JPH0216252B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing glass foam.

The conventional method for manufacturing glass foam is to place fine glass powder containing a glass foaming agent into a foaming mold, heat it above the softening point of the glass powder, and foam the glass foaming agent by heating to form a glass foam. is manufactured. In this conventional manufacturing method, when the raw material powder is turned into a foam by heating, volumetric expansion occurs within the mold. As a result, the upper corners of the molded product are not formed uniformly, and the mold is deformed, making it difficult to manufacture a glass foam having a constant shape. For this reason, for example, in manufacturing a rectangular parallelepiped-shaped glass foam, a relatively large glass foam is manufactured, and the top and bottom surfaces or side portions of the foam are cut to produce a rectangular parallelepiped-shaped foam. As a result, a large amount of chips were generated, resulting in a problem of poor yield. In addition, in the conventional glass foam production method, a large volume expansion occurs within the mold, which causes distortion in the glass foam, which causes problems such as cracks in the resulting molded product. The point was hot. Further, since the conventional manufacturing method requires a mold, the above-mentioned distortion is particularly large. There was also the problem of oxidation of the mold.

The present invention provides a method for manufacturing a glass foam that does not have the above-mentioned problems. That is, the method for producing a glass foam of the present invention uses a glass foaming agent, a glass powder, and a cell structuring agent, and by causing the cell structuring agent to disappear, there is a large number of foams that absorb the volume expanded by the glass foaming agent. a preforming step of producing a green compact containing air bubbles, and a foaming step of heating the green compact and foaming the glass foaming agent to form a glass foam without significantly changing the external shape of the green compact. It is characterized by consisting of.

In the method for manufacturing a glass foam of the present invention,
A green compact composed of a glass foaming agent and glass powder contains a large number of cells formed by eliminating the cell forming agent. By heating this green compact, the glass powder constituting the green compact is softened and the glass foaming agent is decomposed to generate gas and generate a large number of bubbles in the softened glass. The glass, whose apparent volume has increased due to the air bubbles, fills the many air bubbles in the green compact. As a result, the green compact becomes a glass foam that is homogeneous as a whole and has many small closed cells, without significantly changing the external dimensions of the green compact.

The method of manufacturing a green compact containing a large number of air bubbles inside and composed of a glass foaming agent and a glass powder includes, for example, a mixed powder of a glass foaming agent and a glass powder, an adhesive such as water glass, and an adhesive such as water glass. A slurry is made with water, and foamed beads such as foamed polystyrene beads are mixed into this slurry as a cell structuring agent to form a molded body of a glass foaming agent and glass powder in which the foamed beads are uniformly dispersed.

In this case, the mixing ratio of the glass blowing agent is preferably in the range of 1 to 10 parts by weight per 100 parts by weight of the glass powder. If the glass blowing agent is below this range, bubbles will not be sufficiently generated in the next heating step, and the heat insulating properties of the molded article will tend to deteriorate. On the other hand, above this range, too many bubbles are generated, the shape of the molded article is distorted, and the mechanical strength tends to decrease. Further, the amount of the adhesive such as water glass added is preferably 1 to 10 parts by weight per 100 parts by weight of the glass powder. If the adhesive such as water glass is below this range,
The viscosity of the slurry is low; on the other hand, above this range, the viscosity becomes high, and in either case, operations such as casting become difficult.

Furthermore, the mixing ratio of the cell structuring agent is
The range of 2 to 12 parts by weight per 100 parts by weight is preferred. If this mixing ratio is less than 2 parts by weight,
There are few bubbles formed by the foamed bead cell structuring agent, and it tends to be difficult to absorb the volume increase of the foamed glass in the foaming process. As a result, the volume of the glass foam increases and the shape becomes more distorted. If the mixing ratio is 12 parts by weight or more, large air bubbles will remain in the molded product.
Mechanical strength and heat insulation properties tend to decrease.

