KR102314067B1 - A manufacturing method of hydrophobic silica aerogel powder with surfactant applied, a composite foam having silica aerogel and composite foam using this - Google Patents

Abstract

The present invention relates to a method for producing a silica airgel powder having a controlled particle structure and shape using a surfactant, and manufacturing a composite foam using the airgel powder, and the present invention is a stable and simple process under atmospheric pressure. As a result, silica airgel powder with excellent physical properties such as superhydrophobicity and high specific surface area can be manufactured, and by mixing the silica airgel with a binder and other additives to produce a composite foam through microwave can be utilized

Description

A manufacturing method of hydrophobic silica aerogel powder with surfactant applied, a composite foam having silica aerogel and composite foam using this }

The present invention relates to a method for producing a composite foam using a hydrophobic silica airgel powder and silica airgel to which a surfactant is applied, and to a composite foam made through the same.

Airgel is made of silicon dioxide (SiO2) nanostructures loosely tangled like a nonwoven fabric, but the space between the threads is filled with air. Silica airgel of 1 cubic meter is the lightest among inorganic insulation materials, weighing less than 100 kg, and has a porosity of about 80 to 99% and a pore size in the range of 1 to 50 nm. It is a material with excellent ultra-insulation and low dielectric properties.

Airgel has excellent properties such as insulation, sound absorption, fire resistance, hydrophobicity, and shock mitigation. It is attracting attention as a next-generation insulation material because it is superior to existing materials, but the manufacturing process is complicated and the manufacturing cost is high, so it is used for very limited purposes.

Substitution of the sol solvent contained in the wet gel in the atmospheric drying process in the airgel manufacturing process is a pretreatment step for surface modification. In order to minimize drying shrinkage by lowering the capillary force during drying, the surface tension is low and chemical reaction with the surface modifier is caused. It is a process in which the -OH group is modified into a non-condensation reactive species.

After replacing the sol solvent such as methanol in the wet gel with n-hexane that does not react with the surface modifier, the -OH groups on the surface are replaced with -CH ₃ groups by a silane coupling reaction using a silyation agent such as TMCS (trimethylchlorosilane). By modifying it, it is possible to suppress irreversible shrinkage due to condensation during drying, as well as to change the surface properties of the gel from hydrophilicity to hydrophobicity.

The change of surface properties to hydrophobicity due to surface modification can suppress/prevent deterioration of physical properties such as increases in heat and electrical conductivity caused by moisture that may occur in applications such as insulation materials and low-k thin films, and in this regard, surface properties Control is of considerable importance in the application of aerogels.

Although the wet gel with surface modification completed after solvent replacement shrinks due to capillary force due to the low surface tension of the replacement solvent during drying, the shrinkage that occurs at this time is a reversible contraction that does not accompany the condensation reaction of the internal surface groups (terminal species). Therefore, as the heat treatment process proceeds, the capillary force caused by the solvent is relieved, and at the same time, the network structure is re-expanded due to the thermal expansion of the gas inside the pores. This phenomenon is called the spring-back phenomenon and can be said to be a key commercial drying mechanism.

In the case of airgel, it is very difficult to control the nano-sized pore structure because a network of nanopore structures is formed by the sol-gel reaction and also undergoes structural change by condensation and aggregation reactions in the drying process. Therefore, the prepared airgel has a wide range of pore size distribution, which results in a wide range of properties at the same time rather than uniform properties. It is possible to improve the mechanical and thermal properties of the airgel through the control of the pore structure, size distribution, and arrangement, and the synthesis of reproducible insulation materials is possible through the establishment of a manufacturing process of a uniform porous material.

Airgel is applied in the form of blankets for piping at high or low temperatures, but currently, airgel blankets are not produced domestically, but are dependent on imports, and have limitations in application due to high prices. The Korea Energy Research Institute also carried out technology development for the localization of airgel insulation and obtained a patent for the manufacturing method of silica airgel powder. It is not easy due to the hydrophobicity of this airgel powder, and the manufacture of a composite with a polymer system has a problem in that it is difficult to make a composite by maximizing the content of the airgel powder, so that the thermal insulation property is poor.

In addition, the existing airgel has problems in that it is difficult to maintain the surface properties and it is difficult to cut the foam.

