FR2873618A1 - Multi-layer material for covering surfaces by thermoforming has surface, intermediate and backing layers of compatible polymers - Google Patents

Abstract

The multi-layer material, for use in motor vehicles, ships and homes, consists of a surface layer (2) based on polymers of the polyolefin family and conferring a visual aspect, mechanical strength and resistance to chemical aggression and UV rays, an intermediate layer (3) of compatible polymers, and a lower backing layer (6) based on materials compatible with the polymers of the intermediate layer and in contact or associated with the surface to be covered. The surface and intermediate layers are preferably 0.4 mm thick, with the surface layer made transparent, translucent, coloured in the mass or printed. The backing layer can be a single material or a mixture of materials selected from the group comprising non-woven textiles, foams, polymers, especially high-fill polyolefins. The surface layer is co-extruded and then combined immediately with the intermediate and backing layers by high-temperature rolling.

Description

MULTILAYER MATERIAL FOR COATING SURFACES

  THERMOFORMING, METHOD OF OBTAINING AND METHOD OF

THERMOFORMING

  The present invention relates to a multilayer material for surface coating by a subsequent thermoforming process. The invention also relates to a process for obtaining such a multilayer material. The invention relates to a use of a multilayer material for coating surfaces in a thermoforming process. The invention finally relates to a thermoforming process with a multilayer material.

  Multilayered complex materials are increasingly used in the automotive, marine, and interior industries, both indoors and outdoors. These materials are suitable for the coating of various surfaces, such as in particular the floor of the passenger compartment, the dashboard, door panels, bodies, etc. By their constitution, such materials are a coating whose function is not only to ensure the finish of the outer surface, but also to achieve if necessary a shock absorption, and a sound insulation as well as thermal. In addition, these materials have mechanical strength capabilities, for example abrasion, scratching and punching, resistance to chemical attack and ultraviolet radiation. These materials are not only used to cover flat surfaces, but they also have shaping possibilities, including molding and thermoforming. An additional asset is their ease of maintenance, as well as a great stability in time after installation, while being perfectly recyclable at the end of their life.

  State of the art In this field of surface coatings, it has long been proposed to use complexes based on polymeric materials, such as for example polyvinyl chloride (PVC) or the like, generally associated with a structure reinforcement which can be either embedded in the mass of the material, or reported against the back side of the latter. Very often, this thermoplastic sheet, reinforced or not, is associated with an underlayer, in particular foam, and this to improve comfort and thermal and / or sound insulation.

  However, current standards are aimed at phasing out PVC-type materials that can release chlorinated compounds in the event of fire or incineration of waste.

  Also known from EP-0,968,875 a multilayer material, used more specifically as a floor covering of the passenger compartment of a vehicle. This material comprises a lower layer also called a support layer, intended to be in contact with the surface to be coated and ensuring comfort, shock absorption, soundproofing. This support layer is covered with a surface layer, capable of receiving a decoration, the visible face can have a smooth, glossy or matte and / or grained, aspect obtained simultaneously with the production of the material without subsequent treatment.

  In such a material, the support layer and the surface layer are intimately bonded to one another and are made from components selected from the family of polyolefin-based polymers. The combination of the two layers with each other is carried out by complexing the two constituents during the extrusion of the surface film, the lamination being carried out by calendering immediately at the exit of the extruder from the surface film, whereas the latter is still at elevated temperature.

  It is also known from WO-03 / 004.267 a multilayer material for coating surfaces having a support layer intended to be in contact and / or associated with a surface to be coated, a lower layer to be associated with the layer. carrier, with a polyolefin-based composition and fillers, which is colored or printed and has a grainy appearance, and a top layer associated with it, with a similar composition, unloaded, possibly colored, and which has the characteristic of to be translucent.

  However, it has been found that for these materials the properties of strength and surface appearance could be further improved. In addition, winding or curling phenomena, also known as tiling are observable. These phenomena create difficulties during the implementation steps, and in particular thermofollages that follow.

  SUMMARY OF THE INVENTION A major problem to be solved by the invention is to develop a multilayer material which simultaneously has a particularly pleasing surface, surface strength properties and internal absorption capabilities. A second problem is the obtaining of a multilayer material having a dimensional stability and which is particularly suitable for subsequent thermoforming operations. A third problem is the implementation of a method for obtaining such a multilayer material. A fourth problem is the use of a multilayer material for coating surfaces by thermoforming.

  In a known manner, a multilayer material, intended for surface coating by thermoforming, comprises: a surface layer, based on polymers selected from the family of polyolefins, imparting a visual appearance and mechanical strengths, resistance to chemical attack, UV, an intermediate layer, based on polymers compatible with the polymers of the surface layer and selected from the family of polyolefins, and a lower support layer, based on materials compatible with the polymers of the intermediate layer and entering into contact and / or associated with the surfaces to be coated, ensuring comfort, shock absorption, thermal and sound insulation.

