This invention relates to a laminated panel for use in the construction, off-shore or shipping industries, for instance to form the walls, ceilings and/or floors of a room or cabin. The desirable attributes of such a panel have been described in our pending British Patent Application No: 8400448 (Serial No: 2,152,431), which describes a panel comprising the following layers:-

(a) a layer comprising a framework of material made from a fibre-reinforced inorganic binder surrounding a batt of mineral fibres;

(b) a facing fixed onto one face of the frame¬ work/mineral fibre layer;

(c) a self-supporting sheet of metal; (d) a board made from a reinforced inorganic binder having one face fixed onto one face of the sheet of metal, the other face of the sheet or the board being fixed onto the other face of the framework/mineral fibre layer; and (e) a cover layer fixed onto the other face of the board or sheet respectively remote from the mineral fibre layer.

Laminates made' in accordance with our earlier Specification are effective, and for example a panel having a weight of 29 kg per square metre shows a weighted Sound Reduction Index of 41dB over the frequency range 100 to 3,150 Hz.

There is, however, continued effort to improve the acoustic insulation of such panels, and it is the object of the present invention to provide such an improved panel.

According to the present invention there is provided a laminated panel for use in the construction, off-shore or shipping industries, having a layer comprising a frame- work of material made from a fibre-reinforced inorganic binder surrounding a mass of mineral fibres, and a laminate comprising a board made from a reinforced inorganic binder

. ₂ . . a _dh ered to a sheet of metal overlying said mass of mineral fibres such that the sheet of metal faces but is spaced from the mineral fibre mass.

The spacing of the sheet of metal from the mineral fibre mass suitably comprises an air gap, and preferably the air gap has a depth in the range l-15mm.

The side of the panel remote from the air gap is suitably covered with a sheet metal/reinforced inorganic binder board laminate, and the outer faces of the lamin- ated panel are suitably covered with a facing material. In a particularly preferred embodiment of- the invention a metal sheet, e.g. a steel sheet, is situated amongst the mass of mineral fibres. The metal sheet may be plain or perforated, and suitably has a thickness in the range 0.2 - 1.0, most preferably 0.4 - 0.8, mm. It is suitably situated in the middle of the mass of mineral fibres, and preferably adhered thereto, for example using a contact adhesive.

The material used to form the framework may be reinforced by glass and/or cellulose fibres, and the binder may be cement and/or calcium silicate. A suitable material for this purpose is sold under the trade name Cape Marine Board. The framework may be made as a unitary construction, or may be formed by joining together, for instance by adhesive, suitable lengths of the material. Any desired joint shape, such as butt joints or mortise and tenon joints, may be used. The joint may, if desired, be reinforced. Preferably the width of each part of the framework is approximately equal to its thickness.

The mineral fibres may be asbestos fibres, although their use is undesirable because of environ¬ mental considerations. It is therefore preferred that mineral wool fibres be used. These types of fibres are well known in the art and are less hazardous to use than asbestos fibres. Moreover, it has been found that the use of mineral fibres gives a panel having better

- 3 - acoustic properties than a similar panel using asbestos fibres. Suitably, therefore, the mineral fibres are glass wool, slag wool or rock wool fibres. A particu¬ larly suitable fibre is available under the trade name Rocksil.

Preferably the mineral fibres are at least par¬ tially immobilised in the layer, for instance by use of an adhesive. This will assist in ensuring that the correct fibre orientation is retained, whereby good acoustic properties are achieved and maintained.

The laminated panel of the invention, ^" comprises, in addition to the mineral fibre mass layer, a laminate formed from a board made from a reinforced inorganic binder and a sheet of metal adhered thereto. The board may be reinforced with a particulate material, such as vermiculite, but in order to achieve good pro¬ perties in the panel, especially screw-holding, it is necessary to use a relatively thick board, so that a lightweight reinforcement is preferred. Thus, it is preferred that the board be reinforced by a fibrous material, such as wollastonite, glass and/or cellulose fibres. It has been found that a panel using a parti¬ culate reinforced board will need to be 20 to 30% heavier than a panel having similar properties but using a fibre-reinforced board.

The binder for the board may be cement and/or calcium silicate. A particularly suitable board for use in the invention is that sold under the trade name Cape Marine Board. The metal sheet may or may not be self-supporting. Thus, it may. be a very thin sheet of metal such as a metal foil, which is adhered to the reinforced board. Preferably, however, it is a self-supporting sheet, which will not only provide structural strength to the panel, but will also add to the acoustic and thermal insulation and fire resistance of the panel. Preferably the metal is galvanised or stainless steel.

