AU2009201572A1

AU2009201572A1 - Coated Fibre Cement Panels

Info

Publication number: AU2009201572A1
Application number: AU2009201572A
Authority: AU
Inventors: Doug Lavender
Original assignee: CSR Building Products Ltd
Current assignee: CSR Building Products Ltd
Priority date: 2008-04-23
Filing date: 2009-04-23
Publication date: 2009-11-12
Also published as: NZ576422A

Description

mcinnes patents AUSTRALIAN PATENTS ACT 1990 COMPLETE PATENT SPECIFICATION TITLE: Coated Fibre Cement Panels APPLICANT: CSR Building Products Limited Level 4, 9 Help Street Chatswood NSW 2067 INVENTOR: Doug Lavender Level 4, 9 Help Street Chatswood NSW 2067 ADDRESS FOR HODGKINSON McINNES PATENTS SERVICE: Patent & Trade Mark Attorneys HMcIP REFERENCE: P20810AU01 2 COATED FIBRE CEMENT PANELS TECHNICAL FIELD 5 The present invention relates to building panels that have been treated with a protective material that is applied to all surfaces of the panel. The present invention particularly relates to fibre cement and plasterboard sheeting that has been treated in this way. 10 BACKGROUND TO THE INVENTION Conventionally, compressed fibre cement panels that are used for 15 facades on buildings are treated with three different types of sealer, namely a "blocking sealer", a "key coat" and an "acrylic primer". The rear surfaces of the fibre cement panels are coated with a "blocking sealer", which is designed to impede moisture migration from the 20 cavity in the wall behind the panel. However, this "blocking sealer" provides poor adhesion for any other coating, such as paint or any other decorative finish that may wish to be applied to the fibre cement panels. Accordingly, when using fibre cement panels that have been sealed in a conventional way, it is imperative that the rear face is always installed facing inwards. 25 The front faces of the fibre cement panels are traditionally treated with a key coat primer, which is subsequently coated with paint or other desired decorative finishes that may be desirably applied to the fibre cement panels. The key coat primer helps to protect the fibre cement 30 panels from the ingress of moisture and increases the lifespan of the fibre cement panels.

3 The side edges of the fibre cement panels are conventionally treated with an acrylic primer, which is designed to impede moisture movement within the fibre cement panel itself. 5 It is currently recommended that fibre cement panels, whether they are untreated or treated in a conventional manner, should not be used in Alpine areas because of freeze/thaw effects. In Alpine areas, the temperatures soar relatively high during the day, while dropping greatly at night, often below freezing. As the fibre cement panels heat up and expand 10 by day, and cool and contract by night, stress is often exerted on the outer surfaces of the panel. The stress causes the peeling off of the outer surfaces of the fibre cement panels in thin sheets. Though this is caused mainly by temperature changes, thermal expansion is enhanced by the presence of moisture. Particular damage to the fibre cement panels can occur within is cracks that may be present in the fibre cement panels. The cracks grow larger as they attract liquid water from the surrounding area. The ice crystal growth weakens the panels, which in time can begin to disintegrate and break up. 20 The phenomenon is caused by the almost unique property of water in having its greatest density at 4 C, so ice is of greater volume than water at the same temperature. Accordingly, when water freezes, it expands and puts its surroundings under intense stress. When water that has entered the joints freezes, the ice that forms can strain the walls of the joints and cause 25 the joints to deepen and widen. This is because the volume of water expands by approximately 9% when it freezes. When the ice thaws, water can flow further into the fibre cement panels. When the temperature again drops below the freezing point and the water freezes again, the ice enlarges the joints further. Repeated freeze-thaw action weakens the fibre cement 30 panels, which can deteriorate over time and break up, particularly along the joints, which can separate into angular pieces.

4 Accordingly, there is a need to provide improved fibre cement and plasterboard panels, or at least an improved method of treating fibre cement and plasterboard panels. This would overcome at least some of the disadvantages of previously known approaches in this field, or would 5 provide a useful alternative. DISCLOSURE OF THE INVENTION 10 These and other advantages are met with the present invention, which in one broad form concerns a building panel having front, rear and side edge surfaces. Each of the surfaces have a substantially identical surface treatment applied thereon, which forms a hydrophobic barrier on each one of the surfaces. 15 Preferably, the surface treatment is a layer of silicone primer that is applied to each of the surfaces of the building panel. The silicone primer is selected from, "silicone, polydimethylsiloxane, polysiloxane, silane, potassium metyl siliconate, isomeric octyltriethoxysilane, synthetic resin, 20 oranic polymer, organosiloxane, oligomeric siloxane or hydrogen polysiloxane". In one embodiment, the silicone primer is a solvent. In another embodiment, the silicone primer is water based. 25 In one embodiment, the silicone primer is substantially transparent, whilst in another embodiment, the silicone primer contains colour pigmentation and is substantially opaque. 30 Preferably, the silicone primer can readily be painted or have other decorative finishes applied thereto. Preferably, the silicone primer provides UV protection.