  According to a first aspect of the present invention, the material is characterized in that the surface layer is based on a polypropylene composition, an acrylate-patterned polymer and a compatibilizer.

  The compatibilizer ensures compatibility between the hydrophobic polypropylene and the acrylate pattern polymer polar nature. In other words, by the choice of acrylate polymer surface, the multilayer will prove to be a particularly effective material. This surface layer associated with the intermediate layer is an alternative to the products known under the name of thermosetting gel coat.

  Since the acrylate-patterned polymer imparts rigidity properties to the surface, its use as an insulated surface layer with a conventional thickness, complexed on a lower support layer will result in too much rigidity for the resulting multilayer. If, in order to reduce the stiffness, the thickness of the surface layer is lower, it is no longer possible to carry out a subsequent thermoforming of the multilayer because of the unwanted elongations resulting in a multilayer product lacking withstand. Thus, it has been found that the presence of an intermediate layer makes it possible to significantly reduce the thickness of the acrylate-patterned polymer surface layer of the multilayer. The intermediate layer will prevent tiling phenomena.

  Most advantageously, the acrylate-patterned polymer may be poly (methylmethacrylate) or PMMA. The surface layer may favorably comprise substantially: from 60% to 70% by weight of polypropylene; from 20% to 35% by weight of acrylate-patterned polymer; from 5% to 10% by weight of compatibilizer; and from 0 to 15% by weight of fillers.

  Preferably, the surface layer may comprise substantially 70% by weight of polypropylene, 25% by weight of acrylate-patterned polymer and 5% by weight of compatibilizer. The thickness of the surface layer may be substantially between 0.1 mm and 0.6 mm, preferably substantially equal to 0.4 mm. The thickness of the intermediate layer may be substantially between 0.1 mm and 1 mm, preferably substantially equal to 0.4 mm.

  In order to impart an attractive aesthetic appearance, the surface layer may be substantially transparent or translucent and / or is mass-colored and / or may be printed. Depending on the desired application, the materials of the lower support layer may be chosen alone or as a mixture, in the group comprising textiles, and more particularly nonwoven fabrics, foams, polymers, particularly those selected in the family of highly loaded polyolefins, multilayer complexes and others.

  According to a second aspect of the invention, a method for obtaining a multilayer material for surface coating comprises the steps of: coextruding a surface layer, based on a polypropylene composition, an acrylate-patterned polymer, a compatibilizer and fillers and an intermediate layer, based on polymers selected from the family of polyolefins; and - complexing the surface layer and the intermediate layer to a lower support layer, based on materials compatible with the polymers of the intermediate layer, immediately at the exit of the step of coextruding the surface layer and the intermediate layer.

  The lamination can be carried out by high temperature calendering immediately at the exit of the extruder from the surface layer and the intermediate layer.

  According to a third aspect of the present invention, a multilayer material comprising in particular a surface layer, based on a polypropylene composition, an acrylate-patterned polymer, a compatibilizer and fillers, an intermediate layer, base of polymers compatible with the surface layer polymers and selected from the family of polyolefins, and a lower support layer, based on materials compatible with the polymers of the intermediate layer is used to coat surfaces in a thermoforming process ulterior.

  According to a fourth aspect of the invention, a thermoforming process is implemented and comprises the main steps of: - applying a multilayer material, as explained above, against a support to be covered; heating the multilayer material and the support to a thermoforming temperature.

  In a first exemplary embodiment, the thermoforming temperature may be chosen substantially less than 150 C, so as to obtain a gloss effect for the surface layer of the multilayer material. In a second exemplary embodiment, the thermoforming temperature may be chosen substantially greater than 155 ° C., so as to obtain a matting effect for the surface layer of the multilayer material.

Brief description of the figures

  The invention will be better understood and its various advantages and different characteristics will become more apparent in the following description, of the nonlimiting exemplary embodiment, with reference to the appended schematic drawing, in which the single FIGURE represents a simplified view of the process of FIG. obtaining the multilayer material according to the invention.

  Embodiments of the invention A multilayer complex (1) according to the invention is produced comprising, on the one hand, a surface layer (2) produced from a mixture of polyolefin and thermoplastic based on acrylate (PMMA) and pigments. for coloring, and a thickness of 0.4 mm. On the other hand, this surface layer (2) is associated with an intermediate layer (3) produced from a polyolefin and pigments for coloring, with a thickness of 0.4 mm.

