KR20010061337A - Method for manufacturing lightweight heat insulating forming glass by direct forming - Google Patents

Abstract

PURPOSE: A manufacturing method of foamed glass for light weight heat-insulating materials by direct foaming of waste glass(alkaline alumino-silicate) without pre- processing such as melting and hydrolysis. The resultant foamed glass is excellent in flame-shield, heat-insulation and sound-absorption. CONSTITUTION: The method comprises the steps of: mixing 75-98wt.% of waste glass ground to the size having 3000-50000cm2/g of surface area with 2-25wt.% of additives composed of 0.1-10.0wt.% of sodium silicate, 0.1-3.5wt.% of C having 40-500m2/g, 0.1-5.5wt.% of sulfate, 0.5-20.0wt.% of active silica and 0.1-10.0wt.% of boric oxide; grinding the mixed powder to be -150mesh; putting it into a mold; heating to 400-700deg.C and foaming at 750-900deg.C; settling at 500-700deg.C and annealing to 20-40deg.C. The resultant foamed glass has 0.14-0.45g/cm3 of density, 0.039-0.053 kcal/hmdeg,C and less than 1.0% of water absorption.

Description

Method for manufacturing lightweight heat insulating foamed glass by direct foaming of waste glass {Method for manufacturing lightweight heat insulating forming glass by direct forming}

The present invention relates to a method for producing foam glass, and more particularly, to a method for manufacturing foam glass for lightweight insulation by directly foaming waste glass without pretreatment such as melting or hydrolysis.

An object of the present invention is to directly foam various kinds of waste glass for commercial or industrial use without having to go through special treatment process such as melting step or hydrolysis step in manufacturing foamed glass for light insulation material and density 0.14-0.45g / cm ³ The thermal conductivity is 0.039-0.053㎉ / hm ℃, and the moisture absorption of less than 1.0%, to manufacture a foam glass block for lightweight insulation that can withstand mechanical stress of more than 0.5 MPa.

Foam glass blocks are lightweight and have excellent performance in flame protection, heat insulation, heat resistance, soundproofing, etc., and are used when industrial waterproof, heat resistance, and durability are required. Especially, they are used as excellent thermal insulation and soundproofing materials in structures and buildings.

The production principle of foam glass was already proposed in the late 1930s. In brief, a glass of special composition is mixed with a reducing agent, such as a carbonaceous material, and a bubble former containing an oxide, sulfate, or other type of oxidizing component together and pulverized, and then the pulverized mixture is mixed in a constant container or Place in a mold and fire until softened or melted. During this heat treatment, an oxidation-reduction reaction occurs between carbon and sulfur oxides (or oxidants or oxides of glass), resulting in molten glass containing SO ₂ , CO ₂ , N ₂ , H ₂ S or other gases. It forms a glass gas that makes materials that form low density and resists heat conduction and radiation. As a result, for best results, the structure of the glass has a closed pore free of water, water vapor, or other liquids and gases.

According to such a manufacturing principle, many research results and related patents have been proposed for the manufacturing process of the foam glass block, and there is already a completed production plant. 1 is a manufacturing process of foam glass commercialized by Pittsburg Corning (USA). As shown in this process chart, in order to manufacture foamed glass, raw material glass for producing foamed glass having a special composition should be manufactured. To this end, various components such as Na ₂ SO ₄ , CaCO ₃ , MgCO ₃ , Na ₂ O, As ₂ O _3, etc. are added to the raw material for manufacturing glass to form foamed glass, followed by melting at 1300 to 1600 ° C. We are making raw glass for making foamed glass that can make glass. The glass thus prepared is pulverized and mixed well by adding carbon foaming aid, and then the mixed raw glass powder for foamed glass manufacturing is placed in a predetermined container, preheated at 400 to 650 ^o C and foamed under the conditions of 800 to 900 ^o C. After passing through the heat treatment process such as cooling, slow cooling for stabilization to cut to a certain size and sells packaging.

However, this process requires a large amount of energy of 1300 ~ 1600 ℃ in the process of making the raw glass for foam glass manufacturing, as well as the facility investment and management costs accordingly, the production cost of the raw glass for foam glass production is foamed It accounts for more than half of the glass production cost. In addition, the generation of a large amount of fructose foam glass (which occurs up to 20wt%), which is derived when cutting the manufactured foam glass to a certain size, is another major factor that does not lower the production cost of the foam glass block. For this reason, many of the patents and researches that have been proposed regarding the improvement of the foam glass manufacturing process since the operation of the existing Pittsburgh Corning foam glass manufacturing plant are mostly aimed at the process that requires high energy before the foaming step. The focus is on making raw glass for the manufacture of foamed glass directly.

