KR102475766B1 - Manufacturing process silica aerogel blanket using recycled solvent - Google Patents

Abstract

The present invention relates to a method for manufacturing a silica airgel blanket using a recycled solvent, and more specifically, it is possible to reduce the cost of manufacturing a silica airgel blanket by recycling a surface modification solution recovered in a surface modification process during the manufacturing process of a silica airgel blanket, and at the same time, the surface Provided is a method for manufacturing a silica airgel blanket capable of securing physical properties equivalent to those of a silica airgel blanket manufactured using a fresh solvent even when the modified solution is continuously recycled.

Description

Silica airgel blanket manufacturing method using recycled solvent {MANUFACTURING PROCESS SILICA AEROGEL BLANKET USING RECYCLED SOLVENT}

The present invention relates to a method for manufacturing a silica airgel blanket using a recycled solvent.

Airgel is a highly porous material composed of nanoparticles, and has a high porosity, specific surface area, and low thermal conductivity, and is attracting attention as a highly efficient heat insulating material and sound insulating material. Since such airgel has a very low mechanical strength due to its porous structure, an airgel blanket composite in which airgel is impregnated and bonded to a fibrous blanket such as inorganic fibers or organic fibers, which are conventional insulation fibers, has been developed.

On the other hand, the market for airgel blankets is not growing compared to advantages such as excellent insulation performance and convenient workability compared to existing insulation materials, and the reason is high cost. This is because the price of the product is relatively high compared to other insulation materials due to expensive raw materials, complicated manufacturing processes, and disposal costs of a large amount of waste solvents generated during the manufacturing process.

Among the above price increase factors, cost reduction by replacing raw materials or changing the manufacturing process is difficult to apply because it can directly affect product quality. A method for recycling waste solvents.

Specifically, the present invention can reduce manufacturing cost by recycling the surface modification solution recovered in the surface modification process of the silica airgel blanket manufacturing process, and even if the surface modification solution is continuously recycled, it is manufactured using a fresh solvent. It is intended to provide a method for manufacturing a silica airgel blanket capable of securing physical properties equivalent to those of a silica airgel blanket.

Korean Patent Publication No. 2017-0110994 (published on October 12, 2017)

An object to be solved by the present invention is to provide a method for manufacturing a silica airgel blanket, which can reduce the cost of manufacturing a silica airgel blanket by recycling a surface modification solution recovered in a surface modification process of a silica airgel blanket manufacturing process.

In addition, it is to provide a method for manufacturing a silica airgel blanket capable of securing physical properties equivalent to those of a silica airgel blanket manufactured using a fresh solvent even when the surface modification solution is continuously recycled.

The present invention relates to a method for manufacturing a silica airgel blanket,

1) recovering the surface modification solution after the surface modification process;

2) replenishing a surface modifier to the recovered surface modification solution; and

3) recycling the surface modification solution supplemented with the surface modifier;

The content of the supplemented surface modifier is 60 to 75 wt% relative to the content of the surface modifier included in the surface modification solution used in the surface modification process of step 1).

According to the method for manufacturing a silica airgel blanket of the present invention, the surface modification solution can be recycled, thereby reducing the manufacturing cost of the silica airgel blanket.

Specifically, the present invention introduces a step of quantifying the amount of the surface modifier through GC (gas chromatography) analysis of the surface modifying solution recovered in the surface modification process and supplementing the surface modifier only to the required amount, thereby reducing the amount of surface modifier used. Additional cost reduction can be achieved, and overconcentration of the surface modifying agent due to repeated recycling of the surface modification solution can be prevented, so that the surface modification solution can be permanently recycled.

Accordingly, even if the surface modification solution is continuously recycled, it is possible to secure physical properties equivalent to those of a silica airgel blanket manufactured using a fresh solvent.

The following drawings attached to this specification illustrate specific embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the contents of the above-described invention, so the present invention is limited to those described in the drawings. It should not be construed as limiting.
1 is a graph showing the change in the content of the surface modifier according to repeated recycling of the surface modification solutions of Example 1 and Comparative Example 4.

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention. At this time, the terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor appropriately defines the concept of terms in order to explain his/her invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be done.

