Method of manufacturing a building panel

Abstract

A method of manufacturing a building panel including a core, a decorative layer and a balancing layer, including mechanically processing production waste including a resin impregnated paper to processed production waste, applying a first mix including said processed production waste and a thermosetting binder on a first surface of a core, applying a decorative layer on a second surface of the core, and curing the first mix to a balancing layer of the building panel. Also, a building panel formed by such a method.

Claims

1. A method of manufacturing a building panel comprising a core, a decorative layer and a balancing layer, comprising applying a first mix comprising a thermosetting binder and particles formed from production waste comprising resin impregnated paper on a first surface of a core, turning the core having the first mix applied thereto such that the first mix is directed downwards from a surface of the core before applying a decorative layer, applying a decorative layer on a second surface of the core, and curing the first mix to form the balancing layer of the building panel, wherein the first mix comprises 1-50% by weight of said particles formed from production waste, wherein the resin impregnated paper comprises a substantially cured thermosetting binder.

2. A method according to claim 1, wherein the particles formed from production waste comprise lignocellulosic material or cellulosic material.

3. A method according to claim 1, wherein the first mix is a dry powder mix.

4. A method according to claim 1, wherein the thermosetting binder is applied on the core in dry powder form.

5. A method according to claim 1, wherein the thermosetting binder is in powder form when mixed with the particles formed from production waste.

6. A method according to claim 1, wherein the particles formed from production waste comprise wear resistant particles.

7. A method according to claim 1, wherein the particles formed from production waste are formed by mechanically processing production waste comprising resin impregnated paper.

8. A method according to claim 1, wherein the resin impregnated paper is a resin impregnated dcor paper, a resin impregnated backing paper or a resin impregnated overlay paper.

9. A method of manufacturing a building panel comprising a core, a decorative layer and a balancing layer, comprising applying a first mix comprising a thermosetting binder and particles formed from production waste comprising resin impregnated paper on a first surface of a core, applying a decorative layer on a second surface of the core, curing the first mix to form the balancing layer of the building panel, the method further comprising: applying a stabilization fluid on the first mix, turning the core having the first mix applied thereto such that the first mix is directed downwards from a surface of the core before applying the decorative layer, wherein the resin impregnated paper comprises a substantially cured thermosetting binder.

10. A method according to claim 9, further comprising drying the first mix before turning the core.

11. A method according to claim 1, wherein the first mix further comprises lignocellulosic or cellulosic particles separate from the particles formed from product waste.

12. A method according to claim 11, wherein the first mix is formed by adding the particles formed from product waste to a mix comprising the thermosetting binder and said lignocellulosic or cellulosic particles.

13. A method according to claim 1, wherein the decorative layer comprises a dcor paper.

14. A method according to claim 1, wherein the decorative layer comprises a second mix comprising lignocellulosic or cellulosic particles and a thermosetting binder.

15. A method according to claim 1, wherein the core is a wood based board.

16. A method according to claim 1, wherein the decorative layer comprises wear resistant particles.

17. A method according to claim 1, wherein the production waste is sieved so that the maximum particle size is about 1 mm.

18. A method according to claim 1, further comprising forming the first mix by adding the particles formed from the production waste to a powder mix comprising the thermosetting binder, wherein the thermosetting binder is 30-70% of the powder mix.

19. A method according to claim 18, wherein the powder mix further comprises lignocellulosic and/or cellulosic particles.

20. A method according to claim 1, further comprising curing, in a single step, under heat and pressure, the decorative layer on the second surface of the core, and the first mix to form the balancing layer of the building panel.

21. A method according to claim 9, wherein the production waste is sieved so that the maximum particle size is about 1 mm.

22. A method according to claim 9, further comprising forming the first mix by adding the particles formed from the production waste to a powder mix comprising the thermosetting binder, wherein the thermosetting binder is 30-70% of the powder mix.

23. A method according to claim 22, wherein the powder mix further comprises lignocellulosic and/or cellulosic particles.

24. A method according to claim 9, further comprising curing, in a single step, under heat and pressure, the decorative layer on the second surface of the core, and the first mix to form the balancing layer of the building panel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure will by way of example be described in more detail with reference to the appended schematic drawings, which show embodiments of the disclosure.

(2) FIGS. 1a-e illustrate a method to form a balancing layer.

(3) FIGS. 2a-d Illustrate a method to form a balancing layer.

