Filling element comprising a functional layer of conductive paint

Abstract

Upholstery component comprising a functional layer of conductive paint. The vehicle upholstery component (1) comprises a backing layer (2), including an inner face (8) and an outer face (10), and at least one functional layer (6) of conductive material extending opposite at least a portion of the inner face (8) and / or the outer face (10) of the backing layer (2), at least a portion of said functional layer (6) defining at least one pattern (16) comprising at least one conductive area (20) and at least one non-conductive area (22) formed by a through-hole in the functional layer (6), the pattern (16) forming at least part of an electrical circuit arranged to perform an interaction function with a vehicle passenger on an external surface (14) of the upholstery component. The conductive material of the functional layer (6) is conductive paint. Figure for abbreviation: 1

Description

Title of the invention: Filling element comprising a functional layer of conductive paint

[0001] The present invention relates to a vehicle trim element of the type comprising at least one support layer, comprising an inner face and an outer face, and at least one functional layer of conductive material extending opposite at least a part of the inner face and / or the outer face of the support layer, at least a part of said functional layer defining at least one pattern comprising at least one conductive zone and at least one non-conductive zone formed by a through opening in the functional layer, said conductive zone being powered by a current source electrically connected to the conductive zone, the pattern forming at least one part of an electrical circuit arranged to perform an interaction function with a vehicle passenger on an external surface of the trim element.

[0002] The invention also relates to a method for making such a trim element.

[0003] The invention applies for example to a trim element forming a door panel, a center console or dashboard covering of a vehicle or other.

[0004] In such a trim element, it is desirable to integrate certain functionalities for the vehicle occupants on the external surface of the trim element. Thus, the trim element may, for example, include touch surfaces to allow control of certain vehicle functions, detection surfaces to detect contact with the external surface, or other features.

[0005] The functional elements enabling these functions, such as printed circuit boards, are integrated into the trim element, for example under a decorative layer so as not to be visible from inside the vehicle. To achieve this, the circuits are, for example, glued to the substrate layer before the decorative layer is applied. However, such a process is tedious and can be complicated, particularly when several functional surfaces are involved, as various functional elements must then be attached to different locations on the substrate layer.Furthermore, if the functional element(s) are incorrectly positioned on the support layer and / or in relation to the decorative layer, the quality of the filling element is degraded because the functional surfaces do not extend exactly in relation to the indications provided on the external surface of the filling element to indicate their presence and / or their activation zone.

[0006] One of the aims of the invention is to overcome these drawbacks by proposing a trim element comprising one or more functional surfaces which can be made in a simple and reliable manner.

[0007] For this purpose, the invention relates to a filling element of the aforementioned type, in which the conductive material of the functional layer is a conductive paint.

[0008] By creating the pattern in a functional layer made of conductive paint, a functional electrical circuit can be defined at a precise location on the substrate layer in a simple, reliable, and particularly economical way. Indeed, the use of conductive paint makes it possible to obtain a layer with good conductivity for the electrical circuit while being less expensive than a layer made, for example, from carbon fibers.

[0009] In addition, when several functional electrical circuits are planned, they can all be made in the functional layer or layers, which limits the operations of making the filling element and simplifies the relative positioning of the different functional electrical circuits on the support layer.

[0010] According to a particular feature of the invention, the conductive paint comprises graphene and carbon black.

[0011] The use of a conductive paint containing graphene and carbon black makes it possible to obtain particularly satisfactory conductivity. While the synthesis of graphene can be expensive, carbon black is very common and inexpensive. The use of a mixture of these two materials makes it possible to obtain a satisfactory conductive paint at a reduced cost.

