Multilayer structure for making a floor or wall covering

Abstract

The invention relates to a multilayer structure for the production of a tile or plank floor covering, the multilayer structure comprising a top wear layer bonded to a back layer, said top wear layer defining a nominal surface, said top wear layer comprising a relief pattern of a maximum depth P1 from the nominal surface, said top wear layer having a groove opening onto an edge of the multilayer structure, the groove comprising at least two walls, including an edge wall and a bottom wall, the edge wall being inclined relative to the nominal surface (N) at an outward angle α1 between 40° and 90° or at an inward angle α2 between 90° and 100°, said portion of the edge wall extending to a depth P2, from the nominal surface, greater than or equal to the depth P1.

Description

technical field

[0001] The present invention relates to a multilayer structure with improved aesthetics, presented in slabs or planks for the creation of a floor covering. Previous art

[0002] A multilayer structure presented in slabs, planks and obtained from PVC is known from the prior art.

[0003] This multi-layered structure comprises, successively, that is, from the top down: a transparent top wear layer, made of plasticized PVC, and generally between 0.2 and 2 mm thick; a decorative layer with a printed design; a backing layer made of plasticized PVC.

[0004] To enhance the appearance of this type of flooring, a groove or chamfer is often created in the top wear layer to mimic parquet flooring or tiles. For example, LVT (Luxury Vinyl Tile) flooring, which consists of a transparent surface layer or top wear layer, is chamfered on all four edges, with the chamfer having an angle of between 10 and 30 degrees relative to the surface layer.

[0005] It is also known for further improving the imitation of natural surfaces by creating a raised pattern on the surface of the transparent top layer, for example through mechanical hot-press graining processes. These processes are commonly used in the manufacture of PVC-based flooring and allow for a realistic raised pattern, also called "grain," that can mimic natural textures.

[0006] However, there is a drawback to combining surface texturing of a top wear layer with chamfering the edges of a tile or plank flooring. To enhance their realism, the embossed patterns created by chemical or mechanical texturing necessarily include areas with a slight incline. It is therefore common for the texturing to consist primarily of sections inclined at less than 30° to the plane formed by the surface of the top layer. This limitation is inherent to current texturing processes and reflects manufacturers' desire to avoid creating excessively sharp angles or depressions in the surface and to maintain ease of cleaning.

[0007] However, when creating a chamfer on the edges of a tile, manufacturers aim to maintain a consistent chamfer width so that it remains clearly visible and straight on the surface of the flooring. Since the chamfer has an angle of between 10 and 30° relative to the surface layer, it will inevitably encounter numerous sections of the textured surface with identical angles, which will alter, or even eliminate, the boundary between the chamfer and the textured surface. Furthermore, traditional chamfering methods are highly sensitive to variations in flooring thickness, particularly when the underside of the flooring rests on a substrate and the chamfer is created using a tool positioned relative to the substrate, which chamfers the surface layer vertically.In this case, the tool is positioned according to an average thickness measured on the coating, although this thickness may exhibit significant local variations, both upwards and downwards, and in a random manner.

[0008] To illustrate this flaw, the figures 1, 2 , 9 And 10 illustrate a cross-sectional view of a floor covering plank (1) according to the prior art, featuring a chamfer at an angle of 20° to the nominal surface of the embossed pattern. In these figures, the shaded area (T) represents the tool used to create the chamfer of a width (Lt). The figure 1 This presents a cross-sectional view at a first point on the edge where the chamfer width (Lo) is greater than the tool machining width (Lu) at the nominal surface (N). This defect is due to the fact that the grain slope at this point extends the chamfer produced.

[0009] Conversely, the figure 2This illustrates a second cross-section of the same blade (1) where the chamfer width (Lo) at the nominal surface (N) is identical to the machining width (Lu) of the tool. These defects can appear even if the chamfer depth is the same along the entire edge of the blade. From a top view, the actual chamfer width will fluctuate, which is undesirable.

[0010] There figure 9 A detailed cross-sectional view is shown at a third location along the edge where the thickness of the flooring (1) decreases without changing the position of the tool relative to the support (not shown) of the flooring (1). Consequently, the resulting chamfer width (Lo) is reduced at the level of the nominal surface (N), making it barely visible. This defect is due to the fact that the reduced thickness locally lowers the position of the nominal surface relative to the tool.

