Mineral fiber reinforcement mesh for flexible flooring tiles

Abstract

The invention relates to a laminated fiberglass / grid system for flexible floor tiles, formed of a fiberglass web bonded by a first organic polymer, having an air permeability, measured according to standard NF EN ISO 9237 at a pressure of 200 Pa, of between 6,000 and 12,000 l / m².s, and a glass fiber grid having a fiber content of between 30 and 150 tex, coated by a second organic polymer. It also relates to a flexible floor tile comprising such a laminated fiberglass / grid system as its sole reinforcing element.

Description

Title of the invention: Mineral fiber reinforcement mesh for flexible flooring tiles

[0001] The invention relates to a complex glass fiber reinforcement for flexible floor covering tiles allowing to limit the coefficient of thermal expansion of the tiles, as well as the flexible floor covering tiles comprising this complex glass fiber reinforcement.

[0002] LVT (Luxury Vinyl Tile) flooring is a multi-layered PVC-based flooring that is thicker and more durable than standard PVC flooring. It is generally sold not in rolls, but as individual tiles, which may be self-adhesive.

[0003] A distinction is traditionally made between, on the one hand, flexible flooring tiles conforming to ISO 24344 / 2008, and on the other hand, rigid tiles that do not deflect significantly under their own weight when held at one end. The latter are generally laid loosely, without adhesives, with a peripheral space, called an expansion joint, between the flooring and the wall. When rigid tiles are subjected to a temperature increase (exposure to sunlight near a window, proximity to a heater, underfloor heating, etc.), they expand by pushing against each other without deforming, provided that the expansion joint is sufficiently wide.

[0004] In the case of flexible floor coverings, it is generally not sufficient to provide a peripheral expansion joint. When flexible PVC tiles are exposed to a temperature increase, thermal expansion in the direction of the plane of the covering almost always causes a very unsightly warping.

[0005] The present invention aims to provide a solution to the occurrence of such flatness defects in flexible floor covering tiles by effectively limiting the coefficient of thermal expansion of the tiles, without, however, making them excessively rigid.

[0006] It is known to use reinforcing structures based on organic or mineral fibers to reinforce PVC tiles. The reinforcing structures can be individual fibers, non-woven fabrics, woven textiles, grids, particularly those based on glass fibers, or a combination of such structures. Of course, when it is desired to limit the thermal expansion of the tiles, the use of reinforcing structures based on mineral fibers, which inherently have a much lower coefficient of thermal expansion than thermoplastic polymers, is particularly advantageous. extremely interesting.

[0007] The difference between the coefficient of expansion of the mineral fiber reinforcement and that of the thermoplastic organic polymer can, however, cause delamination when the bond between the reinforcement and the thermoplastic polymer is insufficient.

[0008] The risk of delamination is particularly significant in the case of panels manufactured not by coating / gelling PVC with plastisol, but by bringing the reinforcing mesh into contact with plasticized PVC under the application of heat and pressure. The plasticized PVC may then be in the form of granules, sheets, or a mass of PVC extruded directly onto the reinforcement. In this type of manufacturing process using pre-plasticized PVC rather than plastisol, the interface between the reinforcing mesh and the plasticized PVC constitutes a zone of weakness that can initiate delamination.

[0009] The aim of the present invention was to provide reinforcing mesh for PVC tiles that limits both the thermal expansion of flexible PVC tiles and the risk of delamination at the PVC / reinforcing mesh interface. The Applicant discovered that it was possible to achieve this dual objective by using sufficiently "open" web / grid laminates to allow the PVC, in contact with the reinforcing mesh, to penetrate into and through it, thereby establishing adhesive contact with the thermoplastic polymer located on the other side of the mesh. The adhesive contact between the two layers of thermoplastic polymer surrounding the mineral fiber-based reinforcing mesh is stronger the larger the contact surface between the two polymer layers.Using laminated mesh / grid reinforcement with a mesh that is too "open" does not effectively limit the thermal expansion of the slabs if the laminate grid does not effectively compensate for the reduced mechanical resistance of the mesh.

[0010] The web / grid laminates of the present invention therefore combine a web exhibiting relatively high air permeability and a grid made of high-quality yarns.

[0011] The present application relates more particularly to a veil / grid laminate, formed - of a glass fiber veil, bonded by a first organic polymer, exhibiting an air permeability, measured according to standard NF EN ISO 9237 at a pressure of 200 Pa, between 6000 and 12000 l / m2.s, preferably between 7000 and 11000 l / m2.s, - of a glass fiber grid having a content between 30 and 150 tex, coated by a second organic polymer.

