Decorative floor covering element and method for producing such element

Abstract

The invention relates to a decorative covering element, in particular a decorative floor covering element (e.g., a floor panel), a decorative wall covering element (e.g., a wall panel), a decorative ceiling covering element (e.g., a ceiling panel), a wall panel or a ceiling panel. The invention also relates to a post-use treatment method of a recycled decorative covering element, in particular a floor covering element according to the invention.

Description

Technical Field

[0001] The present invention relates to a decorative covering element, in particular a decorative floor covering element (e.g. a floor panel), a decorative wall covering element (e.g. a wall panel), a decorative ceiling covering element (e.g. a ceiling panel), a wall panel or a ceiling panel. The invention also relates to a post-use treatment method for recycled decorative covering elements according to the invention, in particular floor covering elements. Background Art

[0002] The floor covering industry mainly uses traditional core materials to manufacture (laminated) floor tiles. Examples of common materials that constitute the core layer of known floor tiles are: high-density fiberboard (HDF), which can combine formaldehyde or phenolic resins, heterogeneous or homogeneous polyvinyl chloride (PVC) (which may contain any plasticizers), solid hardwood blocks or multiple layers of veneers glued together, and fired and glazed clays such as ceramics and porcelain tiles. The use of these materials depends mainly on their material properties, such as impact resistance, stiffness, acoustic properties and / or appearance. Usually, at least one backing layer is fixed to the core, which backing layer can serve as a balancing layer. An example of such a balancing layer is a layer comprising wood cellulose and a cured resin. The backing layer can also consist of a sound-absorbing layer, which usually consists of a low-density ethylene vinyl acetate (EVA) or cork foam layer.

[0003] With increasing environmental awareness and stricter regulations, there is a growing trend towards environmentally friendly methods for recycling the layers of floor tiles after use. However, to properly recycle these layers, especially when they consist of different materials and / or polymers, they need to be separated, which is very difficult in practice. The adhesives, usually polyurethane (PU) adhesives, used to bond the layers to each other are intended to produce high bond strength and achieve a durable bond between the layers, which makes it difficult or even impossible to properly peel off the layers after use without damaging them. Therefore, the recycling of floor tiles known in the prior art is affected by the following factors: the inability to achieve a clear separation of the layers, which leads to contamination of each separated base material stream handled during the recycling process. In addition, PU adhesives, which are often used as two-component or one-component adhesives, are based on the chemical reaction of different components, which makes the use of PU adhesives not without risks. On the contrary, PU adhesives are well-known for their health hazards, which is why they are subject to safety regulations (such as the German Chemical Ban Ordinance) and cannot be sold to people under the age of 18 in most jurisdictions. Specific safety measures are stipulated for the use of PU adhesives. Summary of the Invention

[0004] A first object is to provide an improved decorative covering element, in particular a decorative floor covering element, which can be handled in an improved manner after use.

[0005] A second object is to provide an improved decorative covering element, in particular a decorative floor covering element, the components of which can be recycled more easily.

[0006] A third object is to provide an improved decorative covering element, in particular a decorative floor covering element, which can be produced in a relatively safe manner.

[0007] In order to meet at least one of the above objects, the present invention provides a decorative covering element according to the preamble, comprising:

[0008] at least one core layer,

[0009] a decorative top structure fixed directly or indirectly to the upper side of the core layer,

[0010] a backing layer fixed indirectly or indirectly via an intermediate connecting layer to the underside of the core layer and / or a decorative surface layer fixed directly or indirectly via an intermediate connecting layer to the upper side of the core layer,

[0011] wherein the (at least one) connecting layer is compatible with two adjacent layers (e.g., the core layer and the backing layer and / or the core layer and the decorative surface layer), and wherein the connecting layer is bonded to at least one of the adjacent layers (e.g., at least one of the core layer and the backing layer and / or at least one of the core layer and the decorative surface layer and / or at least one of the backing layer and another adjacent layer) via hydrogen bonding.

[0012] The decorative covering element according to the present invention can be a decorative floor covering element (e.g., a floor panel), a decorative wall covering element (e.g., a wall panel), a decorative ceiling covering element (e.g., a ceiling panel), a wall panel, or a ceiling panel, hereinafter referred to as a floor covering element. A significant advantage of the floor covering element according to the present invention is that a tie layer, which bonds the backing layer to the core layer, replaces conventional adhesives that chemically bond the backing element to the core layer. The tie layer can be an extremely thin layer, in particular a monomolecular layer, that provides a sufficiently strong bond between the backing layer and the core layer, at least in part due to the formation of hydrogen bonds between the tie layer and at least one adjacent layer. While the hydrogen bridges formed are relatively weak, sufficiently strong bonds are still formed between the tie layer and the at least one adjacent layer for the intended normal use of the floor covering element. These relatively weak bonds between the backing layer and the core layer facilitate separation of the layers after use. This separation can typically be easily achieved by sufficiently heating the floor covering element (typically to a temperature between 80 and 150 degrees Celsius) and then pulling apart the layers to be separated. After separation, the layers can be processed individually and recycled separately to make new products, including new decorative floor covering elements. Since the tie layer can be very thin, even as thin as a monomolecular layer as described above, no visible residue and no significant residue is left after the layers are separated after use. In addition, the tie layer generally does not mechanically penetrate into the porous adjacent layers (such as the core layer), thereby keeping the core layer clean and free of contamination, which facilitates the post-use recycling of the core layer after separation from the backing layer and preferably after separation from the decorative top structure. The tie layer generally acts as a compatibilizer, bonding incompatible layers together. Incompatible layers are layers with different material compositions, in particular layers based on different (main) polymers, which often cannot be bonded to each other by welding, and therefore require additional layers to achieve interlayer bonding. Another advantage of using a tie layer is that the properties of the material of the tie layer pose a low health hazard, which makes it relatively safe to handle. As described below, typically at least one of the layers to be bonded (e.g., a backing layer) will be pre-treated, in particular modified at least on its surface, so as to bond to the other layer (e.g., a core layer), thereby promoting easy and smooth bonding between the two layers. The establishment of hydrogen bonds between the connecting layer and the adjacent layer (e.g., a core layer) is typically achieved by pressing the layers to be bonded to each other at high temperature for a short period of time. In fact, the process conditions for lamination can be similar to those for delamination, except that the direction of force application is different. More specifically, during lamination, the layers to be bonded are pressed onto each other and toward each other, while during delamination, the layers to be separated are pulled apart and / or moved relative to each other.

