AU2012241111A1 - Perforated Sheeting - Google Patents

Abstract

Abstract Insulation sheeting comprising a body (10) having a pair of opposed surfaces (14) and perforations (25) extending through the body (10) between the opposed surfaces (14). The perforations (25) are of a size, spacing and number to provide permeability to water vapour. The body (10) comprises a closed cell structure (13) and two outer layers (11, 12) between which the cell structure (13) is interposed. 15a

Description

P/00/011 28/5/91 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Air-Cell Innovations Pty Ltd Actual Inventor Scott Ian Gibson Keith Robert Anderson Address for service is: WRAYS Ground Floor, 56 Ord Street West Perth WA 6005 Attorney code: WR Invention Title: Perforated Sheeting The following statement is a full description of this invention, including the best method of performing it known to me: 1 -2 "Perforated Sheeting" Field of the Invention This invention relates to insulation sheeting. The invention has been devised particularly, although not necessarily solely, for 5 insulating buildings and other structures. Background Art There are various types of insulation currently available for buildings, including thermo-reflective insulation sheeting. An example of thermo-reflective insulation sheeting is disclosed in the applicant's Australian innovation patent 2003100663, 10 the contents of which are incorporated herein by way of reference. Such insulation sheeting comprises a single layer closed cell structure interposed between two outer layers, at least one of which comprises a reflective foil. This insulation sheeting has proved to be particularly effective barrier in reducing heat energy transfer, the closed air cell structure serving to reduce the amount of heat 15 transfer through convection and conduction, and the reflective layer serving to reduce heat transfer through radiation. In addition to providing a barrier to heat transfer, the insulation sheeting also provides a barrier to vapour. Where insulation sheeting is intended to be installed in walls and floors, it is 20 desirable that the sheeting have some permeability to moisture vapour so as to reduce the risk of moisture damage due to condensation in the building envelope cavity. Disclosure of the Invention According to a first aspect of the invention there is provided insulation sheeting 25 comprising a body having a pair of opposed surfaces, the body comprising a cell -3 structure, the body being perforated for vapour permeability therethrough between the opposed surfaces. Preferably, the perforations are of a size, spacing and number to provide permeability to water vapour in accordance with achieving a low classification for 5 resistance to water vapour transmission under Australian and New Zealand standard AS/NZS4200.1.1994. Such permeability will allow the building "breathe" through the insulation sheeting and also minimise the build up of condensation attributable to the barrier-effect of the insulation sheeting. The perforations may comprise a plurality of holes extending through the body 10 and opening onto the opposed surfaces thereof. The cell structure may comprise a closed cell structure. In one embodiment, the closed cell structure may comprise a single layer cell structure. The single layer cell structure may comprise a plurality of plastic membranes bonded together to form a plurality of air cells therebetween. 15 The plastic membranes used in the formation of the closed cell structure may typically comprise of low-density polyethylene (LDPE), high density polyethylene (HDPE), or linear low-density polyethylene (LLDPE). Preferably, the membrane thickness is about 175pm or smaller. The single layer cell structure preferably comprises a plurality of cells of 20 generally cylindrical construction each of a diameter between about 8mm and 25mm, and a depth of between about 3mm and 10mm. Preferably, the diameter of each cell is about 10mm. Preferably, the thickness of the sheeting between the two opposed surfaces is about 4mm, in which case the depth of each cell would be about 3mm.

-4 In another embodiment, the cell structure may comprise a closed cell foam structure. Preferably, the closed cell foam structure comprises polyethylene foam. More preferably, the closed cell foam structure comprises cross-linked low density 5 polyethylene (LDPE) foam. The 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 and acoustic insulation characteristics as well as greater 10 resistance to heat and flame. The cell structure may define at least one of the opposed surfaces of the body. However, it is preferred that the body further comprise two outer layers between which the cell structure is deposed, with the outer layers defining the respective opposed surfaces. 15 Preferably, at least one of the two outer layers comprises a foil. More preferably, both outer layers comprise a foil. Preferably, the foil comprises a reflective foil such as 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 20 reinforcement may be provided by a scrim bonded to the foil 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, one of the reflective layers may be treated for glare reduction. The 25 layer may be treated in any appropriate way, such as by applying a surface treatment such as colouring to the exposed surface of the layer or by applying a -5 film incorporating the colouring to the exposed surface of the layer. Any appropriate colouring can be used, and particularly 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 5 provide greater comfort and protection against glare blindness while still providing a low enough emittance to provide thermal resistance by way of an upper reflective air space ideally within a range of E=0.08 to E=0.14 The cell structure is preferably provided with fire retardency. This may be achieved by the addition of an appropriate quantity of a fire retardant substance 10 to the resin from which the cell structure is formed. The fire retardant may provide a fire index of less than or equal to 5 under AS1530.2. Preferably, antioxidant is added to provide the cell structure with durability. Preferably, UV protection is also provided to the insulation sheeting. Preferably, the perforations are formed after construction of the insulation 15 sheeting. In this way, the perforations extend not only through the two outer layers but also through the cell structure located therebetween. Further, the perforations in the outer layers and the cell f structure are in alignment to assist air and moisture vapour transmission through the sheeting. The perforations may be generated by perforating the sheeting with a perforating device 20 comprising a set of sharp end extrusions designed to perforate the sheeting at a variety of predetermined intervals. According to a third aspect of the invention there is provided a method of manufacturing insulation sheeting comprising forming a body having a cell structure and a pair of opposed surfaces, and perforating the body to produce a 25 plurality of holes extending through the body between the opposed surfaces thereof.

