AU2015201455B2

AU2015201455B2 - Method of manufacturing a timber composite

Info

Publication number: AU2015201455B2
Application number: AU2015201455A
Authority: AU
Inventors: Peter Chan
Original assignee: Unilin BV
Current assignee: Unilin BV
Priority date: 2014-04-11
Filing date: 2015-03-19
Publication date: 2018-12-06
Anticipated expiration: 2035-03-19
Also published as: AU2015201455A1

Abstract

A method of manufacturing a timber composite is disclosed. The method comprises the steps of applying adhesive to one or more timber layers, applying pressure to the one or more timber layers, and heating the timber layers. The adhesive penetrates into the one or more timber layers and cures to form the timber composite. One or more spacers may be positioned between the timber layers. 62895301 (GHMatters) P97282.AU BENB 110 Cut timber log Stain timber layersI Apply adhesive Arrange layers -122 Apply heat Cool timber Release pressure

Description

METHOD OF MANUFACTURING A TIMBER COMPOSITE

TECHNICAL FIELD

Disclosed herein is a timber composite and a method of manufacturing a timber composite. In particular, the timber composite may be suitable for, but not limited to, flooring or other surface applications.

BACKGROUND ART

Composite timber is used as a construction and/or decorative material. However, known timber composite has low density and low strength, which can limit the viable applications for such timber.

Plywood is one example of a composite timber that is used as a construction material. To form plywood, several layers of wood (e.g. having a thickness of 1.6mm to 2mm) are stacked such the direction of the grains of the layers alternates. Adhesive is applied to the surfaces of the layers of wood such that they are bonded to one another.

For decorative reasons, some timber is produced with an embossed effect, where the surface of the timber is textured according to the grain of the timber. Such an effect is produced by scraping off portions of the surface of the timber that are low density, either manually or by a machine. This results in the surface of the timber having a rugged “wire-drawn” or embossed appearance corresponding to the grain of the timber. The timber used in such a process is low density, because only low density timber (e.g. pine, elm, oak, etc.) is suitable for scraping. However, such timber, due to its low density, may be easily damaged (e.g. forming a concave shape) or may wear quickly from daily usage, and thus may not be suitable for a long term applications.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

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SUMMARY

Disclosed herein is a method of manufacturing a timber composite. The method comprises the steps of cutting one or more timber pieces to form a plurality of timber layers, applying adhesive to the plurality of timber layers, arranging the plurality of timer layers in a stack, applying pressure to the timber layers, and heating the timber layers, such that the adhesive penetrates into the one or more timber layers and cures to form the timber composite, wherein the timber layers are arranged in the stack in their original order and orientation in the timber piece from which they are cut, and wherein the adhesive is a thermosetting adhesive.

The penetration of the adhesive into the timer layers differs, for example, from plywood whereby the adhesive remains on the surface of the plywood layers. It has been found that, using a suitable adhesive, then applying an appropriate amount of heat and pressure to the timber layers may allow the adhesive to penetrate into and throughout the fibres of the timber layers. Curing the resultant penetrated adhesive within the timber layers may result in a denser and stronger composite timber product.

In one embodiment the penetration of the adhesive may be such that it is distributed generally evenly throughout the interstices and pores of the fibres of the one or more timber layers.

The timber layers are arranged in the stack in their original order in the timber piece from which they are cut such that a natural grain appearance of the timber piece is maintained. This may be desirable, for example, when the timber composite is to be used for decorative purposes (i.e. where the appearance of the grain is important to the use of the timber composite).

In one embodiment the cutting may be one of rotary peeling, slicing or saw cutting.

In one embodiment each timber layer may have a thickness of 0.2mm to 1mm.

In one embodiment the timber may have a moisture content of 8% to 12% prior to the application of pressure and heat. The timber may be dried prior to performing the method in order to arrive at this moisture content.

