Method for Manufacturing Vacuum Insulation Panels

Abstract

The invention relates to a method for manufacturing vacuum insulation panels (1) with a fiber core (3), comprising the steps of: providing a core blank of fibers, arranging foil sections on large faces of the core blank, compressing the core blank to a predetermined thickness for forming the core (3), wherein in the compression step the core blank is arranged between the foil sections, wherein the mechanical compression of the core (3) is maintained until the foil sleeve (2) is sealed, and wherein the compression step is performed at the place of manufacture at room temperature without thermal impact, connecting the foil sections for forming the foil sleeve (2), wherein a partial section of the foil sleeve (2) still remains open, evacuating the foil sleeve (2) enveloping the core (3) up to a pressure of <1 mbar, and complete closing of the foil sleeve (2), wherein the foil sleeve (2) is made of a plastic composite foil. This method distinguishes itself by the fact that the mechanical compression is carried out at a pressure of greater than 1 bar. Thereby a vacuum insulation panel (1) is obtained which can be manufactured with low expenditure and without the insulation effect suffering therefrom.

Claims

1-12. (canceled)

13. A method for manufacturing vacuum insulation panels with a core of fibers, comprising the steps of: providing a core blank of fibers; arranging foil sections on faces of the core blank; compressing the core blank to a predetermined thickness for forming the core, wherein, in the compressing step, the core blank is arranged between the foil sections, and is mechanically compressed therebetween, wherein the mechanical compression of the core is maintained until a foil sleeve is sealed, and wherein the compressing step is performed at room temperature without thermal impact; connecting the foil sections for forming the foil sleeve, wherein a section of the foil sleeve remains open; evacuating the foil sleeve enveloping the core up to a pressure of less than 1 mbar; and completely closing the foil sleeve, wherein the foil sleeve is made of a plastic composite foil, and wherein the mechanical compression is performed at a pressure of greater than 1 bar.

14. The method according to claim 13, wherein said mechanical compression is performed at a pressure of 2 to 10 bar.

15. The method according to claim 14, wherein said mechanical compression is performed at a pressure of 4 to 8 bar.

16. The method according to claim 15, wherein said mechanical compression is performed at a pressure of 6 bar.

17. The method according to claim 13, wherein the fibers do not comprise a binder subject to disintegration in a vacuum.

18. The method according to claim 13, wherein the fibers do not comprise an organic binder.

19. The method according to claim 13, wherein the fibers are organic fibers of a thermoplastic material.

20. The method according to claim 19, wherein the thermoplastic material is selected from the group consisting of polyethylene, polyamide, polypropylene and combinations thereof.

21. The method according to claim 13, wherein the fibers are inorganic fibers.

22. The method according to claim 21, wherein the inorganic fibers are selected from the group consisting of mineral wool, glass wool, rock wool, textile glass fibers, and combinations thereof.

23. The method according to claim 22, wherein the mineral wool comprises fibers with a fineness of fibers corresponding to a micronaire of less than or equal to 20 l/min.

24. The method according to claim 22, wherein the mineral wool comprises fibers with a fineness of fibers corresponding to a micronaire of less than or equal to 15 l/min.

25. The method according to claim 21, wherein the step of providing the core blank comprises: drying the inorganic fibers of the core blank up to a residual moisture of less than 0.1%.

26. The method according to claim 25, wherein the step of drying is performed at a temperature ranging at least 200 K below the softening temperature of the fibers.

27. The method according to of claim 13, wherein the step of providing the core blank comprises: providing a felt web of fibers, cutting the felt web to a predetermined finished size, and stacking a plurality of cut felt web sections.

28. The method according to claim 27, wherein said felt web fibers have a weight per unit area of between 800 g/m.sup.2 and 2500 g/m.sup.2 prior to drying the fibers.

29. The method according to claim 13, wherein the step of providing the core blank comprises: providing a plurality of felt webs of fibers, stacking the plurality of felt webs one upon each other, and cutting the felt web stack to a predetermined finished size.

