EP2442976A1

EP2442976A1 - Laminated composites

Info

Publication number: EP2442976A1
Application number: EP10727483A
Authority: EP
Inventors: Timothy Sweatman; Douglas Spinney
Original assignee: ECOTECHNILIN Ltd
Current assignee: Eco-Technilin Sas
Priority date: 2009-06-16
Filing date: 2010-06-16
Publication date: 2012-04-25
Also published as: WO2010146355A1; GB0910376D0; GB2471096A

Abstract

A laminated composite material comprising a first layer formed from granulated cork and a binder, and second and third layers each comprising a network of plant-derived natural fibres, the first layer being sandwiched between and bonded to the second and third layers. The binder used to bind the granulated cork in the first layer is a flame-retardant binder, e.g. a plant-derived material such as a furan resin. The second and third layers are bonded to the first layer by a binder component, typically a furan resin.

Description

LAMINATED COMPOSITES

BACKGROUND TO THE INVENTION

Field of the invention

The present invention relates to laminated, composite materials, methods for making such materials, and uses of such materials. It is of particular relevance to the use of natural materials, such as natural fibre-based materials.

Related art

It have been known for many years that the mechanical properties of wood are limited by the anisotropic nature of wood. Wood tends to be strong in a direction parallel to the wood grain but relatively weak in a direction perpendicular to the wood grain. Thus, a known method to address this problem is to provide plywood, in which layers (plies) of wood are laid so that the grain direction of one ply is perpendicular to the grain direction of another ply. The plies are bonded together with an adhesive. Wood-based particle board takes a different approach, by using chips or flakes of wood as a filler and bonding these together using a binder, such as an adhesive. The overall board has substantially isotropic mechanical properties. Similarly, fibreboard (e.g. medium density fibreboard, or MDF) uses wood fibres as a filler, with a binder. These materials (plywood, particle board and MDF) are of use in construction and other applications.

Although it is of great interest to use a renewable material such as wood in the production of construction materials, the materials have several drawbacks. One such drawback is the relatively high density of these materials. Another such drawback is the fire risk provided by the use of wood.

Alternative materials tend to have different drawbacks, in particular cost and environmental drawbacks. It is known, for example, that fibre-reinforced plastics (e.g. carbon fibre reinforced plastics) can have mechanical properties that are far superior to wood-based materials. However, they tend to be relatively expensive and tend to rely on non-renewable materials in their manufacture.

DE-U-29900621 discloses a composite building material for use as interior insulation. A foamed cork moulding is prepared by holding cork in steel tanks at temperatures in excess of 200⁰C. Steam is supplied into the tanks, thereby forming a highly foamed cork body. This is cut into a desired plate thickness. A natural fibre mat is then impregnated with an isocyanate component and a polyol component (the polyol component derived from vegetable oil). The impregnated mat is then applied to the cork plate and allowed to cure to form polyurethane.

SUMMARY QF THE INVENTION

The present inventors have realised that alternative materials may be provided which are laminated composites, most preferably derived from natural, renewable sources, and which have excellent mechanical properties. The present inventors also consider that the use of polyurethane is to be avoided where possible, in view of the non-sustainability of the starting materials for forming polyurethane, and in view of the health risks associated with working with polyurethane and its precursors.

Accordingly, in a first aspect, the present invention provides a laminated composite material comprising at least a first layer and a second layer, the first layer comprising at least one material selected from the group consisting of: cork, balsa wood, paper, card, wood particles, wood fibres, wood waste and phase change thermal mass materials, and the second layer comprising a network of fibres, preferably natural fibres, the first layer and the second layer being bonded to each other.

In a second aspect, the present invention provides a method for the manufacture of a laminated composite material comprising at least a first layer and a second layer, the first layer comprising at least one material selected from the group consisting of: cork, balsa wood, paper, card, wood particles, wood fibres, wood waste and phase change thermal mass materials, and the second layer comprising a network of fibres, preferably natural fibres, the method including the step of pressing the first layer and the second layer together to bond these layers together.