[0011] Conversely, the Figure 10presents a detailed cross-sectional view at a fourth point along the edge where the thickness of the flooring (1) increases without any change in the tool's position relative to the flooring support (not shown). Consequently, the resulting chamfer width (Lo) is greatly increased at the nominal surface (N), making it too wide and indistinguishable from the grain. This defect is due to the fact that the visible excess thickness locally raises the position of the nominal surface relative to the tool. On the same flooring (1), the figures 9 And 10 This illustrates the variation in widths (Lo) that can be obtained for the same tool when the machining depth relative to the floor covering support remains unchanged. In addition, the figure 3This illustrates a prior art method for producing a chamfered slab. In this figure, the surface layer of a floor covering (1) is chamfered at a cutting plane (P) which, in a subsequent step of the process, will be cut through the entire thickness of the covering (1) to produce two slabs. The cutting plane (P) will therefore form the edge of the two slabs. According to the figure (3 The tool (T), with a width (Lt), creates a chamfer at a 20° angle to the nominal surface of the embossed pattern, using two machining widths (Lu1) and (Lu2) on either side of the cutting plane (P). The figure shows that the resulting chamfer widths (Lo1, Lo2) differ on either side of the nominal surface (N) due to variations in the thickness and angle of the embossed pattern. Therefore, for two slabs made from the same material, the chamfer will not be uniform.

[0012] The process described thus does not allow for obtaining a regular chamfer on both sides of the tool for obtaining slabs from a first floor covering. Description of the invention

[0013] The invention therefore aims to provide a multilayer structure featuring a raised pattern and a groove with improved aesthetics.

[0014] Another objective of the invention is to improve the methods of making grooves.

[0015] For this purpose, a multilayer structure has been developed for the production of a tile or plank floor covering, the multilayer structure comprising a top wear layer bonded to a back layer, said top wear layer defining a nominal surface, said top wear layer comprising a relief pattern of a maximum depth P1 from the nominal surface, said top wear layer having a groove opening onto an edge of the multilayer structure, the groove comprising at least two walls, including an edge wall and a bottom wall, the edge wall being inclined relative to the nominal surface at an outward angle α1 between 40° and 90° or at an inward angle α2 between 90° and 100°, said portion of the edge wall extending to a depth P2, from the nominal surface, of at least 0.01 mm and preferably greater than or equal to the depth P1.

[0016] The terms slab and blade will be used interchangeably throughout the text. A slab or blade is a parallelepiped with four edges, although the invention is adaptable to slabs with more than four sides, for example, hexagonal slabs.

[0017] The multi-layered structure features a groove on at least one edge with a regular and perfectly straight width for the user.

[0018] The nominal surface area corresponds to the principal plane on which the embossed pattern is created, extending above and below this plane. For example, the nominal surface area for a resilient floor covering can be determined by measuring the total thickness of the covering according to standard NF EN ISO 24346 April 2012. The position of the nominal surface area relative to the surface area of ​​the backing layer in contact with the floor corresponds to the average total thickness measured at at least five measurement points.

[0019] The groove according to the invention is made at least in the upper wear layer and can extend into the underside layer.

[0020] The edge wall can be perpendicular to the nominal surface or inclined inwards from the nominal surface at an outward angle α1 between 40° and 90°. This also means that the edge wall can be inclined at an outward angle between 0° and 50° from the perpendicular to the nominal surface.

[0021] The edge banding can be perpendicular to the nominal surface or even inclined outwards from the plank, i.e., towards the edge of the flooring at a re-entrant angle α2 between 90° and 100°. This also means that the edge banding can be inclined at a re-entrant angle between 0° and 10° relative to the perpendicular to the nominal surface. However, to avoid creating hard-to-reach areas and thus compromising cleanability, it is preferable for the edge banding to be inclined at too steep an angle, outwards from the plank. Therefore, when the edge banding is inclined outwards from the plank, i.e., towards the corresponding edge, the re-entrant angle α2 is between 90° and 100°.

[0022] The fact that the groove includes at least one edge wall and one bottom wall and that the edge wall extends to a depth P2, from the nominal surface of at least 0.01 mm allows the part of the grain extending beyond the depth P2 and the nominal surface to be trimmed, planed, and thus obtains a clean and visible groove, despite the variations in thickness commonly encountered on floor coverings, in particular floor coverings one of whose layers is obtained from PVC, and more particularly from a coated and gelled PVC plastisol.

[0023] Advantageously, the fact that P2 is greater than or equal to the depth P1 in combination with the angle formed between the edge wall and the nominal surface allows for an even sharper delimitation between the groove and the embossed pattern and thus makes the groove more regular over the whole of the blade.

