[0001 ] This invention relates to a composite fibre panel, in particular an acoustic panel, for example for use in door constructions, floor insulation or sandwich panels.

[0002] One known form of panel used in doors comprises a mixture of coconut fibres, polyurethane (PU) foam, particulate rubber and glue. The heterogeneous nature of these panels contributes to their good sound absorbing properties and the availability of their constituent parts allows their manufacture at moderate cost.

[0003] WO2013/1 13912, herein incorporated by reference, discloses a composite fibre panel having a core comprising mineral fibres and polymeric material in particulate form selected from elastomers, rubbers, natural rubbers and synthetic rubbers. This has been shown to have useful acoustic properties, for example as a sound deadening panel in doors or sandwich panels.

[0004] One aim of the present invention is to provide improved panels having an advantageous combination of thermal insulation and acoustic performance.

[0005] According to one aspect, the present invention provides a composite fibre panel as defined in claim 1 ; other aspects are defined in other independent claims. The dependent claims define preferred and/or alternative embodiments.

[0006] The composite fibre panels provide an advantageous combination of thermal insulation, fire performance, acoustic properties and mechanical properties. For example, the composite fibre panels may be used to provide improved fire performance compared with the panels disclosed in WO2013/1 13912 whilst providing at least comparable thermal and acoustic properties. This provides a significant advantage for, for example, fire doors, sandwich panels and building applications. Whilst not wishing to be bound by theory, it is believed that the combination of the different materials in the composite fibre panels provides a synergistic effect which contributes to the combination of properties of the panel.

[0007] The composite fibre panel may consist or consist essentially of the combination of the first, second, third and fourth materials and the binder. The combination of the first, second, third and fourth materials and the binder may together make up > 75 wt%, > 80 wt%, > 85 wt% or > 90 wt% and/or < 100 wt% or < 95 wt% of the composite fibre panel. As used herein, reference to the combination of the first, second, third and fourth materials include the fourth material where this is present and does not include the fourth material when this is not present. [0008] As used herein, the term "consists essentially of" is intended to limit the scope of a claim or feature to the specified materials, features or steps and those that do not materially affect the basic and novel characteristic(s) of the claimed invention.

[0009] The first mineral material may comprise mineral fibres, particularly mineral wool fibres. The mineral fibres may be stone wool fibres; they may be glass wool fibres. Stone wool fibres are particularly preferred. In the quantities specified, the first mineral material contributes to providing advantageous fire resistance and/or compressive strength and/or low thermal conductivity and/or acoustic properties. Whilst not wishing to be bound by theory, it is believed that the provision of the fibres of the first mineral material provide good attenuation of the intensity of high frequency sound.

[0010] Where the first mineral material comprises stone wool fibres, the stone wool fibres may comprise: between 30 and 55 wt% Si0 ₂ and/or between 10 and 30 w-% AI203; and/or an alkali/alkaline-earth ratio of their composition which is < 1 ; and/or a combined quantity of CaO and MgO ranging from 20 to 35 wt%; and/or a combined quantity of Na ₂ 0 and K20 < 8 wt%; and/or a total iron content expressed as Fe ₂ C>3 of between 4 and 15 wt%. The stone wool fibres may have a softening point in the range 900-1200°C, notably in the range 1000-1 100°C. The stone wool fibres may have an average diameter in the range 2-1 Opm and/or an average length in the range 2-30mm.

[001 1 ] Where the first mineral material comprises glass mineral wool fibres, the glass fibres may comprise: > 55 wt% silicon oxide (Si0 ₂ ); and/or < 10 wt% aluminium oxide (AhCh); and/or an alkali/alkaline-earth ratio of their composition which is > 1 ; and/or a combined quantity of CaO and MgO < 20 wt%; and/or a combined quantity of Na ₂ 0 and K ₂ 0 > 8%wt. The glass wool fibres may have a softening point in the range 600-750°C, notably in the range 650-700°C.