Patent Document 1: Republic of Korea Patent Publication No. 10-1155431 (Manufacturing method of silica airgel powder) Patent Document 2: Republic of Korea Patent Publication No. 10-1521793 (Manufacturing method of silica airgel powder with reduced manufacturing cost)

The present invention is to solve the above-mentioned problems, and the technical problem to be solved by the present invention is to prepare a stable silica airgel powder having superhydrophobicity in a simple process, and to provide a method for manufacturing a silica airgel composite foam applying the same. .

A method for producing a superhydrophobic silica airgel powder for achieving the above object includes: generating a silica airgel due to a gelation reaction by a sol-gel reaction using a water glass solution, a catalyst, a surfactant, and an organic silane compound; exchanging the solvent by adding an organic solvent to the airgel; filtering the solution; drying the hydrate recovered in the filtration step; A method for producing a hydrophobic silica airgel to which a surfactant is applied, characterized in that it comprises a method for solving the problem.

In addition, the composite foam manufacturing method includes the steps of mixing superhydrophobic silica airgel powder, microcapsule foam, binder, and other additives; Foaming the mixture through a microwave in a state contained in a container having a certain shape; Further drying the composite foam; a method for producing a composite foam using a hydrophobic silica airgel, characterized in that it comprises a means for solving the problem.
And, the recovery method of the silica airgel powder comprises the steps of generating a silica airgel by a sol-gel reaction using a water glass solution, a catalyst, a surfactant, and an organic silane compound; Solvent exchange of the wet gel by adding a non-polar organic solvent; filtering the wet gel solution; and drying the wet gel recovered in the filtration step; in this case, the water glass solution has a concentration of 0.2 to 1.5 M, the catalyst is an inorganic acid catalyst, and the catalyst is a silica sol at a concentration of 3.0 to 4.0 M. The mixture is mixed with stirring in a volume ratio of 1:0.2 to 0.3, the amount of the surfactant is 1:0.005 to 0.01% by weight relative to the silica solution, and the organosilane compound may have a volume ratio of 1:0.1 to 0.15 compared to the silica solution.
In addition, the organic silane compound is one of dimethoxydimethylsilane (DMDMS), methyltrimethoxysilane (MTMS), methoxytrimethylsilane (TMMS), and trimethylchlorosilane (TMCS) instead of hexamethylsilazane (HMDS), or these The solution may be a mixed solution in which at least two or more are mixed.
In addition, the organic solvent may be one of n-hexane, n-heptane, Xylene, Cyclohexane, Benzene, Toluene, and Acetone, or a mixture in which at least two or more of these solutions are mixed.
In addition, the step of exchanging the solvent may be carried out in a temperature atmosphere of 50 ℃.
And, the drying step may be performed at a temperature between 50 ℃ and 70 ℃ atmospheric pressure atmosphere.
In addition, 6.06 to 6.18 wt% of a silica solution is used in the sol-gel reaction to produce silica airgel, and the concentration of the catalyst used is 1 to 5M, and any one of nitric acid, hydrochloric acid, sulfuric acid, and acetic acid or a mixture thereof is used. can
And, in the silica airgel composite foam manufacturing method, silica airgel, a binder and additives are mixed and the mixture is put into a mold made of Teflon material, and then foamed using a microwave, and the silica airgel is a water glass solution, a catalyst, a surfactant and generating a silica airgel by a sol-gel reaction using an organosilane compound; solvent exchange by adding a non-polar organic solvent to the wet gel; filtering the wet gel solution; and drying the wet gel recovered in the filtration step; in this case, the water glass solution has a concentration of 0.2 to 1.5 M, the catalyst is an inorganic acid catalyst, and the catalyst is a silica sol at a concentration of 3.0 to 4.0 M. The mixture is mixed by stirring in a volume ratio of 1:0.2 to 0.3, the amount of the surfactant is 1:0.005 to 0.01% by weight relative to the silica solution, and the organosilane compound may have a volume ratio of 1:0.1 to 0.15 compared to the silica solution.

The manufacturing method of the silica airgel powder according to the present invention is simple and stable in the process, and since the composite foam is manufactured using microwaves, it is stable and economical and has the effect of preventing environmental pollution.

In particular, for the synthesis of mesoporous structures, the formation of a micelle structure of the surfactant and a high-temperature decomposition process therefor must be made. It acts as a very important factor in the manufacturing process, and in the present invention, it is possible to recover ultra-insulating, ultra-porous airgel powder that can maintain an optimal pore structure while maintaining surface properties.

