AU2005202671B2 - Insulation Sheeting - Google Patents

Abstract

Abstract A sheet of insulation (10) comprising a body (10) including a cell structure (13). The body (10) defines a first side (11) and a second side (12). The second side (12) has superior fire performance characteristics in comparison to the first side (11). r=b

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 Address for service is: WRAY & ASSOCIATES Level 4, The Quadrant 1 William Street Perth, WA 6000 Attorney code: WR Invention Title: "Insulation Sheeting" The following statement is a full description of this invention, including the best method of performing it known to me: 1 -2 "Insulation Sheeting" Field of the Invention Without being limited thereto the present invention relates to building insulation. Background Art 5 Various types of insulation such as batts and loose-fill are currently available. Typically batts and loose fill comprise fibreglass, polyester or wool. Another known form of insulation is thermo-reflective insulation having at least one outer reflective foil sheet. A particularly advantageous form of thermo-reflective insulation is disclosed in Australian Innovation Patent 2003100663 to Air-Cell Innovations (Aust) Pty Ltd. 10 In general the performance of insulation is measured in terms of a number of performance characteristics including insulating ability, tear strength, burst strength, impact resistance, durability and fire performance. Fire performance is typically measured in terms of smoke development, flame spread and ignitability. In Australia, for example, Australian Standards AS/NZS4859.1, AS/NZ4200.1, 15 AS1 530.2 and AS1530.3 are presently widely used as standard against which the fire performance of thermo-reflective insulation and radiant barrier materials is assessed. Australian Standards AS1530.2 and AS1530.3 provide benchmarks in assessing the early fire hazard characteristics of insulation. The preceding discussion of the background to the invention is intended only to 20 facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application. Disclosure of the Invention 25 According to a first aspect of the invention there is provided a sheet of insulation comprising a body including a cell structure wherein the body defines a first side and a second side, the second side having superior fire performance characteristics in -3 comparison to the first side, the first side comprising a low-density polymer sheet with a foil layer and high-density polymer scrim reinforcement and the second side comprising a low density polymer sheet with a foil layer and no high-density polyethylene scrim reinforcement. 5 Beneficially the high-density polymer scrim reinforcement of the first side provides advantageous strength and integrity to the insulation while the second side provides advantageous fire performance. The polymer material of the first and second sheets and scrim reinforcement preferably comprises polyethylene. In a preferred arrangement, the cell structure comprises a single air-cell layer 10 interposed between the first and second sides of the body. Each cell is preferably of a diameter between about 15 and 25 mm and a depth of between about 6 to 10 mm. Preferably the air-cell layer includes a quantity of a fire retardant substance such that the body turns in on itself when subjected to naked flame or heat, and thereby limits the available oxygen and thus the potential for ignition. 15 Sufficient fire retardant substance may be added to the low density polyethylene material to provide the sheeting with appropriate fire retardance, without the need to alter the characteristics of the high density polyethylene scrim on the first side of the body. By having high-density polyethylene scrim on one side of the body substantially less fuel is provided than if high-density polyethylene scrim were used on both sides 20 of the body. In the embodiment having fire retardant substance added to the air cell layer and high-density polyethylene scrim on only one side of the body the increase in fireretardancy of the intermediate air-cell layer, achieves a balance which provides desired fire retardancy characteristics. If high density polyethylene scrim were present 25 on other sides, or indeed on only one side without the countering effect of the necessary fire retardancy of the intermediate single layer cell structure, then it is likely that, when vertically disposed and subject to flame, the two sides -4 would burn outward from each other, allowing a greater concentration of oxygen in the area of the combustion and a greater surface area of flame concentration. Indeed, it is considered feasible for the insulation in preferred embodiments of the invention to achieve a vertical burn performance that complies with the 5 AS/NZ4200.1 fire indices while also maintaining adequate strength and integrity of the insulation. According to a second aspect of the invention there is provided a sheet of insulation comprising: a body including a first and a second side with a cell structure therebetween, the first and second sides each including polymer 10 material with high-density polymer scrim being used as a reinforcement only the first side. A vertical burn performance may be achieved that complies with the AS/NZ4200.1 fire indices while being relatively robust by virtue of the high density polymer scrim. Preferably the first side has an emissivity characteristic that is two or more times 15 greater than the equivalent emissivity characteristic of the second side such that the insulation surface thereby acts as a glare shield. The first side may be coloured. Preferably, where a glare shield is not required to be present on the insulation sheeting, the first side has an emissivity characteristic equivalent to the 20 emissivity characteristic of the second side. Preferably the weight of the insulation and is about 380 grams per square metre. The thinness of the insulation may be in the range of 6 to 8 mm. Brief Description of the Drawings The invention will be better understood by reference to the following description 25 of one specific embodiment as shown in the accompanying drawings in which: -5 Figure 1 is a schematic view of insulation sheeting according to the embodiment of the invention, with part of an outer layer of the sheeting removed; Figure 2 is a cross-section along the line 2-2 of Figure 1; 5 Figure 3 is a schematic view of part of the insulation sheeting; and Figure 4 is a schematic perspective view of the insulation sheeting, with several layers partly removed to reveal the construction. Best Mode(s) for Carrying Out the Invention Referring to Figures 1 to 4 of the accompanying drawings there is shown 10 insulation sheeting having a body 10 including a cell structure 13. The body 10 defines a first side 11 and a second side 12. In this arrangement the first side 11 is coloured for glare reduction and the the second side 12 has superior fire performance characteristics compared to the first side 11. The insulation is of a thickness allowing the insulation to be disposed in a rolled 15 configuration. The first and second sides 11, 12 together form substantially planar opposed sides when the body 10 is unrolled. A preferred fire retardancy performance characteristic is provided so as to achieve AS/NZ4200.1 compliance using test standards AS1530.2 and AS1530.3. The cell structure 13 is formed from low density polyethylene material with an appropriate measured 20 quantity of a fire retardant added thereto. The second side 12 comprises plain non-reinforced foil in the form of 99.5% pure aluminium reflective foil laminated together with low density polyethylene sheeting. While similar, the first side 11 is comprised of high density reinforced scrim laminated together with a low density polyethylene sheeting and 99.5% 25 pure aluminium reflective foil for a preferred strength performance.

