Panel and system for constructing a floor or wall covering

Abstract

The invention relates to a panel for constructing a floor or wall covering. The invention also relates to a support element for use in such panel. The invention further relates to a system comprises a plurality of panels according to the invention, in particular to construct or form a floor or a wall covering.

Description

[0001] Panel and system for constructing a floor or wall covering

[0002] The invention relates to a panel for constructing a floor or wall covering. The invention also relates to a support element for use in such panel. The invention further relates to a system comprises a plurality of panels according to the invention, in particular to construct or form a floor or a wall covering.

[0003] Ceramic tiles are widely used as a floor and wall covering in both residential and commercial applications. Ceramic tiles are available in a nearly unlimited color palette and may be installed in an equally unlimited number of designs. This tile is often a top choice for floor and wall coverings because of its waterproofness, great durability and aesthetic qualities. When tiles are installed, they are generally laid side by side on a surface such as a floor or wall. Typically, an adhesive compound is used as a base to attach the tiles to a supporting surface, after which grout is spread over and between the tiles to further bind the tiles to the supporting surface and to fill spaces between adjacent tiles. Due to the time and labor involved in tile installation, it is typically quite costly to have tile professionally installed. Accordingly, many homeowners desire to install tile in their own homes.

[0004] Unfortunately, this is an extremely tedious process, and many homeowners do not wish to spend the time necessary for a satisfactory installation. In recent years, manufactures have attempted to produce do-it- yourself tile solutions that are easier to install. A difficulty, however, is that a click profiling section cannot be directly accomplished at the edges of the ceramic tiles, due to the hardness and brittleness of the material. In fact, the profiling processing cannot be performed directly on the ceramic since, during the profiling process, the milling cutters fail to affect and shape the profile to obtain the aforesaid connection system with the decimal tolerance required by the market of laminate flooring, LVT, or wooden parquet. In addition, the profiling can chip the ceramic material and give rise to breakages / abrasions / cracks or fissures so as to compromise the aesthetic appearance of the profiled element and the traction connection / sealing of the click joint. There is demand for floor panels which are strong, resistant to impact, sound dampening, stable under several conditions, and easy-to-install. It is a first goal of the present invention to provide a prefabricated panel or tile with a ceramic or equivalent top layer, and which can be installed in a relativity simple manner, preferably without using glue and / or grout.

[0005] It is a second goal of the present invention to provide a prefabricated multilayer sound-dampening panel or sound-dampening tile with a ceramic or equivalent top layer.

[0006] It is a third goal of the present invention to provide an improved prefabricated multilayer panel with a ceramic or other hard top layer.

[0007] It is a fourth goal of the present invention to provide a prefabricated multilayer panel or with a ceramic or other top layer configured to be mechanically interconnected with other panels or tiles.

[0008] At least one of these goals can be achieved by providing a panel for constructing a floor or wall covering, comprising: at least one, preferably natural, binder selected from elastomeric and thermoplastic binders; natural particles, particularly natural fibers, dispersed in said binder; preferably water; and at least one decorative top layer which is affixed, either directly or indirectly, to the upper surface of the support element, wherein the top layer is at least partially made of at least one material chosen from the group consisting of: ceramic, stone, steel, concrete, mineral porcelain, glass, mosaic, granite, limestone and marble.

[0009] The composite material, also referred to as bio-composite material, is preferably flexible. The composite material preferably has a compressive strength of at least 800 kPa, preferably at least 900 kPa, more preferably at least 1000 kPa. This combination of flexibility and strength allows for easier installation while maintaining durability under load. Moreover, contrary to e.g. cork, the composite material of the support element having this flexibility and relatively high compressive strength (compared to cork) will not be inclined to break during normal load (and normal use), which will therefore prevent the formation of acoustic bridges to a subfloor, as a result of which an adequate sound dampening effect can be secured. Moreover, the cost price of the composite material of the support element is typically below the cost price of a support element which would be composed of cork. The binder preferably comprises an elastomer, such as rubber and / or a thermoplastic elastomer (TPE). In some embodiments, the binder comprises natural rubber. The use of elastomeric binders contributes to the panel's flexibility and resilience.

[0010] The rubber, if applied, is preferably at least one rubber chosen from the group consisting of: natural rubber (NR), styrene-butadiene rubber (SBR), ethylene- propylene-diene monomer rubber (EPDM), nitrile rubber (NBR), and recycled rubber. Natural rubber (NR), with its high elasticity and abrasion resistance, provides a durable and flexible layer to absorb impact and reduce noise. Styrenebutadiene rubber (SBR) offers cost-effective impact resistance and abrasion protection, making it ideal for general-purpose applications. Ethylene-propylene- diene monomer rubber (EPDM) excels in weather, heat, and UV resistance, making it suitable for outdoor floor or wall panels. Nitrile rubber (NBR), known for its superior oil and chemical resistance, is ideal for panels in industrial or chemical- prone environments. Finally, recycled rubber is an eco-friendly and cost-effective choice, offering excellent impact and sound absorption for sustainable floor or wall panel systems.

[0011] The TPE, if applied, is preferably at least one TPE chosen from the group consisting of: styrene based TPE (SBS, SEBS), polyolefin elastomers (POE), thermoplastic polyurethane (TPU), thermoplastic vulcanizate (TPV), and recycled TPE. Thermoplastic elastomers (TPEs) may be advantageously used in the support element due to its versatile properties. Styrene-based TPEs (SBS, SEBS) provide high flexibility, softness, and sound-dampening, making them ideal for residential or gym flooring panels. Polyolefin elastomers (POE) are lightweight and resistant to impact, offering excellent insulation and durability for subfloor or wall applications. Thermoplastic polyurethane (TPU) stands out for its superior wear resistance, elasticity, and tear strength, making it perfect for heavy-traffic areas or industrial panels. Thermoplastic vulcanizates (TPV) combine the elasticity of rubber with the ease of thermoplastic processing, excelling in outdoor applications due to their resistance to heat, UV, and weathering. Lastly, recycled TPEs are an eco-friendly and cost-efficient option, providing moderate mechanical properties for sustainable floor or wall panel systems. The binder may be at least partially crosslinked, which can enhance the overall strength and durability of the composite material. Crosslinking in rubbers and TPEs enhances their mechanical, thermal, and chemical properties, making them highly suitable as support elements for rigid top layers in floor or wall panels. The three- dimensional network formed during crosslinking improves elastic recovery, allowing the material to deform under stress and return to its original shape, which is critical for impact absorption and durability. It also increases tensile strength, wear resistance, and fatigue resistance, ensuring long-term integrity in high-traffic or heavy-load applications. Crosslinking enhances heat and chemical resistance, making these materials ideal for environments exposed to temperature fluctuations or harsh substances, such as outdoor areas or industrial settings. Additionally, it provides superior dimensional stability, reducing creep or deformation over time, and improves sound and vibration dampening by dissipating energy more effectively. Examples include vulcanized rubbers like NR, SBR, and EPDM, which offer excellent elasticity and durability, and TPVs, a type of TPE with crosslinked rubber particles that combine the benefits of crosslinking with easier processing and recyclability. These properties ensure that crosslinked rubbers and TPEs deliver reliable, long-lasting performance in demanding flooring and wall panel systems.

[0012] Additionally or alternatively, the support element may comprise at least one (other) thermoplastic material, preferably at least one thermoplastic material that is selected from the group consisting of polypropylene (PP), thermoplastic polyurethane (TPU), polystyrene (PS), polyethylene (PE), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), poly(ethylene 2,5- furandicarboxylate) (PEF), polyvinyl chloride (PVC), and mixtures of two or more of these thermoplastic materials.

[0013] The support element is designed to be flexible, which allows it to conform to minor subfloor imperfections and facilitates easier cutting and handling during installation. Moreover, this flexibility allows adjacent support elements to form-fittingly abut each other without leaving gaps, which is in favour of the sound dampening properties of a system composed of a plurality of panels according to the invention. Typically, the top layer has a Mohs hardness of at least 4. For example, the Mohs hardness of the top layer is typically 7 in case the top layer comprises ceramic, 5.5 in case the top layer comprises glass and at least 4.5 in case steel is used. The top layer is preferably a hard tile. The top layer preferably has a thickness of at least 3 mm and may e.g. range from 3 mm to 30 mm in thickness. In another embodiment, the top layer may range from 3 mm to 25 mm in thickness. T n yet another embodiment, the top layer may range from 3 mm to 15 mm in thickness, or from 3 mm to 12 mm, or from 3 mm to 10 mm, or from 3 mm to 8 mm, or from 3 mm to 6 mm in thickness.

[0014] The support elements typically has a lower Mohs hardness compared to the top layer. Preferably, the support element has a Mohs hardness of less than 4, preferably less than 3, more preferably less than 2.

[0015] The Mohs hardness is measured by using the Mohs hardness test: the Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The Mohs hardness scale is in the range 1 to 10.

[0016] The Shore A hardness of the support element is preferably less than 90, and preferably more than 45. This range of hardness provides a balance between flexibility and durability. The Shore A hardness of a material is measured using a durometer, a specialized instrument designed to test the hardness of soft, elastic materials like rubbers and thermoplastic elastomers (TPEs), and is preferably measured by applying the international standard ASTM D2240.

[0017] The tear strength of the support element may be situated between 55 and 75 N / mm, offering good resistance to tearing during installation and use.

[0018] The natural particles in the composite material may include cotton fibers, particularly recycled cotton fibers. This use of recycled materials, preferably obtained from recycled jeans, contributes to the environmental sustainability of the product. The natural particles may comprise a mixture of plant fibers (e.g., cotton fibers) and natural particle dust (e.g., plant dust, cotton dust). The plant fibers may have an average length of between 1 and 20 mm, particularly between 1 and 5 mm. The natural particle dust, if applied, may have an average size of between 1 and 100 microns. These size ranges allow for optimal distribution and bonding within the composite material.

[0019] In a preferred embodiment, at least a fraction of the natural particles comprises a mixture of cotton fibers and at least one additional plant fiber selected from hemp fibers, seagrass fibers, bast fibers (such as flax, kenaf, jute, or ramie), or leaf fibers (such as sisal, abaca, pineapple leaf fiber, or coir). This combination of different fiber types may provide synergistic benefits to the composite material of the support element by creating a multi-scale fiber network. Cotton fibers, particularly recycled cotton fibers from sources such as denim, are short (typically 1-5 mm staple length), relatively fine, and almost pure cellulose with a hollow lumen and crimped shape. These characteristics make cotton an excellent damping and comfort fiber that contributes softness, high porosity, and energy-absorbing properties to the composite. The lumen and surface roughness of cotton fibers create numerous internal air pockets and frictional interfaces that, under dynamic load such as walking or impact, move, bend and rub against the matrix and each other, resulting in viscoelastic and frictional losses that provide good sound absorption. This directly supports the target sound absorption coefficient of at least 0.4 and high sound transmission loss. Additionally, cotton fibers are soft and collapsible, buckling and flattening gradually under compressive load instead of cracking like rigid mineral fillers, which provides a smooth stress-strain curve and contributes to achieving high compressive strength (at least 800 kPa) without brittle failure.

[0020] The additional plant fibers, such as hemp or seagrass, act as stiff, high-aspect-ratio structural fibers that complement cotton's damping role. Hemp fibers, which are bast fibers with high cellulose content and crystallinity, provide high modulus and tensile strength compared to cotton. These longer technical fibers (typically exceeding 10-20 mm before cutting) with higher aspect ratio act like microreinforcing elements within the rubber or thermoplastic elastomer matrix. Hemp fibers bridge microcracks and carry load along their length, increasing compressive stiffness, tear strength (contributing to the 55-75 N / mm range), and resistance to fatigue. This reinforcement helps achieve compressive strength of at least SOO- WOO kPa while keeping the matrix relatively soft (Shore A less than 90). The high- modulus, high-aspect-ratio hemp fibers also restrict long-term flow of the elastomer or thermoplastic elastomer matrix, reducing creep and improving compressive set, which helps maintain low moisture-induced expansion and shrinkage. Furthermore, the longer, stiffer hemp fibers form a percolated network in the matrix that, under dynamic loading, flexes and rubs internally to dissipate energy, particularly at lower frequencies than the cotton micro-network. Combined with cotton, this provides broadband acoustic absorption, with cotton dominating mid-high frequencies and hemp contributing more to low-mid frequencies.

[0021] Seagrass fibers, which are coarser, often ribbon-like fibers with high porosity and waxy or cuticular surfaces, provide similar stiff co-fiber reinforcement with additional benefits. The relatively high lignin and mineral content of seagrass results in good stiffness and excellent resistance in humid or saline environments. The waxy, hydrophobic surfaces and marine origin of seagrass provide good stability in humid environments, and when combined with a low coefficient of moisture expansion rubber matrix and flexible adhesive, they limit moisture-driven movement and potential debonding or delamination. The highly porous internal structure and surface roughness of seagrass provide strong acoustic scattering and absorption, and in combination with cotton, create both micro- and macro-porosity with a rich network of air paths that contribute to good sound absorption coefficient and sound transmission loss without requiring extremely thick support elements.

[0022] The mixture of cotton with hemp, seagrass, or other structural fibers is superior to either fiber type alone because it creates a hybrid reinforcement system with multiple technical advantages. The multi-scale fiber network, with cotton providing a dense micro-network and hemp or seagrass providing a coarser macro-network, results in mechanically interlocked networks at different length scales that deliver high toughness, good tear resistance, and strong damping. This combination balances stiffness versus flexibility, as cotton alone would provide very good damping but would be too soft with lower compressive strength and larger creep, while hemp or seagrass alone would be stiff but risk brittleness, processing difficulties such as fiber clumping and uneven surfaces, and potentially too high Shore hardness. The blend achieves the desired Shore A range of 45-90 with the required compressive strength while maintaining a flexible support element. The mixture also improves the processing window, as cotton improves mixing and calendering by acting like a soft, fluffy internal lubricant and by breaking up hemp or seagrass bundles, while hemp or seagrass prevent the cotton-rich matrix from becoming too rubbery and sticky, which can otherwise complicate cutting and profiling, especially for coupling profiles. The acoustic tuning provided by this combination, with cotton providing strongly damped deformation with internal friction for excellent absorption at mid-high frequencies and hemp or seagrass providing a stiffer network with heavier, longer fibers that shift absorption peaks and damping into lower frequencies and improve sound transmission loss, allows the composite to reach a sound absorption coefficient of at least 0.4 and sound transmission loss of at least 35 dB at frequencies of at least 250 Hz at practical thicknesses.

[0023] Optionally, other bast fibers may be used in place of or in combination with hemp to provide similar reinforcement benefits. Flax fibers, which have very high modulus and strength among natural fibers with a fine cross-section, provide excellent reinforcement, low creep, and very good dimensional stability, and may be chosen where slightly more stiffness and less coarseness than hemp is desired. Kenaf, another bast fiber with high cellulose content and decent stiffness that is widely used in automotive biocomposites, works well with cotton to tune stiffness and damping. Jute, which has slightly lower modulus than flax or hemp but is still significantly stiffer than cotton, is economical and readily available in large quantities, providing good reinforcement and dimensional stability, with slightly higher lignin content that can improve moisture robustness compared to pure cotton. Ramie or nettle fibers, which have very high cellulose crystallinity and strength, provide strong reinforcement similar to or better than hemp. Alternatively, leaf fibers may be used to provide coarser, more porous, moisture-robust reinforcement similar to seagrass. Sisal, a stiff, relatively coarse leaf fiber with good tensile strength and abrasion resistance and higher lignin content that increases rigidity and moisture resistance compared to cotton, is good for edge stability, coupling profiles, and low-frequency acoustic damping. Abaca (Manila hemp), another stiff leaf fiber used in ropes and specialty papers with good wet strength and durability, behaves somewhat between hemp and seagrass in composites. Pineapple leaf fiber (PALF), a fine, high-strength leaf fiber with relatively high cellulose content, provides excellent reinforcement with lower density and good compatibility in polymer matrices, and is useful where strong reinforcement without excessive weight is desired. Coir (coconut fiber), which is coarse, highly lignified and very tough with excellent performance in wet environments, has lower modulus than flax or hemp but excellent impact and fatigue resistance, making it good for vibration damping and moisture robustness, particularly where impact and water resistance are more critical than maximum stiffness.