[0012] As explained in the introduction, the high air permeability of non-woven fiberglass mats used in the manufacture of laminates is an important parameter. If the The fiberglass mesh forming the web was denser, meaning the PVC layers adjacent to the laminate would be in contact primarily with the web / mesh assembly, but very little with the other PVC layer in contact with the other face of the assembly. However, direct adhesive contact between the two PVC layers on either side of the assembly is an important factor in preventing delamination.

[0013] The glass veil used in the present invention is a non-woven textile, also called a non-woven fabric, manufactured by a wet process (wetlaid) or by a dry process (dry laid). For example, by a dry process with carding (drylaid carded) or by an aerodynamic process (airlaid). The glass veil is preferably a non-woven textile manufactured by a wet process.

[0014] It advantageously contains short and relatively large glass fibers, having a length between 10 and 30 mm, in particular between 12 and 25 mm, advantageously having a diameter between 11 pm and 18 pm, preferably between 12 pm and 17 pm.

[0015] The organic polymer used to bind the glass fibers of the glass fiber veil can, in principle, be any organic polymer that, after drying and hardening, provides the glass veil with a cohesion that resists contact between the bonded veil and water. The organic polymer of the binder is therefore preferably a thermosetting polymer advantageously chosen from among urea-formaldehyde resins, melamine-formaldehyde resins, phenol-formaldehyde resins, acrylic resins, and mixtures of these resins, preferably from among urea-formaldehyde resins.The thermosetting polymer may also be a formaldehyde-free polyester binder advantageously formed by esterification of sugars and / or hydrogenated sugars, and at least one polycarboxylic acid, preferably citric acid, in the presence of a catalyst, preferably sodium hypophosphite, such as those described in applications WO10 / 029266, WO2013 / 014399, WO2013 / 021112, WO2015 / 132518, WO2015 / 159012, or a thermosetting binder obtained from Maillard reagents, as described in international application WO2007 / 014236.

[0016] It is advantageously applied in the form of a solution of monomeric or oligomeric reagents (formaldehyde-based resins) or in the form of latex (acrylic resins).

[0017] The hardening of the glass fiber veil binder is done for example by heating at a temperature between 180 and 230 °C for a period of between 5 seconds and 5 minutes, preferably between 10 seconds and 2 minutes.

[0018] The binder is generally applied in a quantity, expressed in dry matter, of between 10 and 35% by weight, preferably between 15 and 25% by weight relative to the total weight of the glass fiber veil.

[0019] The bonded glass fiber veil, used for the manufacture of the complex, advantageously has a surface mass between 25 and 50 g / m2, preferably between 30 and 45 g / m2, in particular between 32 and 40 g / m2.

[0020] Its thickness is advantageously between 250 pm and 500 pm, preferably between 270 and 400 pm, and in particular between 300 pm and 350 pm.

[0021] The glass veil binder advantageously contains flame-retardant agents selected from metal hydroxides, metal hydrates, and hydrated carbonates. Examples of such mineral flame retardants include magnesium hydroxide (Mg(OH)2) and aluminum hydroxide (AlO(OH)3), the most commonly used, as well as huntite (MgCO3CaCO3) and hydromagnesite (MgCO3Mg(OH)2-4H2O). These flame retardants degrade by an en-othermal reaction, releasing water and / or CO2.

[0022] A glass fiber mesh (or glass fiber grid) is then glued onto the glass fiber veil described above. This glass fiber mesh can be a knitted mesh, a woven mesh, or a laid scrim. A knitted glass fiber mesh is preferred.

[0023] The warp and weft yarns of the grid preferably have a count between 30 and 140 tex. The count of the warp yarns can in principle be different from that of the weft yarns, but in order to give the flexible PVC tile the most homogeneous properties possible, it is preferable that the glass yarn grid be made up of weft and warp yarns all having the same count.

[0024] The “density” of the weft and warp yarns is advantageously between 3 and 4 yarns / cm.

[0025] In a preferred embodiment, the glass fiber yarns forming the grid are twisted yarns. This twisting generally increases the breaking strength of the yarns and the grid.

[0026] The glass wires forming the grid advantageously have between 10 and 30 twists / m, preferably from 15 to 28 twists / m.

