AU2014311264A1

AU2014311264A1 - Vapour permeable and flame retardant building membrane

Info

Publication number: AU2014311264A1
Application number: AU2014311264A
Authority: AU
Inventors: Jonathon COLVILLE
Original assignee: Fletcher Insulation Pty Ltd
Current assignee: Fletcher Insulation Pty Ltd
Priority date: 2013-08-30
Filing date: 2014-08-29
Publication date: 2016-03-17
Also published as: WO2015027282A1

Abstract

The present invention relates to a building membrane for use in the construction of buildings. The membrane is suitable for use as an underlay in roofing construction but may also be used as an underlay in wall or floor construction or for other purposes for which the characteristics of the invention render it suitable. The present invention provides a flexible building membrane including a layer of flexible material that is water vapour permeable and liquid water impermeable and a flame retardant and water vapour permeable material applied to the layer of flexible material. In a preferred embodiment the membrane further includes a layer of flexible material that is water vapour permeable and the flame retardant and water vapour permeable material is an adhesive between the layers for laminating the layers together.

Description

WO 2015/027282 PCT/AU2014/000858 1 Vapour Permeable and Flame Retardant Building Membrane Technical Field [0001] The present invention relates to a building membrane for use in the construction of buildings. The membrane is suitable for use as an underlay in roofing construction but may also be used as an underlay in wall or floor construction or for other purposes for which the characteristics of the invention render it suitable. Background of Invention [0002] Building membranes, such as underlay or sarking membranes, are commonly used in the construction of buildings to line rooves or walls. Such membranes often include a foil layer and a substrate layer laminated together. The purpose of the foil layer is to act as a low emittance and high reflectance barrier to thermal radiation to thereby reduce heat transmission into a building lined by the membrane. The substrate layer is often formed from a flexible water-proof material thereby forming a high liquid water barrier and high water vapour barrier. Such membranes are laid beneath external roof cladding or roof tiles or beneath external wall cladding of a structure to insulate the structure from thermal radiation and to prevent the ingress of water through the roof or wall of the structure. [0003] Where the membrane lines a roof or a wall of a structure the membrane helps to weatherproof the structure by preventing the passage of rain water through the roof or the wall. The membrane also acts as a condensation barrier preventing the ingress of water from the external atmosphere through the membrane to the internal structure of the building. The lining of rooves and walls of structures with such membranes helps prevent water damage to the rafters, ceilings, purlins and other structural and non-structural members in the interior of the building structure. [0004] The layers of the membrane can be adhered together via a laminating process whereby a layer of adhesive is applied to the substrate material before the substrate layer and the foil layer are fed into a laminating apparatus to be bonded together by the adhesive layer. The substrate material can be formed from a woven polymeric material and the foil layer can be formed from a sheet of aluminium.

WO 2015/027282 PCT/AU2014/000858 2 [0005] A potential problem with existing building membranes, such as underlay or sarking membranes, is that condensation of vapour from the air within the structure could accumulate on the internal surface of the membrane which can, over time, cause damage to the structure beneath the membrane. Consequently, there could be resultant water damage to the rafters, ceilings, purlins and the like in the interior of the building structure. Another potential problem with existing building membranes is that they can be ineffective at inhibiting or resisting the spread of fire. Summary of Invention [0006] Accordingly, in one aspect, the present invention provides a flexible building membrane including: - a layer of flexible material that is water vapour permeable and liquid water impermeable; and - a flame retardant and water vapour permeable material applied to the layer of flexible material. [0007] Preferably, the membrane further includes: - a layer of flexible material that is water vapour permeable; and - wherein the flame retardant and water vapour permeable material is an adhesive between the layers. [0008] The flame retardant and water vapour permeable adhesive can be formed in an adhesive layer between the layers of flexible material that permits the passage of water vapour through the layers of flexible material. The flame retardant and water vapour permeable adhesive layer can be formed as patches of the adhesive with gaps between the patches. Alternatively, the flame retardant and water vapour permeable adhesive layer is formed as a substantially continuous film. [0009] In other embodiments, the layer of flexible material that is water vapour permeable and liquid water impermeable and the flame retardant and water vapour permeable material applied to the layer of flexible material are adhered together with an adhesive that is flame retardant and water vapour permeable or is just water vapour permeable and includes no flame retardant additives.

