FR3116469A1 - Process for producing a trim element comprising a decorative layer of carbon material - Google Patents

Abstract

Method for producing a trim element comprising a decorative layer of carbon material The method for producing a filling element (1) comprises the following steps: - produce at least one pattern (16) in a layer of carbon material, said pattern (16) being produced by creating at least one open zone (20) over the entire thickness of the layer of carbon material so as to form a layer decor (4), - place the decoration layer (4) and a support (2) in a pressing tool (26), - press the decorative layer (4) against the support (2) so that at least part of the support (2) penetrates the open zone (20) of the pattern (16), - remove the packing element from the pressing tool, said packing element having a substantially continuous external surface (14) at the level of the pattern (16). Figure for abstract: 1

Description

Process for producing a trim element comprising a decorative layer of carbon material

The present invention relates to a method for producing a vehicle trim element of the type comprising at least one support and a decorative layer of carbon material extending over at least part of the support and forming at least part of the surface exterior of the trim element, the decorative layer comprising at least one pattern comprising at least one visible zone of carbon material and at least one open zone formed by a through opening in the decorative layer.

The invention also relates to a packing element, for example produced according to such a production method.

The invention applies for example to the production of a trim element forming a door panel, a central console covering or a vehicle dashboard or other.

In order to lighten such a packing element and reduce its environmental impact, it is known to produce the support layer of the packing element in a composite material comprising for example natural fibers embedded in a matrix of plastic material.

While such a composite material confers satisfactory mechanical properties on the packing element, its rigidity and its self-supporting character can be further improved by adding a reinforcing layer to at least part of a surface of the backing layer. Such a reinforcing layer is for example made of a carbon material.

In addition, in order to improve the appearance of the trim element, it is known to apply a decorative layer to the support layer, the decorative layer forming the outer surface of the trim element.

However, the multiplication of the number of layers in the packing element complicates its structure, increases its size, makes it heavier and makes it more complex to produce.

One of the aims of the invention is to overcome these drawbacks by proposing a process for producing a packing element which is simple to implement and which makes it possible to obtain a packing element having a satisfactory appearance.

To this end, the invention relates to a method for producing a packing element of the aforementioned type, comprising the following steps:

- produce at least one pattern in a layer of carbon material, said pattern being produced by creating at least one open zone over the entire thickness of the layer of carbon material so as to form a decorative layer,

- place the decor layer and a support in a pressing tool,

- press the decor layer against the support so that at least part of the support enters the open area of the pattern,

- removing the packing element from the pressing tool, said packing element having a substantially continuous outer surface at the level of the pattern.

The method according to the invention thus makes it possible to produce a trim element having a satisfactory appearance and in particular a substantially continuous outer surface with a pattern of robust carbon material, the decorative layer making it possible to reinforce the support. The process is simple to implement.

According to other characteristics of the process according to the invention, taken in isolation or according to any technically possible combination:

- the support comprises at least one support layer, said support layer penetrating into the open area of the pattern during the pressing step,

- the support comprises at least one support layer and one appearance layer extending between the support layer and the decor layer, at least the appearance layer penetrating into the open area of the pattern during the pressing stage,

- the support layer is made of a composite material comprising natural fibers in a polypropylene matrix,

- a layer of adhesive material is applied to the decorative layer before being placed in the pressing tool, the decorative layer being fixed to the support during the pressing step via the layer of material adhesive,

- the layer of carbon material is dug by laser attack, chemical attack, milling or mechanical drilling in the carbon material to produce the pattern in said layer of carbon material,

- the pattern in the decorative layer is further arranged to form a functional electrical circuit, the pattern comprising at least one conductive zone formed by the visible zone and at least one non-conductive zone formed by the open zone, the method comprising a step electrical connection of at least one current source to the conductive zone after the output of the packing element from the pressing tool,

- the pressing tool is a three-dimensional shaping tool, the packing element acquiring a three-dimensional shape during the pressing step,

- the decorative layer and/or the support undergo a calibration step before being placed in the pressing tool, the decorative layer and/or the support being adjusted to their dimensions in the packing element during the calibration step.

According to another aspect, the invention also relates to a trim element comprising at least one support and a decorative layer of carbon material extending over at least part of the support and forming at least part of the outer surface of the trim element, the decorative layer comprising at least one pattern comprising at least one visible zone of carbon material and at least one open zone formed by a through opening in the decorative layer, the support extending into the open zone of the pattern , the packing element having a substantially continuous outer surface at said pattern.

