JPH0243689B2 - GARASUHATSU HOTAINOSEIZOHOHO - 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.

Therefore, when manufacturing a rectangular parallelepiped-shaped glass foam, a relatively large glass foam is manufactured, and the upper and lower surfaces or side portions of the foam are cut off to obtain a rectangular parallelepiped-shaped foam. However, when using this method, there were problems in that a large amount of chips were generated and the yield was poor.

In addition, in the conventional method for manufacturing glass foam, large expansion occurs within the mold, which causes distortion in the glass foam, resulting in problems such as the tendency for cracks to occur in the resulting molded product. Furthermore, there was also the problem that the mold was oxidized and corroded.

The present invention solves the problems of the prior art,
The present invention aims to provide a method for easily manufacturing a glass foam free of defects such as distortion.

That is, the present invention includes a first step of attaching a mixture of glass powder and a foaming agent to the skeleton of an organic structure having pores inside to form a preform, and heating the mixture to form the skeleton. A second step of removing the above mixture and forming an intermediate formed body having continuous pores, and a third step of heating the above mixture to a high temperature to foam the mixture. It's in the manufacturing method.

According to the method of the present invention, in the step of manufacturing a glass foam, the volumetric expansion caused by the blowing agent is absorbed by the air bubbles contained inside the intermediate molded body, so that a glass foam without distortion can be manufactured. Therefore,
It is possible to produce a glass foam having almost the same shape and size as the initial organic structure, and the shape of the glass foam can be determined from an early stage.
Also, therefore, the portion that must be cut off to form a glass foam of a desired shape is significantly reduced, improving yield. In addition, there is no need to use a special mold for molding, and manufacturing is simple. Further, a glass foam can be obtained that is free from defects such as distortion and cracks caused by using a mold. Further, depending on the amount of the mixture of glass powder and blowing agent deposited on the organic structure, either small closed cells or open cells can be selectively formed inside the glass foam. Moreover, the closed cells are homogeneous throughout and are formed in large numbers, making it possible to create products with excellent mechanical strength and heat insulation properties. Because it forms bubbles, it can be used in filters, sound absorbing materials, etc.

In the method of the present invention, the organic structure having pores inside used in the first step may be a foamed organic material such as polyurethane foam, polystyrene foam, polyethylene foam, or a cotton-like structure such as loofah or palm chisel. There is an organic body with many pores inside. The above organic structure is
When adhering a mixture of glass powder and a blowing agent to the skeleton, a material that can be easily penetrated and impregnated with the mixture is used. In this sense, it is preferable that the foam such as the polyurethane foam has a structure in which no cell membrane is present. Further, the organic structure preferably has a structure that does not cause changes in shape such as shrinkage or swelling when impregnated with the mixture.

Further, as the glass powder, ordinary soda lime glass, boric acid glass, and various other glass powders are used. As a blowing agent, when heated above the softening temperature of glass powder, it causes thermal decomposition and generates gases such as carbon dioxide and oxygen. Inorganic compounds such as calcium carbonate and dolomite, or carbon powder that burns at a temperature higher than the softening temperature of glass and generates carbon dioxide gas, etc., are used.

Next, these glass powders and a foaming agent are mixed. In this mixing, in order to improve the adhesion of the mixture to the skeleton and increase the amount of adhesion,
As the adhesive, organic adhesives such as water glass, polyvinyl alcohol, vinyl acetate emulsion, carboxymethyl cellulose (CMC), and reactive adhesives such as epoxy resins can also be used.

The method of attaching the mixture to the skeleton of the organic structure, which is the first step of the present invention, includes, for example,
A foaming agent, glass powder, and an adhesive such as water glass are mixed to form a slurry, and an organic structure such as polyurethane foam is immersed in this slurry, then taken out and dried. As a result, a preformed body is formed in which the organic structure is uniformly impregnated with the mixture of the glass powder and the blowing agent.

In this case, the mixing ratio of the glass powder and the blowing agent is preferably in the range of 1 to 10 parts by weight of the blowing agent per 100 parts by weight of the glass powder. If the blowing agent is below this range, bubbles will not be sufficiently generated in the heating step for foaming the blowing agent, and the heat insulation 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 will be low, whereas if it is above this range, the viscosity will be high, and in either case, it will be difficult to attach the slurry to the organic structure.

