Motor vehicle interior trim panel

Abstract

The invention relates to a motor vehicle interior trim panel (1), the panel comprising a body (2) having a cellular core (3), two layers, namely a front layer (8) and a back layer (9), for reinforcing the core, the layers being on the basis of entangled reinforcing fibres embedded in polyurethane foam (16), and a coat (10) based on a polyurethane elastomer covering the front layer, the panel further comprising a polyurethane-tight sheet (11) on the basis of cellulose fibres, the sheet being arranged between the front layer and the coat, the sheet being overmoulded on either side by the polyurethane foam and by the polyurethane elastomer so as to be embedded between the two.

Description

[0001] DESCRIPTION

[0002] Interior trim panel of a motor vehicle

[0003] The invention relates to an interior trim panel for a motor vehicle and a method for manufacturing such a panel.

[0004] It is known to produce an interior trim panel for a motor vehicle, said panel comprising a body, said body comprising:

[0005] • a cellular core, said core having a front face and a back face, said faces being connected to each other by a peripheral slice, said core having open cells opening on both sides towards said faces,

[0006] • two layers of reinforcement for the front and back of said core, said layers being based on entangled reinforcing fibers, said layers being embedded in polyurethane foam, said layers extending respectively over said front and back faces, said foam overmolding said core so as to associate said layers with said core, said panel further comprising a coating layer based on elastomeric polyurethane covering said front layer.

[0007] According to a known embodiment, the coating layer is overmolded onto the front face so as to adhere to it.

[0008] Using polyurethane elastomer for the coating layer provides a waterproof layer that is particularly robust against abrasion and easily washable.

[0009] This arrangement also allows for the creation of a laminated panel with excellent rigidity, achieved through a "beam effect" created by the reinforcing layers joined together via the core, which acts as a spacing mechanism. Such a panel could be used, for example, as a shelf covering a luggage compartment or as a false floor in a passenger compartment or luggage compartment.

[0010] However, because the core cells open on both sides towards the front and back faces, there is a risk during the production of such a panel that the polyurethane elastomer will pass through the front layer and penetrate the core, possibly even reaching the back layer which may itself be penetrated by the polyurethane elastomer.

[0011] This results in overconsumption of polyurethane elastomer and also a risk of aesthetic defects on the reverse side of the panel.

[0012] The invention aims to provide an arrangement that overcomes these drawbacks.

[0013] To this end, and according to a first aspect, the invention proposes an interior trim panel for a motor vehicle, said panel comprising a body, said body comprising:

[0014] • a cellular core, said core having a front face and a back face, said faces being connected to each other by a peripheral slice, said core having open cells opening on both sides towards said faces,

[0015] • two layers of reinforcement for the front and back of said core, said layers being made of entangled reinforcing fibers, said layers being embedded in polyurethane foam, said layers extending respectively over said front and back faces, said foam overmolding said core so as to bond said layers to said core, said panel further comprising a layer of elastomeric polyurethane coating covering said front layer, said panel further having the following characteristics: • it further comprises a polyurethane sealing sheet made of cellulose fibers,

[0016] • said sheet is placed between said top sheet and said coating layer,

[0017] • said sheet is overmolded on both sides by the polyurethane foam and by the polyurethane elastomer so as to be embedded between the two.

[0018] Such an arrangement using such a sealing sheet makes it possible to prevent the passage of polyurethane elastomer through the surface layer.

[0019] This results in the use of a minimized amount of polyurethane elastomer and the absence of aesthetic defects on the reverse side of the panel.

[0020] Furthermore, the use of a sheet based on cellulose fibers has proven to be particularly suitable, especially compared to a sheet based on thermoplastic film.

[0021] Among the advantages observed by the applicant, the use of such a sheet made from cellulose fibers allows:

[0022] • the absence of folds likely to disrupt the flow of the polyurethane elastomer precursor mixture, as such folds risk creating surface defects on the coating layer,

[0023] • to smooth out defects that could result from markings made by the core - for example in the form of a honeycomb pattern when said core has such a structure - due to the strength of the sheet used (provided that it has a sufficient surface mass as mentioned later),

[0024] • good homogeneity of the coating layer which is ensured due to the braking of the precursor mixture of polyurethane elastomer when it flows on such a sheet, excellent adhesion of the polyurethane elastomer and the polyurethane foam on the sheet, which contributes to the robustness of the panel.

[0025] According to a second aspect, the invention proposes a method for making such a panel.

[0026] Other features and advantages of the invention will appear in the following description, made with reference to the attached figure [Fig.1], which is a schematic partial cross-sectional view of a panel according to one embodiment.

[0027] With reference to the figure, a panel 1 of interior trim for a motor vehicle is described, said panel comprising a body 2, said body comprising:

[0028] • a cellular core 3, said core having a front face 4 and a back face 5, said faces being connected to each other by a peripheral slice 6, said core having open cells 7 opening on both sides towards said faces,

[0029] • two layers of reinforcement for the front 8 and back 9 of said core, said layers being based on entangled reinforcing fibers, said layers being embedded in polyurethane foam 16, said layers extending respectively over said front and back faces, said foam overmolding said core so as to bond said layers to said core, said panel further comprising a coating layer 10 based on elastomeric polyurethane covering said front layer, said panel further having the following characteristics:

[0030] • it further comprises a polyurethane sealing sheet 11 based on cellulose fibres - in particular in the form of paper or cardboard -,

[0031] • said sheet is arranged between said top sheet and said coating layer, • said sheet is overmolded on both sides by polyurethane foam and by polyurethane elastomer so as to be embedded between the two.

[0032] According to one design, core 3 is formed by a honeycomb structure.

