Field of the Invention

This invention relates generally to insulation, and more particularly insulation sheeting.

The invention has been devised particularly, although not necessarily solely, for insulating buildings and other structures. Accordingly, the invention also relates to a building construction incorporating the insulating sheeting.

Background Art

There are various types of insulation currently available for buildings, including thermo-reflective insulating sheeting. An example of thermo-reflective insulation sheeting is disclosed in Australian Innovation patent 2003100663. Such insulating sheeting comprises a single layer closed cell structure interposed between two outer layers, at least one of which comprises reflective foil. This insulation sheeting has proved to be a particularly effective barrier in reducing energy transfer, the closed cell structure serving to reduce the amount of heat transferred through convection and conduction, and the reflective foil layer serving to reduce heat transfer through radiation.

The single layer closed cell structure comprises a plurality of plastic membranes bonded together to form a plurality of air cells therebetween. The air cells are of generally cylindrical construction each of a diameter between eight millimetres and twenty five millimetres, and a depth of between about three millimetres and ten millimetres.

The dimensions of the air cells were selected to provide the necessary insulation characteristics without the need to rely upon a double layer cell structure which was previously used in the prior art.

However, insulation sheeting comprising a single layer cell structure defined by membranes bonded together may have some limitations. In particular, such insulation sheeting may not necessarily function to provide acoustic insulation characteristics to a necessary extent in certain applications; that is, it may not provide an effective acoustic break.

It is against this background that the present invention has been developed.

Disclosure of the Invention

It is an object of the present invention to overcome, or at least ameliorate, one or more of the deficiencies of the prior art mentioned above, or to provide the consumer with a useful or commercial choice.

Other objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, a preferred embodiment of the present invention is disclosed.

According to a first aspect of the invention there is provided insulation sheeting comprising an inner structure interposed between two outer layers, the inner structure comprising first and second inner layers of different densities.

Preferably, the inner structure comprises a cell structure. The cell structure may comprise a closed cell structure.

Preferably, the first and second inner layers comprise foam.

Preferably the first inner layer comprises polyethylene foam. More preferably, the first layer comprises cross-linked low density polyethylene (LDPE) foam.

Preferably, the second inner layer comprises ethylene vinyl acetate (EVA). More preferably, the second inner layer comprises carbonate loaded ethylene vinyl acetate.

Preferably, the closed cell foam structure is flexible and resiliently compressible.

The closed cell foam structure is advantageous as it provides resistance to moisture absorption and thereby enhances resistance to development of mould.

The LDPE foam is advantageous as it provides the insulation sheeting with enhanced thermal conductivity resistance characteristics, and some acoustic insulation characteristics, as well as greater resistance to heat and flame. The carbonate loaded ethylene vinyl acetate is advantageous because, by virtue of its higher density, it impedes the penetration of low to medium frequency sound waves that pass through the first inner layer.

The close cell foam structure is preferably provided with fire retardancy. This may be achieved by the addition of an appropriate quantity of a fire retardant substance to the resin from which the foam providing at least the first layer is formed.

Preferably, antioxidant is added to the closed cell foam structure to provide durability. Preferably, UV protection is also provided to the insulation sheeting

The first layer may incorporate a plurality of holes to enhance its acoustic insulation characteristics. More particularly, the holes provides for greater acoustic absorption.

Preferably, the holes extend into the first inner layer from the adjacent outer layer.

While the holes may be of any appropriate size, it has been found that holes of a diameter of about 2mm are effective.

The holes may be formed in the first layer by a punching process. Typically, the holes are punched in the first layer and the adjacent outer layer prior to bonding of the two inner layers together.

The inner structure may comprise one or more further inner layers.

Preferably, at least one of the two outer layers comprises reflective foil. More preferably, both outer layers comprise reflective foil.

Preferably, the reflective foil comprises aluminium foil. The aluminium foil may comprise 99.5 percent pure aluminium reflective foil.

Preferably, at least one of the outer layers is reinforced for tear resistance. The reinforcement may be provided by a scrim bonded to the foil layer for reinforcement to provide strength and tear resistance. Preferably, the scrim comprises high density polyethylene weave laminated to the foil. Other types of scrim can also be used, one example being polypropylene weave. Preferably, at least one of the reflective layers is treated for glare reduction. The layer may be treated in any appropriate way, such as by applying a surface treatment such as colouring thereto. Suitable colours for the surface treatment comprise red, blue, green or orange tones.