[0024] The back wall can have different cross-sections and angles, and therefore extend to a different depth than the side wall. Preferably, the back wall extends to a depth P3 from a nominal surface area greater than or equal to P2. This creates a zone at P3 that will concentrate dirt during use and facilitate cleaning.

[0025] Advantageously, the P3 depth is greater than 0.04 mm in order to further improve the visibility of the groove, despite the variations in thickness commonly encountered on floor coverings, in particular floor coverings where one of the layers is obtained from PVC, and more particularly from a coated and gelled PVC plastisol.

[0026] Preferably, the raised pattern of the top layer extends to a depth of less than 0.3 mm between the highest peak and the deepest hollow. In this way, the raised pattern can imitate most stone or wood textures with a good level of realism. The depth of the raised pattern extends equally above and below the nominal surface.

[0027] Preferably, at the nominal surface level, the groove has a width L1 of between 0.3 and 2 mm, preferably between 0.7 and 1.5 mm, and more preferably between 0.5 and 1 mm. This allows for the imitation of most natural materials while maintaining good visibility of the groove for users.

[0028] Preferably, at level P2, the groove has a width L2 between 0.3 and 2 mm, preferably between 0.5 and 2 mm, more preferably between 0.7 and 1.5 mm, and even more preferably between 0.5 and 1 mm. This also allows for the imitation of most natural materials while maintaining good cleanability.

[0029] Preferably, at the nominal surface level, the groove has a width L1 between 0.3 and 2 mm, preferably between 0.7 and 1.5 mm, and at the P2 level, the groove has a width L2 between 0.5 and 2 mm, preferably between 0.5 and 1 mm. This allows for the imitation of most natural materials while maintaining good cleanability and good visibility of the groove for users.

[0030] Advantageously, the depth P1 is between 0.1 and 0.3 mm, preferably between 0.1 and 0.2 mm. This depth makes it possible to obtain a raised pattern with a natural appearance while remaining clearly visible to the user.

[0031] Advantageously, depth P2 is between 0.01 and 1 mm, preferably between 0.04 and 1 mm, or even between 0.1 and 1 mm, or between 0.04 and 0.6 mm, depending on the desired visibility of the groove. A difference of at least 0.1 mm between P2 and P1 enhances the visibility of the groove. However, a depth greater than 0.6 mm, or even 1 mm, degrades cleanability.

[0032] Advantageously, the bottom wall has a straight cross-section.

[0033] Advantageously, the bottom wall has a curved section, said curved section preferably having a radius of curvature between 4 and 40 mm, preferably between 4 and 8 mm. The curved sections improve the cleanability of the groove.

[0034] Advantageously, the upper wear layer has a thickness E1 of between 0.3 and 2 mm, preferably between 0.3 and 1 mm, more preferably between 0.3 and 0.7 mm, and the depth P2 and / or P3 is less than E1. According to this embodiment, the groove is made exclusively in the upper wear layer.

[0035] The invention also relates to a method for creating a multilayer structure according to the invention, comprising the following steps: Provide a multilayer structure comprising a top wear layer defining a nominal surface and having a relief extending to a maximum depth P1 from the nominal surface; Optionally, measure the depth P1; Make at least one groove in the top wear layer opening onto an edge of the multilayer structure, the groove comprising at least two walls, including an edge wall inclined relative to the nominal surface at an outward angle α1 between 40° and 90° or a re-entrant angle α2 between 90° and 100°, said portion of the edge wall extending to a depth P2, from the nominal surface, of at least 0.01 mm and preferably greater than or equal to the depth P1.

[0036] The process according to the invention allows the creation of a multilayer structure for the production of a floor covering having a groove on at least one edge whose width is regular and perfectly straight for the user. Brief description of the drawings

[0037] Other features and advantages of the invention will become clear from the description given below, which is by way of example and not limitation, with reference to the accompanying figures in which: [ Fig.1 ] is a schematic cross-sectional representation of a chamfered slab according to prior art. Fig. 2 ] is a schematic cross-sectional representation of a chamfered slab according to prior art. Fig.3 ] is a schematic cross-sectional representation of a method for producing a chamfered slab according to the prior art. Fig. 4[ ] is a schematic cross-sectional representation of one embodiment of the multilayer structure of the invention. Fig. 5 [ ] is a schematic cross-sectional representation of a second embodiment of the multilayer structure of the invention. ] Fig. 6 ] is a second schematic cross-sectional representation of the second embodiment of the multilayer structure of the invention. Fig. 7 [ ] is a schematic cross-sectional representation of a third embodiment of the multilayer structure of the invention. ] Fig. 8 [ ] is a schematic cross-sectional representation of a fourth embodiment of the multilayer structure of the invention. ] Fig. 9 ] is a schematic cross-sectional representation of a chamfered slab according to prior art. Fig. 10 ] is a schematic cross-sectional representation of a chamfered slab according to prior art. Fig. 11[ ] is a schematic cross-sectional representation of a fifth embodiment of the multilayer structure of the invention. ] Fig. 12 ] is a schematic cross-sectional representation of a fifth embodiment of the multilayer structure of the invention. Detailed description of the invention

[0038] THE figures 1 to 3 And 9 à 10 illustrate prior art and are not part of the invention.

