FLEXIBLE FIRE BARRIER FOR BUILDINGS

Technical Field of the Invention

The present invention relates generally to flexible fire barriers. In particular, but not exclusively, the invention concerns a flexible fire barrier that is A2 classified as per BS EN ISO 13501-Part 1, is water proof, and is also suitable for use in buildings.

Background to the Invention

Barrier films are one of the most common items that are used in the construction industry throughout the world. This is more prevalent in the developed countries where tall buildings are more common.

The barrier films are mainly used to prevent the spread of moisture and depending on the exact location of the application, they can be either breathable or non- breathable. These can be used either to envelope a large building or to cover just the roof of the building. Sometimes a thicker version of these barriers is used within the wall cavities as cavity trays or as damp-proof courses.

The investigations that had taken place after the Grenfell tower incident in the United Kingdom has highlighted the fact that some of the products that are used in the construction of buildings has led to and/or aided the spread of fire. These investigations are leading to changes in the building regulations and one of the key changes that is being recommended is the use of only Al or A2 classified products, as per EN 13501- 1, in buildings that are more than 18 meters high.

The European classes of reaction to fire performance for construction products excluding floorings are based on four fire test methods: EN ISO 1182 which is a noncombustibility test, EN ISO 1716 which is a gross calorific potential test, the single burning item (SBI) test EN 13823, and EN ISO 11925-2 an ignitability test. The harmonized procedure for the classification of the products based on the above 4 tests is described in EN 13501-1.

Almost all of the barrier products that currently exist in the market are class B and below. The products that are Al classified are predominantly metal based which are very cumbersome to handle, expensive and also add to the weight of the structure. While some A2 classified products do exist, no product exists in the market that has the properties similar to that of a flexible barrier that also prevents the penetration of water.

One of the tests that the material needs to pass along with the above classification, is the EN 1928 water tightness test at 2 kPa. It is the ability to obtain the A1/A2 classification against fire, while also passing the water tightness test which makes it very challenging. No flexible product currently exists in the market that can satisfy both of the above.

Embodiments of the invention seek to at least partially overcome or ameliorate any one or more of the above mentioned disadvantages or provide the consumer with a useful or commercial choice.

Summary of the Invention

According to a first aspect of the invention there is provided a flexible fire barrier comprising a woven inorganic fibre substrate and a fire-resistant and water resistant outer coat applied to the substrate.

Providing a flexible fire barrier in this form provides a lightweight, single layer product to satisfy the A2 classification as per BS EN ISO 13501-1 which is also water tight. The barrier can be formed such that it is less than 1mm thick, lightweight and is easily conformable to any shape.

According to a second aspect of the invention there is provided a method of forming a flexible fire barrier comprising the steps of selecting an inorganic fibre, weaving the inorganic fibre into a selected weight substrate and applying a fire-resistant and water resistant outer coat to the substrate.

The inorganic fibre is typically selected to provide fire resistant properties. Once woven to form the substrate, the substrate will provide dimensional stability to the barrier.

The fibre used is preferably non-metallic.

Any inorganic fibre may be used. Typical fibres that may be used include glass fibre, mineral fibre and/or ceramic fibre. A composite fibre may be used.

The fibre selected may be treated with one or more additives to improve performance or ease processing. Any additives may be used on the fibre prior to, during or after weaving.

The structure of the substrate is preferably selected for optimum strength and weight reduction. A woven substrate is preferred. The weave structure can be an important parameter on the performance of the barrier and/or the ability of the substrate to accept the outer coat. A tight weave pattern will usually be used. In an embodiment, a satin/sateen weave structure is used but any similar tightly woven structure could be used.

A tight weave pattern may alternatively be defined or characterised by ‘cover factor’. Cover factor may be a parameter used in place of or to categorise a weave as being suitable or unsuitable for use in the substrate of the fire-resistant barrier of the present invention.

Cover Factor (provided as a number, without units), indicates the extent to which the area of a weave is covered by a set of threads. It is usually calculated based on parameters relating to the yam, weave structure and thread count used. The ‘weave factor’ and the ‘yarn linear density’ will have an impact on the ‘cover factor’. Cover factor is usually used for comparative purposes of different fabrics rather than defining the ‘tightness’ of a fabric weave.

A cover factor of at least 14 is preferred and more preferred is a cover factor of at least 18. Whilst the upper limit of the cover factor is less important than the lower limit, an upper limit of 28 may be used for the cover factor so that the substrate does not become overly heavy or stiff. The warp threads (called ends) run down the length of the cloth, with the weft threads (picks) being inserted across the width of the cloth.

A weave structure is formed by lifting warp ends vertically over weft picks and by inserting weft picks horizontally across the warp ends.

