METHOD FOR COATING A BUILDING PANEL AND A BUILDING PANEL

Abstract

A method for coating a building panel, the method including applying a first coating fluid including an organic binder on a surface of the building panel to obtain at least one coating layer, and applying barrier components and photocatalytic particles, preferably TiO.sub.2, on the at least one coating layer. Also, such a building panel.

Claims

1. A building panel comprising a surface, the building panel comprising: at least one radiation cured coating layer comprising an organic binder, wherein said at least one coating layer is arranged on said surface, and at least one overlying layer comprising barrier components and photocatalytic particles wherein barrier components prevent the photocatalytic particles from degrading the organic binder of said at least one coating layer, and wherein said at least one overlying layer is arranged on said at least one coating layer.

2. A building panel according to claim 1, wherein said at least one overlying layer comprises a barrier layer comprising the barrier components and a photocatalytic layer comprising the photocatalytic particles, wherein the barrier layer is arranged between said at least one coating layer and the photocatalytic layer.

3. A building panel according to claim 2, wherein an area of mixed barrier and photocatalytic particles is provided between the barrier layer and the photocatalytic layer.

4. A building panel according to claim 1, wherein said at least one coating layer is a UV cured coating layer.

5. A building panel according to claim 1, wherein the organic binder comprises an acrylate or methacrylate monomer, or an acrylate or methacrylate oligomer.

6. A building panel according to claim 5, wherein said acrylate or methacrylate monomer or oligomer is an epoxy (meth)acrylate, an urethane (meth)acrylate, a polyester (meth)acrylate, a polyester (meth)acrylate, a polyether (meth)acrylate, an acrylic (meth)acrylate, a silicone (meth)acrylate, a melamine (meth)acrylate, or a combination thereof.

7. A building panel according to claim 1, wherein the surface of the building panel comprises solid wood, wood veneer, wood-based board, cork, linoleum, thermoplastic material, thermosetting material, or paper.

8. A building panel according to claim 1, wherein the barrier components comprise a silicium containing compound such as SiO.sub.2, colloidal SiO.sub.2, functional nanoscaled SiO.sub.2, silicone resin, organofunctional silanes, and/or colloidal silicic acid silane and/or a combination of said compounds.

9. A building panel according to claim 1, wherein the building panel is a floor panel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The present invention will by way of example be described in more detail with reference to the appended schematic drawings, which show embodiments of the present invention.

[0075] FIG. 1 illustrates a method for coating a building panel according to one embodiment of the invention.

[0076] FIG. 2a illustrates a wooden building panel according to one embodiment of the invention.

[0077] FIG. 2b illustrates a wooden building panel according to one embodiment of the invention.

[0078] FIG. 3a illustrates a thermoplastic building panel according to one embodiment of the invention.

[0079] FIG. 3b illustrates a thermoplastic building panel according to one embodiment of the invention.

[0080] FIG. 4a illustrates a linoleum building panel according to one embodiment of the invention.

[0081] FIG. 4b illustrates a linoleum building panel according to one embodiment of the invention.

DETAILED DESCRIPTION

[0082] A method for coating a building panel will now be described with reference to FIG. 1. FIG. 1 illustrates a coating process for a building panel in a coating line. The building panel 1 may be a floor panel, a wall panel, a furniture component, etc. The building panel 1 may be solid or may comprise more than one layer, i.e., such as a laminated panel. The first coating fluid is applied on a surface 11 of the building panel 1 adapted to face an interior space of a room, for example as an upper surface of a floor panel. The surface 11 comprises preferably a decorative surface of the building panel. The surface 11 provides the building panel with its decorative properties. The surface 11 of the building panel 1 may comprises a wood-based material such as solid wood, wood veneer, a wood fibre-based board. The decorative surface of the building panel 1 may comprises cork, linoleum, thermoplastic material, thermosetting material, or paper.

[0083] The coating line comprises several application apparatuses and a conveyor belt 2 adapted to convey the building panel 1. The conveyor belt 2 preferably conveys the building panel 1 at a constant speed.

