GB2403741A

GB2403741A - Building components clad with or incorporating intumescent material

Info

Publication number: GB2403741A
Application number: GB0414790A
Authority: GB
Inventors: Tor Hoeie
Original assignee: INTERNAT CONCEPT TECHNOLOGIES
Current assignee: INTERNAT CONCEPT TECHNOLOGIES
Priority date: 2003-07-01
Filing date: 2004-07-01
Publication date: 2005-01-12
Also published as: GB0315368D0; GB0414790D0; WO2005003479A2; WO2005003479A3

Abstract

A composite construction panel comprises a core (2) having a pair of major faces which are clad with a facing (3) and where the core incorporates an intumescent material. Preferably the core is formed by mixing polymer beads with intumescent materials prior to expansion and moulding of the core. In a second invention a composite construction panel comprises a core having a pair of major faces which are clad with a facing and intumescent material (4) is placed directly onto at least one of the facings. Preferably the intumescent material is in the form if a pad or sheet and may be covered by an outer cladding of plasterboard (5). The imtumescent material may further incorporate or be covered by a heat reflective or refractive material such as silicon dioxide or aluminium oxide or a material which will carbonise readily. A third invention claims a timber load bearing component clad directly onto one face with an intumescent sheathing.

Description

240374 1

IMPROVEMENTS TO BUILDING COMPONENTS

Field of the Invention

The present invention concerns improvements in and relating to building components and particularly, but not exclusively, composite building panels such as structurally insulated panels (SlPs).

Backaround to the Invention

There are various manufacturers around the world who make Mouldable Intumescent Pads that are intumescent, self-adhesive and classified fire protection products. One example major supplier is the UK based company Environmental Seals Ltd ( Envirografg) ).

The Intumescent pads are usually ready for use and can be hand pressed into place forming an immediate fire seal as they tend to come with a fire resistant adhesive on one side, covered by a releasable backing such as of grease proof paper that is taken off prior to application. Under the influence of fire the Intumescent material expands to a thick char layer that seal the voids and prevents the passage of fire and smoke. The pads normally start their expansion at around 125 C (257 F) and will expand many times (generally more than ten-fold) in volume. Intumescent materials used include graphite, unexpanded vermiculite, hydrobiotite and tetrasilicic fluorine mica and other plate-like or fibrous mineral materials. In an Intumescent pad the Intumescent materials are generally dispersed throughout a porous backing structure such as in EP 0476945, wherein an Intumescent paint such as Pyroplas C is applied to a backing sheet of graphite and vermiculite fibres. Other pads use, for example, a soft resilient foam such as polyurethane silicone in their construction.

Generally the pads are sufficiently flexible/ pliable to facilitate their secure application to uneven surfaces.

Intumescent pads are also used for acoustic insulation as the blend of ash and graphite of many such pads work extremely well to sound insulate.

Intumescent pads are usually placed around doorways to seal the door to the doorframe so it can't be opened, and to stop fire and smoke from getting out. In addition, they are used in electrical boxes that are recessed into walls, in ventilation grills to stop access to oxygen and to stop smoke, in ceilings where there are electrical connections or downlighting, and sometimes around window frames to ensure the windows resist the heat longer.

Intumescent foam or pads are also used in a variety of applications where ingress through a wall, floor, or ceiling, to allow services through, is required.

The current uses of intumescent materials are fairly extensive where the expansion properties of the materials serve to occlude openings and reduce ventilation for any fire. However, there is relatively little usage of such materials more generally in building components.

In the field of composite construction panels such as Structural Insulated Panels, intumescent materials are not used directly in association with the panels but rather are again associated with other components of the building such as doorways and lighting fixtures. Furthermore, where intumescent paints, pads and the like have been used heretofore they are generally located as an outermost covering to be the first layer exposed to the flames of a fire.

Structural Insulated Panels (SlPs) are panels that are used as main load bearing components of a building and comprise an expanded polymer core sandwiched between a pair of opposing facings such as a pair of Cementitious Particle Boards, Plywood Boards or Oriented Strand Boards, one or both of which is commonly, in turn, clad in plasterboard. An improved such SIP is disclosed in our earlier POT application PCT/GB01/01272, the content of which is incorporated herein in its entirety by reference.

Whereas plasterboard and the facing boards each have a limited degree of fire resistance, since SlPs, rigid timber panels and other timber building components are used as main/structurally load bearing components of buildings, it is an object of the present invention to further increase their level of fire resistance to, amongst other objectives, prevent the risk of building collapse in the event of an extreme inferno and/ or to maximise time for evacuation and for emergency services to deal with any fire.

Summary of the Invention

According to a first aspect of the present invention there is provided a composite construction panel comprising a core with a pair of major faces wherein the major faces of the core are each clad in a facing, and wherein the core incorporates intumescent material or wherein intumescent sheathing is placed directly onto at least one of said facings.

In either of these arrangements the integrity of the composite construction panel is not undermined for normal structurally load- bearing use and critically is optimised in the event of fire.

