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Title:
LAMINATED BOARD AND METHOD OF MAKING LAMINATED BOARD
Document Type and Number:
WIPO Patent Application WO/2005/021256
Kind Code:
A1
Abstract:
A laminate (10) has at least one of its layers (14) of, or including, bamboo, bonded to at least one wood layer (12). The laminate (10) can be arranged in multiple layers with the fibre direction perpendicular or sometimes parallel to other laminates.

Inventors:
SOEPANDI HARSUDI (ID)
Application Number:
PCT/AU2004/001155
Publication Date:
March 10, 2005
Filing Date:
August 27, 2004
Export Citation:
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Assignee:
NGN AUSTRALIA PTY LTD (AU)
SOEPANDI HARSUDI (ID)
International Classes:
B27D1/00; B32B5/08; B32B7/02; B32B7/03; B32B9/04; B32B21/13; B32B21/14; E04C2/12; E04C2/16; E04F13/10; E04F15/04; E04G9/04; (IPC1-7): B32B21/13; B32B21/14; B27D1/00
Domestic Patent References:
WO1996009921A11996-04-04
Foreign References:
GB2234935A1991-02-20
US4810551A1989-03-07
GB2292336A1996-02-21
AU6059994A1995-11-02
Other References:
PATENT ABSTRACTS OF JAPAN
PATENT ABSTRACTS OF JAPAN
DATABASE WPI Derwent World Patents Index; Class A32, AN 1997-259653
DATABASE WPI Derwent World Patents Index; Class A92, AN 2001-308945
Attorney, Agent or Firm:
Holt, Bernard Michael (Level 7 1 Market Stree, Sydney NSW 2000, AU)
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Claims:
CLAIMS
1. A laminated board including: a first layer of wood ; and a second layer which includes bamboo, the second layer being bonded to the first layer.
2. A board as claimed in claim 1, further including two said first layers, wherein said second layer is sandwiched between said first layers.
3. A board as claimed in claim 2, wherein the first layer and two second layers together constitute a construction element layer, the laminated board further including two cover layers, wherein the construction element layer is sandwiched between the cover layers.
4. A board as claimed in claim 2, wherein the wood of each first layer has a wood grain oriented in a wood grain direction and the bamboo of the second layer has a bamboo grain oriented in a bamboo grain direction, said wood grain directions and bamboo grain direction being substantially parallel to one another so as to all be oriented in a construction element grain direction.
5. A board as claimed in claim 4, further including a plurality of construction element layers laminated to one another and sandwiched between said cover layers, wherein the construction element grain direction of at least one of said construction element layers is a first direction, and the construction element grain direction of the remainder of said construction element layers is a second direction perpendicular to the first direction.
6. A board as claimed in claim 5, further including a centre construction element layer and two further construction element layers sandwiching the centre layer between them, wherein the construction element grain direction of said centre layer is one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.
7. A board as claimed in claim 5, further including a centre construction element layer and four further construction element layers, a first two of said further layers sandwiching said centre layer between them, and the remaining two said further layers sandwiching said first two further layers and the centre layer between them wherein the construction element grain direction of the centre layer is one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.
8. A board as claimed in claim 5, further including two centre construction element layers laminated to each other and two further construction element layers sandwiching said two centre layers between them, wherein the construction element grain direction of each centre element layer is the same one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.
9. A board as claimed in claim 5, further including two centre construction element layers laminated to each other and four further construction element layers, a first two of said further layers sandwiching said centre layers between them, and the remaining two of said further layers sandwiching the first two further layers and the centre layers between them, wherein the construction element grain direction of each centre layer is the same one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.
10. A board as claimed in claim 5, further including three centre construction element layers laminated to one another and four further construction element layers, a first two of said further layers sandwiching said centre layers between them, and the remaining two of said further layers sandwiching the first two further layers and the centre layers between them, wherein the construction element grain direction of each centre layer is the same one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.
11. A board as claimed in claim 5, further including two centre construction element layers laminated to each other and six further construction element layers, a first two of said further layers sandwiching said centre layers between them, a second two of said further layers sandwiching the first further layers and the centre layers between them, and the remaining two of said further layers sandwiching the first two, and second two, of said further layers and the centre layers between them, wherein the construction element grain direction of each centre layer is the same one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.