In addition, in the present invention, in order to impart shapeness to the airgel, the microcapsule foam and binder are mixed with the airgel and foamed using a microwave to produce a composite foam, so that the powder is prevented from flying and can be used for various purposes such as insulation. There are advantages. In particular, since the foam can be cut, the workability is excellent, and there is an effect that the airgel does not separate even during long-term use.

And the present invention uses inexpensive raw materials and can be manufactured by a simple process, so that it is possible to economically recover silica airgel.

In addition, since the present invention can impart shape to the airgel, it can be made in the form of a general insulating foam block, and through this, excellent thermal insulation properties through low thermal conductivity through the nanopores of the airgel and the micro and macropores of the foam foam It is possible to produce a lighter product due to the low density of the airgel itself and the characteristics of the foam.

And, in the present invention, water repellency is imparted to the foam by applying a hydrophobic airgel. Therefore, the nanoporosity of the airgel has hygroscopicity, so it does not absorb water, but it has the property of evaporating water, so it can be used in various ways.

1 is a photograph of silica airgel powder recovered by the present invention.
Figure 2 is a photograph of a silica airgel composite foam.
3 is a flowchart sequentially showing a process for preparing a hydrophobic silica airgel powder according to the present invention.
Figure 4 is a flowchart sequentially showing the manufacturing process of the composite foam using the silica airgel according to the present invention.
5 is a particle shape (FE-SEM) of the silica airgel powder prepared according to the present invention.
6 is an FT-IR analysis result of the silica airgel powder prepared according to the present invention.

Hereinafter, only the parts necessary for understanding the technical configuration of the present invention will be described with reference to the accompanying drawings for the method for producing a hydrophobic silica airgel powder to which a surfactant is applied and a method for producing a composite foam using silica airgel according to the present invention, It should be noted that descriptions of other parts will be omitted so as not to obscure the gist of the present invention.

The present invention can be broadly divided into two manufacturing methods, first, to prepare a silica airgel powder, and to prepare a composite foam including the thus-made silica airgel powder.

Below, we will first look at the process of manufacturing silica airgel powder.

In the step of generating the silica airgel of the present invention, water glass (Na ₂ SiO ₃ , SiO ₂ 30wt%) is diluted to a concentration of 0.2 to 1.5 M and mixed for 30 minutes or more, and then an acidic solution of 0.5 to 5.0 M concentration is added to the silica sol. The first step of mixing is preceded by stirring in a volume ratio of 1:0.1 to 0.5 (V _{silica sol} : V _{acidic solution} ). (S100) Preferably, an acidic solution of 3.0 to 4.0 M is used to compare 1 to silica sol. It is preferable to mix by stirring in a volume ratio of: 0.2 to 0.3, and it is necessary to prevent gelation of the silica sol during mixing. The acidic solution is an organic acid such as hydrochloric acid, sulfuric acid, acetic acid, and nitric acid, and at least one acidic solution may be used, but is not limited thereto.

In this case, a second step of adjusting the particle shape, specific surface area, pore size, etc. of the silica airgel by adding a surfactant to the silica sol is included. (S200) The surfactant is used in a volume ratio of 1:0.005 to 0.01 compared to the silica sol It is preferable to mix by stirring, and it is more preferable to use it in a volume ratio of 1:0.007 or less. It is preferable to use a minimum amount of surfactant, and when not used, the shape of the silica particles is not controlled. The surfactant is an anionic surfactant, sodium fatty acid (RCOO ^- Na ⁺ ), monoalkyl sulfate (RO(CH ₂ CH ₂ O) _m SO ^3- ), polyoxyethylene sulfate (RO(CH ₂ CH ₂ O) _m SO ^3- M ⁺ ), alkylbenzenesulfonate (RR'CH ₂ CHC ₆ H ₄ SO ^3- M ⁺ ), noalkyl phosphate (ROPO(OH)O ^- M ⁺ ), monoalkyl as a cationic surfactant Trimethylammonium salt (RN ⁺ (CH ₃ ) ₃ X ^- ), dialkyldimethylammonium salt (RR'N ⁺ (CH ₃ ) ₂ X ^- ), alkylbenzylmethylammonium salt (RN ⁺ (CH ₂ PH)(CH ₃ ) ₂ X ^- ), as an amphoteric surfactant, alkylsulfobetaine (RR'R ^〃 N ⁺ (CH ₂ )nSO ₃ ), alkylcarboxybetaine (R(CH ₃ ) ₂ N ⁺ CH ₂ COO ^- ), nonionic surfactant Phosphorus polyoxyethylene alkyl ether (RO(CH ₂ CH ₂ O) _m H), fatty acid diethanolamine (RCON(CH ₂ CH ₂ OH) ₂ ), alkylmonoglyceryl ether (ROCH ₂ CH(OH)CH ₂ OH) and the like may be used, but is not limited thereto.