WO 2015/027282 PCT/AU2014/000858 3 [0010] The adhesive is preferably comprised of a hot melt adhesive. The flame retardant and water vapour permeable adhesive can contain oxides of antimony. The flame retardant and water vapour permeable adhesive can contain an inorganic flame retardant additive to promote charring selected from the group including iron oxides, hydrated calcium and magnesium carbonates, bismuth oxides and carbonates, boric acid, a borate, phosphorus as organic phosphates or as inorganic acid phosphates or any combination thereof. [0011] The layer of flexible material that is water vapour permeable and liquid water impermeable can be comprised of a flexible non-woven polymeric material. The layer of flexible material that is water vapour permeable and liquid water impermeable can be comprised of a flexible non-woven polymeric material laminated to a film of polymeric material that is water vapour permeable and liquid water impermeable. The film of polymeric material can be a microporous film comprised of a matrix of polymeric material and a solid, dispersed material embedded in the matrix. The solid dispersed material can include calcium carbonate. Preferably, the flexible non-woven polymeric material is laminated to the film of polymeric material with another adhesive. In an embodiment, the layer of flexible material that is water vapour permeable is comprised of a flexible non-woven polymeric material. Alternatively, the layer of flexible material that is water vapour permeable can be comprised of Kraft paper material. The Kraft paper material is preferably coated or impregnated with a flame retardant. [0012] Preferably, the layers of flexible material each have a thickness of between 100 pm and 500 pm. Either one or both of the layers of flexible material can contain ultraviolet stabilisers, additives to retard flame propagation and additives to retard mechanical shrinking. Either one or both of the layers of flexible material can be coated with a layer of metal by vapour deposition. [0013] The membrane may further include an additional fibrous layer which may be woven or non-woven. The additional fibrous layer can include strands of fibreglass or woven tapes of extruded polymer embedded in the adhesive between the first and second layers.

WO 2015/027282 PCT/AU2014/000858 4 [0014] In another aspect, the present invention provides a method of forming a flexible building membrane including: - providing a layer of flexible material that is water vapour permeable and liquid water impermeable; and - providing a flame retardant material on the layer of flexible material that is water vapour permeable after application on the layer of flexible material. [0015] Preferably, the method includes: - providing a further layer of flexible material that is water vapour permeable; and - wherein the flame retardant material is an adhesive provided between the layers of flexible material. [0016] The adhesive can be applied in patches with gaps between the patches or in a continuous film to a surface of the layer of flexible material that is water vapour permeable and liquid water impermeable. [0017] In other embodiments, the layer of flexible material that is water vapour permeable and liquid water impermeable and the flame retardant and water vapour permeable material applied to the layer of flexible material are adhered together with an adhesive that is flame retardant and water vapour permeable or is just water vapour permeable and includes no flame retardant additives. [0018] The step of applying the adhesive can include continuously providing the adhesive to a rotating roller, continuously feeding the layer of water vapour permeable and liquid water impermeable material relative to the roller and contacting the roller with the surface of the layer of water vapour permeable and liquid water impermeable material. The step of applying the adhesive can include applying the adhesive with a reverse roll coating machine. [0019] The adhesive is preferably a hot melt, adhesive. The adhesive can contain oxides of antimony. The adhesive can contain an inorganic flame retardant additive to promote charring selected from the group including iron oxides, hydrated calcium and magnesium carbonates, bismuth oxides and carbonates, boric acid, a borate, WO 2015/027282 PCT/AU2014/000858 5 phosphorus as organic phosphates or as inorganic acid phosphates or any combination thereof. [0020] The layer water vapour permeable and liquid water impermeable material can be comprised of a flexible non-woven polymeric material that is water vapour permeable and liquid water impermeable. The layer of water vapour permeable and liquid water impermeable material can be comprised of a flexible non-woven polymeric material laminated to a film of polymeric material that is water vapour permeable and liquid water impermeable. The film of polymeric material can be a microporous film comprised of a matrix of polymeric material and a solid, dispersed material embedded in the matrix. The solid dispersed material can include calcium carbonate. The sheet of flexible non-woven polymeric material can be laminated to the film of polymeric material with another adhesive. The layer of water vapour permeable material can be comprised of a flexible non-woven polymeric material or a Kraft paper material coated or impregnated with a flame retardant. The flexible non woven polymeric materials of the aforementioned embodiments can be formed from polypropylene, polyethylene, polyester, polyvinyl chloride or any combination thereof. [0021] The method of can further include coating one of the layers with a metal by vapour deposition. The method can further include providing an additional fibrous layer which may be woven or non-woven The additional fibrous layer can include strands of fibreglass or woven tapes of extruded polymer embedded in the adhesive between the first and second layers. [0022] Embodiments of the present invention are advantageous in that they provide a membrane for use in construction, such as an underlay for lining roof and/or wall structures, which permits the flow of water vapour from within the building structure to the external atmosphere. Embodiments of the present invention are also advantageous in that they provide a membrane for use in construction, such as an underlay for lining roof and/or wall structures, which exhibits flame retardant properties.

