WO2001085440A1

WO2001085440A1 - A panel comprising mineral fibres and a thermosetting resin, use of the panel and method of preparing the panel

Info

Publication number: WO2001085440A1
Application number: PCT/DK2001/000300
Authority: WO
Inventors: Ole Løgtholt PEDERSEN; Stinne Damsbo Sander
Original assignee: Rockwool International AS
Current assignee: Rockwool AS
Priority date: 2000-05-09
Filing date: 2001-05-02
Publication date: 2001-11-15
Anticipated expiration: 2002-11-09
Also published as: HUP0301940A2; AU2001256146A1; HUP0301940A3; HRP20020978A2; EP1280660A1

Abstract

The invention relates to a panel comprising mineral fibres and a thermosetting resin and comprising a hydrophobic layer and a hydrophilic layer, wherein the hydrophilic layer is in contact with the hydrophobic layer, said hydrophilic layer has a density which is equal to or higher than the density of said hydrophobic layer, preferably the average density of the hydrophilic layer is higher than the density of the hydrophobic layer. The invention also relates to the use of the panel and methods of preparing such panels.

Description

A panel comprising mineral fibres and a thβrmosetting resin, use of the panel and method of preparing the panel .

The present invention relates to a panel comprising mineral fibres and a thermosetting resin which panel is constituted by a hydrophobic layer and a hydrophilic layer. The invention also relates to the use of the panel and methods for preparing such panels.

Panels comprising mineral fibres and a thermosetting resin are widely used. The panels are especially used for thermal and acoustic insulation purposes. For these uses it is normally preferred that the panels are hydrophobic, but for some specific uses and purposes it may sometimes be preferred that the panels or at least a part of the panels are hydrophilic. Such panels can be used as growth media for plants and for special insulation purposes e.g. for drainage and insulation of basement walls. Panels are normally considered to consist of four edges and two sides. Preferably, the panel has a rectangular shape.

EP 0 889 175 A2 discloses a mineral-fibre board with a hydrophobic and a hydrophilic part. The board may be manufactured either from one panel which is impregnated with a hydrophobic agent in one part and a hydrophilic agent in another part, or from one hydrophobic board and one hydrophilic board, which are glued together. The hydrophilic part of the board is made hydrophilic by impregnating it with wetting agents, water-glass or silicic-acid esthers. The board may be used for covering fagades where the hydrophilic part is in contact with the faςade wall to remove salts and other unwanted species from the wall. The board may also be used as growth media for plants.

GB 2 154 257 A discloses an insulating slab for basement walls. The slab consists of mineral fibres bonded with a hydrophobic bonding agent. The slab may also be impregnated with a hydrophobic impregnating agent. In order to make the slab hydrophilic in areas on one side, this side is subjected to a heat treatment so as to remove the hydrophobic bonding agent and the hydrophobic impregnating agent from those areas. Those treated areas then become hydrophilic and when the slabs are used for insulation of basement walls the hydrophilic areas serve as drain conduits.

DK 173106 B discloses a method of applying binding agent onto mineral wool . The document describes a method in which different kinds of binding agents or mixtures of binding agents may be applied to the mineral wool. The document also describes that the amount of binding agent may vary in the mineral wool. The method is suitable for obtaining different properties in the wool. The document discloses nothing about mineral fibre panels having a hydrophobic layer and a hydrophilic layer.

SE 464705 B discloses a method of applying binding agent or impregnating agent to a primary web of mineral wool. The document describes a method in which extra binding agent or impregnating agent is applied to one or both edges of the web which later when the web has been folded become the upper and lower side of the web. The method is suitable for improving the strength in the resulting mineral wool product. The document does not disclose anything about panels having a hydrophobic layer and a hydrophilic layer.

The known panels comprising mineral fibres and a hydrophobic part and a hydrophilic part are usually manufactured from a relatively complicated process with after-treatment of the panels, which increases the cost of the panels. Furthermore, the known panels have the disadvantage that there is a tendency of water to enter into the hydrophobic part from the hydrophilic part when this contains large amounts of water and consequently the hydrophobic part becomes more and more wet. This problem particularly occurs when the panels are used for growth media or basement wall insulation. Furthermore, use of wetting agents to make a part of the panel hydrophilic has the disadvantage that the wetting agents have a strong tendency to migrate into the hydrophobic part, and thereby convert the hydrophobic part into a hydrophilic part, this being an undesired effect.

It is therefore an object of the present invention to provide a panel comprising mineral fibres and having a hydrophobic part and a hydrophilic part with improved qualities. In particular it is an object of the invention to provide a panel having a hydrophilic and a hydrophobic part wherein the tendency of water to enter from the hydrophilic part into the hydrophobic part is significantly reduced with respect to known panels having both a hydrophilic and a hydrophobic part.

Furthermore, it is an object of the present invention to provide methods of manufacturing panels comprising mineral fibres and having a hydrophobic part and a hydrophilic part, which methods are relatively uncomplicated and cost-effective.

