PANEL AND METHODS FOR MANUFACTURING A PANEL

Description

The present invention relates to a panel with an alternative top layer, such as with an alternative decorative and/or wear-resistant layer, as well as to methods for the manufacture thereof.

In particular, the invention relates to a panel comprising a substantially plate-shaped core or substrate, such as a polymer core, and a decorative, wear-resistant layer, wherein said decorative, wear-resistant layer is bonded at least partially to a surface of said polymer core, as well as methods for manufacturing said panel. Material of this kind is known for example from WO 2019/086566 A1.

Floor coverings that comprise a polymer core, in particular based on polyvinyl chloride (PVC), also known as vinyl floors or as LVT (Luxury Vinyl Tiles), have a number of various advantages that make them very suitable for use in living spaces. Thus, they have good hygienic properties, they are very functional and comfortable, and it is possible to provide these floor coverings with printed finishing layers, for example with a wood pattern. These floor coverings are manufactured in thicknesses of approx. 5 mm and can be glued to the substrate. Moreover, PVC panels are also known that are suitable, by means of click profiles, for glueless, floating placement. With respect to laminate floors for example, the advantage of PVC floors is that they are moisture-resistant, feel more comfortable and have significantly better properties relating to sounds from contact and walking.

However, to ensure an acceptable quality and life of these floor coverings, they generally comprise one or more additional layers that increase the comfort and/or the wear resistance further. WO 2018/087637 A1 discloses for example a floor panel with a substrate or core comprising a polymer material, for example PVC, and a separate decorative layer and wear-resistant layer provided thereon. This floor panel with a core of polyvinyl chloride (PVC) may in addition comprise fillers. The addition of fillers in such floors is also known from WO 2019/086566 A1. A plate material of this kind is called SPC (Stone Plastic Composite). The plate material produced by this process is largely dimensionally stable and water-resistant, and has a high specific gravity. It ensures a pleasant sound of walking and is hard enough to compensate for irregularities in the subfloor or to prevent them “by telegraphing”, furthermore it is stable enough to carry out edge profiling and to join several panels together without glue by means of so-called “click profiles”.

Each of the floor coverings and/or floor panels discussed have the feature in common that they preferably make use of a wear-resistant layer, which increases their quality and life. In practice, a first laminated layer then generally provides the decorative finish, and a second laminated layer provides the wear resistance. However, it therefore follows that the production process is quite complex and that often specific conditions are imposed on the decorative and/or wear-resistant layer, in particular the decorative possibilities are quite limited and they are generally applied in the form of a laminated film, which is often perceived as an imitation. Because of its thickness, and its incomplete transparency, the wear layer may be detrimental to the quality of the decor.

The invention aims firstly to provide an alternative panel, wherein according to various preferred embodiments, a solution can be obtained for the problems relating to the decorative and/or wear-resistant layer as described above. Some embodiments of the invention aim in addition to provide imitations for existing tile products that are of good quality but are easier or more practical for handling and/or placement, such as concrete tiles, particularly grit-filled concrete tiles. The invention also aims to provide a good-quality imitation of the appearance of related PVC-based products, such as the so-called compact vinyl tile (CVT).

For this purpose, according to its first independent aspect, the invention relates to a panel comprising a substantially plate-shaped polymer core and a top layer, preferably a decorative and/or wear-resistant layer, wherein said decorative and/or wear-resistant layer is bonded at least partially to and/or in a surface of said polymer core, wherein said decorative and/or wear-resistant layer comprises a granular and/or fibrous material. By using said granular and/or fibrous material that is bonded at least partially to and/or in a surface of the polymer core, there is no longer the need to apply a separate decorative film, or a separate wear-resistant film, on the panel. The invention as described herein namely allows the panel to be provided with an innovative decorative layer that may inherently possess wear-resistant properties.

In the sense of the present invention, the term “panel” means a plate-shaped material, said plate-shaped material being available both in cut form, for example cut to measure, and in uncut form. In particular, reference is made herein to, among others, Luxury Vinyl Tiles (LVT), Stone Polymer Composite (SPC), or other polymer-based panels.

The terms “decorative layer” and “wear-resistant layer” mean, in the sense of the present invention, a single, i.e. unassembled, layer, which provides the panel with a decor, or with wear-resistant properties. Thus, known decorative layers provide a panel for example with a wood grain pattern or with coloring that imitates stone. Said layer extends in particular over an approximately horizontal region of the panel and preferably through a substantial thickness of the panel. This layer is possibly a uniform, continuous layer, for example an extruded polymer layer, or comprises an assembly of material zones that extend continuously in the approximately horizontal region of the panel, as is the case when using separate particles, for example grit. In the prior art, a decorative layer is generally applied on a substrate or core, and the decorative layer is provided in its turn with a wear-resistant layer. According to the present invention, however, the granular and/or fibrous material provides both properties simultaneously. Consequently, application of additional and/or separate wear-resistant layers is possible, but superfluous.

In the sense of the present invention, the term “granular material” means a material that comprises separate particles. Various terms may be used, depending on the order of magnitude of these separate particles. In particular, “granular” is a more general term, i.e. covering a wide range of order of magnitude, and in the case of smaller particles reference may be made for example to “pulverulent material”. It is thus apparent that the granular material possibly assumes a natural form, for example in the case of grit, or may be cut, ground or shredded, for example in the case of polymer granules. The particle size of the granular material can be measured by various techniques from the prior art. In particular, for larger granules the particle size may possibly be determined by means of sieving techniques. The particle size of smaller particles may possibly be determined by laser granulometry, a technique that is carried out in accordance with ISO 13320. This relates to a dynamic light scattering technique using a laser with an emission wavelength of 632.8 nm, measurement being effected at a scattering angle of 90 degrees. This technique may for example be carried out with a Malvern® Mastersizer 2000 or with a Malvern® Mastersizer 3000. For carrying out the measurement of particle size distribution, the respective particles may be dispersed in a liquid, such as water.

According to a preferred embodiment, the granular and/or fibrous material is selected from the group of stone, grit, gravel, quartz, aluminum oxide (Al₂O₃), polyvinyl chloride (PVC), synthetic fibers, textile fibers, natural fibers, or combinations thereof. Suitable synthetic fibers are for example nylon or PET fibers. The choice of the granular and/or fibrous material thus allows very varied decoration possibilities, without it being necessary to apply an additional wear-resistant layer or to tailor such a layer specifically to a decorative layer.

It is clear that in the context of the invention, according to its first aspect, a top layer, for example a decorative and/or wear-resistant layer, may be produced that eliminates the need to apply separate and/or additional wear-resistant layers, and that allows very varied decorative possibilities. In contrast to decorative and/or wear-resistant layers as known in the prior art, the granular and/or fibrous material makes it possible to build up a relatively uniform top layer, in particular of substantial thickness, with exceptionally good wear resistance.

According to a further or another embodiment, the granular and/or fibrous material forms a substantially flat and homogeneous scatter layer on and/or in the surface of said polymer core.

