WO2017155311A1 - Method for manufacturing aerogel blanket, and aerogel blanket manufactured thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing an aerogel blanket having excellent hydrophobicity at a high temperature, and an aerogel blanket manufactured thereby. The present invention mixes a silica sol and a hydrophobic aerogel powder so as to use the same as an aerogel precursor, thereby enabling a hydrophobic aerogel to be present in the aerogel surface structure, contained in an aerogel blanket, and even in the internal structure thereof, and thus the present invention can have high hydrophobicity and can have excellent hydrophobicity retentiveness even during high temperature application.

Description

Method for manufacturing airgel blanket and airgel blanket prepared therefrom

Citation with Related Applications

This application is filed with Korean Patent Application No. 10-2016-0027784 filed March 08, 2016, Korean Patent Application No. 10-2016-0123394 filed September 26, 2016, and Korean Patent Application No. 10-2017 dated March 08, 2017 Claims the benefit of priority based on -0029619, 10-2017-0029620 and 10-2017-0029621, all the contents disclosed in the documents of the relevant Korean patent application are incorporated as part of this specification.

Technical Field

The present invention relates to a method for producing an airgel blanket having excellent high temperature hydrophobicity, and to an airgel blanket prepared using the same.

Aerogel is an ultra-porous, high specific surface area (≥≥500 m ² / g) material with a porosity of about 90% to 99.9% and a pore size in the range of 1 nm to 100 nm. As it is a material with such characteristics, it is also actively researching the development of aerogel materials, as well as researching transparent insulation materials and environment-friendly high-temperature insulation materials, ultra-low dielectric films for highly integrated devices, catalysts and catalyst carriers, electrodes for supercapacitors, and electrode materials for seawater desalination. Going on

The biggest advantage of the airgel is super-insulation, which exhibits a thermal conductivity of 0.300 W / mK or lower, which is lower than that of conventional thermal insulation materials such as styrofoam. In addition, it is possible to solve the fire vulnerability and the generation of harmful gases during the fire, which is a fatal weakness of the organic insulation.

However, aerogels are used only for extremely limited applications despite the excellent material properties due to the complicated manufacturing process and high manufacturing cost. In addition, due to high porosity, the mechanical strength is very weak, and there is a disadvantage that it is easy to be broken even by a small impact. Therefore, in recent years, airgel blanket complexing technology has been researched that compensates for the disadvantages of the airgel itself and enables processing in various forms.

Aerogel blanket (aerogel blanket) is a composite of aerogel material to represent a made in the form of a mattress or sheet, it has the flexibility to bend, fold or cut features. Therefore, it can be applied to places such as pipe insulation or clothing, and also various industrial applications. Flexibility is possible because the airgel blanket is a composite consisting of fibers and aerogels. Fibers enhance the flexibility and mechanical strength of aerogel blankets, and aerogels impart insulation properties due to porosity. The core composite technology of the airgel blanket is to combine the characteristics of the fiber and the characteristics of the airgel to take advantage of each other's advantages and to compensate for the disadvantages.

The airgel blanket is a new material having excellent heat resistance and heat insulation properties than polystyrene foam or polyurethane foam, which is an existing polymer insulation material, and is attracting attention as an advanced material that can solve energy saving and environmental problems in the future.

Conventional airgel blankets were prepared by mixing and gelling fibers in silica sol obtained from water glass or alkoxide precursors, followed by aging, surface modification and drying. However, in the case of the airgel blanket prepared by the conventional method, since hydrophobic modification mainly occurs only on the surface, there is a problem in that the hydrophobicity is easily lost during high temperature firing at 400 ° C. or higher. As the temperature increases during firing, hydrophobic groups, such as methyl or ethyl groups, in the airgel pores are burned and lose hydrophobicity. As such, when the hydrophobicity is lost, the thermal insulation performance is not only degraded by water infiltration, but the pore structure is collapsed by shrinkage during the evaporation of the infiltrated water, thereby permanently losing the thermal insulation performance.

For example, U.S. Patent No. 5,789,075 discloses a method for preparing an airgel blanket using water glass or an alkoxide precursor alone as a precursor of a silica sol, but spring-back when drying is used when water glass alone is used. ) It has a disadvantage of high thermal conductivity because it does not show the porosity of more than 90% due to the reduced thickness because the effect does not occur.In the case of using an alkoxide-based precursor alone, it has excellent properties such as thermal conductivity at first, but it loses hydrophobicity easily at high temperature and functions as an insulating material. In addition to the problem of not having a problem, because the alkoxide precursor is expensive, there is a problem that is uneconomical.

Therefore, in order to use the airgel blanket in a heat insulating material, it is important to keep the hydrophobic group in the pores stably so as to maintain hydrophobicity at high temperatures and to prevent deterioration of high temperature durability, and thus to produce an airgel blanket applicable to high temperatures. There is a need for technology.

(Patent Document 1) US 5,789,075 B

The present invention has been made to solve the problems of the prior art as described above, and an object of the present invention is to provide a method for producing a high temperature superhydrophobic airgel blanket that can maintain excellent hydrophobicity even at high temperatures.

Another object of the present invention is to provide a high temperature superhydrophobic airgel blanket prepared from the above method.

The present invention to solve the above problems, 1) preparing an airgel precursor by mixing the airgel powder in a silica sol; 2) preparing a wet gel-based composite by adding a basic catalyst to the airgel precursor, depositing the gel on a blanket substrate, and then gelling the gel; 3) preparing a hydrophobic wet gel-based composite by performing surface modification on the wet gel-based composite; And 4) it provides a method for producing an airgel blanket comprising the step of drying the hydrophobic wet gel-based composite.

In addition, the present invention comprises a substrate for aerogels and blankets, the airgel is heat treated for 1 to 5 hours at a temperature of 400 ℃ or more than less than 500 ℃, the carbon content retention calculated by the following formula 2 is 1) To provide an airgel blanket that satisfies at least one of the 5).

[Equation 2]

Carbon content retention rate (%) = (carbon content of airgel after heat treatment (% by weight)) / (original carbon content of airgel (% by weight))

1) More than 75% when heat treated for 1 hour

2) 65% or more when heat treated for 2 hours

3) 60% or more when heat treated for 3 hours

4) 59% or more when heat treated for 4 hours

5) 58% or more when heat treated for 5 hours

In addition, the present invention comprises a substrate for aerogels and blankets, wherein the airgel heat treatment for 1 to 5 hours at a temperature of 500 ℃ to 600 ℃ or less, the carbon content retention calculated by Equation 2 is 13% or more To provide an airgel blanket.

[Equation 2]

Carbon content retention rate (%) = (carbon content of airgel after heat treatment (% by weight)) / (original carbon content of airgel (% by weight))

Furthermore, the present invention provides a heat insulating material comprising the airgel blanket.

 By the production method of the present invention, it is possible to produce a high temperature superhydrophobic airgel blanket capable of maintaining excellent hydrophobicity even at high temperatures.

In addition, the airgel blanket prepared according to the manufacturing method has a hydrophobicity is made not only on the surface of the airgel but also the internal structure of the airgel can exhibit high hydrophobicity, excellent hydrophobic holding power even at high temperature application, the thermal conductivity increase rate is not high, heat insulating material As a useful effect.

The following drawings, which are attached to this specification, illustrate preferred embodiments of the present invention, and together with the contents of the present invention serve to further understand the technical spirit of the present invention, the present invention is limited to the matters described in such drawings. It should not be construed as limited.

Figure 1 schematically shows a flow chart of a method of manufacturing an airgel blanket according to an embodiment of the present invention.

Figure 2 is a graph measuring the carbon content contained in the airgel after the heat treatment of the airgel of Examples and Comparative Examples at 400 ℃ for 1 hour to 5 hours.

Figure 3 is a graph measuring the carbon content contained in the airgel after the heat treatment of the airgel of the Examples and Comparative Examples at 500 ℃ for 1 hour to 5 hours.

Figure 4 is a graph measuring the carbon content contained in the airgel after the heat treatment of the airgel of Examples and Comparative Examples at 600 ℃ for 1 hour to 5 hours.

Figure 5 is a graph measuring the thermal conductivity of the airgel blanket after heat treatment of the airgel blanket of Examples and Comparative Examples at 400 ℃ for 1 hour to 5 hours.

Figure 6 is a graph measuring the thermal conductivity of the airgel blanket after heat treatment of the airgel blanket of Examples and Comparative Examples at 500 ℃ for 1 hour to 5 hours.

Figure 7 is a graph measuring the thermal conductivity of the airgel blanket after heat treatment of the airgel blanket of Examples and Comparative Examples at 600 ℃ for 1 hour to 5 hours.

8 is a photograph of comparative analysis of the hydrophobic holding force of the airgel blanket after the heat treatment of the airgel blanket of Examples and Comparative Examples for 1 hour at 400 ℃.

9 is a photograph of comparative analysis of the hydrophobic holding force of the airgel blanket after heat treatment of the airgel blanket of Examples and Comparative Examples at 500 ℃ for 1 hour.