Other aspects and advantages of the invention will appear on reading the following description, given by way of example and made with reference to the appended drawings, in which:

- there is a schematic representation in perspective of part of a packing element according to the invention,

- there is a schematic sectional representation of part of the packing element according to the invention,

- Figs 3 to 5 are schematic representations of different stages of production of a packing element according to a production method according to the invention.

With reference to Figs. 1 and 2, a vehicle trim element 1 is described comprising at least one support 2 and at least one decorative layer 4. Such a trim element is for example intended to form a door panel, a dashboard covering or center console or whatever.

The support 2 is arranged to impart its shape and its mechanical characteristics to the packing element 1, in particular its rigidity. The support 2 comprises at least one support layer, for example made of a substantially rigid material for a door panel, such as a plastic or composite material. According to one embodiment, the support layer of the support 2 is made of a composite material comprising natural fibers in a polypropylene matrix, also known under the name of NFPP for “Natural Fiber PolyPropylene”. The natural fibers are for example chosen from flax, hemp, kenaf and/or wood. The support 2 has for example a three-dimensional shape with areas in relief. By way of example, the support 2 can for example comprise a zone protruding from the rest of the support 2 to form an armrest 6, as shown in the .

The support layer comprises an internal face 8, intended to extend from 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 passenger compartment of the vehicle.

According to one embodiment, the support 2 further comprises at least one appearance layer (not shown) extending over at least part of the outer face 10 of the support layer. Such an appearance layer is for example formed by a film of plastic material bonded to the outer face 10 of the support layer. Such a film can be thin so as not to increase the size of the packing element 1. According to one example, the thickness of the appearance layer is between 20 μm and 1000 μm, preferably substantially equal to 250 µm. The aspect layer can be colored. As a variant or in addition, the aspect layer can be translucent or transparent to form a light guide.

The decorative layer 4 extends over the support 2, that is to say either over at least part of the outer face 10 of the support layer, or over the appearance layer opposite the backing layer. The decorative layer 4 is for example glued to the support 2. The decorative layer 4 is arranged to confer its appearance and its feel to the trim element 1 at the place where the decorative layer 4 extends.

The decorative layer 4 is made of carbon material, which gives a particular appearance and feel to the decorative layer 4. In addition, the carbon material makes it possible to improve the mechanical properties of the packing element, particularly in terms of rigidity and self-supporting, more particularly when the support layer 2 is made of a composite material. Thus, the decorative layer 4 also forms a reinforcing layer of the support layer 2.

It is understood that the packing element may comprise several decorative layers extending over different parts of the support layer 2, these decorative layers 4 possibly being made of different materials and of which at least one is made of carbon material. Thus, by way of example, the packing element 1 comprises for example a layer of decoration 4 in carbon material surrounded by one or more layers of decoration in textile material, in plastic material, in ligneous material, in skin, such than leather or imitation leather or the like, so that, seen from the outside, the trim element 1 has a uniform appearance except in the area where the decorative layer 4 of carbon material extends, which has a particular with respect to the rest of the packing element.

The decorative layer 4 comprises an internal face 12 facing the external face 10 of the support layer 2 and an external face 14 extending towards the outside of the trim element 1. The internal face 12 defines the back of the decorative layer 4 and the external face forms at least part of the external surface 14 of the trim element 1, that is to say forming the visible part of the trim element 1 from the passenger compartment of the vehicle. The decorative layer 4 is shaped to the part of the face of the support layer 2 that it covers, that is to say that the decorative layer 4 matches the shape of this part of the face of the support 2. The decorative layer 4 has for example a thickness substantially between 20 μm and 200 μm .

The carbon material is for example in the form of carbon fibers without sizing, for example from recycling. The fact that there is no sizing makes it possible to improve the electrical properties of the carbon material, which is advantageous for a particular embodiment of the invention which will be described later.

The decorative layer 4 comprises at least one pattern 16. For this purpose, the decorative layer 4 is for example hollowed out so as to include at least one pattern 16 formed in the decorative layer 4 of carbon material. The pattern 16 comprises at least one visible area 18 formed by the carbon material of the decorative layer 4 and at least one open area 20 formed by a through opening in the decorative layer 4. The shape of the pattern 16, and in particular that of the open zone 20 which defines that of the visible zone 18, makes it possible to confer a particular appearance on the trim element 1 at the level of the decorative layer 4 by simply hollowing out the layer of carbon material to outline the visible zone 18 by the open area 20.