[0024] In some embodiments, the cotton fibers may constitute between 30% and 70% by weight of the total natural fiber content, with the remaining portion comprising one or more of the additional plant fibers. The fiber length ranges may be maintained within the disclosed ranges, with cotton fibers having an average length of 1-5 mm and the co-fibers tailored to similar or slightly greater average lengths, while maintaining the weight ratio of natural particles to binder between 0.8 and 4. The selection among these alternative fibers may be optimized based on specific performance requirements: for maximum stiffness and dimensional stability (compressive strength, low creep, precise click profiles), cotton may be combined with flax, ramie, or kenaf; for balanced stiffness, cost, and acoustics, cotton may be combined with hemp, jute, or kenaf; for high moisture robustness and low- frequency damping (bathrooms, ground floors, outdoor walls), cotton may be combined with seagrass, sisal, abaca, or coir; and for lower density but still good reinforcement (weight-sensitive wall panels), cotton may be combined with pineapple leaf fiber or flax.

[0025] Additionally, or alternatively, animal leather fibers may also be used as natural particles in the composite material. These may be mixed with natural particle dust, such as animal leather dust or leather buffing dust. The animal leather fibers may have an average length of between 0.5 and 5 mm, while the natural particle dust, if applied, may have an average size of between 0.1 and 500 microns. It was found that the addition of the leather buffing dust (as filler) to a rubber material of the support element brings improvement in mechanical properties and increase in resistance to thermal ageing and crosslink density of vulcanizates, such as carboxylated butadiene-acrylonitrile rubber-(XNBR) and butadiene-acrylonitrile rubber (NBR).

[0026] Animal leather particles, in particular fibers and / or dust, comprise crosslinked collagen, typically in a three-dimensional structure. However, untreated leather fibers are of acidic nature and typically affects the vulcanization of rubber in the support element. Hence, it is preferred to neutralize the leather (if not already done), before using this leather particles as a filler in the support element. Treatment of leather with too alkaline substances, like NaOH, could affect the rubber as these alkaline substances react with collagen and therefore destroy the collagen structure. It was found that a more neutral treatment, for example by using a urea solution, leads to the best property improvements of the leather particles and their bonding interface with the rubber matrix material of the support element.

[0027] In a preferred embodiment, at least a fraction of the natural particles is formed by a mixture of animal leather fibers and at least one plant fiber chosen from cellulose fibers and wood fibers. This combination may provide a unique balance of properties that leverages the distinct characteristics of both animal-derived and plant-derived materials. Animal leather fibers, which comprise crosslinked collagen in a three-dimensional structure, may contribute excellent flexibility, toughness, and tear resistance to the composite material. The collagen structure provides good energy absorption under dynamic loading, which contributes to the acoustic dampening performance of the support element. When combined with cellulose fibers or wood fibers, the resulting composite may exhibit enhanced mechanical properties compared to composites containing only one fiber type. The cellulose fibers or wood fibers may provide additional stiffness and dimensional stability through their high cellulose content and crystallinity, while the leather fibers may maintain the flexibility and resilience of the support element. This combination may be particularly advantageous for achieving the desired balance between flexibility and compressive strength in the support element, as the leather fibers provide a soft, energy-absorbing component while the plant fibers act as reinforcing elements that restrict matrix flow and reduce creep.

[0028] The plant fibers, such as wood fibers or cellulose fibers, may function similarly to the structural fibers described in the cotton-hemp combination, providing a higher- modulus, higher-aspect-ratio reinforcement network within the elastomeric matrix. Wood fibers, which may include both softwood and hardwood fibers, may be particularly effective in improving the compressive strength of the support element while maintaining adequate flexibility. These fibers may bridge microcracks and carry load, contributing to the achievement of compressive strength of at least 800 kPa and tear strength in the range of 55-75 N / mm. Cellulose fibers, which may be derived from various plant sources including cotton linters, wood pulp, or other cellulosic materials, may provide excellent reinforcement due to their high aspect ratio and strong hydrogen bonding capabilities. The combination of leather fibers with cellulose or wood fibers may create a multi-scale reinforcement system where the leather fibers provide micro-scale damping and flexibility while the plant fibers provide macro-scale stiffness and dimensional stability.

[0029] Optionally, the leather fibers may be sourced from recycled leather materials, such as leather waste from the furniture or automotive industries, thereby contributing to the environmental sustainability of the panel. The plant fibers, such as wood fibers, may similarly be derived from recycled sources or sustainable forestry practices. In some embodiments, the weight ratio of leather fibers to plant fibers may range from 1 :3 to 3:1 , preferably around 1 :1 , to optimize the mechanical properties of the composite. This ratio may provide a balance between the damping and flexibility characteristics of the leather fibers and the reinforcement and dimensional stability provided by the plant fibers. The addition of cellulose fibers or wood fibers to the leather fiber matrix may also improve the processability of the composite material during manufacturing, as these plant fibers may help to distribute the leather fibers more uniformly throughout the elastomeric binder and may prevent excessive stickiness or clumping during mixing and calendering operations. The plant fibers may also facilitate cutting and profiling operations, particularly when forming coupling profiles at the edges of the support element.

[0030] The mixture of leather fibers with plant fibers may provide improved acoustic performance compared to either fiber type alone. The leather fibers, with their collagen structure and inherent damping characteristics, may provide good energy dissipation under dynamic loading, particularly at mid to high frequencies. The plant fibers, with their stiffer structure and higher aspect ratio, may contribute to acoustic absorption at lower frequencies through the formation of a percolated network that flexes and rubs internally under dynamic loading. This combination may help achieve the target sound absorption coefficient of at least 0.4 and sound transmission loss of at least 35 dB at frequencies of at least 250 Hz. Additionally, the mixture may provide improved dimensional stability and resistance to moisture- induced expansion or contraction, as the different fiber types may respond differently to moisture, thereby providing a compensating effect that stabilizes the overall composite. Optionally, the plant fibers may be treated or modified to improve their compatibility with the elastomeric binder and the leather fibers. For example, the plant fibers may be subjected to alkaline treatment, silane treatment, or acetylation to modify their surface chemistry and enhance interfacial adhesion.

[0031] In a preferred embodiment, at least a fraction of the natural particles is formed by a mixture of animal leather fibers, at least one plant fiber chosen from cellulose fibers and wood fibers, and at least one other natural particle, in particular at least one other natural fiber. This three-component natural particle system may provide enhanced versatility and performance characteristics by combining the distinct properties of animal-derived materials, structural plant fibers, and additional natural particles that can be selected to optimize specific properties of the composite material. The animal leather fibers, which comprise crosslinked collagen in a three- dimensional structure, may contribute excellent flexibility, toughness, and tear resistance to the composite material, while also providing good energy absorption under dynamic loading that contributes to acoustic dampening performance. The plant fibers, such as cellulose fibers or wood fibers, may provide structural reinforcement with their high cellulose content, crystallinity, and aspect ratio, acting as stiff, load-bearing elements that bridge microcracks, restrict matrix flow, and reduce creep. The third component, which may be at least one other natural particle or natural fiber, allows for fine-tuning of the composite properties to meet specific application requirements.

[0032] The at least one other natural particle or natural fiber may be selected from a wide range of options depending on the desired characteristics of the final panel. Optionally, this third component may comprise cotton fibers, which are short, fine, and highly porous fibers with a hollow lumen structure that provides excellent damping and acoustic absorption properties. The addition of cotton fibers to a mixture of leather fibers and wood or cellulose fibers may create a three-scale fiber network: the cotton fibers forming a very fine micro-network for high-frequency acoustic damping and comfort, the leather fibers forming an intermediate-scale network for flexibility and energy absorption, and the wood or cellulose fibers forming a coarser macro-network for structural reinforcement and dimensional stability. This multi-scale architecture may result in superior mechanical properties, including high compressive strength (at least 800 kPa), good tear resistance (55-75 N / mm), and excellent acoustic performance across a broad frequency range, with the ability to achieve a sound absorption coefficient of at least 0.4 and sound transmission loss of at least 35 dB at frequencies of at least 250 Hz.

[0033] Alternatively, the at least one other natural particle may comprise stiff, high-aspect- ratio fibers such as hemp, flax, kenaf, jute, or ramie (bast fibers), or sisal, abaca, pineapple leaf fiber, or coir (leaf fibers). These fibers may complement the leather and plant fiber combination by providing additional structural reinforcement, improved dimensional stability, and enhanced resistance to creep and fatigue. For example, a mixture of leather fibers (for flexibility and damping), wood fibers (for moderate reinforcement and cost-effectiveness), and hemp or flax fibers (for high- modulus reinforcement and low creep) may provide an optimal balance of properties for applications requiring maximum stiffness and dimensional stability, such as panels with precise coupling profiles or panels intended for heavy-traffic areas. The longer, stiffer bast or leaf fibers may form a percolated network that restricts long-term flow of the elastomer or thermoplastic elastomer matrix, helping to maintain low moisture-induced expansion and shrinkage (linear moisture expansion coefficient less than 0.015% per % moisture change and thickness swelling coefficient less than 0.6% per % moisture change).

[0034] In another embodiment, the at least one other natural particle may comprise moisture-robust fibers such as seagrass, sisal, abaca, or coir, which have waxy or hydrophobic surfaces and relatively high lignin content. These fibers may be particularly beneficial in applications where the panel will be exposed to humid environments, such as bathrooms, ground floors, or outdoor wall applications. The combination of leather fibers (for flexibility), wood or cellulose fibers (for structural reinforcement), and moisture-robust fibers (for dimensional stability in humid conditions) may provide a composite material with excellent resistance to moisture- induced dimensional changes and reduced risk of debonding or delamination between the support element and the decorative top layer. The waxy surfaces of fibers like seagrass or coir may also contribute to improved water resistance of the support element as a whole.

[0035] Optionally, the at least one other natural particle may comprise natural particle dust, such as plant dust (e.g., cotton dust), wood dust, or animal leather dust (e.g., leather buffing dust). The inclusion of fine dust particles in addition to fibers may provide several benefits. The dust particles, with their small size (typically between 0.1 and 500 microns, or between 1 and 100 microns for plant dust), may fill voids between the larger fibers and improve the packing density of the composite, contributing to higher compressive strength and better dimensional stability. The dust particles may also improve the processability of the composite material by acting as a lubricant during mixing and calendering operations, reducing the viscosity of the mixture and facilitating better dispersion of the longer fibers. In the case of leather buffing dust, the addition of this material to the rubber or thermoplastic elastomer matrix may bring improvement in mechanical properties and increase resistance to thermal ageing and crosslink density of vulcanizates. The leather buffing dust may also improve the interfacial bonding between the leather fibers and the elastomeric binder matrix, as the dust particles can act as a compatibilizer that bridges the interface between the collagen-based leather fibers and the polymer matrix.

[0036] The proportions of the three components in the natural particle mixture may be optimized based on the desired properties of the final panel. In some embodiments, the leather fibers may constitute between 20% and 60% by weight of the total natural particle content, the plant fibers (cellulose or wood fibers) may constitute between 20% and 60% by weight, and the at least one other natural particle may constitute between 10% and 40% by weight. Preferably, the three components may be present in more balanced proportions, for example with leather fibers constituting 30-40% by weight, plant fibers constituting 30-40% by weight, and the other natural particles constituting 20-30% by weight of the total natural particle content. These proportions may provide a good balance between the flexibility and damping characteristics of the leather fibers, the structural reinforcement provided by the plant fibers, and the specific benefits (such as enhanced acoustic absorption, improved moisture resistance, or better processability) provided by the third component.

[0037] The three-component natural particle system may provide improved processing characteristics compared to two-component systems. The presence of three different particle types with different sizes, aspect ratios, and surface characteristics may improve the dispersion and distribution of all components during mixing, as each component may help to break up agglomerates of the other components. This may result in a more uniform composite structure with fewer weak points and more consistent mechanical and acoustic properties. The three-component system may also provide greater flexibility in adjusting the processing parameters, as the relative proportions of the components can be varied to optimize the viscosity, flow behavior, and calendering characteristics of the mixture. This may be particularly beneficial when forming coupling profiles at the edges of the support element, as the three-component system may allow for achieving clean, precise profiles without excessive tearing or roughness.

[0038] The acoustic performance of the three-component system may be superior to two- component systems due to the creation of a more complex, multi-scale fiber network with multiple mechanisms for energy dissipation. The different fiber types may absorb and dissipate sound energy at different frequencies and through different mechanisms (viscoelastic damping, frictional losses, air flow resistance through porous structures), resulting in broadband acoustic absorption and high sound transmission loss. For example, a mixture of cotton fibers (for high-frequency absorption through their porous lumen structure and fine diameter), leather fibers (for mid-frequency absorption through viscoelastic damping of the collagen structure), and hemp or wood fibers (for low-frequency absorption through the flexing and rubbing of a stiff percolated network) may provide excellent acoustic performance across the entire frequency range of interest, easily achieving a sound absorption coefficient of at least 0.4 and sound transmission loss of at least 35 dB at frequencies of at least 250 Hz at practical support element thicknesses (2-12 mm, preferably 2-10 mm, more preferably 2-6 mm).

[0039] The fiber length ranges in the three-component system may be maintained within practical limits to ensure good processability and uniform distribution. The leather fibers may have an average length of 0.5-5 mm, the plant fibers (cellulose or wood fibers) may have an average length of 1-10 mm, and the at least one other natural fiber, if present, may have an average length tailored to its specific type (e.g., 1-5 mm for cotton fibers, 5-20 mm for hemp or flax fibers before cutting). The presence of fibers with different lengths may contribute to the formation of the multi-scale network, with shorter fibers forming finer networks and longer fibers forming coarser networks that are mechanically interlocked. The total natural particle content, including all three components, may be maintained within the preferred range of 30-50% by weight of the support element, while the weight ratio of total natural particles to binder may be maintained between 0.8 and 4, to ensure optimal mechanical properties, flexibility, and acoustic performance.

[0040] The natural particles, particularly the natural fibers, are preferably at least partially encapsulated by the binder. This encapsulation improves the overall strength and water resistance of the composite material. More in particular, this encapsulation may provide several important technical advantages that contribute to the overall performance of the composite material and the panel as a whole. The term "encapsulation" refers to the coating or surrounding of the natural particles, particularly the natural fibers, by the elastomeric or thermoplastic binder material, such that the binder forms a continuous or semi-continuous layer around at least a portion of the surface of each particle or fiber. This encapsulation may occur during the mixing process, when the natural particles are dispersed into the binder matrix, and may be enhanced by appropriate processing conditions such as temperature, mixing time, and shear forces that promote wetting of the fiber surfaces by the binder material. It should be noted that "at least partially encapsulated" means that the natural particles do not need to be completely or uniformly encapsulated along their entire surface. Partial encapsulation, where the binder coats a significant portion of each fiber surface (for example, at least 50%, preferably at least 70%, more preferably at least 80% of the fiber surface area), may be sufficient to provide good interfacial bonding, effective stress transfer, and adequate water resistance.