In a third aspect, the present invention provides a use of the laminated composite material in a constructional application, e.g. in a building, in a vehicle such as a car or truck, in a railway carriage, etc.

In a fourth aspect, the present invention provides a use of the laminated composite material in an acoustical control application, e.g. in a building, in a vehicle such as a car or truck, in a railway carriage, etc.

In a fifth aspect, the present invention provides a use of the laminated composite material in a fire safety application, e.g. in a building, in a vehicle such as a car or truck, in a railway carriage, etc.

In a sixth aspect, the present invention provides a use of the laminated composite material in a thermal insulation application, e.g. in a building, in a vehicle such as a car or truck, in a railway carriage, etc.

Using the invention, it is possible for the natural mechanical advantages of cork (low density, excellent compression properties) to be utilised, or the advantages of an alternative core material to be utilised, if the material of the first layer is other than cork, whilst the second layer may provide tensile strength to give the composite significantly better properties in tension or bending than would be provided by the first layer alone.

Optional features relating to the present invention will now be set out. These may be combined (either singly or in any combination) with any aspect of the invention unless the context demands otherwise.

Preferably, the material includes a third layer, similar to the second layer, located at an opposing face of the first layer compared with the second layer. The third layer and the first layer are preferably bonded to each other. In this way, it is preferred that the first layer is sandwiched between the second layer and the third layer.

Preferably, the material is in the form of a plate or board, i.e. with dimensions of length and width being significantly (e.g. at least 10 times) greater than the thickness of the plate or board.

The material may have a curved or profiled upper and/or lower surface.

The thickness of the first layer may be at least lmm. Typically, the thickness of the first layer is significantly greater than this, e.g. at least 5mm or at least 10mm. The thickness of the second layer (and the thickness of the third layer, if present) is preferably at least 5 times smaller than the thickness of the first layer.

In a preferred embodiment, the core is formed of cork, which is discussed in more detail below. However, alternative embodiments may use alternative materials in the core. The core may, for example, comprise one or more of balsa wood, paper, card, wood particles, wood fibres, wood waste and phase change thermal mass materials.

Balsa wood (Ochroma pyramidale or O. Lagopus) is a well- known hardwood having a very low dried density, typically about 0.16 g/cm³.

Paper, card or cardboard may be used in the first layer. For example, a honeycomb structure may be used. Wood particles, wood fibres or other wood waste may be used.. Typically, such materials are known for their use in composite materials such as medium density fibreboard, chipboard, etc., in combination with a binder such as a glue,

Phase change thermal mass materials are known for their use in products such as DuPont™ Energain®. These are building panels having aluminium skins. The core of the panels is formed from copolymer and paraffin, at a proportion of 60% paraffin by weight. The paraffin is selected so that it undergoes a phase change (between solid and liquid) at 21.7⁰C. This means that the building panel can absorb and release heat by harnessing this phase change. In effect, when the temperature reaches about 22⁰C, the paraffin melts, allowing the panel to absorb heat without increasing in temperature. When the temperature drops to 18⁰C and below, the panel releases the heat as the paraffin solidifies again,

It is known that cork is derived from the bark of specific trees, notably the cork oak tree. The bark is harvested from the tree at regular intervals, with typically 9 to 12 years between each harvest. Cork trees typically live for 200-250 years. After the bark has been harvested from the tree, a new layer of bark regrows. Thus, cork is a naturally renewable material, in the sense that it is renewed by a natural plant growth process, and is replaced within a relatively short period, as indicated above. At present, a significant proportion of cork is used to make bottle closures, typically for wine bottles.

The first layer may further include a binder. In this case, it is typical that the first layer is manufactured from granulated cork which has been mixed with a binder and pressed to form a solid body. The first layer may, for example, be cut from such a solid body. Granulated cork comprises granules of cork material obtainable by shredding or otherwise breaking cork bark. Alternatively, granulated cork may be obtained by recycling cork material, e.g. from used (or unused) bottle closures. It is specifically preferred that the first layer is not formed from foamed cork.

