JP2021172565A - Method for producing aerogel and inorganic fiber composite gel material having high temperature resistance, heat insulation and fire resistance, and use of product thereof - Google Patents

Abstract

To provide a method for producing a hydrophilic aerogel and inorganic fiber composite gel material which does not have organic substances decomposed and does not produce carcinogenic substances even when used at a high temperature of 600°C or higher for long hours.SOLUTION: A method comprises (1) a mixing step, (2) a hydrolysis step, (3) a polycondensation step, (4) an aging step, (5) a high-temperature solvent exchange step, (6) a drying step, and (7) a blending step. The obtained aerogel particles are mixed with inorganic fibers to form an adhesive aerogel composite gel-like substance. The content of aerogel and inorganic fibers after drying ranges from 25 wt.% to 90 wt.%.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing an airgel and an inorganic fiber composite gel material having high temperature resistance, heat insulation and fire resistance, and the use of the product thereof, and in particular, the related product has a property of withstanding a high temperature of 800 ° C. or higher. The present invention relates to a composite gel material and a method for producing the same.

Airgel porous material having a three-dimensional network structure, low density ^{(0.003g / cm 3 ~0.2g / cm} 3), high specific surface area ^{(500m 2 / g~2,000m 2 / g} ), low thermal conductivity It is a high-tech product having characteristics such as (0.02 W / mK to 0.036 W / mK). In addition, the porosity of airgel reaches 95% or more, and a large amount of air is contained inside the airgel. Therefore, it is transparent as a whole and has characteristics such as low thermal conductivity, low sound conductivity, and low dielectric constant, and has extremely excellent heat insulation, soundproofing, electrical insulation, adsorptivity, and filtration performance. It is a material to have. However, in order to achieve the above-mentioned functions in actual use, it is necessary to uniformly disperse the airgel on a base material such as rock wool, glass fiber, or carbon fiber to form an airgel heat insulating blanket. Common airgel insulation blankets have the problem of being easy to blow powder. In addition, most of the airgel heat insulating blankets had a usable temperature of 200 ° C. or lower and were not resistant to high temperatures. In the commercial product, when used at a high temperature of 300 ° C., the airgel heat insulating blanket emitted toxic gas and a foul odor, and a clear decomposition phenomenon occurred after a certain period of use. As a result, a large amount of airgel decomposition products and dust were generated during the replacement, which was harmful to people's health and polluted the environment.

There is a sol-gel method as a conventional method for producing airgel. Mainly, first, a precursor such as an alkoxysilane compound (alkoxysilane), tetramethyl orthosilicate, or water glass is mixed with an organic solvent, and an acid catalyst is added so that a hydrolysis reaction occurs. After hydrolysis for a certain period of time, an alkaline catalyst is added so that a condensation (condensation) reaction occurs, and a sol is gradually formed during the aggregation (polycondensation). Molecular binding in the sol continues and semi-solid polymer gels are gradually formed. Then, by aging for a certain period of time, the sol is converted from a semi-solid structure to a three-dimensional network structure having a stable structure. Finally, the solvent is first exchanged using ethanol, butanol, or 1-propanol, and further solvent exchange is performed using a solvent such as n-hexane or cyclohexane, and then supercritical drying is performed. The solvent in the three-dimensional network structure is extracted and dried by the technique to obtain a porous dry hydrophobic airgel powder.

The currently used hydrophobic airgel adiabatic blanket also uses the sol-gel method first. Mainly, an alkoxysilane compound (for example, methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES)) is first mixed with an organic solvent, and then an alkali catalyst is added so that a hydrolysis reaction occurs. .. After hydrolysis for a certain period of time, the polycondensation reaction is allowed to proceed and a gel is gradually formed during the polycondensation. Then, it is dried at normal temperature and pressure or high temperature and pressure. In other sol-gel methods, an alkoxysilane compound (for example, tetraethoxysilane (TEOS) or tetramethoxysilane (TMOS)) is first mixed with an organic solvent, and then an acid is formed so that a hydrolysis reaction occurs. Add the catalyst. After hydrolysis for a certain period of time, an alkali catalyst is added so that a polycondensation reaction occurs, and a three-dimensional network structure having a stable structure is gradually formed during the polycondensation. Then, first, the solvent is exchanged using etanol, butanol, or 1-propanol, and further the solvent is exchanged using a solvent such as n-hexane or cyclohexane. Then, hydrophobic modification is performed with chlorotrimethylsilane or a hydrophobic silane compound, and the hydrophobic functional group group and the three-dimensional network structure are chemically bonded. Then, the solvent in the three-dimensional network structure is dried by the atmospheric drying technique to obtain a porous dried airgel bulk material. Finally, the derived airgel powder is evenly sprayed onto the inorganic cotton blanket, sprayed with silicone oil and stylized by needle punching to form a multi-layer airgel insulated blanket.

