WO2024069620A2

WO2024069620A2 - Heat insulating panel for building

Info

Publication number: WO2024069620A2
Application number: PCT/IB2024/051872
Authority: WO
Inventors: Antonio PACCIONE; Luca RUSSO; Salvatore MATARRESE; Antonio STOLFA
Original assignee: Green Tech Industry S.R.L.
Priority date: 2023-03-21
Filing date: 2024-02-27
Publication date: 2024-04-04

Abstract

A heat insulating panel for buildings and/or manufactured articles in general comprising plant fibres (10) and a binder; wherein the binder comprises hot-melt fibres (11); wherein the hot-melt fibres (11) bind the plant fibres (10) together; wherein the plant fibres (10) comprise rice straw and/or rice husk; wherein the hot-melt fibres (11) comprise a first component and a second component defining a preferably coaxial or concentric composite structure; wherein the first component is the core of the coaxial structure and the second component is an outer casing of the composite structure or a sheath wrapping the core preferably coaxially or concentrically; wherein the melting temperature of the first component is higher than the melting temperature of the second component; preferably, the first component has a mechanical sealing function, whereas the second component defines the chemical bonds with the plant fibres; preferably, the panel consists of said plant fibres (10) and of said binder, in particular the binder consists of said hot-melt fibres (11); preferably, the plant fibres consist of rice straw and/or rice husk; preferably, the hot-melt fibres consist of said first component and of said second component.

Description

"HEAT INSULATING PANEL FOR BUILDING"

Cross-Reference to Related Applications

This Patent Appl ication claims priority from Italian Patent Application No . 102023000005355 filed on March 21 , 2023 , the entire disclosure of which is incorporated herein by reference .

Technical Field

The invention relates to a thermal insulation panel for buildings and/or manufactured articles , in particular for buildings , and to an exterior insulation and finish system (EI FS ) for buildings and/or manufactured articles , in particular for buildings , comprising said panel .

In particular, the invention applies to a building, which can be a private house or an industrial building or a public building or any other type of building, where the interior of the building, in particular of the house , has to be thermally insulated from the exterior of the building or of the manufactured articles in general .

Background

Generally speaking, an exterior insulation and finish system usually comprises :

- preferably, a glue-based fixing layer for fixing the system to a wall ;

- a thermal insulation layer comprising a plurality of insulating panels ;

- preferably, a mechanical fixing layer consisting of dowels ;

- a plaster layer and, preferably, a reinforcement mesh associated with the plaster layer to increase resistance to mechanical stress and hygrometric stress ;

- preferably, a finishing layer with a function of protection against bad weather and an aesthetic purpose .

The most common types of insulating panels are made of polystyrene foam or polyurethane foam or mineral wool , for example stone wool or glass wool .

The commonly used heat insulating panels are made of stone or glass wool or of non-ecological materials such as polystyrene or polyurethane foam .

These panels of fer good insulating performances ; however, these panels suf fer from the drawback of using materials that could be health-endangering, for instance stone or glass wool , or non-ecological materials , such as polystyrene or polyurethane foam .

Furthermore , the manufacturing process of these panels , especially when dealing with stone and/or glass wool , leads to the emission of a very large quantity of carbon dioxide , for example the production of stone and/or glass wool requires temperatures above 1000 degrees Celsius .

The state of the art envisages the use of heat insulating panels made of a natural material ( of plant or animal origin) , which, however, suffer from a series of technical drawbacks , other than the ones af fecting the panels made of stone wool or polystyrene , which signi ficantly limit their use .

For example , said prior-art heat insulating panels made of natural materials do not of fer suitable values in terms of thermal conductivity and/or of thermal insulation and/or of resistance to hits and/or to scraping .

Furthermore , some prior-art heat insulating panels made of natural materials are not resistant to moulds and/or bacteria .

Furthermore , some prior-art heat insulating panels made of natural materials are not water-repellent .

Furthermore , some of the insulating panels described above do not derive from recycled materials .

Subject-Matter of the Patent

An obj ect of the invention is to provide a heat insulating panel for buildings capable of reducing at least one of the drawbacks of the prior art .