[0084] In the coating line, a first coating fluid is applied to the surface 11 of a building panel 1 by a coating apparatus 3. The first coating fluid is preferably applied on the surface 11 of the building panel 1 by means of spraying, roller coating, etc. The first coating fluid is preferably uniformly applied to the surface 11 of the building panel 1. The first coating fluid is applied such that at least one coating layer is formed on the surface 11 of the building panel 1. The coating layer is preferably continuous. The coating layer covers preferably the entire surface 11 of the building panel 1. The coating layer may be a lacquer layer or varnish layer. The coating layer is adapted to protect the surface 11 of the building panel, which preferably is a decorative surface. The coating layer is adapted to give the surface 11 wear resistant properties.

[0085] The coating layer may comprise one or several layers, for example a base coating layer and a top coating layer. A person skilled in the art realises that also the base coating layer and/or the top coating layer may comprise one or more layers. In FIG. 1, only one coating apparatus 3 is shown. A person skilled in the art appreciates that if more than one layer is to be applied, more than one coating apparatus 3 may be provided or the building panel may pass the coating apparatus 3 more than one time. The base coating layer may be cured before applying a top coating layer.

[0086] The coating fluid comprises an organic binder. The organic binder preferably comprises an acrylate or methacrylate monomer or an acrylate or methacrylate oligomer. The acrylate or methacrylate monomer or oligomer may be an epoxy acrylate, an epoxy methacrylate, a urethane acrylate, a urethane methacrylate, a polyester acrylate, a polyester methacrylate, a polyether acrylate, a polyether methacrylate, an acrylic acrylate, an acrylic methacrylate, a silicone acrylate, a silicone methacrylate, a melamine acrylate, a melamine methacrylate, or a combination thereof. In another embodiment, the organic binder comprises an unsaturated polyester.

[0087] The above examples are examples of monomers and oligomers polymerised by radical reaction.

[0088] The above monomers and oligomers form a component of the coating fluid. The coating fluid may further comprise initiators such as photo-initiators, pigments, fillers, amine synergists, reactive diluents, wetting agent, additives, etc. The coating fluid may be a waterborne, solvent borne, or 100% UV dispersion.

[0089] The coating fluid may be a radiation curing coating fluid, preferably UV curing coating fluid or electron beam curing coating fluid. Preferably, the coating fluid comprises a urethane-based acrylate monomer or oligomer.

[0090] In one embodiment (not shown), the at least one coating layer may be at least partly cured by a curing device, for example a UV lamp. By partly cured is meant that the coating layer is gelled but not completely cured. If more than one coating layer has been applied to the building panel 1, the underlying coating layers may already have been cured but the uppermost coating layer may be wet or partly cured.

[0091] Barrier components are thereafter applied to the building panel 1 by means of an application device 5. The barrier components are adapted to prevent photocatalytic particles from degrading the organic binder of the coating layer. The barrier components comprise silicium containing compound. Examples of such a silicium containing compound are SiO2, colloidal SiO2, functional nanoscaled SiO2, silicone resin, organofunctional silanes, and/or colloidal silicic acid silane and/or a combination of said compounds.

[0092] The barrier components are preferably applied as a barrier coating fluid comprising the barrier components. In the shown embodiment, the barrier coating fluid is applied wet-in wet, i.e., the underlying coating layer is not cured before application of the barrier coating fluid. The barrier coating fluid is preferably a waterborne dispersion having the barrier components dispersed therein. The barrier coating fluid may further comprise a wetting agent such as a non-ionic surfactant and/or other additives. The barrier coating fluid may be heat curing. The amount of the barrier coating fluid may be up to about 50 ml/m2, preferably up to about 40 ml/m2, more preferably up to about 30 ml/m2, and most preferably up to about 20 ml/m2. In one embodiment, the amount of said barrier coating fluid applied is up to about 15 ml/m2, up to about 10 ml/m2, up to about 5 ml/m2, up to about 1 ml/m2.

[0093] In the shown embodiment, the barrier coating fluid is applied by spraying on the coating layer by a spraying device 5. The size of the droplet of the barrier coating fluid is up to about 200 .Math.m, up to about 150 .Math.m, up to about 100 .Math.m, up to about 50 .Math.m, up to about 25 .Math.m or up to about 10 .Math.m.

[0094] The concentration of the barrier components in the barrier coating fluid may be up to about 40 wt%, such as about 30 wt%, preferably up to about 20 wt%, such as about 10 wt%, for example up to about 5 wt%.