[0027] The adhesive used to fix the grid to the glass veil preferably also serves as a binder or coating for the grid, or, conversely, the second organic polymer coating the grid advantageously also serves as an adhesive fixing the grid to the glass veil. An unbonded glass fiber grid, called greige, is impregnated with a polymeric composition ("adhesive") and brought into contact under pressure, immediately after impregnation, with the bonded glass fiber veil, the binder of which has already hardened. The process consists of saturating the grid with a suspension of the second organic polymer by a scrunching process, then pressing the materials together, and finally drying the assembly by exposure to infrared radiation and / or by convective drying (hot air) and / or by contact drying with heated rollers.

[0028] The glass wire grid is then glued to the glass fiber veil by means of the second organic polymer which envelops the grid.

[0029] The adhesive that ensures adhesion between the grid and the veil may, however, be different from the coating on the grid. This embodiment can be particularly advantageous for turbinated grids which, in their unbound state, do not form a greige-type textile that allows for easy handling of the grid for contact with the veil. For turbinated grids, it may therefore be beneficial to prepare them beforehand "offline" using a binder different from the adhesive that will be used to bond the grid to the glass veil.

[0030] The second organic polymer used as a coating for the glass wire grid can be chosen, for example, from the group formed by acrylic copolymers, styrene-butadiene rubbers (SBR), poly(vinyl acetate), poly(vinyl chloride) (PVDC), poly(vinyl chloride) (PVC) and copolymers based on vinyl acetate, vinylidene chloride, vinyl chloride and / or other comonomers.

[0031] The final laminate fabric / grid advantageously has a surface mass of between 70 and 150 g / m2, preferably between 75 and 120 g / m2. Its total thickness is between 0.45 and 0.80 mm, preferably between 0.50 and 0.75 mm.

[0032] Its tensile strength is between 400 and 1000N / 5cm.

[0033] The veil / grid laminate generally has an organic matter content, finished by the loss on ignition (LOI), which is between 30 and 35% relative to the total weight of the laminate.

[0034] The present application also relates to a flexible tile for floor coverings based on poly(vinyl chloride) (PVC) comprising a veil / grid laminate as described above.

[0035] In this application, the term "flexible tile" or "flexible floor covering" refers to multilayer structures exhibiting sufficient flexibility to meet the requirements of ISO 24344:2008. In this standard, flexibility is defined as the ability of a multilayer structure to be wound around a mandrel with a diameter of 20 mm without cracking or splitting. The tile in this application, as tested according to ISO 24344:2008, therefore exhibits no breaks, cracks, splits, or other permanent defects resulting from the winding process.

[0036] The voile / grid laminate is preferably the only reinforcement of the flexible slab of the invention, in other words the reinforcement slab does not include any other textiles based on fibers or glass fibers.

[0037] The laminate is located in the middle area of ​​the slab, hereinafter referred to as the base layer, and is sandwiched between two layers of plasticized PVC in adhesive contact respectively with the two faces of the laminated veil / grid.

[0038] In a preferred embodiment, the flexible flooring tile of the present invention comprises - a base layer comprising an upper face and a lower face, said base layer being made of a sheet / grid laminate according to the invention, and of two layers of plasticized PVC in contact respectively with the two faces of the sheet / grid laminate, - a decorative layer printed on the top face of the base layer, - a transparent wear layer, covering the decorative layer printed on the top face of the base layer.

[0039] In this application, the upper face of a layer means the face of said layer oriented towards the user once the floor covering is laid and ready for use, and the lower face of a layer means the face oriented towards the ground after the floor covering has been laid. By analogy, the adjective "lower" when describing a structure, in particular a layer, indicates that this structure / layer is closer to the ground / substrate than another structure / layer. The adjective "upper" indicates that the structure / layer in question is farther from the ground than another structure / layer.

[0040] The base layer of the slab of the present invention is therefore a three-layer structure consisting of a web / grid laminate and two thermoplastic polymer layers, preferably PVC, which are in adhesive contact with both faces of the web / grid laminate. Thanks to the high air permeability of the web used to manufacture the laminate, the two thermoplastic polymer layers are also in direct contact with each other through the openings in the web.

[0041] The PVC of the two thermoplastic sheets or layers of the base layer is non-expanded, plasticized PVC containing fillers. Its density is typically greater than 1.4 g / cm3, preferably greater than 1.5 g / cm3 and generally does not exceed 2.0 g / cm3.

