WO2001004434A1 - Insulating element with cellular type structure and method for making same - Google Patents

Abstract

The invention concerns an insulating element (1) comprising a cellular structure (6), and having improved properties concerning the stability of the insulating material (3), in particular in powder form, located in the cells (2). This is achieved by cross curing of the insulating means (3) via openings provided in the walls of the cells (4). The invention also concerns an improved method for making insulating elements, in particular insulating elements forming panels, and comprising a cellular structure (6), said cellular structure (6) being pressed in the insulating material (3).

Description

Description:

Insulating body with a cell-like structure and method of manufacture

The invention relates to an insulating body with a cell-like framework and to a method for producing insulating bodies with a cell-like framework.

Cell-like insulating bodies in the form of honeycombs are used in various areas for heat or noise insulation or heat insulation, since they combine considerable advantages. So they have a high mechanical strength. The upstanding walls ensure high bending strength and pressure stability. They are also relatively easy to edit, e.g. B. by cutting. By enclosing the insulating material in individual, relatively small honeycomb spaces, material is only released from the insulating body when the insulating body is cut through, where the cell is immediately severed. Furthermore, when using suitable materials, e.g. B. resin-reinforced paper or plastics, a reduction in the weight of the insulating plates is possible. Cell-like insulating bodies thus combine low weight with good mechanical properties and good handling.

A disadvantage of known cell-like insulating bodies is that, despite strong compression of the insulating material in the cells, there is a risk that the insulating material will loosen over time and leak out of the cells. This is particularly problematic in areas of application where strong vibrations occur, such as. B. in vehicle construction. This problem is remedied in the known insulating bodies in that the finished insulating body with a skin, for. B. made of plastics, paper or resin, such. B. in DE 34 28 285. Also in GB 1,262,459 an outer or shell layer, for. B. made of cardboard. According to GB 1,234,373, a film or paper sleeve is glued on. From US 4,330,494 it is known that foamed resin is used as the insulating material, which is poured into the honeycomb structure in liquid form, where it cures and thus forms a firm connection with the cells. The disadvantage of this insulating plate is that the selection of filler materials that can be used is severely restricted. Only those insulating materials can be used that are foamable and can form a firm connection with the surrounding support material.

According to DE 29 42 087 the insulating material to achieve a high mechanical strength of the cell-like insulating body, a finely ground binder, for. B. thermally curable resins or low-melting glasses, and a dispersant, for. B. polytetrafluoroethylene. This modified insulating material is then filled into the cells and cured. This eliminates the need to wrap the insulation panels.

From the above DE 34 28 285 an insulating body with a cell-like structure and a method for its production are known. A disadvantage of this insulating body with finely divided insulating material is the complex manufacturing process. It is also problematic that after the compression of the insulating material, when the pressure is released, the volume of the insulating material increases, so that the insulating material swells out over the walls of the cell-like structure. This overflowing insulating material must then be removed in a separate manufacturing step, e.g. B. by turning away. According to DE 34 28 285, special flexible or elastic layers are used between the pressure piston and the framework during the pressing, so that the insulating material is pressed to a level below the top edge of the cell and then, when the pressure drops, can rise to the intended cell height. US 3,964,527 describes a method for producing a honeycomb-like insulating body with fibrous insulating material. For this purpose, the honeycomb structure is cut into an insulating felt that lies on a vibrating surface. So that the loose insulation material fills the entire cell space, a vacuum is created after the filling process, with which the insulation material is loosened again and completely sucked into the cells. Disadvantages of this process are, on the one hand, that it is limited to fibrous insulating material, and, on the other hand, that the entire process is very complex since a vibration device and a vacuum system have to be provided.

The object of the present invention is therefore to provide an insulating body which solves the problem of the poor stability of, in particular, powdery insulating material in insulating bodies with a cell-like structure. In addition, a manufacturing method is to be provided with which the known disadvantages in the manufacture of insulating bodies with a cell-like structure can be avoided.

This object is achieved by an insulating body with a cell-like structure according to claim 1 and a manufacturing method according to claim 11. Advantageous developments are the subject of the dependent claims.

The main advantage of the insulating body according to the invention is that, despite the use of powdered insulating materials, the insulating material does not emerge from the cells, since the entire insulating material is cross-linked via the proposed cross-connections. In addition, the insulating material adheres well to the cell walls, since the openings in the walls create additional edges and

Result in mounting surfaces with which the filling material can come into contact. In the case of such insulating bodies, there is no danger that material could escape from the cells even under permanent vibrations. This creates an outer coating on the Completely pressed plates are usually unnecessary. This additional manufacturing step is thus omitted or can be replaced by a simple film wrapping.

