BOARD AND FLOOR PANEL BASED ON SUCH BOARD

Abstract

Sheet material includes at least two layers of material, wherein a first layer of material forms more than half the thickness of the sheet material and is mainly built up from wood particles glued by means of a first binder and pressed. The first binder is thermosetting, wherein the second layer of material is present on the surface of the aforementioned sheet material and is mainly built up from particulate particles glued by a second binder and pressed. The second binder is thermoplastic and/or elastomeric.

Claims

1. A sheet material with at first and second layer of material; wherein a first layer of material forms more than half of the thickness (T) of the sheet material; wherein the first layer is according to a first option mainly built up from wood particles glued by means of a first binder and pressed, wherein the first binder is thermosetting; or wherein the first layer is according to a second option substantially built up from a mineral sheet; wherein the second layer of material contacts the first layer of material and is mainly built up from particulate particles glued by means of a second binder and pressed; wherein the second binder is thermoplastic or elastomeric; wherein the particulate particles of the second layer of material are coated with a thermosetting binder.

2. The sheet material of claim 1, wherein the thermosetting binder with which the particulate particles of the second layer of material are coated is selected from melamine formaldehyde, urea formaldehyde, melamine-urea-formaldehyde, phenol formaldehyde, phenol-urea-formaldehyde, methylene diphenyl diisocyanate, polymeric methylene diphenyl diisocyanate, thermosetting acrylate resin, or a binder obtained by a reaction with dextrose.

3. The sheet material of claim 1, wherein the particulate particles of the second layer of material are wood chips or wood fibres coated with the thermosetting binder.

4. The sheet material of claim 1, wherein the second binder is thermoplastic and is selected from the group of polyvinyl butyral (PVB), polyvinyl butyrate, polyvinyl chloride (PVC), polyvinyl dichloride (PVdC), polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), thermoplastic polyurethane (TPU), thermoplastic aliphatic polyester, polylactic acid (PLA), thermoplastic olefin (TPO).

5. The sheet material of claim 1, wherein the second binder is elastomeric and is selected from the group of synthetic rubber, silicone, polyvinyl butyral and natural rubber.

6. The sheet material of claim 1, wherein the second binder comprises cross-linked polyvinyl butyral.

7. The sheet material of claim 1, wherein the sheet material comprises a decorative top layer arranged on the second layer of material.

8. The sheet material of claim 7, wherein the decorative top layer comprises a printed paper sheet and a transparent or translucent layer applied on the printed paper sheet.

9. The sheet material of claim 7, wherein the decorative top layer comprises a relief, wherein the relief comprises structural features that have a depth greater than the thickness of the decorative top layer.

10. The sheet material of claim 9, wherein the relief comprises elements with a depth between 200 and 2000 micrometer.

11. The sheet material of claim 1, wherein the first layer is mainly built up from wood particles glued by means of a first binder and pressed, wherein the first binder is thermosetting; wherein the wood particles of the first layer of material are wood fibres.

12. The sheet material of claim 11, wherein the first binder is selected from the group of melamine formaldehyde, urea formaldehyde, melamine-urea-formaldehyde, phenol formaldehyde, phenol-urea-formaldehyde, methylene diphenyl diisocyanate, polymeric methylene diphenyl diisocyanate, thermosetting acrylate resin or a binder obtained by reaction with dextrose.

13. The sheet material of claim 1, wherein the first layer substantially built up from a mineral sheet, wherein the mineral sheet comprises a magnesium oxide sheet, a fibre cement sheet or a plasterboard; wherein the mineral sheet comprises fillers.

14. The sheet material of claim 13, wherein the mineral sheet comprises fillers selected from wood particles, wood dust or wood fibres.