[0012] The filling element according to the invention may further comprise one or more of the following features, taken individually or in any technically feasible combination:

[0013] - the filling element further comprises a protective layer extending over at least part of the inner face and / or outer face of the support layer, said protective layer being interposed between said support layer and said functional layer;

[0014] - an insulating layer extends over said functional layer on the opposite side of the support layer, said insulation layer covering said functional layer at least opposite the pattern and filling the through opening in the functional layer;

[0015] - the insulation layer is a dielectric paint layer;

[0016] - the functional layer extends opposite the outer face of the support layer and the insulation layer forms the external surface of the filling element;

[0017] - the support layer is made of a composite material comprising fibers natural in a polypropylene matrix;

[0018] - the electrical circuit formed by the motif in the functional layer is at least a part of a capacitive circuit so as to form a touch surface or a proximity sensor on at least a part of the external surface of the lining element, of a resistive circuit so as to form a pressure sensor or a force sensor on at least a part of the external surface of the lining element or of a resistive circuit forming a heating element of a part of the external surface of the lining element;

[0019] - the conductive paint layer is cut by laser etching, chemical etching, mechanical milling or drilling in conductive paint.

[0020] According to another aspect, the invention also relates to a method for making a trim element as described above, comprising the following steps:

[0021] - provide a support layer;

[0022] - apply a layer of conductive paint opposite at least part of the inner and / or outer face of the support layer,

[0023] - cut the conductive paint layer through its entire thickness so as to to form a pattern comprising at least one conductive area formed by the conductive paint and at least one non-conductive area formed by a through-hole in the conductive paint layer so as to form a functional layer 6 defining at least part of an electrical circuit,

[0024] - electrically connect the conductive area of ​​the functional layer pattern to a power source.

[0025] The method of embodiment according to the invention may further comprise the following features, taken individually or in any technically feasible combination:

[0026] - the manufacturing process includes a step of applying a layer of protection on at least part of the inner and / or outer face of the support layer before the step of applying the conductive paint layer, said protective layer being interposed between said support layer and said functional layer;

[0027] - the manufacturing process includes a step of applying an insulation layer on said functional layer opposite the support layer after the cutting step of the conductive paint layer, said insulation layer covering said functional layer at least opposite the pattern and filling the through opening in the functional layer.

[0028] Other aspects and advantages of the invention will become apparent from the following description, given by way of example and with reference to the accompanying drawings, in which:

[0029] [Fig-1] - [Fig.1] is a schematic cross-sectional representation of part of a functional element according to one embodiment of the invention,

[0030] [Fig.2] - [Fig.2] is a schematic cross-sectional representation of different stages in the production of a trim element according to [Fig. 1].

[0031] With reference to [Fig.1], a trim element 1 of a vehicle is described comprising at least a support layer 2, a decorative layer 4 and a functional layer 6. Such a trim element is, for example, intended to form a door panel, a dashboard or center console covering or other.

[0032] The support layer 2 is arranged to impart its shape and mechanical characteristics to the filling element 1, in particular its rigidity. The support layer 2 is thus, for example, made of a material that is substantially rigid for a door panel, such as a plastic or composite material. In one embodiment, the support layer 2 is made of a composite material comprising natural fibers in a polypropylene matrix, also known as NFPP for "Natural Fiber Polypropylene." The natural fibers are, for example, selected from flax, hemp, kenaf, and / or wood. The support layer 2 is, for example, formed by thermocompression in a pressing tool having the desired shape of the support layer 2, which corresponds to the shape of the filling element 1. Thus, the support layer 2 has, for example, a three-dimensional shape with raised areas.For example, support layer 2 may include an area that protrudes from the rest of support layer 2 to form an armrest.

[0033] Alternatively, the support layer 2 is produced by injecting plastic material, such as polypropylene (PP), polycarbonate acrylonitrile butadiene styrene (PC ABS), or other, into a mold cavity having the desired shape. According to another embodiment, the support layer 2 is obtained by additive manufacturing to the desired shape. The support layer 2 comprises an inner face 8, intended to extend towards the side of the part of the vehicle on which the trim element is to be installed, such as the vehicle door in the case of a door panel, and an outer face 10, opposite the inner face 8, and intended to face the vehicle's passenger compartment.

