TWI864435B - Low-k dielectric aerogel/polymer composite film preparation method - Google Patents

Abstract

The aerogel powder mixed with organic solvent is dispersed to form an aerogel suspension dispersed solution, which can be uniformly aerogel/polymer solution with mixed various types of polymers or plastics solution by mixer, and then coated into an aerogel/polymer composite film, the steps of which comprises : organic solvent suspension dispersion, polymer solution mixing, coating or casting the film and drying and rolling up the film. The prepared organic solvent suspension aerogel powder dispersion can be uniformly mixed with the polymer solution into a uniform aerogel/polymer solution by mixer matching, and then the use of coating, casting, extrusion and other processes are made into various thicknesses of aerogel/polymer composite film, the aerogel/polymer composite film has a low thermal insulation and low dielectric properties, can be applied in high-frequency circuit dielectric layer, semiconductor device insulation layer, or communication mobile phone, computer and other applications.

Description

Preparation method of low dielectric gel/polymer composite film

The present invention relates to an aerogel/polymer composite film, and more particularly to an aerogel powder with low dielectric constant and low heat transfer coefficient and a method for preparing the aerogel/polymer composite film.

It is known that the dielectric properties of materials gradually decrease as the porosity inside the material increases. Therefore, aerogel materials and their related composite materials will become low-dielectric related products required by the 5G industry. As is known to all, aerogel is a porous material with a three-dimensional network structure, with a porosity higher than 80% (even higher than 95%), and has low density (about 0.005 to 0.2g/ ^cm3 ), high specific surface area (500 to ^2000m2 /g), low thermal conductivity (k=15 to 40mW/mk), low dielectric properties ( _Dk = 0.1 to 2.5), low dielectric loss ( _Df <0.001) and other characteristics. Due to the excellent properties of aerogel materials, they can be used in high-temperature insulation, cold insulation, sound insulation or low dielectric industry applications. Since the size of the pores inside porous aerogels is only a few nanometers to tens of nanometers, aerogels have lower thermal conductivity and thermal convection properties. Therefore, the higher the porosity in the material structure of inorganic or organic aerogels, the lower the thermal conductivity and dielectric properties of the material. Therefore, in the future, industries such as petrochemical pipelines, metal smelting, building fire protection and insulation, 5G low dielectric, and electric vehicle high-frequency signal transmission will all require porous aerogels as the preferred product for industrial applications. However, the current aerogel manufacturing process requires the use of a large amount of alcohol, ammonia and a large amount of hydrophobic solvents (such as n-hexane, cyclohexane, benzene, toluene, xylene, etc.) for mixing and solvent hydrophobic replacement, and the use of surfactants to prevent obvious shrinkage and cracking in the aerogel manufacturing process. Therefore, although adding a large amount of organic solvents and surfactants in the process has its effects, it greatly increases the overall aerogel manufacturing cost and leads to defects in subsequent applications; such as cracking and odor in a high temperature environment, and the large amount of impurities and ions in the product will affect the dielectric properties of the product.

Due to its high porosity and extremely low density, aerogels are highly applicable in applications such as high thermal insulation, cold insulation, sound insulation or low dielectric properties. In the process of gradually moving towards the 5G era, high-frequency transmission applications urgently need dielectric materials with low dielectric constants ( D _k ＜2.5) and low signal loss ( D _f ＜0.001). The porosity of the material will reduce the transmission properties of electronic and electromotive forces. Therefore, the higher the porosity in the structure of inorganic or organic materials, the lower its dielectric properties. Therefore, 5G high-frequency applications require porous aerogel materials as the main basic materials for high thermal insulation, cold insulation, sound insulation and low dielectric properties.

According to Japanese Patent Publication No. 8-228105, a method for manufacturing a semiconductor device is disclosed. In this method, a wet gel film is formed on a substrate, and a solvent containing the wet gel film is evaporated by a supercritical and subcritical drying process to form an aerogel film. The prepared dry aerogel film still maintains the mesh structure of the wet gel 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, the use of supercritical or subcritical drying processes in the transistor structure process will lead to disadvantages such as complicated processes 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 under the supercritical state. Therefore, the residual solvent in the network structure can be removed under supercritical conditions without causing the wet glue to shrink. 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 the aerogel solution, the silicone molecules will immediately aggregate and condense, which will cause the viscosity of the aerogel solution to increase with time. When spin coating is performed at a fixed rate, the film thickness on the substrate will also increase. Similarly, the thickness of the transistor thin film structure coating will vary as the process time increases, so it is impossible to produce a high-quality transistor thin film structure.

The traditional method for preparing aerogels is the sol-gel synthesis method, which mainly involves mixing precursors such as alkoxysilane, methyl orthosilicate or water glass with an organic solvent, and then adding an acid catalyst to carry out a hydrolysis reaction. After the hydrolysis reaction has been going on for a certain period of time, an alkaline catalyst is added to carry out a condensation reaction. During the condensation reaction, a sol is gradually formed, and the molecules in the sol 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, solvent replacement is performed using n-butanol, n-hexanol, n-hexane or cyclohexane, and the solvent in the aerogel structure is extracted and dried using supercritical drying technology. In addition to consuming a large amount of expensive organic solvents and supercritical equipment, traditional process technology also requires the use of alcohols or alkanes for a long time for solvent replacement, so the preparation of aerogels is costly and time-consuming.

On the other hand, the preparation method of hydrophobic aerogel also adopts the sol-gel synthesis method, which mainly involves mixing methyl alkoxy silicon precursors such as methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES) with an organic solvent, and then adding an alkaline catalyst to perform a hydrolysis reaction. After the hydrolysis reaction has been carried out for a certain period of time, a condensation reaction is carried out, and a sol is gradually formed during the condensation reaction. The molecules in the sol continue to react and bond, gradually forming a semi-solid polymer gel. After a period of aging, solvent replacement is performed for two to three days using solvents such as isopropyl alcohol, acetone, n-hexane or cyclohexane to form a stable three-dimensional network structure. Finally, the solvent in the aerogel structure is dried using atmospheric pressure drying technology to obtain a porous dry aerogel block. The process of hydrophobic aerogel also consumes a large amount of expensive organic solvents and solvent replacement with alcohols or alkanes for a long time, so the preparation is time-consuming and costly.

Since the process technology used in the above-mentioned aerogel preparation methods requires the use of organic solvents for reaction and multiple solvent replacement for two to three days, and then supercritical drying technology or atmospheric pressure high temperature drying technology is used to prevent the aerogel structure from shrinking or cracking due to the surface tension of water molecules during the atmospheric pressure drying process. However, multiple solvent replacement technology and supercritical drying technology are very time-consuming and costly, which is not conducive to the mass production of aerogels and the competitiveness of future applications.

According to the Republic of China Invention Publication No. TW 201542457, "Flexible Composite Aerogel and Manufacturing Method" mainly involves a direct dispersion preparation method of a hydrophilic aerogel. The method is related to a flexible composite organic aerogel, which includes: a textile reinforcement, and an organic aerogel is placed in the textile reinforcement. The organic aerogel is based on a resin at least partly produced from polyhydroxybenzene and formaldehyde, the organic aerogel is a polymerized organic gel containing at least one water-soluble cationic polyelectrolyte, or the organic aerogel is a thermal decomposition product of the gel in the form of a porous carbon monolith, which contains the thermal decomposition product of the at least one water-soluble cationic polyelectrolyte.

