The present invention relates to coverings, membranes, and related sheet materials. More specifically, it relates to such sheet materials that have fireproof, or fire-resistant or retardant properties, that may meet standards, such as the European standard EN 13501-1 , and hence be “Fire Classified”.

In the construction industry there is a requirement during certain parts of the construction of a new building to add membranes to the building. This may be for various reasons, such as damp proofing, waterproofing, thermal insulation or fire resistance, or some combination of these.

At present the most common material for use as a waterproof membrane is known as EPDM (ethylene propylene diene monomer) rubber. This material provides good waterproofing properties.

There has been increased interest in ensuring that buildings are built or adapted to be as resistant to the spread of fire as is practically possible and achievable, and hence there is increasing interest in the fireproof qualities of membranes used in a building structure. EPDM is a highly combustible material, and can contribute to the spread of flame in a fire situation, which limits its utility in some situations.

Embodiments of the invention have the object of addressing one or more of the above shortcomings of the background art.

According to a first aspect of the invention there is provided a fire-resistant vapour barrier membrane for use in the construction of buildings and comprising a layered structure forming a flexible sheet, and having a first layer of glass fibre, and a second layer of silicone coating, wherein the glass fibre comprises a greater proportion of the material than the silicone, and the ratio, by weight, of glass fibre to silicone is within the range of 51 :49 to 99:1.

An embodiment therefore provides a membrane sheet, that may be used as a vapour barrier layer in the building and construction industry. It may be used anywhere that traditional vapour barriers are used, but has the additional benefit over prior art vapour barriers of providing an improved level of fire resistance (and is capable of being fire rated), whilst maintaining a waterproof barrier.

The materials used, as mentioned above, provide a degree of fire resistance, in slowing the passage of a fire across the membrane. Embodiments therefore provide a significant benefit over the use of EPDM membranes, and may be used in areas where EPDM is currently not suited. Appropriate choice of the material thicknesses, such as those mentioned below, may be made to achieve fire resistance to certain regulatory levels.

Some embodiments of the invention may achieve class A according to the European standard EN 13501-1 , with some embodiments achieving A1 , and others meeting the A2-s1-d0 classification, depending upon the formulation used. A product made according to the invention that meets the A classification (either A1 or A2) as stated above is known herein as being “Fire Classified”. Of course, embodiments may also meet other standards, as determined by other standards setting bodies.

The membrane barrier is normally used, when laid horizontally, with the silicone layer being uppermost, but may be used in any orientation, to suit the application and conditions in which it is being used. For example, it may be used in a vertical orientation, or on an incline, or in a horizontal orientation, with either surface uppermost. When used in a vertical orientation the silicone layer is preferably laid facing outwards, and in such situations, it is typically used under a building fagade etc. It may be fixed with adhesive, or in any other suitable manner.

It may be used in sheet form, or may be cut into smaller pieces, for example into thin strips that are used to e.g., seal fagade interfaces etc. Other applications include, but are not limited to, sealing units back to structure, or to non-structural infill walling or onto other waterproofing membranes. Further uses include, but aren’t limited to, use in roofing, or other internal applications, where for example they may be used in controlling the passage of vapour. In some embodiments the ratio, by weight, of glass fibre to silicone is within the range of 80:20 to 65:35. Choosing the ratio of materials within this range can provide additional benefits in terms of durability, although ratios outside of this range do still have utility for some applications.

Advantageously, in some embodiments the silicone coating is a high temperature vulcanising (HTV) coating. This eases manufacture by allowing the coating to be applied whilst providing greater flexibility in terms of the timing of the drying process, as compared to a room temperature vulcanising (RTV) coating. Some embodiments may comprise of an RTV silicone coating however.

In some embodiments the silicone coating may contain a solid polymer. Polymers improve the ability to spread the silicone onto the glass fibre layer during production. Other embodiments may have a solvent-based polymer, Thus, the silicone in such embodiments is a solvent-based silicone. Each type of silicone has its advantages. Solid polymer silicones tend to have improved fire-resistance over solvent-based ones, whereas solvent based ones tend to have increased workability at the manufacturing stage, which results in a better ability to fill small gaps, voids and spaces in the glass fibre. This tends to result in improved watertightness. The skilled person will therefore choose the polymer type, for a particular embodiment, according to the desired application.

Preferably, some embodiments further have a finish content that may be used to provide a desired colour to the product. In some embodiments the finish content is added to the silicone before the silicone is applied to the glass fibre layer. The finish content may be chosen from e.g. aluminium and carbon black. It may be present in the membrane at a percentage by weight of between e.g. 0.1% and 10%, and more preferably between 1% and 5%. In some embodiments it may be present at approximately 3%. Other finish content materials may be used, in appropriate proportions, as appropriate for a given task or function.

Some embodiments may have one or more layers in addition to those mentioned above, that may have a colouring, or other function. In some embodiments the glass fibre layer has fibres having an average diameter of between 1 pm and 15pm. This range gives the designer the choice of material properties, e.g., trading flexibility for strength, as required for a particular purpose or application.

