KR20000050105A - Method of producing foam glass - Google Patents

Abstract

PURPOSE: A process for preparing a foamed glass by heat foaming porous silica gel in a specified shape is provided which gives homogeneous foamed glass having excellent insulating property at a low cost. CONSTITUTION: A process comprises pouring porous silica gel as a foaming agent in a mold, which is prepared using a sol-gel method and calcining at 980 to 1,170°C in a predetermined shape in a tunnel kiln or shuttle kiln to foamed glass having excellent physical properties such as homogeneity and heat insulation. The silica gel is manufactured by treating alkali silicate obtained from the melting of silica dioxide and alkali. The obtained foamed glass comprises pure silica of above 98% and has a large number of fine pores inside particles such that it generates almost no environmental pollution and has excellent insulating property.

Description

Method of producing foam glass

The present invention relates to a method for producing expandable glass, and more particularly, to the provision of a new method for producing expandable glass having high utility value as a heat insulating material for buildings. That is, the present invention relates to a new method for producing foamed glass in the production of foamed glass for thermal insulation or corrosion resistance.

The materials that have been used as a building fireproofing material in the past have been used by mixing cement or other binding materials with rock wool or glass wool and applying them to the surface of steel structures.

But. While this method has high heat resistance and low thermal insulation, the pollution problem is a serious method because rock wool and the like are scattered as fine particles and absorbed by the human body as pollutants.

Therefore, it is a reality that a new structure and heat insulating material have been required.

In view of such a problem, what has emerged in recent years is foam glass, and foam glass refers to glass having a bubble structure in the glass.

Foamed glass has physical properties such as heat insulation, processability, light weight, weather resistance, chemical resistance, etc. due to the physical properties derived from the bubble structure to the original physical properties of the glass.

Foamed glass is also called Dapo glass and Dapochoza, and in English it is called Foam Glass or Multicelluar Glass, which indicates that it can be manufactured as various kinds of materials with a large number of isolated gas spaces inside.

Foamed glass is widely used as the most desirable material for thermal insulation, cold insulation and internal corrosion of petrochemical plants, LNG liquefied gas tank bottoms, refrigerated warehouses, ships, etc., and its production is also increasing.

Typical physical properties of the foamed glass include non-combustibility, chemical resistance, heat insulation, light weight, processability, and the like. Nonflammability and chemical resistance are the original properties of glass, and heat insulation, light weight, and workability are properties resulting from the foaming of glass.

Briefly explaining the manufacturing principle and process of the foam glass from the prior art are as follows.

The glass is pulverized into glass powder, mixed with this glass powder and various kinds of expensive blowing agents, and then molded into a heat-resistant formwork of a certain shape and heated and processed above the softening temperature of the glass to close the gas generated from the blowing agent. Molded.

However, the conventional method described above has a problem that the manufacturing method is cumbersome and it is difficult to guarantee homogeneous foaming.

This is because even if the foam material ejects the gas, it is not discharged homogeneously but occurs inside the locally molten glass, so that uniform foaming over the entire volume is difficult to be guaranteed.

That is, the conventional method for producing the expandable glass;

1) First, the foam is surrounded by softening the glass powder.

2) At this time, the foam material should be in a state where it cannot be contacted with external air by softened glass particles.

3) When this is further heated, the foam material takes oxygen from the oxygen supply component inside the glass and oxidizes it, converting it into a gas and forming waste pores.

Various kinds of expensive blowing agents have been used with the same process.

The present invention is to provide a foamed glass manufacturing method using a porous particle for producing a foamed glass for insulation or corrosion resistant material using a porous gel in order to have a foamed structure for the insulation material has a closed pore structure as a novel method.

The present invention provides a method for producing a homogeneous foam glass using porous particles. The glass composition developed in the present invention produced a porous glass under various conditions, and when fired, it was possible to produce a foamed glass having excellent natural friendly effects such as heat-resistant heat-insulating heat-resistant corrosion-resistant moisture-proof of homogeneous waste pore structure.

1 is a process chart of the method for producing the expandable glass of the present invention.

Figure 2 is an exemplary product photograph molded in the grain state of the foamed glass produced by the method for producing a foamed glass of the present invention.

3 is another exemplary photograph of a block type of foamable glass produced by the method for manufacturing the foamable glass of the present invention.

4 is a low magnification micrograph showing a cross section of the expandable glass produced by the method for producing the expandable glass of the present invention.

Explanation of symbols on the main parts of the drawings

S: silica gel particles

F: formwork

K: tunnel kiln to shuttle kiln

The object of the present invention is to obtain a homogeneous and shaped foamed glass at a low cost as a minimum processing step.

Another object of the present invention is made of pure silica, extremely poor in pollution and has numerous closed fine pores inside the particles, excellent thermal insulation and fine pores inside the silica hollow body, each pore Silver has a very high thermal insulation because it forms a vacuum, so the surface finish of semiconductor equipment and steel ball building. It is to provide a method for producing expandable glass that can be used as a thermal insulation, heat insulation, cold insulation and corrosion resistant materials for petrochemical processes, the bottom surface of the liquefied gas tank, refrigerated warehouse, ships and the like.