According to the invention publication number TW I655094 of the Republic of China, "Aerogel composite and method for preparing the aerogel composite", mainly relates to an aerogel composite. The aerogel composite comprises at least one base layer having an upper surface and a lower surface, the base layer comprises a reinforced aerogel composition and the aerogel composition comprises a reinforcing material and a single aerogel frame; a first covering layer, which comprises a first covering material adhered to the upper surface of the base layer; and a second covering layer, which comprises a second covering material adhered to the lower surface of the base layer. At least a portion of the single aerogel frame of the base layer extends into a portion of both the first covering layer and the second covering layer. The first covering material and the second covering material may each include elastic fibers such as spandex, nylon, lycra, elastic fibers, or a combination thereof, or may be mainly composed of elastic fibers. However, since the prepared aerogel covering material includes elastic fibers or soft polymer films, and the adhesive material used is also an organic adhesive such as acrylate, urethane, hot melt adhesive, etc., although the relevant soft products have good protection for aerogel.

According to the invention publication number TW I663062 of the Republic of China, "Aerogel composite and its preparation method" is related to a fiber material comprising at least one of inorganic fiber and organic fiber being wetted; the wetted fiber material and a spacer are layered on a plane in a roll-up structure; the fiber material is filled into a container; a front drive is used to The invention relates to a method for preparing a gel-fiber composite by injecting a precursor into the container and gelling the precursor while removing residual bubbles under vacuum; taking out the aerogel-fiber composite from the container and removing the separator; substituting and organically surface modifying the gel-fiber composite by solvent, and then drying the organically surface-modified gel-fiber composite by atmospheric pressure drying or supercritical drying.

According to the invention publication number TW I743082 of the Republic of China, the "laminated body comprising a reinforced aerogel composite material" relates to an aerogel composite material. The aerogel composite material comprises at least one base layer having a top surface and a bottom surface, the base layer comprising a reinforced aerogel composition and a single-piece reinforced aerogel frame, the composition comprising a reinforcing material, a first surface layer comprising a first surface material attached to the top surface of the base layer, and a second surface layer comprising a second surface material attached to the bottom surface of the base layer. At least a portion of the single-piece aerogel frame of the base layer extends to at least a portion of both the first surface layer and the second surface layer. The first side material and the second side material are each substantially composed of a fluoropolymer material.

According to the invention publication number TW I765609 of the Republic of China, "A method for manufacturing aerogel felt", it involves a method for manufacturing aerogel felt, which first injects aerogel slurry into glass fiber felt, and then uses soaking liquid to form a closed coating on the surface of the glass fiber felt to prevent the aerogel felt from falling off during storage and use. Therefore, it can be ensured that the amount of aerogel in the aerogel felt does not decrease, and thus does not affect the thermal insulation performance of the aerogel felt. Among them, the surface closed coating is a mixture of acrylic emulsion, talcum powder, VAE emulsion and water-based curing agent.

According to the invention of the team in the Republic of China, the public number TW The "non-woven/aerogel composite fireproof/heat-insulating material and its preparation method" described in I535658 technology is to prepare an aerogel through a hydrolysis step and a condensation step, and then take the aforementioned aerogel and add it to a non-woven fabric during the molding step, so that the aforementioned aerogel is fully interspersed in the non-woven fabric, and undergo a drying process to form a non-woven/aerogel composite fireproof/heat-insulating material. The aerogel is fully interspersed in the non-woven fabric through an impregnation processing method or a continuous rolling method; the conditions of the drying process are to dry the water-free aerogel at room temperature and pressure, or to use the rapid vaporization drying of the organic solution between 30 degrees Celsius and 80 degrees Celsius.

According to the U.S. Patent Publication No. US8,945,677B2, it discloses "manufacturing electronic devices using low-K dielectric materials", mainly using low-dielectric materials (including polyimide aerogel) to manufacture electronic devices and semiconductor components. This patent provides a method for manipulating the properties of dielectric materials and affecting the overall dielectric properties of the system. Specifically, a polyurethane polyimide presolvent, a catalyst and a polar solvent are mixed into a sol mixture layer, and then the sol components are cross-linked to form a wet gel material, and the solvent is removed using a supercritical fluid to form a polyimide aerogel film. This technology is used to combine it with a polyimide aerogel film on the surface of a non-porous, 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 stages through pressure circulation. The overall technology is time-consuming and costly, and the process takes too long and is not cost-effective.

According to the Chinese invention patent publication number CN105189104A, it discloses "aerogel insulation panel and its manufacturing", which mainly uses polyimide aerogel to prepare an insulation panel, which can be applied to aerospace application laminated panels. This panel includes a polyimide aerogel surface layer and a reflective protective layer on the surface layer. The process of making polyimide aerogel in this patent includes: (a) polymerizing a mixture of dianhydride and diamine monomers in a bipolar alkaline solvent (DMAc or NMP) to form a polyimide solution; (b) casting the polyimide solution into fiber flocs; (c) using acetic anhydride and pyridine to gel the polyimide solution by chemical imidization reaction; (d) using supercritical or subsupercritical _CO2 drying technology to remove the solvent in the gel to form a fiber/polyimide aerogel composite. The overall technology is time-consuming and costly, and the process takes too long, which is not cost-effective and competitive.

According to the Chinese invention patent publication number CN108203516A, a method for preparing cross-linked polyimide aerogel is disclosed, which mainly adopts a sol-gel method, which includes: (a) polymerizing a mixture of dianhydride and diamine monomers in a dipolar alkaline solvent (DMAc or NMP) to form a polyimide solution; (b) casting the polyimide solution on fiber flocs; (c) using acetic anhydride and pyridine to gel the polyimide solution by chemical imidization reaction; (d) using supercritical or subsupercritical CO ₂ Drying technology removes the solvent in the gel to form a fiber/polyimide aerogel composite. The overall technology is also time-consuming and costly. The process takes too long and is not cost-effective and competitive.

In the traditional manufacturing technology of porous aerogels, 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. Therefore, the process requires a long time of solvent replacement and rinsing with deionized water to maintain the stability of the aerogel structure during the drying process to produce products with appropriate low dielectric properties. In addition, the use of supercritical or sub-supercritical _CO2 drying technology to remove the solvent in the gel can effectively produce high-quality aerogel materials.

In addition, a polyimide solution is combined with a supercritical or subsupercritical _CO2 drying technique to remove the solvent in the polyimide gel to prepare a pure polyimide aerogel or a fiber/polyimide aerogel having a large number of pore structures. However, the dielectric constant of the polyimide aerogel prepared by the related technique cannot be significantly reduced to 3.5, and its dielectric loss remains at 0.003. This is because the chemical structure of polyimide contains a large number of dipole structures and hydrophilic groups, and therefore the dielectric constant or dielectric loss of the material cannot be significantly reduced.

According to the "Low Dielectric Aerogel and Its Preparation Method" technology disclosed by the applicant in Taiwan Patent Application No. 110106194, the linear shrinkage rate of the bulk aerogel preparation is reduced by using the rapid condensation technology, and the aerogel wet gel does not need to be immersed in a solvent for solvent replacement, so the aerogel structure can be prepared quickly. This prior art uses the rapid gelation technology to form the gel structure quickly, and rinses it in deionized water to remove ions in the structure to reduce ion accumulation in the subsequent application process. In addition, the steps of immersing the wet gel film in liquid and removing the solvent using supercritical fluid technology are removed from the overall process, and surprisingly, a porous low-dielectric film can be obtained by aging in about a few minutes. However, the use of deionized water for washing the aerogel material will also waste a lot of process time and produce a large amount of washing waste water.