[0095] The barrier coating fluid forms a barrier layer on the coating layer. If more than one coating layer is provided, the barrier layer is arranged on the top coating layer. Preferably, the barrier layer is at least one monolayer of barrier components. The barrier layer is preferably continuous over the coating layer. The barrier components may be at least partly embedded in the coating layer. The thickness of the barrier layer may be up to about 1 .Math.m, up to about 0.800 .Math.m, up to about 0.600 .Math.m, up to about 0.400 .Math.m, up to about 0.200 .Math.m, up to about 0.100 .Math.m or up to about 0.05 .Math.m.

[0096] If the coating layer is not cured before applying the barrier components, or only partly cured or semi-cured, the barrier components may engage with the underlying coating layer. The underlying coating layer and the barrier layer may not be completely separate. A portion where the coating layer and the barrier layer are mixed may be formed.

[0097] In a preferred embodiment, the barrier layer is dried before applying the photocatalytic particles. In FIG. 1, a heating apparatus 6, preferably an IR heating apparatus, is arranged after the spraying device 5 adapted to spray the barrier coating fluid.

[0098] The concentration of the barrier components in the barrier layer may be at least 70%, more preferably at least 80% and most preferably at least 90%. In one embodiment, the barrier layer substantially consists of the barrier components. By substantially consist is meant that additives and a binder may be present in a small amount compared to the amount of the barrier components.

[0099] Photocatalytic particles are thereafter applied on the barrier layer. The photocatalytic particles are preferably photocatalytic nanoparticles, more preferably TiO2. The photocatalytic particles may have a size of less than 100 nm, preferably less than 50 nm, more preferably less than 30 nm, most preferably less than 20 nm, as measured when being present in the photocatalytic coating fluid.

[0100] Preferably, the photocatalytic particles are applied as a photocatalytic coating fluid comprising the photocatalytic particles. The photocatalytic coating fluid may be a waterborne dispersion having the photocatalytic particles dispersed therein. The photocatalytic coating fluid may further comprise a wetting agent such as a non-ionic surfactant and/or other additives. The photocatalytic coating fluid may be heat curing. The concentration of the photocatalytic particles may be up to about 30 wt%, up to about 20, wt%, up to about 10 wt%, up to about 5 wt%, or up to about 1 wt%. The amount of the photocatalytic coating fluid applied may be up to about 50 ml/m2, preferably up to about 40 ml/m2, more preferably up to about 30 ml/m2, and most preferably up to about 20 ml/m2. In one embodiment, the amount of the photocatalytic coating fluid applied is up to about 15 ml/m2, up to about 10 ml/m2, up to about 5 ml/m2, up to about to 1 ml/m2.

[0101] The photocatalytic coating fluid may comprise an additive such as a wetting agent, preferably a non-ionic surfactant, in a concentration determined relative the concentration of photocatalytic particles in the photocatalytic coating fluid. In the photocatalytic coating fluid, the weight ratio (weight/weight) between the wetting agent such as a non-ionic surfactant and the photocatalytic particles may be 0,01-0,04, preferably 0,02-0,03.

[0102] In the shown embodiment, the photocatalytic coating fluid is applied by spraying on the barrier layer by a spraying device 7. The size of the droplet of the photocatalytic coating fluid is up to about 200 .Math.m, up to about 150 .Math.m, up to about 100 .Math.m, up to about 50 .Math.m, up to about 25 .Math.m or up to about 10 .Math.m.

[0103] The photocatalytic coating fluid applied forms a photocatalytic layer arranged on the barrier layer. The photocatalytic layer is preferably continuous over the barrier layer. The thickness of the photocatalytic layer may be up to about 1 .Math.m, preferably up to about 0.800 .Math.m, more preferably up to about 0.600 .Math.m, most preferably up to about 0.400 .Math.m, up to about 0.200 .Math.m, up to about 0.100 .Math.m or up to about 0.05 .Math.m.

[0104] The underlying barrier layer and the photocatalytic layer may not be completely separated. A portion where the coating layer and the barrier layer are mixed may be formed. An area of mixed barrier and photocatalytic particles may be provided in the border between the barrier layer and the photocatalytic layer. A part of the photocatalytic particles may be partly embedded by the barrier particles in the border between the barrier layer and the photocatalytic layer.

[0105] The photocatalytic layer is preferably dried, for example by a heating apparatus 8, preferably an IR heating apparatus, as shown in FIG. 1.