[0042] Plasticized PVC generally contains an amount of plasticizer between 20 and 70 parts, preferably between 30 and 50 parts per 100 parts of PVC resin.

[0043] The plasticizers are known plasticizers. Examples include diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), dioctyl terephthalate (DOTP), diisononyl 1,2-cyclohexane-dicarboxylate (DINCH), plasticizers of the benzoate and adipate families, epoxidized soybean oil (HSE) and octyl epoxystearate (ESO).

[0044] The quantity of fillers present in the plasticized PVC of the two layers of the base layer is generally between 70 and 300 parts, preferably between 100 and 200 parts per 100 parts of PVC resin.

[0045] Mineral fillers such as clays, silica, chalk, kaolin, talc and calcium carbonate can be used in a known manner.

[0046] The base layer, formed by the veil / grid laminate and by the two PVC layers in contact with it, generally has a total thickness of between 0.8 and 2.8 mm.

[0047] The base layer of the flexible panel according to the invention cannot, in principle, be manufactured by coating the web / grid complex with a plastisol composition followed by a heating-curing gelation step. Indeed, the high open-pore size of the reinforcing mesh makes the coating step difficult, as the liquid plastisol is generally not sufficiently retained by the web / grid laminate of the present invention.

[0048] Therefore, for the manufacture of the base layer, PVC is used which has been previously plasticized, in the form of granules, extruded or calendered sheets or in the form of a viscous mass extruded hot directly onto the sheet / laminate complex.

[0049] A manufacturing process using extruded PVC sheets is described for example in international application WO2020 / 152408.

[0050] When using plasticized PVC sheets, the fixing of the sheets to the reinforcing frame is preferably done by thermolamination.

[0051] The upper surface of the base layer is then printed with a design, called the decorative layer, which will be visible through the transparent or translucent wear layer covering the decorative layer. The decorative layer can, in principle, be applied by any known printing process, and examples include screen printing, gravure printing, offset printing, and inkjet printing.

[0052] According to the invention, the top wear layer is transparent or translucent to visible light so that the decorative layer printed on the top surface of the base layer can be seen through the wear layer. The wear layer is generally made from a thermoplastic polymer, for example, from polyvinyl chloride. This layer preferably has a thickness of between 0.10 and 1.0 mm. The wear layer can be obtained by extrusion, calendering, pressing, or by coating / gelling a plastisol. Preferably, the wear layer is a gelled PVC plastisol layer, advantageously comprising 20 to 70 parts plasticizer to 100 parts PVC resin. The plasticizers can be chosen, for example, from those listed above in relation to the PVC of the base layer.

[0053] The flexible flooring tile of the present invention may further comprise a support layer which is in contact with the underside of the layer of base. The support layer is preferably made of poly(vinyl chloride) (PVC), expanded or not, and advantageously has a thickness of between 0.4 and 5 mm, preferably between 0.4 and 3 mm.

[0054] The support layer may be compact (dense) or foamed (expanded) and may comprise one or more sub-layers. It may be obtained by any process well known to those skilled in the art, in particular by calendering, pressing, extrusion or coating / gelling.

[0055] When it is a foam-type layer, the density can be between 0.2 and 0.5 g / cm3, preferably between 0.30 and 0.40 g / cm3. Example

[0056] A slab A according to the invention and a comparative slab B having the following technical characteristics are prepared:

[0057] Slab A: The base layer is made of PVC reinforced with a laminated fiberglass / grid layer consisting of a non-woven fiberglass fleece with a length of 18 mm and a diameter of 13 µm, bonded with a urea / formaldehyde binder, a surface mass of 35 g / m², a 20% LOA (Lower strand length), an air permeability of 9200 l / m².s at 200 Pa, and a knitted grid (3.5 threads / cm; 34 tex (warp); 68 tex (weft); acrylic binder). The total thickness of the tile (including the wear layer, base layer, and backing layer) is 4 mm.

[0058] Slab B: Base layer in PVC reinforced by a non-woven fabric of E-glass fibers with a length of 18 mm and a diameter of 13 µm, bonded by a urea / formaldehyde binder, surface mass of 35 g / m², LOI 20%, air permeability 9200 l / m².s at 200 Pa. The thickness of the slab (including wear layer, base layer and support layer) is 4 mm.