Through the second step of adding such a surfactant, a hydrophobic airgel with a modified surface can be obtained.

On the other hand, the third step of preparing a silica airgel by adding an organosilane compound to the silica sol may be further included. (S300) The organosilane compound is preferably used in a volume ratio of 1: 0.05 to 0.2 compared to the silica sol, It is more preferable to use it in a volume ratio of 1: 0.1 to 0.15. Examples of the organosilane compound include trimethylchlorisilane (TMCS), hexamethyldisilazane (HMDS), methyltrimethoxysilane (MTMS), trimethylethoxysilane (TMES), and ethyltriethane. Toxysilane (ethyltriethoxysilane), phenyltriethoxysilane (phenyltriethoxysilane), dimethoxydimethylsilane (Demethoxydimethylsilane, DMDMS), methoxytrimethylsilane (Methoxytrimethylsilane, TMMS), etc. may be used, but is not limited thereto.

On the other hand, in the present invention, unlike performing the conventional silica airgel formation and surface modification process separately, by performing both processes at the same time, a sufficient surface modification effect can be obtained and the process speed can be increased. That is, the above second step and the third step can be performed simultaneously. Of course, the above two steps may be performed in sequence.

_{Subsequently, the fourth step (S400) of replacing the solvent is a step of substituting an organic solvent for moisture (H 2} O), etc. present in the airgel in the step of generating the silica airgel, which can be said to be a step to complete the surface modification. have. As the non-polar organic solvent used in the above step, n-hexane, n-heptane, Xylene, Cyclohexane, Benzene, Toluene, Acetone, etc. may be used, and it is more preferable to use n-hexane or Acetone. The non-polar organic solvent is preferably used in a volume ratio of 1:0.3 to 1.5 compared to silica airgel, and more preferably used in a volume ratio of 1:0.3 to 0.7. When the volume ratio of the organic solvent is less than 0.3, complete solvent replacement does not occur and the density of the powder increases.

And a fifth step (S500) of filtering the silica airgel is followed. The fifth step is to remove water, an organic solvent, an organic silane compound, etc. remaining in the solution in which the silica airgel is generated, and it is preferable to use a centrifugal separator or a filter press.

Finally, the sixth step (S600) of drying the silica airgel is a step of obtaining a powder by drying the silica airgel under atmospheric pressure. Drying is performed in two steps at a temperature of 50 to 200 °C, and after primary drying at a temperature of 50 to 100 °C for 1 to 4 hours, secondary drying is preferably performed at 200 °C or less for 1 to 4 hours. The primary drying is more preferably dried at 60° C. for 1 hour and then dried at 150° C. for 2 hours.

Through these steps, a hydrophobic silica airgel powder to which a surfactant is applied is prepared. Next, a process of making a composite foam using a hydrophobic silica airgel powder to which such a surfactant is applied will be described.

First, the composite foam using the silica airgel powder prepared by the method described above includes the silica airgel powder, the microcapsule foam and the binder, and additives. So, first, a seventh step (S700) of mixing them is performed, which is a step of mixing and manufacturing raw materials for forming a foam, and each composition is arbitrarily set and mixed.

Here, the additive is a flame retardant, and various kinds of flame retardants may be applied. For example, the melamine-based flame retardant is less toxic than the halogen-based flame retardant and is not only easy to handle, but also rarely generates toxic gas during thermal decomposition so that it does not affect human health and the environment. The melamine-based flame retardant may include melamine, melamine cyanurate, melamine phosphate, melamine polyphosphate, melamine borate, and the like. In addition, phosphorus (P)-based flame retardants react with combustible materials in the combustion process to form a carbonaceous layer on the polymer surface, and this carbonaceous film blocks oxygen required for combustion to exhibit a flame retardant effect. , Any one or more of ammonium phosphate, ammonium polyphosphate, metal phosphinate, or melamine polyphosphate may be used.

