BOARD, METHOD FOR MANUFACTURING A BOARD AND A PANEL COMPRISING SUCH BOARD MATERIAL

Abstract

A board including a plurality of layers having a different composition. At least one of the layers is based on MgO and MgChloride and/or at least one of said layers is based on MgO and MgSulphate. Methods for manufacturing such boards, and methods for manufacturing coated panels include such board.

Claims

1. A panel, wherein the panel comprises a board, wherein the board is based on MgO and MgChloride, or wherein the board is based on MgO and MgSulphate; wherein the board comprises between 20 wt % and 90 wt % of plant fibers.

2. The panel as in claim 1, wherein the board comprises more than 30 wt % of plant fibers.

3. The panel as in claim 1, wherein the board comprises less than 80 wt % of plant fibers.

4. The panel as in claim 1, wherein the plant fibers are selected from wood fibers, bamboo fibers, or straw fibers.

5. The panel as in claim 1, wherein the board comprises an alkali resistant binder.

6. The panel as in claim 5, wherein the alkali resistant binder is selected from latex, acrylic, polyurethane, polyvinyl alchohol (PVA), ethylene vinylacetate (EVA), PVAc dispersion, acrylic styrene emulsion, silicate glue, silane and siloxanes.

7. The panel as in claim 1, wherein the board is free from glass fiber nets, free from glass fiber woven fabrics, and free from unwoven glass fiber structures.

8. The panel as in claim 1, wherein the plant fibers are coated with a sizing or with a resin.

9. The panel as in claim 1, wherein the board comprises a plurality of layers having a different composition, wherein each of the plurality of layers are based on MgO and MgChloride, or based on MgO and MgSulphate.

10. The panel as in claim 1, wherein a paper layer provided with a thermoset resin is adhered to the upper surface of the board.

11. The panel as in claim 10, wherein the thermoset resin is a melamine formaldehyde resin.

12. The panel as in claim 10, wherein at the side opposite to the side of the board onto which a paper layer is adhered, a resin-provided paper layer is adhered to the board as counterbalancing layer.

13. The panel as in claim 10, wherein the upper surface of the panel comprises a relief.

14. The panel as in claim 1, wherein the board is symmetrical through its thickness.

15. The panel as in claim 1, wherein the board comprises a bottom layer, a central layer and a top layer, wherein each of the bottom layer, the central layer and the top layer is based on MgO and MgChloride, or is based on MgO and MgSulphate; wherein the central layer has a lower weight percentage of plant fibers than each of the bottom layer and the central layer.

16. The panel as in claim 1, wherein the panel comprises coupling parts at opposite edges of the panel, wherein the coupling parts are substantially provided in the board, wherein the coupling parts are basically shaped as a tongue and a corresponding groove, wherein the groove is bordered by an upper lip and a lower lip, wherein the tongue and the corresponding groove provide in coupled condition a locking in the direction perpendicular to the surface of the coupled panels, wherein the lower lip comprises a locking element, and the tongue comprises a corresponding locking element; wherein the locking elements are configured for providing a locking in the direction parallel with the coupled panels and perpendicular to the coupled edges.

17. The panel as in claim 16, wherein the board comprises a bottom layer, a central layer and a top layer, wherein each of the bottom layer, the central layer and the top layer is based on MgO and MgChloride, or is based on MgO and MgSulphate; wherein the central layer has a lower weight percentage of plant fibers than each of the bottom layer and the central layer; wherein the upper lip is at least partially provided in the top layer; wherein the lower lip is at least partially provided in the bottom layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0093] With the intention of better showing the characteristics according to the invention, in the following, as an example without limitative character, an embodiment is described, with reference to the accompanying drawings, wherein:

[0094] FIG. 1, in perspective, shows a floor panel in accordance with the invention;

[0095] FIG. 2 at larger scale shows a cross-section according to the line II-II on FIG. 1;

[0096] FIG. 3 in a similar view shows a variant; and

[0097] FIG. 4 schematically illustrates a method in accordance with the invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0098] FIG. 1 illustrates a panel 1 in accordance with the ninth aspect of the invention. In this case it is a floor panel 1 that is oblong and rectangular and comprises a long pair of opposite edges 2-3 and a short pair of opposite edges 4-5, both provided with coupling parts 6 allowing to couple two such panels at the respective edges 2-3;4-5.

