FR3081133A1 - MOTOR VEHICLE PART COMPRISING A FLASHING SURFACE FILM - Google Patents

Abstract

The invention relates to a part (2) of a motor vehicle made of plastic material comprising: - a main body (4) transparent or translucent, - a transparent or translucent surface film (6) comprising two opposite faces (10, 12) l one to the other with at least one relief (8) formed on each of the two faces (10, 12), - an adhesive layer (14) transparent or translucent disposed between the main body (4) and the surface film ( 6), and - means (18) able to send light into the main body (4) so that the light is reflected in the main body (4) and leaves it through a face (24) of the main body ( 4) in contact with the adhesive layer (14), the piece (2) being able to refract the light rays sent into the piece (2) at least twice, once when the light rays reach one of the faces ( 10) of the surface film (6) and a second time when the light rays reach the other face (12) of the surface ilm (6).

Description

The invention relates to motor vehicle parts made of plastic and more particularly the integration of three-dimensional effect surface films on such parts.

These surface films are films made of plastic. They include one or more layers of plastic (for example an inner layer (called matrix) of polyurethane and decorative layers of polyamide) transparent. The decorative layers form the external faces of the film and for this purpose carry one or more reliefs making it possible to obtain a depth effect, called above "three-dimensional effect". It is a lenticular effect. The reliefs can be obtained by stamping (or embossing) the faces of the surface film.

An example of such a surface film is described in patent AT 511,083 B1.

These surface films are currently present on various equipment, in particular sports equipment (for example skis), in order to optimize the visual rendering of this equipment by being placed on the latter, for example on the face of skis bearing the mark of maker.

In order to obtain an optimal visual effect, an impression is made on the face of the surface film intended to be in contact with the equipped part. It can for example be a screen printing.

The phenomenon observed is as follows: the light flux reaching the surface film (called the incident ray) is partly refracted during its passage through the surface film. The part of the refracted light flux then reaches the face of the film in contact with the equipped part (that is to say the face having undergone printing) and will be reflected by the printed layer. The luminous flux then crosses the surface film in the direction of the face opposite to the part (that is to say the entry face). The luminous flux then leaves the surface film (we speak of an emerging ray) by undergoing a second refraction. The angles of refraction and reflection of the light rays are different depending on the area of the relief in interaction with the light rays. The positioning of the reliefs with respect to each other on either side of the film makes it possible to obtain an optimal visual effect.

This solution has a major drawback. Indeed, if the equipped part is a transparent or translucent part, then the surface film does not allow this transparency of the part to be preserved because of the printing carried out on one of the faces of the surface film. In other words, the technique implemented to obtain a quality visual effect alters the initial appearance of the equipped room.

Printing also requires a step of recovering the surface film after manufacture, which requires time and generates significant costs due to the printing techniques to be implemented, for example by depositing ink dots only. in strategic places to obtain an optimal optical effect.

In addition, the visual effect obtained is of a random quality because it is dependent on light, for example the amount of light, reaching the surface film. The visual effect could for example be of lower quality or even non-existent under certain conditions.

An object of the invention is therefore to propose a motor vehicle part comprising a three-dimensional effect surface film making it possible to maintain an optimal optical effect whatever the environment in which the bodywork part is located.

The subject of the invention is a motor vehicle part made of plastic and comprising:

- a transparent or translucent main body,

- a transparent or translucent surface film comprising two opposite faces to each other with at least one relief produced on each of the two faces,

a transparent or translucent adhesive layer placed between the main body and the surface film, and

- Means capable of sending light into the main body so that the light is reflected in the main body and leaves it through one face of the main body in contact with the adhesive layer, the part being capable of refracting the light rays sent in the room at least twice, once when the light rays reach one side of the surface film and a second time when the light rays reach the other side of the surface film.

Thus, a part is obtained retaining an optimal optical effect thanks to at least two refractions when the light flux crosses the surface film right through while avoiding an impression of the face of the surface film in contact with the main body, this which keeps the transparency of the room.