5 The building panel is preferably a fibre cement or plasterboard panel. The building panel preferably has freeze/thaw resistance and is 5 adapted for installation and use in Alpine areas. The building panel is preferably adapted for external installation on a facade of a building, a floor for a decking or other structure or for internal installation in a wet area. 10 In a further broad form, the present invention concerns a method of treating a building panel having front, rear and side edge surfaces by applying a substantially identical surface treatment to each one of the surfaces to form a hydrophobic barrier on each one of the surfaces. 15 Preferably, the surface treatment is a silicone primer. The silicone primer is selected from, "silicone, polydimethylsiloxane, polysiloxane, silane, potassium metyl siliconate, isomeric octyltriethoxysilane, synthetic resin, oranic polymer, organosiloxane, oligomeric siloxane or hydrogen 20 polysiloxane". Preferably, the building panel is a fibre cement or plasterboard panel. In a further broad form, the present invention concerns a method of 25 installing a treated building panel having front, rear and side edge surfaces onto a building whereby either the front or the rear surface can be installed facing inwards. 30 BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in 6 which: FIG 1 is a perspective view of a wall being constructed with building panels that have been conventionally treated according to the prior art; 5 FIG 2a is an enlarged transverse cross-sectional view of a building panel according to the present invention; FIG 2b is an enlarged cross-sectional view of the building panel 10 shown in FIG 2a shown in end view; and FIG 3 is a perspective view of a plurality of building panels shown in FIG 2 installed in a bathroom. 15 BEST MODES FOR CARRYING OUT THE INVENTION FIG 1 shows a wall of a building being constructed using prior art fibre cement building panels 1 that have been treated in a conventional 20 way. Prior to being installed on the wall of the building, the building panels 1 are arranged in stacks located adjacent to the building. In the first stack 6a, the front face 2 of each of the building panels 1 is orientated in the 25 direction facing out of the page. On the other hand, in the second stack 6b, the rear face 3 of each of the building panels 1 is orientated in the direction facing out of the page. When installing the fibre cement building panels 1 that have been treated according to prior art conventional techniques, i.e. having three different types of sealer, namely a "blocking sealer", a "UV 30 sealer" and an "acrylic primer" applied to the different surfaces thereof, it is necessary to ensure that the front face 2 of each of the building panels 1 is facing outwards when the panels are installed on the wall. This is because the "blocking sealer" that is conventionally applied to the rear face 3 of the 7 building panels 1 provides poor adhesion for any other coating, such as paint or any other decorative finish that may wish to be applied to the fibre cement panels. Accordingly, when using fibre cement building panels 1 that have been sealed in a conventional way, it is imperative that the rear face 3 5 is always installed facing inwards. As shown in FIGS 2a and 2b, the front, rear and side edge surfaces 2, 3, 4a-4d respectively of each of the building panels 1 are treated with a silicone primer 5 that forms a hydrophobic barrier between each of the 10 surfaces of the building panel and the atmospheric environment. The building panels 1 are preferably fibre cement or plasterboard panels, although any suitable building panels may be used. The silicone primer 5 is selected from the following group of materials, "silicone, polydimethylsiloxane, polysiloxane, silane, potassium metyl siliconate, is isomeric octyltriethoxysilane, synthetic resin, oranic polymer, organosiloxane, oligomeric siloxane or hydrogen-polysiloxane". Preferably, the silicone primer 5 is one of the suitable products marketed under the trade name "SILRES BS"* by Wacker Silicones. 20 The silicone primer 5 may be a solvent or alternatively, it may be water based. Depending on the application in which the treated building panels 1 of the present invention are to be used, the silicone primer 5 may be either clear or it may contain colour pigmentation. In any case, the silicone primer 5 can be readily painted or have other decorative finishes 25 applied thereto. In addition to providing UV protection to the building panels 1, the silicone primer 5 provides a high level of hydrophobicity to the front, rear and side edge surfaces 2, 3, 4a-4d. The hydrophobic properties of the 30 silicone primer 5 effectively blocks the migration of moisture into the building panel 1. As the silicone primer 5 is applied to each of the front 2, rear 3 and side edge 4a-4d surfaces of the building panel 1, unlike conventionally treated building panels, there is no dedicated front or back 8 surface. This allows the building panels 1 that are treated according to the present invention to be installed in any orientation. Unlike conventional fibre cement building panels 1 that are not 5 recommended for use in Alpine areas because of the effects of freeze/thaw cycles, the hydrophobic nature of the silicone primer 5 also allows the building panels 1 that are treated according to the present invention to be installed in Alpine areas. This is because the devastating freeze/thaw effects when water has entered the building panels 1 is eliminated or at least 10 substantially reduced by the hydrophobic barrier. The building panels 1 that have been treated with the silicone primer 5 in accordance with the present invention are typically used for external facades on buildings or for floors on decking or other structures. However, 15 as shown in FIG 3, the treated building panels may also be used in internal wet areas such as bathrooms and the like. When used in such applications, the silicone primer 5 provides a hydrophobic barrier that protects the fibre cement or plasterboard building panels 1 from water damage. The silicone primer 5 also reduces the likelihood that mould or mildew will be able to 20 grow on the plasterboard panels when subjected to wet, humid conditions commonly found in bathroom environments. The treatment of the building panels 1 with the silicone primer 5 can be carried out in a factory environment or on a building site where the 25 panels are to be installed. The silicone primer 5 may be applied to the building panels 1 by a brush, a paint roller, spray equipment, which may be portable which is particularly useful when the building panels are treated on site or a sophisticated in-line spraying apparatus, which would be used when the panels are treated in a factory environment. 30 It will be apparent that obvious variations or modifications may be made which are in accordance with the spirit of the invention and which are 9 intended to be part of the invention, and any such obvious variations or modifications are therefore within the scope of the invention. In this specification, unless the context clearly indicates otherwise, the 5 term "comprising" has the non-exclusive meaning of the word, in the sense of "including at least" rather than the exclusive meaning in the sense of "consisting only of". The same applies with corresponding grammatical changes to other forms of the word such as "comprise", "comprises" and so on. 10 INDUSTRIAL APPLICABILITY The invention can be utilised in building panels that have been is treated with protective coating that is applied to all surfaces of the panel. The present invention particularly relates to fibre cement and plasterboard sheeting that has been treated in this way.