For example, Japanese Unexamined Patent Publication No. 59-116,151, as one of the solutions to solve the problems of the existing process is to foam the glass by hydrolysis of the glass in the following reaction by alkaline solution and vaporize the water involved in the reaction in the foaming process It shows how to get the glass.

As taught in Japanese Laid-Open Patent Publication No. 59-116,151, foamed glass having an apparent specific gravity of 0.4 to 0.5 can be easily produced by adding carbon as a foaming aid to a glass hydrolyzed by an aqueous alkali solution. However, according to the method of Japanese Patent Laid-Open No. 59-116,151, the density of foamed glass, that is, foamed glass, that is currently commercially available as a heat insulating material, 0.3 g / cm ³ (apparent specific gravity 0.3 or less, thermal conductivity 0.05 Kcal / hm ^o C or less) It is not possible to manufacture foamed glass having the same, and when the glass hydrolyzed using alkaline aqueous solution is used as a raw glass for producing foamed glass, the fifth process mentioned in Japanese Patent Laid-Open No. 59-116,151, namely Alkaline components introduced into the glass by hydrolysis during the foaming process at 850 ~ 1000 ℃ are released in vapor state with the generation of water, so the thermal insulation material in the foam furnace under high temperature is greatly corroded and damaged by alkaline components. There is a fatal problem.

In connection with this problem of Japanese Patent Application Laid-Open No. 59-116,151, the present applicant is required to apply certain heating pressurization conditions without using alkali in Korean Patent Application No. 97-53852 (1999 Patent No. 246755) dated October 20, 1997. In the following, a process for producing a foamed glass using a glass that has undergone hydrolysis reaction using only moisture was proposed. As a result, it is light and has a uniform pore diameter, which is never obtained through Japanese Patent Laid-Open Publication No. 59-116,151 ( the thermal conductivity of the commercially available foamed glass that is low thermal conductivity (with an apparent specific gravity of 0.3 or less) also: 0.05 Kcal / hm ^o C or less, even standard thermal conductivity as the insulating insulation: 0.1Kcal / hm ^o C or less) to produce a good quality of the foam glass having a performance Could.

By the way, the process using the hydrolysis has a great advantage to solve the problem of the foamed glass manufacturing process using the existing high energy, but it is inevitable that additional processes associated with a separate reaction device for the hydrolysis reaction is required. Therefore, the process of manufacturing foamed glass having low density and low thermal conductivity, which is a characteristic of foamed glass, by directly foaming the waste glass itself without the additional process of hydrolysis and without the high temperature melting process for the production of raw glass. Development is the ultimate goal of the foam glass business.

In the process for manufacturing foamed glass by direct foaming of glass powder without any pretreatment process, various types of methods were proposed in US Patent No. 2,123,536 in 1938, when research on manufacturing foamed glass began. From US Patent No. 2,775,524 on March 25 to 1996 US Patent No. 5,516,351 has been proposed. However, the important point is not that the glass can be foamed to form simply foamed glass, but the resultant foamed glass should be foamed glass with the characteristics of lightweight insulation, that is, low density and low thermal conductivity and also high mechanical strength performance. Is that.

Looking more specifically at these prior arts, U.S. Patent No. 2,775,524, issued Dec. 25, 1956, formed of a material such as silica or diatomaceous earth containing 5-50 wt% carbon and having a specific surface area of 10 m ² / g. It is proposed to manufacture foamed glass by adding 0.08-0.15wt% of carbon black to glass and softening and foaming the glass at a certain temperature, and then cooling and slow cooling annealing. There is no mention of the physical properties. This manufacturing method uses a gas produced by redox reactions such as carbon and arsenic (Stibium), vanadium (Vanadium), molybdenum (Molibdene), tungsten (Tungsten). In fact, it is not suitable to produce high quality foam glass with low density as the oxidant to produce SO ₃ (or SO ₂ ).

In addition, the method of manufacturing a foamed glass block proposed in US Patent No. 5,516,351 of May 14, 1996 is crushed glass, added a large amount of foaming aids such as CaCO ₃ or CaSO ₄ and mixed well, and then put into a mold and preheated and calcined. In this case, the foamed glass is produced by SO _x or CO _x produced, and cooled and annealed. This method uses a variety of different types of glass. This method uses a chemical component to produce a foamed glass by trapping the gas produced by chemical reaction with the glass in closed pores. The foamed glass obtained in this process has the disadvantage that its bulk density, heat insulation, mechanical properties, and properties as heat insulators deteriorate very rapidly in the presence of moisture. In addition, the use of SO _x and CO _x gas increases the production cost and worsens the atmospheric environment has a high cost of the collection, worsening the workplace environment caused by the gas generation, there is a high risk of human injury.