According to the invention, there is provided a heat insulating panel for buildings comprising plant fibres and a binder ; wherein the binder comprises hot-melt fibres ; wherein the hot-melt fibres bind the plant fibres together ; wherein the plant fibres comprise rice straw and/or rice husk; wherein the hot-melt fibres comprise a first component and a second component defining a preferably coaxial or concentric composite structure ; wherein the first component is the core of the coaxial structure and the second component is an outer casing of the composite structure or a sheath wrapping the core preferably coaxially or concentrically; wherein the melting temperature of the first component is higher than the melting temperature of the second component ; preferably, the first component has a mechanical sealing function, whereas the second component defines the chemical bonds with the plant fibres ; preferably, the panel consists of said plant fibres and of said binder, in particular the binder consists of said hot-melt fibres ; preferably, the plant fibres consist of rice straw and/or rice husk; preferably, the hot-melt fibres consist of said first component and of said second component .

Thanks to the invention, a heat insulating panel is obtained, which o f fers performances that can be compared to those of heat insulating panels made of stone and/or glass wool , but with a signi ficantly smaller emission of carbon dioxide during the production .

Another obj ect of the invention is to provide a thermal insulation system for a building, which reduces at least one of the drawbacks of the prior art . According to the invention, there is provided a thermal insulation system, preferably an exterior insulation and finish system, for a building comprising : a thermal insulation layer comprising a plurality of insulating panels according to any one of the claims from 1 to 11 ; a fixing layer based on adhesives and/or mechanical elements , preferably dowels , for fixing the thermal insulation layer to a building wal l , in particular along an external fagade of a wall of a building; a plaster layer and, preferably, a reinforcement mesh associated with the plaster layer to increase resistance to mechanical stress and hygrometric stress , wherein the plaster layer is fixed on top of the thermal insulation layer, in particular on the side opposite the side where the thermal insulation layer is fixed to the wall ; preferably, a finishing layer with a function of protection against bad weather and an aesthetic purpose .

Another obj ect of the invention is to provide a method for producing a heat insulating panel for buildings , which reduces at least one of the drawbacks of the prior art .

According to the invention, there is provided a method for producing a heat insulating panel for buildings according to any one of the claims from 1 to 11 , the heat insulating panel comprising plant fibres and hot-melt fibres , wherein the plant fibres comprise rice straw and/or rice husk; the method comprising the steps of : - preferably grinding, using a granulator, and/or flaking, using a flaker, the plant fibres ;

- mixing the plant fibres and the hot-melt fibres together ;

- placing the blended plant fibres and hot-melt fibres in a receiver in a pneumatic manner so as to form a layer of blended fibres with a defined thickness , pre ferably by distributing them evenly along the plane , preferably the receiver is a plane of a conveyor belt where the layer of blended fibres is advanced along said conveyor belt ;

- applying a heat treatment for a defined amount of time so that the hot-melt fibres bind themselves to the plant fibres , in particular at a temperature close to the melting temperature of a first component o f the hot-melt fibres , in particular heating the plant fibres and the hot-melt fibres mixed in the receiver .

Brief Description of the Drawings

Further features and advantages of the invention will be best understood upon perusal of the description of the following non-limiting embodiments , with reference to the accompanying drawings , wherein : figure 1 is a schematic partial view of a thermal insulation system according to the invention; and figure 2 is a perspective view of a heat insulating panel of the thermal insulation system of figure 1 . Description of the Embodiments

With reference to figure 1 , number 1 indicates a thermal insulation system, preferably an exterior insulation and finish system, for a building comprising : a thermal insulation layer 2 comprising a plurality of heat insulating panels 3 ; a fixing layer 4 based on adhesives and/or mechanical elements , preferably dowels , for fixing the thermal insulation layer 2 to a building wall 5 , in particular along an external fagade of a wall 5 of a building; a plaster layer 6 and, preferably, a reinforcement mesh 7 associated with the plaster layer 6 to increase resistance to mechanical stress and hygrometric stress .

The plaster layer 6 is fixed on top of the thermal insulation layer 2 , in particular on the opposite side of the thermal insulation layer 2 relative to the side where the thermal insulation layer 2 adheres to the external fagade of the wall 5 .

