WO2008107664A1

WO2008107664A1 - Plant fibre mat and method of making a plant fibre mat

Info

Publication number: WO2008107664A1
Application number: PCT/GB2008/000730
Authority: WO
Inventors: Douglas Spinney; Peter Topham
Original assignee: Eco Technilin Limited
Priority date: 2007-03-05
Filing date: 2008-03-04
Publication date: 2008-09-12
Also published as: EP2118351A1; GB2452235A; GB0704236D0

Abstract

A fibre mat has plant-derived fibres arranged in a fibrous network and a plant-derived material, different from the plant-derived fibres, held within the fibrous network. The fibrous network comprises an array of linked fibres, the fibres each being substantially single fibres. The mat also has a heat activated binder component. Also disclosed are methods for forming the fibre mat and fibre panels formed from fibre mats.

Description

PLANT FIBRE MAT AND METHOD OF MAKING A PLANT FIBRE MAT

The present invention relates to mats made from plant fibres and a method of making such mats and in particular, mats made from two different types of plant.

Flax plants can have a stem with a length between 600 and 800 mm. 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 lengths from 2000 mm to 3000 mm. Similarly, the hemp stem may comprise outer fibre bundles and a inner wood cells (shives) consisting of short fibres with lengths from 0.5 mm to 0.6 mm.

Traditionally, the flax or hemp fibres are separated from the wood fibres in 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 the 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. The retting process is a biological process and so the retting process is difficult to control.

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

The straws are processed by placing the stems in parallel and treating them in parallel through processing equipment .

Fibre mats are made using the harvested plant fibres such as the above mentioned hemp or flax fibres. Such fibre mats are formed by carding the fibres. Carding the fibres consists of passing the fibres through a card, a comb-like structure, which disentangles them and straightens the fibres. Thereafter, a fur is formed and finally a needling process is performed for making the finished fibre mat. In order to perform the needling process, the flax or hemp is required to be a certain humidity so that the flax or hemp is pliable. If the flax or hemp is too dry, then the flax or hemp will to dust and short fibres. Short fibres are easily torn out of a formed fibre mat.

Furthermore, the above mentioned carded fibre mats have fibres which are lying in separate piles . Often there are very few or no strong bonds between the single layers in the fibre mat. EP-A-1090176, which is incorporated in its entirety by reference herein, discloses a method of manufacturing a fibre mat. The method incorporates the steps of exposing and using fibres from a completely un-retted to a strongly over-retted quality, depending on the purpose of use .

Specifically, EP-A-1090176 discloses a method of making a vegetable fibre mat including the steps of harvesting the plants by cutting and threshing, retting wholly or partially the plant stems, drying them for providing a desired water content, shortening and separating the fibres for establishing a fibre mass comprising mainly single fibres and for creating their fibrillation, forming the mat by a dry forming process whereby the fibres are randomly oriented and form inter-fibre bonds. Therein, bonds are formed between the single fibres without the need of a binder component.

The above mentioned method of EP-A-1090176 means that a vegetable fibre mat may be made using stems that are not retted, which have been dew-retted on the field, or which have been retted by a controlled retting process (e.g. with a chemical process) .

By partially retting and subsequent mechanical and / or chemical treatment it is possible to decompose the fibre bundles and form single fibres.

The single fibres are used to provide more "airy" products ( e.g. less dense) than is the case when making products from fibre bundles. Single cell fibres are not suitable for making fibre mats by the above mentioned needle processes because the single cell fibres are shortened. This makes also makes the single cell fibres unsuitable for carding.

As mentioned previously, a step of the method of EP-A- 1090176 requires that the fibres are fibrillat'ed. The fibrillation of the fibres causes the single fibres to form a sheet wherein the fibre bundles mesh with each other. Essentially, bonds are formed between the single fibres and the subsequent formed mat does not need to be needled or steam bonded. The formed fibre mat is airy and voluminous and may be compacted to the desired degree, depending on the intended use. The formed fibre mat may also include a binder component.