12. A board as claimed in claim 5, further including a centre construction element layer, a pair of additional layers sandwiching the centre construction element layer between them, each additional layer including bamboo, a pair of further additional layers of wood sandwiching the centre construction element layer and additional layers between them, and a pair of cover layers sandwiching the centre construction element layer and all of said additional layers between them.
13. A board as claimed in claim 12, wherein the wood of one of said further additional layers has a wood grain oriented in a wood grain direction which is perpendicular to the construction element grain direction of the centre construction element layer.
14. A board as claimed in claim 1, further including two said second layers, wherein said first layer is sandwiched between said second layers.
15. A board as claimed in claim 1, wherein the first layer itself includes layers of wood, so as to constitute a laminated wood layer.
16. A board as claimed in claim 1, further including two veneer wood layers sandwiching the first and second layers between them.
17. A board as claimed in claim 16, further including two cover layers sandwiching the first and second layers and veneer wood layers between them, wherein each cover layer is a veneer cover layer of wood.
18. A board as claimed in claim 17, wherein the wood of each of the laminated wood layer, the veneer wood layers and the veneer cover layers has a wood grain oriented in a respective wood grain direction and the bamboo of each of the second layers has a bamboo grain oriented in a respective bamboo grain direction, wherein the wood grain direction of the first layer is one direction, and the wood grain direction of each of the wood veneer layers, and the bamboo grain direction of each of the second layers, is another direction perpendicular to said one direction.
19. A board as claimed in any one of claims 118, wherein all of the layers are bonded one to another.
20. A board as claimed in claim 18, wherein each cover layer is of wood, or a combination of melamine or coconut husk fibres and adhesive, phenolic coating, or coatings of the type sold under the brand names Casco and Dna.
21. A method of making a laminated board, the method including the steps of : superposing at least one first layer on at least one second layer, wherein each second layer consists of a sheet which includes bamboo; and bonding the layers one to another.
22. A method of making a laminated board as claimed in claim 21 wherein each first layer is of wood.
23. A method of making a laminated board as claimed in claim 21 wherein the step of providing each second layer includes the steps of : cutting portions from a bamboo stem; and arranging the portions substantially in a sheet configuration to form at least part of the second layer.
24. A method of making a laminated board as claimed in claim 23, wherein the step of cutting portions includes the step of cutting said portions using a cutting machine.
25. A method of making a laminated board as claimed in claim 24 wherein the step of providing each second layer includes the step of peeling parts from the cut portions, wherein said parts include one or more knots and/or part of an outer layer of the stem.
26. A method of making a laminated board as claimed in claim 25 wherein the step of providing each second layer includes the step of compressing said portions to at least partly flatten the surfaces thereof.
27. A method of making a laminated board as claimed in claim 21 wherein the steps of superposing at least one first layer to at least one second layer and bonding the layers include the steps of applying adhesive to each first layer and then superposing each first layer on a second layer.
28. A method of making a laminated board as claimed in claim 21 wherein the steps of superposing at least one first layer to at least one second layer and bonding the layers, include the step of pressing each first layer to the second layer on which it is superposed.
29. A method of making a laminated board as claimed in claim 28 wherein the step of pressing the first layer to the second layer includes effecting said pressing in a cooled condition or at room temperature.
30. A method of making a laminated board as claimed in claim 28 wherein the step of pressing the first layer to the second layer includes effecting said pressing at a raised temperature in a range from 120 degrees Celsius to 180 degrees Celsius.
31. A method of forming a laminated board having a sheet, the method including the steps of : forming at least one sheet including supporting coconut husk fibres; applying an adhesive to the fibres to embed the fibres in the adhesive; and allowing the adhesive to set and harden so as to form, together with the fibres, a hardened sheet; superposing said at least one sheet as a first layer, on at least a second layer consisting of a sheet which includes bamboo and bonding said layers one to another.
32. A method of forming a laminated board as claimed in claim 31, wherein the method includes the step of pressing the fibres and adhesive before the adhesive has fully set and hardened. DATED THIS 27TH DAY OF AUGUST 2004.
Description:
LAMINATED BOARD AND METHOD OF MAKING LAMINATED BOARD FIELD OF THE INVENTION This invention relates to a laminated board wherein at least one of its layers is of, or includes, bamboo, to a method of making a laminated board, and to a method of making a sheet.