-6 Brief Description of the Drawings The invention will be better understood by reference to the following description of several specific embodiment thereof as shown in the accompanying drawings in which: 5 Figure 1 is a schematic view of insulation sheeting according to a first embodiment, with part of an outer layer of the sheeting removed to reveal the cellular structure; Figure 2 is a cross-section along the line 2-2 of Figure 1; Figure 3 is a schematic view of part of the cellular structure; 10 Figure 4 is a schematic perspective view of the insulation sheeting, with several layers partly removed to reveal the internal construction; Figure 5 is a fragmentary perspective view of insulation sheeting according to a second embodiment; Figure 6 is a schematic fragmentary elevational view of insulation sheeting 15 according to a third embodiment, with part of an outer layer of the sheeting removed to reveal the inner closed cell foam structure; and Figure 7 is a fragmentary side elevational view of the insulation sheeting of Figure 6. Best Mode(s) for Carrying Out the Invention 20 Referring now to Figures 1 to 4 of the accompanying drawings, there is shown insulation sheeting according to the first embodiment, comprising a body 10 having two outer layers 11, 12 with a cell structure 13 bonded therebetween. Each outer layer 11, 12 has an outer surface 14. The body 10 is of a thickness between the outer surfaces 14 which allows the insulation sheeting to be -7 disposed in a rolled configuration and also unrolled to assume a substantially flat configuration. In this embodiment, the insulation sheeting has a thickness of about 4mm between the outer surface 14. The first outer layer 11 comprises reinforced reflective aluminium foil. More 5 particularly, the first outer layer 11 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 a greater tear strength and burst strength. 10 The second outer layer 12 comprises aluminium foil, although it is not necessarily reinforced. The cell structure 13 is a closed cell structure comprising first and second polyethylene membranes 15 and 17 respectively bonded together. With this arrangement, the closed cell structure 17 comprises a single-layer cell structure. 15 The first membrane 15, which is best seen in Figure 3 of the drawings, is formed by a vacuum suction process into a series of depressions 19 having open ends 20 which are closed by the second membrane 17. With the closure of the openings 20 in the first membrane 15 by the second membrane 17, the depressions 19 form air cells 21 within the cell structure. 20 In this embodiment, the first and second membranes 15, 17 comprise fire retarded modified low-density polyethylene (LDPE), high density polyethylene (HDPE) or linear low-density polyethylene (LLDPE). Each air cell 21 in this embodiment is of generally circular cross-section, having a diameter a and a depth b, as illustrated in Figure 3 of the drawings. In this 25 way, each cell 21 is of generally cylindrical construction. In this embodiment, the diameter a is about 10mm. The depth b is about 3mm, based on the overall thickness of the sheeting 10 being about 4mm.

-8 The exposed surface of the first 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 workers in the vicinity. In this 5 embodiment, the treatment comprises colouring. Suitable colours for the exposed surface may comprise red, blue, green, or orange tones. The body 10 is perforated to provide the insulation sheeting with permeability to air and water vapour. In this regard, the body 10 has a plurality of perforations 25 extending therethrough between the two outer surfaces 14 thereof. The 10 perforations 25 comprise holes 27 which open onto the outer surfaces at openings 28. formed. The holes 27 of course also open onto the interior of the air cells 21 within the cell structure 13 from opposed sides thereof. In this embodiment, the perforations 25 are formed by piercing the body 10 with a perforating tool. 15 The perforations 25 are of a size, spacing and number to provide the insulating sheeting with permeability to water vapour, thereby allowing a building in which the sheeting is installed to "breathe" through the sheeting and to minimise any condensation arising within the building envelope cavity from the barrier-effect of the sheeting. More particularly, the perforations 25 are such that the insulation 20 sheeting can comply with the permeability rating required for wall and floor applications. The perforations 25 are, of course, of a size which excludes normal passage of water in liquid form therethrough. While the perforations 25 provide the body 10 with the requisite permeability to air and water vapour, they do not adversely affect the thermal barrier 25 characteristics of the insulation sheeting to any significant effect. Referring now to Figures 5 of the drawings, insulation sheeting according to the second embodiment is similar to the first embodiment, with the exception that the second layer 12 is formed of polyethylene sheeting rather than reflective aluminium foil. As with the first embodiment, the body 10 has perforations 25 to 30 provide the requisite permeability to air and water vapour.

