Multilayer structure for creating a heterogeneous, printed, linoleum-based floor or wall covering

Abstract

The invention relates to a multilayer structure (1) for producing a floor or wall covering comprising a backing layer (2) based on linoleum reinforced by a reinforcing mesh (3), a wear layer (4) made of a thermoplastic polymer transparent at least to visible light and bonded to the backing layer (2), and a decorative printing layer (5) positioned between the wear layer (4) and the backing layer (2), characterized in that it comprises a cross-linked varnish layer (11) deposited on an underside of the backing layer (2). Figure for the abstract: Fig. 1

Description

Title of the invention: Multilayer structure for producing a heterogeneous, printed, linoleum-based floor or wall covering. Technical field

[0001] The present invention relates to a multilayer structure for the production of a heterogeneous floor or wall covering, printed with a design and based on linoleum.

[0002] The present invention finds an advantageous application in the production of linoleum-based floor coverings and loose-lay floor coverings, for example presented in the form of rolls, tiles or planks. Previous art

[0003] In the field of the present invention, it is known to produce a multilayer structure for the production of a floor or wall covering, heterogeneous having a decoration in digital printing on a back layer based on linoleum.

[0004] For example, a multilayer structure comprising: is known - a backing layer made of linoleum which is supported by a reinforcing frame, such as a jute canvas or a woven polyester grid, intended to be in contact with the floor or the wall; - a layer of bonding primer positioned on the back layer; - a decorative printing layer, such as a digital printing layer, deposited on the primer layer; - a cross-linked polyurethane wear layer positioned on the decorative printing layer.

[0005] In practice, the linoleum-based backing layer may comprise two layers bonded together, namely a top layer of so-called "noble" linoleum and a bottom layer of recycled linoleum.

[0006] During manufacturing, the noble layer and the layer containing recycled linoleum are calendered together on the reinforcing frame before being cross-linked in an oven at 80 °C for more than 30 days.

[0007] The drawback of this type of multilayer structure is that the abrasion resistance of the cross-linked polyurethane wear layer is insufficient. Indeed, abrasion tests show excessively rapid wear for multilayer structures subjected to average traffic. In particular, the decorative finish disappears after 550 cycles on an abrasion and wear testing machine known as TABER (Registered Trademark) according to standard NF EN 16511+A1.

[0008] Document EP 2 723 561 specifies that this wear layer is made of cross-linked polyurethane by hot sealing and incorporates inorganic particles. This type of hot-sealed layer is known to those skilled in the art as "hotcoating" and is preferably applied with a thickness between 50 and 150 µm, and filled with a filler providing abrasion resistance, such as, for example, an alumina-type filler.

[0009] A cross-linked polyurethane wear layer is more resistant when obtained from a hot-sealing layer. However, this wear layer adds mechanical stresses to the surface of the coating, which can lead to significant deflection when it is in the form of a sheet. Furthermore, this type of wear layer can be brittle if subjected to significant impacts. Moreover, the manufacturing process for a multilayer structure incorporating such a wear layer is lengthy and expensive.

[0010] Moreover, according to one or the other of the multilayer structures described above, it is not possible to grain the wear layer after crosslinking, which makes the products obtained less realistic or more complex to produce.

[0011] Document EP2424911 is also known, describing the presence of a varnish layer on a homogeneous substrate, which may be linoleum, supplied in rolls, tiles, or planks. The UV varnish is applied to the surface, edges, or back of the substrate to seal the product. EP2424911 does not describe whether the tile, plank, or roll substrate may have a heterogeneous structure, nor does it address the balancing problem of this type of heterogeneous substrate.

[0012] Document EP3995305 is also known, which aims to solve the problem of balancing heterogeneous floor or wall coverings based on linoleum.

[0013] This document describes in particular a multilayer structure for the production of a floor or wall covering comprising a backing layer based on linoleum reinforced by a reinforcing mesh, a wear layer bonded to the backing layer, and a decorative printing layer positioned between the wear layer and the backing layer.

[0014] To remedy the balancing problems, this document proposes that the wear layer be made of polyethylene terephthalate (PET), thermoplastic polyurethane (TPU), preferably aliphatic, polypropylene (PP), or polyethylene glycol terephthalate (PETG), or ionomer.