10 is a photograph of comparative analysis of the hydrophobic retention of the airgel blanket after heat treatment of the airgel blanket of Example and Comparative Example at 600 ℃ for 1 hour.

11 is a graph showing the results of thermogravimetric analysis (TGA) for the airgel of the Examples and Comparative Examples.

Hereinafter, the present invention will be described in more detail to aid in understanding the present invention.

The terms or words used in this specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors may appropriately define the concept of terms in order to describe their own invention as the best invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

In general, aerogel blankets are used to prepare silica sol alone or in combination with water glass or alkoxysilane (hereinafter referred to as Method 1), or to prepare a sol by mixing a binder with a hydrophobized airgel powder (hereinafter referred to as Method 2). And then, it is prepared by mixing the base material for the blanket such as fibers, gelation, aging, surface modification and drying. However, when the airgel blanket is manufactured by the method 1, the surface modification is mostly made only on the surface, so that it is difficult to be hydrophobically modified to the inside, and as a result, a problem of easily losing hydrophobicity at a high temperature may occur. In addition, when the airgel blanket is manufactured by the method 2, the hydrogel is hydrophobic to the inside, so hydrophobicity can be maintained even at a high temperature. However, the thermal conductivity is increased due to the use of a binder. ) Has a lot of disadvantages.

Therefore, it is necessary to develop a high temperature super hydrophobic airgel blanket capable of maintaining high thermal insulation properties while maintaining excellent thermal conductivity and excellent hydrophobic retention at high temperatures.

In the present invention, on the other hand, by using a silica gel sol mixed with an aerogel powder, especially a hydrophobic silica airgel powder or an organic functionalized airgel powder containing one or more organic functional groups on the surface of the aerogel powder, hydrophobicity at high temperature while excellent in thermal conductivity characteristics Provided is a method for producing an airgel blanket having excellent retention.

Hereinafter, a method of manufacturing an airgel blanket according to an embodiment of the present invention will be described in detail with reference to FIG. 1.

Figure 1 schematically shows a flow chart of the manufacturing method according to an embodiment of the present invention, it is only an example for explaining the present invention is not limited thereto.

Method for producing the airgel blanket according to an embodiment of the present invention,

1) preparing an airgel precursor by mixing the airgel powder in a silica sol;

2) preparing a wet gel-based composite by adding a basic catalyst to the airgel precursor, depositing the gel on a blanket substrate, and then gelling the gel;

3) preparing a hydrophobic wet gel-based composite by performing surface modification on the wet gel-based composite; And

4) drying the hydrophobic wet gel-based composite.

Step 1) is a step for preparing an airgel precursor, the airgel precursor may be prepared by mixing the airgel powder in a silica sol.

More specifically, the airgel precursor may be prepared by mixing and reacting an acidic aqueous solution with a mixed solution containing an alkoxysilane and an alcohol to prepare a silica sol, and adding and mixing the airgel powder thereto.

The silica sol used in the preparation of the airgel precursor acts as a chemical binder between the airgel powders in preparation of the airgel blanket, thereby increasing the binding force of the airgel powders and enabling uniform gelation. As a result, high-temperature hydrophobicity and durability can be improved to exhibit high thermal insulation performance. Specifically, the silica sol may be prepared by mixing an acidic aqueous solution with a mixed solution containing an alkoxysilane and an alcohol.

The alkoxysilanes usable in the preparation of the silica sol may specifically be tetraethylorthosilicate (TEOS), tetramethylorthosilicate (TMOS) or trialkoxysilane (trialkoxysilane) and the like, a mixture comprising one or more of them. This can be used. More specifically, the alkoxysilane of the present invention may be tetraethylorthosilicate.

In addition, the alcohol that can be used to prepare the silica sol is not particularly limited, but may be, for example, an alcohol having 1 to 6 carbon atoms such as ethanol, and the content of silica contained in the mixed solution is 2 to 6 wt%, more specifically May be added in an amount such that from 3% to 5% by weight.

In addition, the acidic aqueous solution used for the production of the silica sol is characterized in that it contains an acidic catalyst and water.

The water serves to hydrate the alkoxysilane and at the same time serves as a solvent to dissolve the acidic catalyst. Accordingly, the water may be added separately from the acidic catalyst, or may be added as an acidic aqueous solution in which the acidic catalyst is dissolved.

The acidic catalyst is a catalyst for promoting the hydration reaction of the alkoxysilane, and may be used in an amount such that the pH in the mixed solution is 0.5 to 1. Specific examples of the acidic catalyst may include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, and the like, and a mixture including one or more of them may be used.

Meanwhile, the airgel powder mixed with the silica sol for preparing the airgel precursor may specifically be a silica airgel powder, and more specifically, the surface may be organic by surface modification using an organic functional group, especially a compound having a hydrophobic functional group. Functionalized, specifically, silylated or hydrophobized. The hydrophobized airgel powder is mixed with the silica sol to be used as a precursor for preparing the airgel blanket, thereby improving hydrophobicity of the airgel blanket, particularly in the interior thereof.

Specifically, according to an embodiment of the present invention, the airgel powder mixed with the silica sol for preparing the airgel precursor is at least one, more specifically one, two or three identical on the inner surface of the airgel Or an organic functionalized airgel powder comprising different organic functional groups.

On the other hand, the organic functional group means a structure having a polar atom bond formed by the presence of a hetero atom in the organic group, it can react with a hydroxyl group or an ether group on the surface of the airgel. Specific examples of the functional group include a halogen group, a pseudo halogen group, a hydroxyl group, a thio group, an amino group, an amide group, an ether group, an ester group, an acid group, a formyl group, a ketone group or a silyl group.

In addition, the hydrocarbon group containing the aforementioned functional group may be an alkyl group having 1 to 22 carbon atoms, more specifically, 1 to 12 carbon atoms, branched or unbranched. At least one methylene group (-CH _2- ) in the alkyl group is -O-, -S-, -CO-, -COO-, -O-CO-O-, -CONR'-, -SO-,- 4-10 carbons which may contain SO _2- , -NH-CO-NH-, a cycloalkylene group having 3 to 6 carbon atoms, -CH = CH-, or a hetero atom (for example, N, S or O, etc.) It may be substituted by an arylene group, or one or more hydrogen atoms in the alkyl group is F, Cl, Br, I, CN, SCN, -NCO, -OCN, -NO ₂ , -SO ₃ R ", -PR" It can be substituted by at least one functional group of ' ₂ , and -CHO (wherein R', R "and R"'are each independently a hydrogen atom, an alkyl group of 1 to 12 carbon atoms, of 6 to 12 carbon atoms Or an arylalkyl group having 7 to 12 carbon atoms such as an aryl group or a benzyl group.

Specifically, the organic functionalized airgel powder may be any one airgel powder selected from the group consisting of a) to d):

a) an airgel containing a functional group of the following formula (I)

-X-Y (I)

Wherein X is a linear or branched alkylene group having 1 to 22 carbon atoms, Y is a halogen group, pseudohalogen group, -SR ¹ , -PR ² R ³ , oxirane group or CH ₂ = C (CH ₃ ) -COO-, and wherein, R ¹ is an alkyl group of straight or branched chain of hydrogen atoms, containing 1 to 22 carbon atoms, or an aryl group having 4 to 10, R ² and R ³ are, each independently containing 1 to 22 carbon atoms It may be a linear or branched alkyl group or an aryl group having 4 to 10 carbon atoms.

b) an airgel modified with an amino alcohol of formula (II), which is capable of binding to the airgel via an ether bridge

R ⁴ -NH-R ⁵ -OH (II)

Wherein R ⁴ is a hydrogen atom; an alkyl group having 1 to 4 carbon atoms; and a hydroxyalkyl group such as — (CH ₂ ) ₃ —OH, and R ⁵ is an alkylene group having 1 to 4 carbon atoms)

_{c) - (CH 2) 3} -NH 2 or _{- (CH 2) 3 -NH- (} CH 2) amino-modified airgel having an alkyl group such as ₃ -NH ₂

d) aerogels modified with a functional group of formula (III)

R ⁶ R ⁷ N- (CHR ⁸ ) _a -N (R ⁹ )-(CHR ¹⁰ ) _b -Si (OR ¹¹ ) ₃ (III)

Wherein R ⁶ is an alkyl group having 1 to 8 carbon atoms, and R ⁷ , R ⁸ and R ¹¹ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 10 carbon atoms such as a phenyl group is selected and, R ⁹ and R ¹⁰ are alkyl groups each independently represent a hydrogen atom or a C 1 -C 4, a is an integer from 1 to 4, b is an integer from 1 to 8, these functionalities are Pd, Pt, Ni, Complexes with a metal element selected from the group consisting of Co and Cu)

The organic functionalized airgel powder may be prepared by reacting a silica wet gel obtained by polycondensation of water glass with at least a bifunctional organic compound, followed by drying. In addition, the bifunctional organic compound is characterized in that it comprises at least one functional group that acts as a bonding group with the airgel, more specifically the bifunctional organic compound is methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane It may include one or more compounds selected from the group consisting of, chloropropyltrichlorosilane, trimethyl methoxysilane and hexamethyldisilazane.

