The present invention relates to a layered thermal insulation material, comprising at least one layer of bubble foil and at least one layer of reflective foil, which at least one layer of bubble foil is provided with a plurality of fluid-filled bubbles on at least one side thereof, and which at least one layer of reflective foil is arranged to abut the side of said at least one layer of bubble foil that is provided with bubbles.

A great number of many different insulation materials are available for insulating buildings. The type of building and the use of the insulation material in or on the building determine what insulation materials are most suitable, and what the thickness of said insulation materials should be. As a rule, insulation materials must preferably have a high insulating value or R-value, they must be flexible in order to enable easy handling thereof, and in addition they must be sufficiently robust and durable.

In the construction industry, use is frequently made of glass wool or rock wool blankets and panels. Advantages of these materials include their relatively high R-vafue, their easy handling and their relatively low cost price. Rock wool and glass wool are readily commercially available, in many cases they are already provided with a vapour-retarding or vapour-resistant layer, in some cases they are provided with a reflective coating. The vapour-retarding layer is needed to prevent condensation in the insulation material as a result of the temperature difference between the heated space and cold outside air. Condensation leads to an accumulation of moisture in the insulation material, which has a negative effect on the insulating value and which, moreover, is undesirable in connection with the large number of moisture-related problems that can occur in buildings, such as (wood) rot, fungi and/or moulds, and vermin.

British patent application GB 2,441 ,636 discloses an insulation panel for forming a door of a cold store, which panel has a layered structure. The layered structure comprises, inter alia, a bubble foil which is provided with a metal foil on both sides. A drawback of the panel disclosed in the aforesaid document is the complex layered structure thereof, which, in addition to said bubble material and said metal foil, consists of a (thick) layer of a loose fibre material clamped between a multitude of different layers. The panel disclosed in GB 2,441,636 is furthermore only available as a panel, and it is not suitable for being marketed as a flexible blanket. After all, the sides of the material disclosed in GB 2,441 ,636 need to be stiffened because of the loose structure of the panel, which consists of a thick layer of loose fibres. If the sides are not stiffened, the material of which the panel is made will fall apart into the various layers. Although the bubble material, the metal foil and adjacent layers can be bonded together, this is not possible with the loose internal fibre structure of the panel. Because of this limitation, the required stiffening at the edges, it is not possible to cut the panel without the panel falling apart. Although the panel known from GB 2,441 ,636 no doubt provides a high R-value, it is thus less suitable for use as an insulation blanket or insulation material to be used in the construction of buildings. Another drawback of the material disclosed in GB 2,441 ,336 is the use of a metal foil. Metal foils are vulnerable, and will tear even when subjected to small forces or low-force impacts. Because of this, the use of insulation blankets or insulation foil provided with a metal foil in the construction of buildings is problematic. Such foils must usually be installed at places which are difficult to reach, and often they are fixed to, for example, a wooden rail construction by means of staples or nails. A vulnerable metal foil makes this problematic. It is an object of the present invention to provide a thermal insulation material having a high insulating value which is easy to handle during construction, which is suitable for use as an insulation blanket, and which is sufficiently robust to enable easy use thereof in buildings.

In order to accomplish that object, the invention provides a layered thermal insulation material comprising at (east one layer of bubble foil and at least one layer of reflective foil, which at least one layer of bubble foil is provided with a multitude of fluid-filled bubbles on at least one side thereof, and which at feast one layer of reflective foil is arranged to abut the side of said at least one layer of bubble foil that is provided with bubbles, characterised in that said at least one layer of reflective foil comprises a plastic foil.

The use of a plastic foil as a reflective layer makes the insulation material robust, so that it can readily withstand impacts and, in addition, is easy to handle. Furthermore, plastic generally has a low thermal conduction coefficient, so that it contributes to the high insulating value of the insulation material. In addition to that, plastic is a very flexible material which is capable of imparting a certain elasticity to the insulation material. Another important advantage is the fact that plastic foils have vapour-retarding or even vapour-resistant properties, so that condensation in the interior of the layered thermal insulation material can be prevented.

By placing the reflective foil against the bubble foil in such a manner that the layer of reflective foil abuts the side of said at least one layer of bubble foil that is provided with bubbles, the plastic reflective layer seals the space between the bubbles of the bubble foil, so that a compact cell structure is formed between the bubble foil and the reflective foil. Said cells are formed on the one hand by bubbles of the bubble foil and on the other hand by the space between the bubbles, which is sealed with said at least one layer of reflective plastic foil. Each of said cells is furthermore filled with a fluid, for example air. As is known, a stationary layer of air has excellent insulating properties. The bubble foil is preferably made of polyethylene (PE). If the thickness of the material of which the bubble foil is made is suitably selected, the foil will be transparent to infrared (IR) radiation. The IR radiation will be reflected by the reflective layer in that case and can exit the insulation material.