[0015] However, it turns out that linoleum is a material very sensitive to ambient humidity, and that the slightest variation in humidity leads to curving phenomena.

[0016] In particular, the thermoplastic surface layer exhibits a different mechanical and thermal behavior from that of the linoleum backing layer. By Furthermore, the continuous manufacturing process for this type of flooring includes heating and winding phases that add tension to the different layers. The surface layer is therefore very sensitive to temperature variations, and the linoleum backing layer is sensitive to applied tension as well as humidity. Description of the invention

[0017] One of the aims of the invention is therefore to remedy the aforementioned problems by providing a multilayer structure for the production of a heterogeneous floor or wall covering based on printed linoleum with a design, which has sufficient resistance in terms of abrasion, i.e. which meets the tests of the standard NF EN 16511+A1, while avoiding the problems of curvature of the covering when it is in the form of planks or tiles.

[0018] For this purpose, a multilayer structure has been developed for the production of a floor or wall covering comprising a backing layer based on linoleum reinforced by a reinforcing reinforcement, a wear layer made of thermoplastic polymer transparent at least to the light in the visible range and bonded to the backing layer, and a decorative printing layer positioned between the wear layer and the backing layer.

[0019] According to the invention, the multilayer structure comprises a crosslinked varnish layer, for example based on polyurethane or acrylic, deposited on an underside of the reverse layer.

[0020] The coating according to the invention has sufficient resistance in terms of abrasion, in particular satisfying the standard NF EN 16511+A1, while reducing or even eliminating the problems of curvature of the coating when it is in the form of a sheet and making the multilayer structure less brittle. The use of such a decorative printing layer also improves the dimensional stability of the multilayer structure.

[0021] The cross-linked varnish layer limits the linoleum's sensitivity to water by acting as a "pore sealer." The varnish layer therefore delays water absorption and acts as a moisture barrier, further reducing the risk of warping of the flooring, which remains below 3 mm, preferably below 2 mm.

[0022] The varnish layer also helps to counterbalance the stresses generated by the thermoplastic polymer surface layer, which promotes the balancing of the coating.

[0023] The invention therefore makes it possible to solve the problems of the prior art, while maintaining a low thickness and low weight since the varnish layer presents generally a thickness that can be between 5 and 30 pm, preferably between 10 and 20 pm, which is equivalent to about 10-20g / m2.

[0024] In practice, the multilayer structure has, for example, a thickness of between 1.4 mm and 3.5 mm, and the reverse layer has, for example, a thickness of between 1.3 mm and 3 mm, preferably between 1.6 mm and 2.2 mm.

[0025] Preferably, the varnish layer includes a textured underside, for example grained, to improve adhesion to the floor or wall.

[0026] The thermoplastic polymer wear layer is for example made of polyethylene terephthalate (PET), thermoplastic polyurethane (TPU), preferably aliphatic, polypropylene (PP), or polyethylene glycol terephthalate (PETG), or ionomer, or polyvinyl chloride (PVC).

[0027] The manufacturing process for the multilayer structure can also be simplified and is less expensive, since the decorative printing layer is preferably a printed ink layer, for example by digital printing: - on an underside of the wear layer which is transparent, or; - on an upper face of the reverse layer, or; - on an upper face of a thermoplastic support layer, for example PVC, PET, TPU, preferably aliphatic, PP, PETG or ionomer, or of a paper layer impregnated with a binder, such as melamine formaldehyde or urea formaldehyde resin.

[0028] Thus, the decorative printing layer can be printed separately on a layer that is then bonded to another layer of the coating. This simplifies the process, provides greater flexibility, and reduces costs. Indeed, obtaining a backing layer is quite time-consuming, exceeding 30 days, and is done on a production run basis. It is therefore simpler to produce a backing layer and a wear layer with the decorative finish separately and bond them together as needed. The multilayer structure can be manufactured in rolls and then cut into strips or tiles.

[0029] Furthermore, the wear layer implemented in the multilayer structure according to the invention can be grained and / or chamfered, thus making the decoration more realistic.

[0030] According to a particular embodiment, the wear layer is bonded to the backing layer by hot rolling, depending on the chemical compatibility of the two materials to be joined.

