Light-permeable multilayer composite film for motor vehicle interior trim

Abstract

The invention relates to a light-permeable multilayer composite film (1), wherein the composite film (1) has an at least translucent cover layer (2) and a translucent or transparent carrier layer (6) arranged on the rear side of the cover layer (2), wherein at least one first illumination means (8) for illuminating a first segment (12) of the composite film (1) and a second illumination means (10) for selectively illuminating a second segment (14) of the composite film (1) are arranged on the rear side of the carrier layer (6). The carrier layer (6) has a barrier (16) in the transverse direction (Y) between the first illumination means (8) and the second illumination means (10) for reducing light guidance in the transverse direction (Y) within the carrier layer (6).

Description

[0001] Description

[0002] Translucent multi-layer composite film for automotive interior trim

[0003] The invention relates to a translucent multilayer composite film according to the preamble of claim 1. The invention further relates to an interior trim part of a vehicle according to claim 10.

[0004] Films in the form of multilayer composite films for coating or as surfaces of various objects are well-known in the art, including in the surface design of furniture and interior trim parts of vehicles. In the latter case, textured, patterned, or finely structured plastic films are used as surfaces for interior trim, often as relatively soft, foam-backed films with a pleasant feel, for example, for dashboard trim or door panels. With appropriate adjustments to their strength and design, such films can, of course, also be used for other high-quality coated goods.

[0005] Films used for interior trim in vehicles, furniture, bags, etc., also known as synthetic leather, often have a multi-layered structure, are frequently foamed, and feature three-dimensionally structured surfaces in a wide variety of shapes and finishes. The multi-layered structure generally consists of a top or decorative layer, which is embossed or molded, and one or more underlayers. The top layer is usually coated with lacquer and can also be colored. By carefully adjusting the layers, including their softness or the aforementioned foamed layers, an appealing feel is achieved, meaning a pleasantly soft touch and a certain sheen.The ever-increasing demand for comfort features, for example in the area of ​​vehicle equipment, leads not only in these areas to a desire for ever greater individualization of objects, but also to a focus on the integration of functions into everyday objects or their surfaces.

[0006] Sticking with the vehicle sector, the focus is now shifting to reference materials or flexible surface materials with integrated functional, sensor, or signaling elements, particularly the integration of lighting or signal lights into the films used for coating or cladding components. It has also been proposed to integrate electroluminescent elements or layers into or onto components.

[0007] to attach trim parts for the interior of motor vehicles. In this regard, DE 102005 038 680 A1 discloses a motor vehicle component with a three-dimensional surface that has an electroluminescent layer and is back-injected with thermoplastic material to fix the component shape. This is used to manufacture essentially smaller, non-flexible light sources, such as illuminated push buttons or light bulbs.

[0008] German patent DE 102010 051 166 A1 discloses a method for producing a material with an opaque surface and a graphic, logo, or animation visible on the surface when backlit. In this process, the graphic itself is made translucent on a film, while the spaces between it are kept or designed to be opaque, and then a translucent layer is applied.

[0009] DE 102004 044 035 A1 discloses a trim part for the vehicle interior, which is provided in its outer areas with a cavity into which a light guide can be inserted.

[0010] German patent DE 102016 106 539 A1 discloses an interior trim part for a motor vehicle, comprising a carrier layer, a cover layer, and optionally further intermediate layers. The carrier layer is provided with perforations that can form an illuminated structure when the carrier layer is illuminated from the back.

[0011] German patent DE102006 016 068 A1 discloses a layer-like lighting component whose structure or pattern is said to be visible both during the day and at night. This component has a first translucent area and a second, non-translucent area. The two areas are colored differently.

[0012] German patent DE 102007 041 678 A1 discloses a composite component for the interior fittings of a motor vehicle, comprising a carrier, a textile layer arranged thereon, and a protective plastic layer covering the latter. The carrier can also be translucent, thus allowing light to pass through the composite component.

[0013] DE 102004 010 974 A1 describes a layered lighting component for vehicles that includes translucent areas. A decorative material layer is applied to the visible side of the lighting component. This decorative material layer contains a lighting material in the translucent areas and a decorative material in the opaque areas.

[0014] Backlighting presents a key challenge in the development of translucent coating materials. The current approach involves using multiple LEDs on the back of the coating material, installed at a relatively large distance from the surface. This large distance is necessary to combine the multiple LED point light sources into a diffuse light source when the light is transmitted through the material.