The present invention is to recover the various types of waste glass, such as window glass, white bottle, green bottle, brown bottle, medicine bottle, pesticide bottle without any distinction or distinction, excluding the melting process for producing a glass of a special composition and the above problems are The present invention relates to a method for producing a lightweight foam glass having a density of 0.15-0.45 g / cm ³ having a high thermal insulation effect of 0.039-0.053 Pa / hm ° C. by introducing a material having an oxidizing agent or another compound composition.

The invention to be realized is to produce foamed glass having excellent properties from various kinds of waste glass which are not classified or classified without melting the glass.

The quality and characteristics of foamed glass blocks depend on their density, bubble distribution and size, bubble wall thickness, and water absorption. In other words, defects that deteriorate the quality of the foam glass include differences in the size of the bubbles in the foam glass block, inhomogeneity in the block portion, increase in bubble wall thickness, high density, the presence of residual glass stress, reduction in mechanical durability, and permeability of the foam. Excessive presence, high intake rate of water or bubbles, etc.

The present invention relates to the production of foamed glass insulation of efficient function with low density and low thermal conductivity. Process for producing lightweight foamed glass insulation which can utilize waste glass from municipal waste or waste glass from industrial waste as raw glass and does not require melting, hydrolysis or any other pre-processing of glass to make a special composition The purpose is to provide.

Figure 1 is a foam glass manufacturing process chart used by Pittsburg Corning (USA).

The present invention is directed to various types of alkali alkaline alumino-slicate glasses, which do not melt these glasses and provide desired properties by oxidation-reduction reactions involving the formation and separation of bubbles in a softened state. It is a manufacturing method of high quality foam glass.

In the method for producing lightweight foamed glass according to the present invention, the waste glass is ground to have a specific surface area of 3,000 to 50,000 cm ² / g, and 75 to 98 wt% of the ground waste glass powder is mixed with an additive of 2 to 25 wt%. As an additive, 0.1-10.0 wt% of sodium silicate, 0.1-3.5 wt% of carbon having a specific surface area of 40-500 m ² / g, 0.1-5.5 wt% of sulfate, 0.5- of active silica 20.0 wt% and boric oxide 0.1-10.0 wt%. The glass and the additive may be mixed together and crushed to -150mesh or the additive may be added to the crushed glass and mixed homogeneously. This mixed powder is placed in a mold and calcined to 400 to 700 ^° C. and foamed at 750 to 900 ^° C. After the foaming process, the foamed glass block is stabilized at 500 ^~ 700 ^o C and then annealed up to 20 ^~ 40 ^o C.

The present invention is applicable to all kinds of waste glass such as various kinds of glass, ie, green bottle, brown bottle, transparent bottle, pharmaceutical bottle, pesticide bottle, and window glass, and when applied separately to each individual glass bottle, It is possible to manufacture foamed glass blocks However, the application to each individual glass is not economically effective considering the process of collecting and recovering waste glass. Therefore, in consideration of the physical and chemical properties of the glass and the technical characteristics of the process, it is desirable to recover and apply the classification in a wide form.

To this end, there are three separate collection and recovery methods currently adopting waste glass, namely, green or glass bottles such as soju bottles as the first group, brownish jam bottles such as beer bottles, pesticide bottles and pharmaceutical bottles as the second group, As a third group, it is preferable to apply this process by classifying transparent waste glass such as window glass and transparent bottle.

First, the waste glass should be pulverized. At this time, the powder is pulverized to have a specific surface area of 3,000 to 50,000 cm ² / g. If the specific surface area of crushed glass powder is less than 3,000cm ² / g there are required more than 0.35wt% of the added amount of carbon foam preparation increases the sintering temperature is also above all, as well as high density in 860~950 ^o C of the foaming process weight Inhibits. The finer the fineness of the waste glass is, the better it is preferably up to 50,000 cm ² / g considering the economical degree of grinding. When the glass powder has a specific surface area of 3000 to 50,000 cm ² / g, the amount of carbon, which is a foaming aid, can be added at 0.05 to 0.35 wt%, and the temperature conditions of the foaming process are also lowered to 750 to 850 ^o C. In addition, the density of the foam glass is also lowered and the moisture absorption rate is also lowered.