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In one embodiment the adhesive applied to the timber layers may be of a type that cures at high temperatures. In this respect, the adhesive may not cure until it has fully penetrated the timber layers.

In one embodiment the adhesive may be applied to one or both sides of the or each timber layer. The adhesive may be a melamine resin such as a melamine formaldehyde; and or a resin based on one or more of polyolefins, polyamides, polyurethane, polyvinyl acetal, urea, asphalt, etc. The adhesive may contain formaldehyde, sodium hydroxide, urea, melamine, polyvinyl alcohol, polyolefine, polyamide adhesive, polyurethane or asphalt

In one embodiment the pressure applied to the timber may be between 2000 kPa and 10,000 kPa, for example 0.1 MPa and 30 MPa, such as 2 MPa to 10 MPa.

In one embodiment the timber may be heated to a maximum temperature of between 50°C and 250°C, such as 100°C and 200°C.

In one embodiment the timber may be gradually heated to allow the adhesive to fully penetrate the one or more timber layers. For example, in some cases when the timber is heated too quickly the adhesive may cure prior to fully penetrating the timber layers.

In one embodiment, when the step of heating the timber is performed, the temperature of the timber may be increased from room temperature to a maximum temperature (e.g. being in the range of 50°C to 100°C) gradually over a period of 20 to 60 minutes. Again, the gradual increase in temperature may allow the adhesive to fully penetrate (and be distributed generally evenly throughout) the one or more timber layers, penetrating the interstices and pores of the fibres.

In one embodiment the method may further comprise the steps of cooling the timber and releasing the pressure. In one embodiment the pressure may only be released once the temperature of the timber has returned to approximately room temperature. Delaying the release of the pressure may better allow the adhesive to fully cure.

In one embodiment the method may further comprise the step of positioning a spacer between two timber layers. When a spacer is located between two timber layers, it may help to reduce or inhibit the escape of moisture from the timber layers. When moisture is trapped

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2015201455 07 Nov 2018 in the timber, the timber may soften, which in turn may facilitate compression of the timber.

It may also provide varying shrinkage of the spring wood and summer wood in the timber.

When the adhesive cures it may hold the timber in this shape such that the resulting timber composite has raised portions of summer wood (i.e. such that the texture of the grain structure is enhanced).

The spacer may be positioned such that a stack of timber layers is formed on either side of the spacer. Each stack of layers may be cut from a different timber piece.

In one embodiment each stack of layers on either side of the spacer may be arranged in the original order from which they are produced from the timber piece(s), such that a natural grain of each stack may be maintained. This may be desirable in decorative applications where the timber composite will be visibly used (e.g. flooring).

In one embodiment the spacer may be a sheet of cardboard, plastic or soft metal.

In one embodiment the method may further comprise the step of applying a stain to the one or more timber layers prior to applying an adhesive to the one or more timber layers. The stain may be applied so as to penetrate into and be distributed evenly within the one or more timber layers.

When the timber layers are, for example, thinly cut the stain may more easily penetrate into and be evenly distributed throughout each timber layer, including into pores and interstices between fibres (e.g. compared to a block or panel of timber). In this way, when the timber layers are formed into a timber composite, the timber composite may have an even colouring (i.e. stain) throughout its interior. This even colouring (or staining) throughout the timber composite may not be achievable, or may be difficult to achieve, with a traditional block or panel of timber where the stain can only be applied to the outer surface of the block of timber and may not penetrate into its interior.

An even distribution of stain may be desirable, for example, when the timber composite is used in applications in which it may be subject to wear. Without a uniform distribution of stain (i.e. when stain does not penetrate into the timber), wearing of the surface of the timber will cause the colour of the timber to fade (i.e. because the areas that are more deeply stained

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2015201455 07 Nov 2018 on the surface are worn away). On the other hand, by staining the layers of timber composite such that the stain is generally uniformly distributed throughout the timber, removal of the surface of the timber composite (e.g. through wear) may not affect the appearance of the timber composite.