The proportion of binder to cork in the first layer may be as high as 50% by weight. However, it is preferred that the amount of binder in the first layer is lower than this. For example, the proportion of binder to cork in the first layer may be 45% by weight or less, more preferably 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, or 15% by weight or less. The proportion of binder to cork in the first layer may be 1% by weight or more, more preferably 5% by weight or more or 10% by weight or more. Most preferably, the proportion of binder to cork in the first layer is in the range 10-15% by weight. Preferably, the density of the first layer is not more than 0.4 gem^"3 (i.e. not more than 400 grams per litre) . More preferably, the density of the first layer is not more than 0.35 gem^"3, more preferably not more than 0.3 gem^"3 and is preferably about 0.27 gem^"3.

However, in other embodiments, the density of the first layer should be not more than 0.6 gem^"3 (i.e. not more than 600 grams per litre) .

Cork itself is a relatively flame-retardant material. In order to utilise this advantage in the composite, it is preferable that the binder used in the first layer is either used at low levels, or that the binder itself is also flame- retardant, or both of these features. A typical cork binder is polyurethane . Preferably, the binder used in the first layer is a thermosetting binder. Thermosetting polyurethane can be used, for example, although this may not be preferred for safety or environmental reasons. Alternative binders are discussed in more detail below.

Preferred features of the second layer are now set out. These features are also separately preferred features of the third layer, if present. Preferably the second layer is in the form of a sheet. Preferably, the fibres of the second layer are arranged substantially randomly but substantially parallel to a surface of the second layer. The fibres of the second layer may have an average length of at least 10mm, more preferably at least 20mm, at least 30mm, at least 40mm, at least 50mm, at least 60mm or at least 70mm. The fibres may be processed (e.g. cut) to have a maximum length of up to 150mm, for example .

Preferably, the fibres are natural (i.e. non-synthetic) fibres. In particular, they are preferably plant-derived fibres. Preferably, the plant-derived fibres are one or more selected from the following: hemp, jute, flax, ramie, kenaf, rattan, soya bean fibre, okra fibre, cotton, vine fibre, peat fibre, kapok fibre, sisal fibre, banana fibre or other similar types of bast fibre material. Such plant- derived fibres are fibrous and are flexible. Thus it is preferred that the filler material of both the first layer and of the second layer are plant-derived renewable materials .

Preferably, the second layer has a binder component, in order to form a strong network of fibres. The binder component may be a synthetic binder but is more preferably a natural binder. Typically, the binder component may be heat activated. For example, whether the binder is a synthetic material, it may be selected from one or more of: polypropylene, polyethylene, polyester, vinyl, polyvinyl acetate, and other similar binding material. Where the binder is, more preferably, a natural material, it may be selected from one or more of: polylactic acid, starch, furan resin, and other similar binding material. Further detail relating to binders is set out below.

As mentioned above, the binder component may be heat activated. The binder component is typically a polymer or resin. This may be thermoplastic or thermosetting. Thermosetting binders are particularly preferred. When the second layer is heated to an activation, or melting, temperature of the binder, inter-fibre bonds are established.

Preferably, the percentage weight of the binder component in the second layer is in the range lwt% to 75wt%. The percentage weight of the binder component in the second layer may be at least lwt%, 5wt%, 10wt%, 15wt%, or 20wt%. The percentage weight of the binder component in the second layer may be at most 70wt%, 65wt%, 60wt%, 55wt%, 50wt% or 45wt%. The remaining weight of the second layer is taken up by the fibre content of the second layer. In other words, these values for the percentage weight of binder component in the second layer are expressed in terms of the weight of the second layer when the binder component is present. Preferably, the method of forming the material includes the step of providing a fibre mat and pressing the fibre mat to the first layer, in order to create the second layer and bond the second layer to the first layer in a single step. This step may include heating. The composite may be heated in this step to a temperature of at least 80 degrees C, more preferably to at least 100 degrees C, at least 120 degrees C, or at least 140 degrees C. Preferably, in this step, the composite is heated to a temperature of 250 degrees C or lower, more preferably 200 degrees C or lower. A typical temperature for this heating step is 160-165 degrees C.