The treatment for glare reduction is designed to provide a reduction of glare to provide greater comfort and protection against glare blindness.

Preferably, the outer layer treated for glare reduction comprises the outer layer adjacent the first inner layer.

The insulation sheeting is advantageous as it can compress under load for fixing while still affording worthwhile insulation benefits. This is because of the presence of the resilient nature of the inner structure.

For certain applications, the outer layers may be perforated for air and water vapour permeability through the insulation sheeting.

Preferably, the perforations are of a size, spacing and number to provide permeability to water vapour in accordance with achieving a low classification for resistance to water vapour transmission under Australian and New Zealand standard AS/NZS4200.1. Such permeability will allow the building to "breath" through the insulation sheeting and also minimises the build up of condensation attributable to the barrier effect of the insulation sheeting.

Preferably, the perforations are formed after construction of the insulation sheeting. In one arrangement, the perforations may extend not only through the two outer layers but also entirely through the inner structure located therebetween.

According to a second aspect of the invention there is provided insulation sheeting comprising an inner structure interposed between two outer layers, the inner structure comprising first and second inner layers, the second inner layer being of higher density than the first inner layer, and a plurality of holes provided in the first inner layer.

According to a third aspect of the invention there is provided insulation sheeting comprising an inner structure interposed between two outer layers, the inner structure comprising first and second inner layers of foam material, the two outer layers comprising reflective foil, the second inner layer being of higher density than the first inner layer, and a plurality of holes extending into the first inner layer from the adjacent outer layer.

According to a fourth aspect of the invention there is provided a building construction comprising a frame, cladding attached to the frame, and insulation between the frame and the cladding, the insulation comprising insulation sheeting according to any one of the preceding aspects of the invention.

According to a fifth aspect of the invention there is provided a method of manufacturing insulating sheeting according to the third aspect of the invention comprising the step of punching holes in the first inner layer and the adjacent outer layer prior to bonding the first and second inner layers together.

Brief Description of the Drawings

The invention will be better understood by reference to the following description of one specific preferred embodiment thereof as shown in the accompanying drawings in which:

Fig. 1 is an underside plan view of insulation sheeting according to the embodiment;

Fig. 2 is a fragmentary side perspective view of the insulation sheeting;

Fig. 3 is a fragmentary side elevational view of the insulation sheeting;

Fig. 4 is a schematic perspective view of the insulation sheeting, with several layers partly lifted to better show its construction; and

Fig. 5 is a fragmentary cross-sectional; view of the sheeting.

Best Mode(s) for Carrying Out the Invention

Referring to the drawings, there is shown insulation sheeting 10 according to the embodiment. The insulation sheeting 10 comprises two outer layers 11 , 12 and an inner structure 13 bonded therebetween. Each outer layer 11, 12 has an outer surface 14. The sheeting 10 is of a thickness between the outer surfaces 14 which allows the sheeting to be disposed in a rolled configuration and also unrolled to assume a substantially flat configuration. The thickness can be up to about 12mm for typical applications. In one typical application the thickness is about 4mm and in another typical application it is about 8-9mm.

The outer layers 11 , 12 each comprises reinforced reflective aluminium foil. The reflective aluminium foil comprises 99.5 % pure aluminium reflective foil reinforced with high density polyethylene scrim. The reinforcement enhances the tensile strength of the insulation sheeting 10, allowing it to be installed over large spans in a building construction. The reinforcement also provides greater tear strength.

The inner structure 13 comprises a closed cell foam structure which is of composite construction and which is compressible with at least some resiliency. In the arrangement shown, the inner structure 13 comprises a first inner layer 15 of foam and a second inner layer 17 of foam. The second inner layer 17 is of foam having a higher density than the foam of the first inner layer 15.

In the arrangement shown, the first inner layer 15 is bonded to the first outer layer 11 , the second inner layer 17 is bonded to the second outer layer 12, and the two inner layers 15, 17 are bonded together. The outer layers 11 , 12 can be applied and bonded to the inner layers 15, 17 in any appropriate way. One particularly suitable way involves a hot melt lamination process.

