The invention relates to a decorative panel, in particular a floor panel, ceiling panel or wall panel. The invention also relates to a decorative panel covering, such as a decorative floor covering, decorative ceiling covering or decorative wall covering, comprising a plurality of panels according to the invention, wherein the panels are preferably interconnected. The invention further relates to an intermediate layer for use in a decorative panel according to the invention.

Laminated panels comprise a core layer onto which a decorative top structure is applied having a printed decorative image which typically has the appearance of a wood pattern. The decorative image is covered by a transparent layer to preserve and protect said the image. In order to improve the optical and haptic appearance of the decorative image of the decorative top structure, impressions can be realized in the transparent layer, this in order to obtain an e.g., imitation of wood pores and other unevennesses which can be present at the surface of real wood. Often PVC is used as main constituent for composing the core. Often, the decorative image is digitally printed onto a PVC film, wherein said printed PVC film is affixed to said core. Although the digital printing techniques are constantly improving, leading to more realistic natural appearances, there is also a trend of leading flooring manufacturers to develop more environmental-friendly decorative panels which are more composed of natural materials rather than of synthetic, in particular thermoplastic, materials, such as PVC. To this end, flooring panels have been developed which use a cork layer, rather than a PVC film, to bear a printed decor image. Although this solution constitutes an improvement from an environmental point of view, it has been found that cork is rather expensive and it is practically impossibly to reach to same panel quality compared to panels wherein PVC are used to bear the decorative image, in terms of image quality and panel stability.

It is therefore a first objective of the invention to provide a relatively environmental- friendly, high-quality decorative panel.

It is therefore a second objective of the invention to provide a relatively environmental-friendly decorative panel comprising a high-quality decor image. It is therefore a third objective of the invention to provide an environmental-friendly, inexpensive decorative panel.

At least one of these objective can be met by providing a decorative panel according to the preamble, comprising: a core provided with an upper side and a lower side, a decorative top structure affixed, directly or indirectly, on said upper side of the core, said decorative top structure comprising: at least one decorative layer, preferably a printed decorative layer, more preferably a digitally, printed decorative layer, forming and/or bearing at least one decor image, and, preferably, at least one transparent and/or translucent protective layer covering said decorative layer; and at least one intermediate layer comprises non-human collagen and/or leather, wherein said at least one intermediate layer is positioned underneath said decorative top structure.

Preferably, the decorative panel is an interlockable panel configured to interlock with adjacent panels. To this end, the decorative panel comprises a first panel edge comprises a first coupling profile, and a second panel edge, preferably opposite to the first panel edge, comprising a second coupling profile being designed to engage interlockingly with said first coupling profile of an adjacent panel, both in horizontal direction and in vertical direction. Alternatively, it is also conceivable that the decorative panel according to the invention is a so-called dry-back panel which is configured to be glued onto a subfloor.

The intermediate layer is a collagen based layer. Skin, or animal hide, is formed primarily of collagen, a fibrous protein, and serves as source for composed at least a part of said intermediate layer. Collagen is a generic term for a family of at least 28 distinct collagen types; animal skin is typically type I collagen, although other types of collagen may be used in forming leather. Collagens are characterized by repeating triplets of amino acids, -(Gly-X-Y) n -, so that approximately one-third of the amino acid residues are in collagen are glycine. X is typically proline and Y is typically hydroxyproline. The structure of collagen may consist of twined triple units of peptide chains of differing lengths. Different animals may produce different amino acid compositions of the collagen, which may result in different properties (and differences in the resulting leather). Collagen fiber monomers may be produced from alpha-chains of about 1050 amino acids long, so that the triple helix takes the form of a rod of about 300 nm long, with a diameter of 1.5 nm. Triple helices can be bound together in bundles called fibrils, and fibril bundles come together to create fibers. Fibers typically divide and join with each other throughout an animal skin layer. Variations of the crosslinking or linking may provide strength to the material. Fibers may have a range of diameters depending on the type of animal hide. In addition to type I collagen, skin (hides) may include other types of collagen as well, including type III collagen (reticulin), type IV collagen, and type VII collagen. Leather derived from animal mainly consists of collagen type I when hides are obtained from adult animals, and significant proportion of collagen types III and IV, together with collagen type I when skins are derived from young animals. The composition and ratio of collagen types affect the physical properties of leather, a younger hide with proper tanning provides the softest leather.

The use of non-human collagen, and (bonded) leather in particular, is not only technically driven, but also environmentally and morally driven. The global leather industry slaughters more than a billion animals per year. The leather skin resulting from this slaughtering process is often and largely treated as waste, which is typically burned afterwards. By reusing this leather at least partially the amount of waste is reduced and a more circular production cycle can be realised. Moreover, these leather residues, typically offered as bonded leather, is relatively inexpensive, and therefore more attractive than other natural materials, such as cork, which may be used for this purpose.

Moreover, the application of a collagen and/or leather based intermediate layer for supporting the decorative top structure is favourable since, this intermediate layer is well-suitable for adhesion of a primer layer and/or a digital print layer of the decorative top structure. Moreover, due to the flexible (elastic) nature of the intermediate layer, the intermediate layer is typically configured to compensate differences in the temperature and/or moisture expansion coefficient of the core and at least a part of the decorative top structure. This prevents delamination of the panel, which is in favour of the lifetime of the panel. An additional advantage of the intermediate layer is it capability to be sawn, milled, and edged, which is favourable when profiling the panel to realising coupling profiles. Furthermore, the intermediate layer provide the panel additional strengthening. Additionally, the presence of one or more intermediate layer provides the panel improved acoustic dampening properties. Since at least the edges of at least one intermediate layer are typically exposing to the surrounding atmosphere, it is additionally favourable that the intermediate layer(s) has/have a relatively good resistance against cleaning agents.