However, the above-mentioned hydrophobic airgel and the formed multilayer airgel adiabatic blanket could not be industrially used because decomposition started at 350 ° C. and released a large amount of toxic organic substances. Further, since the above-mentioned hydrophobic airgel needs to be subjected to solvent exchange many times during the manufacturing process and also needs to be modified with an organic substance, it is costly and time-consuming as a whole, and the cost performance is poor.

Further, as a conventional patent document relating to a heat insulating ceramic plate resistant to high temperature, for example, the following Patent Document 1 describes "foam ceramic composite floor heating brick and its manufacturing method". Here, a foamed ceramic having a specific density of 0.2 to 0.8 is used as a substrate, and the adhesive layer between the ceramic brick and the foamed ceramic is ultrafast-hardened cement. However, this technology has the following problems.
1. The thermal conductivity of the foamed ceramic is higher than that of the airgel material or the conventional organic foaming material, which is 4 to 5 times that of the airgel material, and the heat loss is relatively high.
2. The related organic foaming material clearly decomposes in a high temperature environment of 350 ° C or higher, generates a large amount of toxic gas, and affects the service life of the foamed ceramic.

Further, for example, the following Patent Document 2 describes "electric heating composite ceramic brick and its manufacturing method". Here, an electric heating film is used as the heat generating element, and 55 wt% to 75 wt% of an organic binder is contained in the components. As the organic binder, for example, an organic resin such as an epoxy resin, polyurethane, or silicon rubber is used. However, ceramic bricks containing these organic binders cannot be used for a long time in a high temperature environment of 350 ° C., and are prone to decomposition in the process of heating to a high temperature, and by releasing a large amount of toxic gas. there were.

Further, for example, the following Patent Document 3 describes "a porous material and a method for producing the same". A porous material is produced by mixing and synthesizing an alkoxysilane compound (for example, tetraethoxysilane) or a silicate compound (for example, water glass) and an organic solvent mainly using a sol-gel method, and modifying the mixture with a modifier. do. As a result, the hydrophilic functional groups on the surface of the porous material are replaced with the hydrophobic functional groups, and the event that the airgel bursts due to the influence of the surface tension of water is avoided. The drawback of this technique is that the resulting hydrophobic airgel material cannot be used in high temperature environments and begins to decompose at about 350 ° C., releasing large amounts of toxic gas.

Currently commonly used porous ceramic plates mainly belong to foamed ceramics, ceramic honeycombs, or granular ceramic conjugates, all of which are silicate ceramic materials that are fired at high temperatures. These porous ceramic plates essentially have a high density ceramic structure, and the porous ceramic bricks obtained by utilizing the foaming technique are thin and light and have high flame retardancy. However, the heat insulating property at high temperature was not excellent, and the effect was low even when applied in a high temperature environment.

Chinese Patent Application Publication No. CN105135507A Chinese Patent Application Publication No. CN105025598A Japanese Patent Application Publication No. 200835648

Therefore, as a result of diligent studies in view of the above problems, the present inventor has come up with a proposal of the present invention for effectively improving the above problems with a rational design.

The present invention has been made in view of these circumstances, and the first object of the present invention is to use a porous ceramic plate and a hydrophobic airgel heat insulating blanket in which a conventional organic binder is used for a long time in a high temperature environment. It is to improve the drawback of not being able to do it.

A second object of the present invention is to add inorganic fibers (for example, ceramic fibers, rock wool, glass fibers, carbon fibers, etc.) to airgel, and to mechanically reduce the pressure resistance and anti-knock property of the airgel-related heat insulating products. Airgel powder is sprayed between inorganic fiber blankets by spraying or coating the appearance of various irregularly shaped columns and equipment with an airgel composite gel material that directly enhances the properties and is obtained by mixing. It eliminates the need to manufacture adiabatic blankets.

Another object of the present invention is to use an aqueous inorganic pressure-sensitive adhesive solution as a pressure-sensitive adhesive with materials such as hydrophilic airgel particles and inorganic fibers to further increase the porosity of the entire material after drying and increase the density of the material. It is to lower it and improve the heat insulation of the material. In addition, it avoids the generation of a large amount of carcinogens due to decomposition of general organic adhesives in a high temperature environment. By using an aqueous solution of an inorganic adhesive as an adhesive, the structural stability and heat insulating properties of the hydrophilic airgel and the inorganic fiber in a high temperature environment are improved, and the problem of blowing powder even after long-term use in a high temperature environment is solved. Does not occur.