Referring to Figures 6 and 7, there is shown insulation sheeting according to a third embodiment. The insulation sheeting according to the third embodiment is similar in some respects to the insulation sheeting according to the first embodiment and so corresponding reference numerals are used to identify 5 corresponding parts. The body 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. In this embodiment, the thickness is about 6.5mm. 10 The cell structure 13 comprises a closed cell foam structure. The closed cell foam structure 13 comprises flexible light gauge foam which in this embodiment comprises cross-linked LDPE foam. The polyethylene foam incorporates UV protection, fire retardancy and an anti-oxidant. The fire retardancy is such as to provide compliance with AS1530.2. Indeed, the fire retardant may provide a Fire 15 Index of less than or equal to five under AS1530.2. Anti-oxidant protection is such as to afford a minimum 15 year product life when installed. The cross-linked structure of the closed cell foam structure 13 provides enhanced thermal and acoustic insulation characteristics, as well as greater resistance to heat and flame, in comparison to the prior art insulation sheeting 20 referred to previously. Specifically the closed cell foam structure 13 produced from cross-linked LDPE foam allows construction of insulation sheeting which is thinner than the prior art sheeting referred to previously because of inherent stiffness in the foam arising from the cross-linking. Further, the closed cells within the cross-linked LDPE foam are much smaller in size than the air cells in 25 the earlier embodiments and also in prior art sheeting. Indeed, the closed cells in the foam structure 13 comprise micro-encapsulated air cells, typically of a cross-sectional size less than 0.1mm. With this arrangement, the air cells are generally evenly distributed within the foam cell structure 13, so affording better fire resistance. This is because there are no relatively large bubbles of air to 30 support combustion, as exist in the prior art insulation referred to previously. The - 10 even distribution of micro-encapsulated air cells also provides resistance to thermal and acoustic energy transfer. The perforations 25 comprise holes 27 formed by piercing the body 10 with a perforating tool. The holes 27 not only extend through the outer layers 11, 12 to 5 open on to the outer surfaces 14 thereof at openings 28 but also extend through the closed cell foam structure 13. The perforations 21 are not apparent in the closed cell foam structure 13 owing to the collapsible nature of the foam. Even though collapsed within the closed cell foam structure 13, the perforations 25 do provide a transmission path through the body 10 for air and water vapour. 10 From the foregoing, it is evident that the embodiments each provide insulation sheeting which is simple in construction and highly effective in use, yet permeable to air and water vapour so as to be particularly suitable for wall and floor applications. It should be appreciated that the scope of the invention is not limited to the scope 15 of the embodiments described. 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. 20

Claims (16)

1. Insulation sheeting comprising a body having a pair of opposed surfaces, the body comprising a cell structure, the body being perforated for vapour permeability therethrough between the opposed surfaces. 5

2. Insulation according to claim 1 wherein the cell structure comprises a closed cell structure.

3. Insulation according to claim 2 wherein the cell structure comprises a single layer cell structure.

4. Insulation according to claim 3 wherein the single layer cell structure 10 comprises a plurality of plastic membranes bonded together to form a plurality of air cells therebetween.

5. Insulation according to claim 2 wherein the closed cell structure comprises a closed cell foam structure.

6. Insulation according to claim 5 wherein the closed cell foam structure 15 comprises polyethylene foam.

7. Insulation according to claim 5 wherein the closed cell foam structure comprises cross-linked low density polyethylene (LDPE) foam.

8. Insulation sheeting according to any one of the preceding claims wherein the body further comprise an outer layer adjacent the cell structure, the 20 outer layers defining one of the opposed surfaces.

9. Insulation sheeting according to any one of claims 1 to 7 wherein the body further comprise two outer layers between which the cell structure is deposed, the outer layers defining the respective opposed surfaces. - 12

10. Insulation sheeting according to claim 8 or 9 wherein at least one of the outer layers comprises a foil.

11. Insulation according to any one of claims 1 to 7 wherein the cell structure defines at least one of the opposed surfaces of the body. 5

12. Insulation sheeting according to any one of the preceding claims wherein the perforations are formed after construction of the insulation sheeting.

13. Insulation sheeting according to claim 12 wherein the perforations are generated by perforating the sheeting with a perforating device comprising a set of sharp end extrusions designed to perforate the sheeting at a variety 10 of predetermined intervals.

14. A method of manufacturing insulation sheeting comprising forming a body having a cell structure and a pair of opposed surfaces, and perforating the body to produce a plurality of holes extending through the body between the opposed surfaces thereof.

15 15. Insulation sheeting substantially as herein described with reference to the accompanying drawings.

16. A method of manufacturing insulation sheeting substantially as herein described.