Decorative surface covering comprising PVB

Abstract

A preferably PVC-free surface covering comprising a core layer, a decorative layer or decorative layer assembly, and optionally a backing layer. The core layer is a rigid layer having a deformation angle of less than 10 degrees, preferably less, clamped in a horizontal overhanging position so as to obtain a 160mm * 300mm protrusion, as measured for a rectangular sample of a size of 160mm * 450mm, and the core layer is a rigid layer having a deformation angle of less than 10 degrees, preferably less, as measured for the rectangular sample of a size of 160mm * 450mm, as measured for the rectangular sample of a size of 160mm * 450mm. The deformation angle is measured 30 seconds after removal of a support that prevents deformation of the protruding portion under the influence of its own weight. The core layer comprises a thermoplastic material comprising PVB. The thermoplastic material has a plasticizer content of no more than 20% by weight, preferably less, relative to the PVB content.

Description

Background Art

[0001] The present invention generally relates to decorative surface coverings, such as for example floor coverings (floors) or wall coverings, comprising PVB (polyvinyl butyral, poly[(2-propyl-1,3-dioxane-4,6-diyl)methylene), in particular recycled PVB.

[0002] PVB is a polymer resin with interesting properties for various applications. PVB has outstanding optical transparency, ability to combine with inorganic materials such as metals, glass and ceramics, high toughness. PVB is widely used in interlayers of safety glass for vehicles, buildings and other applications, for example. Other applications include thermoplastic processing, but due to the vinyl alcohol units of PVB, PVB can also be used in crosslinked compositions (for example, in combination with epoxy resins or isocyanates).

[0003] EP 0 950 688 A1 discloses a polyvinyl chloride (PVC) floor covering which, in addition to customary additives, contains PVB and magnesium hydroxide.

[0004] EP 0 853 097 A1 relates to a thermoplastic blend which can be processed to form a resilient floor and which comprises polyvinyl butyral and a polymer having a polar portion which is effective in forming hydrogen bonds with the polyvinyl butyral. The polymer having a polar portion can be selected from polyvinyl methacrylic acid, partial metal salts of polyvinyl methacrylic acid, polyvinyl acrylic acid, polyvinyl acetate, polyamide, polyamine, thermoplastic polyurethane, polyvinyl alcohol, polyethylene monoxide and mixtures thereof.

[0005] EP 1 104 783 A1 relates to a floor or wall covering comprising a mixture of a PVB resin and an ethylene vinyl acetate (EVA) copolymer, a benzoic acid glycol ester plasticizer, fillers and additives.

[0006] WO 93 / 02141A1 discloses a process for recycling PVB, wherein waste PVB is melt blended with an incompatible polymer having a melt processing temperature below the decomposition temperature of PVB and an effective amount of an anhydride-modified polymer which compatibilizes the resulting blend.

[0007] EP 0 471 658 A2 discloses floor coverings and floor covering compositions containing recycled plasticized PVB resins. Since the recycled PVB originates from laminated safety glass, the PVB may contain up to 10% by weight of fine glass particles.

[0008] EP 1 599 335 A1 uses post-consumer and / or post-industrial PVB (recycled or recycled PVB or PVB waste) as a component of the back coating, pre-coating and main back coating composition of floor coverings such as carpet materials, pile carpets and carpet tiles. The document more specifically proposes a mixture of recycled PVB, plasticizers and fillers; a mixture of recycled PVB, plasticizers, ethylene-vinyl acetate (EVA) and fillers; a mixture of recycled PVB, tackifier compositions, EVA and fillers (and optionally plasticizers); a mixture of recycled PVB, plasticizers, anionic surfactants and fillers; and recycled PVB extruded alone or in combination with fillers or other additives. The recycled PVB composition is considered to have excellent chemical and physical properties, long-term durability and compatibility with other floorings. Recycled PVB may contain glass particles and other contaminants. Recycled PVB is processed by crushing and density differences to separate PVB from glass and other components. Generally, recycled PVB contains plasticizers (typically, between about 30 phr and about 50 phr). EP 1599335 A1 states that recycled PVB may contain plasticizers (and other contaminants) for the purposes disclosed therein.

[0009] DE 4 202 948 A1 discloses a floor covering comprising 30% to 60% recycled PVB, 5% to 20% polyacrylate (PA) and 20% to 60% filler. Optional additives include pigments, UV stabilizers, flame retardants, antistatic agents or antimicrobial agents. The document mentions that the plasticizer content of the recycled PVB is 5% to 50%, but it is clear from the document that low plasticizer content is considered undesirable. If the plasticizer introduced into the composition via recycled PVB is insufficient, additional plasticizers, such as plasticizers compatible with both PVB and PA, can be added to the composition. The document also discusses the possibility of blending recycled PVB containing plasticizers with sufficient amounts of unplasticized virgin PVB and approximately the same amount of fillers and forming a floor covering with the composition obtained therefrom. It is mentioned that the floor covering exhibits disadvantages in terms of residual indentation and stability in the presence of moisture. Summary of the invention

[0010] According to an aspect of the invention, a surface covering is provided, such as a floor covering or a wall covering. The surface covering is preferably a PVC-free surface covering, i.e. a surface covering comprising less than 0.5%, preferably less than 0.2%, more preferably less than 0.1%, most preferably less than 0.05% by weight of PVC (polyvinyl chloride). The surface covering may comprise a core layer, a decorative layer or decorative layer assembly and optionally a backing layer.

[0011] The core layer may be a hard core layer having a deformation angle of less than 10 degrees, preferably less than 7 degrees, more preferably less than 5 degrees, most preferably less than 3 degrees, as measured by the following deformation test (cantilever test) performed under ambient temperature and pressure conditions (at 23°C and atmospheric pressure (i.e. about 1000 hPa)). According to the deformation test, a rectangular sample (in this case, a rectangular sample of the core layer) with dimensions of 160 mm×450 mm is clamped in a horizontal overhang position so as to obtain a 160 mm×300 mm protruding portion of the sample. The protruding portion is initially supported by removable horizontal supports over the entire length and width of the protruding portion. The deformation angle is measured 30 seconds after removing the supports that prevent the protruding portion from deforming under the influence of its own weight. The deformation angle corresponds to the angle between the horizontal support plane and a plane extending from the edge of the support (from which the protruding portion protrudes) to the lowermost end of the protruding portion. The deformation angle is a measure of the flexural strength of the structure being tested. According to one embodiment, the core layer has a flexural modulus of more than 500 MPa, preferably more than 1000 MPa, more preferably more than 1500 MPa, and most preferably more than 3000 MPa. According to another embodiment, the core layer has a flexural modulus of less than 20000 MPa, preferably less than 12000 MPa and more preferably less than 10000 MPa. Preferably, the core layer has a flexural modulus comprised between 1000 MPa and 10000 MPa. The flexural modulus is determined from the slope of the stress-strain curve produced by the flexural test (3-point flexural test), which is measured on a sample of 50 mm wide by 80 mm long (corresponding to the length extension in the machine direction).