Yet another object of the present invention is to significantly reduce the time required for solvent exchange or washing with water in the production of conventional hydrophilic airgel by utilizing the high temperature solvent exchange technique in the process of producing the developed hydrophilic airgel particles. The manufacturing time is also remarkably shortened, and the yield is improved while suppressing the manufacturing cost.

Yet another object of the present invention is to form a general airgel adiabatic blanket by directly forming an airgel and an inorganic fiber composite gel material onto an inorganic fiber blanket by a conventional processing technique such as spray painting or extrusion. Further, the airgel and the inorganic fiber composite gel material are mutually bonded with a general fiber blanket to form a multi-layer structure, and by adding a water repellent to the airgel and the inorganic fiber composite gel material, water repellency and high temperature heat insulating properties are obtained. The airgel heat insulating blanket having the above is continuously produced or produced in a large lot, and the action between the airgel and the fabric such as the fiber blanket is enhanced to improve the applied value of the product.

The present invention combines the production techniques of hydrophilic airgel and inorganic fibers. Hydrophilic airgel particles are produced by the improved sol-gel technology, and the inorganic fibers are mixed with an aqueous solution of an inorganic pressure-sensitive adhesive to produce heat-insulating airgel and inorganic fibers. It binds (composites) as a fiber composite gel material. This composite gel material has properties suitable for processing such as flexibility and high cohesiveness, and an airgel heat insulating plate material or airgel heat insulating brick having high temperature resistance and high heat insulating properties after cross-linking and drying is formed.

In order to solve the above problems, in the method for producing a hydrophilic aerogel and an inorganic fiber composite gel material according to one aspect of the present invention, a siloxane-based compound is added to a mixed solvent, and the siloxane-based compound is mixed to form a mixed solution. Disperse in a solvent (1) Add an acid catalyst to the mixed solution so that a hydrolysis reaction occurs (2) Add an alkali catalyst to the mixed solution so that a polycondensation reaction occurs (3) In the polycondensation step, a hydrophobic dispersion solvent is added during the polycondensation reaction, and a wet gel of aerogel having a uniform structure is formed in the mixed solution by high-speed stirring, or during the polycondensation reaction. A hydrophobic dispersion solvent was added to the mixture, and a wet gel of aerogel having a uniform structure was formed in the mixed solution by high-speed stirring. The particle size of the gel becomes several hundred nm to several tens of mm and is dispersed in a hydrophobic dispersion solvent, and the wet gel of the aerogel is aged under a specific temperature, and the wet gel of the aerogel is further stabilized ( 4) In the aging step and under normal pressure and high temperature conditions, replace the hydrophobic dispersion solvent with the solvent in the aerogel wet gel until the aerogel wet gel becomes transparent or completely transparent (5) high temperature. After the solvent exchange step and the hydrophobic dispersion solvent are removed by high temperature distillation or filtered by a filter, the wet gel of the aerogel is dried at a high temperature and the water molecules in the wet gel structure of the aerogel are rapidly dried by the mixed solvent of hydrophilic and hydrophobic. To obtain aerogel particles having a high pore ratio and low thermal conductivity characteristics, and to obtain hydrophilic aerogel particles having a high pore ratio and a high specific surface area (6) Drying step, dried hydrophilic aerogel particles and inorganic The fibers are mixed with a stirrer and uniformly dispersed to form an inorganic mixture, and by adding an aqueous inorganic pressure-sensitive adhesive to the inorganic mixture, the adhesiveness of the aerogel particles, the inorganic fibers, and the aqueous solution of the inorganic pressure-sensitive adhesive can be improved. After forming the composite gel material of the hydrophilic aerogel and the inorganic fiber, water, a pressure-sensitive adhesive aqueous solution, a dispersant aqueous solution, or an aerogel powder is added in order to adjust the viscosity of the composite gel material (7). include. Airgel occupies 15v / v% to 40v / v%, inorganic fiber occupies 10v / v% to 35v / v%, and inorganic adhesive aqueous solution occupies 25v / v% to 75v / v% with respect to the composite gel material. Occupy. The total content of airgel and inorganic fibers in the airgel heat insulating plate obtained after drying the composite gel material is in the range of about 25 wt% to 90 wt%.

Further, the siloxane compound mainly improves the density of the network structure and enhances the flexibility and structural strength of the airgel. Examples of the siloxane compound include hydrophilic alkoxysilane compounds (alkoxysilane) such as tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS), and mainly aerogels that provide a trace amount of hydrophobic properties and have an aerogel structure. Contains small amounts of hydrophobic alkoxysilane compounds such as methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES) that enhance structural stability.