[0039] The multilayer structure (10) according to the invention can have any shape, particularly a panel, slab or blade, and can preferably be rolled up on itself. The multilayer structure (10) generally has a length and width between 10 and 150 cm, preferably between 15 and 120 cm, and more preferably between 20 and 100 cm.

[0040] When presented in a roll, the multilayer structure can be wound onto itself, exhibiting sufficient flexibility to meet the requirements of ISO 24344:2008. In this standard, flexibility is defined as the ability of a floor covering or a layer of a floor covering to be wound around a 20 mm mandrel without cracking or splitting. Therefore, the multilayer structure according to the invention, as tested, would not exhibit any breaks, cracks, splits, or other permanent defects.

[0041] With reference to figures 4 to 8 And 11 à 12A multilayer structure (10) has been developed for the production of a tile or plank floor covering, the multilayer structure comprising a top wear layer (2) bonded to a backing layer (3), said top wear layer defining a nominal surface (N), said top wear layer (2) comprising a relief pattern (4) of a maximum depth P1 from the nominal surface (N), said top wear layer (2) having a groove (5) opening onto an edge (6) of the multilayer structure (10), the groove (5) comprising at least two walls (7,8), including an edge wall (7) and a bottom wall (8), the edge wall (7) being inclined relative to the nominal surface (N), said edge wall (7) extending to a depth P2, from the nominal surface (N), of at least 0.01 mm and preferably greater than or equal to the depth P1.

[0042] According to the figures 4 to 7 , And 11 à 12The edge wall (7) is inclined relative to the nominal surface (N) at an outward angle α1 between 40° and 90°. This also means that the edge wall can be inclined at an outward angle between 0° and 50° relative to the perpendicular to the nominal surface.

[0043] According to the figure 8 The edge wall (7) can also be inclined relative to the nominal surface (N) by a re-entrant angle α2 between 90° and 100°. This also means that the edge wall can be inclined at a re-entrant angle between 0° and 10° relative to the perpendicular to the nominal surface.

[0044] With reference to figures 4 to 8 And 11 à 12 The multilayer structure (10) according to the invention has a groove (5) on at least one edge whose width is regular and perfectly straight for the user.

[0045] The nominal surface area (N) corresponds to the principal plane along which the embossed pattern (4) extends and is created, the pattern extending above and below this plane, preferably with a total depth of 0.3 mm. The nominal surface area (N) can, for example, be determined for a resilient floor covering by measuring the total thickness of the covering according to standard NF EN ISO 24346 April 2012. The position of the nominal surface area (N) relative to the surface of the backing layer in contact with the floor corresponds to the average total thickness measured at at least five measurement points.

[0046] The total thickness E2 of the multilayer structure (10) is generally between 2 and 6mm, preferably between 3 and 5mm.

[0047] The top wear layer (2) provides slip resistance, wear resistance, and ease of cleaning. It generally has a thickness (E1) between 0.2 and 2 mm, preferably between 0.3 and 1 mm, and more preferably between 0.3 and 0.7 mm. When made from PVC, it typically contains 20 to 50 PCR (polymerase chain reaction) plasticizers.

[0048] The upper wear layer (2) can be obtained by extrusion, calendering, pressing, or by coating and then gelling a PVC plastisol.

[0049] The upper wear layer (2) can also serve as a decorative layer, especially if it is obtained from a dyed plastisol or by pressing dyed granules, for example obtained from plasticized and dyed PVC granules.

[0050] The backing layer (3) can be obtained by extrusion, calendering, pressing, or by coating and then gelling a plastisol; although calendering, extrusion, and pressing provide better resistance to expansion. The backing layer (3) is preferably made from plasticized and filled PVC, for example with calcium carbonate. The backing layer (3) is generally between 0.5 and 5 mm thick, more preferably between 1 and 2 mm.

[0051] The upper wear layers (2) and underside layers (3) can be made from one or more layers bonded together without departing from the scope of the invention.

