire protection of 5G communications, microwave circuits, or electric vehicle lithium battery modules.

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