KR101129375B1 - Porous Ceramic Prepared From Sodium Silicate and Aerogel and A Method for Preparing Thereof - Google Patents

Abstract

The present invention relates to a ceramic porous body made from water glass and airgel having excellent thermal insulation, heat resistance and ultra-lightness by synergy of pores formed by foaming water glass and fine pores of airgel, and a method of manufacturing the same. According to the present invention, a ceramic porous body which is a fired body of a fired mixture in which water glass and an airgel are mixed in a weight ratio of 2: 1 to 8: 1 as an inorganic additive; And preparing a calcined mixture by mixing the water glass with the airgel as an inorganic additive in a 2: 1 to 8: 1 weight ratio, and then calcining the calcined mixture into a desired shape and calcining at 120 to 800 ° C. for 10 minutes to 2 hours. Provided is a method of manufacturing a ceramic porous body. The new ceramic fired body according to the present invention manufactured from a mixture of water glass and aerogel not only has excellent heat insulating property, but also is light weight and energy saving function of new material as ultra-light fired body in terms of weight, and can be applied to various fields as advanced materials. Can be.

Water glass, aerogels, organic solvents, inorganic materials, ceramic porous bodies, firing, foaming, ultralight, ultra-insulation

Description

Porous Ceramic Prepared From Sodium Silicate and Aerogel and A Method for Preparing Thereof}

The present invention relates to a ceramic porous body prepared from water glass and aerogels and a method for producing the same. More specifically, the present invention relates to a ceramic porous body made from water glass and airgel having excellent super-insulation and ultra-lightness by synergy of pores formed by foaming water glass and fine pores of airgel, and a method for manufacturing the same.

Recently, the necessity of ultra-light and ultra-insulating materials is increasing due to the specialization of the industrial field, the advancement of building materials, and the demand for new energy-saving materials. Currently, lightweight organic insulating materials such as polyurethane, styrofoam, and other representative organic products, pearlite, and diatomaceous earth are mainly used. However, polyurethane and styrofoam have not only a fatal drawback that is very weak at high temperatures, but also harmful to the human body since a very toxic gas is generated in case of fire. On the other hand, pearlite and diatomaceous earth, which are inorganic materials, are excellent in terms of heat resistance, but are insufficient to meet the demands of the state-of-the-art technology in terms of light weight, heat insulation, and heat resistance. Therefore, there is a need for a new ceramic porous body having super insulation and ultra lightweight.

In one aspect, the present invention is to provide a novel ceramic porous body having excellent ultra-thermal insulation and ultra-lightness made from water glass and aerogels.

In another aspect, the present invention is to provide a novel method for producing a ceramic porous body having excellent superheat insulation and ultralightness.

According to one aspect of the invention,

There is provided a ceramic porous body which is a plastic foam of a fired mixture in which water glass and an airgel are mixed in a weight ratio of 2: 1 to 8: 1 as an inorganic additive.

According to another aspect of the present invention,

Preparing a fired mixture by mixing the water glass with the airgel as an inorganic additive in a 2: 1 to 8: 1 weight ratio;

There is provided a ceramic porous body manufacturing method comprising the step of molding the plastic mixture in a desired shape and baking for 10 minutes to 2 hours at 120 to 800 ℃.

The new ceramic porous body according to the present invention, which is a plastic foam prepared from a mixture of water glass and aerogel, has excellent super-thermal insulation and ultra-light weight. The ceramic porous body of the present invention (sometimes referred to as "fired foam") exhibits fire resistance even at a high temperature of 1000 ° C or higher, and is excellent in heat resistance and does not generate toxic gas during combustion. In addition, it has an excellent sound insulation effect. Ceramic porous body according to the present invention can be applied to various fields as a high-tech material that meets the weight reduction and energy saving function of the new material. Specifically, it can be applied to technical fields requiring thermal insulation, such as refrigerated warehouses, double insulation panels, building interior insulation materials, soundproof panels, pipe insulation materials, ship interior materials, thermal insulation materials in kilns and melting furnaces, and home appliance insulation materials. have.

The present invention has been made to provide a novel ceramic porous body having excellent light weight and ultra-thermal insulation, and according to the present invention, a ceramic porous body which is a plastic foam of a plastic mixture comprising water glass and aerogel is provided. That is, by firing the plastic mixture including the water glass and the airgel, a porous ceramic structure in which the pores formed by the foaming of the water glass and the fine pores inherent in the airgel is uniformly mixed, thereby obtaining a new ceramic porous body exhibiting excellent superheat insulation and ultralightness.

As the water glass, any kind of water glass generally known may be used. Although not specifically limited to this, for example, any one, two, three and / or four kinds of water glass according to the KS M 1415 standard may be used. Water glass standards according to these KS M 1415 standards are as shown in Table 1 below.