According to another embodiment, the layered insulation material comprises at least one first layer of bubble foil and at least one second layer of bubble foil, which at least one layer of reflective foil is arranged to abut a bubble side of both said at least one first layer of bubble foil and said at least one second layer of bubble foil. This configuration provides an even more complex cell structure consisting of the bubbles of the first layer of bubble foil, the space between the bubbles of the first layer of bubble foil and the layer of reflective layer foil, the space between the layer of reflective foil and the second layer of bubble foil, and the bubbles of the second layer of bubble foil. Because of this configuration, the layered insulation material has a very advantageous insulating value.

In a preferred embodiment, the layered insulation material comprises at least four layers of bubble foil. In the course of the development of the layered insulation material it was found that a layered insulation material according to the invention comprising eight layers of bubble foil has an R-value that equals 5. A bubble foil having a thickness of 4 mm was used in this case. The insulation material thus has a thickness of 32 mm. By way of comparison, to obtain an R-value of 5, using glass wool, a glass wool blanket having a thickness of 250 mm is needed.

To provide the reflective properties of said at least one layer of reflective plastic foil, the foil according to one embodiment thereof is provided with a reflective coating on at least one side. According to another embodiment of the invention, said at least one layer of reflective foil is provided with a reflective coating on both sides. The reflective coating, which provides the reflective properties, ensures that radiant heat (infrared radiation) is reflected by the thermal insulation material. Loss of heat resulting from the emission thereof from the hot space to the surrounding cold outside air can thus be effectively prevented. If said at feast one layer of reflective foil is even provided with said reflective coating on either side, and has reflective properties on both sides, therefore, transfer of heat caused by radiation can be prevented on both sides. This is important, for example, in order to ensure that the space which is insulated with the layered insulation material according to the invention will remain warm in winter and can be kept cool in summer. If the _, space is heated in winter, transfer of radiant heat from the warm space to the cold outside a is prevented as a result of the presence of the reflective coating on the sides of the warm space. On the other hand, if the outside air is hot, for example in summer (for example 30 "C), transfer of radiant heat from the outside to the inside is prevented, and the unheated interior space can be kept cool longer. The reflective coating may comprise a metal. Metals which are suitable for use in the reflective coating may for example comprise elements from the group consisting of copper, aluminium, cobalt, nickel, silver, gold or an alloy comprising at least one of said elements. When applied to the foil, for example by vapour deposition or sputtering, the above metals provide a mirror reflective coating, which thus has a very high reffection coefficient. Preferably, more than 85% of the infrared radiation is reflected by the reflective layer.

The plastic foil material which serves as a base for the reflective coating can be freely selected by the skilled person. When selecting a suitable plastic foil, factors such as the heat conduction coefficient of the material, flexibility and elasticity, durability and robustness and available material thicknesses may be considered. Also the extent to which it is possible to bond the plastic foil to the bubble foil may play a part in the selection of a suitable plastic foil that serves as a base for the reflective layer. To that end, the interaction of the polymer of which the foil is made with other chemical substances, for example adhesives, needs to be considered, for example. Another, optional, aspect that may be relevant in selecting a suitable plastic foil are the vapour and/or fire resistance thereof.

Some polymeric materials which can be used as a plastic foil on the basis of which the layer of reflective foil can be provided are for example selected from a group consisting of polyethylene (PE), polyethylene terephthalate (PT) and other polyesters, fluoropolymers, such as polytetrafluoroethylene (PTFE, Teflon™), or ethylene tetrafluoroethylene copolymer (EFTE), polyvinyl chloride (PVC), nylon, polypropylene (PP) and other polyamides.

As for example explained in the foregoing, the bubble foil may be made of polyethylene (PE) of a suitable thickness. The reflective layer may be made of polyethylene terephthalate (PET), for example, with a layer of a reflective material, such as aluminium, applied thereto. The thickness of the bubble foil that is used can be freely selected by the skilled person; preferably, however, it ranges between 1 mm and 20 mm, measured through the bubbles (in fact this is the thickness of the bubbles, therefore).