In some embodiments the scatter layer or the layer of granular material has a thickness between 0.05 and 10.00 mm, preferably between 0.10 and 8.00 mm, more preferably between 0.50 and 5.00 mm. The scatter layer or layer of granular material is, in each of these embodiments, bonded to and/or in the polymer core, wherein the possibility exists that the scatter layer or the layer of granular material and the polymer core run partially into each other, or that they merely touch each other and so do not run into each other. The scatter layer with a thickness within the range described herein allows the scatter layer to form a relatively uniform decorative and/or wear-resistant layer, wherein the polymer core is only slightly or is not visible through this decorative and/or wear-resistant layer. In some embodiments the granular and/or fibrous material consists of particles with a particle size and/or transverse dimension between 0.05 and 10.0 mm. According to some embodiments, particles with a larger particle size may also be used, wherein a coarser structured surface is obtained. Preferably, the granular and/or fibrous material consists of particles with a particle size and/or transverse dimension between 0.10 and 8.00 mm, more preferably between 0.50 and 5.00 mm. Consequently, relatively uniform spreading of the granular and/or fibrous material over the surface of the polymer core is possible, wherein a structured decorative and/or wear-resistant layer is formed, which differs markedly from for example a flat printed film.

According to some embodiments, the coverage of the granular and/or fibrous material is at least 90%. This means that a perpendicular projection of the granular and/or fibrous material on the surface of the polymer core covers this surface to at least 90%. Preferably, the coverage of the granular and/or fibrous material is at least 95%, more preferably at least 99%.

According to some embodiments, the individual particles of the granular and/or fibrous material have only limited hues, wherein a decor is obtained that is substantially uniform. According to some other embodiments, the individual particles of the granular and/or fibrous material have a number of different hues, wherein they display arbitrary ordering. Yet other embodiments relate to those in which the individual particles of the granular and/or fibrous material have a number of different hues, and wherein their ordering follows a pattern. It is thus clear that the decorative possibilities of the decorative and/or wear-resistant layer as described herein are very varied. According to yet another possibility there is printing or other coloring on the granular and/or fibrous material. This printing or coloring may be continuous over substantially the whole surface of the respective panel or may be interrupted.

Although the present invention eliminates the need for separate and/or additional wear-resistant layers, it is possible to apply said layer on top of the granular and/or fibrous material. Possibly said additional wear-resistant layer relates to a wear-resistant film, or a transparent varnish coat applied in liquid form, or printing or coloring as stated above.

With the same aim as in the first aspect, according to an independent second aspect the present invention relates to a panel comprising a substantially plate-shaped polymer core and a top layer, such as a decorative and/or wear-resistant layer, wherein said decorative and/or wear-resistant layer is bonded at least partially to the surface of said polymer core, particularly wherein the thickness of said decorative and/or wear-resistant layer and the thickness of said polymer core are in a ratio between 1:5 and 5:5. The advantage of this is that the top layer or decorative and/or wear-resistant layer has an inherent wear resistance, wherein the need for the application of separate and/or additional wear-resistant layers is eliminated. The decor of the top layer or decorative and/or wear-resistant layer now extends through a substantial thickness, so that the decor remains intact, even though this layer will display wear after a certain time. This contrasts with the decorative films known from the prior art, wherein slight damage of the decorative film may already reduce the quality of the decor drastically, hence the need for a separate and/or additional wear-resistant film. However, the top layer or decorative and/or wear-resistant layer of the second aspect provides a decor that extends both in the surface of the panel, and perpendicular to the surface of the panel. The decor is thus also visible along any saw cuts, or where the decorative and/or wear-resistant layer is damaged locally and/or on the surface. Preferably, the ratio of the thickness of the top layer or decorative and/or wear-resistant layer to the thickness of the polymer core is between 2:5 and 4:5

According to a preferred embodiment, the polymer material of the top layer or decorative and/or wear-resistant layer is an extruded polymer material. This extruded polymer material can be fastened to the polymer core by regular techniques, which include heat lamination or gluing, and the two layers may possibly be coextruded. The use of an extruded polymer material has the further advantage that any coloring matter can be incorporated directly in the polymer material to be extruded, thus determining the appearance of the decor directly.

According to another preferred embodiment, the polymer material of the top layer or decorative and/or wear-resistant layer is a scattered polymer material. This scattered polymer material may be bonded to the polymer core by regular techniques, for example by heating and/or pressing.

According to some embodiments, the polymer material of the top layer or decorative and/or wear-resistant layer comprises one or more colorants. The colorants are then distributed over the polymer material as uniformly as possible, or may be dosed specifically so that certain hues are obtained. The dosage of the one or more colorants thus determines the decor of the decorative and/or wear-resistant layer.

According to some embodiments as described in the first and/or second aspect of the invention, the polymer core is an extruded polymer core.

In some embodiments, the polymer core and/or the polymer material of the top layer or decorative and/or wear-resistant layer comprises one or more polymers from the group of modified or unmodified polyolefins, for example polyethylene, polypropylene, polyvinyl chloride, or copolymers thereof.

Preferably, the polymer core and/or the polymer material of the top layer or decorative and/or wear-resistant layer comprises polyvinyl chloride (PVC). Preferably, in the case of the top layer, the polyvinyl chloride has a concentration of at least 95 wt %, more preferably at least 99 wt %, most preferably 100 wt %. Preferably, in the case of the polymer core, the polyvinyl chloride has a concentration of at least 20 wt %.

It is possible that the polymer core further comprises one or more fillers selected from the group of inorganic fillers, such as chalk, lime and/or talc, or organic fillers, such as wood, bamboo and/or cork, and/or mineral fillers.

According to a further or another embodiment, the polymer core and/or the polymer material of the top layer or decorative and/or wear-resistant layer comprises polyvinyl chloride (PVC) and calcium carbonate (CaCO₃) as filler.

Preferably, the polymer core and/or the polymer material of the top layer or decorative and/or wear-resistant layer comprises one or more additives selected from the group of Ca/Zn stabilizers, impact strength modifiers, waxes, or combinations thereof.

According to some embodiments, the calcium carbonate (CaCO₃) has a concentration of at most 80 wt % and the polyvinyl chloride (PVC) has a concentration of at least 20 wt %, wherein these concentrations may be employed in the polymer core and/or in the top layer. Preferably, the calcium carbonate (CaCO₃) has a concentration between 10 and 80 wt % and the polyvinyl chloride (PVC) has a concentration between 20 and 90 wt %. More preferably, the calcium carbonate (CaCO₃) has a concentration between 60 and 80 wt % and the polyvinyl chloride (PVC) has a concentration between 20 and 40 wt %. It was found that a particularly good result is achieved when the proportion of calcium carbonate is greater than the proportion of PVC. Preferably, the calcium carbonate (CaCO₃) has a concentration between 65 and 80 wt % and the polyvinyl chloride (PVC) has a concentration between 20 and 35 wt %. More preferably, the calcium carbonate (CaCO₃) has a concentration between 70 and 80 wt % and the polyvinyl chloride (PVC) has a concentration between 20 and 30 wt %. Most preferably, the calcium carbonate (CaCO₃) has a concentration of 75 wt % and the polyvinyl chloride (PVC) has a concentration of 25 wt %.