Also disclosed herein is a method of manufacturing a timber composite. The method comprises the steps of applying adhesive to a plurality of timber layers, arranging the timber layers in a stack, and positioning a spacer between two of the timber layers in the stack. The method further comprises applying pressure to the stack of timber layers and heating the stack of timber layers, such that the adhesive penetrates into the timber layers and cures to form the timber composite.

The method may be as otherwise defined above.

Also disclosed herein is a timber composite manufactured using the methods as defined above.

Also disclosed herein is a timber composite comprising timber layers and an adhesive matrix. At least one surface of the timber composite has raised portions of summer wood and depressed portions of spring wood.

Also disclosed herein is a decorative panel comprising a substrate material and a decorative top layer, wherein the top layer is formed by a timber composite comprising a plurality of timber layers obtained from a same timber piece and penetrated with a cured thermosetting adhesive, wherein said timber layers are available in said top layer in their original order in which they were cut from said timber piece.

In an embodiment, for said timber composite use may be made of a timber composite as set forth above.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a flow chart illustrating a method of manufacturing a timber composite;

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Figure 2 schematically illustrates an apparatus for manufacturing a timber composite;

Figure 3 is a flow chart illustrating a further method of manufacturing a timber composite; and

Figure 4 schematically illustrates a further apparatus for manufacturing a timber composite.

DETAILED DESCRIPTION

In the following detailed description, reference is made to accompanying drawings which form a part of the detailed description. The illustrative embodiments described in the detailed description, depicted in the drawings and defined in the claims, are not intended to be limiting. Other embodiments may be utilised and other changes may be made without departing from the spirit or scope of the subject matter presented. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings can be arranged, substituted, combined, separated and designed in a wide variety of different configurations, all of which are contemplated in this disclosure.

Referring firstly to Figure 1, the method 110 comprises rotary cutting or slicing a timber billet into timber layers 112. Natural timber can warp due to differential shrinkage of the wood as it dries. This differential shrinkage causes internal stresses (i.e. due to tension) in the timber. When the timber is cut into thin layers, these stresses are reduced. In the illustrated embodiment the timber layers have a thickness of 0.01-1.5 mm. After the timber is cut, the timber layers are in a natural state containing water. The water content of the timber layers can be reduced to l%-20% by natural drying or machine drying, which can result in the produced timber composite (discussed in more detail below) having a higher density.

After the timber is cut into timber layers 112, a stain is applied to each layer 114. Applying the stain 114 to the thin layers of timber means that the stain more easily penetrates into and throughout the timber. In this way, the stain may be distributed throughout the timber such that, when the timber layers are later formed into a composite timber (discussed below), the stain may be evenly distributed throughout the timber composite. This may not

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2015201455 07 Nov 2018 be the case with, for example, a block or panel of timber where the stain is only applied to the external surface, so that the stain is not be able to penetrate into the centre of the block or panel of timber (this may especially be the case with hardwoods).

The method 110 further comprises applying an adhesive 116, of the type that cures at high temperatures, to the surfaces of the timber layers. The adhesive is applied 116 by spray gun to a single surface of each of the timber layers. The adhesive may contain formaldehyde, sodium hydroxide, urea, melamine, polyvinyl alcohol, polyolefine, polyamide adhesive, polyurethane and/or asphalt.

In the illustrated embodiment the adhesive is prepared by mixing evenly 10 parts by weight of formaldehyde, 5 parts by weight of sodium hydroxide, 5 parts by weight of urea, 50 parts by weight of melamine, 5 parts by weight of polyvinyl alcohol, 5 parts by weight of polyolefine, 5 parts by weight of polyamide adhesive, 5 parts by weight of polyurethane, and 10 parts by weight of asphalt in a reaction vessel at a temperature of 80 degrees centigrade. It would be understood by a person skilled in the art that the amounts of each component and the reaction temperature can be varied without departing from the scope of the method as disclosed herein.