[0034] The decorative layer 4 extends from the outer face 10 of the support layer 2 opposite at least a portion thereof. The decorative layer 4 is arranged to give its appearance and feel to the upholstery element 1. The decorative layer 4 is thus, for example, made of a flexible or rigid material, having a particular appearance and / or feel that is desired to be given to the upholstery element 1. Thus, the decorative layer 4 is, for example, made of textile material, plastic material, wood material, leather or imitation leather, or other. However, when, as shown in [Fig. 1], the decorative layer 4 extends over the support layer As will be described later, the decorative layer 4 is preferably formed by an insulating layer 12, for example made of dielectric paint. Such an insulating layer 12 will be described in more detail later.

[0035] The decorative layer 4 is shaped to the outer face 10 of the support layer 2, that is to say, it substantially conforms to the shape of the outer face 10 in the area of ​​the support layer 2 that it covers. In one embodiment, the decorative layer 4 covers the entire support layer 2.

[0036] The decorative layer 4 comprises an outer face 14 extending outwards from the trim element 1 and forming the external surface of the trim element 1, i.e., forming the visible part of the trim element 1 from inside the vehicle's passenger compartment. The outer face 14 may include decorative patterns or indications for a user to indicate the presence of a functional area, for example, as will be described later. Alternatively or in addition, the decorative layer 4 may be translucent, at least in certain areas, to allow light to pass from the outer face 14 to the surface, thus enabling these areas to be backlit to inform a user of the presence of a functional area, for example.

[0037] According to one embodiment, the decorative layer 4 is fixed directly onto the support layer 2. Alternatively, a functional layer 6 is interposed between the support layer 2 and the decorative layer 4, the latter then being formed by an insulation layer 12, as shown in [Fig.1].

[0038] According to one embodiment, the trim element 1 is devoid of a decorative layer 4 and the external surface 14 of the trim element is formed by the external face of the support layer 2 and / or by the functional layer 6 extending over the support layer 2.

[0039] The functional layer 6 is a layer made of a conductive material and comprising at least one motif 16 enabling the functional layer to impart a particular functionality to the trim element 1, as will be described later. The conductive material is a conductive paint containing graphene and carbon black. In other words, the conductive material is a paint based on graphene particles and carbon black whose composition is arranged so that the functional layer 6 has a conductivity enabling the motif 16 to perform the function for which it is intended, as will be described later. More specifically, the amount of graphene is adjusted to give the conductive paint the desired conductivity. Thus, the conductive paint contains, for example, between 0.05 and 50% graphene and between 0.05 and 50% carbon black.More specifically, the conductive paint forming the conductive material is, for example, a conductive paint based on carbon black. commercially available conductive paints incorporate graphene particles to improve their conductivity. For example, the composition of the conductive paint is designed so that the functional layer 6 has a resistivity of less than 30 kOhms / Sqrt. It should be noted that such a conductive material is particularly economical, especially compared to a layer of carbon material containing carbon fibers. Furthermore, such a conductive paint differs from ink in that it is more liquid and less viscous, and in that it is applied by spraying rather than printing, which simplifies its use, as will be described later. In addition, a conductive paint can be applied directly to a three-dimensional substrate, i.e., a pre-formed substrate whose outer face 10 and / or inner face 8 are not flat.The functional layer 6, for example, has a thickness between 5 and 50 µm.

[0040] The functional layer 6 extends over at least a portion of the inner face 8 or at least a portion of the outer face 10 of the support layer 2, depending on the function to be performed, as will be described later. In one embodiment, the functional layer 6 extends over the entire surface of the inner face 8 or the outer face 10 of the support layer.

[0041] In one embodiment, the functional layer 6 is applied directly onto the support layer 2, i.e., there is no intermediate layer between the support layer 2 and the functional layer 6. However, in a particularly advantageous embodiment where the support layer 2 is made of NFPP, a protective layer 18 is interposed between the support layer 2 and the functional layer 6. In other words, the protective layer 18 is applied to the inner face 8 or the outer face 10 of the support layer 2, and the functional layer 6 is applied to the protective layer 18 on the opposite side of the support layer 2, as shown in [Fig. 1]. The protective layer 18 serves, in particular, to protect the functional layer 6 against moisture and mold that may originate from the support layer 2, especially when the latter contains natural fibers, as previously mentioned.Furthermore, the protective layer 18 seals the pores of the support layer 2 to prevent the functional layer from soaking into the support layer 2 during its application and to create a more even surface on which the functional layer 6 is applied. The protective layer 18 is, for example, a polymeric paint or coating (e.g., epoxy, acrylic, polyester, etc.). The protective layer has a thickness ranging, for example, from 1 to 2000 µm.