BACKGROUND TO THE INVENTION Known types of plywood boards and wooden planks are made or derived from high quality hard woods, for providing the necessary strength characteristics. These woods are obtained from trees grown in natural forests. The veneer of the plywood is derived from logs obtained from such trees, where the logs have relatively large diameters, usually greater than 40 centimetres. However, the availability of trees which can provide such relatively large diameter logs and planks of desired dimensions is decreasing, due to lower forestry productivity or forest damage. This lower availability of the necessary raw materials has become disadvantageous to industries concerned.

It is an object of the present invention to overcome or ameliorate disadvantages of the prior art, and/or to make provision for an alternative form of plywood board or plank or laminated board, and/or of parts thereof.

SUMMARY OF THE INVENTION According to a first aspect of the invention there is provided a laminated board including: a first layer of wood; and

a second layer which includes bamboo, the second layer being bonded to the first layer.

In a preferred embodiment, the board includes two said first layers, wherein said second layer is sandwiched between said first layers.

Preferably, the first layer and two second layers together constitute a construction element layer, the laminated board further including two cover layers, wherein the construction element layer is sandwiched between the cover layers.

Preferably, the wood of each first layer has a wood grain oriented in a wood grain direction and the bamboo of the second layer has a bamboo grain oriented in a bamboo grain direction, said wood grain directions and bamboo grain direction being substantially parallel to one another so as to all be oriented in a construction element grain direction.

Then, in one preferred embodiment, the board includes a plurality of construction element layers laminated to one another and sandwiched between said cover layers. In this case, preferably, the construction element grain direction of at least one of said construction element layers is a first direction, and the construction element grain direction of the remainder of said construction element layers is a second direction perpendicular to the first direction.

In another preferred embodiment, the board includes a centre construction element layer and two further construction element layers sandwiching the centre layer between them. In this case, preferably, the construction element grain direction of said centre layer is one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.

In another preferred embodiment, the board includes a centre construction element layer and four further construction element layers, a first two of said further

layers sandwiching said centre layer between them, and the remaining two said further layers sandwiching said first two further layers and the centre layer between them. In this case, preferably, the construction element grain direction of the centre layer is one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.

In another preferred embodiment, the board includes two centre construction element layers laminated to each other and two further construction element layers sandwiching said two centre layers between them. In this case, preferably, the construction element grain direction of each centre element layer is the same one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.

In another preferred embodiment, the board includes two centre construction element layers laminated to each other and four further construction element layers, a first two of said further layers sandwiching said centre layers between them, and the remaining two of said further layers sandwiching the first two further layers and the centre layers between them. In this case, preferably, the construction element grain direction of each centre layer is the same one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.

In another preferred embodiment, the board includes three centre construction element layers laminated to one another and four further construction element layers, a first two of said further layers sandwiching said centre layers between them, and the remaining two of said further layers sandwiching the first two further layers and the centre layers between them. In this case, preferably, the construction element grain direction of each centre layer is the same one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.

In another preferred embodiment, the board includes two centre construction element layers laminated to each other and six further construction element layers, a first two of said further layers sandwiching said centre layers between them, a second two of said further layers sandwiching the first further layers and the centre layers between them, and the remaining two of said further layers sandwiching the first two, and second two, of said further layers and the centre layers between them. In this case, preferably, the construction element grain direction of each centre layer is the same one of said first and second directions, and the construction element grain direction of each said further layer is the other of said first and second directions.

In another embodiment, the board includes a centre construction element layer, a pair of additional layers sandwiching the centre construction element layer between them each additional layer including bamboo, a pair of further additional layers of wood sandwiching the centre construction element layer and additional layers between them, and a pair of cover layers sandwiching the centre construction element layer and all of said additional layers between them.

Preferably, the wood of one of said further additional layers has a wood grain oriented in a wood grain direction which is perpendicular to the construction element grain direction of the centre construction element layer.

In another embodiment, the board includes two said second layers, wherein said first layer is sandwiched between said second layers.