Further, the proportion of the mixture to be adhered to the organic structure is preferably in the range of 400 to 1200 parts by weight, for example, per 100 parts by weight of the organic structure. If the mixture exceeds this range, there will be fewer continuous pores formed by the organic structure, making it difficult to absorb the volume increase of foamed glass during the foaming process using a foaming agent, and the apparent volume of the molded product will increase. As a result, the shape of the glass foam becomes distorted and distorted. On the other hand, below this range, large bubbles will remain in the molded product, resulting in a decrease in mechanical strength and heat insulation properties.

In addition to the above methods, methods for attaching the mixture to an organic structure include a method of embedding the mixture into the voids of an organic structure such as polyurethane foam with a very fine mesh to form a molded body;
There is also a method of moistening an organic structure with an adhesive such as vinyl acetate emulsion and attaching powder of the mixture to form a molded body.

Note that the slurry of excess glass powder and foaming agent adhering to the organic structure formed as described above can be removed by a centrifugation method, a pressurized air blowing method, a vacuum suction method, or the like.

Next, in the second step, the organic structure is heated to a temperature higher than the decomposition temperature of the organic structure, for example, about 250° C. in the case of polyurethane foam, and the polyurethane foam as the organic structure is thermally decomposed and removed. As a result, an intermediate molded body made of the mixture and having a large number of communicating holes therein is formed.

Next, in the third step, the intermediate molded body is heated to a higher temperature than in the second step to soften the glass powder constituting the intermediate molded body and foam the foaming agent. At this time, the blowing agent decomposes and generates gas, creating a large number of bubbles in the softened glass.
During this foaming, the glass bubbles fill the inside of the continuous holes formed in the second step. In addition, at this time, if the amount of glass powder deposited in the first step is large, the volumetric expansion of the glass will be large;
Fill most of the open pores and form small closed cells. On the other hand, when the amount of glass powder is small, communicating holes remain.

The heating method in the third step of the present invention is the same as the heating method used to manufacture conventional glass foams. For example, when using soda-lime glass as glass powder, 650 to 800
The glass foam is produced by heating at a temperature of °C, then slowly cooling, and still cooling to room temperature.

In the third step of the present invention, most of the increase in the volume of the glass is absorbed by the continuous pores of the intermediate formed body, so that no change in the external shape of the glass foam occurs.

Note that in the present invention, a glass foam can be manufactured without using a mold, but a mold can also be used if necessary.

Examples of the present invention will be described below.

Example 1 Ordinary soda-lime glass was crushed into glass powder. 100 parts by weight of this glass powder and 5 parts by weight of dolomite as a foaming agent were added and further pulverized and mixed to produce a raw material powder mixture. To 105 parts by weight of this powder mixture, 100 parts by weight of a 1% polyvinyl alcohol aqueous solution and 5 parts by weight of water glass (JIS 3 parts) were added and stirred to prepare a slurry as a mixture.

On the other hand, as an organic structure having internal pores, polyurethane foam (13 cells/25
The polyurethane foam was impregnated with the above slurry using a polyurethane foam (mm), and after removing excess slurry, it was dried. This operation was repeated 5 times, and then dried at room temperature for about 24 hours. Furthermore, after that, this thing was dried at 80℃, and the length x width x height was 10 x 10 x
A 3 cm preform was obtained. Next, this preform is placed on a ceramic plate and inserted into a gas furnace.
The temperature was gradually raised to 350° C., and the polyurethane foam was decomposed and removed, thereby producing an intermediate molded body with a large porosity composed of a mixture of glass powder and a blowing agent. Then, in the same gas furnace,
The glass was heated to 750°C and held for 1 hour to foam the glass. Thereafter, it was slowly cooled to obtain a glass foam according to the present invention. A cross-sectional view of this glass foam is shown in FIG. In the figure, the shaded area is the glass foamed area, the area surrounded by the solid line is the air bubbles, and the area inside the dotted line is the remains of the continuous holes in the intermediate molded body. The dimensions of this glass foam are length x width x height 11 x 11 x
It was 3.5cm. This dimension was approximately the same as the dimension of the preform before heating. Further, this glass foam was a closed cell glass foam in which closed cells of about 0.3 to 1.5 mm were uniformly dispersed almost to the inside. The bulk density of this glass foam is 0.15g/
It was warm at ^cm3 .