[0042] The functional layer 6 and, where applicable, the protective layer 18 are shaped to the part of the face of the support layer 2 that they cover, i.e. that the functional layer 6 and the protective layer 18 conform to the shape of this part of the face of support layer 2.

[0043] The motif 16 comprises at least one conductive area 20 formed by the carbon material of the functional layer 6 and at least one non-conductive area 22 formed by a through-hole in the functional layer 6. The shapes of the conductive area 20 and the non-conductive area 22 are arranged to form at least part of a functional electrical circuit that performs a particular function when the conductive area 20 is energized. In other words, the motif 16 is such that the functional layer 6 defines at least one electrical circuit that performs the desired function when the circuit is energized. Depending on the desired function, several distinct conductive areas 20 and non-conductive areas 22 may be provided. Generally, the functional layer 6 includes at least one through-hole delimiting the motif 16 in order to isolate the electrical circuit formed by the motif 16 from the rest of the functional layer 6.

[0044] The functions performed by the electrical circuit(s) are interaction functions with a vehicle passenger on the external surface 14 of the upholstery element. In other words, the functions performed are part of the vehicle's human-machine interface, as vehicle passengers can interact with the external surface 14 of the upholstery element to activate, control, and / or influence the function performed by the electrical circuit formed by the motif 16. Alternatively or in addition, the electrical circuit formed by the motif 16 is arranged to heat a portion of the external surface 14 of the upholstery element.

[0045] Thus, the motif 16 can be arranged to form an electrical circuit on the outer face 10 of the support layer 2, between it and the decoration layer 4, for example a resistive circuit, for example to form a heating element, a force or pressure sensor. The motif 16 can also be arranged to form a capacitive circuit to form a proximity sensor or a touch surface, such as a so-called "multi-touch" or "touch slider" surface.

[0046] The pattern 16 on one face of the support layer 2 can be arranged to form part of an electrical circuit, another part of which is formed by a pattern on another functional layer 6, also made of conductive paint, for example, located opposite the other face of the support layer 2. Thus, a capacitive circuit can, for example, be formed by a pattern 16 formed in a functional layer 6 extending opposite the outer face 10 of the support layer and by another pattern, extending opposite the pattern 16, formed in a functional layer 6 extending opposite the inner face 8 of the support layer 2. Alternatively or in addition, the electrical circuit can include an active part, formed, for example, on the side of the outer face 10 of the support layer 2 and arranged to perform the function intended by the circuit, and a power supply part, formed, for example, on the side of the face internal 8 of the support layer 2 and arranged to be connected to a current source to supply the circuit with electricity. In this case, a connection must be ensured between the two parts of the circuit, for example through the support layer 2 and, where applicable, through the protection layer(s) 18.

[0047] It is understood that a single functional layer 6 or two functional layers on each face may comprise several motifs 16 in different zones in order to perform different functions on the corresponding zones of the external surface 14 of the packing element 1. Thus, for example, a motif 16 forming a resistive heating circuit is provided on the external face 10 of the support layer 2 in a first zone, and another motif 16 forming a pressure sensor is provided on the internal face 8 of the support layer 2 in a second zone, the pressure sensor allowing, for example, the control of the heating surface. Alternatively, several distinct motifs forming distinct electrical circuits are provided, for example. In some cases, the functions have been described with reference to a particular positioning of the functional layer on one of the faces of the support layer 2.It is understood, however, that the same functions could be achieved by placing the functional layer 6 on the other side of the support layer 2.