Thanks to the process for producing the packing element, which will be described later, at least a part of the support 2 extends into the open zone 20, that is to say that the material forming the support 2 penetrates into the through opening forming the open zone 20 in the decorative layer 4. The material of the support 2 is thus flush with the carbon material forming the visible zone 18 so that the outer surface 14 of the trim element 1 is substantially continuous at the level of the pattern 16, as more particularly visible on the . By substantially continuous, it is meant that the outer surface 14 does not have any protruding or recessed zones at the level of the pattern 16, even if it is not necessarily planar. Thus, if the outer surface 14 is curved, the curvature of the outer surface 14 is for example substantially regular at the level of the pattern 16. In other words, the outer surface 14 is substantially smooth at the level of the pattern 16 so that a user passing his hand over the pattern 16 does not feel, or very little, the transition between the visible zone 18 made of carbon material and the open zone 20 filled with the material of the support apart from the difference in feel due to the different materials in the zone visible 18 and the open area 20. Thus, the packing element 1 has a particularly satisfactory appearance.

When the decorative layer 4 is applied directly to the support layer, a user sees the support layer in the open area 20 of the pattern 16 from outside the trim element. When the support 2 comprises an appearance layer, it is this which is visible to a user in the open zone 20 from the outside of the trim element.

It is understood that the pattern 16 may comprise several distinct visible zones 18 and/or open zones 20.

According to one embodiment, the conductive nature of the carbon material of the decorative layer 4 is further exploited by arranging the pattern 16 so that it forms at least part of a functional electrical circuit performing a particular function when the circuit is supplied with electricity. To do this, the visible area 18 of the pattern 16 forms a conductive area and the open area 20 forms a non-conductive area. The conductive zone is electrically connected to a current source, for example at the level of a connection terminal formed by part of the visible zone 18, so that the circuit is powered and can perform the desired function. The shape of the pattern 16 is in this case not only chosen for aesthetic purposes but also for practical purposes. More particularly, the shape of the visible zone 18 makes it possible to form tracks of the electrical circuit. Depending on the desired function, several distinct conductive zones 18 and/or non-conductive zones 20 can be provided. In particular in the case where the pattern 16 also forms a circuit, the pattern 16 comprises in particular an open area 20, and therefore non-conductive, surrounding the visible area or areas 18, and therefore conductive, to isolate the functional electrical circuit from the rest of the decor layer 4.

The functions performed by the electrical circuit(s) are interaction functions with a vehicle passenger on the outer surface 14 of the trim element. In other words, the functions performed are part of the man-machine interface of the vehicle, the passengers of the vehicle being able to interact with the outer surface 14 of the trim element to activate, control and/or influence the function performed by the electrical circuit formed by pattern 16.

The pattern 16 can be arranged to form a capacitive circuit on the outer surface 14 of the trim element 1. Such a capacitive circuit makes it possible to form, for example, a so-called "touch slider" touch surface on the outer surface 14 of the decorative layer 4. Such a pattern 16 comprises for example a row of visible and conductive zones 18, each connected to a connection terminal and having the shape of an arrowhead. The visible and conductive zones 18 are separated by open and non-conductive zones 22 also in the shape of an arrowhead and delimiting the visible and conductive zones 18. Such a touch surface is for example used by sliding the finger along the row , for example to modify the value of a parameter controlled by a user, such as a temperature, a sound volume or the like.

Other forms of patterns can be envisaged, for example so that pattern 16 forms a flexible resistive circuit. By flexible, it is meant that the resistive circuit is capable of deforming when pressure is exerted on the outer face 14 of the decorative layer 4, this deformation modifying a characteristic value of the circuit so as to allow detection of a pressure on the decorative layer 4. Thus, the pattern 16 forms a pressure sensor or a force gauge on a part of the outer surface 14 of the decorative layer 4 at the level of the pattern 16. Such a sensor can for example be used to control the operation of certain functions of the vehicle, in particular by forming, for example, a switch or a continuous force sensor.

According to one embodiment, the pattern 16 formed in the decorative layer 4 may be only part of an electrical circuit. The other part can be formed in a reinforcement layer, also in carbon material, of the support layer 2. Such a reinforcement layer extends for example on the internal face 8 of the support layer 2 and is hollowed out to form a pattern cooperating with the pattern 16 of the decorative layer 4 to perform the desired function and/or to supply electricity to the visible and conductive zones 18 of this pattern 16. Thus, by way of example, the pattern in the reinforcement layer is arranged to form a capacitive circuit with the pattern in the decorative layer 4 to produce a so-called “multi-touch” capacitive circuit (multiple touch). As a variant, the pattern in the reinforcement layer is arranged to form a supply part of a circuit, the functional part of which is formed by the pattern 16 in the decoration layer 4. In this case, the functional part has the desired shape for the electric circuit to perform the desired function, as previously described, and the power supply part comprises the connection terminals of the circuit which are electrically connected to the current source. The power supply part is electrically connected to the functional part by at least a connection element extending in the support layer 2. The connection element is for example formed by a conductive material filling an opening passing through the support layer 2 between the supply part and the functional part of the circuit. It is understood that as a variant the part of the circuit extending on the internal face 8 of the support layer 2 does not extend into a reinforcing layer and that only the tracks necessary to produce this part of the circuit can be applied. on the internal face 8 of the support layer 2.