Example 2 A glass foam according to the present invention was produced in the same manner as in Example 1, except that the steps of impregnating a polyurethane foam without a cell membrane with a slurry mixture, removing excess slurry, and drying were performed three times. was manufactured. The dimensions of this glass foam are length x
The width x height was 10.5 x 10.5 x 3.3 cm.

This dimension was almost the same as that of the molded product before heating. Further, this glass foam had open cells of about 0.5 to 1.5 mm uniformly dispersed almost to the inside. Moreover, the bulk density of this glass foam was 0.12 g/cm ³ .

The reason why the glass foam differs from that obtained in Example 1 in that it has open cells and has a low bulk density is because the number of times the slurry was impregnated was smaller than in Example 1. .

Example 3 In the same manner as in Example 1, 40 parts by weight of a 2% polyvinyl alcohol aqueous solution and 5 parts by weight of water glass (JIS No. 3) were added to 105 parts by weight of a powder mixture of glass powder and blowing agent and stirred to prepare a slurry. did. This slurry was impregnated into a polyurethane foam having the same structure and size as in Example 1, except for the number of cells (8 cells/25 mm) and no cell membrane, and after removing excess slurry, it was dried. This operation was repeated four times to obtain a preform. The dimensions of this molded body are
The length x width x height was 10 x 10 x 3 cm. The subsequent steps were the same as in Example 1 to produce a glass foam. The dimensions of this glass foam are length x width x
The height was 10.5 x 10.5 x 3.5 cm, which was approximately equal to the dimensions of the preform before the heating process. Also,
This glass foam was a glass foam in which open cells of about 0.5 to 1 mm were uniformly dispersed almost throughout the interior. The bulk density of this glass foam is 0.18
g/ ^cm3 .

Example 4 Glass foam according to the present invention was produced in the same manner as in Example 3, except that the steps of impregnating a polyurethane foam without a cell membrane with the slurry as a mixture, removing excess slurry, and drying were carried out seven times. manufactured the body. The dimensions of this glass foam are:
The length x width x height was 11 x 11 x 3.5 cm, which were almost the same as those of the preform before heating. Further, this glass foam had closed cells of about 1 mm uniformly dispersed almost inside. Further, the bulk density of this glass foam was 0.20 g/cm ³ .

The reason why the glass foam differs from that obtained in Example 3 in that it has closed cells and has a high bulk density is because the number of times the slurry was impregnated was greater than in Example 3. .

Example 5 35 parts by weight of a 2% aqueous polyvinyl alcohol solution and 5 parts by weight of water glass (JIS No. 3) were added to the same powder mixture of glass powder and blowing agent as in Example 1 and stirred to prepare a slurry. Using a soft urethane foam (density 0.02 g/cm ³ cells/25 mm) as an organic foam having pores inside, the above slurry is impregnated into the soft urethane foam,
After filling the gap between the soft urethane foam, it was dried to produce a preform having the same dimensions as in Example 1. The subsequent steps for manufacturing the glass foam were carried out in the same manner as in Example 1. The dimensions of the obtained glass foam are 11 x 11 x length x width x height.
The size was 3.5 cm, which was almost equal to the size of the preform before the heating process. Further, this glass foam had closed cells of about 0.5 to 1 mm uniformly dispersed almost throughout the interior. The bulk density of this glass foam was 0.21 g/cm ³ .

[Brief explanation of the drawing]

The figures show examples of the present invention; FIG. 1 shows an end face of a polyurethane foam without a cell membrane in Example 1, and FIG. 2 shows a cross section of the glass foam obtained in Example 1. 1... Skeleton of polyurethane foam, 2... Holes, 3... Glass foam portion, 4... Traces of continuous holes in intermediate molded body.

Claims (1)

[Claims] 1 In the skeleton of an organic structure that has pores inside,
A first step of adhering a mixture of glass powder and a foaming agent to form a preform, and a second step of heating them to remove the skeleton and forming an intermediate molded object made of the mixture and having continuous holes. A method for producing a glass foam, comprising two steps and a third step of foaming the mixture by heating these steps to a high temperature.