Accordingly, the method of manufacturing an airgel blanket according to an embodiment of the present invention may further include preparing the organic functionalized airgel powder before preparing an airgel precursor.

Specifically, the gelation may be performed by adding acid ion exchange resin or mineral acid to an aqueous solution of water glass to prepare silicic acid, and then polycondensation reaction in strong acid or strong base.

In addition, after the gelation step of aging at pH 4 to pH 11 at a temperature of 0 ℃ to 100 ℃; And inert, low boiling organic solvents for the resulting gel (for example, aliphatic alcohols such as methanol, ethanol, n-propanol, isopropanol; esters such as ethyl acetate; ethers such as dioxane; ketones such as acetone or tetrahydrofuran) at least one or more of the solvent substitution process using an aliphatic or aromatic hydrocarbon such as n-hexane or toluene) may optionally be further performed.

In addition, the at least bifunctional organic compound which can be used at the time of surface functionalization (modification) of the gel is a compound containing at least one of the aforementioned organic functional groups, and specifically, an amino alcohol of R ⁴ -NH-R ⁵ -OH ( Wherein R ⁴ and R ⁵ are as defined above, R ¹² _{4- n} SiCl _n or R ¹³ _{4- n} Si (OR ¹⁴ ) _n , where n is an integer from 1 to 3, and R ¹² and R ¹³ May be each independently selected from a hydrogen atom, a linear or branched alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 18 carbon atoms, and an aryl group having 6 to 18 carbon atoms, and R ¹⁴ is 1 to 18 carbon atoms. More specifically, the organic compound may be methyl trichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, chloropropyltrichlorosilane, trimethyl methoxysilane, or hexamethyldisilazane. Lift Were, there is any one or a mixture of two or more of them may be used.

On the other hand, the drying step for the surface organic functionalized gel is -30 ° C to 200 ° C, more specifically, a temperature of 0 ° C to 200 ° C; And 0.001 bar to 20 bar, more specifically 0.1 bar to 2 bar, and may be carried out until the residual solvent content of the gel is less than 0.1% by weight.

In addition, according to another embodiment of the present invention, the airgel powder mixed with the silica sol for preparing the airgel precursor may be an organic functionalized airgel powder prepared by silylating the surface of the hydrogel. have.

Specifically, the silylated organic functionalized airgel powder may be prepared by surface modification of hydrogel, specifically, silica hydrogel, specifically surface silylation, and then drying. The silica hydrogel is controlled to pH 3 or less by adding an acidic ion exchange resin, an inorganic acid or hydrochloric acid solution to an aqueous glass solution, followed by polycondensation by adding a base, and washing the resulting gel with water, or a water glass solution. Preparing a gel of SiO ₂ through an intermediate step of a silica sol by adding an organic acid or an inorganic acid to it; And it may be prepared by a drying step, and more specifically may be prepared by hydrolysis and polycondensation of silicon tetrachloride. The surface modification, in particular surface silylation, can also be carried out by surface modification with respect to hydrogels using a silylating agent on liquid, gas or water vapor. Thereafter, an acid such as a base or a base may be optionally further added before or after the silylating agent is added. Moreover, as said silylating agent, Disiloxane of following General formula (IV); Disilazane of formula (V); And at least one silylating agent of the silane of formula (VI) or (VII) with a gel.

(R _a1 ) ₃ Si-O-Si (R _a2 ) ₃ (IV)

(R _b1 ) ₃ Si-N (H) -Si (R _b2 ) ₃ (V)

(R _c ) _{4- m} SiCl _m (VI)

(R _d ) _{4- n} Si (OR _e ) _n (VII)

Wherein R _a1 , R _a2 , R _b1 , R _b2 , R _c , R _d and R _e are each independently a hydrogen atom or non-reactive, organic, linear, branched, cyclic, saturated or unsaturated, aromatic ( aromatic) or heteroaromatic radical, and more specifically, may be a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 18 carbon atoms, or an aryl group having 6 to 14 carbon atoms, and more specifically An alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group; Cyclohexyl group; Or a phenyl group, m and n are each independently an integer of 1 to 4.

More specifically, the silylating agent is alkyltrichlorosilane such as methyltrichlorosilane; Dialkyldichlorosilanes such as dimethyldichlorosilane; Trialkylchlorosilanes such as trimethylchlorosilane; Symmetric disiloxanes or hexaalkyldisiloxanes such as hexamethyldisiloxane and the like; Trialkyl methoxysilanes such as trimethyl methoxysilane; Or silazanes such as hexamethyldisilazane and the like, and any one or a mixture of two or more thereof may be used.

The airgel particles may exhibit hydrophobicity in whole or in part depending on the degree of silylation, wherein the hydrophobicity may be permanent.

In addition, a part of the water present in the pores of the hydrogel during the surface modification reaction may react with the silylating agent which is the surface modification agent. Accordingly, the inner surface of the aerogel surface-silylated using the silylating agent described above is Si-R. Si-OR only containing groups or Si-OH groups Group is not included (wherein R is an alkyl group). Specifically, in the case of the hydrogel containing Si-OH groups on the inner surface, when the surface silylation using trialkylchlorosilane or hexaalkyldisiloxane as the silylating agent, the Si-OH groups react completely or partially on the inner surface. Si-O-Si (R)₃ Will provide a flag. While the presence of organic solvents usually adds organic solvents to the reactive OH groups of the gels during silylation, the hydrogels are used throughout the entire process, such as alcohols (eg, methanol, ethanol, isopropanol, etc.), ketones (eg, acetone, etc.). ) Or Si-OR on the inner surface of the gel as it is not in contact with a reactive solvent such as ether (e.g. dimethoxyethane, etc.) or tetrahydrofuran. No groups can be formed.

Accordingly, the surface silylated airgel powder may have the following i) or ii) characteristics:

i) does not contain Si-OR groups (R is an alkyl group having 1 to 18 carbon atoms)

ii) the degree of coverage of the internal surface or coverage by organic surface groups applied by surface silylation is surface modified to at least 90% of theoretically possible values. Specifically, the application degree of the trimethylsilyl group is 2.5 or more per nm ² .

In the present invention, 'application' refers to the number of organic surface functional groups per square nanometer of the inner surface area of the airgel, and the theoretically applicable applicability value may be calculated according to Equation 1 below.

[Equation 1]

Application = [C] / [BET] * K; Unit: [nm ^-2 ]

Wherein ^{K = 6.022 * 10 23/100} * 12 * 3 * 10 18 = 167.28; Unit: [g ^-1 ]

[C]: C content (% by weight)

[BET]: BET surface area; Unit: [m ² / g]

The use application value may have an error of less than 10% depending on the measuring method, and the internal surface area may be measured by nitrogen adsorption according to the BET method (multipoint BET method of DIN66131, ASAP 2010, manufactured by Micromeritics, Inc.). ).

The application has been described using, but not limited to, trimethylsilyl-modified aerogels.

Meanwhile, according to an embodiment of the present invention, the airgel powder mixed with the silica sol for preparing the airgel precursor may be a hydrophobic silica airgel powder having a carbon content of 10 parts by weight to 12 parts by weight based on the total weight of the airgel powder. If the carbon content in the airgel powder is out of the above range, the prepared hydrogel blanket may have low hydrophobicity, and consequently, there is a concern that the hydrophobic holding force may be lowered at high temperature.

The airgel powder is not particularly limited in its manufacturing method except that the hydrophobic condition is satisfied. Specifically, in the case of hydrophobic silica airgel powder, it can be prepared through the sequencing of the surface modification and drying process using a surface modifier having a hydrophobic functional group, such as gelling, hexamethyldisilazane (HMDS) for the silica sol, the silica When the solvent used in the preparation of the sol is water, a solvent replacement process using an alcohol such as methanol may be optionally further performed after the gelation.

The airgel powder may be used in an amount of 25 parts by weight to 50 parts by weight based on 100 parts by weight of silica contained in the silica sol. If the amount of the airgel powder used is less than 25 parts by weight, the degree of improvement in internal hydrophobicity may be insignificant, and a problem of not maintaining hydrophobicity at high temperature may occur. In addition, when the amount of the airgel powder exceeds 50 parts by weight, the binding strength of the airgel powder is reduced due to the decrease in the relative content of the silica sol, as a result of the blowing of the airgel powder during the blanket manufacturing process, and finally the thermal insulation performance is lowered There is a concern.

Next, step 2) in the manufacturing method of the airgel blanket according to an embodiment of the present invention is to prepare a wet gel-based composite in which the base material for the airgel and the blanket of the wet gel form, step 1 It can be carried out by adding a basic catalyst to the aerogel precursor prepared in the) and depositing on the substrate for the blanket and then gelling.

As the substrate for the blanket, a substrate of various materials may be used according to the use of the blanket. Specifically, the blanket substrate may be a film, a sheet, a net, a fiber, a porous body, a foam, a nonwoven fabric, or a laminate of two or more thereof. In addition, depending on the application, the surface roughness may be formed or patterned.

In addition, when the base for the blanket is a fiber, specifically may be glass fiber, carbon fiber or polyimide fiber, etc., may be used a mixture of one or more of them as desired.