In this way, a mat made from plant fibres or other natural fibres does not use synthetic fibres and may be considered environmentally friendly. For example, vehicle manufacturing regulations of certain countries require the vehicle to be made out of a certain percentage of renewable or green products (e.g. made from plants) .

The present inventor has realised that such known mats made from plant fibres have physical properties which are principally determined by the physical properties of the raw material, e.g. hemp or flax.

For example, fibre mats, such as those made according to the method EP-A-1090176 using hemp or flax are very flexible when processed into single cell fibres. In order to stiffen the fibre mats, the fibre mats must be reinforced. Previously, fibre mats were stiffened using additives such as synthetic binders or a plastics material. Consequently, the addition of synthetic materials such as those derived from petroleum to the fibre mats mean the fibre mats are considered to be less environmentally friendly.

Accordingly in a general aspect, the present invention provides a fibre mat having plant-derived fibres and a plant-derived material, the plant-derived fibres being different from the plant-derived material.

In a first preferred aspect, the invention provides a fibre mat having: plant-derived fibres arranged in a fibrous network; and a plant-derived material, different from the plant- derived fibres, held within the fibrous network, to provide a mat structure.

As mentioned previously, it is known to make fibre mats from plants using plant-derived fibres. Typically the plant-derived fibres are bast plant fibres. That is, using parts of plants which are particularly fibrous.

The present inventor has observed a surprising effect when a plant-derived material which is different from the plant-derived fibres is mixed with the plant-derived fibres; the plant-derived material is held within a network formed from the plant-derived fibres. Consequently, the characteristics of the plant-derived material may complement the characteristics of the plant- derived fibres and form a fibre mat composite. By mixing plant-derived fibres with a plant-derived material, which is different from the plant-derived fibres, the physical properties and structure of the fibre mat may be altered. The invention has particular applicability where the plant-derived fibres are derived from a plant of a different species to that from which the plant-derived material is derived.

Typically, the plant-derived material cannot be used for making a fibre mat alone because the plant-derived material does not form suitable fibres.

Usually, the plant-derived fibres are high quality and are expensive. By incorporating the plant-derived material in the fibrous network, a smaller amount of plant-derived fibres is required and hence the resulting fibre mat has a reduced manufacturing cost.

Preferably, the plant-derived fibres have an average length between 0.1mm and 150mm. In this way, the structure of the fibrous network may be altered by changing the length of the fibres and the number of links each fibre has in the fibrous network.

Advantageously, the addition of a plant-derived material different from the plant-derived fibres may change the overall physical properties of the fibre mat. Preferably, the plant-derived material comprises material elements having an average stiffness greater than that of the plant-derived fibres. This arrangement provides the fibrous network of plant-derived fibres which is reinforced with material elements of the plant-derived material. The material elements contribute significantly to the overall stiffness of the fibre mat, whilst the plant-derived fibres provide a fibrous network to hold the material elements. This means that the fibre mat requires less reinforcement with synthetic components, i.e. a synthetic binder component, which advantageously reduces the cost of the fibre mat manufacturing process. Preferably, the plant-derived material elements have an average length between 0.1mm and 150mm.

Preferably, the fibrous network comprises an array or mesh of linked fibres, said fibres each being substantially single fibres. The arrangement of single fibres provide more links / nodes in the fibrous network compared to larger bundles of fibres and this provides a stronger network and mat structure.

Alternatively, the fibrous network comprises interlinking fibre bundles, each bundle having a plurality of fibres. The plurality of fibres may be a few single fibres up to a maximum of 10 to 30 single fibres.