[0015] To reduce the distance between the light source and the surface for a compact design while simultaneously ensuring uniform light distribution, a transparent or diffuse substrate can be used for the coating material. EP 3 702 144 A1 discloses a light-guiding and / or at least partially translucent, planar coating material made of plastic as a surface coating for an object, wherein the coating material is designed as a multilayer film composite, the film composite comprising at least one film within its layer structure that is provided with a printed or embossed light-guiding or translucent structure.

[0016] EP 3676 089 A1 discloses a further translucent multilayer composite film for providing a homogeneous light distribution on the surface when backlit.

[0017] A disadvantage is that the diffuse light distribution can lead to areas of the surface that should not be visually highlighted being unintentionally illuminated.

[0018] The object of the invention was to provide a film for the surface coating of objects, wherein individual sections or segments of the film surface can be selectively highlighted by illumination, but lateral, planar light transmission through the film can be avoided.

[0019] The solution to this problem is achieved by a translucent multilayer composite film with the features of independent claim 1.

[0020] Further advantageous embodiments are disclosed in the dependent claims. Another solution to the present problem is achieved by an interior trim part of a vehicle having the features of claim 10. Further advantages and features can be found in the general description and the exemplary embodiments.

[0021] The present invention relates to a translucent multilayer composite film, wherein the composite film comprises at least a translucent top layer and a translucent or transparent carrier layer arranged on the reverse side of the top layer. On the reverse side of the carrier layer, at least one first illumination element for illuminating a first segment of the composite film and a second illumination element for selectively illuminating a second segment of the composite film are arranged. The carrier layer has a barrier in the transverse direction between the first and second illumination elements to reduce transverse light transmission within the carrier layer.

[0022] For an overall translucent composite, the individual layers of the film can be completely transparent or partially translucent. Individual layers can also be opaque and have at least partially translucent segments or gaps, commonly known as a masking layer. The overall translucent composite film can have a multilayer structure consisting of a combination of translucent, transparent, and / or partially opaque layers. Translucency refers to a wavelength range of electromagnetic waves for visible light between 380 nm and 780 nm, hereinafter referred to as light waves. The top layer can, for example, be made of a thermoplastic polyolefin (TPO) and / or...or have an additional layer of lacquer to adjust the optical properties and improve abrasion resistance.

[0023] The composite film according to the invention comprises at least a first segment and a second segment, which can be individually backlit by a first and / or a second lighting means. The first and / or the second segment can, for example, be designed as a pictogram, number, or character and mark switching or operating elements.

[0024] It is desirable that at least the first segment and / or the second segment can be individually and independently highlighted by backlighting. To attenuate or completely prevent unwanted illumination of the second segment by the first light source, or vice versa, the substrate layer features a barrier in the transverse direction between the first and second light sources to reduce transverse light transmission within the substrate layer. This barrier can be a local geometric irregularity within the substrate layer designed for selective reflection or complete or partial absorption of light waves.The barrier prevents further transverse light transmission within the substrate layer, ensuring that the light waves emitted by the first lighting unit illuminate only the first segment and / or the light waves emitted by the second lighting unit illuminate only the second segment, thus visually highlighting it. The first segment and the second segment, respectively, remain unilluminated as long as the first or second lighting unit is switched off.

[0025] According to a further aspect of the present invention, a masking layer is arranged on the reverse side of the top layer. The masking layer is designed as an opaque layer with translucent areas. The masking layer can be formed by printing the reverse side of the top layer with an opaque ink, while the translucent areas of the top layer remain unprinted. In this way, for example, symbols, letters, or numbers can be depicted on the surface of the composite film, the visibility of which only becomes apparent when the film is backlit, or can at least be enhanced by backlighting.

[0026] According to a further aspect of the present invention, a translucent or transparent sensor layer is arranged between the masking layer and the carrier layer or between the carrier layer and the lighting means. The sensor layer can be formed as a multilayer structure consisting of electrically conductive and electrically non-conductive layers and can, for example, form a capacitive touch or proximity sensor. The proximity or touch sensors thus formed can be functionally assigned to the at least first segment and / or the second segment. For example, when used as a coating material for a surface in the interior of a vehicle, the composite film can be used to control vehicle functions by triggering a technical command for controlling functions in a vehicle when a person approaches or touches the composite film in the area of ​​the first segment and / or the second segment.

[0027] According to a further aspect of the present invention, the barrier has a structured surface. The barrier can be produced by laser ablation, which creates the surface structure in the form of roughness. The peaks and valleys of the resulting surface structure represent a multitude of local scattering and reflection centers for the light waves, thereby effectively reducing light transmission in the transverse direction within the substrate layer.