15. The sheet material of claim 1, wherein the second binder is polyvinyl butyral obtained from the recycling of safety glass.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0094] With the aim of demonstrating the features of the invention better, some preferred embodiments are described hereunder, as examples without any limiting character, referring to the appended drawings, in which:

[0095] FIG. 1 shows a floor panel with the features of the invention;

[0096] FIG. 2 shows a cross-section along line II-II shown in FIG. 1;

[0097] FIG. 3 shows, on a larger scale, a view of the region that is indicated with F3 in FIG. 2, in a coupled state of two of said floor panels;

[0098] FIG. 4 shows, on a larger scale, a view of the region that is indicated with F4 in FIG. 3;

[0099] FIG. 5 shows schematically some steps in a method for making a sheet material with the features of the invention;

[0100] FIG. 6 shows schematically some steps in a method for making a floor panel with the features of the invention;

[0101] FIG. 7 gives, on a larger scale, a view of the region that is indicated with F7 in FIG. 5 for a variant;

[0102] FIG. 8 shows a graph with the density of the sheet material from FIGS. 1 to 4 as a function of the thickness thereof; and

[0103] FIG. 9 shows a cross-section of a sheet material according to one embodiment of the invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0104] FIG. 1 shows a decorative panel, more particularly a floor panel 1, in accordance with the invention. The panel 1 is rectangular and elongated and comprises a pair of opposite short edges 2-3 and a pair of opposite long edges 4-5.

[0105] FIGS. 1 to 3 show that both pairs of opposite edges 2-3-4-5 are provided with mechanical coupling means 6 that are mainly realized as a tooth 7 and a groove 8 delimited by an upper lip 9 and a lower lip 10, wherein the tooth 7 and the groove 8 are mainly responsible for the locking in a vertical direction V1, and wherein the tooth 7 and the groove 8 are provided with additional locking elements 11-12, which are mainly responsible for the locking in a horizontal direction H1. Preferably the locking elements comprise a projection 11 on the underside of the tooth 7 and a recess 12 in the lower groove lip 10, delimited by a projecting portion 13. The coupling means 6 shown in FIGS. 1 to 3 allow at least coupling by means of a rotating movement W round the respective edges 2-3-4-5 and/or coupling by means of a sliding movement S in a substantially horizontal manner of the edges to be coupled 2-3-4-5 towards each other.

[0106] FIG. 3 clearly shows that the decorative panel 1 comprises a substrate 14 on which a decorative top layer 15 is provided.

[0107] The particular feature of the floor panel 1 from FIGS. 1 to 3 is among other things that the substrate 14 is obtained on the basis of a sheet material 16 according to the first aspect of the invention. For this purpose the sheet material 16 comprises a first layer of material 17 which forms more than half of the thickness T of the sheet material 16 and is mainly built up from wood particles glued by means of a first binder and pressed. In this case the first layer of material 17 has the structure of a typical HDF board. It is namely built up from wood fibres 18 glued by means of MUF and pressed.

[0108] FIG. 4 clearly shows that the sheet material 16 additionally has a second layer of material 19 on the surface, wherein this second layer of material 19 is mainly built up from particulate particles 20 glued by means of a second binder and pressed. The second binder is in the present case thermoplastic, more particularly polyvinyl butyral (PVB) obtained by recycling of glass. The particulate particles 20 are wood chips with a particle size of 500 micrometres or more, as expressed with the d50 value measured by laser diffraction granulometry according to ISO13320 (2009). According to a concrete example, the wood chips have the following particle size distribution.

TABLE-US-00001 Fraction weight Size weight Mass (mm) (g) (%) >3 21.5 4.174757 2.5-3 48.5 9.417476 2-2.5 29.5 5.728155 1.4-2 189.5 36.79612 1-1.4 63.5 12.3301 <1 162.5 31.5534 515 100

[0109] The thickness T1 of the aforementioned first layer of material 17 is at least three times the thickness T2 of the aforementioned second layer of material 19.

[0110] The sheet material 16 consists of the aforementioned first layer of material 17 and second layer of material 19, and thus does not have any further layers of material than the aforementioned first and second layers of material 17-19. The aforementioned decorative top layer 15 is applied on the surface of the sheet material 16 that is formed by the aforementioned second layer of material 19.

[0111] The aforementioned decorative top layer 15 comprises a printed paper sheet 21 and a transparent or translucent layer 22 applied thereon. In this case the transparent or translucent layer comprises synthetic material, which is subjected at least to thermal curing, more particularly it relates here to thermally cured acrylate resin or unsaturated polyester, preferably cured on the basis of an at least thermally initiated radical crosslinking reaction.