According to a preferred embodiment, said at least one layer of bubble foil and said at least one layer of reflective foil are connected in such a manner that the layers loosely abut against each other. This can be accomplished in various ways, for example by connecting the layers together by connecting means from a group comprising staples, by tying or threading the layers together by means of a string, by affixing the layers together by means of an adhesive label, by rivetting the layers together, or by bonding, affixing or glueing the layers together on one or more sides.

The present invention will now be explained in more detail with reference to figures and a few specific embodiments, in which:

Figure 1 shows an embodiment of the present invention;

Figure 2 shows an embodiment of the present invention;

Figure 3 is a larger-scale view of an embodiment of the present invention; Figure 4 shows an embodiment of the present invention, in which the layers are bonded together by means of adhesive labels.

Figure 1 shows a layered insulation material 1 consisting of a layer of bubble foil and a layer of reflective foil 4 provided thereon. The reflective foil 4 is made of a plastic foil, for example comprising polyethylene terephthalate (PET) or another polyester. Those skilled in the art will realise that any desired plastic foil can be used for this purpose. The bubble foil 3 is provided with a multitude of bubbles, such as the bubble 7, on one side thereof. Each bubble is internally filled with a fluid, for example air. Those skilled in the art will appreciate that the bubbles may also be filled with another gas or liquid instead of air; as is known, however, the excellent thermal insulation properties of a stationary column of air will suffice. Spaces 8 are present between the bubbles 7. Because the reflective foil 4 abuts the bubbles of the bubble foil 3, and is preferably bonded thereto, the space present between the bubbles 8 is sealed, so that said spaces form further air chambers or cells. The layered structure comprising the layer of reflective plastic foil 4, the bubble foil 3 and the eel! structure consisting of bubbles 7 and spaces δ present between layers 3 and 4 provides excellent insulation properties, which impart a high R-value to the layered insulation material.

Figure 2 shows another embodiment of the present invention, comprising a first bubble foil layer 10 and a second bubble foil layer 11 , between which a reflective foil layer 12 is disposed. The bubble sides of the layers 10 and 11 of bubble foil face towards each other, being separated from each other by the layer 12 of reflective plastic foil. The layer 12 of reflective plastic foil abuts against the bubbles of the layers of bubble foil 10 and 11, preferably being bonded thereto. In this way a compact but efficiently insulating stack of layers 10, 11 and 12 is obtained, between which an insulating cell structure is present.

Figure 3 shows a large-scale view of a preferred embodiment of the invention, consisting of four layers of bubble foil 15, 16, 17 and 18, and a reflective foil layer 20. In the embodiment shown in figure 3, the insulation material is formed by two layers of bubble foil, with the bubbles of each layer of bubble foil being located on the side that faces towards the next layer. Located adjacent to two layers of bubble foil 17 and 18 is the layer 20 of reflective plastic foil, which is likewise located adjacent to the bubbles of the layer of bubble foil 17. Present on top of said layer 20 are the layers of bubble foil 15 and 16. The material shown in figure 3 comprises a complex cell structure of bubbles 23 and spaces 24, in which stationary air is present.

When use is made of 8 layers of bubble foil having a thickness of 4 mm, measured from the flat foil sides up to the upper side of the bubbles, and a layer of reflective foil having a thickness of 12 μm, for example, made of polyethylene terephthalate (PET), and provided with an aluminium reflective coating, an insulation value (R-value) of 5 is obtained. The insulation material thus obtained is only 32 mm thick. By way of comparison, a glass wool blanket having the same R- vaiue is about 250 mm thick. In a preferred embodiment, as shown in figure 4, the layers of bubble foil 15, 16, 17 and 18, and the reflective foil 20, are affixed together by means of adhesive labets 30 and 31. Since the various layers are only bonded together in one or more places spread over the surface, the layers loosely abut against each other over the larger part of their surface. Upon installation of the insulation foil in a building, the spacing between the layers can become much larger than the thickness of the bubbles. The stationary column of air between the layers is thicker, therefore, and consequently the R-value will be higher. This effect is comparable with the effect of a curtain hanging in a window, spaced by about 10 - 15 cm from, for example, a window pane surface. In addition, there is hardly any contact between the layers, so that contact heat transmission between the layers will also be minimal. The R-value actually achieved upon installation can thus be much higher than in the situation in which the layers abut against each other in a compact manner.

Instead of using adhesive labels, the layers can also be connected together by means of, for example, staples, adhesives and the like. It is important in that case that said connecting together takes place only in a few places spread over the surface (depending on the dimension of the surface).