Fire barrier products are well known. These are usually installed in the form of a hanging curtain of mineral wool which is continuously supported and secured to a support structure such as timber roofing, metal decks or concrete soffits. The system for fixing the curtain to the supporting structure generally employs metal angles and straps to secure the insulation with nuts and bolts. The conventional system is time consuming for those carrying out the installation. Nevertheless, fire barriers of this type have been on the market for at least 20 years and fixing systems of this general type have been used to date.

The mineral wool is of necessity of relatively high density (eg about 100 kg/m3). The curtain is commonly used as a fire barrier in large cavities and must therefore be relatively long. As a result the curtain tends to be heavy and it is important that the fixing system is sufficiently secure for such a heavy product.

Various fixing systems are known for other types of mineral wool product. For instance the company LaFarge supplies a product called the Cormet Insulation Hold Strip which is a galvanised steel strip having pre-punched arrows in the strip which may be folded outwardly and passed through a mineral wool quilt in order to hold the mineral wool quilt in position. These arrows are useful for maintaining the position of low density, light mineral wool, for instance in cavity insulation, simply to prevent sagging. However, this type of system would be wholly inadequate if used with the heavy duty curtains required for fire barrier products.

A similar construction is described in CA 1,197,064.

This also describes a metal strip having pre-punched barbs or arrows which can be folded outwardly to an angle of

around 90° with the strip. A mineral wool quilt may be impaled on the arrows. Again, this publication describes the purpose of the arrows as prevention of sagging of insulation. There are suggestions that washers may be used on the heads of the arrows and that the arrow may be bent over the washer to secure it in position. However again a product of this type suitable for prevention of sagging of light duty mineral wool would be wholly inadequate for use in a system which is required to suspend a curtain of mineral wool from a supporting structure.

According to the invention we provide a mineral wool barrier comprising a curtain of mineral wool having density of at least 40 kg/m3 which is arranged substantially vertically for at least a portion of its length and which has a top end fixed to a supporting structure by a support system comprising a support plate which is secured to the surface of the supporting structure and which has at least two support tongues which are integral with the support plate and which protrude from the support plate, and the mineral wool curtain is positioned so that a first surface of the mineral wool is in contact with the support plate and the support tongues pass through the mineral wool curtain, and the support system also comprises a holding plate having at least two apertures through each of which a support tongue passes and which is positioned in contact with the second, opposite, surface of the mineral wool curtain, and the tongues are angled so as to secure the holding plate onto the surface of the mineral wool curtain.

The invention also provides a process of fixing a mineral wool barrier comprising providing a curtain of mineral wool having a density of at least 40 kg/m3, securing to the surface of a supporting structure a support plate which has at least two support tongues

integral with the support plate and which protrude from the support plate, positioning the mineral wool curtain such that a first surface of its top end is positioned in contact with the support plate and so that the support tongues pass through the mineral wool curtain, positioning a holding plate having at least two apertures in contact with the second, opposite, surface of the mineral wool curtain so that one support tongue passes through each aperture, and bending the tongues toward the outer surface of the holding plate so as to secure the holding plate onto the surface of the mineral wool curtain.

We find that it is possible to fix a heavy duty, high density curtain of mineral wool suitable for use as a fire barrier to a supporting structure by means of the defined support system. In particular we find that the use of a continuous holding plate having at least two apertures through which the support tongues pass provides a secure and strong support system for heavy duty mineral wool.

The barrier is generally a fire barrier, and in particular is provided in a large cavity.

The mineral wool curtain has density of at least 40 kg/m3. Preferably this is at least 80 kg/m3, more preferably at least 90 kg/m3. It can for instance be up to 400 kg/m3 but is generally not more than 200 kg/m3.

The curtain can have thickness as low as 5 mm, but generally has a thickness of at least 20 mm, preferably at least 30 mm, more preferably at least 40 mm and often around 50 mm. It is generally not more than 150 mm, often not more than 100 mm.

The curtain is arranged substantially vertically for at least a portion of its length, generally the whole of its length. The curtain often has a length of at least 2m.

The top end is fixed to a supporting structure by the support system discussed below. The bottom end may also be fixed to a supporting structure. Alternatively, the

support system can be used to fix a further curtain to the bottom of the first curtain.

The supporting structure can for instance be timber roofing, metal decks or a concrete soffit.

The support plate may have a straight cross-section but is preferably of L-profile cross-section. In this latter case one arm of the L-profile is fixed to the supporting structure and the other arm is provided with the support tongues.

The support plate is fixed to the surface of the supporting structure using any suitable securing means.

The support plate is provided with at least two support tongues integral therewith. These protrude from the support plate and are generally provided by pre- punching the tongues in the support plate and bending the tongues outwardly so that they extend at an angle of from 80 to 100°, usually about 90°, with the surface of the support plate from which they were punched.