WO 2015/027282 PCT/AU2014/000858 6 Brief Description of the Drawings [0023] The present invention will now be described with reference to the accompanying drawings, of which at least some illustrate embodiments of the invention, wherein: [0024] Figure 1 illustrates a perspective view of a flexible laminated building membrane in accordance with an embodiment of the invention wherein the membrane includes a first layer of flexible material that is water vapour permeable and liquid water impermeable, a second layer of flexible material that is water vapour permeable, and a flame retardant and water vapour permeable adhesive between the first and second layers. [0025] Figure 2 illustrates a schematic view of an apparatus for forming a flexible laminated building membrane by a method in accordance with an embodiment of the invention including, a roll from which is fed a first layer of flexible material that is water vapour permeable and liquid water impermeable, a roll from which is fed a second layer of flexible material that is water vapour permeable, and a roll for applying a flame retardant and water vapour permeable adhesive to a surface of the second layer and a pair of nip rollers for laminating together the first and second layers with the adhesive therebetween. [0026] Figure 3 illustrates a section of the second layer after the flame retardant and water vapour permeable adhesive is applied to a surface of the second layer in accordance with the embodiment of the method illustrated in Figure 2. [0027] Figure 4a illustrates a perspective view of a section of a flexible laminated building membrane in accordance with an embodiment of the invention wherein the membrane includes a first layer of flexible material comprised of a flexible non-woven polymeric material laminated to a film of polymeric material that is water vapour permeable and liquid water impermeable, a second layer of flexible material that is water vapour permeable and a flame retardant and water vapour permeable adhesive therebetween.

WO 2015/027282 PCT/AU2014/000858 7 [0028] Figure 4b illustrates a perspective view of the first layer of flexible material with the water vapour permeable and a flame retardant and water vapour permeable adhesive applied thereto. [0029] Figure 4c illustrates a perspective view of a section of the flexible laminated building membrane of Figure 4a showing the layers comprising the membrane. [0030] Figure 5 illustrates a schematic view of the apparatus of Figure 3 used in a method for forming the flexible laminated building membrane of Figures 4a to 4c. [0031] Figure 6a illustrates a side view of a cross section of a flexible laminated building membrane in accordance with an embodiment of the invention wherein the membrane includes a first layer of flexible material that is water vapour permeable and liquid water impermeable, a second layer of flexible material that is water vapour permeable, a flame retardant and water vapour permeable adhesive and a reinforcement layer between the first and second layers, and a layer of metal applied to a surface of the second layer. [0032] Figure 6b illustrates a perspective view of a section of the flexible laminated building membrane of Figure 6a showing the layers comprising the membrane. [0033] The present invention will now be described in more detail with reference to preferred embodiments of the invention illustrated in the figures. Detailed Description [0034] The present invention broadly includes a flexible building membrane including a layer of flexible material that is water vapour permeable and liquid water impermeable and a flame retardant and water vapour permeable material applied to the layer of flexible material. In a preferred embodiment, the membrane further includes a layer of flexible material that is water vapour permeable and the flame retardant and water vapour permeable material is an adhesive between the layers. In other embodiments disclosed herein, the flame retardant and water vapour permeable material can include a layer of material that exhibits flame retardant properties such as a layer of Kraft paper impregnated or coated with flame retardant material that is WO 2015/027282 PCT/AU2014/000858 8 adhered to the layer of flexible material that is water vapour permeable and liquid water impermeable with an adhesive that in one embodiment has flame retardant properties an in another embodiment does not have flame retardant properties. [0035] Preferred embodiments of the invention are disclosed herein including a flexible, vapour permeable membrane comprised of a laminate of a layer, referred to herein as a first layer, that is a water vapour permeable layer which is liquid water impermeable and another layer, referred to herein as a second layer, comprised of a water vapour permeable layer which is liquid water permeable. The layers are interposed by a water vapour permeable and flame retardant layer. In embodiments, the water vapour permeable and flame retardant layer is an adhesive between the first and second layers. In embodiments where the second layer exhibits flame retardant properties, such as a flame retardant coated or impregnated Kraft paper layer, the adhesive may be a flame retardant or non-flame retardant adhesive. The present invention has been developed for use as a roofing underlay membrane, sometimes referred to as a sarking membrane, and is herein described in that context. However, the invention has broader application including, but not limited to, a wall cladding underlay, a flooring underlay and in any other application where a flexible membrane that is water vapour permeable but liquid water impermeable may be of use. [0036] The adhesive layer can be formed as an incomplete or patchy layer comprised of patches of the adhesive with gaps between the patches, such as in the embodiments illustrated in Figures 1 to 3 and 6a, 6b. Alternatively, the adhesive layer can be formed as a substantially continuous film such as in the embodiment illustrated in Figures 4a to 4c. By employing a flame retardant adhesive between the first and second layers that permits the transmission of water vapour through the first and second layers, the resulting laminated membrane is not only water vapour permeable and liquid water impermeable but it also exhibits flame retardant properties, which is a major benefit in materials for use in construction. [0037] Thus, when embodiments of the membrane are employed in a structure as a roof or wall cladding underlay condensation of water vapour from the air within the structure will tend not to accumulate on the internal surface of the membrane. Thus embodiments of the membrane can ameliorate the potential problem of the WO 2015/027282 PCT/AU2014/000858 9 accumulation of condensation on the internal surface of the membrane which can potentially cause damage to the structure beneath the membrane. Membranes in accordance with embodiments of the invention are also advantageous in that they include a layer exhibiting flame retardant properties rendering the membrane capable of inhibiting or resisting the spread of fire in a structure having a roof and/or wall lined with the membrane. In embodiments of the invention in which the layer that exhibits flame retardant properties is an adhesive, that layer also serves the function of adhering or bonding other layers of the membrane together. Thus, embodiments of the present invention can be produced in an economical manner with as few layers and manufacturing steps as possible while still providing enhanced functionality over existing building membranes. First and Second Layers [0038] Figure 1 illustrates a laminated membrane 1 in accordance with an embodiment of the invention including a first layer 10 formed out of flexible, water vapour permeable material which is also liquid water impermeable, a second layer 20 formed out of water vapour permeable material and an intermediate layer 30 of water vapour permeable and flame retardant adhesive. [0039] The first layer 10, which is water vapour permeable and liquid water impermeable, can be comprised of a flexible non-woven polymeric material formed by spun bonding, spun blowing, spun melting, flash bonding or any combination thereof. The polymeric material can be formed from polypropylene, polyethylene, polyester, polyvinyl chloride or similar material or any combination thereof. In other embodiments, the first layer 10 can have a thickness of between 100 pm and 500 pm. Alternatively, the first layer 10 can be formed from a microporous film of polymeric material that is comprised of a matrix of polymeric material and a solid, dispersed material embedded in the matrix such as calcium carbonate. The microporous film is subtantially impervious to liquid water yet can permit the transmission of water vapour and air through the film so as to render the first layer 10 breathable. Alternatively, the first layer 10 can be formed from a film or sheet of polymeric material that is coated or impregnated with a flame retardant.