Further, the mixed solvent contains a first component and a second component. The first component contains one or more components of the group consisting of water, alcohols, and alkyls, and the second component is one or one of the group consisting of emulsifiers and surfactants. Contains more than one type of ingredient.

In addition, the acid catalyst added in the hydrolysis step comprises one or more components of the group consisting of sulfuric acid, phosphoric acid, nitric acid, and boric acid.

In addition, the alkali catalyst added in the polycondensation step comprises one or more components of the group consisting of sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, and potassium hydrogen carbonate.

Further, the surfactant comprises one or more components of the group consisting of cationic surfactants, anionic surfactants, zwitterionic surfactants, and nonionic surfactants.

Further, the hydrophobic dispersion solvent used in the polycondensation step includes a dispersion solvent produced by harmonizing the hydrophilic solvent and the hydrophobic solvent in the production process. A large amount of dispersion solvent (eg, one or more of alcohols, aromatics, alkyls, and organic halides) is added during the polycondensation crushing reaction, and the airgel wet gel becomes a large amount of hydrophobic. It has a large number of pores due to the action of the sex dispersion solvent, and controls the interaction between the molecules of the dispersion solvent and the airgel wet gel by utilizing the harmonic proportion of the hydrophilic solvent and the hydrophobic solvent, and the airgel in the condensation bond. Further controls the microphase separation of wet gel molecules. As a result, the particle size and pore distribution of the molecules of the formed airgel wet gel are controlled.

Further, in this method, a general normal pressure high temperature hydrophobic solvent exchange method is adopted to exchange the solvent, the solvent exchange efficiency is improved, and the time required for producing the airgel is shortened. This method utilizes the mixing and co-boiling effect between solvents with different hydrophilicity and hydrophobicity, and mixes water molecules or other hydrophilic molecules inside the wet gel during high-temperature solvent exchange with a large amount of hydrophobic dispersion solvent. The co-boiling is allowed to proceed at high speed until the solvent in the wet gel becomes transparent or completely transparent to produce hydrophilic aerogel particles with low density and high porosity.

Further, in this method, the solvent is evaporated and dried by a general normal pressure high temperature method. After drying, hydrophilic airgel particles having a particle size in the range of several hundred nm to several tens of mm can be obtained. Overall, the manufacturing process is simplified and the airgel particles are surface modified with different hydrophilic functional groups based on the properties of the substrate. The production process is completed within 8 to 12 hours, and continuous production produces airgel particles having a general hydrophilic group group or a special hydrophilic group group to improve production efficiency.

Further, the transparent airgel particles obtained by evaporating and drying the solvent under normal pressure and high temperature are directly mixed with the inorganic fibers by a stirrer to form an airgel inorganic mixture uniformly dispersed. After that, when the inorganic pressure-sensitive adhesive is added, the airgel particles, the inorganic fibers, and the inorganic pressure-sensitive adhesive interact with each other to form a composite gel-like product of the pressure-sensitive airgel. Next, in order to adjust the viscosity of the composite gel of airgel, water, an aqueous pressure-sensitive adhesive solution, an aqueous dispersant solution, or an airgel powder is added. The content of airgel in the airgel composite gel material according to the present invention is in the range of 15v / v% to 40v / v%, the content of inorganic fibers is in the range of 10v / v% to 35v / v%, and the inorganic pressure-sensitive adhesive. And the total content of water is in the range of 25v / v% to 75v / v%. The airgel composite gel material according to the present invention has high adhesiveness and is directly filled or coated in high temperature equipment such as a high temperature furnace or an internal combustion machine, or manufactured as an applied product such as an airgel heat insulating brick or a plate by a die casting method. Will be done. The total content of airgel and inorganic fibers in aerogel insulating bricks or plates ranges from about 25 wt% to 90 wt%.

Further, the total content of airgel and inorganic fibers in the airgel insulation plate formed after drying the airgel composite gel material is about 90 wt%. Further, the heat resistance reaches 800 ° C. or higher, and the thermal conductivitys in the environment of room temperature and 500 ° C. are 0.04 W / mK and 0.095 W / mK, respectively.

Further, the inorganic fiber is one kind or one or more kinds of materials in the group consisting of inorganic materials such as ceramic fiber, glass fiber, carbon fiber, oxide fiber, and rock wool fiber.