Of course, any proportion of additives should be taken into account. According to some embodiments, the concentration of the additives is at most 5 wt %.

In the sense of the present invention, it is to be understood in particular that the panel according to the preceding embodiments is free from resins, adhesives and/or glues between the polymer core and the decorative and/or wear-resistant layer. The bond between the various layers may thus be achieved unequivocally by the polymer material of the polymer core. Alternatively, however, one or more materials may be applied between the polymer core and the decorative and/or wear-resistant layer. Thus, for example, a layer of a flexible polymer, for example a layer that contains PVC and plasticizer, for example 15 phr plasticizer or more, may be provided on the surface of the polymer core facing the top layer. Said layer may have a favorable influence on embedding of a granular material or a fibrous material, and may also have a positive effect on walking comfort and the sound of walking.

The panel as described in each of the various embodiments is preferably a floor board or floor panel, a ceiling board or ceiling panel, or a wall board or wall panel.

In a further or another embodiment, the invention also envisages that the panel as described herein can be placed easily, wherein the risk of errors in laying, or of gaps between the placed boards or panels, is minimized. According to some embodiments, the invention envisages that the panel as described herein excludes or at least optimally counteracts the formation of any gaps or cracks. To this end, the invention relates to a board or panel according to one of the embodiments described above, wherein at the edges of two sides located opposite each other, the panel is provided with interacting coupling parts, substantially in the form of a tongue and a groove. These coupling parts are provided with integrated mechanical locking means, which prevent the moving of two coupled boards or panels apart in a direction perpendicular to the respective edges and parallel to the underside of the coupled floor panels. Preferably, these coupling parts are shaped in such a way that they allow any clearance between the boards or panels to be minimized, or more preferably excluded. In particular, for this purpose the coupling parts comprise an upper lip and a lower lip, which delimit the groove, and the tongue is a tongue-shaped element.

“Integrated mechanical locking means” is to be understood to mean that these form a fixed component of the boards or panels, either by being bonded rigidly to the boards or panels, or by being formed in one piece therewith. In one embodiment, the coupling parts are provided with locking means, which, in the coupled state of two or more of such boards or panels, exert a clamping force on each other, which forces the panels, for example floor panels, together. The result is that not only the formation of gaps is counteracted during application, but also the development of gaps at a later stage is counteracted.

According to some embodiments, the coupling parts are made in one piece with the polymer material of the polymer core of the panel, but not with the top layer or decorative and/or wear-resistant layer. This is for example the case when a coarse granular material is used as decorative and/or wear-resistant layer, such as grit. According to some other embodiments, the coupling parts are made in one piece with both the polymer material of the polymer core and with the polymer material of the top layer or decorative and/or wear-resistant layer. In some embodiments, the contact surface, more particularly the horizontally active contact surface on the sealing face of the panels, between the tongue-shaped element and the upper lip, is formed by the polymer material of the polymer core, and the top layer or decorative and/or wear-resistant layer is only present on a horizontal level above this contact surface. In some other embodiments, the contact surface, more particularly the horizontally active contact surface on the sealing face of the panels, between the tongue-shaped element and the upper lip, is formed by the polymer material of the top layer or decorative and/or wear-resistant layer, wherein a completely seamless decor is possible.

According to some embodiments, a part of the upper lip is formed by the top layer or decorative and/or wear-resistant layer, so that a continuous decor is possible between successive panels. According to some other embodiments, the granular material may partially cover and thus camouflage any seam between successive panels.

According to some embodiments, at least 10% of the thickness of the upper lip is formed by the polymer material of the top layer or decorative and/or wear-resistant layer. Preferably at least 20% of the thickness of the upper lip is formed by the polymer material of the top layer or decorative and/or wear-resistant layer, more preferably at least 40%, at least 60%, most preferably at least 80%.

According to some embodiments, said design of the coupling parts consists in that the panel has the following combination of properties: that the coupling parts and locking means are made in one piece with the polymer material of the polymer core and/or polymer material of the decorative and/or wear-resistant layer; that the coupling parts have a form such that two successive boards or panels may be fastened together exclusively by clicking into each other and/or turning, wherein each successive panel can be coupled sideways in the preceding one; that the coupling parts ensure clearance-free locking in all directions in the plane that is perpendicular to the aforementioned edges; that any difference between the upper lip and the lower lip of the lips that delimit the aforementioned groove, measured in the plane of the floor panel and perpendicular to the longitudinal direction of the groove, is less than 1×the total thickness of the panel; and that the total thickness of each related panel is greater than or equal to 4 mm or is greater than or equal to 5 mm.

In particular, when the coupling parts provide clearance-free locking, and these coupling parts are made from one piece from the polymer material of the polymer core and/or top layer or decorative and/or wear-resistant layer of the panel, a perfect join between adjacent floor panels can always be guaranteed, even in repeated expansion and contraction of the floor surface, for example under the effect of temperature changes.

This combination of properties may or may not be combined with the aforementioned property that stipulates that the locking means exert a clamping force on each other. According to a further or another embodiment, the properties of which may or may not be combined with the properties of the embodiments described above, the panel is characterized in that the lower lip, which delimits the underside of the groove, reaches farther than the upper lip; that the locking means are formed from at least one portion that slopes inwards; and that this portion is located, at least partially, in the portion of the lower lip that extends beyond the upper lip.

A third aspect of the present invention relates to a method for manufacturing an extruded, preferably decorative, panel, comprising the steps:

• • a) providing a polymer mixture to be extruded;
  • b) providing a finishing material;
  • c) transferring the polymer mixture to an extruder;
  • d) melting and extruding the polymer mixture by means of said extruder and one or more T-dies, wherein a plate material is obtained;
  • e) applying the finishing material;
  • f) optionally, calibrating the plate material to a desired thickness; and
  • g) optionally, cutting the plate material into one or more panels;
    and wherein the finishing material from step b) comprises a granular and/or fibrous material, and in step e) this finishing material forms a top layer or decorative and/or wear-resistant layer.

It is thus clear that the finishing material does not necessarily form the complete top layer of the decorative panel. It is also clear that the method of the third aspect is eminently suitable for manufacturing the panels with the characteristic features of the first and/or second aspect of the invention, as well as the preferred embodiments thereof.

A particular advantage of the present method is that both the decorative and the wear-resistant functions can be applied in a single layer, which greatly simplifies the production process, as well as the required raw material streams. Preferably, the top layer or decorative and/or wear-resistant layer extends through a substantial thickness, which leads to a considerable improvement in wear resistance, in comparison with techniques currently in use.

Preferably, application in step e) comprises the scattering of the granular and/or fibrous material. Scattering of the granular and/or fibrous material allows a homogeneous distribution thereof on and/or in the surface of the polymeric core, wherein a good-quality decor and a uniform wear resistance are obtained in a single step, i.e. application of a so-called scatter layer.

According to a further or another embodiment, the granular and/or fibrous material is selected from the group of stone, grit, gravel, quartz, aluminum oxide (Al₂O₃), polyvinyl chloride (PVC), synthetic fibers, textile fibers, natural fibers, or combinations thereof. Suitable synthetic fibers are nylon or PET fibers. The choice of the granular and/or fibrous material thus allows very varied decoration possibilities, without the need to apply an additional wear-resistant layer or to tailor such a layer specifically to this.