[0048] The motif or motifs 16 are supplied with electricity by at least one current source (not shown) electrically connected to the conductive area(s) 20 of the motif 16, for example, connected to terminals formed by a portion of motifs 16, for example, in a power supply section as described above. The current source is, for example, the electrical system of the vehicle in which the trim element is installed. When a functional layer 6 is provided on each side of the support layer 2 and each comprises at least one separate electrical circuit, each functional layer 6 is supplied with current by one or more current sources.

[0049] The functional layer 6 can form a grounding zone outside the pattern(s) 16 formed in this functional layer 6. Such a grounding zone protects the electrical circuit(s) from electrostatic discharges that could damage them. To achieve this, the grounding zone is electrically connected to the electrical circuit(s). Alternatively or in addition, the functional layer 6 allows one or more electrical circuits of the packing element 1 to be grounded, separate from the circuit(s) formed in the functional layer 6. Thus, the circuit(s) provided on a printed circuit board can be protected from electrostatic discharges by connecting the grounding output of the printed circuit board to the grounding zone of the functional layer 6.

[0050] As described previously, the decoration layer 4 can be formed by a layer An insulation layer 12 is arranged to isolate the electrical circuit(s) from the exterior of the trim element and thus protect users touching the external surface 14 of the trim element 1. Such an insulation layer 12 is, for example, formed by a dielectric paint extending over the functional layer 6 opposite the support layer 2, at least with respect to the pattern(s) 16 formed in the latter. In one embodiment, the insulation layer 12 extends over the entire functional layer 6. Furthermore, the insulation layer 12 may also extend into the opening(s) forming the non-conductive zone(s) 22 of the pattern(s) 16. The insulation layer has, for example, a thickness of approximately between 5 and 50 mm. The insulation layer 12 also serves to protect the support layer 2 and / or the functional layer and, in particular, to prevent damage to the pattern(s) 16.

[0051] The packing element described above allows one or more functions to be integrated on the surface of the packing element in a simple, reliable and economical way by integrating the electrical circuit(s) enabling these functions to be carried out in one or more functional layers 6, made of a conductive paint based on graphene and carbon black.

[0052] A method for making a trim element according to an embodiment described previously will now be described with reference to [Fig.2].

[0053] First, a support layer 2 is provided, onto which a protective layer 18 is deposited. The protective layer 18 is deposited on all or part of the inner face 8 and / or outer face 10 of the support layer 2, at least in the area(s) where one or more functional layers 6 are provided. The protective layer 18 is deposited, for example, by spraying onto the support layer 2. As described previously, this step is optional, and the functional layer 6 can be deposited directly onto the support layer 2.

[0054] A layer of conductive paint 24 is then deposited on all or part of the protective layer 18, or, where applicable, on all or part of the inner and / or outer face of the support layer 2. The conductive paint layer 24 is deposited by spraying, unlike ink deposited by printing. Such a spraying step is particularly simple and economical to perform and allows the functional layer to be applied regardless of the shape of the pattern 16 to be created, unlike ink, which is deposited only where ink is intended. This implies programming the printing process appropriately to avoid depositing material where a non-conductive area is intended. When several functional layers 6 are planned, several layers of conductive paint 24 are sprayed. A functional layer 6 can also be formed by several successive layers of conductive paint.

[0055] The pattern(s) 18 are then made in the conductive paint layer 24. To achieve this, at least one through-hole is formed in the conductive paint layer to create the non-conductive zone 22. "Through-hole" means that the conductive paint layer 24 is cut through its entire thickness. The shape of the through-hole(s) in the conductive paint layer 24 defines the shape of the pattern 16 and its conductive zone(s) 20. In one embodiment, the conductive paint layer is etched using laser beams, allowing the shape of the pattern 16 to be defined very precisely. Alternatively, the conductive paint layer is cut by chemical etching, milling, or mechanical drilling. As described previously, several patterns 16 can be incorporated into the functional layer 6.

[0056] Where appropriate, an insulation layer 12 is then applied to the functional layer 6 at least opposite one or more patterns 16. The insulation layer 12 is applied by spraying and is arranged to penetrate into the through opening(s) formed in the functional layer 6.