According to the present invention, there are the following effects.
1. In the production method according to the present invention, the hydrophilic solvent inside the wet gel of the airgel and the hydrophobic dispersion solvent interact with each other and are mixed by the action of the hydrophobic dispersion solvent during the polycondensation step, and the surface layer of the wet gel. Is gelled at high speed to form a dense airgel shell layer. In addition, the hydrophobic dispersion solvent also penetrates into the wet gel of the aerogel to promote gelation, and the penetration of the hydrophobic dispersion solvent causes liquid-solid phase-separation, resulting in the wet gel. The structure has a large amount of nanopores to mesopores. In addition, after the hydrophobic dispersion solvent has penetrated into the wet gel, it is miscible with ethanol and water. This changes the interfacial tension of the water molecules, significantly reducing the shrinkage of the wet gel structure of the airgel during the subsequent aging and drying process, producing hydrophilic airgel particles with high porosity. This clearly improves the heat insulation and fire protection performance of the hydrophilic airgel particles, clearly increases the content of the airgel particles in the blend material, and enhances the practicality of the airgel.
2. The hydrophilic aerogel particles obtained by the production method according to the present invention have the density, particle size, porosity, and pore size, for example, the content of the hydrophilic alkoxysilane compound and the content of the hydrophobic alkoxysilane compound. , Solvent content, acid catalyst or alkali catalyst content, surfactant content, hydrophobic dispersion solvent component and its content, hydrophobic dispersion solvent component and its content, solvent exchange temperature and stirring rate, etc. Based on conditions.
3. In the production method according to the present invention, in the polycondensation dispersion step, crushing and high-speed stirring are performed with a large amount of hydrophobic dispersion solvent, and then the hydrophobic dispersion solvent is dried and removed, and the particle size is several hundred nm to several tens. Produces hydrophilic airgel particles with a size of mm. The produced hydrophilic airgel particles have excellent dispersibility and are mixed with the base material in a high content, and the high porosity inside the airgel in the base material is maintained, and the hydrophilicity in various different base materials is maintained. Improves heat insulation and fire protection performance of airgel particles.
4. In the high temperature solvent exchange step, the present invention shortens the time required for the exchange of the entire airgel by controlling the conditions such as the solvent content and temperature, and a large amount (volume of about 500 L) within 12 to 24 hours at the fastest. The production of hydrophilic airgel particles of ~ 5000 L) is completed. This increases the production efficiency of airgel.
5. In the present invention, hydrophilic airgel particles are added to and mixed with inorganic fibers, and the viscosity is adjusted with an aqueous solution of an inorganic pressure-sensitive adhesive to form a high-temperature airgel and an inorganic fiber heat-insulating composite gel material. The related products can be used for a long time at a temperature of 600 ° C. or higher, and further exhibit a short-time heat insulating effect even in an extremely high temperature environment of 1000 ° C.

It is a flowchart which shows the manufacturing method of the hydrophilic airgel and the composite gel material which concerns on one Embodiment of this invention. It is an appearance photograph of the hydrophilic airgel particles of this invention. It is an appearance photograph of the hydrophilic airgel particles of this invention. It is a scanning electron microscope observation photograph of the hydrophilic airgel particles of this invention. It is an external photograph of a high temperature heat insulating airgel brick of 10.5 cm × 10.5 cm × 9.5 cm. It is a graph which shows the temperature change of the back surface when the high temperature heat insulating airgel brick of a thickness 3cm was heated at 1200 degreeC for 3 hours (the ratio is a volume ratio).

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The present invention is not limited to the following embodiments, and various forms can be adopted as long as it belongs to the scope of claims (technical scope) of the present invention.

Other features of the present invention will be clarified by the description in the present specification and the accompanying drawings.

FIG. 1 illustrates a method for producing a hydrophilic airgel composite gel material according to an embodiment of the present invention. Mixing step (S1), hydrolysis step (S2), agglutination (polycondensation) dispersion step (S3) or polycondensation pulverization step (S3'), aging step (S4), high temperature solvent exchange step (S5). And a drying step (S6) and a blending step (S7). This makes it possible to apply it to the production of airgel heat insulating brick materials having high temperature resistance.

<Mixing step (S1)>
The siloxane compound and the mixed solvent are mixed. Siloxane compounds include hydrophilic alkoxysilane compounds (alkoxysilane) such as tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS), and methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES). One or more of the group consisting of such alkylsiloxane compounds. In the text, the hydrophobic molecule mainly imparts a trace amount of hydrophobic property to the airgel and improves the structural stability of the airgel structure. Further, by adding a smaller amount of another hydrophilic alkoxysilane compound such as R-alkoxysilane compound, the airgel microstructure is mainly modified and the content of functional groups is controlled. Here, R is a hydrophilic functional group and contains an acid group-COOH, an amine group-NH ₂ , an imide group-NH-, a hydroxy group-OH, an amide group-CONH-, or an epoxy group-COH-COH. The number of carbon atoms of the hydrophilic functional group is in the range of C1 to C8. Calculated from the total content of the mixed solution, the total content of the siloxane compound is in the range of 3.0 mol% to 60.0 mol%, and the content of the alkyl siloxane compound is in the range of 0.05 mol% to 6.0 mol%. The content of the solvent is in the range of 97.0 mol% to 40.0 mol%.