The present invention relates to a method for manufacturing a silica airgel blanket using a recycled solvent, and more specifically, it is possible to reduce the cost of manufacturing a silica airgel blanket by recycling a surface modification solution recovered in a surface modification process during the manufacturing process of a silica airgel blanket, and at the same time, the surface An object of the present invention is to provide a method for manufacturing a silica airgel blanket capable of securing physical properties equivalent to those of a silica airgel blanket manufactured using a fresh solvent even when the modified solution is continuously recycled.

The silica airgel blanket of the present invention is manufactured by a silica sol preparation process, a gelation process, an aging process, a surface modification process, and a drying process. Hereinafter, the method for manufacturing a silica airgel blanket and the method for recycling a surface modification solution according to the present invention will be described in detail.

Silica sol manufacturing process

The silica sol of the present invention is characterized in that it is prepared by mixing a silica precursor, an alcohol and an acidic aqueous solution.

The silica precursor usable for preparing the silica sol may be a silicon-containing alkoxide-based compound, specifically tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), methyltriethyl methyl triethyl orthosilicate, dimethyl diethyl orthosilicate, tetrapropyl orthosilicate, tetraisopropyl orthosilicate, tetrabutyl orthosilicate ), tetra secondary butyl orthosilicate, tetra tertiary butyl orthosilicate, tetrahexyl orthosilicate, tetracyclohexyl orthosilicate , tetraalkyl silicate such as tetradodecyl orthosilicate. More specifically, in the case of the present invention, the silica precursor may be tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), or a mixture thereof.

The silica precursor may be used in an amount such that the content of silica (SiO ₂ ) in the silica sol is 0.1 to 30 wt%. If the silica content is less than 0.1 wt%, the content of the silica airgel in the finally manufactured blanket is too low, and a desired level of insulation effect cannot be expected, and if it exceeds 30 wt%, excessive silica airgel is formed. There is a possibility that the mechanical properties of the blanket, in particular, the flexibility may be deteriorated.

In addition, the alcohol usable for preparing the silica sol of the present invention may specifically include monohydric alcohols such as methanol, ethanol, isopropanol, and butanol; Alternatively, polyhydric alcohols such as glycerol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and sorbitol may be used, and any one or a mixture of two or more thereof may be used. Among them, considering miscibility with water and airgel, it may be a monohydric alcohol having 1 to 6 carbon atoms such as methanol, ethanol, isopropanol, butanol, and the like.

The alcohol (polar organic solvent) as described above may be used in an appropriate amount in consideration of the degree of hydrophobicity of the silica airgel to be finally prepared while accelerating the surface modification reaction.

In addition, the acidic aqueous solution usable for preparing the silica sol of the present invention can promote gelation of the silica sol thereafter. The acid catalyst included in the acidic aqueous solution may specifically include one or more inorganic acids such as nitric acid, hydrochloric acid, acetic acid, sulfuric acid, and hydrofluoric acid, and may be used in an amount that promotes gelation of the silica sol.

gelation process

The gelation process of the present invention may be performed by adding a base catalyst to the silica sol and depositing it on a substrate for a blanket.

The base catalyst that can be used to prepare the silica gel of the present invention serves to promote gelation by increasing the pH of the silica sol.

Examples of the base catalyst include inorganic bases such as sodium hydroxide and potassium hydroxide; Alternatively, an organic base such as ammonium hydroxide may be used, but in the case of an inorganic base, since metal ions included in the compound may be coordinated with the Si—OH compound, an organic base may be preferable. Specifically, the organic base is ammonium hydroxide (NH ₄ OH), tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), methylamine, ethylamine, isopropylamine, monoisopropylamine, diethylamine, diisopropylamine, dibutylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, choline, Monoethanolamine, diethanolamine, 2-aminoethanol, 2-(ethylamino)ethanol, 2-(methylamino)ethanol, N-methyl diethanolamine, dimethylaminoethanol, diethylaminoethanol, nitrilotriethanol, 2 -(2-aminoethoxy)ethanol, 1-amino-2-propanol, triethanolamine, monopropanolamine, or dibutanolamine, and the like, any one or a mixture of two or more of these may be used. More specifically, in the case of the present invention, the base may be ammonium hydroxide (NH ₄ OH).