These above-mentioned objectives have in fact most unexpectedly been achieved by the present invention. The present invention provides a panel comprising mineral fibres and having a hydrophobic and a hydrophilic part, in which panel water can freely pass into the hydrophilic part and wherein substantially no water will pass into the hydrophobic part. Furthermore the panel is stable and has long-lasting properties due to the manufacturing method.

The methods of preparing panels according to the invention are uncomplicated and cost-effective and no after-treatment of the panels is required. The methods according to the invention result in panels with improved qualities, which are stable and have excellent features and properties for many uses.

The panel, the use of the panel and the methods of preparing panels according to the invention are defined in the claims.

The invention provides a very useful mineral fibre panel comprising a hydrophobic layer and a hydrophilic layer. Due to the relatively low production costs of the panel, the possible uses can be expanded to areas, where such type of panels has not been used so far because of the costs of such panels.

The panel is excellent for covering and insulation of building faςades and also serves very well as insulation and for drainage purposes for basement" walls. Furthermore, the panel is extremely useful as growth media for plants, especially in connection with * green roofs" .

Furthermore, the hydrophilic part of the panel according to the invention may preferably be made hydrophilic without any use of wetting agents to eliminate the risk of having the hydrophobic part of the panel destroyed by migrating wetting agents.

The mineral fibres used in the panel according to the invention may in general be any type of mineral fibres, preferably man-made vitreous fibres (MMVF) such as rock wool fibres, slag wool fibres, glass wool fibres and stone wool fibres. The panel according to the invention may also contain other additives such as fungicides and particles to improve the properties e.g. hygroscopic particles, carbon particles, etc. The panel may also contain dyestuff to modify the colour of the panel.

The methods for production of the panel make the panel relatively cheap to produce, due to the fact that the panels are produced online without requirements for after treatment. Furthermore the panel has improved properties because of the production methods according to the invention.

Normally, mineral fibre panels for use as growth media have been produced from a separate hydrophobic panel and a separate hydrophilic panel being glued together. These known panels have the disadvantage that the glue may be toxic to some plants. This disadvantage is avoided when using panels prepared by the methods according to the invention. If the hydrophobic layer is not fully impregnated with hydrophobic binding agent and optionally hydrophobic oil, this may cause a wetting of the hydrophobic layer. In such case the hydrophilic layer is able to remove the water or moisture from the hydrophobic layer due to the capillary effect of the hydrophilic layer induced by the density of the hydrophilic layer.

Furthermore, the hydrophilic layer is able to prevent soil from entering the panel e.g. when the panel is used for insulation and drainage of a basement wall. Further, it has appeared that there is no need for sand to lead water to the drain-pipe which is normally used in traditional drainage systems.

The strength of the panel is moreover increased as the density of the layers is increased.

The panel according to the invention comprises mineral fibres and a thermosetting resin and comprises a hydrophobic layer and a hydrophilic layer, wherein the hydrophilic layer is in contact with the hydrophobic layer, said hydrophilic layer has a density which is equal to or higher than the density of said hydrophobic layer. In general, the average density of the hydrophilic layer may preferably be at least 5% more, preferably at least 10% higher than the density of the hydrophobic layer.

In an embodiment of the panel according to the invention the panel comprises mineral fibres and a thermosetting resin and furthermore at least one hydrophobic layer and at least one hydrophilic layer, wherein the at least one hydrophilic layer has an average density of at least 60 kg/m³, preferably a density of 75 to 2200 kg/m³, more preferably a density of 150 to 2000 kg/m³.

These above-mentioned features have appeared to give unexpectedly good properties with regard to the interaction of the capillary effects of the hydrophobic layer and the hydrophilic layer. The features result in that the capillary forces of the hydrophilic layer prevent water from penetrating into the hydrophobic layer, and thus improve the properties of the entire panel .

The average density of the hydrophilic layer is especially useful when the hydrophilic layer is divided into sub-layers of different densities. The densities of the single hydrophilic sub-layers are then used to calculate the average density of the hydrophilic layer.

In one embodiment of the invention the hydrophobic layer has a density of 20-300 kg/m³, preferably 60-250 kg/m³, more preferably 80-200 kg/m^J. This embodiment is particularly preferred for panels for use as thermal insulation and drainage purpose for basements walls and for use as growth media.

In another embodiment of the invention the hydrophobic layer has an average density of 150-2000 kg/m³. This embodiment is particularly preferred for panels for use as covering and insulation of faςade walls.

In order to achieve the best qualities it is in general preferred that the hydrophilic layer or the sum of hydrophilic layers if more has a thickness of up to about it is preferred that the hydrophilic layer has a thickness up to about 100 mm.

In one preferred embodiment of the panel according to the invention, the hydrophilic layer has a thickness up to 10 mm which makes the panel very useful for covering and insulating of building faςades.

In a second preferred embodiment the hydrophilic layer has a thickness of 1-45 mm which makes the panel very useful for insulation and drainage purposes in respect of e.g. basement walls.

In a third preferred embodiment the hydrophilic layer has a thickness of 20-80 mm which makes the panel very useful as growth media for plants.

