DE2606159A1 - THERMAL INSULATION MATERIAL AND DEVICE FOR ITS PRODUCTION - Google Patents

Abstract

In the multi-layer insulation material, highly reflecting layers and layers of open-pored foam are arranged alternately. Due to the use of this combination of materials, the insulation value is considerably increased owing to the open porosity of the foam and the associated reduction in the radiant heat exchange between the highly reflecting layers. The multi-layer insulation material can form the core of an insulation element. In this case, the sealed core can be filled with an insulating gas. The shell consists of another insulation material.

Description

Thermal insulation material and device for its manufacture.

Thermal insulation materials are known in many forms.

For example, layers of glass wool, rock wool, inorganic and organic fibers, plastic foam or naturally occurring substances, for example cork is used.

The invention aims to create improved thermal insulation materials, which in particular enable a very high thermal insulation with a small thickness and also meet the respective mechanical and thermal requirements, easily are easy to handle, have a low weight and do not require too much effort.

To this end, the invention provides that the thermal insulation material from any number of alternating layers of highly reflective material Material and spacer material.

The heat transfer between two parallel plates takes place in Form of radiation transport, heat conduction and convection. To achieve a possible With good thermal insulation, each of the mentioned components must be as small as possible. The invention combines the process of radiant heat exchange known in thermodynamics with the low thermal conductivity of certain materials. So far only in complicated Constructions or improperly used high reflectivity property certain substances, for example aluminum, gold or silver in coated or pure form becomes simple, manageable with the insulation material according to the invention Wisely exploited. The use of the highly reflective surfaces is reduced the radiant heat exchange is particularly effective, and the more so, the greater the temperature gradient is between the facing plates or layers. The spacer material should meet the following requirements at the same time as possible. In the ideal case, it may no obstacle to the exchange of radiation between the reflecting surfaces must therefore be transparent for thermal radiation.

To prevent convective heat transport, the distance between the reflective layers, i.e. the thickness of the gap, is small be, and the spacer material must ensure that this small gap is also kept under the loads occurring in practice will. Included however, the spacer material must not form any thermal bridges to ensure heat conduction to keep it as small as possible. On the one hand, this requires a spacer material, the one that is as possible has low thermal conductivity and, on the other hand, the two layers are different Temperature bridged only with the smallest possible cross-sections with a long path. Finally, the spacer material should show favorable mechanical properties, in particular be flexible and also have the necessary temperature stability.

The invention recommends reticulated material as a particularly suitable spacer material Material made of polyurethane, polyvinyl chloride, polyethylene and similar plastics. Reticulated material is understood to mean a hardened material foam, in which the walls of the vesicles have burst out and only a framework of material remains remains. The pores should take into account the respective intended use be as large as possible. The limits are due to the material strength and also due to it given that at a certain thickness of the reticulated material above a certain mean pore size the cohesion of the material is lost. A an appropriate value for the mean pore size is 3 to 5 pores per cm.

Values for the thickness of the spacer material are given below specified. Reticulated material is practical for small thicknesses and large pores transparent. Be reticulated Plastics used in are transparent to a certain degree for thermal radiation, so can despite the scaffolding a practically undisturbed radiation exchange take place, whereby the heat transfer becomes minimal due to radiation transport. The framework of the reticulated material is very thin, which means that only minor thermal bridges are formed.

The sum of the contact areas is less than 0.5 of the respective Total area. In addition, the way in which the heat in the framework material is from a Layer must be passed to the other, much larger than the gap thickness, since it is very unlikely that two points of contact are directly opposite each other lie. In addition to the good properties in terms of radiation exchange, the reticulated material has the advantage that the convective flow in the space is additionally hindered and thus the heat exchange between the layers the convective portion is reduced.

The spacer material can also be made of a loose mesh or inorganic Fibers, such as fabrics, consist of fibers, in particular / mineral fibers or glass fibers. Even with such a material, the requirements explained above for the Distance material are met. The temperature resistance is also better. For use at very high temperatures, asbestos strips can be used as spacer material be used.

In turn, it must be ensured that the proportion of material of The space in between remains as small as possible in relation to the total volume. An improvement in this direction can also be achieved with each spacer material by that the layers are partially punched out.

The reflective layers and spacer material can do with many Applications can be placed loosely on top of one another, especially when outer casings or additional covers to secure the position. In many other cases however, a material is desired that by itself has the necessary cohesion. Therefore, the invention recommends in its further development that the spacer layers welded or glued at the points of contact with the reflective layers are.

When using reticulated foam as spacer material and from Aluminum foil as reflective layers can be the connection instead of welding can also be done by softening the foam with a solvent. After hanging up of the foam on the aluminum foil, the solvent evaporates, and the original The state of the foam and the connection are established.