(4) FIG. 3 illustrates a building panel wherein the decorative layer is laminate.

DETAILED DESCRIPTION

(5) FIGS. 1a-e illustrate a method of forming a building panel. The building panel may be a floor panel, a wall panel, a ceiling panel, a furniture component, a worktop, etc. The method comprises arranging a core 2 on a conveyor belt. The core 2 may be a board, such as a wood based board. The wood based board may, for example, be a HDF, MDF, particleboard, OSB, plywood, etc., or a WPC (Wood Plastic Composite). The core 2 may also be a thermoplastic core.

(6) The method further comprises applying a first mix 3 on a first surface of the core 2. The first mix 3 comprises particles formed from production waste comprising resin impregnated paper and separate particles of thermosetting binder. The first mix 3 is applied as a powder.

(7) By production waste is meant both residues from production and left-overs, such as unconsumed material intended for use in production.

(8) Production of building panels, for example, floor panels, results in a certain amount of production waste. The production waste may, for example, be unconsumed material, such as dcor papers, backing papers and overlay papers used for laminate flooring production. Dcor papers may be printed resin impregnated papers. Overlay papers may also be resin impregnated and comprise wear resistant particles. The printed dcor of dcor papers may be outdated and therefore can no longer be used. Both overlay papers, backing papers and dcor papers may have a limited storing time due to the resin included in the paper, which may start to cure. Unconsumed material may therefore be overlay papers, backing paper, and dcor papers, which have been stored for a longer time than recommended.

(9) The production waste may also be residues from production. Residues may originate from the production of the laminate papers, e.g., resin impregnated papers for use as dcor papers, backing papers or overlay papers. When impregnating the papers, the edges of the papers are cut, in order to obtain a straight edge, in an edge cutting operation, resulting in production waste comprising substantially uncured binder. Residues may also originate from pressing of the resin impregnated papers to a core for forming a building panel having a laminate surface layer. After pressing, the edge of the resin impregnated papers extending beyond the edge of the core are trimmed, resulting in production waste comprising substantially cured binder.

(10) Consequently, the production waste may comprise both substantially uncured and substantially cured binder, depending on the origin of the residues. If cured particles are included in the residues, the cured particles may function as hard particles facilitating scattering of the first mix 3.

(11) The production waste may comprise both lignocellulosic material and/or cellulosic material, or a combination thereof. The lignocellulosic or cellulosic material originates from the resin impregnated paper of the production waste.

(12) The production waste comprising resin impregnated paper is mechanically processed into particles. The production waste is preferably grinded. After grinding, the production waste is preferably sieved. The maximum particle size may be less than 1 mm, preferably less than 0.5 mm, preferably less than 0.3 mm.

(13) The processed production waste, preferably grinded into particles, is mixed with a binder in a mixing station. The resulting first mix 3 is preferably stored in a container. The first mix 3 is preferably a homogenous mix. The binder is preferably a thermosetting binder, such as an amino resin, for example, melamine formaldehyde resin, urea formaldehyde, phenol formaldehyde, or a combination thereof. The thermosetting binder is preferably in powder form, and preferably mixed with the production waste in powder form. The thermosetting binder added to the production waste is separate from the resin impregnated paper of the production waste. For example, the thermosetting binder is preferably not a resin separated from the production waste. The thermosetting binder may be separate from any resin in or obtained from the production waste. The thermosetting binder may be added in addition to the production waste and any resin therein. The thermosetting binder is not a recycled binder. The thermosetting binder is newly produced. Preferably, the thermosetting binder has its reactivity maintained.

(14) In one embodiment, wherein it is not required that the balancing layer counteracts the decorative layer, the binder may be a thermoplastic binder. In this embodiment, the balancing layer is a protective layer.

(15) In one embodiment, the binder may comprise a mix of a thermosetting binder of the type described above and a thermoplastic binder.

(16) In addition to the particles formed from processed production waste and the binder, the first mix 3 may also comprise lignocellulosic or cellulosic particles separate from any lignocellulosic or cellulosic material from, or obtained from, the resin impregnated paper of the production waste. The lignocellulosic or cellulosic particles are added to the first mix 3. The lignocellulosic or cellulosic particles may have maximum size of less than 1 mm, preferably less than 0.5 mm, preferably less than 0.3 mm. It is also contemplated that vegetable fibres as jute, linen, flax, cotton, hemp, bamboo, bagasse and sisal may be used. Also mineral fibres and carbon fibres may be used.