Due to the above properties it can be advantageous that (i) at least one intermediate layer is situated in between the core and the decorative top structure, and preferably affixed, either directly or indirectly, to the upper side of the core, and/or that (ii) at least one intermediate layer is embedded in the core, and/or that (iii) at least one intermediate layer is affixed, either directly or indirectly, to the lower side of the core.

The collagen present in the intermediate layer is preferably derived from cows, water buffaloes, horses, deers, crocodiles, or goats, as the tear strength of this leather types are relatively high, in particular higher than 60 N/mm. Hence, the intermediate layer(s) preferably comprise(s) bovine leather, which is typically preferred over ovine leather, also because there is a correlation between leather strength and fibril diameter in bovine leather. In bovine leather, the collagen fibrils are more aligned than in ovine skin, and it was found that where tissue contains highly aligned fibrils, the fibril diameter becomes a significant determinant of strength. In tissues where the fibrils are not well aligned, the influence of fibril alignment on strength is greater than that of fibril diameter. Therefore, in leather and skin, larger fibrils may lead to stronger material, but for weaker leathers, fibril diameter is secondary to fibril alignment for strength. Preferably, the fibril length is at least 66 nm, which is typical for cows and horses.

Preferably, the amount of (genuine) leather is preferably situated between 40 and 80% and more preferably approximately 60% by weight of the intermediate layer. Although it is imaginable that the intermediate layer is entirely (100%) composed of leather, this will commonly be considered as a rather expensive solution compared to a composite material which comprises further to leather also one or more other materials.

Preferably, at least one intermediate layer is at least partially or entirely composed of bonded leather, also referred to as reconstituted leather or blended leather.

Bonded leather is at least partially composed of (genuine) leather particles bonded by means of a binding material, wherein the amount of binding material is preferably situated between 10 and 40% and more preferably approximately 20% by weight of the intermediate layer. Examples of suitable binding material are natural rubber, such as latex, and polyurethane. Preferably, bonded leather comprises a layered structure of a carrier layer onto which leather particles are bonded by means of said binding material. The carrier layer may, for example, be composed of a paper, fabric, cork, wood, and/or a, preferably natural polymer, such as natural rubber (latex). The carrier layer may be either a woven or non-woven layer. Preferably, the binding material is partially penetrated into the carrier layer. It is conceivable that the binding material is partially penetrated into the core and/or at least one other adjacent layer. Since the collagen of the intermediate layer typically has a porous structure, it typically allows penetration of other materials. It is therefore imaginable that the decorative top structure is partially penetrated into at least one intermediate layer situated in between the top structure and the core. More in particular, it is imaginable that a primer layer of the top structure, is partially penetrated into at least one intermediate layer situated in between the top structure and the core. Penetration of layers into each other typically increases the bonding strength between said layers.

Preferably, at least one intermediate layer comprises between 40-80%, more preferably at least 50% and/or less than 70%, most preferably approximately 60% (+/-3%), by weight of natural leather fibres. Preferably, at least one intermediate layer comprises between 10-40%, more preferably at least 15% and/or less than 35%, and most preferably approximately 20% (+/- 3%), by weight of synthetic polymer and/or natural polymer, in particular natural latex. Preferably, at least one intermediate layer comprises between 1 -20%, more preferably at least 5% and/or less than 15%, and most preferably approximately 10% (+/- 3%), by weight of fat, in particular natural fat. Preferably, at least one intermediate layer comprises between 1 -20%, more preferably at least 5% and/or less than 15%, and most preferably approximately 10% (+/- 3%), by weight of water and/or vegetable additive, such as vegetable tanning agent, and/or at least one other additive.

Preferably, at least one intermediate layer comprises at least one natural fat, such as fatty tissue derived from animals and/or vegetable oil, in particular rapeseed oil, wherein the amount of natural fat is preferably situated between 5 and 25%, and more preferably approximately 10% by weight of the intermediate layer. Typically, such a natural fat, such as natural oil, in particular rapeseed oil, acts as lubricant within the intermediate layer. The presence of one or more lubricants modulates or controls fibril-fibril bonding during dehydration to leather which improves the strength of the intermediate layer. Other suitable lubricants include surfactants, anionic surfactants, cationic surfactants, cationic polymeric surfactants, anionic polymeric surfactants, amphiphilic polymers, fatty acids, modified fatty acids, nonionic hydrophilic polymers, non-ionic hydrophobic polymers, poly acrylic acids, poly methacrylic, acrylics, natural rubbers, amphiphilic anionic polymer and copolymers, amphiphilic cationic polymer and copolymers and mixtures thereof as well as emulsions or suspensions of these in water, alcohol, ketones, and other solvents. In case a polymeric substance is used as lubricant, preferably a natural (bio)polymeric substance is used.

