JPH0159902B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a form of subdivided thermal insulation material that can be handled and processed, and to a process for making such a form.

BACKGROUND OF THE INVENTION Manipulable blocks of thermally insulating material have been made in a number of ways from mixtures of finely divided silica and reinforcing fibers with the optional addition of impermeable powders or binders. The strength of such blocks depends on the source, amount and type of binder used and on the use of heat treatment. A further important factor is the type of fiber used. The strongest blocks contain asbestos fibers, but the use of asbestos is undesirable due to health risks. Still, such blocks of thermally insulating material are too difficult to handle in the form of large sheets or panels because the bending strength of the material is low and the panels are prone to flaking and cracking. One method that has been used to overcome these problems is to include a thermally insulating material within a porous skin so that the skin is thinly bonded to the insulating material, thereby providing additional strength. The goal is to create a panel with a unique design. Panels made by this method have excellent handling properties, but are difficult to manipulate because machining and cutting break the bond between the insulating material and the porous skin. .

Problems to be Solved by the Invention It is an object of the present invention to provide a form of subdivided thermal insulation material that is easy to handle and process in the form of large sheets.

Means for Solving the Problems According to the invention, a reinforcing honeycomb structure and a subdivided thermal insulating material comprising microporous pyrogenic silica or silica aerogel, the subdivided thermal insulating material A thermal insulator characterized in that the residual pressure within the insulating material acts on the walls of the honeycomb structure and is compacted into the cells of the honeycomb structure to firmly hold the walls of the honeycomb structure in place. is provided.

Further, according to the present invention, a finely divided thermal insulation material containing microporous pyrogenic silica or silica aerogel is used, whereby the residual pressure within the thermal insulation material acts on the walls of the honeycomb structure. A method of making a thermal insulator is provided which comprises the step of compacting into the cells of a reinforcing honeycomb structure to hold the walls rigidly in place.

As used herein, the term "honeycomb" defines a cellular structure in which adjacent cells are separated from each other by thin membranes. Generally, the cell shape is hexagonal, but need not be; the term "honeycomb" as used herein includes triangular, other multi-sided and curved cells. The cells are generally of the same size and shape, but need not be.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below as illustrated in the accompanying drawings.

EXAMPLE The honeycomb structure shown in FIG. 1 is based on hexagonal cells, while the structure shown in FIG. 2 is based on triangular cells and the structure shown in FIG. 3 is based on circular cells.

The material of the honeycomb structure can be selected from a large number of materials including, for example, metal objects such as aluminum foil, inorganic materials such as laminate, organic materials such as plastic materials, textiles, or paper. The structure can also be made from a combination of several materials. Additives may be used if the material is inherently low in stiffness. For example, paper can be cured with phenolic resin. Although the material of the honeycomb structure can be a combustible material, the honeycomb structure providing the thermal insulation material is relatively non-flammable, as detailed below.

If thermally insulating materials with varying strengths are required, the dimensions of the cells of the honeycomb structure or the thickness of the material forming the honeycomb structure may be varied within selected ranges.

FIG. 4 illustrates one method of making a panel of thermally insulating material according to the present invention.

The honeycomb structure 10 has walls 12 of a mold or stamping die.
It is placed on a plane 11 surrounded by.
An amount of insulating material 13, approximately five times the volume occupied by the honeycomb structure, is then poured into a mold or die and spread over the honeycomb structure. The insulating material is compacted into the honeycomb cells by rams 14 fitted inside the walls 12 of the mold.

Air is drawn from the insulating material while solidifying it by using a ram 14 having a porous surface and by providing an opening 15 extending through the ram 14. However, in the case of small-area rams, it is appropriate to bleed air through a gap 16 between the ram and the die wall.

The ram moves to or near the surface of the honeycomb structure by compressing and packing the insulating material with the ram. After removing the pressure, the product consisting of a honeycomb structure containing packed insulating material is removed from the mold.

The insulating material may extend above the height of the honeycomb structure. If desired, excess insulating material can be brushed or scraped away to bring the insulating material flush with the honeycomb structure.