Therefore, in order to improve the shortcomings of the past low-dielectric aerogel product process and to mass-produce low-dielectric and high-purity (low impurity content) aerogel submicron powder, the preparation method provided by the present invention can be used to prepare extremely low dielectric loss (<0.001) aerogel powder; in addition, during the preparation process, the powder is suspended and dispersed with a photoelectric grade organic solvent to form an aerogel suspension solution, and the aerogel suspension solution is mixed with various polymer solutions to adjust the dielectric constants and dielectric loss of aerogel/polymer composites. The related products can be applied to future 5G high-frequency electronic components. The present invention can improve the shortcomings of current 5G application product preparation, such as uneven low-dielectric aerogel structure, unclear reduction in aerogel dielectric properties or dielectric loss, and difficulty in applying supercritical drying technology to the preparation of integrated circuit structures.

There are currently two major technical difficulties in the preparation of aerogels mixed with polymer solutions: First, during the mixing process of low-density aerogels (0.01±0.05g/cm ³ ) and polymer solutions (1.0±0.3g/cm ³ ), the density difference between the aerogel and the polymer solution causes the aerogel to be unable to disperse with the polymer solution and form agglomerates; second, aerogel is a porous material, and during the mixing process with the polymer solution, the aerogel will also absorb the polymer solution and penetrate into the aerogel structure, causing the pores of the aerogel to be filled with polymers and disappear, resulting in the loss of the pore structure of the aerogel. Therefore, this patent hopes to improve the above shortcomings and develop a manufacturing technology and a film-forming technology that can be evenly mixed with the polymer solution and avoid the polymer solution from penetrating into the pores of the aerogel.

The present invention provides aerogel powder with low dielectric and low thermal conductivity coefficients on one hand, and a method for preparing aerogel/polymer film on the other hand. In the preparation of the aerogel powder with low dielectric and low thermal conductivity coefficients, a sol-gel synthesis technology with low content of organic solvent (such as ethanol and other solvents) and extremely low acid and alkaline catalyst concentration is used, and a process technology for preparing high-purity, low dielectric and low thermal conductivity aerogel powder without adding surfactants and other additives is used, which includes the following steps: (1) a mixed hydrolysis step: a siloxane compound (such as TEOS) or a hydrophobic modified siloxane compound (MTMS) or a mixture thereof is added in a trace acid catalyst and a large amount of recovered solvent (including water, ethanol, and other trace organic solvents) or a new The solvents are mixed into a uniform solution, and the hydrolysis reaction is carried out during the mixing process; (2) Condensation and decomposition step: the hydrolyzed silicon molecule solution is added to a large amount of recovery solvent (including water, ethanol, and other trace organic solvents) or a large amount of dispersion solution containing a trace amount of alkali catalyst, and the hydrolyzed silicon molecule solution is dispersed into nanometer to sub-micrometer suspended water droplets in a large amount of dispersion solution (containing a trace amount of alkali catalyst) under high-speed stirring and dispersion using an emulsifier, homogenizer, turbo mixer, etc., and the nanometer to sub-micrometer suspended water droplets are subjected to condensation reaction under the catalysis of the trace amount of alkali catalyst under high-speed stirring and dispersion conditions to obtain aerogel wet gel particles. The present invention can utilize stirring speed, condensation reaction rate, hydrolysis solution content, dispersion solution content, etc. to control the particle size and internal microstructure of the prepared aerogel wet gel particles; (3) Solvent drying and recovery step: After the gel structure of the aerogel wet gel particles is stabilized, high temperature drying is then performed under normal pressure and slow stirring conditions. The solvent in the aerogel wet gel structure is evaporated and dried using the azeotropic theory in a high temperature environment, and the vaporized solvent is condensed and recovered using a recovery device. The recovered solvent can be reused in the mixed hydrolysis and condensation separation steps. Finally, the drying temperature is increased to vaporize the trace solvent inside the aerogel instantly and generate a vapor pressure that causes the aerogel structure to expand, thereby obtaining aerogel powder with higher porosity and higher purity.

In addition, in order to solve the problem that the low-density aerogel powder and polymer solution are not evenly mixed and the polymer solution easily penetrates into the aerogel body in the current preparation technology of low-dielectric aerogel/polymer composite materials or composite membranes; in particular, the hydrophobic aerogel powder and various polymer solutions are almost impossible to disperse in the mixture. Therefore, in another embodiment of the present invention, the aerogel powder dried to 80% to 95% dryness (slightly containing solvent) is mixed with an organic solvent to form an aerogel suspension containing an organic solvent. The aerogel powder slightly containing solvent can be easily and evenly mixed with various polymer solutions matching the solvent to form a uniform aerogel/polymer suspension solution without agglomeration. The process technology includes the following steps: (4) organic solvent suspension dispersion step: the previously dried aerogel powder or the slightly wet aerogel powder dried to 80% to 95% dryness is suspended and dispersed in an organic solvent; such as toluene, butanone, anhydrous alcohol or other solvents, so that the aerogel powder forms a uniformly dispersed aerogel suspension dispersion in the organic solvent; (5) polymer solution mixing step: the uniformly dispersed aerogel suspension dispersion is mixed with a polymer solution in the same solvent; such as toluene, butanone, anhydrous alcohol or other solvents; such as a polyphenylene ether (PPE) solution, polytetrafluoroethylene (PTFE) solution in toluene solvent; solution; epoxy resin solution in butanone solvent; polyimide (PI) solution in anhydrous alcohol, and aqueous acrylic (PMMA) solution or aqueous polyurethane (PU) solution in water solvent, etc., which can simply make the uniformly dispersed aerogel suspension dispersion and various polymer solutions matched with the solvent mixed to form a uniformly dispersed aerogel/polymer solution; (6) coating and film forming step: the uniformly dispersed aerogel/polymer solution is coated or formed by coating technology, laminating technology, extrusion technology or film drawing technology, and then further subjected to high temperature rolling. The step of drying and shaping the film thickness by using a roller to form an aerogel/polymer surface wet-dry film or an aerogel/polymer surface wet-dry thick film of uniform thickness; and (7) drying and rolling up step: finally using an exhaust heating channel or a plurality of sets of heating rollers to dry and shape the aerogel/polymer surface wet-dry film or the aerogel/polymer surface wet-dry thick film of uniform thickness, and then rolling up the dried and shaped aerogel/polymer film or the aerogel/polymer membrane by using a conventional rolling-up device, so that an aerogel/polymer film or an aerogel/polymer membrane can be obtained by using this process technology.

The process technology of the present invention can quickly produce high-purity and low-dielectric-constant aerogel powder or aerogel/polymer film or aerogel/polymer membrane. In the aerogel powder process, no surfactant, metal oxide or other additives are added, and the acid-base catalyst ion content is controlled at an extremely low concentration in the process. In the process, no solvent replacement, water washing or supercritical drying is required. The overall process is simple, the aerogel manufacturing cost can be significantly reduced, and a high-purity aerogel powder product can be obtained. On the other hand, the process technology of the present invention provides another embodiment that can be quickly and easily mixed with a polymer solution uniformly to prepare aerogel/polymer films of tens to hundreds of microns or aerogel/polymer sheets of several millimeters to centimeters in thickness. The overall composite processing process is simple, fast, economical, and the product has a higher purity, thereby improving the production efficiency of low-dielectric high-purity aerogels and aerogel/polymer composite films or composite thick sheets.