In one preferred embodiment, the first layer itself includes layers of wood, so as to constitute a laminated wood layer.

In a preferred embodiment, the board includes two veneer wood layers sandwiching the first and second layers between them.

Preferably, the board includes two cover layers sandwiching the first and second layers and veneer wood layers between them. In a preferred embodiment, each cover layer is a veneer cover layer of wood.

In a preferred embodiment, the wood of each of the laminated wood layer, the veneer wood layers and the veneer cover layers has a wood grain oriented in a respective wood grain direction and the bamboo of each of the second layers has a bamboo grain oriented in a respective bamboo grain direction. Then, preferably, the wood grain direction of the first layer is one direction, and the wood grain direction of each of the wood veneer layers, and the bamboo grain direction of each of the second layers, is another direction perpendicular to said one direction.

Preferably, in respect of each of the above embodiments, all of the layers are bonded one to another.

In one preferred form of the above embodiments, each cover layer is of wood.

In other preferred embodiments, each cover layer is of, or includes, other materials, such as melamine, a combination of coconut husk fibres and adhesive, phenolic coating, or coatings of the types sold under the brand names Casco and Dna.

According to a second aspect of the invention there is provided a method of making a laminated board, the method including the steps of : superposing at least one first layer on at least one second layer, wherein each second layer consists of a sheet which includes bamboo; and bonding the layers one to another.

In one preferred embodiment, each first layer is of wood.

Preferably, the method includes the step of providing each second layer. In this case, preferably, the step of providing each second layer includes the steps of : cutting portions from a bamboo stem; and

arranging the portions substantially in a sheet configuration to form at least part of the second layer.

In a preferred embodiment, the step of cutting portions includes the step of cutting said portions using a cutting machine.

Preferably, the step of providing each second layer includes the step of peeling parts from the cut portions, wherein said parts include one or more knots and/or part of an outer layer of the stem.

Preferably, the step of providing each second layer includes the step of compressing said portions to at least partly flatten surfaces thereof.

In a preferred embodiment, the steps of superposing at least one first layer to at least one second layer and bonding the layers include the steps of applying adhesive to each first layer and then superposing each first layer on a second layer.

Then, preferably, the steps of superposing at least one first layer to at least one second layer and bonding the layers, include the step of pressing each first layer to the second layer on which it is superposed. In a preferred embodiment, the step of pressing the first layer to the second layer includes effecting said pressing in a cooled condition or at room temperature. Also in a preferred embodiment, the step of pressing the first layer to the second layer includes effecting said pressing at a raised temperature, preferably in a range from 120 degrees Celsius to 180 degrees Celsius.

Preferably, the laminated board according to the second aspect of the invention or preferred embodiments thereof is a board according to the first aspect of the invention or preferred embodiments thereof.

According to a third aspect of the invention there is provided a method of forming a sheet, the method including the steps of : supporting coconut husk fibres;

applying an adhesive to the fibres to embed the fibres in the adhesive; and allowing the adhesive to set and harden so as to form, together with the fibres, a hardened sheet.

Preferably, the method includes the step of pressing the fibres and adhesive before the adhesive has fully set and hardened.

According to a fourth aspect of the invention there is provided a method of making a laminated board, the method including: the steps according to the third aspect of the invention to provide a pair of said sheets, and the steps according to the second aspect of the invention, wherein each sheet constitutes a layer of said laminated board.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying representations in which: Figure 1 is a schematic exploded perspective view of an embodiment of the invention constituting a construction element layer; Figures 2 to 8 are schematic exploded side elevations of laminated boards according to various embodiments of the invention; Figure 9 is a schematic exploded perspective view of a laminated board according to a further embodiment of the invention; Figures 10 and 11 are schematic exploded side elevations of preferred versions of the embodiment of Figure 9; Figure 12 is a schematic perspective view of part of a laminated board according to a further embodiment of the invention; and Figure 13 is a flow chart of a process for preparing bamboo fibers for board as described with respect to Figures 1-12.