[0041] The encapsulation of natural fibers by the binder may significantly improve the overall strength of the composite material through several mechanisms. First, the encapsulation may enhance the interfacial bonding between the natural fibers and the binder matrix, which is critical for effective stress transfer from the matrix to the fibers under load. When a fiber is well-encapsulated by the binder, mechanical loads applied to the composite can be efficiently transferred from the binder matrix to the fiber through shear stresses at the fiber-matrix interface. This allows the high-modulus, high-strength fibers (such as hemp, flax, wood fibers, or even the collagen structure of leather fibers) to carry a significant portion of the applied load, thereby increasing the overall compressive strength, tensile strength, and tear strength of the composite. The improved interfacial bonding provided by encapsulation may contribute to achieving the target compressive strength of at least 800 kPa, and in some cases at least 900 kPa or 1000 kPa, as well as the desired tear strength range of 55-75 N / mm. Second, the encapsulation may improve the distribution of stresses within the composite material, reducing stress concentrations that could otherwise lead to premature failure. When natural fibers are well-encapsulated, the binder can effectively grip the fibers along their length, distributing applied loads more uniformly along the fiber rather than concentrating stresses at fiber ends or at poorly bonded regions. The encapsulation may also reduce the tendency for cracks to propagate along fiber-matrix interfaces, instead forcing cracks to deflect around fibers or to break through fibers, both of which require more energy and result in higher toughness and tear resistance.

[0042] The encapsulation of natural particles by the binder may also significantly improve the water resistance of the composite material. Natural fibers, particularly plant fibers with their cellulose structure, are inherently hygroscopic, meaning they have a tendency to absorb moisture from the surrounding environment. This moisture absorption can lead to several problems, including dimensional instability (swelling in the thickness direction and expansion in the plane of the panel), reduction in mechanical properties, and potential biological degradation (growth of mold or mildew). By encapsulating the natural fibers with the elastomeric or thermoplastic binder, which is typically hydrophobic or at least less hygroscopic than the natural fibers, the direct exposure of the fibers to environmental moisture may be significantly reduced. The encapsulation creates a barrier layer around each fiber that moisture must penetrate before it can be absorbed by the fiber itself. This barrier effect may slow down the rate of moisture absorption and may reduce the total amount of moisture that the fibers can absorb at equilibrium. When the encapsulation is effective, the composite material may exhibit significantly lower moisture absorption compared to unencapsulated or poorly encapsulated natural fibers, which contributes to achieving low linear moisture expansion coefficients (less than 0.015% per % moisture change) and low thickness swelling coefficients (less than 0.6% per % moisture change). The water resistance provided by encapsulation may be particularly important for the long-term dimensional stability and durability of the panel, preventing or minimizing moisture-induced dimensional changes that could otherwise lead to gaps between adjacent panels, warping, or delamination between the support element and the decorative top layer. The degree of encapsulation may be influenced by several processing parameters and material characteristics. The viscosity of the binder at the processing temperature may affect how well the binder can wet and flow around the natural particles during mixing, with lower viscosity generally promoting better wetting and more complete encapsulation. The surface characteristics of the natural fibers may also affect encapsulation, with fibers having rough, porous surfaces (such as cotton with its lumen structure, or leather fibers with their fibrous collagen structure) providing more surface area and mechanical interlocking sites for the binder, promoting better encapsulation and interfacial bonding. Optionally, the natural fibers may be treated prior to mixing with the binder to improve the encapsulation and interfacial bonding. For example, plant fibers may be subjected to alkaline treatment, which removes surface waxes and increases surface roughness, or silane coupling agents may be applied to fiber surfaces to create chemical bridges between the hydrophilic fiber surface and the hydrophobic binder matrix. For leather fibers, treatment with urea solution may neutralize the acidic nature of untreated leather and improve compatibility with the elastomeric binder, particularly rubber binders that undergo vulcanization. The mixing process itself may be optimized to promote good encapsulation, with sufficient mixing time and appropriate shear forces necessary to break up fiber bundles, disperse individual fibers throughout the binder matrix, and allow the binder to wet and flow around each fiber, while avoiding excessive mixing that could damage the fibers.

[0043] Additionally or alternatively, the natural particles may include a wide variety of plant-based fibers, such as coir, kapok, jute, flax, hemp, kenaf, ramie, sisal, abaca (manila hemp), pineapple, banana, palm, bagasse, straw, bamboo, grass, and / or seagrass particles. This variety allows for customization of the composite material's properties and the use of locally available resources.

[0044] The plant particles used in the composite material may comprise at least 60% by weight of cellulose, with a cellulose crystallinity of at least 80% by weight of the total amount of cellulose. This high cellulose content contributes to the material's strength and dimensional stability. The plant particles may comprise less than 20% by weight of lignin, which lignin is crosslinked and relatively brittle which may affect the material's properties and processing characteristics. Additionally, or alternatively, wood flour and / or wood fibers may be included as part of the natural particles, offering additional options for material composition and properties.

[0045] In a preferred embodiment, the natural particles content in the composite material is at least 30% by weight, and preferably less than 50% by weight, of the support element. This range of natural particle content may provide an optimal balance between the reinforcing effect of the natural particles and the binding and flexibility characteristics provided by the elastomeric or thermoplastic binder. At natural particle contents below 30% by weight, the composite material may not achieve sufficient mechanical strength and stiffness, and the acoustic dampening properties may be suboptimal due to insufficient fiber network formation. The multi-scale fiber network that provides both micro-scale damping (from soft, porous fibers like cotton or leather) and macro-scale reinforcement (from stiff, high-aspect-ratio fibers like hemp, flax, or wood fibers) requires a minimum fiber content to form mechanically interlocked networks at different length scales. Below 30% by weight, the fiber networks may not be sufficiently developed to provide the desired high toughness, good tear resistance (55-75 N / mm), and strong damping across a broad frequency range.

[0046] Conversely, at natural particle contents exceeding 50% by weight, the composite may become too brittle and difficult to process, and the flexibility of the support element may be compromised. Excessive fiber content may lead to fiber clumping and uneven dispersion during mixing, resulting in anisotropic properties and potential weak points in the composite. The processing window may also narrow, as high fiber contents can make the mixture too stiff and difficult to calender, cut, or profile, particularly when forming coupling profiles at the edges of the support element. Additionally, at very high fiber contents, there may be insufficient binder matrix to adequately encapsulate all the fibers, leading to poor interfacial bonding and reduced mechanical properties. The flexibility that is often important for the support element to conform to minor subfloor imperfections and to allow adjacent support elements to form-fittingly abut each other without leaving gaps may also be lost at excessive fiber contents. Within the preferred range of 30% to 50% by weight, the natural particles may provide effective reinforcement while allowing the binder to adequately encapsulate the particles and maintain the desired flexibility. This content range may enable the formation of both the dense micro-network (from short, fine fibers like cotton) and the coarser macro-network (from longer, stiffer fibers like hemp or wood fibers) that together provide the synergistic benefits of high damping, good acoustic performance, high compressive strength (at least 800 kPa), low creep, controlled moisture behavior, and good processability. The fiber content in this range may also contribute to good dimensional stability and resistance to moisture-induced expansion or contraction, as the fiber networks restrict long-term flow of the elastomer or thermoplastic elastomer matrix and help maintain low moisture expansion coefficients (less than 0.015% per % moisture change) and low thickness swelling coefficients (less than 0.6% per % moisture change).

[0047] Optionally, the natural particle content may be adjusted within this range depending on the specific type of natural particles used and the desired properties of the final panel. For example, when using relatively stiff fibers such as hemp, flax, or sisal, a lower natural particle content (e.g., 30-40% by weight) may be preferred to maintain adequate flexibility and to prevent the composite from becoming too stiff or brittle. When using softer fibers such as cotton, kapok, or leather fibers, a higher natural particle content (e.g., 40-50% by weight) may be employed to achieve the desired mechanical properties, as these softer fibers require higher loading levels to provide sufficient reinforcement. When using a mixture of soft and stiff fibers, such as cotton combined with hemp or leather fibers combined with wood fibers, the total natural particle content may be optimized to balance the contributions of both fiber types, typically falling in the middle of the range at approximately 35-45% by weight.

[0048] In some embodiments, the natural particle content may be approximately 40% by weight, which may represent an optimal balance for many fiber types and applications. This content level may ensure that the support element achieves the required compressive strength of at least 800 kPa while maintaining sufficient flexibility for easy installation and good acoustic performance. At this content level, the fiber networks may be well-developed without being so dense as to compromise processability or flexibility. The acoustic tuning provided by the multi- scale fiber network, with soft fibers providing strongly damped deformation with internal friction for excellent absorption at mid-high frequencies and stiff fibers providing a network that shifts absorption peaks into lower frequencies and improves sound transmission loss, may be optimized at this content level to reach a sound absorption coefficient of at least 0.4 and sound transmission loss of at least 35 dB at frequencies of at least 250 Hz at practical thicknesses (2-12 mm, preferably 2-10 mm, more preferably 2-6 mm).

[0049] The composite material may also include synthetic fibers, such as polyester, nylon, polypropylene, aramid, polyethylene, acrylic, carbon, glass, or polyvinyl alcohol (PVA) fibers. These synthetic fibers can be used to enhance specific properties of the composite material. Synthetic fibers that can be added to the, preferably elastomeric, matrix material of the support element, may enhance specific properties of the support element, such as tensile strength, impact resistance, durability, and dimensional stability while complementing the natural fibers. Polyester and nylon offer flexibility and resilience, polypropylene and polyethylene improve chemical resistance and lightweight characteristics, aramid fibers provide exceptional strength and heat resistance, and glass fibers enhance stiffness and thermal stability. The choice of synthetic fiber depends on the desired mechanical, thermal, and chemical properties of the composite material.

[0050] The support element may contain sulfur and zinc oxide, which can act as vulcanizing agents if rubber binders are used, improving the material's strength and durability. In vulcanization, sulfur and zinc oxide work together to enhance the crosslinking process of rubber. Sulfur is the primary vulcanizing agent, forming crosslinks between the rubber's polymer chains to improve elasticity, strength, and durability. Zinc oxide acts as an activator, reacting with accelerators and sulfur to form intermediate complexes that speed up and facilitate the crosslinking reaction. This combination ensures efficient vulcanization, resulting in a rubber material with improved mechanical properties, heat resistance, and resilience.

[0051] The composite material may include inert mineral fillers. Preferably at least one mineral filler is chosen from the group consisting of: calcium carbonate, silica, talc, kaolin, bentonite, magnesium hydroxide, alumina trihydrate, barium sulfate, mica, dolomite, wollastonite, zeolites, pumice, perlite, and vermiculite. These fillers improve mechanical properties, thermal stability, and processing characteristics, while maintaining the eco-friendly aspect of the bio-composite. The choice of filler depends on the desired properties, such as reinforcement, weight reduction, or flame resistance. Moreover, these fillers can help reduce costs of the support element and hence of the panel as such.

[0052] In a preferred embodiment, the composite material comprises at least one inert mineral filler, such as calcium carbonate and / or talc, wherein the mineral filler content in the composite material is at least 20% by weight, and preferably less than 30% by weight, of the support element. The inclusion of inert mineral fillers may provide several technical advantages to the composite material. Mineral fillers such as calcium carbonate or talc may improve the dimensional stability of the support element by reducing the overall coefficient of thermal expansion and moisture expansion of the composite. These fillers, being inorganic and non- hygroscopic, do not respond to moisture changes in the same way as natural fibers, and their presence may help to stabilize the composite and reduce moisture- induced dimensional changes. This contributes to achieving low linear moisture expansion coefficients (less than 0.015% per % moisture change) and low thickness swelling coefficients (less than 0.6% per % moisture change).

[0053] Mineral fillers may also enhance the compressive strength and stiffness of the support element, contributing to its ability to support the rigid decorative top layer without excessive deformation under load. The hard, incompressible nature of mineral particles provides load-bearing capacity that complements the reinforcement provided by the natural fiber networks. This helps achieve compressive strength of at least 800 kPa, and in some cases at least 900 kPa or 1000 kPa, while maintaining the desired Shore A hardness range of 45-90. The mineral fillers may also help to maintain the high density of the support element (at least 1000 kg / m3, preferably at least 1100 kg / m3, more preferably at least 1200 kg / m3), which is important for achieving good sound transmission loss (at least 35 dB at frequencies of at least 250 Hz). The high density provided by mineral fillers, combined with the controlled microporosity introduced by natural fibers (particularly porous fibers like cotton with its lumen structure), allows the composite to achieve good acoustic absorption (sound absorption coefficient of at least 0.4) while still maintaining high sound transmission loss. Additionally, mineral fillers may improve the processability of the composite material during manufacturing by adjusting the viscosity and flow characteristics of the mixture. The presence of mineral fillers may reduce the stickiness of the elastomeric binder and may facilitate mixing, calendering, cutting, and profiling operations. The mineral particles may act as internal lubricants during processing, reducing friction and heat generation during mixing and improving the surface finish of the final support element. This is particularly beneficial when forming coupling profiles at the edges of the support element, as the mineral fillers may help to achieve clean, precise profiles without excessive tearing or roughness. The use of mineral fillers may also provide economic benefits by reducing the overall cost of the support element, as these materials are typically less expensive than the elastomeric binders and natural fibers.

[0054] At filler contents of at least 20% by weight, these benefits may be realized without significantly compromising the flexibility and acoustic properties of the support element. The mineral fillers at this content level may provide sufficient reinforcement and dimensional stability while still allowing the natural fiber networks (both the dense micro-network from soft fibers and the coarser macro-network from stiff fibers) to function effectively in providing damping and acoustic absorption. At filler contents exceeding 30% by weight, the composite may become too rigid and the acoustic dampening performance may be reduced. Excessive mineral filler content may interfere with the formation and function of the fiber networks, reducing the internal friction and viscoelastic losses that are often important for good acoustic absorption. The flexibility of the support element may also be compromised at very high mineral filler contents, making it more difficult for the panel to conform to minor subfloor imperfections and potentially leading to gaps between adjacent panels that could form acoustic bridges.

[0055] Optionally, the mineral filler may be surface-treated to improve its compatibility with the elastomeric binder and enhance the interfacial bonding. For example, calcium carbonate may be treated with stearic acid or other coupling agents to improve dispersion and reduce agglomeration. Surface treatment may also improve the interaction between the mineral fillers and the natural fibers, potentially enhancing the overall mechanical properties of the composite. Alternatively, other inert mineral fillers may be used, such as silica, kaolin, bentonite, magnesium hydroxide, alumina trihydrate, barium sulfate, mica, dolomite, wollastonite, zeolites, pumice, perlite, or vermiculite, each of which may provide specific benefits depending on the desired properties of the final panel. For example, magnesium hydroxide or alumina trihydrate may provide flame retardancy in addition to reinforcement, which may be beneficial for certain applications. Mica or talc may provide particularly good dimensional stability and low moisture expansion. In some embodiments, a combination of two or more mineral fillers may be used to achieve a synergistic effect on the composite properties. For example, a combination of calcium carbonate (for cost-effectiveness and good dispersion) with talc (for dimensional stability and processing benefits) may provide an optimal balance of properties.