According to an embodiment of the present invention, the blanket substrate may specifically be a reinforcing structure including a lofty fibrous batting sheet, more specifically a lofty fibrous batting, wherein the fibers are three Oriented along all axes, the bet is in the form of a sheet, the lofty fibrous bet compressible to at least 50% of the thickness and recover to at least 70% of the original thickness after compression for 5 seconds, the density of the lofty fibrous bet Is 0.001 g / cm ³ to 0.26 g / cm ³ and the cross sectional area of the identifiable fibers in the cross section of the airgel blanket to be produced may be less than 10% of the total cross sectional area.

The batting refers to a layer or sheet of a fibrous material used as a blanket for thermal insulation, and the batting manufacturing fiber may be thin, specifically 15 or less, more specifically 10 or less denier. In addition, the cross section of the fiber in the cross section of the blanket to be finally produced may be less than 10%, specifically less than 8%, more specifically less than 5% of the total cross section of the cross section.

More specifically, the reinforcing structure may include a polyester batting reinforcing structure; Polyester fiber batting comprising a polyvinyl alcohol binder; Lofty silica fiber structures; Fiber laminates of polyester / silicon carbide / copper mesh / silicon carbide / polyester; A stack of unidirectional carbon fiber / copper mesh / loft polyester batting comprising a polyester batting / polymerizable binder; And a laminate of silica felt / stainless steel mesh / silica felt.

When the basic catalyst is added to the aerogel precursor prepared in step 1) and the blanket substrate is deposited, gelation occurs, whereby the wet gel-type aerogel is formed on the surface and inside of the blanket substrate, thereby providing the wet gel-based composite. Is formed.

In this case, the basic catalyst may play a role of adjusting the pH to promote gelation.

Specifically, the pH adjustment step may be performed so that the pH of the airgel precursor deposited on the blanket substrate using a basic catalyst is 4 to 9, wherein the basic catalyst may be ammonia or the like. More specifically, the basic catalyst may be used at 0.05% by volume to 10% by volume, more specifically 0.1% by volume to 1% by volume relative to the total volume of the airgel precursor.

In addition, the method for producing an airgel blanket according to an embodiment of the present invention, in order to achieve a complete chemical change to the wet gel, after the wet gel in the prepared wet gel-based composite after step 2) It may further comprise the step of aging.

In this case, the aging may be carried out by leaving the airgel wet gel at a suitable temperature for a long time, specifically, by leaving the wet gel volume in a 90 to 110 volume ratio alcohol at a temperature of 50 ℃ to 70 ℃ for 30 minutes to 3 hours. Can be performed. When the aging process is performed under the above conditions, the network structure in the wet gel can be strengthened, and thus the strength of the manufactured airgel blanket can be improved.

Next, in the method of manufacturing an airgel blanket according to an embodiment of the present invention, step 3) is a step for preparing a hydrophobic wet gel-based composite, in the wet gel-based composite prepared in step 2). It can be carried out by surface modification of the wet gel.

Specifically, the surface modification may be performed using a solution in which the surface modifier is dissolved in an organic solvent. More specifically, the solution may be prepared by adding and mixing the surface modifier to the organic solvent so as to be 2.5 vol% to 7.5 vol% with respect to the total volume of the solution. If the surface modifier and the organic solvent are included in the above ratio, surface modification can be easily performed on the surface of the wet gel and the pores therein to show hydrophobicity. Cracks can be prevented during the heat treatment process. More specifically, the surface modification may be performed by using a solution prepared by mixing the surface modifier to 5 vol% to 7.5 vol% in an organic solvent.

In addition, as the surface modifier, a silane compound, a silazane compound, or a siloxane compound may be specifically used. More specifically, trimethylchlorosilane, methyltrimethoxysilane, phenyltriethoxysilane, dimethylchlorosilane, One or more selected from the group consisting of trimethylethoxysilane, hexamethyldisilazane and polydimethylsiloxane may be used, but is not limited thereto.

As the organic solvent, specifically, an alcohol solvent such as ethanol or isopropyl alcohol; Or hydrocarbon-based solvents such as n-hexane, heptane, toluene or xylene, and the like, or a mixture of two or more of them may be used.

On the other hand, the solution containing the surface modifier may be used in a 70 to 100 volume ratio based on the volume of the wet gel to 100. If the amount of the solution is less than 70% by volume, the problem of surface modification and solvent replacement may not be achieved completely, and if it exceeds 100% by volume, it may be economically unfavorable due to excessive use.

The surface modification is more specifically in the wet gel-based composite prepared in step 2), after adding a solution containing a surface modifier, at a temperature of 50 ℃ to 80 ℃, more specifically 1 hour to 10 hours Can be carried out by maintaining at a temperature of 60 ℃ to 70 ℃ for 4 hours to 5 hours.

Through such a surface modification process, the airgel distributed on the surface and inside of the blanket substrate exhibits hydrophobicity.

In addition, the manufacturing method of the airgel blanket according to an embodiment of the present invention, when the drying process is carried out by the atmospheric pressure drying, after the surface modification may optionally further include a solvent replacement process.

The solvent replacement process may be performed by replacing the solvent in the hydrophobic airgel with the organic solvent by adding an organic solvent after the surface modification process. In this case, a hydrocarbon solvent or the like may be used as the organic solvent.

Next, in the method for producing an airgel blanket according to an embodiment of the present invention step 4) is to prepare the final airgel blanket of the present invention by drying the hydrophobic wet gel-based composite prepared in step 3) Manufacturing step.

Specifically, the drying process may be performed by a supercritical drying process or an atmospheric pressure drying process using supercritical carbon dioxide.

Carbon dioxide (CO ₂ ) is a gaseous state at room temperature and atmospheric pressure, but if it exceeds a certain temperature and high pressure limit called the supercritical point, the evaporation process does not occur, so it becomes a critical state in which gas and liquid cannot be distinguished. Carbon dioxide in the state is called supercritical carbon dioxide. Supercritical carbon dioxide has a molecular density close to a liquid, but has a low viscosity, close to a gas, high diffusion efficiency, high drying efficiency, and short drying time.

The supercritical drying process may be performed according to a conventional method except for using the silica gel-based composite prepared in Step 2. Specifically, in the supercritical drying process the supercritical drying the reactor, surface airgel of the modified hydrophobic-insert the substrate composite, and then, filling up the CO ₂ in the liquid state to the solvent replacement step of replacing the alcohol solvent within the airgel to CO ₂ Perform. Thereafter, the temperature is raised to 40 ° C. to 50 ° C. at a constant temperature increase rate, specifically 0.1 ° C./min to 1 ° C./min, and then the pressure or more at which carbon dioxide becomes a supercritical state, specifically, 100 bar to 150 The pressure of bar is maintained for a certain time, specifically 20 minutes to 1 hour, in the supercritical state of carbon dioxide. In general, carbon dioxide is supercritical at a temperature of 31 ° C. and a pressure of 73.8 bar. The carbon dioxide may be maintained at a constant temperature and a constant pressure for 2 hours to 12 hours, more specifically, 2 hours to 6 hours at a constant temperature and then the pressure is gradually removed to complete the supercritical drying process.

In addition, in the case of the atmospheric pressure drying process, it may be carried out according to a conventional method such as natural drying, hot air drying under normal pressure (1 ± 0.3 atm). Specifically, the reaction may be performed at a temperature of 50 ° C. to 150 ° C. for 12 hours to 24 hours.

Through the above manufacturing method, a high temperature superhydrophobic airgel blanket capable of maintaining excellent hydrophobicity even at high temperatures is manufactured. The airgel blanket has hydrophobicity not only on the surface but also on the internal structure, and thus may exhibit excellent hydrophobic retention even at high temperature.

Accordingly, according to another embodiment of the present invention, there is provided an airgel blanket prepared by the above manufacturing method.

The airgel contained in the airgel blanket prepared by the manufacturing method of the present invention has a higher carbon content retention rate compared with the conventional airgel even when heat treated at a temperature of 400 ° C. or higher and less than 500 ° C., and compared with a conventional airgel blanket. Thermal conductivity increase may be low.

Specifically, the airgel blanket of the present invention comprises an airgel and the base for the blanket, the airgel is a carbon content calculated by the following formula 2 when the heat treatment for 1 to 5 hours at a temperature of 400 ℃ or more less than 500 ℃ Retention rate may be to satisfy at least one of the following 1) to 5), preferably may be to satisfy all of 1) to 5).

[Equation 2]

Carbon content retention rate (%) = (carbon content of airgel after heat treatment (% by weight)) / (original carbon content of airgel (% by weight))

1) More than 75% when heat treated for 1 hour

2) 65% or more when heat treated for 2 hours

3) 60% or more when heat treated for 3 hours

4) 59% or more when heat treated for 4 hours

5) 58% or more when heat treated for 5 hours

More specifically, the airgel of the present invention when the heat treatment for 1 hour to 5 hours at a temperature of 400 ℃ or less than 500 ℃, the carbon content retention rate may be to satisfy at least one of the following 1) to 5), Preferably, all of 1) to 5) may be satisfied.