Thereafter, the molded body is heated at a temperature higher than the decomposition temperature of the cell structuring agent.
For example, in the case of polystyrene foam beads, it is heated to about 250°C to decompose and remove the polystyrene foam beads as a cell structuring agent. By eliminating the cell forming agent, a green compact can be obtained which is composed of a glass blowing agent and glass powder and contains a large number of cells inside. Furthermore, in this method,
In addition to polystyrene foam beads, granular foams such as polyethylene foam beads, polyurethane foam pieces, etc. can be used as the cell structure. In other special cases, organic substances such as rice husks and bread crumbs can be used as a cell structuring agent. or,
In addition to water glass, polyvinyl alcohol,
Organic adhesives such as vinyl acetate emulsion, carboxymethyl cellulose (CMC), and reactive adhesives such as epoxy resins can be used.

Other methods of manufacturing green compacts include:
Like the manufacturing method of plastic extrusion foam molded products, a resin extrusion molded product containing a glass foaming agent and glass powder is foamed with an organic foaming agent as a cell structuring agent, thereby producing a foam molded product containing a large number of cells inside. is produced, and then this molded body is subjected to a degreasing process such as heating to remove the resin and form a green compact composed of a glass foaming agent containing many air bubbles inside and glass powder.

In the present invention, a glass blowing agent is an inorganic compound such as calcium carbonate or dolomite that decomposes at the softening temperature of glass powder to generate carbon dioxide gas, oxygen, etc., or an inorganic compound such as calcium carbonate or dolomite that is combusted at the softening temperature of glass and generates carbon dioxide gas, etc. carbon powder, etc. Further, as the glass powder, ordinary soda lime glass, boric acid glass, and various other glass powders can be used.

In the process of manufacturing glass foam, the green compact obtained as described above is heated to a higher temperature to soften the glass powder that makes up the green compact, and the glass foaming agent is decomposed and softened by the gas generated. This method involves foaming glass, fixing glass powder together, and creating a glass foam containing fine air bubbles inside.
At this time, as the foaming occurs, the apparent volume of the glass increases and fills the air bubbles contained in the green compact, so the volume of the glass foam hardly increases compared to that of the green compact.

The glass blowing agent and glass powder used in the present invention, as well as the heating process for the glass foam, are the same as the conventional glass blowing agent, glass powder, and heating process, and conventional methods and methods can be used as they are. Can be done. Specifically, when soda lime glass is used as a glass powder, it is heated to 650 to 800°C, then gradually cooled, and then cooled to room temperature to produce a glass foam.

In the manufacturing method of the present invention, no mold is required to manufacture the glass foam. Note that a mold can also be used depending on the purpose. Moreover, the apparent expansion (in terms of appearance) during the glass foam molding process is not large. Therefore, a glass foam having substantially the same shape and size as the green compact can be manufactured. Therefore, in order to produce a glass foam of a predetermined shape, the portion that must be cut away is greatly reduced, and the yield is improved. In addition, since there is no need to use a mold when manufacturing the glass foam, problems such as cracking of the glass foam, oxidation, and wear and tear of the mold due to the use of a mold are eliminated.
Improved product yield and reduced costs.

Examples will be described below.