To meet demands for special properties in the panel according to the invention, the hydrophilic layer in a preferred embodiment comprises two or more sub-layers, and one of the hydrophilic sub-layers may preferably constitute an upper hydrophilic sub-layer defined as a layer constituting one side of the panel.

In this embodiment it is further preferred that the upper hydrophilic sub-layer has a density of 150-2000 kg/m³, and more preferably the upper hydrophilic sub-layer has a thickness up to 30 mm. The embodiment may be useful for covering and insulation of faςade walls.

In order to meet further demands for special properties of the panel according to the invention, the hydrophobic layer may preferably comprise two or more sub-layers. Preferably a first hydrophobic sub-layer has a density of from 20 to 130 kg/m³, more preferably from 50 to 110 kg/m³.

It is also preferred that a second hydrophobic sub-layer has a density of from 130 to 280 kg/m³, more preferably of from 150 to 250 kg/m³.

In a particular embodiment of the panel according to the invention it is preferred that a second hydrophobic sublayer has a density of from 150 to 2000 kg/m³ which may contribute to the strength of the panel.

In a particularly preferred embodiment the panel has a hydrophobic layer consisting of two sub-layers, wherein the first hydrophobic sub-layer has a density from 50 to 130 kg/m³ and the second hydrophobic sub-layer has a density from 150 to 250 kg/m³ and the hydrophilic layer has a density from 300 to 2000 kg/m³. Such a panel is very useful for covering and insulation of faςade walls. The panel has both good strength and insulation properties .

In a variation of the above embodiment the panel has a hydrophobic layer consisting of three sub-layers, wherein the first hydrophobic sub-layer has a density of from 50 to 130 kg/m³, the second hydrophobic sub-layer has a density of from 150 to 250 kg/m³, the third hydrophobic sub-layer has a density of from 300 to 2000 kg/m³ and the hydrophilic layer has a density of from 300 to 2000 kg/m³

To achieve the best properties with regard to strength it is preferred that the hydrophobic layer has a thickness of up to 500 mm and the hydrophilic layer has a thickness of up to 100 mm. Such panels are especially useful as growth media for plants.

The drainage capacity of the panel may be varied by e.g. varying density and/or thickness. In a number of particularly preferred e°mbodiments as described below the drainage capacity may be even further improved.

In one of these particulary preferred embodiments the panel comprises at least one internal cavity, the at least one internal cavity has a size sufficient to allow fluids, gasses or particles to flow freely in the panel. It will be clear for the skilled person that the internal cavity referred to is significantly larger than the voids which are naturally formed in the mineral fibre web during the production process, preferably the at least one internal cavity has a cross section area of at least 10 mm².

Preferably the internal cavities are substantially parallel with one edge of the panel and have a cross section area up to 50000 mm², preferably 100-2500 mm², and if more cavities present they preferably have a regular mutual spacing up to 1000 mm. The at least one internal cavity is preferably used in connection with a panel according to the invention for drainage purposes or as growth media for plants.

In another of these particularly preferred embodiment one or more grooves are formed on one or both sides of the panel . Preferably, the groove or grooves preferably have a depth of 3-150 mm and preferably a width of 3-50 mm, and they are preferably substantially parallel to one edge of the panel and if more grooves present they preferably have a regular mutual spacing of up to 1000 mm.

To improve the strength of the panel in a preferred embodiment one or both sides of the panel are covered with a non-woven and/or a woven material and/or a metal- foil.

For some specific uses it is preferred that the panel according to the invention comprises two hydrophilic layers, a first and a second hydrophilic layer, separated by a hydrophobic layer. This embodiment may e.g. be used for covering and insulation of fagade walls, where the first hydrophilic layer is facing away from the fagade wall and coated with a rendering. The second hydrophilic layer is facing the wall and serves as a buffer for moisture.

Preferably, the first hydrophilic layer has a density of at least 100 kg/m³ and the second hydrophilic layer has a density of at least 40 kg/m³, and the average density of the hydrophilic layer is at least 60 kg/m³.

Furthermore, it is preferred that the first hydrophilic layer has a thickness of up to 100 mm and the second hydrophilic layer has a thickness of up to 50 mm.

The invention also comprises use of a panel according to the invention for covering and/or insulation of fagade walls, and preferably the panel is mounted with the hydrophobic layer in contact with the fagade wall. In a preferred embodiment of the use of the panel, the hydrophilic layer is coated with a rendering, as the hydrophilic layer is a good basis for applying water- based rendering or adhesive mortar.

In another preferred embodiment of the use of the panel comprising at least two hydrophilic layers, where the hydrophilic layers constitute the sides of the panel, the first hydrophilic layer is facing away from the fagade wall being coated with rendering and a second hydrophilic layer is facing and is preferably in contact with the fagade wall. The second hydrophilic layer will serve for removing moisture and unwanted salts from the fagade wall.

The invention also comprises use of a panel according to the invention for thermal insulation and drainage of basement walls.

Preferably, the panel used has a hydrophilic and a hydrophobic layer, where the hydrophilic and hydrophobic layers constitute the sides of the panel, and the panel is mounted with the hydrophobic layer in contact with the basement wall.