[0013] The core layer may comprise a (mainly) polymer, preferably a thermoplastic material, more preferably selected from the group consisting of: PVC, PET, PETG (PP, PS, thermoplastic polyurethane (TPU), PE, in particular MDPE and / or HDPE; and combinations thereof.

[0014] Preferably, at least one core layer and / or the backing layer (and / or at least one decorative layer (applied on the core layer)) comprises at least one thermoplastic material selected from the group consisting of polypropylene (PP), thermoplastic polyurethane (TPU), polystyrene (PS), polyethylene (PE), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polyvinyl chloride (PVC), and furan resin. The at least one thermoplastic base layer (e.g., core layer) can be solid or foamed. Although the decorative layer can also be foamed, in most embodiments, this layer is a solid (unfoamed) layer, more particularly a solid film. The polymer used in the floor covering element layer (preferably an extruded floor covering element layer) preferably consists at least partially of a polymer formed from a mixture of virgin polymer material, recycled polymer material, or a combination of virgin and recycled polymer materials. Preferably, the at least one polymer used in the floor covering element layer, preferably an extruded floor covering element layer, is preferably enriched with at least one additive, preferably the at least one additive is selected from the group consisting of talc, chalk, wood, calcium carbonate, titanium dioxide, calcined clay, ceramics, glass particles, glass fibers, carbon particles, silicon particles, (other) mineral fillers, rice, textile fibers (e.g. cotton fibers) and other natural fillers.

[0015] Preferably, the furan resin optionally used for at least one core layer and / or at least one decorative top layer is at least one furan resin selected from the group consisting of poly(ethylene 2,5-furandicarboxylate) (PEF), poly(propylene 2,5-furandicarboxylate) (PPF), poly(butylene 2,5-furandicarboxylate) (PBF), poly(1,4-cyclohexanedimethylene-2,5-furandicarboxylate) (PCHDMF), poly(trimethylene furan dicarboxylate) (PTF), poly(neopentyl 2,5-furandicarboxylate) (PNF) and mixtures thereof. According to the invention, the furan resin optionally used for the floor covering element may be a homopolymer or a copolymer, for example a random copolymer or a block copolymer. An example of such a furan(-based) copolymer is poly(ethylene 2,5-thiophenedicarboxylate-co-ethylene 2,5-furandicarboxylate) (PEThF).

[0016] The PS can be in the form of expanded PS (EPS) to further reduce the density of the floor covering elements, thereby saving costs and facilitating panel handling. Furthermore, if other thermoplastic materials are used, they can be applied to the core in a foamed state to reduce density and cost. However, it is also conceivable that the thermoplastic material used as the main polymer is a solid polymer (i.e., an unfoamed polymer). Preferably, at least a portion of the polymer used can be made from recycled thermoplastics, such as recycled PVC or recycled PU. It is also conceivable to use a mixture of virgin thermoplastics and recycled thermoplastics to form at least a portion of the core. It is also possible to use thermosetting polymers (e.g., thermosetting polyurethanes) instead of thermoplastics.

[0017] Preferably, the core layer comprises at least one filler, which is at least partially composed of molecules comprising at least one hydroxyl group (OH group) and / or at least one amino group (NH group) and / or at least one fluoro group (FH group). These functional groups must be able to impart dipole properties to the filler, thereby allowing hydrogen bridges to be formed between these functional groups present and exposed on the surface of the core layer and similar functional groups of the connecting layer. The hydroxyl group may constitute part of the carboxyl group. Preferably, the filler comprises lignin and / or cellulose and / or hemicellulose. Preferably, the core layer comprises at least one natural filler, which is at least partially composed of molecules comprising at least one hydroxyl group, wherein at least one such natural filler is preferably selected from the group consisting of the following materials: wood, paper, cork, bamboo, hemp, linen, flax, jute, sisal, coconut fiber, banana fiber, cotton, felt and leather. The filler may be made of fibers, such as glass fibers, synthetic fibers or dermal fibers, and / or may be made of dust-like particles. Here, the term "dust" is understood to mean fine dust-like particles (powder), such as bamboo shavings, wood shavings, cork shavings, or non-wood shavings, such as ore shavings, stone dust, especially cement, and combinations thereof. The average particle size of the dust is preferably between 14 and 20 microns, more preferably between 16 and 18 microns.

[0018] Additionally or alternatively, the side of the core layer facing the backing layer may be provided with at least one coating and / or layer, which is at least partially composed of molecules containing at least one hydroxyl group (OH group) and / or at least one amino group (NH group) and / or at least one fluorine group (FH group). This may also promote the formation of hydrogen bridges between these functional groups present and exposed on the surface of the layer covering the core layer and similar functional groups of the connecting layer.

[0019] In one embodiment, the core layer comprises at least one mineral filler or synthetic filler, and this mineral filler or synthetic filler are at least partially made of the molecule that comprises at least one hydroxyl and / or at least one amino.In this case, for example, the core layer may comprise mesoporous silica particles, porous calcium carbonate particles and / or porous calcium phosphate particles, wherein said particle load has at least one material that comprises at least one amino and / or at least one hydroxyl, for example sodium dihydrogen phosphate dihydrate and / or sodium dihydrogen phosphate heptahydrate.Usually, described one or more described hydrates or other hydrates are deposited on the outer surface of mineral filler or synthetic filler.This deposition can form the mineral filler that is susceptible to hydrogen bond influence or shell or coating of synthetic filler.By using porous mineral or synthetic particle as filler, the surface area of these fillers significantly increases, and this also makes it easier to form (more) hydrogen bond with tie layer.

[0020] Although the tie layer is based on (non-covalent) hydrogen bonds formed between the tie layer and at least one adjacent layer to be bonded to the tie layer, this does not exclude the formation of covalent bonds, ionic bonds, metallic bonds or van der Waals bonds between the tie layer and the adjacent layer(s). It may even be preferred that at least one side of the tie layer forms both hydrogen bonds and covalent bonds with at least one of the core layer and the backing layer. This provides a slightly stronger bond between the layers while still being weak enough to separate the multiple layers in a smooth and effective manner after use. The ratio of the number of non-covalent bonds to the number of covalent bonds at a specific interface between the tie layer and the adjacent layer is preferably between 1:2 and 2:1, more preferably about 1:1. The latter can be achieved, for example, by comprising at least a portion of the tie layer from maleic anhydride, a molecule that is configured to form one non-covalent hydrogen bond and one covalent bond with one or more (e.g., two) hydroxyl groups of the adjacent layer, as shown below.

