AT404586B - COMPOSED GLASS PANEL - Google Patents

Description

ΑΤ 404 586 Β

The invention relates to composite glass plates that provide high sound attenuation.

There is a requirement for glass plates that apply a high degree of sound attenuation, and various types of glass plates have been proposed to meet this requirement. In particular, hollow glass sheets, including gas (e.g. air) filled sheets and evacuated sheets, and laminates are known, including those in which the adhesive resin has a fairly smooth texture so that it has a damping effect. Both hollow and multilayer panels can be provided with thin layers of asymmetrical thickness to improve sound attenuation at certain frequencies. It is of course known to incorporate one or more multilayer glass plates in a hollow glass plate. Such panels have various disadvantages which make them unsuitable for use in certain circumstances where it would be desirable to provide a high level of soundproofing.

AT-385948A describes a process for drying swellable material consisting of hydrogenated salts, a process for the production of refractory glass, and the production of a layer of the swellable material as an intermediate layer between two transparent glass plates.

From GB-1.122.870A a layer process for the production of glass plates with incorporated decorative bubbles has become known. In this layering process, the two glass plates, which can also be colored, are connected to one another by fusion; decorative bubbles are incorporated after the fusion process.

Gas-filled hollow panels have a sound attenuation, which is largely due to the " thickness " of the gas-filled layer interspace is determined. For a high attenuation, the interlayer gap must be quite large and this can create manufacturing and framing difficulties. For example only, such panels are unsuitable for installation in thin partitions due to their thickness. As long as they are evacuated, the plates can provide good attenuation with a relatively narrow layer gap, such evacuation tends to bend the thin glass layers of the plates inwards, particularly in the case of fairly large plates, and this can result in an undesirable direction of reflection .

Multilayer glass plates provide an attenuation which, generally speaking, depends on their mass. A high specific mass (i.e. mass per unit area) is required for high attenuation. Again, just as an example, such panels are unsuitable for installation in walls where weight considerations are an important factor.

It is an object of the invention to provide a composite glass plate which offers a very high degree of sound attenuation in relation to its total thickness and specific mass.

According to the invention there is provided a composite glass plate which provides high sound attenuation, characterized in that such a plate consists of two layers of glass-like material, between which a layer of an airgel is arranged, the sandwich plate being connected as a monolithic laminate.

The term " monolithic laminate " is used here with the meaning of a laminate that is connected in such a way that it is in the same way as a single plate of a material with a modulus of elasticity resulting from the modulus of elasticity! and thicknesses of the individual layers of the laminate can be calculated vibrates. Such monolithic laminates contrast with hollow panels and laminates that are only weakly assembled so that they behave more like a box than a panel during vibration. Therefore, in a monolithic laminate there is no "mass / interracial mass" resonance.

Such a composite glass plate offers a very high degree of sound attenuation in relation to its total thickness and specific mass.

Such a plate has the advantage of guaranteeing that two essential sides of the airgel layer are protected against atmospheric moisture. Aerogels in general are highly absorbent to atmospheric moisture, which means that they tend to split and dissolve in dust. The corners of such a laminate can be quickly protected in a manner known per se by using a moisture-resistant sealant, such as a silicone-based mastic preparation.

Another object of the invention is to provide a method for producing such a plate.

Accordingly, the present invention provides a method of making a composite glass panel that provides high sound attenuation, characterized in that an airgel layer is sandwiched between two layers of vitreous material and the sandwich panel is bonded as a monolithic laminate.

This is a very simple process for making such a plate. 2nd

AT 404 586 B

The airgel used can be an airgel made of aluminum, zirconium, tin oxide or tungsten, but is preferably a silica-based airgel. To make an airgel plate for assembly into such a laminate, a layer of the appropriate gel is spread in a solvent on a suitable mold plate, and the solvent is removed from the layer to leave an airgel plate. In a preferred method, a silica gel is spread in alcohol as a solvent on a mold plate, which is then placed in an autoclave. The autoclave is pressurized and the gel is flushed with liquid carbon dioxide, if desired, to displace all or most of the alcohol solvent. The pressure in the autoclave is increased to a pressure which is greater than the critical pressure for the solvent liquid present in the layer (about 8x10 * Pa (80 bar) for alcohol or about 7.4x10 * Pa (74 bar) for carbon dioxide). The temperature in the autoclave is then increased to above the critical temperature for this solvent (about 240 * C for alcohol or about 31 * C for CO2). In order to form the airgel, it is possible to remove the solvent from the layer, without the silica structure collapsing, and indeed the structure of the airgel can contain up to 98% air bubbles per volume. The airgel plate obtained by this process is then placed between two layers of glass and the sandwich plate is bonded as a monolithic laminate to produce a plate according to the invention.

Panels according to the invention can be opaque, for example they can be made as decorative panels, which can then be colored by adding colorants to the airgel or in some other way, but this sandwich panel is preferably connected to produce a non-permeable laminate. If the laminate is translucent, it can be used as a window shutter or elsewhere where translucency is an important factor. Depending on the thickness of the airgel within the laminate, it may even be transparent.