0.1 to 5.5 wt% of sodium silicate added as a foaming aid causes an oxidation-reduction reaction with carbon accompanied with the production of SOx, COx, N ₂ and H ₂ S gases required for the foaming process. Therefore, as the amount of the oxidant is increased, the size of the foamed glass block also increases (density decrease). Therefore, when the addition amount is 0.1wt% or less, it is difficult to manufacture foamed glass having a low density of 0.2g / cm ³ or less. However, in the case of more than 5.5wt%, since the reaction amount with carbon such as combustion of carbon increases, many open pores are formed in the foam glass block, and as a result, the water absorption of the foam glass is increased.

Carbon, which is a foaming aid, is added with 0.15 to 3.5 wt% of carbon having a specific surface area of 40 to 500 m ² / g. Under these conditions, the foamed glass will form predominantly and completely independent pores smaller than 30-300 μm. The use of carbon with a specific surface area of 40 m ² / g or less reduces the efficiency of the redox reactions involving the production of gases which must be accompanied in the glass to produce foamed glass, resulting in foamed glass with high density. do. On the other hand, when carbon having a specific surface area of more than 500 m ² / g is used, carbon is burned by the air or gas absorbed before the foaming process, which also reduces the foaming efficiency.

The production mechanism of the foam glass is first melted or softened the surface of the pulverized glass particles, bubbles are generated by the reaction of the foaming aid including carbon present between the glass particles and the foaming of the glass by these gases generated It is going. Therefore, the foaming process temperature for the foaming of the glass must be maintained up to the melting or softening point of the glass. In other words, the molten structure must be formed in the glass particles. The present invention is characterized by forming a molten structure of glass using active silica without foaming temperature conditions reaching the melting or softening point of the glass for foaming the glass. The use of active silica has the function of stabilizing and homogenizing the structure of the glass to reduce or prevent water absorption.

The glass powder can be maintained in a molten state below the softening point by adding 0.1 to 20.0 wt% of active silica using diatomaceous earth, aerosol or silicogel. When the active silica is added below 0.1wt%, it is difficult to stabilize the foamed glass block because the viscosity of the heated part shows relatively large deviation during the formation of the foamed glass block. In this case, the volume of the powder glass itself increases due to the aggregation of glass particles, which also lowers the foaming efficiency.

The use of 0.1 to 10.0 wt% of boric acid as another additive in the foaming aid reduces the thermomechanical strain of the foamed glass blocks in the foaming process, as well as simplifies the thermal stress during slow cooling and annealing, resulting in the final product foaming. It greatly increases the mechanical properties of glass blocks.

Preheating at 400 to 700 ^o C temperature before foaming inhibits the formation of thick shells and the emptying of the glass powder outward. If the preheating temperature is below 400 ^o C, the outward swelling is suppressed, and as a result, the foaming state is badly bad or foaming does not occur. In addition, when the preheating temperature is 700 ^° C. or higher, thermal shocks destroy the densely formed structure of the glass and fragment the foam glass block.

On the other hand, the heating rate before reaching the foaming temperature to form the foamed glass block depends on the material of the container that determines the volume of the foamed glass block.

When the foaming temperature is 700 ^o C or less, the production of foamed glass blocks having a density of 0.15 to 0.45 g / cm ³ of the foamed glass block is suppressed. When the foaming temperature is more than 900 ^o C, pores are lost due to the loss of dense pore walls. Larger sizes and cavities are created, limiting the porous structure of the glass to breakdown of uniformity. As a result, it is difficult to produce high quality foam glass blocks that are economical and practical.

The glass powder in which the foam structure is formed is contained in the container, but since it is in a softened or molten state as a whole, the foam structure must be stabilized by quenching the foamed glass to 500 to 700 ^° C.

When quenching under the condition of 500 ^o C or less, thermal stress that causes cracking or destruction of the foam glass is caused by thermal shock, and when quenching under the temperature condition of 700 ^o C or higher, oxidation to uniformly control the volume of the foamed glass block formed The inhibition of the reduction reaction is limited. Therefore, it may be over-foamed.

The practical application of the process according to the invention can be achieved by the influence of the properties of the foamed glass blocks mentioned in detail, their levels and the technical application of various parameters. The recovered waste glass is pulverized in a grinding apparatus such as a ball mill or a vibratory mill. Active silica, water glass, active carbon black, sulfate, boric oxide can be added together. The recovered glass powder, that is, alkaline alumino-silicate glass powder, can be mixed with these concentration-controlled additives and placed in a container which determines the shape of the actual foamed glass block. The combination and functional sequence of the functional ingredients does not serve as a special variable in the production of high quality foam glass. Containers containing foamed glass raw material powder should be made of materials that can withstand all processes such as furnace for firing, foaming, stabilization of structure, annealing, removal of thermal strain from foamed glass blocks.