In one particularly preferred embodiment the core of the composite construction panel is a moulded foamed plastics core and the intumescent material is mixed into the core as or prior to moulding of the core. In the example of an EPS moulded core, the polystyrene beads to be expanded and moulded to form the core may be admixed with intumescent materials, suitably in a powder slurry form, prior to expansion and moulding.

Preferably plasterboard or other outer cladding is applied covering the intumescent sheathing.

Preferably the intumescent sheathing is not formed by an intumescent paint but comprises a pre-formed sheet or pad which is applied to the facing. Pre-formed sheets or pads have been found to be far more effective heat transfer barriers than intumescent paint coating of the facings. See, for example, Figures 2 and 3 hereinbelow.

Preferably the composite construction panel is a SIP having a foamed plastics core, suitably of EPS, faced with facings of cementitious particleboard, plywood, gypsum/ textile composite board or OSB.

The thickness of the sheathing/ sheets may suitably be around 2mm to 4mm thick but can vary according to fire resistance or acoustic requirements. The use of the sheathing dramatically increases the fire resistance of the composite construction panel and is especially useful in the context of Structural Insulated Panels (SlPs).

Users may still batten out and put plasterboard on the outside to meet minimum fire requirements, but the mineral wool that is commonly used between battens may be eliminated right away, or used in lesser volume or of lesser density. The sheathing also dramatically increases fire resistance for other structurally load bearing building components of timber, be they panels or posts.

Further, we can do away with the battens altogether and use less plasterboard on the outside and still generate stronger fire resistance than otherwise.

The fire resistance may be dramatically further enhanced if a heat refractive or heat reflective further (non-intumescent) material is added to or incorporated in the intumescent sheathing, suitably during manufacture of the intumescent sheathing.

Suitable such further heat reflective/ refractive materials comprise silicon dioxide, aluminium/ oxide or other oxides or crystalline materials that when combined with graphite ash eliminate or drastically reduce the rate of heat transfer through the intumescent barrier to the core of the composite panel; or may comprise biological/ proteinaceous matter such as wool or chicken feathers, which will carbonise readily.

The further heat reflective/ refractive materials may for some uses, instead of being added to or incorporated in the intumescent sheathing, be applied to the composite construction panel prior to applying the intumescent sheathing. Indeed there are advantages to having a discrete layer of heat reflective/ refractive material overlying or even underlying the intumescent sheathing.

For internal walls intumescent sheathing can be placed directly onto both sides of the insulation, with plasterboard applied directly on the exterior of the intumescent sheathing. If chases for services are moulded directly into the insulation, or made by a router or other means, intumescent sheathing can be put directly into these chases to ensure fire does not weaken the insulation and the intumescent sheathing will help overcome any loss of acoustic insulation occurring by taking foam away for the chases.

The sheathing can be used for composite cladding panels in buildings and in timber building components to increase their fire resistance to acceptable levels. Just to name one, composite insulation panels are used in food processing plants with a foam core sandwiched between mild steel sheet facings to avoid food contamination remaining behind on walls. Steel obviously transmits heat directly onto the foam so the structural integrity of those panels are immediately threatened if the foam is expanded polystyrene (EPS) - combustible, polyurethanes (PUR) combustible, standard polyisocyanurates (PIR) - combustible, or even if "approved" polyisocyanurates (PIR) - which will withstand fire for longer but which are ultimately combustible, modified phenolics - which are combustible but with a good degree of fire resistance, or other foams that fall into the same category.

By adding the intumescent sheathing, not only does this stop the fire from reaching the composite panel sooner, it also stops the transmittance of heat through the steel sheathing for much longer, which can allow the composite panel to survive until the fire is put out. This stops fire ingress throughout the structure.

Further, in caravans intumescent sheathing can be used on the interior of the caravan, creating a cheaper option for caravan panel manufacturers as higher fire resistant insulation is expensive, while using EPS is not. On the exterior of caravans or buildings made with SlPs, such as the Mantle_ Panel Building System@, an intumescent spray/ coat can be applied, either clear or as a paint coat that will increase fire resistance. With the intumescent sheathing the construction of the caravan or building external wall may in many cases have a high enough fire retardance to meet those fire regulations that restrict building within one metre of an adjacent structure.

Cold storage units, cladding applications, load bearing walls, non-load bearing walls, in fact most composite panels and other building components using foams as part of the composite will benefit from the present invention. Indeed timber structures may also benefit from the higher fire retardancies achieved.

In a further development, additionally or alternatively to providing an intumescent sheathing to the composite panels, the panels may have their foam core moulded with a composition that includes intumescent materials. In other words the EPS or other plastics for forming the core may have intumescent materials admixed therewith when forming the core or, less desirably, coated onto the outer faces of the core after moulding and prior to mounting the facings.