[0012] The core layer may comprise a thermoplastic material containing PVB. The thermoplastic material preferably has a plasticizer content (total plasticizer content) of no more than 20 wt. %, preferably no more than 18 wt. %, preferably no more than 16 wt. %, preferably no more than 15 wt. %, preferably no more than 12.5 wt. %, preferably no more than 10 wt. %, preferably no more than 8 wt. %, preferably no more than 5 wt. %, more preferably no more than 3 wt. %, yet more preferably no more than 2 wt. %, and yet more preferably no more than 1 % relative to the PVB content. According to a specific embodiment, the core layer may have a plasticizer content of 5 wt. % to 18 wt. % relative to the PVB content and more preferably 8 wt. % to 14 wt. % relative to the PVB content. When referring to the PVB content in this article, this refers to the amount of PVB polymer (resin), excluding any plasticizers, additives or contaminants.

[0013] It may be noted that the core layer may comprise a single layer, or may comprise a plurality of layers (core layer assembly). The term "core layer" may refer to those layers of the surface covering on the back side of the decorative layer or decorative layer assembly, which layers form the structural support of the decorative layer or decorative layer assembly. The optional backing layer (which may comprise one or more resilient foam layers and / or one or more textile layers) is generally not considered to be part of the core layer. The core layer may comprise one or more reinforcement layers, such as, for example, glass or fiber felt, glass or fiber mesh, textile layer, etc., which are embedded in the thermoplastic material or adjacent to the thermoplastic material. The core layer may comprise, for example, two or more thermoplastic materials arranged in different layers.

[0014] Particularly preferred core layer components may include three or more layers, including two outer layers sandwiching one or more inner layers. In this case, the outer layer may preferably contain a first thermoplastic material, and the one or more inner layers contain at least a second thermoplastic material different from the first thermoplastic material. Preferably, the outer layers have (substantially) the same chemical composition. The outer layers may have the same thickness or different thicknesses. The first thermoplastic material of the outer layer is preferably a thermoplastic material containing PVB with a low plasticizer content. The thermoplastic material of the inner layer can be a different thermoplastic material containing PVB with a low plasticizer content. However, it should be noted that the inner layer may alternatively contain a thermoplastic PVB material with a higher plasticizer content.

[0015] According to a preferred embodiment of the present invention, the thermoplastic material may contain deplasticized recycled PVB (recycled PVB from which plasticizer has been removed). The presence of deplasticized recycled PVB in the thermoplastic material can be detected due to the presence of residual contaminants (especially glass particles or plasticizers) that have not been removed during the recycling process. Recycled PVB is usually obtained from laminated glass by mechanical stripping or mechanical rupture, followed by chemical separation in an alkaline aqueous solution. Although separation can be efficient, the residual content of glass particles can characterize recycled PVB. Deplasticized recycled PVB may contain a residual amount of plasticizer, which is preferably less than 20% by weight relative to the PVB content, more preferably less than 10% by weight, more preferably less than 8% by weight, more preferably less than 5% by weight, more preferably less than 3% by weight, more preferably less than 2% by weight, and more preferably less than 1% by weight. It is found that for the present invention, the lower the plasticizer content of PVB, the better the properties of the surface covering are generally. However, experimental product tests have shown that satisfactory results can already be achieved if the plasticizer content of the thermoplastic material does not exceed 20% by weight relative to the PVB content. Better results can be achieved when the plasticizer content of the thermoplastic material does not exceed 15% by weight, more preferably does not exceed 12.5% ​​by weight relative to the PVB content. An interesting advantage of using recycled PVB is the reduced carbon footprint.

[0016] The surface covering may take the form of a surface covering tile comprising a first locking profile along a first edge, a second locking profile along a second edge, the first locking profile and the second locking profile being complementary so that the surface covering tile can be interlocked with another surface covering tile by engaging the first locking profile or the second locking profile of the surface covering tile with the second locking profile or the first locking profile of the other surface covering tile. The expression "surface covering tile" refers to a piece of surface covering, such as for example a brick, a plank, a panel, etc., which piece of surface covering can be assembled with other pieces of flooring in order to be used as a facing on a surface, such as an underlying floorboard. Preferred examples of surface covering tiles include floor tiles, in particular rigid floor tiles.

[0017] The plasticizer content of the thermoplastic may include a content of 0.1% to 20% by weight, preferably 0.1% to 15% by weight, preferably 0.1% to 10% by weight, preferably 0.1% to 5% by weight, more preferably 0.1% to 2% by weight, even more preferably 0.1% to 1% by weight, and most preferably 0.1% to 0.5% by weight of plasticizer, the plasticizer being an aliphatic diester of triethylene glycol or tetraethylene glycol. Preferably, the plasticizer content includes a content of 0.1% to 19.5% by weight, preferably 0.1% to 15% by weight, preferably 0.1% to 10% by weight, preferably 0.1% to 5% by weight, more preferably 0.1% to 2% by weight, even more preferably 0.1% to 1% by weight, and most preferably 0.1% to 0.5% by weight of triethylene glycol bis(2-ethylhexanoate), relative to the PVB content. In addition to the above, the thermoplastic material may also contain a plasticizer suitable for plasticizing the PVB; in particular, esters of polyvalent acids, polyols or oligoether diols, such as, for example, adipates, sebacates, ricinoleates, citrates or phthalates, in particular di-n-hexyl adipate, dibutyl sebacate, dibutyl maleate, dioctyl phthalate, esters of ethylene glycol, diethylene glycol, triethylene glycol or tetraethylene glycol with linear or branched aliphatic carboxylic acids, and mixtures of these esters may be suitable. Esters of aliphatic diols with long-chain aliphatic carboxylic acids may be present, in particular esters of triethylene glycol with aliphatic carboxylic acids containing 6 to 10 C atoms (such as 2-ethylbutyric acid or n-heptanoic acid). One or more plasticizers selected from the group consisting of di-n-hexyl adipate, dibutyl sebacate, dioctyl phthalate, esters of diethylene glycol, triethylene glycol or tetraethylene glycol with linear or branched aliphatic carboxylic acids, in particular triethylene glycol-bis-2-ethylbutyrate, triethylene glycol-bis-n-heptanoate, tetraethylene glycol-bis-n-heptanoate, may be present in the thermoplastic material. Ethers of ethylene glycol may also be considered plasticizers. However, it should be understood that preferably, each of the above plasticizers is present in an amount of up to less than 15% by weight, preferably less than 10% by weight, more preferably less than 5% by weight relative to the PVB content, with the general proviso that the total plasticizer content of the thermoplastic material does not exceed 20% by weight, preferably does not exceed 18% by weight, preferably does not exceed 16% by weight, preferably does not exceed 15% by weight, preferably does not exceed 12.5% ​​by weight, preferably does not exceed 10% by weight, preferably does not exceed 8% by weight, more preferably does not exceed 5% by weight, even more preferably does not exceed 3% by weight, even more preferably does not exceed 2% by weight, and even more preferably does not exceed 1% by weight relative to the PVB content.

[0018] PVB is a random terpolymer consisting of vinyl butyral, vinyl alcohol (VA) and vinyl acetate (VAc) monomeric parts. Virgin PVB is obtained by the condensation reaction of polyvinyl alcohol and butyraldehyde, which itself is usually obtained by the hydrolysis of polyvinyl acetate (resulting in the presence of a small amount of residual VAc). Recycled PVB is available in different grades and is significantly cheaper than virgin PVB. PVB may advantageously contain 17% to 23% by weight, preferably 18% to 21% by weight, and even more preferably 19% to 21% by weight of vinyl alcohol (VA). Preferably, PVB contains up to 3% by weight of VAc, preferably up to 2.5% by weight of VAc, more preferably up to 2% by weight of VAc, even more preferably up to 1.5% by weight of VAc, and most preferably up to 1% by weight of VAc.

