Wood fibre based panels with a thin surface layer

1. A method of manufacturing a floor board comprising a wood fibre based core, a thin surface layer and a sub layer between the surface layer and the core, the sub layer comprises wood fibres and a binder, wherein the method comprises the steps of:

mixing particles comprising wood fibres and an uncured binder for the sub layer;

applying the wood fibres and the uncured binder in a powder form for the sub layer on the core;

applying a surface layer on the wood fibres and the uncured binder; and

pressing:

the core,

the surface layer, and

the wood fibres and the uncured binder, in powder form, under increased pressure and temperature with an embossed pressing matrix such that the surface layer obtains upper portions and embossed portions lower than the upper portions, such that the embossed portions extend into the sub layer, and forming them into a floor board by curing the binder.

2. The method as claimed in claim 1 , wherein the core is HDF.

3. The method as claimed in claim 1 , wherein the thin surface layer has a thickness of about 0.3-1.0 mm.

4. The method as claimed in claim 1 , wherein the binder in the sub layer is a thermosetting resin.

5. The method as claimed in claim 1 , wherein the method further comprises applying water or a liquid resin on the core or into the fibres of the sub layer prior to pressing.

6. The method as claimed in claim 1 , wherein the surface layer comprises a homogenous mix of wood fibre particles, wear resistant particles, binders and colour pigments.

7. The method as claimed in claim 6 , wherein the wear resistant particles comprise aluminum oxide.

8. The method as claimed in claim 1 , wherein the surface layer comprises a binder of a thermosetting resin.

9. The method as claimed in claim 1 , wherein the surface layer comprises a binder of a thermoplastic resin.

10. The method as claimed in claim 1 , wherein the surface layer is a printed paper with an overlay.

11. The method as claimed in claim 1 , wherein the surface layer is a wood veneer.

12. The method as claimed in claim 1 , wherein the method comprises a machining operation comprising forming the floor board to a floor panel with mechanical locking systems at opposite edges.

13. The method as claimed in claim 1 , wherein the step of applying the wood fibres and the binder comprises scattering the wood fibres and the binder with a roller comprising needles or engraved protruding portions.

14. The method as claimed in claim 13 , wherein the amount of needles or the engraved protruding portions is about 40-120 per cm 2 .

15. The method as claimed in claim 1 , wherein the step of applying the wood fibres and the binder comprises scattering a dry powder mixture of the wood fibres and the binder onto the core.

16. The method as claimed in claim 1 , wherein the wood fibres have an average length to thickness ratio of about 30 or smaller.

17. The method as claimed in claim 1 , wherein the wood fibres have an average length to thickness ratio of about 10 or smaller.

18. The method as claimed in claim 1 , wherein the wood fibres have an average length smaller than 0.5 mm.

19. The method as claimed in claim 1 , wherein the wood fibres have an average length of 0.1 to 0.3 mm.

20. The method as claimed in claim 1 , wherein the sub layer comprises about 70-85% (weight) wood fibers and about 15-30% (weight) melamine resin.

21. The method as claimed in claim 1 , wherein the step of applying the surface layer comprises scattering a dry powder mixture of wood fibre particles, wear resistant particles, binders and colour pigments.