The finely divided insulating material can be a microporous insulating material, or other powders such as silica gel, volatilized silica, calcium silicate, vermiculite and nacre, and microporous materials such as alumina and titania. You can choose from a wide range of partitioned metal oxides.

Microporous materials are materials that have a lattice structure in which the average penetration dimension is less than the mean free path of the molecules of air or other gas in which the microporous material is located. As a result, the thermal conductivity is less than the molar conductivity of air or other gas with which the material is used. The lattice structure is created in a finely divided material by using powder with microscopic particles attached to each other in chains. Suitable powders for making this structure are usually finely divided silica into a form called silica aerogel or pyrogenic silica. The other powder is finely divided carbon black.

For high temperature applications, infrared opacity is preferred and may be necessary, and this can be accomplished by adding reflective metal powders or materials such as manganese oxide, chromium oxide, titanium dioxide, iron oxide, and zirconium oxide to the finely divided material. This can be achieved by adding various opaque materials such as metal oxides with high reflectivity. Also, infrared absorbing materials such as carbon black can be used.

In particular, the cell dimensions of the honeycomb structure are approximately 5 mm in diameter.
If the diameter exceeds mm, it is desirable to insert reinforcing fiber material into finely divided thermal insulation material. Such fiber materials can be ceramic fibers, glass fibers, cotton, rayon or other synthetic fibers, carbon fibers, or other fibers commonly used for reinforcing purposes.

Any substance added to the finely divided material must be thoroughly mixed with the finely divided material before the insulating material is poured into the mold.

When the finely divided insulating material comprises a microporous material, the method described above may be modified.

For example, when packing microporous silica, when the packing pressure is subsequently released, the volume of the packed silica may increase by as much as 20%. Therefore, the insulating material can be packed to the height of the honeycomb structure, but when the packing pressure is released, the insulating material expands above the honeycomb structure height, bringing the insulating material to the same height as the honeycomb structure. When it is necessary to flatten the surface, a flattening operation may be required.

This causes the elastic material 17 of the ram to deform when in contact with the honeycomb structure but will pack the insulating material below the surface height of the honeycomb structure when the insulating material is under its maximum packing pressure. We have found that this can be overcome by placing it in front of the user. When the packing pressure is relieved, the insulating material expands so that its surface is below the surface height of the honeycomb structure.

Another method of packing the insulating material below the surface level of the honeycomb structure is to position a flexible membrane between the surface of the insulating material and the ram and provide means for applying fluid pressure to the membrane. be. When the insulating material is packed and the ram is at or near the surface level of the honeycomb structure, flow pressure is applied to the membrane to further compress the insulating material to a height below the surface of the honeycomb structure. The thin film is passed through the opening of the ram.
Or it can be made of rubber or plastic material inflated with air fed through grooves formed in the surface of the ram. Alternatively, fluid may be permanently stored in the space between the membrane and the ram.

If desired, a second membrane may be located between the honeycomb structure and the surface of the mold on which it is supported. By inflating the second thin film, it is possible to control the filling of the insulating material from both sides of the honeycomb structure.

Obviously, with two rams it is possible to operate from both sides of the honeycomb structure. It is also possible to provide a skin on one side of the honeycomb structure before filling the honeycomb structure with insulating material.

It may also be desirable to support the honeycomb structure on a surface that is perforated to allow air to escape from the insulating material during packing, or to allow the insulating material to evacuate to assist with the packing process. be.

The insulating material can be compacted into the honeycomb structure with a density of 80-800 Kg/m ³ as required. The resulting product is sufficiently rigid to handle and can be processed to provide varying thicknesses along its length, fabricate desired shapes, and create holes. Processing can be performed using mechanical or laser cutting equipment.

To obtain relatively smooth edges when forming and contouring the holes, a skin 18 may be provided on one or both sides of the honeycomb structure, as shown in FIGS. 5 and 6. The skin may be bonded to the honeycomb structure and/or the insulating material by gluing. The skin can be metal, plastic, woven or non-woven fabric, paper, or other suitable sheet material. The product can also be coated with other surface treatments, such as paints or resinous materials, to improve handling.

