Multilayer comprising a polyolefin-based main layer

Abstract

The present invention relates to a multilayer comprising at least: a) a main layer having a composition, over its entire thickness, comprising at least 70% by weight of polyolefin, b) a surface layer, c) a protective layer. The invention also relates to the use of this multilayer in the automotive or leatherware field.

Description

[0001] MULTILAYER COMPRISING A MAIN LAYER BASED ON

[0002] POEYOEEFINE

[0003] Field of invention

[0004] The present invention relates to a multilayer whose main layer comprises at least one polyolefin and polyurethane. The invention also relates to the use of this multilayer in the following fields: automotive, leather goods, etc.

[0005] Prior art

[0006] In the automotive field, the functions of the dashboard and the door panel are generally based on a main structure (insert) made of thermoplastic, often polyolefin, although other materials such as ABS can be used. To meet current or future environmental requirements, manufacturers must develop structures incorporating recycled plastic materials (RPM). One of the main constraints related to RPM is aesthetic, as RPMs are generally dark in color and not controlled in terms of shades. Thus, these new structures, due to their material design (presence of RPM), may not meet the expectations of designers. There is therefore a need to develop a technical sheet (multilayer made of polymer materials) to cover these structures and, consequently, have a satisfactory finish, for example, light-colored, plain variants. ..

[0007] Another issue concerns the association between the technical sheet (multilayer) and the main structure based on MPR. Indeed, the technical sheet must be compatible with conventional techniques such as overmolding (single-step process), display (Hot Melt bonding), thermocladding (display thermoforming process).

[0008] Therefore, conventional multilayers cannot be used.

[0009] Polyolefin multilayers are commonly used in many areas, including the manufacture of dashboards, door panels and floor mats in the automotive industry.

[0010] The manufacture of multilayers necessarily generates waste (scrap), the recycling of which is generally problematic, in particular due to the presence of polymers of different natures, or even incompatible with each other. Indeed, the different layers of the multilayers can be made of polymers that are incompatible in the molten state, that is to say during the preparation of the layers, the association between the layers being ensured by an adhesive.

[0011] Furthermore, the properties of a layer containing recycled materials are generally not satisfactory, and points of weakness may appear.

[0012] Therefore, there is a need to develop solutions that allow these large quantities of materials to be recycled without requiring prior sorting and therefore additional energy and logistical constraints.

[0013] The present invention makes it possible to solve these problems (compatibility with a structure based on MP R, recycling of MPR in a multilayer) by integrating within a multilayer a specific layer based on polyolefin and advantageously crosslinked polyurethane (varnish).

[0014] Description of the invention

[0015] The present invention relates to a multilayer combining different layers of polyolefin and / or polyurethane.

[0016] More specifically, the present invention relates to a multilayer comprising at least: a) a main layer having a lower FICP face and an upper FSCP face, the main layer having a thickness of between 0.2 and 2.2 mm and a weight of between 150 and 2100 g / m 2 , the main layer having a composition, over its entire thickness, comprising:

[0017] * at least 70% by mass of polyolefin, and

[0018] * advantageously crosslinked polyurethane, b) a surface layer having a thickness less than or equal to 0.12 mm and a weight less than 110 g / m 2 , the surface layer being a multilayer film made of thermoplastic polymer(s), preferably chosen from: polyolefin; polyurethane and their mixtures, the surface layer having a lower face Fies facing the upper face FSCP of the main layer, and an upper face FScs, c) a protective layer facing the upper face FScs of the surface layer, the protective layer being based on crosslinked polyurethane and having a polyurethane weight of between 1 and 25 g / m 2 .

[0019] The presence of at least two layers within the surface layer makes it possible to obtain several technical effects, including:

[0020] - optimize the concentration of anti-UV additives by placing them only in the superficial layers of the surface layer, where they are really needed,

[0021] - functionalize the outer layer (in contact with the protective layer) to maximize the effectiveness of the Corona treatment, for example by increasing the polypropylene content,

[0022] - conceal any visual defects in the main layer, particularly those linked to the integration of MPR (recycled plastic materials) in the formulation,

[0023] - improve abrasion resistance through the use of harder olefinic components (better wear resistance),

[0024] - add a translucent protective layer to enhance durability and aesthetics, especially when the lower layer (in contact with the protective layer) of the surface layer is printed,

[0025] - improve surface sealing (barrier effect) in order to limit the migration of chemical compounds, for example plasticizers or undesirable odorous pollutants,

[0026] - enable other specific functionalities depending on needs and applications.