In a preferred, though non-limiting embodiment of the invention, the thermal insulation system 1 comprises a finishing layer 8 with a function of protection against bad weather and an aesthetic purpose .

In a preferred, though non-limiting embodiment of the invention, the building is a house and/or a building and/or a manufactured article in general and/or a public building and/or a private building . Said heat insulating panel 3 is a heat insulating panel for buildings , in particular for a building, preferably for a house and/or buildings and/or manufactured articles in general .

Furthermore , said heat insulating panel 3 is soundabsorbing .

In an alternative embodiment , said heat insulating panel 3 is used for filling air gaps in a house and/or in a building and/or in a manufactured article in general for the purpose of thermally insulating said house and/or building and/or manufactured article .

In an alternative embodiment , said heat insulating panel 3 is used as at least part of an envelope to protect and/or insulate a product .

In other words , in an alternative embodiment, said heat insulating panel 3 is used as at least part of the packaging of a product .

With reference to figure 2 , the heat insulating panel 3 comprises plant fibres 10 and a binder .

The plant fibres 10 comprise rice straw and/or rice husk .

In particular, the binder compri ses hot-melt fibres 11 , which are aimed at binding themselves to the plant fibres and at binding the plant fibres together .

In particular, the hot-melt fibres 11 comprise a first component and a second component (not shown) , which define a coaxial or concentric composite structure .

In particular, the first component is the core of the coaxial structure and the second component is an outer casing of the composite structure or a sheath wrapping the core preferably coaxially or concentrically .

In particular, the melting temperature of the first component is higher than the melting temperature of the second component .

In particular, the first component has a mechanical sealing function, whereas the second component defines the chemical bonds with the plant fibres after it has been subj ected to a heat treatment , as explained more in detail hereinafter . In other words , the binder is heated at a temperature that is approximately the same as the melting temperature of the second component , so that the second component , by melting, binds itsel f to the plant fibres , while the first component does not melt and ensures the mechanical sealing ability of the binder .

In an alternative embodiment , the step carried out to heat the blended fibres takes place at temperature that is higher than the melting temperature of the second component and lower, in particular adequately lower, than the temperature of the first component , whereby " adequately lower" means so that the first component does not even partially melt .

In a preferred embodiment , the first component has a melting temperature ranging from 140 °C to 270 °C, in particular from 140 °C to 170 °C or from 245 °C to 265 °C, in particular equal to 160 °C + /- 15 °C or 255 °C + /- 10 °C.

In a preferred embodiment, the second component has a melting temperature ranging from 110 °C to 150 °C, in particular from 120 °C to 140 °C, in particular equal to 130 °C +/- 5 °C.

In this document, the term "consisting of" means exclusively comprising the listed elements, whereas the term "comprising" means comprising the listed element, but also capable of comprising other elements or of not comprising other elements.

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments, the heat insulating panel 3 consists of said plant fibres 10 and of said binder.

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments, the binder consists of said hot-melt fibres 11.

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the plant fibres 10 consist of rice straw and/or rice husk .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the hot-melt fibres 11 consist of said first component and of said second component .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the first component of the hot-melt fibres 11 comprises polypropylene ( commonly known as PP) or polyethylene terephthalate ( commonly known as PET ) ; in an embodiment , it consists of polypropylene and/or polyethylene terephthalate .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the second component of the hot-melt fibres 11 comprises polyethylene ( commonly known as PE ) ; in an embodiment , it consists of polyethylene .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the first component and/or the second component comprise an at least partially recycled material , in particular at least partially recycled polypropylene and/or polyethylene terephthalate and/or polyethylene .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the first component and/or the second component consist of an at least partially recycled material , in particular at least partially recycled polypropylene and/or polyethylene terephthalate and/or polyethylene .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the first component and the second component comprise polylactide or polylactic acid or as poly ( lactic acid) ( commonly known as PLA) , in particular they consist of polylactide or polylactic acid or as poly ( lactic acid) .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the percentage distribution of the plant fibres 10 relative to the hot-melt fibres 11 ranges from 70% to 90% , in particular from 82 % to 88 % , preferably from 84 % to 86% , and is preferably equal to 85% .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the plant fibres 10 are subj ected to flocking before being mixed with the hot-melt fibres 11 .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the plant fibres 10 are subj ected to grinding before being mixed with the hot-melt fibres 11 .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the hot-melt fibres 11 have a length from 2 to 13 mm, in particular equal to 3 mm or 4 mm or 6 mm or 12 mm, and a count from 1 . 2 to 1 . 8 dtex, in particular equal to 1 . 3 or 1 . 7 dtex .