[0019] The thermoplastic material may contain fillers dispersed in the thermoplastic polymer matrix, but in certain embodiments, it is not necessary to contain such fillers. A filler content of 10% to 500% by weight relative to the PVB content (10 phr to 500 phr) may be selected. Advantageously, a filler content of 50% to 400% by weight, preferably 80% to 300% by weight, more preferably 100% to 250% by weight relative to the PVB content may be selected. The filler may include: organic filler materials, such as, for example, ground cork, wood flour, cellulose fibers, bleached chemical wood pulp, etc.; and / or mineral filler materials, such as, for example, ground limestone, chalk, magnesium carbonate, dolomite, clay, silica, aluminum hydroxide, magnesium hydroxide, precipitated calcium carbonate, glass fibers and / or glass particles, etc. Layered or fibrous fillers can be used to advantageously modify the mechanical properties of the thermoplastic material, such as the coefficient of thermal expansion. In the context of embodiments of the present invention, available fibrous fillers may include glass fibers or biomass fibers, such as bamboo fibers, hemp fibers, flax fibers, wood fibers, etc., preferably delignified cellulose fibers. Particularly preferred fillers may include inorganic layered fillers, such as, for example, sheet silicates (especially, talc or mica), clay, montmorillonite, glass flakes and layered double hydroxides. The term "layered silicate" refers to a mineral from a silicate (e.g., phyllosilicate) family in which silicate anions are usually arranged in layers. By way of example, phyllosilicates may include minerals from mica, chlorite, kaolinite and serpentine families. Filler or a part of filler may be or may include biochar obtained by thermochemical conversion of biomass in an oxygen-poor environment (reducing atmosphere) or by thermal catalytic depolymerization of biomass, i.e., a solid material rich in carbon. The thermoplastic material may have a biochar content of 50 to 400 wt %, preferably 80 to 300 wt %, more preferably 80 to 250 wt %, and even more preferably 80 to 100 wt %, relative to the PVB content.

[0020] The thermoplastic material may further comprise one or more additives such as, for example, lubricants, stabilizers, fillers and extenders. The additive content of the thermoplastic material may be limited to 10 wt % or less, such as 8 wt % or less or 7 wt % or less, relative to the PVB content.

[0021] The PVB of the thermoplastic material may contain at least 50 wt%, preferably at least 60 wt%, more preferably at least 70 wt%, even more preferably at least 80 wt%, yet more preferably at least 90 wt%, and most preferably 100 wt% of deplasticized recycled PVB.

[0022] Optionally, the thermoplastic material comprises up to 20% by weight, preferably up to 15% by weight, more preferably up to 10% by weight, even more preferably up to 8% by weight, yet more preferably up to 5% by weight, and most preferably up to 2% by weight of a synthetic polymer different from PVB, relative to the PVB content.

[0023] The surface covering may include a decorative layer assembly including a decorative print and a transparent or translucent wear layer, the wear layer optionally including a cross-linked top coat (e.g., containing epoxy resin, polyurethane, polyurethane acrylate, polyester polyurethane acrylate, polyurethane methacrylate and / or polyester polyurethane methacrylate) or consisting of a cross-linked top coat, the decorative layer assembly optionally including an embossed pattern in registration with the decorative print. The wear layer and the top coat may each include one or more layers or be constructed of one or more layers. These layers may be distinguishable or indistinguishable from each other in the final product. The decorative print may include a digital print or a print generated by a similar printing technique such as, for example, rotogravure, gravure, offset printing, etc.

[0024] According to an embodiment, the surface covering may take the form of a rigid surface covering tile (e.g. a floor tile). Such a surface covering tile is preferably rigid in the sense that it exhibits a deformation angle of less than 3 degrees, preferably less than 2 degrees, preferably less than 1 degree, as measured for a rectangular sample tile of dimensions 160 mm x 450 mm, clamped in a horizontal overhang position so as to obtain a 160 mm x 300 mm protruding portion of the sample, the deformation angle being measured 30 seconds after removing the support preventing the protruding portion from deforming under the influence of its own weight.

[0025] The thermoplastic material of the core layer may have the form of at least one foam layer. Additionally or alternatively, the surface covering may include a backing layer, which preferably includes a foam backing. The core layer may be manufactured by direct extrusion through a flat die. In the case of a core layer assembly, coextrusion may be used. As an alternative, the core layer (assembly) may be obtained by compacting (under heat and pressure) a pre-compounded granular material of a thermoplastic material.

[0026] According to a preferred embodiment, a PVC-free surface covering in the form of a surface covering tile (preferably a floor tile) comprises a core layer, a decorative layer or a decorative layer assembly and optionally a backing layer. The core layer is a hard core layer having a deformation angle of less than 10 degrees, preferably less than 7 degrees, more preferably less than 5 degrees, and most preferably less than 3 degrees, as measured by the above-mentioned deformation test. The core layer comprises a thermoplastic material containing PVB, wherein the thermoplastic material has a (total) plasticizer content of no more than 2% by weight and more preferably no more than 1% by weight relative to the PVB content. The PVB of the thermoplastic material is preferably composed of deplasticized recycled PVB containing 17% to 23% by weight, preferably 18% to 21% by weight of vinyl alcohol. The plasticizer content may include a content of 0.1% to 2% by weight of a plasticizer relative to the PVB content, the plasticizer being an aliphatic diester of triethylene glycol or tetraethylene glycol, in particular triethylene glycol bis (2-ethylhexanoate). The thermoplastic material further preferably comprises a synthetic polymer different from PVB in an amount of up to 10 wt % relative to the PVB content. The thermoplastic material preferably has a filler content of 50 wt % to 400 wt %, more preferably 80 wt % to 300 wt %, and even more preferably 100 wt % to 250 wt % relative to the PVB content. The thermoplastic material preferably comprises one or more additives, such as, for example, lubricants, stabilizers, filler extenders, the additive content of the thermoplastic material being less than 10 wt % relative to the PVB content in total. The surface covering brick preferably comprises a first locking profile along a first edge, a second locking profile along a second edge, the first locking profile and the second locking profile being constructed complementary to each other, so that the surface covering brick can be interlocked with another surface covering brick by engaging the first locking profile or the second locking profile of the surface covering brick with the second locking profile or the first locking profile of another surface covering brick.