The solvent used in the mixing step (S1) is water, treated water, deionized water, secondary water, alcohols C1 to C8, alkyls C1 to C8, polymer emulsifiers, or surfactants. Specific mixing solvents are water, treated water, deionized water, ethanol, toluene, n-hexane, cyclohexane, polyvinyl alcohol, or hexadecyltrimethylammonium chloride.

<Hydrolyzed step (S2)>
An acid catalyst is added to the mixed solution so that a hydrolysis reaction occurs. The content ratio (mass) of the total content of the siloxane compound to the acid catalyst is 1: 0.5 to 1: 0.0001. Further, by containing a specific R-alkoxysilane compound, it is possible to directly carry out hydrolysis without adding an acid catalyst. When the total content of the siloxane compound and the content ratio of the acid catalyst are 1: 0.0001, the hydrolysis reaction time is 360 minutes. When the total content of the siloxane compound and the content ratio of the acid catalyst are 1: 0.5, the hydrolysis time is 5 minutes. Thus, the hydrolysis time decreases as the content of the acid catalyst increases.

<Polycondensation dispersion step (S3) or polycondensation grinding step (S3')>
An alkaline catalyst is added to the mixed solution so that a polycondensation reaction occurs. The molar ratio of acid catalyst to alkali catalyst is 1: 1 to 1: 4. As the content of the alkaline catalyst in the mixed solution increases, the polycondensation reaction time (ie, gelation time) is clearly shortened. When the molar ratio of acid catalyst to alkali catalyst is 1: 1, the gelation time is about 1200 minutes. When the molar ratio of acid catalyst to alkali catalyst is 1: 3, the gelation time is shortened to about 3-5 minutes. Therefore, the gelation time can be adjusted by adjusting the content of the alkaline catalyst.

Before the polycondensation reaction is nearing completion, the mixed solution becomes a solution-like sol. In the polycondensation dispersion step (S3), a large amount of incompatible hydrophobic dispersion solvent is added under the condition that the mixed solution is controlled in a sol form, and the mixture is stirred at a high speed of 100 rpm to 500 rpm. The mixed solution is affected by the hydrophobic dispersion solvent, the hydration action of water molecules in the mixed solution is suppressed, and the subsequent gelation forms a wet gel of hydrophilic airgel. The volume ratio of the (mixed) solvent to the hydrophobic dispersion solvent is 1: 0.05 to 1: 0.5, and the higher the content of the hydrophobic dispersion solvent, the lower the shrinkage rate of the airgel particles formed thereafter. do. From a macro perspective, the appearance is so opaque that the phase separation becomes remarkable. However, the higher the porosity of the structure, the lower the density. In the polycondensation pulverization step (S3'), the wet gel of the hydrophilic airgel is crushed under the condition of a larger amount of hydrophobic dispersion solvent. Specifically, the wet gel is crushed to a size of several hundred nm to several tens of mm and dispersed in a hydrophobic dispersion solvent.

The hydrophobic dispersion solvent used in the polycondensation dispersion step (S3) or the polycondensation grinding step (S3') is C2-C4 alcohols, C6-C12 aromatics, C5-C9 alkyls, or C7. ~ C12 aromatic solvents. Specifically, for example, ethanol, hexane, cyclohexane, pentane, benzene, toluene, benzyl alcohol, or phenethyl alcohol.

<Aging step (S4)>
By aging the formed hydrophilic airgel wet gel at a specific temperature (for example, 35 ° C to 80 ° C, further 40 ° C to 50 ° C), the wet gel structure of the hydrophilic airgel is stabilized.

<High temperature solvent exchange step (S5)>
The solvent of the wet gel is exchanged at normal pressure and high temperature (for example, 50 ° C. to 160 ° C.). In the high temperature solvent exchange step (S6), the miscibility between the hydrophilic and hydrophobic solvents is utilized to mix and azeotrope the water molecules or other hydrophilic molecules inside the wet gel with a large amount of the hydrophobic dispersion solvent. Change the solvent in the wet gel at high speed until it becomes transparent or completely transparent. This makes it possible to produce hydrophilic airgel particles with low density and high porosity.