Further, the alkoxysilane compound is one or more selected from the group consisting of tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS), and the hydrophobic modified alkoxysilane compound is one or more selected from the group consisting of methyltrimethoxysilane (MTMS) and methyltriethoxysilane (MTES). ); the addition of the siloxane compound in the present technology is mainly to provide and regulate the porosity inside the aerogel and the microstructure of its gel network structure. Therefore, the higher the content of the siloxane compound added in the present technology, the higher the porosity inside the aerogel and the more complete the aerogel network structure, but its shrinkage rate will also be significantly improved; on the contrary, the addition of the hydrophobic modified siloxane compound is mainly to reduce the shrinkage and turtle cracking phenomenon produced by the aerogel structure during the drying process. Therefore, the higher the content of the hydrophobic modified siloxane compound added in the present technology, the higher the hydrophobic property inside the aerogel and the low dielectric property of the aerogel product is improved, but the porosity inside the aerogel particles decreases.

Furthermore, in the mixed hydrolysis step, 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 dielectric properties under the action of the electric field, thereby improving the dielectric properties of the aerogel, that is, the dielectric loss of the aerogel will be higher. In contrast, the lower the content ratio of the acid catalyst, the slower the overall hydrolysis rate. In this technology, the temperature can also be increased to increase the hydrolysis rate of the acid ions. In addition, in the preparation process, deionized water or process recovery solvents are used to prepare the aerogel, which can reduce the influence of related ions on the dielectric properties of the aerogel.

Furthermore, in the dispersion and condensation step, an emulsifier, a homogenizer, a turbo mixer or other fast stirring machine is used to accelerate the hydrolysis of the silicon molecule dispersion solution to disperse into nanometer-scale to sub-micrometer-scale silicon-containing molecules to form round fine water droplets under high-speed stirring, and a trace amount of alkaline catalyst is added in the dispersion and condensation step to accelerate the condensation of the sub-micrometer-scale silicon-containing molecules dispersed in the round fine water droplets under the catalysis of the alkaline catalyst, thereby promoting the condensation of the silicon-containing molecule dispersion solution to form a sol and further form a stable gel. In addition, a small amount of organic solvent compatible with the aerogel surface is added during the process, so that the solvent forms an organic solvent liquid film on the aerogel surface, and then a dispersing solvent incompatible with the organic solvent is used for condensation dispersion. Therefore, a large amount of dispersing solvent is used to prevent the condensed aerogel structure from aggregating the round fine water droplets in the solution condensation reaction to form a single round fine wet gel particle of the aerogel. In this dispersion and condensation step, it is not necessary to add emulsifiers, surfactants or suspension dispersion stabilizers. It is not necessary to add various additives during the preparation process, and the purity of the aerogel product is the highest.

Furthermore, in the solvent drying and recovery step, the gelled and stabilized aerogel spherical fine wet gel particle dispersion solution is first filtered to remove most of the dispersion solvent, and the dispersion solvent is recovered and reused. The filtered aerogel spherical fine wet gel particles are subjected to azeotropic evaporation of the solvent inside the aerogel particles under normal pressure and high temperature environment. Therefore, the solvent content in the solvent drying and recovery process of this technology is significantly reduced, the process is safer and a high-purity aerogel product can be prepared. The low-density and high-porosity aerogel powder prepared by this technology does not contain any impurities inside or on the surface, so the product has excellent low dielectric constant and low dielectric loss.

Furthermore, according to the preparation method provided by the present invention, wet aerogel spherical fine wet gel particles can be further prepared, wherein the aerogel spherical fine wet gel particles contain only 3-10 vol% of a trace solvent, and the aerogel spherical fine wet gel particles are particularly suitable for improving the problem of uneven dispersion when lightweight aerogels are mixed with various polymers or polymer concentrated solutions. The preparation method is that, according to the organic solvent compatible with the mixed polymer, the aerogel spherical fine wet gel particles in the drying process can be subsequently quickly suspended and dispersed to form an aerogel suspension containing an organic solvent.

Furthermore, the organic solvent suspension dispersion step is as follows: the dried aerogel powder or the slightly solvent-containing wet aerogel spherical fine particles dried to 80% to 95% dryness is dispersed by using an organic solvent that is similar to the surface of the aerogel spherical fine particles but repellent to the inside of the aerogel spherical fine particles, utilizing the affinity and repulsion of the mixed solvent inside the aerogel spherical fine particles and the fine particles surface, so as to promote the aerogel spherical fine particles to form a uniformly dispersed suspension during the dispersion process.

Further, the polymer solution mixing step: the uniformly suspended and dispersed aerogel spherical fine particles are mixed with a polymer solution using a solvent having a similar surface solubility parameter or compatibility to the aerogel particles; for example, the polymer solution of the solvent is toluene, xylene, hexane and methyl pyrrolidone, etc. The polymer solution may be polyphenylene ether (PPE) solution, polytetrafluoroethylene (PTFE) Another example is a polymer solution whose solvent is butanone, dimethylacetamide and methyl pyrrolidone, such as epoxy, acrylic (PMMA) solution, polyurethane (PU) solution, etc. Another example is a polyimide acid (PAA) solution whose solvent is ethanol or anhydrous ethanol; and finally, a water-based acrylic (PMMA) solution or a water-based polyurethane (PU) solution whose solvent is water. The above can be used to easily mix the uniformly dispersed aerogel round fine particles with the polymer solution that matches or is compatible with the surface to form a uniformly dispersed aerogel/polymer composite solution.

Furthermore, the coating and film-forming step: the uniformly dispersed aerogel/polymer composite solution can be coated or coated by coating, pressure suction, laminating, extruding or film drawing techniques to form an aerogel/polymer wet film or aerogel/polymer wet film of uniform thickness, and then further dried the surface of the aerogel/polymer wet film or aerogel/polymer wet film and fixed the film thickness by using a vacuum infrared heating plate, a UV curing machine or a plurality of high-temperature rollers.

Furthermore, the drying and rolling step: finally, the uniform thickness of the formed aerogel/polymer surface wet-dry film or aerogel/polymer surface wet-dry thick film is finally dried and shaped by using an exhaust high-temperature heating channel or multiple sets of high-temperature heating rollers, and then the dried and shaped aerogel/polymer film or aerogel/polymer film is rolled up using a traditional rolling device. By using this process technology, an aerogel/polymer film or an aerogel/polymer film can be obtained. The above preparation technology can be used to prepare low-dielectric aerogel composite materials such as low-dielectric layers in high-frequency circuits, insulating layers in semiconductor devices, or microwave circuits in communication integrated circuits.

Furthermore, in the low-dielectric aerogel composite material, the higher the low-dielectric aerogel content in the preparation process, the greater the content of the internal pores in the aerogel, the better the dielectric properties, and the worse the physical properties of the low-dielectric aerogel composite material such as strength, toughness, and rigidity; on the other hand, the lower the low-dielectric aerogel content, the higher the polymer content in the low-dielectric aerogel composite material, the better the physical properties of the low-dielectric aerogel composite material, and the worse the low dielectric properties. Therefore, the properties of the product can be adjusted by adding the low-dielectric aerogel content.

In general, the process is simple, low in manufacturing cost, fast in process speed, and does not require long solvent replacement and long water washing steps, nor does it require complex process technologies such as supercritical drying. The batch process speed of the developed aerogel composite sheet can be shortened to a few hours, or aerogel polymer composite films or sheets can be prepared in a continuous production method, thereby improving production efficiency.