Typically, the plant-derived material is one or more selected from the following: wheat straw, oat straw, rye straw, barley straw, grass straw, rice straw, bean straw, oilseed rape straw, cellulose, paper, cardboard, coconut husk or other similar plant-derived material. Such material these plants tends to break down to a dust when mechanically worked. Preferably, the plant-derived fibres are one or more selected from the following: hemp, jute, flax, ramie, kenaf, rattan, soya bean fibre, okra fibre, vine fibre, peat fibre, kapok fibre, sisal fibre, banana fibre or other similar types of bast fibre material. As mentioned previously, such plant-derived fibres are fibrous and are flexible .

Preferably, the mat has a binder component. Often it is desirable to include a binder component to provide strong bonds between the plant-derived fibres and the plant- derived material. Preferably, the binder component is a synthetic binder or a natural binder. Additionally or alternatively, the binder component may be heat activated. More preferably, the binder component is selected from one or more of: polypropylene, polylactic acid, polyethylene, polyester, vinyl, polyvinyl acetate, starch or other similar binding material.

As mentioned above, the binder component may be heat activated. Typically, the binder component is a polymer, for example thermoplastic. When forming composite products and / or high strength products with a fibre reinforcement in a matrix structure of polymers, relatively large amounts of the binder component may be used. When the fibre mat is heated to an activation, or melting, temperature of the plastic, inter-fibre bonds are established.

The amount and type of binder component added will thus depend on the intended use of the formed fibre mat. A fibre mat intended for isolation mats may contain very little or no binder. Alternatively, a composite sheet, for example, has properties corresponding to those known from fibre and chip-boards will contain a larger amount of binder component.

As mentioned previously, the amount of the binder component present in the fibre mat may alter the physical properties of the overall fibre mat. Preferably, the percentage weight of the binder component is the range lwt% to 50wt%. All percentage weight values disclose herein refer to the percentage weight (wt%) with respect to the total weight of the fibre mat. (e.g. a mat have 50wt% of a binder component means there are 50 parts by weight binder component in 100 parts by weight fibre mat.) More preferably, the percentage weight of the binder component is in the range 10wt% to 40wt%. Even more preferably, the percentage weight of the binder component is in the range 20wt% to 30wt%. These upper and lower limits may be combined together to provide a range for the range of binder component in the fibre mat. Alternatively, the percentage weight of the binder component may be at least: lwt%, 5wt%, 10wt%, 15wt%, or 20wt%. The percentage weight of the binder component may be at most 25wt%, 30wt%, 35wt%, 40wt%, 45wt% or 50wt%.

Preferably, the percentage weight of the plant-derived fibres is in the range 5wt% to 95wt%. More preferably, the percentage weight of the plant-derived fibres is in the range 20wt% to 80wt%. Even more preferably, the percentage weight of the plant-derived fibres is in the range 30wt% to 70wt%. Most preferably, the percentage weight of the plant-derived fibres is in the range 40wt% to 60wt%. Alternatively, the percentage weight of the plant-derived fibres may be at least lwt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, or 40wt%. The percentage weight of the plant-derived fibres may be at most 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% or 95wt% .

Preferably, the percentage weight of the plant-derived material is in the range 5wt% to 95wt% . More preferably, the percentage weight of the plant-derived material is in the range 20wt% to 80wt%. Even more preferably, the percentage weight of the plant-derived material is in the range 30wt% to 70wt%. Most preferably, the percentage weight of the plant-derived material is in the range

40wt% to 60wt%. Alternatively, the percentage weight of the plant-derived material may be at least lwt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, or 40wt%. The percentage weight of the plant-derived material may be at most 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% or 95wt%.

Preferably, the fibre mat has additional material elements held in the fibrous network. Preferably, the additional material elements are non plant-derived organic material . Typically the non plant-derived organic material may be wool. Alternatively, the additional material elements may be one or more selected from the following: peat, rice waste, foam, acoustic insulation, absorbent granules, sawdust, vermiculite

(mica) . Additionally, or alternatively the additional material elements may include a fire retardant such as borax, boric acid, aluminium hydroxide or other similar material or materials.