The mineral wool curtain is impaled on the support tongues. To assist in this the support tongues may be provided in any suitable shape. They can be essentially rectangular but may be provided with a barb or arrow, or preferably a smooth rounded end, to facilitate impaling the mineral wool curtain. This is particularly useful when the mineral wool is of high density and, as is often the case. with fire barrier mineral wool curtains, is provided with reinforcing metal netting on each surface.

In some embodiments it is desirable for the support tongues to be provided with holes at regular intervals along their length to enable the installer to assess how far onto the support tongues the mineral wool curtain has been impaled.

The support system also comprises a holding plate.

This has at least two apertures positioned to correspond with the support tongues so that a support tongue passes through each aperture. This support plate may also be of

straight cross-section but may alternatively be in the form of a channel.

When the holding plate is in position with the support tongues protruding through the apertures, each support tongue is bent so as to lie substantially in contact with the surface of the holding plate and secure it in position.

The tongues may be bent outwardly from the support plate and bent again on to the holding plate by hand but preferably they are bent using a tool provided for this purpose. Generally this is a steel plate which can be manipulated by hand to bend the tongues.

In some embodiments the support plate may be used to support two parallel mineral wool curtains, one on each side of the support plate and substantially coextensive.

To achieve this, alternate support tongues are bent outwardly in opposite directions so that a series of support tongues protrudes from the support plate on each side of the support plate. A mineral wool curtain may be impaled on each side.

The support plate, support tongues, holding plate and tool if used are generally formed from steel, for instance galvanised steel. This must be of a sufficiently substantial gauge to support the mineral wool curtain.

Preferably it has a thickness of at least lmm.

The mineral wool is preferably suitable for production of a fire barrier and has low resin binder content, preferably not more than 2%, more preferably not more than 1%. It may also be provided with a layer of reinforcing metal netting.

The mineral wool may be provided with a fire retardant material. This is generally an endothermic material.

Preferably it has an endothermic decomposition temperature above 200°C and undergoes substantially no endothermic decomposition below 200°C. It can for instance be a hydrate or carbonate. Preferably it is a hydroxide such as magnesium hydroxide or aluminium hydroxide. In particular

the fire retardant material may be as described in our publication W097/20780.

Any particle size may be chosen but is preferably at least 5 Am, for instance from 10 to 500 ym, preferably 10 to 100 ßm. In some embodiments it may have a size of from 0.5 to 3 mm. Preferably at least 90% by weight of the particles are within these size ranges.

If used the fire retardant material may be present in an amount of at least 5 wt. %, preferably 5 to 50 wt. %, more preferably 25 to 30 wt. %, based on mineral wool.

Fire retardant material may be introduced into the mineral wool in any suitable manner, but in particular may be introduced as described in our publications W097/20779, W097/20780 and W097/20781.

The mineral wool can be made from glass, ceramic, rock, stone or slag but preferably is made from rock, stone or. slag because the high fire resistance of such wool.

The mineral wool is generally made in standard manner, by applying a mineral melt to a spinner and converting the mineral melt to fibres and collecting the fibres as a web.

The spinner can be of the cup type described in EP-A- 530,843 or of the Downey type as described in US 2,944,284 and US 3,343,933, but preferably the spinner has a rotor mounted about a substantially horizontal axis and the rotor has a solid periphery and is constructed to receive melt applied onto the periphery and to throw mineral fibres off the periphery. Most preferably it is a cascade spinner containing 2,3 or 4 such rotors.

The invention will now be illustrated with reference to the accompanying drawings.

Figure 1 shows the support plate according to the invention showing three illustrative support tongues.

Figure 2 shows a holding plate according to the invention.

Figure 3 shows the top of a mineral wool curtain impaled upon support tongues forming part of a support plate according to the invention.

In Figure 1 the support plate 1 has an L-profile having, in use, a substantially horizontal plate 2 and a substantially vertical plate 3. The substantially vertical plate is provided with support tongues 4. In the illustration support tongue 4A is in the flat position prior to bending. Support tongue 4B has been bent outwardly from the vertical plate and support tongue 4C has been bent outwardly in the opposite direction. Each support tongue is provided with marker slots 5 to enable the installer to assess how far the mineral wool curtain has impaled on the tongues. Each tongue is provided with a rounded tip to facilitate impaling.

Figure 2 shows the holding plate 6 in the form of a channel. This is provided with holding apertures 7 through which the support tongues pass in use.

Figure 3 shows the support plate 1 having holes provided in the substantially horizontal plate 2 for fixing to the surface of the supporting structure. The mineral wool curtain 8 is impaled on the support tongues 4, which in this case have been bent outwardly in the same direction.

The drawings shows the holding plate 6 in two positions. In position A it is ready to fit over the support tongues. In position B it has been placed over the support tongues and pressed against the mineral wool. We find that shaping the support plate as a channel increases its rigidity and aids in fixing the plate to the mineral wool. The support tongues may then be bent so as to lie flat along the surface of the holding plate 6.