If the skin is a rigid board, the product can be used, for example, as an insulating wall or as a fireproof door by simply gluing a reinforcing skin to the product. Microporous silica can sometimes be treated to provide some degree of water resistance, but is usually severely damaged by contact with water. However, a high degree of water resistance is obtained when the material of the honeycomb structure is impermeable to water by applying an impermeable skin of the product.

Products according to the invention are particularly useful where there is a need for lightweight, high strength thermal insulation materials with very low thermal conductivity. Heat is transferred to the product through the packed thermal insulation material and the walls of the honeycomb structure. Surprisingly, the walls of the honeycomb structure can be extremely thin, yet the resulting product has high strength and stiffness. This is because the walls of the honeycomb structure are held firmly in place by the compacted thermal insulation material, so that the strength of the resulting product is derived from both the honeycomb structure and the thermal insulation. I found out that it depends on the situation.

It was anticipated that the walls of the honeycomb structure might collapse when compressing and solidifying the thermal insulation material into the honeycomb structure. However, it has been found that very high mold pressures can be used to ensure that the thermally insulating material hardens as it is compressed and supports the walls of the honeycomb structure and does not distort the walls.

Because thin-walled honeycomb structures can be used, the heat transferred through the honeycomb structure is small, and the overall thermal conductivity of the product is low, especially if a material with low thermal conductivity is used for the honeycomb structure. Very small in line with the thermal conductivity of the insulating material.

It has been found that even if the material of the honeycomb structure is flammable, the product remains sufficiently non-flammable. This is especially the case when the thermally insulating material is in particular microporous silica. When the flame hits one surface of the product, the thermal insulation material prevents free access to oxygen, and the organic material of the honeycomb structure slowly carbonizes and oxidizes from the hot surface of the product. The low thermal conductivity of the product generally means that the cold side of the product is below the carbonization and oxidation temperature, so even if a part of the honeycomb structure is finally destroyed, the rest of the honeycomb structure Holding the thermally insulating material in place ensures that the product retains it perfectly and prevents heat penetration. If the honeycomb structure were to fracture on the hot side of the product, the residual pressure in the thermal insulation material would cause the material to expand and close the gap created by the disappearance of the honeycomb structure;
In this way, the remaining parts of the honeycomb structure close to the cold surface are protected.

FIG. 7 shows another method by which a panel of thermally insulating material according to the invention can be made.

FIG. 7 shows a honeycomb structure 20 on a flexible belt 21 supported by a number of rollers 22. FIG. An amount of insulating material 23 approximately five times the volume occupied by the honeycomb structure is injected into the honeycomb structure, and this structure
The insulating material is packed into the honeycomb structure by means of another belt 24 supported by rollers 25. The belt 24 is tilted relative to the belt 21 to provide progressive compaction of the insulating material. Belts 21 and 24 can be omitted if some means of initially retaining the insulating material in the honeycomb structure is provided. Furthermore, insulating material may be packed between a pair of rollers instead of multiple rollers as shown in FIG.

Alternatively, the insulating material can be packed into the honeycomb structure by vibration.

By forming the panels on one roller as shown in FIG. 8, circular, semicircular or arcuate handleable shapes can be created. As seen in FIG. 8, panel 30 is formed into a curved shape by rollers 31, 32 pressing the panel against forming roller 33. As seen in FIG. The panels are maintained in a curved configuration by applying a skin or additional skin to the radially inner surface of the panel. This skin should have little stretch, at least once it has been applied to the surface of the curved panel, in order to maintain the curvature of the panel. In this way, the bent profile also forms a honeycomb structure between the rollers 31, 32, 33 and the insulating material is sufficiently compressed and solidified in the cells of this honeycomb structure, so that the bent profile It can also be made by applying a skin to the radially inner surface. This skin can be applied either before or after the insulating material is compacted into the honeycomb structure.