The fibre mat may have at least two layers, the at least two layers having different percentage weights of the plant-derived material and / or different percentage weights of the plant-derived fibres. In this arrangement, a composite fibre mat structure may be formed having multiple layers with different physical properties. More preferably, a layer of the at least two layers has a different plant-derived material and/or different plant- derived fibre to another layer of the at least two layers . In this arrangement, the relative physical properties of the layers of the fibre mat can be further altered. For example a stiff layer can be combined with a thermally insulating layer.

As mentioned previously, the plant-derived material and the plant-derived fibres have different physical properties. Preferably, a physical property of the plant-derived material has a different value with respect to the same physical property of the plant-derived fibre. More preferably, the physical property may be any one of the following: thermal conductivity, density, elastic modulus or tensile strength. Even more preferably, the elastic modulus of the plant-derived material is greater than the elastic modulus of the plant-derived fibres. Other properties of relevance here include absorbency (e.g. water absorbency), acoustic properties, fire retarding properties, odour properties, plant root penetration properties, hydrophobic/hydrophilic properties . This means the plant-derived material may have a different acoustic insulation properties, liquid absorbency, hardness, thermal insulation properties, smell, density, insect repelling properties, fire retarding properties, odour properties, plant root penetration properties, and/or hydrophobic/hydrophilic properties, etc. from those properties of the plant- derived fibres .

Preferably, the fibre mat has a thickness between 2mm and 300mm.

Preferably, fibre mat has an area density in the range of 30 and 8000g/m².

Preferably, the fibrous network of plant-derived fibres is a web and net formation.

In a second aspect, the present invention provides a method of making a fibre mat having the steps: mixing plant-derived fibres arranged in a fibrous network with a plant-derived material, the plant-derived material being different from the plant-derived fibres; and forming a mat structure from a mixture of the fibrous network and the plant-derived material. In this way, the mat according to the first aspect is manufactured.

Preferably, the step of forming a mat structure comprises the step of applying suction to draw the mixture of the fibrous network and the plant-derived material onto a template for a mat. Typically, the fibrous network holds material elements of the plant-derived material and the mixture of the fibrous network and the plant-derived material are drawn towards a template by a differential pressure created by a suction means. Multiple layers of fibrous network may be drawn towards the template, each layer of fibrous network integrating and interlocking with adjacent layers of the fibrous network.

The method may further have the step of separating a fibrous plant material into the fibrous network of plant- derived fibres. The bast fibres typically break down into a fibrous network when the fibrous plant material is beaten, bashed, milled, hammered or worked by a similar method.

The method may further have the step of working the plant-derived material to break down the plant-derived material. In this way, the plant-derived material may be used in a raw state and processed. The plant-derived material may be processed until the material elements of the plant-derived material are of a suitable length and / or shape. Preferably, the step of working the plant- derived material and the step of mixing are carried out together. Advantageously, the method of making the fibre mat is made more efficient if the plant-derived material is broken down into material elements at the same time as mixing the plant-derived material with the fibrous network. This reduces the manufacturing time and increases the amount the fibrous network and material elements are mixed together. Alternatively, the step of working the plant-derived material and the step of mixing may occur at different times. Different plant materials will require different amounts of processing, depending on their raw state

(water content, brittleness, hardness etc) . Working the plant-derived material at a different time to the step of mixing provides increased controllability of the mixing and working steps. For example, mixing the plant-derived material for too long may break the plant-derived material into material elements, which are too small to lend their advantageous physical properties to the overall fibre mat structure.

Additionally or alternatively, the step of separating the plant-derived fibres occurs at the same time as the step of working the plant-derived material. In this way, the method of making the fibre mat may be sped up. Preferably, the step of separating the plant-derived fibres and the step of working the plant-derived material are the same process step. For example, the same machinery for working the plant-derived material is used to separate the plant-derived fibres at the same time. Preferably the steps of working and separating are carried out with a mill. More preferably, the mill is a hammer-mill. Alternatively, the step of separating the plant-derived fibres occurs at a different time from the step of working the plant-derived material. Again separating the method steps may provide further control over the extent that the plant-derived fibres and the plant-derived material are respectively separated and worked. Preferably, the method further comprises the step of mixing a binder component with the mixture of the fibrous network and the plant-derived material. More preferably, the binder component is a heat activated and the method further includes the step of heating the mixture of the fibrous network, the plant-derived material and the binder component to an activation temperature such that bonds are established between the fibrous network and the plant-derived material.