[0106] The at least one coating layer, the barrier layer and the photocatalytic layer are then cured in a curing apparatus 9. The coating layer may be completely cured by radiation curing, preferably UV curing or electron beam curing. In the embodiment shown in FIG. 1, the curing apparatus comprises an UV lamp 9 for curing the coating layer. The barrier layer and the photocatalytic layer are completely dried. Thereby, a building panel 1 having photocatalytic properties is obtained. The building panel 1 comprises a surface 11 provided with at least one coating layer, and an overlying layer comprising the barrier layer and the photocatalytic layer.

[0107] A building panel 1 having photocatalytic properties will now be described with reference to FIGS. 2a and b. The building panel 1 is preferably coated according to the method described above. The building panel 1 is a wooden panel, for example a wall panel, a floor panel, a furniture component. The building panel 1 may be of solid wood 12 as shown in FIGS. 2a and 2b. Alternatively, the building panel 1 may comprise a core provided with a surface layer of wood, for example a veneer layer (not shown). The building panel 1 may also be a wood-based panel, such as a MDF, HDF, OSB or particleboard. The building panel 1 may be a floor panel.

[0108] A surface 11 of the wooden building panel 1 is provided with at least one coating layer 13 and an overlying layer 14, preferably applied by above-described method. The coating layer 13 comprising an organic binder of the above-described type. The coating layer 13 may be a lacquer layer or a varnish layer. Preferably, the coating layer 13 comprises at least one base coating layer 13a and a least one top coating layer 13b as shown in FIGS. 2a and 2b. The coating fluid comprises preferably a urethane-based acrylate. The coating fluid is preferably UV curable.

[0109] In FIG. 2a, the overlying layer 14 is arranged on the top coating layer 13. The overlying layer 14 comprises a barrier layer 14a and a photocatalytic layer 14b. The barrier layer 14a comprises barrier components of the above-described type. The barrier layer 14a is arranged on the top coating layer 13b. The photocatalytic layer 14b comprising photocatalytic particles is arranged on the barrier layer 14a. The photocatalytic particles are of the above-described type.

[0110] In FIG. 2b, the overlying layer 14 is arranged on the top coating layer 13b. The overlying layer 14 comprises barrier components of the above-described type and photocatalytic particles of the above-described type. The barrier components and the photocatalytic particles are at least partly mixed. The overlying layer 14 comprises a lower part wherein the concentration of the barrier components is higher than the concentration of photocatalytic particles. The overlying layer 14 comprises an upper part wherein the concentration of the photocatalytic particles is higher than the concentration of barrier components. A mixed area may be provided comprising both barrier components and photocatalytic particles.

[0111] FIGS. 3a and 3b illustrate a building panel 1 in form of a floor panel 1′. The floor panel 1′ is preferably coated according to the above-described method. The floor panel 1′ may be a Luxury Vinyl Tile (LVT) or Luxury Vinyl Plank. The floor panel 1′ comprises a core 15, at least one surface layer 16, 17, at least one coating layer 13 and an overlying layer 14. A backing layer (not shown) may also be provided on the lower side of the core. The surface layer may comprise a décor layer 16 and a protective layer 17. A person skilled in the art appreciates that layers may be excluded, such as the protective layer and/or decorative layer. The core 15 comprises thermoplastic material. The thermoplastic material may be polyvinyl chloride (PVC) or polypropylene (PP). The core may further comprise a filler, for example calcium carbonate, and additives such as plasticizer, impact modifier, stabilizer, processing aids, pigment, lubricants, etc. Alternatively, the core 15 may be a Wood Plastic Composite (WPC) comprising a thermoplastic binder and wood fibres. The surface layer, such as a décor layer 16 comprises a thermoplastic material such as polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), or polyethylene terephthalate (PET). The décor layer 16 may further comprise additives such as a plasticizer. The décor layer 16 may be in form of a film or foil. The décor layer 16 preferably has a decorative print printed thereon. The protective layer 17 may be in form of a thermoplastic foil or film. The protective layer 17 comprises a thermoplastic material such as polyvinyl chloride (PVC), polyester, polypropylene (PP), polyethylene (PE), polystyrene (PS), polyurethane (PUR), or polyethylene terephthalate (PET). The protective layer 17 may further comprise additives such as a plasticizer.