WO 2015/027282 PCT/AU2014/000858 10 [0040] The material forming the first layer 10 can contain ultraviolet stabilisers, ultraviolet absorbers, such as a colourant or pigment, additives to retard flame propagation and additives to retard mechanical shrinking. The first layer 10 acts as a functional layer resisting penetration of a head of water. [0041] The water vapour permeable second layer 20 can be a non-woven material formed from a polymeric material by spun bonding, spun blowing, spun melting, flash bonding or any combination thereof. Alternatively, the water vapour permeable second layer 20 can be a woven synthetic material, such as a polymeric material or a natural woven fiber. The polymeric material can be formed from polypropylene, polyethylene, polyester, polyvinyl chloride or similar material or any combination thereof. Alternatively, the water vapour permeable second layer 20 can be formed from a Kraft paper material that is coated or impregnated with a flame retardant material. In other embodiments, the second layer 20 can have a thickness of between 100 pm and 500 pm. Alternatively, the second layer 20 can be formed from a microporous film of a form such as is described above. In still yet another embodiment, the second layer 20 can be formed from any film that is at least water vapour permeable and that may, though not necessarily be liquid water permeable. Alternatively, the second layer 20 can be formed from a film or sheet of polymeric material that is coated or impregnated with a flame retardant. [0042] The material forming the second layer 20 can contain ultraviolet stabilisers, absorbers, such as a colourant or pigment, additives to retard flame propagation and additives to retard mechanical shrinking. The second layer 20 acts as a protective layer to prevent degradation upon exposure to corrosive environments, dry heat and ultraviolet radiation. The second layer 20 can contain a colorant, dye or pigment thereby acting as an aesthetic or decorative layer. [0043] The materials forming the first layer 10 and the second layer 20 can be made resistant to ultraviolet light by the incorporation of ultraviolet stabilisers. These ultraviolet stabilisers can be organic compounds that protect polymeric and other light sensitive materials from degradation by sunlight and artificial sources of ultraviolet radiation. Various ultraviolet stabilisers can be employed such as ultraviolet absorbers, such as a colourant or pigment, hindered amines, nickel chelates, hindered phenols and aryl esters.