When a prefabricated layer of airgel is bonded to a layer of glass, care must be taken. If a solvent glue is used, the solvent is likely to penetrate the airgel, which would collapse the airgel matrix, in some ways in the same way that moisture absorption is.

Therefore, the adhesive is preferably essentially free of solvent. Therefore, it is preferred to use heat-softenable or easily meltable adhesive. Aerogels are very well able to withstand the high temperatures required to fuse many heat-softenable adhesives. Such heat-softenable adhesives can be in the form of a thin layer or film, but it is advantageous that the adhesives be in powder form as this simplifies handling problems. Such a powder adhesive can be easily, e.g. by means of an electrostatic spray technique known per se. Easily meltable silicone resins are particularly well adapted to form a highly effective connection between silica aerogels and glass layers, which are also rich in silica.

In a particularly preferred embodiment of the invention, the or at least one of the airgel layer (s) is (are) connected directly to the glass layer. This avoids any problems in the selection and use of an intermediate adhesive layer, and greatly simplifies manufacture. The simplest way to ensure such a direct connection is to use this glass layer as a molding plate on which the airgel layer is first formed. In this way, the or at least one of the airgel layer (s) is formed directly on the glass layer, so that they are directly connected to it. A silica-based airgel is easily coated directly with the glass silica matrix from e.g. connected to a glass plate.

In some preferred embodiments of the invention, the laminate contains two airgel layers, each bonded directly to the glass layer. By assembling two airgel layers, each formed directly on the glass layer to make the laminate, it is easy to manufacture a plate that has a very high degree of sound attenuation in relation to its thickness and weight.

It is believed that the sound attenuation across a glass plate according to the invention is largely due to the very large difference in acoustic impedance as between the airgel and the glass-like material, due to the very low speed of sound propagation in airgel. However, to take full advantage of this phenomenon, the airgel layer (s) should not be too thin and it is accordingly preferred that the or at least one of the airgel layer (s) have a thickness of at least 10 mm. Increasing the thickness of an airgel layer is also very useful for thermal insulation if desired. It should be noted, however, that the airgel layers transmit a significant amount of light in a diffuse manner, and therefore the total thickness of the airgel in a plate should not be too large if a high degree of resolution through the plate is considered important. 3rd

AT 404 586 B

In order to protect the airgel as a whole against possible attacks by atmospheric moisture, it is preferred that the airgel is hermetically sealed within the laminate. This can be done in several ways, e.g. by using an edge sealant of the mastic type as mentioned above, optionally in connection with a gutter frame, e.g. made of extruded aluminum. Preferably, however, the laminate is hermetically sealed by one or more spacers which extend around the plate and which are soldered to the glass layers of the laminate. This creates a very effective and long-lasting protection for the airgel.

In some preferred embodiments of the invention in which the airgel is hermetically sealed within the laminate. the inside of the laminate is evacuated. This is very preferred from the point of view of thermal insulation, and it can also have a useful advantage in allowing more reliable maintenance of the very low sound propagation rate in airgel.

Preferred embodiments of the invention will now be described by way of example only with reference to the accompanying schematic drawings, in which:

Fig. 1 shows a stage in the manufacture of a plate according to the invention and

2 and 3 are cross sections through two embodiments of a plate according to the invention.

A glass layer 1 of suitable size and appearance has a framing dam 2 which is attached around its periphery (cf. FIG. 1).

The space formed above layer 1 and within dam 2 is then filled with an airgel-forming solution. As shown in FIG. 1, layer 1 is housed within an autoclave 3 having gas inlet 4 and outlet port 5 and a heater shown at 6.

The solution used is an alcohol solution, which is a solution in alcohol. The gel-forming solution can be silica alone or other oxides, e.g. of aluminum, tellurium, germanium or other materials, so that the airgel to be formed is given specifically desired properties.

After the airgel-forming solution has been poured out and any bubbles have been removed, the solution is allowed to gel and deposit. The alkogel formed in this way is refined with liquid carbon dioxide, which takes the place of the alcohol in the alkogel solution. This can be done by repeatedly washing the gel solution at about 18 to 20 * C, at a pressure of about 5.5x106 Pa (55 bar). This has the advantage that the next stage of manufacture is simplified.

The pressure inside the autoclave 3 is then increased to above the critical pressure of the solvent, 7.4x10 "Pa (74 bar) for CO2, and the temperature inside the autoclave is then increased to above the critical temperature, 31 * C for carbon dioxide. This stage is simplified for the replacement of carbon dioxide as a solvent, since if the solvent remains alcohol, the temperature and the required pressure would exceed 240 * C and 8x106 Pa (80 bar). Typical practicable temperatures for this stage of production are about 40 * C for carbon dioxide and about 270 * C for alcohol as a solvent. Carbon dioxide is suitably used as compressed gas, supplied via the inlet slide 4. During the drying of the layer, part of the steam inside the autoclave is deaerated to escape through the outlet slide 5, and after completion of the drying, an airgel layer 7, which is connected to the layer 1, is left behind.