[0021]

[0022] As mentioned above, maleic anhydride is covalently bonded to the main chain of, for example, the main polymer of the backing layer (schematically depicted as a meandering line) and thus actually forms the side chains of the main polymer. Therefore, the backing layer preferably comprises at least one polymer and wherein at least a portion of the tie layer molecules are grafted onto the polymer of the backing layer. This grafting process can be carried out in advance and is usually carried out by specialized companies. In the above-mentioned bonding mechanism, the weakest link in the laminate of core layer, tie layer and backing layer (onto which the tie layer is grafted) will be the hydrogen-bonded interface between the core layer and the backing layer. Here, the backing layer and the tie layer grafted onto the backing layer can be regarded as a single layer (assembly layer). Preferably, the amount of tie layer molecules grafted onto the backing layer is at least 1.0% of the weight of the backing layer (including the grafted tie layer molecules). Additionally or as an alternative, it is also conceivable to graft the tie layer onto the surface of the core layer. It is even conceivable that the core layer (lower surface) is provided with a preferably grafted core tie layer and the backing layer (upper surface) is provided with a preferably grafted backing tie layer, wherein the core tie layer and the backing tie layer are configured to hydrogen bond to each other.

[0023] As mentioned above, the covalent bond between maleic anhydride and the hydroxyl group is formed by chemical reaction, and in this reaction, the ring of maleic anhydride group opens and bonds with alcohol group, and hydrogen atom is transferred to maleic acid group from one of alcohol group simultaneously.Therefore, maleic anhydride is configured to serve as hydrogen acceptor, and the alcohol group of adjacent layer can serve as hydrogen donor.Therefore, tie layer can not only be configured to be bonded with at least one hydrogen in described core layer and described backing layer, can also be bonded with at least one reactive bond in described core layer and described backing layer, wherein this reactive bond is preferably based on (or accompanying) hydrogen atom transfer, also referred to as transfer hydrogenation.For example, this reactive tie layer preferably includes the material of the group being made up of following substances: polyanhydride (polyanhydride);Maleic anhydride;Polymaleic anhydride;And the copolymer of described polyanhydride or described polymaleic anhydride and olefin, ethyl vinyl acetate and / or ethylene acrylate.

[0024] The chemical reaction between the reactive tie layer and at least one of the core layer and the backing layer (or any other adjacent layer) produces a linear polyester. Although a separate transfer hydrogenation catalyst can be used to promote the chemical reaction, such as a catalyst comprising cobalt, nickel, copper, palladium, platinum, ruthenium, iridium, a Group 6 metal, or a combination thereof, such a separate catalyst may not be required because heating the tie layer to, for example, 70-120 degrees Celsius is generally sufficient to initiate the reaction.

[0025] The thickness of the backing layer, preferably a backing layer modified by a tie layer, is preferably 0.2 to 3 mm. This thickness is generally sufficient to achieve the desired comfort and / or sound insulation and / or balancing properties of the decorative covering element.

[0026] In a preferred embodiment, the backing layer comprises rubber, particularly natural rubber, and the tie layer is bonded to the rubber. Preferably, the backing layer is at least partially composed of at least one partially ultraviolet (UV)-cured natural rubber, comprising rubber chains at least partially crosslinked by at least one organic (preferably sulfur-free) crosslinker, and the natural rubber includes at least one photoinitiator and / or at least one photoinitiator derivative. Rubber, particularly natural rubber, is durable, wear-resistant, shock-absorbing, and less expensive than many alternative synthetic polymers (e.g., EVA). Furthermore, natural rubber has a large stretch ratio, high resilience, and excellent water resistance. Because the rubber is cured (vulcanized) using UV radiation, it is at least partially UV-cured. This curing system does not require, and preferably does not use, sulfur and conventional sulfur-based curing systems. The use of sulfur-containing chemicals in sulfur-based (pre-)vulcanization processes can cause allergic reactions. Because the UV-cured natural rubber used in the floor covering elements of the present invention does not require (and preferably does not use) any sulfur to crosslink the rubber chains, the likelihood of an allergic reaction during use of the floor covering elements (particularly upon contact with the exposed backing layer) is significantly reduced. Furthermore, the natural rubber used in the backing layer is preferably an unfoamed (solid) layer, which inhibits microbial growth and makes the material more resistant to microorganisms than porous and / or foamed materials (e.g., EVA). Another advantage of using natural rubber in the backing layer of the floor covering element according to the invention is that, depending on the state of cure (crosslinking density), the natural rubber can have surface tack, which enables the rubber to fix the floor covering element to the subfloor, thereby contributing to the stability of the floor covering composed of a plurality of such floor covering elements.

[0027] Preferably, the natural rubber comprises rubber chains that are at least partially cross-linked by at least one branched organic (preferably sulfur-free) cross-linking agent. Preferably, each cross-link comprises a backbone chain comprising at least five carbon atoms and optionally oxygen atoms. This creates sufficient space between the rubber chains and also sufficient to accommodate the optional side chains of the cross-links. As described above, preferably, the natural rubber comprises rubber chains that are at least partially cross-linked by at least one (preferably branched) organic sulfur-free cross-linking agent.

[0028] The natural rubber preferably includes at least one photoinitiator selected from the group consisting of α-hydroxyphenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, triarylphosphine oxide, bisacylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-hydroxy-2-methyl-1-phenylpropanone. The latter compound is also known as Irgacure 1173 (or Omnirad 1173) and is available from BASF. It is conceivable that these compounds will remain in the natural rubber after UV curing. During UV curing, at least a portion of these compounds (or any other suitable photoinitiator) will cleave (typically homolytically) upon absorption of UV light, forming free radicals. These free radicals are suitable for reacting with rubber chains and / or crosslinkers, thereby initiating and / or promoting crosslinking. These free radicals typically form part of crosslinks between rubber chains. These free radicals are considered photoinitiator derivatives. Therefore, the crosslinking agent (in the crosslinked state (crosslinking adjacent rubber chains)) preferably includes at least one photoinitiator derivative. For example, using 2-hydroxy-2-methyl-1-phenylpropanone as the initial photoinitiator, the molecule is cleaved under ultraviolet light into benzoyl radicals and isopropanol radicals. These reactive radicals typically and preferably react with the crosslinker to become part of the crosslinker and / or part of the crosslinking bridge based on the crosslinker (in the form of benzoyl and isopropanol groups).