Example 1 Ordinary soda-lime glass waste was washed and dried, and it was coarsely crushed to obtain glass powder. 100 parts by weight of this glass powder and dolomite 5 as a glass foaming agent.
The mixture was further finely pulverized and mixed to produce a raw material powder mixture having a total mesh size of 350 meshes (mesh size 44 μm). To this powder mixture, 50 parts by weight of water, 5 parts by weight of water glass (JIS No. 3), and 5 parts by weight of polyvinyl alcohol were added and stirred to prepare a slurry. Add foamed polystyrene beads (particle size: approx. 1mm, apparent density: 0.048) to this slurry as a cell structuring agent.
3.6 parts by weight of (g/cc) were added and thoroughly kneaded. Pour this into a mold with a concave part with internal dimensions of 16 x 4 x 4 cm (length x width x height), dry and solidify at room temperature for about 24 hours, and form a rectangular parallelepiped with length x width x height = 16 x 4 x 4 cm. A molded body was obtained. Thereafter, the molded body was placed in a dryer and dried at 80°C for 3 hours. Next, this molded body was placed on a ceramic plate, inserted into a gas furnace, heated at a rate of 250°C per hour to 350°C, and the foamed polystyrene beads as a cell structuring agent were decomposed and removed. A green compact made of a glass blowing agent and glass powder and having air bubbles inside was obtained. After that, per hour in the same gas furnace,
The glass foam of the present invention was produced by heating to 750°C at a heating rate of 250°C, holding for 1 hour, and then slowly cooling at a cooling rate of 30°C per hour. The length x width x height of this glass foam was 17.5 x 5 x 5.5 cm. These dimensions were approximately equal compared to the dimensions of the green compact. Further, this glass foam was a closed cell glass foam in which closed cells of about 0.5 to 2 mm were uniformly dispersed almost throughout the interior. The bulk density of this glass foam is 0.114g/cm ³
The compressive strength was 8.1 Kg/cm ² (average value of 3 samples).

Example 2 In this example, polyvinyl alcohol was added to 5 parts by weight of polyvinyl alcohol in Example 1.
A glass foam was produced in exactly the same manner as in Example 1 except that the amount was 2.5 parts by weight, and 4.8 parts by weight in this example compared to 3.6 parts by weight of expanded polystyrene beads in Example 1. The dimensions of the obtained glass foam were 17 cm x 4.5 cm x 5 cm (length x width x height), which were almost the same as the dimensions of the green compact. or,
Closed cells of about 0.3 to 1.5 mm were almost uniformly dispersed inside this glass foam.
In addition, the bulk density of the glass foam of this example is 0.187
g/cm ³ , and the compressive strength was 25.7 Kg/cm ² (average value of 3 samples).

Example 3 In this example, 1 part by weight of polyvinyl alcohol was added to 5 parts by weight of polyvinyl alcohol in Example 1, 6 parts by weight was added to 3.6 parts by weight of expanded polystyrene beads, and the other parts were the same as in Example 1. A glass foam was produced in the same manner. The obtained glass foam had closed cells of 0.2 to 1.2 mm uniformly dispersed therein. In addition, the bulk density of this glass foam is 0.203g/ ^cm3 , and the compressive strength is 37.9Kg/cm3.
cm ² (average value of 3 samples).

Example 4 In place of 5 parts by weight of polyvinyl alcohol in Example 1, 5.5 parts by weight of vinyl acetate emulsion,
A glass foam was produced in the same manner as in Example 1 except that 4.8 parts by weight of polystyrene beads were added to 3.6 parts by weight of polystyrene beads. The obtained glass foam has closed cells with a diameter of 0.5 to 2 mm.
It was dispersed almost uniformly throughout. In addition, the bulk density of this glass foam is 0.108 g/cm ³ ,
The compressive strength was 9.9 Kg/cm ² (average value of 3 samples).

Example 5 Borosilicate glass waste was washed and dried, and it was coarsely crushed to obtain glass powder. After adding 100 parts by weight of this glass powder and 5 parts by weight of calcium carbonate as a glass foaming agent, they are further finely pulverized and mixed to obtain a raw material powder mixture that can pass through a Japanese Industrial Standards standard sieve of 350 mesh (44 μm). Manufactured. To this powder mixture, 100 parts by weight of glass powder, 50 parts by weight of water, 5 parts by weight of water glass (JIS No. 3), and 1 part by weight of carboxymethyl cellulose were added and stirred to prepare a slurry. Add 100% glass powder to this slurry and add expanded polystyrene beads (particle size: approx. 1mm) as a cell structuring agent.
4.8 parts by weight were added to the parts by weight and thoroughly kneaded.
Pour this into a mold with internal dimensions of 16 x 4 x 4 cm (length x width x height), dry and solidify at room temperature for about 24 hours, and form a rectangular parallelepiped with length x width x height of 16 x 4 x 4 cm. I got a body. Furthermore, after that, the molded body was placed in a dryer and dried at 80°C for 3 hours. Next, this molded body was placed on a ceramic plate, inserted into a gas furnace, heated at a rate of 250°C per hour to 350°C, the foamed polystine beads were decomposed and removed, and the glass foaming agent and glass powder were removed. A molded body was obtained. After that, 1 more
Heat to 750℃ at a heating rate of 250℃ per hour.
After being held for several minutes, it was slowly cooled at a cooling rate of 30° C. per hour to produce the glass foam of the present invention.
The dimensions of this glass foam are length x width x height 17 x 5
It was 4.5cm long. This shape was almost the same as the dimensions of the compact. Also, inside this glass foam,
Closed cells of about 0.5 to 1 mm were uniformly dispersed.
The bulk density of this glass foam is 0.199g/
cm ³ and the compressive strength was 26.4 Kg/cm ² (average value of 3 samples). It had lower density and higher strength than the conventional one.