The layer of airgel 7 is then placed between the first layer 1 and a second glass layer.

FIG. 2 shows a plate in which the airgel layer 7 is connected to a second layer of glass 8 by an intermediate layer of an adhesive 9. Such a connection is brought about by electrostatically spraying a layer of powdered silicone resin onto the airgel layer 7, joining the second layer 8 to the adhesive, and heating the assembly to bring about a fusion of the resin, so that after cooling the sandwich panel is connected as a laminate. The plate is completed by placing a silicone-based mastic material 10 in the undercut between the aeroge layer 2 and the first layer 1, which was left behind after removal of the framing dam 2 (FIG. 1).

In Fig. 3 a second embodiment of the plate is shown, which is formed by gluing together two layers 7 of airgel, each being formed on a glass pane 1 and connected directly to it. Like the laminate of FIG. 2, the laminate of FIG. 3 is connected by means of an adhesive layer 9, which is suitably formed accordingly.

Each of the glass layers 1 of Fig. 3 carries an edge metal vapor deposition layer of copper, covered by a layer of soft solder, these are shown together at 11. These layers 11 were applied before the airgel layers 7 were formed and they were covered by the framing dams 2 during the formation of such airgel layers. After the laminate has been glued together, metallic spacer strips 12 are placed between the metal vapor deposition / soft solder layers around the edge of the plate 4

Claims (20)

ΑΤ 404 586 Β soldered so that the airgel layers are hermetically sealed from the surrounding atmosphere. The inside of the plate can then be evacuated if desired. Such panels, whether according to Fig. 2 or Fig. 3 offer a very high degree of sound attenuation, taking into account their total thickness and weight per unit area and they also offer excellent thermal insulation. In a variant of the embodiment shown in FIG. 3, the spacer strip 12 is not exactly guided between the two glass layers, but rather it is chosen in such a way that the path of heat conduction between these layers is extended around its edges. In a further different plate, one according to FIG. 2 or 3, the sealing material 10 from FIG. 2 or the metal vapor deposition strip 11 and the spacer 12 from FIG. 3 are produced according to the instructions. For this, the two layers of glass are soldered together using a glass connection point. It can be appreciated that such a laminate, as shown in Fig. 2 or 3, can be assembled into one or more elements to produce a board of a more complex structure, if desired. In particular, such a more complex plate can contain one or more further glass plates such as 1, which carries a directly formed layer 7 of airgel. 1. Composite glass plate that provides high sound attenuation, characterized in that the plate consists of two layers of glass-like material, between which a layer of an airgel is arranged, the sandwich plate being connected as a monolithic laminate. 2. Board according to claim 1, wherein the laminate is translucent. 3. Plate according to claim 2 or 3, wherein a slightly melting silicone resin is used as an adhesive for connecting layers of the laminate. 4. A plate according to any preceding claim, wherein the or at least one airgel layer is bonded directly to the glass layer. 5. The panel of claim 4, wherein the laminate contains two layers of airgel, each layer being bonded directly to the glass layer. 6. A plate according to any preceding claim, wherein the or at least one airgel layer is at least 10 mm thick. 7. A panel according to any preceding claim, in which the airgel is hermetically sealed within the laminate. The panel of claim 7, wherein the laminate is hermetically sealed by one or more spacers that extend around the front edge (s) of the airgel layer (s) and soldered to the glass layers of the laminate. 9. Panel according to claims 7 or 8, wherein the interior of the laminate is evacuated. 10. A method for producing a composite glass plate which provides a high sound attenuation, characterized in that a layer of an airgel is placed between two layers of glass-like material, and the sandwich plate is connected as a monolithic laminate. 11. The method according to claim 10, in which the sandwich panel is connected from translucent individual disks or layers. 12. The method according to claim 10 or 11, in which an essentially solvent-free, easily meltable adhesive is used as the adhesive for connecting the layers of the laminate. 13- Method according to claim 12, in which a powdery adhesive is used as the adhesive for connecting the layers of the laminate. 5 AT 404 586 B 14. The method according to claim 12 or 13, in which a silicone resin is used as the adhesive for connecting the layers of the laminate. 15. The method according to any one of claims 10 to 14, wherein the or at least one of the airgel layers is formed directly on the glass layer so that it is bonded directly thereon. 16. The method of claim 15, wherein the laminate is formed by assembling two airgel layers, each being formed directly on the glass layer. 17. The method according to any one of claims 10 to 16, wherein the or at least one airgel layer is formed into a thickness of at least 10 mm. 18. The method of any of claims 10 to 17, wherein the airgel is hermetically sealed within the laminate. 19. The method of claim 18, wherein the laminate is hermetically sealed using one or more spacers that extend around the leading edge (s) of the airgel layer (s) and that are soldered to the glass plates of the laminate. 20. The method according to claim 18 or 19, wherein the interior of the laminate is evacuated. Including 1 sheet of drawings