This lack of recovery for printing also saves time and saves money during the production of the parts, a non-negligible element in the case of parts having to be manufactured while respecting an industrial rate.

Finally, the integration of a light source in the room makes it possible to obtain a constant and quality optical effect whatever the environment in which the room is located.

The bodywork part according to the invention can also include at least one of the following characteristics:

the main body is made of a material having a refractive index different from that of the surface film;

- the adhesive layer has a refractive index different from that of the main body;

- the adhesive layer has a refractive index different from that of the surface film;

the adhesive layer comprises an acrylic adhesive;

- The part comprises an opaque substrate on a face of the main body opposite to the face of the main body in contact with the adhesive layer;

- the relief includes bosses;

- the main body is made of polymethyl methacrylate, polycarbonate, polyurethane, polypropylene, cyclo-olefins copolymers or cyclo-olefins-polymers;

the means capable of sending light into the main body comprise light-emitting diodes, optical fibers or even light guides made of polymethyl methacrylate with a light source at their end or remote;

- The means capable of sending light into the main body are positioned so as to send light from a face of the main body perpendicular to the face of the main body in contact with the adhesive layer;

The invention also relates to a motor vehicle comprising a part according to the invention.

We will now present several embodiments of the invention given by way of nonlimiting examples and with the support of the appended figures in which:

- Figure 1 is a sectional view of a portion of a motor vehicle part according to the invention;

- Figure 2 is an enlargement of the portion of Figure 1 showing the path of a light ray;

- Figure 3 is a top view of the portion of Figure 1, the light source being turned off; and

- Figure 4 is a top view of the portion of Figure 1, the light source being on.

Figure 1 shows a part 2 of a motor vehicle made of plastic and comprising a main body 4 transparent (it can also be translucent and it can have a diffusing effect to homogenize the distribution of light rays in the volume of this main body 4) , a transparent surface film 6 fixed to the main body 4 and comprising two faces opposite one another with at least one relief 8 produced on each of the two faces and a transparent adhesive layer disposed between the main body and the film area. The surface film 6 forms the external face of the part 2, that is to say the face visible to a user from outside the vehicle when the part 2 is mounted on a motor vehicle. The main body 4, the surface film 6 and the adhesive layer 14 are made of materials capable of refracting the light rays at least twice, a first time when the light rays reach one of the faces of the surface film and a second time when the light rays reach the other side of the surface film.

Here, transparency means the fact that a fraction of the light flux is able to pass through room 2. It is therefore a question of the transmittance of visible light (ratio characterizing the transmission of light in room 2). The main body 4 of the part 2 can have dimensions equivalent to standard vehicle parts, for example those of a bumper if the part 2 is a bumper. The material used for the production of the main body 4 allows good light scattering. It can for example be preferably made of polycarbonate (PC), polymethyl methacrylate (or PMMA), or alternatively polyurethane (PU) or polypropylene (PP) or else based on amorphous polyolefin such as cyclo-olefinescopolymers ( COC) and cyclo-olefins-polymers (COP).

The surface film 6 is a film as described above. It includes one or more layers of plastic. The materials used are for example polyamides, polycarbonates or even polyurethane. For example, polyurethane is used as an inner layer and the outer layers forming the outer faces are made of polyamide. Polyamides have a refractive index between 1.53 and 1.59. Polycarbonates have a refractive index between 1.56 and 1.64. Polyurethane has a refractive index between 1.50 and 1.67. However, the value of the refractive index depends on certain parameters such as the density of the material through which the light passes. When the surface film 6 is produced in several layers of material, the surface layer or layers carrying the relief (s) are at least 150 micrometers thick for a surface film 6 with a thickness of between 0, 2 and 0.8 millimeters. In any event, the surface film 6 is known to those skilled in the art, described for example in the patent cited in the preamble to the application.