[0052] The top wear layer (2) and backing layer (3) can be made from polymeric materials such as, for example, thermoplastic polymers like PVC, polyurethane, polypropylene, polyethylene, and polyethylene terephthalate. Alternatively, the top and / or backing layer (3) can each be made from a layer of linoleum.

[0053] According to the figure 4 , the upper wear layer (2) may be transparent or translucent so that a printed decorative layer (9) is visible through the upper wear layer (2).

[0054] When the top wear layer (2) is made of PVC and is transparent, it generally comprises 30 to 50 PCR of plasticizer and a filler content of zero or less than 5% by weight of the top wear layer (2). The decorative layer (9) can be printed on the underside of the top wear layer (2), the top side of the backing layer (3), or on a polymer film such as a PVC film. Alternatively, the decorative layer (9) can be printed on a top side coated with a reinforcing mesh. The decorative layer can be printed using any known technique, such as digital printing or gravure printing.

[0055] Preferably, the decorative layer (9) has a printed pattern comprising at least one area imitating a mineral or wood texture and delimited by a peripheral area imitating a joint, such as a tile joint, and the groove (5) is made at least partly or totally in line with the peripheral area, in a registered manner, and in such a way as to increase the realism of the floor covering (1).

[0056] The underside layer (3) may advantageously include a foam layer (3b), the latter being preferably arranged to be in contact with the ground.

[0057] A foam layer (3b) that can be included within the backing layer (3) is preferably a layer of foamed and then gelled PVC plastisol or a closed-cell foam layer. A closed-cell foam can advantageously be made from extruded foamed polystyrene or cross-linked foamed polyethylene. The presence of a foam layer (3b) increases the risk of local variations in the thickness of the floor covering; the invention thus makes it possible to obtain a clear view of the groove (5) on this type of floor covering (10).

[0058] When the backing layer (3) includes a foam layer (3b), the foam layer generally has a thickness of between 0.5 and 3 mm, more preferably between 1 and 2 mm. The foam layer (3b) may constitute the entire thickness of the backing layer (3) or a part of it in conjunction with an additional layer (3a) of the backing layer (3).

[0059] The upper wear layers (2) and reverse layer (3) may be bonded by any means such as thermolamination and / or via a bonding layer of glue, plastisol or double-sided adhesive film not shown.

[0060] Advantageously and according to the figure 5 The bottom wall (8) of the groove (5) extends to a depth P3 from the nominal surface (N) greater than or equal to P2. This allows in particular the creation of an area at the level of P3 which will concentrate the dirt in use and facilitate cleaning.

[0061] Advantageously and according to the figure 6 At the level of the nominal surface (N), the groove (5) has a width L1 between 0.3 and 2 mm, preferably between 0.7 and 1.5 mm, more preferably between 0.5 and 1 mm. This makes it possible to imitate most natural materials while maintaining good visibility of the groove for users.

[0062] Advantageously and always according to the figure 6 At level P2, the groove (5) has a width L2 between 0.3 and 2 mm, or even between 0.5 and 2 mm, preferably between 0.7 and 1.5 mm, more preferably between 0.5 and 1 mm

[0063] This also allows for the imitation of most natural materials while maintaining good cleanability.

[0064] Preferably, at the nominal surface (N), the groove (5) has a width L1 between 0.3 and 2 mm, preferably between 0.7 and 1.5 mm, and at the P2 level, the groove (5) has a width L2 between 0.5 and 2 mm, preferably between 0.5 and 1 mm. This makes it possible to imitate most natural materials while maintaining good cleanability and good visibility of the groove for users.

[0065] Preferably, the depth P1 is between 0.1 and 0.3 mm, preferably between 0.1 and 0.2 mm. This depth allows for a natural-looking raised pattern that is clearly visible to the user.

[0066] Preferably, the depth P2 is between 0.01 and 1 mm, preferably between 0.04 and 1 mm, or even between 0.1 and 1 mm, or even between 0.04 and 0.6 mm, depending on the expected visibility of the groove. A difference between P2 and P1 of at least 0.1 mm enhances the visibility of the groove (5). However, a depth greater than 0.6 mm, or even 1 mm, degrades cleanability. Preferably, and as shown in the figures 4 , 7 and 8 The bottom wall (8) has a straight cross-section. Preferably, and as shown figures 6 , 11 and 12The bottom wall (8) has a curved section, said curved section preferably having a radius of curvature between 2 and 40 mm, preferably between 4 and 8 mm. The curved sections improve the cleanability of the groove.