[Table 1] Water Glass Industrial Standard according to KS M 1415

Type 1 2 types 3 types 4 types importance
(20 ° C, g / cm ³ ) 1.690 or higher 1.590 or more 1.380 or more 1.260 or more Water insoluble
(weight%) 0.2 or less 0.2 or less 0.2 or less 0.2 or less Sodium oxide (Na ₂ O) (% by weight) 17? 18  14-15  9? 10  6? 7 Silicon dioxide (SiO ₂ ) (% by weight) 36? 38  34? 36  28-30  23-25

(The remainder other than the constituents of the water glass shown in Table 1 above is water.

The water insoluble content is not limited thereto, but may be a component such as silica, iron, TiO ₂ , Al, Mg, and Cu.)

More preferably, water glass having a SiO ₂ content of 7 to 30% by weight is preferably used in the ceramic porous body so that a plurality of pores of as small and uniform size as possible are formed in a uniform distribution and exhibit excellent strength. Water glass having a content of SiO ₂ of less than 7% by weight has a very small viscosity, and therefore, a portion having a high SiO ₂ content exists due to the rapid vaporization of water at high temperature firing, and thus, large pores as in high viscosity water glass. This can be formed. Thus, locally nonuniform pores are formed in the ceramic porous body. On the other hand, since the content of the foaming component is small in general, the pore formation is not preferable. In addition, since the amount of water increases compared to the content of SiO ₂ in the water glass that acts as a caking agent when firing foaming, it is uneconomical, and the smooth mixing of the water glass and airgel due to too low viscosity is a problem. For reference, a photograph of a plastic foam (firing condition at 250 ° C., 2 hours) formed of water glass diluted three times with water (KS standard water glass (SiO ₂ 36-38 wt%): water 1: 3 weight ratio mixture) is shown in FIG. 1. Shown in

Water glass having a content of more than 30 wt% SiO ₂ has a high viscosity, and due to the high viscosity, a number of coarse pores are formed in the ceramic porous body which is a plastic foam of water glass. As such, the ceramic porous body including a large number of coarse pores is not preferable because the strength is very weak and therefore easily broken by a weak impact. In addition, it is difficult to mix smoothly with the airgel due to the high viscosity. For reference, the plastic foam formed of one kind of water-glass KS standard containing 36 to 38% by weight of SiO ₂ is shown in Figure 2 the picture of (baking conditions 250 ℃, 2 hours).

For the reasons as described above, it is preferable to use a water glass having a SiO ₂ content of 7 to 30% by weight so that a plurality of pores as small and uniform as possible in the silica porous body are formed in an even distribution. Therefore, one, two, three and four water glasses according to the KS M 1415 standard is preferably diluted with water so as to have a SiO ₂ content of 7 to 30% by weight, if necessary. Specifically, one kind and two kinds of water glass are preferably diluted and used, and three kinds and four kinds of water glass can be used as it is.

Aerogels formulated as inorganic additives in the plastic mixtures used in the manufacture of the porous ceramic bodies according to the present invention have a specific surface area of 600-1500 m2 / g with numerous pores. It exhibits excellent thermal insulation as a low density (0.05 to 0.3 g / cm ³ ), highly porous material having a low thermal conductivity, specifically, a thermal conductivity of 5 to 30 mW / mk. The airgel used in the present invention is not particularly limited, and any kind of airgel generally known may be used. More specifically, silica airgel can be used, and hydrophobized airgel and hydrophobized silica airgel can also be preferably used. In the case of using a hydrophobized airgel, the ceramic porous body exhibits excellent water resistance and water repellency due to the hydrophobicity of the surface of the airgel. Furthermore, due to the hydrophobicity of the surface of the airgel, the inflow of moisture into the ceramic porous body is blocked, so that small, uniform pores are not damaged, and thus, super-insulation and ultra-lightness can be maintained for a long time. In addition, the airgel may be a powder or granular airgel.

Aerogels are generally prepared in a sol-gelation process. The sol-gelation process may be performed using any suitable sol-gel technique known in the art [R.K. Colloid Chemistry of Silica and Silicates 1954, chapter 6; C.J. Brinker, G.W. Scherer, Sol-Gel Science, 1990, Chaps 2 and 3].

That is, an airgel is obtained by preparing a wet gel by the sol-gelation process of an airgel precursor and drying the wet gel. Specifically, the wet gel is obtained through hydrolysis, condensation and aging by the reaction of the aerogel precursor and water during the sol-gelation process. For example, hydrolysis proceeds by adding a catalyst to an aerogel precursor and water in an alcohol solvent, and a condensation reaction of the hydrolyzate proceeds to form a “sol” compound. At this time, the condensation reaction can be carried out in the presence of a base or an acid catalyst. After the sol solution is gelled, it is aged for a sufficient time to prepare a wet gel.