Furthermore, at least one intermediate layer comprises at least one additive, such as, preferably vegetable, tanning agent and/or water, wherein the amount of additive is preferably situated between 5 and 20 % and more preferably 10% by weight of the intermediate layer. Examples of vegetable tanning agents are pyrogallol- or pyrocatechin-based tannins, such as valonea, mimosa, ten, tara, oak, pinewood, sumach, quebracho and chestnut tannins; chromium tanning agents include chromium salts like chromium sulphate; aldehyde tanning agents include glutaraldehyde and oxazolidine compounds, syntans include aromatic polymers, polyacrylates, polymethacrylates, copolymers of maleic anhydride and styrene, condensation products of formaldehyde with melamine or dicyandiamide, lignin and natural flours.

The intermediate layer(s) may comprise at least one filler, preferably an inorganic filler, such and calcium carbonate and/or clays. These fillers may fill the interstitial spaces in loose leathers and in between leather particles, and make the looseness less pronounced, and hence the intermediate as such more robust.

Preferably, at least one intermediate layer comprises synthetic particles, in particular synthetic fibres, in particular polymer fibres. These particles may e.g. be formed by glass particles, carbon particles, silicon particles or other types of polymer fibres. It is imaginable that at least one intermediate layer has a textured upper surface, preferably an artificially textured upper surface. This increases the contact surface between the intermediate layer and an adjacent layer, which typically increases the bonding strength in between these layers. Moreover, this textured upper surface could contribute to a texture of the upper side of the panel.

Preferably, the density of at least one intermediate layer is between 0.75 and 0.95 g/cm ³ , preferably between 0.8 and 0.9 g/cm ³ , more preferably approximately 0.85 (+/- 0.02) g/cm ³ . The density is preferably measured by using ISO 2420.

Preferably, the thickness of at least one intermediate layer is between 0.75 and 0.95 mm, preferably between 0.77 and 0.87 mm, more preferably approximately 0.80 (+/- 0.02) mm. The thickness is preferably measured by using ISO2589.

Typically, each non-human collagen comprising intermediate layer is a flexible layer. This layer may be manufactured and marketed separately, preferably in a rolled up condition, prior to manufacturing of the panel according to the invention.

The core may be flexible, semi-rigid or substantially rigid. The core may be solid or at least partially foamed. The core is preferably at least partially, and more preferably entirely composed, of a natural material, such as wood or mineral. It is preferred that the core is at least partially, and more preferably entirely composed, of high-density fibreboard (HDF) or medium-density fibreboard (MDF). Alternatively, it could be preferred that the core is preferably at least partially, and more preferably entirely composed, of magnesium oxide and/or magnesium hydroxide. It is also imaginable that the core is formed by another type of mineral board, such as a cement board, in particular a fiber cement board. Alternatively, the core may comprise at least one polymer selected from the group consisting of: ethylene vinyl acetate (EVA), polyurethane (PU), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC), polyethylene terephthalate (PET), Polyisocyanurate (PI R), or mixtures thereof. The polymer may be a virgin polymer, a recycled polymer, or a combination of virgin polymer and recycled polymer. The core may comprise at least one wood-based material. The core may comprise at least one composite material of at least one polymeric material and at least one non-polymeric material. The at least one non-polymeric material is preferably selected from the group consisting of: talc, chalk, wood, calcium carbonate, leather, and a mineral filler. The non-polymeric material may be, for example, in the form of fibers and/or in the form of dust. The material of the core as such may also be free of any non-human collagen material. This latter doesn’t mean that it is not imaginable to embed at least one non-human collagen based intermediate layer into the core. In this embodiment the core and the embedded intermediate layer(s) are considered as separate layer. It is possible though that core material, such as polymeric core material, at least partially penetrates the embedded intermediate layer(s).

As said, the decorative top structure preferably comprises at least one primer layer applied onto at least one intermediate layer. The primer layer is intended to securely bond the ink of the decor image. The primer layer preferably comprises at least one acryl resin and/or at least one acrylate. The primer layer preferably has a white or whitish colour. The decor image may be directly printed on the primer layer, or directly onto the intermediate layer in case a separate primer layer is omitted.

It is imaginable that the decor image is directly printed onto a(n) (alternative) carrier layer, such as a paper sheet and/or polymeric film, wherein said carrier layer is affixed to at least one intermediate layer and/or onto at least one primer layer of the decorative structure.

Preferably, at least one transparent and/or translucent protective layer is formed by a wear layer. It is imaginable and often preferred that a plurality of the wear layers is applied. Preferably, at least one transparent and/or translucent protective layer is formed by a top coating, such as a UV hardened top coating, preferably applied on top of at least one wear layer of the decorative top structure. One or more transparent and/or translucent protective layers may be applied by printing, in particular digital printing.

The decorative top structure preferably comprises at least one decorative layer and at least one transparent wear layer covering said decorative layer. The decorative top structure may additionally comprise at least one back layer (also referred to as backing layer) situated in between said decorative layer and the core, wherein said back layer is preferably at least partially made of a vinyl compound, another polymer, wood, paper, textile, leather, such as cotton and/or recycled jeans (denim), and/or combinations thereof. The one or more materials used in said at least one back layer may virgin materials, recycled materials, and combinations thereof. Here, it is for example imaginable and even preferred that the back layer comprises a mixture of wood, cotton, preferably recycled cotton, more preferably recycled cotton based upon recycled jeans (denim), and/or virgin cotton; and at least one binding agent. The recycled cotton can be post-consumer recycled cotton, being a type of cotton that comes from garments which have been sold to and used by the consumer, such as jeans. Additionally or alternatively, the recycled cotton can be pre-consumer recycled cotton (cutting waste), which is a type of cotton that comes from the waste that is produced in the manufacturing process. Preferably, the back layer comprises wood in an amount of 20-60% by weight of the back layer, and a cotton based material, such as recycled jeans and/or raw cotton (virgin cotton), in an amount of 30-70% by weight of the back layer, and at least one binding agent, preferably in an amount of 1 -7% by weight of the back layer. The back layer may be free of PVC and/or any other synthetic polymer. Optionally, the back layer may act as decorative layer (which does not require a separate decorative layer on top).