In this step, the fibre mat is typically compressed to a greater extent than the first layer. Additionally, after this step the fibre mat typically does not recover its shape but instead is permanently compressed to form the second layer. In contrast, the first layer typically at least partially recovers from the compression. In this step, the density of the second layer at the end of the step is typically at least three times (preferably at least four times or at least five times) the density of the fibre mat at the beginning of the step.

The binder component for the second layer may be incorporated in the fibre mat, e.g. as binder particles. However, more preferably, at least some of the binder component for the second layer is preferably applied to the surface of the fibre mat facing the first layer, and/or is applied to the surface of the first layer facing the fibre mat. This may be applied by sprinkling, spraying, painting, roller coating, etc.

Additional binder component for the second layer may be provided by applying the binder component to the opposite face of the second layer, e.g. by sprinkling, spraying, painting, roller coating, dipping, impregnation, etc.

In the method set out above, the first layer is pre-formed before the second layer is applied to the first layer. However, it is possible for the first layer and the second layer to be formed substantially at the same time. In this case, the fibre mat and granulated cork (typically with a binder mixed with the granulated cork) are brought into contact, pressed and heated. This allows the granulated cork to be adhered by the binder to form the first layer and, at the same time, allows the second layer to be formed and bonded to the first layer. This also allows the first layer to be moulded to any desired shape, e.g. to include reinforcing ribs or other surface undulations.

Preferably, the fibre mat is formed by needle punching. Alternatively, air laying may be used. Such fibre mats are non-woven. Non-woven mats are preferred. However, woven mats may be used. The area density of the fibre mat may be in the range 300-3000 grams per square metre (gsm) .

Preferably, the density of the second layer, is greater than the density of the first layer. For example, the density of the second layer may be at least 0.5 gem^"3, more preferably at least 0.6 gem^"3, more preferably at least 0.7 gem^"3, e.g. about 0.8 gem^"3.

Preferably, the binder component used to bond the second layer to the first layer (and also preferably to retain the shape of the second layer after pressing) is a plant-derived material. For example, the binder component may be furfural (furan-2-carbaldehyde) or a derivative of furfural such as furfural alcohol, furan, tetrahydrofuran and tertahydrofurfural alcohol (collectively referred to as furans) . In particular, it is preferred that the binder component is a furan resin, such as a resin comprising prepolymers of furfuryl alcohol. The cured resin may therefore be a poly (furfuryl alcohol) .

For example, a furan resin may be produced in which furfural replaces formaldehyde in a conventional production of a phenolic resin. The furan resin cross links (cures) in the presence of a strong acid catalyst via condensation reactions. Furfural is an aromatic aldehyde, and is derived from pentose (C5) sugars, and is obtainable from a variety of agricultural byproducts. It is typically synthesized by the acid hydrolysis and steam distillation of agricultural byproducts such as corn cobs, rice hulls, oat hulls and sugar can bagase. Further details relating to furan resins whose use is contemplated in the present invention is set out in "Handbook of Thermoset Plastics", edited by Sidney H. Goodman, Edition 2, Published by William Andrew, 1998, ISBN 0815514212, 9780815514213, Chapter 3: Amino and Furan Resins, by Christopher C. Ibeh, the content of which is incorporated herein by reference in its entirety.

Furan resins are of particular interest because they are derived from natural, renewable sources, they bond well to natural fibres and they have good flame-retardancy properties.

The same binder component may be used in the first layer, i.e. to as the binder to bind the cork granules together in the first layer.

Thus, an aspiration of the present invention is to provide a laminate composite material as set out above, which consists essentially only of natural, renewable, plant-derived materials. For example, at least 95% by weight of the laminate composite (and more preferably at least 96% by weight, at least 97% by weight, at least 98% by weight or at least 99% by weight of the laminate composite, and most preferably 100% by weight of the laminate composite) may be natural, renewable, plant-derived materials.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS, AND FURTHER OPTIONAL FEATURES

Preferred embodiments of the present invention will now be set out, in which further optional features of the invention are described. Such features may be combined either singly or in any combination with any aspect of the invention, unless the context demands otherwise.