Without wishing to be limited by theory, satin is a warp faced weave, whilst its counterpart sateen, is the weft faced version and so satin and sateen are the reverse of one another. Where a satin/sateen weave structure is used, a 5-end or 8-end structure may be preferred. This could also be increased to a weave structure having more ends such as a 16-end structure for example. The 8-end weave generally gives a tighter weave as 7 out of 8 warp ends are being lifted at one time.

A single layer or a multi-layer weave may be used.

The substrate may be formed as a single layer or a multi-layer substrate could be used. A single layer substrate will generally be thinner and lighter in weight than a multi-layer substrate. A multi-layer substrate may take advantage of different fibres in one or more layers. Normally, a multi-layer substrate will be heavier in weight than a single layer substrate.

The weight of the substrate will preferably be minimised. The thickness of the substrate will generally increase weight of the fire resistant barrier, although the fibre used will also affect the weight of the substrate. Depending upon the fibre and weave structure selected, a single layer substrate will normally be approximately 0.5mm in thickness.

In an embodiment, the fibre and weave structure selected will result in the weights of the substrate being approximately 600GSM. This gives a flexible substrate which is light in weight that maintains optimum flexibility and weight characteristics after the outer coat is applied. A higher or lower weight substrate may be used for different applications or uses.

The woven substrate will normally be provided in the form of a substantially planar mat or similar having a length and a width, typically woven and provided in a roll.

The woven inorganic fibre substrate has a fire-resistant and water resistant outer coat applied to the substrate.

In one form, the outer coat may be or include a fire-resistant and water resistant polymeric material. The polymeric material used may be or include fluorocarbon-based fluoroelastomer (FKM) or polyurethane.

Fluoroelastomers may be more expensive than neoprene or nitrile rubber elastomers which may make them less preferred. Further, at high temperatures or in a fire, fluoroelastomers may decompose and release hydrogen fluoride which can be adverse. Fluoroelastomers are also of relatively high density, usually of over 1800 kg/m3, significantly higher than other fire-resistant and water resistant polymeric materials which may be preferred due to the above features.

There are numerous types of fluoroelastomers which could be used including, filled and unfilled fluoroelastomer materials. The fluoroelastomer material(s) used may be modified. For example, the fluoroelastomers used may be modified to change viscosity.

There are a wide variety of polyurethanes available which may be used in or as the outer coat of the barrier of the invention. The particular polyurethane selected will normally be both fire-resistant and water resistant. The particular polyurethane selected will preferably form a continuous outer coat above the substrate and may be selected for spreadability as well as fire-resistance and water resistance. The polyurethane may be a polyurethane elastomer.

There are numerous types of polyurethane material which could be used including, filled and unfilled polyurethane materials. The polyurethane material(s) used may be modified. For example, the polyurethane material(s) used may be modified to change viscosity.

In another form, the outer coat may be a silicone-based outer coat applied to the substrate. The silicone-based outer coat will typically comprise mainly silicone rubber as additives such as silica could be added to a silicone rubber material for example, to improve spreadability.

The outer coat is typically applied to one or more sides of the woven substrate. In one form, the outer coat may be applied to one side of the woven substrate only. In another form, the outer coat may be applied to both sides of the woven substrate.

The outer coat may fully encapsulate the substrate. The outer coat may penetrate the weave of the substrate to provide the advantages of the invention even when cut.

The outer coat will typically be applied to form a continuous outer coat. As little material is used to form the outer coat as possible. This will reduce the weight of the barrier and also retain maximum flexibility of the end product barrier.

The method of application of the outer coat will typically be chosen according to the type of outer coat material used or vice versa. As an example, a dipping process may be used for a water-based outer coat material.

Examples of water-based silicone-based materials which could be used include:

• Bluesil™ TCS 7110

• Bluesil™ TCS 7513

• Dowsil™ 7170

• XIAMETER™ MEM0075 Emulsion

• BLUESIL™ EMUL 2600

• SILBIONE™ TCS 7773

A spread coat process could be used for a non-water-based outer coat material. A Doctor blade or Meyer bar spread coating process could be used or a roller transfer process. A precision 'knife-over-air' or 'knife-over-roller' technique could be used. A preformed film can also be adhered via a lamination process.

Examples of non-water-based silicone-based materials which could be used include:

Techsil™ 5600

Bluesil™ TCS 7550

Silastic™ 9151

Silastic™ 9400 Series

Silastic™ FL 40-9201

Techsil™ 5300

The flexible fire barrier of the present invention may include an outer coat formed using both a dip coat and a spread coat. The particular sequence of dip coating and spread coating may be chosen to imbue different properties into the flexible fire barrier. For example, an inner coat layer may better penetrate the weave of the substrate to provide the advantages of the invention even when cut. An outer layer may more fully encapsulate the substrate. A spread coat layer may be used after a dip coat layer has already been applied to the substrate.