A lacquer layer or other protective layer may be applied on top of said wear layer. The protective layer and/or wear layer preferably comprises silicon oxide (SiO2). Preferably, said protective layer is an UV cured protective layer, which is preferably applied, more preferably by using hot-coating, in liquid state prior to curing. A finishing layer, which may be an UV cured layer, may be applied in between the decorative layer and the wear layer. The decorative layer will be visible and will be used to provide the panel an attractive appearance. To this end, the decorative layer may have a design pattern, which can, for example be a wood grain design, a mineral grain design that resembles marble, granite or any other natural stone grain, or a colour pattern, colour blend or single colour to name just a few design possibilities. It is imaginable and may even be preferred that the decorative layer comprises at least one recycled material and/or at least one natural material, such as e.g. wood, coffee (e.g. coffee grounds, and/or ground coffee, and/or coffee powder, and/or coffee chaff), textile, cotton, in particular recycled jeans material, and/or mixtures thereof, for example a mixture of wood and a coffee based material. In this latter embodiment, the decorative layer may e.g. comprise wood in an amount of 40-80% by weight of the decorative layer, and a coffee based material, such as coffee grounds and/or coffee chaff, in an amount of 10-50% by weight of the decorative layer, and at least one binding agent, preferably in an amount of 1-7% by weight of the decorative layer. The decorative layer may be free of PVC and/or any other synthetic polymer. Additionally or alternatively, the decorative layer comprises a film, such as a polymer film, for example a PVC film, and/or a paper film, onto which at least one decor image is printed, preferably digitally printed. Customized appearances, often realized by digital printing during the panel production process, are also imaginable. The decorative top structure may also be formed by a single layer. In an alternative embodiment, the decorative top structure is omitted, thus not applied, in the panel according to the invention. In this latter embodiment, the upper side of the core constitutes the upper side of the panel.

The top surface of the decorative top structure, which defines the top surface of the panel, may be provided by a provided with a texture, which is preferably aligned in register with at least a part of at least one decor image of the decorative top structure. Preferably, the texture is a result of digital printing of one or more layers of the decorative top structure.

In a preferred embodiment, the first coupling profile and the second coupling profile are preferably configured such that two of such panels can be coupled to each other by means of a lowering movement (fold-down movement) and/or turning movement. In case the panel is rectangular, then the first panel edge and second panel edge are typically situated at opposite short edges of the panel. The panel preferably also comprises at least one third coupling profile and at least one fourth coupling profile located respectively at a third panel edge and a fourth panel edge, wherein the third coupling profile comprises: a sideward tongue extending in a direction substantially parallel to the upper side of the core, at least one second downward flank lying at a distance from the sideward tongue, and a second downward groove formed between the sideward tongue and the second downward flank, wherein the fourth coupling profile comprises: a third groove configured for accommodating at least a part of the sideward tongue of the third coupling profile of an adjacent panel, said third groove being defined by an upper lip and a lower lip, wherein said lower lip is provided with an upward locking element, wherein the third coupling profile and the fourth coupling profile are configured such that two of such panels can be coupled to each other by means of a turning movement (angling down movement), wherein, in coupled condition: at least a part of the sideward tongue of a first panel is inserted into the third groove of an adjacent, second panel, and wherein at least a part of the upward locking element of said second panel is inserted into the second downward groove of said first panel.

Preferably, the panel comprises a back layer (also referred to as underlay) which is affixed, either directly or indirectly, to a lower side of the core. As mentioned above, such a back layer may be formed by one of said intermediate layers. It is also imaginable that the back layer is formed by, for example, a polymer layer, a cork layer, preferably a high density cork layer (typically having a density of at least 150 kg/m3), a linoleum layer, and/or a composite layer, such as cork-linoleum composite layer. Also other materials, which may optionally be expanded (low density) or compressed (high density), may be used as backing layer. The backing layer is typically glued to the core. It is also imaginable that the backing layer and the core are fused together.

It is further preferred that the panel according to the invention has a thickness in the range of 3.0 mm to 20.0 mm, preferably in the range of 3.8 mm to 12.0 mm. The panel according to the invention, is preferably of a rectangular, parallelogrammatic, or hexagonal shape. The panel preferably has an oblong shape.

The invention also relates to a panel covering, in particular floor covering, ceiling covering, or wall covering, consisting of a plurality of, preferably mutually coupled, panels according to the invention.

The invention further relates to an intermediate layer comprising non-human collagen, wherein said intermediate layer is intended for use in a decorative panel according to the invention. These layers, embodiments of which have been described above and below in more detail, may be manufactured (and optionally separately marketed) separately and prior to the manufacturing of the decorative panels according to the invention.

The invention will be elucidated on the basis of non-limitative exemplary embodiments shown in the following figures. Herein:

Figure 1 shows a rectangular floor panel according to the present invention; Figure 2 is a cross-sectional view indicated by section A-A in Figure 1 ; Figure 3 is a cross-sectional view indicated by section B-B in Figure 1 ; Figures 4a-4f show different views of the successive steps for interconnecting multiple floor panels according to Figures 1-3 for forming a floor covering;

Figures 5a-5e show different embodiments of the first and second edges of a floor panel according to the invention;

Figure 6 shows a different embodiment of the third and fourth edges of a floor panel according to the invention; and

Figure 7 shows a detailed cross-sectional view of a panel according to one of Figures 1-6, wherein various (bonded) leather based intermediate layers are shown.