The use of a panel according to the invention also comprises general use for drainage purposes.

Furthermore, the invention comprises the use of a panel according to the invention, in which the panel has a hydrophilic and a hydrophobic layer, where the hydrophilic and hydrophobic layers constitute the two sides of the panel for covering roof on buildings, and where the hydrophobic layer is in^' contact with the roof structure. The hydrophilic layer may preferably serve as a growth media for plants, and hereby making the panel very useful for green roofs".

When the panel is used to serve as "green roof" on pitched roofs it may preferably be provided with one or more cuts to prevent undesired flow of water. The one or more cuts are made through the whole hydrophilic layer and partly into the hydrophobic layer. The one or more cuts are substantially made in the direction perpendicular to the direction of the inclination of the roof. The one or more cuts may preferably be filled with waterproof material such as bitumen to improve the properties as water flow barriers. To prevent undesired water flow between neighbouring panels, the two neighbouring edges of the panel may preferably be coated with waterproof material e.g. bitumen.

More generally a panel according to the invention may be used as a growth media for plants.

When the panel is used as growth media for plants the hydrophilic layer may be pre-treated before delivery to the user, e.g. the hydrophilic layer may be pre-treated by applying a gel or mat containing seeds of the plants wanted to grow in the panel. The hydrophilic layer may also be pre-treated by sowing seeds onto the layer and covering the layer with a woven or non-woven material to prevent birds or other animals to remove the seeds. Furthermore, fertilisers, pesticides and fungicides may be added. The invention comprises a fagade wall covered with a panel according to the invention.

The invention furthermore comprises a roof covered with a panel according to the invention.

The invention also comprises methods of preparing a panel according to the invention.

A first method for preparation of panels according to the invention comprising a hydrophobic layer and a hydrophilic layer comprises the steps of providing a primary mineral fibre web comprising a hydrophobic binding agent and optionally a hydrophobic oil, impregnating the primary web with a hydrophilic binding agent in one longitudinally extending zone, leaving a longitudinally extending zone un-impregnated with hydrophilic binding agent, bringing the primary web to overlap itself by laying it out substantially transversally to the longitudinal direction of the primary web to form a secondary web comprising a hydrophobic layer and a hydrophilic layer, compressing the secondary web to obtain a tertiary web, curing or hardening the binding agents in said tertiary web and cutting the panels from the cured or hardened tertiary web.

In a preferred embodiment of the first method the secondary web is divided into a substantially hydrophobic sub-web and a substantially hydrophilic sub-web and the hydrophilic sub-web is compressed to a desired density and preferably the hydrophobic sub-web is compressed to a desired density, whereafter the compressed hydrophilic sub-web is contacted with the hydrophobic sub-web to obtain a tertiary web.

It is preferred that the hydrophilic sub-web is compressed to obtain a density as described above for the preferred embodiments of the panel, preferably a density of at least 60 kg/m³, preferably 75 to 2200 kg/m³, more preferably 150 to 2000 kg/m³.

In another preferred embodiment of the first method according to the invention, the hydrophilic layer of the secondary web is divided into sub-layers, whereafter at least one of these sub-layers is further compressed and the sub-layers are united to obtain a hydrophilic layer with sub-layers of different densities.

In a further preferred embodiment of the ^' first method according to the invention, the hydrophobic layer of the secondary web is divided into sub-layers where after at least one of these sub-layers is compressed and the sublayers are united to obtain a hydrophobic layer with sublayers of different densities.

In a preferred embodiment of the first method according to the invention, the hydrophilic binding agent is added to the longitudinally extending zone in an amount sufficient to dominate the hydrophobic binding agent and the hydrophobic oil in said zone.

In a preferred embodiment of the first method according to the invention, the secondary web is provided with a bulk surface layer on one or both sides and preferably at least a part of said bulk surface layer is hydrophilic and preferably at least a part of said bulk surface layer is hydrophobic.

A second method for preparation of panels according to the invention comprising a hydrophobic layer and a hydrophilic layer comprises the steps of providing a hydrophobic mineral fibre web constituting a hydrophobic layer, providing a bulk surface layer, distributing the bulk surface layer material onto one surface of the web to form a hydrophilic layer thereon to obtain a tertiary web constituted of the hydrophobic layer and the hydrophilic layer, curing or hardening the tertiary web while the hydrophilic layer is impregnated with a hydrophilic binding agent before or after the curing or hardening oven and cutting the panels from the cured or hardened tertiary web, said hydrophobic mineral fibre web comprising a hydrophobic binding agent and a hydrophobic oil and said bulk surface layer material having an average bulk density of at least 150 kg/m³ and comprising a substantially homogenous mixture of at least one mineral material.

More specificly the bulk surface material may be mineral fibres, milled mineral fibres, sand, quarts, Si0₂/ MgO, Ti0₂, CaO, K₂0, Na₂0, A1₂0₃ and similar material. The bulk surface material may further comprise additives such as hygroscopic particles, dyestuff, fungicides, etc.

Preferably the average grain size of the bulk surface material is less than 10 mm.