(17) The first mix 3 may be formed by adding particles formed from the production waste to a powder mix comprising the thermosetting binder and the lignocellulosic or cellulosic particles. The particles may be mixed with the thermosetting binder and the lignocellulosic or cellulosic particles in a mixing station. The thermosetting binder content of the powder mix comprising the thermosetting binder may be 30-70% by, preferably 40-65% by weight, more preferably 50-60% by. The amount of thermosetting binder added depends on the concentration of uncured resin in the production waste used in the mix.

(18) If needed, the mix formulation can be modified, such that thermoplastic particles, pigments, hard particles, release agents, wetting agents and similar materials are included into the mix. The thermoplastic particles may be mixed at random into the mix or applied as a separate thin layer and may be used to provide a sealing against moisture penetration into the core.

(19) The first mix 3 may further comprise additives, such as wetting agents, release agents, catalysts, etc. The first mix 3 may also comprise pigments.

(20) The first mix 3 is applied on a first surface of the core 2, preferably by scattering as shown in FIG. 1a. The first mix 3 is applied as a powder. The binder of the first mix 3 is applied as a powder. The first mix 3 is applied as a dry mix. The first mix 3 may be applied by a scattering device 110, for example, comprising a hopper, a roller 120 and optionally one or more nets. A first layer is thereby formed on the first surface of the core 2. The first layer is adapted to form a balancing layer 13.

(21) The scattering device 110 may have capacity of scattering of 100-1000 g/m2 with a tolerance of +/5% as measured using a calibration cup with an area of 100100 mm cross- and lengthwise the board.

(22) The scattering device 110 may comprise a needle belt and a scattering roller 120. The scattering roller 120 may be provided with needles in the range of about 30-120, preferably about 50-100, and most preferably about 70-90 needles per cm2. The needle length may be about 0.5-2.5 mm, preferably about 1-2 mm and most preferably about 1.5 mm. Several scattering devices 110 may be used to even out differences in the applied powder mixture.

(23) Furthermore, the scattering device 110 may be provided with a needle belt with needles with a preferred length of about 15-20 mm, a preferred frequency in the range of about 500-1000 rpm preferably about 1000 rpm, and a stroke length of about +/3 mm.

(24) FIG. 1b shows that the first mix 3 applied on the core 2 is thereafter pre-stabilized by a stabilization fluid 7, preferably comprising water, which is applied by a stabilizing device 9. The amount of stabilization fluid may vary from 0 up to 200 g/m2, and for example from 5 to 100 g/m2.

(25) The stabilization device 9 may apply the stabilization fluid by using steam, nozzle spray coating or ultra-sonic spray coating.

(26) The stabilization fluid 7 may comprise solvents, such as non-polar solvents, polar aprotic solvents and polar protic solvents or mixtures thereof. Preferred solvents are polar protic solvents, such as isopropanol, ethanol and water. Most preferred is water.

(27) The stabilization fluid 7 can further comprise additives, such as wetting agents, defoamers, release agents, anti-slip agents and catalysts.

(28) The first layer 3 is thereafter preferably dried, as shown in FIG. 1b. Such drying can be performed off-line in a controlled environment or in-line by applying heat 8 with a heating device 10 on the first mix 3. The heating device 10 may comprise infrared light (IR).

(29) The stabilization 7 and the following drying 8, attaches the first layer 3 to the core 2, to such an extent that the core 2 with the first layer 3 can be turned 180 to bring the first layer 3 downwards, as shown in FIG. 1c, such that it may be transported further along the production line or be stacked on a pallet for intermediate storage before further production takes place.

(30) In FIG. 1d, a second mix 1 is applied to a second surface of the core 2 for forming a decorative layer 12. The second mix 1 may comprise lignocellulosic or cellulosic particles, a binder, preferably a thermosetting binder, and optionally wear resistant particles. The second mix 1 may further comprise pigments. A print 4 may be printed into the second mix, preferably by means of digital printing. The second mix 1 is preferably applied as a powder. The second mix 1 is preferably applied by scattering the second mix in powder form. The second mix 1 may be applied as one or several layers to form a second layer.