[0056] The weight ratio of natural particles to binder in the support element is designed to be at least 0.25, preferably at least 0.8, more preferably at least 1 , and preferably less than 4. This ratio ensures an optimal balance between the natural particles and the binder for strength and flexibility. For example, a ratio falling within this ratio range typically yields to relatively good mechanical properties such as tensile strength, tear strength, and hardness. At a ratio of 1 (+ / - 0.2), it was found that the composite achieves a relatively good balance between the mechanical reinforcement provided by the natural fibers, in particular leather fibers, and the elasticity and flexibility of the elastomeric matrix, in particular rubber matrix, of the support element. Ratios higher than 4 typically leads to a decrease in mechanical properties due to fiber aggregation and reduced flexibility of the rubber chain

[0057] At least a fraction of the natural particles may be porous, which can contribute to the material's acoustic properties and moisture regulation capabilities. Porous fibers in a bio-composite material of the support element enhance acoustic dampening by effectively absorbing and dissipating sound energy. Their porous structure provides pathways for sound waves to enter, trapping and converting their energy into heat through friction and thermal dissipation. The increased surface area and air pockets of porous fibers improve interaction with sound waves, reducing reflection and reverberation across a broad frequency range. Additionally, their acoustic impedance, closer to that of air, allows sound to penetrate rather than reflect, further improving absorption. Examples of porous natural fibers are: cotton fibers, coir fibers, kapok fibers, hemp fibers, jute fibers, flax fibers, sisal fibers, abaca fibers, wool fibers, kenaf fibers, bamboo fibers, palm fibers, and leather fibers.

[0058] In a preferred embodiment, the binder content in the composite material is at least 20% by weight, and preferably less than 60% by weight, of the support element. The binder preferably comprises a natural binder, such as natural rubber (latex), which may be derived from the sap of rubber trees (Hevea brasiliensis). Natural rubber provides excellent elasticity, flexibility, and binding properties, making it particularly well-suited as a matrix material for encapsulating natural particles and forming the multi-scale fiber networks that provide the synergistic benefits of high damping, good acoustic performance, high compressive strength, low creep, and controlled moisture behavior. The use of natural rubber as the binder may contribute to creating an essentially fully natural composite material that is completely biobased. This provides significant environmental benefits including renewability, biodegradability at end-of-life, and a reduced carbon footprint compared to synthetic polymer-based composites.

[0059] Other examples of natural binders that may be used in the composite material include natural latex from other plant sources, such as guayule latex (from Parthenium argentatum), which provides similar properties to Hevea natural rubber and can be cultivated in arid regions. Additionally, plant-based resins and oils may be used as natural binders, including castor oil-based polyurethanes, which are derived from castor beans and can be formulated to provide elastomeric properties suitable for the support element. Soy-based polyols and resins, derived from soybean oil, may also be used as natural binders, either alone or in combination with other natural binders. Tung oil, linseed oil, and other drying oils, which can polymerize and crosslink upon exposure to air, may serve as natural binders, particularly when combined with natural crosslinking agents. Natural polysaccharides such as starch-based binders, cellulose derivatives, or chitosan (derived from crustacean shells) may also be employed, although these may be more suitable in combination with more elastomeric natural binders to achieve the desired flexibility. Protein-based binders, such as soy protein isolate, wheat gluten, or casein (milk protein), may also be used as natural binders, particularly when chemically modified or crosslinked to improve their water resistance and mechanical properties. Natural waxes, such as carnauba wax or beeswax, may be incorporated as co-binders or processing aids to improve the water resistance and processability of the composite material.

[0060] The application of a natural binder, particularly natural rubber, preferably leads to an essentially fully natural composite material that is completely biobased. When natural rubber is combined with natural particles (such as cotton fibers, hemp fibers, wood fibers, leather fibers, or other plant or animal-derived particles), natural mineral fillers (such as calcium carbonate, which is naturally occurring chalk or limestone, or talc, which is a naturally occurring mineral), and natural processing aids and crosslinking agents (such as sulfur, which is a naturally occurring element, and zinc oxide, which can be derived from natural zinc ores), the resulting composite material may be composed entirely or almost entirely of renewable, biobased materials. This essentially fully natural composition may provide several important advantages. First, it may significantly reduce the environmental impact of the panel compared to panels using synthetic polymers, synthetic fibers, or other petroleum-derived materials. The biobased composite material may have a much lower carbon footprint, as the natural materials sequester carbon during their growth (in the case of plant fibers and natural rubber) rather than releasing fossil carbon (as would occur with petroleum-based synthetic polymers). Second, the fully natural composition may improve the end-of-life options for the panel, as the biobased materials are generally biodegradable or compostable under appropriate conditions, or can be incinerated for energy recovery with lower emissions of harmful substances compared to synthetic polymers. Third, the use of natural materials may appeal to environmentally conscious consumers and may help the panel meet green building standards and certifications, such as LEED, BREEAM, or Cradle-to-Cradle certification.

[0061] The binder, whether natural rubber or another natural binder, serves as the matrix material that holds the natural particles and mineral fillers together and provides the composite with its flexibility and resilience. The binder matrix is often important for encapsulating the natural fibers and enabling the formation of the multi-scale fiber networks that provide the synergistic benefits described elsewhere in this application. At binder contents of at least 20% by weight, there may be sufficient matrix material to adequately encapsulate the natural particles and mineral fillers, ensuring good interfacial bonding and effective stress transfer between the components. This minimum binder content may ensure that both the dense micronetwork (formed by short, fine fibers like cotton or leather fibers) and the coarser macro-network (formed by longer, stiffer fibers like hemp, flax, or wood fibers) are properly embedded in the matrix and can function effectively. The binder provides the continuous phase that allows the fiber networks to move, bend, and rub against each other under dynamic loading, creating the viscoelastic and frictional losses that are often important for acoustic dampening. Without sufficient binder content, the fibers may not be adequately bonded together, leading to poor mechanical properties and reduced acoustic performance. The minimum binder content of 20% by weight may also ensure that the composite material maintains adequate flexibility and can accommodate minor subfloor imperfections during installation, allowing adjacent support elements to form-fittingly abut each other without leaving gaps that could form acoustic bridges.

[0062] At binder contents exceeding 60% by weight, the composite may become too soft and may not achieve the required compressive strength of at least 800 kPa. Excessive binder content may result in insufficient reinforcement from the natural fibers and mineral fillers, as the fiber networks may be too dilute to provide effective load-bearing capacity and dimensional stability. The composite may exhibit excessive creep under sustained loading, and the dimensional stability may be compromised due to the higher coefficient of thermal expansion and moisture expansion of the binder compared to the fibers and mineral fillers. Additionally, higher binder contents may increase the cost of the support element, as natural rubber and other high-quality natural binders are typically more expensive than natural fibers and mineral fillers. The environmental benefits associated with using high proportions of natural fibers and other natural particles may also be reduced at very high binder contents, even when using natural binders, as the production and processing of natural rubber or other natural binders still requires energy and resources.

[0063] Within the preferred range of 20% to 60% by weight, the binder content may be optimized based on the specific type of binder used, the nature and content of the natural particles, and the desired properties of the final panel. Optionally, when using natural rubber as the binder, the binder content may be maintained at the lower end of this range (e.g., 20-40% by weight) due to the excellent binding properties and flexibility of natural rubber. Natural rubber provides high elasticity and good interfacial bonding with natural fibers, allowing effective encapsulation and stress transfer at relatively low binder contents. This is particularly advantageous for creating an essentially fully natural composite material, as it allows for higher proportions of natural fibers and other natural particles, maximizing the biobased content and the environmental benefits. When using other natural binders, such as plant-based polyurethanes or protein-based binders, a higher binder content (e.g., 40-60% by weight) may be preferred to achieve comparable performance, as these materials may have somewhat lower binding efficiency or flexibility compared to natural rubber. When using synthetic elastomers or thermoplastic elastomers (which would result in a composite that is not fully natural), a higher binder content (e.g., 40-60% by weight) may also be preferred to achieve comparable performance.

[0064] In some embodiments, the binder content may be approximately 30-40% by weight, which may provide an optimal balance between mechanical properties, flexibility, and cost-effectiveness, while still maintaining a high proportion of natural particles to maximize the biobased content of the composite. This binder content range may facilitate the formation of a continuous matrix phase that effectively encapsulates the natural particles and mineral fillers while still allowing high enough filler and fiber contents to achieve the desired compressive strength (at least 800 kPa), density (at least 1000 kg / m3), and acoustic properties (sound absorption coefficient of at least 0.4 and sound transmission loss of at least 35 dB at frequencies of at least 250 Hz). At this binder content level, the multi-scale fiber networks may be well-developed, with the soft fibers (cotton or leather) forming a dense micronetwork for damping and the stiff fibers (hemp, flax, wood fibers) forming a coarser macro-network for reinforcement, while the binder matrix allows these networks to function synergistically. This binder content range may also contribute to the water resistance and dimensional stability of the support element, as the binder encapsulates the natural fibers and reduces their direct exposure to moisture, helping to achieve low linear moisture expansion coefficients (less than 0.015% per % moisture change) and low thickness swelling coefficients (less than 0.6% per % moisture change). When natural rubber is used as the binder, its inherent hydrophobicity may further enhance the water resistance of the composite material, protecting the natural fibers from moisture absorption and contributing to the longterm dimensional stability and durability of the panel.

[0065] The water content (moisture content) in the support element is typically limited and less than 10% by weight, preferably 5% or less by weight of the composite material of the support element, such as 3% or 4% by weight of the composite material of the support element. Having some moisture in a composite material made of an elastomeric matrix filled with natural fillers (like plant or leather fibers) can improve flexibility, toughness, and processing. Moisture acts as a plasticizer, enhancing the elasticity of the natural fibers by increasing their molecular mobility, which helps distribute stresses more evenly in the composite. It can also improve fiber-matrix adhesion by slightly swelling the fibers, allowing better mechanical interlocking. Furthermore, during manufacturing, controlled moisture levels can aid in reducing brittleness of natural fillers, improving their dispersion within the elastomeric matrix. However, excessive moisture (> 10% by weight) should be avoided as it may cause voids, hydrolysis, or long-term degradation in some cases.

[0066] In a preferred embodiment, the water content of the composite material exceeds a nominal equilibrium moisture content of the natural particles. The nominal equilibrium moisture content refers to the moisture content that the natural particles would naturally attain when exposed to standard atmospheric conditions (typically around 20°C and 65% relative humidity). For most natural fibers, this equilibrium moisture content ranges from approximately 5% to 12% by weight, depending on the specific fiber type. Cotton fibers typically have an equilibrium moisture content of around 7-8%, hemp fibers around 8-10%, wood fibers around 8-12%, and leather fibers around 10-14%. By maintaining a water content in the composite material that exceeds this nominal equilibrium level, several technical advantages may be achieved. The water in the composite material may be present in various forms and locations: it may be present in between fibers as free water dispersed throughout the composite material, it may be present as surface moisture on the fibers and other particles, and at least one fraction of the water content may also be absorbed by the natural fibers themselves, leading to a higher water content in the fibers than their natural equilibrium water content. This water is typically added during production of the composite material, either intentionally as part of the formulation or as residual water that remains in the composite after processing, and is therefore residual water that is retained in the final support element rather than water absorbed from the environment after manufacturing.

[0067] The additional moisture may act as a plasticizer for the natural particles, particularly for the natural fibers, thereby increasing their flexibility and reducing their brittleness. This plasticizing effect occurs because water molecules interact with the cellulose or collagen structures in the natural particles, inserting themselves between the polymer chains and increasing their molecular mobility. This effectively reduces the glass transition temperature of the natural fibers, making them more flexible and less prone to cracking or breaking under stress. For cotton fibers, which form the dense micro-network that provides damping and acoustic absorption, this increased flexibility may enhance their ability to move, bend, and rub against the matrix and each other under dynamic loading, thereby improving the viscoelastic and frictional losses that contribute to good sound absorption. For stiffer fibers like hemp, flax, or wood fibers, which form the coarser macro-network that provides reinforcement, the plasticizing effect may reduce the risk of fiber fracture during processing and use, improving the overall toughness and tear resistance of the composite. The water present in between fibers may also act as a lubricant during processing, facilitating the movement and rearrangement of fibers during mixing, calendering, and other forming operations, which may contribute to better fiber dispersion and more uniform composite properties.

[0068] The presence of controlled moisture may also enhance the interfacial bonding between the natural particles and the elastomeric binder by promoting better wetting and mechanical interlocking. Moisture on the fiber surfaces may improve the initial contact between the fibers and the binder during mixing, allowing the binder to more effectively penetrate into surface irregularities and pores in the fibers. This may result in stronger interfacial adhesion and more effective stress transfer between the fiber networks and the binder matrix, contributing to higher compressive strength (at least 800 kPa) and tear strength (55-75 N / mm). Furthermore, the additional moisture may improve the processability of the composite material during manufacturing by reducing the viscosity of the mixture and facilitating better dispersion of the natural particles throughout the binder matrix. This may be particularly beneficial when processing mixtures of different fiber types, such as cotton combined with hemp or leather fibers combined with wood fibers, as the moisture may help to break up fiber bundles and achieve more uniform distribution of both the soft, fine fibers and the stiff, coarse fibers. The residual water that remains in the composite after production may be controlled through appropriate drying or conditioning steps, where the composite is partially dried to remove excess water while retaining sufficient moisture to provide the plasticizing and processing benefits described above.

[0069] Optionally, the water content may be controlled to be between 1 % and 3% above the nominal equilibrium moisture content of the natural particles, which may provide the plasticizing benefits without introducing excessive moisture that could lead to dimensional instability or degradation over time. For example, if the natural fibers in the composite have a nominal equilibrium moisture content of 8%, the actual water content in the composite material may be maintained at 9-11%. This controlled excess moisture may optimize the balance between flexibility, processability, and dimensional stability. In some embodiments, the total water content in the composite material may be maintained between 6% and 9% by weight of the support element, which may represent an optimal balance for many natural fiber types. This range may provide sufficient moisture to achieve the plasticizing and processing benefits while remaining well below the 10% by weight threshold above which potential issues with hydrolysis, void formation, or long-term degradation of the composite material may arise. It may be important to note that while the water content exceeds the nominal equilibrium moisture content, it preferably remains below 10% by weight of the support element to avoid potential issues. Excessive moisture may lead to dimensional instability, as the composite material may be more susceptible to swelling and shrinkage in response to environmental humidity changes, potentially compromising the achievement of low linear moisture expansion coefficients (less than 0.015% per % moisture change) and low thickness swelling coefficients (less than 0.6% per % moisture change). High moisture levels may also promote the growth of mold or mildew, particularly in humid environments, which could compromise the hygiene and durability of the panel. Furthermore, excessive water content may interfere with the curing or crosslinking of the elastomeric binder (particularly when using rubber binders with sulfur and zinc oxide vulcanization systems), potentially reducing the mechanical properties of the composite. The controlled water content that exceeds the nominal equilibrium moisture content but remains below 10% by weight may therefore represent an optimal balance that enhances flexibility, processability, and interfacial bonding while maintaining dimensional stability, durability, and resistance to biological degradation. The residual water from production may be maintained at this optimal level through careful control of the manufacturing process, including the initial water content of the raw materials (particularly the natural fibers, which may be supplied with varying moisture contents), any water added during mixing or processing, and the drying or conditioning steps applied to the composite material before or after forming the support element.

[0070] The support element may be provided with flexible, preferably vertical, side edges. This feature can facilitate easier installation and improve water resistance at tight / closed panel joints.

[0071] The support element may be oversized and / or offset with respect to the decorative top layer, extending beyond at least two side edges, preferably each side edge of the decorative top layer. This oversize and / or offset allows for easier alignment and connection of adjacent panels during installation, and moreover to the formation of grout lines (grout channels) which can be filled with grout mortar.