  The surface layer (2) and the intermediate layer (3) are obtained by coextrusion (4) and are associated with a support (6) which may be of different types: - a polypropylene foam having a thickness of 3 mm and a density of 67 kg / m3; a needled polyester nonwoven of 120 g / m2; a needled polypropylene nonwoven of 180 g / m 2; or a support based on polyolefin and thermoplastic elastomer and heavily loaded with 2500 g / m2.

  This combination is obtained by complexing by means of two rolls of the shell (7).

  In a first possibility of using the multilayer material with its PMMA-based surface layer, the thermoforming temperature is chosen to be substantially less than 150 ° C., so as to obtain a gloss effect for the surface layer and thus for the product. final. In a second possibility of using the multilayer material with its PMMA-based surface layer, the thermoforming temperature is chosen to be substantially greater than 155 ° C., so as to obtain a matting effect for the surface layer.

  The change of structure, around 155 C, gives the material a change of brightness. Transformation beyond this temperature fats to obtain a dullness for the surface layer. This point can be very interesting for the negative thermoforming process.

  The present invention is not limited to the embodiments described and illustrated. Many modifications can be made, without departing from the scope defined by the scope of the set of claims.

Claims (12)

  Multilayer material, for surface coating by thermoforming, comprising: a surface layer (2), based on polymers selected from the family of polyolefins, imparting a visual appearance and mechanical strength, resistance to chemical attack, UV, an intermediate layer (3), based on polymers compatible with the polymers of the surface layer (2) and selected from the family of polyolefins, and a lower support layer (6), based on materials compatible with the polymers of the intermediate layer (3) and coming into contact with and / or associated with the surfaces to be coated, providing comfort, shock absorption, thermal and sound insulation, characterized in that the surface layer (2) is based on a polypropylene composition, an acrylate-patterned polymer and a compatibilizer.   2. Material according to claim 1, characterized in that the acrylate-patterned polymer is a poly (methyl methacrylate).   3. Material according to claim 1 or 2, characterized in that the surface layer (2) comprises substantially: - from 60% to 70% by weight, preferably 70% by weight, of polypropylene; From 20% to 35% by weight, preferably 25% by weight, of acrylate-patterned polymer; from 5% to 10% by weight, preferably 5% by weight, of compatibilizer; and from 0 to 15% by weight, preferably 0% by weight, of fillers.   4. Material according to any one of the preceding claims, characterized in that the thickness of the surface layer (2) is substantially between 0.1 mm and 0.6 mm, preferably substantially equal to 0.4 mm. , and in that the thickness of the intermediate layer (3) is substantially between 0.1 mm and 1 mm, preferably substantially equal to 0.4 mm.   5. Material according to any one of the preceding claims, characterized in that the surface layer (2) is substantially transparent or translucent and / or is colored in bulk and / or has an impression.   6. Material according to any one of the preceding claims, characterized in that the materials of the lower support layer (6) are chosen alone or as a mixture, in the group comprising textiles, and more particularly the nonwoven fabrics, the foams, polymers, particularly those selected from the family of highly filled polyolefins, multilayer complexes.   A method for obtaining a multilayer material (1) for surface coating, comprising the steps of: - coextruding a surface layer (2), based on a polypropylene composition, of a polymer an acrylate unit, a compatibilizer and fillers and an intermediate layer (3), based on polymers selected from the family of polyolefins; and complexing the surface layer (2) and the intermediate layer (3) with a lower support layer (6), based on materials compatible with the polymers of the intermediate layer, immediately out of the step of coextruding the surface layer (2) and the intermediate layer (3).   8. Process according to claim 7, characterized in that the complexing is carried out by calendering (7) at a high temperature immediately at the exit of the extruder (4) from the surface layer (2) and the intermediate layer ( 3).   9. Use of a multilayer material (1), comprising in particular a surface layer (2), based on a polypropylene composition, an acrylate-patterned polymer, a compatibilizer and fillers, an intermediate layer (3), based on polymers compatible with the polymers of the surface layer (2) and selected from the family of polyolefins and a lower support layer (6), based on materials compatible with the polymers of the intermediate layer ( 3) for coating surfaces in a thermoforming process.   10. A method of thermoforming, wherein the main steps of: applying a multilayer material according to any one of claims 1 to 6 against a support to be coated; heating the multilayer material and the support to a thermoforming temperature.   11. The method of claim 10, characterized in that the thermoforming temperature is chosen substantially less than 150 C, so as to obtain a gloss effect for the surface layer of the multilayer material.   12. The method of claim 10, characterized in that the thermoforming temperature is chosen substantially greater than 155 C, so as to obtain a matting effect for the surface layer of the multilayer material.   Exhibitor TEXTILES AND PLASTICS CHOMARAT Mandataire Cabinet LAURENT & CHARRAS