(31) As an alternative to applying the second mix 1 for forming the decorative layer 12, the decorative layer 12 may be a laminate, as shown in FIG. 3. In this embodiment, a dcor paper 21 is arranged on the second side of the core 2. An overlay paper 22 may be arranged on the dcor paper 21. The overlay paper 22 may comprise wear resistant particles. The dcor paper 21 and/or the overlay paper may be impregnated with a binder, such as a thermosetting binder, or may be unimpregnated. If using unimpregnated papers, a binder may be applied between the core and the dcor paper, and/or between the dcor paper and the overlay paper, and/or on the overlay paper.

(32) As further alternatives, the decorative layer 12 may be a veneer layer, a wooden layer, a layer of thermoplastic material, etc. Any such layer may be combined with a powder based layer.

(33) The core 2 with the decorative layer 12 and the first mix 3 adapted to form the balancing layer 13 is thereafter fed into a press where the layers are cured under heat and pressure. Thereby, a building panel 6 is formed, comprising a balancing layer 13 arranged on a first surface of the core 2, as shown in FIG. 1e.

(34) FIGS. 2a-d shows an alternative method of manufacturing a building panel. In FIG. 2a, a first mix 3 of the type described above with reference to FIGS. 1a-e is applied on a carrier 11. The first mix 3 comprises particles formed from production waste comprising resin impregnated paper as described above. The first mix 3 further comprises a thermosetting binder of the above described type. The first mix 3 may further comprise lignocellulosic or cellulosic particles, additives, etc. as described above with reference to FIGS. 1a-e. The components are preferably mixed into a first mix as described above, preferably in powder form.

(35) The first mix 3 is preferably scattered on the carrier 11, for example, by means of a scattering device 110 of the type described above, for example, comprising a hopper, a roller 120 and optionally one or more nets. The carrier 11 may be a conveyor belt. The carrier 11 may also be a paper sheet or a non-woven.

(36) By scattering the first mix 3 on the carrier 11, a first layer is formed, adapted to form a balancing layer 13.

(37) A stabilization fluid 7, preferably comprising water, may be applied to the first mix 3. The stabilization fluid 7 may be applied by a stabilizing device 9. The stabilization fluid 7 may further comprise additives, such as wetting agents, release agents, catalysts, etc. The first layer is thereafter preferably dried. Such drying can be performed off-line in a controlled environment or in-line by applying heat 8 with a heating device 10 on the mix 3. The heating device 10 may comprise infrared light (IR).

(38) The first mix 3 may be dried to a loss on cure of 1.5-15 wt %. By loss on cure is meant the weight loss, calculated as weight percentage of the original weight, occurring when heating the impregnated paper at 160 C. for 5 minutes. The weight loss corresponds to moisture released from the impregnated paper. Under these conditions the released moisture is of two parts. The first part is the free moisture formed from water and/or other substances having a boiling point below 160 C. being trapped in the powder and the second part origins from the cross linking of the binder. Melamine formaldehyde resin cures during the heating up to 160 C. and the resin cross-links via a condensation reaction, i.e., water is released by the condensation reaction.

(39) As an alternative or complement, the stabilization fluid 7 may be applied on the carrier 11 before applying the first mix 3.

(40) In one embodiment, the first layer 3 is formed into a pre-preg as disclosed in U.S. patent application Ser. No. 13/445,379, which hereby is incorporated by reference in its entirety, for example by pre-pressing. The pre-preg can be handled separately and be stored.

(41) In FIG. 2b, a core 2 is arranged on the first layer 3. The core 2 may be of the type described above with reference FIGS. 1a-e. A first surface of the core 2 is abutting the first layer 3.

(42) In FIG. 2c, a second mix 1 is applied on a second surface of the core 2 for forming a decorative layer 12. The second mix 1 may be scattered on the second surface of the core 2. The second mix 1 may comprise lignocellulosic or cellulosic particles, a binder, preferably a thermosetting binder, and optionally wear resistant particles. The second mix may further comprise pigments. A print 4 may be printed into the second mix 1, preferably by means of digital printing. The second mix 1 may be applied as one or several layers to form a second layer.

(43) As an alternative or complement to applying a second mix 1, the decorative layer 12 may be a laminate, as shown in FIG. 3. In this embodiment, a dcor paper 21 is arranged on the second side of the core 2. An overlay paper 22 may be arranged on the dcor paper 21. The overlay paper 22 may comprise wear resistant particles. The dcor paper 21 and/or the overlay paper 22 may be impregnated with a binder, such as a thermosetting binder, or may be unimpregnated. If using unimpregnated papers, a binder may be applied between the core and the dcor paper, and/or between the dcor paper and the overlay paper, and/or on the overlay paper.