The method 110 further comprises arranging the timber layers in a stack 118. The layers are arranged so as to be in their original order in the timber billet, which ensures that the wood grain of one layer matches the grain of its adjacent layers such that the stack retains the appearance of the original timber billet.

The method 110 further comprises applying a pressure of 0.1-30 MPa to the stack of timber layers 120 and heating the stack 122 to a temperature between 50°C and 250°C and typically 100°C to 200°C. The stack is gradually heated from room temperature to this temperature over a period of between 3 minutes and 20 minutes. In other embodiments, the temperature may be increased at a faster or slower rate (i.e. over a shorter or longer period of time).

The heat 122 and pressure 120 causes the adhesive to penetrate into and throughout the fibres of the timber layers including into the interstices and pores between fibres. The

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2015201455 07 Nov 2018 gradual heating of the adhesive provides the adhesive with time to penetrate into the timber. Once the adhesive cures, it holds the timber in shape (i.e. the shape it takes when compressed or pressurised), such that upon release of the pressure it does not return (e.g. bounce back) to its original shape. Thus, the density of the timber composite is higher than the density of the original timber billet (i.e. the non-composite timber). The timber layers are bonded to one another by the curing of the adhesive and form a single piece of high density composite timber. The timber is then allowed to cool and the pressure is released.

Figure 2 schematically illustrates an apparatus 224 used to manufacture a composite wood board, for example, according to the method shown in Figure 1 and described above.

As illustrated, four sheets of timber 226 are stacked on top of one another to form a stack of timber layers 228. Each timber layer 226 has been coated with adhesive by way of spray gun, and has a thickness of 1.5 mm and a water content of 1%. The stack of timber layers 228 is positioned between two steel plates 230 which, in use, apply a pressure of 1-20 MPa to the stack of timber layers 228. Additionally, each steel plate 230 can be gradually heated from room temperature to 100-200°C over a period of 3-20 minutes, which in turn heats the stack of timber layers 228. The heat can be transferred directly from the steel plates 230 to the stack of timber layers 228. This allows the adhesive to penetrate the fibres of the timber and cure, so as to bond the timber layers 226 to one another. The bonding of the timber layers 226 forms a high density composite timber. The pressure applied by the steel plates 230 is then released and the timber composite is allowed to cool.

Referring now to Figure 3 the method 310 is similar to that shown in Figure 1 and described above, but includes some differences. For example, the method 310 further comprises the step of positioning a spacer 332 between two timber layers in the stack. The spacer may be a sheet of cardboard, plastic or soft metal. As set forth above, when the stack of timber layers is pressurized (i.e. compressed) 320 and heated 322, the adhesive permeates (or penetrates) into the fibres of the timber and cures. Additionally, the moisture in the

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2015201455 07 Nov 2018 timber tends to move towards the centre of the stack of timber layers (due to heat being transferred at external surfaces of the stack). When a spacer is positioned between two of the layers it prevents passage of moisture between the layers (i.e. the moisture is essentially trapped by the spacer). As the temperature increase 322 the moisture forms steam, which softens the timber layers located either side of the spacer. The spring wood in the timber layers shrinks to a greater extent than the summer wood in the timber layers. When the adhesive cures (as discussed above), it holds the timber in this shape (i.e. the spring wood having shrunk to a greater extent than the summer wood), such that upon release of the pressure the timber does not return (e.g. bounce back) to its original shape. Hence, the resultant timber has raised portions of summer wood and depressed portions of spring wood. This produces an embossed appearance that accentuates the grain structure of the timber. Due to the depth of the grain, this embossed (wood grain) appearance can remain even after polishing the timber composite.

When the timber layers are cut 312 from a single piece of timber (e.g. billet - as is the case in this embodiment), the timber layers can be stacked 318 in the same order and orientation as they were in before the billet was cut (i.e. so as to essentially re-form the original piece of timber). By doing so, the produced timber composite will have the same (or similar) natural wood grain as the original timber piece and having a wire-drawing and embossed effect.