The base catalyst may be included in an amount such that the pH of the silica sol is 4 to 8. If the pH of the silica sol is out of the above range, gelation may not be easy or the gelation rate may be excessively slow, resulting in deterioration in fairness. In addition, since the base may precipitate when added in a solid state, it may be preferable to add it in a solution diluted with the alcohol (polar organic solvent).

The gelation of the silica airgel blanket manufacturing method of the present invention may be to form a network structure from a silica precursor material, and the network structure is a plane in which a specific polygonal arrangement of one or more types of atoms is connected. It may represent a net-like structure or a structure that forms a three-dimensional skeletal structure by sharing vertices, edges, faces, etc. of a specific polyhedron.

Meanwhile, gelation of the silica sol may occur in a state in which the silica sol is deposited on a substrate for a blanket.

Specifically, the deposition may be performed in a reaction vessel capable of accommodating a substrate for a blanket, and the deposition may be performed by pouring silica sol into the reaction vessel or by putting the substrate for a blanket in a reaction vessel containing silica sol and soaking it. have. At this time, in order to improve the bonding between the blanket substrate and the silica sol, the blanket substrate may be lightly pressed so that the silica sol is sufficiently deposited. Thereafter, the blanket substrate is pressed with a constant pressure to a certain thickness to remove excess silica sol, and the subsequent drying time may be reduced.

The substrate for a blanket usable in the present invention may be a film, a sheet, a net, a fiber, a porous material, a foam, a nonwoven fabric, or a laminate of two or more layers thereof. In addition, depending on the use, surface roughness may be formed or patterned on the surface. More specifically, the blanket substrate may be a fiber capable of further improving thermal insulation performance by including spaces or voids into which silica airgel is easily inserted into the blanket substrate. In addition, the substrate for the blanket may preferably have low thermal conductivity.

Specifically, the substrate for the blanket is polyamide, polybenzimidazole, polyaramid, acrylic resin, phenolic resin, polyester, polyether ether ketone (PEEK), polyolefin (eg, polyethylene, polypropylene or copolymers thereof). etc.), cellulose, carbon, cotton, wool, hemp, nonwoven fabric, glass fiber or ceramic wool, etc., and more specifically, the substrate for the blanket may include glass fiber or polyethylene.

aging process

The aging process of the present invention is to leave the silica gel at an appropriate temperature to complete the gelation reaction.

The aging process of the present invention may be performed by leaving it in an organic solvent at a temperature of 50 to 90 ° C. for 1 to 10 hours. In the present invention, by going through the aging process, the formed network structure can be formed more firmly, thereby enhancing mechanical stability.

surface modification process

The dried silica airgel maintains low thermal conductivity immediately after drying, but has a disadvantage in that the thermal conductivity gradually increases due to the hydrophilicity of the silanol group (Si-OH) on the silica surface, absorbing water in the air. Therefore, in order to maintain low thermal conductivity, it is necessary to modify the surface of the silica airgel to be hydrophobic.

The surface modification solution of the present invention means containing a surface modifier and an organic solvent, and the organic solvent may use at least one selected from the group consisting of methanol, ethanol, hexane and pentane. Ethanol can be used if

In addition, the surface modifier is trimethylchlorosilane (TMCS), hexamethyldisilazane (HMDS), trimethylsilanol (TMS), trimethylethoxysilanol (Trimethylethoxysilanol, TMES), hexamethyldisiloxane (Hexamethyldisiloxane, HMDSO), methyltrimethoxysilane, trimethylethoxysilane, ethyltriethoxysilane, phenyltriethoxysilane and polydimethylsiloxane At least one selected from may be used, and more specifically, in the case of the present invention, hexamethyldisilazane (HMDS), trimethylsilanol (TMS), trimethylethoxysilanol (Trimethylethoxysilanol, TMES), or hexamethyldisilazane (HMDS). Methyldisiloxane (Hexamethyldisiloxane, HMDSO) can be used.

The surface modification solution used in the surface modification process may be used in an amount of 80 to 110 vol%, more specifically, 85 to 95 vol%, based on the volume of the silica gel used to prepare the silica airgel blanket.

When the surface modification solution is used within the above range, the silica gel can be sufficiently immersed in the surface modification solution, while cost increase due to excessive use of the surface modification solution and shrinkage caused by the unreacted surface modifier can be minimized. Therefore, the above range is particularly appropriate in terms of surface modification reaction time, reaction efficiency, and economics.