[0012] The first mineral material may, in addition to comprising mineral material in the form of fibres, further comprise the first mineral material in the form of shots (also called beads), i.e. particles which are not in the form of fibres, for example particles having a largest apparent diameter of less than 60 pm. This is particularly the case where the first mineral material comprises stone wool fibres as manufacturing methods for stone wool fibres generally result in the presence of shots combined with and entangled with the stone wool fibres. Particularly where the first mineral material comprises stone wool fibres, the quantity of the first material present in the form of fibres may be > 70 wt%, > 75 wt%, > 80 wt%, > 90 wt% and/or < 95 wt%, with respect of the total weight of the first mineral material; this facilitates manufacture of the stone wool fibres without significantly prejudicing the combination of properties of the composite fibre panel. [0013] Preferably, the entire content of the first mineral material has the same composition; this facilitates manufacturing. Alternatively, the first mineral material may comprise a combination of mineral fibres having different compositions. As used herein, the term,“the same chemical composition” in relation to mineral fibres means substantially the same chemical composition, allowance being made for ordinary industrial manufacturing variations and tolerance and, notably, mineral fibres have the same composition when the variation in their chemical composition is within the range:

±2.5% points for each oxide present in a quantity that is > 15 wt%; and

±1 .5% points for each oxide present in a quantity that is > 2 wt% and < 15 wt%; and

±1 .0% point for each oxide present in a quantity that is < 2 wt%;

with the proviso that (CaO + MgO) and (Na ₂ 0 + K ₂ 0) are each treated as one oxide component.

For example, for Si0 ₂ present in a quantity of 63 wt%, the tolerance expressed above is 63% ±2.5% points i.e. 60.5% to 65.5%.

The term “different chemical composition” as used herein means that the chemical compositions are not the same and notably that the two compositions fall outside the above tolerances.

For individual fibres which have a homogeneous composition throughout their volume the composition can be measured from a single portion of the fibre. Alternatively, the fibre may be melted to provide a mass having a homogeneous composition for analysis.

[0014] The first mineral material may be present in a quantity which is > 30 wt% weight and < 60 wt%, preferably > 35%wt or > 40%wt and/or < 55%wt, < 50%wt with respect to the total combined weight of the first, second, third and fourth materials and the binder.

[0015] Notably when the first mineral material comprises a combination of mineral fibres having different compositions, the first mineral material may comprise a combination of:

- mineral wool fibres, particularly glass wool fibres and/or stone wool fibres; and

- mineral reinforcing fibres.

The mineral reinforcing fibres contribute to mechanical properties of the panel, for example flexibility, resilience and/or an ability to support deformation without breaking. The mineral reinforcing fibres may make up > 2 wt%, > 5 wt% or > 10 wt% and/or < 20 wt% or < 15 wt% with respect to the total combined weight of the first, second, third and fourth materials and the binder. The amount of mineral reinforcing fibres may be > 2 wt%, > 5 wt% or > 10 wt% and/or < 20 wt% or < 15 wt% with respect to the total combined weight of first mineral material. The mineral reinforcing fibres may comprise, consist or consist essentially of basalt fibres and/or continuous glass fibres. [0016] The second mineral material may comprise, consist or consist essentially of plasterboard, gypsum, calcium sulphate dihydrate, stones comprising water, clay, vermiculite and combinations thereof. The second mineral material may be present in the panel in a quantity which is > 15 wt%, > 20 wt%, > 25 wt% and/or < 35 wt%, < 30 wt% and

< 40 wt% with respect to the total combined weight of the first, second, third and fourth materials and the binder. Preferably, the quantity of the second mineral material present in the form of particles is > 75 wt%, > 80 wt%, > 85 wt% or > 90 wt% and/or < 100 wt% or < 98 wt% with respect of the total weight of the second mineral material. Whilst not wishing to be bound by theory, it is believed that the provision of the second mineral material in particulate form provides good attenuation of mid-frequency sound and fire performance. The mineral particles may have a particle distribution such that at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt% or at least 90 wt% of the particles have a particle size which is of > 0.1 mm, > 0.2mm or > 0.5mm and/or < 8mm, < 5mm, < 3mm or < 2mm, preferably within the range 0.5 to 3 mm. As used herein, the term particle size means particle size determined by sieving.

[0017] In a preferred embodiment, the second mineral material comprises, consists or consists essentially of plasterboard particles, notably obtained by recycling plasterboard, particularly scrap plasterboard panels. For example, pieces of plasterboard panel may be ground to provide particles having a range of particle sizes and such particles may be sieved to separate particles having a desired particle size for the composite fibre panel. It has been found that plasterboard particles having a particles size in the range 0.5 mm to 3 mm are particularly advantageous as i) such a particle size facilitates mixing with the other materials of the composite fibre panel and ii) where plasterboard particles of this size are obtained by grinding and sieving pieces of plasterboard, this process substantially eliminates the presence of any paper or facings of the pieces of plasterboard and thus avoids their inclusion in the composite fibre panels.