[0112] The surface layer, for example the décor layer 16 or the protective layer 17, is provided with at least one coating layer 13 and an overlying layer 14, preferably applied by above-described method. The coating layer 13 comprising an organic binder of the above-described type. The coating layer 13 may be a lacquer layer or a varnish layer. The coating layer 13 may comprise at least one base coating layer and a least one top coating layer (not shown). The coating fluid comprises preferably a urethane-based acrylate. The coating fluid is preferable UV curable. It is also contemplated that the coating fluid may be applied directly on the décor layer 16, or directly on the core 15.

[0113] In FIG. 3a, the overlying layer 14 is arranged on the coating layer 14. The overlying layer 14 comprises a barrier layer 14a and a photocatalytic layer 14b. The barrier layer 14a comprises barrier components of the above-described type. The barrier layer 14a is arranged on the coating layer 13. The photocatalytic layer 14b comprising photocatalytic particles is arranged on the barrier layer 14a. The photocatalytic particles are of the above-described type.

[0114] In FIG. 3b, the overlying layer 14 is arranged on the coating layer 13. The overlying layer 14 comprises barrier components of the above-described type and photocatalytic particles of the above-described type. The barrier components and the photocatalytic particles are at least partly mixed. The overlying layer 14 comprises a lower part wherein the concentration of the barrier components is higher than the concentration of photocatalytic particles. The overlying layer 14 comprises an upper part wherein the concentration of the photocatalytic particles is higher than the concentration of barrier components. A mixed area may be provided comprising both barrier components and photocatalytic particles.

[0115] FIGS. 4a and 4b illustrate a building panel 1 in form of a floor panel 1′. The floor panel 1′ is preferably coated according to the above-described method. The floor panel 1′ is a linoleum floor panel. The floor panel 1′ may be of solid linoleum, or may be as shown in FIGS. 4a and b comprise a core 18 and a surface layer 19 of linoleum. The core 18 may be a wood-based panel such as MDF or HDF. A backing layer (not shown), for example a cork layer, may be arranged on a lower side of the core. The linoleum surface layer 19 may comprise wood flour, linseed oil, binder, a filler such as calcium carbonate and pigments.

[0116] The linoleum surface layer 19 is coated by at least one coating layer 13 and an overlying layer 14 comprising barrier components and photocatalytic particles, preferably by the above-described method. In FIGS. 4a and 4b, the coating layer 13 comprises a base coating layer 13a and a top coating layer 13b. The coating layer 13 comprises an organic binder of the above-described type. The coating layer 13 may be a lacquer layer or a varnish layer. The coating fluid comprises preferably a urethane-based acrylate. The coating fluid is preferable UV curable.

[0117] The overlying layer 14 is arranged on top of the top coating layer 13b. In the embodiment shown in FIG. 4a, the overlying layer 14 comprises a barrier layer 14a and a photocatalytic layer 14b. The barrier layer 14a comprises barrier components of the above-described type. The barrier layer 14a is applied on the top coating layer 13b. The photocatalytic layer 14b is applied on the barrier layer 14a. The photocatalytic layer 14b comprises photocatalytic particles of the above-described type.

[0118] In FIG. 4b, the overlying layer 14 is arranged on top of the top coating layer 13b. The overlying layer 14 comprises barrier components of the above-described type and photocatalytic particles of the above-described type. The barrier components and the photocatalytic particles are at least partly mixed. The overlying layer 14 comprises a lower part wherein the concentration of the barrier components is higher than the concentration of photocatalytic particles. The overlying layer 14 comprises an upper part wherein the concentration of the photocatalytic particles is higher than the concentration of barrier components. A mixed area may be provided comprising both barrier components and photocatalytic particles.

[0119] The floor panel 1′ shown in FIGS. 4a and 4b is provided with a mechanical locking system. The floor panel 1′ is provided with a mechanical locking system for locking the floor panel 1′ to adjacent floor panels horizontally and/or vertically. The mechanical locking system comprises at a first edge of the floor panel a tongue groove 26 adapted to receive a tongue 25 of an adjacent floor panel, and a locking strip 22 provided with a locking element 23 adapted to cooperate with a locking groove 24 of an adjacent floor panel and lock the floor panel 1′ in a horizontal direction to the adjacent floor panel. The mechanical locking system further comprises at a second edge a locking groove 24 adapted to receive a locking element 23 of an adjacent floor panel, and a tongue 25 adapted cooperate with a tongue groove 26 of an adjacent floor panel and lock the panel 1′ in a vertical direction. The mechanical locking system is formed in the core 18 of the floor panel 1′. Both long side edges and short side edges of the floor panel 1′ may be provided with a mechanical locking system. Alternatively, long side edges of the floor panel 1′ may be provided with the mechanical locking system for horizontally and vertically locking, and the short side edges may be provided with a mechanical locking system for horizontally locking only. It is also contemplated that other locking systems may be used, for example of the type disclosed in WO2007/015669.