[0027] The expression "facing" means that two elements are facing each other. This also covers the case where two layers are separated by an intermediate layer, for example by a layer of glue or by glue dots.

[0028] Undercoat

[0029] According to a particular embodiment, the multilayer also comprises a sub-layer, opposite the lower face FICP of the main layer.

[0030] This underlay is advantageously made of textile material or polyolefin foam.

[0031] Thus, the multilayer may comprise a sub-layer made of textile material (for example a jersey, a three-dimensional textile, a non-woven fabric, etc.) which is glued to the lower FICP face of the main layer. In this case, the sub-layer has a thickness advantageously between 0.1 and 6 mm and a weight advantageously between 30 and 300 g / m 2 .

[0032] The multilayer may comprise a polyolefin foam underlayer, which is advantageously extruded or bonded to the FICP underside of the main layer. In this case, the underlayer has a thickness advantageously between 1 and 6 mm, preferably 1.5 to 3 mm, and a density advantageously between 67 and 100 kg / m 3 , preferably between 67 and 71kg / m 3 .

[0033] According to another particular embodiment, the multilayer comprises a polyolefin foam underlayer having a lower FISCM face covered with a crosslinked polyurethane-based layer and an upper FSSCM face which faces the lower FICP face of the main layer.

[0034] Main layer

[0035] The composition of the main layer includes, over its entire thickness, by mass:

[0036] * at least 70% polyolefin, advantageously 80 to 95%,

[0037] * advantageously 30% or less of crosslinked polyurethane, advantageously from 0.5 to 15%, for example from 0.5 to 5%.

[0038] When the multilayer comprises a textile underlayer, the main layer advantageously comprises at least 70% by mass of polyolefin.

[0039] When the multilayer comprises a polyolefin foam underlayer, the main layer advantageously comprises at least 80% by mass of polyolefin.

[0040] Advantageously, the main layer has a density of between 0.89 and 0.97, more advantageously between 0.89 and 0.92. The density may be lower when the main layer has a cellular structure.

[0041] Advantageously, the main layer has a weight between 150 and 1300 g / m 2 , more advantageously between 400 and 500 g / m 2 .

[0042] According to a particular embodiment, the main layer has a weight of between 400 and 800 g / m 2 and a thickness between 0.45 and 0.90 mm, for example a weight of 450 g / m 2and a thickness of 0.5 mm. According to a particular embodiment, the polyolefin of the main layer is a mixture of linear polyolefin and crosslinked polyolefin.

[0043] Advantageously, the composition of the main layer comprises crosslinked polyurethane.

[0044] According to a particular embodiment, the composition of the main layer comprises:

[0045] - a linear polyolefin and / or a crosslinked polyolefin,

[0046] - polyurethane and / or crosslinked polyurethane,

[0047] - at least one additive chosen from: stabilizers (in particular heat stabilizers), antioxidants, flame retardants, anti-UV agents, lubricants, fillers (for example silica), expansion agents, hot-melt adhesives (advantageously polyolefin or polyurethane based), mineral fillers, colorants, pigments and mixtures thereof.

[0048] Generally, the composition of the main layer may include compounds of plant origin, for example starch.

[0049] The linear polyolefin is advantageously chosen from the group comprising polyethylenes, polypropylenes, polybutenes, polypentenes, poly(4-methylpentene), olefin copolymers (for example ethylene-propene copolymers (EP), ethylene-propene-diene copolymers (EPDM), etc.), elastomeric polyolefins and their mixtures.

[0050] The crosslinked polyolefin is advantageously chosen from the group comprising polyethylenes, polypropylenes, polybutenes, olefin copolymers, styrenic resins, elastomers, and their mixtures.

[0051] According to a preferred embodiment, the main layer comprises 5 to 100% by mass of recycled materials, for example 10 to 50% by mass, or 20 to 40% by mass. The recycled materials are advantageously recycled polymers, more advantageously recycled polyolefins and / or recycled polyurethane. These recycled polymers may or may not be crosslinked.

[0052] Recycled materials can come from any type of industry, including the automotive industry (dashboards, door panels, etc.). Indeed, the polymers in the main layer are commonly used due to their lightness and versatility. Thus, the main layer is advantageously derived, in part or entirely, from the recycling of polyolefin foam and varnished polyolefin films, the varnish being made of crosslinked polyurethane.

[0053] Generally, the presence of varnish in the main layer can be visible to the naked eye as it provides a discontinuous visual appearance.