Although not limited thereto, for example, the airgel may be prepared by a process of preparing a wet gel using an airgel precursor and a process of drying the wet gel. The sol-gelation process is used in the preparation of wet gels. In the sol-gelation process, first, the hydrogel is subjected to hydrolysis and condensation reaction by hydrolysis (step 1), and then, a gel is formed (step 2) through gelation and aging. Although not limited thereto, hydrochloric acid or the like is added as a catalyst to the aerogel precursor solution dissolved in ethanol and partially hydrolyzed by dropwise addition of distilled water. Thereafter, in step 2, distilled water and methanol may be added to the solution produced in step 1, and a wet gel may be formed using a catalyst such as aqueous ammonia.

For example, but not limited to, aerogel precursors may be water glass or metal alkoxides having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The metal alkoxide is not limited to this, but tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), tetra-n-propoxysilane, aluminum isopropoxide, aluminum-sec-butoxide, cerium iso At least one selected from the group consisting of propoxide, hafnium tert-butoxide, magnesium aluminum isopropoxide, yttrium isopropoxide, titanium isopropoxide and zirconium isopropoxide may be used alone or in combination. have. In particular, tetraethoxy silane (TEOS) and / or tetramethoxysilane (TMOS) comprising silanes are the most preferred metal alkoxides.

Hydrophobized airgels can be prepared, for example, by hydrophobizing the wet gel. Although hydrophobization treatment is not limited to this, For example, the surface of a wet gel can be manufactured by silylating (hydrophobizing) by making a wet gel react with a silylating agent etc., for example. As the silylating agent, hexamethyldisilane, ethyltrimethoxysilane, ethyltriethoxysilane, triethylethoxysilane, trimethylethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane and methoxytrimethylsilane are generally used. , Trimethylchlorosilane, triethylchlorosilane and the like can be used.

An aerogel is obtained by drying the wet gel or hydrophobized wet gel. Drying can be performed by methods such as atmospheric pressure drying or supercritical drying. If necessary, solvent substitution may be carried out before drying the wet gel or the hydrophobization wet gel, and solvent replacement may be performed simultaneously with the hydrophobization treatment.

The plastic mixture used to form the ceramic porous body may include water glass and an airgel inorganic additive in a 2: 1 to 8: 1 weight ratio. If the amount of water glass is less than the lower limit, the amount of water glass is too small, resulting in insufficient pore formation and caking due to foaming of the water glass. If the amount of water glass is higher than the upper limit, non-uniform pores having a different degree of foaming may be formed due to non-uniform mixing of water glass and airgel, and the heat insulation of the ceramic porous body is deteriorated due to non-uniform pore formation, which is not preferable.

In another embodiment of the present invention, as well as the airgel as the inorganic additive, other inorganic materials may also additionally be used together. That is, as the inorganic additive, if necessary, but not limited thereto, for example, at least one inorganic material selected from the group consisting of ocher powder, mica, talc, silica, diatomaceous earth, titania (TiO ₂ ), pearlite and activated carbon May be used with the airgel. These inorganic materials may be used alone or in combination of two or more. By using aerogel and the other inorganic materials together as an inorganic additive, not only the cost of producing the ceramic porous body is reduced, but also the properties due to the properties of the inorganic material can be imparted to the ceramic porous body. Although not limited to this, for example, the ocher powder has a far infrared radiation effect, and the ceramic porous body obtained by blending the ocher powder also has far infrared radiation. Tatinia has the function of a photocatalyst, and the ceramic porous body obtained by mix | blending titania powder can also expect the effect of a photocatalyst.

The particle size of the inorganic material is not particularly limited, but in consideration of uniform mixing and foaming properties with aerogels and water glass, particle sizes of hundreds of nanoscales to thousands of microscales, preferably 1 μm to 500 μm Inorganic materials having a can be used.

In the case where the inorganic material is further included as the inorganic additive, the airgel: inorganic material may be blended in an amount of 1:10 weight ratio or less.

By blending the inorganic material in an amount of 10 parts by weight or less with respect to 1 part by weight of the airgel, the airgel is physically adsorbed on the surface of the inorganic material so that the inorganic material also exhibits hydrophobicity, which is the property of the airgel. Therefore, the ceramic porous body made of a hydrophobic mixture containing an airgel and an inorganic material in a 1:10 weight ratio or less is preferable because the porosity of the ceramic porous body is maintained even after a long time, and thus heat insulation is maintained for a long time.