WO 2015/027282 PCT/AU2014/000858 11 [0044] The materials forming the first layer 10 and the second layer 20 can be made resistant to flame propagation by the incorporation of a fire retardant additive. Such flame retardant additives include inorganic flame retardants such as iron oxides, hydrated calcium and magnesium carbonates, bismuth oxides and carbonates, boric acid, borates such as zinc borate, phosphorus as organic phosphates or as inorganic acid phosphates or any combination thereof. [0045] The materials forming the first layer 10 and the second layer 20 can be made resistant to mechanical shrinking when exposed to prolonged dry heat by the incorporation of additives or by mechanical or thermal processing. [0046] Figures 4a to 4c illustrate a laminated membrane 101 in accordance with another embodiment of the invention. The laminated membrane 101 includes a first layer 210 which is water vapour permeable and liquid water impermeable, a second layer 220 which is water vapour permeable and an intermediate layer 230 of water vapour permeable and flame retardant adhesive 259. The first layer 210 is formed from a flexible non-woven polymeric material 212 laminated to a film of polymeric material 214 that is water vapour permeable and liquid water impermeable. The film of polymeric material 214 is a microporous film comprised of a matrix of polymeric material and a solid, dispersed material embedded in the matrix. The solid dispersed material in the film of polymeric material 214 can include calcium carbonate. The microporous film is subtantially impervious to liquid water yet can permit the transmission of water vapour and air through the film so as to provide a breathable film. The flexible non-woven polymeric material 212 and the microporous film 214 of the first layer are laminated together with another adhesive in a manner so as not to substantially or completely inhibit the water vapour permeability of the first layer 210. The first layer 210 acts as a functional layer resisting penetration of a head of water yet is permeable to water vapour and other gases such as air. [0047] Like the embodiment of Figure 1, in the embodiment of Figures 4a to 4c, the water vapour permeable second layer 220 can be formed from a non-woven polymeric material such as by spun bonding, spun blowing, spun melting, flash bonding or any combination thereof. The polymeric material can be formed from polypropylene, polyethylene, polyester, polyvinyl chloride or similar material or any combination thereof. Alternatively, the water vapour permeable second layer 220 can WO 2015/027282 PCT/AU2014/000858 12 be formed from a Kraft paper material that is coated or impregnated with a flame retardant material. Flame Retardant Layer [0048] In preferred embodiments disclosed herein, the flame retardant adhesive 30, 230 between the first and second layers 10, 20, 210, 220 is a hot melt, thermoplastic adhesive and at least two adjacent layers of the laminate, which in the embodiment of Figure 1 includes the first and second layers 10, 20, 210, 220 are bonded together by the flame retardant adhesive 30, 230. Although a hot melt adhesive is preferred for use as the flame retardant adhesive 30, 230 other adhesives such aqueous or solvent based adhesives could be employed. In some embodiments, the flame retardant adhesive 30, 230 is based on chlorinated paraffin containing filler and other additives promoting adhesion and cohesion. The filler can include calcium carbonate and other additives including ethylene vinyl acetate copolymer, a tackifier such as a hydrocarbon resin, and a synthetic hydrocarbon wax as a viscosity modifier. In some embodiments, the flame retardant adhesive 30, 230 contains oxides of antimony, such as antimony trioxide and/or metal stannates such as zinc stannate or zinc hydroxystannate that act as a synergistic flame retardant compounds dispersed therein. In some embodiments, the flame retardant adhesive 30, 230 contains an inorganic flame retardant additive to promote charring of the combustible material. These inorganic flame retardants may include iron oxides, hydrated calcium and magnesium carbonates, bismuth oxides and carbonates, boric acid, borates such as zinc borate, phosphorus as organic phosphates or as inorganic acid phosphates or any combination thereof. [0049] Alternatively, in embodiments where the water vapour permeable second layer 20, 220 is formed from a Kraft paper material that is coated or impregnated with a flame retardant material the adhesive 30, 230 bonding together the first and second layers 10, 20, 210, 220 may be a flame retardant or non-flame retardant adhesive. The Method [0050] In the embodiment of Figures 1 to 3, the adhesive 30 is applied to a surface 22 of the second layer 20 by a reverse roll coating and laminating apparatus 100. It is to be appreciated that in an alternative embodiment, the method could WO 2015/027282 PCT/AU2014/000858 13 involve the adhesive 30 being applied to a surface 12 of the first layer 10. [0051] The apparatus 100 includes an unwind roller 25 of the material forming the water vapour permeable second layer 20. The second layer 20 is fed continuously to a reverse roll coating apparatus 50. The reverse roll coating apparatus 50 includes a support roller 55, an application roller 56, a repository 58 containing a hot-melt adhesive 59, which in preferred embodiments is a flame retardant hot-melt adhesive, and a metering roller 57. The application roller 56 is partially immersed in the repository 58 where an external surface 56a of the application roller 56 picks up the adhesive 59. The metering roller 57 is positioned closely adjacent to the application roller 55 to provide a coating 56b of the adhesive 59 on the external surface 56a of the application roller 56. The support roller 55 supports the second layer 20 as the second layer 20 is fed in a feed direction between the support roller 55 and the application roller 56. The application roller 56 rotates in the same direction to the direction of rotation of the support roller 55 with the external surface 56a of the application roller 56 being positioned closely adjacent to the surface 22 of the second layer 20. The external surface 56a of the application roller 56 thus moves in the opposite direction to the feed direction of the second layer 20 at a point of contact of the adhesive coating 56b on the external surface 56a of the application roller 56 with the surface 22 of the second layer 20. The adhesive coating 56b on the external surface 56a of the application roller 56 is thereby applied to the surface 22 of the second layer 20 to provide the adhesive 30 thereon. [0052] The hot-melt adhesive 59 is maintained in the adhesive repository 58 at a temperature sufficient to maintain the adhesive 59 in liquid form. Parameters of the reverse roll coating process described herein above can be controlled or modified to ensure that the adhesive 30 applied to the surface 22 of the second layer 20 is water vapour permeable and preferably, but not necessarily, liquid water permeable. Such parameters include a distance or gap between the application roll 56 and the metering roll 57, the speed of rotation of the application roll 56 relative to the metering roll 57 and the feed rate of the second layer in the feed direction. Another variable parameter can include the roughness of the surface 22 of the second layer 20 to which the adhesive 30 is applied. The roughness of the surface 22 of the second layer 20 affects the way in which adhesive 59 is applied. The roughness of the surface 22, containing differential highs and lows, can be varied to result in the adhesive 30 being WO 2015/027282 PCT/AU2014/000858 14 applied predominantly on the highs rather than the lows thus producing a dappled appearance of the adhesive 30 on the surface 22 of the second layer 20. By altering the gap between the application roll 56 and the metering roll 55, the speed of rotation of the application roll 56 relative to the metering roll 55 and the feed rate of the second layer 20, in conjunction with providing a rough surface 22 to the second layer 20 with differential highs and lows, produces a dappled adhesive coating 30 thereon. In addition, or in the alternative, the characteristics of the adhesive 30 itself could be such that when applied to the surface 22 of the second layer 20 the resulting adhesive coating 30 is at least water vapour permeable. [0053] Other parameters of the reverse roll coating process described herein above that can be controlled or modified include the composition, viscosity and temperature of the adhesive 59. Such parameters may all be controlled or modified as necessary to ensure that when the adhesive 59 is applied to the surface 22 of the second layer 20, the adhesive 30 partially, or intermittently, covers the surface 22 of the second layer 20 such as is illustrated in Figure 3. The flow properties of the adhesive can be altered with viscosity modifiers