Another way to form a panel between rollers is to
A nearly arcuate shape can be formed by having a panel 40 with at least the bottom surface having a flexible covering of, for example, glass fiber material, as shown in FIGS. 9 and 10. The upper surface may also be provided with such a coating. The V-shaped groove 41 is machined on the top surface of the panel and extends to near the bottom surface. FIG. 10 shows the panel 4 bent along the line of the groove 41.
0, so that the panel is V-shaped and can be used, for example, to insulate small diameter pipes. If desired, an adhesive may be applied to the grooves and, in addition, or in addition, a coating may be applied to the bent panel to maintain it in the folded condition.

Panel 42 shown in FIGS. 11 and 12
is similar to the panel shown in FIGS. 9 and 10, except that a number (three in the illustrated example) of grooves 43 are formed in the top surface of the panel. When the panel of FIG. 11 is bent along the line of groove 43 as shown in FIG.
As can be seen by comparing the figure and FIG. 12, the cross section has become more arcuate. A similar process was carried out in the 9th
11 as described above with respect to FIGS.
It can be applied to the panels shown in Figures and Figure 12.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the reinforcing honeycomb structure used in the present invention, FIG. 2 is a diagram showing another example of the reinforcing honeycomb structure used in the present invention, and FIG. 3 is a diagram showing another example of the reinforcing honeycomb structure used in the present invention. FIG. 4 is a diagram illustrating a method of manufacturing a thermal insulation material according to the present invention; FIG. 5 is a diagram illustrating an example of a thermal insulation material according to the present invention; FIG. Figure 7 shows another example of the thermal insulation material according to the invention, Figure 7 shows another method of making the thermal insulation according to the invention, and Figure 8 shows a bent body of the thermal insulation according to the invention. Figure 9 shows a panel with one groove machined on one side; Figure 10 shows the panel of Figure 9 corresponding to the panel folded along the groove line; Fig. 11 shows a panel with many grooves machined on one side, and Fig. 12 shows the panel 11 folded along the line of the grooves.
FIG. 3 is a diagram showing a panel of the figure. 10...honeycomb structure, 11...plane, 12
... Wall, 13 ... Insulating material, 14 ... Ram, 15
... opening, 16 ... gap, 17 ... elastic material, 18 ... skin, 20 ... honeycomb structure,
21...Belt, 22...Roller, 23...Insulating material, 24...Belt, 25...Roller, 30...
...Panel, 31, 32, 33...Roller, 40...
...Panel, 41...Groove, 42...Panel, 43...
…groove.

Claims (1)

[Scope of Claims] 1 Consists of a reinforcing honeycomb structure and a finely divided thermal insulation material containing microporous pyrogenic silica or silica aerogel, the finely divided thermal insulation material having a structure in which the residual pressure within the thermal insulation material is reduced. Thermal insulation that is compacted into the cells of the honeycomb structure to act on the walls of the honeycomb structure to hold the walls of the honeycomb structure rigidly in place. 2. The thermal insulator according to claim 1, wherein a skin is adhered to one or both sides. 3. The thermal insulator according to claim 2, wherein the skin is made of metal, plastic, woven fabric, non-woven fabric, or paper. 4. The thermal insulator according to claim 1, wherein the honeycomb structure is made of metal, inorganic or organic material. 5. The thermal insulator according to claim 4, wherein the honeycomb structure is paper. 6. The thermal insulator according to claim 5, wherein the paper is cured with a phenolic resin. 7. The thermal insulator of claim 1, wherein the subdivided thermal insulating material comprises an infrared opaque material. 8. The thermal insulator of claim 1 or 7, wherein the subdivided thermal insulation material comprises reinforced fiber material. 9 A subdivided thermal insulation material comprising microporous pyrogenic silica or silica aerogel is prepared by residual pressure within the thermal insulation material acting on the walls of the honeycomb structure to hold the walls of the honeycomb structure rigidly in place. A process for producing a thermal insulator consisting of a step of compressing and solidifying into the cells of a reinforcing honeycomb structure. 10. The method of manufacturing a thermal insulator according to claim 9, wherein the compaction and solidification are performed by one or more rollers.