[0033] Depending on the design, the honeycomb is made of cardboard, thermoplastic material or aluminum.

[0034] According to the embodiment shown, the coating layer 10 further extends over the edge 6 of the core 3 and over a peripheral band 14 of the underside layer 9, so as to ensure extensive protection of the panel 1 - in particular in the event of water being spilled on it.

[0035] According to one embodiment, the sealing sheet 11 has a surface mass between 100 and 400 g / m² 2 , and in particular between 250 and 300 g / m 2, which gives it a good shape allowing in particular the absence of creases and markings by the core 3.

[0036] Depending on the specific design, the reinforcing fibers are mineral fibers - for example glass - or plant fibers - for example flax, cotton, or hemp.

[0037] According to one implementation, the thickness of the coating layer 10 is between 0.5 and 2 mm, and in particular around 1.5 mm.

[0038] According to one embodiment, a backing layer 15 - for example based on non-woven material - is glued or overmolded by the foam onto the backing layer 9.

[0039] In one embodiment, the reinforcing fibers are bonded together by a bonding agent, for example in the form of a resin. In one embodiment, the reinforcing layers 8,9 have a surface mass between 200 and 500 g / m². 2 , and in particular in the order of 450 g / m² 2 .

[0040] We now describe a manufacturing process for such a panel 1, said process comprising the following steps:

[0041] • provide a cellular core 3, said core having a front face 4 and a back face 5, said faces being connected to each other by a peripheral slice 6, said core having open cells 7 opening on both sides towards said faces,

[0042] • Arrange two layers of reinforcement, one on the right side (8) and one on the wrong side (9), on each of the said faces, said layers being made of interwoven reinforcing fibers,

[0043] • pour a precursor mixture of polyurethane foam 16 onto each of the said layers,

[0044] • place the assembly in a first mold defining a first molding cavity, the wall of said cavity being lined opposite said facing layer with a sheet 11 made of cellulose fibers,

[0045] • wait for the foam to expand so that said sheets are impregnated with foam, said foam overmolding said core, so as to join said sheets to said faces, said foam further overmolding said sheet, so as to join said sheet to said top sheet,

[0046] • remove the entire mold and transfer it into a second mold defining a second molding cavity, said cavity defining a space of substantially homogeneous thickness between its wall and said sheet,

[0047] • fill said space by injection with a precursor mixture of polyurethane elastomer so as to create the coating layer 10,

[0048] • remove the resulting panel from the mold.

[0049] According to one embodiment, it is planned that the space will also extend over the edge 6 of the core 3 and over a peripheral band 14 of the reverse layer 9, so as to obtain a panel 1 whose coating layer 10 also extends over said edge and said band.

[0050] It is also possible to plan to associate at least one layer of reverse coating on the reverse layer, in particular by gluing or by overmolding with the foam in the first mold.

Claims

DEMANDS 1. Interior trim panel (1) of a motor vehicle, said panel comprising a body (2), said body comprising: • a cellular core (3), said core having a front face (4) and a back face (5), said faces being connected to each other by a peripheral slice (6), said core having open cells (7) opening on both sides towards said faces, • two layers of reinforcement for the front (8) and back (9) of said core, said layers being based on entangled reinforcing fibers, said layers being embedded in polyurethane foam (16), said layers extending respectively over said front and back faces, said foam overmolding said core so as to bond said layers to said core, said panel further comprising a coating layer (10) based on elastomeric polyurethane covering said front layer, said panel being characterized in that: • it further comprises a polyurethane sealing sheet (11) based on cellulose fibres, • said sheet is placed between said top sheet and said coating layer, • said sheet is overmolded on both sides by the polyurethane foam and by the polyurethane elastomer so as to be embedded between the two.

2. Panel (1) according to claim 1, characterized in that the core (3) is formed by a honeycomb structure.

3. Panel (1) according to claim 2, characterized in that the honeycomb is based on cardboard, thermoplastic material or aluminum.

4. Panel (1) according to any one of the preceding claims, characterized in that the coating layer (10) further extends over the edge (6) of the core (3) and over a peripheral band (14) of the backing layer (9), so as to ensure extensive protection of said panel.

5. Panel (1) according to any one of the preceding claims, characterized in that the sealing sheet (11) has a surface mass of between 100 and 400 g / m² 2 .

6. Panel (1) according to any one of the preceding claims, characterized in that the reinforcing fibers are mineral fibers or vegetable fibers.

7. Panel (1) according to any one of the preceding claims, characterized in that the thickness of the coating layer (10) is between 0.5 and 2 mm.

8. A method for manufacturing a panel (1) according to any one of the preceding claims, characterized in that it comprises the following steps: • provide a cellular core (3), said core having a front face (4) and a back face (5), said faces being connected to each other by a peripheral slice (6), said core having open cells (7) opening on both sides towards said faces, • Arrange two layers of reinforcement, one on the front (8) and one on the back (9), on each of said faces, said layers being made of interwoven reinforcing fibers, • pour a precursor mixture of polyurethane foam (16) onto each of the said layers, • place the assembly in a first mold defining a first molding cavity, the wall of said cavity being lined opposite said facing layer with a sheet (11) made of cellulose fibers, • wait for the foam to expand so that said sheets are impregnated with foam, said foam overmolding said core, so as to join said sheets to said faces, said foam further overmolding said sheet, so as to join said sheet to said top sheet, • remove the entire mold and transfer it into a second mold defining a second molding cavity, said cavity defining between its wall and said sheet a space of substantially homogeneous thickness, • fill said space by injection with a precursor mixture of polyurethane elastomer so as to produce the coating layer (10), • remove the resulting panel from the mold.

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