When the content of the inorganic material exceeds the upper limit, the amount of the inorganic material with low foamability is increased with respect to the whole plastic mixture, and the relative content of the airgel in the plastic mixture is not only reduced, but also the amount of water glass is also relatively reduced. It may not be desirable in terms of pore securing. In addition, due to the excess inorganic material, the hydrophobicity of the airgel may not be sufficiently expressed. In addition, the said arbitrary inorganic material is a component which can be mix | blended further as needed, and a lower limit is not specifically limited.

In the case of using an airgel and any of the inorganic materials together as an inorganic additive, as described above in consideration of the pore formation by the water glass and the strength of the porous body, the water glass: the inorganic additive including the airgel and the inorganic material is 2: 1 to It may be combined in an 8: 1 weight ratio.

Since the water glass contains a considerable amount of water, a ceramic porous body is obtained due to the foaming of the water glass by the reaction of the water and the water glass when firing by heating the calcined mixture. However, it is preferable to further mix the organic solvent in the calcined mixture so that the ceramic porous body having more uniform pores is formed.

As the organic solvent, alcohols such as methanol, ethanol, propanol or acetone may be used. These organic solvents not only evaporate rapidly from a relatively low temperature during the firing process because the vapor pressure at the same temperature is much higher than that of water, and some remaining organic solvents also evaporate rapidly through the small pores of the ceramic porous body at a relatively high temperature. In order to form a plurality of uniform and fine pores in the.

In addition, by using an additional organic solvent, the viscosity of the calcined mixture, specifically, water glass, is adjusted to a more suitable state for forming a plurality of uniform pores. More specifically, in the organic gel which is a mixture of water glass (Na ₂ O? SiO ₂ ? XH ₂ O, wherein X represents the amount of water contained in the water glass) and the organic solvent, H ⁺ ion concentration is It is much smaller than water and therefore the solubility of water glass is also small. For this reason, for example, gelation to form a three-dimensional silica network by dehydration of the hydroxy period bonded to silicon at a high H ⁺ ion concentration when acid is added to the water glass does not develop well, and only a portion thereof proceeds. Therefore, some of the water glass in the organic gel is in the form of the original high viscosity water glass, and some of the water glass is in the form of a wet gel which is a viscous three-dimensional network structure formed when acid is added to the water glass. As such, since the water glass in the organic gel is mixed in the original water glass state and the wet gel state, the organic gel has a high viscosity inherent in the water glass and a viscosity of about the middle of the wet gel. Thus, by using a plastic mixture containing an organic solvent, a ceramic fired body having a more uniform and smaller number of pores evenly formed is obtained.

In addition, the Na component in the organic gel serves to lower the sintering temperature of the inorganic additive during the firing process, and thus serves as a crosslinking role to easily bond the inorganic materials at a lower temperature.

On the other hand, the smaller the polarity of the organic solvent, the smaller the ion concentration of H ⁺ , and thus, the lower the solubility of water glass (Na ₂ O? SiO ₂ ? XH ₂ O). Compared to the organic gel using this large organic solvent, not only has a large viscosity but also a large portion of the water present in the water glass and the organic gel is replaced by the organic solvent.

In fact, a large number of large pores are formed in the plastic foam of the organic gel using acetone having a small polarity among the plastic foams of the organic gel in which acetone, ethanol and methanol (polarity: acetone <ethanol <methanol) are used as organic solvents. The smallest amount of pores is produced in the plastic foam of the organic gel using methanol. For reference, calcined foams of an organic gel in which acetone, ethanol or methanol organic solvent and water glass of FIG. 3 are mixed in a 2: 1 weight ratio (calcination condition 500 ° C., 2 hours), as shown in the photograph, calcined foams using acetone (3 The largest pores were formed in), and relatively small pores were formed in the plastic foam 1 of FIG. 3 using methanol having a lower viscosity due to a large dissociation of Na ₂ O components. In the calcined foam (2) using ethanol, medium pores were formed. This result is consistent with the fact that the larger the viscosity, the larger the pores.

As such, the ceramic porous body formed of the calcined mixture further comprising an organic solvent has a viscosity more suitable for forming a ceramic calcined body having more uniform pores and excellent strength. In addition, by using a plastic mixture containing an organic solvent, organic components of the organic solvent are uniformly adsorbed to many micropores of the airgel, and thus act as a pore agent, so that pores are more uniformly generated in the ceramic porous body, thereby providing excellent insulation and ultra-light weight. The ceramic porous body shown can be manufactured.

Thus, in another embodiment of the present invention, a ceramic porous body is provided using a firing mixture comprising water glass, an airgel inorganic additive, and an optional organic solvent. In still another aspect of the present invention, there is provided a ceramic porous body using a calcined mixture containing an inorganic additive and an organic solvent including water glass, airgel and other inorganic materials.