[0031] According to another embodiment, the wear layer is linked to the backing layer by means of a bonding layer, optionally transparent at least to light in the visible range, such as a layer of adhesive, for example a hot melt known by the English name "hotmelt", for example in copolyester or cross-linked polyurethane, or a hot melt film, a hot melt grid or a hot melt veil, for example non-woven, of copolyester or copolyamide.

[0032] In the case of a bonding layer in the form of a hot melt film, said hot melt film may be either single-layer, for example in ethylene-vinyl acetate (EVA), thermoplastic polyurethane (TPU), copolyamide, polyester, copolyester, or two-layer, such as a co-extruded film composed of a copolyamide layer and a polyolefin layer.

[0033] It is evident that, when a bonding layer is used and the decorative printing layer is printed on the top face of the reverse layer, said bonding layer must be transparent at least to light in the visible range so as not to obscure the decorative printing layer.

[0034] Advantageously and in order to facilitate the manufacturing process of the multilayer structure according to the invention, the decorative printing layer is preferably printed by a digital printing machine, and is a layer of water-based ink, or UV ink, in particular to be cross-linked under ultraviolet.

[0035] Preferably, the decorative printing layer is positioned, and in particular printed, on a layer of white ink, which unifies the decoration and facilitates color reproducibility. In some cases, particularly if a layer of white ink cannot be printed, the layer receiving said ink layer may be coated with a white, water-based, temperature-curing primer or a white, UV-curing primer before printing the decorative printing layer. The primer may be polyurethane or acrylic.

[0036] In this embodiment, the bonding layer can be a two-layer hot melt film comprising an upper layer of polyolefin, due to its good affinity with polypropylene, and a lower layer of copolyamide, due to its good affinity with linoleum, or a hot melt layer, for example of cross-linked polyurethane, due to its good affinity with paper and linoleum.

[0037] The reinforcing mesh is embedded within the thickness of the backing layer on one of its lower and / or upper faces, and may be, for example, made of jute fabric, a paper-based mesh, a non-woven fabric or woven polyester grid, cotton fabric, or natural fibers. Positioning the reinforcing mesh on the upper face of the backing layer improves dimensional stability and further reduces, or even eliminates, the curvature of the multilayer structure. In one embodiment, the multilayer structure comprises two reinforcing meshes, positioned on either side of the backing layer.

[0038] Preferably, and in order to make the coating more realistic, depending on the desired decor, the upper face of the wear layer is chamfered and / or grained.

[0039] The varnish layer deposited on the underside of the reverse layer can, for example, be a light-curing varnish. The varnish can be cured conventionally, i.e., using polychromatic UV emitters.

[0040] The invention also relates to a method of manufacturing such a remarkable multilayer structure in that the varnish layer is crosslinked by means of exposure to ultraviolet radiation, followed or preceded by exposure to a monochromatic laser emitter of the excimer laser type.

[0041] In this way, more tension is obtained in the varnish layer, which promotes the flattening of the multilayer structure. In other words, crosslinking the varnish layer using a monochromatic excimer laser emitter provides the same counterbalancing effect as with a conventional crosslinking technique, but with a thinner varnish layer.

[0042] Furthermore, such a varnish layer provides a better moisture barrier effect and limits the absorption of moisture by the linoleum layer after application of the product, as well as the sensitivity of the structure to temperature variations. The counterbalancing effect is therefore more durable. Brief description of the drawings

[0043] [Fig.1] is a schematic representation of a multilayer structure according to a first variant of the invention.

[0044] [Fig.2] is a schematic representation of a multilayer structure according to a second variant of the invention.

[0045] [Fig.3] is a schematic representation of a multilayer structure according to a third variant of the invention.

[0046] [Fig.4] is a schematic representation of a multilayer structure according to a fourth variant of the invention.

[0047] [Fig.5] is a schematic representation of a multilayer structure according to a fifth variant of the invention. Detailed description of the invention

[0048] With reference to figures 1 to 5, the invention relates to a multilayer structure (1) for the production of a floor or wall covering, said to be heterogeneous and based on linoleum, which can be presented in tile, plank, panel or roll form, with a decorative printing layer, preferably obtained by digital printing, which resists the current abrasion tests and in which the curvature phenomena are limited, or even avoided.