such as synthetic gels or waxes or by altering the liquids and solids ratio. It has been found that by controlling the viscosity and temperature of the adhesive, in conjunction with controlling the feed rate of the second layer 20 and the speed of rotation of the application roller 56 results in a complete coating of the adhesive 59 on the application roller 56 yet only some of the adhesive 59 being transferred, in patches, to the second layer 20. In some embodiments, the adhesive 30 as applied to the surface 22 of the second layer 20 has a dappled appearance, as illustrated in Figure 3, consisting of spots or patches of the adhesive 59. The gaps between the spots or patches of the adhesive 59 allow for the passage of water vapour through the first and second layers 10, 20 of the membrane. In some embodiments, the parameters of the reverse roll coating process may not be responsible for the water vapour permeability of the adhesive coating 30 but rather the characteristics of the adhesive 30 itself could be such that when applied as a continuous film to the surface 22 of the second layer 20 the resulting coating of adhesive is at least water vapour permeable and may also be liquid water permeable. [0054] The second layer 20 having the adhesive 30 applied thereto is fed to a laminating apparatus 60. The laminating apparatus 60 includes an unwind roller 15 of the first layer 10 and a pair of nip rollers 62, 64. The second layer 20 having the WO 2015/027282 PCT/AU2014/000858 15 adhesive applied thereto and the first layer 10 are fed between the nip rollers 62, 64. The second layer 20 having the adhesive 30 applied thereto and the first layer 10 meet between the nip rollers 62, 64 such that a surface 12 of the first layer 10 contacts with the adhesive 30 applied to the surface 22 of the second layer 20. The first and second layers 10, 20, with the adhesive 30 therebetween, are compressed together between the nip rollers 62, 64 to form the laminated membrane 1 which is then fed onto a rewind roller 5. [0055] Although in embodiments disclosed herein the adhesive 30 is comprised of a hot melt adhesive and is applied to the surface 22 of the second layer 20 via a reverse roll coating method, as described herein, it is to be appreciated that other forms of adhesive that are not a hot melt adhesive may be applied to the surface 22 of the second layer 20 and may be applied by other means. Alternatively, the adhesive may be applied to the surface 12 of the first layer. Such other means of applying the flame retardant adhesive may include spraying a flame retardant adhesive onto the surface 12 of the first layer 10 or the surface 22 of the second layer 20 so as to provide a partial or intermittent coating, consisting of spots or patches, as illustrated in Figure 3. Any method of applying the flame retardant adhesive to between the first and second layers 10, 20 whereby the flame retardant adhesive 30 between the first and second layers 10, 20 in the resultant membrane 1 is water vapour permeable may be adopted. In other embodiments, the flame retardant adhesive may be comprised of an adhesive material that is applied to initially form a complete coating of one or the other of the first and second layers 10, 20 and which subsequently becomes an intermittent coating. Other embodiments may employ the use of a fire retardant adhesive material that, when applied in a complete coating, is intrinsically water vapour permeable. In such embodiments, the adhesive 30 may be applied as a complete coating to the surface 22 of the second layer 20 rather than as an incomplete coating yet still not inhibit the vapour permeability of the resulting membrane. [0056] In some embodiments of the flexible building membrane of the invention, a surface of the second layer 20 opposite to the surface 22 coated with the adhesive 30 may be coated with a layer of metal, such as aluminium, by vapour deposition or by other suitable means. The metal coating acts as a barrier to thermal radiation which provides embodiments of the membrane with reflective insulation properties. The WO 2015/027282 PCT/AU2014/000858 16 metal layer is also water vapour permeable so as not to prevent the passage of vapour through the second layer 20 coated by the metal layer and thereby maintaining water vapour passage through the membrane. [0057] In some embodiments of the flexible building membrane of the invention, the membrane can include additional layers to improve the structural characteristics of the membrane. Such additional layers may include a fibrous layer provided in the laminate to provide structural characteristics. The fibrous layer may be comprised of woven or non-woven fibres. Additionally or alternatively, the membrane may be reinforced by strands of fibreglass or woven tapes of extruded polymer located in mass in the flame retardant adhesive 30 between the first and the second layers 10, 20. Such arrangements may be preferred where the membrane is required to act as a structural mesh of sufficient strength to support the weight of a person. Such embodiments of the flexible building membrane may function to provide not only a water vapour permeable, liquid water impermeable and thermally insulating membrane but also a safety mesh for use in the construction of rooves. [0058] Another embodiment of the method is illustrated in Figure 5 in which like features are identified by like reference numerals. The method of Figure 5 is for the production of the laminated membrane 201 of Figures 4a, 4b, 4c and 5 in which the first layer 210 is comprised of a flexible non-woven polymeric material 214 laminated to a film of polymeric material 212 that is water vapour permeable and liquid water impermeable. The film of polymeric material 212 is a microporous film comprised of a matrix of polymeric material and a solid, dispersed material embedded in the matrix. The sheet of flexible non-woven polymeric material 214 is laminated to the film of polymeric material 212 with another adhesive (not shown). It is to be appreciated that in another embodiment, the relative positions of the non-woven polymeric material 214 and the film of polymeric material 212 can be reversed. [0059] In the method of Figure 5, the adhesive 230 is applied to a surface 216 of the first layer 210 by a reverse roll coating and laminating apparatus 100. It is to be appreciated that in an alternative embodiment, the method could involve the adhesive 30 being applied to a surface 222 of the second layer 220. [0060] The apparatus 100 includes an unwind roller 25 of the material forming the WO 2015/027282 PCT/AU2014/000858 17 first layer 210 which is fed continuously to a reverse roll coating apparatus 50. The reverse roll coating apparatus 50 applies a flame retardant hot-melt adhesive 59 to form a layer of adhesive 230 to the surface 216 of the first layer 210 and subsequently brings the adhesive coated first layer into contact with a surface 222 of the second layer 220 between a pair of nip rollers 62, 64. The first and second layers 210, 220, with the adhesive 230 therebetween, are compressed together between the nip rollers 62, 64 to form the laminated membrane 201 which is then fed onto a rewind roller 205. [0061] Figures 6a and 6b illustrates a side view of a cross section of a flexible laminated building membrane 101 in accordance with another embodiment of the invention wherein the membrane 101 includes a first layer 110 comprised of a flexible material that is water vapour permeable and liquid water impermeable, a second layer 120 comprised of a flexible material that is water vapour permeable, a flame retardant and water vapour permeable adhesive 130 and a reinforcement layer 140 between the first and second layers 110, 120. A layer 150 comprised of metal is applied to the second layer 120. More particularly, the embodiment of the membrane 101 illustrated in Figures 6a, 6b includes the following layers: * 500 pm thick non-woven, water vapour permeable and liquid water impermeable layer (110) formed from melt-blown polypropylene filaments with a nominal weight of 90 g/m 2 containing ultraviolet stabilisers, flame retardant additives and additives to retard mechanical shrinking; * flame retardant and water vapour permeable, hot-melt adhesive (103) with a coating weight of 60 g/m 2 . * fibreglass scrim (140) reinforcement comprised of tri-directional strands of fiberglass; * 200 pm thick non-woven, water vapour permeable second layer (120) formed from spun-bonded polypropylene filaments with a nominal weight of 60 g/m 2 containing ultraviolet stabilisers, flame retardant additives and additives to retard mechanical shrinking; and WO 2015/027282 PCT/AU2014/000858 18 * a water vapour permeable coating of aluminium (150) applied by vapour deposition. [0062] Finally, it will be appreciated that variations and or modifications may be made to the components herein described without departing from the spirit of ambit of the invention.