It is also advantageous that neither the stability nor the insulating ability of the insulating bodies decrease in comparison to cell-like insulating bodies without a cross connection. The insulating body according to the invention even has further improved insulating properties compared to conventional cell-like insulating plates. The problem of inadequate insulation by the cell walls, which may serve as heat or sound bridges from one side of the insulating body to the other, since the cell walls are continuous, is alleviated because the relatively poorly insulating cell walls are repeatedly grid-like in the openings of good insulating material to be interrupted.

The manufacturing method according to the invention is simplified in comparison to the prior art, since the honeycomb structure can simply be pressed into the filling material lying on a base, possibly smooth-drawn, with a low pressing force. Furthermore, no voids remain in the insulating material, since any air that may still be present can escape in the exchange between the honeycomb cells when the framework is pressed in. The result of this method in relation to the presence of voids in the insulation is comparable to that obtained by vibration compression. The process, on the other hand, is much simpler since no separate system for generating the necessary vibrations is required.

An embodiment of the invention is described below with reference to the drawings. Show it:

Figure 1 is a fragmentary perspective view of a honeycomb insulating body. Figure 2 is a side view with associated section through a honeycomb structure. 3 shows an insulating body with an alternative cell structure; and Fig. 4 is a schematic press for producing an insulating body.

As can be seen from FIG. 1, an insulating body 1 according to the invention consists of lined-up, honeycomb-shaped cells 2. The cells 2, which are open at the top and bottom, are filled with an insulating material 3 shown in dotted lines. The walls 4 of the individual cells 2 are partially broken through with openings 5 shown in a circle. These openings can be provided on all side walls 4 of the cells 2 or only on a part of the sides, for. B. only on every second or third side wall (see FIG. 2), so that there are three or two openings 5 to the neighboring cells for each hexagonal cell or honeycomb. The openings 5 in the cell-like framework 6 thus formed can preferably be distributed regularly, but also irregularly in the walls 4.

FIG. 2 shows that the shape and number of the openings 5 forming the transverse openings per cell 2 can be varied. Round openings 5 are particularly advantageous since they can be formed simply by punching out the walls 4 when manufacturing the cell-like framework 6. However, oval or angular shapes are also possible, as is indicated by reference number 5 '. The number of openings 5 per side wall 4 is largely arbitrary. In order to achieve sufficient interlinking of the insulating material 3 from cell to cell, one opening or opening 5, 5 'is sufficient, but two openings 5 or more are also possible. It is also provided that there is only one opening per cell, but two or more openings 5 are more favorable in order to ensure the best possible spatial cross-linking to the respective neighboring cells. In order to achieve sufficient interlinking of the insulating material 3, a certain minimum size of the openings is also necessary, in particular depending on the size ratios of the powders or mineral fibers used. The size of the openings 5 is about 30% of the Wall area of the wall 4 (cf. sectional view in FIG. 2, right), so that a good interlocking of the insulating material 3 between adjacent cells 2 is possible. Sufficient stability of the cell-like framework 6 is also made possible.

FIG. 3 shows an insulating body with an alternative structure of the cell-like framework 6, namely with trigonal cells 2. Its walls 4 are also provided with a large number of openings 5, analogously to the cells with a honeycomb structure shown in FIG. 1. Trigonal cells represent only one of the conceivable alternatives to honeycomb-like cells. Round cells or cells 2 in rectangular or square form may also be mentioned here as examples. Uneven shapes and shapes are also conceivable.

Plastics and resin-reinforced paper are preferably used as materials for the walls 4 or the cell-like framework 6. However, there are cell-like frameworks 6 made of aluminum honeycombs or fiber-reinforced cardboard, as is known from sandwich constructions in aircraft construction.

If an encapsulation of the pressed insulating body 1 is desired in particular in the form of a plate, although this is not absolutely necessary, this is possible. These envelopes can consist of plastic films, paper, cardboard, fabrics, etc., depending on the desired strength or application area, e.g. B. from carbon or aramid fiber cover layers.

Depending on the intended use, all flowable materials with insulating properties can be used as insulating materials 3. The prerequisite is that they can make cross-connections through the openings 5 with the neighboring cells 2 (see FIG. 2, right). Interlocking of individual particles must be ensured, as z. B. is the case when a mineral fiber content is included. Microporous insulating material is particularly preferred. The following composition is given as an example: 65% by weight of finely divided metal oxide, 32% by weight of opacifier, 3% by weight of fiber material.