[0027] According to another embodiment, a PVC-free surface covering in the form of a surface covering tile (preferably a floor tile) comprises a core layer, a decorative layer or a decorative layer assembly and optionally a backing layer. The core layer is a hard core layer having a deformation angle of less than 10 degrees, preferably less than 7 degrees, more preferably less than 5 degrees, most preferably less than 3 degrees, as measured by the above-mentioned deformation test. The core layer comprises a thermoplastic material containing PVB, wherein the thermoplastic material has a (total) plasticizer content of 5% to 18% by weight and more preferably 8% to 14% by weight relative to the PVB content. The PVB of the thermoplastic material preferably consists of deplasticized recycled PVB containing 17% to 23% by weight, preferably 18% to 21% by weight of vinyl alcohol. The plasticizer content may include a content of 5% to 18% by weight and more preferably 8% to 14% by weight of plasticizer relative to the PVB content, the plasticizer being an aliphatic diester of triethylene glycol or tetraethylene glycol, in particular triethylene glycol bis(2-ethylhexanoate). The thermoplastic material further preferably comprises a synthetic polymer different from PVB in an amount of up to 10% by weight relative to the PVB content. The thermoplastic material preferably has a filler content of 50% to 400% by weight, more preferably 80% to 300% by weight, and even more preferably 100% to 250% by weight relative to the PVB content. The thermoplastic material preferably comprises one or more additives, such as, for example, lubricants, stabilizers, filler compatibilizers, the additive content of the thermoplastic material being less than 10% by weight relative to the PVB content. The surface covering brick preferably comprises a first locking profile along a first edge, a second locking profile along a second edge, the first locking profile and the second locking profile being constructed complementarily to each other so that the surface covering brick can be interlocked with another surface covering brick by engaging the first locking profile or the second locking profile of the surface covering brick with the second locking profile or the first locking profile of another surface covering brick. The PVC-free surface covering may also comprise at least one reinforcing fiber layer, preferably at least two reinforcing fiber layers, such as a felt, a mesh or a textile made of reinforcing fibers (e.g., glass fibers, aramid fibers, ultra-high molecular weight polyethylene (UHMWPE) fibers, etc.). The addition of one or more reinforcing fiber layers in the PVC-free surface covering may allow controlling the thermal expansion of the core layer, which may occur due to a plasticizer content of 5 wt. % to 18 wt. % and more preferably 8 wt. % to 14 wt. % relative to the PVB content.

[0028] According to an even more preferred variant of the above preferred embodiment, the surface covering brick comprises a decorative layer assembly comprising a decorative print and a transparent or translucent wear layer, the wear layer optionally comprising or consisting of a cross-linked top coat, the decorative layer assembly optionally comprising an embossed pattern in registration with the decorative print. The surface covering brick preferably has a deformation angle of less than 3 degrees, more preferably less than 2 degrees, and even more preferably less than 1 degree, as measured by the above deformation test. The thermoplastic material of the core layer may take the form of one or more foam layers. The surface covering brick may further comprise a backing layer, which preferably comprises a foam backing.

[0029] Terms such as "upper," "lower," "lower," "upper," "horizontal," "vertical," "above," "below," "top," and "bottom," and derivatives thereof (e.g., "horizontally," "upward," etc.) refer to the orientation of a surface covering tile when laid with its finished surface oriented upward. For a floor tile or flooring, the orientation corresponds to the position of the floor tile or flooring when in use (i.e., laid on a baseboard). Terms referring to the orientation of a surface covering are adopted herein for convenience of description and as a naming convention. They should be interpreted as referring to the relative orientation of different components, but are not meant to imply a particular absolute orientation of a tile or flooring assembly in space. For example, arranging the finished surface of a tile upside down should not prevent that finished surface from being considered the top surface.

[0030] As used herein, the qualifier "decorative" is intended to imply that the article thus defined (such as a surface covering) remains visible in normal use (as a finished article). However, the use of this term should not be understood as implying any particular aesthetic appearance or any particular aesthetic design. The expression "decorative layer" means a layer having a decorative pattern. Examples of decorative layers include printed layers, in particular rotogravure printed layers and digitally printed layers.

[0031] The expression "surface normal" refers to the direction perpendicular to the surface of the decorative side (top side) of the surface covering.

[0032] As used herein, the expression "thermoplastic material" encompasses the following plastic polymer material blends, which become flexible or moldable at a certain elevated temperature and solidify when cooled, and the solidification is reversible by heating the material to the elevated temperature again. Thermoplastic (polymer) materials may include thermoplastic polymers and optionally one or more plasticizers, (inorganic or organic) fillers and other additives (e.g., impact modifiers, compatibilizers, processing aids). Thermoplastic polymers include, for example: polyacrylic acid, polyacrylate, polyamide, polyester, polylactic acid (PLA), polycarbonate, polyethersulfone (PES), polyetheretherketone (PEEK), polyetherimide (PEI), polyethylene, polypropylene (PP), polystyrene, polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), acrylonitrile butadiene styrene (ABS), etc. In this article, thermoplastic material includes PVB. Other thermoplastic polymers may be present in the thermoplastic material, but according to a preferred embodiment, the thermoplastic material contains significantly less other synthetic polymers (in particular, thermoplastic polymers) than PVB. In the context of this document, two or more initially separate thermoplastic materials that have been intimately blended together must be considered as one thermoplastic material in their blended state. Therefore, when referring to a surface covering or any component thereof comprising two or more thermoplastic materials in this document, it should be understood that the two or more thermoplastic materials are present in physically separate volumes, such as in different layers, in different distinguishable pellets, etc.

[0033] In contrast to "thermoplastic", the expression "cross-linked" defines a polymer material (such as, for example, a topcoat) that has been irreversibly hardened by crosslinking between polymer chains to generate an infusible and insoluble polymer network. Cross-linked (polymer) materials may include, for example, one or more thermosetting or radiation-cured polymers. Radiation-cured polymers include in particular UV-cured and / or electron beam-cured polymers. Cross-linked (polymer) materials may contain thermosetting and / or radiation-cured polymers (e.g., polyurethanes, polyimides, epoxy resins, etc.) and optionally one or more plasticizers, (inorganic or organic) fillers and further additives (e.g., impact modifiers, photoinitiators, antioxidants, etc.) or processing aids.

[0034] In this document, the verb "comprise" and the expression "consisting of" are used as open transition phrases, meaning "including" or "consisting of at least..." Unless the context implies otherwise, the use of singular word forms is intended to include the plural, except when the cardinal number "one" is used: "one" in this document means "exactly one". Ordinal numbers ("first", "second", etc.) are used in this document to distinguish different instances of common objects; the use of these expressions does not imply a particular order, importance, hierarchy, or quantitative limitation. In addition, when multiple instances of an object are referred to by ordinals, this does not necessarily mean that there are no other instances of the object (unless clearly inferred from the context). When this specification refers to "an embodiment", "one embodiment", "various embodiments", etc., this means that the features of those embodiments can be used in the combinations clearly presented, and these features can be combined across the embodiments without departing from the invention, unless it is inferred from the context that the features cannot be combined.

[0035] (Residual) plasticizer content can be measured using different methods. For example, nuclear magnetic resonance (NMR) can be used, for example, MQC23+ desktop NMR analyzer (Oxford Instruments) can be used. Alternative methods for measuring plasticizer content include dissolving the plasticizer in an organic solvent, and determining the plasticizer content by post-distillation gravimetric analysis, gas chromatography and / or infrared spectroscopy. The preferred method uses DMA (dynamic mechanical analysis) to determine the glass transition temperature Tg of the sample according to ISO 6721-11:2019 (determine the temperature of the peak in the loss factor (tan (δ)) versus temperature curve). Preferably, ISO 6721-11:2019 procedure B (temperature rate of 2.5K / min; frequency of 1Hz) is used. If the sample has a known composition (except for plasticizer content), the plasticizer content is obtained from a calibration curve or calibration table (lookup table) that links Tg to the plasticizer content of a given composition. If the composition of the sample is initially unknown, its different components (resin, filler, plasticizer type, etc.) are determined in a first step. Different comparison samples are then prepared with different accurately metered amounts of plasticizer and a calibration curve or calibration table (lookup table) is determined that relates Tg to the plasticizer content of a given composition by measuring the Tg of the comparison samples using the tan(δ) method according to ISO 6721-11:2019. The calibration curve or calibration table can then be used to determine the plasticizer content of the sample being examined. The indication of the plasticizer content in this document refers to the preferred method based on the determination of the glass transition temperature and a reference value (calibration curve or table). BRIEF DESCRIPTION OF THE DRAWINGS