On the other hand, the organic gel formed by the reaction of water glass and the organic solvent is difficult to be mixed with other components because of the fluidity in the form of jelly. In particular, the aerogel is a material having a very small specific gravity, so it is not uniformly mixed with the organic gel. Therefore, in the case where the organic solvent is further blended with the calcined mixture, it is preferable to blend the organic solvent with the airgel and any inorganic material, and then add water glass.

In addition, when a hydrophobized airgel is used, the organic solvent and the airgel are first blended, so that the organic solvent is adsorbed on the surface of the airgel, and the airgel becomes polar to some extent. As such, the water glass and the airgel may be relatively easily mixed by blending the airgel and the water glass in a state where the surface of the airgel is somewhat polar. On the other hand, after mixing an organic solvent and an inorganic additive (aerogel and any inorganic material), and then adding water glass to the mixture, the organic solvent adsorbed on the surface of the water glass and the airgel reacts to form an organic gel. However, since the degree of formation of the organic gel is insignificant and the organic solvent and the airgel are first mixed, the airgel, water glass, any inorganic material, and the organic solvent may be uniformly mixed.

The organic solvent is preferably used in a small amount as much as possible so that the inorganic additive, specifically, the airgel and the inorganic additive which is any inorganic material can be wetted. This is not only economically, if a large amount of the organic solvent is used, it is difficult to obtain a silica porous body in which the organic gel is locally formed by the reaction of the excess organic solvent and water glass, thereby uniformly present in the aerogel. More specifically, the organic solvent is not limited thereto, but the organic solvent is more preferably blended in an amount of 1: 2-1: 7 by weight ratio of an inorganic additive (aerogel and an optional inorganic material): organic solvent. The organic solvent acts as a pore agent when foaming by firing the plastic mixture. If the amount of the organic solvent is less than the lower limit, the organic solvent is not evenly adsorbed to the entire inorganic additive, the organic solvent is present only in a part of the inorganic additive, This is because the distribution of pores in the ceramic porous body may be non-uniform due to the non-uniform presence of such an organic solvent.

On the other hand, if the content of the organic solvent is higher than the upper limit, as described above, the organic solvent adsorbed on the surface of the inorganic additive and the remaining organic solvent is reacted with the water glass to be mixed later is not preferable because a large amount of organic gel is locally formed. That is, since a large amount of organic gel is formed locally without forming a uniform organic gel on the surface of the inorganic additive, it is difficult to obtain a plastic foam in which uniform pores are formed. That is, in order to obtain a plastic foam in which uniform pores are formed, a uniform organic gel should be formed on the surface of the inorganic mixture.

Water glass is foamed by shaping and calcining the calcined mixture into a desired shape to obtain a ceramic porous body which is a super lightweight, super thermally calcined foam. As used herein, the term “desired shape” refers to the shape of any ceramic foam that is finally desired, and the person skilled in the art does not particularly limit the shape of the molded product because it can be molded into any shape as needed.

It is preferable to perform baking at the baking temperature of 120-800 degreeC. If the firing temperature is less than 120 ℃ calcination time is long and the strength of the ceramic porous body is weakened, if the firing temperature exceeds 800 ℃ unnecessary energy cost is required and the fine pores are aggregated by sintering. On the other hand, as the firing temperature increases, the strength of the ceramic porous body increases, but the ultra-lightness and ultra-thermal insulation are inferior. Therefore, in consideration of the physical properties of the final ceramic porous body, the firing temperature can be adjusted to suitably control in the firing temperature range described above.

On the other hand, the hydrophobization compound used in the hydrophobization treatment of the airgel is generally started to decompose at 200 to 250 ℃. Therefore, in the case where hydrophobization airgel is used, in order to maintain the hydrophobicity of the airgel and the ceramic porous body prepared using the same, preferably at a temperature of 180 ° C to 250 ° C, more preferably 180 ° C to 200 ° C It is good to fire.

Firing may be performed for about 10 minutes to 2 hours in the firing temperature range. If the firing time is less than 10 minutes, it is difficult to form a foamable ceramic porous body because it is not sufficiently foamed. The firing time is about 2 hours, so that the foam is sufficiently foamed to obtain a ceramic porous body. On the other hand, in general, a lower firing temperature requires a longer firing time.

The ceramic porous body which is the plastic foam according to the present invention is not only uniformly distributed small and uniform pores formed by the foaming of the water glass, but also fine pores inherent in the airgel is also uniformly mixed, so that heat transfer is effectively blocked by air convection in the pores. It shows excellent super insulation and ultra lightness.