In addition to this, a dispersant may be used for dispersing the airgel. These dispersants are added for deagglomeration and stability maintenance of the airgel, and those generally used in the art may be used without limitation. For example, commercially available dispersants include DISPER BYK-2001, DISPER BYK-2100, DISPER BYK-180, DISPER BYK-102, and the like.

In the seventh step, it is preferable to use a mixer for more effective mixing. The binder used in the above step is vinyl acetate (EVA)-based, polyvinyl alcohol (PVA)-based, acrylic (Acryl)-based, acrylamide (Acrylamide)-based, vinyl chloride (PVC)-based, polyvinyl acetal-based , acrylic, saturated polyester, polyamide, polyethylene, natural rubber, silicone, or melamine, or a mixture thereof may be used.

After mixing, the eighth step (S800) of foaming the mixture in a container having a certain shape is followed. Step 8 is made by manufacturing a container made of Teflon material, putting the foaming mixture into the container, and then foaming using a microwave. Foaming can be made by foaming the microwave power at 5-20 KW for 3-20 minutes. It is more preferable to foam for 5 minutes at 6 KW of microwave power. If the microwave power is very high or the foaming time is long, the foam may burn due to the high temperature and shrink after complete foaming.

Finally, a ninth step (S900) of additional drying is followed. The ninth step is to remove moisture that may remain in the composite foam, and it is preferable to dry it at 80 to 120° C. for 10 to 48 hours. It is more preferable to dry at 100° C. for 24 hours.

Hereinafter, the present invention will be described in detail through the following examples, and the present invention is not necessarily limited only by the following examples.

First, an example in which silica airgel powder was prepared will be described.

[Silica Airgel Powder Preparation Example]

(Example 1)

Industrial sodium silicate solution (manufacturer: Yeongilhwaseong, No. 3, SiO ₂ 30.01% by weight) was diluted to prepare a 6.18% by weight solution, the total amount of the solution was 38.47 mL, and the solution was used.

After mixing 11 mL of 5 M nitric acid solution with the silica solution and stirring for 2-3 minutes, 0.01 g of Span-80 surfactant was additionally added and stirred for 2-3 minutes. In this step, gelation did not proceed.

Then, for the gelation reaction, 10 mL of hexamethyldisilazane (HMDZ), an organic silane compound, was added and stirred for 2 more minutes to proceed with the sol-gel reaction to produce a wet gel (P100), and the entire mixed solution was very It gelled in a short time.

Surface modification (P200) was performed while stirring for 2 hours by adding 50 mL of n-hexane to the wet gel. Residual moisture, n-hexane, an organic silane compound, etc. were removed from the surface-modified solution through a pressure filtration method (P300).

After filtration, the wet gel was placed in a drying oven and first dried at 50° C. for 1 hour under atmospheric pressure, and then secondary dried (P400) at 150° C. for 2 hours to finally obtain silica airgel powder.

(Example 2)

In order to confirm the effect of the type of the organic silane compound used in the gelation reaction, dimethoxydimethylsilane (DMDMS), methyltrimethoxysilane (MTMS) instead of hexamethylsilazane (HMDS) as the organic silane compound of Example 1 ), methoxytrimethylsilane (TMMS), and trimethylchlorosilane (TMCS) were respectively added and used by adding 10 mL of silica airgel powder under the same conditions as in Example 1.

(Example 3)

In order to confirm the effect of the amount of the organic silane compound (HMDZ) used in the gelation reaction, silica airgel powder was prepared under the same conditions as in Example 1 except that the amount of the organic silane compound in Example 1 was changed and used. prepared.

(Example 4)

In order to confirm the effect depending on the type of organic acid used in the gelation reaction, a silica airgel powder was prepared under the same conditions as in Example 1, except that the organic acid of Example 1 was changed and used.

(Comparative Example 1)

Industrial sodium silicate solution (manufacturer: Yeongilhwaseong, No. 3, SiO ₂ 30.01% by weight) was diluted to prepare a solution of 6.06% by weight, and a cation exchange resin was applied to an ion exchange resin tower to remove the sodium (Na) component as an impurity. The silica sol was recovered by removing the sodium component by passing the water glass solution through the resin tower.

A wet gel was synthesized by adding aqueous ammonia (3M) to the silica sol (500 mL) from which impurities were removed and adjusting the pH to 5.1.

Isopropyl alcohol (IPA), n-hexane, and trimethylchlorosilane (TMCS) were sequentially mixed with the recovered wet gel, followed by surface modification and solvent replacement at 50° C. for 3 hours.