[0036] By way of example, various preferred non-limiting embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0037] Figure 1 is a schematic cross-sectional view of a surface-covered brick according to an embodiment of the present invention;

[0038] Figure 2 is a diagram of a deformation test showing an overhanging specimen in an initial supported position; and

[0039] Figure 3 is an illustration of a deformation test showing the overhanging specimen after the support of the protruding portion has been removed. DETAILED DESCRIPTION

[0040] LVT floors assembled by click are one of the fastest growing flooring categories due to numerous advantages (easy installation, suitable for renovation (including uneven base floors), water-tightness...). The core layer of these products is quite thick (e.g. 3mm to 6mm) and is usually semi-rigid or rigid (hardness ranges from 0.5GPa to 2GPa and 2GPa to 10GPa (or higher) respectively). Usually, filled PVC is used as base polymer, but there is a growing demand for PVC alternatives suitable for LVT floors (complying with some local regulations, concerns about PVC in some regions...). According to an aspect of the present invention, a LVT floor based on PVB is proposed. According to a particularly preferred aspect, such a PVB-based floor tile is substantially or completely free of PVC.

[0041] Figure 1 A "vinyl" type floor panel 10 is shown according to an embodiment of the present invention. The floor panel 10 may be a rigid luxury vinyl tile (LVT). The floor panel 10 has a top surface 12, a bottom surface 14, and at least four side edges. Figure 1 A first edge 16 and a complementary shaped second edge 18 are shown in more detail. The first edge 16 may include a first locking profile featuring a tongue 20, and the second edge 18 may include a second locking profile featuring a groove 22. The first locking profile and the second locking profile may be configured to complement each other to mechanically engage and interlock with a second connection profile and a first connection profile, respectively, of another floor panel of the same type. In particular, the tongue 20 and the groove 22 may be of complementary shape so as to enable a tongue-and-groove connection between adjacent panels. The groove 22 may be defined at its bottom by a base 24.

[0042] The floor panel 10 can be a layered structure and includes a core layer 26 and a decorative layer assembly 28 disposed on the core layer 26. The core layer 26 can be rigid. The decorative layer assembly 28 can include a print layer 28a (e.g., a print substrate carrying one or more digital printing ink layers) and a transparent or translucent wear layer 28b. The print layer 28a can also be printed directly on the core layer 26. As another possibility, the print layer 28a can be printed on the back side of the wear layer 28b, and then the wear layer 28b and the core layer are laminated so as to sandwich the print layer 28a. A backing layer 30 (e.g., a resilient foam layer, a felt layer, or a fleece fabric layer) can be disposed on the bottom side 14 of the floor panel 10.

[0043] The core layer 26 may include multiple sub-layers, such as one or more PVB-based thermoplastic layers 26a, 26b, 26c and one or more reinforcing fiber layers 26d, 26e. The fiber layers 26d, 26e may include a felt, a mesh, or a textile made of reinforcing fibers (e.g., glass fibers, aramid fibers, ultra-high molecular weight polyethylene (UHMWPE) fibers, etc.). One or more fiber layers 26d, 26e may be embedded in or adjacent to one or more PVB-based thermoplastic layers 26a, 26b, 26c. If the core layer 26 includes multiple PVB-based thermoplastic sub-layers 26a, 26b, 26c, these PVB-based thermoplastic sub-layers may be made of thermoplastic materials of the same composition or of two or more different compositions. However, it may be worth noting that the core layer 26 may alternatively include the same PVB material throughout its height.

[0044] The floor panel 10 may have an overall height in the range from 2 mm to 10 mm, preferably in the range of 2.5 mm to 9 mm, and most preferably in the range of 2.5 mm to 8.5 mm.

[0045] The core layer 26 may have a deformation angle (α) of less than 10 degrees, preferably less than 7 degrees, more preferably less than 5 degrees, and most preferably less than 3 degrees, as measured by a deformation test. Figure 2 and Figure 3The deformation test illustrated, prepares a 160mm×450mm rectangular sample 32 of the core layer 26 (in the illustrated embodiment, including sublayers 26a, 26b, 26c, 26d, 26e) or other layers (components). The sample 32 is then clamped in a horizontal overhang position to obtain a 160mm×300mm rectangular protrusion of the sample. The protrusion is initially supported by a removable horizontal support member over the entire length and width of the protrusion. The support is then removed so that the protrusion bends under its own weight. The deformation angle α is measured 30 seconds after removing the support 34 that prevents the protrusion from deforming under the influence of its own weight. The deformation angle α corresponds to the angle between the horizontal support plane 40 and the plane extending from the edge 36 of the support member (the protrusion protrudes from the edge) to the lowermost end 38 of the protrusion. The core layer 26 may also exhibit a flexural modulus of more than 500MPa, preferably more than 1000MPa, more preferably more than 1500MPa, and most preferably more than 3000MPa. The flexural modulus is determined from the slope of the stress-strain curve produced by a flexural test (3-point flexural test), measured on a sample 50 mm wide by 80 mm long (corresponding to the length extension in the machine direction).

[0046] The PVB-based thermoplastic material of the core layer 26 may have a plasticizer content (total plasticizer content) of no more than 20 wt. %, preferably no more than 18 wt. %, preferably no more than 16 wt. %, preferably no more than 15 wt. %, preferably no more than 12.5 wt. %, preferably no more than 10 wt. %, preferably no more than 8 wt. %, more preferably no more than 5 wt. %, more preferably no more than 3 wt. %, yet more preferably no more than 2 wt. %, and yet yet more preferably no more than 1 wt. % relative to the PVB content. More specifically, the PVB-based thermoplastic material comprises a content of 0.1 to 19.5 wt. %, preferably 0.1 to 15 wt. %, preferably 0.1 to 10 wt. %, preferably 0.1 to 5 wt. %, more preferably 0.1 to 2 wt. %, still more preferably 0.1 to 1 wt. %, and most preferably 0.1 to 0.5 wt. % of a plasticizer, the plasticizer being an aliphatic diester of triethylene glycol or tetraethylene glycol (such as, for example, triethylene glycol bis(2-ethylhexanoate)), relative to the PVB content.

[0047] Thermoplastic materials based on PVB preferably contain deplasticized recycled PVB.Thermoplastic materials based on PVB may contain virgin PVB, but according to a preferred embodiment, all PVB are deplasticized recycled PVB.PVB may contain 17 wt % to 23 wt %, preferably 18 wt % to 21 wt %, more preferably 19 wt % to 21 wt % of vinyl alcohol (VA).Preferably, PVB contains up to 3 wt % of VAc, preferably up to 2.5 wt % of VAc, more preferably up to 2 wt % of VAc, more preferably up to 1.5 wt % of VAc, and most preferably up to 1 wt % of VAc.Thermoplastic materials based on PVB preferably contain up to 20 wt %, preferably up to 15 wt %, more preferably up to 10 wt %, more preferably up to 8 wt %, more preferably up to 5 wt %, and most preferably up to 2 wt % of synthetic polymers different from PVB relative to the PVB content.