[0029] The crosslinking agent comprises and / or is based on an acrylate. Preferably, the crosslinking agent comprises and / or is based on 1,9-bis(acryloyloxy)nonane. The latter preferably compound is suitable for forming monoradicals and / or diradicals. Natural rubber chains typically comprise polyisoprene, preferably cis-1,4-polyisoprene. Therefore, as an example, the UV crosslinking mechanism (curing system) based on cis-1,4-polyisoprene (natural rubber), 1,9-bis(acryloyloxy)nonane (crosslinking agent) and 2-hydroxy-2-methyl-1-phenylpropanone can be described as follows. In the first step, the absorption of UV light leads to the formation of benzoyl radicals and isopropyl alcohol radicals by homolytic cleavage of 2-hydroxy-2-methyl-1-phenylpropanone.

[0030]

[0031] These free radicals (P·) initiate (pre)vulcanization by attacking the C=C bonds of the polyisoprene (rubber chain) and the closest molecules of the crosslinker. The reaction between the photoinitiator radicals and the polyisoprene chains produces polymer radicals, while the reaction between the photoinitiator radicals and 1,9-bis(acryloyloxy)nonane produces products with one or two free radical centers. These products are called monoradicals and diradicals, respectively.

[0032]

[0033] These cross-linking radicals can also react with polyisoprene to form cross-links between polyisoprene chains.

[0034]

[0035] Preferably, the dry rubber content (solid rubber content) of the natural rubber of the backing layer is at least 40%, more preferably at least 50%, most preferably at least 60% by weight of the natural rubber. Such a dry rubber content confers on the backing layer properties suitable for use as a backing layer for floor covering elements.

[0036] Preferably, at least a portion of natural rubber is obtained from Brazilian rubber tree (Hevea brasiliensis tree) and / or Indian banyan tree (Ficus elastica tree). This is still the main source of natural rubber today, but the increase in global demand means that there is an urgent need for alternative sustainable sources. Russian dandelion (rubber grass (Taraxacumkoksaghyz Rodin)) is such a substitute, because its root system produces a large amount of natural rubber. Therefore, preferably, even more preferably, at least a portion of the natural rubber used in the backing layer is from dandelion. Here, at least a portion of natural rubber is preferably obtained from the species of Taraxacum, preferably from following species, select at least one: Western dandelion (Taraxacum officianale) and rubber grass (Taraxacum kok-saghyz). Different from Hevea (Hevea) rubber tree, rubber grass (Taraxacum kok-saghyz) can be grown in temperate regions around the world, including North America and Russia.

[0037] Preferably, the tie layer comprises at least one substance selected from the group consisting of polyacrylates or polymethacrylates, wherein the ester moiety has 1 to about 12 carbon atoms; blends of said polyacrylates or polymethacrylates with polyolefins; ethylene-methyl acrylate copolymers; polyanhydrides; maleic anhydride; polymaleic anhydride; and copolymers of said polyanhydrides or polymaleic anhydride with olefins, ethylvinyl acetate and / or ethylene-acrylate. These compounds are generally well suited for coating and form (sufficient) hydrogen bonds with adjacent layers.

[0038] Preferably, the adhesive peel strength between the backing layer and the core layer is at least 1.0 kN / m, preferably at least 1.5 kN / m. Preferably, the peel strength is less than 5 kN / m, so that the backing layer can be smoothly layered. The peel strength is measured according to the 90 ° peel test of D6862 (ASTM 2007b). The peel strength can be divided by the peel width of the sample by the average recorded load, wherein the average recorded load is determined by taking the average load over the entire peel length.

[0039] Preferably, the Vicat softening temperature of the tie layer and / or the backing layer (measured according to the A50 method defined in ISO 306) is between 80 and 150 degrees Celsius. This temperature range is also the preferred range for lamination during the manufacture of the decorative covering element to form hydrogen bonds and optionally covalent bonds, as well as for layer separation after use. Using a tie layer and / or backing layer with a softening point well below 80 degrees Celsius (e.g., 70 degrees Celsius) is generally disadvantageous because the decorative covering element may be heated by the sun to temperatures as high as 70 degrees Celsius, which could affect the interlayer adhesion of the floor covering element during normal use.

[0040] In a preferred embodiment, at least one intermediate layer is located between the tie layer and the core layer and / or between the tie layer and the backing layer, wherein the intermediate layer preferably comprises a polymer, more preferably a thermoplastic polymer, and / or wherein the intermediate layer is preferably a water-impermeable layer. Such a layer can increase the water-impermeability of the decorative covering element itself. Optionally, the polymer of the intermediate layer, in particular the thermoplastic polymer, can be grafted on at least one side of the intermediate layer by at least one tie layer to impart to the polymer the ability to form hydrogen bonds with at least one adjacent layer (e.g., the core layer and / or the backing layer and / or another tie layer, if desired). If at least one intermediate layer is located between the tie layer and the core layer, the tie layer preferably forms hydrogen bonds with the intermediate layer rather than with the core layer itself. In embodiments described or otherwise disclosed in the present disclosure that mention or relate to bonding a tie layer to a core layer, the expression "core layer" may be replaced by "intermediate layer" if the intermediate layer is applied and positioned between the tie layer and the core layer. If at least one intermediate layer is positioned between the tie layer and the backing layer, the tie layer preferably forms hydrogen bonds with the intermediate layer rather than with the backing layer itself. For embodiments described or otherwise disclosed in this disclosure that involve combining a tie layer with a backing layer, the expression "backing layer" may be replaced with "intermediate layer" if an intermediate layer is applied and positioned between the tie layer and the backing layer.