The glass fibre layer may in some embodiments be formed using a continuous filament process, using a binder. It may in some embodiments comprise a woven mat, or may in other embodiments be a non-woven layer. It may be formed in other embodiments using other, e.g. known, glass fibre layer production methods

Advantageously, in some embodiments the fibres have an average diameter of between 6pm and 12pm. This gives a good balance of strength and flexibility for many uses.

Even more advantageously, in some embodiments the fibres have an average diameter of approximately 9pm. This has been found to be a good compromise for a general purpose membrane product. The fibres may, in some embodiments, be continuous filament fibres, as explained above.

In some embodiments the glass fibre layer has a thickness of between approximately 0.1mm and 1mm. Other embodiments may go beyond this, e.g. to 1.5mm or 2mm, or even more. The thickness of this layer may be chosen according to desired physical properties of the membrane, such as required strength, and fire rated properties. It will be appreciated by those skilled in the art that increasing the thickness of the glass fibre layer has benefits in terms of the membrane’s fire retardance properties, and so the thickness of the glass fibre layer in any given embodiment can be chosen with this in mind.

Advantageously, the glass fibre layer may have in some embodiments a thickness of between approximately 0.1 and 0.3mm. This has been found to give good material properties for a general-purpose membrane.

In some embodiments the silicone may have a thickness of between approximately 0.03 and 0.3mm, and being typically approx. 0.07mm Again, the thickness may be chosen to provide desired material properties, such as increased wear resistance, UV resistance, or flexibility. Again, other embodiments may have a thickness greater than this, such as 0.5mm or 0.7mm.

The silicone layer provides a degree of ultraviolet (UV) protection, and so advantageously, in use, preferably the silicone side of the membrane should be chosen to oriented towards the sun, or other bright UV source, if the membrane is not covered with some other material.

Advantageously, the membrane may be formed so as to have a surface finish on at least one surface thereof, comprising of pits, bumps, ridges, and/or dimples. This helps to add additional grip for materials sitting on or located against the product when in use, or to act as a keying surface when gluing the material to another surface.

Preferably the silicone layer is arranged to be a continuous, waterproof layer across the sheet. This provides the best fire resistance, and waterproof properties of the membrane.

According to a second aspect of the present invention there is provided a method of making a fire-resistant waterproof membrane for use in the construction industry, comprising the steps of: a) producing a glass-fibre sheet; b) applying a silicone coating across a surface of the glass fibre sheet; and c) curing the silicone coating.

The membrane so produced may be a membrane as describe in relation to the first aspect of the invention, and so optionally have the various features and elements as described above.

Advantageously, some embodiments use a high-temperature vulcanising silicone. This is cured in a curing oven after application to the glass fibre sheet. Alternatively, a room temperature vulcanising silicone can be used Embodiments of the invention will now be described in more detail, by way of example only, and with reference to the accompanying drawing, of which:

Figure 1 shows in profile form an embodiment of the invention.

An embodiment of the invention is shown in profile view in Figure 1. A membrane 10 comprises of a layered structure, having a first layer 12 comprising a glass fibre material (CAS-No.65997-17-3), and a second layer 14 comprising a silicone material (CAS- No.63394-02-5) having a solvent-based polymer. The glass fibre layer comprises of 9pm diameter (on average) fibres in a random orientation on a plane, to form a layer having a thickness of 0.16 - 0.2mm approximately

The glass fibres are mixed with a binder, as is standard in the production of glass fibre layers, and allowed to cure to form the layer as described. The glass fibre layer is then coated with a HTV liquid silicone material dispensed on one side thereof. This is then rolled between rollers to produce a desired thickness and to add a texture to the silicone surface before going into a curing oven, where it is cured to produce a finished product. The silicone layer is typically around 0.07mm thick.

The finished product is rolled up onto a core, with a sheet width of 1500mm, and is typically produced in lengths of up to 500m to produce a master reel. These are then rewound into smaller rolls of 20m length for commercial sale.

A typical use of such a product is to sit behind a fagade on a wall, to provide a waterproof seal. Other constructional uses include waterproofing of roofing structures, or to provide a vapour barrier between floors.

Testing of a product according to this embodiment has been found to meet A2-s1-d0 fire rating when tested according to the European standard EN 13501-1 fire- classified, whilst also meeting British and European water vapour permeability, equivalent air layer thickness, and vapour resistance standards. The embodiment therefore provides a waterproof membrane for building and construction uses, whilst also being capable of meeting UK and European Union fire rating qualifications. The finished membrane may be used in standard manner, where waterproof membranes of broadly similar type are used in the building and construction industry. For example, it may be used in roofing, or in between floors of a multi-story building.

The functions described herein as provided by individual components could, where appropriate, be provided by a combination of components instead. Similarly, functions described as provided by a combination of components could, where appropriate, be provided by a single component.

Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.