[0048] The PVB-based thermoplastic material may or may not contain fillers. A filler content of 10% to 500% by weight relative to the PVB content may be selected. Advantageously, a filler content of 50% to 400% by weight, preferably 80% to 300% by weight, more preferably 100% to 250% by weight relative to the PVB content may be selected. The filler may include: organic filler materials, such as, for example, biochar, ground cork, wood flour, cellulose fibers, bleached chemical wood pulp, etc.; and / or mineral filler materials, such as, for example, ground cork limestone, talc, chalk, magnesium carbonate, dolomite, clay, silica, aluminum hydroxide, pigments, etc.

[0049] The PVB-based thermoplastic material may further comprise one or more additives, such as, for example, lubricants, stabilizers, fillers and extenders. The additive content of the thermoplastic material may be limited to 10 wt % or less, such as 8 wt % or less or 7 wt % or less, relative to the PVB content.

[0050] Examples of PVB-based thermoplastic compositions for floor panels according to preferred embodiments of the present invention are indicated in the following Table 1. The amounts of ingredients or components are expressed in parts by weight.

[0051] Table 1 - PVB-based thermoplastic compositions

[0052]

[0053]

[0054] In Examples E1 to E11, the medium molecular weight virgin PVB is Mowital B 60T from Kuraray, and the high molecular weight virgin PVB is Mowital B 75H from Kuraray. The deplasticized recycled PVB is obtained by extracting plasticizer from recycled PVB flakes such as purchased from Shark Solutions. Calcium carbonate is Omyacarb 15-VA from Omya, talc is Luzenac ST30 from Imerys, and biochar is dust waste from the pyrolysis process of Carbonex. Different lubricant packages are used according to the embodiments, and the lubricant packages include oxidized PE wax (e.g., Wiraten XW-12 from Wiwax), stearin (Radiacid 0444 from Oleon) and / or zinc stearate (e.g., Ligastar Zn 101 / 6 from Peter Greven) as main components. The stabilizer package includes a blend of Irganox (trademark) 1010 from BASF and Irgafos (trademark) 168 from BASF. The ATH filler is Alfrimal (trademark) 447S from Alpha Calcit. The samples of Examples E1 to E11 are extruded using a twin-screw extruder equipped with a flat die. The melting temperature is close to 180° C. (e.g., included between 180° C. and 210° C.).

[0055] The (residual) plasticizer content of the compositions according to the examples was 0 in E1, E2 and E3, 5.2 wt.-% relative to the PVB content in E4, 7.8 wt.-% relative to the PVB content in E5, 2 wt.-% relative to the PVB content in E6, less than 1 wt.-% relative to the PVB content in E7, 1.2 wt.-% relative to the PVB content in E8, 13.9 wt.-% relative to the PVB content in E9 and E10, and 19.6 wt.-% relative to the PVB content in E11.

[0056] Table 2 summarizes some properties of the PVB-based thermoplastic materials according to Examples E1 to E11.

[0057] Table 2 - PVB-based thermoplastic compositions

[0058]

[0059] Linear thermal expansion coefficient (10 -5 / ℃) have been measured at temperatures ranging from 35 ℃ to 65 ℃. The flexural modulus is determined each time from the slope of the stress-strain curve generated by the flexural test (3-point flexural test), which is measured on a sample of 50 mm wide × 80 mm long (corresponding to the length extension in the machine direction). For the 3-point bending setup, a span of 64 mm is used. Before the start of the test, a preload is applied at a speed of 5 mm / min (until a force of 5 N is reached). The load is then displaced at a rate of 4% / min until fracture. The flexural modulus is determined as the initial slope of the stress-strain curve. The flexural modulus has been measured on samples equilibrated at 23 ℃. The fracture stresses indicated in Table 2 correspond to the corresponding maximum recorded stresses.

[0060] As indicated in Table 2, it was found that hard PVB exhibits good thermomechanical properties (fracture stress, low thermal expansion, good planar stability, ...) and is therefore suitable for use in the core layer of rigid LVT with locking connectors. It may be noted that the surface covering according to the present invention may have a hardness that cannot be achieved by conventional plasticized PVB.

[0061] Table 3 summarizes some properties of the core layers (CL) made of PVB-based thermoplastic materials according to Examples E7, E8, E9, E10 and E11.

[0062] Table 3 - Core Layer

[0063]

[0064] The glass mat used in these examples is Adfors (trademark) U35 from Adfors. The core layers CL1, CL4, CL6 and CL7 are extruded using a twin-screw extruder equipped with a flat die. The core layers CL2, CL3 and CL5 are obtained by compacting (under heat and pressure) pre-compounded pellets of thermoplastic material.

[0065] As indicated in Table 3, all core layers according to the invention exhibit good thermomechanical properties (fracture stress, low thermal expansion, good planar stability, ...) and are therefore suitable for use in rigid LVT with locking connectors. It must be noted that by adding at least one reinforcement layer in the core layer, the linear thermal expansion coefficient can be significantly reduced.

[0066] Floors assembled from floor tiles according to the invention comprising a PVB-based composition according to Examples E1 to E11 were subjected to the castor wheelchair test as specified in standard ISO 4918:2016. The floor tiles comprise locking connectors along their edges. After 25,000 cycles, no damage was observed on the floor surface and the locking connectors.

[0067] Although various specific embodiments have been described in detail herein, it will be appreciated by those skilled in the art that various modifications and alternatives to these details may be developed based on the overall teachings of the present disclosure. Therefore, the specific arrangements disclosed are intended only to illustrate and not to limit the scope of the present invention, which is given by the full scope of the appended claims and any and all equivalents thereof.

[0068] Particularly preferred embodiments of the invention are defined in the following numbered clauses (NC).

[0069] NC 1: A surface covering, preferably a PVC-free surface covering, comprising a core layer, a decorative layer or decorative layer assembly and optionally a backing layer, wherein: the core layer is a hard core layer, the hard core layer having a deformation angle of less than 5 degrees, most preferably less than 3 degrees, as measured at 23°C for a rectangular core layer sample of dimensions 160mm×450mm, the rectangular core layer sample being clamped in a horizontal overhang position so as to obtain a 160mm×300mm overhang of the sample, the deformation angle being removed to prevent the overhang from bending under its own weight The core layer comprises a thermoplastic material containing PVB, measured 30 seconds after the impact of the deformed support, wherein the thermoplastic material has a plasticizer content of not more than 20% by weight, preferably not more than 18% by weight, preferably not more than 16% by weight, preferably not more than 15% by weight, preferably not more than 12.5% ​​by weight, preferably not more than 10% by weight, preferably not more than 8% by weight, more preferably not more than 5% by weight, more preferably not more than 3% by weight, yet more preferably not more than 2% by weight, and yet more preferably not more than 1% by weight, relative to the PVB content.

[0070] NC 2: The surface covering according to NC 1, wherein the thermoplastic material comprises deplasticized recycled PVB.

[0071] NC 3: A surface covering according to NC 1 or NC 2, which is in the form of a surface covering brick, which includes a first locking profile along a first edge and a second locking profile along a second edge, and the first locking profile and the second locking profile are complementary, so that the surface covering brick can be interlocked with another surface covering brick by engaging the first locking profile or the second locking profile of the surface covering brick with the second locking profile or the first locking profile of the other surface covering brick.