[0099] FIG. 2 shows that the coupling parts 6 at least on the long pair of opposite edges 2-3 are basically shaped as a tongue 7 and a groove 8 provided with locking elements 9-10 preventing the moving apart of the tongue and groove connection. These coupling parts 6 are realized in one piece with the core or board 11 of the floor panels 1. The cooperation of the coupling parts 6 results in two such panels 1 to become interlocked, wherein a vertical locking in a direction VI perpendicular to the plane of coupled panels 1 and a horizontal locking in a direction Hl perpendicular to the respective edges 2-3 and in the plane of the coupled panels 1 is obtained.

[0100] FIG. 2 further shows that the floor panel 1 comprises a board 11 and a provided thereon decorative layer 12. At the bottom of the board 11 a counterbalancing layer 13 is provided.

[0101] The board 11 is based on MgO and MgChloride, or, based on MgO and MgSulphate. In this case the board 11 in particular shows the characteristics of the fifth independent aspect. The board comprises a plurality of layers 14-15-16 having a different composition. In the example, the board 11 comprises at least three layers, namely a centrally located layer 14 and two more outwardly situated layers 15-16 at each side of the central layer 14, wherein the more outwardly situated layers 15-16 each comprise a higher cellulose content than the central layer 14. The cellulose content of the outer layers 15-16 may be 15 wt % or higher, while the cellulose content of the centrally located layer 14 is between 0 and 6 wt %.

[0102] The floor panel 1 in the example of FIGS. 1 and 2 further illustrates a coated panel obtained or obtainable through a method with the characteristics of the eighth independent aspect of the invention. The decorative layer 12 comprises a printed paper sheet 17 being treated with a melamine formaldehyde resin, wherein the paper sheet 17 has a raw paper weight of 50 to 100 grams per square meter and has a resin content of 50 to 130 grams per square meter dry weight. The decorative layer 12 further comprises an overlay, in this case a paper sheet 18 that is transparent or translucent in the obtained panel and applied on top of said printed paper sheet 17. Said overlay is treated with melamine formaldehyde resin as well, has a raw paper weight of 8 to 30 grams per square meter and a resin content of 30 to 100 grams per square meter. The overlay comprises, at its side facing said printed paper sheet 17, particles of aluminum oxide in an amount of 8-20 grams per square meter. Said counterbalancing layer 13 also comprises a paper sheet 19 and melamine formaldehyde resin, for example a paper sheet 19 having a raw paper weight of 70 to 100 grams per square meter and a resin content of 80 to 200 grams per square meter dry weight.

[0103] The higher cellulose content in the upper outer layer 15 is beneficial for creating a sufficient adherence with the melamine formaldehyde resin containing top decorative layer 12. The lower cellulose content in the centrally located layer 14 ensures an acceptable dimensional stability of the coated panel 1 as a whole in changing ambient relative humidity.

[0104] It is noted that, in the example of FIG. 2, the groove 8 at said long pair of opposite edges 2-3 is bordered by an upper lip 20 and a lower lip 21, and, in this case, it is the lower lip 21 that comprises a locking element 10 taking part in said horizontal locking. The lower lip 21 is provided at least partially in the outer layer 16 situated at the bottom of said central layer 14, namely in a layer of the board that comprises cellulose fibers. Preferably, as is the case here, at least half of the thickness TL of the lower lip 21 at its thinnest zone 22 is formed by said lower outer layer 16.

[0105] In the example tongue-and-groove locking system, the lower lip 21 of the groove 8 is required to or resiliently deform upon coupling. The lower lip 21 can therefore be regarded as a critical area of the coupling system. Because of it being at least partially provided in the cellulose containing lower outer layer 16 of the board 11, the risk of failure of the lower lip 21 upon coupling and afterwards can be limited.

[0106] In the engaged condition of two or more of such panels 1 the locking elements 9-10 exert a tension force upon each other which forces the panels 1 towards each other. In the example the lower lip 21 of the groove 8 has an elastically bendable portion 23 which, in the engaged condition, is at least partially bent and in this manner provides the aforementioned tension force. Said bendable portion 23 is provided with a contact surface 24 which inwardly slopes downward.

[0107] Preferably, the coupling parts 6 and the locking means 9-10 are realized in one piece with the core or board 11 of the panels 1, e.g. floor panels.