As described above, a fired mixture is prepared by blending water glass, aerogel, any inorganic material, and any organic solvent and firing the same, thereby obtaining a super-insulating and ultra-light ceramic porous body. The ceramic porous body according to the present invention is a breakthrough ultra-light ceramic porous body whose weight is about twice that of styrofoam, and exhibits excellent heat insulation and sound insulation effects. In addition, it exhibits excellent heat resistance, exhibits heat insulation and fire protection even at a high temperature of 1000 ° C. or higher, and does not generate toxic gases in case of fire and further has hydrophobicity. The ceramic porous body of the present invention can be applied to various fields as advanced materials to meet the weight reduction and energy saving functions of new materials. Specifically, it can be applied to technical fields requiring thermal insulation, such as refrigerated warehouses and double insulation panels, building interior insulation materials, soundproof panels, pipe insulation materials, ship interior materials, plastic furnace and melting furnace insulation, and home appliance insulation materials. have.

Hereinafter, the present invention will be described in more detail with reference to Examples. The following examples are intended to illustrate the invention and are not intended to limit the invention.

Example 1

Hydrogel hydrophobized to 100 g of water glass with a concentration of 17 wt% SiO ₂ (NEB-217 ^TM (NV's hydrophobic silica airgel powder, density 0.05 ~ 0.3g / ml, thermal conductivity 5 ~ 30mW / mK, particle size 10 ~) 100 µm) 50 g was added and mixed with stirring to prepare a fired mixture, and the fired mixture was formed into circular spheres of various sizes and fired at 200 ° C. for 30 minutes to obtain a white ceramic porous body. The prepared ceramic porous body exhibited ultralightness of specific gravity 0.117 g / cm ³ and excellent thermal insulation of 29 mW / mk, while the ceramic porous body prepared in the present embodiment was shown in FIG. Water repellency was shown, from which it could be confirmed that the hydrophobicity.

Comparative Example 1

50 g of silica powder (particle size 250 mesh) was added to 100 g of water glass having a concentration of 17 wt% SiO ₂ and mixed with stirring, but it became a slurry like a thin porridge with a very low viscosity so that it could not be molded. Thus, a calcined mixture was prepared by adding 150 g of silica powder (particle size 250 mesh) to 100 g of 17 wt% SiO ₂ concentration water glass and mixing with stirring. The calcined mixture was formed into round spheres of various sizes and calcined at 200 ° C. for 30 minutes to produce a ceramic mixture. Porous body was prepared. The photograph of the manufactured ceramic porous body is shown in FIG. Meanwhile, the cross section of the manufactured ceramic porous body is shown in FIG. 7, and as shown in FIG. 7, dense pores are formed. On the other hand, the specific gravity of the ceramic porous body prepared in Comparative Example 1 was 0.754 g / cm ³ , which showed a larger specific gravity than the ceramic porous body of Example 1. The heat transfer rate was also 74 mW / mk, indicating poor thermal insulation compared to the ceramic porous body of Example 1. On the other hand, the ceramic porous body of Comparative Example 1 did not show hydrophobicity.

Comparative Example 2

Hydrogel hydrophobized to 450 g of water glass with a concentration of 17 wt% SiO ₂ (NEB-217 ^TM (NV's hydrophobic silica airgel powder, density 0.05 ~ 0.3g / ml, thermal conductivity 5 ~ 30mW / mK, particle size 10 ~) 100 µm) 50 g was added and mixed with stirring to prepare a calcined mixture The calcined mixture was shaped into various pancake shapes and calcined at 200 ° C. for 30 minutes to form a ceramic porous body, and a photograph thereof is shown in FIG. The ceramic porous body produced was very irregular and large pores were formed due to the excessive amount of water glass, and some of the water glass was unevenly consolidated and hardened, which is unsuitable for commercialization.

Comparative Example 3

50 g of diatomaceous earth powder (particle size 250 mesh) was added to 450 g of water glass having a concentration of 17 wt% SiO ₂ to prepare a sintered mixture. However, unlike Example 1, stirring was difficult due to the high viscosity of the water glass and diatomaceous earth powder mixture. The calcined mixture was molded into a sphere and calcined at 200 ° C. for 30 minutes to prepare a ceramic porous body. The cross section of the obtained ceramic porous body was very dense, exhibiting a light weight and / or poor thermal insulation, and a photograph thereof is shown in FIG. 9. On the other hand, the specific gravity of the ceramic porous body prepared in Comparative Example 3 is 0.54 g / cm ³ has a larger specific gravity than the ceramic porous body of Example 1. The heat transfer rate was also 67 mW / mk showed low thermal insulation. On the other hand, the ceramic porous body of Comparative Example 3 did not show hydrophobicity.