In addition, the surface modifier included in the surface modification solution used in the surface modification process may be 2 to 10 wt%, more specifically 3 to 6 wt%, based on the weight of the surface modification solution.

When the surface modifier included in the surface modification solution is used within the above range, cost increase due to excessive use of the surface modification solution and shrinkage caused by the unreacted surface modifier can be minimized. Therefore, the above range is particularly appropriate in terms of surface modification reaction time, reaction efficiency, and economics.

The hydrophilic silica gel is modified into a hydrophobic silica gel by the surface modification process. Specifically, a hydrophilic silica wet gel blanket can be changed into a hydrophobic silica wet gel blanket by substituting an alkyl group or an aryl group for a hydroxyl group (OH) on the silica gel surface of the silica wet gel blanket.

surface modification Solution recycling process

However, since the surface modification process uses a large amount of expensive organic solvents and surface modifiers, recycling of the surface modification solution recovered in the surface modification process is inevitable in order to reduce the manufacturing cost of the silica airgel blanket, which is the object of the present invention.

The present invention is a novel surface modification capable of securing physical properties equivalent to those of a silica airgel blanket prepared using a fresh solvent that does not contain impurities, even if the surface modification solution recovered after the surface modification process is continuously recycled. A method for recycling a solution and a method for manufacturing a silica airgel blanket including the same are provided.

Specifically, the present invention relates to a method for manufacturing a silica airgel blanket,

1) recovering the surface modification solution after the surface modification process;

2) replenishing a surface modifier to the recovered surface modification solution; and

3) recycling the surface modification solution supplemented with the surface modifier;

The content of the supplemented surface modifier is set to be 60 to 75 wt% compared to the content of the surface modifier contained in the surface modification solution used in the surface modification process of step 1) to achieve the above object.

The reason for replenishing the surface modifier to the surface modification solution recovered after the surface modification process in step 2) is to maintain the same content of the surface modifier included in the surface modification solution used in the surface modification process.

If a lack of surface modifier occurs due to the surface modification reaction that occurred in the surface modification process, and the surface modification solution recovered after the surface modification process is directly recycled without making up for the shortage, the surface modification in the next batch of surface modification process This is because the hydrophobic degree of the silica airgel blanket is reduced because the reaction is not sufficiently performed, and thus the thermal insulation performance may also be deteriorated.

However, even if the surface modifier is supplemented to secure excellent physical properties, if the same amount of surface modifier is added at each recycling stage, the effect of reducing the amount of the expensive surface modifier cannot be seen, and the physical properties of the silica airgel blanket can be adversely affected. .

The concentration of the surface modifier contained in the surface modification solution that is recycled repeatedly is overconcentrated to a certain level, and the remaining surface modifier that does not participate in the surface modification reaction makes the gel soft, thereby preventing uniform pore formation. because you can get

Accordingly, the present invention is characterized by quantifying the amount of the surface modifier to be supplemented through GC (gas chromatography) analysis of the surface modification solution recovered after the surface modification process.

Therefore, the present invention is characterized in that the amount of the surface modifier to be replenished is identified and supplemented so that the content of the surface modifier included in the surface modification solution used in each stage of the surface modification process can be kept the same.

Through this, the present invention can supplement only the insufficient amount of the surface modifier, thereby reducing the amount of expensive surface modifier used, thereby achieving additional manufacturing cost savings, and preventing the surface modification solution from being over-concentrated, so that the surface modification solution can be continuously recycled Even with the method, it is possible to secure physical properties equivalent to those of a silica airgel blanket prepared using a fresh solvent.

Specifically, in the present invention, the content of the supplemented surface modifier is 60 to 75 wt%, more specifically 65 to 70 wt%, relative to the content of the surface modifier included in the surface modification solution used in the surface modification process of step 1). It is characterized by being In other words, it means that it is 60 to 75 wt%, more specifically 65 to 70 wt%, relative to the content of the surface modifier contained in the surface modification solution used in the surface modification process of the previous batch.

This is because the present invention is characterized by maintaining the same content of the surface modifier included in the surface modification solution used in the surface modification process of step 1).

