Method of manufacturing a timber composite, the timber composite obtained and decorative panels comprising such timber composite

Abstract

A decorative panel including a substrate material and a decorative top layer, wherein the decorative top layer includes at least one timber layer with a wood structure, wherein the timber layer is a compressed timber layer with naturally occurring vessels throughout a thickness of the wood structure, the vessels being collapsed.

Claims

1. A decorative panel comprising a substrate material and a decorative top layer, wherein the decorative top layer comprises at least one timber layer with a wood structure, wherein the timber layer is a compressed timber layer with naturally occurring vessels throughout a thickness of the wood structure, the vessels being collapsed.

2. The decorative panel of claim 1, wherein the timber layer has a permanent increased density as compared to an original timber layer.

3. The decorative panel of claim 2, wherein the timber layer has an increased density of at least 20 percent or at least 50 percent.

4. The decorative panel of claim 1, wherein the substrate material is a wood-based material, selected from the group consisting of a MDF or HDF board, a chipboard, a Wood Plastic Composite board, a lamella core, a board assembled from laths, a thermoplastic board and a plywood board.

5. The decorative panel of claim 1, wherein the decorative panel comprises a glue layer between the decorative top layer and the substrate material to attach the decorative top layer to the substrate material.

6. The decorative panel of claim 5, wherein the glue layer comprises an adhesive or a thermosetting adhesive.

7. The decorative panel of claim 1, wherein the decorative top layer comprises a wear resistant coating or a wear resistant coating that is a UV lacquer or oil.

8. The decorative panel of claim 1, wherein the decorative panel is a square or rectangular floor panel which, at, at least one pair of opposite edges, or at both pairs, comprises mechanical coupling allowing to couple two of such floor panels to each other such that a locking is created in a vertical direction perpendicular to a plane of the coupled panels, as well as in a horizontal direction perpendicular to the coupled edge and in the plane of the coupled panels, the mechanical coupling being in the substrate material.

9. The decorative panel of claim 1, wherein the timber layer comprises a wood grain comprising both summer wood grain and spring wood grain, wherein the timber layer comprises raised portions and depressed portions, wherein the raised portions correspond to the summer wood grain and the depressed portions correspond to the spring wood grain.

10. The decorative panel of claim 1, wherein the wood structure is free from voids.

11. The decorative panel of claim 1, wherein the timber layer has a thickness of below 1.5 mm, or a thickness of below 1 mm and above 0.2 mm.

12. The decorative panel of claim 1, wherein the timber layer is a stained timber layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1 is a flow chart illustrating a method of manufacturing a timber composite;

(3) FIG. 2 schematically illustrates an apparatus for manufacturing a timber composite;

(4) FIG. 3 is a flow chart illustrating a further method of manufacturing a timber composite;

(5) FIG. 4 schematically illustrates a further apparatus for manufacturing a timber composite;

(6) FIG. 5 shows a perspective view of a decorative panel in accordance with the invention;

(7) FIGS. 6 and 7 are cross-sections at a larger scale according to the line VI-VI and VII-VII respectively in FIG. 5;

(8) FIG. 8 in a view similar to that of FIG. 7 illustrates a variant;

(9) FIG. 9 illustrates how the floor panel of FIG. 8 may be joint to form a floating floor covering; and

(10) FIG. 10 at a larger scale illustrates the area indicated with F10 on FIG. 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

(11) 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 utilized 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.

(12) Referring firstly to FIG. 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 this case 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 1%-20% by natural drying or machine drying, which can result in the produced timber composite (discussed in more detail below) having a higher density.

(13) 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 it more easily penetrates into and throughout the timber. In this way, the stain may be generally distributed throughout the timber. Thus, when, the timber layers are later formed into a composite timber (discussed below) the stain may be evenly distributed throughout the timber. This may not be the case with, for example, a block or panel of timber where the stain is applied to the external surface, because the stain may not be able to penetrate into the center of the block or panel of timber (this may especially be the case with hardwoods).

(14) 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 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.

(15) 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 invention.

(16) 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).

(17) 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).

(18) The heat 122 and pressure 120 causes the adhesive to penetrate into and throughout the fibers of the timber layers including into the interstices and pores between fibers. The 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 pressurized), 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.

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

(20) 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 fibers 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.

(21) Referring now to FIG. 3 the method 310 is similar to that shown in FIG. 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 fibers of the timber and cures. Additionally, the moisture in the timber tends to move towards the center 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 generally holds the timber in its compressed shape, with the spring wood having shrunk to a greater extent than the summer wood. Upon release of the pressure, the timber generally does not return, e.g. bounce back, to its original shape. The summer wood however, due to its greater density, may minimally return to its natural state, whilst the spring wood in the timber does not return (e.g. bounce back). 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.

(22) 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 of the original timber piece and having a wire-drawing and embossed effect.

(23) 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.

(24) 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 heater also capable of directly heating the two steel plates 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 FIG. 3, the apparatus 424 may allow the production or manufacture of timber composite having an embossed (i.e. raised grain) appearance.

(25) 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.

(26) FIG. 5 illustrates a decorative panel, more particularly a floor panel 1, in accordance with the invention. The panel 1 is rectangular and oblong and comprises a pair of opposite short edges 2-3 and a pair of opposite long edges 4-5. The decorative upper surface 6 is formed by a timber composite 7.