[0049] To this end, the multilayer structure (1) comprises, in a conventional manner, a backing layer (2) based on linoleum which may comprise two layers, namely A top layer (2a), referred to as the "noble" layer, and a bottom layer (2b) containing recycled linoleum. The backing layer (2) has, for example, a thickness of between 1.3 and 3 mm, and preferably between 1.6 and 2.2 mm. The backing layer (2) is reinforced by a reinforcing mesh (3), which can be jute, a paper-based mesh, a non-woven fabric, a woven polyester grid, or a cotton or natural fiber fabric, for example, embedded within the thickness of the backing layer (2). The noble (2a) and recycled (2b) layers of the backing layer (2) are, for example, calendered together over the reinforcing mesh (3) before being cross-linked in an oven, for example at 80°C for more than 30 days. The backing layer (2) has, for example, a thickness of between 1.5 and 3 mm.

[0050] A wear layer (4), transparent to visible light, is then applied, in particular made of PET, preferably aliphatic TPU, PP, PETG or an ionomer, or PVC, and is bonded to the backing layer (2), after first positioning a decorative printing layer (5) between the wear layer (4) and the backing layer (2). For example, the decorative printing layer (5) has a thickness of between 4 and 300 µm and can be printed on a lower face of the wear layer (4) or on a upper face of the backing layer (2). The wear layer (4) comprises, for example, a density of between 0.9 and 1.4, and preferably between 1.15 and 1.25, and a thickness of between 50 and 600 µm, and preferably between 200 and 500 µm. The multilayer structure has a thickness between 1.4 mm and 3.5 mm.

[0051] Several solutions are possible for bonding the wear layer (4) to the backing layer (2) based on linoleum. For example, the two layers can be laminated together under heat so as to obtain a fusion of the materials at the interface of the two layers or can be bonded by means of a bonding layer (6), possibly transparent to visible light, such as a layer of hot melt adhesive, a hot melt film, a hot melt grid or a hot melt veil, for example a non-woven, copolyester or copolyamide.

[0052] The hot melt film comprises, for example, a surface mass of 20 to 300 g / m2 and can be single-layer, for example in EVA, TPU, copolyamide, polyester or copolyester, or a two-layer hot melt film, for example co-extruded, composed of a layer of copolyamide and a layer of polyolefin.

[0053] The hot melt grid or hot melt veil, for example non-woven, copolyester or copolyamide, comprises for example a surface mass of 5 to 100g / m2.

[0054] The decorative printing layer (5) is preferably printed by a digital printing machine, and may be a layer of water-based ink or ink UV to be cross-linked under ultraviolet light, possibly printed on a layer of white ink (7) in order to unify and improve the reproducibility of the colours of the decoration.

[0055] The wear layer (4) can be varnished to give it good surface properties, in particular gloss, resistance to soiling and slip resistance, with a varnish, for example acrylic or polyurethane, of a thickness generally between 7 and 30 µm.

[0056] In order to further balance the multilayer structure according to the invention, a crosslinked varnish layer (11), for example polyurethane or acrylic based, with a thickness of between 5 and 30 pm, preferably between 10 and 20 pm, is deposited on an underside face of the reverse layer (2).

[0057] The varnish layer (11) is preferably crosslinked by means of exposure to ultraviolet radiation, followed or preceded by exposure to a monochromatic laser emitter of the excimer laser type, and advantageously comprises a textured underside, for example, grained, to improve adhesion to the floor or wall. The varnish layer can be crosslinked solely by exposure to ultraviolet radiation, but exposure also to a monochromatic laser emitter of the excimer laser type increases the stresses in the varnish layer, which promotes the flattening of the multilayer structure.

[0058] From the concept at the base of the invention, several forms of embodiment can be envisaged.

[0059] For example, with reference to [Fig.1], a decorative printing layer (5) can be printed on an underside of a wear layer (4) made of PET, TPU, PP, ionomer or PETG or PVC.

[0060] On top of the decorative printing layer (5), a layer of white ink (7), with a thickness of approximately 5 to 10 pm, is then optionally printed, and preferably also with a digital printing machine.