Flax plants can be grown with a stem length between 600mm and 800mm. The stem has strong fibre bundles running from root to top. These fibre bundles are disposed outermost in the stem, and in the internal space between the fibre bundles there is a central stalk consisting of wood cells (shives) .

In comparison, hemp plants have stems which are considerably longer than the stem of the flax plants. They may have stem lengths from 2000mm to 3000mm. Similarly, the hemp stem may comprise outer fibre bundles and a inner wood cells (shives)

Traditionally, the flax or hemp fibres are separated from the woody parts of the stem by a retting process. Retting is a microbiological process which partially decomposes the natural fibre. In particular, retting causes hemicellulose and pectin in the natural fibre to bind the fibres together.

Harvesting of flax and hemp for textile production consists of pulling up all of the plant. Pulling up the plants is a slow and work intensive process. After pulling up the plants, the plants are laid aside for retting and the retting process takes place in the field (e.g. dew-retting) . The degree of retting is important for determining the properties of the fibres in the making of textile fibres for carding and spinning.

Subsequently, the stems are pressed into bales and transported to a fibre factory. The seeds are torn off in a scutching mill. Scutching is a process of mechanically separating the fibres from the woody part.

Fibre mats may be made using the harvested plant fibres, such as hemp or flax fibres. The fibres may be subjected to carding. Carding the fibres consists of passing the fibres through a card (a comb-like structure) , which disentangles the fibres and straightens the fibres. The fibres may be cut to a suitable length, e.g. about 8cm. Thereafter, a fur is formed and finally a needle punching process is performed for making the finished fibre mat. Alternatively, the fibre mat may be formed by air-laying. Alternatively woven natural fibre mats may be used. However, in the most preferred embodiments of the present invention, the natural fibre mat is formed by needle punching, since this provides a good tensile strength to the mat (even before the addition of the binder component) and yet can be carried out on a large scale.

In some cases, it may be preferred not to use a retting process. In this case, the plant material may be subjected to a hammer milling process, as described in WO2008/107664, the content of which is incorporated herein by reference in its entirety.

According to a first embodiment of the invention, there is provided a laminate composite with a first layer consisting of granulated cork and a polyurethane (or polypropylene) binder. Such a material is readily available and is typically formed by pressing and heating a mixture of the cork granules and the binder, typically at about 10-15% by weight of binder. This process forms a block, and the first layer can be formed by cutting the block to an appropriate size and shape. For example, the first layer may be in the shape of a board.

The laminate composite of the first embodiment has second and third layers, bonded to opposite faces of the first layer. Each of the second and third layers is formed from a plant fibre mat. Suitable plant fibre mats include needle punched hemp fibre mats and needle punched flax fibre mats, as described above. Alternatively, air laid fibre mats may be used.

The plant fibre mat may have a binder component already incorporated, such as a polypropylene binder. More preferably, the plant fibre mat is partially impregnated (or coated) with an uncured furan resin binder, set out in more detail below. Still further, the face of the first layer to which the plant fibre mat is to be applied can be coated with the same binder, in order to improve bonding between the first and second layers at a specified degree of compression applied during the process.

The plant fibre mats are placed on either side of the first layer in a heatable press. The arrangement is then heated to a temperature of 160-165 degrees C and pressed. The degree of compression is set to compress the plant fibre mats to a thickness of about one-fifth of their starting thickness, thereby to form the second and third layers.

In order to demonstrate the typical properties of laminated composites manufactured according to the invention, composite boards of thickness 10 mm were manufactured by applying furan resin to one side of needle-punched natural fibre mat, to form partially impregnated natural fibre mats. The dry side of two such partially impregnated natural fibre mats were placed in contact with the surface of the cork board. The composite was then heated and pressed for 60 seconds under the conditions set out above.

The cork used in these tests was NL20 CoreCork from Amorim Cork Composites (PO Box 1, Ruade Meladas, 260 4536-902 Mozelos VFR, Portugal) .