PREFERRED MODES FOR PERFORMING THE INVENTION Referring to Figure 1, there is shown, in exploded form, a laminated board, generally designated 10, according to an embodiment of the invention. The board 10 is made up of a pair of outer wooden layers 12 and an inner layer 14 which includes bamboo. These layers 12 and 14 are superposed on, and bonded to, one another to form the laminated board 10. The thickness of each of the outer layers 12 is preferably 0.5 to 3 mm, more preferably 1 to 3 mm, and that of the inner layer 14 is preferably 1 to 10 mm, more preferably 1.5 to 10 mm. The length of the board 10 is preferably in the range of 240 cm to 480 cm, and the width preferably in the range from 60 cm to 120 cm.

To form the inner layer 14, portions are cut from one or more stems of bamboo (not shown). These portions are cut along the length of the bamboo stem using a splitting or cutting machine, and are about 2 to 3 cm in width. Once the portions are cut, each portion is peeled to remove that surface thereof which constituted an outer surface of the bamboo stem, and also to remove knots that were present in the stem.

The portions are then crushed or compressed to at least partly flatten surfaces thereof, and are then arranged adjacent to one another in a sheet-like configuration, for constituting the inner layer 14.

The steps of this latter process are shown in more detail with reference to Figure 13. Bamboo of an outer diameter of 6-17 centimetres, thickness 5-30 millimetres and length 120-480 centimetres is selected. The appropriate length is chosen by cross cutting across the bamboo stem then the stem is split into two parts and flattened using a press. Each layer of bamboo is 8-20 centimetres wide and hence provides a uniform standard for bamboo board thickness. The outer layer and the lower most layer of the bamboo is discarded using a planing machine leaving the middle part of the bamboo providing a substantially uniform thickness overall. As the

outer edges of the bamboo are irregular, the outermost 1-2 centimetres are discarded using a cutting machine on both the left and right hand sides of the stripped bamboo.

The amount that is discarded will depend upon the size of the bamboo stem producing an overall width of bamboo board approximately 6-16 centimetres wide.

The bamboo is subsequently chemically treated to preserve the bamboo against fungi, termite and other micro organisms. The bamboo is then drained of excess liquid by putting the bamboo on a rack with the drained liquid being recycled to the treatment process. The bamboo is treated until approximately 20-25% water remains.

To further reduce the water content of the bamboo the bamboo is heated in a drying oven to reduce the water content to approximately 8-10% or to meet such requirements as may be required. The bamboo is then stored before it is to be used in producing laminate as described herein.

The laminated board 10 can be used as a component of more complex laminated boards according to other embodiments of the invention, and will therefore be referred to hereunder as a"construction element".

The bamboo as prepared above is made into the layer 14 by applying adhesive to the prepared material. The structure of the prepared bamboo has more free space in a given sized layer than that of wood allowing more adhesive to be used giving greater strength. Similarly, suitable adhesive is applied to the wood to constitute each of the outer layers 12, and these layers are then superposed on opposite faces of the layer 14, to form the construction element 10. The inner and outer layers 14, and 12, respectively, are pressed together, either at a cooled temperature or at room temperature (cold pressing) and are then pressed again at a raised temperature which is in the range from 120°C to 180°C (hot pressing).

The actual temperature within this range at which the hot pressing is carried out depends on the type of adhesive used, as will be understood by those skilled in the art. In preferred embodiments, the adhesive used is one of Urea Formaldehyde (UF),

Phenol Formaldehyde (PF), Melamine Formaldehyde (MF), or a mixture of UF or MF and Polyurethane.

The layers 12 and 14 are arranged such that their respective grains are substantially parallel to each other as indicated by the arrows 16 and 18 in Figure 1.

As these grain directions are substantially parallel, it will be appreciated that the grains of all of the wood or bamboo components of the construction element 10 extend in the same direction. Accordingly, this direction will be referred to as the construction element grain direction 24 of the construction element 10.

In Figures 2 to 8 there are shown laminated boards according to various embodiments of the invention, in which one or more substantially similar construction elements 10 are used. The laminated board of these embodiments are designated 22.1 to 22.7 in Figure 2 to 8, respectively.

Referring to the embodiment 22.1 in Figure 2, it will be seen that the single construction element 10 that is used is sandwiched between two cover layers 26.

These cover layers 26 are laminated to the construction element 10 using a method of cold and hot pressing as described above in relation Figure 1, with respect to the construction element 10 itself. The construction element grain direction 24 is oriented in the direction in which most of the strength of the laminated board of the embodiment 22.1 will be required in use.