The present invention has the following effects:

1. The preparation method provided by the present invention modifies the traditional sol-gel reaction process for preparing aerogel powder. Since it is not necessary to add a large amount of organic solvents, emulsifiers, surfactants, suspension dispersion stabilizers, adhesives and other substances in the process, it is not necessary to use long-term solvent replacement or use deionized water to extract various impurities or ions in the process. Therefore, the overall process is simple and has economic competitive advantages.

2. The preparation method provided by the present invention utilizes rapid dispersing equipment such as an emulsifier and a homogenizer in combination with a very small amount of hydrophobic solvent and a large amount of ethanol-containing deionized water to perform rapid suspension dispersion during the condensation dispersion process, so that the hydrolyzed solution containing the siloxane compound forms a suspended dispersion of aerogel spherical fine wet gel particles under rapid dispersion. In this technology, in addition to utilizing the aerogel spherical fine solution beads to gradually form solid-like gel fine particles during the gelation process, the difference in compatibility between the solvent in the aerogel spherical fine wet gel particles and the large amount of dispersing solvent is also utilized to form stable gel fine particles. Therefore, in this process, there is no need to add emulsifiers, surfactants, suspension dispersion stabilizers, and aerogel powder with high purity and excellent low dielectric properties can be easily prepared.

3. In the preparation method provided by the present invention, the porosity, pore size and density of the aerogel structure can be easily adjusted by using factors such as different ratios of siloxane compounds or hydrophobically modified siloxane compounds, the content of a large amount of hydrolysis solvent, the content and ratio of acid catalyst and alkali catalyst, etc. In addition, by using the stirring rate of dispersing equipment such as emulsifiers and homogenizers in combination with the content of a large amount of dispersing solvent, the size of aerogel particles and the agglomeration properties between particles can be easily adjusted to improve the practical properties of aerogel.

4. In the preparation method provided by the present invention, the mixed solvent inside the aerogel spherical fine particles containing a slight amount of solvent and the affinity and repulsion of the fine particles on the surface are utilized, and an organic solvent similar to the surface of the aerogel spherical fine particles but repellent to the inside of the aerogel spherical fine particles is utilized to disperse the aerogel spherical fine particles, thereby promoting the aerogel spherical fine particles to form a uniformly dispersed suspension during the dispersion process. The solvent-containing aerogel spherical fine particle suspension dispersion can be further mixed with various polymer organic solutions to prepare a uniformly dispersed aerogel/polymer composite solution, and then a uniform low-dielectric aerogel/polymer composite material can be quickly prepared, especially a low-dielectric aerogel/polymer composite product for 5G or 6G high-frequency applications.

5. In the preparation method provided by the present invention, a suspension dispersion of slightly solvent-containing aerogel spherical fine wet gel particles containing an organic solvent is mixed with a polymer solution, so that the aerogel suspension and the polymer chain are uniformly dispersed in a solvent environment to prepare an aerogel/polymer composite material containing aerogel particles. The low dielectric properties of the aerogel/polymer composite material change significantly with the increase of the internal pores or aerogel content of the material. When the polymer content is lower, the polymer mixed aerogel content is higher, and the internal pore efficiency of the aerogel/polymer composite is better, the low dielectric property is significantly reduced; but the physical properties of the aerogel/polymer composite are reduced; on the contrary, the higher the polymer content in the aerogel/polymer composite, the better the strength of the prepared low dielectric aerogel/polymer composite. Therefore, the low dielectric constant and strength of the prepared low dielectric aerogel/polymer composite can be further adjusted by the content of aerogel and polymer solution.

6. In the preparation method provided by the present invention, various polymer solutions can be mixed to prepare low dielectric aerogel/polymer composite materials with different properties, so as to adjust the strength, durability temperature, bonding with other materials, product dielectric constant (approximately 1.3 to 2.5) and dielectric loss (0.0005 to 0.001) of the low dielectric aerogel/polymer composite materials.

7. In the preparation method provided by the present invention, the added acid catalyst and alkaline catalyst can accelerate the hydrolysis and condensation reaction of siloxane and hydrophobically modified siloxane. The molar ratio of the total content of the mixture of siloxane and hydrophobically modified siloxane to the content of the acid catalyst in the reaction system is 1:0.001 to 1:0.00005; and the molar ratio of the acid catalyst to the alkaline catalyst in the condensation reaction is 1:0.7 to 1:1.8. The higher the content of acid catalyst and alkaline catalyst in the mixed solution, the faster the reaction rate; conversely, the higher the content of acid catalyst and alkaline catalyst, the higher the ion content in the overall aerogel structure, and the greater the dielectric loss of the aerogel, thereby regulating the process rate and product properties.

Please refer to FIG. 1, which is an implementation of a method for preparing a low dielectric aerogel powder and aerogel/polymer composite film provided by the present invention, wherein the steps include: a mixing and hydrolysis step (S1), a condensation and separation step (S2), a solvent drying and recovery step (S3), an organic solvent suspension and separation step (S4), a polymer solution mixing step (S5), a coating and film forming step (S6), and a drying and rolling step (S7), wherein:

Mixing and hydrolysis step (S1): a siloxane compound or a hydrophobic modified siloxane compound is mixed with a large amount of an ethanol aqueous solution containing a trace amount of an acid catalyst, and a hydrolysis reaction is carried out during the mixing process to form a hydrolysis solution containing silicon molecules, wherein the siloxane compound (alkoxysilane) comprises tetramethoxysilane (TMOS), tetraethoxysilane (TEOS) or a combination thereof, and the hydrophobic modified siloxane compound comprises hydrophobic methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES) ) or a combination thereof; the purpose of adding the hydrophobic modified siloxane is to reduce the cracking phenomenon of the aerogel structure during the drying process, and the purpose of adding the siloxane is to adjust the internal microstructure of the aerogel structure to increase the pore content in the structure; in some embodiments, for the overall mixed solution, the total molar percentage of the siloxane compound and the hydrophobic modified siloxane is between 0.5mol% and 50mol%, and the total molar percentage of the micro-solvent and ethanol aqueous solution is between 99.5mol% and 50mol%; in some embodiments, the molar ratio of the siloxane compound and the hydrophobic modified siloxane compound is from 0:100 to 45:55; in a preferred embodiment, the molar ratio of the siloxane compound and the hydrophobic modified siloxane compound is 12.5:87.5. In the ethanol aqueous solution, the molar ratio of the slightly contained organic solvent, ethanol and water is from 3:5:92 to 5:45:50; in a preferred embodiment, the molar ratio of the slightly contained organic solvent, ethanol and water is 5:15:80.

In the process of fully mixing the siloxane compound or the hydrophobically modified siloxane compound with a large amount of alcohol water containing a trace amount of an acid catalyst, a hydrolysis reaction is simultaneously carried out, wherein the solvent of the acid catalyst alcohol water solution includes one or a mixture of different compositions of ethanol, deionized water, recycled ethanol solution, recycled distilled water, secondary treatment water, etc., and the total content of the siloxane and hydrophobically modified siloxane mixture is a molar ratio of the content of the acid catalyst. The molar ratio is 1:0.01 to 1:0.00005. The higher the content ratio of the acid catalyst in the mixed solution of the siloxane and the hydrophobically modified siloxane is, the faster the hydrolysis rate is. In other words, the higher the content ratio of the acid catalyst is, the greater the ion content in the overall aerogel structure is, and the greater the dielectric loss of the aerogel will be. In a preferred embodiment, the molar ratio of the total content of the mixture of siloxane and the hydrophobically modified siloxane to the content of the acid catalyst is 1:0.0015.