[0108] The floor panels 1 illustrated in FIG. 2 further show the characteristics that the coupling parts 6 have such a shape that two subsequent floor panels can at least be engaged into each other by a turning movement W, whereby each subsequent floor panel 1 can be inserted laterally into the previous; that the coupling parts 6 provide in an interlocking, free from play, according to all directions in the plane which is situated perpendicular to the aforementioned edges 2-3; that the possible difference E between the upper lip 20 and lower lip 21 of the groove 8, measured in the plane of the panel and perpendicular to the longitudinal direction of the groove 8, is smaller than one time the total thickness T of the panel 1; that the total thickness T of each related panel 1 is larger than or equal to 5 mm, or even larger than or equal to 7 mm.

[0109] FIG. 3 shows a similar example floor panel 1 as that illustrated by means of FIGS. 1 and 2, with two main differences, as explained here below.

[0110] A first difference is in that the board 11 of the FIG. 3 embodiment essentially comprises five layers 14-15-16-25-26 instead of three, namely a centrally located layer 14 with 0 to 6 wt %, of cellulose based material, two outer layers 15-16, one at each side of said centrally located layer 14, and two intermediate layers 25-26, one intermediate to each of the outer layers 15-16 and the centrally located layer 14, wherein said outer layers 15-16 each have a cellulose content of 15 wt % or more and wherein said intermediate layers 25-26 have an intermediate cellulose content, preferably of 5 to 15 wt % or 6 wt % to 15%.

[0111] A second difference is in that the board 11 of the FIG. 3 embodiment comprises a decorative layer 12 including, next to a printed paper sheet 17 and an overlay, also an underlay. The underlay is, in this example, a paper sheet 27 treated with melamine formaldehyde resin, having a raw paper weight of 8 to 30 grams per square meter and a resin content of 20 to 80 grams per square meter dry weight.

[0112] It is clear that the above two differences need not necessarily be combined.

[0113] FIG. 4 schematically illustrates that the printed paper sheet 17, the overlay with the transparent paper sheet 18, the optional paper sheet 27 for the underlay, the board 11, and the counterbalancing layer 13 of the embodiments of FIGS. 1 to 3 may be cured and consolidated during one and the same pressing operation between heated press elements 28, for example using a DPL process. In such case, as shown here, the press element 28A contacting the overlay may be structured in order to from a relief in the surface or top side of the obtained coated panel 1A-1B. Such relief may correspond to the print 29 contained on the printed paper sheet. For example in the case of a wood print impressions imitating wood grains or grain lines may be provided in the surface. Preferably such wood grains or grain lines follow the course of the printed pattern 29.

[0114] The higher cellulose content at the upper outer layer 15 of the board 11 may accommodate deformations due to the forming of said relief. As shown here, the press element 28A is designed to form relatively deep relief or structure features, for example having a depth of 0.35 millimeter or more. The formation of deep structure features can also be cased due to the availability of said underlay.

[0115] In the present example, next to deep embossments formed in the actual upper surface of the coated panel 1, structure features forming a lower edge area at one or more of the edges of the coated panel 1 are achieved. In this case the lower edge are forms a bevel 30. FIG. 4 also illustrates by means of the contours 1A-1B of the obtained coated panels, that the upper outer layer 15 may be deformed somewhat to accommodate the deepest structure features, such as said bevels 30.

[0116] FIG. 4 further illustrates the presence of hard particles 31, such as particles of aluminum oxide at that side of the overlay which faces the printed paper sheet 17. The available resin 32 on the respective paper sheets 17-18-19-27 is also illustrated.

[0117] It is noted that, by means of the DPL pressing operation larger coated boards, or pressed wholes, are formed from which, by means of a dividing operation, such as a sawing operation, several floor panels 1A-1B may be formed. In FIG. 4 the contours of two floor panels 1A-1B adjacent in the larger coated boards are illustrated by means of the dashed lines.

[0118] It is further noted that the boards illustrated in the figures are symmetric through their thickness, i.e. the layers 15-16-25-26 at both sides of a centrally located layer 14 show a thickness, composition and order that results in a symmetric build-up as seen from the middle of the thickness of the board 11.

[0119] With regard to FIG. 3, it is further remarket that, in this example the contact surfaces 33-34 between the tongue 7 and the bottom of the upper lip 20 of the groove 8 are entirely realized the intermediate layer 25 adjacent to the upper outer layer 15.

[0120] The present invention is in no way limited to the above described embodiments, but such methods, boards and coated panels may be realized according to several variants without leaving the scope of the invention.