If the amount of the supplemented surface modifier is less than the above range, the hydrophobicity of the silica airgel blanket may decrease, resulting in poor thermal insulation performance. Accordingly, uniform pore formation may be hindered, resulting in poor thermal insulation performance, and permanent recycling of the surface modification solution may be impossible.

The surface modification solution supplemented with the surface modifier of the present invention is characterized in that it is recycled in the surface modification process of step 1) of the next batch, and the recycled surface modification solution is 70 to 70% of the weight of the surface modification solution required in the surface modification process. 100 wt%, more specifically 80 to 95 wt%. The rest of the surface modification solution required in the surface modification process may be supplemented with a fresh surface modifying solution used initially.

When the content of the recycled surface modification solution relative to the weight of the surface modification solution required in the surface modification process is within the above range, organic solvent treatment and disposal costs can be reduced, and it is particularly preferable in terms of reducing raw material costs and protecting the environment.

In addition, the surface modifier included in the surface modification solution recovered after the surface modification process is 3 wt% or less, more specifically, 2.5 wt% or less, based on the weight of the surface modification solution.

When the surface modifier included in the surface modification solution recovered after the surface modification process is within the above range, it is possible to maintain constant thermal conductivity of the silica airgel blanket.

The surface modification solution recovered after the surface modification process of the present invention can be repeatedly recycled several times through the steps 1) to 3) discussed above, so that the surface modification mother liquor can be permanently reused.

drying process

Thereafter, the hydrophobic silica airgel blanket may be manufactured through a drying process of removing the solvent while maintaining the pore structure of the surface-modified hydrophobic silica airgel blanket. The drying process may be atmospheric drying or a supercritical drying process, but the method for manufacturing a silica airgel blanket according to the present invention may be particularly performed by a supercritical drying process using supercritical carbon dioxide.

The normal pressure drying process does not require high-pressure reaction conditions and special high-pressure equipment for supercritical drying, so the process is simple and economical, but as water or organic solvent evaporates at a high temperature, There may be a problem in that the collapse of the internal pore structure occurs and the insulation performance is rapidly deteriorated. In addition, the above problem may be further aggravated in the case of direct drying without substitution with an organic solvent having low surface tension.

On the other hand, the drying of the present invention can maximize the porosity by supercritical drying, and thus the insulation performance can be far superior to that of the silica airgel blanket by atmospheric pressure drying. Therefore, it is preferable to use a supercritical drying process for a silica airgel blanket used for a heat insulating material.

However, as a process for removing a small amount of solvent that is not completely removed in the supercritical drying step after the supercritical drying and a hydrophilic salt that may be generated by meeting ammonia and CO ₂ inside the gel during supercritical drying, an atmospheric pressure drying process is optionally performed. may be performed additionally.

In view of the fact that the atmospheric drying process additionally performed is not an essential process and the destruction of the pore structure is not large, the atmospheric drying process in which the entire solvent is removed by atmospheric pressure drying is different from the drying process of the present invention in terms of purpose and effect. has a different aspect.

Carbon dioxide (CO ₂ ) is in a gaseous state at normal temperature and pressure, but when it exceeds the limits of a certain temperature and high pressure called the supercritical point, it becomes a critical state in which it is impossible to distinguish between gas and liquid because the evaporation process does not occur. Carbon dioxide in this state is called supercritical carbon dioxide. Supercritical carbon dioxide has a molecular density close to that of a liquid, but has a low viscosity and is close to a gas.

Meanwhile, in the method for manufacturing a silica airgel blanket of the present invention, the step of washing before drying may be further performed. The washing removes impurities (sodium ions, unreacted products, by-products, etc.) generated during the reaction and residual ammonia, which may react with CO ₂ during supercritical drying to generate ammonium carbonate salt, to obtain a high-purity hydrophobic silica airgel blanket. It can be obtained by a dilution process using an organic solvent or a solvent exchange process.

silica airgel blanket

The silica airgel blanket manufacturing method of the present invention can secure physical properties equivalent to those of the silica airgel blanket manufactured using a fresh solvent even if the surface modification solution is continuously recycled by the novel surface modification solution recycling method of the present invention. do.

Specifically, the silica airgel blanket of the present invention is characterized in that the thermal conductivity is 19.5 mW/mK or less, more specifically 18.5 mW/mK or less.