30. The method according to claim 29, wherein said felt web fibers have a weight per unit area of between 800 g/m.sup.2 and 2500 g/m.sup.2 prior to drying the fibers.

31. The method according to claim 13, wherein the step of evacuating is performed up to a pressure of less than or equal to 0.05 mbar.

32. The method according to claim 31, wherein the step of evacuating is performed up to a pressure of less than or equal to 0.01 mbar.

Description

[0033] The method according to the invention will be explained in detail in the following by means of embodiments. There show:

[0034] FIG. 1 a schematic representation of a vacuum insulation panel manufactured according to the inventive method; and

[0035] FIG. 2 a flowchart of the method according to the invention.

[0036] In FIG. 1 a vacuum insulation panel 1 is shown schematically in section. It comprises a foil sleeve 2 entirely enclosing a core 3.

[0037] In the embodiment according to FIG. 1 the foil sleeve 2 is designed as a plastic composite foil and comprises a two-layer structure of a HDPE layer with a thickness of 150 m and an aluminum layer with a thickness of 6 m. It is formed of two foil sections 2a and 2b which are welded to one another in lateral edge regions of the core 3 at projecting edge sections. A vacuum in which the internal pressure is set to approximately 0.01 mbar is available inside the foil sleeve 2. Contrary to the schematic representation in FIG. 1, the foil sleeve 2 is therefore in close contact with the core 3 in practice, wherein the core 3 serves as a support body against the external pressure. The core 3 consists of a binder-free mineral wool, here glass wool.

[0038] In the following, a method for manufacturing the vacuum insulation panel 1 will be explained in detail by means of the flowchart illustrated in FIG. 2:

[0039] First of all, a core blank is produced. For this purpose, a felt web of binder-free mineral wool is provided. This felt web is typically supplied in a coil shape. As a rule, a foil is available between the winding layers which prevents mingling of the fibers of the layers among each other and thus contributes to maintaining the present weight per unit area. In the illustrated embodiment this felt web has a weight per unit area of approximately 2500 g/m.sup.2 and consists of fibers with a fineness with a micronaire of 12 l/min.

[0040] The mineral wool of this felt web is then dried, if required, until the residual moisture has a value of less than 0.1%. To this end, the felt web is impacted with a temperature of approximately 150 C. for a period of approximately two minutes. This drying step of the mineral wool can be performed at the felt web as such as well as also at cut felt web sections.

[0041] The cutting of the felt web is performed here to a predetermined finished size which orients itself at the typical dimensions of such vacuum insulation panels. Usual dimensions lie in the range of between 600 mm*300 mm and 1800 mm*1200 mm Cutting may be performed with suitable known methods such as, for instance, with band saws, rotating knives, water jet cutting, punching, or the like.

[0042] In the present embodiment, a plurality of felt web sections that have been cut in this manner, here three felt web sections that have been cut in this manner, are stacked on top of each other until sufficient mineral wool material, i.e. the layer required for producing the desired insulation thickness, is available.

[0043] Then, so-called getter materials, drying agents or the like are added to achieve particular functional improvements of the material of the core. These materials may be added as loose powder, sheets, etc.

[0044] Subsequently, the foil sections 2a and 2b are arranged as an enclosure or envelope at the upper and lower sides of the core blank thus formed.

[0045] In the next step, the core blank available between the two foil sections 2a and 2b is subjected to compression at a pressing power of approximately 6 bar. This compression is performed without thermal impact, that means without any heating of the material of the core, and thus at room and/or ambient temperature at the place of manufacture. In the course of this, a thickness of the core is set to approximately 25 mm and a density of the core 3 is set to approximately 300 kg/m.sup.3.

[0046] In a further step, the foil sections 2a and 2b are first of all welded to each other at three side edges, as may be seen from the projections in FIG. 1. The distance of the welding seam from the core 3 is restricted to few millimeters and amounts here to less than 5 mm.

[0047] While the foil sleeve 2 is thus closed at three sides, the core 3 remains under the compression pressure applied by the mechanical compression and keeps its predetermined thickness.