[0041] The decorative top structure is preferably at least partially transparent or translucent. The decorative top structure can consist of a single layer, such as a printed decorative layer or a wear layer, but is typically composed of multiple layers. Preferably, the decorative top structure includes at least one printed (more preferably digitally printed) decorative layer and at least one transparent wear layer and / or a transparent top coating covering the decorative layer. The top coating is also referred to as a lacquer layer. The wear layer is preferably made of polyvinyl chloride, polyurethane and / or an acrylic resin. The decorative top structure may also include at least one backing layer (primer layer) located between the decorative layer and the core layer, wherein the backing layer is preferably made of a vinyl or polyurethane compound. A finishing layer may be applied between the decorative layer and the wear layer. The decorative layer will be visible and will serve to give the panel an aesthetically pleasing appearance. To this end, the decorative layer may have a design pattern, which can be, for example, a wood grain pattern, a mineral pattern similar to the texture of marble, granite or other natural stone, or a color pattern, a color mixture or a single color, to name just a few design possibilities. Alternatively, the decorative roof structure may also consist of a fabric and / or carpet-based roof structure and / or other decorative roof structures, such as ceramic tiles or layers, stone tiles or layers, glass tiles or layers, wood tiles or layers, marble tiles or layers. These tiles or layers may be adhered to the core layer, for example, by at least one intermediate layer, which may be a conventional adhesive layer and / or another adhesive layer.

[0042] Preferably, the floor covering elements comprise complementary coupling profiles at a first pair of opposing edges, the coupling profiles being configured to interlock adjacent floor covering elements; and preferably, the floor covering elements comprise further complementary coupling profiles at a second pair of opposing edges, the coupling profiles being configured to interlock adjacent floor covering elements. More preferably, the floor covering elements are floor panels, the first panel edge of which comprises a first coupling profile and the second panel edge of which comprises a complementary second coupling profile, the coupling profiles being designed to directly or indirectly interlock adjacent panels. In the case of direct interlocking, the coupling profile of one panel will directly interact with the complementary coupling profile of an adjacent panel. In the case of indirect interlocking, a separate coupling structure (connecting element) is typically used to interconnect the multiple panels, wherein the coupling profile of each panel is connected to this coupling structure. In the coupled state, the floor panels can be adjacent to each other or, alternatively, can be spaced apart from each other. The floor panels may further comprise a third panel edge comprising a third coupling profile and a fourth panel edge comprising a complementary fourth coupling profile designed for directly or indirectly interlocking adjacent panels. In a preferred embodiment, the first and / or third coupling profile comprises an upward tongue, at least one upward flank spaced apart from the upward tongue, an upward groove formed between the upward tongue and the upward flank, wherein the upward groove is adapted to receive at least a portion of a downward tongue of a second coupling profile of an adjacent panel, and at least one first locking element, preferably arranged on a side of the upward tongue remote from the upward flank; and wherein the second and / or fourth coupling profile comprises a first downward tongue, at least one first downward flank spaced apart from the downward tongue, a first downward groove formed between the downward tongue and the downward flank, wherein the downward groove is adapted to receive at least a portion of the upward tongue of the first coupling profile of an adjacent panel, and at least one second locking element adapted to cooperate with the first locking element of the adjacent panel, the second locking element preferably being arranged at the downward flank. Preferably, the first locking element comprises a protrusion and / or a recess, and wherein the second locking element also comprises a protrusion and / or a recess. The projection is typically adapted to be at least partially accommodated in a recess of an adjacent coupled panel to achieve a locked coupling, preferably a vertically locked coupling. It is also conceivable that the first locking element and the second locking element are not formed by a projection-recess combination, but by a combination of other co-acting profiled surfaces and / or high-friction contact surfaces. In the latter embodiment, at least one of the first locking element and the second locking element can be formed by a (planar or other shaped) contact surface, which is composed of an optionally independent plastic material, which is configured to generate friction with the other locking element of the other panel in the engaged (coupled) state.

[0043] At least a portion of the tie layer may be extruded. It is also conceivable that the entire tie layer is an extruded layer. It is also conceivable that at least one of the core layer and the backing layer is extruded. In the case of multiple layers of the decorative cover element being extruded, these layers are preferably (simultaneously) coextruded and preferably bonded directly downstream of the (co)extrusion equipment.

[0044] It is conceivable that the decorative covering element comprises a plurality of tie layers. Preferably, each tie layer is located between different layers of the decorative covering element. For example, a first tie layer may be located between a core layer and a decorative layer applied above the core layer, while a second tie layer may be located between the core layer and a backing layer applied to the underside of the core layer. The different tie layers may have different compositions, which may depend, for example, on the layers to be joined. It is also conceivable that the different tie layers have the same composition. Therefore, it is preferred that the decorative floor covering element comprises at least one decorative surface layer fixed directly or indirectly on top of the core layer, wherein the at least one decorative surface layer is fixed to the upper side of the core layer via an intermediate tie layer, wherein the tie layer is compatible with the core layer and the decorative surface layer, and wherein the tie layer is bonded to at least one of the core layer and the decorative surface layer by hydrogen bonds and optionally by covalent bonds.

[0045] The decorative surface layer may form part of a decorative top structure. This top structure may include a protective or wear layer located above the decorative layer to protect the decorative layer and, if applicable, the core layer. The decorative layer may consist solely of an ink layer representing the decorative object. The decorative layer may also include an ink-carrying layer, such as a paper or polymer film, which carries the ink layer representing the decorative object. Alternatively, it is conceivable that the decorative layer is a colored layer, such as a polymer layer enriched with one or more colorants. The color of the decorative layer may be a solid color or may consist of a plurality of colors. Typically, the decoration defines a motif, image, and / or pattern, preferably consisting of a plurality of colors. The decoration is preferably printed (more preferably digitally printed) using (colored) ink onto another floor covering element layer, such as an ink-carrying layer, in particular a film, typically consisting of paper and / or a thermoplastic material. The decoration contributes to the visual appearance ("pattern") of the decorative floor covering element. To protect the decorative layer, one or more protective layers are applied on top of the decorative layer, which protective layers may have a textured upper surface or a relief structure. The textured upper surface or relief structure (also known as embossed structure) preferably matches the visual effect of the decorative object at least partially (preferably completely). This alignment is also known as register alignment. This is particularly attractive, for example, for imitation wood grain patterns, where the relief structure can include a plurality of indentations, or cavities, and / or grooves created by printing the relief structure, which are aligned with the wood grain and wood pores of the printed wood grain pattern. The position and depth of the indentations, cavities, and / or grooves depend on the wood grain and wood pores of the printed pattern. The relief structure imparts an enhanced, more realistic look and feel to the finished decorative floor covering element.

[0046] At least one protective layer can be a cured layer, such as a UV cured lacquer layer, preferably located on top. At least one other protective layer, preferably located below the cured layer (if applicable), is configured as a wear-resistant layer and can be enriched with wear-resistant particles, such as aluminum oxide.