Fig. 4 schematically illustrates an apparatus 424 for simultaneously pressing multiple composite timber boards 426 according to, for example, the method 310 shown in Fig. 3 and described above.

Two stacks 428 of timber layers 426, each consisting of timber layers 426 of 1.2 mm thickness, are positioned adjacent to one another (i.e. one on top of the other). A spacer in the form of a plastic sheet 434 is positioned between the adjacent stacks of timber layers 428. In the illustrated embodiment each timber layer 426 has a water content of 20%. The apparatus 424 comprises two steel plates 430, which the stacks of timber layers 428 are positioned between. The steel plates 430 are capable of applying pressure of 1-20 MPa to the stacked wood slice assemblies 428. Whilst not shown, the apparatus 424 comprises a

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2015201455 07 Nov 2018 heater also capable of directly heating the two steel plate to 100-200°C, over a period of 3-20 minutes. In use, this heat is transferred from the steel plates 430 to the timber layers 426. Two or more composite timber boards are produced after the release of the pressure and then the removal of the plastic sheet spacer 434. In this respect, the apparatus 424 allows more than one composite timber board to be produced in one pressing and heating operation. Thus apparatus 424 may provide an efficient way to produce multiple timber composite boards, which may in turn provide energy savings. Further, and as set forth above with regards to the method 310 shown in Figure 3, the apparatus 424 may allow the production or manufacture of timber composite having an embossed (i.e. raised grain) appearance.

In the illustrated embodiment, two stacks of timber layers 428 are shown, each having four timber layers 426. In alternative embodiments, there may be three, four, five, etc. stacks of timber layers (having spacers therebetween) each having one, two, three, five, six, etc. timber layers. In such embodiments, any timber composite produced from stacks located between two spacers would have an embossed appearance on both (e.g. upper and lower) sides. It would be understood by a person skilled in the art that the number and the thickness of the timber layers in each stack of timber layers can be varied to vary qualities of the timber composite that is produced by the apparatus.

Some embodiments of the method have been described above, but the method may be embodied in many other forms. Modifications and improvements can be made by a person skilled in the art without departing from the essence of the present method. Such modifications and improvements fall within the scope of the present method.

For example, the spacer can alternatively be paper or card board, plastic film, soft metal (e.g., aluminium or copper) etc. Alternatively, the spacer may be formed from a combination of these materials.

Further, the timber layer may have a thickness of 0.01 to 100mm. Alternatively, the timber layer may have a thickness between 0.1 to 3 mm. The timber composite produced from the methods and apparatus set forth above may have a higher density if the thickness of the wood slices is alternatively between 0.2 to 1 mm. Additionally, the cutting method can

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2015201455 07 Nov 2018 be rotary peel, slicing or saw cutting.

The moisture content of the timber layers may be 1% to 60%. Alternatively the moisture content may be 5% to 30%. Alternatively the moisture content may be 8% to 12%.

The pressure applied to the timber layers or stacks may be 0.01 MPa to 30MPa. Alternatively the pressure may be 0.05MPa to 20MPa. Alternatively the pressure may be 2MPa to lOMPa.

The maximum temperature applied to the timber layers or stacks may be 10°C to 400°C. Alternatively the temperature may be 50°C to 300°C. Alternatively the temperature may be 100°C to 200°C.

As discussed above, the number of timber layers in each stack can be varied as needed. For example, there may be one, two, three, four, five, etc. layers in each stack of timber layers. Additionally, each stack of timber layers does not have to have the same number of timber layers as other stacks.

Multiple spacers can be used be used between stacks of timber layers. For example, when there are three stacks of timber layers, two spacers may be positioned between the stacks.