After separating and recovering the wet gel, it was placed in a drying oven, dried first at 50° C. under atmospheric pressure for 1 hour, and then secondary dried at 150° C. for 2 hours to finally obtain silica airgel powder.

(Comparative Example 2)

Industrial sodium silicate solution (manufacturer: Yeongil Hwaseong, No. 3, SiO ₂ 30.01 wt%) was diluted to prepare a 6.13 wt% solution.

Based on the volume of the water glass solution, a mixed solvent of 2/3 of ethanol and 1/1 of water was prepared. A wet gel was formed by adding a water glass solution to the mixed solvent. Unlike other examples, acid treatment was not carried out.

After the wet gel was separated and recovered, surface modification, solvent replacement, and drying were performed in the same manner as in Comparative Example 1 to finally obtain a silica airgel powder.

For the silica airgel powder prepared by the method of Examples 1 to 4 and Comparative Examples 1 and 2, the results of checking the tap density, specific surface area, contact angle, and the volume and size of micropores are shown in Table 1 below.

Manufacturing method tap density
[g/mL] specific surface area
[m ² /g] average pore size
[nm] pore volume
[mL/g] contact angle
[°] Example 1 0.07 781 13.98 3.27 142 Example 2-1 0.19 548 20.13 2.39 142 Example 2-2 0.50 257 9.914 0.41 10 Example 2-3 0.42 314 12.20 0.62 107 Example 2-4 0.16 578 21.45 2.96 128 Example 3-1 0.12 684 14.05 3.24 141 Example 3-2 0.13 671 16.27 3.54 136 Example 3-3 0.28 598 15.23 2.98 129 Example 4-1 0.17 494 24.7 3.05 127 Example 4-2 0.16 586 25.84 3.79 125 Comparative Example 1 0.31 824 4.2 1.46 136 Comparative Example 2 0.05 324 5.4 0.05 138

As shown in Table 1 above, the silica airgel powder according to the present invention had a relatively large average pore size and pore volume, and the specific surface area was improved through the surfactant, and the contact angle was improved through the surface modification process.

Next, an example in which a composite foam including silica airgel powder was prepared will be described.

[Example of manufacturing composite foam]

(Example 5)

The silica airgel powder, binder, and other additives obtained in Example 1 are mixed by selecting a predetermined mixing ratio, and the mixed composition is put into a mold made of Teflon material. Thereafter, the mold is put into a microwave and irradiated with microwaves to foam. When foaming is completed, the mold is naturally cooled. The molded body foamed from the cooled mold is demolded. The demolded molded body is further dried at 100° C. for 8 hours.

(Example 6)

A silica airgel composite foam was prepared under the same conditions as in Example 5 except that the mixing ratio of Example 5 was changed.

(Comparative Example 3)

The mixture having the same composition as in Example 5 was heat-treated at 150° C. to 200° C. for 2 hours by pressing the mold mold, and then the heat-treated mold mode was cooled.

The molded body formed in the cooled mold was degreased.

(Comparative Example 4)

A silica airgel composite foam was prepared under the same conditions as in Comparative Example 3, except that the mixing ratio of Comparative Example 3 was changed. That is, in Comparative Examples 3 and 4, the process of foaming by putting it in a microwave was omitted.

For the silica airgel composite foam prepared by the method of Examples 5 to 4, the results of checking the thermal conductivity, flexural strength, compressive strength, flame retardancy and water absorption are shown in Table 2 below.

Manufacturing method thermal conductivity
[mW/m K] compressive strength
[N/cm ² ] flexural strength
[N/cm ² ] flexural failure load
[N] agas hazard
[minute] Example 5 0.017 12 152 43 14.0 Example 6-1 0.019 12 140 38 9.2 Example 6-2 0.023 13 136 41 7.6 Example 6-3 0.025 13 124 32 4.3 Comparative Example 3 0.045 8 84 19 3.7 Comparative Example 4-1 0.050 7 55 15 3.5 Comparative Example 4-2 0.058 7 34 10 3.2 Comparative Example 4-3 0.042 8 59 13 3.0

As shown in the table above, it can be seen that the composite foam made in the embodiment according to the present invention is excellent in all areas of thermal conductivity, compressive strength, flexural strength, flexural fracture load and gas toxicity.