[0120] Any of the building panels described above with reference to FIGS. 2a-b and FIGS. 3a-b may be provided with a mechanical locking system as described above with reference to FIGS. 4a and 4b.

[0121] It is contemplated that there are numerous modifications of the embodiments described herein, which are still within the scope of the invention as defined by the appended claims. For example, in the figures, said at least one coating layer and the overlying layer are shown as separate layers. However, it is contemplated that the layers may not be present as separate layers and may be at least partly integrated into for example the underlying coating layer.

EXAMPLES

LVT - Reference 1

[0122] A coating layer in form of 9 g/m2of a UV-curing lacquer was applied on a Luxury Vinyl Tile (LVT) comprising a core, a décor layer, and a protective layer. The coating layer was applied on the protective layer. The UV-curing lacquer was cured at a speed of 10 m/min. Two mercury lamps were used both having a light effect of 120 W.

[0123] The product produced was put under UV light and checked for hydrophilicity. After 1 week in UV light the product showed a hydrophobic behaviour.

LVT - Reference 2

[0124] A coating layer in form of 9 g/m2of a UV-curing lacquer was applied on a Luxury Vinyl Tile (LVT) comprising a core, a décor layer, and a protective layer. The coating layer was applied on the protective layer. 5 g of a photocatalytic coating fluid comprising 1.5 wt-% nanofluid comprising photocatalytic nanoparticles, wherein the nanofluid is of the type described in patent application WO 2010/110726, and 0.5 wt-% BYK-348 was applied on the UV coating layer. The UV-curing lacquer was cured at a speed of 10 m/min. Two mercury lamps were used both having a light effect of 120 W.

[0125] The product produced was put under UV light and checked for hydrophilicity. After 1 week in UV light the product showed a hydrophilic behaviour. However, the product has started to chalk, since the photocatalytic particles have started to degrade the organic binder of the UV-curing coating layer.

LVT - With Barrier Layer and Photocatalytic Layer

[0126] A coating layer in form of 9 g/m2of a UV-curing lacquer was applied on a Luxury Vinyl Tile (LVT) comprising a core, a décor layer, and a protective layer. The coating layer was applied on the protective layer. 5 g of a barrier coating fluid comprising 5 wt-% SiO2 as barrier components was sprayed into the UV-curing lacquer. 5 g of a photocatalytic coating fluid comprising 1.5 wt-% nanofluid comprising photocatalytic nanoparticles, wherein the nanofluid is of the type described in patent application WO 2010/110726, and 0.5 wt-% BYK-348 was applied on the barrier coating. The UV-curing lacquer, the barrier coating fluid and the photocatalytic coating fluid were cured at a speed of 10 m/min. Two mercury lamps were used at 120 W each.

[0127] The product produced was put under UV light. After 1 week in UV light the product showed a hydrophilic behaviour with no deterioration of the lacquer.

Linoleum - Reference 1

[0128] A base coating layer in form of a 20-30 g/m2of a UV-curing base coating lacquer was applied on a linoleum floor panel comprising a core and a surface layer of linoleum. The UV-curing base coating lacquer was applied on the surface layer of linoleum. A top coating layer in form of 20-30 g/m2of a UV-curing top coating lacquer was applied on top of the base coating layer. The UV-curing lacquers were cured at a speed of 10 m/min using an Hg and a Ga lamp at 120 W.

[0129] The produced product was put under UV light. After 1 week in UV light the product showed a hydrophobic behaviour.

Linoleum - Reference 2

[0130] A base coating layer in form of a 20-30 g/m2of a UV-curing base coating lacquer was applied on a linoleum floor panel comprising a core and a surface layer of linoleum. The UV-curing base coating lacquer was applied on the surface layer of linoleum. A top coating layer in form of 20-30 g/m2of a UV-curing top coating lacquer was applied on top of the base coating layer. 5 g of a photocatalytic coating fluid comprising 5 wt-% nanofluid comprising photocatalytic nanoparticles, wherein the nanofluid is of the type described in patent application WO 2010/110726, and 0.5 wt-% BYK-348 on the UV curing lacquer. The UV-curing lacquers were cured at a speed of 10 m/min using an Hg and a Ga lamp at 120 W. The produced product was put under UV light.