The surfaces of the timber layers can be coated with adhesive by, for example, using one or more of the following methods:

1. The adhesive can be sprayed to a surface of a timber layer by using a spray gun so that the adhesive can be applied to the surface of the timber layer evenly.

2. The adhesive can be applied to a surface of a timber layer by using a coating roller, so that the adhesive can be applied to the surface of the timber layer evenly.

3. The timber layer can be dipped into adhesive so that the fibres in the timber layer can naturally absorb the adhesive, thus coating the surface of the timber layer with adhesive.

4. Providing the adhesive in a sealable container, dipping a timber layer into the adhesive, sealing the container, pressurizing the interior of the container. This may force the adhesive to permeate into the wood fibres of the timber layer more sufficiently under pressure.

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5. Applying adhesive to both sides of a carrier, and placing the carrier between two wood slices so that the adhesive can permeate into the wood fibres of the wood slices 1 sufficiently.

The carrier can be, for example, paper or nonwoven cloth.

EXAMPLES

EXAMPLE 1

Six timber layers of 0.6 mm thickness were sliced from a timber billet. The timber layers were kiln dried in order to reduce their moisture content to approximately 10%. Adhesive was then sprayed on to both sides of the timber layers. Following this, the timber layers were again kiln dried to a moisture content of approximately 10%.

The six timber layers were then arranged in a stack according to the order they were sliced from the timber billet. This stack was placed into a pressing machine, which was used to apply 7MPa of pressure to the stack. The temperature was increased from 20°C to 200°C over a 60 minute period and then held at 200°C for 20 minutes. Following this, the temperature was decreased from 200°C to 20°C over a period of 45 minutes.

The pressure was then released from the stack of timber layers, which were formed into a timber composite board having smooth upper and lower surfaces.

EXAMPLE 2

Twelve timber layers of 0.6mm thickness were sliced from a timber billet. The timber layers were kiln dried in order to reduce their moisture content to approximately 10%. Adhesive was then sprayed on to both sides of the timber layers. Following this, the timber layers were again kiln dried to a moisture content of approximately 10%.

The twelve timber layers were then arranged in two stacks, each stack having six timber layers stacked according to the order they were sliced from the timber billet. The stacks were placed into a pressing machine and a plastic film spacer was placed between the two stacks of timber layers. Using the press, a pressure of 7MPa was applied to the stacks.

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The temperature was increased from 20°C to 200°C over a 60 minute period, and then held at

200°C for 20 minutes. Following this, the temperature was reduced from 200°C to 20°C over a period of 45 minutes.

The pressure was then released from the stacks of timber layers and the plastic film was removed. Each stack was formed into a timber composite board having one surface with a raised grain or embossed appearance.

EXAMPLE 3

The timber was sliced into a series of 0.5 mm thick veneer. The veneer was dried so as to reduce the veneer moisture content to 12% by weight.

Formaldehyde melamine adhesive (200g/m²) was sprayed onto the veneer, then the veneer was dried again to a moisture content of 12% by weight.

The veneer was then stacked according the original order of slicing.

Pressure (95 kg/cm²) then heat were applied to the stack. The temperature was raised from room temperature to 180°C. When the adhesive in the stack was fully cured, the temperature was reduced back to room temperature.

EXAMPLE 4

The veneer was then stacked in two separate stacks according the original order of slicing. The two stacks were separated by a plastic film. Use of the plastic film allowed an embossed look to be achieved.

Pressure (95 kg/cm²) then heat was applied to the stack. The temperature was raised

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2015201455 07 Nov 2018 from room temperature to 180°C. When the adhesive in the stack was fully cured, the temperature was reduced back to room temperature.

In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the timber composite and its method of manufacture.

Claims

1. A method of manufacturing a timber composite, the method comprising the steps of:

cutting one or more timber pieces to form a plurality of timber layers;

applying adhesive to the plurality of timber layers;

arranging the plurality of timer layers in a stack;

applying pressure to the timber layers; and heating the timber layers, such that the adhesive penetrates into the one or more timber layers and cures to form the timber composite, wherein the timber layers are arranged in the stack in their original order and orientation in the timber piece from which they are cut, and wherein the adhesive is a thermosetting adhesive.

