Patent Description:
Conventional Medium Density Fibre boards (MDF), High Density Fibre boards (HDF) and particle boards generally have a brown colour, which may vary with the type of wood raw material used. MDF and HDF are often used as a core material to which a veneer or laminate such as DPL (Direct Pressure Laminate) or HPL (High Pressure Laminate) is adhered. An alternative to attaching a laminate is to print directly on a HDF or MDF in order to reduce cost. However, the colour of the MDF or HDF makes it difficult to print pale décors since the colour of the MDF or HDF shines through the printed décor. Accordingly, it is difficult to print a paler colour than the colour of the HDF or MDF. Furthermore, a comparable large amount of ink may be required to obtain the desired décor due to the underlying colour of the HDF or MDF, which increases the cost of the décor.

It is known from <CIT> to produce a white wood-based board of bleached wood fibres and/or combined with beater dyeing with a white pigment. However, using bleached wood fibres and pigment result in a board produced to a considerable higher cost compared to a conventional MDF or HDF.

<CIT> describes an improved chipboard, which may have a white surface comprising wood flour and titanium dioxide. The white surface is obtained by a large amount of titanium dioxide.

<CIT> discloses a method of extruding a thermoplastic composite material containing a thermoplastic resin and a vegetable filler.

<CIT> discloses in one embodiment distributing a dried particle/resin mixture on a carrier consisting of a base paper in form of a web. The base paper may consist of Kraft paper impregnated with phenol-formaldehyde resin. The base paper web with the particle/resin mixture on top is fed between two settle belts of a continuous laminate press together with an uppermost primary surface layer. The primary surface layer consists of two so-called overlay papers in form of webs impregnated with melamine-formaldehyde.

It is an object of at least certain embodiments of the present invention to provide an improvement over the above described techniques and known art.

A further object of at least certain embodiments is to provide a wood-based board having a pale to white or coloured surface.

A further object of at least certain embodiments is to provide a wood-based board, which is suitable for being printed directly upon.

A further object of at least certain embodiments is to provide a wood-based board having a printable surface at a low cost.

A further object of at least certain embodiments is to provide a wood-based board on which pale or bright décors may be printed directly upon.

At least some of these and other objects and advantages that will be apparent from the description have been achieved by a method of manufacturing a wood-based board according to a first aspect, which does not form part of the claimed invention.

The method comprises applying at least one first fibre mat comprising a first mix comprising lignocellulosic particles and a first binder on a carrier, applying a second fibre mat comprising a second mix comprising cellulosic particles and a second binder on said at least one first fibre mat, and pressing said at least one first fibre mat into a base layer and the second fibre mat into a surface layer simultaneously, thereby forming a wood-based board.

The surface layer may be a top layer of the wood-based board.

Pressing preferably comprises applying heat and pressure. Pressing may comprise curing the first and second binder of the first and second fibre mat, respectively.

The second fibre mat is applied on said at least one first fibre mat prior to pressing said at least one first fibre mat, or at least prior to final pressing. In one embodiment, the second fibre mat is applied on said at least one first fibre mat prior to curing said at least one first fibre mat.

By lignocellulosic particles are meant particles comprising cellulose and/or hemicellulose and lignin. The particles may be wood fibres or vegetable fibres such as jute, linen, flax, hemp, bamboo, bagasse and sisal.

By cellulosic particles are meant particles comprising no or substantially no lignin (e.g., les than <NUM> % lignin). The particles may be produced from wood, preferably wood fibres or vegetable fibres such as cotton.

In one embodiment, the surface layer comprises no pigment. The surface layer may be free from pigments. The surface layer may consist of cellulosic particles, a binder and, optionally, additives selected from hydrophobing agents, hardener, and catalysts.

An advantage of embodiments is that a wood-based board having a pale to white surface is obtained. Thereby, the wood-based board is suitable for being directly printed on. The wood-based board is thereby also suitable for being used as a core for a surface layer being at least partly translucent. The wood-based board may also be used without any further treatment.

As a result of the pale to white colour of the surface layer of the wood-based board, a high quality print may be printed directly on the surface of the wood-based board. Especially, pale colours may be printed on the wood-based board. The disadvantages of printing on a conventional wood-based board having a brown colour are overcome or at least reduced.

Furthermore, by using cellulosic particles in the surface layer, a pale to white surface of the wood-based board may be achieved at a lower cost compared to when using pigment such as titanium dioxide, to obtain a white surface. The amount of pigment such as titanium dioxide, can be reduced or eliminated.

Another advantage is that by using cellulosic particles only in the surface layer, a pale to white surface of the wood-based board may be achieved at a lower cost compared to producing a wood-based board of entirely cellulosic particles. The cellulosic particles may be only used where required, i.e. at a surface.

By arranging a pale to white surface layer, the need for covering the wood-based board with a paper or similar in order to reduce the visibility of the core is eliminated, or at least reduced.

By printing directly on the surface of the wood-based board, and since no paper is required to cover the surface of the board, the number of required steps in the manufacturing process is reduced. The cost for producing a wood-based board having for example a printed decorative design is reduced.

The step of pressing, which may include curing, may comprise simultaneously adhering said base layer and the surface layer to each other. Curing may take place by applying heat and pressure to said base layer and/or the surface layer. Thereby, the wood-based board is formed in one step.

The step of pressing, which may include curing, said at least one fibre mat and the second fibre mat may comprise applying heat and pressure, and wherein pressure and/or binder content of the second fibre mat are chosen such that the surface layer remains opaque after curing. Thereby, the base layer remains invisible through the surface layer after curing. The base layer does not shine through the surface layer after curing. If the pressure applied exceeds a certain limit, there is a risk that the surface layer becomes transparent such that the colour of the underlying base layer shines through the surface layer. By adapting the pressure applied to the binder content of the surface layer such that the surface layer still contains air pockets after curing, the surface layer may remain opaque after curing. For example, the surface layer preferably has an opacity of at least <NUM> %.

The step of pressing may comprise curing said at least one first fibre mat into a base layer and the second fibre mat into a surface layer simultaneously.

The method may further comprise printing, preferably by digital printing or rotogravure printing, a print on the surface layer after pressing, which may involve curing. Printing may be performed directly on the surface layer of the wood-based board, without any intervening layers. In one embodiment, a primer may be applied on the surface layer before printing. The primer may comprise pigments such as titanium dioxide.

The method may further comprise printing, preferably by digital printing, a print on the second fibre mat before pressing. A protective layer may be applied on the print before pressing. Thereafter, all layers are pressed together in one step. By providing cellulosic particles in the surface layer, it is possible to print in the surface layer prior to pressing. Since the cellulosic particles are relatively small, void space between the particles is at least reduced, thereby reducing ink drops from permeating into the layer and being displaced during pressing.

Pigment or pigments may be included in the second mix, for example to form a coloured surface layer or such that the pigments are chosen to match the print. For example, it may be desirable to have a slightly grey colour of the print layer. This may be achieved by adding pigments and/or by using a certain amount of recycled fibres.

The carrier may be a conveyor belt, or any other type of conveyor device.

The method may further comprise applying a protective layer on the surface layer. The protective layer may be an overlay sheet, a lacquer layer, a powder overlay comprising wood particles and a binder. The protective layer may be a radiation curing layer such that a UV curing layer. The protective layer may be applied prior or after pressing.

The cellulosic particles of the second mix may be at least partially bleached. By using at least partly bleached particles such as at least partly bleached fibres, the lignin content of the fibres is further reduced.

The lignocellulosic particles of the first mix may be refined wood fibres, wood chips, unrefined wood fibres, wood strands, or sawdust. Depending on the type of lignocellulosic fibres used, the wood-based board obtain properties similar to a MDF, HDF, particle board, OSB etc..

The first binder of the first mix may be a thermosetting resin. The thermosetting binder may be an amino resin. The thermosetting binder may be melamine formaldehyde resin, urea formaldehyde resin, or a combination thereof, or a co-condensation thereof such as MUF (melamine urea formaldehyde). The binder may be an isocyanate resin.

The second binder of the second mix may be a thermosetting resin. The thermosetting binder may be an amino resin. The thermosetting binder may be melamine formaldehyde resin, urea formaldehyde resin, or a combination thereof, or a co-condensation thereof such as MUF (melamine urea formaldehyde). The binder may be an isocyanate resin.

The wood-based board may be a MDF or HDF. If using refined wood fibres, the resulting wood-based board corresponds to a MDF or HDF.

The wood-based board may be a particle board or an OSB. If using wood chips, the resulting wood-based board corresponds to a particle board.

The lignocellulosic material of the first mix may have similar properties as the cellulosic properties of the first mix regarding binder content, humidity etc. The particle size of the lignocellulosic material of the first mix may essentially correspond to the particle size of the cellulosic material of the second mix.

The base layer may comprise a lower base layer and a upper base layer, wherein the particle size of the lignocellulosic particles of the lower base layer is less than the particle size of the lignocellulosic particles of the upper base layer. By using larger particle size of the lignocellulosic particles of the upper base layer, i.e. the layer arranged between the lower base layer and the surface layer, the thickness of the wood-based board may be increased without increasing the weight of the board to the same extent by incorporating air in the upper base layer.

The lignocellulosic material of the lower base layer may have similar properties as the cellulosic properties of the surface layer regarding binder content, humidity etc. The particle size of the lignocellulosic material of the first mix may essentially correspond to the particle size of the cellulosic material of the second mix.

According to a second aspect, which forms part of the claimed invention, a wood-based board is provided. The wood-based board is defined in claim <NUM> and comprises a base layer comprising lignocellulosic particles and a first binder, a surface layer comprising cellulosic particles and a second binder, and wherein the building panel comprises a portion wherein cellulosic particles from the surface layer are mixed with lignocellulosic particles from said base layer.

The second aspect of the invention incorporates all the advantages previously discussed, whereby the previous discussion is applicable also for the wood-based board.

The wood-based board may be a HDF or MDF. Alternatively, the wood-based board may be a particle board or an OSB.

The first binder may be a thermosetting binder, for example, an amino resin.

The second binder may be a thermosetting binder, for example, an amino resin.

The wood-based board may be produced according to the first aspect.

According to a third aspect of the invention, a method of manufacturing a wood-based board is provided. The method is defined in claim <NUM> and comprises:.

Preferably, pressing comprises applying heat and pressure.

An advantage of embodiments of the present invention is that a wood-based board having a pale to white surface is obtained, and for example having a white grade measured according to Berger of more than <NUM>. Thereby, the wood-based board is suitable for being directly printed on. The wood-based board is thereby also suitable for being used as a core for an additional surface layer being at least partly translucent. The wood-based board may also be used without any further treatment. The disadvantages of printing on a conventional wood-based board having a brown colour are overcome or at least reduced by arranging a surface layer comprising cellulosic fibres on the first fibre mat.

Another advantage is that by arranging a surface layer comprising cellulosic particles, a pale to white surface of the wood-based board may be achieved at a lower cost compared to producing a wood-based board of cellulosic particles, or by incorporating pigments in the mix in order to obtain a white surfaces. The cellulosic particles may be only used where required, i.e. at the surface.

Furthermore, the surface layer is attached to the fibre mat in the same step as the fibre mat is pressed into a board. Thereby, no additional step is required to provide the board with a surface layer suitable for being printed on.

The surface layer may comprise a sheet comprising cellulose particles, preferably a paper sheet.

The sheet may be impregnated or unimpregnated. The binder of the first fibre mat may instead impregnate the sheet during pressing. If impregnated, the sheet may be impregnated with a thermosetting binder such as an amino resin.

The sheet may be pigmented. The sheet may, for example, be a white paper.

The step of pressing may comprise curing said at least one first fibre mat into a base layer. Preferably, the surface layer is applied on the first fibre mat prior to curing said at least one first fibre mat.

The method may further comprise printing, preferably by digital printing, a print on the surface layer prior or after pressing.

The first binder may be a thermosetting binder, for example an amino resin. The method may comprise curing the first binder during pressing.

As described above in relation to the first aspect, the surface layer may in one embodiment comprise cellulosic fibres and a second binder applied as first fibre mat.

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.

<FIG> shows a schematic representation of an equipment <NUM> and method for forming a wood-based board.

The equipment <NUM> comprises at least two mixing containers <NUM>, <NUM>. In a first mixing container <NUM>, lignocellulosic particles are provided. The lignocellulosic particles comprise lignin. The lignocellulosic particles may be refined wood fibres.

In an embodiment wherein a HDF or MDF is formed, the refined wood fibres may have a length of <NUM>-<NUM>, preferably <NUM>-<NUM>, and a width of <NUM>-<NUM>, preferably <NUM>-<NUM>.

In another embodiment wherein a particle board is formed, the lignocellulosic particles are wood chips. A coarse fraction of the wood chips may have a length of <NUM>- <NUM>, a width about <NUM>, and thickness about <NUM>-<NUM>. A fine fraction of the wood chips may have a length less than <NUM>, a width about <NUM>-<NUM>, and a thickness about <NUM>-<NUM>. A thickness/length ratio for both the fine and the coarse fraction of the wood chips may be <NUM>:<NUM>.

In another embodiment wherein an OSB (Oriented Strand Board) is formed, the lignocellulosic particles are wood chips. The wood chips may have a length of about <NUM>, a width about <NUM>-<NUM>, and thickness less than <NUM>.

The lignocellulosic particles are mixed with a first binder in the first mixing container <NUM> to form a first mix. The first binder may be a thermosetting resin, preferably an amino resin. The first binder may be melamine formaldehyde resin, urea formaldehyde resin, phenol formaldehyde resin, or a mix or combination thereof, or a co-condensation thereof such as MUF (melamine urea formaldehyde). Alternatively, the binder may be an isocyanate resin such as PMDI (polymeric methylene diphenyl diisocyanate) or EMDI (emulsifiable methylene diphenyl diisocyanate). Preferably, the lignocellulosic material is mixed with the first binder in a dry state.

In a second mixing container <NUM>, cellulosic particles are provided. The cellulosic particles may be at least partly bleached particles, preferably at least partly bleached wood fibres. The cellulosic particles comprise no lignin, or substantially no lignin. The cellulosic particles may have length of about <NUM>-<NUM>, preferably about <NUM>. The cellulosic particles may have a width of <NUM>-<NUM>, preferably <NUM>-<NUM>.

The cellulosic particles are mixed with a second binder in the second mixing container <NUM> to form a second mix. The second binder may be a thermosetting resin, preferably an amino resin. The second binder may be melamine formaldehyde resin, urea formaldehyde resin, or a mix or combination thereof, or a co-condensation thereof such as MUF (melamine urea formaldehyde). Alternatively, the second binder may be an isocyanate resin such as PMDI (polymeric methylene diphenyl diisocyanate) or EMDI (emulsifiable methylene diphenyl diisocyanate). Preferably, the cellulosic particles are mixed with the binder in a dry state.

Additives, such as catalysts, hydrophobic agents, etc., may be added both to the lignocellulosic particles and to the cellulosic particles. The additives are preferably added to the binder and added to the lignocellulosic and/or cellulosic particles when adding the binder.

The first mix comprising the lignocellulosic particles mixed with the first binder is thereafter fed to a first collecting container <NUM>. The second mix comprising the cellulosic particles mixed with the second binder is fed to a second collecting container <NUM>.

The first mix comprising the lignocellulosic particles is thereafter fed to a first scattering device <NUM>. The first scattering device <NUM> applies, preferably scatters, the first mix on a carrier <NUM>. The carrier <NUM> may be a conveyor belt. The first mix forms a first fibre mat <NUM> adapted to form a base layer <NUM> comprising lignocellulosic particles.

The second mix comprising the cellulosic particles mixed with the second binder is fed to a second scattering device <NUM>. The second scattering device <NUM> applies, preferably scatters, the second mix on the first fibre mat <NUM> formed by the first mix. The second mix comprising the cellulosic particles forms a second fibre mat <NUM> adapted to form a surface layer <NUM> comprising cellulosic particles.

Both the first and/or the second mix may be applied as several layers, such that more than one layer forms the first fibre mat <NUM>, and more than one layer forms the second fibre mat <NUM>.

The first fibre mat <NUM> adapted to form the base layer <NUM> and the second fibre mat <NUM> adapted to form the surface layer <NUM> are thereafter conveyed to a pre-pressing station <NUM>. The first fibre mat <NUM> and the second fibre mat <NUM> are pre-pressed, preferably without applying heat (cold pressing).

The first fibre mat <NUM> may also be pre-pressed before the second fibre mat <NUM> is applied. As a further alternative, no pre-pressing may take place. However, the second fibre mat is applied to the first fibre mat before final pressing of the first fibre mat. In one embodiment, the second fibre mat is applied to the first fibre mat prior to substantial curing the first fibre mat.

After pre-pressing, the first fibre mat <NUM> adapted to form the base layer <NUM> and the second fibre mat <NUM> adapted to form the surface layer <NUM> are conveyed to a pressing station <NUM>. The first fibre mat <NUM> and the second fibre mat <NUM> are pressed by applying heat and pressure.

In one embodiment, as an example for a continuous press, the temperature may be <NUM>-<NUM>. Pressure may be applied for <NUM>-<NUM> seconds per mm product thickness. The pressure applied may be varying during the press cycle. Initially, a pressure of about <NUM> bars may be applied. The pressure is thereafter lowered to about <NUM> bars. The pressure may be increased towards the end of the press cycle to about <NUM>-<NUM> bars in order to adjust the thickness of the board.

By applying heat and pressure, the first fibre mat <NUM> and the second fibre mat <NUM> are pressed simultaneously into a base layer <NUM> and a surface layer <NUM>, respectively. In one embodiment, the binder of the first and second fibre mat is cured by the pressing step. Simultaneously, the base layer <NUM> and the surface layer <NUM> adhere to each other such that a wood-based board <NUM> is formed.

In one embodiment, no pre-pressing takes place and the first fibre mat <NUM> and the second fibre mat <NUM> are directly conveyed to the pressing station <NUM>.

It is also contemplated that more than one first fibre mat may be applied on the carrier to form more than one base layer.

As shown in <FIG>, the wood-based board <NUM> thereby formed comprises a base layer <NUM> comprising lignocellulosic particles and a surface layer <NUM> comprising cellulosic particles. Depending on the type of particles used for the base layer <NUM>, the wood-based board may be a HDF, MDF, particle board, OSB etc. If the lignocellulosic particles are refined fibres, the wood-based board forms a MDF or HDF. If the lignocellulosic particles are wood chips, the wood-based board forms a particle board. Common for all embodiments is that the cellulosic particles of the surface layer <NUM> forms a surface layer of the wood-based board <NUM>. The surface layer <NUM> may have a pale to white colour.

Since the first fibre mat <NUM> and the second fibre mat <NUM> are pressed simultaneously to form the base layer <NUM> and the surface layer <NUM>, and simultaneously adhered to each other, a portion wherein cellulosic particles form the surface layer <NUM> are mixed with lignocellulosic particles from the base layer <NUM> is formed.

About <NUM>/m<NUM> or more of the second mix may be applied for forming the surface layer <NUM>.

In <FIG>, a wood-based board <NUM>' comprises a lower base layer 14a comprising lignocellulosic particles, an upper base layer 14b comprising lignocellulosic particles, and a surface layer <NUM> comprising cellulosic particles. The lignocellulosic particles of the lower and upper base layer 14a, 14b may be wood chips. The wood-based board <NUM>' may thus be a particle board having an integrated surface layer of cellulosic particles.

Since the two first fibre mats and the second fibre mat <NUM> are pressed simultaneously to form the lower base layer 14a, the upper base layer 14b and the surface layer <NUM>, and simultaneously adhered to each other, a portion wherein cellulosic particles form the surface layer <NUM> are mixed with lignocellulosic particles from the upper base layer 14b is formed.

The lower base layer 14a and the surface layer <NUM> may have similar properties concerning dimensional stability and resistance to moisture.

The particle size of the lignocellulosic particles of the lower base layer 14a and of the upper base layer 14b, respectively, may differ. In one embodiment, the particle size of the lower base layer 14a corresponds to the particle size of the cellulosic particles of the surface layer <NUM>. The particle of the lower base layer 14a and of the surface layer <NUM> may have a length less than <NUM>, a width about <NUM>-<NUM>, and a thickness about <NUM>-<NUM>. The upper base layer 14b, arranged between the lower base layer 14a and the surface layer <NUM>, may have a particle size exceeding the particle size of the lower base layer 14a. In case of a particle board, the upper base layer 14b may comprise coarse wood chips having a length of <NUM>- <NUM>, a width about <NUM>, and thickness about <NUM>-<NUM>. Thereby, a three layer wood-based board <NUM>' is obtained, for example a three layer particle board.

In one embodiment of a wood based board <NUM>", which is shown in <FIG>, the second fibre mat <NUM> is replaced by a surface layer <NUM>' comprising cellulosic particles, preferably comprising a sheet such as a paper sheet. A first fibre mat <NUM> is applied on a carrier <NUM> as described above with reference to <FIG>. Instead of applying a second fibre mat <NUM>, a surface layer <NUM>' is applied on the first fibre mat <NUM>. The surface layer <NUM>' may comprise a sheet comprising cellulosic particles, such as a paper sheet. The paper sheet may be an impregnated or an unimpregnated paper sheet. If impregnated, the sheet may comprise a thermosetting binder such as an amino resin. When pressing the paper sheet on the first fibre mat <NUM> comprising the first binder, the first binder may impregnate the surface layer <NUM>' simultaneously as adhering the surface layer to the first fibre mat <NUM>. The sheet may be printed prior or after being pressed to the first fibre mat <NUM>. The sheet may be pigmented such as a white paper.

The wood-based board <NUM>, <NUM>', <NUM>" as described above may be cut or sawn to a desired shape and size. The surface layer <NUM>, <NUM>' of the wood-based board <NUM>, <NUM>', <NUM>" may be ground. The surface layer <NUM>, <NUM>' may be subjected to corona treatment. The wood-based board <NUM>, <NUM>', <NUM>" may be used without any further surface layer or decorative print as a wood-based board <NUM>, <NUM>', <NUM>" having a pale to white surface. Alternatively, a décor layer may be attached to the wood-based board <NUM>, <NUM>', <NUM>". Due to the surface layer of cellulosic particles, a thin and/or pale décor layer may be used without any risk that the colour of the wood-based board <NUM>, <NUM>', <NUM>" shines through the décor layer.

A print may be printed directly on the surface <NUM>, <NUM>' of the wood-based board <NUM>, <NUM>', <NUM>" of the above described type. The surface layer <NUM>, <NUM>' of cellulosic particles forms a print layer integrated in the wood-based board <NUM>, <NUM>', <NUM>". The print is preferably applied by means of digital printing. The digital printing device may comprise a Drop-on-Demand (DOD) inkjet printer, preferably a piezoelectric DOD inkjet printer. Preferably, the ink is an aqueous ink, but solvent based and UV curing inks may also be used. A print may also be applied by other suitable means such as rotogravure. A print may also be applied by dry particles used as colorants to create a digital image as described in <NPL>.