Figure 1 shows a rectangular floor panel 1 according to the present invention. The panel 1 is interconnectable with similar panels for forming a covering, as will be shown in further figures. The floor panel 1 can be made of any material, though typical materials are wood, in particular HDF, MDF, and LDF, and plastic, in particular thermoplastic, more in particular PVC. Commonly, the floor panel 1 is made of a laminate comprising a central layer (core layer) enclosed by a backing structure and a top structure (not shown). The top structure commonly comprises a decorative layer, which may be printed onto the central layer, on top of which a protective layer is applied. The panel 1 comprises a centrally located core 2 provided with an upper side 3 and a lower side 4. The core 2 is integrally connected with a first pair of opposite edges, in particular a first edge 5 and a complementary second edge 6, located at the long lateral sides of the panel 1 . The core is also integrally connected with a second pair of opposite edges, in particular a third edge 7 and a complementary fourth edge 8, located at the short sides of the panel 1 in this exemplary embodiment. Figure 2 is a cross-sectional view indicated by section A-A in Figure 1 . In this crosssection, the shape of the complementary first edge 5 and second 6 edge are shown in detail. The first edge 5 comprises a sideward tongue 9 which is integrally connected to the core 2. By means of the vertical dashed line the border between the sideward tongue 9 and the core 2 is visualised. A front region 9a of the sideward tongue 9 is provided with a rounded bottom surface 10. An outer end of the rounded bottom surface 10 adjoins an inclined locking surface 11 . An opposite end of the rounded bottom surface 10 adjoins a bearing surface 12 making part of a back region 9b of the sideward tongue 9. The second edge 6 of the panel 1 comprises an upper lip 13 and a lower lip 14 defining a recess 15. Both lips 13, 14 are integrally connected to the core 2. By means of the vertical dashed line the border between the lips 13, 14 and the core is visualised. As shown in Figure 2, the width of the upper lip 13 is substantially smaller than the width of the lower lip 14. The recess 15 has a shape which is complementary to the shape of the sideward tongue 9. More in particular, a top surface 16 of a back region 14a of the lower lip 14 has a (complementary) rounded shape, configured to co-act with the rounded front region 9a of the sideward tongue 9, while a front region 14b of the lower lip 14 is provided with a upwardly protruding shoulder 17, configured to co-act with the bearing surface 12 of the sideward tongue 9. A lower surface 18 of the upper lip 13 is inclined and corresponds to the locking surface 11 of the sideward tongue 9. Locking at the first edge 5 and the second edge 6 of adjacent panels 1 by insertion of the sideward tongue 9 of a panel 1 to be coupled into the recess 15, wherein said panel 1 is initially held in an inclined position. After insertion of the sideward tongue 9 into the recess, the panel 1 to be coupled will be pivoted (angled) in downward direction about an axis parallel to the first edge 5 until both panels 1 are positioned in the same - commonly horizontal - plane, wherein the locking surface 11 of the sideward tongue 9 will engage the locking surface of the upper lip 18, and wherein at least a bottom front part is accommodated substantially form-fittingly in the recess 15, and wherein the bearing surface 12 is supported by the shoulder 17. Locking at the first edge 5 and the second edge 6 leads to locking of the connected panels 1 in both horizontal direction and vertical direction. The angling down locking principle of the first and second edges 5, 6 is a relatively easy locking principle which facilitates mutual coupling of panels at these edges 5, 6 tremendously. Further details relating to this locking mechanism are visualised in Figures 4 and 5. Figure 3 is a cross-sectional view indicated by section B-B in Figure 1 . In this crosssection, the shape of the complementary third edge 7 and second 8 edge are shown in detail. The third edge 7 comprises an upward tongue 19, an upward flank 20 and an upward groove 21 formed between upward tongue 19 and upward flank 20. The upward tongue 19 is connected to the core 2 by means of a bridge 22, which is preferably resilient to some extent. A side 19a of upward tongue 19 facing toward upward flank 20 extends in the direction of the normal N1 of the upper side 3 of the core 2. The tangent R1 and the normal N1 of the upper side 3 of the core 2 are thus directed toward each other (converging orientation), wherein the angle enclosed by R1 and N1 is preferably between 0 and 10 degrees in this exemplary embodiment. Due to the converging orientation of the upward flank 20 and the side 19a of the upward tongue 19 facing toward to the upward flank 20, the upward groove 22 is a closed groove, which is only accessible to a complementary counterpart by deformation of the upward tongue 19 and/or bridge 22. Another side 19b of upward tongue 19 facing toward upward flank 20 forms an aligning edge enabling facilitated realization of a coupling to an adjacent floor panel 1 . As shown, this side 19b functioning as aligning edge is directed away from the normal N1 of upper side 3 of the core 2. An upper side 19d of upward tongue 19 does however extend in the direction of the normal N1 of the upper side 3 of the core 2, and runs inclining downward in the direction of the side 19e of upward tongue 19 facing away from upward flank 20. This chamfering provides the option of giving the complementary fourth edge 8 a more robust and therefore stronger form. A part of the side 19e of upward tongue 19 facing away from upward flank 20 is oriented substantially vertically and is moreover provided with an outward bulge 23. A lower part 20a of upward flank 20 is oriented diagonally, while an upper part 20b of upward flank 20 is shown to be substantially vertical and forms a stop surface for fourth edge 8. In between the inclined part 20a and the substantially vertical part 20b of the upward flank an additional coupling element, in particular an additional bulge 24, is provided. A lower wall part 21a of upward groove 21 is oriented substantially horizontally in this exemplary embodiment.