In some embodiments this scatter layer or layer of granular material has a thickness between 0.05 and 10.00 mm, preferably between 0.10 and 8.00 mm, more preferably between 0.50 and 5.00 mm. The scatter layer or layer of granular material is, in each of these embodiments, bonded to and/or in the polymer core, where it is to be understood that the scatter layer and the polymer core possibly run partially into each other. The scatter layer or layer of granular material with a thickness within the limits described herein allows the layer to form a relatively uniform decorative and/or wear-resistant layer, wherein the polymer core is only slightly or is not visible through this top layer or decorative and/or wear-resistant layer. In some embodiments the granular and/or fibrous material has a particle size and/or transverse dimension between 0.05 and 10.0 mm. According to some embodiments, particles with a larger particle size may also be used, wherein a coarser structured surface is obtained. Preferably the granular and/or fibrous material consists of particles with a particle size and/or transverse dimension between 0.10 and 8.00 mm, more preferably between 0.50 and 5.00 mm. Consequently, a relatively uniform spreading of the granular and/or fibrous material is possible, wherein a structured decorative and/or wear-resistant layer is formed, which differs markedly from for example a flat printed film.

According to some embodiments, the panel obtained comprises a coarse-structured surface, said surface being defined by the specific shape of the granular and/or fibrous material. In some embodiments the specific shape of the granular and/or fibrous material is flattened, for example by means of grinding techniques, possibly before scattering the granular and/or fibrous material, or else thereafter.

According to some embodiments, the individual particles of the granular and/or fibrous material have only limited hues, wherein a decor is obtained that is substantially uniform. According to some other embodiments, the individual particles of the granular and/or fibrous material have a number of different hues, wherein they display arbitrary ordering. In yet other embodiments, the individual particles of the granular and/or fibrous material display a number of different hues, and their ordering follows a pattern. It is thus clear that the decorative possibilities of the decorative and/or wear-resistant layer as described herein are very varied. Possibly, any voids between individual particles are filled with a polymer powder in order to obtain a more uniform surface.

According to a further or another embodiment, prior to step e) the polymer core is provided with a relief print. The forming of a relief print prior to application of the decorative and/or wear-resistant layer allows a panel to be obtained with a well-defined relief. Because the relief is applied prior to application of the top layer or decorative and/or wear-resistant layer, the wear-resistant properties of the panel obtained are not adversely affected thereby. Application of a relief further increases the decorative possibilities. Preferably, the final surface of the panel, for example the top layer formed by granular and/or fibrous material, also displays the relief that is applied in the surface of the polymer core. However, it is possible that this relief is available on the surface to a somewhat weakened extent, depending on the nature and dimensions of the granular and/or fibrous material.

With the same aim as in the third aspect, according to an independent fourth aspect the present invention relates to a method for manufacturing an extruded, preferably decorative, panel, comprising the steps:

• • a) providing a first and a second polymer mixture to be extruded;
  • b) transferring the first and the second polymer mixture to a first and a second extruder, respectively;
  • c) melting and co-extruding the first and the second polymer mixture by means of said first and second extruder respectively, and one or more T-dies, wherein a layered plate material is obtained;
  • d) optionally, calibrating the plate material to a desired thickness; and
  • e) optionally, cutting the plate material into one or more panels;
    and wherein the layer comprising the second polymer mixture forms a top layer or decorative and/or wear-resistant layer. In contrast to the application of decorative and/or wear-resistant films, the co-extruding of a decorative and/or wear-resistant layer allows a layer to be formed that has a substantial thickness, and consequently displays the required wear resistance intrinsically. Thus, both functions can be realized in one single layer. It is clear that the method of the fourth aspect is eminently suitable for manufacturing panels with the characteristic features of the second independent aspect and/or preferred embodiments thereof.

Preferably, the layer comprising the second polymer mixture comprises one or more colorants. The colorants stated herein allow the second polymer mixture to be provided partially, if not completely, with one or more colors, which contribute to the decor of the top layer or decorative and/or wear-resistant layer. Since this layer is manufactured to a substantial thickness, particularly according to the relations as described herein, the decor also extends through said substantial thickness. When a decorative film only provides the surface with decor, the present method thus makes it possible to form a deeper decor that is also visible along any saw cuts, or places where the decorative and/or wear-resistant layer is damaged locally and/or on the surface.

According to a further or another embodiment, the top layer or decorative and/or wear-resistant layer formed by means of co-extrusion also serves as a so-called Inkjet Receiver Coating (IRC). This IRC allows printing of the panel with a detailed decor, wherein the decorative possibilities are thus further increased. According to some embodiments the IRC comprises at least one pigment and a binder.

In some embodiments, the layer comprising the second polymer mixture is provided, between steps d) and e), with a decorative structure or relief by brushing said layer.

In a fifth independent aspect, for which it is clear that it serves the same purpose as each of the foregoing aspects, the present invention relates to a method for manufacturing a panel, comprising the steps:

• • a) providing a polymer mixture to be extruded;
  • b) providing a finishing material;
  • c) transferring the polymer mixture to an extruder;
  • d) melting and extruding the polymer mixture by means of said extruder and one or more T-dies, wherein a plate material is obtained;
  • e) applying the finishing material;
  • f) optionally, calibrating the plate material to a desired thickness; and
  • g) optionally, cutting the plate material into one or more panels;
    and wherein the finishing material from step b) is a pulverulent polymer material, said pulverulent polymer material being scattered, in step e), over the plate material, wherein a top layer or decorative and/or wear-resistant layer is formed, wherein the thickness of the decorative and/or wear-resistant layer and said plate material are in a ratio between 1:5 and 5:5. The advantage of this is that the top layer or decorative and/or wear-resistant layer displays an inherent wear resistance, wherein the need for application of separate and/or additional wear-resistant layers is eliminated. The decor of the top layer or decorative and/or wear-resistant layer now extends through a substantial thickness, so that the decor remains intact, even though this layer will display wear after a certain time. This contrasts with the decorative films as known from the prior art, wherein slight damage of the decorative film may already reduce the quality of the decor drastically, hence the need for a separate and/or additional wear-resistant film. Preferably the decorative and/or wear-resistant layer and the plate material are in a ratio between 2:5 and 4:5.

It is clear that the method of the fifth aspect is eminently suitable for manufacturing panels with the characteristic features of the first and/or second aspect of the invention and preferred embodiments thereof.

Preferably the pulverulent polymer material comprises one or more colorants. The colorants are distributed as uniformly as possible over the polymer material, or may be dosed specifically so that certain hues are obtained.

According to a further or another embodiment, application of the finishing material in step e) comprises the at least partial melting thereof.

According to a further or another embodiment, prior to step e), the polymer core is provided with a relief print. The forming of a relief print prior to application of the finishing material allows a panel to be obtained with a well-defined relief. Because the relief is applied prior to application of the finishing material, which forms a decorative and/or wear-resistant layer, the wear-resistant properties of the panel obtained are not adversely affected thereby. Application of a relief further increases the decorative possibilities.