[0067] On the other hand, the groove (5) manufacturing methods according to the invention can use ultrasonic knives as cutting tools. These knives remove material from the upper wear layer (2) and create the groove (5) in a single pass. The knife shape corresponds to the cross-sections of the edge (7) and bottom (8) walls. It is preferable to limit the number of angles between these walls, as these angles are points of weakness for the ultrasonic knives. When the bottom wall (8) has a curved cross-section, the corresponding knife is more resistant and will not break or be damaged during machining. The method for creating the multilayer structure is therefore more robust.

[0068] In one particular embodiment, the upper wear layer (2) has a thickness E1 of between 0.3 and 2 mm, preferably between 0.3 and 1 mm, more preferably between 0.3 and 0.7 mm, and the depth P2 and / or P3 is less than E1. In this embodiment, the groove (5) is formed exclusively in the upper wear layer (2) and does not extend into the backing layer (3) or the printed decorative layer (9), if any. It is generally undesirable for these layers to be visible because they have a different color that detracts from the overall visual appearance.

[0069] According to a first example of implementation presented at the figure 4 , the edge wall (7) has an angle α1 of 90° with respect to the nominal surface (N) and the bottom wall (8) has a straight section and is parallel to the nominal surface (N).

[0070] According to the illustrated implementation examples figures 5 to 7, the edge wall (7) is inclined towards the inside of the blade or slab, at an outward angle α1 between 40° and 90° so that L1 is greater than L2.

[0071] In the example of the figure 6 , α1 has an outward angle of 80° with respect to the nominal surface (N), the bottom wall (8) having a curved section with a radius of curvature of 6 mm.

[0072] Following the example of the figure 7α1 has an outward angle α1 between 40° and 90°, for example 80° with respect to the nominal surface (N). The bottom wall (8) has a curved section (13) with a radius of curvature of 2 mm and a straight section. The transition between the edge wall (7) and the embossed pattern (4) also has a curved section (12), so that the entire groove (5) has a sigmoid cross-section. The curved section (12) of the transition between the edge wall (7) and the embossed pattern (4) advantageously has a radius of curvature between 0.5 and 3 mm.

[0073] A groove (5) with a sigmoid cross-section optimizes cleaning and ensures a perfect visual appearance. When the groove (5) has a sigmoid cross-section, the ultrasonic cutter used to create it is more durable because it has no sharp edges and is less likely to break or be damaged during machining. The manufacturing process for the multilayer structure (10) is therefore more robust, and the multilayer structure (10) has a more uniform appearance.

[0074] According to the figure 8 The edge profile (7) is inclined relative to the nominal surface (N) at a re-entrant angle α2 between 90° and 100°. This re-entrant angle allows for a clear distinction between the groove (5) and the embossed pattern (4). However, to avoid creating hard-to-reach areas and thus impairing cleanability, it is preferable for the edge profile (7) to be inclined too far outwards from the blade.

[0075] Following the example of the figure 11On which only the top layer (2) is shown, the backing wall (8) has a curved section (13) with a radius of curvature of 35 mm. In this example, at the nominal surface, the groove has a width L1 between 1 and 1.5 mm, and at level P2, the groove has a width L2 between 0.5 and 1 mm. The transition between the edge wall (7) and the embossed pattern (4) has a curved section (12) that deviates inward from the coating with a radius of curvature of 3 mm, such that the entire groove (5) has an outward angle α1 of 89° with respect to the nominal surface (N) at the intersection of the edge wall (7) and the backing wall (8). The embossed pattern (R) is shown as a dashed line for the portion removed by the tool (T), in this case, an ultrasonic knife.In this example, depth P2 is less than P1 so that the tool (T) creating the groove (5) removes the ridges of the raised pattern and forms a clearly visible groove (5), and the field wall (7) creates an outward angle that clearly delimits the edge of the groove, the width of which will be more consistent, even if the thickness of the flooring (10) varies. Furthermore, the bottom wall (7) creates a local difference in the gloss of the top layer (2), which reflects more light than a conventional chamfer of the prior art and makes it more visible.

[0076] The example of the figure 12 takes up the same groove shape (5) and illustrates the case of a local increase in the thickness of the coating which will shift the depth P2 and make it greater than P1. In this figure, the groove (5) is perfectly visible and the width obtained is almost identical to the width obtained at the figure 11despite the variation in thickness. The groove (5) is thus more realistic and of higher quality across the entire surface of the floor covering.