Example 6 Sozo silicate glass waste was washed and dried, and it was crushed into glass powder. 100 parts by weight of this glass powder and 5 parts by weight of dolomite as a glass foaming agent were added, further finely pulverized and mixed, and passed through a Japanese Industrial Standard sieve 350.
A raw material powder mixture was produced that had a mesh size (44 μm). Add 50 parts by weight of water to this powder mixture.
1 part of polyvinyl alcohol was added and stirred to prepare a slurry. To this slurry, 6 parts by weight of expanded polystyrene beads (particle size: about 1 mm) were added as a cell structuring agent and thoroughly kneaded. Pour this into a mold with internal dimensions of 16 x 4 x 4 cm (length x width x height).
It dries and solidifies at room temperature for about 24 hours, and measures 16 mm in length x width x height.
A rectangular molded body measuring 4 cm x 4 cm was obtained. Furthermore, after that, the molded body was placed in a dryer and dried at 80°C for 3 hours. Next, this molded body was placed on a ceramic plate, inserted into a gas furnace, heated at a rate of 250°C per hour to 350°C, the foamed polystyrene beads as a cell structuring agent were decomposed and removed, and the glass foam was formed. A molded body consisting of the agent and glass powder was obtained. after that,
At a heating rate of 250 °C per hour in the same gas furnace
After heating to 600℃ and holding at that temperature for 10 minutes,
A glass foam was produced by slow cooling at a cooling temperature of 30°C per hour. The dimensions of this glass foam are length x
The width and height were 17 x 5 x 5 cm, respectively. This dimension was approximately equal to the dimension of the molded body. Moreover, closed cells of about 0.5 to 1 mm were uniformly dispersed inside this glass foam. The bulk density of this glass foam was 0.201 g/cm ³ , and the strength in the compression test was 28.5 Kg/cm ² (average value of 3 samples).

Claims (1)

[Claims] 1. A green compact that uses a glass foaming agent, glass powder, and a cell structuring agent, and contains a large number of cells that absorb the volume expanded by the glass foaming agent when the cell structuring agent disappears. and a foaming step of heating the green compact and foaming the glass foaming agent to form a glass foam without significantly changing the external shape of the green compact. A method for producing glass foam. 2 The preforming step includes a slurry step in which a glass foaming agent, glass powder, and a binder are mixed to prepare a slurry, and a cell structuring agent is mixed in the slurry to form a molded body in which the cell structuring agent is uniformly dispersed. 2. The method for producing a glass foam according to claim 1, comprising a forming step for preparing the foam and a cell forming step for eliminating the cell structuring agent in the molded object. 3. The preforming step includes a molding step of extruding a mixture of a glass blowing agent, glass powder, and a resin containing foam to form an extruded body, and a forming step of forming an extruded body by foaming the extruded body with a cell forming agent made of an organic blowing agent. Claim 1, characterized in that it consists of a bubble forming step of forming a large number of bubbles inside, and a degreasing step of removing the resin in the molded body in which the bubbles have been formed.
A method for producing a glass foam as described in Section 1.