[0072] The decorative top structure may be adhered to the support element using at least one adhesive layer, particularly a flexible adhesive layer. This flexibility in the adhesive layer can help accommodate any differences in thermal expansion or contraction between the support element and the top layer. The adhesive layer may comprise a water-based adhesive having a viscosity below 50 Pa s at (an application temperature being) room temperature, or a hot melt adhesive, such as a PU hot melt adhesive, having a viscosity below 10 Pa s at a(n application) temperature between 120 and 180 °C. These viscosity ranges allow for effective application and penetration of the adhesive. Hence, the adhesive layer may penetrate into the support element and / or the decorative top layer, enhancing the bond strength between the layers. Preferably a flexible adhesive layer is used. This flexibility is important in particular in case the support element and the top layer have different coefficients of thermal expansion or respond differently to changes in humidity. By using a flexible adhesive layer, the panel can accommodate these differences without causing stress or potential separation between the layers. In some embodiments, the adhesive layer is a hot melt adhesive layer. Hot melt adhesives offer several advantages in this application. They can be quickly applied and set, which can speed up the manufacturing process. They also typically provide strong initial tack, which helps hold the layers together during the rest of the manufacturing process. Hot melt adhesives can be formulated to maintain flexibility after cooling, which aligns with the need for a flexible adhesive layer in this panel design.

[0073] The support element as defined above is typically relatively waterproof, and as the support element is affixed to the typically also waterproof top layer, it is strongly preferred that the coefficients of moisture expansion (CME) of both layers are in the same order of magnitude, and / or preferably aligned with each other. In case these CMEs of both layers mutually strongly differ delamination of damaging of the panels as such could easily occur. Expansion properties (linear expansion and contraction in the plane of the panel) and swelling properties (thickness swelling and shrinkage in a direction perpendicular to the plane of the panel) are commonly key parameters in the dimensional stability of the individual layers and of the panel according to the invention as such. Linear expansion values are typically considerably smaller than thickness swelling value. Particularly, linear expansion is considered as the control factor in qualifying the behaviour of the individual layers and of the panel as such when exposed to moisture. The hygroscopic linear expansion of the individual panel layers, in the plane of the panel, is of practical importance for using the panels to create a durably stable floor or wall covering. A flexible adhesive is preferably used to compensate differences in CME.

[0074] The top layer is typically not, or practically not, susceptible for expansion or contraction due to moisture changes in the direct environment. Hence, the CME of the top layer is typically zero or very close to zero. It is therefore advantageous in case the support element has a linear moisture expansion coefficient of less than 0.015% per % moisture change of the support element. This means that the expansion of the support element in the plane of the panel is less than 0.15 mm per m length of the support element in case the moisture content of the support element is changing, typically increasing, with 1 %. Preferably, the support element has a first linear moisture expansion coefficient, and wherein the top layer has second linear moisture expansion coefficient, wherein the difference between the first linear moisture expansion coefficient and the second linear moisture expansion coefficient is less than 0.015% per % moisture change. Preferably, the support element has a linear moisture contraction coefficient of less than 0.025% per % moisture change of the support element. This means that the contraction (shrinkage) of the support element in the plane of the panel is less than 0.25 mm per m length of the support element in case the moisture content of the support element is changing, typically decreasing, with 1 %. Preferably, the support element has a first linear moisture contraction coefficient, and wherein the top layer has second linear moisture contraction coefficient, wherein the difference between the first linear moisture contraction coefficient and the second linear moisture contraction coefficient is less than 0.025 % per % moisture change.

[0075] In a preferred embodiment, the support element has a thickness swelling coefficient of less than 0.6% per % moisture change of the support element. This means that the expansion of the support element, in a direction perpendicular to the plane of the panel, is less than 0.0006 mm per mm thickness of the support element in case the moisture content of the support element is changing, typically increasing, with 1 %. Preferably, the support element has a first thickness swelling coefficient, and wherein the top layer has second thickness swelling coefficient, wherein the difference between the first thickness swelling coefficient and the second thickness swelling coefficient is less than 0.6% per % moisture change. Preferably, the support element has a thickness shrinkage coefficient of less than 0.5% per % moisture change of the support element. This means that the thickness reduction of the support element is less than 0.0005 mm per mm thickness of the support element in case the moisture content of the support element is changing, typically decreasing, with 1%. Preferably, the support element has a first thickness shrinkage coefficient, and wherein the top layer has a second thickness shrinkage coefficient, wherein the difference between the first thickness shrinkage coefficient and the second thickness shrinkage coefficient is less than 0.5% per % moisture change. Both for the top layer and for the support element, the moisture expansion can be determined by applying the test described in ISO 10545. The above moisture-related properties ensure that the panel remains stable and flat under varying humidity conditions, reducing the risk of warping, separation, or gap formation. The support element may have a density of at least 1000 kg / m3, preferably at least 1100 kg / m3, more preferably at least 1200 kg / m3. This relatively high density contributes to the panel's stability and sound insulation properties. The support element may consist of a single material layer, simplifying manufacturing and ensuring uniform properties throughout its thickness. The support element may have a thickness between 2 and 12 mm, preferably between 2 and 10 mm, more preferably between 2 and 6 mm. This range of thicknesses provides adequate strength and sound insulation while maintaining a relatively low profile.

[0076] The support element may be designed either with or without interconnecting coupling profiles for joining adjacent panels. When present, these profiles may lock the panels in horizontal and / or vertical direction. To this end preferably at least one pair of opposed side edges of the support element is provided with interconnecting coupling means for interconnecting adjacent panels. This enables easier constructing of a floor or wall covering of a plurality of panels according to the present invention. Partly because of the relatively high density of the support element, it is possible to provide the side edges of the support element with interconnecting coupling means. Non-limiting examples of possible interconnecting coupling means are described hereinafter. It is for example conceivable that the support element is provided with complementary coupling means, such as a tongue and groove. The tongue and groove may e.g. be coupled by means of a horizontal movement and / or vertical movement and / or angling movement (turning movement). In a more specific embodiment, the interconnecting coupling means may e.g. include respectively a first and a second coupling profile at a respective first and second side edge of the pair of side edges, wherein the first coupling profile comprises:

[0077] • an upward tongue,

[0078] • at least one upward flank lying at a distance from the upward tongue,

[0079] • an upward groove formed in between the upward tongue and the upward flank wherein the upward groove is adapted to receive at least a part of a downward tongue of a second coupling profile of another, identical panel, and

[0080] • at least one first locking element, preferably provided at a distant side of the upward tongue facing away from the upward flank, and wherein the second coupling profile comprises:

[0081] • a first downward tongue, • at least one first downward flank lying at a distance from the downward tongue,

[0082] • a first downward groove formed in between the downward tongue and the downward flank, wherein the downward groove is adapted to receive at least a part of an upward tongue of a first coupling profile of another, identical panel, and

[0083] • at least one second locking element adapted for co-action with a first locking element of the other identical panel, said second locking element preferably being provided at the downward flank.

[0084] Preferably, the first coupling profile and the second coupling profile are configured such that the first and second coupling profiles of two identical panels can be coupled to each other by means of a lowering or vertical movement, which involves at least a part of the downward tongue of a first panel being inserted into the upward groove of the other identical panel, and wherein at least a part of the upward tongue of the other panel is inserted into the downward groove of the first panel. An inside of the upward tongue (facing the upward flank) and the inside of the downward tongue (facing the downward flank) may be in contact in coupled condition, to transfer forces between them, in particular from the upward tongue to the downward tongue. The insides of the tongues may be in contact at tongue contact surfaces, wherein the tongue contact surfaces may be inclined. The inclination may be such that a portion of the inside of the upward tongue is inclined towards the flank, such that a tangent line from the tongue contact surface intersects with the inner vertical plane above the tongue contact surface.

[0085] Alternatively the inclination may be such that a portion of the inside of the tongue is inclined away from the upward flank, such that a tangent line from the tongue contact surface intersects with the inner vertical plane below the tongue contact surface. These are closed groove and open groove systems respectively. Closed groove systems provide for an improved (drop-)locking, but are more difficult to couple, whereas open groove systems are easier to couple but do not provide the additional vertical locking of a closed groove system.

[0086] Furthermore, in the panel according to the invention, the panel may comprise at least one third coupling profile and at least one fourth coupling profile located respectively at a third panel edge and a fourth panel edge, wherein the third coupling profile comprises: • a sideward tongue extending in a direction substantially parallel to the upper side of the panel,

[0087] • at least one second downward flank lying at a distance from the sideward tongue, and

[0088] • a second downward groove formed between the sideward tongue and the second downward flank, wherein the fourth coupling profile comprises:

[0089] • a third groove configured for accommodating at least a part of the sideward tongue of the third coupling profile of a second identical 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 the third and fourth coupling profiles of two identical panels can be coupled to each other by means of a turning movement, which involves at least a part of the sideward tongue of a first panel being inserted into the third groove of the other identical panel, and wherein at least a part of the upward locking element of the other panel is inserted into the second downward groove of the first panel.

[0090] Preferably, the panel comprises, at a first pair of opposed side edges, a first and a second coupling profile, wherein the first coupling profile and the second coupling profile are configured such that the first and second coupling profiles of two identical panels can be coupled to each other by means of a vertical movement, and wherein the panel comprises, at a second pair of opposed edges, a third coupling profile and a fourth coupling profile, wherein the third coupling profile and the fourth coupling profile are configured such that the third and fourth coupling profiles of two identical panels can be coupled to each other by means of a turning movement.

[0091] An exposed upper surface and / or the entire upper surface of the support element may be provided with a coating, preferably comprising at least one silane coupling agent. Coating a bio-composite surface of the support element with silane coupling agents, such as APTES, GPTMS, VTMS, MPTS, or OTES, significantly enhances the bonding of grout mortar by improving interfacial adhesion through chemical bonding between the organic bio-composite and inorganic grout. Moreover, the use of silane coupling agents in between the support element and the top layer can significantly improve the adhesion between the support element and the top layer. These agents also provide hydrophobic properties, reducing water absorption and preventing moisture-related degradation, while reactive functional groups increase compatibility with cementitious materials. Additionally, the treatment improves durability, mechanical performance, and resistance to environmental factors like temperature fluctuations and chemicals, ensuring a robust and long-lasting grout layer on the bio-composite surface. Additionally or alternatively to silane coupling agents, other options for enhancing adhesion between a bio-composite surface and grout mortar include epoxy-based coatings, polyurethane (PU) coatings, and acrylic primers, which provide strong bonding and chemical resistance. Phosphate-based treatments and latex or styrene-butadiene rubber (SBR) primers improve adhesion and flexibility, while mechanical surface treatments like sandblasting or etching create textures for mechanical interlocking. Advanced methods such as plasma or corona treatment modify surface energy, and nanoparticle-based coatings enhance roughness and chemical compatibility. Organic acid treatments, like citric acid, and polyvinyl alcohol (PVA) coatings also offer effective alternatives, promoting better adhesion and moisture resistance. These approaches can be tailored to optimize bonding strength, durability, and environmental resistance.

[0092] The panel is designed to have good acoustic properties, with a sound absorption coefficient (a) of at least 0.4 and a sound transmission loss (STL) of at least 35 dB at sound frequencies of at least 250 Hz. A sound absorption coefficient of 0.4 ensures that the panel absorbs at least 40% of incident sound energy, reducing reverberation and improving acoustic comfort in enclosed spaces. The high STL of 35 dB minimizes the transmission of sound through the panel, significantly reducing noise transfer between rooms or floors. This property is particularly important for reducing the transmission of speech and other common indoor sounds between rooms or between floors in a building. These characteristics make the panel particularly suitable for multi-story buildings or noise-sensitive areas, such as offices, residential complexes, or hospitals, where controlling sound reflections and isolating noise are critical for comfort, productivity, and privacy. Additionally, these properties contribute to compliance with building standards for noise control, enhancing the overall value and functionality of the construction. The top layer may have a thickness between 2 and 20 mm, preferably between 2.5 and 10 mm, more preferably between 3 and 6 mm. This range of thicknesses allows for durability of the decorative surface while maintaining compatibility with various installation methods.

[0093] The top layer, which provides the decorative surface of the panel, has a thickness between 2 and 20 mm, preferably between 2.5 and 10 mm, more preferably between 3 and 6 mm. This range of thicknesses allows for a balance between durability and weight. The thicker end of this range provides excellent durability and can withstand heavy wear, making it suitable for high-traffic commercial applications. The thinner end of the range reduces the overall weight of the panel, which can be beneficial for easier handling and installation, and may be suitable for residential or light commercial use.

[0094] These features work together to create a panel that not only provides the aesthetic appeal of ceramic or stone, but also offers improved acoustic performance, durability, and ease of installation compared to traditional tile or stone flooring. The combination of the flexible, sound-absorbing support element with the durable top layer, all held together with a flexible adhesive, results in a product that can meet the demands of modem construction while providing comfort and style to the end user.

[0095] The compressive strength of the support element is measured by determining the maximum compressive load a material can withstand before failing. The procedure typically involves applying a compressive force to a test specimen under controlled conditions using a universal testing machine (UTM). To measure compressive strength, a test specimen (e.g., cube, cylinder, or prism) is prepared according to standardized dimensions and surface conditions. The specimen is placed in a universal testing machine (UTM), and a compressive force is gradually applied at a controlled rate until failure occurs. The maximum load (Pmax) is recorded, and the compressive strength (fc) is calculated using the formula fc= Pmax l A, where A is the cross-sectional area of the specimen. Multiple specimens are tested to ensure reliability, and the average strength is reported. This method is guided by standards such as ISO 604, ASTM D695, ISO 14126 and / or ASTM D3410. The invention also relates to a support element for intended use and / or the use of such a support element in a panel according to the invention.

[0096] The invention further relates to a system for constructing a floor or wall covering comprises a plurality of panels according to the invention, wherein adjacent support elements abut each other, and wherein adjacent support elements are preferably mechanically connected to each other. Preferably, the support element of each panel is oversized with respect to the decorative top layer of said panel, such that gaps are formed in between adjacent decorative top structures of the system, wherein said gaps are preferably at least partially filled by means of a grout material.

[0097] The support element according to the invention may be manufactured using various processing methods that are adapted to the specific binder system and natural particle composition. In a preferred embodiment, the manufacturing process comprises several steps that ensure good dispersion of the natural particles, adequate encapsulation by the binder, and optimal mechanical and acoustic properties of the final composite material. The process may begin with preparation of the natural particles, particularly the natural fibers, which may include cleaning, cutting to desired lengths, and optionally treating the fibers to improve their compatibility with the binder. For example, plant fibers may be subjected to alkaline treatment to remove surface waxes and increase surface roughness, or may be treated with silane coupling agents to improve interfacial bonding with the binder. Leather fibers, if used, may be treated with urea solution to neutralize their acidic nature and improve compatibility with elastomeric binders, particularly rubber binders that undergo vulcanization, without destroying the collagen structure as more alkaline treatments such as sodium hydroxide might do.

[0098] The mixing process is a critical step in manufacturing the support element. In a preferred embodiment, the binder (such as natural rubber or thermoplastic elastomer) is first softened or melted, either by heating (for thermoplastic binders) or by mechanical working (for rubber binders), to reduce its viscosity and facilitate incorporation of the natural particles. The natural particles, particularly the natural fibers, are then gradually added to the binder while mixing continues. The mixing may be performed in internal mixers (such as Banbury mixers), on open mills (two- roll mills), or in continuous mixing equipment, depending on the scale of production and the specific material characteristics. Sufficient mixing time and appropriate shear forces are applied to break up fiber bundles, disperse individual fibers throughout the binder matrix, and allow the binder to wet and flow around each fiber to achieve the desired encapsulation. The mixing conditions are particularly important when combining different fiber types, such as cotton with hemp or leather fibers with wood fibers, as the different fiber characteristics (length, stiffness, surface properties) require careful control to achieve uniform distribution of both the soft, fine fibers and the stiff, coarse fibers throughout the matrix. However, excessive mixing time or too high shear forces are avoided to prevent damage to the fibers, which could reduce their reinforcing effectiveness and compromise the formation of the multi-scale fiber networks that provide the synergistic benefits of high damping, good acoustic performance, and high compressive strength.