[0077] The invention also relates to a method for producing a multilayer structure (10) according to the invention comprising the following steps: Provide a multilayer structure (10) comprising a top wear layer (2) defining a nominal surface (N) and having a relief (4) extending to a maximum depth P1 from the nominal surface (N); Optionally, measure the depth (P1); Make at least one groove (5) in the top wear layer (2) opening onto an edge (6) of the multilayer structure (10), the groove (5) comprising at least two walls (7, 8), including an edge wall (7) inclined relative to the nominal surface (N) at an outward angle α1 between 40° and 90° or a re-entrant angle α2 between 90° and 100°, said portion of the edge wall (7) extending to a depth P2, from the nominal surface (N), of at least 0.01 mm and preferably greater than or equal to the depth P1.

[0078] When the multilayer structure (10) is manufactured in roll form, the nominal surface area (N) is advantageously defined with respect to the minimum or average thickness measured on the roll, according to standard NF EN ISO 24346 April 2012, or by means of a continuous measurement performed during the manufacturing of the structure. Methods for continuously measuring the minimum or average thickness include, for example, methods using radioactive gauges or laser measuring systems. Advantageously, the nominal surface area (N) corresponds to the minimum thickness of the multilayer structure (10) measured by a continuous method during the manufacturing of the multilayer structure (10) when it is supplied in roll form.

[0079] When the multilayer structure (10) is in slab or plank form, the nominal surface area (N) is advantageously defined in relation to the minimum or average thickness measured on the slab or plank, according to standard NF EN ISO 24346 April 2012, or by means of a measurement taken continuously during the manufacturing of the structure before it is cut into planks or slabs. Advantageously, the nominal surface area (N) corresponds to the minimum thickness of the multilayer structure (10) measured by a continuous process during the manufacturing of the multilayer structure (10) when it is manufactured continuously and then cut into slabs or planks.

[0080] The invention also relates to an advantageous method of realizing a multilayer structure (10) according to the invention.

[0081] Traditional methods for creating grooves or chamfers generally involve placing the LVT tile or plank to be chamfered upside down on a subfloor, with the top layer exposed, allowing the edge of the plank to extend beyond the subfloor. The technique then consists of chamfering the edges of this top layer using a sander or a double tenoner with rotary tools. In these techniques, the depth of the chamfer is determined by the distance between the subfloor in contact with the top surface of the wear layer (which serves as the reference plane) and the tip of the chamfering tool. Therefore, the resulting chamfer is independent of the thickness of the wear layer or the flooring, as the tool is always correctly positioned relative to the subfloor.The nominal surface is therefore always at the same distance from the support and by extension the depth of the chamfer is always at the same distance from the nominal surface.

[0082] Resilient floor coverings, and in particular PVC vinyl floor coverings on foam, or any floor covering with a foam backing, are however difficult to integrate with these processes.

[0083] This technique, which uses a double tenoner, is also incompatible with machining slabs, panels, or rolls for manufacturing panels or panels where the transport support during chamfer machining is in contact with the underside of the multilayer structure. This is because there can be significant variations in thickness, exceeding 0.1 mm and up to 0.5 mm, between the underside and top wear layers, depending on the manufacturing processes used.

[0084] Resilient floor coverings, and in particular PVC vinyl flooring on foam backing, or any floor covering with a foam backing, are generally chamfered with ultrasonic cutters. The floor covering is placed on a flat surface, and the ultrasonic cutter is brought to the edge to be chamfered. Therefore, if the chamfering tool is positioned with the backing as a reference, the cutting depth will vary considerably depending on the thickness of the multi-layered structure.

[0085] To overcome this problem, some manufacturers use sanding steps on the back layer to even out the thickness of the multilayer structure before chamfering its edges. With a more uniform overall thickness, ultrasonic machining processes can be used. However, this results in material loss and an undesirable additional cost.

[0086] The invention therefore also relates to a method for producing a multilayer structure (10) according to the invention comprising the following steps: Provide a first multilayer structure comprising a top wear layer (2) defining a nominal surface (N) and having a relief (4) extending to a maximum depth P1 from the nominal surface (N), the first multilayer structure having a width and a length and being able to be in the form of a slab, plank, or roll; Measure the thickness E2 of the entire first multilayer structure along at least one width and / or one length in order to establish a thickness profile E; Optionally, measure the depth P1; Place the back layer of the first multilayer structure (10) in contact with a support defining a reference plane;To create at least one groove (5) in the upper wear layer (2) opening onto an edge (6) of the first multilayer structure, the groove (5) comprising at least two walls (7, 8), including an edge wall (7) inclined at an angle to the nominal surface (N) of an outward angle α1 between 40° and 90° or a re-entrant angle α2 between 90° and 100°, said portion of the edge wall (7) extending to a depth P2, from the nominal surface (N), of at least 0.01 mm and preferably greater than or equal to the depth P1, the depth P2 being defined according to the thickness profile E. Optionally, cut the first multilayer structure in the form of a roll to obtain a multilayer structure (10) to form a slab or a plank.