[0112] FIG. 4 shows the printed paper sheet 21. Preferably the core of this paper sheet 21 is provided with modified or unmodified melamine resin. On both surfaces of the paper sheet 21, in this example a synthetic material is provided that comprises double carbon bonds, such as polyurethane. As an alternative to said polyurethane, use can for example be made of a water-based polyurethane dispersion. Above that, as already stated, the transparent or translucent wearing layer 22 is present. In the top layer 15, in a position above the print 23, hard particles 24, such as aluminium oxide particles, are applied additionally in order to obtain improved wear resistance.

[0113] FIGS. 2 and 3 clearly show that the aforementioned decorative top layer 14 has a relief with structural features that have a depth greater than the thickness T3 of the decorative top layer 15. On the edges of at least two opposite sides, the floor panel has lower edge regions 25, in this case in the form of a chamfer. The print 23 or decorative effect extends as far as the respective upper edge 26. The underside of the decorative top layer 15 is located at the position of the upper edge 25 on a horizontal level L that extends below the level of the second layer of material 19.

[0114] FIG. 5 shows schematically a method for making a sheet material 16 with the properties of the invention. In the example, it relates to a method that is carried out on the basis of a production line 27 which corresponds substantially to a typical MDF or HDF production line. In this case it starts from a material mass 28 for the aforementioned first layer of material 17, which in a preceding step S0 is assembled at least on the basis of the aforementioned first binder and the aforementioned wood particles. In this case both constituents are fed simultaneously into a spreading machine 29 in the form of wood particles provided beforehand with a first binder, namely polycondensation glue, more particularly wood fibres 18 provided with polycondensation glue, for example MUF.

[0115] The spreading machine 29 of said production line 27 may be of any design. In the example, a spreading machine 29 is used such as that known per se from WO 03/053642. The spreading machine 29 of the example is provided with several agitating elements 30 which bring the glued wood fibres 18 in motion in the spreading chamber 31. On the basis of the wood fibres 18 that leave the spreading chamber 31 on the underside, the material mass 28 is assembled on the conveying device or conveyor belt 32 located thereunder. For further description of said spreading machine 29, refer to the aforementioned international patent application. Other types of spreading machines are of course also suitable, for example such as the spreading machines described in the international patent applications WO 99/36623 and WO 2005/044529.

[0116] Seen in succession, the spreading machine 29 is followed by a so-called scalpel roll 33, which removes any excess wood fibres 18 from the material mass 28, after which a material mass 28 with a flat or almost flat upper surface is then obtained. It is to be noted that it is not essential to work with said scalpel roll 33.

[0117] In succession, the aforementioned scalpel roll 33 is followed by a compacting device or pre-press 34 in which the assembled material mass 28 is gradually compacted beforehand on the actual hot presses in step S2 to a state in which they can be transported more easily in comparison with the uncompacted assembled material mass 28. For this purpose, the assembled material mass 28 is transported during step S1 preferably, as shown here, between press bands 35, wherein these press bands 35 have a successively decreasing clearance. In this pre-compaction in the pre-press 34, preferably no heat is supplied and/or, preferably, the first binder that is present is not yet or only partially activated. Rather, the pre-compaction is preferably at least partial removal of the gases, such as air, present in the assembled material mass 28.

[0118] After the aforementioned pre-compaction in step S1 has been carried out, granules 36 are applied on the material mass 28 of the first layer of material 17. The granules 36 in question comprise the aforementioned second binder and the particulate particles 20, in this case polyvinyl butyral (PVB) and wood chips, optionally supplemented with a glue fraction, for example pMDI. For this purpose, seen in succession, the spreading machine 29 is followed by a device 37 for applying the aforementioned granules 34 on the material mass 28. In this case the device 37 executes a spreading operation. For this purpose, for example a spreading device may be used such as is known per se from GB 1,003,597 or GB 1,035,256. As illustrated in FIG. 5, said spreading device may comprise a recipient 38 that is connected to a metering roll 39, which carries the granules 36 away from the recipient 38. Said metering roll 39 is preferably of structured design, wherein the granules 36 are then entrained mainly via the lower structural portions of the metering roll 39. Said spreading device preferably further comprises a device 40 which detaches the granules 36 from the aforementioned metering roll 39. In this case a brush device is used for this purpose. On the basis of said spreading device, sufficiently uniform spreading can be obtained.