The surface film 6 comprises at least one relief 8 which can take the form of particular patterns as shown in FIGS. 3 and 4. These patterns make it possible to obtain a depth effect which will be called optical effect hereinafter. three dimensions (lenticular effect). You can also obtain a texturing effect by giving the impression that the part 2 is rough or even bumpy while the latter is smooth. These patterns can be produced for example by stamping (or embossing) after extruding the film. This relief is visible in FIGS. 1 and 2. The reliefs 8 are produced in the example illustrated on the two faces of the surface film 8, the face 10 opposite the main body 4 and the face 12 in contact with the adhesive layer 14 The number of reliefs 8 can obviously vary.

The main body 4 can, as mentioned above, be a bumper or a part of the bumper located on the front face of the vehicle or of a hubcap. The main body 2 can for example be made of polyamide, polycarbonate or else polymethyl methacrylate. It is therefore produced from a transparent plastic material which can be identical or different from that of the surface film 6. The main body 4 can then have an identical or different refractive index than that of the surface film.

In order to fix the surface film 6 to the main body 4, a layer of adhesive material 14 is added between the two. This adhesive layer 14, which can be deformable, not only allows the fixing of the surface film 6 to the main body 4 but it also contributes to the conservation of an optimal optical effect by playing the role of optical intermediary by ensuring the continuity of passage of light waves. In fact, it is made of a material having a refractive index different from that of the surface film 6. The adhesive layer can for example be made of acrylic adhesive, a material having a refractive index equal to 1.49. In addition to the difference in refractive index, the adhesive layer can be transparent. This makes it possible to obtain a transparent or translucent part 2 with an optimal optical effect.

In order to accentuate the depth effect and / or the texturing effect, means 18 capable of sending light are integrated into part 2. They will be called "light source 18" below. It can also be a light guide. The light emitted is visible light having a wavelength between about 400 and 800 nm.

The light source 18 can for example be made up of optical fibers or PMMA light guides with a light source at the end or positioned remotely. Advantageously, the light source 18 can consist of LEDs. It can for example be integrated by fixing a housing 20 on a lateral face of the part 2, by ensuring for example the fixing of the housing 20 on the part 2 by means of a stud 22. The light source 18 can be positioned so as to send light, quite powerfully and directly or indirectly, from a face of the main body 4 perpendicular to the face 24 of the main body 4 in contact with the adhesive layer 14. The light is in this case laterally diffused in the main body 4 from one end of the latter. In any event, the light source 18 makes it possible to obtain a constant visual effect with respect to a room for which the visual effect is obtained by interaction between the room and the surrounding light. In addition, it is possible to vary the color of the light emitted in order to obtain a personalized visual effect.

FIG. 2 represents an enlargement of FIG. 1 on which the trajectory of a light ray is represented.

The face of the main body 4 opposite the face 24 in contact with the adhesive layer 14 can be covered with an opaque substrate 26 (for example a layer of paint) as can be seen in FIG. 2.

A portion of the light ray emitted by the light source 18 can be reflected several times in the main body 4 at the faces 24 and 28 of the latter.

When the light ray reaches a portion of the face 24 of the main body 4 in contact with the adhesive layer 14, a part of the latter is able to pass from the main body 4 to the adhesive layer 14 and can be reflected on the face of the adhesive layer 14 opposite the main body 4 to return to the main body 4 where it is partly reflected at the face 28 and returned towards the adhesive layer 14. These different passages between the main body 4 and the adhesive layer 14 can be accompanied by a more or less significant refraction or no refraction, as is the case in FIG. 2.

When the light ray reaches a portion of the adhesive layer 14 in contact with the surface film 6, at least part of this light ray undergoes two successive refractions at the reliefs 8, a first passing from the adhesive layer 14 to the film of surface 6 and a second passing from the surface film 6 to the air. These successive refractions are due to the differences in refractive indices between the adhesive layer 14, the surface film 6 and the air.