A comparison between the mechanical properties of the cork core and of the finished laminated composite is set out in Table 1:

Table 1

The shear strength and modulus of the cork composite laminate was measured based on EN 314, whereas the corresponding properties of the cork core were measured using ASTM C273.

The test results demonstrate that a laminated composite material according to the invention has certain properties that are a significant improvement over the corresponding properties of the cork core material alone, in particular in terms of stiffness and strength.

In order to improve the bonding of the second and third layers to the first layer, an additional binder component may be incorporated at the interface between the first layer and the second layer and at the interface between the first layer and the third layer. This may be, for example, by painting the binder component on to the plant fibre mats and/or on to the surfaces of the first layer. The binder component is furan resin. Furan resin can be obtained, for example, from TransFurans Chemicals bvba, Industriepark Leukaard 2, 2440 GEEL, Belgium. Furan resin can be cured either by heat activation or by cold-cured using a catalyst, depending on the resin used. Based on the final weight of the second layer, the proportion of binder component in the second layer is typically at most about 45% by weight, based on the weight of the second layer including the binder component. In alternative embodiments, it may be preferred to include up to at most 35% by weight binder component in the second layer, in order to reduce the density and cost of the product.

After forming, the laminate composite has remarkable stiffness and a low density. The cork first layer provides the laminate with useful thermal insulation and acoustical control properties. Furthermore, the cork first layer is a naturally fire-retardant material, and so the composite may be used in applications where fire-retardancy is required.

A second embodiment of the invention is similar to the first embodiment except that in the heating/pressing step, the composite is not made to be flat. Instead, at least one major surface of the composite is formed to have a curved or undulating surface. For example, an array of strengthening ribs may be formed at one or both major surfaces of the composite. A third embodiment of the invention is similar to the first embodiment except that the third layer is not provided.

A fourth embodiment of the invention is similar to the first embodiment except that the first layer is formed from granulated cork and furan resin as a binder. In this way, the entire product is formed of natural, renewable, plant- derived materials.

A particularly suitable liquid binder component is furan resin. Furan resin can be obtained, for example, from TransFurans Chemicals bvba, Industriepark Leukaard 2, 2440 GEEL, Belgium, under the trade name BioRez™, for example BioRez™ 050525-S-1B. It is preferred that this resin is cured via a heat-activated catalyst. The curing temperature of this resin is in the range 140-190 degrees C. Storage of this product at 20-25 degrees C is possible for extended periods, e.g. up to one month or longer.

A suitable catalyst is maleic acid. This is preferred since it is considered not to have an adverse effect on the natural fibres of the mat. An alternative catalyst is citric acid.

Suitable furan resin can be obtained by the following process. Hemicellulosic agricultural waste (e.g. waste from sugar cane) are rich in pentose sugars. Controlled hydrolysis of pentose sugars gives furfural. This is converted to furfuryl alcohol by catalytic hydrogenation. Furfuryl alcohol can then be formed into prepolymers of furfuryl alcohol, which is the base material of the resin.

One particular advantage of furan resin is that it is substantially free from volatile organic solvents. Furthermore, during the curing process, water is formed from condensation reactions which occur as the resin crosslinks.

There are various possible routes to achieve full or partial impregnation of the natural fibre mat with the curable liquid binder component (i.e. resin) .

One suitable approach is to dip coat the natural fibre mat with the resin. This can be one-sided or two-sided dip coating. Alternatively, the natural fibre mat can be coated with resin by roller coating or foam coating. In these methods, and particularly for dip coating, it can be advantageous to use a doctor blade, scraper blade or similar to make more uniform the amount of resin coated on the natural fibre mat per unit area.

In the presently preferred embodiment, the core is formed of cork, discussed in detail above. However, alternative embodiments may use alternative materials in the core. The core may, for example, comprise one or more of balsa wood, paper, card, wood particles, wood fibres, wood waste and phase change thermal mass materials.

Balsa wood (Ochroma pyramidale or 0. Lagopus) is a well- known hardwood having a very low dried density, typically about 0.16 g/cm³. The skilled person will understand that it is straightforward to substitute, for example, a balsa wood panel for the cork core used in the embodiments described above.