The present invention was able to recover the silica airgel powder having a nanopore structure, as confirmed by the above examples, and it was possible to prepare a composite foam in which thermal insulation properties were secured by using the airgel powder.

As described above, in the manufacturing method of silica airgel powder and composite foam according to a preferred embodiment of the present invention, silica airgel having a high porosity is recovered and the powder is used in the composite foam, thereby having high thermal insulation properties and compressive strength. , it is possible to manufacture a type of insulating material with improved absorption and gas hazard properties.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

Claims (15)

A method for recovering silica airgel powder, the method comprising:
producing a silica airgel by a sol-gel reaction using a water glass solution, a catalyst, a surfactant, and an organic silane compound;
solvent exchange by adding a non-polar organic solvent to the wet gel;
filtering the wet gel solution;
drying the wet gel recovered from the filtration step;
including,
The water glass solution has a concentration of 0.2 to 1.5 M, the catalyst is an inorganic acid catalyst, and the catalyst is mixed by stirring at a volume ratio of 1:0.2 to 0.3 compared to silica sol at a concentration of 3.0 to 4.0 M,
The amount of the surfactant used is 1:0.005 to 0.01% by weight relative to the silica solution, and the organic silane compound is a method for producing a silica airgel powder having a volume ratio of 1:0.1 to 0.15 compared to the silica solution.
delete According to claim 1,
The organosilane compound is one of dimethoxydimethylsilane (DMDMS), methyltrimethoxysilane (MTMS), methoxytrimethylsilane (TMMS), and trimethylchlorosilane (TMCS) instead of hexamethylsilazane (HMDS) or a solution thereof A method for producing silica airgel powder, which is a mixed solution in which at least two or more are mixed.
According to claim 1,
The organic solvent is one of n-hexane, n-heptane, Xylene, Cyclohexane, Benzene, Toluene, and Acetone, or a method for producing a silica airgel powder in which at least two of these solutions are mixed.
5. The method of claim 4,
The step of exchanging the solvent is a method of producing a silica airgel powder that is carried out in a temperature atmosphere of 50 ℃.
According to claim 1,
The drying of the wet gel is a method of manufacturing a silica airgel powder, characterized in that after primary drying for 1 to 4 hours at a temperature of 50 ~ 100 ℃, and then secondary drying at 200 ℃ or less for 1 ~ 4 hours.
According to claim 1,
A method for producing a silica airgel powder in which 6.06 to 6.18 wt% of a silica solution is used in the sol-gel reaction to produce silica airgel.
delete In the silica airgel composite foam manufacturing method,
After mixing the silica airgel, the binder and the additives, the mixture is put into a mold made of Teflon material, and then foamed using a microwave,
The silica airgel is
producing a silica airgel by a sol-gel reaction using a water glass solution, a catalyst, a surfactant, and an organic silane compound;
solvent exchange by adding a non-polar organic solvent to the wet gel;
filtering the wet gel solution;
drying the wet gel recovered from the filtration step;
including,
The water glass solution has a concentration of 0.2 to 1.5 M, the catalyst is an inorganic acid catalyst, and the catalyst is mixed by stirring at a volume ratio of 1:0.2 to 0.3 compared to silica sol at a concentration of 3.0 to 4.0 M,
The amount of the surfactant used is 1:0.005 to 0.01% by weight relative to the silica solution, and the organic silane compound is a method for producing an airgel composite foam having a volume ratio of 1:0.1 to 0.15 compared to the silica solution.
10. The method of claim 9,
The drying of the wet gel is a method of manufacturing an airgel composite foam, characterized in that after primary drying at a temperature of 50 to 100 ° C. for 1 to 4 hours, and then secondary drying at 200 ° C. or less for 1 to 4 hours.
10. The method of claim 9,
The binder is vinyl acetate (EVA)-based, polyvinyl alcohol (PVA)-based, acryl (Acryl)-based, acrylamide (Acrylamide)-based, vinyl chloride (PVC)-based, polyvinyl acetal (Polyvinyl acetal)-based, saturated polyester A method of manufacturing an airgel composite foam foamed using any one of, polyamide-based, polyethylene-based, natural rubber-based, silicone-based, or melamine-based, or a mixture thereof.
10. The method of claim 9,
Method for producing an airgel composite foam, characterized in that the foaming using a microwave in the foaming step.
delete delete 13. A composite foam made by the manufacturing method of any one of claims 9 to 12.

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