According to one embodiment, the pattern 16 formed by the decorative layer 4 forms a heating element arranged to heat the outer surface of the trim element 1 opposite the pattern 16. In this case, the pattern 16 forms for example a resistive circuit heating by Joule effect. According to another variant, the pattern 16 can form a proximity sensor, arranged to detect the presence of an object in the vicinity of the pattern 16. Several circuits can be provided in the decorative layer 4 by forming several distinct patterns in this layer of decor 4. Alternatively, several patterns 16 may be provided, some defining electrical circuits and others having only a decorative or informative function. For example, a pattern can form a pictogram informing a user of the presence of a functional electrical circuit in the vicinity of the pictogram.

According to a particular embodiment, the trim element may comprise a transparent or translucent coating extending over the decorative layer 4, through which the decorative layer 4 is visible. Such a coating is for example a varnish or a translucent film, for example based on Polyproylene, making it possible to protect the decorative layer 4 and in particular to prevent the degradation of the pattern(s) 16.

The packing element 1 described above is thus compact, light and has a satisfactory appearance. In addition, it makes it possible to easily integrate additional functions into the trim element by arranging the pattern(s) 16 appropriately and supplying them as described above. The fact that the support 2 extends in the open area(s) 20 of the pattern(s) 16 is also particularly advantageous when this pattern(s) 16 form electrical circuits. Indeed, the material of the support 2 then makes it possible to avoid short circuits by avoiding any contact between two conductive zones which should not be.

A method of making a packing element as described above will now be described with reference to Figs. 3 to 5.

A support 2 is first made. Thus the support layer is for example made of a composite material. If necessary, an appearance layer can be glued to the outer face 10 of the support layer. Alternatively, the appearance layer can be attached to the support layer 2 during assembly with the decorative layer, as will be described later. A step for calibrating the support 2 can be provided, during which the support 2 is formed to acquire the shape, the mechanical characteristics and the dimensions that it must have in the packing element. Such a calibration step is for example a thermocompression step during which the material forming the support layer is hot pressed under conditions, for example of temperature and pressure, defined in order to compress the natural fibers with the polypropylene of the matrix in order to obtain a rigid support layer having the desired shape and dimensions, in particular the thickness.

In parallel, before or after the production of the support, the decorative layer 4 is then produced, in particular by hollowing out one or more patterns 16 in the decorative layer 4. To do this, at least one through opening is hollowed out right through in the layer of carbon material in order to produce the open zone 20. By “right through”, it is meant that the layer of carbon material is hollowed out over its entire thickness. The shape of the through opening(s) in the layer of carbon material defines the shape of the pattern 16 and of the visible area(s) 18 thereof. According to the embodiment shown in the , the carbon layer is dug by means of laser radiation 22, which makes it possible to define the shape of the pattern 16 very precisely. As a variant, the layer of carbon material is hollowed out by chemical attack, by milling or by mechanical drilling in the carbon material. As described above, several patterns 16 can be provided in the layer of carbon material. The decorative layer 4 is thus obtained.

A layer of adhesive material 24 is then applied to the internal face 12 of the decorative layer 4, as represented on the .

The decorative layer 4 and the layer of adhesive material 24 can also undergo a calibration step during which this assembly is formed to acquire the shape, the mechanical characteristics and the dimensions that it must have in the trim element. As described above, such a calibration step is for example a thermocompression step during which the assembly is hot pressed under defined conditions in order to obtain a rigid assembly having the shape and dimensions, in particular the thickness, wanted.

The support 2 and the decorative layer 4, with its layer of adhesive material, are then placed in a pressing tool 26, in which the decorative layer 4 is pressed against the support 2 so as to be fixed thereon by through the layer of adhesive material 24 and so as to cause the support 2 to penetrate into the open zone(s) 20 of the pattern(s) 16 of the decorative layer 4. It is understood that other layers can be placed in the pressing tool when they are provided in the trim element. Thus, by way of example, a reinforcing layer can be fixed during pressing on the internal face 8 of the support 2.