Comparative Example 4

50 g of ocher powder (Cosera Co., Ltd., ocher powder, particle size 150 mesh) was added to 100 g of water glass having a concentration of 17 wt% SiO ₂ and mixed with stirring. And more 100 g of ocher powder had to be added. Therefore, 150 g of ocher powder (Cosera Co., Ltd., ocher powder, particle size 150mesh) was added to 100 g of 17 wt% water glass, and mixed with stirring to prepare a plastic mixture, which was formed into circular spheres of various sizes and formed at 200 ° C. Firing for 30 minutes to prepare a ceramic porous body. A cross-sectional photograph of the ceramic porous body manufactured in Comparative Example 4 is shown in FIG. 10. As can be seen in Figure 10, a very large pores were formed in the ceramic porous body prepared in Comparative Example 4, it was confirmed that the heat insulation is poor from this. In addition, the specific gravity of the ceramic porous body is 0.5117 g / cm ³ and has a larger specific gravity than the ceramic porous body of Example 1. The heat transfer rate was also 78 mW / mk showed low thermal insulation. The ceramic porous body of Comparative Example 4 did not show hydrophobicity.

Example 2

Hydrogel hydrophobized to 100 g of water glass with a concentration of 17 wt% SiO ₂ (NEB-217 ^TM (NV's hydrophobic silica airgel powder, density 0.05 ~ 0.3g / ml, thermal conductivity 5 ~ 30mW / mK, particle size 10 ~) 100 μm) 50 g was added and mixed with stirring to prepare a fired mixture, and the fired mixture was formed into circular spheres of various sizes and fired at 600 ° C. for 20 minutes to prepare a ceramic porous body. The prepared ceramic porous body showed very light insulation with a specific gravity of 0.121 g / cm ³ and a very good thermal insulation of 31 mW / mk, but the porous body did not show hydrophobicity due to high temperature firing at 600 ° C. Was grayish white because the hydrophobization agent that had been coated on the surface of the airgel was oxidized at high temperatures.

Example 3

Addition of ethanol to 100g of hydrophobic airgel powder (NEB-217 ^TM ((Note) Yep hydrophobic silica airgel powder of a density of 0.05 ~ 0.3g / ml, a thermal conductivity 5 ~ 30mW / mK, particle size 10 ~ 100㎛) 50g and The mixture was mixed with stirring to prepare a mixture of airgel powder and ethanol, and then, 140 g of water glass having a concentration of 17 wt% SiO ₂ was slowly added to the mixture, followed by stirring and mixing to prepare a fired mixture. The ceramic porous body was prepared by molding into a spherical shape and firing for 60 minutes at 150 ° C. The ceramic porous body obtained in Example 3 exhibited very excellent thermal insulation with a specific gravity of 0.109 g / cm ³ and a heat transfer rate of 28 mW / m. On the other hand, the ceramic porous body prepared in Example 3, when floated on the water, as shown in Figure 12, was kept floating on the water without absorbing any water, From there you can see the hydrophobicity.

Example 4

The addition of the hydrophobic airgel powder (NEB-217 ^TM, (state) of the hydrophobic silica airgel powder Yep, density 0.05 ~ 0.3g / ml, a thermal conductivity 5 ~ 30mW / mK, particle size 10 ~ 100㎛) ethanol and 100g in 50g Stirring and mixing to prepare a mixture of airgel powder and ethanol. Thereafter, 150 g of water glass having a concentration of 17 wt% SiO ₂ was slowly added to the mixture, followed by stirring and mixing to prepare a fired mixture. The plastic mixture was molded into circular spheres of various sizes and fired at 600 ° C. for 15 minutes to prepare a ceramic porous body, and a photograph thereof is shown in FIG. 13. The prepared ceramic porous body exhibited very light insulation with a specific gravity of 0.115 g / cm ³ and a very good thermal insulation of 30 mW / mk. However, the ceramic porous body did not show hydrophobicity due to high temperature firing at 600 ° C., and the color was grayish white. This is because the hydrophobization surface treatment agent of the surface of the airgel is oxidized at a high temperature.

Example 5

Hydrogel hydrophobized to 100 g of water glass with a concentration of 17 wt% SiO ₂ (NEB-217 ^TM , hydrophobic silica airgel powder of Nep, density 0.05 ~ 0.3g / ml, thermal conductivity 5 ~ 30mW / mK, particle size 10 ~ 100 μm) and 50 g of diatomaceous earth powder were added and mixed to prepare a calcined mixture. The calcined mixture was molded into circular spheres of various sizes and calcined at 200 ° C. for 30 minutes to prepare a ceramic porous body. The prepared ceramic porous body exhibited very light insulation with a specific gravity of 0.207 g / cm ³ and excellent heat insulation of 34 mW / mk of heat transfer rate. Furthermore, the prepared ceramic porous body was confirmed to be hydrophobic as showing water repellency as shown in FIG. 14. In addition, it was confirmed that dense pores were formed from the cross-section of the ceramic porous body with a knife.