[0018] The third polymeric material in the form of a foam may comprise polyurethane foam, expanded polystyrene foam (EPS), extruded polystyrene foam (XPS) or mixtures thereof. Preferably, the foam consists essentially of or consists of polyurethane. Whilst not wishing to be bound by theory, it is believed that the presence of foam within the panel of the composite fibre panel provides attenuation of low frequency sounds. The third polymeric material in the form of foam may be present in the panel in an amount of > 2 %wt, > 5% wt and preferably in an amount of < 15%wt with respect to the total combined weight of the first, second, third and fourth materials and the binder. The foam may have a closed cell structure or an open cell structure or a combination thereof. The foam may have a density

< 60 kg/m ³ , < 50 kg/m ³ , or notably < 40 kg/m ³ ; it may have a density > 5 kg/m ³ , > 10 kg/m ³ or notably > 20 kg/m ³ . Foams having such densities may be referred to as“light foams”. The foam may comprise a hard foam, for example a foam having a density > 60 kg/m ³ , > 80 kg/m ³ or notably > 100 kg/m ³ and/or < 160 kg/m ³ , or notably < 150 kg/m ³ . Such densities may contribute to the compressive strength and/or fire performance and thus facilitate use in doors, floor applications and/or sandwich panels for structural applications. The foam may have a particle distribution such that at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt% or at least 90 wt% of the foam has a particle size which is of > 0.1 mm, > 0.3 mm or > 0.5 mm and/or < 20 mm, < 15 mm, < 10 mm or < 5 mm, preferably within the range 0.5 to 5 mm. Preferably, the foam is present in the form of discrete pieces of foam interspersed with the other components; such a form is not comparable with, for example, a panel which consists of a continuous foam material comprising reinforcing fibres.

[0019] In a preferred embodiment, the composite fibre panel is free or substantially free of particulate polymeric material, notably free of particulate polymeric material selected from rubber(s), natural rubber(s), synthetic rubber(s), elastomer(s) or mixtures thereof. Such particulate polymeric materials add to the weight of the panel and add to the potentially combustible components. Nevertheless, the composite fibre panel may comprise a polymeric material in particulate form, for example particulate polymeric material selected from rubber(s), natural rubber(s), synthetic rubber(s), elastomer(s) or mixtures thereof, notably in an amount of < 5%wt or < 2%wt or < 1 %wt, with respect of the total combined weight of the first, second, third and fourth materials and the binder. Such materials may be present as impurities, for example from recycled materials.

[0020] The binder may comprise, consist or consist essentially of an organic binder, for example a a polyurethane or a reducing sugar based binder. As used herein the term reducing sugar based binder means a binder obtained by curing a binder composition in which at least 50 wt% of the reactants, preferably at least 60 wt%, comprise reducing sugar(s) and/or reaction products of reducing sugar(s). The reducing sugar based binder may be a binder obtained by curing a binder composition in which at least 50 wt%, preferably at least 60 wt%, of the reactants comprise reducing sugar(s) and/or reaction products of reducing sugar(s), preferably in combination with a source of nitrogen to form a Maillard reaction product, notably in combination with preferably at least 10 wt% of i) amine(s) and/or ii) amine salt(s), for example amine salts of inorganic acids or carboxylic acid(s). The binder may be present in the panel in a quantity which is > 2 wt% and < 12 wt% with respect to the total combined weight of the first, second, third and fourth materials and the binder.

[0021 ] The composite fibre panel may further comprise a fourth polymeric material in the form of fibres, notably reinforcing fibres. The reinforcing fibres may make a significant contribution to mechanical properties of the panel, for example flexibility, resilience and/or an ability to support deformation without breaking. This is particularly the case where relatively long fibres are used, notably fibres having a length which is > 5 mm and/or < 50 mm , or notably < 10 mm. The fibres of the fourth polymeric material may have a mean average diameter which is of > 1 pm, > 2 pm or > 5 pm and/or < 200 pm, < 100 pm, < 50 pm or < 20 pm, preferably within the range 5 to 20 pm The fourth polymeric material in the form of fibres may be present in the panel in a quantity which is > 2 wt%, > 5 wt% or > 10 wt% and/or < 20 wt% or < 15 wt% with respect to the total combined weight of the first, second, third and fourth materials and the binder. In a preferred embodiment, the fourth polymeric material comprises, consists or consists essentially of melamine fibres; such melamine fibres provide suitable mechanical properties without being significantly prejudicial to fire resistance properties. Alternatively, the fourth polymeric material may comprise, consist or consist essentially of polyester, nylon, acrylic or aramid fibres; such fibres are readily available. Preferably, the fibres comprise recycled or scrap fibres.