[0028] According to a further aspect of the present invention, the barrier is formed by a recess. The depth of the recess is less than the thickness of the carrier layer. The deeper the recess, the more effective the described barrier effect. A particularly advantageous feature is that the design of the barrier recess according to the invention avoids any visual impairment of the composite film or the top layer, since the recess does not penetrate the carrier layer. This prevents, for example, the top layer from sagging in the area of ​​the barrier. It also allows, for example, a complete, continuous vacuum to be applied to the underside, which is beneficial and, depending on the machine type, even necessary in a subsequent molding step, such as thermoforming.

[0029] According to a further aspect of the present invention, the recess is filled with a polymer composition. The polymer composition can be, for example, a resin or an adhesive. Advantageously, the stiffness of the carrier layer can be increased in the area of ​​the recess. Preferably, the stiffness of the entire composite film remains unchanged across its planar extent. By avoiding local changes in the stiffness and / or the elongation properties of the film, subsequent processing of the composite film, for example, when coating a component carrier in a thermoforming process, can be simplified.

[0030] Transverse light transmission within the substrate layer can be further reduced by using an opaque polymer composition. The polymer composition can, for example, contain inorganic pigments such as titanium dioxide.

[0031] According to a further aspect of the present invention, the carrier layer has a thickness between 1 mm and 3 mm. The carrier layer can be made of any thermoplastic material, preferably polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyethylene terephthalate modified with glycol (PETG), or polycarbonate (PC). A thermoplastic material with a thickness between 1 mm and 3 mm offers a good compromise between a compact structure, good thermoformability, and low overall weight of the composite film.

[0032] According to a further aspect of the present invention, the lighting means are designed as LEDs and arranged on a flexible film substrate. In other words, the lighting means can be arranged within a layer of the composite film and integrated into the composite structure in a particularly space-saving manner. Conductive tracks can be arranged on the substrate using electrically conductive printing inks, which can supply the LEDs with current.

[0033] The present invention further relates to an interior trim panel of a vehicle comprising a composite film according to the invention. The interior trim panel can, for example, be a door panel, a console, a headliner, or an instrument panel for the vehicle interior. The interior trim panel has a carrier on the outer surface of which the composite film according to the invention is arranged.

[0034] Exemplary embodiments and further advantages of the invention are schematically illustrated and explained in more detail below in connection with the following figures. These show:

[0035] Fig. 1 shows a schematic representation of a translucent composite film known from the prior art.

[0036] Fig. 2 shows a translucent composite film according to a first embodiment according to the invention.

[0037] Fig. 3 shows a translucent composite film according to a second embodiment according to the invention, wherein the barrier has a structured surface.

[0038] Fig. 4 shows a translucent composite film according to a third embodiment according to the invention, wherein the recess is filled with an opaque polymer composition.

[0039] The above figures are described in Cartesian coordinates with a longitudinal direction X, a transverse direction Y perpendicular to the longitudinal direction X, and a vertical direction Z perpendicular to both the longitudinal direction X and the transverse direction Y. The longitudinal direction X can also be referred to as depth X, the transverse direction Y as width Y, and the vertical direction Z as height Z. The longitudinal direction X and the transverse direction Y together form the horizontal, X, Y, which can also be referred to as the horizontal plane X, Y. The longitudinal direction X, the transverse direction Y, and the vertical direction Z together can also be referred to as spatial directions X, Y, Z, or as Cartesian spatial directions X, Y, Z.

[0040] Figure 1 shows a translucent multilayer composite film 1 known from the prior art, wherein the composite film 1 has a translucent top layer 2 and a masking layer 18 arranged on the back of the top layer 2. A transparent carrier layer 6 is arranged on the back of the masking layer 18. The composite film 1 has a first segment 12 and a second segment 14, which can be illuminated by a first light source 8 and / or a second light source 10 arranged on the back of the carrier layer 6. The light sources 8 and 10 are designed as LEDs and are arranged on a flexible film substrate 24. The film substrate 24 has an electrically conductive layer 27 formed by an electrically conductive ink, which supplies current to the light sources 8 and 10. In the illustrated embodiment, the first light source 8 is switched on.The light waves are guided through the carrier layer 6 and the first segment 12 through the cover layer 2. The first segment 12 is optically highlighted by the surrounding areas of the composite film 1. Although the second lighting unit 10 is switched off, the light waves of the first lighting unit 8 are reflected by reflections within the composite film 1, and in particular at the boundaries of the carrier layer 6 and the masking layer 18, and are thus guided in the transverse direction Y through the carrier layer 6, so that the attenuated light waves of the first lighting unit 8 also optically highlight the second segment 14.