Alternatively, the method further comprises the steps of mixing hot water and / or steam with the mixture of the fibrous network and the plant-derived material and drying the mixture of the fibrous network and the plant-derived material. This means that the mixture dries such that the fibrous network has more nodes. Essentially, the fibrous network has an increased number of interlocking fibres. Advantageously, this method does not require a binder component and the percentage of natural, renewable type products in the fibre mat may be increased.

In a third aspect, the invention provides a fibre panel having a fibre mat according to the first aspect; wherein the fibre mat is compressed and heated at a panel-forming pressure and temperature.

In this way, the fibre mat as mentioned previously may be used to form a stiff, panel type structure. Such a panel may have improved structural properties over the fibre mat that make it particularly suitable for interior walls of buildings and / or vehicles.

Typically, fibre panel may be reinforced with a thermosetting plastic material or a thermoplastic material. This means that when the fibre mat is pressed and heated, bonds will form between the plant-derived fibres and plant-derived material, further strengthening the fibre panel.

In a fourth aspect, the present invention provides a method of making a plant fibre panel comprising the method of making a fibre mat according the second aspect; wherein the method further comprises the steps of compressing the fibre mat to a panel-forming pressure; and / or heating the fibre mat to a panel-forming temperature.

Preferably, the panel-forming pressure is between 6 tonnes/m² to 120 tonnes/m². Preferably, the panel-forming temperature is between 100⁰C and 250⁰C. More preferably, the panel-forming temperature is between 150°C and 250°C, e.g. about 200°C.

Preferably, the method further includes the step of moulding the plant fibre panel. As mentioned above, typically, although not necessarily, a thermosetting plastic material or a thermoplastic material is added to the fibre mat. This means that the fibre panel is particularly suitable for moulding into desired shapes. For example, an interior panel of a vehicle may be produced using a fibre panel when pressed and heated on a respective interior vehicle panel mould.

It is to be understood that any of the preferred and/or optional features may be applied separately or in conjunction with any of the aspects of the invention, unless the context demands otherwise. Indeed the present invention includes a combination of each aspect with one or more other aspects. Thus, the invention provides another aspect which includes the combination of any aspect with one or more aspect (s) .

Preferred embodiments of the present invention will now be described with reference to the accompanying drawing, in which Fig. 1 shows a schematic magnified view of a fibre mat according to a first embodiment of the present invention .

Fig. 1 shows a schematic magnified view of a fibre mat according to first embodiment of the present invention. The fibre mat has plant-derived fibres 2 arranged in a fibrous network 1 and a plant-derived material 3 held within the fibrous network 1.

The fibrous network 1 is formed from the plant-derived fibres 2 which interlock at nodes 4. The plant-derived fibres are typically single fibres. The nodes 4 connect the separate plant-derived fibres 2 together and are locations where the separate plant-derived fibres are tangled together or are bonded together by a binder component or other suitable binding mechanism. The plant-derived material 3 comprises material elements which have been cut to a desired length. The material elements are held within the fibrous network 1 by bonds to the plant-derived fibres 2 or being entangled within the fibrous network 1. The material elements are sufficiently entangled / bonded within the fibrous network 1 such that movement of the material elements is limited.

In the first embodiment, flax is the plant-derived fibres 2 and the straw is the plant-derived material 3.

In a second embodiment polyethylene is used as a binder component. The polyethylene forms bonds between the separate plant-derived fibres 2 in the fibrous network 1 and bonds between the plant-derived fibres 2 and the material elements of the plant-derived material 3.