[0022] In a preferred embodiment, the composite fibre panel comprises, consists or consists essentially of

i) stones wool fibres;

ii) plasterboard particles;

iii) polyurethane foam;

iv) optionally, polymeric reinforcing fibres, notably comprising a material selected from melamine or polyester ; and

v) an organic binder, notably selected from a polyurethane binder or a reducing sugar based binder, ;

notably in which the stone wool fibres are present in a quantity which is > 30 wt% weight and < 60 wt% with respect to the total combined weight of the stones wool fibres, the plasterboard particles, the polyurethane foam and the optional polymeric reinforcing fibres and the organic binder

[0023] The composite fibre panel may have a reaction to fire classification of at least C, B, A2 or A1 according to European Standard EN 13501 -1. The composite fibre panel may have or provide a fire resistance of at least 15 minutes, at least 30 minutes, at least 45 minutes, at least 60 minutes or at least 90 minutes, notably when provided as part of a system, for example a door or sandwich panel. The fire resistance is notably determined according to EN 1363-1 , EN 1365-1 , EN 1365-2, EN 1365-3; EN 1365-4, EN 13381 -3, EN 13381 -4, EN 13381 -5, EN 13381 -6, EN 13381 -7 (the appropriate standard being selected as a function of the system in which the composite fibre panel is provided). [0024] The provision of a composite fibre panel having a height of at least 160 cm and a width of at least 60cm allows the panel to be used without requiring additional panels to fill the cavity of a fire rated door. Handling and assembling a single panel is easier and more efficient than dealing with multiple different panels. In addition, the provision of a single or unitary panel having dimensions that can fill the entire cavity of a door avoids the risk of a point of weakness or a thermal bridge in the insulation that would occur at the abutments of separate but adjoining panels. The panel may be substantially rectangular; it may be provided with preformed cuts and/or cut-outs to facilitate its assembly in a door cavity. The panel may be provided as a single or as a multilayer arrangement, for example of two or more superposed panels.

[0025] The dimensions of the composite fibre panel may be:

Each of the length, width and thickness indicated above may be independently selected.

[0026] The composite fibre panel is particularly suited for use in doors, particularly in fire rated doors and even more particularly in doors meeting a Ei 30, Ei45 or Ei 60, fire class. The doors may be functional doors. In one embodiment, the doors comprise peripheral wooden skins or wooden external panels or cover plates which define an internal door cavity in which the composite fibre panel is arranged. Each wooden cover plate may have a thickness > 2 mm, notably > 2.5 mm or > 3 mm and/or < 8 mm notably < 5 mm or < 4.5 mm. The cover plates may be of chipboard, medium density fibre board (MDF) or high density fibre board (HDF) and may comprise a veneer. In an alternative embodiment the doors comprise peripheral sheet metal skins or sheet metal external panes, notably of steel, which define an internal door cavity in which the composite fibre panel is arranged. The doors may have a door leaf thickness > 30 mm, notably > 35 mm or > 40 mm and/or < 100 mm notably

< 75 mm or < 50 mm. The door leaf weight in kg/m ² may be > 10, notably > 15 or > 20 and/or < 100 notably < 80, < 70, < 60 or < 40.

[0027] The density of the composite fibre panels may be:

- > 300 kg/m ³ , > 400 kg/m ³ ; > 500 kg/m ³ or > 600 kg/m ³ ; and/or

- < 1000 kg/m ³ , notably < 950 kg/m ³ , < 800 kg/m ³ or < 700 kg/m ³ .

[0028] The compressive strength of the composite fibre panels may be > 200 kPa, notably > 300 kPa, > 400 kPa, > 450 kPa or > 500 kPA when determined on the basis of 10% deformation according EN 826. Such compressive strength facilitates use in doors and/or sandwich panels for structural applications; one way of providing higher compressions strengths is to manufacture the panel at a higher density.