Each cover layer 26 may be of soft, medium-soft, or hard wood, and may be patterned, engraved, moulded or otherwise marked on its respective outer surface, depending on the intended use of the laminated board according to the embodiment 22. 1. Alternatively, instead of being of wood, each cover layer 26 may be of, or include, another material, depending on the intended use of the board. In different preferred embodiments, the cover layer 26 is a layer of melamine or a layer coated with melamine, or a layer made from a combination of coconut husk fibres and adhesive, or a layer constituting or having a phenolic coating, or a layer constituting or having a coating of the types sold under the brand names Casco and Dyne .

Cover layers having coatings with phenolic, Casco and Dynes may be suitable when the laminated board is used as formwork or shuttering for concrete construction, as these coatings tend to resist the sticking of concrete. Cover layers having coatings with coconut husk fibres and adhesive as described may be suitable in uses such as crate-or shipping-container flooring, as these coatings tend to be largely weather resistant, and have a relatively rough finish to resist shoes slipping thereon.

On the other hand, such layers lend themselves to the sticking of concrete and painting, in situations where this is desirable, unlike the previously mentioned coatings used for concrete formwork and shuttering.

Cover layers can include various metal skins such as steel, copper, aluminium, stainless steel to a thickness of approximately 200-500 microns. The outer metallic surface skin can be stuck to the outermost layers by suitable adhesive known to a person skilled in the art. The metallic skin can provide modulus of rupture up to 1100 kg/cm2 and in addition provides improved fire resistance and weather resistance enabling it to be more useable for external use.

The embodiments 22.2 to 22.7 as shown in Figures 3 to 8, respectively, are essentially the same as the embodiment 22.1 of Figure 2, with the exceptions that they have different numbers of construction element 10 sandwiched between the veneer cover layers 26, and that the construction elements 10 are arranged, in the various embodiments, with different construction element grain directions 24.

The laminated boards 22.2 to 22.7 are each formed using a method of cold and hot pressing similar to that described above in relation Figure 1, with respect to the construction element 10 itself.

In Figure 3, there are three construction elements 10, the outer two of these having construction element grain directions 24 as indicated by the arrows, and the centre construction element having a grain direction 24 substantially at right angles to those of the outer two construction elements (that is, in a direction perpendicular to

the page on which Figure 3 appears) as indicated by the encircled"x"in that figure.

This symbol in the specification represents a direction perpendicular to the page on which the relevant figure appears.

In Figures 4 to 8, there are various numbers of construction elements 10 used, with constructional element grain directions 24 being as indicated by the respective arrows or the encircled"x"in each case.

The laminated boards according to Figures 1 to 8 may be used as replacements for conventional plywood boards in situations where such plywood would ordinarily be used. Such situations may include using the board for formwork or shuttering, for example in concrete construction, as liners for container-or crate-flooring, and so on.

Referring now to Figure 9, there is shown a laminated board 28 according to a further embodiment of the invention. This laminated board 28 includes a centre layer 30 which has a thickness in the range of 7 to 20 mm. In one preferred embodiment, the centre layer 30 is itself of laminated wood as indicated by the dashed line 30. 1, while in other embodiments, it is not itself laminated.

The centre layer 30 is sandwiched between a pair of layers 32 which include bamboo, and which are of a type substantially corresponding to that of the layers 14 described above. These layers 32 are of a thickness in the range of 1 to 10 mm.

The layers 30 and 32 are, in turn, sandwiched between a pair of veneer wood layers 34. These layers 34, in different embodiments, are of a soft, medium-soft, or hard wood, and are each of a thickness in the range of 0.5 to 3 mm, or more preferably 1 to 3 mm.

The layers 30,32 and 34 are all sandwiched between a pair of veneer cover layers 36. These layers 36, in different embodiments, are of soft, medium-soft, or hard wood, and have a thickness in the range from 0.5 to 3 mm, or more preferably 1 to 3 mm. The layers 36 may be patterned, engraved, moulded or otherwise marked on

their respective outer surfaces, similar to the veneer cover layers 26 referred to above, depending on the intended use of the laminated board 28 in question.