In two alternatively preferred embodiments of the second method according to the invention the hydrophilic layer is impregnated with a hydrophilic binding agent before the curing or hardening oven, and the hydrophilic binding agent is cured or hardened by the curing or hardening oven, or the hydrophilic layer is impregnated with a hydrophilic binding agent after the curing or hardening oven, and the hydrophilic binding agent is cured or hardened by the remaining heat in the tertiary web.

In a preferred embodiment of the second method according to the invention, the hydrophilic layer is compressed to obtain a density of from 300 to 2000 kg/m³, and preferably the hydrophobic layer is being compressed to obtain a density of from 50 to 250 kg/m³.

In another preferred embodiment of the second method according to the invention, the hydrophobic layer is divided to obtain a least two hydrophobic sub-layers.

In a particularly preferred embodiment of the second method according to the invention the hydrophobic layer is divided into two hydrophobic sub-layers, and the first hydrophobic sub-layer is compressed to obtain a density of from 50 to 130 kg/m³ and the second hydrophobic sublayer is compressed to obtain a density of from 150 to 250 kg/m³.

In a further preferred embodiment of the second method according to the invention, the hydrophobic layer is formed with a thickness of 10 to 100 mm and the hydrophilic layer is formed with a thickness of 0,5 to 5 mm.

In a preferred embodiment of the second method according to the invention the hydrophobic layer is provided with a bulk surface layer on one or both sides and preferably at least a part of said bulk surface layer is hydrophilic, and preferably at least a part of said bulk surface layer is hydrophobic.

A third method for preparation of panels according to the invention comprising a hydrophobic layer and a hydrophilic layer comprises the steps of providing a primary mineral fibre web, applying hydrophilic binder to one area extending in the longitudinal direction of the web and applying hydrophobic binder and optionally a hydrophobic oil to the remaining area of the web, bringing the primary web to overlap itself by laying it out substantially transversally to the longitudinal direction of the primary web to form a secondary web comprising a hydrophobic layer and a hydrophilic layer, compressing the secondary web to obtain a tertiary web, curing or hardening the binding agents in said tertiary web and cutting the panels from the cured or hardened tertiary web.

In a preferred embodiment of the third method according to the invention, the secondary web is divided into a substantially hydrophobic sub-web and a substantially hydrophilic sub-web and the hydrophilic sub-web is compressed to a desired density and preferably the hydrophobic sub-web is compressed to a desired density, whereafter the compressed hydrophilic sub-web is contacted with the hydrophobic sub-web to obtain a tertiary web. It is preferred that the density of the hydrophilic sub-web is at least 60 kg/m³, preferably 75 to 2200 kg/m³, and more preferably 150 to 2000 kg/m³.

In another preferred embodiment of the third method according to the invention, the hydrophilic layer of the secondary web is divided into sub-layers, whereafter at least one of these sub-layers is compressed and the sublayers is united to obtain a hydrophilic layer with sublayers of different densities.

In a further preferred embodiment of the third method according to the invention the hydrophobic layer of the secondary web is divided into sub-layers, whereafter at least one of these sub-layers is compressed and the sub- layers are united to obtain a hydrophobic layer with sublayers of different densities.

In a particularly preferred embodiment of the third method according to the invention, the secondary web is provided with a bulk surface layer on one or both sides and preferably at least a part of said bulk surface layer is hydrophilic, and preferably at least a part of said bulk surface layer is hydrophobic.

Although three preferred methods of producing the panel according to the invention have been described, the skilled person will of course be able to provide other methods of producing the panel, including the traditional method of connecting a separate hydrophobic panel and a separate hydrophilic panel to form a panel having a hydrophobic part and a hydrophilic part.

The invention shall now be explained in further details with reference to a drawing in which

Figure 1. Shows a panel according to the invention for thermal insulation of a flat roof with a ^λX green roof" Figure 2. Shows a panel according to the invention used for covering and thermal insulation of fagade walls .

Figure 3. Shows a panel according to the invention for use as thermal insulation and drainage aid for basement walls.

Figure 4. Shows a panel according to the invention for thermal insulation of pitched roofs, serving as a ^N green roof" as well.

The following examples are just meant to illustrate embodiments of the invention, and in such way they are not to be considered limiting the scope of the invention. The skilled person would easily be able to apply the invention to many other embodiments and uses .

Example 1

A panel according to the invention for use as ^λX green roof" was produced using the third method according to the invention. To provide the hydrophobic layer a hydrophobic phenol resin was used and to provide the hydrophilic layer a hydrophilic furan resin was used. The resins are described in detail in the published international patent application WO 99/38372.

The dimensions of the panel were: length: 2000 mm, width: 600 mm and thickness: 120 mm.

With reference to figure 1 the panel had a hydrophobic layer 1 to provide the thermal insulation of the roof and a hydrophilic layer 2 to provide a water reservoir for the green roof.

The hydrophobic layer 1 had a density of 120 kg/m³ and a thickness of 80 mm. The hydrophilic layer 2 had a density of 210 kg/m³ and a thickness of 40 mm.