The method for producing the expandable glass of the present invention as described above; By using silica gel as the foaming material and suggesting the optimum molding method and conditions, it is useful to obtain foamed glass having excellent physical properties with homogeneous and good thermal insulation.

Method for producing the expandable glass of the present invention to achieve the above object;

In the manufacturing method of the expandable glass having a plurality of fine pores therein; The foamed material is made of only porous silica gel prepared by using a sol-gel method, and foamed to a predetermined shape by heating and foaming the silica gel. The foamed material is heated above the softening temperature of the silica gel to soften the silica gel and at the same time, a porous internal structure. It is characterized in that the gas is expanded to form a micro-pore tissue,

The silica gel is prepared by treating the alkali silicate obtained by melting silicon dioxide and alkali by a conventional sol-gel method, and controlling the ratio of the internal pore surface area and the external surface area to the silica gel according to the acid introduced during the silica gel molding. It is characterized in that the foaming degree can be adjusted differently according to the drying degree.

The manufacturing method of the expandable glass of this invention is demonstrated in detail with accompanying drawing.

1 is a process chart of the manufacturing method of the expandable glass of the present invention, Figure 2 is an exemplary product photo of the expandable glass produced by the manufacturing method of the expandable glass of the present invention, Figure 3 is a manufacturing method of the expandable glass of the present invention Is another exemplary product photograph of the foamable glass produced by the present invention.

The biggest technical feature of the method for producing the expandable glass of the present invention is to employ porous particles as the foam material and to use silica gel as a preferred embodiment of the porous particles.

Silica gel is a porous semi-transparent gel material used as a desiccant by acid-decomposing water glass, and silica gel is a gel of silicic acid having high adsorptive power, and the component is SiO 2 · nH 2 O, and is a colorless or yellowish brown transparent or translucent powder.

In addition, silica gel is applied to remove moisture from the air, to collect benzene from coal gas, and to collect low-boiling hydrocarbons from natural gas.

Silica gel describes water glass silicon that is silicified.

Water glass is a concentrated aqueous solution of alkali silicates obtained by melting silicon dioxide and alkali. It contains 2 to 4 mol of SiO2 in 1 mol of Na2O, and is a colorless, highly viscous liquid that becomes glass when dried in air.

The composition of the water glass is Na2O.SiO2, which is a transparent solution showing viscous alkalinity. The molar ratio of Na2O and SiO2 has various compositions from 1: 1 to 1: 4. Usually, those having n = 2 are referred to as No. 1, those having n = 2.5 are referred to as No. 2, those having n = 3 are referred to as No. 3, and those having n = 4 are referred to as No. 4.

Sodium silicate exists in various forms depending on the bonding ratio of Na2O and SiO2.

There are more than 40 kinds of sodium silicate that is currently commercialized for various uses. Silicates with a ratio of Na2O to SiO2 ranging from 1: 1.6 to 1: 4 are called colloidal silica and a ratio of Na2O to SiO2 of 1: 1 is sodium metasilicate, and the ratio of Na2O to SiO2 is 1.5 1: sesquisilicate (sesqui-silicate), Na 2 O: SiO 2 ratio is 1.5: 1, that is, NaSiO 4 is called ortho-silicate (ortho-silicate).

Silica gel preparation by the reaction of water glass and acid is as follows.

Na2OxSiO2 + H2SO4 → xSiO2 + Na2SO4 + H2O

The manufacturing process of sodium silicate is as follows.

Caustic soda solution and silica sand are mixed in the autoclave, and heated water vapor is blown into it to dissolve. The product is left still, filtered and concentrated as in the dry method.

Silica sol is made of water glass and acid and gelled.The method of adding acid to gel in the mixing method of the two liquids does not form a homogeneous sol even if it is sufficiently stirred. If it becomes homogeneous, hydrated silica is mixed. Another method is to inject water glass and acid into the container at the same time. That is, sodium silicate and H2SO4 are simultaneously injected into a vessel equipped with a high speed stirrer and mixed. At this time, the concentration and amount should be adjusted correctly.

Then, it becomes sol state. If the stirrer is removed and left to stand, the gelation time is different depending on the temperature. In the most important washing step of this manufacturing process, excess acid is removed along with the produced sodium sulfate according to the washing method.

The yield is about 98% of the theoretical amount depending on the method, but since it is 5 to 10% moisture, it is about 90% and it is less than the loss during washing.

Therefore, in the present invention, it is configured by applying silica gel as a preferable foaming material, thereby preparing porous particles (silica gel) prepared by the sol-gel method, and putting it in a heat-resistant formwork of a predetermined shape and heat-treating it above the softening temperature of the glass. At the same time as the softening occurs, the gas in the porous internal tissue expands to form the foamed glass in the closed hole tissue.

Silica gel has an internal pore surface area and an external surface area ratio of about 250,000 times. Therefore, the gas and liquid absorbed therein are heated out to reach the softening temperature, and the pores are surrounded by the surface softening of the silica gel. It is blocked.

In one embodiment, the porous silica sand particles (silica gel) are heated (980-1200 degrees) and processed into granules or block boards.