(27) FIG. 6 clearly shows that the decorative panel 1 comprises a substrate material 8 upon which the timber composite 7 is provided, e.g. glued or otherwise connected. The substrate material 8 in this case consists of a so-called lamella core, which comprises a plurality of adjacent laths 9 oriented cross wise over the length of the floor panel 1. Preferably such laths are made from softwood, e.g. spruce or hevea. The outermost laths 9A-9B that form the short edges 2-3 may be made from a different material, such as from MDF/HDF or plywood. Such material allows for a better processing, for e.g. milling to form the mechanical coupling parts 10 therein. At the bottom of the substrate material 8 a backing layer 11 is provided, e.g. glued or otherwise attached against the lamella core. Such backing layers is preferably made from a wood veneer having a thickness of at least 50 percent of said timber composite 7 forming the upper surface 6. According to a variant a timber composite 7 may be used for the backing layer 11 as well.

(28) FIGS. 6 and 7 illustrate that both pairs of opposite edges 2-3-4-5 are provided with mechanical coupling 10 that is substantially realized as a tongue 12 and a groove 13 bordered by an upper lip 14 and a lower lip 15, wherein this tongue 12 and groove 13 substantially are responsible for the locking in a vertical direction V, and wherein the tongue 12 and the groove 13 are provided with additional locking parts 16-17, substantially responsible for the locking in a horizontal direction H. Preferably, the locking parts comprise a protrusion 16 on the lower side of the tongue 12 and a recess 17 in the lowermost groove lip 15. The coupling parts 10 illustrated in FIGS. 6 and 7 at least allow a coupling by a turning movement W along the respective edges 2-3-4-5 and/or a coupling by a shifting movement S in a substantially horizontal fashion of the edges 2-3-4-5 to be coupled towards each other.

(29) FIGS. 8 and 9 illustrate a variant with a short pair of edges 2-3 that allow a coupling at least by a downward-directed movement D. One edge 2 is provided with a male coupling part 18, while the other edge 3 of this short pair 2-3 is provided with a female coupling part 19. By the downward movement D the male coupling part 18 is pushed into the female coupling part 19 to become locked in the vertical direction V due to a pair of cooperating heels 20 and recesses 21. In this case the recess 21 is partly formed by a resilient element 22 arranged in the female coupling part 19.

(30) FIG. 10 gives a detailed view on the composite structure of the timber composite 7 that forms the upper decorative surface 6. The timber composite 7 is formed by a plurality of superposed timber layers 23 that are penetrated with cured adhesive 24. Further the timber composite 7 shows an embossed effect at the decorative upper surface 6, wherein the summer wood 25 shows up as a raised portion 26.

(31) FIG. 10 clearly illustrates that the plurality of timber layers 23 have been assembled or laminated on top of each other such that the summer wood 25 of the plurality of timber layers is substantially vertically aligned. The order and orientation of the timber layers 23 has been maintained as compared to the order in which they were cut from a timber billet.

(32) Some embodiments of the invention have been described above, but the invention 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 invention. Such modifications and improvements fall within the scope of the present invention.

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

(34) Further, the timber layer may have a thickness of 0.01 to 100 mm. Alternatively, the timber layer may have a thickness between 0.1 to 5 mm or 1 to 3 mm. In case the timber composite is used as the top layer in a decorative flooring panel, the thickness is preferably at least about 2.5 mm and may range up to 3.5 or 4 mm. To reach such thickness it is clear that the timber composite should preferably comprise two or more timber layers. It is not excluded that a timber composite forming the upper surface of the decorative flooring panel would only comprise one timber layer penetrated with cured adhesive. Such floor panel presents important advantages over floor panels for veneer parquet.

(35) 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 be rotary peel, slicing or saw cutting.

(36) 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%.

(37) The pressure applied to the timber layers or stacks may be 0.01 MPa to 30 MPa. Alternatively the pressure may be 0.05 MPa to 20 MPa. Alternatively the pressure may be 2 MPa to 10 MPa.

(38) 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.

(39) 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.

(40) Multiple spacers can 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.

(41) 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 fibers 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 fibers of the timber layer more sufficiently under pressure. 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 fibers of the wood slices 1 sufficiently. The carrier can be, for example, paper or nonwoven cloth.

EXAMPLES

Example 1

(42) 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%.

(43) 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 7 MPa 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.

(44) 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

(45) Twelve 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%.

(46) 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 7 MPa was applied to the stacks. 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.

(47) 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

(48) 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.

(49) Formaldehyde melamine adhesive (200 g/m.sup.2) was sprayed onto the veneer, then the veneer was dried again to a moisture content of 12% by weight.

(50) The veneer was then stacked according to the original order of slicing.

(51) Pressure (95 kg/cm.sup.2) then heat ware 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

(52) 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.

(53) Formaldehyde melamine adhesive (200 g/m.sup.2) was sprayed onto the veneer, then the veneer was dried again to a moisture content of 12% by weight.

(54) 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 plastic film allowed an embossed look to be achieved.

(55) Pressure (95 kg/cm.sup.2), 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.

(56) 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” and variations such as “comprises” or “comprising” are 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 methods or timber composite as disclosed herein.