<Drying step (S6)>
The above-mentioned excess hydrophobic dispersion solvent is removed by high-temperature distillation, or the above-mentioned excess hydrophobic dispersion solvent is filtered through a filter, and then the wet gel is dried at high speed under normal pressure conditions of 60 ° C. to 160 ° C. Obtain high density hydrophilic airgel particles. After that, the airgel particles are further dried at 90 ° C. to 250 ° C. by a fluidized bed dryer, a constant temperature bath, a drum type dryer, a blend dryer, a spray dryer, or a vacuum dryer to obtain dry hydrophilic airgel particles. obtain.

In this way, porous hydrophilic airgel particles having a particle size of several hundred nm to several tens of mm are produced. The present technology can also produce airgel particles modified with hydrophilic functional groups. Then, by mixing with materials such as cement, cement paint, adhesive, and lacquer, it can be applied to various fireproof and heat insulating products, and airgel particles are often used. In particular, the obtained airgel particles can be applied to the production and application of high temperature resistant airgel heat insulating plate materials and brick materials.

<Blend step (S7)>
The transparent airgel particles are directly mixed with the inorganic fibers by a stirrer to form a uniformly dispersed inorganic mixture. Then, an inorganic adhesive such as airgel particles is added to form a composite gel of adhesive airgel by the action of the inorganic fiber and the inorganic adhesive. Then, water, an aqueous pressure-sensitive adhesive solution, an aqueous dispersant solution, or an airgel powder is added to adjust the viscosity of the airgel composite gel-like substance to obtain an airgel composite gel material.

The inorganic pressure-sensitive adhesive used in the blending step (S7) is one or more of the group consisting of phosphates, silicates, sulfates, borates, and metal oxides. Specifically, the phosphate is zirconium phosphate or phosphate-copper oxide, the silicate is aluminum silicate or water glass, and the metal oxides are copper, aluminum, zirconium, yttrium, and lanthanum. It is an elemental metal oxide.

2 and 3 show the appearance of hydrophilic airgel particles observed using a general camera. FIG. 2 shows hydrophilic airgel particles having a nanoscale hydrophilic airgel particle size of about 50 nm to 200 nm. FIG. 3 shows that the size of the hydrophilic airgel particles of the millimeter scale is about 3 mm to 20 mm.

FIG. 4 is a photograph of observing the fine structure of hydrophilic airgel particles using a scanning electron microscope. It has a large number of holes on its surface and inside.

FIG. 5 is an external photograph of the manufactured 10.5 cm × 10.5 cm × 9.5 cm high temperature insulated airgel brick. From the display of the scale in the photograph, it can be seen that the weight is 277.1 g. By calculation, it was found that the density of the high temperature insulated airgel brick was 0.265 g / cm ³ , and it was confirmed that an excellent weight reduction effect could be obtained.

FIG. 6 shows a graph comparing the back surface temperature when a high temperature insulated airgel brick having a thickness of 3 cm is heated with a flame of 1200 ° C. for 3 hours. From the comparison results, when the room temperature is 25 ° C., the back surface temperature after heating the high temperature insulated airgel brick at 1200 ° C. for 3 hours is about 175 ° C., and the product of the present embodiment has extremely excellent high temperature resistance and heat insulating properties. Is shown.

The above-described embodiment is described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention belongs to carry out the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is construed in the broadest range according to the technical idea defined by the claims.

(S1) Mixing step (S2) Hydrolysis step (S3) Polycondensation dispersion step (S3') Polycondensation pulverization step (S4) Aging step (S5) High temperature solvent exchange step (S6) Drying step (S7) Blending step

Claims (10)

