Powder overlay

Abstract

A method is disclosed of manufacturing a transparent wear resistant surface layer (1). The method may include the steps of, applying a decorative material on a carrier, applying a dry powder layer comprising a mix of processed wood fibers, binder and wear resistant particles above the decorative layer, curing the mix to a decorative surface, including the transparent wear resistant layer, by applying heat and pressure on the mix. In a preferred embodiment the method includes the step of pressing the mix against an embossed matrix to create an embossed decorative surface with high wear resistance.

Claims

1. A method of manufacturing a building panel, wherein the method comprises the steps of: applying a first layer on a carrier; applying a dry powder layer, comprising a binder and wear resistant particles, on the first layer, the binder being a thermosetting resin in dry powder form; and applying heat and pressure on the dry powder layer to obtain a transparent wear resistant layer.

2. The method according to claim 1, wherein the wear resistant particles comprise aluminium oxide and/or silica.

3. The method according to claim 1, wherein the dry powder layer further comprises processed wood fibres.

4. The method according to claim 1, wherein the first layer is a decorative layer.

5. The method according to claim 4, wherein the decorative layer is a printed paper.

6. The method according to claim 4, wherein the decorative layer is wood veneer.

7. The method according to claim 4, wherein the decorative layer is a paper.

8. The method according to claim 4, wherein the decorative layeris a scattering of decorative mix.

9. The method according to claim 4, wherein the decorative layer is cork.

10. The method as claimed in claim 1, wherein the carrier is a wood based board.

11. The method as claimed in claim 1, wherein the carrier is an HDF or MDF board.

12. The method as claimed in claim 1, wherein the pressings step comprises pressing the dry powder layer against an embossed matrix.

13. The method as claimed in claim 12, wherein the pressing against the embossed matrix creates an embossing depth that exceeds the combined thickness of the first layer and the transparent wear layer.

14. The method as claimed in claim 1, wherein the first layer is applied on the carrier before the dry powder layer is applied on the first layer.

15. A method of manufacturing a building panel, wherein the method comprises the steps of: applying a first layer on a carrier; applying a dry powder layer, comprising a binder and wear resistant particles, on the first layer; and applying pressure on the dry powder layer to form the dry powder layer into a transparent wear resistant layer so that the building panel is manufactured comprised of the carrier, the first layer on the carrier, and the transparent wear resistant layer on the first layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will in the following be described in connection to preferred embodiments and in greater detail with reference to the appended exemplary drawings, wherein:

(2) FIG. 1 illustrates a conventional laminate floor panel with an embossed portion; and

(3) FIG. 2 illustrates an improved laminate floor with embossed portions.

DETAILED DESCRIPTION OF EMBODIMENTS

(4) A laminate floor having good mechanical wear properties are made from the application of heat and pressure to layers of various types of sheets of papers over which a powder layer is scattered. The sheets are positioned over a core, such as a medium or high density fibre board. Under the core one or more sheets of paper can be positioned. The sheets are made using standard papermaking techniques and chemistry and are typically impregnated using standard impregnation techniques and chemistry. In an embodiment the powder layer is composed of a homogenous mixture of powder resin, fibres and hard particles. The powder resin is preferably a thermoset resin such as amino resin or a mixture of such resins. A preferred resin is melamine formaldehyde resin. The fibres are preferably transparent such as processed wood fibres but also other transparent fibres such as glass fibres can be used. Fibres having limited transparency such as various inorganic fibres, metal fibres or unprocessed wood fibres can be used but would not yield the desired transparency of the protective layer. Preferred hard particles to yield the final good mechanical wear properties include aluminum oxide, silicon oxide and mixtures thereof. The use of heat and pressure convert the layers of sheets and the scattered powder layer into a laminate.

(5) A typical laminate floor (FIG. 1) is composed from top and bottom with the following layers: (2) an overlay sheet composed of melamine resin impregnated cellulose fibres in which abrasive particles are incorporated, (3) a d?cor sheet composed of melamine resin impregnated cellulose fibres, (4) a core material such as high density fibre board. A balancing sheet composed of melamine resin impregnated cellulose fibres is typically used on the backside of the panel. A laminate floor typically has embossed portions (6) extending below the main surface (1). If the embossed portions extend to far from the main surface poor surface appearance can occur due to the limitation of the impregnated papers.

(6) An improved laminate floor (FIG. 2) according to one non-restrictive embodiment of the invention comprises from top to bottom the following layers: (5) a protective powder layer, powder overlay, composed of melamine resin powder, processed wood fibres and abrasive particles, (3) a d?cor sheet composed of melamine resin impregnated cellulose fibres, (7) an optional powder layer comprising of melamine resin powder and processed wood fibres, (4) a core material such as high density fibre board. A balancing sheet composed of melamine resin impregnated cellulose fibres is typically used. Since the protective powder layer does not have a restricted movement in neither horizontal nor vertical directions embossed potions can be found both below (6a) and above (6b) the main surface (1). The resulting products have a higher amount of the protective melamine resins and aluminum oxide particles in the protruding surface portion (6b) giving an improved wear resistance compared to what is found with conventional overlays.