In some embodiments, the polymer mixture to be extruded and/or the pulverulent material as described in the third, fourth and/or last aspect comprises one or more polymers from the group of polyolefins, for example polyethylene, polypropylene, polyvinyl chloride, or copolymers thereof.

Preferably the polymer mixture to be extruded comprises polyvinyl chloride (PVC). Preferably, the polyvinyl chloride has a concentration of at least 95 wt %, more preferably at least 99 wt %, most preferably 100 wt %.

It is possible that the polymer mixture to be extruded further comprises one or more fillers selected from the group of inorganic fillers, such as chalk, lime and/or talc, or organic fillers, such as wood, bamboo and/or cork, or mineral fillers.

The polymer mixture to be extruded and/or the pulverulent polymer material preferably comprise polyvinyl chloride (PVC) and calcium carbonate (CaCO₃) as filler.

Preferably, the polymer mixture to be extruded and/or the pulverulent polymer material comprise one or more additives selected from the group of Ca/Zn stabilizers, impact strength modifiers, waxes, plasticizers or combinations thereof. Preferably, the content of plasticizer in the material of the top layer or decorative and/or wear-resistant layer is higher than in the aforementioned plate material, and/or 15 phr plasticizer or more is used in the material of the top layer. The use of high plasticizer contents in the top layer leads to a comfortable walking comfort with an acceptable sound of walking.

It is to be noted that the plate material may be foamed, and may, for example, display a weight reduction of at least 15%, or even at least 20 or 25%, relative to an unfoamed material with the same composition.

The particle size of the polyvinyl chloride (PVC) is, according to some embodiments, between 50.0 and 250.0 μm, preferably between 80.0 and 200.0 μm, or between 250.0 and 500.0 μm. According to some embodiments the particle size of the calcium carbonate (CaCO₃) is between 0.5 and 20.0 μm, preferably between 1.0 and 10.0 μm.

According to some embodiments, the calcium carbonate (CaCO₃) has a concentration of at most 80 wt % and the polyvinyl chloride (PVC) has a concentration of at least 20 wt %. Preferably, the calcium carbonate (CaCO₃) has a concentration between 10 and 80 wt % and the polyvinyl chloride (PVC) has a concentration between 20 and 90 wt %. More preferably, the calcium carbonate (CaCO₃) has a concentration between 60 and 80 wt % and the polyvinyl chloride (PVC) has a concentration between 20 and 40 wt %. It was found that a particularly good result is achieved when the proportion of calcium carbonate is greater than the proportion of PVC. Preferably, the calcium carbonate (CaCO₃) has a concentration between 65 and 80 wt % and the polyvinyl chloride (PVC) has a concentration between 20 and 35 wt %. More preferably, the calcium carbonate (CaCO₃) has a concentration between 70 and 80 wt % and the polyvinyl chloride (PVC) has a concentration between 20 and 30 wt %. Most preferably, the calcium carbonate (CaCO₃) has a concentration of 75 wt % and the polyvinyl chloride (PVC) has a concentration of 25 wt %.

Of course, a possible proportion of additives should be taken into account. According to some embodiments, the concentration of the additives is at most 5 wt %.

According to a further or another embodiment, prior to transfer of the polymer mixture to be extruded to the extruder, the polymer mixture is heated to a temperature between 100 and 140° C. until the polyvinyl chloride (PVC) softens to a kneadable composition and the calcium carbonate (CaCO₃) binds at least partially to the polyvinyl chloride (PVC).

Preferably, after heating the polymer mixture, and prior to the melting and extruding thereof, it is cooled to a temperature between 40 and 50° C.

According to some embodiments, the plate material is calibrated to the desired thickness by means of at least two calender rolls. Preferably, the plate material is calibrated to the desired thickness by means of at least three, four or five calender rolls.

A sixth independent aspect of the present invention relates to an installation for manufacturing a panel, said installation comprising an extruder and a scattering unit, said scattering unit being configured downstream of said extruder. The installation as described herein allows the manufacture of a panel according to the first and/or second aspect, and/or the manufacture of a panel by means of one of the methods described herein, wherein a polymer core can be formed by means of the extruder, after which the scattering unit can apply a top layer or decorative and/or wear-resistant layer on this polymer core. This top layer or decorative and/or wear-resistant layer possibly comprises a granular and/or fibrous material, or comprises a pulverulent polymer material in the ratios as described in preceding embodiments. A particular advantage of the installation is that an innovative top layer or decorative and/or wear-resistant layer can be applied on the polymer core of a panel in just a single step, wherein there is no longer a need to provide several finishing layers. The installation thus provides a simplified production technique, which in addition offers a wide range of finishing possibilities.

According to some embodiments, the scattering unit is configured so that a uniform decor can be applied, in which individual particles of the granular and/or fibrous material, or pulverulent polymer material, display only limited hues, and/or wherein said particles are mixed homogeneously prior to the scattering thereof.

According to some embodiments, the scattering unit is configured so that a decor pattern can be applied, in which individual particles of the granular and/or fibrous material, or pulverulent polymer material, display a number of different hues, and wherein they are ordered according to a pattern.

According to some embodiments, the installation comprises one or more T-dies, said T-dies being configured between the extruder and the scattering unit. These T-dies allow the formation of a substantially plate-shaped polymer core, on which homogeneous distribution and binding of the decorative and/or wear-resistant layer is possible.

According to a further or another embodiment, the installation comprises at least two calender rolls, said calender rolls preferably being configured downstream of said scattering unit. According to some embodiments, the installation comprises at least two calender rolls, which are configured both upstream and downstream of said scattering unit. These calender rolls make it possible to adjust the thickness of the panels obtained and give improved adhesion of the decorative and/or wear-resistant layer to the polymer core of the panel obtained.

The installation possibly comprises one or more additional calender rolls, which may provide the polymer core with a relief, said additional calender rolls preferably being configured upstream of said scattering unit. The decorative possibilities are further increased thereby, without having an adverse effect on the wear-resistant properties of the panel obtained.

According to a seventh, or respectively eighth independent aspect, the present invention further relates to a decorative panel and a method for manufacturing decorative panels. More particularly, according to the seventh independent aspect, the invention relates to decorative panels with a cement-bonded top layer, and according to the eighth independent aspect it relates to a method for manufacturing said panels.

According to its seventh independent aspect, the invention is a panel, preferably a decorative panel, which comprises a substrate and a top layer, preferably a decorative and/or wear-resistant layer, wherein the substrate comprises a polymer-based material, a wood-based material or a combination thereof, characterized in that it comprises one or more cement-based layers of material. The decorative panel of the invention may have an upper side that has a realistic appearance of cement, stone or concrete, and may in essence be handled and/or installed as easily as synthetic or wood-based panels from the prior art. The panels of the invention may be considerably lighter than real cement, stone or concrete tiles such as are known in the prior art.

According to its eighth independent aspect, the invention is a method for manufacturing, preferably decorative, panels, wherein the method comprises at least the following steps:

• • step S1 of providing a substrate or core, wherein said substrate consists of a polymer-based material, a wood-based material or a combination thereof; and
  • step S2 of providing a top layer on the aforementioned substrate, wherein step S2 of application of said top layer on the aforementioned substrate comprises the step S2b of application of one or more cement-based layers of material.