[0099] The mixing temperature may be controlled to optimize the viscosity of the binder for good fiber wetting while avoiding degradation of the natural particles or premature crosslinking of the binder. For rubber-based systems, particularly natural rubber systems, mixing temperatures typically range from 40°C to 120°C, with lower temperatures (40-80°C) used for the initial incorporation of fibers to avoid premature vulcanization, and higher temperatures (80-120°C) potentially used for subsequent mixing stages to improve dispersion and encapsulation. For thermoplastic systems, temperatures may range from 120°C to 200°C depending on the specific thermoplastic material used, with the temperature selected to provide adequate fluidity for fiber incorporation while remaining below the degradation temperature of the natural fibers. Water content in the composite may be controlled during mixing, either by using natural fibers with a controlled initial moisture content, by adding water during mixing to achieve the desired plasticizing effect, or by controlling the drying conditions after mixing. The water content is preferably maintained to exceed the nominal equilibrium moisture content of the natural particles, as this provides plasticizing benefits that enhance flexibility and processability, while remaining below 10% by weight to avoid dimensional instability or interference with crosslinking reactions.

[0100] After the natural fibers are incorporated and well-dispersed, mineral fillers (such as calcium carbonate or talc) may be added and mixed until uniformly distributed throughout the composite. The mineral fillers, which preferably constitute 20-30% by weight of the support element, contribute to dimensional stability, compressive strength, and density while also improving processability by reducing stickiness of the elastomeric binder. For rubber-based systems, crosslinking agents (such as sulfur and zinc oxide) and accelerators are typically added in a final mixing step at lower temperatures (typically 40-80°C) to avoid premature vulcanization during mixing. The mixed composite material is then formed into sheets or panels using calendering, compression molding, or extrusion processes. In calendering, the mixed material is passed through a series of heated rollers that progressively reduce the thickness and improve the uniformity of the sheet. The calendering temperature and roller gap settings are controlled to achieve the desired thickness (typically 2-12 mm, preferably 2-10 mm, more preferably 2-6 mm) and surface finish. Multiple calendering passes may be used to achieve the target thickness and to improve the orientation and distribution of fibers in the plane of the sheet. In compression molding, the mixed material is placed in a heated mold and subjected to pressure (typically 5-50 MPa) and temperature (typically 140-180°C for rubber vulcanization, or appropriate temperatures for thermoplastic processing) for a specified time to form the sheet and, in the case of rubber systems, to achieve crosslinking (vulcanization) that creates the three-dimensional network structure in the binder matrix. After forming, the sheets may be cooled, trimmed to size, and optionally subjected to post-curing or conditioning steps to optimize the properties and stabilize the dimensions. If coupling profiles are to be formed at the edges of the support element, these may be machined or milled after the sheet is formed, using appropriate cutting tools and machining parameters to achieve clean, precise profiles without excessive tearing or roughness of the composite material. The presence of mineral fillers and the controlled moisture content may facilitate this profiling operation by reducing stickiness and improving the cutting characteristics of the composite.

[0101] The decorative top layer is preferably affixed to the support element by means of at least one adhesive layer, which may be applied using various methods depending on the type of adhesive and the production scale. In a preferred embodiment, the adhesive is applied to the upper surface of the support element, to the lower surface of the decorative top layer, or to both surfaces, using application methods such as roller coating, spray application, curtain coating, or screen printing. For water-based adhesives, which may have a viscosity below 50 Pa s at room temperature (typically 20-25°C), roller coating or spray application may be preferred, as these methods can apply a uniform thin layer of adhesive with good control over the application rate. The water-based adhesive may comprise polymers such as polyvinyl acetate (PVA), acrylic polymers, polyurethane dispersions, or styrene-butadiene latex, and may be formulated to provide the desired balance of initial tack, open time, final bond strength, and flexibility. The water-based adhesive may be applied at room temperature and may be allowed to partially dry or become tacky before the decorative top layer is placed onto the support element and pressure is applied to ensure good contact and bonding. For hot melt adhesives, such as polyurethane (PU) hot melt adhesives, which may have a viscosity below 10 Pa s at application temperatures between 120°C and 180°C, the adhesive is heated to its application temperature and then applied using heated roller coaters, slot die coaters, or spray nozzles. The hot melt adhesive solidifies upon cooling, providing rapid bonding between the support element and the decorative top layer without the need for solvent or water evaporation, which can speed up the manufacturing process.

[0102] The adhesive layer is preferably a flexible adhesive layer that can accommodate differences in thermal expansion or contraction between the support element and the decorative top layer, as well as any minor dimensional changes due to moisture variations. The flexibility of the adhesive layer is important because the support element, which contains natural fibers and an elastomeric or thermoplastic binder, may have different coefficients of thermal expansion and moisture expansion compared to the decorative top layer, which is typically made of ceramic, stone, or another rigid material with very low thermal and moisture expansion. While the support element is designed to have low linear moisture expansion coefficients (less than 0.015% per % moisture change) and low thickness swelling coefficients (less than 0.6% per % moisture change) that are well-matched to the essentially zero expansion of the decorative top layer, some differential movement may still occur under extreme conditions or during thermal cycling. A flexible adhesive layer can deform elastically to accommodate these differential movements without generating excessive stresses that could lead to delamination or cracking. Preferably, the adhesive layer has an elongation at break of at least 50%, more preferably at least 100%, and most preferably at least 200%, which allows it to stretch and accommodate differential movements between the layers. The adhesive layer preferably also has good peel strength, typically at least 1 N / mm, preferably at least 2 N / mm, more preferably at least 3 N / mm, measured according to standard peel test methods such as ASTM D903 or ISO 8510, to ensure that the decorative top layer remains securely bonded to the support element under normal use conditions including foot traffic, furniture loads, and cleaning operations.

[0103] The adhesive layer may penetrate into the support element and / or the decorative top layer, which can enhance the bond strength by creating mechanical interlocking in addition to adhesive bonding. The penetration depth may depend on the viscosity of the adhesive, the porosity and surface roughness of the support element and decorative top layer, the application pressure, and the time allowed before the adhesive sets or cures. For the support element, which is a composite material containing natural fibers and having some degree of porosity (particularly due to the porous structure of fibers such as cotton with its lumen, or the fibrous structure of leather fibers), the adhesive may penetrate into surface pores and around surface fibers to a depth of typically 0.1 to 2 mm, creating a transition zone where the adhesive is mixed with the composite material. This penetration and mechanical interlocking may significantly enhance the bond strength and may help to distribute stresses over a larger area, reducing the risk of delamination. The penetration may be particularly effective when the exposed upper surface of the support element has been treated with a coating comprising silane coupling agents, as these agents can improve the wettability of the surface and promote better adhesive penetration and chemical bonding. For the decorative top layer, particularly if it is a porous ceramic tile or natural stone, the adhesive may also penetrate into surface pores, although typically to a lesser depth than in the support element due to the generally lower porosity and smaller pore sizes of these materials. The penetration may be controlled by adjusting the adhesive viscosity, with lower viscosity promoting deeper penetration and higher viscosity limiting penetration to the surface region. In some embodiments, a primer or surface treatment may be applied to the decorative top layer prior to adhesive application to improve wetting and bonding, particularly for dense, low-porosity materials such as porcelain tile or polished stone. The panel according to the invention is designed to provide excellent acoustic performance, which is quantified by two key parameters: the sound absorption coefficient (a) and the sound transmission loss (STL). The sound absorption coefficient measures the ability of the panel to absorb sound energy that strikes its surface, converting the acoustic energy into heat through various mechanisms. In the composite material of the support element, sound absorption occurs through multiple mechanisms that operate at different frequencies and length scales. At the microscopic level, the natural fibers, particularly porous fibers such as cotton with its hollow lumen structure, provide numerous internal air pockets and surface irregularities that create viscous and thermal losses as sound waves cause air to move in and out of these small spaces. At a slightly larger scale, the natural fibers embedded in the elastomeric or thermoplastic binder matrix undergo viscoelastic deformation when subjected to the oscillating stresses associated with sound waves, and the internal friction within the fiber material and at the fiber-matrix interface converts mechanical energy into heat. At a still larger scale, the multiscale fiber network structure, with short, fine fibers such as cotton forming a dense micro-network and longer, stiffer fibers such as hemp or wood fibers forming a coarser macro-network, allows for frictional energy dissipation as fibers rub against each other and against the binder matrix under dynamic loading. The cotton fibers, being soft and highly porous, are particularly effective at absorbing sound at mid to high frequencies (typically 500 Hz to 4000 Hz), while the stiffer structural fibers such as hemp or wood fibers contribute more to absorption at lower frequencies (typically 250 Hz to 1000 Hz) through the flexing and internal rubbing of the percolated network they form.

[0104] A sound absorption coefficient of 0.4 means that 40% of the incident sound energy is absorbed by the panel, with the remaining 60% being reflected. The panel according to the invention preferably achieves a sound absorption coefficient of at least 0.4 at frequencies of at least 250 Hz, which provides significant reduction in reverberation and echo in a room, improving acoustic comfort. This is particularly beneficial in residential spaces, offices, restaurants, and other environments where control of reflected sound is important for speech intelligibility and overall comfort. The broadband acoustic absorption provided by the multi-scale fiber network allows the panel to be effective across a wide frequency range, rather than only at specific resonant frequencies as might be the case with some acoustic treatments. The sound transmission loss measures the ability of the panel to block sound from transmitting through it from one side to the other, which is important for reducing noise transfer between rooms or between floors in a building. An STL of 35 dB means that sound passing through the panel is reduced in intensity by 35 dB, which represents a reduction to approximately 1 / 3000 of the original sound intensity, or equivalently, a reduction in sound pressure level from, for example, 70 dB (typical conversation level) to 35 dB (quiet library level). This level of sound transmission loss is sufficient to significantly reduce the transmission of speech, television sound, footsteps, and other common indoor sounds between spaces, providing good acoustic privacy.

[0105] The high STL is achieved through several mechanisms. First, the high density of the support element (at least 1000 kg / m3, preferably at least 1100 kg / m3, more preferably at least 1200 kg / m3) provides mass that resists sound transmission according to the mass law of acoustics, which states that STL increases with increasing surface mass density (mass per unit area). The mineral fillers such as calcium carbonate or talc contribute significantly to this high density while maintaining the flexibility of the composite. Second, the damping properties of the composite material, arising from the viscoelastic behavior of the elastomeric binder and the energy dissipation in the multi-scale fiber networks, reduce the amplitude of vibrations in the panel and thereby reduce sound radiation from the panel surfaces. A highly damped panel will vibrate less in response to incident sound and will radiate less sound to the opposite side compared to an undamped panel of the same mass. Third, the decorative top layer, which is typically a dense, stiff material such as ceramic or stone, acts as an additional mass layer and also provides a impedance mismatch at the interface with the support element, which can reflect some sound energy back rather than allowing it to transmit through. The combination of the flexible, damped support element with the rigid, dense decorative top layer creates a composite structure with superior sound transmission loss compared to either material alone.

[0106] The acoustic properties of the panel may be measured using standardized test methods to ensure reliable and reproducible results. The sound absorption coefficient may be measured using the impedance tube method according to ISO 10534-2 or ASTM E1050. In this method, a sample of the panel (typically a circular sample with diameter 29 mm or 100 mm, depending on the frequency range of interest) is placed at one end of a rigid-walled tube, and sound waves of various frequencies are generated at the other end using a loudspeaker. Two microphones are positioned at known locations in the tube between the loudspeaker and the sample, and the sound pressure is measured at these locations. From the measured sound pressures and the known microphone positions, the complex reflection coefficient of the sample can be calculated, and from this the sound absorption coefficient can be determined as a function of frequency. This method is particularly suitable for measuring absorption at normal incidence (sound waves perpendicular to the sample surface) and can cover a wide frequency range by using tubes of different diameters. Alternatively, the sound absorption coefficient may be measured in a reverberation room according to ISO 354 or ASTM C423. In this method, a larger sample of the panel (typically 10-12 m2of floor area) is placed in a room with highly reflective walls, ceiling, and floor, and the reverberation time (the time required for sound to decay by 60 dB after the source is stopped) is measured with and without the sample present. The sound absorption coefficient is calculated from the change in reverberation time, corrected for the sample area and the room volume. This method measures absorption at random incidence (sound waves arriving from all directions) and provides a single-number rating that is useful for comparing different materials.

[0107] The sound transmission loss may be measured using a two-room method according to ISO 10140 or ASTM E90. In this method, the panel is installed as a partition between two adjacent rooms: a source room where sound is generated, and a receiving room where the transmitted sound is measured. The rooms are typically constructed to have high sound insulation between them except for the test opening where the panel is installed. Sound is generated in the source room using loudspeakers, and the sound pressure levels are measured in both the source room and the receiving room using microphones at multiple positions. The STL is calculated from the difference in average sound pressure levels between the two rooms, corrected for the area of the test specimen and the acoustic absorption in the receiving room (which affects how much the transmitted sound builds up in that room). Measurements are typically made at multiple frequencies (usually in one-third octave bands from 100 Hz to 5000 Hz), and the results can be presented as a function of frequency or summarized using single-number ratings such as the weighted sound reduction index (Rw) according to ISO 717-1. For floor panels, impact sound insulation may also be measured according to ISO 10140-3 or ASTM E492, in which a standardized tapping machine is operated on the floor surface and the sound levels in the room below are measured. The impact sound insulation is quantified by the impact sound pressure level (Ln) or the impact insulation class (HO), with lower values indicating better impact sound insulation. The panel according to the invention, with its flexible, damped support element, may provide excellent impact sound insulation in addition to good airborne sound transmission loss, making it particularly suitable for multi-story buildings where both airborne and impact sound transmission are concerns.

[0108] Further embodiments of the invention are described in the non-limitative set of clauses presented below.

[0109] 1 . Panel for constructing a floor or wall covering, comprising:

[0110] • at least one planar support element comprising: an upper surface and a lower surface, wherein the support element is at least partially made of a composite material, which composite material comprises: o at least one binder selected from the group consisting of: an elastomeric binder and a thermoplastic binder, o natural particles, in particular natural fibers, dispersed in said binder, wherein at least one type of natural particles is chosen from the group consisting of: plant particles, wood particles, and animal particles, and o water; o wherein said composite material is flexible and has a compressive strength of at least 800 kPa, and

[0111] • at least one decorative top layer which is affixed, either directly or indirectly, to the upper surface of the support element, wherein the top layer is at least partially made of at least one material chosen from the group consisting of: ceramic, stone, concrete, mineral porcelain, glass, mosaic, granite, limestone and marble. 2. Panel according to clause 1 , the binder comprises an elastomer, such as rubber and / or a thermoplastic elastomer (TPE).

[0112] 3. Panel according to clause 1 or 2, the binder comprises rubber, in particular natural rubber.

[0113] 4. Panel according to any of the preceding clauses, the binder is at least partially crosslinked.

[0114] 5. Panel according to any of the preceding clauses, wherein the support element is flexible.

[0115] 6. Panel according to any of the preceding clauses, wherein the support element has a Mohs hardness scale rating of less than 3, preferably less than 2.

[0116] 7. Panel according to any of the preceding clauses, wherein the support element has a Shore A hardness of less than 90, and preferably more than 45.