Although the cover layers 36 are described as being wood veneer layers, they may, in other embodiments, be of, or include, the other materials as described above in relation to the cover layers 26.

In one preferred embodiment, the laminated board 28 has a length in the range of 240 to 480 cm, and a width in the range of 60 to 120 cm. The length is presented in the transverse axis in Figure 9, while the width is presented as the"depth"axis in this figure.

The process for preparing the bamboo layer 32, and for laminating the board 28, as a whole, corresponds to the process described above in relation Figure 1 and Figure 13, with respect to the construction element 10 itself (with necessary changes to suit the particular configuration of the layers).

The grain directions of the respective layers 30,32, 34 and 36 are represented by the arrows 38. It will be noted that the grain directions 38 of the centre layer 30 and the veneer cover layers 36 are substantially perpendicular to those of the bamboo layer 32 and veneer wood layers 34.

Referring to Figure 10, there is shown a side elevation of the embodiment of Figure 9. In this figure, as well as in Figure 11, the encircled"x"symbol is used, and has the same meaning as described above.

In Figure 11, there is shown an alternative embodiment of the laminated board 28, designated 28.1, which differs from the embodiment 28 of Figures 9 and 10 in respect of the grain directions 38 of the layers 30,32 and 34 as shown.

The laminated boards 28 and 28. 1 may be used as substitutes for conventional wooden planks, in situations where such planks may otherwise be used. For example

they may be used as constructional components, such as flooring, walls, frameworks, semi-structural timber, and so on.

Embodiments of the invention also relate to a method of forming a sheet made of coconut husk fibres, as described below in relation to Figure 12. The method involves applying an adhesive to the fibres so that the fibres are embedded in the adhesive. The adhesive is then allowed to set and harden to form a hardened sheet.

The sheet is pressed prior to the adhesive completely setting and hardening.

Referring to Figure 12, the laminated board 100 that is shown incudes a centre construction element 102 similar to the construction element 10 described above, having a construction element grain direction 104 as indicated by the arrow. The construction element 102 is sandwiched between a pair of additional layers 106 including bamboo, that is, of a similar type to the layer 14 described above. The bamboo grain direction 107 of each additional layer 106, indicated by the arrow, is perpendicular to the grain direction 104. A pair of further additional layers 108 sandwich the construction element 102 and additional layers 106 between them, and have wood grain directions 110, indicated by the arrows. A pair of cover layers 112 sandwiches the construction element 102 and additional layers 106 and 108 between them.

The process for preparing the bamboo layers 106 and 14 (of the construction element 102), and for laminating the board 100, as a whole, corresponds to the process described above in relation Figure 1, with respect to the construction element 10 (with necessary changes to suit the particular configuration of the layers).

The cover layers 112 are formed from coconut husk fibres and adhesive as described above. The adhesive used can be one of those referred to above in relation to the laminated board of Figure 1. Preferably, the same adhesive is used in relation to forming the cover layers 112 as is used to laminate the other layers of the board 100, to enhance the bonding of the layers.

The pressing of the cover layers 112 during the process of forming these layers as described above is preferably a partial-pressing, with a further pressing occurring as part of the lamination process for the board 100 as a whole, once the cover layers are superposed on the other layers of the board.

As mentioned above, board made with cover layers of coconut husk as described may be suitable as crate-, or shipping-container flooring, due to the weather resistant and non-slip qualities of these finishes. For such uses, the thickness of the board is ideally around 28 to 29 mm In this specification, although reference is made to the various wood layers being of a soft wood, medium-soft wood, or a hard wood, a soft wood is preferred.

Such a wood, in a preferred embodiment of the invention, is a fast-growing type of soft wood species such as Albazia wood (Paraserianthes falcataria, Acacia manii).

The advantage of the use of bamboo and soft woods is apparent in relation to the respective growing times of the various types of wood and bamboo ; while hard wood trees may take 35 years to grow sufficiently, soft wood trees take around 5 to 7 years, and bamboo around 21/2 years to grow sufficiently.

Soft wood as referred to in this specification is a wood having a density of less than 500 kg/m3, while a medium-soft wood is a wood having a density of 500 to 670 kg/m3, and a hard wood is a wood having a density of above 670 kg/m3.