Claims

1. A flexible building membrane including: - a layer of flexible material that is water vapour permeable and liquid water impermeable; and - a flame retardant and water vapour permeable material applied to the layer of flexible material.

2. The membrane of claim 1, further including: - a layer of flexible material that is water vapour permeable; and - wherein the flame retardant and water vapour permeable material is an adhesive between the layers.

3. The membrane of claim 2, wherein the flame retardant and water vapour permeable adhesive is formed in an adhesive layer between the layers of flexible material that permits the passage of water vapour through the layers of flexible material.

4. The membrane of claim 3, wherein the flame retardant and water vapour permeable adhesive layer is formed as patches of the adhesive with gaps between the patches.

5. The membrane of claim 3, wherein the flame retardant and water vapour permeable adhesive layer is formed as a substantially continuous film.

6. The membrane of any one of the preceding claims, wherein the flame retardant and water vapour permeable adhesive is comprised of a hot melt adhesive.

7. The membrane of any one of the preceding claims, wherein the flame retardant and water vapour permeable adhesive contains oxides of antimony.

8. The membrane of any one of the preceding claims, wherein the flame retardant and water vapour permeable adhesive contains an inorganic flame retardant WO 2015/027282 PCT/AU2014/000858 20 additive to promote charring selected from the group including iron oxides, hydrated calcium and magnesium carbonates, bismuth oxides and carbonates, boric acid, a borate, phosphorus as organic phosphates or as inorganic acid phosphates or any combination thereof.