The outer coat may be formed from more than one layer of outer coat material. Different materials may be used in different layers of the outer coat. The number of layers and the material of each layer will normally be chosen to different properties into the flexible fire barrier.

There are numerous types of silicone-based material which could be used including, filled and unfilled silicone materials. The silicone-based material(s) used may be modified. For example, the silicone-based material(s) used may be modified to change viscosity.

The barrier (or component thereof) may be coloured. A colour may be used in the outer coat for example. Colouring one surface of the barrier differently to the opposite surface may provide an indication of a preferred orientation for use or installation of the barrier.

One consideration is the ratio between the substrate and the outer coat. As mentioned above, the amount of outer coat material used will preferably be minimised, but it is important that a sufficient amount of outer coat material be provided to provide the water resistance.

In an embodiment, the ratio may stand at 87.5%: 12.5% of substrate and outer coat respectively on a weight basis. Depending on the weight of the substrate fabric used, the ratio could range from 75% - 95% for the substrate and 5%-25% for the outer coat.

Detailed Description of the Invention

In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

Figure 1 is a peg diagram of a satin weave according to an embodiment. Figure 2 is a schematic illustration of the satin weave woven according to the peg diagram shown in Figure 1.

Figure 3 is a comparison of an 8-end satin weave peg diagram with an 8-end sateen weave peg diagram according to an embodiment.

Figure 4 is a schematic view of a flexible fire barrier of an embodiment with an outer coat applied to one side of a substrate.

With reference to the accompanying figures, a flexible fire barrier comprising a woven inorganic fibre substrate and a silicone-based outer coat applied to the substrate is provided.

One specific example of the barrier is a 600 GSM, 8-end, satin glass fabric that has been coated with 85 grams per square metre of silicone-based material in total. The tested product is coloured grey on one side and red on the other. This particular product is being tested for use as a cavity tray.

The inorganic fibre is typically selected to provide fire resistant properties. Once woven to form the substrate, the substrate will provide dimensional stability to the barrier.

The structure of the substrate is preferably selected for optimum strength and weight reduction. A woven substrate is preferred. The weave structure can be an important parameter on the performance of the barrier and/or the ability of the substrate to accept the outer coat. A tight weave pattern will usually be used. In an embodiment, a satin/sateen weave structure is used but any similar tightly woven structure could be used.

Figure 1 shows a peg diagram of a 5-end satin weave and Figure 2 shows the weave formed using that 5-end satin weave structure.

As mentioned above, satin is a warp faced weave, whilst its counterpart sateen (the peg diagrams shown in Figure 3 compare an 8-end satin weave with an 8-end sateen weave), is the weft faced version and so satin and sateen are the reverse of one another. An 8-end weave structure generally gives a tighter weave as 7 out of 8 warp ends are being lifted at one time.

A single layer weave structure is illustrated in the Figures.

A single layer substrate will generally be thinner and lighter in weight than a multi-layer substrate.

The weight of the substrate will preferably be minimised. The thickness of the substrate will generally increase weight, although the fibre used will also affect the weight of the substrate. The example provided above, is a single layer substrate of approximately 0.5mm in thickness which gives a barrier which is less than 1mm in thickness.

The woven substrate will normally be provided in the form of a substantially planar mat or similar having a length and a width, typically woven and provided in a roll.

The barrier illustrated in Figure 4 includes a silicone-based outer coat 30 applied to the substrate 50 (partially peeled away for visibility). The outer coat 30 illustrated in Figure 4 is applied to one side of the substrate 50 but the outer coat may be applied to both sides of the woven substrate and/or to fully encapsulate the woven substrate.

The outer coat normally fully encapsulates the woven substrate. The outer coat may penetrate the weave of the substrate to provide the advantages of the invention even when cut.

The outer coat will typically be applied to form a continuous outer coat.

The method of application of the outer coat will typically be chosen according to the type of outer coat material used or vice versa. As an example, a dipping process may be used for a water-based outer coat material, and a spread coat process may be used for a non-water-based outer coat material.

A Doctor blade or Meyer bar spread coating process could be used or a roller transfer process. In an embodiment, a combination of layers may be used to form the outer coat with one or more layers applied to the substrate using a spread coat process and one or more layers applied to the substrate using a dipping process.

A preformed film can also be adhered via a lamination process. The barrier (or component thereof) may be coloured. A colour may be used in the outer coat for example. Colouring one surface of the barrier differently to the opposite surface may provide an indication of a preferred orientation for use or installation of the barrier.

The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.