[0041] Figure 2 shows a translucent composite film 1 according to a first embodiment of the invention, wherein the individual superimposed layers of the composite film 1 correspond to the structure of Figure 1. In contrast to Figure 1, the carrier layer 6 has a barrier 16 in the transverse direction Y between the first illumination element 8 and the second illumination element 10 to reduce light transmission in the transverse direction Y within the carrier layer 6. The barrier 16 is formed by a wedge-shaped recess 22. The depth of the recess 22 is less than the thickness of the carrier layer 6. The barrier 16 prevents further light transmission in the transverse direction Y within the carrier layer 6, so that the light waves emitted by the first illumination element 8 illuminate only the first segment 12 and thus optically highlight it.The second segment 14 remains unilluminated because the second lighting unit 10 is switched off. According to a second embodiment, the barrier 16 of the translucent composite film 1 according to the invention in Figure 3 has a structured surface 20. The surface of the wedge-shaped recess 22 has peaks and valleys, which leads to the refraction or reflection of light waves when they strike the barrier 16. This further effectively reduces the light transmission in the transverse direction Y within the carrier layer 6.

[0042] Figure 4 shows the translucent composite film 1 according to a third embodiment of the invention, wherein the recess 22 is filled with an opaque polymer composition 26. The polymer composition 26 is an adhesive that is injected into the void of the recess 22 after the composite film 1 has been manufactured. This ensures that the stiffness of the carrier layer 6 in the area of ​​the recess 22 remains unchanged. The polymer composition 26 is opaque. The light transmission is further reduced by the opacity of the polymer composition 26 in the transverse direction Y within the carrier layer 6.

[0043] Reference symbol list (part of the description)

[0044] 1 composite film

[0045] 2 Top layer

[0046] 6 Carrier layer

[0047] 8 first lighting device

[0048] 10 second lighting source

[0049] 12 first segment

[0050] 14 second segment

[0051] 16 Barrier

[0052] 18 masking layer

[0053] 20 structured surfaces

[0054] 22 Exclusion

[0055] 24 film substrate

[0056] 26 opaque polymer composition

[0057] 27 electrically conductive layer

[0058] X longitudinal direction; depth

[0059] Y transverse direction; width

[0060] Z vertical direction; height

[0061] X, Y Horizontal; horizontal plane

Claims

Patent claims 1. Translucent multilayer composite film (1), wherein the composite film (1) has at least a translucent top layer (2) and a translucent or transparent carrier layer (6) arranged on the back side of the top layer (2), wherein on the back side of the carrier layer (6) at least a first illumination means (8) for illuminating a first segment (12) of the composite film (1) and a second illumination means (10) for selectively illuminating a second segment (14) of the composite film (1) are arranged, characterized in that the carrier layer (6) has a barrier (16) in the transverse direction (Y) between the first illumination means (8) and the second illumination means (10) for reducing light transmission in the transverse direction (Y) within the carrier layer (6).

2. Composite film (1 ) according to claim 1 , characterized in that a masking layer (18) is arranged on the reverse side of the cover layer (2).

3. Composite film (1 ) according to one of claims 1 to 2, characterized in that a translucent or transparent sensor layer is arranged between the masking layer (18) and the carrier layer (6) or the carrier layer (6) and the illumination means (8, 10).

4. Composite film (1 ) according to claim 3, characterized in that the sensor layer forms a touch sensor.

5. Composite film (1) according to one of claims 1 to 4, characterized in that the barrier (16) has a structured surface (20).

6. Composite film (1 ) according to one of claims 1 to 5, characterized in that the barrier (16) is formed by a recess (22).

7. Composite film (1 ) according to claim 6, characterized in that the recess (22) is filled with a polymer composition (26).

8. Composite film (1 ) according to one of claims 1 to 7, characterized in that the carrier layer (6) has a layer thickness between 1 mm and 3 mm.

9. Composite film (1 ) according to one of claims 1 to 8, characterized in that the lighting means (8, 10) are designed as LEDs and are arranged on a flexible film substrate (24).

10. Interior trim part of a vehicle comprising a composite film (1 ) according to one of claims 1 to 9.

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