[0131] After 1 week in UV light the product showed a hydrophilic behaviour. The product has started to chalk, since the photocatalytic particles have started to degrade the organic binder of the UV-curing lacquer.

Linoleum - With Barrier Layer and Photocatalytic Layer

[0132] A base coating layer in form of 20-30 g/m2of a UV-curing base coating lacquer was applied on a linoleum floor panel comprising a core and a surface of linoleum. The UV-curing base coating lacquer was applied on the surface layer of linoleum. A top coating layer in form of 20-30 g/m2of a UV-curing toping coat lacquer was applied on top of the base coating layer. 5 g of a barrier coating fluid comprising 5 wt-% SiO2 as barrier components was sprayed into the UV-curing lacquer layers. 5 g of a photocatalytic coating fluid comprising 5 wt-% nanofluid comprising photocatalytic nanoparticles, wherein the nanofluid is of the type described in patent application WO 2010/110726, and 0.5 wt-% BYK-348 was applied on the barrier coating. The UV-curing lacquer layers, the barrier coating fluid and the photocatalytic coating fluid were cured at a speed of 10 m/min using a Hg and a Ga lamp at 120 W. After 1 week in UV light the product showed a hydrophilic behaviour with no deterioration of the lacquer.

Wood Panel - Reference 1

[0133] A coating layer in form of 9 g/m2of a UV-curing lacquer was applied on a surface of a wooden building panel. The UV-curing lacquer was cured at a speed of 10 m/min. Two mercury lamps were used both having a light effect of 120 W.

[0134] The product produced was put under UV light and checked for hydrophilicity. After 1 week in UV light the product showed a hydrophobic behaviour.

Wood Panel - Reference 2

[0135] A coating layer in form of 9 g/m2of a UV-curing lacquer was applied on a surface of a wooden building panel. 5 g of a photocatalytic coating fluid comprising 1.5 wt-% nanofluid comprising photocatalytic nanoparticles, wherein the nanofluid is of the type described in Patent Application WO 2010/110726, and 0.5 wt-% BYK-348 was applied on the UV curing lacquer. The UV-curing lacquer was cured at a speed of 10 m/min. Two mercury lamps were used both having a light effect of 120 W.

[0136] The product produced was put under UV light and checked for hydrophilicity. After 1 week in UV light the product showed a hydrophilic behaviour. The product has started to chalk, since the photocatalytic particles have started to degrade the organic binder of the UV-curing lacquer.

Wood Panel - With Barrier Layer and Photocatalytic Layer

[0137] A coating layer in form of 9 g/m2of a UV-curing lacquer was applied on a surface of a wooden building panel. 5 g of a barrier coating fluid comprising 5 wt-% SiO2 as barrier components was sprayed into the UV-curing lacquer. 5 g of a photocatalytic coating fluid comprising 1.5 wt-% nanofluid comprising photocatalytic nanoparticles, wherein the nanofluid is of the type described in patent application WO 2010/110726, and 0.5 wt-% BYK-348 was applied on the barrier coating. The UV-curing lacquer, the barrier coating fluid and the photocatalytic coating fluid were cured at a speed of 10 m/min. Two mercury lamps were used at 120 W each.

[0138] The product produced was put under UV light. After 1 week in UV light the product showed a hydrophilic behaviour with no deterioration of the lacquer.

Embodiments

[0139] 1. A method for coating a building panel (1, 1′), comprising: [0140] applying a first coating fluid comprising an organic binder on a surface (11) of the building panel (1, 1′) to obtain at least one coating layer (13), and [0141] applying barrier components and photocatalytic particles, preferably TiO2, on said at least one coating layer (13).

[0142] 2. A method according to embodiment 1, wherein the step of applying the barrier components and the photocatalytic particles comprises: [0143] applying a barrier coating fluid comprising the barrier components on said at least one coating layer (13) to obtain a barrier layer (14a), and [0144] applying a photocatalytic coating fluid comprising the photocatalytic particles on said barrier layer (14a) to obtain a photocatalytic layer (14b).

[0145] 3. A method according to embodiment 1 or 2, wherein the first coating fluid is a radiation curing coating fluid, preferably UV curing coating fluid.