In a preferred, though non-limiting embodiment of the invention, which can be combined with one or more previously discussed or not previously discussed embodiments , the plant fibres 10 are added with silanes and/or aminosilanes , preferably by means of a silani zation process , and/or with fluorocarbon resins , preferably prior to being mixed with the hot-melt fibres , so as to obtain water-repellent and/or antibacterial properties .

In particular, the plant fibres 10 are added with an organosilane with a -NH3 amine functional group, whose features positively af fect both the substrate adhesion mechanism and the hydrophobicity of the rice straw and/or rice husk .

The silani zation process comprises a first step, during which an aminosilane and hydrochloric acid are added to a water solution of ethanol , said solution is used to impregnate and/or spray the plant fibres 10 , subsequently a heat treatment is applied at a temperature > 65 ° C for condensing/drying the plant fibres 10 .

Thanks to this treatment , the plant fibres 10 have hydrophobic and/or antibacterial and/or anti fungal properties .

In a preferred, though non-limiting embodiment of the invention, a method for producing the heat insulating panel 3 comprises the following steps : a ) preferably grinding, using a granulator, and/or flaking, using a flaker, the plant fibres 10 ; b ) mixing the plant fibres 10 and the hot-melt fibres 11 together ; c ) placing the blended plant fibres and hot-melt fibres in a receiver so as to form a layer of blended fibres with a def ined thickness , preferably by distributing them evenly along the plane in at least one dimension of the plane , in particular along the width of the plane , preferably the receiver is a plane of a conveyor belt where the layer of blended fibres is advanced along said conveyor belt , preferably the plant fibres and the hot-melt fibres are transported pneumatically in the receiver ; d) applying a heat treatment for a defined amount of time so that the hot-melt fibres 11 bind themselves to the plant fibres 10 , in particular heating the blended plant fibres 11 and hot-melt fibres 11 in the receiver, in particular heating the blended fibres at a temperature that is approximately equal to the melting temperature of the second component and in particular lower than, in particular adequately lower than, the melting temperature of the second component .

In particular, in a preferred, though non-limiting embodiment of the invention, the step of heating the blended fibres takes place at a temperature ranging from 110 ° C to 160 ° C, in particular from 120 ° C to 140 ° C, in particular equal to 130 ° C + /- 5 ° C .

In a preferred, though non-limiting embodiment of the invention, step c ) of the method can comprise one or more of the following steps : cl ) causing the blended fibres to go through an opening section and feeding them to a forming chamber, wherein the combined action of a series of distributor cylinders and suction through a perforated belt located at the base of the forming chamber ensures an even distribution of the material and a perfectly hori zontal layering of the fibres in said receiver ; c2 ) weighing the fibres before placing them in the receiver, in particular weighing the flow of fibres in and out of the formation chamber to adj ust the density of the final panel .

Furthermore , in a preferred, though non-limiting embodiment of the invention, the method comprises the step of , before or during the heat treatment , applying a compaction step for the plant fibres and the hot-melt fibres so as to increase the density of the final panel .

In a preferred embodiment , the heat insulating panel 3 shown in this document is rigid and not flexible . Furthermore , said heat insulating panel 3 is sel f- supporting and has a density ranging from 70 kg/m3 to 110 kg/m3 .

In a non-limiting embodiment of the invention, the hot-melt fibres 11 incorporate a flame retardant additive and have a LOI index ranging from 30 to 38 .