In the case of insulation with low temperature differences, the heat transfer plays a role radiation only plays a subordinate role. Then you can without any significant deterioration the heat insulation the highly reflective layers by little or not at all reflective layers, for example through plastic films can be replaced without reflective vapor deposition. The prevention of heat transfer by convection remains because of the subdivision into thin layers and in addition obtained through the spacer material.

Depending on the intended use, the thermal insulation material according to the invention from a single layer of a spacer material with two adjacent reflective layers exist, or there can be several such insulation layers be formed by alternating reflective layers and spacer material be strung together. There is also the possibility of layer sequences with different spacer material and different reflective layers to be used, especially when very high temperature differences occur.

The case in which the spacer material should be mentioned as a special feature is covered with a reflective layer on only one side. Such a material can in roll form, for example, for the insulation of pipes and other objects serve by wrapping.

A further development of the invention provides that a piece of the thermal Isolation material is hermetically sealed. Then the insulation element formed in this way can to the further reduction in heat exchange through conduction with a gas of low thermal conductivity, such as carbon dioxide or freons if necessary, be reduced further at reduced pressure. Even with a filling with air, the heat conduction can be made smaller by partial evacuation.

There are several options for creating the hermetic seal Options. So outer metal foils can be arranged overlapping and welded or soldered. Outer foils, one side with a thermoplastic Layer are laminated, can also be welded. Instead of a lamination with a thermoplastic layer can also be a tape of thermoplastic material be inserted between the edges of the outer foils to be connected. If that If the spacer material is reticulated foam, this foam can be used at the same time for welding the foils instead of a tape made of thermoplastic material use.

A further development provides for the hermetically sealed insulation elements the invention a subdivision into parts. The subdivision can for example by welding the film layers to the reticulated Foam of the spacer material. The subdivision leads to a more flexible execution the insulation elements. When filled with a gas of low thermal conductivity results There is also the advantage that, in the event of damage, only the respective part leaks.

A piece of the insulation material according to the invention, which optionally is hermetically sealed according to the above explanation, can in further training of the invention provided as a core with a shell made of conventional insulation material be. The shell consists for example of polyurethane or polystyrene foam. if the core, as described above, is divided into pieces, so it is for the practical application, e.g. for attaching kinks, appropriate, when the sections on the outer shell made of conventional insulation material are designated.

To glue the core directly to a base or with any To be able to combine material, it can be provided that the core with a self-adhesive Layer is equipped.

Insulations for pipes can optionally be in the form of half-shells can also be produced in combination with conventional insulation foams. With big ones Flexible self-adhesive mats with a Protective cover be surrounded.

The drawings show: FIG. 1 a cross section through an exemplary embodiment an insulation material according to the invention; Fig. 2 schematically plant for continuous Manufacture of the insulation material according to the invention; Fig. 3 schematically a Cross section through a thermal insulation material according to the invention, which on the system according to Fig.2 has been produced, the thermal insulation material 1 comprises two layers 2 of reticulated polyurethane foam. That The structure of the coarse-pored foam forms a network of fine rods that only very small contact surfaces 3 the miv highly reflective layers 1 on the outside of the insulation material and between the two layers 2. The reflective Layers 1 consist of aluminum foil, but can also consist of plastic foils vapor-deposited reflective layer made of aluminum, silver or gold be.

Fig. 2 shows a plant for the continuous production of a thermal Insulation material according to the invention, a cross section of this material in Fig. 3 is shown. Both the reticulated foam material and the reflective layers are introduced into the system from roll-off stations 4 and 5, respectively. The reflective layers are in a heating section 6 to an elevated temperature brought in such a way that when using a suitable base material, for example Polyethylene, polyvinyl chloride, polyurethane, etc. are the material of the intermediate layers welded to the reflective layers at the points of contact in a pressing section 7 will.

In a subsequent device 8 can be used as protection for the insulation material from further unwinding stations 9, a plastic film is placed over the outer layers and welded at the overlap points. The now closed room is filled with a gas of low thermal conductivity depending on the intended use or evacuated.

Used as a spacer material and as a protective layer material, it is non-weldable Material used, take the place of the heating zones 6 or the welding zones 8 gluing devices. Only as small an area as possible may be included Be covered with glue so as not to impair the exchange of radiation.

The insulation material can be lo, with the help of a cutting device which has longitudinal and transverse cutting, to be cut to size, so that further processing in roll or plate form is possible.