[0054] The present invention therefore makes it possible to recycle, within the same layer, materials whose properties generally require a compatibilizing agent. However, according to a particular embodiment, the main layer is devoid of a compatibilizing agent between the polyolefin and the crosslinked polyurethane.

[0055] Surface layer

[0056] As already indicated, the multilayer comprises a surface layer having a lower face Fies facing the upper face FSCP of the main layer, and an upper face FScs.

[0057] The surface layer has a thickness less than or equal to 0.12 mm, advantageously between 0.070 mm and 0.12 mm.

[0058] The surface layer has a weight of less than 110 g / m 2, advantageously between 70 and 85 g / m 2 , more advantageously between 75 and 80 g / m 2 .

[0059] The surface layer is advantageously a thermoplastic polymer film, preferably chosen from: polyolefin; polyurethane; and mixtures thereof.

[0060] The surface layer is a multilayer of thermoplastic polymer(s), for example a polyolefin multilayer or a multilayer having at least one polyolefin layer and at least one polyurethane layer. The multilayer may comprise at least one layer consisting of a mixture of polyolefin and polyurethane.

[0061] Advantageously, the surface layer is a multilayer comprising 2 to 11 layers of thermoplastic polymer(s), more advantageously 3 to 11 layers, more advantageously 3 to 5 layers, in particular 3 or 5 layers. The different layers constituting the surface layer may have different characteristics, such as for example their composition, their thickness, their weight, the additives present or even their surface treatment.

[0062] Advantageously, the surface layer is a multilayer comprising (advantageously consisting of) the following three layers:

[0063] - polyolefin layer (preferably mainly or entirely polypropylene), having a thickness advantageously between 0.015 and 0.025 mm, and a weight advantageously between 14 and 23 g / m 2 , constituting the upper face FScs of the surface layer, this layer being advantageously colored and / or stabilized,

[0064] - polyolefin layer (preferably composed of polypropylene, polyethylene or at least one copolymer of olefins (for example ethylene and propene)), having a thickness advantageously between 0.035 and 0.055 mm, and a grammage advantageously between 32 and 50 g / m 2 , this layer being advantageously colored and / or stabilized,

[0065] - polyolefin layer (preferably composed of polypropylene, polyethylene or at least one copolymer of olefins (for example ethylene and propene)), having a thickness advantageously between 0.015 and 0.025 mm, and a grammage advantageously between 14 and 23 g / m 2 , constituting the lower face of the surface layer, this layer being advantageously colored and / or stabilized.

[0066] The multilayer constituting the surface layer is advantageously produced by extrusion blow molding according to the general knowledge of those skilled in the art.

[0067] Advantageously, at least one layer constituting the surface layer comprises at least one additive chosen from: stabilizers (in particular thermal stabilizers), antioxidants, flame retardants, anti-UV agents, lubricants, fillers (for example silica), expansion agents, hot-melt adhesives (advantageously polyolefin or polyurethane based), mineral fillers, dyes, pigments and mixtures thereof.

[0068] Protective layer

[0069] As already indicated, the multilayer comprises a protective layer opposite the upper face FScs of the surface layer. The protective layer is based on crosslinked polyurethane and has a polyurethane weight between 1 and 25 g / m 2 .

[0070] Multilayer and its use

[0071] According to a particular embodiment, the multilayer comprises (advantageously consists of) the following layers:

[0072] - protective layer with a weight between 1 and 25 g / m 2 ,

[0073] - surface layer having a grammage of less than 110 g / m 2 , and advantageously including

[0074] 3 to 11 layers, more preferably 3 to 5 layers,

[0075] - main layer with a weight of less than 2100 g / m 2 ,

[0076] - layer of glue,

[0077] - textile underlay.

[0078] According to another particular embodiment, the multilayer comprises (advantageously consists of) the following layers:

[0079] - protective layer with a weight between 1 and 25 g / m 2 ,

[0080] - surface layer having a grammage of less than 110 g / m 2 , and advantageously including

[0081] 3 to 11 layers, more preferably 3 to 5 layers,

[0082] - main layer with a weight of less than 2100 g / m 2 .

[0083] According to another particular embodiment, the multilayer comprises (advantageously consists of) the following layers:

[0084] - protective layer with a weight between 1 and 25 g / m 2 ,

[0085] - surface layer having a grammage of less than 110 g / m 2 , and advantageously including

[0086] 3 to 11 layers, more preferably 3 to 5 layers,

[0087] - main layer with a weight of less than 2100 g / m 2 ,

[0088] - foam underlay.