[0072] NC 4: The surface covering according to any one of NC 1 to NC 3, wherein the plasticizer content comprises a content of plasticizer not exceeding 20 wt. %, preferably not exceeding 15 wt. %, preferably not exceeding 10 wt. % relative to the PVB content, the plasticizer being an aliphatic diester of triethylene glycol or tetraethylene glycol.

[0073] NC 5: Surface covering according to NC 4, wherein the plasticizer content comprises a content of triethylene glycol bis(2-ethylhexanoate) of not more than 19.5 wt.-%, preferably not more than 15 wt.-%, preferably not more than 10 wt.-%, relative to the PVB content.

[0074] NC 6: Surface covering according to any one of NC 1 to NC 5, wherein the PVB contains 17 to 23 wt. %, preferably 18 to 21 wt. % of vinyl alcohol.

[0075] NC 7: Surface covering according to any one of NC 1 to NC 6, wherein the thermoplastic has a filler content of 50 to 400 wt.-%, preferably 80 to 300 wt.-%, more preferably 100 to 250 wt.-%, relative to the PVB content.

[0076] NC 8: Surface covering according to any one of NC 1 to NC 7, wherein the thermoplastic material comprises one or more additives, such as for example lubricants, stabilizers, fillers and compatibilizers, the additive content of the material being less than 10 wt. % relative to the PVB content.

[0077] NC 9: A surface covering according to any one of NC 1 to NC 8, wherein the PVB of the thermoplastic material comprises at least 50 wt. %, preferably at least 60 wt. %, more preferably at least 70 wt. %, even more preferably at least 80 wt. %, yet more preferably at least 90 wt. %, and most preferably 100 wt. % of deplasticized recycled PVB.

[0078] NC 10: A surface covering according to any one of NC 1 to NC 9, wherein the thermoplastic material comprises at most 20% by weight, preferably at most 15% by weight, more preferably at most 10% by weight, more preferably at most 8% by weight, still more preferably at most 5% by weight, yet more preferably at most 2% by weight, and most preferably at most 1% by weight of a synthetic polymer different from PVB, relative to the PVB content.

[0079] NC 11: A surface covering according to any one of NC 1 to NC 10, wherein the surface covering comprises a decorative layer assembly comprising a decorative print and a transparent or translucent wear layer, the wear layer optionally comprising or consisting of a cross-linked top coat, the decorative layer assembly optionally comprising an embossed pattern registered with the decorative print.

[0080] NC 12: A surface covering according to any one of NC 1 to NC 11, which is in the form of a rigid floor tile, which exhibits a deformation angle of less than 3 degrees, preferably less than 2 degrees, preferably less than 1 degree, as measured at 23°C for a rectangular sample tile with dimensions of 160mm×450mm, which is clamped in a horizontal overhang position so as to obtain a 160mm×300mm protrusion of the sample, the deformation angle being measured 30 seconds after removing the support that prevents the protrusion from deforming under the influence of its own weight.

[0081] NC 13: Surface covering according to any of NC 1 to NC 13, wherein the thermoplastic material of the core layer has the form of at least one foam layer and / or wherein the surface covering comprises a backing layer, preferably comprising a foam backing.

[0082] NC 14: Surface covering according to NC 1 to NC 10 considered in combination, wherein the thermoplastic material has a plasticizer content of not more than 2% by weight relative to the PVB content, wherein the PVB of the thermoplastic material consists of deplasticized recycled PVB, and wherein the thermoplastic material contains at most 10% by weight of a synthetic polymer different from PVB relative to the PVB content.

[0083] NC 15: Surface covering according to NC 11 to NC 14 considered in combination.

[0084] NC 16: A surface covering, preferably a PVC-free surface covering, comprising a core layer, a decorative layer or a decorative layer assembly and optionally a backing layer, wherein: the core layer is a hard core layer, the hard core layer having a deformation angle of less than 5 degrees, most preferably less than 3 degrees, as measured at 23°C for a rectangular core layer sample of dimensions 160 mm×450 mm, the rectangular core layer sample being clamped in a horizontal overhang position so as to obtain a 160 mm×300 mm protruding part of the sample, the deformation angle being measured 30 seconds after removing a support that prevents the protruding part from deforming under the influence of its own weight, the core layer comprising a thermoplastic material containing PVB, wherein the thermoplastic material has a plasticizer content of not more than 12.5% ​​by weight, preferably not more than 10% by weight, preferably not more than 8% by weight, more preferably not more than 5% by weight, more preferably not more than 3% by weight, still more preferably not more than 2% by weight, and still more preferably not more than 1% by weight relative to the PVB content.

[0085] NC 17: The surface covering according to NC 16, wherein the thermoplastic material comprises deplasticized recycled PVB.

[0086] NC 18: A surface covering according to NC 16 or NC 17, which is in the form of a surface covering brick, which includes a first locking profile along a first edge and a second locking profile along a second edge, and the first locking profile and the second locking profile are complementary, so that the surface covering brick can be interlocked with another surface covering brick by engaging the first locking profile or the second locking profile of the surface covering brick with the second locking profile or the first locking profile of the other surface covering brick.

[0087] NC 19: The surface covering according to any one of NC 16 to NC 18, wherein the plasticizer content comprises a content of 0.1 to 20 wt. %, preferably 0.1 to 15 wt. %, preferably 0.1 to 10 wt. % of plasticizer relative to the PVB content, the plasticizer being an aliphatic diester of triethylene glycol or tetraethylene glycol.

[0088] NC 20: Surface covering according to NC 19, wherein the plasticizer content comprises a content of triethylene glycol bis(2-ethylhexanoate) of less than 12% by weight relative to the PVB content.

[0089] NC 21: Surface covering according to any one of NC 16 to NC 20, wherein the PVB contains 18 to 21 wt. % of vinyl alcohol.

[0090] NC 22: Surface covering according to any one of NC 16 to NC 21, wherein the thermoplastic material contains one or more fillers and wherein the thermoplastic has a filler content of 50 to 400 wt.-%, preferably 80 to 300 wt.-%, more preferably 100 to 250 wt.-% relative to the PVB content.

[0091] NC 23: Surface covering according to any one of NC 16 to NC 22, wherein the thermoplastic material comprises one or more additives, such as for example lubricants, stabilizers, fillers and compatibilizers, the additive content of the material being less than 10 wt. % relative to the PVB content.

[0092] NC 24: A surface covering according to any one of NC 16 to NC 23, wherein the PVB of the thermoplastic material comprises at least 50 wt. %, preferably at least 60 wt. %, more preferably at least 70 wt. %, even more preferably at least 80 wt. %, yet more preferably at least 90 wt. %, and most preferably 100 wt. % of deplasticized recycled PVB.

[0093] NC 25: A surface covering according to any one of NC 16 to NC 24, wherein the thermoplastic material contains at most 20 wt.-%, preferably at most 15 wt.-%, more preferably at most 10 wt.-%, even more preferably at most 8 wt.-%, yet more preferably at most 5 wt.-%, and most preferably at most 2 wt.-% of a synthetic polymer different from PVB, relative to the PVB content.

[0094] NC 26: A surface covering according to any one of NC 16 to NC 25, wherein the surface covering comprises a decorative layer assembly comprising a decorative print and a transparent or translucent wear layer, the wear layer optionally comprising or consisting of a cross-linked top coat, the decorative layer assembly optionally comprising an embossed pattern registered with the decorative print.