[0061] The wear layer (4) is then turned over and bonded, i.e. hot laminated or via a bonding layer (6), with a backing layer (2) based on natural linoleum, or composed of a top layer (2a) of so-called "noble" linoleum and a bottom layer (2b) of recycled linoleum, supported by a reinforcing frame (3), such as a jute canvas, a paper-based frame, a non-woven fabric, or a woven polyester grid, and with a cross-linked varnish layer (11) deposited on the back and intended to be in contact with the floor or wall to be covered.

[0062] The bonding layer (6) can be an adhesion primer, a hot melt adhesive layer, or a hot melt film.

[0063] Alternatively, and according to [Fig.2], the reinforcing reinforcement layer (3) can be positioned between the bonding layer (6) and the upper face of the underside layer (2), in order to further limit, or even eliminate, the bending phenomenon.

[0064] Alternatively, and according to [Fig. 3], the multilayer structure (1) comprises a support layer (8), for example, with a thickness between 70 and 150 µm, made of polypropylene or paper impregnated with a binder such as melamine-formaldehyde or urea-formaldehyde resin, positioned between the wear layer (4) and the bonding layer (6). More specifically, the wear layer (4), the decorative printing layer (5), and the support layer (8) form a complex, which complex is bonded to the backing layer (2) by the bonding layer (6). During the manufacture of the complex, the decorative printing layer (5) can be printed on the underside of the wear layer (4), or on an upper side of the support layer (8).

[0065] For example, the assembly may comprise a support layer (8) made of pre-printed paper with a decorative printing layer (5) then bonded by hot lamination with a wear layer (4) made of polypropylene. The wear layer (4) is then varnished.

[0066] In this example, the bonding layer (6) advantageously takes the form of a hot melt adhesive, for example cross-linked polyurethane, the application of the adhesive possibly being preceded by a corona or plasma type pretreatment of the surface of the back layer (2) in order to improve its adhesion.

[0067] In another example, the assembly may comprise a support layer (8) of polypropylene printed with a decorative printing layer (5) and then bonded by hot lamination with a wear layer (4) of polypropylene. The wear layer (4) is then varnished.

[0068] In this example, the bonding layer (6) advantageously takes the form of a two-layer hot melt film (9) comprising an upper layer (9a) of polyolefin, due to its good affinity with polypropylene, and a lower layer (9b) of copolyamide, due to its good affinity with the linoleum of the reverse layer (2).

[0069] The back layer (2) is similar to that shown in [Fig.1], with the reinforcing frame (3) positioned on the underside of the back layer (2) and covered with a cross-linked varnish layer (11) intended to be in contact with the floor or wall to be covered.

[0070] In the examples of Figures 2 and 3, the decorative printing layer (5) can be printed with aqueous inks by rotogravure. The wear layer (4), for example, a layer obtained from a Surlyn-type ionomer, i.e., a copolymer of ethylene with a vinyl monomer (methacrylic acid), has, for example, a thickness of approximately 300 µm and is textured. The complex formed by the wear layer (4), the decorative printing layer (5), and the support layer (8) has a total thickness of between 170 µm and 420 µm, depending on the desired wear class.

[0071] The bonding layer (6), which may in particular be a bilayer hot melt film (9) in polyolefin (9a) / copolyamide (9b) has for example a weight between 24 and 95 g / m2 and allows the complex to be assembled with the reverse layer (2).

[0072] Alternatively, and with reference to [Fig.4], the reinforcing reinforcement (3) can be positioned between the bonding layer (6) and the underside layer (2) in order to reduce, or even eliminate, the bending phenomenon.

[0073] According to another manufacturing variant, illustrated in [Fig.5], the invention consists of directly printing the decorative printing layer (5) onto a top layer of the backing layer (2) based on linoleum.

[0074] The multilayer structure (1) then comprises, from the floor or wall to the surface: - a crosslinked varnish layer (11); - a backing layer (2) based on linoleum, with a reinforcing reinforcement (3) embedded in the thickness of the underside of the backing layer (2); - a decorative printing layer (5) printed on an upper face of the backing layer (2) or possibly on a polyurethane or acrylic type bonding primer (10) deposited on the upper face of the backing layer (2); - a bonding layer (6), in particular transparent to light in the visible range, such as another bonding primer, a hot melt adhesive, a hot melt film; - a wear layer (4) positioned on the bonding layer (6).