[0089] According to another particular embodiment, the multilayer comprises (advantageously consists of) the following layers:

[0090] - protective layer with a weight between 1 and 25 g / m 2 ,

[0091] - surface layer having a grammage of less than 110 g / m 2 , and advantageously including

[0092] 3 to 11 layers, more preferably 3 to 5 layers,

[0093] - main layer with a weight of less than 2100 g / m 2 ,

[0094] - a layer of foam, - a layer of glue,

[0095] - textile underlay.

[0096] The multilayer may comprise one or more intermediate layers, for example made of polyolefin. Advantageously, the surface layer is a multilayer comprising 3 to 11 layers, more advantageously 3 to 5 layers.

[0097] The multi-layer can be grained and / or printed.

[0098] The multilayer may also include a layer of varnish (polyurethane) on the lower face FICP of the main layer when the multilayer does not include an undercoat or on the lower face of the undercoat when the multilayer includes an undercoat.

[0099] When applied to the back of the multi-layer (main layer or undercoat), the varnish can have a binding function to facilitate the bonding of the multi-layer.

[0100] When applied to the surface of the multi-layer, the varnish constitutes the protective layer which has a protective function and advantageously an aesthetic function.

[0101] The multilayer according to the invention can in particular be used in one of the following fields: automotive, leather goods, etc.

[0102] Multilayer preparation process

[0103] The present invention also relates to a method of manufacturing the multilayer. This method comprises preparing a laminate comprising a main layer, a surface layer and a protective layer, the main layer having a lower face FICP and an upper face FSCP, the surface layer having a lower face Fies opposite the upper face FSCP of the main layer, and an upper face FScs, the protective layer being deposited on the upper face FScs of the surface layer.

[0104] Optionally, the multilayer can be grained, advantageously in line in a calender.

[0105] During the extrusion assembly process, the graining cylinder can press the material into its final shape. According to a particular embodiment, the main layer is extruded onto the surface layer, the surface layer being, prior to extrusion, a thermoplastic polymer film (advantageously polyolefin or polyurethane) associated with the protective layer.

[0106] According to another particular embodiment, the main layer is extruded between the surface layer and a sub-layer, the surface layer being, prior to extrusion, a thermoplastic polymer film associated with the protective layer, the sub-layer being made of polyolefin foam.

[0107] According to yet another particular embodiment, the surface layer is a multilayer produced by extrusion blow molding, made of thermoplastic polymer (advantageously polyolefin or polyurethane).

[0108] Thus, when the underlayer is made of polyolefin foam, it is advantageously associated with the main layer by calendering.

[0109] When the underlay is made of textile material, it is advantageously associated with the main layer by gluing, for example by means of a layer of glue or glue dots.

[0110] According to another particular embodiment, the main layer is associated with a sub-layer by direct calendering (without glue) or indirect (with glue), the sub-layer being made of textile material or polyolefin foam.

[0111] According to another particular embodiment, the main layer is advantageously prepared by extrusion of thermoplastic granules having a composition comprising:

[0112] * at least 70% by mass of polyolefin, and

[0113] * advantageously crosslinked polyurethane, the granules (optionally ground) having an average size of between 2 and 15 mm.

[0114] The composition of thermoplastic granules can be derived, at least partially, from recycled materials.

[0115] As already indicated, the invention also relates to the use of this multilayer in the automotive or leather goods sector. Examples

[0116] The following multilayer was prepared as follows:

[0117] - Application of a layer of varnish (5g / m 2 crosslinked polyurethane) on the underside of a foam underlay (crosslinked polyolefin, with a thickness of 2.5 mm and a density of 67 kg / m 3 ),

[0118] - Application of a protective layer (2x5g / m 2crosslinked polyurethane) on a surface layer of polyolefin (multilayer of polyethylene / polypropylene and olefin copolymers, with colorant and UV stabilizer) (80 g / m 2 , 85 um),

[0119] - Extrusion of the main layer (220°C, 370 g / m 2 , 500 iim) between the surface layer and the foam underlay,

[0120] - Consolidation of the multilayer by passing through a calender (rubber / steel).

[0121] The surface layer is a multi-layer composed of the following layers, and is manufactured by blow molding in a single step:

[0122] - a first uncolored layer (thickness: 20 um and weight: 19 g / m 2 ), composed of ethylene-propene copolymers to improve adhesion to the main layer and the top layer,

[0123] - a second layer (thickness: 45 um and weight: 42 g / m 2), colored and UV stabilized, composed of polyolefin (polypropylene),

[0124] - a third layer (thickness: 20 um and weight: 19 g / m 2 ), colored and UV stabilized, composed of polypropylene and having undergone a Corona-type surface treatment to facilitate its adhesion with the protective layer.