In the embodiments described above, it will be appreciated that the various grain directions referred to are substantially parallel to the respective planes in which the respective layers extend. As will be appreciated by those skilled in the art, the mechanical strength of wood or bamboo is greatest in a direction parallel to the grain direction. Accordingly, in laminated boards according to embodiments of the invention, a suitable overall mechanical strength may be achieved in the respective lengthwise and widthwise directions of the board, by suitably orienting the layers according to their respective grain directions. The mechanical strength sought to be achieved will usually depend on the intended use of the laminated board in question

A key feature of the invention is the lamination of one layer, which includes bamboo, to another layer, such as a wood veneer layer. The other layer essentially serves as a bed to support the adhesive which attaches the layers to each other, and the adhesive, in turn, holds the bamboo layer in place. Where the board is to serve as a substitute for conventional plywood, then as a result of the reinforcement provided by the layers that include bamboo, the other layers of the board need not be of as high a quality as those in conventional plywood. Therefore, for example, in conventional plywood where a particular layer may have to be a continuous layer of a certain thickness, in an embodiment of the invention, a layer made up of a plurality of pieces of wood rather than a continuous layer, which may be thinner than layers in conventional plywood, may suffice.

Because of the strength characteristics of bamboo, the layers which include bamboo as described above are considered as being the primary reinforcing layers of the respective laminated boards. For this reason, it is envisaged that these bamboo layers will be oriented with their grains extending in the direction in which most of the mechanical strength of the board will be required (although a combination of directions may be used to achieve the desired strength characteristics of the board as a whole). However, the other layers, particularly when of wood, do also contribute to the strength of the board. An important aspect of this strength is in relation to the sheer stress capabilities of the board, which relies both on layers that include bamboo and those that do not (such as the wood layers) and also the strength of the bond between adjacent layers.

The outermost layer of the board can be covered with a variety of materials as described above.

In addition to contributing to the strength, the other layers such as wood layers, also contribute to the bulk of the board. However, the thicknesses of the various layers are also determined by the required strength characteristics of the laminated board and the ease of handling of the layers during board manufacture. Where the

layers are of wood, particularly soft wood, then they are susceptible to breakage during handling if too thick. To reduce the risk of this occurring, instead of a particular layer being a single layer of the desired thickness, it may be a layer which itself is made up of more than one laminated layer, as in the case of the layer 30 described above in relation to the dashed line 30. 1.

Tests have indicated that, using the boards according to the embodiments described above in relation to Figures 1 to 8 instead of conventional plywood, can result in the modulus of rupture increasing from about 200 kg/cm2 to around 750 kg/cm2, or sometimes even as much as 1,500 kg/cm2.

Similarly, tests have indicated that, using boards according to the embodiments described above in relation to Figures 9 to 11 instead of conventional wooden planks, can result in an increase in the modulus of rupture from around 200 kg/cm2 to around 700 kg/cm2. Tests have also indicated similar ratios of increase in the modulus of elasticity (an increase of about 1.5 to 3 times) according to embodiments of the present invention when compared to conventional plywood or planks.

A further advantage of the invention is that it can provide for boards which may be significantly thicker than conventional plywood, for example, having a thickness of around 20 cm as opposed to thicknesses of conventional plywood which are typically around 26 to 28 mm, up to approximately 36 mm.

By using bamboo as described in relation to the embodiments above, particularly when the wood used in the remaining layers is a soft wood, the invention may assist in achieving many advantages over the use of conventional plywood or plank products. These advantages may include lower costs, more plentiful supply of materials, benefits to forestry and the environment, as well as the encouragement of the relevant industries. The advantages are contributed to by the relatively fast- growing nature of bamboo and of suitable soft woods.

Although the invention has been described in relation to the preferred embodiments above, it will be appreciated by those skilled in the art that it is not limited to those embodiments, and may be embodied in many other forms. For example, other combinations and permutations of different layers to those described above may be used. In addition, the boards according to embodiments of the invention are not only limited to those uses in which plywood or planks are conventionally used. As one example, embodiments of the invention may be used as so-called studs in the construction industry, that is, studs of the type used as spacer- and support-columns in the walls of framework buildings.




 
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