[0117] 8. Panel according to any of the preceding clauses, wherein tear strength of the support element is situated between 55 and 75 N / mm.

[0118] 9. Panel according to any of the preceding clauses, wherein at least a fraction of the natural particles is formed by cotton fibers, in particular recycled cotton fibers.

[0119] 10. Panel according to any of the preceding clauses, wherein at least a fraction of the natural particles is formed by a mixture of plant fibers, in particular cotton fibers, and natural particle dust, in particular plant dust, preferably cotton dust.

[0120] 11 . Panel according to clause 9 or 10, wherein the plant fibers, in particular the cotton fibers, have an average length of between 1 and 20 mm, in particular between 1 and 5 mm; and wherein the natural particle dust, in particular the plant dust, preferably the cotton dust, if applied, has an average size of between 1 and 100 micron. 12. Panel according to any of the preceding clauses, wherein at least a fraction of the natural particles is formed by animal leather fibers.

[0121] 13. Panel according to any of the preceding clauses, wherein at least a fraction of the natural particles is formed by a mixture animal leather fibers and natural particle dust, in particular animal leather dust, more in particular leather buffing dust.

[0122] 14. Panel according to clause 12 or 13, wherein the animal leather fibers have an average length of between 0.5 and 5 mm, and wherein the natural particle dust, in particular the animal leather dust, if applied, has an average size of between 0.1 and 500 microns.

[0123] 15. Panel according to any of the previous clauses, wherein the natural particles, in particular natural fibers, are at least partially encapsulated by said binder.

[0124] 16. Panel according to any of the previous clauses, wherein the natural particles comprises at least one natural fiber chosen from the group consisting of: cotton fiber, coir fiber, kapok fiber, jute fiber, flax fiber, hemp fiber, kenaf fiber, ramie fiber, sisal fiber, abaca (manila hemp) fiber, pineapple fiber, banana fiber, palm fiber, bagasse fiber, straw fiber, bamboo fibers, grass fibers, and / or seagrass particles.

[0125] 17. Panel according to any of the previous clauses, wherein the natural particles comprise plant particles comprising at least 60% by weight of cellulose.

[0126] 18. Panel according to any of the previous clauses, wherein the natural particles comprise plant particles comprising cellulose having a cellulose crystallinity of at least 80% by weight of the total amount of cellulose.

[0127] 19. Panel according to any of the previous clauses, wherein the natural particles comprise plant particles comprising less than 20% by weight of lignin.

[0128] 20. Panel according to any of the previous clauses, wherein the natural particles comprise plant particles comprising wood flour and / or wood fibers. 21 . Panel according to any of the previous clauses, wherein the natural particles comprise animal particles comprising leather particles, in particular leather fibers.

[0129] 22. Panel according to clause 21 , wherein the leather particles, in particular animal leather fibers, are urea-treated animal leather particles, in particular urea- treated animal leather fibers.

[0130] 23. Panel according to any of the previous clauses, wherein the composite material comprises synthetic fibers, preferably at least one synthetic fiber chosen from the group consisting of: polyester fiber, nylon fiber, polypropylene fiber, aramid fiber, polyethylene fiber, acrylic fiber, carbon fiber, glass fiber, polyvinyl alcohol (PVA) fiber.

[0131] 24. Panel according to any of the preceding clauses, wherein the support element comprises sulfur and preferably zinc oxide.

[0132] 25. Panel according to any of the previous clauses, wherein the composite material comprises at least one inert mineral filler, such as calcium carbonate and / or talc.

[0133] 26. Panel according to any of the preceding clauses, wherein the weight ratio of natural particles and binder in the support element is at least 0.25, preferably at least 0.8, more preferably at least 1 , and preferably less than 4.

[0134] 27. Panel according to any of the preceding clauses, wherein at least a fraction of the natural particles is porous.

[0135] 28. Panel according to any of the preceding clauses, wherein the support element is provided with flexible, preferably vertical, side edges.

[0136] 29. Panel according to any of the preceding clauses, wherein the support element is oversized with respect to the decorative top layer. 30. Panel according to any of the preceding clauses, wherein the support element extends with respect to each side edge of the decorative top layer.

[0137] 31 . Panel according to any of the preceding clauses, wherein the decorative top structure is adhered onto the support element by means of at least one adhesive layer.

[0138] 32. Panel according to any of the preceding clauses, wherein the decorative top structure is adhered onto the support element by means of at least one adhesive layer, in particular at least one flexible adhesive layer.

[0139] 33. Panel according to clause 32, wherein the adhesive layer comprises a water based adhesive having a viscosity below 50 Pa s at room temperature and / or wherein a hot melt adhesive, such as a PU hot melt adhesive having a viscosity below 10 Pa s at a temperature between 120 and 180 °C.

[0140] 34. Panel according to clause 32 or 33, wherein the adhesive layer penetrates into the support element and / or the decorative top layer.

[0141] 35. Panel according to any of the previous clauses, wherein the support element has a linear moisture expansion coefficient of less than 0.015% per % moisture change of the support element.

[0142] 36. Panel according to any of the previous clauses, wherein the support element has a first linear moisture expansion coefficient, and wherein the top layer has second linear moisture expansion coefficient, wherein the difference between the first linear moisture expansion coefficient and the second linear moisture expansion coefficient is less than 0.015% per % moisture change.

[0143] 37. Panel according to one of the previous clauses, wherein the support element has a linear moisture contraction coefficient of less than 0.025% per % moisture change of the support element.

[0144] 38. Panel according to one of the previous clauses, wherein the support element has a first linear moisture contraction coefficient, and wherein the top layer has second linear moisture contraction coefficient, wherein the difference between the first linear moisture contraction coefficient and the second linear moisture contraction coefficient is less than 0.025 % per % moisture change.

[0145] 39. Panel according to one of the previous clauses, wherein the support element has a thickness swelling coefficient of less than 0.6% per % moisture change of the support element.

[0146] 40. Panel according to one of the previous clauses, wherein the support element has a first thickness swelling coefficient, and wherein the top layer has second thickness swelling coefficient, wherein the difference between the first thickness swelling coefficient and the second thickness swelling coefficient is less than 0.6% per % moisture change.

[0147] 41 . Panel according to one of the previous clauses, wherein the support element has a thickness shrinkage coefficient of less than 0.5% per % moisture change of the support element.

[0148] 42. Panel according to one of the previous clauses, wherein the support element has a first thickness shrinkage coefficient, and wherein the top layer has a second thickness shrinkage coefficient, wherein the difference between the first thickness shrinkage coefficient and the second thickness shrinkage coefficient is less than 0.5% per % moisture change.

[0149] 43. Panel according to one of the previous clauses, wherein the support element has a density of at least 1000 kg / m3, preferably at least 1100 kg / m3, more preferably at least 1200 kg / m3.

[0150] 44. Panel according to any of the previous clauses, wherein the support element consists of a single material layer.

[0151] 45. Panel according to any of the previous clauses, wherein the support element has a thickness between 2 and 12 mm, preferably between 2 and 10 mm, more preferably between 2 and 6 mm. 46. Panel according to any of the previous clauses, wherein the support element is free of interconnecting coupling profiles for interconnecting adjacent panels.

[0152] 47. Panel according to one of clauses 1-45, wherein at least one pair of opposed side edges of the support element is provided with interconnecting coupling profiles for interconnecting adjacent panels.

[0153] 48. Panel according to clause 47, wherein the panel comprises, at a first pair of opposed side edges, a first and a second coupling profile, wherein the first coupling profile and the second coupling profile are configured such that the first and second coupling profiles of two identical panels can be coupled to each other by means of a vertical or horizontal movement, and wherein the panel comprises, at a second pair of opposed edges, a third coupling profile and a fourth coupling profile, wherein the third coupling profile and the fourth coupling profile are configured such that the third and fourth coupling profiles of two identical panels can be coupled to each other by means of a turning or horizontal movement.

[0154] 49. Panel according to one of the previous clauses, wherein an exposed upper surface of the support element is provided with a coating, wherein said coating preferably comprises at least one silane coupling agent such as 3- aminopropyltriethoxysilane (APTES), 3-glycidoxypropyltrimethoxysilane (GPTMS), vinyltrimethoxysilane (VTMS), methacryloxypropyltrimethoxysilane (MPTS), and / or octyltriethoxysilane (OTES).

[0155] 50. Panel according to any of the previous clauses, wherein the support element and the top layer are mutually affixed via an adhesive layer.

[0156] 51 . Panel according to clause 50, wherein the adhesive layer is flexible layer configured to withstand expansion differences between the support element and the top layer.

[0157] 52. Panel according to clause 50 or 51 , wherein the adhesive layer is a hot melt adhesive layer. 53. Panel according to any of the previous clauses, wherein the sound absorption coefficient of the support element (a) is at least 0.4.

[0158] 54. Panel according to any of the previous clauses, wherein the sound transmission loss (STL) at least 35 dB at sound frequencies of at least 250 Hz.

[0159] 55. Panel according to any of the previous clauses, wherein the top layer has a thickness between 2 and 20 mm, preferably between 2.5 and 10 mm, more preferably between 3 and 6 mm.

[0160] 56. Panel according to any of the preceding clauses, wherein at least a fraction of the natural particles is formed by a mixture of cotton fibers and at least one plant fiber chosen from the group consisting of: hemp fibers, seagrass fibers, at least one bast fiber selected from the group consisting of: flax fiber, kenaf fiber, jute fiber and ramie fiber, and at least one leaf fiber selected from the group consisting of: sisal fiber, abaca fiber, pineapple leaf fiber (PALF) and coir fiber.

[0161] 57. Panel according to any of the preceding clauses, wherein at least a fraction of the natural particles is formed by a mixture of animal leather fibers and at least one plant fiber chosen from the group consisting of: cellulose fibers and wood fibers.

[0162] 58. Panel according to any of the preceding clauses, wherein at least a fraction of the natural particles is formed by a mixture animal leather fibers and plant fibers, such as wood fibers and / or cellulose fibers.

[0163] 59. Panel according to any of the preceding clauses, wherein the natural particles content in the composite material is at least 30% by weight, and preferably less than 50% by weight, of the support element.

[0164] 60. Panel according to any of the previous clauses, wherein the composite material comprises at least one inert mineral filler, such as calcium carbonate and / or talc, wherein the mineral filler content in the composite material is at least 20% by weight, and preferably less than 30% by weight, of the support element..

[0165] 61 . Panel according to any of the preceding clauses, wherein the binder content in the composite material at least 20% by weight, and preferably less than 60% by weight, of the support element.

[0166] 62. Panel according to any of the preceding clauses, wherein the water content of the composite material exceeds a nominal equilibrium moisture content of the natural particles.

[0167] 63. Support element for intended use in a panel according to any of the previous clauses.

[0168] 64. System for constructing a floor or wall covering comprises a plurality of panels according to any of clauses 1-62, wherein adjacent support elements abut each other, and wherein adjacent support elements are preferably mechanically connected to each other.

[0169] 65. System according to clause 64, wherein the support element of each panel is oversized with respect to the decorative top layer of said panel, such that gaps are formed in between adjacent decorative top structures of the system, wherein said gaps are preferably at least partially filled by means of a grout material.

[0170] The invention will be further elucidated based upon the following non-limitative figures. Herein shows: figure 1 an exploded perspective view of a panel according to the present invention; figure 2a and 2b cross sectional view of panels according to the present invention;

[0171] Within these figures, similar reference signs correspond to similar or equivalent features or elements; figure 3 shows a top view of an embodiment of another decorative panel according to the invention; figure 4 on a larger scale shows a cross section along the line IV-IV of Figure 3; and

[0172] Figure 5 on a larger scale shows a cross section along the line V-V of Figure 5. Figure 1 shows a schematic representation of a panel 1 according to the present invention. The panel is configured for constructing a floor or wall covering, and comprises a substantially flat support element 2 which comprises an upper surface 3, a lower surface 4, a first pair of opposed side edges 5a, 5b and a second pair of opposed side edges 7a, 7b. Further a decorative top layer 6 is configured to be affixed to the upper surface 3 of the support element 6. The support element 2 comprises wood fibers and / or plant fibers, and at least one binder has a density of at least 1000 kg / m3. In the shown embodiment, a backing layer 9 is attached to the lower surface 4 of the support element. It is to be understood that, in other embodiments, the support element 2 may assume various shapes, different from the shown rectangular shape. For example, the support element 2 may have diamond or square shape. In further embodiments, the support element 2 may be a polygon with a number of sides greater than four. Also in this case the opposed side edges 5a, 5b , 7a, 7b are consecutive one to the other and alternate in sequence to each other. Typically, the support element 2 has a thickness between 2 and 12 millimeters, preferably between 2 and 10 millimeters. In the shown embodiment, the support element 2 is provided with interconnecting coupling means 10. The coupling means 10 are in the shown embodiment a combination of a female coupling part 11 and a male counter coupling part 12. The support element 2 and the top layer 6 can be mutually affixed via an adhesive layer (not shown).

[0173] Figures 2a and 2b show a cross sectional view of panels 1 according to the present invention. It can be seen that two adjacent panels 1 can be interconnected via the coupling means 10. The thickness Ht of the top layer 6 is larger than the thickness Hs of the support element 2. It can be seen that the top layer 6 does not protrudes outside the perimeter of the upper surface 3 of the support element 2. Figure 2b shows an embodiment, wherein, in an assembled condition, the adjacent panels 1 are arranged such that a predetermined distance D is defined between the side surfaces 8 of the top layers 6. The distance D can for example be between 0 and 4 millimeters, and preferably between 1 and 2.5 millimeters. Once the floor or wall covering is provided, it is possible to seal the distance D between two adjacent panels, for example with sealing means. This can for example be done with resins for joints which are typically used in the construction industry such as water-based resins, epoxy and / or cement resins.

[0174] Figure 3 shows a top view of another embodiment of a decorative panel 21 , such as a floor panel, according to the invention. The floor element 21 comprises a decorative tile 22, acting as top layer, disposed above an oversized support element 23. The support element 23 extends beyond all side edges of the tile 22. As illustrated, the panel 21 has a rectangular elongated shape. Preferably, the panel 21 comprises a superficial area of less than 1.5 sqm, preferably less than 1 sqm, and more preferably less than 0.4 sqm. For example, the decorative tile 22 comprises edges with a maximum length L of less than 1 .5 m, preferably less than 0.9 m. The decorative tile 22 has a decorative upper face 24 which can include a variety of textures, designs, and colors. In the illustrated example, the decorative tile 22 is formed by a ceramic tile, such as red body ceramic tile or a porcelain tile.

[0175] The decorative tile 22 may include a background coating, such as a glaze, covering at least part of the upper surface of the tile 22. This coating is adapted to receive an printed decorative layer on top, which print layer is optionally covered by a protective coating, which at least partially covers the decor and is transparent or translucent. In the embodiment shown, this laminate of layers is not applied on top. In practice this laminate of layers is not always needed as the tile as such may have a decorative character.