[0125] The main layer comprises (by mass) 99% polyolefin (including 4.5% crosslinked polyolefin) and 1% crosslinked polyurethane; 20% by mass of the main layer being of recycled origin.

[0126] Two other multilayers were prepared identically, but with a surface layer comprising a second layer of polyethylene or olefin copolymer (ethylene + propene).

Claims

CLAIMS 1. Multilayer comprising at least: a) a main layer having a FICP lower face and an FSCP upper face, the main layer having a thickness of between 0.2 and 2.2 mm and a weight of between 150 and 2100 g / m 2 , the main layer having a composition, over its entire thickness, comprising at least 70% by mass of polyolefin, and b) a surface layer having a thickness less than or equal to 0.12 mm and a grammage less than 110 g / m 2, the surface layer being a multilayer film made of thermoplastic polymer(s), preferably chosen from: polyolefin; polyurethane and their mixtures, the surface layer having a lower face Fies facing the upper face FSCP of the main layer, and an upper face FScs, c) a protective layer facing the upper face FScs of the surface layer, the protective layer being based on crosslinked polyurethane and having a polyurethane weight of between 1 and 25 g / m 2 .

2. Multilayer according to claim 1, characterized in that the composition of the main layer comprises crosslinked polyurethane.

3. Multilayer according to claim 1 or 2, characterized in that the multilayer comprises an underlayer made of textile material or polyolefin foam, the underlayer advantageously facing the lower face FICP of the main layer.

4. Multilayer according to one of claims 1 to 3, characterized in that the multilayer comprises a polyolefin foam sub-layer having a lower FISCM face covered with a layer based on crosslinked polyurethane and an upper FSSCM face advantageously facing the lower FICP face of the main layer.

5. Multilayer according to one of claims 1 to 4, characterized in that the composition of the main layer comprises linear polyolefin and crosslinked polyolefin.

6. Multilayer according to one of claims 1 to 5, characterized in that the composition of the main layer comprises: - a linear polyolefin and / or a crosslinked polyolefin, - polyurethane and / or crosslinked polyurethane, - at least one additive chosen from: stabilizers, antioxidants, flame retardants, anti-UV agents, lubricants, fillers, blowing agents, hot-melt adhesives, mineral fillers, dyes, pigments and mixtures thereof, the linear polyolefin being chosen from the group comprising polyethylenes, polypropylenes, polybutenes, polypentenes, poly(4-methylpentene), olefin copolymers, elastomeric polyolefins and mixtures thereof, the crosslinked polyolefin being chosen from the group comprising polyethylenes, polypropylenes, polybutenes, olefin copolymers, styrenic resins, elastomers and mixtures thereof.

7. Multilayer according to one of claims 1 to 6, characterized in that the main layer comprises 5 to 100% by mass of recycled polyolefins and / or recycled polyurethane.

8. Multilayer according to one of claims 1 to 7, characterized in that the surface layer is a polyolefin film having a thickness of between 0.070 mm and 0.12 mm, the surface layer comprising 3 to 11 layers, advantageously 3 to 5 layers.

9. Multilayer according to one of claims 1 to 8, characterized in that the composition of the main layer comprises compounds of plant origin, advantageously starch.

10. Method for manufacturing the multilayer according to one of claims 1 to 9, comprising the preparation of a laminate comprising a main layer, a surface layer and a protective layer, the main layer having a lower face FICP and an upper face FSCP, the surface layer having a lower face Fies opposite the upper face FSCP of the main layer, and an upper face FScs, the protective layer being deposited on the upper face FScs of the surface layer.

11. Method according to claim 10, characterized in that the main layer is extruded onto the surface layer, the surface layer being, prior to extrusion, a thermoplastic polymer film associated with the protective layer.

12. Method according to claim 10, characterized in that the main layer is extruded between the surface layer and a sub-layer, the surface layer being, prior to extrusion, a thermoplastic polymer film associated with the protective layer, the sub-layer being made of polyolefin foam.

13. Method according to claim 10, characterized in that the main layer is associated with a sub-layer by direct calendering without glue or indirect with glue, the sub-layer being made of textile material or polyolefin foam.

14. Method according to one of claims 10 to 13, characterized in that the main layer is prepared by extrusion of thermoplastic granules having a composition comprising: * at least 70% by mass of polyolefin, and * crosslinked polyurethane, with an average size between 2 and 15 mm.

15. Use of the multilayer according to one of claims 1 to 9, in the automotive or leather goods field.