This manufacturing process is shown in FIG. 1 and described as an example.

Example

The silica gel obtained by melting silicon dioxide and alkali is prepared by a conventional sol-gel method.

(1) The silica gel (S) is exposed to air to absorb an appropriate amount of moisture. At this time, if the amount of water absorbed is increased, foaming is induced a lot, and thus the degree of foaming can be controlled.

(2) A predetermined amount of the silica gel (S) is added to the heat-resistant form (F) to have a shape.

(3) When the formwork is fired at 980 ° C to 1170 ° C using a tunnel kiln or shuttle kiln (K) and heated to a temperature above the softening temperature of the glass, at the same time as the glass is softened, the gas in the porous internal tissue is flattened and discarded. Forms a ball tissue.

(4) As the silica gel is melted by the firing step, foamed glass (FG) is obtained on the principle described above.

The above manufacturing method is that the absorbed from the outside from the original characteristics of the absorbent and the trace amount of carbide remaining inside the raw material does not escape from the molten gel, and when it reaches a specific temperature, it expands and foams.

In this case, the heating time is adjusted so that the surface of the softened gel particles cannot come into contact with external air. When the softening point is reached, the internal air expands rapidly, and when it cools down, the internal pores become vacuum when the external rotor is first cooled. Will have.

That is, a reaction such as the following expression is induced.

SO3 + 2C remaining in the silica gel → S2- + CO (gas) + CO2 (gas)

As2O5 + C → As2O3 + CO2 (gas) in silica gel

In the above formula, SO3 and As2O5 are oxygen supply components present in the glass. SO3 remains as it is absorbed from the combustion gas during melting of the glass and does not escape from the molten glass of various base materials used as the glass material.

In the present invention, it can be used to obtain a homogeneous foam glass.

That is, in the usual manufacturing method of foamable glass which forms a waste hole;

The foamed material is made of porous silica gel ceramic particles, mixed with a glass base material in a heat-resistant formwork, and then fired at 980 ° C to 1170 ° C using tunnel kilns or shuttle kilns, followed by foam molding.

It can be seen that an exemplary molding of the foamed glass produced by the above method is shown in FIG. 2, resulting in a homogeneous foamed glass.

The physical properties of the thus obtained foam glass were measured by ASTM C552-91. As a result, excellent physical properties of density 225 kg / m3, compressive strength 700 kPa, bending strength 500 kPa, water absorption 0.01%, and water vapor permeability 0.003 g / hmmHg · m were obtained. .

Figure 2 is an exemplary product photograph formed in the grain state of the foamed glass produced by the manufacturing method of the foamed glass of the present invention shows that the foamed glass of round and homogeneous pores are molded, Figure 3 is molded in a block shape City,

Figure 4 is a low-magnification micrograph showing the cross section of the foamed glass, showing that the micropores are formed in a myriad of closed fine pores therein, because the glass composition itself is suitable for the production of foamed glass, It is not affected and becomes a very important factor in mass production.

In addition, it is possible to adjust the ratio of the inner pore surface area and the outer surface area to the silica gel according to the doping material such as acid, base, etc. introduced during the molding of the silica gel, and the foaming degree can be adjusted differently according to the drying degree. .

The foamed glass produced by the above-mentioned method is made of pure silica of more than 98%, has very low pollution, and has numerous closed fine pores inside the particles, which is excellent in heat insulation and fine pores with an internal pore surface area inside the hollow silica. Since each pore forms a vacuum, it has the advantage of very high thermal insulation, so that the surface finish of the semiconductor equipment, steel structure building. It provides optimum physical properties as thermal insulation, heat insulation, cold insulation and internal plant material in petrochemical process, bottom of liquefied gas tank, refrigerated warehouse and ship.

The method for producing the expandable glass of the present invention as described above; By using silica gel as the foaming material and suggesting the optimum molding method and conditions, it is useful to obtain foamed glass having excellent physical properties with homogeneous and good thermal insulation.

Claims (3)

In the manufacturing method of the expandable glass having a plurality of fine pores therein; The foam material is made of only porous silica gel prepared using the sol-gel method, By foaming to a predetermined shape by heat foaming the silica gel, Heat-treating at or above the softening temperature of the silica gel to soften the silica gel and at the same time expand the gas in the porous internal tissue to form an ultrafine waste pore structure. In the manufacturing method of the expandable glass having a plurality of fine pores therein; The foam material is made of only porous silica gel prepared using the sol-gel method, By mixing the silica gel into a heat-resistant die, and firing at 980 ℃ to 1170 ℃ as tunnel kiln to shuttle kiln, Heat treatment above the softening temperature of the silica gel and the silica gel is softened and at the same time the gas of the porous internal tissue is expanded to form a fine microporous structure. The method according to claim 1 or 2, The silica gel is prepared by treating the alkali silicate obtained by melting silicon dioxide and alkali by a conventional sol-gel method, Production of foamed glass, characterized in that the ratio of the inner pore surface area and the outer surface area to the silica gel is adjusted according to the dopant such as acid and the like introduced during the silica gel molding, and the foaming degree can be adjusted differently according to the drying degree. Way.