In the illustrated Ausführungsbeispiei for the insulation material according to In Fig. 3, the core 11 consists of alternating layers 12 of reticulated foam and reflective layers 13. The cladding 14 of the core 11 is made of conventional Insulation material, for example polyurethane or polystyrene foam, is formed.

As stated above, the distance between the reflective Layers 13, that is to say the thickness of the layer 12, remain so small that the heat transport remains negligibly small due to convection. The limit depends on the type of the gas in the gap, the operating pressure, the temperature difference between two Layers and the location of the gap (vertical, horizontal, etc.). As an an example results for air as a gas at atmospheric pressure, a temperature difference between two layers of 200C in any position that the distance should be less than 5 mm target. The convective part of the heat transport is then less than 10 3. With increasing Temperature difference, the layer spacing must be reduced.

In general, instead of the layer thickness, a requirement can be made for air, for example Here: Ra Rayleigh number, g acceleration due to gravity, ß volume expansion coefficient, g layer thickness, tT temperature difference between two layers, a temperature diffusivity, V kinematic viscosity.

The following table gives several examples of measured resp. calculated values for the mean thermal conductivity of layer materials according to of the invention.

T A B E L L E Thickness d. Surrounding Middle Distance Shift Individual Total training container conductivity material material layer thickness gas temp. temperature (W / m °) (per cm) (mm) (mm) (° C) (° C) Polyurethane Aluminum 5 30 Air 15 25 0.029 1) 0.025 2) 4 pore film polyurethane aluminum 5 30 Freon 12 15 25 0.012 2) 4 Pore film polyurethane aluminum 5 175 air 20 -165 0.020 2) 4 pore film asbestos Aluminum 5 175 Air 35 300 0.048 2) 2 pore foils 1) measured 2) calculated

Claims (1)

Claims 1) Thermal insulation material, characterized through any number of alternating layers of highly reflective Material (1) and spacer material (2). 2) insulation material according to claim 1, d a d u r c h e k e n n z It is n e ect that the spacer material consists of reticulated foam (2). 3) insulation material according to claim 1, d a d u r c h e k e n n z e i n e t that the spacer material is made up of a loose mesh or fabric Fibers, in particular inorganic fibers such as mineral fibers or glass fibers. 4) insulation material according to claim 1, d a d u r c h g e k e n n z It is clear that the spacer material is made from strips of asbestos. 5) insulation material according to one of the preceding claims, d a it is indicated that the spacer layers are partially punched out are. 6) insulation material according to one of the preceding claims, d a it is indicated that the spacer layers (2) at the points of contact (3) are welded to the reflective layers (1). 7) insulation material according to one of the preceding claims, characterized adurchgekennzeichne t that the spacer layers at their points of contact with the reflective layers are glued. 8) insulation material according to one of the preceding claims, characterized by a coating with a protective layer that completely covers the material from the outside concludes 9) insulation material according to one of the preceding claims, d a d It is indicated that the reflective layers are replaced by demarcation layers of a non-reflective type are replaced. lo) insulation material according to one of the preceding claims, d a d u r c h g e k e n n n z e i c h n e t that a piece of material (11) is hermetically sealed is. 11) Insulation material according to claim lo, d u r c h e k e n n n notices that the piece of material (11) with a gas of low thermal conductivity is filled. 12) insulation material according to claim 10 d a d u r c h g e k e n n notices that the piece of material (11) is used to reduce the thermal conductivity is partially evacuated. 13) insulation material according to one of claims 1o to 12, d a d u c h e k e k e n nn n n e i n e t that the piece of material is divided into pieces is. 14) insulation material according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t a that a piece of material as core (11) with a sheath (14) made of conventional insulation material is provided. 15) insulation material according to claim 13 and 14, d a d u r c h g e k e n n n e i n g e i n e t, that the partial cores on the outside the shell are designated. 16) insulation material according to one of the preceding claims, g I do not have a self-adhesive equipment. 17) Device for making the thermal insulation material according to one of the preceding claims, characterized by alternately one behind the other arranged unwinding stations (5,4) for the reflective and the spacer material, Heating devices (6) which apply the reflective material to one for welding heat the necessary temperature, press sections downstream of the heating devices (6) (7), in which the materials are welded, the last pressing section (7) downstream longitudinal and cross cutting devices (1o), which the insulation material Cut to the required size, unwinding stations (9) for protective layer material and a device (8) for welding the protective layer material and for Filling a heat conduction inhibiting gas. 18) Vori'ichtung according to claim 15, d u r c h g e k e n n z e i c h n e t that the heating devices have been replaced by gluing devices. 18) Device according to claim 15, d a d u r c h e k e n n z e i c h n e t that the heating device is part of the pressing section (7).