The first layer 15 comprises cross-linked LDPE foam. The polyethylene foam incorporates UV protection, fire retardancy and an antioxidant. The cross-linked structure of the first layer 15 provides enhanced thermal insulation characteristics, some acoustic insulation characteristics, as well as greater resistance to heat and flame.

The second layer 17 comprises carbonate loaded ethylene vinyl acetate (EVA). The carbonate loaded EVA is advantageous because, by virtue of its higher density, it can function to impede the penetration of low to medium frequency sound waves that might pass through the first layer 15. The first layer 15 incorporates a plurality of holes 19 to enhance its acoustic insulation characteristics. More particularly, the holes 19 provide additional acoustic absorption. The holes 19 extend into the first inner layer 15 from the adjacent outer layer 11. In the arrangement shown, the holes 19 extend entirely through the outer layer 11 and into the first inner layer 15, terminating inwardly of the second inner layer 17, as shown in Fig. 5. Alternatively, the holes 19 may extend entirely through both the first inner layer 15 and the adjacent outer layer 11.

In this embodiment, the holes 19 are of a diameter of about 2mm and are disposed in an array, with spacings of about 20mm between neighbouring holes

The holes 19 may be formed in the first inner layer 15 and the adjacent outer layer 11 by a punching process. Typically, the holes 19 are punched in the first inner layer 15 and the adjacent outer layer 11 prior to bonding of the two inner layers 15, 17 together.

In this embodiment, the reflective foil has a thickness of about 6.5μm and the scrim comprises high density polyethylene scrim with a 6mm by 6mm weave.

The first layer 15 typically is of a thickness of between about 3mm and 8mm, according to the performance requirements of the insulation.

The second layer 17 typically is of a thickness of between about 1mm and 3mm, according to the performance requirements of the insulation.

The outer surface 14 of outer layer 11 is treated to provide some glare reduction while retaining heat reflective characteristics. Glare reduction can be particularly desirable on construction sites where the sheeting may be exposed for some time, so creating a glare problem for persons in the vicinity. In this embodiment, the treatment comprises colouring. Specifically, the colouring comprises an orange pigment.

In addition to providing a thermal break and an acoustic break, the sheeting 10 according to the embodiment may also provides a barrier to air and water vapour. The insulation sheeting 10 is advantageous as it can compress under load for fixing while still affording worthwhile insulation benefits. This is because of the presence of the closed cell foam structure.

The insulation sheeting is suitable for use in building construction involving a frame and cladding attached to the frame, where the insulation sheeting can be installed between the frame and the cladding. The cladding may comprise wall cladding or roof cladding.

The insulation sheeting according to this embodiment can function as a thermal break, an acoustic break and a vapour barrier. It is waterproof and unaffected by water in normal applications. Accordingly, it is particularly suitable for humid climates and can afford protection against water damage. It will not promote growth of fungi or bacteria and does not provide a nesting medium for rodents and insects.

There may be certain situations where it might be desirable that insulation sheeting have some permeability to air and water vapour so as to reduce the risk of moisture damage due to condensation. In such circumstances, the insulation sheeting may be provided with a plurality of perforations extending through the sheeting 10 between the two outer surfaces 14.

It should be appreciated that the scope of the invention is not limited to the scope of the embodiment described. For example, it is not necessary that both outer layers 11 , 12 be reflective foil. One of the outer layers could be reflective foil (preferably treated for glare reduction) and the other layer could comprise a membrane of any appropriate type including, for example, polyethylene film.

Modifications and changes can be made without departing from the scope of the invention. By way of example, the insulation sheeting 10 according to the embodiment incorporated holes 19 in the first layer 15. In another embodiment, the holes may be omitted.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Throughout the specification and claims, unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

Also, future patent applications maybe filed in Australia or overseas on the basis of, or claiming priority from, the present application. It is to be understood that the following provisional claims are provided by way of example only, and are not intended to limit the scope of what may be claimed in any such future application. Features may be added to or omitted from the provisional claims at a later date so as to further define or re-define the invention or inventions.

It will be clearly understood that, if a prior art publication is referred to herein, that reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.