[0095] NC 27: A surface covering according to any one of NC 16 to NC 26, which is in the form of a rigid floor tile, which exhibits a deformation angle of less than 3 degrees, preferably less than 2 degrees, preferably less than 1 degree, as measured at 23°C for a rectangular sample tile of dimensions 160mm×450mm, which is clamped in a horizontal overhang position so as to obtain a 160mm×300mm protrusion of the sample, the deformation angle being measured 30 seconds after removing the support that prevents the protrusion from deforming under the influence of its own weight.

[0096] NC 28: Surface covering according to any of NC 16 to NC 27, wherein the thermoplastic material of the core layer has the form of at least one foam layer and / or wherein the surface covering comprises a backing layer, preferably comprising a foam backing.

[0097] NC 29: Surface covering according to NC 16 to NC 25 considered in combination, wherein the thermoplastic material has a plasticizer content of not more than 2% by weight relative to the PVB content, wherein the PVB of the thermoplastic material consists of deplasticized recycled PVB, and wherein the thermoplastic material contains up to 10% by weight of a synthetic polymer different from PVB relative to the PVB content.

[0098] NC 30: Surface covering according to NC 26 to NC 29 considered in combination.

[0099] NC 31: Surface covering according to any one of NC 1 to NC 30, wherein the thermoplastic material comprises one or more lamellar fillers.

[0100] NC 32: The surface covering according to NC 31, wherein the one or more layered fillers comprise phyllosilicates.

[0101] NC 33: Surface covering according to NC 31, wherein the one or more lamellar fillers comprise talc.

[0102] NC 34: A surface covering according to NC 31, wherein the one or more lamellar fillers comprises talc.

[0103] NC 35: A surface covering according to NC 31, wherein the one or more layered fillers comprise clay.

[0104] NC 35: Surface covering according to NC 31, wherein the thermoplastic material has a lamellar filler content of 50% to 400% by weight.

[0105] NC 36: Surface covering according to NC 31, wherein the thermoplastic material has a lamellar filler content of 100% to 300% by weight.

Claims

1. A surface covering, preferably a PVC-free surface covering, comprising a core layer, a decorative layer or a decorative layer assembly and optionally a backing layer, wherein: the core layer is a rigid core layer having a deformation angle of less than 10 degrees, preferably less than 7 degrees, more preferably less than 5 degrees, most preferably less than 3 degrees, as measured at 23°C for a rectangular core layer sample of dimensions 160 mm x 450 mm, clamped in a horizontal overhang position so as to obtain a 160 mm x 300 mm protruding portion of the sample, the deformation angle being measured 30 seconds after removing a support preventing the protruding portion from deforming under the influence of its own weight, The core layer comprises a thermoplastic material containing PVB, wherein the thermoplastic material has a plasticizer content of not more than 20 wt %, preferably not more than 18 wt %, preferably not more than 16 wt %, preferably not more than 15 wt %, preferably not more than 12.5 wt %, preferably not more than 10 wt %, preferably not more than 8 wt %, more preferably not more than 5 wt %, more preferably not more than 3 wt %, yet more preferably not more than 2 wt %, and yet more preferably not more than 1 wt % relative to the PVB content.

2. The surface covering of claim 1, wherein the thermoplastic material comprises deplasticized recycled PVB.

3. A surface covering according to claim 1 or 2, wherein the core layer has a flexural modulus exceeding 500 MPa, preferably exceeding 1000 MPa, more preferably exceeding 1500 MPa, and most preferably exceeding 3000 MPa.

4. The surface covering according to claims 1 to 3, is in the form of a surface covering brick, the surface covering brick comprising a first locking profile along a first edge and a second locking profile along a second edge, the first locking profile and the second locking profile being complementary so that the surface covering brick can be interlocked with the other surface covering brick by engaging the first locking profile or the second locking profile of the surface covering brick with the second locking profile or the first locking profile of the other surface covering brick.

5. The surface covering according to any one of claims 1 to 4, wherein the plasticizer content comprises a content of 0.1 to 20 wt. %, preferably 0.1 to 15 wt. %, preferably 0.1 to 10 wt. % of plasticizer relative to the PVB content, the plasticizer being an aliphatic diester of triethylene glycol or tetraethylene glycol.

6. The surface covering according to claim 5, wherein the plasticizer content comprises a content of triethylene glycol bis(2-ethylhexanoate) of 0.1 wt.-% to 19.5 wt.-%, preferably 0.1 wt.-% to 15 wt.-%, preferably 0.1 wt.-% to 10 wt.-%, relative to the PVB content.

7. The surface covering according to any one of claims 1 to 6, wherein the PVB comprises 17 to 23 wt. %, preferably 18 to 21 wt. % vinyl alcohol.

8. The surface covering according to any one of claims 1 to 7, wherein the thermoplastic has a filler content of 50 to 400 wt.-%, preferably 80 to 300 wt.-%, more preferably 100 to 250 wt.-%, relative to the PVB content.

9. A surface covering according to any one of claims 1 to 8, wherein the thermoplastic material comprises one or more additives, such as for example lubricants, stabilizers, fillers and extenders, the additive content of the material being less than 10% by weight relative to the PVB content.

10. The surface covering according to any one of claims 1 to 9, wherein the PVB of the thermoplastic material comprises at least 50 wt. %, preferably at least 60 wt. %, more preferably at least 70 wt. %, even more preferably at least 80 wt. %, yet more preferably at least 90 wt. %, and most preferably 100 wt. % of deplasticized recycled PVB.

11. The surface covering according to any one of claims 1 to 10, wherein the thermoplastic material comprises at most 20 wt.-%, preferably at most 15 wt.-%, more preferably at most 10 wt.-%, even more preferably at most 8 wt.-%, yet more preferably at most 5 wt.-%, and most preferably at most 2 wt.-% of a synthetic polymer different from PVB, relative to the PVB content.

12. A surface covering according to any one of claims 1 to 11, wherein the surface covering comprises a decorative layer assembly comprising a decorative print and a transparent or translucent wear layer, the wear layer optionally comprising or consisting of a cross-linked top coat, the decorative layer assembly optionally comprising an embossed pattern registered with the decorative print.

13. A surface covering according to any one of claims 1 to 12, in the form of a rigid floor tile, which exhibits a deformation angle of less than 3 degrees, preferably less than 2 degrees, preferably less than 1 degree, as measured at 23°C for a rectangular sample tile of dimensions 160 mm x 450 mm, clamped in a horizontal overhang position so as to obtain a 160 mm x 300 mm protrusion of the sample, the deformation angle being measured 30 seconds after removing a support preventing the protrusion from deforming under the influence of its own weight.

14. A surface covering according to any one of claims 1 to 13, wherein the thermoplastic material of the core layer has the form of at least one foam layer and / or wherein the surface covering comprises a backing layer, preferably comprising a foam backing.

15. Surface covering according to claims 1 to 11 considered in combination, wherein the thermoplastic material has a plasticizer content of not more than 2% by weight and preferably not more than 1% by weight relative to the PVB content, wherein the PVB of the thermoplastic material consists of deplasticized recycled PVB, and wherein the thermoplastic material contains up to 10% by weight of a synthetic polymer different from PVB relative to the PVB content.

16. Surface covering according to claims 1 to 11 considered in combination, wherein the thermoplastic material has a plasticizer content of 5 to 18 wt.-% and more preferably of 8 to 14 wt.-% relative to the PVB content.

17. A surface covering according to claims 11 to 16 considered in combination.

Images