In addition, the silica airgel blanket of the present invention is characterized in that the water impregnation rate is 2.5 wt% or less, more specifically 2.1 wt% or less.

The moisture impregnation rate is an index representing a degree of hydrophobicity measured by the ASTM C1511 method, and can be calculated by immersing the silica airgel blanket in a water bath and then measuring the weight of the water impregnated in the silica airgel blanket. The lower the water impregnation rate, the higher the degree of hydrophobicity, and the better the ability to maintain the insulating performance of the silica airgel blanket.

As described above, the present invention can reduce the manufacturing cost of a silica airgel blanket by recycling the surface modification solution recovered in the surface modification process of the silica airgel blanket manufacturing process, and at the same time, even if the surface modification solution is continuously recycled, a fresh solvent is used. It is possible to manufacture a silica airgel blanket capable of securing the same level of physical properties as the silica airgel blanket manufactured by the above method.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

manufacturing example

To a mixed solution prepared by mixing tetraethylorthosilicate (TEOS) and ethanol in a weight ratio of 3:1 (silica content = 4 wt%), a hydrochloric acid solution diluted in water (concentration = 0.15%) was added to the pH of the mixed solution. After adding so that is 1, mixing was performed to prepare an alkoxide silica sol. A silica wet gel composite was prepared by depositing a glass fiber on the prepared silica sol and gelling it by adding an ammonia catalyst in an amount of 0.5% by volume. The prepared silica wet gel composite was aged in an ethanol solution at 70° C. for 2 hours. Thereafter, a surface modifier solution prepared by mixing hexamethyldisilazane and ethanol at a volume ratio of 1:19 was added at 90% by volume to the wet gel, and the surface was modified at 70 ° C. for 10 hours to obtain a hydrophobic silica wet gel composite. manufactured. The hydrophobic silica wet gel composite was put into a 7.2 L supercritical extractor and CO ₂ was injected. Thereafter, the temperature in the extractor was raised to 60° C. over 1 hour, and supercritical drying was performed at 50° C. and 100 bar. Thereafter, CO ₂ was vented for 2 hours, and further drying was performed in an oven at 150° C. under atmospheric pressure to prepare a hydrophobic silica airgel blanket.

Example One

A hydrophobic silica airgel blanket was prepared in the same manner as in Preparation Example by recycling 95 wt% of the surface modification solution recovered in the surface modification process of Preparation Example based on the total weight of the surface modification solution used in the next batch of surface modification process.

On the other hand, the surface modifier was supplemented by 60 wt% compared to the surface modifier added in Preparation Example through GC analysis (GC / FID (EQC-0270), AT-1000 column) for the surface modification solution recovered before recycling. Hydrophobic silica airgel blankets were prepared 5 times by repeating surface modification solution recovery, surface modifier replenishment through GC analysis, and recycling 5 times.

Example 2

A hydrophobic silica airgel blanket was prepared 5 times in the same manner as in Example 1, except that the amount of the surface modifier supplemented in Example 1 was 70 wt%.

comparative example One

A hydrophobic silica airgel blanket was prepared 5 times in the same manner as in Example 1, except that the amount of the surface modifier supplemented in Example 1 was 30 wt%.

comparative example 2

A hydrophobic silica airgel blanket was prepared 5 times in the same manner as in Example 1, except that the amount of the surface modifier supplemented in Example 1 was 40 wt%.

comparative example 3

A hydrophobic silica airgel blanket was prepared 5 times in the same manner as in Example 1, except that the amount of the surface modifier supplemented in Example 1 was 80 wt%.

comparative example 4

A hydrophobic silica airgel blanket was prepared 5 times in the same manner as in Example 1, except that the amount of the surface modifier supplemented in Example 1 was 100 wt%.

Experimental example

Each physical property of the Preparation Example, Examples 1 to 2 and Comparative Examples 1 to 4 was measured, and the results are shown in Table 1 (Example 1), Table 2 (Example 2), Table 3 (Comparative Example 1), Table 4 (Comparative Example 2), Table 5 (Comparative Example 3) and Table 6 (Comparative Example 4) and FIG. 1 (Example 1 and Comparative Example 4).