1) 75% or more and 80% or less when heat treated for 1 hour

2) 65% or more and 75% or less when heat treated for 2 hours

3) 60% or more and 70% or less when heat-treated for 3 hours

4) 59% or more and 65% or less when heat treated for 4 hours

5) 58% or more and 64% or less when heat treated for 5 hours

In addition, when the airgel blanket is heat-treated for 1 hour to 5 hours at a temperature of 400 ° C or more and less than 500 ° C, the thermal conductivity increase rate calculated by Equation 3 below satisfies at least one of the following 1) to 5): It may be, preferably to satisfy all of 1) to 5).

[Equation 3]

Thermal conductivity increase rate (%) = (Thermal conductivity of airgel blanket (mW / mK) at 25 ° C after heat treatment) / (Initial thermal conductivity of airgel blanket at 25 ° C (mW / mK))

1) 6% or less when heat treated for 1 hour

2) 10% or less when heat treated for 2 hours

3) 11% or less when heat treated for 3 hours

4) 12% or less when heat treated for 4 hours

5) 13% or less when heat treated for 5 hours

More specifically, the airgel blanket of the present invention when the heat treatment for 1 hour to 5 hours at a temperature of 400 ℃ or more less than 500 ℃, the thermal conductivity may be to satisfy at least one of the following 1) to 5). And, preferably it may be to satisfy all of 1) to 5).

1) 5% or more and 6% or less when heat treated for 1 hour

2) 7% or more and 10% or less when heat treated for 2 hours

3) 8% or more and 11% or less when heat-treated for 3 hours

4) 9% or more and 12% or less when heat treated for 4 hours

5) 10% or more and 13% or less when heat treated for 5 hours

The airgel contained in the airgel blanket prepared by the manufacturing method of the present invention has a higher carbon content retention rate compared with the conventional airgel even when heat treated at a temperature of 500 ° C. or higher and 600 ° C. or lower, and compared with a conventional airgel blanket. Thermal conductivity increase may be low.

Specifically, the airgel blanket of the present invention comprises an airgel and the substrate for the blanket, the airgel is a carbon content calculated by the following formula (2) when heat-treated for 1 to 5 hours at a temperature of 500 ° C or more and 600 ° C or less Retention rate may be 13% or more.

[Equation 2]

Carbon content retention rate (%) = (carbon content of airgel after heat treatment (% by weight)) / (original carbon content of airgel (% by weight))

More specifically, the airgel of the present invention may have a carbon content retention of 15% or more, preferably 13% or more and 70% or less, more preferably 15% or more and 60% or less.

More specifically, the airgel of the present invention may be one that satisfies at least one of the following 1) to 5) when the heat treatment for 1 hour to 5 hours at a temperature of 500 ℃ to 600 ℃, Preferably, all of 1) to 5) may be satisfied.

1) 40% or more when heat treated for 1 hour

2) 24% or more when heat treated for 2 hours

3) 20% or more when heat treated for 3 hours

4) 17% or more when heat treated for 4 hours

5) 15% or more when heat treated for 5 hours

More specifically, the airgel of the present invention may be one that satisfies at least one of the following 1) to 5) when the heat treatment for 1 hour to 5 hours at a temperature of 500 ℃ to 600 ℃, Preferably, all of 1) to 5) may be satisfied.

1) 40% or more and 60% or less when heat treated for 1 hour

2) 24% or more and 50% or less when heat treated for 2 hours

3) 20% or more and 45% or less when heat-treated for 3 hours

4) 17% or more and 42% or less when heat treated for 4 hours

5) 15% or more and 40% or less when heat treated for 5 hours

In addition, when the airgel blanket of the present invention is heat-treated for 1 hour to 5 hours at a temperature of 500 ° C or more and 600 ° C or less, the thermal conductivity increase rate calculated by Equation 3 below may be 17% or less.

[Equation 3]

Thermal conductivity increase rate (%) = (Thermal conductivity of airgel blanket (mW / mK) at 25 ° C after heat treatment) / (Initial thermal conductivity of airgel blanket at 25 ° C (mW / mK))

As described above, the airgel blanket of the present invention has a high carbon content retention rate and a low increase rate of thermal conductivity even when the high temperature heat treatment is performed, thereby maintaining excellent thermal insulation performance.

This is because hydrophobic airgel may be present in the internal structure as well as the surface structure of the airgel included in the airgel blanket by mixing the hydrophobic airgel powder with the silica sol and using it as an airgel precursor. Bar and hydrophobic holding power is excellent also in the heat treatment at high temperature.

In addition, the airgel blanket of the present invention may have a density of 130 g / cm ³ to 200 g / cm ³ and a porosity of 80% to 99%. At this time, the density of the airgel blanket can be measured using a density measuring device (TAP Density Volumeter, Engelsman Model STAV II), the porosity can be measured using a specific surface area method using a 3Flex instrument of Micrometrics.

Such a high hydrophobic airgel blanket can maintain a low thermal conductivity even at high temperatures can be used in a variety of fields, such as insulation, ultra-low dielectric film, catalyst, catalyst carrier, or blanket, in particular, Pore properties can be useful in the manufacture of thermal insulation because it can maintain low thermal conductivity.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited only to them.

Example  One

To a mixed solution prepared by mixing tetraethylorthosilicate and ethanol in a weight ratio of 3: 1 (silica content = 4% by weight), a hydrochloric acid solution (concentration = 0.15%) diluted in water was added at a pH of 1 Silica sol was prepared by addition and mixing to make the addition. Airgel powder was then mixed with 140 ml of the prepared silica sol in an amount of 25 parts by weight based on 100 parts by weight of the silica in the silica sol to prepare an airgel precursor. In this case, the airgel powder is prepared by preparing a silica sol using tetraethylorthosilicate, gelling it, and surface modification with hexamethyldisilazane (carbon content: 11% by weight of the total weight of the airgel powder). Next, an ammonia catalyst was added to the prepared airgel precursor in an amount of 0.5% by volume based on the total volume of the airgel precursor, and glass fibers were deposited and gelled to prepare a wet gel-based composite. Subsequently, the prepared wet gel-based composite was aged by standing in ethanol at a temperature of 70 ° C. for 2 hours. Subsequently, the surface modifier solution prepared by mixing polydimethylsiloxane and ethanol in a volume ratio of 1:19 was added at a 90 volume ratio based on the volume of the wet gel 100, and surface modified at 70 ° C. for 5 hours to give a hydrophobic wet gel-based substrate. The complex was prepared. Then, the hydrophobic wet gel-based composite was added to an extractor in a supercritical equipment, supercritical drying was performed using supercritical CO ₂ , and heat-treated at 150 ° C. for 1 hour to prepare an airgel blanket.

Example  2

An airgel blanket was prepared in the same manner as in Example 1 except that the airgel powder was used in an amount of 50 parts by weight based on 100 parts by weight of silica when the airgel precursor was prepared.

Example  3

An airgel blanket was prepared in the same manner as in Example 1, except that the hydrophobic wet gel-based composite was dried for 12 hours at a temperature of 120 ° C. under 1 ± 0.3 atm.

Example  4

0.5 L of acid ion exchange resin (Duolite ™ C20) of styrene-divinyl benzene copolymer with sulfonic acid group in 1 L of sodium water glass solution (SiO ₂ content = 7 wt%, Na ₂ O: SiO ₂ molar ratio = 1: 3.3) After addition was stirred (pH 2.7). The ion exchange resin was filtered off from the resulting mixture, and then adjusted to pH 4.7 by addition of 1 M NaOH solution. The resulting gel was aged at 85 ° C. for 6 hours and then water was extracted with 3 L of acetone. Chloropropyl trichlorosilane (added 50 mg per 1 g of acetone-containing gel) was added to the resulting acetone-containing gel, reacted for 5 hours, and washed with 1 L of acetone. Under an atmosphere of a gel of the resulting atmosphere for 3 hours at 40 ℃, and dried at 50 ℃ in 2 hours and 150 ℃ 12-hour sequential surface functionalised the airgel powder was prepared (airgel density = 0.152 g / cm ^3, BET specific surface area = 638 m ² / g, carbon content: 10.2% by weight of the total weight of the airgel powder).

An airgel blanket was prepared in the same manner as in Example 1 except for using the surface functionalized airgel powder prepared above.

Example  5

After cooling 424 g of a 7.5% hydrochloric acid solution to 10 DEG C, 712 g of a sodium water glass solution (containing 13% by weight of silicon dioxide and a ratio of sodium oxide to silicon dioxide = 1: 3.3) was added dropwise and cooled to 10 DEG C. . PH was 4.7. The resulting hydrogel was kept at 85 ° C. for at least 30 minutes and then washed with 3 L of hot water. Then, for silylation, 1 L of hexamethyldisiloxane (HMDSO) and 100 ml of concentrated hydrochloric acid solution were heated until boiling in the flask and treated for at least about 30 minutes by hot nitrogen fractionation (50 l / h, 100 ° C.). Heated to 80 ° C. and then passed through the wet gel (150 ml). The resulting gel was then dried for 1 hour at hot nitrogen fractionation (1500 l / h, 200 ° C.) to give an aerogel powder (aerogel density = 0.124 g / cm 3, BET specific surface area = 685 m 2 / g, carbon content: aerogels) 12.3% by weight of the total weight of the powder, application area 3.0 nm ^-2 )

An airgel blanket was prepared in the same manner as in Example 1 except that the airgel powder prepared above was used.