[0047] The decorative roof structure preferably comprises at least one primer layer, at least one decorative layer located on top of the primer layer, and at least one protective layer applied on top of the decorative layer. The primer layer preferably has a white or whitish color, which facilitates the color appearance (color authenticity) of the printed decorative element applied (preferably directly) on top of the primer layer. The primer layer may, for example, comprise melamine cyanurate.

[0048] The thickness of the decorative layer is preferably between 0.03 and 0.2 mm. The thickness of the decorative top structure is preferably between 0.2 and 1.2 mm, more preferably between 0.3 and 0.8 mm. The backing layer may be a polymer (particularly thermoplastic) base layer and / or a cork layer. Preferably, the backing layer, at least one core layer (preferably each core layer), and the decorative layer are coextruded layers. The thickness of the backing layer is preferably between 1 and 2.5 mm, more preferably between 1.5 and 2.0 mm. The thickness of the floor covering element may vary, but is preferably between 3.5 and 15 mm.

[0049] The invention further relates to a decorative covering comprising a plurality of decorative covering elements according to the invention, preferably coupled to one another.

[0050] The present invention also relates to a method for the post-use treatment of recycled decorative covering elements, in particular floor covering elements according to the invention, comprising the following steps:

[0051] A) heat treatment of decorative covering elements, in particular floor covering elements,

[0052] B) pulling the core layer and the backing layer apart to destroy the bonding of the core layer and the backing layer based on the tie layer, resulting in separation of the core layer from the backing layer.

[0053] Preferably, in step A), the floor covering element is placed in an atmosphere having a temperature between 80 and 150 degrees Celsius. Preferably, in step A), the floor covering element is heated to a temperature of at least 80 degrees Celsius.

[0054] Steps A) and B) are preferably carried out simultaneously. This means that the pulling apart in step B) is carried out at the elevated temperature of step A).

[0055] Preferably, the method comprises a step C) of recycling the core layer into a new product, preferably a new floor covering element. In the new floor covering element, the recycled core layer is typically comminuted or ground and, where appropriate, re-extruded to form a new core layer. Typically, before the new core layer is produced, the virgin core layer material is mixed with the recycled core layer material. Depending on the formulation of the backing layer, the same principle can be applied to the recycled backing layer, which can also be recycled into a new product, such as a new floor covering element, in particular an at least partially recycled backing layer of a new floor covering element.

[0056] Preferably, the method comprises a step D) comprising separating at least a majority of the decorative top structure from the core layer, wherein step D) is preferably carried out before step C). This step can also be carried out at high temperature and / or by milling (i.e. mechanically removing) the decorative top structure relative to the core layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The present invention will be further illustrated by means of several non-limiting examples, in which:

[0058] - Figure 1 schematically shows a cross-sectional view of a decorative covering element according to the invention,

[0059] - Figure 2 Schematically shows Figure 1 An enlarged cross-sectional view of the square portion A,

[0060] - Figure 3 schematically shows an enlarged view of the core layer, the connecting layer and the backing layer of the decorative covering element according to the invention, and

[0061] - Figure 4 The post-use treatment method of a recycled decorative covering element according to the invention is schematically shown. DETAILED DESCRIPTION

[0062] Figure 1 A cross-sectional view of a decorative covering element 1 according to the present invention is schematically shown. Decorative covering element 1 can be a decorative floor covering element, a decorative wall covering element, or a decorative ceiling covering element. Decorative covering element 1 comprises a core layer 2. A decorative top structure 4 is secured directly or indirectly to the upper side 3 of core layer 2. A backing layer 6 is secured to the lower side 5 of core layer 2 via an intermediate connecting layer 9. Connecting layer 9 forms a bond between core layer 2 and backing layer 6. Connecting layer 9 is at least partially bonded to core layer 2 and / or backing layer 6 via hydrogen bonds. The illustrated decorative covering element 1 further comprises a pair of complementary coupling profiles 8, 9 with opposing edges for interlocking adjacent decorative covering elements. A first coupling profile 8 comprises a downward tongue 81, downward flanks 82 spaced apart from downward tongue 81, and a downward groove 83 formed between downward tongue 81 and downward flanks 82, wherein downward groove 83 is adapted to receive at least a portion of an upward tongue 71 of a second coupling profile 9 of another decorative covering element. Optionally, a second locking element 85 is provided at the downward flank 82, which is adapted to cooperate with the first locking element 75 of the further decorative covering element 1. The second coupling profile 7 comprises an upward tongue 71, an upward flank 72 at a distance from the upward tongue, and an upward groove 73 formed between the upward tongue 71 and the upward flank 72, wherein the upward groove is adapted to receive at least a portion of the downward tongue 81 of the first coupling part 8 of the further decorative covering element 1. The first locking element 75 is provided on the outer side of the upward tongue 71 facing away from the upward flank 72.

[0063] Figure 2 Schematically shows Figure 1 An enlarged cross-section of a square portion A of a decorative covering element is shown. Figure 2 A core layer 2 is shown, which is bonded to a backing layer 6 via an intermediate tie layer 9. The underside 5 of the core layer 2 is at least partially functionalized with functional groups 25, in particular hydroxyl and / or amino groups. These functional groups 25 are configured to chemically bond with tie layer molecules 29, thereby forming a tie layer-based bond between the core layer 2 and the backing layer 6. It is conceivable that the backing layer 6 can also be functionalized with the tie layer molecules 29, for example by grafting. It is conceivable that at least a portion of the functional groups 25 is configured to form dipole-dipole interactions with the tie layer molecules 29. Preferably, at least a portion of the functional groups 25 of the core layer 2 is configured to form hydrogen bonds with at least one tie layer molecule 29. A portion of the functional groups 25 of the core layer 2 can form covalent bonds with the tie layer molecules 29. It is conceivable that at least a portion of the tie layer molecules 29 is configured to form dipole-dipole interactions with the backing layer 6. Preferably, at least a portion of the tie layer molecules 29 is configured to form hydrogen bonds with the backing layer 6. At least a portion of the tie layer molecules 29 can be configured to form covalent bonds with the backing layer 6. It is conceivable that the backing layer 6 and / or the core layer 2 are bound by the tie layer 9 through a combination of covalent bonds and hydrogen bonds. The functional groups 25 can be loaded and / or deposited on the underside 5 of the core layer 2. However, the core layer 2 can also include a material that is at least partially formed by molecules containing functional groups 25. For example, the core layer 2 can include a filler containing at least one hydroxyl group and / or at least one amino group. It is also conceivable that the core layer 2 includes particles functionalized with at least one functional group 25 (e.g., hydroxyl and / or amino groups).