Condensation and dispersion step (S2): Add the hydrolyzed silicon-containing solution to a large amount of dispersed ethanol aqueous solution containing a trace amount of alkaline catalyst, and combine it with an emulsifier, homogenizer and other high-speed stirring equipment to form nano-scale suspended water beads under high-speed stirring and dispersion conditions, and then perform condensation reaction. reaction), and a condensation reaction is carried out at a condensation reaction temperature by stirring to obtain a low dielectric aerogel dispersion suspension, so that the low dielectric aerogel powder is suspended and dispersed in a suspension solvent; it should be further explained that in the condensation reaction, the condensation reaction temperature can be controlled, and the content of the large amount of dispersed ethanol aqueous solution added can be adjusted to adjust the condensation reaction rate to control the obtained aerogel structure. The large amount of dispersed ethanol aqueous solution added can utilize one or a mixture of different compositions of the ethanol aqueous solution recycled in the process, recycled distilled water, recycled secondary treatment water, and deionized water. In some embodiments, the content of a large amount of dispersed water can accelerate the dispersion of nano-scale to sub-micron-scale silicon-containing molecules to form round micro water droplets to form gelation and accelerate curing. The silicon-containing molecular dispersion solution is forced to condense to form a sol and further to form a stable gel. In addition, a small amount of organic solvent compatible with the surface of the aerogel is added during the process, so that the solvent forms an organic solvent liquid film on the surface of the aerogel, and then a dispersing solvent incompatible with the organic solvent is used for condensation and dispersion. Therefore, a large amount of dispersing solvent is used to prevent the round fine water droplets from agglomerating in the solution condensation reaction to form a single low-dielectric aerogel round fine wet gel particle. In this dispersion and condensation step, no emulsifier, surfactant or suspension dispersion stabilizer needs to be added. In the preparation process, no various additives need to be added, and the purity of the aerogel product is the highest.

In the condensation dispersion, the increase in temperature helps to significantly shorten the condensation reaction time, that is, the gelation time of the aerogel is effectively shortened in the dispersion condensation step (S2); wherein, when the content equivalent ratio of the alkaline catalyst to the acid catalyst is 1.0:1.0, the condensation reaction temperature is 20-55°C, and the condensation reaction time is 20-250 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 increase in the content of the alkali catalyst will also significantly shorten the condensation reaction time, wherein the content equivalent ratio of 1.0M alkali catalyst to 1.0M acid catalyst is 0.8:1.0~2.0:1.0, and the condensation reaction time is 360~about 2 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 is 1.6:1.0. The reaction time is about 5 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 aerogel will be significantly reduced; when the content equivalent ratio is greater than 1.0:1.0, the condensation reaction time gradually decreases, but the dielectric loss of the prepared aerogel will be significantly increased due to the ion content; in a preferred embodiment of this implementation, the content volume ratio is 1.4:1.0.

Solvent drying and recovery step (S3): After the low dielectric aerogel spherical fine wet gel particle suspension is stabilized, the aerogel spherical fine wet gel particle dispersion solution is first filtered to remove most of the dispersion solvent, and the dispersion solvent is recovered for reuse. The filtered aerogel spherical fine wet gel particles are subjected to azeotropic evaporation and vaporization of the ethanol-water solvent in the aerogel particle system at an azeotropic temperature using a drying recovery system under normal pressure and high temperature environment to obtain 90% to 97% dry low-dielectric micro-solvent wet aerogel spherical fine particles, and the solvent in the process is recovered and reused. Therefore, the solvent content in the solvent drying recovery process of this technology is significantly reduced, the process is safer and a high-purity aerogel product can be prepared. In some embodiments, the evaporation temperature is 110-150°C.

Please refer to Figure 2, which is an aerogel powder prepared according to the above preparation method or a slightly solvent-containing spherical fine particle of wet aerogel dried to 90% to 97% dryness, which has the appearance of a white wet aerogel powder structure; please refer to Figure 3, which is a scanning electron microscope image of a low dielectric aerogel powder prepared according to the above preparation method; under an electron microscope, the dry to 90% The microstructure of the slightly solvent-containing wet aerogel spherical fine particles under 97% dry conditions presents a uniform spherical structure with a size ranging from about 100 nanometers to sub-micrometers, and then the aerogel particles of about 100 nanometers are aggregated into sub-micrometer to micrometer-sized agglomerates; in addition, it can be seen from Figure 3 that there are a large number of fine pores in the aerogel agglomerate structure, which form the porosity of the aerogel powder.

Furthermore, in the second embodiment of the present invention, the solvent drying and recovery comprises a vaporization step (S3-1) and a solvent recovery step (S3-2).

Vaporization step (S3-1): adjusting the vaporization temperature of the aerogel system to the azeotropic temperature of a mixed solvent, so that a large amount of trace organic solvents and a large amount of ethanol and water molecules contained in the aerogel produce a rapid boiling phenomenon under two-phase azeotropic or three-phase azeotropic conditions; in some embodiments, the ethanol-water two-phase azeotropic temperature is 65-68°C; the ethanol-water-toluene three-phase azeotropic temperature is 73-78°C. It should be further explained that in the high temperature environment created by the two-phase azeotropic or three-phase azeotropic temperature, a positive pressure is generated inside the aerogel, and the positive pressure can inhibit the shrinkage or collapse of the aerogel structure during the drying process; on the other hand, the positive pressure can make the aerogel porous; in some embodiments, the vaporization temperature is 75~120℃.

Solvent recovery step (S3-2): adjust a vaporization temperature to the azeotropic temperature of the mixed solvent, so that a large amount of trace organic solvents and a large amount of ethanol and water molecules contained in the aerogel produce a rapid boiling phenomenon under two-phase azeotropic or three-phase azeotropic conditions; then use a condensation recovery device to recover and reuse all two-phase azeotropic or three-phase azeotropic solvents to form 90% to 97% dry micro-solvent wet aerogel spherical fine particles. In some embodiments, the solvent recovery device is a water-cooled condensation device, which can recover and reuse 85 to 95% of the solvent in the process to reduce air pollution and reduce manufacturing costs.

Organic solvent suspension dispersion step (S4): The previously dried aerogel powder or the slightly solvent-containing wet aerogel spherical fine particles dried to 90% to 97% dryness are dispersed by using an organic solvent that is similar to the surface of the aerogel spherical fine particles but repellent to the inside of the aerogel spherical fine particles, making use of the affinity and repulsion between the inside of the aerogel spherical fine particles and the surface of the aerogel spherical fine particles, so as to promote the aerogel spherical fine particles to form a uniformly dispersed suspension during the dispersion process. In some embodiments, in the organic solvent suspension distribution step, the volume solid content of the uniformly suspended and dispersed aerogel spherical fine particles is about 20 to 75%. In a preferred embodiment, the volume solid content of the uniformly suspended and dispersed aerogel spherical fine particles is about 35 to 45%.