As mentioned above, different plant-derived fibres and different plant-derived material may be used together to achieve different mat structures.

In a third embodiment, cellulose is used with hemp. The hemp is the plant-derived fibres 2 and the cellulose is the plant-derived material 3. Cellulose material elements have good water absorption properties . The fibre mat made from hemp and cellulose has good water absorption properties and is suitable for absorbing liquids and mopping up spillages (e.g. spilt water or oil) . In a fourth embodiment, wheat straw is used with hemp. The hemp is the plant-derived fibres 2 and the wheat straw is the plant-derived material 3. The wheat straw is stiff and is resistant to abrasive forces. The fibre mat made from hemp and straw is suitable for preventing soil erosion. Typically, such a fibre mat is placed, partially buried or completely buried on a soil bank or an area of ground with exposed soil. The fibre mat of the fourth embodiment prevents the soil from being eroded.

In a fifth embodiment, coconut husk fibres are used with hemp. The hemp is the plant-derived fibres 2 and the coconut husk fibre is the plant-derived material 3. Coconut husk fibre is stiff (but flexible) compared to hemp fibre. Furthermore, coconut husk fibre is resiliently deformable. The fibre mat made from hemp and coconut husk fibre provides a springy mat, which returns to its original shape after being deformed. Typically, such a fibre mat is used for thermal and / or acoustic insulation because the resiliently deformable nature of the fibre mat traps air within the mat. This means the mat is lightweight and has good thermal and acoustic insulating properties.

In a sixth embodiment, there is a fibre panel having a fibre mat according to the second embodiment except the binder component is polypropylene. The fibre mat is compressed and heated and the polypropylene melts and forms bonds between the separate plant-derived fibres 2 in the fibrous network 1 and bonds between the plant- derived fibres 2 and the material elements of the plant- derived material 3. The polypropylene reinforces the fibre mat and after the heating and pressing of the fibre mat, a fibre panel is produced. The fibre panel is a highly reinforced composite material .

The method of manufacture of the fibre mat according to the first embodiment will now be described. The second to fifth embodiments are manufactured in a similar way.

The flax stems are laid in swaths and after about ten days on the field are combine harvested with a typical combine harvester machine. Hereafter the flax lies in a straw run/swath on the field and is retted. The retting process may be observed by noting a change in colour on the straw. The desired degree of retting has been achieved when the colour on the straw/fibres changes to light grey. It may be necessary to turn the swath in order to ensure a uniform retting.

The retting process is monitored and samples are taken daily in order to ascertain how far the retting process has advanced.

When the desired change of colour has appeared, the straw is gathered by pressing into bales, for example round bales. Normally baling of the flax takes place when there is a 15wt% water content in the flax.

The bales are transported to the factory where they are dried to a 12wt% water content. After drying, the bale is unrolled/cut up. The flax straw is fed into a hammer mill where the scutching takes place. This separates the flax straw into a fibrous network 1.

At the same time, the plant-derived material, in this case, wheat straw, is fed into the hammer mill. The hammer mill works the wheat straw and breaks the wheat straw down into smaller components, referred to herein as material elements. Typically the material elements are 15 mm long, but the size range may be 10-15 mm. The hammer mill also mixes the material elements of the wheat straw into the fibrous network.

The mixture of the flax straw fibrous network and wheat straw material elements is then transported to the fibre mat manufacturing plant where a dry-forming process takes place .

The dry-forming process uses a former head placed above a vacuum box. Between the former head and the vacuum box, there is a template or former wire on which the mixture is deposited. The vacuum box creates a differential pressure between the former head and the former wires. The mixture is held on the former wires by virtue of the differential pressure.

The fibre mat manufacturing plant is adjusted to forming a fibre mat of a desired thickness. This is regulated by means of the speed at which the fibrous network and plant-derived material mixture is fed from the former head. At the same time the advancing speed on the wire is regulated. During the dry-forming process, where the fibres are drawn onto the former wires, 2-3wt% of polyethylene is added.