Furthermore , in a preferred non-limiting embodiment of the invention, the method comprises the step of impregnating the plant fibres 10 and/or the hot-melt fibres 11 with a flame retardant while mixing the plant fibres 10 and the hot-melt fibres 11 or before mixing the plant fibres 10 and the hot-melt fibres 11 and subsequently applying said heat treatment .

The flame retardant being compostable .

Furthermore , in a preferred non-limiting embodiment of the invention, the method comprises the step of impregnating or spraying the heat insulating panel 3 with a flame retardant after the heat treatment applying step .

In an optional preferred non-limiting embodiment of the invention, the silani zation process described above is carried out by spraying the water solution of ethanol , with the addition of the aminosilane and of hydrochloric acid, on the plant fibres 10 during and/or before and/or after one or more of steps a ) , b ) , c ) (preferably including cl ) , c2 ) ) , d) .

The heat insulating panel 3 manufactured in the way described above has a thickness ranging from 5 to 15 cm depending on the needs .

In a preferred, though non-limiting embodiment of the invention, the production method described above comprises the step of spraying a fire-retardant material , preferably a fire-retardant liquid, on the plant fibres 10 and/or the hot-melt fibres 11 so as to impregnate said plant f ibres 10 and/or hot-melt fibres 11 with said water-retardant material . Said spraying step i s preferably carried out after the step b ) of mixing the plant fibres 10 and the hot-melt fibres 11 .

Thanks to the invention, a heat insulating panel is obtained, which is made of a water-retardant plant material , preferably of type C or B or more . In an embodiment , in order to increase the thicknes s of the thermal insulation layer 2 , two heat insulating panels 3 as described above are coupled to one another along one of the two sides having a larger area and are glued to one another so as to obtain a panel assembly having a greater thickness than the thickness of each heat insulating panel 3 .

In a preferred, though non-limiting embodiment of the invention, two heat insulating panels 3 are coupled by means of a spreadable hot-melt element , which is applied along the two sides next to one another of the heat insulating panels and, subsequently, is fixed through heat , in particular by heating the heat insulating panels 3 at a suitable temperature . Said hot-melt element preferably has a natural and/or compostable base .

In an embodiment , said hot-melt element is applied along the two sides next to one another of the heat insulating panels 3 forming strips and leaving empty spaces without hot-melt element between the two adj acent faces of the hot-melt panels 3 , so as to ensure the breathability of the panel assembly .

In a preferred embodiment , the two heat insulating panels 3 are coupled to one another by means of a heat- activated adhesive film, alternatively or in addition to the hot-melt element , which is subsequently fixed through heat , preferably by heating the heat insulating panels 3 at a suitable temperature . The heat-activated adhesive film preferably is perforated, so as to be breathable .

Finally, the panel , the system and the method described herein can clearly be subj ected to changes and variations , without for this reason going beyond the scope of protection set forth in the appended claims .

Claims

1. A heat insulating panel for building; wherein the panel comprising plant fibres (10) and a binder; wherein the binder comprises thermo-fusible fibres (11) ; wherein the thermo-fusible fibres (11) bind the plant fibres (10) together; wherein the plant fibres (10) comprise rice straw and/or rice husk; wherein the thermofusible fibres (11) comprise a first component and a second component defining a composite structure preferably coaxially or concentrically; wherein the first component is the core of the coaxial structure, and the second component is an outer casing of the composite structure or a sheath wrapping the core preferably coaxially or concentrically; wherein the melting temperature of the first component is higher than the melting temperature of the second component; preferably the first component has a mechanical sealing function while the second component defines the chemical bonds with the plant fibres; preferably the panel comprises said plant fibres (10) and said binder, in particular the binder comprises said hot melt fibres (11) ; preferably the plant fibres comprise rice straw and/or rice husk; preferably the hot melt fibres comprise said first component and said second component.

2. The panel according to claim 1, the first component of the hot melt fibres comprises PP or PET.

3. The panel according to any of the preceding claims, where the second component of the thermo-fusible fibres comprises PE.

4. The panel according to any of the preceding claims, where the first component and the second component comprises at least partially recycled material, in particular PP and/or PE and/or PET at least partially recycled .