1) Room temperature thermal conductivity (mW/mK, 25℃)

The room temperature thermal conductivity of the silica airgel blankets prepared in Preparation Examples, Examples and Comparative Examples was measured using HFM 436 equipment from NETZSCH.

2) Water impregnation rate (hydrophobicity) measurement (wt%)

The moisture impregnation rate of the silica airgel blankets prepared in Preparation Examples, Examples and Comparative Examples was measured through the ASTM C1511 method.

3) Analysis of surface modifier content of surface modification solution

The surface modifier component included in the surface modification solution in Preparation Example, Example 1 and Comparative Example 4 was analyzed through GC analysis (GC/FID (EQC-0270), AT-1000 column) and shown in the graph of FIG. 1.

Example 1 Compared to the initial input of HMDS
Amount added
(weight ratio) room temperature thermal conductivity
(mW/mK, 25℃)
moisture impregnation rate
(wt%) Recycle 0 (manufacturing example) 1.0 18.3 1.9 Recycle 1 0.6 17.8 1.8 Recycle 2 18.2 2.1 Recycle 3 18.4 1.9 Recycle 4 18.0 1.9 Recycle 5 18.2 2.0

Example 2 Compared to the initial input of HMDS
Amount added
(weight ratio) room temperature thermal conductivity
(mW/mK, 25℃)
moisture impregnation rate
(wt%) Recycle 0 (manufacturing example) 1.0 18.3 1.9 Recycle 1 0.7 17.7 1.9 Recycle 2 18.1 2.0 Recycle 3 18.2 2.1 Recycle 4 17.9 1.9 Recycle 5 18.2 2.0

Comparative Example 1 Compared to the initial input of HMDS
Amount added
(weight ratio) room temperature thermal conductivity
(mW/mK, 25℃)
moisture impregnation rate
(wt%) Recycle 0 (manufacturing example) 1.0 18.3 1.9 Recycle 1 0.3 18.9 3.0 Recycle 2 19.1 3.9 Recycle 3 19.6 4.5 Recycle 4 20.0 5.1 Recycle 5 20.2 5.6

Comparative Example 2 Compared to the initial input of HMDS
Amount added
(weight ratio) room temperature thermal conductivity
(mW/mK, 25℃)
moisture impregnation rate
(wt%) Recycle 0 (manufacturing example) 1.0 18.3 1.9 Recycle 1 0.4 18.5 2.8 Recycle 2 18.8 3.2 Recycle 3 19.1 3.5 Recycle 4 19.5 3.9 Recycle 5 19.7 4.1

Comparative Example 3 Compared to the initial input of HMDS
Amount added
(weight ratio) room temperature thermal conductivity
(mW/mK, 25℃)
moisture impregnation rate
(wt%) Recycle 0 (manufacturing example) 1.0 18.3 1.9 Recycle 1 0.8 18.5 1.7 Recycle 2 18.6 2.0 Recycle 3 19.4 1.8 Recycle 4 19.6 1.9 Recycle 5 20.0 2.2

Comparative Example 4 Compared to the initial input of HMDS
Amount added
(weight ratio) room temperature thermal conductivity
(mW/mK, 25℃)
moisture impregnation rate
(wt%) Recycle 0 (manufacturing example) 1.0 18.3 1.9 Recycle 1 1.0 18.6 1.7 Recycle 2 18.8 1.9 Recycle 3 19.7 2.2 Recycle 4 20.3 2.0 Recycle 5 20.7 1.8

As shown in Tables 1 to 6, the method for manufacturing a silica airgel blanket including the surface modification solution recycling method of the present invention of Examples 1 and 2 shows thermal conductivity and moisture impregnation even after recycling the surface modification solution 5 times. It was confirmed that the rate was maintained at an excellent level.

However, in Comparative Example 1 and Comparative Example 2, the content of the supplemented surface modifier was too small, and the more the surface modification solution was recycled, the more the surface modification reaction was not performed, so that the thermal conductivity and the water impregnation rate increased, and the insulation performance deteriorated. I was able to confirm.

In Comparative Examples 3 and 4, it was confirmed that as the surface modifying solution was recycled due to an excessive amount of the surface modifier, the thermal conductivity increased due to the over-concentration of the surface modifier and its derived components, resulting in a decrease in thermal insulation performance. On the other hand, in this case, the more recycled, the more the water impregnation rate did not decrease. Through this, it is possible to secure an excellent level of water impregnation rate if only a certain level or more of the surface modifier is present, and even if the surface modifier is higher than that, the water impregnation rate is not lowered. It was found that improvement did not help.