(7) The impregnation of overlay papers are typically made in impregnation lines such as for example described in US 2009/0208646 A1. Such impregnation lines require investments and handling of impregnation fluids that typically have limited shelf life. Such a process could be improved by the use of a powder overlay.

Example 1: Direct Laminate Product Having a Conventional Overlay (Comparative Example)

(8) A laminate product comprising a HDF carrier board, a balancing paper, a printed melamine impregnated paper and an overlay was pressed in a short cycle press using a force of 40 kg/cm.sup.2 for 25 seconds at a surface temperature of 160? C. The press plate was a virtually smooth glossy plate.

(9) The resulting product was a laminated surface having an abrasion resistance exceeding the demands for AC3 according to the test method in EN13329:2006 (E) with a good surface appearance.

Example 2: Deeply Embossed Laminate Product Having a Conventional Overlay (Comparative Example)

(10) A laminate product comprising a HDF carrier board, a balancing paper, a printed melamine impregnated paper and an overlay was pressed in a short cycle press using a force of 40 kg/cm.sup.2 for 25 seconds at a surface temperature of 160? C. The press plate was a deeply structured plate with parts having 0.7 mm depth.

(11) The resulting product was a laminated surface having an abrasion resistance failing the demands for AC2 according to the test method in EN13329:2006 (E). In addition the surface appearance was not good enough since the paper sheets of the laminate cracked at the large embossings.

Example 3: Deeply Embossed Direct Laminate Product Having a Protective Layer Made with Regular Fibres (Comparative Example)

(12) A laminate product comprising a HDF carrier board, a balancing paper, a printed melamine impregnated paper and 300 g/m.sup.2 of a protective layer comprising a homogenous mixture of recycled fibres that have not been processed, melamine powder resins and aluminum oxide particles was pressed in a short cycle press using a force of 40 kg/cm.sup.2 for 25 seconds at a surface temperature of 160? C. The press plate was a virtually smooth press plate.

(13) The resulting product was a laminated surface having an abrasion resistance passing the demands for AC6 according to the test method in EN13329:2006 (E). The surface appearance was not good enough since the fibres in the protective layer were visible.

Example 4

(14) Deeply embossed direct laminate having a protective Layer as per an embodiment of the disclosure.

(15) A laminate product comprising a HDF carrier board, a balancing paper positioned under the HDF, 1000 g/m.sup.2 of a scattered sub layer comprising a homogenous mixture of recycled fibres and amino resins, scattered over the HDF, a melamine resins impregnated printed paper positioned over the scatted sub layer and 300 g/m.sup.2 of a protective layer comprising a homogenous mixture of processed fibres, melamine powder resins and aluminum oxide particles, scattered over the printed melamine impregnated paper, was pressed in a short cycle press using a force of 40 kg/cm.sup.2 for 25 seconds at a surface temperature of 160? C. The press plate was a deeply structured plate with parts having 0.7 mm depth.

(16) The resulting product was a laminated surface having an abrasion resistance passing the demands for AC3 according to the test method in EN13329:2006 (E). The surface appearance was good enough since the fibres in the protective layer was not visible and no cracks of overlay paper were found in the deep embossed parts of the surface.

Example 5: Deeply Embossed Paper Free Building Panel Having a Protective Layer as Per an Embodiment of the Disclosure

(17) 150 g/m.sup.2 of a protective layer comprising a homogenous mixture of processed fibres, melamine powder resins and aluminum oxide particles, scattered over 150 g/m.sup.2 of a decorative layer comprising a homogenous mixture of processed fibres, melamine powder resins, pigment particles and aluminum oxide particles, scattered over 500 g/m.sup.2 of a second decorative layer comprising a homogenous mixture of processed fibres, melamine powder resins, pigment particles and aluminum oxide particles was pressed in a short cycle press using a force of 40 kg/cm.sup.2 for 25 seconds at a surface temperature of 160? C. The press plate was a deeply structured plate with parts having 0.7 mm depth.

(18) The resulting product was a deeply structured paper free laminate having an abrasion resistance passing the demands for AC6 according to the test method in EN13329:2006 (E). The initial surface appearance was excellent since the protective layer protects the surface from micro scratches that typically give products an early worn appearance.

Example 6: Wood Panel Having a Protective Layer as Per an Embodiment of the Disclosure

(19) A sanded wood panel was scattered with 150 g/m.sup.2 of a protective layer comprising a homogenous mixture of processed fibres, melamine powder resins and aluminum oxide particles. The product was compressed at 20 bars for 30 seconds at 160? C. using a smooth glossy press plate.

(20) The resulting product was a clear glossy wood product having excellent chemical and abrasion resistance.