According to preferred embodiments of the seventh aspect, the panels have one or more of the following characteristic features:

• • the feature that the substrate is almost free from cement-based or cement-bonded material;
  • the feature that each of said one or more cement-based layers of material has a thickness of between 0.4 and 1.0 mm, preferably between 0.5 and 0.7 mm;
  • the feature that one or more cement-based layers of material have a total thickness between 1.0 and 5.0 mm, preferably between 2.5 and 3.5 mm;
  • the feature that the top layer comprises at least 3 cement-based layers of material, preferably at least 4 cement-based layers of material, and preferably at least 5 cement-based layers of material;
  • the feature that at least one of said cement-based layers of material is fiber-reinforced, preferably glass-fiber reinforced;
  • the feature that the top layer comprises at least 3 cement-based layers of material, wherein the top 2 layers of the aforementioned cement-based layers of material are fiber-reinforced, preferably glass-fiber reinforced; preferably the feature that the top layer comprises at least 5 cement-based layers of material, wherein the top 3 layers of these cement-based layers of material are fiber-reinforced, preferably glass-fiber reinforced;
  • the feature that the cement-based layers of material comprise at least aluminum-containing cement and one or more additives selected from the group of coarse sand, river sand, elastic resin or combinations thereof;
  • the feature that the top layer comprises an upper sealing layer, which is positioned on top of the uppermost cement-based layer of material; preferably the feature that the upper sealing layer comprises one or more acrylate compounds;
  • the feature that the top layer comprises one or more substrate sealing layers, wherein the substrate sealing layers are located between the substrate and the lower cement-based layer of material; preferably the feature that the one or more substrate sealing layers comprise at least one first substrate sealing layer, wherein the first substrate sealing layer is located closest to the substrate and the first substrate sealing layer comprises one or more polyurethane compounds (PU); preferably the feature that the one or more substrate sealing layers comprise at least one second substrate sealing layer, wherein the second substrate sealing layer is located closest to the lower cement-based layer of material and the second substrate sealing layer comprises one or more acrylate compounds; preferably wherein the top layer comprises at least three substrate sealing layers, wherein the bottom two substrate sealing layers comprise one or more polyurethane compounds (PU) and wherein the upper substrate sealing layer comprises one or more acrylate compounds; preferably wherein the top layer comprises at least 5 substrate sealing layers, wherein the bottom 4 substrate sealing layers comprise one or more polyurethane (PU) compounds and wherein the upper substrate sealing layer comprises one or more acrylate compounds;
  • the feature that the substrate comprises a polymer core or comprises a material based on polymers, preferably a thermoplastic material selected from the group polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyvinyl chloride (PVC) or combinations thereof, wherein the thermoplastic material is preferably polyvinyl chloride (PVC); preferably wherein the substrate contains more than 40 wt % fillers, preferably between 65 and 85 wt % fillers, preferably the substrate contains between 65 and 85 wt % chalk and/or limestone;
  • the feature that the substrate comprises a reinforcing layer, preferably a glass-fiber layer;
  • the feature that the decorative panel is provided with coupling parts on at least two sides located opposite each other, so that two such panels can be coupled together on the respective edges, wherein, in the coupled state, locking is obtained in the vertical direction perpendicular to the plane of the coupled panels, and in the horizontal direction in the plane of the coupled panels and perpendicular to said edges; preferably wherein the coupling parts are formed largely in the substrate, for example to at least 70% of their respective contour seen in cross section on the respective side; and/or
  • the feature that on the upper side, on at least two edges opposite each other, the decorative panel is provided with a lowered edge region, preferably a chamfer or an imitation joint; preferably wherein the lowered edge region is varnished and/or painted.

According to preferred embodiments of the eighth aspect, the method has one or more of the following characteristic features:

• • the feature that the substrate is almost free from cement-based or cement-bonded material;
  • the feature that each of the cement-based layers of material applied in step S2b has a thickness between 0.4 and 1.0 mm, preferably between 0.5 and 0.7 mm;
  • the feature that one or more cement-based layers of material in step S2b have a total thickness between 1.0 and 5.0 mm, preferably between 2.5 and 3.5 mm;
  • the feature that in step S2b, one or more cement-based layers of material are applied in an amount between 750 and 1500 g/m², preferably between 950 and 1250 g/m²;
  • the feature that each of the cement-based layers of material applied in step S2b is dried and/or cured for 5 to 15 hours, preferably 8 to 12 hours;
  • the feature that step S2b comprises the application of at least three cement-based layers of material, preferably at least four cement-based layers of material, and preferably at least five cement-based layers of material;
  • the feature that at least one of said cement-based layers of material is fiber-reinforced, preferably glass-fiber reinforced;
  • the feature that step S2b comprises the application of at least 3 cement-based layers of material, the top 2 layers of which are fiber-reinforced, preferably glass-fiber reinforced; preferably wherein step S2b comprises the application of at least 5 cement-based layers of material, wherein the top 3 layers of said cement-based layers of material are fiber-reinforced, preferably glass-fiber reinforced;
  • the feature that the cement-based layers of material at least comprise aluminum-containing cement and one or more additives selected from the group of coarse sand, river sand, elastic resin or combinations thereof;
  • the feature that step S2b comprises the scraping of each of said cement-based layers of material to the desired level;
  • the feature that step S2 of application of the top layer on the substrate comprises step S2c of the application of an upper sealing layer on top of the uppermost cement-based layer of material, which is carried out after step S2b; preferably wherein the upper sealing layer comprises one or more acrylate compounds; preferably wherein the upper sealing layer in step S2c is applied in an amount between 50 and 100 g/m², preferably between 50 and 70 g/m²; preferably wherein the upper sealing layer applied in step S2c is dried and/or cured for 2 to 6 hours, preferably 3 to 5 hours; preferably wherein the upper sealing layer is applied by means of a paint roller;
  • the feature that step S2 of application of the top layer on the substrate comprises step S2a of the application of one or more substrate sealing layers, which is carried out before step S2b, wherein said substrate sealing layers are located between the substrate and the lower cement-based layer of material; preferably wherein step S2a comprises at least one first substrate sealing layer, wherein said first substrate sealing layer is located closest to the substrate and said first substrate sealing layer comprises one or more polyurethane compounds (PU); preferably wherein step S2a comprises a second substrate sealing layer, wherein the second substrate sealing layer is located closest to the lower cement-based layer of material and the second substrate sealing layer comprises one or more acrylate compounds; preferably wherein step S2a comprises at least three substrate sealing layers, wherein the bottom two substrate sealing layers comprise one or more polyurethane compounds (PU) and the upper substrate sealing layer comprises one or more acrylate compounds; preferably wherein step S2a comprises the application of at least 5 substrate sealing layers, wherein the bottom 4 substrate sealing layers comprise one or more polyurethane (PU) compounds and the upper substrate sealing layer comprises one or more acrylate compounds; preferably wherein the substrate sealing layer in step S2a is applied in an amount between 50 and 100 g/m², preferably between 50 and 75 g/m²; preferably wherein the substrate sealing layer applied in step S2a is dried and/or cured for 2 to 8 hours, preferably 4 to 6 hours; preferably wherein each of said one or more substrate sealing layers is applied by means of a paint roller;
  • the feature that step S1 of providing the substrate is carried out by extrusion;
  • the feature that the substrate comprises a polymer core 2 or a polymer-based material, preferably a thermoplastic material selected from the group of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyvinyl chloride (PVC) or combinations thereof, wherein the thermoplastic material is preferably polyvinyl chloride (PVC); preferably wherein the substrate contains more than 40 wt % fillers, preferably 65 to 85 wt % fillers, and preferably 65 to 85 wt % lime and/or limestone;
  • the feature that the substrate comprises a reinforcing layer, preferably a glass-fiber layer; and/or
  • the feature that a decorative panel with the features of the seventh aspect and/or the preferred embodiments thereof is obtained.