[0146] 4. A method according to any one of embodiments 1-3, wherein the organic binder comprises an acrylate or methacrylate monomer, or an acrylate or methacrylate oligomer.

[0147] 5. A method according to embodiment 4, wherein said acrylate or methacrylate monomer or oligomer is an epoxy (meth)acrylate, an urethane (meth)acrylate, a polyester (meth)acrylate, a polyester (meth)acrylate, a polyether (meth)acrylate, an acrylic (meth)acrylate, a silicone (meth)acrylate, a melamine (meth)acrylate, or a combination thereof.

[0148] 6. A method according to any one of embodiments 1-5, wherein the surface (11) of the building panel (1, 1′) comprises solid wood, wood veneer, wood-based board, cork, linoleum, thermoplastic material, thermosetting material, or paper.

[0149] 7. A method according to any one of embodiments 2-6, further comprising partly curing said at least one coating layer (13), preferably by radiation curing, more preferably by UV curing, prior to applying the barrier components and the photocatalytic particles.

[0150] 8. A method according to any one of embodiments 2-7, further comprising drying said barrier layer (14a), prior to applying the photocatalytic coating fluid.

[0151] 9. A method according to any one of embodiments 2-8, further comprising drying said photocatalytic layer (14b).

[0152] 10. A method according to any one of embodiments 2-9, further comprising curing said at least one coating layer (13), said barrier layer (14a) and/or said photocatalytic layer (14b).

[0153] 11. A method according to any one of embodiments 2-10, wherein the barrier and/or photocatalytic coating fluid(s) is (are) aqueous fluids.

[0154] 12. A method according to any one of embodiments 2-11, wherein the barrier and/or photocatalytic coating fluid(s) is (are) applied by spraying.

[0155] 13. A method according to any one of embodiments 1-12, wherein the barrier components comprise a silicium containing compound such as SiO2, colloidal SiO2, functional nanoscaled SiO2, silicone resin, organofunctional silanes, and/or colloidal silicic acid silane and/or a combination of said compounds.

[0156] 14. A building panel (1, 1′) comprising a surface (11), the building panel comprising: [0157] at least one radiation cured coating layer (13) comprising an organic binder, wherein said at least one coating layer (13) is arranged on said surface (11), and [0158] at least one overlying layer (14) comprising barrier components and photocatalytic particles, preferably TiO2, wherein barrier components prevent the photocatalytic particles from degrading the organic binder of said at least one coating layer (13), and wherein said at least one overlying layer (14) is arranged on said at least one coating layer (13).

[0159] 15. A building panel according to embodiment 14, wherein said at least one overlying layer (14) comprises a barrier layer (14a) comprising the barrier components and a photocatalytic layer (14b) comprising the photocatalytic particles, wherein the barrier layer (14a) is arranged between said at least one coating layer (13) and the photocatalytic layer (14b).

[0160] 16. A building panel according to embodiment 15, wherein an area of mixed barrier and photocatalytic particles is provided between the barrier layer (14a) and the photocatalytic layer (14b).

[0161] 17. A building panel according to any one of embodiments 14-16, wherein said at least one coating layer is a UV cured coating layer.

[0162] 18. A building panel according to any one of embodiments 14-17, wherein the organic binder comprises an acrylate or methacrylate monomer, or an acrylate or methacrylate oligomer.

[0163] 19. A building panel according to embodiment 18, wherein said acrylate or methacrylate monomer or oligomer is an epoxy (meth)acrylate, an urethane (meth)acrylate, a polyester (meth)acrylate, a polyester (meth)acrylate, a polyether (meth)acrylate, an acrylic (meth)acrylate, a silicone (meth)acrylate, a melamine (meth)acrylate, or a combination thereof.

[0164] 20. A building panel according to any one of embodiments 14-19, wherein the surface (11) of the building panel (1, 1′) comprises solid wood, wood veneer, wood-based board, cork, linoleum, thermoplastic material, thermosetting material, or paper.

[0165] 21. A building panel according to any one of embodiments 14-20, wherein the barrier components comprise a silicium containing compound such as SiO2, colloidal SiO2, functional nanoscaled SiO2, silicone resin, organofunctional silanes, and/or colloidal silicic acid silane and/or a combination of said compounds.

[0166] 22. A building panel according to any one of embodiments 14-21, wherein the building panel is a floor panel (1′).