[0075] Of course, and as mentioned previously, the bonding layer (6) is optional if the wear layers (4) and backing layers (2) are laminated together and hot.

[0076] Tests according to ISO 23999 procedure B were carried out on an example of a multilayer structure (1) as shown in [Fig. 2]. A reference sample reproducing the structure of [Fig. 2] without the varnish layer (11) was first made. From an A4-sized sample of the structure (1), the curvature was measured in the machine direction (MD) and across the grain (CMD), as well as at the corners. The measurement was taken before the sample was placed in an oven, then heated to 50°C for 6 hours, and a second measurement was taken 24 hours after removal from the oven.

[0077] The results are compiled in Table 1 below.

[0078] [Tables] Reference without varnish (11) Initial curvature (mm) Final curvature (mm) MD 4 10 CMD 0 0 Coins 6 11

[0079] A first sample (ECH1) according to the invention, having a UV-cured polyurethane (PU) varnish layer of 8 g / m², is tested under the same conditions. The results are compiled in Table 2 below.

[0080] [Tables2] ECH1 Initial curvature (mm) Final curvature (mm) MD 3 2 CMD 0 -3 Corners -2 -3

[0081] This ECH1 sample shows that the curvature of the structure is corrected by the presence of the varnish layer, even after oven drying.

[0082] A second sample (ECH2) according to the invention, having a 10g / m² layer of polyurethane varnish crosslinked under excimer and then under ultraviolet light, is tested under the same conditions. The results are compiled in Table 3 below.

[0083] [Tables3] ECH2 Initial curvature (mm) Final curvature (mm) MD 0 0 CMD -2 -2 Corners -2 -2

[0084] This ECH2 sample shows that the curvature of the structure is further improved and is less than 2 mm, even after oven drying.

Claims

Demands

1. Multilayer structure (1) for the production of a floor or wall covering comprising a backing layer (2) based on linoleum reinforced by a reinforcing frame (3), a wear layer (4) of thermoplastic polymer transparent at least to the light in the visible range and bonded to the backing layer (2), and a decorative printing layer (5) positioned between the wear layer (4) and the backing layer (2), characterized in that it comprises a cross-linked varnish layer (11) deposited on an underside of the backing layer (2).

2. Multilayer structure (1) according to claim 1, characterized in that the varnish layer (11) is polyurethane or acrylic based.

3. Multilayer structure (1) according to any one of the preceding claims, characterized in that the varnish layer (11) has a thickness of between 5 and 30 pm, preferably between 10 and 20 pm.

4. Multilayer structure (1) according to any one of the preceding claims, characterized in that the varnish layer (11) comprises a textured underside.

5. Multilayer structure (1) according to any one of the preceding claims, characterized in that the wear layer (4) is made of PET, TPU, PP, PETG, ionomer, or PVC.

6. Multilayer structure (1) according to any one of the preceding claims, characterized in that the decorative printing layer (5) is an ink layer printed: - on a lower face of the wear layer (4) which is transparent, or; - on a upper face of the backing layer (2), or; - on an upper face of a support layer (8) made of thermoplastic or of a paper layer impregnated with a binder.

7. Multilayer structure (1) according to any one of the preceding claims, characterized in that the back layer (2) has a thickness of between 1.3 mm and 3 mm, preferably between 1.6 mm and 2.2 mm.

8. Multilayer structure (1) according to any one of the preceding claims, characterized in that it has a thickness between 1.4 mm and 3.5 mm.

9. Multilayer structure (1) according to any one of the preceding claims, characterized in that the reinforcing reinforcement (3) is embedded in the thickness of the back layer (2) at the level of a lower and / or upper face of the back layer (2).

10. Multilayer structure (1) one of the preceding claims, characterized in that the reinforcing frame (3) is in the form of a jute canvas, a paper-based frame, a non-woven or woven polyester grid, a cotton fabric or natural fibers.

11. A method for manufacturing a multilayer structure (1) according to any one of the preceding claims, characterized in that the varnish layer (11) is crosslinked by means of exposure to ultraviolet radiation, followed or preceded by exposure to a monochromatic laser emitter of the excimer laser type.

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