Examples of finely divided metal oxides are pyrogenic silicas or aluminum oxides. As opacifiers, for. B. titanium dioxide or zirconium silicate can be used. Examples of fiber materials are ceramic fibers, glass wool and rock wool or, in the low temperature range, also organic fibers. The fiber content in the insulating material used should be high enough to support the crosslinking through the openings, but low enough so as not to impair penetration through the openings 5 to the respective neighboring cells during the pressing. The fiber content is preferably in the range from 0.25 to 25% by weight, in particular approximately 5% by weight.

Fig. 4 shows an example of a device 10 for producing an insulating body 1 (see FIG. 1) with a cell-like frame 6. The cell-like frame 6 is placed on the insulating material 3 filled in a tub 8 and by means of a press ram 7, which by a Press cylinder 9 is pressed down into the insulating material 3. The insulating material 3 can also be preformed in the form of a plate, so that a smooth base is sufficient. During the pressing process, the honeycomb frame 6, in particular with the openings 5 (only a few are indicated here), is thus pressed into the insulating material 3 over the entire surface.

The insulating material 3 can be pressed in either at the same time as the cell-like framework 6 is pressed in, or beforehand. The pre-compression has the advantage that the insulating material can already be compressed to the final height, so that after the framework 6 has been pressed in, no insulating material 3 protrudes and would have to be turned away or removed in some other way. The simultaneous pressing, however, has the advantage that an additional manufacturing step for the Pre-compression is not necessary. In addition, the process of indenting itself results in a certain degree of compression, since part of the material is thereby displaced and lacking

Evasion is compressed to a considerable extent. Depending on the desired area of application, one or the other method can therefore be selected.

The press die 7 preferably has an openwork, lattice-like plate. As a result, air escaping during the pressing process can easily escape upwards. The proposed manufacturing process is not only suitable for insulating panels with a fixed size in the form of a panel, but also for continuous production for continuous insulating bodies to be cut later. For this purpose, the cell-like framework 6 is pressed in sections into the insulating material 3.

When using microporous insulating material 3, the manufacturing method according to the invention and the cell-like framework 6 with openings 5 used to create cross-connections prove to be particularly advantageous. The cross-linking via the large number of openings 5 in the cell walls 4 makes it much easier for the powdered insulating material 3 to remain in the insulating plates. Even with high vibrations, such as this. B. occur in the use of insulating panels with insulation in vehicle or aircraft construction (z. B. in turbine nacelles), no insulating material is vibrated out of the cells 2. As a result, a covering with an outer layer is generally unnecessary, so that a manufacturing step can be omitted. The manufacturing method according to the invention offers the advantage of simple, effective and rapid filling of the cell-like framework 6 with the microporous insulating material 3, which can also be fiber-reinforced, as long as the formation of cross-links across the cell boundaries is not impeded.

Claims

claims: 1. Insulating body with a cell-like frame and insulating material introduced therein, characterized in that the cell-like frame (6) has openings (5) in the walls (4) between individual cells (2). 2. Insulating body according to claim 1, characterized in that the insulating material (3) is a highly disperse, microporous powder, in particular pyrogenic silica or an airgel. 3. Insulating body according to claim 1 or 2, characterized in that the insulating material (3) has a fiber content in the range of 0.25 - 25%, in particular of about 5%. 4. Insulating body according to one of the preceding claims, characterized in that the shape of the openings (5) in the walls (4) is rounded, in particular circular. 5. Insulating body according to one of the preceding claims, characterized in that the shape of the openings (5) in the walls (4) is oval or angular (5 '). 6. Insulating body according to one of the preceding claims, characterized in that at least one opening (5) is present per cell (2), in particular two or more openings (5). 7. Insulating body according to one of the preceding claims, characterized in that at least one opening (5) is provided per wall (4). 8. Insulating body according to one of the preceding claims, characterized in that the basic shape of the cells (2) is honeycomb-shaped. 9. Insulating body according to one of the preceding claims, characterized in that the cell-like frame (6) consists of metal, fiber-reinforced cardboard or plastic. 10. Insulating body according to one of the preceding claims, characterized in that its surfaces are covered with a film. 11. A method for producing an insulating body with a cell-like frame, characterized in that the cell-like frame (6) is pressed into an insulating material (3). 12. The method according to claim 11, characterized in that the walls (4) of the cell-like frame (6) contain openings (5) according to one of claims 1 to 9. 13. The method according to claim 11 or 12, characterized in that the insulating material (3) is pre-compressed before the cell-like structure (6) is pressed in. 14. The method according to any one of claims 11 to 13, characterized in that the insulating material (3) is compressed to the final height before the cell-like structure (6) is pressed in.