[0029] The thermal conductivity of the composite fibre panels may be less than 150 mW/m.K, notably less than 130 mW/m.K, less than 1 10 mW/m.K, less than 100 mW/m.K, preferably less than 95 mW/m.K and/or > 35 mW/m.K when measured at 10 °C according to EN 12667. Preferably, the composite fibre panel has :

- a thermal conductivity of > 35 mW/m.K and less than 150 mW/m.K when measured at 10 °C according to EN12667; notably in combination with

- a reaction to fire classification of at least B according to European Standard EN 13501 -1 .

[0030] Preferably, the composite fibre panel has:

a thickness > 10 mm; and

a density > 300 kg/m ³ ; and

a density < 1 100 kg/m ³ ; and

a compression strength > 300 kPa; and

a thermal conductivity > 35 mW/m.K and < 1 15 mW/m.K, when measured at 10°C in accordance with EN12667.

[0031 ] The composite fibre panels may also comprise one or more additives for example: fire resistant additives, for example fire resistant additives incorporated in the panel and/or at one or more surfaces of the panel, small stones (dolomites, quartz sand), paper. Such additives may be derived from recycled materials and/or provided in particulate form, notably having a particle size > 0.1 mm or > 0.2mm or > 0.5mm or > 1 mm or > 2mm and/or

< 10mm or < 5mm. Preferably such additive(s) do not make up more than 5 wt% of the panel. [0032] According to a further aspect, the invention provides a door, sandwich panel, building panel, building construction, floor, technical insulation, marine insulation, domestic appliance (for example dishwasher, washing machine), industrial appliance (for example thermal heating pump) or sound separation panel incorporating the composite fibre panel. The composite fibre panels are particularly appropriate for such use.

[0033] Such doors, structures or panels may have:

- a sound insulation category of at least SSK3, preferably SSK2, more preferably SSK1 ; and/or

- a sound insulation of at least 34, at least 38dB, at least 39dB, at least 41 dB or at least 42dB, measured according to SIST EN ISO 717-1 ;

- a sound isolation on the facility RW,R (DIN 4109) of at least 35-39 dB, preferably 30-34 dB, more preferably 25-29 dB; and/or

- a laboratory sound isolation RW (EN ISO i40-3) of at least minimum 42 dB, preferably minimum 37 dB, more preferably minimum 32 dB;

particularly for a structure:

wooden facing 2-6 mm thick (notably about 3-4.5mm thick) /composite fibre panel 15-60 mm thick (notably about 25-50 mm thick, particularly 30-45 mm thick)/ wooden facing 2-6 mm thick (notably about 3-4.5mm thick).

[0034] In accordance with a further aspect, the present invention provides a method of manufacturing a composite fibre panel comprising:

i) combining :

a first mineral material, wherein the first material comprises mineral fibres;

a second mineral material, wherein the second mineral material comprises mineral particles;

a third polymeric material in the form of a foam, preferably polyurethane foam;

optionally a fourth polymeric material in the form of fibres, preferably melamine fibres; and a binder, notably an organic binder, more notably a polyurethane;

ii) forming the combined material in to the composite fibre panel.

Preferably, the first mineral material is present in a quantity which is > 30 wt% weight and < 60 wt% with respect to the total combined weight of the first, second, third and fourth materials and the binder.

Forming the combined material in to the composite fibre panel may comprise:

- introducing the combined materials into a mould; and/or

- compressing the combined materials, notably in a mould; and/or

- curing the combined materials, particularly curing in the mould, for example by application of heat, notably by application of steam. The method may further comprise preparing the second mineral material. Particularly where the second mineral material comprises plasterboard particles, preparing the second mineral material may comprise grinding pieces of plasterboard, notably scrap or recycled plasterboard, and/or sieving ground pieces of plasterboard.

[0035] Embodiments of the invention will now be described, by way of example only.

[0036] Example composite fibre boards having a thickness of about 13mm have one of the following compositions:

[0037] Each board may be produced by sequentially i) thoroughly mixing the materials together; ii) introducing the mixture into a mould and allowing the binder to cure by applying steam for a duration of about 2 minutes; iii) removing the moulded panel from the mould; iv) cutting the moulded panel to size and size and grinding one or both major surfaces to provide the finished composite fibre panel. Due to the thorough mixing, the mineral fibres, mineral particles, polymeric materials and binder are present and substantially homogeneous throughout the entire thickness of the panel.

[0038] One of the test specimens of the composite fibre panel having a width of about 99 cm and a length of about 213 cm was installed in a frame and junctions between the frame and the test panel were sealed.

[0039] The test panel had the following acoustic properties in accordance to EN ISO 10140- 2:2010: