Patent Description:
In the field of building, the use of panels which are based on a laminated multi-layer structure is generally known. They have proven highly versatile for covering surfaces, such as a floor, a wall and a ceiling. In particular it is attractive to use a laminated multi-layer structure which comprises:.

Recent developments have been directed to a specific modification of the top side of the top layer of such a panel once the multi-layered structure is formed, which is referred to as embossing. In embossing, the top side of the top layer is provided with a relief which mimics a natural top surface such as perceived from wooden panels. A special way of embossing is embossing in register, which provides a relief that corresponds with the decorative layer, for instance corresponding with a decorative image of a wooden panel surface with a grain pattern. <CIT> for example relates to a method for manufacturing decorative surfaces. <CIT> for example provides sound absorbing or attenuating laminate flooring materials. <CIT> for example provides a laminate and the method for its formation.

In producing such panels, the embossing of the top layer may be executed by several techniques, such as compression, milling or chemical etching of the top layer. After the relief is embossed on the top surface, further finishing steps may be needed such as finely grinding or sanding of the embossed surface.

It has been found that during embossing and/or finishing of the top layer of a panel, the integrity or the appearance of the underlying decorative layer may be negatively affected, and may even be damaged.

It is therefore an objective of the invention to further secure that in producing a laminated multi-layered panel such as defined above, it is prevented that the embossing and finishing steps for the top layer could alter the integrity or appearance of the underlying decorative layer.

The present invention achieves the above objective by the provision of a panel, in particular a floor panel, ceiling panel or wall panel, having a laminated multi-layer structure which comprises.

which intermediate layer is transparent, and at least <NUM> wt. % is made from a protective material which comprises a polyurethane composition which is the reaction product of a polyester polyol, a polyether polyol and an isocyanate, and wherein the polyurethane composition is a thermoset polymer material.

It has been found that the specific protective material of the intermediate layer has a sufficiently high hardness to protect the decorative layer against any abrasion or indentation during the embossing and finishing of the top layer of the panel.

In the context of the panel according to the invention, the terms 'above' and 'upper' relate to the direction to which the panel faces once it is applied on a floor or likewise. The term 'substantially' encompasses that at least <NUM> wt. %, and preferably at least <NUM> wt. %, most preferably <NUM> wt. %, of the intermediate layer is made from the protective material.

The decorative layer may contain a (printed) decorative image on the upper side of the decorative layer which is visible when the panel is used as a floor panel, ceiling panel, or wall panel. The intermediate layer is of a satisfactorily transparent quality so that the visibility of the decorative image is not affected by the intermediate layer.

In the panel according to the invention, it is typical that the respective layers of the laminated multi-layer structure are directly or indirectly attached onto each other.

The polyurethane composition of the panel of the invention is a thermoset polymer material, and in particular the polyurethane composition is a cross-linked polymer.

The thermoset polymer material is in the art also known as a hot-melt adhesive, wherein thermosetting typically occurs over a heat trajectory of <NUM> - <NUM>.

When producing the panel, the intermediate layer could be applied in a hot-melt state in order to be solidly attached to a neighbouring layer of the panel.

In the panel according to the invention, the polyester polyol preferably has a weight average molar mass Mw in the range of <NUM> to <NUM>,<NUM>, and comprises preferably a polyester polyol having linear monomers of <NUM> to <NUM> carbon atoms.

The polyester polyol may include a polyester glycol, such as for instance a polyester formed by reacting hexane diol with adipic acid.

Further in the panel according to the invention, the polyether polyol preferably has a weight average molar mass Mw in the range of <NUM> to <NUM>,<NUM>, and comprises preferably a polyether polyol having branched monomers of <NUM> to <NUM> carbon atoms.

The polyether polyol may include a polyether glycol, such as polypropylene glycol.

It is in particular preferred in the panel according to the invention, that the isocyanate is a di-isocyanate and/or tri-isocyanate, preferably methylene diphenyl di-isocyanate.

With respect to the protective material, the following preferred weight percentages apply:.

It is furthermore preferred that the protective material comprises a filler material as an additive, such as microfibers and/or alumina, preferably in a range of <NUM> - <NUM> wt. % with respect to the protective material.

This type of filler material further contributes to the required hardness of the protective material, and thus enhances the anti-abrasive properties of the protective material.

In the panel according to the invention, it is preferred that the intermediate layer is directly attached onto the decorative layer and/or onto the top layer.

As such, the required visibility of the decorative layer can be accomplished most expediently.

In the context of the panel according to the invention, it is preferred that the top side of the top layer is embossed with a relief, which relief preferably corresponds to the decorative image of the decorative layer.

It is furthermore preferred that in the panel according to the invention, the intermediate layer has a grammage of <NUM> up to <NUM>/m2.

Such a grammage determines the thickness of the intermediate layer to such a range, that an optimum protection for the decorative layer as well as an optimum visibility of the decorative layer is achieved.

It is advantageous in the panel according to the invention that the intermediate layer is colorless. As such, the appearance of the decorative layer is not altered by any hue on the top side of the panel.

It is preferred in the panel according to the invention that the intermediate layer has a relatively low reflectance of <NUM>%, <NUM>%, <NUM>% or lower.

Such an intermediate layer has a reflectance value that is comparable to glass, or may even be lower than glass. The reflectance value is also referred to in the field as the reflection coefficient of a material.