(44) As further alternatives, the decorative layer 12 may be a veneer layer, a wooden layer, a layer of thermoplastic material, etc. Any such layer may be combined with a powder based layer.

(45) The core 2 with the decorative layer 12 and the first layer 3 adapted to form a balancing layer 13 is thereafter fed into a press where the layers are cured under heat and pressure. Thereby, a building panel 6 having a balancing layer 13 is formed, as shown in FIG. 2d.

(46) FIG. 3 shows a building panel 6 having a core 2, a decorative layer 12 and a balancing layer 13. The core 2 may be a board, such as a wood based board. The wood based board may, for example, be a HDF, MDF, particle board, OSB, plywood, etc., or a WPC (Wood Plastic Composite). The core may also be a thermoplastic core.

(47) The balancing layer 13 is arranged on a first surface of the core 2, adapted to face the subfloor when the building panel installed as a floor panel. The balancing layer 13 is formed of a first mix 3 of the type described above, comprising particles formed from production waste and a thermosetting binder.

(48) The decorative layer 12 is arranged on a second surface of the core 2, adapted to face the interior of a room when the building panel is installed as floor panel. The decorative layer 12 comprises a dcor paper 21 and an overlay paper 22. The dcor paper 21 comprises a print. The dcor paper 21 and the overlay paper 22 are preferably resin impregnated. The overlay paper 22 preferably comprises wear resistant particles, such as corundum.

(49) In an alternative embodiment, the particles formed from production waste of the above described type and the binder of the above described type is applied to the core separately, and are not mixed prior to being applied to the core.

(50) In the above description, balancing layer is used as equivalent to any protective layer.

(51) It is contemplated that there are numerous modifications of the embodiments described herein, which are still within the scope of the disclosure as defined by the appended claims.

(52) It is contemplated that no additional thermosetting binder is added to the particles formed from production waste comprising resin impregnated paper. Thereby, particles formed from processed production waste comprising resin impregnated paper forms the balancing layer. Substantially uncured resin in the production waste formed from resin impregnated paper may create the counteracting forces of the balancing layer such that no separate binder has to be added to the particles formed from production waste.

EXAMPLES

(53) In the examples, production waste from the following resin impregnated papers were used: Backing paper having a paper weight of 140 g/m2 impregnated with 170 g/m2 melamine formaldehyde resin, which has been stored approximately one year. Dcor paper having a paper weight of 80 g/m2 impregnated with 80 g/m2 melamine formaldehyde resin, which has been stored approximately one year. Overlay paper having a paper weight of 25 g/m2 impregnated with 75 g/m2 melamine formaldehyde resin, which has been stored over one year.

(54) The papers were divided into coarse particles and then milled in a hammer mill to a powder having a particle size of less than 1000 m.

(55) A powder backing mix was prepared comprising 56 wt % of spray-dried melamine formaldehyde resin (MF), 1 wt % Al2O3, 3 wt % pigments and 40 wt % of cellulosic or lignocellulosic particles.

(56) Eight different mixes were prepared, wherein the powder backing mix was mixed with a varying amount of particles formed from production waste comprising resin impregnated paper according to the following.

(57) TABLE-US-00001 Production waste from resin impregnated papers Powder backing mix Example 1 0 wt % 100 wt % Example 2 5 wt % 95 wt % Example 3 10 wt % 90 wt % Example 4 25 wt % 75 wt % Example 5 50 wt % 50 wt % Example 6 75 wt % 25 wt % Example 7 90 wt % 10 wt % Example 8 100 wt % 0 wt %

(58) 450 g/m2 of each mix was applied on a HDF board having a thickness of 9.7 mm for forming a balancing layer. Water was applied on the mix in an amount of approximately 20 g/m2. The board having the mix applied thereon was pressed at 40 bar during 35 seconds at a temperature of 160 C.

(59) All resulting boards having a balancing layer formed by any one of the eight examples created a counteracting force, resulting in a board having a convex shape. All eight examples resulted in counteracting forces of comparable strength to a conventional backing paper or a powder backing layer of the type disclosed in WO2012/141647, which hereby is incorporated by reference in its entirety.