[0119] After the compacting device or pre-press 34, and the device 37, there is, viewed in the direction of passage, the actual press 41, in which the assembled material mass is pressed under the effect of heat. The temperature used may be for example between 100 C. and 150 C. and the pressure used may be for example on average between 4 and 10 bar, although brief peak pressures up to 40 bar are not excluded. Preferably, the binder present in the granules 36 is melted in this press 41, or at least heated to above its glass transition temperature. Preferably, activation of the first binder present on the wood fibres 18 also takes place here. In the case of a polycondensation glue, water or rather steam may be produced in this press 41.

[0120] The press 41 shown here is of the continuous type, namely of the type wherein the assembled material mass is transported and/or is gradually pressed between press bands 42. A pressure and/or temperature variation may be created on passing through said press 41. By means of this press 41, the density of the already partially compacted assembled material mass 16 can be at least doubled. It is clear that the method of the invention can also be carried out with other presses, for example such as with a vapour pressure press, with a multistage press or with a so-called short-cycle press. With these other presses 41, the pressure and/or temperature employed may be set as a function of the time that the material mass in question remains in the press 41.

[0121] It is clear from the foregoing that FIG. 5 forms an example of the fifth concrete possibility described in the introduction for the step of depositing particulate particles 20 and binder particles of the second layer of material 19. It is clear that the other concrete possibilities presented there can also be used in a production line 27, by varying the contents of the recipient 38 and/or the number of devices 37 according to the desired possibility. Preferably all the devices 37 or spreading operations for the second layer of material 19 are located between the pre-press 34 and the actual press 41.

[0122] FIG. 6 shows schematically some steps in a method for making the floor panel 1 from FIGS. 1 to 4. In the example, it starts from a decorative top layer 15 that comprises at least one paper sheet 21. The paper sheet 21 is provided with a print 23. In a first step S3, the paper sheet 21, more particularly a paper web from which the paper sheet 21 will be obtained later by cutting, is provided with synthetic material 43. For this purpose, the paper web is unrolled and the core is impregnated with a first synthetic material 43. Core impregnation may limit the risk of splitting of the paper sheet 21 in the final covered panel 1. In the example, this core impregnation takes place in two substeps, namely a first substep S3A in which synthetic material 43 is applied by means of a roll 45, and a second substep S3B in which the paper sheet 21 is immersed in a bath 46 of the respective synthetic material 43. In the example, the synthetic material 43 that is applied in the first substep S3A and in the second substep S3B is the same. It is, however, also possible that the synthetic material applied in the first substep and in the second substep are different from one another, regardless of the actual application technique that is employed. Between the first substep S3A and the second substep S3B, the paper sheet 21 follows a path 47 that allows sufficient penetration of the first synthetic material 43 applied during the first substep S3A. As the first synthetic material 43, it is possible to use a modified or unmodified melamine-formaldehyde resin, modified or unmodified urea-formaldehyde resin or modified or unmodified melamine-urea-formaldehyde resin.

[0123] FIG. 6 further shows that, after the aforementioned core impregnation, aluminium oxide particles 24 may be applied in a third substep S3C, for example, as here, by a spreading operation. This is preferably followed in a fourth substep S3D by a drying operation in a hot air oven 48. Optionally, in a fifth substep S3E, an interlamellar coating 44, which increases the compatibility with the wearing layer 22 to be formed from thermosetting acrylate resin or unsaturated polyester, may be applied on the side of the print 23 and/or the side of the paper sheet 21 that is intended to face the wearing layer 22. This interlamellar coating 44 may for example consist of a water-based polyurethane coating, a water-based UV curing substance and/or carbodiimide. During the same step S3E, or in a separate step, a coating 44 may also be applied on the side of the paper sheet 21 that is intended to face the substrate 14. This coating 44 has the purpose of providing better adhesion with the substrate 14. According to another possibility, said coating 44 may also have the purpose of providing sound damping. In this last case it is preferable to use polyurethane, for example aromatic polyurethane or thermoplastic polyurethane (TPU). After application of the interlamellar coating 44, as in the example, a drying operation may be carried out again, similar to that in the fourth substep S3D.

[0124] In a seventh substep S3F, the treated paper sheet 21 passes in this example over a cooling roll 49, and the paper web is divided into sheets.

[0125] In a second step S5, a stack 50 is formed, which at least comprises the substrate 14 and the paper sheet 21 with the print 23, obtained in step S3.