The print may be printed prior or after pressing of the first and second fibre mats <NUM>, <NUM>. In one embodiment, the print is printed into the second fibre mat <NUM> prior to pressing. However, the second fibre mat <NUM> may be prepressed prior to pressing. The printed second fibre mat <NUM> is thereafter pressed. In another embodiment, the print is printed on the surface layer <NUM>, <NUM>' after pressing, and preferably after curing.

The print may be a decorative design or a fantasy pattern. The decorative design may be natural designs and patterns such as a wood pattern or stone patterns.

The second mix forming the surface layer <NUM> may comprise pigment or pigments such that a coloured surface layer <NUM> is obtained. Thereby, a wood-based board <NUM>, <NUM>' having a coloured surface layer <NUM> is obtained. The wood-based board <NUM>, <NUM>' can be used without any additional paint layers and/or décor foils. A coloured surface layer <NUM> can be combined with a print as described above.

A protective layer or coating (not shown) may be applied on the surface <NUM>, <NUM>' of the wood-based board <NUM>, <NUM>', <NUM>" according to any embodiment described above. The protective coating may be applied on a decorative print printed on the surface <NUM> of the wood-based board <NUM>, <NUM>', <NUM>". The protective coating may be an overlay paper such as a resin impregnated paper, preferably comprising wear resistant particles such as aluminium oxide particles, for example, corundum. The protective coating may be a powder overlay comprising a binder in powder form and preferably cellulosic particles and wear resistant particles such as aluminium oxide particles, for example, corundum. The protective coating may be a radiation curing coating such as electron beam curing coating or UV curing coating. The protective coating may comprise acrylate or methacrylate polymers.

The protective coating may be applied prior or after pressing. In one embodiment, the protective coating is applied on the second fibre mat <NUM> prior to pressing, with an optional print thereon, and the first fibre mat <NUM>, the second fibre mat <NUM> are pressed together in one step.

The wood-based board <NUM>, <NUM>', <NUM>" may be used as a building panel, for example as floor panel, a wall panel, a furniture panel. The building panel may be provided with a mechanical locking system for locking building panels to each other. The mechanical locking system may be of the type described in <CIT>, <CIT>, <CIT>, or <CIT>.

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. It is for example contemplated that more than one base layer of lignocellulosic particles may be provided, and that more than one surface layer of cellulosic particles may be provided.

Example <NUM>: Three different blends have been prepared. <NUM> of a lower base layer comprising wood flour (<NUM>-<NUM>) and <NUM>% melamine-formaldehyde resin was scattered on a carrier to form a first layer of a first fibre mat. <NUM> of an upper base layer comprising wood particles (<NUM> in length, <NUM> in width) and <NUM>% melamine-formaldehyde resin, was scattered on the first layer of the first fibre mat to form a second layer of the first fibre mat. Another <NUM> of a white surface layer comprising cellulosic fibres (<NUM>) and <NUM>% melamine-formaldehyde resin, was scattered on top of the second layer of the first fibre mat to form a second fibre mat. The first fibre mat and the second fibre mat were prepressed cold and moved into a hot press, pressing with <NUM> in <NUM> seconds at <NUM> bar. The product was a <NUM> x <NUM> x <NUM> particle board with a density of about <NUM>/m3 and a printable white surface layer.

Claim 1:
A wood-based board (<NUM>; <NUM>'; <NUM>"), comprising
a base layer (<NUM>; 14a, 14b) comprising lignocellulosic particles and a first binder,
a surface layer (<NUM>) comprising cellulosic particles and a second binder, wherein the cellulosic particles are particles comprising no or less than <NUM>% lignin, and
characterised in that the wood-based board comprises a portion wherein cellulosic particles from the surface layer (<NUM>) are mixed with lignocellulosic particles from the base layer (<NUM>; 14a, 14b).