The panel was installed on a flat roof. It was observed that no transport of water occurred from the hydrophilic layer 2 to the hydrophobic layer 1.

When the panel was installed on the roof it was observed that the installation time for the panel was significantly shorter than for similar products with separate thermal insulation layer and separate water buffer layer.

Example 2

A panel according to the invention was provided for covering and thermal insulation of a fagade wall. The panel was produced according to the second method of the invention. The resins were a hydrophobic phenol resin and a hydrophilic furan resin as in example 1.

As seen in fig. 2 the panel consisted of a hydrophobic layer which was divided into two hydrophobic sub-layers 1 and 2. The panel further consisted of a layer divided into two sub-layers, a hydrophobic sub-layer 3 and a hydrophilic sub-layer 4.

The dimensions of the panel were: length: 1000 mm, width: 600 mm and thickness: 205 mm. The hydrophobic sub-layer 1 had a density of 80 kg/m³ and a thickness of 180 mm. The hydrophobic sub-layer 2 had a density of 180 kg/m³ and a thickness of 20 mm. The hydrophobic sub-layer 3 had a density of 1000 kg/m³ and a thickness of 4 mm. The hydrophilic sub-layer 4 had a density of 1000 kg/m³ and a thickness of 1 mm.

The surface of the panel constituted by the hydrophilic layer 4 was covered with a glass scrim 5. The glass scrim had overlap 6 on two sides, each having a width of 50 mm. The purpose of the glass scrim was to serve as reinforcement for a render system.

The panel was mounted on a fagade wall and the joint where the panel was connected to other panels was covered by the overlap of the glass scrim. The rendering was then applied on the panel.

It was observed that the application of render on the panel was less time consuming than for the standard products for covering and thermal insulation of fagade walls. The hydrophilic surface layer 4 provides the immediate tack of the render on the surface.

The surface tension of the hydrophilic layer 4 was measured to approximately 72 mN/m compared to approximately 29 mN/m on standard insulation products for covering and thermal insulation of fagade walls. This explains the good properties of the panel with regard to application of rendering. Example 3

A panel according to the invention similar to the panel in example 2 was produced. The panel was equal to the panel in example 2 apart from a hydrophilic surface layer 7 opposite to the hydrophilic surface layer 4 in fig. 2.

The panel was installed on a fagade wall with the hydrophilic layer 7 facing the wall by means of render glue. It was observed that the gluing time of the panel to the wall was reduced because the hydrophilic surface layer 7 provided an immediate tack of the panel to the wall .

Example 4

A panel according to the invention used for thermal insulation and drainage of basement walls according to the invention was provided.

As shown in fig. 3 the panel consisted of a hydrophobic layer 1 and a hydrophilic layer 3.

The dimensions of the panel were: length: 2400 mm, width: 600 mm and thickness: 120 mm. In order to make better connections between panels, the edges of the panel in the length direction were prepared with a bevel cut 4.

The hydrophobic layer 1 had a density of 100 kg/m³ and a thickness of 100 mm. The hydrophilic layer 3 had a density of 180 kg/m³ and a thickness of 20 mm. In the interface between the hydrophobic layer 1 and the hydrophilic layer 3 cavities 2 were established. The cavities had a tubular shape and ran in the whole longitudinal direction of the panel. The cavities 2 had a diameter of 15 mm and were established with a mutual distance of 100 mm.

The panel was installed to a basement wall 5 made of concrete. The hydrophobic layer 1 was fastened to the wall 5 by use of mechanical means. On top of the panel a moisture or vapour barrier 6 was attached. As more panels according to the invention were installed, they formed a closed envelope around the basement of the building.

A drain-pipe 7 to lead away water was installed at the bottom of the structure.

Before installation of the panel according to the invention to the basement wall, the basement wall had been provided with a traditional drainage system consisting of gravel and a drain-pipe. The traditional system was not able to prevent water and moisture from entering the basement through the basement wall.

The panel according to the invention was able to drain water from the ground into the hydrophilic layer 3 and vertically down through the hydrophilic layer 3 and the cavities 2 to the drain 7.

The panel was also able to filter the water and prevent backfilled soil from entering the panel. Furthermore, the panel provided thermal insulation on the outside of the basement wall and allowed moisture from the construction to evaporate through the system.

During the installation of the panel to the basement wall it was observed that the installation time was shorter than the installation time for traditional drainage systems . This was particularly caused by the fact that a damp-proof membrane appeared to be superfluous when using the panel according to the invention.

After installing the panel according to the invention the basement was free of intruding water and moisture, and it was observed that the moisture content in the basement construction was significantly reduced.

Example 5

When the panel according to the invention is used for drainage of basement walls, the water needs to be drained vertically down to the drain at the bottom of the basement wall.

The vertical drain capacity needs to correspond to the amount of water that can be expected.

When looking at the indicated water exposure indicated by national norms and standards in Germany and Denmark, it is clear that a drain capacity of the hydrophilic layer and/or internal cavities must be sufficient to keep the hydrophobic layer dry. This has been proven by in situ test. DIN 1986 indicates 3 levels of water exposure along building perimeters.