[0126] Preferably a method of the invention comprises at least the third step shown S5, namely the step of applying, on top of the print 23 or the decorative effect, an acrylate resin containing a thermal initiator, and the fourth step shown S6, namely the step of at least partially curing the aforementioned acrylate resin in a heated pressing operation. In the third step S5, an acrylate resin with a thermal initiator is also applied on the underside 51 of the substrate 14, for forming a balance layer 52. It is clear that here the third step S5, namely the step of applying the acrylate resin, is carried out while the paper sheet 21 with the print 23 or decorative effect already forms part of a stack 50, which comprises at least the substrate 14 and the decorative effect or the paper sheet 21 with the print 23.

[0127] In the example shown, the pressing operation is carried out using a so-called short-cycle press 53, and more particularly using a structured press element 54 or pressure plate. The pressing operation is carried out on a stack 50 that comprises the substrate 14, the paper sheet 21 with the print 23, the acrylate resin of the wearing layer 22 and the balance layer 52. During the pressing operation, the structure 55 of the press element 54 is copied in the surface of the wearing layer 22.

[0128] FIG. 7 shows a variant of the device 37 shown in FIG. 5. This relates to a device 56 that comprises one or more devices 37A-37B-37C or spreading machines, which deposit particulate particles, first binder and/or granules on a conveying device, in this case a conveyor belt 57. The devices 37A-37B-37C shown here are similar to those described in the context of FIG. 5. The assembled material mass 58 for the second layer of material 19, or a portion thereof, is transferred, here poured, via the conveyor belt 57 onto the material mass 28 for the first layer of material 17. It is obvious that using the device 57 shown here, several of the concrete possibilities stated in the introduction for the step of depositing particulate particles 20 and binder particles 59 of the second layer of material 19 can be carried out. Preferably, using at least one of the spreading devices, for example spreading device 37B, wood chips are deposited. Using one or more of the other spreading devices 37A-37C, particles 59 of the first binder may be deposited on the conveyor belt 58. Preferably, as shown here, in the direction of passage first a layer of binder particles 59 is deposited, then a layer of wood chips and then a layer of binder particles 59 again.

[0129] It is to be noted that a device 57 wherein the second material mass 58 is assembled on a conveyor belt 58 may also be used for applying the material mass in question 58, instead of on the first material mass 28 that is still to be pressed, on an already preformed substrate that consists substantially only of the aforementioned first layer of material 17.

[0130] FIG. 8 shows a graph with the density of the sheet material from FIGS. 1 to 4 on the ordinate and the thickness on the abscissa, wherein the thickness is expressed in mm, and the density in kg/m.sup.3. The thickness 0 mm coincides with the side of the sheet material that is formed by the first layer of material 17, whereas the thickness 8 mm is located near the surface formed by the second layer of material 19. The graph shows an average density of 830 kg/m.sup.3, a peak density P1 near the surface of the first layer of material 17 of 1058 kg/m.sup.3 and a peak density P2 near the surface of the second layer of material 19 of 1033 kg/m.sup.3. It is clear from the graph that the sheet material in question has the properties of the particular independent aspect stated in the introduction. The density remains between the aforementioned peak densities P1-P2 below the level of these peaks, but remains above the level of 80% of the average density. The minimum density is 717 kg/m.sup.3 and is reached roughly in half of the thickness of the sheet material.

[0131] It is clear from FIG. 8 that a density profile is reached that is very similar to that of a standard HDF board, but wherein one of the peak densities P2 is formed in the aforementioned second layer of material 19.

[0132] FIG. 9 shows a cross section of a sheet material according to an embodiment of the invention. The sheet material comprises a substrate 16 and a decorative top layer 15. The substrate comprises a first layer of material 17, a second layer of material 19 and a third layer of material 61. The first layer of material 17 is situated between the second layer of material 19 and the third layer of material 61. The first layer of material 17 may be configured as described for the first layer of material in any embodiment of the invention. The second layer of material 19 may be configured as described for the second layer of material in any embodiment of the invention. The third layer of material 61 comprises the features of the second layer of material as described in any of the embodiments of the second layer of material.

[0133] The present invention is by no means limited to the embodiments described above, but said sheet material and floor panels may be made according to several variants while remaining within the scope of the present invention.