2. A method as claimed in claim 1 wherein the adhesive penetrates such that it is distributed generally evenly throughout the one or more timber layers.

3. A method as claimed in claim 1 or 2 wherein the cutting is one of rotary peeling, slicing or saw cutting.

4. A method as claimed in any one of the preceding claims wherein each timber layer has a thickness of 0.2 mm to 1 mm.

5. A method as claimed in any one of the preceding claims wherein the timber has a moisture content of 8% to 12% prior to the application of pressure and heat.

6. A method as claimed in any one of the preceding claims wherein the adhesive applied to the timber layers is of a type that cures at high temperatures.

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7. A method of claim any one of the preceding claims, wherein the adhesive contains formaldehyde, sodium hydroxide, urea, melamine, polyvinyl alcohol, polyolefine, polyamide adhesive, polyurethane or asphalt.

8. A method as claimed in any one of the preceding claims wherein the adhesive is based on melamineformaldehyde, ureumformaldehyde, meamine-ureuformaldehyde or phenolformaldehyde.

9. A method as claimed in any one of the preceding claims wherein the pressure applied to the timber is between 0.1 MPa and 30 MPa.

10. A method as claimed in any one of the preceding claims wherein the pressure applied to the timber is between 2 MPa and 10 MPa.

11. The method of any one of the preceding claims, wherein the timber is heated to a maximum temperature of between 50°C and 250°C.

12. A method as claimed in any one of the preceding claims wherein the timber is heated to a maximum temperature of between 100°C and 200°C.

13. A method as claimed in any one of the preceding claims wherein the timber is gradually heated to allow the adhesive to fully penetrate the one or more timber layers.

14. A method as claimed in any one of the preceding claims wherein, when the step of heating the timber is performed, the temperature of the timber is increased from room temperature to a maximum temperature gradually over a period of 20 to 60 minutes.

15. A method as claimed in any one of the preceding claims further comprising the steps of cooling the timber and releasing the pressure, wherein the pressure is only released once the temperature of the timber has returned to approximately room temperature.

16. A method as claimed in any one of the preceding claims further comprising the step of positioning a spacer between two timber layers.

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17. A method as claimed in claim 16 wherein the adhesive is applied to a plurality of timber layers, the spacer positioned such that a stack of timber layers is formed on either side of the spacer.

18. A method as claimed in claim 17 wherein each stack of layers is cut from a different timber piece.

19. A method as claimed in claim 17 or 18 wherein each stack of layers on either side of the spacer is arranged in the original order from which they are produced from the timber piece(s), such that a natural grain of each stack is maintained.

20. A method as claimed in any one of the claims 16 to 19 wherein the spacer is a sheet of cardboard, plastic or soft metal.

21. A method as claimed in any one of the preceding claims, further comprising the step of applying a stain to the one or more timber layers prior to applying an adhesive to the one or more timber layers.

22. A method as claimed in claim 21 wherein the stain is applied so as to penetrate into and be distributed evenly throughout the one or more timber layers.

23. The method of any one of the preceding claims, wherein a high density timber composite is obtained where the density of the timber composite is increased compared to the timber pieces or timber layers.

24. A timber composite comprising timber layers and an adhesive matrix, at least one surface of the timber composite having raised portions of summer wood and depressed portions of spring wood.

25. A decorative panel comprising a substrate material and a decorative top layer, wherein the top layer is formed by a timber composite comprising a plurality of timber layers obtained from a same timber piece and penetrated with a cured thermosetting adhesive, wherein said timber layers are available in said top layer in their original order in which they were cut from said timber piece.

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26. The decorative panel of claim 25, wherein for said timber composite use is made of a timber composite in accordance with claim 24.

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