In addition, the reliefs 8 present on the faces 10 and 12 play a role in the refraction of the light rays, which makes it possible to obtain an optimal optical effect by reorienting the light rays differently thanks to the different changes of direction of the surfaces 10 and 12 at the level of these reliefs. In other words, a light ray reaching a relief 8 in a first zone or in a second zone will not be refracted identically if the orientation of the first zone (that is to say the plane in which s 'extends this area) is different from the orientation of the second area.

Figures 3 and 4 are top views of the part 2, the light source 18 (connected to an energy source by means 30) being inactive in Figure 3 and activated in Figure 4.

When the light source 18 is activated, the latter can illuminate the room beyond the areas comprising reliefs 8. When the light rays reach the latter, the phenomenon described above occurs, which makes it possible to obtain a texturing effect and / or an impression of relief.

To make part 2, it is possible to mold the main body, for example by injection, then fix the surface film 6 on the main body 4 using the adhesive layer 14.

The invention is not limited to the embodiments presented and other embodiments will be apparent to those skilled in the art.

It is in particular possible to consider protecting the surface film when the latter is exposed and can be damaged due to climatic hazards (rain, prolonged exposure to the sun, hail, ...). Such protection can be achieved by adding a layer of material above the surface film, for example a layer of transparent plastic or an adhesive layer. This additional transparent layer 10 protects the surface film without degrading the optical properties of the part.

It is also possible to produce the vehicle part by overmolding the main body on an assembly composed of the surface film and the adhesive layer (playing here only its role of optical intermediary taking into account overmolding).

In addition, the patterns present on the surface film can take different forms from that illustrated in FIGS. 3 and 4.

List of numerical references: piece

4: main body: surface film: reliefs

10, 12: faces of the surface film: adhesive layer

18: light source: housing: stud

24, 28: faces of the main body: opaque substrate

30: means of feeding

Claims (11)

claims 1. Motor vehicle part (2) made of plastic material, characterized in that it comprises: - a transparent or translucent main body (4), - a transparent or translucent surface film (6) comprising two faces (10, 12) opposite one another with at least one relief (8) produced on each of the two faces (10, 12), - a transparent or translucent adhesive layer (14) disposed between the main body (4) and the surface film (6), and - Means (18) capable of sending light into the main body (4) so that the light is reflected in the main body (4) and exits therefrom by a face (24) of the main body (4) in contact with the adhesive layer (14), the part (2) being able to refract the light rays sent into the part (2) at least twice, a first time when the light rays reach one of the faces (10) of the film surface (6) and a second time when the light rays reach the other face (12) of the surface film (6). 2. Part (2) according to claim 1, wherein the main body (4) is made of a material having a refractive index different from that of the surface film (6). 3. Piece (2) according to any one of the preceding claims, in which the adhesive layer (14) has a refractive index different from that of the main body (4). 4. Part (2) according to any one of the preceding claims, in which the adhesive layer (14) has a refractive index different from that of the surface film (6). 5. Piece (2) according to any one of the preceding claims, wherein the adhesive layer (14) comprises an acrylic adhesive. 6. Part (2) according to any one of the preceding claims comprising an opaque substrate (26) on a face (28) of the main body (4) opposite to the face (24) of the main body in contact with the adhesive layer ( 14). 7. Part (2) according to any one of the preceding claims, in which the relief (8) comprises bosses. 8. Part (2) according to any one of the preceding claims, wherein the main body (4) is made of polymethyl methacrylate, polycarbonate, polyurethane, polypropylene, copolymer cyclo-olefins or cyclo-olefins- 5 polymers. 9. Part (2) according to any one of the preceding claims, in which the means (18) capable of sending light into the main body (4) comprise light-emitting diodes, optical fibers or even light guides. 10 polymethyl methacrylate with a light source at their end or remote. 10. Part (2) according to any one of the preceding claims, in which the means (18) capable of sending light into the main body (4) are positioned so as to send light from a face of the main body 15 (4) perpendicular to the face (24) of the main body in contact with the adhesive layer (14). 11. Motor vehicle comprising a part (2) according to any one of the preceding claims.