Example  6

2 L of sodium water glass solution (content of 6% by weight of silicon dioxide, sodium oxide: silicon dioxide ratio 1: 3.3) was filled with 4 L of acid ion exchange resin (Duolite ™ C20) of styrene-divinylbenzene copolymer with sulfonic acid group Passed through a glass column (jacketed glass column (length = 100 cm, diameter = 8 cm) at a rate of about 70 ml / min. The column is operated at about 7 ° C. As a result, 1.0 mol of sodium hydroxide solution was added to the silica solution (pH 2.3) flowing out from the end of the bottom of the column until the pH 4.7, and then maintained at 85 ℃ for 3 hours to carry out the condensation polymerization reaction. The resulting gel was washed with concentrated hydrochloric acid solution until the pore water of the gel became 10% hydrochloric acid solution. Then, for silylation, 100 g of the resulting hydrogel was suspended in 100 ml of hexamethyldisiloxane (HMDSO) followed by the addition of 31.5 g (42 ml) of trimethylchlorosilane (TMCS). An aqueous phase (120 ml of concentrated HCl) was formed below the HMDSO phase by gas (HCl) release. The resulting hydrophobized gel was separated from the HMDSO phase and then dried by hot nitrogen fractionation (1500 l / h at 200 ° C.) for 1 hour to obtain an aerogel powder (aerogel density = 0.101 g / cm 3, BET specific surface area =). 728 m 2 / g, carbon content: 11.2% by weight of the total weight of the airgel powder, application 2.5 nm ^-2 )

An airgel blanket was prepared in the same manner as in Example 1 except that the airgel powder prepared above was used.

Example  7

2 L of sodium water glass solution (content of 6% by weight of silicon dioxide, sodium oxide: silicon dioxide ratio 1: 3.3) were filled with 4 L of acid ion exchange resin (Duolite ™ C20) of styrene-divinyl benzene copolymer with sulfonic acid group Passed through a glass column (jacketed glass column (length = 100 cm, diameter = 8 cm) at a rate of about 70 ml / min. The column is operated at about 7 ° C. As a result, 1.0 mol of sodium hydroxide solution was added to the silica solution (pH 2.3) flowing out from the end of the bottom of the column until the pH 4.7, and then maintained at 85 ℃ for 3 hours to carry out the condensation polymerization reaction. Subsequently, for silylation, 1 L of trimethylsiloxane ((CH ₃ ) ₃ SiOH) and 100 ml of concentrated hydrochloric acid solution were heated until boiling in a flask and the formed gas mixture was heated to a hot nitrogen stream (50 l / h, 100 ° C.). Was treated for at least about 30 minutes, heated to 80 ° C., and then passed through the wet gel (150 ml). The resulting gel was then dried for 1 hour in hot nitrogen fractionation (1500 l / h at 200 ° C.) to give an aerogel powder (aerogel density = 0.128 g / cm 3, BET specific surface area = 645 m 2 / g, carbon content: aerogels) 11.8% by weight of the total weight of the powder, application 2.4 nm ⁻² ).

An airgel blanket was prepared in the same manner as in Example 1 except that the airgel powder prepared above was used.

Example  8

The above embodiment except that the polyester fiber batting as the substrate for the blanket uses a reinforcing structure of a lofty silica fiber structure (Quartz el, Saint-Gobain Quartz) containing a polyvinyl alcohol binder and having a density of 65 g / m 2. Airgel blanket was prepared in the same manner as in 1.

Comparative example  One

An airgel blanket was prepared in the same manner as in Example 1, except that no airgel powder was further added in the preparation of the airgel precursor in Example 1.

Comparative example  2

An airgel blanket was prepared in the same manner as in Example 1, except that hydrophilic precipitated silica powder (manufactured by Evonkit, 22S) was used instead of the airgel powder in the preparation of the airgel precursor in Example 1.

Experimental Example  1: Carbon content comparison analysis

The initial carbon content of each airgel prepared in Examples and Comparative Examples was measured, and the carbon content of the airgel was measured after heat treatment at temperatures of 400 ° C., 500 ° C. and 600 ° C. for 1 to 5 hours. As shown in Figures 2 to 4, Tables 1 to 3 to calculate the carbon content retention rate. On the other hand, the carbon content was measured using a carbon analyzer (ELTRA, CS-800).

-Carbon content retention rate (%) = (carbon content of airgel after heat treatment (% by weight)) / (initial carbon content of airgel before heat treatment (% by weight))

		Example 1		Example 2		Comparative Example 1		Comparative Example 2
Temperature (℃)	Heat treatment time (hr)	Carbon content	Carbon content retention rate	Carbon content	Carbon content retention rate	Carbon content	Carbon content retention rate	Carbon content	Carbon content retention rate
400	0	10.1	100	11.84	100	9.78	100	6.98	100
	One	8.01	79.30	9.1	76.85	7.12	72.80	4.32	61.89
	2	7.2	71.28	7.74	65.37	5.9	60.32	3.56	51.00
	3	6.71	66.43	7.43	62.75	5.75	58.79	3.3	47.27
	4	6.41	63.46	7.11	60.05	5.66	57.87	3.21	45.98
	5	6.4	63.36	7.01	59.20	5.5	56.23	3.1	44.41

		Example 1		Example 2		Comparative Example 1		Comparative Example 2
Temperature (℃)	Heat treatment time (hr)	Carbon content	Carbon content retention rate	Carbon content	Carbon content retention rate	Carbon content	Carbon content retention rate	Carbon content	Carbon content retention rate
500	0	10.1	100	11.84	100	9.78	100	6.98	100
	One	5.81	57.52	6.74	56.92	1.2	12.26	0.56	8.02
	2	4.9	48.51	5.75	48.56	0.5	5.11	0.34	4.87
	3	4.42	43.76	5	42.22	0.3	3.06	0.19	2.72
	4	4.14	40.99	4.48	37.83	0.22	2.24	0.15	2.14
	5	3.95	39.10	4.5	38.00	0.19	1.94	0.11	1.57

		Example 1		Example 2		Comparative Example 1		Comparative Example 2
Temperature (℃)	Heat treatment time (hr)	Carbon content	Carbon content retention rate	Carbon content	Carbon content retention rate	Carbon content	Carbon content retention rate	Carbon content	Carbon content retention rate
600	0	10.1	100	11.84	100	9.78	100	6.98	100
	One	4.15	41.08	5.05	42.65	0.7	7.15	0.29	4.15
	2	2.84	28.11	2.89	24.40	0.3	3.06	0.21	3.00
	3	2.42	23.96	2.45	20.69	0.22	2.24	0.12	1.71
	4	2.12	20.99	2.15	18.15	0.12	1.22	0.08	1.14
	5	1.98	19.60	1.99	16.80	0.09	0.92	0.08	1.14

As shown in Tables 1 to 3, the aerogels of Examples 1 and 2 in which an aerogel precursor was prepared by adding a hydrophobic airgel powder to a silica sol were compared with those of Comparative Example 1, in which the aerogel powder was not added during preparation of the aerogel precursor. It was confirmed that the carbon content retention after heat treatment was higher than before. In particular, as the heat treatment time is performed within the first 1 hour, and at a very high temperature of 500 ℃ or more, it was confirmed that the carbon content retention ratios of Examples 1 and 2 and Comparative Example 1 were significantly different.

In addition, in preparing the airgel precursor, Comparative Example 2, in which precipitated silica powder was added instead of hydrophobic airgel powder, did not have a high carbon content retention rate as compared with Comparative Examples 1 as well as Examples 1 and 2, and thus, It was confirmed that the hydrophobic holding power was remarkably inferior.

Compared with Comparative Examples 1 and 2, the higher carbon content retention rate of Examples 1 and 2 was obtained by mixing a hydrophobic airgel powder with a silica sol to prepare a silica precursor, thereby providing hydrophobicity not only on the surface structure but also on the internal structure of the finally prepared airgel. According to the presence of the airgel, the airgel blanket of the present invention can have a high hydrophobicity compared to the conventional airgel blanket, it can be expected that the hydrophobic retention is excellent even at high temperature applications.

On the other hand, compared with Example 1, Example 2 does not have a large difference in terms of carbon content retention rate, but contains a higher amount of carbon content than Example 1 in terms of absolute amount of carbon content, thereby maintaining higher hydrophobicity. It can be seen that. This is because Example 2 added a higher amount of hydrophobic airgel powder.

Example 1 has the advantage that can maintain high hydrophobicity at the same time does not weaken the thermal insulation performance compared to Comparative Example 1 not added hydrophobic airgel powder, Example 2 compared to Example 1 by the addition of a larger amount of hydrophobic airgel powder Since the insulation performance is somewhat inferior to the higher hydrophobicity, the amount of hydrophobic airgel powder can be adjusted to produce a more suitable airgel blanket according to the application environment and application of the insulation.