The organic solvent added to the suspension dispersion of the aerogel spherical fine particles can be prepared according to the solubility parameter or the organic solvent with similar compatibility matched with the surface properties of the fine particles or a mixture thereof. The trace organic solvent is toluene, xylene, hexane, cyclohexane, N-methylpyrrolidone (NMP), 2-butanone (MEK), acetone, N, N-dimethylacetamide (DMAC), ethyl acetate, ethanol, anhydrous ethanol and deionized water or one of their combinations or a combination of two or more thereof.

Polymer solution mixing step (S5): The suspended and dispersed aerogel spherical fine particles are mixed with a polymer solution matched with a solvent having a similar surface solubility parameter or compatibility; for example, the solvent is toluene, xylene, hexane and methyl pyrrolidone, and the polymer solution matched with the solvent can be polyphenylene ether (PPE) solution, polytetrafluoroethylene (PTFE) solution, Solution, polyester (PET, or PEN) and polyimide (PI) solution; another example is that the polymer solution matched with butanone, dimethylacetamide solvent and methyl pyrrolidone solvent can be epoxy resin (Epoxy), acrylic (PMMA) solution, polyurethane (PU) and other solutions; another example is that the solvent is ethanol or anhydrous ethanol matched with polyimide acid (PAA) solution; finally, if the solvent is water-matched aqueous acrylic (PMMA) solution or aqueous polyurethane (PU) solution, in some embodiments, the solid content of the polymer solution mixed solution is 20% to 60%, and the above can be used to simply mix the uniformly dispersed aerogel round fine particles with the surface matching or compatible polymer solution to form a uniformly dispersed aerogel/polymer composite solution. In some embodiments, in the polymer solution mixing step, the volume ratio of the organic solvent suspension dispersion solution to the polymer solution is 0.5:1 to 1:0.5. In a preferred embodiment, the volume ratio of the organic solvent suspension dispersion solution to the polymer solution is 1.0:1.0.

The polymer mixed solution includes a thermoset polymer, a liquid crystal polymer, a thermoplastic polymer or a combination thereof; specifically, for example, epoxy, polyimide (PI), polyetherimide (PEI), polyphenylene ether (PPE), polyphenylene sulfide (PPS), polyetherketone liquid crystal polymer (PEK), polyetheretherketone liquid crystal polymer (PEEK), polypropylene (PP), polyethylene (PE), polycarbonate (PC), polyamide (PA), polyamide (PEA), polyester (PET), polytetrafluoroethylene (PTFE) , acrylic (PMMA) solution, polyurethane (PU), polyimidic acid (PAA), water-based acrylic (PMMA), water-based polyurethane (PU) or other polymers. The solvent of the polymer solution also includes toluene, xylene, hexane, cyclohexane, N-methylpyrrolidone, butanone, acetone, N, N-dimethylacetamide, ethyl acetate, ethanol, deionized water or one of their combinations or a combination of two or more thereof.

Coating and film-forming step (S6): When the uniformly dispersed aerogel/polymer composite solution can be coated or coated by coating, pressure suction, laminating, extrusion or film drawing techniques to form an aerogel/polymer wet film or aerogel/polymer wet film of uniform thickness, then the surface of the aerogel/polymer wet film or aerogel/polymer wet film is further dried and the film thickness is fixed by using an exhaust infrared heating plate, a UV curing machine or a plurality of high-temperature rollers.

In the coating film forming step, when the solid content of the aerogel/polymer solution is low (solid content is about 20-35%) or the solvent has a low boiling point, the drying technology uses a vacuum-type infrared heating plate, and the heating temperature is 3-10 degrees below the boiling point of the solvent for a few seconds to a few minutes; when the solid content of the aerogel/polymer solution is high (solid content is about > 65%) or the solvent has a high boiling point The drying technology uses multiple sets of high-temperature rollers to dry the surface of aerogel/polymer wet film or aerogel/polymer wet film and determine the film thickness; when the aerogel/polymer solution is heat-curable or UV-curable or the solvent has a high boiling point, the drying technology uses a UV curing machine with a high-temperature roller to dry the surface of aerogel/polymer wet film or aerogel/polymer wet film and determine the film thickness.

Please refer to FIG. 4, which is an appearance image of the aerogel/polyimide soft film prepared in the second embodiment, which shows that the prepared aerogel/polyimide soft film has soft and bendable characteristics; please refer to FIG. 5. It is a SEM electron micrograph of the aerogel/polyimide soft film observed at different magnifications. It can be observed from the SEM electron microscope that the surface of the aerogel/polyimide soft film has a flat appearance with holes of a size of about several microns to ten microns, and a large amount of aerogel powder adhered by polyimide can be clearly observed in the holes of the aerogel/polyimide soft film; In general, the aerogel/polyimide soft film is flat and has a uniform structure. It contains a large number of aerogel particles with pores and a uniform structure of about 100 nanometers. As a result, the aerogel/polyimide soft film has excellent low dielectric and thermal insulation properties, and has considerable application potential as a 5G low dielectric or high temperature resistant thermal insulation aerogel/polyimide composite film.

Please refer to FIG. 6 , which is an appearance image of the aerogel/silicone soft film prepared in the third embodiment, which shows that the prepared aerogel/silicone soft film has thinner and softer characteristics; please refer to FIG. 7 . These are SEM electron micrographs of aerogel/silicone soft films observed at different magnifications. From the SEM electron microscope, it can be observed that the surface and side surfaces of the aerogel/silicone soft film contain aerogel powder with a size of about tens of nanometers to 100 nanometers. Overall, aerogel and silicone can be evenly mixed to form an extremely soft aerogel film. The film is smooth and has a uniform structure. It contains a large number of aerogel particles with a size ranging from about 100 nanometers to sub-micrometers. The aerogel particle structure has many tiny pores.

Drying and rolling step (S7): Finally, the formed aerogel/polymer surface wet-drying film or aerogel/polymer surface wet-drying thick film of uniform thickness is dried and formed into an aerogel/polymer film by using an exhaust high-temperature heating channel or a plurality of sets of high-temperature heating rollers, and then the dried and formed aerogel/polymer film or aerogel/polymer film is rolled and packaged into a roll or a tube by using a conventional rolling device. Aerogel/polymer film or aerogel/polymer membrane can be obtained by this process technology. The above preparation technology can be used to prepare low-dielectric aerogel composite materials such as low-dielectric layers in high-frequency circuits, insulating layers in semiconductor devices, or microwave circuits in communication integrated circuits.

In summary, the above implementation methods and examples illustrate that the present invention can rapidly prepare inorganic aerogel powder with high porosity and low dielectric constant under normal pressure, and then use an organic solvent to uniformly suspend the low dielectric constant aerogel to produce an aerogel suspension, which is then mixed with a polymer solution to prepare a uniform and porous aerogel/polymer composite membrane, and then the aerogel/polymer composite membrane is heat-set and rolled up; the low dielectric constant aerogel and aerogel/polymer composite membrane preparation method provided by the present invention do not require lengthy solvent replacement or the use of supercritical drying equipment, and the overall process is simple, fast, safe and low-cost.

In summary, the manufacture, application and effects of the present invention should have been 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 implementation of the present invention. In other words, simple equivalent changes and modifications made according to the scope of the patent application and the content of the invention description are all within the scope of the present invention.

