Method for producing a panel with a wood based core and a surface layer comprising a thermosetting resin
View Patent ↗A method for forming of a building panel with a surface including a thermosetting resin such that tension created during curing of the surface is reduced or eliminated.
1. Method for producing a panel with a wood based core and a surface layer comprising a thermosetting resin, wherein the method comprises the steps of:
curing and connecting the surface layer to the core while applying heat and pressure in a first main pressing step, thus raising a temperature of the surface layer above an initial temperature;
while the panel is still above the initial temperature from the first pressing step, applying a bending force on the panel in a second pressing step to bend the panel such that an uppermost surface of the panel is convex and a lowermost surface of the panel is concave; and
releasing the bending force such that the panel springs back to an essentially flat shape.
2. The method as claimed in claim 1 , wherein the method further comprises the step of decreasing the surface temperature while applying the bending force.
3. The method as claimed in claim 2 , wherein the surface temperature decrease is about 20° C.
4. The method as claimed in claim 2 , wherein the surface temperature decrease is more than 20° C.
5. The method as claimed in claim 1 , wherein the thermosetting resin is a melamine formaldehyde resin.
6. The method as claimed in claim 1 , wherein the bending is at least about 3 cm/m.
7. The method as claimed in claim 1 , wherein the surface layer comprises wood fibres and wear resistant particles.
8. The method as claimed in claim 1 , wherein the surface layer comprises impregnated paper, the wood based core comprises a high-density fibreboard (HDF) core, and the impregnated paper is bonded to the HDF core.
9. The method as claimed in claim 1 , wherein the surface layer comprises wood fibres, wear resistant particles and colour pigments.
10. The method as claimed in claim 1 , wherein the surface layer comprises a powder based layer, the powder comprising wood fibers, wear resistant particle and colour pigments.
11. The method as claimed in claim 1 , wherein the panel is a building panel.
12. The method as claimed in claim 1 , wherein the panel is a floor panel.
13. The method as claimed in claim 1 , wherein the bending force is applied to at least two opposite edge portions of the panel.
14. The method as claimed in claim 1 , wherein the panel is rectangular and the bending force is applied to both sets of opposite edge portions of the panel.
15. The method as claimed in claim 1 , wherein the bending force is applied with a first press table on the uppermost surface of the panel and a second press table on the lowermost surface of the panel.
16. The method as claimed in claim 15 , wherein the first and second press tables are curved in two perpendicular directions, such that bending is made along and across the panel.