<Example 1>

Crush the green bottle glass to a size smaller than 250 microns. The ground glass has a specific target of 14,000 cm ² / g. 76.3 wt% of diatomaceous earth, 2.7 wt% of active carbon black, 5.7 wt% of sulfate and 15.3 wt% of boric oxide are mixed together as a foaming aid in the pulverized glass. At this time, the mixing amount of the foaming aid of the composition with respect to the glass powder is uniformly mixed with the foaming aid 15wt%, hydrated glass powder as 85wt%. To this powder mixture is added 2.5 wt% of dissolved sodium silicate on a dry powder basis, mixed well and placed in a container. A plastic container containing the raw material powder to 550~700 ^o C, pre-heating and combustion ever then foamed at 750~850 ^o C. This is then again stabilized and immobilized at a temperature of 550-650 ^° C. The formed foamed glass is slowly cooled and annealed to a temperature range of 20 to 40 ^° C.

The physical properties of the foamed glass block thus prepared are as follows.

Density 0.186 g / cm ³

-Thermal conductivity (at 20 ^o C) 0.045㎉ / hm ℃

-4.8% of volume water capacity

-Compressive strength 1.45MPa

<Example 2>

Grind the brown bottle glass to 250 μm or less. The specific surface area of the ground glass powder was 15,000 cm ² / g. Foaming aids are prepared by mixing together 76.3 wt% of diatomaceous earth, 2.7 wt% of active carbon black, 5.7 wt% of sulfate and 15.3 wt% of boric oxide. Then, the amount of the foaming aid is adjusted to 20wt% and the hydrated glass powder to 80wt%, and mixed as uniformly as possible. The powder mixture thus mixed is added with 2.5 wt% of dissolved sodium silicate on a dry powder basis and mixed well. The mixed powder is put in a metal container, charged into a furnace, preheated and calcined to 500 to 600 ^° C., and then heated to foam at 800 to 860 ^° C. by combustion. This is then again stabilized and immobilized at a temperature of 520-650 ^° C. The foamed glass is slowly cooled and annealed to a temperature of 20 to 40 ^° C.

The physical properties of the foamed glass block thus prepared are as follows.

Density 0.198 g / cm ³

-Thermal conductivity (based on 20 ^o C) 0.05㎉ / hm ℃

-Volume water capacity 4.9%

-Compressive strength 1.45MPa

<Example 3>

The waste transparent bottle glass was pulverized and mechanically pulverized to have a particle size of 200 μm or less to obtain a glass powder having a specific surface area of 18,000 cm ² / g. Foaming aids are prepared by mixing together 76.3 wt% of diatomaceous earth, 2.7 wt% of active carbon black, 5.7 wt% of sulfate and 15.3 wt% of boric oxide. Then, the amount of the foaming aid is adjusted to 20wt% and the hydrated glass powder to 80wt%, and mixed as uniformly as possible. To this powder mixture, dissolved sodium silicate in an amount of 2.5 wt% based on dry powder is added and mixed well, and then it is put in a metal container. Vessel containing the raw material powder is then expanded by heating to a 550~690 800~870 ^o C ^o to C, and pre-heating and firing combustion ever. This is then again stabilized and immobilized at a temperature of 500 to 660 ^° C. The formed foamed glass is slowly cooled and annealed to a temperature range of 20 to 40 ^° C.

The characteristics of the foamed glass block thus produced are as follows.

Density 0.171 g / cm ³

-Thermal conductivity (at 20 ^o C) 0.042㎉ / hm ℃

-Volume water capacity 4.27%

-Compressive strength 1.02MPa

Foamed glass with low density and low thermal conductivity as a lightweight insulation material is manufactured by directly foaming the powder of glass using chemical components, which eliminates the need for high-temperature melting and hydrolysis processes required by conventional methods. A glass manufacturing process is established.

Claims (1)

A glass grinding step of grinding the waste glass to a specific surface of 3,000 to 50,000 cm ² / g of powder; Sodium silicate 0.1-10.0 wt%, carbon having a specific surface area of 40-500m ² / g 0.1-3.5 wt%, sulfate 0.1-5.5 wt%, active silica 0.5-20.0 wt %, And the additive mixture composition process of boric oxide 0.1-10.0 wt%; Mixing the pulverized waste glass 75-98 wt% and the additive mixture 2-25 wt% to form a homogeneous raw powder mixture; Putting the raw material powder mixture into a foam mold and preheating it to 400 to 700 ^° C. and then foaming at 750 to 900 ^° C. to form a foamed glass block; And Stabilizing the foam glass block at 500 ^~ 700 ^° C and annealing (annealing) to 20 to 40 ^° C Method for producing a lightweight insulation foam glass by direct foaming of the waste glass, characterized in that comprises a.