The fibre mat is then placed in an oven at 145°C. After heating the fibre mat, it is packed and cut into shape.

The method of making the fibre panel according to the sixth embodiment will now be described.

The fibre mat is made according to the method of manufacturing the fibre mat of the first embodiment as mentioned above, except that a different binder component and amount of binder component are used.

Typically a fibre panel is made using a fibre mat having a weight of 300 g/m².

During the manufacture of the mat, a plant-fibre compatilizer is sprayed on. That is, a chemical component which modifies the surface of the plant-derived fibres. The plant-compatilizer is isocyanate (about 1- 2wt%) in order to ensure the hydrophobic fibres obtain a surface which is compatible with the binder component such as the above mentioned binder components in the fibre panel. It is possible at this stage also (or alternatively) to add a hydrophilic agent, a hydrophobic agent and/or a fire retarding agent.

As mentioned above, the sixth embodiment incorporates polypropylene as a binder component. Approximately 50wt% of polypropylene is added to the mixture of the plant- derived fibres and plant-derived material immediately before the fibre mat is formed on the template former wires. Additionally, a coconut husk component may be added, in order to promote stiffness and resilience to the finished product.

Thereafter, the mixture of plant-derived fibres, plant- derived material and polypropylene is heated to an activation temperature of 200⁰C and compressed at a panel-forming pressure of 150 Tonnes/m². This forms a fibre panel according to the sixth embodiment.

The fibre panels are be cut and formed in to mouldable fibre panel blanks. These are typically flat panels which may be conveniently transported.

Since the fibre panels contain a thermoplastic, i.e. polypropylene, the fibre panel blanks can be heated and moulded into a suitable shape after the manufacturing process the fibre panel. The fibre panel blanks may be moulded for interior panels of vehicles or buildings.

The present invention has been described with reference to preferred embodiments. 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 invention.

Claims

1. A fibre mat having plant-derived fibres arranged in a fibrous network; ^• and a plant-derived material, different from the plant- derived fibres, held within the fibrous network, to provide a mat structure.

2. A mat according to claim 1 wherein the plant-derived fibres have an average length between 0.1mm and 150mm.

3. A mat according to claims 1 or 2 wherein, the plant- derived material comprises material elements having an average stiffness greater than that of the plant-derived fibres .

4. A mat according to claim 3 wherein the plant-derived material elements have an average length between 0.1mm and 150mm.

5. A mat according to any one of the preceding claims wherein the fibrous network comprises an array of linked fibres, said fibres each being substantially single fibres.

6. A mat according to any one of the preceding claims, wherein the plant-derived material is one or more selected from the following: wheat straw, oat straw, rye straw, barley straw, grass straw, rice straw, bean straw, oilseed rape straw, cellulose, paper, cardboard, coconut husk or other similar plant-derived material.

7. A mat according any one of the preceding claims wherein the plant-derived fibres are one or more selected from the following: hemp, jute, flax, ramie, kenaf, rattan, soya bean fibre, okra fibre, vine fibre, peat fibre, kapok fibre, banana fibre or other similar types of bast fibre material.

8. A mat according to any of the preceding claims further having a binder component.

9. A mat according to claim 8 wherein in the binder component is a synthetic binder or a natural binder.

10. A mat according to claim 9 wherein the binder component is heat activated.

11. A mat according to claim 8 wherein the binder component is selected from one or more of: polypropylene, polylactic acid, polyethylene, polyester, vinyl, polyvinyl acetate or other similar binding material.

12. A mat according to any of the preceding claims wherein the percentage weight of the plant-derived fibres is in the range 5wt% to 95wt%.

13. A mat according to any of the preceding claims wherein the percentage weight of the plant-derived material is in the range 5wt% to 95wt%.

14. A mat according to claims 8 to 11 wherein the percentage weight of the binder component is in the range lwt% to 50wt%.