[0057] Alternatively, a decorative layer 4 of another type is deposited on the support layer 2 and / or on the functional layer 6.

[0058] The conductive area(s) 20 are then connected to one or more current sources, for example when mounting the trim element 1 on the vehicle.

[0059] A three-dimensional shaping step of the support layer 2 can be provided to give the filler element the desired shape. This step can be carried out before or after the application of the other layers on the support layer 2.

[0060] The process is therefore particularly simple and inexpensive to implement. In addition, the positioning of the motif(s) 18 can be ensured precisely.

Claims

Demands

1. Vehicle trim element (1) comprising at least one backing layer (2), comprising an inner face (8) and an outer face (10), and at least one functional layer (6) of conductive material extending opposite at least a portion of the inner face (8) and / or the outer face (10) of the backing layer (2), at least a portion of said functional layer (6) defining at least one pattern (16) comprising at least one conductive area (20) and at least one non-conductive area (22) formed by a through-opening in the functional layer (6), said conductive area (20) being powered by a current source electrically connected to the conductive area (20), the pattern (16) forming at least a portion of an electrical circuit arranged to perform an interaction function with a vehicle passenger on an external surface (14) of the trim element,characterized in that the conductive material of the functional layer (6) is a conductive paint.

2. A trim element according to claim 1, wherein the conductive paint comprises graphene and carbon black.

3. Filling element according to claim 1 or 2, further comprising a protective layer (18) extending over at least a portion of the inner face (8) and / or the outer face (10) of the support layer (2), said protective layer (18) being interposed between said support layer (2) and said functional layer (6).

4. Filling element according to any one of claims 1 to 3, wherein an insulation layer (12) extends over said functional layer (6) opposite the support layer (2), said insulation layer (12) covering said functional layer (6) at least opposite the pattern (16) and filling the through opening in the functional layer (6).

5. Filling element according to claim 4, wherein the insulation layer (12) is a dielectric paint layer.

6. Filling element according to claim 4 or 5, wherein the functional layer (6) extends opposite the outer face (10) of the support layer (2) and the insulation layer (12) forms the outer surface (14) of the filling element.

7. A filling element according to any one of claims 1 to 6, wherein the support layer (2) is made of a material composite comprising natural fibers in a polypropylene matrix.

8. A packing element according to any one of claims 1 to 7, wherein the electrical circuit formed by the motif (16) in the functional layer (6) is at least part of a capacitive circuit so as to form a touch surface or a proximity sensor on at least part of the external surface (14) of the packing element, of a resistive circuit so as to form a pressure sensor or a force sensor on at least part of the external surface (14) of the packing element, or of a resistive circuit forming a heating element of a part of the external surface (14) of the packing element.

9. A method for making a trim element according to any one of claims 1 to 8, comprising the following steps: - providing a support layer (2); - applying a conductive paint layer (24) opposite at least a part of the inner face (8) and / or the outer face (10) of the support layer (2); - cutting the conductive paint layer (24) through its entire thickness so as to form a pattern (16) comprising at least one conductive area (20) formed by the conductive paint and at least one non-conductive area (22) formed by a through opening in the conductive paint layer (24) so ​​as to form a functional layer 6 defining at least part of an electrical circuit; - electrically connecting the conductive area (20) of the pattern (16) of the functional layer (6) to a current source.

10. A method of embodiment according to claim 9, comprising a step of applying a protective layer (18) to at least a part of the inner face (8) and / or the outer face (10) of the support layer (2) before the step of applying the conductive paint layer (24), said protective layer (18) being interposed between said support layer (2) and said functional layer (6).

11. A method of embodiment according to any one of claims 9 or 10, comprising a step of applying an insulation layer (12) on said functional layer (6) opposite the support layer (2) after the step of cutting the conductive paint layer (24), said insulation layer (12) covering said functional layer (6) at least opposite the pattern (16) and filling the through opening in the functional layer (6).