On the other hand, Figure 1 is a graph showing the change in the content of the surface modifier according to repeated recycling of the surface modification solution of Preparation Example, Example 1 and Comparative Example 4.

Example 1 includes the method for recycling the surface modification solution of the present invention. Even when the surface modification solution is repeatedly recycled 5 times, the content of the surface modifier contained in the surface modification solution before and after the surface modification is maintained at the same level. It was confirmed that the surface modifier included in the surface modification solution after modification was maintained at 3 wt% or less based on the weight of the surface modification solution.

On the other hand, in Comparative Example 4, the same amount of HMDS input was added to the surface modification solution recovered after the surface modification process. In particular, after the second recycling, it was confirmed that the surface modifier contained in the surface modification solution after surface modification exceeded 3 wt% based on the weight of the surface modification solution.

The above description of the present invention is for illustrative purposes, and those skilled in the art can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

Claims (14)

In the method for manufacturing a silica airgel blanket,
1) recovering the surface modification solution after the surface modification process;
2) replenishing a surface modifier to the recovered surface modification solution; and
3) recycling the surface modification solution supplemented with the surface modifier;
The surface modifier included in the surface modification solution used in the surface modification process is 3 to 6 wt% based on the weight of the surface modification solution,
The surface modifier contained in the surface modification solution recovered after the surface modification process is 3 wt% or less based on the weight of the surface modification solution,
The content of the supplemented surface modifier is 60 to 75 wt% relative to the content of the surface modifier contained in the surface modification solution used in the surface modification process of step 1).
According to claim 1,
The method of manufacturing a silica airgel blanket, characterized in that the surface modification solution contains a surface modifier and an organic solvent.
According to claim 2,
The organic solvent is a silica airgel blanket manufacturing method, characterized in that at least one selected from the group consisting of methanol, ethanol, hexane and pentane.
According to claim 1,
The surface modifier is trimethylchlorosilane (TMCS), hexamethyldisilazane (HMDS), trimethylsilanol (TMS), trimethylethoxysilanol (TMES), hexamethyldisiloxane , HMDSO), methyltrimethoxysilane (methyltrimethoxysilane), trimethylethoxysilane (trimethylethoxysilane), ethyltriethoxysilane (ethyltriethoxysilane), phenyltriethoxysilane (phenyltriethoxysilane) and polydimethylsiloxane selected from the group consisting of A method for manufacturing a silica airgel blanket, characterized in that at least one kind.
According to claim 1,
The surface modification solution used in the surface modification process is a silica airgel blanket manufacturing method, characterized in that 80 to 110 vol% of the volume of the silica gel used in the manufacture of the silica airgel blanket.
delete According to claim 1,
The method of manufacturing a silica airgel blanket, characterized in that the surface modification solution supplemented with the surface modifier is recycled in the surface modification process of step 1) of the next batch.
According to claim 1,
A method for manufacturing a silica airgel blanket, characterized in that the recycled surface modification solution is used in an amount of 70 to 100 wt% relative to the weight of the surface modification solution required in the surface modification process.
According to claim 1,
The method of manufacturing a silica airgel blanket, characterized in that the amount of the supplemented surface modifier is quantified through GC (gas chromatography) analysis of the surface modification solution recovered after the surface modification process.
According to claim 1,
The addition of the surface modifier to the surface modification solution recovered after the surface modification process in step 2) is to ensure that the content of the surface modifier contained in the surface modification solution used in the surface modification process is always maintained the same. Blanket manufacturing method.
delete According to claim 1,
The method for manufacturing a silica airgel blanket, characterized in that the surface modification solution can be repeatedly recycled several times through the steps 1) to 3).
The method of any one of claims 1 to 5, 7 to 10 and 12,
The silica airgel blanket manufacturing method, characterized in that the thermal conductivity of 19.5 mW / mK or less.
The method of any one of claims 1 to 5, 7 to 10 and 12,
The silica airgel blanket manufacturing method, characterized in that the moisture impregnation rate is 2.5 wt% or less.

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