-6 The cell structure 13 comprises first and second polyethylene membranes 15 and 17 respectively bonded together. Although not shown in the drawings a third polyethylene membrane in the form of a flat polyethylene sheet is bonded to the side of membrane 15 opposite the side to which membrane 17 is bonded. The 5 second side 12 thus includes the third membrane. It is however to be appreciated that the second side 12 could consist only of aluminium foil and the lower part of cell structure 13. The presence of the high density polyethylene scrim on only the first side 11 of the body 10, together with the increase in fire retardancy of the cell structure 13, 10 achieves a balance which provides the insulation sheeting according to the embodiment with desired fire retardancy characteristics. With this arrangement, it has been found that rather than the first and second sides burning outward from each other, allowing an increased concentration of oxygen in the area of combustion and a greater surface area of flame 15 concentration, the insulation sheeting according to the embodiment has a self extinguishing effect on the flame. The insulation sheeting, on being exposed to the flame, tends to turn in on itself so as to provide an extinguishing effect under the individual burn tests, by limiting the available oxygen for combustion. Thus the embodiment shown in Figures 1 to 4 meets the requirements of 20 Australian Standard AS/NZ4200.1 under AS1530.2 and AS1530.3 test protocols. In addition by its construction the insulation is strong enough to meet the impact resistance test protocols of AS/NZS4040.4. In outline Australian Standards AS1530.2 utilises a vertically mounted test apparatus that supports a vertical sample of insulation. The vertically mounted 25 apparatus has a small trough at the base of the apparatus for containing absolute alcohol so as when ignited the test sample is exposed to the naked flame. The purpose of the test methodology is to access flammability of particular insulation.