The fourth edge 8 is substantially complementary to third edge 7. The fourth edge 8 comprises a downward tongue 25, a downward flank 26 and a downward groove 27 formed between downward tongue 25 and downward flank 26. The downward tongue 25 is connected to the core 2 by means of a bridge 28, which is preferably resilient to some extent. A side 25a of downward tongue 25 facing toward downward flank 26 lies in the direction of the normal N2 of the lower side 4 of the core 2. This means that a tangent R2 of side 25a of downward tongue 25 and the normal of the lower side 4 of the core 2 are mutually converging, wherein the angle enclosed by R2 and N2 is preferably between 0 and 10 degrees in this exemplary embodiment. More preferably, the inclination of R1 is identical to the inclination of R2; hence, R1 and R2 are preferably parallel. Due to the converging orientation of the downward flank 26 and the side 25a of the downward tongue 25 facing toward to the downward flank 26, the downward groove 27 is a closed groove, which is only accessible for the upward tongue 19 of an adjacent panel 1 by deformation of the downward tongue 25 and/or bridge 28, as a result of which the entrance of the downward groove can be widened (temporary).

A side 25b of the downward tongue 25 facing away from downward flank 26 is diagonally oriented, but has a flatter orientation than the complementary side 20a of upward flank 20, whereby a gap (air space) will be formed in the coupled position, which will generally facilitate coupling between two floor panels 1. The inclining side 25b of downward tongue 25 also functions as aligning edge for the purpose of further facilitating coupling between two floor panels 1. Another side 25c facing away from downward flank 26 takes a substantially vertical form, though is provided with a small cavity 29 configured to co-act with the additional bulge 24 of another panel 1 . A top part of the side 25c facing away from downward flank 26 forms a complementary stop surface for stop surface 20b of upward flank 20 (of an adjacent floor panel). Downward flank 26 is oriented substantially vertically and is provided with a recess 30 adapted to receive the outward bulge 23 of the upward tongue 19 (of an adjacent floor panel).

Figures 4a-4f show different views of the successive steps for interconnecting multiple floor panels 1 according to Figures 1-3 for forming a floor covering 31 . Figures 4a and 4b relate to the first step of the installation process, wherein a first row of floor panels 1 is generated by connecting the third edge 7 of a panel 1 to the fourth edge 8 of an adjacent panel, by pressing - in a substantially vertical direction (as indicated by the arrow) - the fourth edge 8 of a panel 1 to be coupled onto and into the third edge 7 of an already installed panel 1 . Due to the vertical displacement, the third edge 7 and/or the fourth edge 8 will be deformed slightly, such that the downward tongue 25 will be pushed into the upward groove 21 , and the upward tongue 19 will be pushed into the downward groove 27. Moreover, the bulges 23, 24 will be positioned in the corresponding recesses 29, 30 to better secure the floor panels 1 with respect to each other. Due to this temporary deformation, wherein both the upward groove 21 and the downward grove 27 will be widened temporary for the insertion of the downward tongue 25 and the upward tongue 19 respectively, both edges 7, 8 will snap into each other.

Figures 4c and 4d relate to the second step of the installation process, wherein a second row of floor panels 1 is created which is connected to the first row of floor panels. To this end, a first edge 5 of a floor panel 1 to be coupled is positioned in an inclined orientation against a second edge 6 of an already installed panel 1 , such that the sideward tongue 9 is at least partially inserted in the complementary recess 15 of the second profile 6. After this partial insertion the inclined panel is pivoted (angled) down - see arrow - around an axis parallel to the first edge 5, until the panel 1 is located in the same plane as defined by the first row of panels, as a result of which the sideward tongue 9 will be locked into the recess 15 both in at least one horizontal direction and in vertical direction.

The first two steps as shown in Figures 4a-4d are preparatory steps for installation of one or more subsequent panels 1 which are to be coupled at multiple edges instead of only at a single edge. Installation of a subsequent floor panel 1 is visualised in Figures 4e and 4f. Again, a floor panel 1 to be coupled is held at inclined position, wherein the sideward tongue 9 of the floor panel 1 is inserted partially into the corresponding recess 15 of a second edge of at least one floor panel already installed. The fourth edge 8 of the floor panel 1 to be installed is positioned substantially above the third edge 7 of the panel 1 already installed in the second row, wherein the fourth edge 8 and the third edge 7 mutually enclose an angle (being the inclination angle of the panel to be coupled). During angling down of the panel 1 to be coupled (see arrow) both the first edge 5 and the fourth edge 8 of the panel 1 will be connected to adjacent panels 1 . More in particular, during angling down of the panel 1 , the front region of the sideward tongue 9 will be accommodated in the recess 15, and will be held in position by means of the limiting shoulder 17 and the limiting locking surface 18 of the upper lip 13 of the second edge 6 of the panel(s) already installed in the first row. Moreover, simultaneously the fourth edge 8 of the panel 1 to be coupled will make a downward scissoring movement with respect to the underlying third edge 7 and will zip (snap) into the third edge 7 and vice versa, leading to a firm and durable connection between the panels 1 .