Example 6

Hydrogel hydrophobized to 100 g of water glass with a concentration of 17 wt% SiO ₂ (NEB-217 ^TM , hydrophobic silica airgel powder of Nep Co., Ltd., density 0.05 ~ 0.3g / ml, thermal conductivity 5 ~ 30mW / mK, particle size 10 ~ 100 μm) 50 g and ocher powder (Corcera Co., Ltd., ocher powder, particle size 150 mesh) were added and mixed with stirring to prepare a sintered mixture. The calcined mixture was molded into circular spheres of various sizes and calcined at 200 ° C. for 30 minutes to prepare a ceramic porous body. The prepared ceramic porous body exhibited very excellent thermal insulation with an ultra-lightness of 0.191 g / cm ³ and a heat transfer rate of 33 mW / mk. In addition, the ceramic porous body was floated on the water as shown in FIG. 15, and it was confirmed that the ceramic porous body was shown therefrom. In addition, it was confirmed that irregular pores were formed from the cross-section of the ceramic porous body with a knife.

1 is a photograph of a ceramic porous body of low viscosity water glass,

2 is a photograph of a ceramic porous body of high viscosity water glass,

3 is a photograph of a plastic foam foamed with an organic gel in which water glass (KS standard 3 kinds) and an organic solvent are mixed;

4 is a photograph of a ceramic porous body prepared in Example 1,

5 is a photograph showing that the porous ceramic body prepared in Example 1 is hydrophobic,

6 is a photograph of a ceramic porous body prepared in Comparative Example 1,

7 is a cross-sectional photograph of a ceramic porous body prepared in Comparative Example 1,

8 is a photograph of a ceramic porous body prepared in Comparative Example 2,

9 is a cross-sectional photograph of a ceramic porous body prepared in Comparative Example 3,

10 is a cross-sectional photograph of a ceramic porous body prepared in Comparative Example 4,

11 is a photograph of a ceramic porous body prepared in Example 2,

12 is a photograph showing that the porous ceramic body prepared in Example 3 is hydrophobic,

13 is a photograph of a ceramic porous body prepared in Example 4,

14 is a photograph showing that the porous ceramic body prepared in Example 5 is hydrophobic,

15 is a photograph showing that the ceramic porous body prepared in Example 6 is hydrophobic.

Claims (16)

A ceramic porous body which is a plastic foam of a plastic mixture in which water glass and an airgel as an inorganic additive are mixed in a weight ratio of 2: 1 to 8: 1. The ceramic porous body according to claim 1, wherein the water glass is selected from the group consisting of one, two, three and four water glasses according to KS standards. The ceramic porous body of claim 1, wherein the water glass has a SiO ₂ content of 7 to 30 wt%. The ceramic porous body of claim 1, wherein the inorganic additive further comprises at least one inorganic material selected from the group consisting of ocher powder, mica, talc, silica, diatomaceous earth, titania, pearlite and activated carbon in addition to the airgel. 5. The ceramic porous body according to claim 4, wherein the inorganic additive comprises the airgel and the inorganic material in a 1:10 weight ratio or less. The ceramic porous body according to any one of claims 1 to 5, wherein the calcined mixture further comprises an organic solvent selected from the group consisting of methanol, ethanol, propanol and acetone. 7. The ceramic porous body according to claim 6, wherein the amount of the organic solvent is 1: 2 to 1: 7 by weight ratio of the inorganic additive: organic solvent. Preparing a fired mixture by mixing the water glass with the airgel as an inorganic additive in a 2: 1 to 8: 1 weight ratio; And Forming the plastic mixture into a desired shape and baking for 10 minutes to 2 hours at a baking temperature of 120 to 800 ℃. 9. The method of claim 8, wherein the water glass is selected from the group consisting of one, two, three, and four water glasses according to KS standards. 9. The method of claim 8, wherein the water glass has a SiO ₂ content of 7 to 30% by weight. The method of claim 8, wherein the inorganic additives in addition to the airgel, at least one inorganic material selected from the group consisting of ocher powder, mica, talc, titania, silica, diatomaceous earth, pearlite and activated carbon further comprises a ceramic porous body Way. 12. The method of claim 11, wherein the inorganic additive comprises the airgel and the inorganic material in a 1:10 weight ratio or less. The method of claim 8, wherein the calcined mixture further comprises an organic solvent selected from the group consisting of methanol, ethanol, propanol and acetone. 15. The ceramic according to claim 13, wherein when the calcined mixture contains an organic solvent, the inorganic additive and the organic solvent are mixed first, and then water glass is added to the mixture of the inorganic additive and the organic solvent and mixed. Porous body manufacturing method. The method of claim 13, wherein the amount of the organic solvent is 1: 2 to 1: 7 by weight ratio of the inorganic additive: organic solvent. The method of claim 8, wherein the firing temperature is a ceramic porous body manufacturing method, characterized in that 120 to 250 ℃.

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