Experimental Example  2: comparative analysis of thermal conductivity

The initial thermal conductivity of each airgel blanket prepared in Examples and Comparative Examples was measured, and the thermal conductivity of the airgel blanket was measured after heat treatment at temperatures of 400 ° C., 500 ° C. and 600 ° C. for 1 to 5 hours. On the basis of this, the thermal conductivity increase rate is calculated as follows and the results are shown in FIGS. 5 to 7, and Tables 4 to 6. On the other hand, the thermal conductivity was measured at room temperature (25 ℃) using a thermal conductivity measuring device (NETZSCH, HFM436 Lambda).

% Thermal conductivity increase = (thermal conductivity of airgel blanket (mW / mK) at 25 ° C. after heat treatment) / (initial thermal conductivity of airgel at 25 ° C. (mW / mK))

		Example 1		Example 2		Comparative Example 1		Comparative Example 2
Temperature (℃)	Heat treatment time (hr)	Thermal conductivity	Thermal conductivity increase	Thermal conductivity	Thermal conductivity increase	Thermal conductivity	Thermal conductivity increase	Thermal conductivity	Thermal conductivity increase
400	0	17.75	0	19.2	0	17.2	0	18.55	0
	One	18.8	5.91	20.35	5.98	18.45	7.26	19.8	6.73
	2	19.38	9.18	20.78	8.22	18.99	10.40	20.5	10.51
	3	19.65	10.70	20.92	8.95	19.38	12.67	20.89	12.61
	4	19.78	11.43	21.03	9.53	19.54	13.60	21.08	13.63
	5	19.9	12.11	21.2	10.41	19.7	14.53	21.1	13.74

		Example 1		Example 2		Comparative Example 1		Comparative Example 2
Temperature (℃)	Heat treatment time (hr)	Thermal conductivity	Thermal conductivity increase	Thermal conductivity	Thermal conductivity increase	Thermal conductivity	Thermal conductivity increase	Thermal conductivity	Thermal conductivity increase
500	0	17.75	0	19.2	0	17.2	0	18.55	0
	One	20.22	13.91	21.6	12.50	20.2	17.44	21.45	15.63
	2	20.25	14.08	21.63	12.65	20.22	17.55	21.68	16.87
	3	20.33	14.53	21.65	12.76	20.23	17.61	21.79	17.46
	4	20.34	14.59	21.66	12.81	20.25	17.73	21.86	17.84
	5	20.38	14.81	21.7	13.02	20.25	17.73	21.91	18.11

		Example 1		Example 2		Comparative Example 1		Comparative Example 2
Temperature (℃)	Heat treatment time (hr)	Thermal conductivity	Thermal conductivity increase	Thermal conductivity	Thermal conductivity increase	Thermal conductivity	Thermal conductivity increase	Thermal conductivity	Thermal conductivity increase
600	0	17.75	0	19.2	0	17.2	0	18.55	0
	One	20.47	15.32	21.02	9.47	20.58	19.65	21.54	16.11
	2	20.58	15.94	21.39	11.40	20.61	19.82	21.64	16.65
	3	20.66	16.39	21.55	12.23	20.77	20.75	21.89	18.00
	4	20.68	16.50	21.75	13.28	20.91	21.56	21.91	18.11
	5	20.65	16.33	21.71	13.07	20.85	21.22	21.98	18.49

As shown in Tables 4 to 6, the aerogel blankets of Examples 1 and 2 in which an airgel precursor was prepared by adding a hydrophobic airgel powder to a silica sol were prepared in Comparative Example 1, in which the airgel precursor was not added. Compared with the airgel blanket, it was confirmed that the thermal conductivity increase rate after heat treatment was not high compared with before heat treatment. In particular, it was confirmed that the thermal conductivity was not significantly increased except within the first hour of the heat treatment time, and the thermal insulation performance was maintained relatively well.

This is due to the effect of the presence of hydrophobic airgel in the internal structure as well as the surface structure of the airgel finally prepared by mixing the hydrophobic airgel powder in the silica sol, the airgel blanket of the present invention It can be expected that the thermal insulation performance is excellent even in the application at high temperature compared to the airgel blanket of.

On the other hand, Comparative Example 2 to which the hydrophilic powder was added rather than the hydrophobic powder was confirmed that the thermal insulation performance is high compared with Example 1, the thermal conductivity increase rate is also high, it is not good.

Experimental Example  3: hydrophobic retention  Furnace test

Hydrophobic holding force was compared and analyzed by Furnace test at high temperature heat treatment of each airgel blanket prepared in Examples and Comparative Examples, and the results are shown in FIGS. 8 to 10.

Specifically, each piece of airgel blanket prepared in Examples and Comparative Examples was subjected to (1) heat treatment at 400 ° C for 1 hour, (2) heat treatment at 500 ° C for 1 hour, and (3) heat treatment at 600 ° C for 1 hour. After the sample was prepared, it was put in a vial containing water to observe the water absorption, and the hydrophobic holding power was evaluated.

As shown in FIGS. 8 to 10, the airgel blankets of Examples 1 and 2 prepared by using the airgel powder in the preparation of the airgel precursor showed high hydrophobic retention even at high temperature heat treatment, but Comparative Examples 1 and 2 Aerogel blanket lost its hydrophobicity by high temperature heat treatment. In particular, the aerogel blanket of Comparative Example 2 using a hydrophilic powder lost hydrophobicity and settled even after heat treatment at a relatively low temperature of 400 ° C. From these results, it can be expected that hydrophilicity at high temperature is easily weakened when hydrophilic powder is used, and durability at high temperature is easily reduced.

Experimental Example  4: NMR comparative analysis

NMR analysis was performed to compare the surface and internal hydrophobicity of each airgel prepared in Example 2 and Comparative Example 1, and the results are shown in Table 7 below.

In Table 7, M represents a monofunctional group [Si (OSi) (R _x ) ₃ ], which is derived from hexamethyldisilazane (HMDS) used in the preparation of the airgel powder, wherein R _x is a methyl group. being). D represents a difunctional group [Si (OSi) ₂ (R _y ) ₂ and Si (OSi0) (R _z ) ₂ (OR _w )], which is derived from polydimethylsiloxane (PDMS), which is a surface modifier. (Wherein R _y , R _z and R _w are each methyl groups), Q represents a tetrafunctional group [(SiO ⁻ ) ₄ ].

peak (intensity)	M	D	Q
Example 2	1.0	1.1	7.8
Comparative Example 1	-	1.0	3.3

As shown in Table 7, Example 2 is a peak derived from hexamethyldisilazane (HMDS) used to prepare hydrophobic airgel powder added even though NMR analysis was performed on any part of the airgel. ), It was found that the added hydrophobic airgel powder was uniformly distributed throughout the airgel. This is in accordance with the expectation that the hydrophobic airgel powder is uniformly dispersed in the ethanol-based silica sol of Example 2 because of its high dispersibility in the ethanol solution.

Therefore, it can be seen that the added hydrophobic airgel powder is uniformly distributed not only on the surface structure of the finally prepared airgel but also on the internal structure. Accordingly, the airgel blanket of the present invention has high hydrophobicity compared to the conventional airgel blanket. It can be confirmed that the hydrophobic holding power is excellent even at high temperatures.

Experimental Example  5: Heat weight  comparison analysis

TGA analysis was performed on each of the airgels prepared in Examples 1 and 2 and Comparative Example 1, and the results are shown in FIG. 11.

As a result, the airgels of Examples 1 and 2 prepared using airgel powder in the preparation of the airgel precursor showed excellent hydrophobic holding power over a wide temperature range, and compared with the loss of most of the hydrophobic groups, especially at ultrahigh temperatures of 500 ° C. or higher. Unlike Example 1, the airgels of Examples 1 and 2 still had about 6% of the hydrophobic group remaining at 500 ° C. or higher, indicating that they exhibited excellent high temperature stability compared to Comparative Example 1.

From the above experimental results, the airgel blanket prepared by using the airgel powder in the preparation of the airgel precursor according to an embodiment of the present invention has excellent hydrophobicity on the surface and the inside can maintain the hydrophobicity stable even at high temperature application It can be seen that.

Claims (30)

1) preparing an airgel precursor by mixing the airgel powder in a silica sol;

2) preparing a wet gel-based composite by adding a basic catalyst to the airgel precursor, depositing the gel on a blanket substrate, and then gelling the gel;

3) preparing a hydrophobic wet gel-based composite by performing surface modification on the wet gel-based composite; And

4) A method for producing an airgel blanket comprising the step of drying the hydrophobic wet gel-based composite.

The method according to claim 1,

The airgel powder is a method for producing an airgel blanket, characterized in that the silica airgel powder.

The method according to claim 1,

The airgel powder is a method for producing an airgel blanket, characterized in that the hydrophobic airgel powder 10 to 12 parts by weight of the carbon content relative to the total weight of the airgel powder.