-7 Additionally, Australian Standards AS1530.3 utilises a horizontal test apparatus that supports a horizontally mounted test sample of insulation exposing the sample to the effects of high temperature radiant heat. Important characteristics of insulation sheeting include ignitability, smoke release, heat release and flame 5 propagation. In terms of smoke release or smoke generation other important sub-characteristics include visibility and toxicity. The present embodiment has acceptable, if not preferred, characteristics in this regard. The reinforcement of the first side 11 enhances the tensile strength of the 10 insulation 10, allowing the insulation 10 to be installed over large spans in a building construction. Furthermore the reinforcement provides a greater tear strength and burst strength, thus preventing tearing or damage as a result of broken roof tiles, bricks or other building debris during and after construction. The reinforcement accordingly provides robustness to the insulation 10 as a 15 whole. In this arrangement, the closed cell structure 13 comprises first and second polyethylene membranes 15 and 17 respectively bonded together. 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 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 closed cells 21 containing air. Each closed 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. 25 In this way, each cell 21 is of generally cylindrical construction. The diameter a is within a range of about 15 mm to 25 mm, with the preferred value being about 20 mm. The depth b is within a range of about 6 mm to 10 mm, with the preferred value being about 8 mm.

-8 The cell structure 13 with closed air cells 21 of such a size provide the necessary R rating for the insulation while retaining the integrity of the sheeting. If, for example, the diameter "a" is larger than about 25 mm, there is a real possibility that sections of the two outer sides 11, 12 could deflect inwardly and contact 5 each other to create a thermal bridge which would disrupt the thermal effectiveness of the insulation. Additionally, if the cells 21 are too deep in terms of dimension b, there may be difficulty in fastening the sheeting in position using staples or other fixing means. Additionally, where the insulation sheeting is installed under tile battens, metal deck roofing and wall sheeting, a depth in 10 excess of 10 mm would cause a floating effect and difficulties securing outer building envelope claddings. It is, however, necessary for the closed cells 21 to be of at least the minimum sizes specified in order to provide the necessary insulating value. Because the cellular insulation sheeting 10 is of a single layer cell construction, 15 as opposed to a double layer cell construction as in the case with some insulation sheeting, it can be manufactured conveniently. In particular, only one pass through a machine is required in order to form the closed cell structure 13. As mentioned above the first side 11 can be coloured so as to reduce glare while retaining radiant heat reflective characteristics. This can be particularly desirable 20 on construction sites where the sheeting is used to line walls and roofs of building envelopes under construction, and where it may be exposed for some time so creating a reflective glare problem for workers in the vicinity. Suitable colours for the exposed surface comprise red or orange tones. From the foregoing, it is evident that the present invention provides insulation 25 sheeting that is simple in construction yet highly effective in use. It should be appreciated that the scope of the invention is not limited to the scope of the embodiment described. Various changes may be made to the form, details, arrangement and proportion of the various parts and steps without departing from the spirit and scope of the invention. Modifications and variations -9 such as would be apparent to the skilled addressee are, at the very least, considered to fall within the scope of the present invention. Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood 5 to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims (7)

1. A sheet of insulation comprising a body including a cell structure wherein the body defines a first side and a second side, the second side having superior fire performance characteristics in comparison to the first side, the first side 5 comprising a low-density polymer sheet with a foil layer and high-density polymer scrim reinforcement, and the second side comprising a low-density polymer sheet with a foil layer and no high-density polyethylene scrim reinforcement.

2. A sheet of insulation as claimed in claim 1 wherein the polymer material of the 10 first and second sheets and scrim reinforcement comprises polyethylene.

3. A sheet of insulation as claimed in claim 1 or 2 wherein the cell structure comprises a single air-cell layer interposed between the first and second sides of the body.

4. A sheet of insulation as claimed in claim 3 wherein the air-cell layer includes a 15 quantity of a fire retardant substance.

5. A sheet of insulation as claimed in any one of claims 1 to 4 wherein body turns in on itself when subjected to naked flame or heat, so as to limit the available oxygen and thus the potential for ignition.

6. A sheet of insulation as claimed in any one of claims 1 to 5 having a vertical 20 burn performance that complies with the AS/NZ4200.1 fire indices while being relatively robust by virtue of the high-density polymer scrim.

7. A sheet of insulation as claimed in any one of the preceding claims, the sheet being substantially as herein described with reference to the accompanying drawings. 25