[0176] Figure 2 indicates the oversize D1 at both sides. This oversize D1 may have equal widths at opposite sides but may also have mutually different widths. The oversize leads to exposed upper surface portions of the support element 23. This exposed upper surface portions may optionally be covered by a coating, such as a silane coupling agent, preferably to improve adhesion of grout mortar material applied on top when creating a floor covering or wall covering of a plurality of adjacent panels 21 . As also indicated in figure 2, the decorative tile 22 has a thickness T1 ranging from 4 to 15 mm, such as 6 mm, preferably greater than 7 mm, such as 8 or 10 mm, while the support element 23 has a thickness T2 which is less than the thickness T 1 of the tile 22. The thickness T2 . preferably ranges from 2 to 7 mm, ideally less than 6 mm, and more preferably about 4 mm or less. The support element 23, in this example, comprises at least one binder selected from the group consisting of: an elastomeric binder, such as rubber or another thermosetting material; and a thermoplastic binder, such as a thermoplastic elastomer. The binder typically acts as matrix material. The support element 23 further comprises natural particles, in particular natural fibers, dispersed in said binder, wherein at least one type of natural particles is chosen from the group consisting of: plant particles, wood particles, and animal particles. At least a fraction of the natural particles is formed by natural fibers. At least a fraction of the natural particles is formed by porous particles. Preferably, the support element further comprises (some) water.

[0177] As indicated in figures 4 and 5 the support element 23 may be provided with coupling profiles at the longitudinal edges and the short edges. It is however also imaginable that the longitudinal edges and the short edges are free of coupling profiles or that only one pair of edges of the longitudinal edges and the short edges is provided with coupling profiles.

[0178] In figure 4, it is shown that longitudinal edges 25 equipped with first coupling elements 25a and 25b configured for mechanical coupling with corresponding coupling elements of an adjacent panel 21 . In the example shown, the coupling elements 25a and 25b include complementary male and female parts positioned on opposite longitudinal edges 25. These first coupling elements 25a and 25b are designed for coupling via an angling motion around a horizontal axis parallel to the longitudinal edges 25. The male and female parts are shaped as a tongue 25a and groove 25b, respectively. As indicated above, the exposed upper surface of the support element 23 at the longitudinal edges 25 extends - as seen from a top view - with respect to the decorative tile 22 by a distance D1, which may or may not be equal on both sides. For example, D1 may exceed 0.5 mm, preferably more than 0.75 mm, such as approximately 1.5 mm.

[0179] Figure 4 further shows an intermediate adhesive layer 27 located between the decorative tile 22 and the support element 23. This adhesive layer is preferably a flexible adhesive layer 27. The adhesive layer 27 preferably comprises a resin material, such as a thermosetting or thermoplastic resin. Examples of thermosetting resins include epoxy, polyurethane, cyanoacrylate, or acrylic resins, while thermoplastic options include hot melts, polyester thermoplastics, or vinyl. The adhesive layer 27 may penetrate into the decorative tile 22 and / or the support element 23. Grooves (not shown) may be included in the support element 23 to collect any overflow resin from the intermediate layer 27, preventing interference with the coupling elements 25a and 25b. These grooves may run parallel to the edges 25 of the decorative layer 22. They may also extend along the short edges of the panel 21.

[0180] Figure 5 indicates that the support element 23 includes short edges 26 equipped with complementary second coupling elements 26a and 26b. These elements enable mechanical coupling with corresponding elements of an adjacent floor element 21 via a downward translational motion. The support element 23 also extends beyond the decorative layer’s side edges by a distance D2, which may or may not be equal on both sides. For example, D2 may exceed 0.5 mm, preferably more than 0.75 mm.

[0181] The above-described inventive concepts are illustrated by several illustrative embodiments. It is conceivable that individual inventive concepts may be applied without, in so doing, also applying other details of the described example. It is not necessary to elaborate on examples of all conceivable combinations of the abovedescribed inventive concepts, as a person skilled in the art will understand numerous inventive concepts can be (re)combined in order to arrive at a specific application.

[0182] 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.

[0183] When it is referred to a ‘panel’, also the term ‘tile’ or ‘prefabricated element’ could be used. 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”, “is” and conjugations thereof, and vice versa. It must also be noted that, as used in the specification and the appended claims, the singular forms “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, reference to a component is intended also to include composition of a plurality of components. References to a composition comprising “a” constituent may be intended to include other constituents in addition to the one named. In other words, the terms “a”, ”an,” and “the” do not denote a limitation of quantity, but rather denote the presence of “at least one” of the referenced item. As used herein, the term “and / or” may mean “and”, it may mean “or”, it may mean “exclusive-or,” it may mean “one”, it may mean “some, but not all,” it may mean “neither”, and / or it may mean “both.” The term “or” is intended to mean an inclusive “oh’.

Claims

62Claims1 . Panel for constructing a floor or wall covering, comprising:- at least one planar support element comprising: an upper surface and a lower surface, wherein the support element is at least partially made of a composite material, which composite material comprises: o at least one natural binder selected from the group consisting of: an elastomeric binder and a thermoplastic binder, o natural particles, in particular natural fibers, dispersed in said binder, wherein at least one type of natural particles is chosen from the group consisting of: plant particles, wood particles, and animal particles, and o water; wherein said composite material is flexible and has a compressive strength of at least 800 kPa, wherein said composite material is essentially entire composed of natural materials, and- at least one decorative top layer which is affixed, either directly or indirectly, to the upper surface of the support element, wherein the top layer is at least partially made of at least one material chosen from the group consisting of: ceramic, stone, concrete, mineral porcelain, glass, mosaic, granite, limestone and marble.

2. Panel according to claim 1 , the binder comprises an elastomer, such as rubber and / or a thermoplastic elastomer (TPE).

3. Panel according to claim 1 or 2, the binder comprises rubber, in particular natural rubber.

4. Panel according to any of the preceding claims, the binder is at least partially crosslinked.

5. Panel according to any of the preceding claims, wherein the support element is flexible.

636. Panel according to any of the preceding claims, wherein the support element has a Mohs hardness scale rating of less than 3, preferably less than 2.

7. Panel according to any of the preceding claims, wherein the support element has a Shore A hardness of less than 90, and preferably more than 45.

8. Panel according to any of the preceding claims, wherein tear strength of the support element is situated between 55 and 75 N / mm.

9. Panel according to any of the preceding claims, wherein at least a fraction of the natural particles is formed by cotton fibers, in particular recycled cotton fibers.

10. Panel according to any of the preceding claims, wherein at least a fraction of the natural particles is formed by a mixture of plant fibers, in particular cotton fibers, and natural particle dust, in particular plant dust, preferably cotton dust.11 . Panel according to any of the preceding claims, wherein at least a fraction of the natural particles is formed by a mixture of cotton fibers and at least one plant fiber chosen from the group consisting of:- hemp fibers,- seagrass fibers,- at least one bast fiber selected from the group consisting of: flax fiber, kenaf fiber, jute fiber and ramie fiber, and- at least one leaf fiber selected from the group consisting of: sisal fiber, abaca fiber, pineapple leaf fiber (PALF) and coir fiber.

12. Panel according to claim 10 or 11 , wherein the plant fibers, in particular the cotton fibers, have an average length of between 1 and 20 mm, in particular between 1 and 5 mm; and wherein the natural particle dust, in particular the plant dust, preferably the cotton dust, if applied, has an average size of between 1 and 100 micron.

13. Panel according to any of the preceding claims, wherein at least a fraction of the natural particles is formed by animal leather fibers.6414. Panel according to any of the preceding claims, wherein at least a fraction of the natural particles is formed by a mixture of animal leather fibers and at least one plant fiber chosen from the group consisting of: cellulose fibers and wood fibers.

15. Panel according to any of the preceding claims, wherein at least a fraction of the natural particles is formed by a mixture of animal leather fibers and natural particle dust, in particular animal leather dust, more in particular leather buffing dust.

16. Panel according to any of the preceding claims, wherein at least a fraction of the natural particles is formed by a mixture animal leather fibers; and at least one plant fiber chosen from the group consisting of: cellulose fibers and wood fibers; and at least one other natural particle, in particular at least one other natural fiber.

17. Panel according to any of claims 12-16, wherein the animal leather fibers have an average length of between 0.5 and 5 mm, and wherein the natural particle dust, in particular the animal leather dust, if applied, has an average size of between 0.1 and 500 microns.

18. Panel according to any of the previous claims, wherein the natural particles, in particular natural fibers, are at least partially encapsulated by said binder.

19. Panel according to any of the previous claims, wherein the natural particles comprises at least one natural particle, in particular at least one natural fiber, chosen from the group consisting of: cotton fiber, coir fiber, kapok fiber, jute fiber, flax fiber, hemp fiber, kenaf fiber, ramie fiber, sisal fiber, abaca (manila hemp) fiber, pineapple fiber, banana fiber, palm fiber, bagasse fiber, straw fiber, bamboo fibers, grass fibers, and / or seagrass particles.

20. Panel according to any of the previous claims, wherein the natural particles comprise plant particles comprising at least 60% by weight of cellulose.21 . Panel according to any of the previous claims, wherein the natural particles comprise plant particles comprising cellulose having a cellulose crystallinity of at least 80% by weight of the total amount of cellulose.6522. Panel according to any of the previous claims, wherein the natural particles comprise plant particles comprising less than 20% by weight of lignin.

23. Panel according to any of the previous claims, wherein the natural particles comprise plant particles comprising wood flour and / or wood fibers.

24. Panel according to any of the previous claims, wherein the natural particles comprise animal particles comprising leather particles, in particular leather fibers.

25. Panel according to claim 24, wherein the leather particles, in particular animal leather fibers, are urea-treated animal leather particles, in particular urea- treated animal leather fibers.

26. Panel according to any of the preceding claims, wherein the natural particles content in the composite material is at least 30% by weight, and preferably less than 50% by weight, of the support element.

27. Panel according to any of the previous claims, wherein the composite material comprises at least one inert mineral filler, such as calcium carbonate and / or talc, wherein the mineral filler content in the composite material is at least 20% by weight, and preferably less than 30% by weight, of the support element.

28. Panel according to any of the preceding claims, wherein the weight ratio of natural particles and binder in the support element is at least 0.25, preferably at least 0.8, more preferably at least 1 , and preferably less than 4.

29. Panel according to any of the preceding claims, wherein the binder content in the composite material at least 20% by weight, and preferably less than 60% by weight, of the support element.

30. Panel according to any of the preceding claims, wherein at least a fraction of the natural particles is porous.6631 . Panel according to any of the preceding claims, wherein the water content of the composite material exceeds a nominal equilibrium moisture content of the natural particles.

32. Panel according to any of the preceding claims, wherein the total water content in the composite material is at least 4% by weight, and preferably less than 10% by weight, of the support element.

33. Panel according to any of the preceding claims, wherein the support element is provided with flexible, preferably vertical, side edges.

34. Panel according to any of the preceding claims, wherein the support element is oversized with respect to the decorative top layer.

35. Panel according to any of the preceding claims, wherein the support element extends with respect to each side edge of the decorative top layer.

36. Panel according to any of the preceding claims, wherein the decorative top structure is adhered onto the support element by means of at least one adhesive layer.

37. Panel according to any of the preceding claims, wherein the decorative top structure is adhered onto the support element by means of at least one adhesive layer, in particular at least one flexible adhesive layer.

38. Panel according to claim 37, wherein the adhesive layer comprises a water based adhesive having a viscosity below 50 Pa s at room temperature and / or wherein a hot melt adhesive, such as a PU hot melt adhesive having a viscosity below 10 Pa s at a temperature between 120 and 180 °C.

39. Panel according to claim 37 or 38, wherein the adhesive layer penetrates into the support element and / or the decorative top layer.

40. Panel according to any of the previous claims, wherein the support element has a linear moisture expansion coefficient of less than 0.015% per % moisture change of the support element.41 . Panel according to any of the previous claims, wherein the support element has a first linear moisture expansion coefficient, and wherein the top layer has second linear moisture expansion coefficient, wherein the difference between the first linear moisture expansion coefficient and the second linear moisture expansion coefficient is less than 0.015% per % moisture change.

42. Panel according to one of the previous claims, wherein the support element has a linear moisture contraction coefficient of less than 0.025% per % moisture change of the support element.

43. Panel according to one of the previous claims, wherein the support element has a first linear moisture contraction coefficient, and wherein the top layer has second linear moisture contraction coefficient, wherein the difference between the first linear moisture contraction coefficient and the second linear moisture contraction coefficient is less than 0.025 % per % moisture change.

44. Panel according to one of the previous claims, wherein the support element has a thickness swelling coefficient of less than 0.6% per % moisture change of the support element.

45. Panel according to one of the previous claims, wherein the support element has a first thickness swelling coefficient, and wherein the top layer has second thickness swelling coefficient, wherein the difference between the first thickness swelling coefficient and the second thickness swelling coefficient is less than 0.6% per % moisture change.

46. Panel according to one of the previous claims, wherein the support element has a thickness shrinkage coefficient of less than 0.5% per % moisture change of the support element.

47. Panel according to one of the previous claims, wherein the support element has a first thickness shrinkage coefficient, and wherein the top layer has a second thickness shrinkage coefficient, wherein the difference between the first thickness shrinkage coefficient and the second thickness shrinkage coefficient is less than 0.5% per % moisture change.

48. Panel according to one of the previous claims, wherein the support element has a density of at least 1000 kg / m3, preferably at least 1100 kg / m3, more preferably at least 1200 kg / m3.

49. Panel according to any of the previous claims, wherein the support element consists of a single material layer.

50. Panel according to any of the previous claims, wherein the support element has a thickness between 2 and 12 mm, preferably between 2 and 10 mm, more preferably between 2 and 6 mm.51 . Panel according to any of the preceding claims, wherein the support element comprises sulfur and preferably zinc oxide.

52. Panel according to any of the previous claims, wherein the support element is free of interconnecting coupling profiles for interconnecting adjacent panels.

53. Panel according to one of claims 1 -52, wherein at least one pair of opposed side edges of the support element is provided with interconnecting coupling profiles for interconnecting adjacent panels.

54. Panel according to claim 53, wherein the panel comprises, at a first pair of opposed side edges, a first and a second coupling profile, wherein the first coupling profile and the second coupling profile are configured such that the first and second coupling profiles of two identical panels can be coupled to each other by means of a vertical or horizontal movement, and wherein the panel comprises, at a second pair of opposed edges, a third coupling profile and a fourth coupling profile, wherein the third coupling profile and the fourth coupling profile are configured such that the69 third and fourth coupling profiles of two identical panels can be coupled to each other by means of a turning or horizontal movement.

55. Panel according to one of the previous claims, wherein an exposed upper surface of the support element is provided with a coating, wherein said coating preferably comprises at least one silane coupling agent such as 3- aminopropyltriethoxysilane (APTES), 3-glycidoxypropyltrimethoxysilane (GPTMS), vinyltrimethoxysilane (VTMS), methacryloxypropyltrimethoxysilane (MPTS), and / or octyltriethoxysilane (OTES).

56. Panel according to any of the previous claims, wherein the support element and the top layer are mutually affixed via an adhesive layer.

57. Panel according to claim 56, wherein the adhesive layer is flexible layer configured to withstand expansion differences between the support element and the top layer.

58. Panel according to claim 56 or 57, wherein the adhesive layer is a hot melt adhesive layer.

59. Panel according to any of the previous claims, wherein the sound absorption coefficient of the support element (a) is at least 0.4.

60. Panel according to any of the previous claims, wherein the sound transmission loss (STL) at least 35 dB at sound frequencies of at least 250 Hz.61 . Panel according to any of the previous claims, wherein the top layer has a thickness between 2 and 20 mm, preferably between 2.5 and 10 mm, more preferably between 3 and 6 mm.

62. Support element for intended use in a panel according to any of the previous claims.

63. System for constructing a floor or wall covering comprises a plurality of panels according to any of claims 1-61 , wherein adjacent support elements abuteach other, and wherein adjacent support elements are preferably mechanically connected to each other.

64. System according to claim 63, wherein the support element of each panel is oversized with respect to the decorative top layer of said panel, such that gaps are formed in between adjacent decorative top structures of the system, wherein said gaps are preferably at least partially filled by means of a grout material.

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