Paper, card or cardboard may be used in the first layer. For example, a honeycomb structure may be used. The skilled person will understand how a paper honeycomb can be used in order to form the core.

Wood particles, wood fibres or other wood waste may be used. Typically, such materials are known for their use in composite materials such as medium density fibreboard, chipboard, etc., in combination with a binder such as a glue,

Phase change thermal mass materials are known for their use in products such as DuPont™ Energain®. These are building panels having aluminium skins. The core of the panels is formed from copolymer and paraffin, at a proportion of 60% paraffin by weight. The paraffin is selected so that it undergoes a phase change (between solid and liquid) at 21.7⁰C. This means that the building panel can absorb and release heat by harnessing this phase change. In effect, when the temperature reaches about 22°C, the paraffin melts, allowing the panel to absorb heat without increasing in temperature. When the temperature drops to 18⁰C and below, the panel releases the heat as the paraffin solidifies again. In one embodiment of the present invention, the same core material may be used but with reinforcing second and third layers formed of natural fibres and a binder component, as described with respect to the cork composite laminate embodiments.

The embodiments set out above have been described by way of example. On reading this disclosure, modifications of these embodiments, further embodiments and modifications thereof will be apparent to the skilled person and as such are within the scope of the present invention.

Claims

1. A laminated composite material comprising at least a first layer and a second layer, the first layer comprising at least one material selected from the group consisting of: cork, balsa wood, paper, card, wood particles, wood fibres, wood waste and phase change thermal mass materials, and the second layer comprising a network of natural fibres and a binder component, the first layer and the second layer being bonded to each other via the binder component, and wherein the binder component comprises a furan resin.

2. A material according to claim 1 further comprising a third layer, similar to the second layer, located at an opposing face of the first layer compared with the second layer, the third layer and the first layer being bonded to each other, so that the first layer is sandwiched between the second layer and the third layer.

3. A material according to claim 1 or claim 2 wherein first layer is formed from granulated cork and a binder.

4. A material according to claim 3 wherein the binder in the first layer is a plant-derived material.

5. A material according to claim 4 wherein the binder in the first layer is a furan resin.

6. A material according to any one of claims 1 to 5 wherein the density of the first layer is not more than 0.4 gem^'3.

7. A material according to any one of claims 1 to 6 wherein the fibres of the second layer are plant-derived fibres.

8. A material according to claim 7 wherein the plant- derived fibres are one or more selected from the following: hemp, jute, flax, ramie, kenaf, rattan, soya bean fibre, okra fibre, cotton, vine fibre, peat fibre, kapok fibre, sisal fibre, banana fibre. »

9. A material according to any one of claims 1 to 8 wherein the density of the second layer is greater than the density of the first layer.

10. A method for the manufacture of a laminated composite material comprising at least a first layer and a second layer, the first layer comprising at least one material selected from the group consisting of: cork, balsa wood, paper, card, wood particles, wood fibres, wood waste and phase change thermal mass materials, and the second layer comprising a network of natural fibres and a binder component comprising a furan resin, the method including the step of pressing the first layer and the second layer together to bond these layers together via the binder component .

11. A method according to claim 10 wherein at least some of the binder component is applied to the interface between the first and second layers, before pressing.

12. A method according to claim 10 or claim 11 wherein at least some of the binder component is applied to a surface of the second layer opposite to the interface between the first and second layers, before pressing.

13. A method according to any one of claims 10 to 12 further comprising providing a third layer, similar to the second layer, and pressing to bond it to an opposing face of the first layer, so that the first layer is sandwiched between the second layer and the third layer.

14. A method according to any one of claims 10 to 13 in which the first layer and the second layer are formed substantially at the same time, including the step of bringing a fibre mat, binder component, and at least one material for the first layer and an optional binder into contact, pressing and heating, wherein the material for the first layer comprises at least one material selected from the group consisting of: granulated cork, balsa wood, paper, card, wood particles, wood fibres, wood waste and phase change thermal mass materials.

15. A method according to claim 14 wherein the binder in the first layer is a furan resin.