5. The panel according to claim 4, wherein the first component and the second component comprise PLA.

6. The panel according to any one of the previous claims, where the percentage distribution of plant fibres in relation to thermally conductive fibres ranges from 70 to 90 per cent, in particular 82 to 88 per cent, preferably 84 to 86 per cent, preferably equal to 85 per cent.

7. The panel according to any of the preceding claims, in which the thermo-fusible fibres (11) have a length of 2 to 13 mm, in particular equal to 3 mm or 4 mm or 6 mm or 12 mm, and a count of 1.2 to 1.8 dtex, in particular equal to 1.3 or 1.7 dtex.

8. The panel according to any one of the preceding claims, wherein the first component has a melting temperature between 140 °C and 270 °C, in particular between 140 °C and 170 °C or between 245 °C and 265 °C, in particular between equal to 160 °C +/- 15 °C or 255 °C + /- 10 °C; preferably the second component has a melting temperature between 110 °C and 150 °C, in particular between 120 ° C and 140 ° C, in particular equal to 130 ° C +/- 5 ° C .

9. The panel according to any of the above claims , being rigid and not flexible and having a density between 70 kg/m3 and 110 kg/m3 .

10 . The panel according to any one of the preceding claims , wherein the plant fibres ( 10 ) are added with silanes and/or aminosilanes and/or fluorocarbon resins preferably prior to bonding to the hot melt fibres ( 11 ) to obtain water repellent and/or antibacterial properties .

11 . The panel according to any of the above claims , being sound-absorbent .

12 . A thermal insulation system, preferably a thermal insulation layer, for a building comprising : a thermal insulation layer comprising a plurality of insulation panels according to any one of the preceding claims ; a fixing layer based on adhesives and/or mechanical elements , preferably dowels , for fixing the thermal insulation layer to a building wall , in particular along an external fagade of a wall of a building and/or a manufactured article ; a plaster layer and preferably a reinforcement mesh associated with the plaster layer to increase resistance to mechanical stress and hygrometric stress , whereby the plaster layer is fixed above the thermal insulation layer, in particular on the side opposite to the side where the thermal insulation layer is fixed to the wall ; preferably a finishing layer with a function of protection against weathering and an aesthetic purpose.

13. A method for producing a heat insulating panel for buildings and/or articles according to any one of claims 1 to 11, wherein the heat insulating panel comprises plant fibres and heat fibres, wherein the plant fibres comprise rice straw and/or rice husk; the method comprising the steps of:

- preferably grind, using a granulator, and/or flake, using a flaker, the plant fibres; mix together the vegetable fibres (10) and hot-melt fibres (11) ;

- Place the blended plant fibres (10) and hot melt fibres (11) in a receiver to form a layer of blended fibres with a defined thickness, preferably by distributing them evenly along the plane, preferably the receiver is a plane of a conveyor belt where the layer of blended fibres is advanced along that conveyor belt;

- apply heat treatment for a defined time so that the hot melt fibres (11) bind to the plant fibres (10) , in particular at a temperature close to the melting temperature of the first component of the hot melt fibres (11) , in particular by heating the plant fibres (10) and hot melt fibres (11) mixed preferably at a temperature between 110 °C and 160 °C.

14. The method of claim 13, further comprising the step of passing the mixed fibres through an opening section and feeding them to a forming chamber, wherein the combined action of a series of distributor cylinders and suction through a perforated belt positioned at the base of the forming chamber ensures uniform distribution of the material and horizontal fibre layering in said receiver.

15. The method of claim 13 or 14, comprising the step of weighing the plant fibres (10) and/or the thermo-fusible fibres (11) and/or the fibres mixed together before placing them in the receiver, in particular weighing the flow of fibres in and out of the formation chamber to adjust the density of the thermo-insulating panel (3) .

16. The method according to any one of claims 13 to

15, before or during the heat treatment step apply a compaction step of plant fibres (10) and thermo-fusible fibres (11) to increase the density of the thermal insulation board (3) .

17. The method according to any one of claims 13 to

16, comprising the step of impregnating the plant fibres (10) and/or the hot melt fibres (11) with a flame retardant while mixing the fibres or before mixing the fibres and subsequently applying said heat treatment.