[0048] In this constellation the core 3 is placed in a vacuum plant along with the foil sleeve 2 and the interior of the foil sleeve 2 is evacuated to an internal pressure of approximately 0.01 mbar. The core 3 remains under the compression pressure until the foil sleeve 2 is closed or sealed.

[0049] In a final step the foil sleeve 2 is then also closed at the remaining open side, so that the side edges of the foil sections 2a and 2b are then welded to each other completely.

[0050] Since the desired vacuum is then available in the interior of the foil sleeve 2, the mechanical compression thereon may subsequently be cancelled. It is, however, preferred to maintain the mechanical compression until the pressure balance, i.e. the flooding of the vacuum chamber. By this measure it is possible to avoid a bulging in the vacuum which is possibly caused by restoring forces of the core material.

[0051] With the parameters set there results a vacuum insulation panel 1 with a product thickness of approximately 30 mm and a density of the core 3 of approximately 250 kg/m.sup.3.

[0052] The transfer of the core blank provided with the foil sections 2a and 2b from one processing station to the next one is performed here via suitable movable or slidable transport belts or roller tables as well as sheets or plates between which the arrangement is transported by means of a feeder or a slider. In particular in the region of the vacuum plant these processes may be performed in a robot-controlled manner

[0053] The vacuum insulation panel 1 thus formed is then ready for transportation and may be delivered.

[0054] In the explained embodiment, the manufacturing method is typically performed discontinuously outside the manufacturing line. Under certain conditions, for instance, if a felt web with suitable parameters (weight per unit area, etc.) can be produced directly, integration into a continuously operated manufacturing line is, however, also possible.

[0055] In addition to the embodiments explained, the invention allows for further design approaches.

[0056] Thus, instead of the plastic composite foil with a two-layer structure, also a composite foil with another structure may be used for the foil sleeve 2. In another embodiment, for instance, a multi-layer plastic composite foil with, for instance, multiple aluminizing is used. In the case of minor requirements to the duration of functioning of few years, also a simple multi-layer plastic foil may be used.

[0057] Glass wool is provided here as a material for the core 3; instead, however, also rock wool, cinder wool or other inorganic fibers such as textile glass fibers, etc. may be used. Alternatively, or additionally, organic fibers may also be used.

[0058] Furthermore, it is not stringently necessary that the material of the core 3 is subjected to a drying step. The degree of drying may also vary in correspondence with the requirements for the case of application, if necessary. Accordingly, the parameters for the drying step may also be adapted where required.

[0059] The providing of the core blank may also be performed in some other way than the one explained above. It is in particular not necessary to provide a felt web in coil shape. It may, for instance, also be supplied directly from a forming section in which the felt web is produced from the mineral fibers just generated. The stacking of a plurality of felt web sections may possibly also be renounced. Alternatively, it is also possible to fold a felt web in a suitable manner.

[0060] The addition of getter materials, drying agents or the like for achieving particular functional improvements of the material of the core may be performed on the felt web or on a felt web section prior to stacking, so that the getter materials are arranged in the stack and not on a surface. This has the advantage that the getter materials are not in direct contact with the foil sleeves.

[0061] In the illustrated embodiment the evacuation of the vacuum insulation panel 1 or 1 is performed up to an internal pressure of 0.01 mbar. It is, however, also possible to admit a greater internal pressure of, for instance, 0.05 mbar or 0.1 mbar if the application purpose allows so. On the other hand, it may also be expedient for specific cases of application to lower the internal pressure even further to 0.001 mbar, for instance.

[0062] In the illustrated embodiments the core 3 is compressed with a pressing pressure of 6 bar in the compression step. Depending on the case of application it is, however, also possible to preset another pressing pressure in the range of 2 bar to 10 bar, whereby the corresponding thicknesses and densities of the core 3 will set during the pressing process.

[0063] Likewise, it is not necessary to use fibers with the indicated fiber fineness corresponding to a micronaire of 12 l/min For many applications it might also be sufficient to use coarser fibers with a micronaire of less than 20 l/min.

[0064] The weight per unit area of the felt web prior to the drying step may also vary as a function of the requirements given.