Claims

1. A building panel having front, rear and side edge surfaces, each of said surfaces having a substantially identical surface treatment applied thereon, which forms a hydrophobic barrier on each one of the surfaces.

2. A building panel of claim 1 wherein the surface treatment is a layer of silicone primer that is applied to each of the surfaces of the building panel.

3. A building panel of claim 2 wherein the silicone primer is selected from, "silicone, polydimethylsiloxane, polysiloxane, silane, potassium metyl siliconate, isomeric octyltriethoxysilane, synthetic resin, oranic polymer, organosiloxane, oligomeric siloxane or hydrogen polysiloxane".

4. A building panel of claim 2 or 3 wherein the silicone primer is a solvent.

5. A building panel of claim 2 or 3 wherein the silicone primer is water based.

6. A building panel of claim 2 or 3 wherein the silicone primer is substantially transparent.

7. A building panel of claim 2 or 3 wherein the silicone primer contains colour pigmentation and is substantially opaque.

8. A building panel of claim 2 or 3 wherein the silicone primer can readily be painted or have other decorative finishes applied thereto. 11

9. A building panel of claim 2 or 3 wherein the silicone primer provides UV protection.

10. A building panel of any of the preceding claims being a fibre cement or plasterboard panel.

11. A building panel of claim 1 having freeze/thaw resistance and being adapted for installation and use in Alpine areas.

12. A building panel of claim 1 adapted for external installation on a facade of a building, a floor for a decking or other structure or for internal installation in a wet area.

13. A method of treating a building panel having front, rear and side edge surfaces by applying a substantially identical surface treatment to each one of the surfaces to form a hydrophobic barrier on each one of the surfaces.

14. A method of treating a building panel of claim 12 wherein the surface treatment is a silicone primer.

15. A method of treating a building panel of claim 14 wherein the silicone primer is selected from, "silicone, polydimethylsiloxane, polysiloxane, silane, potassium metyl siliconate, isomeric octyltriethoxysilane, synthetic resin, oranic polymer, organosiloxane, oligomeric siloxane or hydrogen-polysiloxane".

16. A method of treating a building panel of claim 12 wherein the building panel is a fibre cement or plasterboard panel.

17. A method of installing a treated building panel having front, rear and side edge surfaces onto a building whereby either the front or the rear surface can be installed facing inwards. 12

18. A building panel substantially as hereinbefore described with reference to any one or more of the Examples and accompanying drawings (excluding FIG 1).

19. A method of treating a building panel substantially as hereinbefore described with reference to any one or more of the Examples and accompanying drawings (excluding FIG 1).

20. A method of installing a treated building panel substantially as hereinbefore described with reference to any one or more of the Examples and accompanying drawings (excluding FIG 1).