A mixing step of mixing a siloxane compound and a solvent to prepare a mixed solution, and
A hydrolysis step in which an acid catalyst is added to the mixed solution to allow the hydrolysis reaction to proceed,
A polycondensation step in which an alkali catalyst is added to the mixed solution to allow the polycondensation reaction to proceed. A hydrophobic dispersion solvent is added during the polycondensation reaction, and a wet gel of airgel is formed in the mixed solution by stirring. Or, a hydrophobic dispersion solvent was added during the polycondensation reaction, and an airgel wet gel was formed in the mixed solution by stirring, and the airgel wet gel was crushed and crushed in the hydrophobic dispersion solvent. A polycondensation step in which a wet gel having a particle size of several hundred nm to several tens of mm is dispersed in the hydrophobic dispersion solvent, and
The aging step of aging the wet gel of the airgel under a specific temperature to stabilize the wet gel of the airgel, and the aging step.
A high-temperature solvent exchange step of exchanging the hydrophobic dispersion solvent and the solvent in the wet gel of the airgel under the conditions of normal pressure and high temperature, and
After the hydrophobic dispersion solvent is removed by high temperature distillation or filtered by a filter, the wet gel of the airgel is dried at a high temperature to obtain hydrophilic airgel particles.
The dried hydrophilic airgel particles and inorganic fibers are mixed with a stirrer to form an inorganic mixture, and the inorganic pressure-sensitive adhesive aqueous solution is added to the inorganic mixture, and the hydrophilic airgel particles, the inorganic fibers, and the inorganic pressure-sensitive adhesive aqueous solution are added. A method for producing a hydrophilic airgel and an inorganic fiber composite gel material, which comprises a blending step of forming a hydrophilic airgel and an inorganic fiber composite gel material containing the above. The siloxane compound contains a first hydrophilic alkoxysilane compound (alkoxysilane), a small amount of a second hydrophilic alkoxysilane compound, and a hydrophobic alkoxysilane compound, and the first hydrophilic alkoxysilane compound is tetra. Selected from tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS), the hydrophobic alkoxysilane compound is selected from methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES), said second. The hydrophilic alkoxysilane compound is an R-alkoxysilane compound, where R is a hydrophilic functional group, acid group-COOH, amine group-NH ₂ , imide group-NH-, hydroxy group-OH, amide group-CONH- , Or the hydrophilic aerogel and inorganic fiber composite gel material according to claim 1, which is selected from an epoxy group-COH-COH and has a hydrophilic functional group having a carbon number in the range of C1 to C8. Production method. The solvent contains a first component and a second component, the first component contains one or more components of the group consisting of water, alcohols, and alkyls, and the second component The method for producing a hydrophilic airgel and an inorganic fiber composite gel material according to claim 1, wherein one or more of the components in the group consisting of an emulsifier and a surfactant are contained. Claim 1 is characterized in that the hydrophobic dispersion solvent is at least one selected from the group consisting of ethanol, hexane, cyclohexane, pentane, benzene, toluene, benzyl alcohol, and phenethyl alcohol. The method for producing a hydrophilic airgel and an inorganic fiber composite gel material according to. The method for producing a hydrophilic airgel and an inorganic fiber composite gel material according to claim 1, wherein the high-temperature solvent exchange step is performed under a normal pressure of 50 ° C. to 160 ° C. The high temperature distillation of the drying step is carried out under normal pressure conditions of 60 ° C. to 160 ° C., and the high temperature drying is performed by a fluidized layer dryer, a constant temperature bath, a drum type dryer, a blend dryer, a spray dryer, or a vacuum dryer. The method for producing a hydrophilic aerogel and an inorganic fiber composite gel material according to claim 1, wherein the method is carried out at 90 ° C to 250 ° C. The density, particle size, porosity, and pore size of the aerogel particles are determined by the content of the first hydrophilic alkoxysilane compound, the content of the second hydrophilic alkoxysilane compound, the content of the hydrophobic alkoxysilane compound, and the solvent. It should be adjusted based on the conditions of content, solvent viscosity, acid catalyst content, alkali catalyst content, hydrophobic dispersion solvent type or content, hydrophobic dispersion solvent type or content, solvent exchange temperature, and stirring speed. The method for producing a hydrophilic aerogel and an inorganic fiber composite gel material according to claim 2. The blending step is replaced by the step of forming an inorganic mixture in which the dried hydrophilic airgel particles are mixed with the inorganic fibers by a stirrer, and an inorganic adhesive is added to the inorganic mixture to form the airgel particles, the inorganic fibers, and the inorganic fibers. The method for producing a hydrophilic airgel and an inorganic fiber composite gel material according to claim 1, wherein a composite gel of the adhesive airgel containing the inorganic pressure-sensitive adhesive is formed. The inorganic pressure-sensitive adhesive is selected from phosphates, silicates, sulfates, borates, or metal oxides, the phosphates are zirconium phosphate, phosphate-copper oxide, and the silicates are. The method for producing a hydrophilic aerogel and an inorganic fiber composite gel material according to claim 8, wherein the metal oxide is aluminum silicate or water glass, and the metal oxide is an oxide containing copper, aluminum, and a zirconium-based element. .. The airgel occupies 15 v / v% to 40 v / v% of the content of the composite gel material, the inorganic fiber occupies 10 v / v% to 35 v / v%, and the inorganic pressure-sensitive adhesive aqueous solution occupies 25 v / v% to 75 v. The first aspect of claim 1, wherein the total content of the airgel and the inorganic fibers in the airgel heat insulating plate obtained after drying the composite gel material occupies / v% is in the range of 25 wt% to 90 wt%. A method for producing a hydrophilic airgel and an inorganic fiber composite gel material.

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