Figures 5a-5e show different embodiments of the first and second edges of a floor panel according to the invention. In Figure 5a the embodiment according to Figures 1 -4f is shown, while in Figures 5b-5e alternative embodiments of these edges are shown. More in particular, Figure 5b shows a first and second edge 40, 41 of a floor panel 42, wherein, instead of a smoothly rounded bottom portion a more hooked (segmented rounded) bottom portion is shown. In Figure 5c, an embodiment of a floor panel 43 is shown which is almost identical to the floor panel shown in Figure 5a, though wherein the first and second edges 44, 45 are provided with horizontal locking surfaces 44a, 45b instead of inclined locking surfaces. In Figure 5d, an alternative embodiment of a floor panel 46 is shown, wherein the first and second edges 47, 48 are shaped such that a bottom contact portion between the two edges 47, 48 is partially smoothly rounded and partially discontinuously rounded (segmented rounded). Locking surfaces 50, 51 of a sideward tongue 49 of the first edge 47 and of an upper lip 52 of the second edge have a substantially horizontal orientation. In Figure 5e, an embodiment of a floor panel 53 almost identical to the floor panel 46 as shown in Figure 5d is shown, with the difference that a front bottom part 54a of a sideward tongue 54 is not smoothly rounded, but flat giving a bottom portion of the sideward tongue 54 as such a segmented rounded (hooked) shape.

Figure 6 shows a different embodiment of the third and fourth edges of a floor panel 57 according to the invention. Floor panel 57 comprises a core 58 provided with an upper side 58a and a lower side 58b, and coupling parts 59, 60 positioned on opposite longitudinal sides of core 58 and connected integrally to core 58. A first coupling part 59 comprises an upward tongue 61 , an upward flank 62 and an upward groove 63 formed between upward tongue 61 and upward flank 62. A side 61 a of upward tongue 61 facing toward upward flank 62 is inclined and extends in the direction of the normal N1 of the upper side 58a of core 58. The tangent R1 and the normal N1 of upper side 58a of core 58 are thus directed toward each other (converging orientation), wherein the angle enclosed by R1 and N1 amounts to 3-5 degrees. On top of side 61 a, a substantially flat upward aligning edge 61 b of the upward tongue 61 is positioned, which faces toward upward flank 62 and which enables facilitated realization of a coupling to an adjacent floor panel. The inclined surface 61 a, acting as locking surface, and the adjoining upward aligning edge 61 b together form the inner side surface of the upward tongue 61 . As shown, this side 61 b functioning as upward aligning edge is substantially flat and, moreover, directed away from the normal N1 of upper side 58a of the core. A (single) upper side 61 d of upward tongue 61 does however extend in the direction of the normal N1 of upper side 68a of core 68, and runs inclining downward in the direction of the side 61 e of upward tongue 61 facing away from upward flank 62. The angle of inclination is about 30 degrees. This chamfering provides the option of giving the complementary second coupling part 60 a more robust and therefore stronger form, as will be elucidated below. The side 61 e of upward tongue 61 facing away from upward flank 62 is oriented substantially vertically and is moreover provided with an outward bulge 64 which clearly extends with respect to vertically oriented parts of the outer side wall 61 of the upward tongue 59. A lower part 62a of upward flank 62 is oriented diagonally, while an upper part 62b of upward flank 62 is shown to be substantially vertical and forms a stop surface for second coupling part 60. A lower wall part 63a of upward groove 43 is oriented substantially horizontally in this exemplary embodiment. A bridge 65 lying between lower wall part 63a of upward groove 63 and a lower side 59a has a somewhat elastic nature and is adapted to allow upward tongue 61 to slightly pivot relative to upward flank 62, this resulting in a (temporary) widening of upward groove 63, whereby coupling of floor panel 57 to an adjacent floor panel can be facilitated. Second coupling part 60 is substantially complementary to first coupling part 59. Second coupling part 60 comprises a downward tongue 66, a downward flank 67 and a downward groove 68 formed between downward tongue 66 and downward flank 67. A side 66a of downward tongue 66 facing toward downward flank 67 is inclined and extends in the direction of the normal N2 of the lower side 58b of core 58. This means that a tangent R2 of side 66a of downward tongue 66 and the normal of the lower side 58b of core 58 are mutually converging. In this exemplary embodiment the tangent R2 and the normal N2 enclose a mutual angle of 3-5 degrees. A side 66b facing away from downward flank 67 is diagonally oriented, but has a flatter orientation than the complementary side 62a of upward flank 62, whereby a gap (air space) will be formed in the coupled position, which will generally facilitate coupling between two floor panels 57. The inclining side 66b of downward tongue 66 also functions as aligning edge for the purpose of further facilitating coupling between two floor panels 57. Another side 66c facing away from downward flank 67 takes a substantially vertical form and forms a complementary stop surface for stop surface 62b of upward flank 62 (of an adjacent floor panel). Downward tongue 66 is further provided with a small aligning edge 66d which is facing toward downward flank 67. Because upper side 61 d of upward tongue 61 has an inclining orientation, an upper side 68a of downward groove 68 likewise can be given, and in this embodiment has, a corresponding inclining orientation, whereby the (average) distance between upper side 68a of downward groove 68 and an upper side 60a of second coupling part 60 is sufficiently large to impart sufficient strength to second coupling part 60 as such. Downward flank 67 is oriented substantially vertically and is provided with a recess 69 adapted to receive the outward bulge 64 of upward tongue 61 (of an adjacent floor panel).