The method according to claim 1,

The airgel powder is a method for producing an airgel blanket, characterized in that used in an amount of 25 to 50 parts by weight based on 100 parts by weight of silica contained in the silica sol.

 The method according to claim 1,

The silica sol is prepared by mixing an acidic aqueous solution to a mixed solution containing alkoxysilane and alcohol.

The method according to claim 5,

The alcohol is a method for producing an airgel blanket, characterized in that the addition of the silica content contained in the mixed solution is 2% to 6% by weight.

The method according to claim 5,

The acidic aqueous solution is a method of producing an airgel blanket, characterized in that the pH is added so that the mixed solution is 0.5 to 1.

The method according to claim 1,

The surface modification is a method for producing an airgel blanket, characterized in that carried out using at least one surface modifier selected from the group consisting of a silane compound, a silazane compound and a siloxane compound.

The method according to claim 1,

The drying is a method for producing an airgel blanket, characterized in that carried out by a supercritical drying process, or an atmospheric pressure drying process at a temperature of 50 ℃ to 150 ℃ under 1 ± 0.3 atm.

The method according to claim 1,

The airgel powder is a method for producing an airgel blanket, characterized in that the organic functionalized airgel powder.

The method according to claim 10,

Wherein said organic functionalized airgel powder is prepared by reacting a silica wet gel with at least a bifunctional organic compound and drying it.

The method according to claim 11,

The bifunctional organic compound is a method for producing an airgel blanket, characterized in that it comprises at least one functional group that acts as a bond with the airgel.

The method according to claim 11,

The bifunctional organic compound is at least one selected from the group consisting of a halogen group, a pseudo halogen group, a hydroxyl group, a thio group, an amino group, an amide group, an ether group, an ester group, an acid group, a formyl group, a ketone group and a silyl group Method for producing an airgel blanket comprising a hydrocarbon group containing a functional group.

The method according to claim 11,

The bifunctional organic compound includes one or more compounds selected from the group consisting of methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, chloropropyltrichlorosilane, trimethyl methoxysilane and hexamethyldisilazane Airgel blanket production method characterized in that.

The method according to claim 10,

The organic functionalized airgel powder is a method for producing an airgel blanket, characterized in that the surface silylated airgel powder having the characteristics of i) or ii):

i) does not contain a Si-OR group (R is an alkyl group having 1 to 18 carbon atoms)

ii) the degree of coverage of internal surface or coverage by an organic surface group applied by surface silylation, calculated according to Equation 1 below, of at least 90%

 [Equation 1]

Application = [C] / [BET] * K; Unit: [nm ^-2 ]

^{Wherein, K = 6.022 * 10 23/} 100 * 12 * 3 * 10 18 = 167.28; Unit: [g ^-1 ]

[C]: C content; Unit [wt%]

[BET]: BET surface area; Unit: [m ² / g]

The method according to claim 15,

The organic functionalized airgel powder is prepared by reacting the wet gel with a silylating agent to modify the surface of the wet gel and then dry it.

The silylating agent is a method for producing an airgel blanket, characterized in that it comprises one or more compounds selected from the group consisting of hexamethyldisiloxane and trimethylchlorosilane.

The method according to claim 1,

The blanket base material includes a reinforcing structure,

The reinforcing structure is a lofty fibrous batting, wherein the fibers are oriented along all three axes, and the bet is in the form of a sheet,

The Lofty fibrous bets are compressible to at least 50% of the thickness and recover to at least 70% of the original thickness after compression for 5 seconds, the density of the Lofty fibrous bets is between 0.001 g / cm ³ and 0.26 g / cm ³ ,

Method for producing an airgel blanket, characterized in that the cross-sectional area of the identifiable fibers in the cross section of the final airgel blanket is less than 10% of the total cross-sectional area.

The method according to claim 17,

The reinforcement structure is a polyester batting reinforcement structure; Polyester fiber batting comprising a polyvinyl alcohol binder; Lofty silica fiber structures; Fiber laminates of polyester / silicon carbide / copper mesh / silicon carbide / polyester; A stack of unidirectional carbon fiber / copper mesh / loft polyester batting comprising a polyester batting / polymerizable binder; And a laminate of silica felt / stainless steel mesh / silica felt.

A base material for aerogels and blankets,

When the airgel is heat-treated for 1 hour to 5 hours at a temperature of 400 ° C or more and less than 500 ° C, an airgel blanket satisfying at least one of the following 1) to 5) carbon content retention rate calculated by Equation 2 below.

[Equation 2]

Carbon content retention rate (%) = (carbon content of airgel after heat treatment (% by weight)) / (original carbon content of airgel (% by weight))

1) More than 75% when heat treated for 1 hour

2) 65% or more when heat treated for 2 hours

3) 60% or more when heat treated for 3 hours

4) 59% or more when heat treated for 4 hours

5) 58% or more when heat treated for 5 hours

The method according to claim 19,

The airgel is an airgel blanket, characterized in that when the heat treatment for 1 hour to 5 hours at a temperature of 400 ℃ or more less than 500 ℃ satisfies at least one of the following 1) to 5).

1) 75% or more and 80% or less when heat treated for 1 hour

2) 65% or more and 75% or less when heat treated for 2 hours

3) 60% or more and 70% or less when heat-treated for 3 hours

4) 59% or more and 65% or less when heat treated for 4 hours

5) 58% or more and 64% or less when heat treated for 5 hours

The method according to claim 19,

When the airgel blanket is heat treated at a temperature of 400 ° C. or more and less than 500 ° C. for 1 to 5 hours, the thermal conductivity increase rate calculated by Equation 3 below satisfies at least one of the following 1) to 5). Aerogel blanket.

[Equation 3]

Thermal conductivity increase rate (%) = (Thermal conductivity of airgel blanket (mW / mK) at 25 ° C after heat treatment) / (Initial thermal conductivity of airgel blanket at 25 ° C (mW / mK))

1) 6% or less when heat treated for 1 hour

2) 10% or less when heat treated for 2 hours

3) 11% or less when heat treated for 3 hours

4) 12% or less when heat treated for 4 hours

5) 13% or less when heat treated for 5 hours

The method according to claim 19,

The airgel blanket is an airgel blanket, characterized in that when the heat treatment for 1 to 5 hours at a temperature of 400 ℃ or more less than 500 ℃ satisfies at least one of the following 1) to 5).

1) 5% or more and 6% or less when heat treated for 1 hour

2) 7% or more and 10% or less when heat treated for 2 hours

3) 8% or more and 11% or less when heat-treated for 3 hours

4) 9% or more and 12% or less when heat treated for 4 hours

5) 10% or more and 13% or less when heat treated for 5 hours

A base material for aerogels and blankets,

When the airgel is heat-treated for 1 to 5 hours at a temperature of 500 ° C or more and 600 ° C or less, the air content blanket is 13% or more carbon content retention calculated by Equation 2 below.

[Equation 2]

Carbon content retention rate (%) = (carbon content of airgel after heat treatment (% by weight)) / (original carbon content of airgel (% by weight))

The method according to claim 23,

The airgel is an airgel blanket, characterized in that the carbon content retention rate is 15% or more when heat-treated for 1 hour to 5 hours at a temperature of 500 ℃ to 600 ℃ or less.

The method according to claim 23,

The airgel is an airgel blanket, characterized in that the carbon content retention rate is 13% or more and 70% or less when heat-treated for 1 hour to 5 hours at a temperature of 500 ℃ to 600 ℃ or less.

The method according to claim 23,

The airgel is an airgel blanket, characterized in that the carbon content retention rate is 15% or more and 60% or less when heat-treated for 1 hour to 5 hours at a temperature of 500 ° C or more and 600 ° C or less.

The method according to claim 23,

The airgel is an airgel blanket, characterized in that when the heat treatment for 1 to 5 hours at a temperature of 500 ℃ to 600 ℃ below at least any one of the following 1) to 5).

1) 40% or more when heat treated for 1 hour

2) 24% or more when heat treated for 2 hours

3) 20% or more when heat treated for 3 hours

4) 17% or more when heat treated for 4 hours

5) 15% or more when heat treated for 5 hours

The method according to claim 23,

The airgel is an airgel blanket, characterized in that when the heat treatment for 1 to 5 hours at a temperature of 500 ℃ to 600 ℃ below at least any one of the following 1) to 5).

1) 40% or more and 60% or less when heat treated for 1 hour

2) 24% or more and 50% or less when heat treated for 2 hours

3) 20% or more and 45% or less when heat-treated for 3 hours

4) 17% or more and 42% or less when heat treated for 4 hours

5) 15% or more and 40% or less when heat treated for 5 hours

The method according to claim 23,

The airgel blanket is an airgel blanket, characterized in that when the heat treatment at a temperature of 500 ° C or more and 600 ° C or less for 1 hour to 5 hours, the thermal conductivity increase rate calculated by Equation 3 below 17%.

[Equation 3]

Thermal conductivity increase rate (%) = (Thermal conductivity of airgel blanket (mW / mK) at 25 ° C after heat treatment) / (Initial thermal conductivity of airgel blanket at 25 ° C (mW / mK))

 30. An insulating material comprising the airgel blanket of claim 19.

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