/GB87/00304

- 4 -

The outer faces of the laminated panel of the in¬ vention are preferably provided with a facing or- covering material. Such may comprise a layer of sheet metal, e.g. a sheet of metal foil, or a layer of a hard plastics material or of a plastics laminate. Preferably a plastics laminate is used as the facing material, as this can be readily coloured and/or patterned to give a pleasing appearance to the panel.

The laminated panel may further comprise surface layers on one or both of its sides to provide a decora¬ tive effect or further sound or heat insulation or fire resistance.

The layers of the laminated panel may be fixed together in any conventional way. However, it is preferred that the layers are fixed together by means of an adhesive. As the panel is intended tobe fire resistant, it will be desirable to use a fire resistant adhesive. Such adhesives are well known in the art and a skilled person will have no difficulty in select- ing a suitable one in accordance with the types of material to be adhered together. One such adhesive which can be used to advantage in the p_anel of the present invention is available under the trade name Sadofoss Adhesive Foss-THA 2K767. Preferably, the edges of the panel are treated with a resin, such as a silicone resin, to prevent or at least hinder moisture uptake.

It is envisaged that a panel according to the present invention will be useful not only in construct¬ ing rooms or cabins on offshore platforms or on board ship, but also in constructing walls, dividing walls, ceilings and/or floors in temporary, permanent or portable structures. For Instance the panels may be used in conventionally constructed building to sub-

- 5 - divide larger rooms, to construct temporary accommoda¬ tion on site, or to fabricate portable buildings in a factory for transport to a site.

In use, the panels may be located by use of channel section framework members and held in place by nails, screws or both. Alternatively, the panels may be held in fixed relation by clamping them between suitably shaped members placed on opposite sides of adjacent panels at their edges. In a third alternative method, the panels may be located by use of incombustible splines fitted into grooves machined into the ^' edges of the panel. The framework members, clamping members or splines may be made from fibre reinforced inorganic materials so that the panels are not distorted by differential thermal expansion.

The panels may be provided with conduits, for instance for electrical cables or pipes. The panel of the present invention has an improved combination of thermal and acoustic insulating, fire resistant and screw-holding properties, may be light in weight and may be made from environmentally acceptable materials. An embodiment of the invention will now be des¬ cribed with reference to the accompanying drawing, which is a cross-sectional view of a laminated panel. Referring to the drawing, the panel comprises a framework 1 made of four lengths of Ca e Marine Board

(a material made of fibre-reinforced calcium silicate) ad¬ hesively butt jointed together to form a rectangular frame. The lengths of Cape Marine Board are 40mm. in width and 30mm. in thickness. The space defined by the framework is substantially filled with a sandwich comprising a plain or perforated steel sheet 2 of a thickness in the range 0.4 to 0.8mm., adhered on each side to a mass, e.g. a batt, of mineral wool fibres 3 and 4, each of a thickness of the order of 12.5mm. An air gap 5, e.g. 4 to 5mm. deep, separates the mineral wool layer 4 from a laminate 6 comprising a steel sheet 7 stuck to a board 8 of Cape Marine Board. The periphery of the board 8 is stuck to the frame 1.

A laminate 9, similar to laminate 6 and comprising a solid steel sheet 10 stuck to a Cape Marine Board 11 is adhered to the other side of the frame 1, and on this side the steel sheet 10 is in contact with the mineral fibre batt 3. A thin facing 12 of a- hard plastics laminate completes the panel.

In the panel illustrated, the boards 8 and 11 suitably have a thickness of 8.0mm; the solid steel sheets 7 and 10 have a thickness of 0.4mm; and the facing laminates 12 have a thickness of the order of

1.2mm. The facing laminates may be of Formica (Trade Mark) decorative sheet.

The adhesive used for fixing the components of the panel together is Sadofoss Adhesive Foss-THAN 2K767. The complete panel shown in the drawing weighs only 34kg/m . It provides high sound attenuation, its weighted Sound Reduction Index (Rw) being 48dB over the frequency range 100 to 3,150Hz.

A similar panel to that shown in the drawing, but without the intermediate steel sheet 2, weighs 26kg/m ² , and has a weighted Sound Reduction Index (RW) of 44dB over the frequency range 100 to 3,150 Hz.

Both panels have excellent fire protection properties, up to the Department of Trade Standard for B.15 bulkheads. The panels will hold a No.8 screw against a direct pull of 92kg, thus showing the excellent screw-holding properties of the panels. Both panels have a thermal conductivity of approximately 11..11 WWmm~ - ² 2 DDeegg..CC ^" - ¹ 1,, tthhuuss demonstrating their good thermal insulation properties.