[0064] Figure 3A schematic diagram shows an enlarged view of a core layer 32, a tie layer 9, and a backing layer 36 of a decorative covering element according to the present invention. The views shown show two possible chemical structures of the core layer 32, the tie layer 9, and the backing layer 36. Two diagonal lines in the figure separate these two different examples. The upper view shows that the core layer 32 is not in contact with the tie layer 9 and is therefore not bonded to the backing layer 36. The lower view shows that the core layer 32 is bonded to the backing layer 36 via the intermediate tie layer 9. The core layer 32 comprises functional groups 35a, 35b. In this embodiment, the core layer 2 is functionalized with either two hydroxyl groups 35a or one amino group 35b. However, the core layer 32 can also be functionalized with calcium carbonate. The core layer 32 is functionalized with at least one functional group 35a and 35b. The core layer 32 can also be functionalized with a combination of two different functional groups 35a, 35b. The backing layer 36 comprises a polymer onto which the tie layer 9 is grafted. Tie layer 9 includes tie layer molecules 39a and 39b. It is conceivable that at least a portion of tie layer molecules 39a and 39b are grafted onto the polymer of backing layer 36. In this embodiment, backing layer 36 is covalently bonded to tie layer molecules 39a and 39b. The polymer of backing layer 36 in this figure is covalently bonded to polymaleic anhydride 39a and polyacrylate 39b for illustrative purposes only. Tie layer 9 can, for example, be composed of other substances, such as polyacrylate, polymethacrylate, or polyanhydride. As can be seen from the bottom of this figure, hydrogen bonds are formed between the functional groups and the tie layer molecules. More specifically, hydrogen bonds are formed between hydroxyl groups 35a and polymaleic anhydride 39a, and between amino groups 35b and polyacrylate 39b. Those skilled in the art will appreciate that hydroxyl groups 35a can also form hydrogen bonds with polyacrylate 39b. It is also possible that amino groups 35b and polymaleic anhydride 39a can also form hydrogen bonds. In addition, a covalent bond is formed between the hydroxyl group 35a and the polymaleic anhydride 39a.

[0065] Figure 4A method 40 for the post-use treatment of a recycled decorative covering element 41 according to the invention is schematically shown. The decorative covering element 41 comprises a core layer 42. A decorative top structure 44 is fixed directly or indirectly to the upper side 43 of the core layer 42. A backing layer 46 is fixed to the lower side 45 of the core layer 42 via an intermediate connecting layer 49. The lower side 45 of the core layer 42 is at least partially functionalized with functional groups 47, in particular hydroxyl and / or amino groups. The functional groups 47 are bonded to connecting layer molecules 48. The connecting layer 49 is bonded to the core layer 42 and the backing layer 46. The connecting layer 49 is bonded to the core layer 42 and / or the backing layer 46 at least partially via hydrogen bonds. The decorative covering element 41 after use is first subjected to a heat treatment A). The heat treatment of the decorative covering element 41 results in at least partial destruction of the connecting layer-based bond between the core layer 42 and the backing layer 46. Specifically, the decorative covering element 41 is heat-treated to cause the relatively weak hydrogen bonds between the functional groups 47 of the core layer 42 and the connecting layer molecules 48 and / or between the backing layer 46 and the connecting layer molecules 48 to break. Preferably, the heat treatment is carried out at a temperature of 80 to 150 degrees Celsius. Subsequently, the core layer 42 and the backing layer 46 are pulled apart B) to separate the core layer 42 from the backing layer 46. For example, the core layer 42 and the backing layer 46 can be pulled apart by applying a mechanical force F. The mechanical force F can be equivalent to the core layer 42 and the backing layer 46 pointing in substantially opposite vertical directions. By pulling the core layer 42 and the backing layer 46 apart, the remaining (non-hydrogen) bonding based on the connecting layer is destroyed. It is conceivable that the decorative covering element 41 is heated A) and pulled apart B) at the same time. The destruction of the bonding based on the connecting layer of the core layer 42 and the backing layer 46 causes the core layer 42 and the backing layer 46 to separate. The separated core layer 42 can then be recycled to make a new decorative cover element 41. It is conceivable that the backing layer 46, in particular the backing layer material, can also be recycled. In addition, the decorative top structure 44 can be separated from the core layer 42, preferably before recycling the core layer 42.

[0066] Thus, the above-described inventive concepts have been illustrated by means of several exemplary embodiments. It is contemplated that individual inventive concepts may be applied without also applying the other details of the examples described. While it is not necessary to provide a detailed description of all possible combinations of the above-described inventive concepts, those skilled in the art will appreciate that numerous inventive concepts may be (re)combined to achieve a particular application. The various embodiments of the panel described above and in the appended claims may be combined with this alternative panel configuration.

[0067] Ordinal numbers such as "first" and "second" are used in this document for identification purposes only.

[0068] Obviously, the invention is not limited to the working examples shown and described herein, but several variations are possible within the scope of the appended claims, which will be obvious to a person skilled in the art.

[0069] The verb "to comprise" and its conjugations used in this patent disclosure should be understood not only as "to include", but also as the phrases "to include", "to consist essentially of", "to be formed of" and their conjugations.

Claims

1. Decorative floor covering elements, including: at least one core layer, a decorative top structure fixed directly or indirectly to the upper side of the core layer, a backing layer fixed to the underside of the core layer via an intermediate connecting layer, The connecting layer is compatible with the core layer and the backing layer, and the connecting layer is bonded to at least one of the core layer and the backing layer through hydrogen bonding.

2. The decorative floor covering element according to claim 1, wherein The core layer comprises a polymer, in particular selected from the group consisting of: PVC, PET, PETG, PP, PS, thermoplastic polyurethane (TPU), PE, in particular MDPE and / or HDPE, at least one furan resin; and combinations of polymers from said group; wherein at least a portion of said polymer is preferably a recycled polymer.

3. Decorative floor covering element according to claim 1 or 2, wherein The core layer comprises at least one filler formed at least partially from molecules comprising at least one hydroxyl group and / or at least one amino group.