In general it should further be noted that a cement-based layer of material generally means a cement-bonded layer of material, wherein the cement content need not necessarily be 50 wt % or more. It is possible, for example, to work with a cement content of 30 wt % or less.

Moreover, the purpose of the following table is to illustrate a particular preferred embodiment of the invention, according to its seventh and/or eighth aspect, and describes various features of a decorative panel and a method for manufacturing a panel of this kind. Column A gives the type of layer, arranged from top to bottom, i.e. from the upper side of the panel to the underside of the panel. Column B shows the number of layers of the corresponding type of layer; column C gives the materials of the corresponding type of layer; column D gives the thickness of each of the separate layers of the corresponding type of layer, expressed in millimeters (mm); column E shows the application weight of each of the separate layers of the corresponding type of layer, expressed in grams per square meter (g/m²); and column F shows the drying and/or curing time of each of the separate layers of the corresponding type of layer, expressed in hours (h).

In column D, “liquid penetration” means that the material in question from column B penetrates into an underlying layer and thus adds little if anything to the thickness of the panel. The thickness of the actual substrate may be selected freely, and is for example between 2 and 10 mm, better still between 3 and 6 mm, wherein a substrate thickness of about 4 to 5 mm is a good value, wherein sufficient stability of the whole may be obtained, while the weight of the panel remains limited.

A	B	C	D	E	F

Upper	1	Acrylate compounds	Liquid	62.5	4
sealing layer			penetration
Fiber-reinforced	3	Aluminum-	0.7	1250	8
cement-		containing cement,
based layer		fiber, elastic resin,
of material		coarse sand, river
		sand
Cement-based	2	Aluminum-	0.5	950	12
layer of		containing cement,
material		elastic resin, river
		sand
First substrate	1	Acrylate compounds	Liquid	62.5	4
sealing layer			penetration
Second substrate	4	Polyurethane (PU)	Liquid	70	6
sealing layer		compounds	penetration
Substrate	1	Polyvinyl chloride	—	—	—
		(PVC), fillers

For the purpose of better demonstrating the features of the invention, some preferred embodiments, as examples without any limiting character, are described hereunder, referring to the appended drawings, in which:

FIG. 1 shows a floor panel with the features of the invention, as well as a local enlargement of the decorative and/or wear-resistant layer;

FIG. 2 shows a cross section according to line II-II shown in FIG. 1;

FIGS. 3 to 9 show a variant, in an identical view as FIG. 2;

FIGS. 10 to 13 show further variants in a view according to line X-X shown in FIG. 1;

FIG. 14 shows schematically some steps in a method with the features of the invention;

FIG. 15 shows schematically some steps in another method with the features of the invention; and

FIG. 16 shows schematically some steps in a method with the features of the eighth aspect of the invention.

FIG. 1 shows a panel 1 according to the invention. As shown in FIG. 2, the panel 1 comprises a polymer core 2 and, at least partially bonded thereon, a decorative and/or wear-resistant layer 3, which comprises a granular material 4. Herein, this material 4 may for example be stone, grit, gravel, quartz, or a combination thereof. This granular material 4 provides the panel with an innovative decorative appearance and has the advantage that it inherently endows the panel with high wear resistance. Thus, application of an additional wear-resistant layer, although still possible, is no longer essential. The polymer core 2 comprises a polymer material 5, preferably polyvinyl chloride (PVC) and calcium carbonate (CaCO₃) as filler. Suitable particle sizes of the calcium carbonate (CaCO₃) are in the range between 1 and 10 μm. FIG. 3 also shows a panel 1, which comprises a polymer core 2 and a decorative and/or wear-resistant layer 3 at least partially bonded thereon. The decorative and/or wear-resistant layer 3 comprises a substantially granular, particularly pulverulent, material 4. This fine material 4 possibly comprises stone, grit, gravel, quartz, aluminum oxide (Al₂O₃), polyvinyl chloride (PVC), or combinations thereof. The substantially granular, particularly pulverulent, material 4 thus endows the panel with an innovative decorative appearance, as well as an inherently present wear resistance.

FIGS. 4 and 5 show a panel 1 comprising a polymer core 2 and a decorative and/or wear-resistant layer 3 at least partially bonded thereon, wherein the thickness of said decorative and/or wear-resistant layer 3 and the thickness of said polymer core 2 are in a ratio of 1:5, or of 2:5. It is thus clear that this ratio may according to the present invention lie within the complete range between 1:5 and 5:5. Since the decorative and/or wear-resistant layer 3 has a considerable thickness relative to the thickness of said polymer core 2, this layer provides the aforementioned two functions simultaneously, and application of an additional wear-resistant layer, although this is still possible, is no longer essential. It is to be understood that the decorative and/or wear-resistant layer 3 as shown herein is not per se of above average hardness or scratch-resistant, it is in essence the thickness of the layer that ensures that there is a certain margin for wear. The decorative and/or wear-resistant layer 3 may wear to some limited extent after a period of time, but the quality of the panel is not reduced thereby. Both the decorative and/or wear-resistant layer 3 and the polymer core 2 comprise a polymer material 6, 5, preferably comprising polyvinyl chloride (PVC) and calcium carbonate (CaCO₃) as filler. In essence, the embodiments described herein form a good-quality imitation of a compact vinyl tile (CVT).

FIGS. 6, 7, 8 and 9 show in essence the respective panels 1 from FIGS. 2, 3, 4 and 5, wherein a comfort layer 7 is provided on the underside thereof, i.e. located on the side opposite to the decorative and/or wear-resistant layer 3 of the polymer core 2. Thus, the panel comprises a successive stratification from bottom to top: the comfort layer 7, the polymer core 2 and the decorative and/or wear-resistant layer 3. Suitable materials for the comfort layer 7 possibly comprise a foamed plastic layer, such as foamed polyethylene (PE), a crosslinked plastic layer, such as IXPE, or cork.