15. A mat according to any of the preceding claims wherein the mat has at least two layers, the at least two layers having different percentage weights of the plant- derived material and / or different percentage weights of the plant-derived fibres.

16. A mat according claim 15 wherein one layer of the at least two layers has a different plant-derived material and/or different plant-derived fibre to another layer of the at least two layers.

17. A mat according to any of the preceding claims wherein a physical property of the plant-derived material is a different quantity with respect to the same physical property of the plant-derived fibre.

18. A mat according to claim 17 wherein the physical property may be any one of the following: thermal conductivity, density, tensile strength or elastic modulus .

19. A mat according to claim 18 wherein the elastic modulus of the plant-derived material is greater than the elastic modulus of the plant-derived fibres.

20. A mat according to any of the preceding claims wherein the mat has a thickness between 2mm and 300mm.

21. A mat according to any of the preceding claims wherein the mat has a weight in the range of 30 and 8000g/m².

22. A method of making a fibre mat having the steps: mixing plant-derived fibres arranged in a fibrous network with a plant-derived material, the plant-derived material being different from the plant-derived fibres; and; forming a mat structure from a mixture of the fibrous network and the plant-derived material.

23. A method of making a fibre mat according to claim 22 wherein the step of forming a mat structure comprises the step of applying suction to draw the mixture of the fibrous network and the plant-derived material onto a template for a mat.

24. A method according to claims 22 or 23, wherein the method further has the step of separating a fibrous plant material into the fibrous network of plant-derived fibres

25. A method according to any of claims 22 to 24, wherein the method further has the step of working the plant-derived material to break down the plant-derived material.

26. A method of making a fibre mat according to claim 25 wherein the step of working the plant-derived material and the step of mixing are carried out together.

27. A method according to claim 25 wherein the step of working the plant-derived material and the step of mixing occur at different times.

28. A method according to claim 25, in so far as claim 25 is dependent on claim 24, wherein the step of separating the plant-derived fibres occurs at the same time as the step of working the plant-derived material.

29. A method according to claim 28 wherein the step of separating the plant-derived fibres and the step of working the plant-derived material are the same process step .

30. A method according to claim 25, in so far as claim 25 is dependent on claim 24, wherein the step of separating the plant-derived fibres occurs at a different time from the step of working the plant-derived material.

31. A method according to any one of claims 22 to 29, wherein the plant-derived fibres and the plant-derived material are mixed by a mill, such as a hammer mill.

32. A method according to claims 22 to 31, wherein the method further comprises the step of mixing a binder component with the mixture of the fibrous network and the plant-derivable material.

33. A method according to claim 32 wherein the binder component is heat activated and the method further includes the step of heating the mixture of the fibrous network and the plant-derivable material and the binder component to an activation temperature such that bonds are established between the fibrous network and the plant-derivable material.

34. A method according to claims 22 to 31 wherein the method further comprises the steps of mixing hot water and / or steam with the mixture of the fibrous network and the plant-derived material and drying the mixture of the fibrous network and the plant-derived material.

35. A fibre panel having a fibre mat according to claims 1 to 19; wherein the fibre mat is compressed and heated at a panel-forming pressure and temperature.

36. A fibre panel according to claim 35 wherein the fibre panel is reinforced with a thermosetting plastic material or a thermoplastic material .

37. A method of making a plant fibre panel comprising the method of making a fibre mat according to claims 22 to 34; wherein the method further comprises the steps of compressing the fibre mat to a panel-forming pressure; and / or heating the fibre mat to a panel-forming temperature.

38. A method of making a plant fibre panel according to claim 37 wherein the panel-forming pressure is between 6 tonnes/m² to 120 tonnes/m².

39. A method of making a plant fibre panel according to claims 37 or 38 wherein the panel-forming temperature is between 100⁰C and 250⁰C.

40. A method of making a plant fibre panel according to claims 35 to 39 wherein the method further includes the step of moulding the plant fibre panel.