9. The membrane of any one of the preceding claims, wherein the layer of flexible material that is water vapour permeable and liquid water impermeable is comprised of a flexible non-woven polymeric material.

10.The membrane of claim 9, wherein the layer of flexible material that is water vapour permeable and liquid water impermeable is comprised of a flexible non woven polymeric material laminated to a film of polymeric material that is water vapour permeable and liquid water impermeable.

11.The membrane of claim 9, wherein the film of polymeric material is a microporous film comprised of a matrix of polymeric material and a solid, dispersed material embedded in the matrix.

12.The membrane of claim 11, wherein the solid dispersed material includes calcium carbonate.

13. The membrane of any one of claims 9 to 12, wherein the flexible non-woven polymeric material is laminated to the film of polymeric material with another adhesive.

14.The membrane of any one of the preceding claims, wherein the layer of flexible material that is water vapour permeable is comprised of a flexible non-woven polymeric material.

15.The membrane of any one of claims 1 to 13, wherein the layer of flexible material that is water vapour permeable is comprised of Kraft paper material.

16.The membrane of claim 15, wherein the Kraft paper material is coated or impregnated with a flame retardant.

17.The membrane of any one of the preceding claims, wherein the layers of flexible material each have a thickness of between 100 pm and 500 pm. WO 2015/027282 PCT/AU2014/000858 21

18.The membrane of any one of the preceding claims, wherein either one or both of the layers of flexible material contain ultraviolet stabilisers, additives to retard flame propagation and additives to retard mechanical shrinking.

19.The membrane of any one of the preceding claims, wherein either one or both of the layers of flexible material is coated with a layer of metal by vapour deposition.

20.The membrane of any one of the preceding claims, further including an additional fibrous layer which may be woven or non-woven.

21.The membrane of claim 20, wherein the additional fibrous layer includes strands of fibreglass or woven tapes of extruded polymer embedded in the adhesive between the first and second layers.

22.A method of forming a flexible building membrane including: - providing a layer of flexible material that is water vapour permeable and liquid water impermeable; and - providing a flame retardant material on the layer of flexible material that is water vapour permeable after application on the layer of flexible material.

23.The method of claim 22, including: - providing a further layer of flexible material that is water vapour permeable; and - wherein the flame retardant material is an adhesive provided between the layers of flexible material.

24. The method of claim 23, wherein the adhesive is applied in patches with gaps between the patches or in a continuous film to a surface of the layer of flexible material that is water vapour permeable and liquid water impermeable.

25.The method of claim 24, wherein the step of applying the adhesive includes continuously providing the adhesive to a rotating roller, continuously feeding the layer of water vapour permeable and liquid water impermeable material relative to WO 2015/027282 PCT/AU2014/000858 22 the roller and contacting the roller with the surface of the layer of water vapour permeable and liquid water impermeable material.

26.The method of claim 24 or claim 25, wherein the wherein the step of applying the adhesive includes applying the adhesive with a reverse roll coating machine.

27.The method of any one of claims 23 to 26, wherein the adhesive is a hot melt, adhesive.

28.The method of any one of claims 23 to 27, wherein the adhesive contains oxides of antimony.

29.The method of any one of claims 23 to 28, wherein the adhesive contains an inorganic flame retardant additive to promote charring selected from the group including iron oxides, hydrated calcium and magnesium carbonates, bismuth oxides and carbonates, boric acid, a borate, phosphorus as organic phosphates or as inorganic acid phosphates or any combination thereof.

30.The method of any one of claims 22 to 29, wherein the layer water vapour permeable and liquid water impermeable material is comprised of a flexible non woven polymeric material that is water vapour permeable and liquid water impermeable.

31.The method of any one of claims 22 to 29, wherein the layer of water vapour permeable and liquid water impermeable material is comprised of a flexible non woven polymeric material laminated to a film of polymeric material that is water vapour permeable and liquid water impermeable.

32.The method of claim 31, wherein the film of polymeric material is a microporous film comprised of a matrix of polymeric material and a solid, dispersed material embedded in the matrix.

33.The method of claim 32, wherein the solid dispersed material includes calcium carbonate.

34. The method of any one of claims 22 to 33, wherein the sheet of flexible non woven polymeric material is laminated to the film of polymeric material with another adhesive. WO 2015/027282 PCT/AU2014/000858 23

35.The method of any one of claims 22 to 34, wherein the layer of water vapour permeable material is comprised of a flexible non-woven polymeric material or a Kraft paper material coated or impregnated with a flame retardant.

36.The method of any one of claims 31 to 35, wherein the flexible non-woven polymeric material is formed from polypropylene, polyethylene, polyester, polyvinyl chloride or any combination thereof.

37.The method of any one of claims 22 to 36, further including coating one of the layers with a metal by vapour deposition.

38.The method of any one of claims 22 to 37, further including providing an additional fibrous layer which may be woven or non-woven.

39.The method of claim 38, wherein the additional fibrous layer includes strands of fibreglass or woven tapes of extruded polymer embedded in the adhesive between the first and second layers.