By virtue of such a reflectance value of the intermediate layer, an optimum visibility of the underlying decorative layer is achieved, because the amount of transmitted light is relatively high while only small amounts of light are reflected.

In the context of the invention, it is further preferred that the intermediate layer has a relatively low refractive index, preferably between <NUM> and <NUM>.

Further preferred features of the panel according to the invention include:.

In a further preferred embodiment, the panel according to the invention, comprises a first panel edge comprises a first coupling profile, and a second panel edge, preferably opposite to the first panel edge, comprising a second coupling profile being designed to engage by interlocking with said first coupling profile of an adjacent panel, both in horizontal direction and in vertical direction, wherein the first coupling profile and the second coupling profile are preferably configured such that two of such panels can be coupled to each other by means of a lowering movement.

Such a panel allows for adequately covering a flat surface with a multitude of interconnected panels and thus achieving a covering of panels that is robust as a whole.

Additionally or alternatively to the above first and second coupling profiles, the panel may further comprise at least one third coupling profile and at least one fourth coupling profile located respectively at a third panel edge and a fourth panel edge, wherein the third coupling profile comprises:.

In a second aspect, the invention relates to the use of an additional layer in a laminated multi-layer structure of a panel in particular a floor panel, ceiling panel or wall panel,
wherein the additional layer is preferably transparent, and is substantially made from a protective material which comprises a polyurethane composition which is the reaction product of a polyester polyol, a polyether polyol and an isocyanate.

Such a use of an additional layer forms a protective layer, which protects the laminated structure of the panel to any high-impact techniques which are performed during the production of a panel, such as during embossing of a relief on a top layer of the panel.

In the use of an additional layer according to the invention, it is preferred that the polyurethane composition is a thermoset polymer material, wherein preferably the polyurethane composition is a cross-linked polymer.

Such preferred types of polyurethane composition have a suitable hardness for the intended function of the additional layer, i.e. a hardness which is sufficiently high to protect the laminated multi-layer structure against any abrasion or indentation during the production of the panel.

In general, the use according to the invention may include preferred features relating to the panel and the respective additional layer, which features correspond to the preferred features already described above in view of the panel and the respective intermediate layer according to the first aspect of the invention.

In particular it is preferred in the use of an additional layer according to the invention, that the laminated multi-layer structure of the panel comprises:.

and the additional layer is applied as an intermediate layer situated between the decorative layer and the top layer.

As already explained above, such an intermediate layer is most effective in protecting the decorative layer against any abrasion or indentation during the production of the panel.

In general, it is preferred that the use of an additional layer according to the second aspect of the invention is applied in a panel according to the first aspect of the invention.

The invention will be further elucidated by specific preferred embodiments which are shown in the appended figures, wherein:.

<FIG> shows schematically a cross-section of a laminated multi-layer structure of a panel <NUM>, which is constituted from multiple layers which are directly connected to each other. These layers include a backing layer <NUM>, a core layer <NUM>, a decorative layer <NUM> provided with a decorative image, an intermediate layer <NUM> and an embossed top layer <NUM>. The embossed top layer contains depressions <NUM> and elevations <NUM>, so that a relief is formed on the top surface of the top layer which corresponds to the pattern of the decorative image that is facing upwards from the decorative layer <NUM>. The intermediate layer <NUM> is formed from a protective material in accordance with the invention, and is transparent and colorless.

<FIG> show two types of engaging coupling profiles 401A, 401B resp. 402A, 402B, of two interconnecting panels 400A, 400B according to the present invention. The panels 400A and 400B comprise an embossed top layer <NUM>. As a whole, each panel has a laminated multi-layer structure in accordance with <FIG> (which is however not further shown in detail in <FIG>).

<FIG> shows panels 400A and 400B, which respectively comprise a first panel edge 440A comprising a first coupling profile 401A, and a second panel edge 440B opposite to the first panel edge 440A, comprising a second coupling profile <NUM> B being designed to engage by interlocking with said first coupling profile 401A of an adjacent panel, both in horizontal direction and in vertical direction, wherein the first coupling profile 401A and the second coupling profile 401B are configured such that two of such panels can be coupled to each other by means of a lowering movement.

<FIG> shows panels 400A and 400B, which respectively comprise a third coupling profile 402A and a fourth coupling profile 402B located respectively at a third panel edge 441A and a fourth panel edge <NUM> B. The third coupling profile 402A and the fourth coupling profile 402B are configured such that the two panels 440A, 440B can be coupled to each other by means of a turning movement, wherein, in coupled condition at least a part of a sideward tongue 404B of a first panel is inserted into a groove 404A of an adjacent, second panel, and wherein at least a part of an upward locking element 406A of said second panel is inserted into a second downward groove 406B of said first panel.

Claim 1:
Panel (<NUM>), in particular a floor panel, ceiling panel or wall panel,
having a laminated multi-layer structure which comprises:
- a core layer (<NUM>),
- a decorative layer (<NUM>) above the core layer,
- a transparent top layer (<NUM>) above the decorative layer, and
- an intermediate layer (<NUM>) situated between the decorative layer and the top layer,
which intermediate layer (<NUM>) is transparent, and at least <NUM> wt.% of the intermediate layer (<NUM>) is made from a protective material which comprises a polyurethane composition which is the reaction product of a polyester polyol, a polyether polyol and an isocyanate, and wherein the polyurethane composition is a thermoset polymer material.