This norm was used to compare the drain capacity of the internal cavities and hydrophilic layer of panels according to the invention.

The vertical drain capacity through the hydrophilic part of a panel was found to vary with the density.

The vertical flow through 10 cavities with a cross section area each of 70 mm² and a mutual spacing of 100 mm was found to be around 6,8 kg/meter/minute. The test showed that the drain capacity of the panels according to the invention was within the desired range according to DIN 1986.

Example 6

A panel according to the invention was produced for use as green roof" on buildings with pitched roof .

As shown in fig. 4 the panel 1 consisted of a hydrophilic layer 3 and a hydrophobic layer 4.

The dimensions of the panel were: length: 2400 mm, width: 600 mm and thickness: 150 mm. In order to make better connections between panels, the edges on two sides of the panel perpendicular to the direction of the inclination of the roof were prepared with an overlap 5.

The hydrophilic layer 3 had a density of 170 kg/m³ and a thickness of 50 mm. The hydrophobic layer 4 had a density of 85 kg/m³ and a thickness of 100 mm.

The panel was provided with four cuts 6 with a regular mutual spacing of 600 mm perpendicular to the direction of the inclination of the roof. The cut went all through the hydrophilic layer 3 and partly into the hydrophobic layer 4. The purpose of the cuts was to stop an undesired flow of water when the panel was installed on the pitched roof. To prevent undesired flow of water between neighbouring panels the edges of the panel were coated with a layer of bitumen. In the interface between the hydrophilic layer 3 and the hydrophobic layer 4 cavities 7 were established. The cavities had a tubular shape and ran in the whole longitudinal direction of the panel. The cavities 7 had a diameter of 15 mm and were established with a mutual distance of 100 mm. The purpose of the cavities 7 was to serve as reservoir for water and also to lead air to the roots of the plants in the hydrophilic layer 3.

The panel was installed on a pitched roof to serve as an extensive green roof. The inclination of the roof was 25 degrees. Between the roof and the panel a waterproof barrier layer 8 was installed. The installation time was much shorter than the traditional installation with a separate insulation panel and separate growth media panel .

The panel was sowed with grass which grew extremely well in the hydrophilic layer. The hydrophobic layer remained dry and kept its insulation properties.

Claims

1. A panel comprising mineral fibres and a thermosetting resin and comprising a hydrophobic layer and a hydrophilic layer, wherein the hydrophilic layer is in contact with the hydrophobic layer, said hydrophilic layer has a density which is equal to or higher than the density of said hydrophobic layer, preferably the average density of the hydrophilic layer is at least 5%, more preferably at least 10% higher than the density of the hydrophobic layer.

2. A panel according to claim 1, characterized in that said at least one hydrophilic layer has an average density of at least 60 kg/m³, preferably a density of at least 75 kg/m³, more preferably a density of at least 150 kg/m³.

3. A panel according to any one of the claims 1-2, characterized in that said hydrophobic layer has an average density of 20-300 kg/m³, preferably 60-250 kg/m³, and more preferably 80-200 kg/m³.

4. A panel according to any one of the claims 1-2, characterized in that said hydrophobic layer has an average density of 150-2000 kg/m³.

5. A panel according to any of the preceding claims, characterized in said hydrophobic layer being composed from two, three or more sub-layers.

6. A panel according to any of the preceding claims, characterized in said hydrophilic layer being composed from two, three or more sub-layers.

7. A panel according to any of the preceding claims, characterized in that the panel comprises at least one internal cavity, said at least one internal cavity preferably has a size sufficient to allow fluids, gasses or particles to flow freely in the panel and preferably said at least one internal cavity preferably has a cross section area of at least 10 mm².

8. A panel according to claim 7, characterized in that said at least one internal cavity is preferably substantially parallel to one edge of the panel and has a cross section area up to 50000 mm², preferably 100-2500 mm², and if more internal cavities are present, they preferably have a regular mutual spacing of up to 1000 mm.

9. A panel according to any of the preceding claims, characterized in that one or more grooves are formed on one or both sides of the panel

10. A panel according to any of the preceding claims, characterized in that the panel comprises two hydrophilic layers, a first and a second hydrophilic layer separated by a hydrophobic layer.

11. Use of a panel according to claims 1-10 for covering and/or insulation of fagade walls.

12. Use according to claim 11, wherein said use includes the step of mounting the panel so that the hydrophobic layer is brought into contact with the fagade wall.

13. Use of a panel according to any one of the claims 11- 12, wherein the panel comprises at least two hydrophilic layers, and said hydrophilic layers constituting the two sides of the panel, said use comprising the step of mounting the panel so that the first hydrophilic layer is facing away from the fagade wall and is coated with a rendering and the second hydrophilic layer is facing and is preferably in contact with the fagade wall.

14. Use of a panel according to claims 1-10 for thermal insulation and drainage of basement walls.

15. Use according to claim 14, in which the panel comprises a hydrophilic and a hydrophobic layer, said hydrophilic and said hydrophobic layer constitute the two sides of the panel, said use includes the step of mounting the panel with the hydrophobic layer preferably in contact with the basement wall.