[0059] The thermal expansion of these two slabs is measured as follows by dynamic mechanical temperature analysis (DMTA) using a DMTA device, model Q800 from TA Instruments:

[0060] The PVC tile is cut into 25 mm x 6 mm samples (in the longitudinal (warp) and transverse (weft) directions). The sample is attached between two jaws of the DMTA apparatus, which subject the sample to tensile stress. A furnace then closes around the sample. The sample is subsequently subjected to periodic tensile mechanical stress: deformation of 0.001%, frequency 1 Hz.

[0061] The sample is first cooled at a rate of 2°C / min from ambient temperature to 5°C, then heated at a rate of 1°C / min to 50°C, and again cooled to 5°C at a rate of 2°C / min. The heating / cooling cycle is performed 3 times in total for each sample.

[0062] During the second and third cycles, an increase in length is recorded of the sample between 12 °C (Li2) and 38 °C (L38), and the expansion is calculated over this temperature range according to the following formula:

[0063] Expansion (%): 100 x (L38 - Li2) / Li2

[0064] The results correspond to the average calculated over the two heating / cooling cycles.

[0065] For slab A according to the invention, the thermal expansion is 0.13% in the direction of the 34 tex warp yarns (machine direction) and between 0.11 and 0.14% in the direction of the 68 tex weft yarns (cross-machine direction).

[0066] For the comparative slab B, the thermal expansion is 0.19% in the "warp" direction (machine direction) and 0.22% in the "weft" direction (cross-machine direction).

[0067] These results show that the use of a glass fiber veil / glass wire grid laminate according to the invention makes it possible to effectively limit the thermal expansion of flexible slabs compared to identical slabs reinforced by a simple non-woven glass fiber veil.

[0068] The slabs do not present any delamination problems.

Claims

Demands

1. Laminated veil / grid, formed of - a veil of glass fibers, bonded by a first organic polymer, having an air permeability, measured according to standard NF EN ISO 9237 at a pressure of 200 Pa, of between 6000 and 12000 l / m2.s, - a grid of glass fibers having a count between 30 and 150 tex, coated by a second organic polymer.

2. Veil / grid laminate according to claim 1, characterized in that the glass fiber grid is bonded to the glass fiber veil by means of the second organic polymer.

3. Laminated veil / grid according to claim 1 or 2, characterized in that the glass fibers forming the veil have a diameter between 12 and 17 pm, and a length between 12 and 25 mm.

4. Laminated veil / grid according to any one of the preceding claims, characterized in that the glass fiber veil has a surface mass between 25 and 50 g / m2, preferably between 30 and 45 g / m2, in particular between 32 and 40 g / m2.

5. Laminated veil / grid according to any one of the preceding claims, characterized in that the glass fiber veil has a thickness between 250 pm and 500 pm, preferably between 270 and 400 pm, and in particular between 300 pm and 350 pm.

6. Laminated voile / grid according to any one of the preceding claims, characterized in that the glass wire grid is made up of weft and warp wires all having the same count.

7. Laminated web / grid according to any one of the preceding claims, characterized in that the "density" of the weft and warp yarns is between 3 and 4 yarns / cm.

8. Laminated veil / grid according to any one of the preceding claims, characterized in that the glass fibers have between 10 and 30 twists / m, preferably from 15 to 28 twists / m.

9. Laminate veil / grid according to any one of the preceding claims, characterized in that the laminate has a surface mass of between 70 and 150 g / m2, preferably between 75 and 120 g / m2, and a thickness of between 0.45 and 0.80 mm, preferably between 0.50 and 0.75 mm.

10. A veil / grid laminate according to any one of the preceding claims, characterized in that the grid is a knitted grid, a woven grid or turbinated grid, preferably a knitted grid.

11. Flexible flooring tile based on poly(vinyl chloride) (PVC) comprising, as the sole reinforcing structure, a veil / grid laminate according to any one of the preceding claims.

12. Flexible flooring tile according to claim 11, characterized in that it comprises - a base layer having an upper face and an lower face, said base layer being made of a veil / grid laminate according to any one of claims 1 to 9, and of two layers of plasticized PVC in contact respectively with the two faces of the veil / grid laminate, - a decorative layer printed on the upper face of the base layer, - a transparent wear layer, covering the decorative layer printed on the upper layer of the base layer.

13. Flexible floor covering tile according to claim 11 or 12, characterized in that it further comprises a support layer, in contact with the underside of the base layer.

14. Flexible flooring tile according to any one of claims 11 to 13, characterized in that the base layer has a total thickness of between 0.8 and 2.8 mm and the transparent wear layer has a thickness of between 0.1 mm and 1.0 mm.