As a variant, no layer of adhesive material is applied to the decor layer or to the support layer. The connection of the support layer and the decorative layer is done by melting the thermoplastic matrix of the two layers, in particular in the case of assembly by overmolding or thermocompression.

According to an embodiment shown in the , the pressing tool 26 is a three-dimensional shaping tool in which the trim element acquires the desired three-dimensional shape at the same time as the decorative layer 4 is fixed on the support 2 and the support 2 enters the or the open areas 20 of the pattern(s) 16 of the decorative layer 4.

If necessary, a translucent or transparent coating is applied to the decorative layer 4 before or after its assembly with the support 2.

The packing element 1 is then removed from the pressing tool 26, the external surface 14 being substantially continuous at the level of the pattern(s) 16, as previously described. Additional steps can be provided, such as the addition, if necessary, of other layers of decoration around the layer of decoration 4 comprising one or more patterns 16 when these other layers of decoration are made of a material other than the carbon material.

The process is therefore particularly simple and inexpensive to implement and makes it possible to obtain a trim element 1 having a particularly satisfactory appearance. In addition, the positioning of the pattern(s) 16 can be ensured precisely.

When one or more patterns 16 of the decorative layer 4 form an electrical circuit, the method further comprises an electrical connection step between the conductive area(s) and one or more current sources. This step is for example carried out during the assembly of the trim element 1 in a vehicle.

Claims (10)

Method for producing a trim element (1) comprising at least one support (2) and a decorative layer (4) of carbon material extending over at least a part of the support (2) and forming at least a of the outer surface (14) of the trim element, the decorative layer (4) comprising at least one pattern (16) comprising at least one visible zone (18) in carbon material and at least one open zone (20) formed by a through opening in the decorative layer (4), the method comprising the following steps:
- producing at least one pattern (16) in a layer of carbon material, said pattern (16) being produced by creating at least one open zone (20) over the entire thickness of the layer of carbon material so as to form a layer decor (4),
- placing the decorative layer (4) and a support (2) in a pressing tool (26),
- pressing the decorative layer (4) against the support (2) so that at least part of the support (2) penetrates into the open zone (20) of the pattern (16),
- removing the packing element from the pressing tool, said packing element having an external surface (14) substantially continuous at the level of the pattern (16). Production method according to claim 1, in which the support (2) comprises at least one support layer, the said support layer penetrating the open zone (20) of the pattern (16) during the pressing step. Production method according to Claim 1, in which the support (2) comprises at least one support layer and an appearance layer extending between the support layer and the decorative layer (4), at least the penetrating appearance in the open area (20) of the pattern (16) during the pressing step. Production method according to Claim 2 or 3, in which the support layer is made of a composite material comprising natural fibers in a polypropylene matrix. Production method according to any one of Claims 1 to 4, in which a layer of adhesive material (24) is applied to the decorative layer (4) before being placed in the pressing tool (26), the decorative layer (4) being fixed to the support (2) during the pressing step via the layer of adhesive material (24). Production method according to any one of Claims 1 to 5, in which the layer of carbon material is hollowed out by laser etching, chemical attack, milling or mechanical drilling in the carbon material to produce the pattern (16) in the said layer of carbon. Production method according to any one of Claims 1 to 6, in which the pattern (16) in the decorative layer (4) is further arranged to form a functional electrical circuit, the pattern (16) comprising at least one zone formed by the visible area (18) and at least one non-conductive area formed by the open area (20), the method comprising a step of electrically connecting at least one current source to the conductive area after the output of the packing element (1) of the pressing tool (26). Production method according to any one of Claims 1 to 7, in which the pressing tool (26) is a three-dimensional shaping tool, the packing element (1) acquiring a three-dimensional shape during pressing step. Production method according to any one of Claims 1 to 8, in which the decorative layer (4) and/or the support (2) undergo a calibration step before being placed in the pressing tool (26) , the decorative layer (4) and/or the support (2) being adjusted to their dimensions in the packing element (1) during the calibration step. Trim element comprising at least one support (2) and a decorative layer (4) of carbon material extending over at least part of the support (2) and forming at least part of the outer surface (14) of the lining element (1), the decorative layer (4) comprising at least one pattern (16) comprising at least one visible zone (18) in carbon material and at least one open zone (20) formed by a through opening in the decorative layer (4), the support (2) extending in the open area (20) of the pattern (16), the trim element (1) having an external surface (14) substantially continuous at the level of said pattern (16).