(S1): Mixing and hydrolysis step (S2): Condensation fractionation step (S3): Solvent drying and recovery step (S4): Organic solvent suspension fractionation step (S5): Polymer solution mixing step (S6): Coating and film forming step (S7): Drying and rolling step

FIG. 1 is a step-by-step flow chart illustrating the first embodiment of the low dielectric gel powder manufacturing process of the present invention. FIG. 2 is an appearance image of the low dielectric gel powder prepared by the first embodiment of the present invention. FIG. 3 is a scanning electron microscope image of the low dielectric gel powder prepared by the first embodiment of the present invention. FIG. 4 is an appearance image of the low dielectric gel/polyimide composite film prepared by the second embodiment of the present invention. FIG. 5 is a scanning electron microscope image of the low dielectric gel/polyimide composite film prepared by the second embodiment of the present invention. FIG. 6 is an appearance image of the low dielectric gel/silicone composite film prepared by the third embodiment of the present invention. Figure 7 is a scanning electron microscope image of the low dielectric gel/silicone composite film prepared by the third embodiment of the present invention.

(S1): Mixed hydrolysis step

(S2): Contraction and division of walking

(S3): Solvent drying and recovery step

(S4): Organic solvent suspension dispersion

(S5): Polymer solution mixing step

(S6): coating and film-forming step

(S7): Dry rolling step

Claims (9)

A method for preparing a low dielectric gel/polymer composite film comprises the following steps: a mixing and hydrolysis step: mixing a siloxane compound and a hydrophobic modified siloxane compound with an ethanol aqueous solution containing a trace amount of an acid catalyst and a trace amount of an organic solvent, and performing a hydrolysis reaction during the mixing process to form a hydrolysis solution containing silicon molecules, wherein the total molar percentage of the siloxane compound and the hydrophobic modified siloxane compound is between 0.5 mol% and 50 mol%, and the total molar percentage of the ethanol aqueous solution containing a trace amount of an acid catalyst and a trace amount of an organic solvent is between 99.5 mol% and 50 mol%, wherein the siloxane compound and the hydrophobic modified siloxane compound are mixed with an ethanol aqueous solution containing a trace amount of an acid catalyst and a trace amount of an organic solvent, and ... organic solvent, and the siloxane compound and the hydrophobic modified siloxane compound are mixed with an ethanol aqueous solution containing a trace amount of an organic solvent, and the siloxane compound and the hydrophobic modified siloxane compound The molar ratio of the total content of the oxane compound and the hydrophobic modified siloxane compound to the content of the acid catalyst is 1:0.01 to 1:0.00005; the condensation decomposition step: the hydrolysis solution containing silicon molecules is added to the dispersed ethanol aqueous solution containing a trace amount of alkali catalyst, and the hydrolysis solution containing silicon molecules is dispersed into nano-scale suspended water droplets in the dispersed ethanol aqueous solution containing a trace amount of alkali catalyst under high-speed stirring by combining an emulsifier and a homogenizer, and a condensation reaction is performed to obtain a low-dielectric gel round fine wet gel particle dispersion suspension, wherein the molar ratio of the alkali catalyst to the acid catalyst is 0.8:1.0~2.0:1.0; the solvent Drying recovery step: When the low dielectric aerogel spherical fine wet gel particles are dispersed and suspended, the ethanol-containing aqueous solvent in the aerogel wet gel particles system is evaporated at an azeotropic temperature using a drying recovery system under normal pressure to obtain a 90% to 97% dry low dielectric micro-solvent-containing wet aerogel spherical particle. The aerogel spherical fine particles are formed and the solvent in the process is recycled and reused; the organic solvent suspension dispersion step: based on the affinity and repellency of the interior and surface of the aerogel spherical fine particles, the organic solvent similar to the aerogel surface but repellent to the interior is used for dispersion, so that the aerogel spherical fine particles form a uniform Dispersing the suspended body; Polymer solution mixing step: the suspended and dispersed aerogel spherical fine particles are mixed with a polymer solution matched with a solvent having similar surface solubility parameters or compatibility to form a uniformly dispersed aerogel/polymer composite solution; coating and film forming step: coating or laminating the aerogel/polymer composite solution to form an aerogel/polymer wet film of uniform thickness; and drying and rolling step: drying and shaping the formed aerogel/polymer wet film of uniform thickness into an aerogel/polymer film, and then rolling the dried and shaped aerogel/polymer film into a roll or a tube. The preparation method as described in claim 1, wherein the siloxane compound is tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS); the hydrophobic modified siloxane compound is methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES); the molar ratio between the siloxane compound and the hydrophobic modified siloxane compound is from 0:100 to 45:55; and the molar ratio of the slightly contained organic solvent, ethanol and water in the ethanol aqueous solution is from 3:5:92 to 5:45:50. The preparation method as described in any one of claim 1 or 2, wherein: in the condensation separation step, the dispersed ethanol aqueous solution includes one or a mixture of different compositions of the ethanol aqueous solution recovered in the process, the recovered distilled water, the recovered secondary treatment water and the deionized water; and the solvent drying recovery step: the ambient temperature is controlled at the azeotropic temperature, so that the suspension solvent and the water molecules in the low dielectric gel powder are in a two-phase or three-phase azeotropic condition, and the low dielectric gel powder is dried and dried. The gel powder is dried to 90% to 97% dryness to form the low dielectric micro-solvent wet aerogel spherical fine particles to obtain a stable aerogel suspension, wherein the organic solvent used in the organic solvent suspension dispersion step includes toluene, xylene, hexane, cyclohexane, N-methylpyrrolidone, butanone, acetone, N,N-dimethylacetamide, ethyl acetate, anhydrous ethanol, deionized water or one of their combinations or a combination of two or more thereof. The preparation method as described in claim 3, wherein the polymer mixed solution contains a thermosetting polymer, and the thermosetting polymer is selected from one of the following or a mixture thereof: epoxy, polyimide (PI), polyetherimide (PEI), polyphenylene ether (PPE), polyphenylene sulfide (PPS), polyetherketone liquid crystal polymer (PEK), polyetheretherketone liquid crystal polymer (PEEK). The preparation method as described in claim 3, wherein the polymer mixed solution contains a thermoplastic polymer, and the thermoplastic polymer is selected from one of the following or a mixture thereof: polypropylene (PP), polyethylene (PE), polycarbonate (PC), polyamide (PA), polyesteramide (PEA), polyester (PET, PEN), polytetrafluoroethylene (PTFE), acrylic (PMMA) solution, polyurethane (PU), polyamidic acid (PAA), water-based acrylic (PMMA), and water-based polyurethane (PU). The preparation method as described in claim 4, wherein the solvent of the polymer solution includes toluene, xylene, hexane, cyclohexane, N-methylpyrrolidone, butanone, acetone, N,N-dimethylacetamide, ethyl acetate, ethanol, deionized water or one of their combinations or a combination of two or more thereof. The preparation method as described in claim 5, wherein the solvent of the polymer solution includes toluene, xylene, hexane, cyclohexane, N-methylpyrrolidone, butanone, acetone, N,N-dimethylacetamide, ethyl acetate, ethanol, deionized water or one of their combinations or a combination of two or more thereof. The preparation method as described in any one of claim 1 or 2, wherein the low dielectric aerogel/polymer composite solution can be applied or coated to form an aerogel/polymer composite film of uniform thickness by coating, pressure suction, laminating, extruding or stretching, and the surface is dried and the film thickness is fixed by using an exhaust infrared heating plate, a UV curing machine or multiple sets of high-temperature rollers. The preparation method as described in claim 8, wherein the low dielectric gas gel/polymer composite film is finally dried and shaped using a vacuum high-temperature heating channel or multiple sets of high-temperature heating rollers, and is rolled and packaged using a rolling device.

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