16. Use of a panel according to claims 1-10 for drainage purposes .

17. Use of a panel according to claims 1-10 for covering roof on buildings, said use includes the step of mounting the hydrophobic layer in contact with the roof structure.

18. Use of a panel according to claims 1-8 as a growth media for plants.

19. A fagade wall covered with a panel according to claim 1-10.

20. A roof covered with a panel according to claims 1-10.

21. A method of preparing panels preferably according to claims 1-10 comprising at least one hydrophobic layer and at least one hydrophilic layer, comprising the steps of:

- providing a primary mineral fibre web comprising a hydrophobic binding agent and optionally a hydrophobic oil, impregnating the primary web with a hydrophilic binding agent in one longitudinally extending zone, leaving a longitudinally extending zone un- impregnated with hydrophilic binding agent, preferably said hydrophilic binding agent being added to the longitudinally extending zone in an amount sufficient to dominate the hydrophobic binding agent and the optionally hydrophobic oil in said zone, bringing the primary web to overlap itself by laying it out substantially transversally to the longitudinal direction of the primary web to form a secondary web comprising a hydrophobic layer and a hydrophilic layer, compressing the secondary web to obtain a tertiary web, curing or hardening the binding agents in said tertiary web, and cutting the panels from the cured or hardened tertiary web.

22. A method according to claim 21, characterized in that the secondary web is divided into a substantially hydrophobic sub-web and a substantially hydrophilic sub- web, the hydrophilic sub-web being compressed to a desired density and preferably the hydrophobic sub-web being compressed to a desired density, whereafter the compressed hydrophilic sub-web is contacted with the hydrophobic sub-web to obtain a tertiary we .

23. A method according to any one of claims 21-22, characterized in that the hydrophilic layer of the secondary web is divided into sub-layers, whereafter at least one of these sub-layers is further compressed and the sub-layers are united to obtain a hydrophilic layer with sub-layers of different densities, and preferably the hydrophobic layer of the secondary web is divided into sub-layers, whereafter at least one of these sublayers is compressed and the sub-layers are united to obtain a hydrophobic layer with sub-layers of different densities .

24. A method of preparing panels preferably according to claims 1-10, comprising a least one hydrophobic layer and at least one hydrophilic layer, comprising the steps of:

- providing a hydrophobic mineral fibre web constituting a hydrophobic layer, providing a bulk surface layer, distributing the bulk surface layer material onto one surface of the hydrophobic web to form a hydrophilic layer thereon to obtain a tertiary web constituted of the hydrophobic layer and the hydrophilic layer, curing or hardening the tertiary web while the hydrophilic layer is impregnated with a hydrophilic binding agent before or after the curing or hardening oven, and cutting the panels from the cured or hardened tertiary web, wherein said hydrophobic mineral fibre web comprises a hydrophobic binding agent and optionally a hydrophobic oil, and said bulk surface layer material has an average bulk density of at least 150 kg/m³ and comprises a substantially homogenous mixture of at least one mineral material .

25. A method according to claim 24, characterized in that the hydrophobic layer is divided to obtain a least two hydrophobic sub-layers, and preferably the hydrophobic layer is divided into two hydrophobic sub-layers, and the first hydrophobic sub-layer is compressed to obtain a density of from 50 to 110 kg/m³ and the second hydrophobic sub-layer is compressed to obtain a density of from 150 to 250 kg/m³.

26. A method of preparing panels preferably according to claims 1-10, comprising at least one hydrophobic layer and at least one hydrophilic layer, comprising the steps of:

providing a primary mineral fibre web, applying hydrophilic binder to one area extending in the longitudinal direction of the primary web, - applying hydrophobic binder and optionally a hydrophobic oil to the remaining area of the primary web, bringing the primary web to overlap itself by laying it out substantially transversally to the longitudinal direction of the primary web to form a secondary web comprising a hydrophobic layer and a hydrophilic layer, optionally dividing said secondary web into a substantially hydrophobic sub-web and a substantially hydrophilic sub-web, compressing the hydrophilic sub-web to a desired density and preferably compressing the hydrophobic sub-web to a desired density, whereafter the compressed hydrophilic sub-web is contacted with the hydrophobic sub-web to obtain a tertiary web, optionally compressing the tertiary web, curing or hardening the binding agents in said tertiary web, and - cutting the panels from the cured or hardened tertiary web.

27. A method according to claim 26, characterized in that said hydrophilic sub-web is compressed to a density of at least 110 kg/m³, preferably 150 to 2000 kg/m³.

28. A method according to any one of the claims 26-27, characterized in that the hydrophilic layer of the secondary web is divided into sub-layers, whereafter at least one of these sub-layers is compressed and the sublayers are united to obtain a hydrophilic layer with sublayers of different densities.

29. A method according to any one of the claims 26-28, characterized in that the hydrophobic layer of the secondary web is divided into sub-layers, whereafter at least one of these sub-layers is compressed and the sub^¬ layers are united to obtain a hydrophobic layer with sublayers of different densities.