[0087] In this way, the top wear layer of the multilayer structure can be chamfered regardless of its thickness variations. The depth P2 can, for example, be defined based on the minimum thickness of the multilayer structure obtained from the thickness profile (E).

[0088] This process is particularly beneficial for resilient floor coverings, PVC vinyl flooring on foam backing, or any flooring with a foam backing. These foam layers exacerbate thickness variations. The process is also especially advantageous when the multi-layered structure has a length and / or width exceeding 60 cm, and preferably exceeding 90 cm, as these factors increase the risk of thickness variations.

[0089] Furthermore, if the coating is initially manufactured in rolls and stored as coils several meters long before being grooved and cut into slabs, a creep effect of the composition can occur between the areas above and below the coil's core. Areas above or below the core, in particular, tend to compress depending on the storage method. If the roll is suspended from the core, the areas above the core will be especially prone to compression. Therefore, by using the thickness profile measurement of the roll or coil along the manufacturing axis, for example with a laser or radioactive source profilometer, as an adjustment variable for the chamfering process, the process adapts to the actual thickness of the coating at the chamfering tool and adjusts the depth P2 so that it is always greater than or equal to P1.

Claims

1. Multilayer structure (10) for the production of a tile or plank floor covering, the multilayer structure (10) comprising a top wear layer (2) bonded to a backing layer (3), said top wear layer (2) defining a nominal surface (N), said top wear layer (2) comprising a relief pattern (4) of a maximum depth P1 from the nominal surface (N), said top wear layer (2) having a groove (5) opening onto an edge (6) of the multilayer structure (10), the groove (5) comprising at least two walls (7,8), including an edge wall (7) and a bottom wall (8) characterized by This that the edge wall (7) is inclined relative to the nominal surface (N) by an out angle α1 between 40° and 90° or by an inward angle α2 between 90° and 100°, said portion of edge wall (7) extending to a depth P2, from the nominal surface (N), of at least 0.01 mm and preferably greater than or equal to the depth P1.

2. Multilayer structure (10) according to claim 1 characterized by This that the bottom wall (8) of the groove (5) extends to a depth P3 from the nominal surface (N) greater than or equal to P2.

3. Multilayer structure (10) according to claim 1 or 2 characterized in that 'at the level of the nominal surface (N) the groove (5) has a width L1 between 0.3 and 2 mm, preferably between 0.7 and 1.5 mm.

4. Multilayer structure (10) according to any one of the preceding claims characterized in this thatat level P2, the groove (5) has a width L2 between 0.3 and 2 mm, preferably between 0.7 and 1.5 mm, more preferably between 0.5 and 1 mm.

5. Multilayer structure (10) according to any one of the preceding claims characterized by This that The depth P1 is between 0.1 and 0.3 mm, preferably between 0.1 and 0.2 mm.

6. Multilayer structure (10) according to any one of the preceding claims characterized by This that The depth P2 is between 0.01 and 1 mm.

7. Multilayer structure (10) according to any one of the preceding claims characterized by This that the bottom wall (8) has a straight section.

8. Multilayer structure (10) according to any one of claims 1 to 6 characterized in that the bottom wall (8) has a curved section, said curved section preferably having a radius of curvature between 2 and 40 mm, preferably between 4 and 8 mm.

9. Multilayer structure (10) according to any one of the preceding claims characterized in that the upper wear layer (2) has a thickness E1 of between 0.3 and 2 mm, preferably between 0.3 and 1 mm, more preferably between 0.3 and 0.7 mm and in that Depth P2 is less than E1.

10. A method for producing a multilayer structure (10) according to any one of the preceding claims comprising the following steps: - Providing a multilayer structure (10) comprising an upper wear layer (2) defining a nominal surface (N) and having a relief (4) extending to a maximum depth P1 from the nominal surface (N); - Optionally, measuring the depth P1; - To make at least one groove (5) in the upper wear layer (2) opening onto an edge (6) of the multilayer structure (10), the groove (5) comprising at least two walls (7,8), of which an edge wall (7) inclined relative to the nominal surface (N) at an outward angle α1 between 40° and 90° or at an inward angle α2 between 90° and 100°, said portion of edge wall (7) extending to a depth P2, from the nominal surface (N) by at least 0.01 mm and preferably greater than or equal to the depth P1.

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