FIGS. 10, 11, 12 and 13 show in essence the respective panels 1 from FIGS. 6, 7, 8 and 9, wherein at the edges of two sides located opposite each other, the panel is provided with interacting coupling parts, substantially comprising a tongue-shaped element 8 and a groove 9, said groove 9 being defined by an upper lip 10 and a lower lip 11. It is obvious that each of the features discussed are combinable together, and thus the coupling parts shown herein may also be provided on the panels 1 from FIGS. 2, 3, 4 and 5, i.e. in the absence of a comfort layer 7. The coupling parts are provided with locking means, which possibly in the gripped state of two or more of such boards exert a clamping force on each other, which forces the floor panels together. Therefore it is achieved that not only during application, the formation of gaps is counteracted, but also at a later stage the development of gaps is counteracted. It can be seen in FIGS. 10 and 11 that the coupling parts are made as one piece with the polymer material 5 of the polymer core 2 of the panel 1. It can be seen in FIGS. 12 and 13 that, depending on the ratio of the thickness of the polymer core 2 to the thickness of the decorative and/or wear-resistant layer 3, the coupling parts are made as one piece with both the polymer material 5 of the polymer core 2 and with the polymer material 6 of the decorative and/or wear-resistant layer 3.

FIG. 14 shows a method for manufacturing a panel, comprising the steps: (a) providing a polymer mixture 12 to be extruded; (b) providing a finishing material; (c) transferring the polymer mixture 12 to an extruder 13; (d) melting and extruding the polymer mixture 12 by means of said extruder 13 and one or more T-dies 14, in the present case only one T-die 14, wherein a plate material, or also polymer core 2, is obtained; (e) applying the finishing material. FIG. 14 shows further the optional step (f) relating to the calibration of the plate material and the finishing material to a desired thickness. The optional step (g) relating to the cutting of the plate material into one or more panels is not shown here. The finishing material from step b) is in this case a granular material 4, and forms a decorative and/or wear-resistant layer 3 in step e). The plate material is calibrated herein to the desired thickness by means of calender rolls 15.

FIG. 15 shows a method for manufacturing a panel, comprising the steps: (a) providing a first 16 and a second polymer mixture 17 to be extruded; (b) transferring the first 16 and the second polymer mixture 17 to a first 18 and a second extruder 19, respectively; (c) melting and co-extruding the first 16 and the second polymer mixture 17 by means of said first 18 and second extruder 19 respectively, and one or more T-dies 14, in the present case only one T-die 14, wherein a layered plate material 20 is obtained. FIG. 15 further shows the optional step (d) relating to the calibrating of the layered plate material 20 to a desired thickness. The optional step (e) relating to the cutting of the layered plate material 20 into one or more panels is not shown here. The layer comprising the second polymer mixture 17 forms a decorative and/or wear-resistant layer 3 herein. The plate material is calibrated herein to the desired thickness by means of calender rolls 15.

In general, it should further be noted that the panel according to any aspect of the invention may have any shape whatever. The panel in the examples has two pairs of parallel opposite sides, and is configured rectangular and square, or almost square, so that this panel may for example be installed in a checkerboard pattern with other similar panels. It is clear that said panel may also be configured rectangular and elongated, namely with a pair of long opposite parallel sides and a pair of short opposite and parallel sides. In general it is preferred that the panel of the invention has at least one pair of parallel opposite sides. It is clear that the respective sides are then preferably configured to be rectilinear. However, it is not excluded that the respective opposite sides could be configured other than rectilinear. Preferably, the respective two opposite sides are in such a case at least partially complementary, namely so that a first of the respective sides is complementary to at least half of the second of the respective sides of a similar panel. In this way, such panels may be assembled to a floor covering without a marked gap. A panel that has at least one pair of opposite complementary, non-rectilinear, sides may give rise to the masking of seams between two such panels, even if the decorative and/or wear-resistant layer should comprise relatively coarse granular material.

Furthermore, it should also be noted that in the case when the decorative layer and/or wear-resistant layer comprise granular material, the particles of this granular material on the edges of the panel, on one or more sides thereof, may or may not be cut through. The optional cutting through may, in the case of mineral or stone particles, such as pebbles or gravel, be carried out on the basis of waterjet or laser processing. The cutting through of the granular material on the edge of the panels may lead to a good join of such panels in a floor covering. When the granular material is not cut through, on one or more of the edges of the panel a portion of the surface of the polymer core may be free from granular material, so that even in this case a good join of the panels may be obtained on the respective edge. Said portion may be configured as a lowered edge portion or chamfer. Said portion preferably has a width, measured perpendicular to the respective edge, which corresponds to 0.1 to 5 times the average particle size of the granular material used, or better still 0.5 to 2 times the average particle size. In the floor covering, said portion may form per se an imitation of a cement joint, or may be filled on the basis of a jointing means. In the latter case, a waterproof surface can be obtained.

FIG. 16 shows a possible scheme for carrying out a method with the features of the eighth aspect of the invention.

In a step S1, a substrate is provided, preferably based on polymer. It may then be important to check the flatness and/or the compressive strength of the substrate. Optionally, the state of the surface of the substrate may also be checked, for example whether or not cracks or pits are present in the surface. It is preferable to work with substrates that have a flatness in a maximum tolerance of ±0.2 mm.

In a step S2, a top layer is provided on the substrate. In the example, step S2 is carried out in several substeps S2A, S2B, S2C.

In a step S2A, the aforementioned surface is sealed by means of one or more substrate sealing layers, for example based on polyurethane compounds and/or acrylate compounds.

In a step S2B, in this case several cement-based layers of material are applied. This operation starts with substep 21A of preparing the cement mix. In substep 22A, three cement-based layers of material are applied successively, for example each with a thickness of about 1 mm. In this case particular attention is paid to the flatness of the layers of material, for example by processing by scraping. The layers of material dry or cure for 24 hours. After curing, the layer obtained is abraded in substep 23A with a view to improving the flatness and the uniformity of the surface.

The steps described thus far may take up to 2 days.

In substep 21B, a cement mix may then be prepared for application of for example two further cement-based layers of material in substep 22B. Each layer of material may then have a thickness of 1 to 2 mm. After application of the first layer of material in substep 21B, it may be important to monitor the condition thereof very carefully, and apply the second cement-based layer of material at the moment when the first cement-based layer of material is only half-dry. Increased dimensional stability may be obtained thereby. The layers of material then dry or harden for 8 hours. After curing, the layer obtained is abraded in substep 23B, again with a view to improving the flatness and the uniformity of the surface.

The steps described for this may take up to 3 days.

In step S2C, a sealing layer is applied on the uppermost cement-based layer of material. This may comprise acrylate compounds or for example may be a two-component polyurethane coating. Thus, for example four layers of said sealing layer may be applied, for example to obtain a total thickness of the panel of 3 to 5 mm. Preferably, each sealing layer is cured for at least 6 hours. With the sealing layer, a waterproof surface is obtained. Application of the sealing layers may take one day.

It is obvious that after installation of a floor covering that consists of panels obtained on the basis of the method of the eighth aspect, for example as illustrated on the basis of FIG. 16, maintenance treatments may be necessary. Preferably, maintenance treatments are carried out with a neutral cleaning agent and/or an almost dry cloth. The regular use of polishing machines is possible.

The present invention is by no means limited to the embodiments described above; said plate materials and relevant methods for the manufacture thereof may be realized according to many variants while remaining within the scope of the present invention.