Brief Description of the Drawings

A composite construction panel embodying the invention, here a SIP, is illustrated by way of example in Figure 1 hereinafter. This SIP comprises a moulded core 2 of a foamed plastics material such as expanded polystyrene (EPS) formed of two mating halves 2a,2b and sandwiched between two facings of cementitious particle board 3 one on each external face of the core 2. Each particle board facing 3 is covered with a respective sheet of intumescent material 4 that is suitably adhered in place. The sheet of intumescent material 4 may suitably be provided as a sheet with adhesive pre-applied to one face and protected initially with a quick release backing layer that is removed before placing against the particle board 3. Other means of fastening the intumescent sheet material may be used but are generally not quite as reliable - examples include stapling or clipping the sheeting in place. Each intumescent sheet 4 is then clad with a respective one of a pair of plasterboards 5 to form the complete SIP with high level fire heat retardance.

Chases / conduits 6 that are formed in the core 2 to receive services such as electrical wiring suitably accomodate further intumescent material.

Referring to Figures 2 and 3 of the attached drawings, these show some trials results demonstrating the efficacy of the preferred arrangement of the present invention.

In Figures 2 and 3, three different arrangements, (1), (2) and (3), are compared for their heat transfer/ penetration when exposed to controlled fire measured at three different locations - A, B. C- in the core of the composite panel ( location C being farthest from the 50kW/m2 heat source).

For these three arrangements: Figure 2 is a graph of Temperature (degrees C) at the three core depths after 40 minutes of heat exposure; and Figure 3 is a corresponding graph of Temperature (degrees C) at the three core depths after 60 minutes of heat exposure. In the first arrangement the SIP is protected by paper impregnated with intumescent paint and with the paper being sandwiched between the 12.5mm thick external Plasterboard cladding and the outer facing of the SIP.

In the second arrangement the SIP is protected by a blanket or pad impregnated with intumescent paint and with the blanket being sandwiched between the 12.5mm thick external Plasterboard cladding and the outer facing of the SIP.

In the third arrangement the SIP is protected by a special 10 mm thick external cement bonded particle board/ mineral wool cladding and which has intumescent paint between it and the outer facing of the SIP.

Claims

Claims 1. A composite construction panel comprising a core with a pair of

major faces wherein the major faces of the core are each clad in a facing, and wherein the core incorporates intumescent material or wherein intumescent sheathing is placed directly onto at least one of said facings.
2. A composite construction panel as claimed in claim 1, wherein the core of the composite construction panel is a moulded foamed plastics core and the intumescent material is mixed into the core during or prior to moulding of the core.
3. A composite construction panel as claimed in claim 2 wherein the core is one that has been formed by admixing polymer beads with intumescent materials prior to expansion and moulding of the polymer.
4. A composite construction panel as claimed in claim 1, 2 or 3, having intumescent sheathing wherein plasterboard or other outer cladding is applied covering the intumescent sheathing.
5. A composite construction panel as claimed in claim 1, 2, 3 or 4, having intumescent sheathing wherein the intumescent sheathing is not formed by an intumescent paint but comprises a pre-formed sheet or pad which is applied to the facing.
6. A composite construction panel as claimed in any preceding claim, wherein the composite construction panel is a SIP having a foamed plastics core faced with facings of cementitious particleboard, plywood, gypsum/ textile composite board or OSB.
7. A composite construction panel as claimed in claim 5, wherein the thickness of the sheet or pad is about 2mm to about 4mm.
8. A composite construction panel as claimed in any preceding claim, wherein a heat refractive or heat reflective further (non-intumescent) material is applied to or incorporated in the intumescent sheathing.
9. A composite construction panel as claimed in claim 8, wherein the heat refractive or heat reflective further (non-intumescent) material is incorporated in the intumescent sheathing during manufacture of the intumescent sheathing.
10. A composite construction panel as claimed in claim 8 or 9, wherein the further heat reflective/ refractive material comprises silicon dioxide or aluminium/ oxide
11. A composite construction panel as claimed in claim 8 or 9, wherein the further heat reflective/ refractive material comprises biological/ proteinaceous matter, which will carbonise readily.
12. A composite construction panel as claimed in any preceding claim having an intumescent sheathing wherein a further heat reflective/ refractive material is applied to the composite construction panel prior to applying the intumescent sheathing and thereby underlies the intumescent sheathing.
13. A structurally load bearing building component of timber having a pair of major faces wherein at least one of the major faces of the component is clad with intumescent sheathing that is placed directly onto it.
14. A structurally load bearing building component of timber as claimed in claim 13, wherein the sheathing is a pad or sheet of intumescent material, not a paint.
15. A structurally load bearing building component of timber as claimed in claim 13 or 14, wherein a heat refractive or heat reflective further (nonintumescent) material is applied to or incorporated in the intumescent sheathing.
16. A structurally load bearing building component of timber as claimed in claim 13 or 14,wherein plasterboard or other outer cladding is applied covering the intumescent sheathing.
17. A composite construction panel as hereinbefore described with reference to Figure 1.