4. The decorative floor covering element according to claim 3, wherein The core layer comprises at least one natural filler, which is at least partially formed by molecules comprising at least one hydroxyl group, wherein at least one such natural filler is preferably selected from the group consisting of wood, cork, bamboo, hemp, linen, flax, jute, sisal, coconut fiber, banana fiber, cotton, felt and leather.

5. Decorative floor covering element according to claim 3 or 4, wherein The core layer comprises at least one mineral or synthetic filler formed at least partially from molecules comprising at least one hydroxyl group and / or at least one amino group.

6. The decorative floor covering element according to claim 5, wherein The core layer comprises mesoporous silica particles, porous calcium carbonate particles and / or porous calcium phosphate particles, wherein the particles are loaded with at least one substance comprising at least one amino group and / or at least one hydroxyl group, such as sodium dihydrogen phosphate dihydrate and / or sodium dihydrogen phosphate heptahydrate.

7. Decorative floor covering element according to any one of the preceding claims, wherein At least one side of the tie layer is bonded to at least one of the core layer and the backing layer through hydrogen bonds and covalent bonds.

8. The decorative floor covering element according to claim 7, wherein The covalent bond between the tie layer and at least one of the core layer and the backing layer is formed by a chemical reaction between the tie layer and at least one of the core layer and the backing layer.

9. The decorative floor covering element according to claim 8, wherein The chemical reaction is based in part on the transfer of at least one hydrogen atom from at least one of the core layer and the backing layer, which is a hydrogen donor, to the connecting layer, which is a hydrogen acceptor.

10. The decorative floor covering element according to any one of the preceding claims, wherein The tie layer includes at least one substance selected from the group consisting of: polyanhydride; polymaleic anhydride; and copolymers of the polyanhydride or the polymaleic anhydride with olefins, ethyl vinyl acetate and / or ethylene acrylate.

11. Decorative floor covering element according to any one of the preceding claims, wherein The tie layer comprises at least one substance selected from the group consisting of: polyacrylate or polymethacrylate, wherein the ester portion of the polyacrylate or polymethacrylate has 1 to about 12 carbon atoms; a blend of the polyacrylate or polymethacrylate with a polyolefin; and ethylene methyl acrylate copolymer.

12. The decorative floor covering element according to any one of the preceding claims, wherein The backing layer comprises at least one polymer, and wherein at least a portion of the tie layer molecules are grafted to the polymer of the backing layer.

13. The decorative floor covering element according to claim 12, wherein The amount of tie layer molecules grafted onto the backing layer is at least 1.0% by weight of the backing layer, the weight of the backing layer including the grafted tie layer molecules.

14. Decorative floor covering element according to claim 12 or 13, wherein The backing layer and the tie layer grafted onto the backing layer form a single layer.

15. Decorative floor covering element according to any one of the preceding claims, wherein The thickness of the backing layer, preferably the thickness of the backing layer modified by the tie layer, is 0.2-3 mm.

16. Decorative floor covering element according to any one of the preceding claims, wherein The backing layer comprises rubber, in particular natural rubber, and wherein the tie layer is bonded to the rubber.

17. The decorative floor covering element according to claim 16, wherein The backing layer consists at least partially of at least one partially UV-cured natural rubber, comprising rubber chains at least partially crosslinked by at least one organic crosslinker, preferably a sulfur-free crosslinker, and comprising at least one photoinitiator and / or at least one photoinitiator derivative.

18. Floor covering element according to claim 17, wherein The natural rubber comprises rubber chains at least partially crosslinked by at least one branched organic crosslinking agent, preferably a sulfur-free crosslinking agent.

19. Floor covering element according to any one of claims 17-18, wherein The natural rubber comprises at least one photoinitiator and / or at least one derivative of at least one photoinitiator, wherein the photoinitiator is selected from the group consisting of α-hydroxyphenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, triarylphosphine oxide, bisacylphosphine oxide, 2-hydroxy-2-methyl-1-phenylpropanone.

20. The decorative floor covering element according to any one of the preceding claims, wherein The peel strength of the bond between the backing layer and the core layer, measured according to the 90° peel test following D6862 (ASTM 2007b), is at least 1.0 kN / m, preferably at least 1.5 kN / m.

21. The decorative floor covering element according to any one of the preceding claims, wherein The tie layer and / or the backing layer has a Vicat softening temperature measured according to method A50 defined in ISO 306 of between 80 and 150 degrees Celsius.

22. The decorative floor covering element according to any one of the preceding claims, wherein At least one intermediate layer is located between the connecting layer and the core layer, wherein the intermediate layer preferably comprises a polymer, more preferably a thermoplastic polymer, and / or wherein the intermediate layer is preferably a water-impermeable layer, and wherein the connecting layer is preferably bonded to the intermediate layer by hydrogen bonds.

23. The decorative floor covering element according to any one of the preceding claims, wherein The decorative floor covering element comprises at least one decorative surface layer fixed directly or indirectly on top of the core layer.

24. The decorative floor covering element according to any one of the preceding claims, wherein The at least one decorative surface layer is fixed to the upper side of the core layer by an intermediate tie layer, wherein the tie layer is compatible with the core layer and the decorative surface layer, and wherein the tie layer is hydrogen bonded to at least one of the core layer and the decorative surface layer, and optionally covalently bonded.

25. The decorative floor covering element according to any one of the preceding claims, wherein The connecting layer is an extruded layer.

26. The decorative floor covering element according to any one of the preceding claims, wherein The tie layer and at least the core layer and the backing layer are coextruded layers.

27. Process for the post-use disposal of recycled floor covering elements according to any one of the preceding claims, comprising the following steps: A) heat treatment of floor covering elements, B) pulling the core layer and the backing layer apart to destroy the bonding of the core layer and the backing layer based on the tie layer, resulting in separation of the core layer from the backing layer.

28. The method according to claim 27, wherein During step A), the floor covering element is subjected to an ambient atmosphere having a temperature between 80 and 150 degrees Celsius.

29. The method according to claim 27 or 28, wherein Steps A) and B) are performed simultaneously.

30. The method according to any one of claims 27 to 29, wherein: The method comprises a step C) comprising the step of recycling the core layer into new floor covering elements.

31. The method according to any one of claims 27 to 30, wherein: The method comprises a step D) comprising the step of separating at least a major portion of the decorative top structure from the core layer, wherein step D) is preferably performed before step C).

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