A bridge 70 lying between upper side 68a of downward groove 68 and upper side 60a has a somewhat elastic nature due its reduced thickness close to the downward tongue 66 (and possibly also due to material characteristics), and is adapted to allow downward tongue 66 to slightly pivot relative to downward flank 67, this resulting in a (temporary) widening of downward groove 68, whereby coupling of floor panel 67 to an adjacent floor panel can be facilitated. This pivoting point (point of deformation) is typically formed by the weakest point in the bridge 70, which is indicated by the sign “P”. The shown floor panel 67 can form a parquet floor panel, a plank, a laminated floor panel and/or a plastic floor panel. The coupling parts 59, 60 and the core 58 are preferably integrally connected.

Figure 7 shows a detailed cross-sectional view of a panel 57 according to one of Figures 1 -6 and/or which can be combined (integrated) with a panel as shown in one the previous figures. The panel 57 shown in figure 7 comprises a core 58, wherein said core 58 comprises an upper side 58a and a lower side 58b. According to this non-limitative embodiment of the panel 57 the upper side 58a of the core 58 is provided with at least one intermediate layer 71 , on top of which intermediate layer 71 a decorative top structure 72 is provided. It is conceivable that said core layer 58 is optionally provided with a further intermediate layer 79 that is embedded in the core 58, said further intermediate layer 79 may function as reinforcement of the core. The optional intermediate layer 79 may, for example, be a woven or nonwoven glass fibre layer. Another, yet further intermediate layer 78 may optionally be affixed to the lower side 58b of the core 58, and as such function as a damping or sound absorbing layer. Said intermediate layers 71 , 78, 79 comprise at least a non-human collagen and/or leather, more preferably bonded leather. It is conceivable that at least one, or all intermediate layers 71 , 78, 79 comprise a layered structure having at least a carrier layer, onto which carrier layer particles, such as leather particles, are bonded by means of a binding material. It is conceivable that said carrier layer may be composed out of a paper, fabric, and/or a polymer layer and may either be woven or non-woven. In order to adhere the leather particles to said carrier layer, the binding material may partially penetrate into the carrier layer. At least one intermediate layer 71 , 78, 79 may in particular comprise between 40-80% by weight of genuine leather fibres, preferably 60% of genuine leather fibres, between 10-40% by weight of natural latex, preferably 20% by weight of natural latex, preferably additionally between 5-25% by weight of natural fat, preferably 10% by weight of natural fat, and preferably between 5-20% by weight of miscellaneous raw material, preferably 10% by weight of miscellaneous raw material. Said raw material may as a non-limited example be a vegetable tanning agent, water, or the like.

The encircled portion, A, of the panel 57 is enlarged for the sake of clarity to further elucidate the structure of the layers 73, 74, 75, 76, 77 provided onto the upper side 58a of the core 58. At least one carrier layer provided with leather particles 73 (which is a specific embodiment of the intermediate layer 71), as described above, is affixed directly onto the upper side 58a of the core 58. The carrier layer with leather particles 73 may optionally be referred to as a bonded leather layer 73. The side of the carrier layer comprising the leather particles preferably faces away from said upper side 58a. A primer 74 is provided onto said carrier layer provided with leather particles 73. Preferably, said primer layer 74 partially penetrates the intermediate layer 71 , 73, and a digital print layer 75 may as a result be affixed sufficiently to said intermediate layer 71 , 73. However, optionally, it is conceivable that said print layer 75 is, preferably digitally, printed directly on top of the intermediate layer 71 , 73 and/or primer layer 74. To protect the bonded leather layer 73 and the print layer 75 it is conceivable that at least one wear layer 76 is provided over at least a part of the print layer 75, preferably covering essentially the entire panel 57. Although in this figure only one wear layer 76 is depicted, the skilled person would realise that a plurality of wear layers 76 may be provided. A top coating 77 essentially entirely covers the wear layer 76, which top coating 77 may for example be a lacquer or the like.

Although the intermediate layers 71 , 78, 79 and the decorative top structure 72 are only depicted in this particular figure, it may be realized that said layers, either in this particular non-limitative configuration or separately, may be applicable to any of the embodiments according to the preceding figures. That is, all the layers elucidated in this figure, may be combined separately of one another in various embodiments according to the present invention.

The ordinal numbers used in this document, like “first”, “second”, “third”, and “fourth” are used only for identification purposes. Hence, the use e.g. of the expressions “third locking element” and “second locking element” does therefore not necessarily require the co-presence of a “first locking element”. The decorative panels according to the invention may also be referred to as decorative tiles. By "complementary" coupling profiles is meant that these coupling profiles can cooperate with each other. However, to this end, the complementary coupling profiles do not necessarily have to have complementary forms. By locking in "vertical direction" is meant locking in a direction perpendicular to the plane of the panel. By locking in "horizontal direction" is meant locking in a direction perpendicular to the respective coupled edges of two panels and parallel to or falling together with the plane defined by the panels.

It will be apparent that the invention is not limited to the working examples shown and described herein, but that numerous variants are possible within the scope of the attached claims that will be obvious to a person skilled in the art.

The verb “comprise” and conjugations thereof used in this patent publication are understood to mean not only “comprise”, but are also understood to mean the phrases “contain”, “substantially consist of”, “formed by” and conjugations thereof.