Translucent metallized design surface

Abstract

The present invention relates to a multilayer body comprising a transparent thermoplastic layer, a diffuser layer and a metal layer, which, despite having a decorative structured visible surface, is able to transmit information from a projection unit behind it with excellent clarity and brightness. Corresponding elements can be used, for example, in car-to-X communication.

Description

[Technical field]

[0001] The present invention relates to a combination of a decorative multi-layer body and a light source that transmits information.The invention also relates to the use of such an element. [Background technology]

[0002] Body components based on thermoplastic materials used in vehicles offer significant advantages over body components made from other materials, such as glass or metal. These advantages include, for example, increased impact strength, high fracture resistance, and / or reduced weight, which in the case of passenger cars allows for higher occupant safety and lower fuel consumption in road traffic accidents. Finally, thermoplastic materials allow for a significantly greater design freedom for body mounting parts, since they are easier to mold. Thermoplastic materials are becoming increasingly important as a result of recent developments in the field of partial and fully electric drives, since automobiles can be designed more aerodynamically and their designs are more distinguishable from conventional internal combustion vehicles. A known example of a new aerodynamic design is a front grille, which consists of a closed thermoplastic molding over the entire surface area. Furthermore, transparent, transparent-colored, and translucent thermoplastic polymers are suitable for providing light functions to mounting parts such as headlights or front grilles. Fueled by vehicle personalization and the development towards highly automated and autonomous driving, there is a demand for many new variants of indicator and decorative lights that enhance the communication between the vehicle and its surroundings ("car-to-X") to a higher level.

[0003] In this respect, it is a technical challenge to integrate display functions, light functions and light designs into an aerodynamically closed decorative thermoplastic moulding.

[0004] In the prior art, closed front grilles of vehicles with integrated electronic displays have already been described. The solution described in DE 101 13 200 13 578 A1 has the advantage that the electronic display is arranged behind a closed cover sheet and can in this case fulfill both decorative and informational tasks. The described display comprises, together with a primary light source, a light guide plate which not only illuminates the display panel but also provides light highlighting the brand logo located in the center of the grille. The light color and light intensity of the decorative lights can be controlled electronically. This type of technical solution has the major disadvantage that the body surface reserved by the display is no longer available for real, i.e. not digitally represented, decorative elements. This is because the electronic display is not able to adequately simulate the dynamic appearance of the decoration created by the natural ambient light. The difference between the naturally changing light, shadow and color shimmer of the decoration and the electronically created image is always noticeable and can be annoying, especially when the electronically created image is intended to simulate a three-dimensional or metallic reflective surface. A further disadvantage is that the electronic display always consumes electrical energy. Therefore, continuous operation of a display whose sole purpose is to perform a decorative task is disadvantageous from an energy point of view.

[0005] No approach can be derived from the prior art as to how such components should be procured. EP 1 339 633 A1 describes vapor deposition and sputtering methods for producing metal coatings. EP 1 339 633 A1 discloses a metallized plastic component with a display element produced using such a method, having a first adhesion-promoting layer on which a metal coating is provided. The metal coating, which is opaque per se, is partially removed with a laser so that backlighting is possible. However, such a system does not extend beyond the decorative element to be illuminated. In the case of two-dimensional rear projection, the remaining opaque parts of the metal coating will appear as dark defects in the information display. A display of variable information without image distortion is therefore not possible.

[0006] US Patent No. 5,399,633 shows that a sufficiently thin evaporated or sputtered metal layer is partially transparent to LED light, so that in combination with an opaque paint layer behind the metal layer, the symbol can be illuminated when the backlighting is activated, and becomes invisible as a result of the metallic luster when the backlighting is turned off. Multi-component injection molding or in-mold coating of opaque films in a combined work process is mentioned as a method for producing the display element. However, this component can only be used as an LED symbol display with an "on / off" circuit, but not as a transitional display with variable image content and variable colors. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent Application Publication No. 102010008334 [Patent Document 2] DE 10337456 [Patent Document 3] German Patent Application Publication No. 102005006459 [Patent Document 4] International Publication No. 2008 / 034610 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a sheet-like thermoplastic molded article having a decorative structure that is suitable for use as a decorative vehicle body component of a vehicle and at the same time as a (preferably colored) changing display. In particular, as many areas as possible, i.e., over the topographically designed decorative elements, should be usable as a display screen with a prominent contour. In this case, the safety aspect of the exterior display of a passenger car should be considered, and its image information and video information should be recognizable over a wide field of view in a contrast-rich and error-free manner.

Means for Solving the Problem

[0009] Surprisingly, it has been found that the lighting unit according to claim 1 can transmit information with an exact contour via light, despite the decorative surface having a structure, and thus the above problem is solved.

[0010] In the context of the present invention, the lighting unit comprises the following elements: A transparent thermoplastic layer having a visible surface and a surface facing away from the visible surface, having a transmittance Ty of 10% or more determined in accordance with DIN ISO 13468-2:2006 (D65, 10°), and having a three-dimensional structured surface on the surface facing away from the visible surface, a transparent layer; A metal layer on the surface facing away from the visible surface directly above the transparent layer, having a transmittance Ty of 4% or more determined in accordance with DIN ISO 13468-2:2006 (D65, 10°), a metal layer; Here, the transmittance Ty of the combination of the metal layer and the transparent layer is determined in accordance with DIN ISO 13468-2:2006 (D65, 10°) and is at least 3.0%; A diffuser layer having a distance of 5 mm or less from the metal layer, having a transmittance Ty of more than at least 50% determined in accordance with DIN ISO 13468-2:2006 (D65, 10°), and having a half-value angle of 0° < x < 70° determined in accordance with DIN 5036:1978 (based on light intensity); a light source which transmits information and is located at a distance of less than 80 cm, preferably less than 50 cm, particularly preferably less than 15 cm, very particularly preferably less than 5 cm from the diffuser layer; in that order.

[0011] The individual elements of the lighting unit according to the invention are explained in more detail below.

[0012] The lighting unit comprises a transparent layer having a visible surface and a surface opposite to the visible surface. Transparent in the context of the present invention means that the layer has a light transmittance Ty of 10% or more, preferably 50% or more, more preferably 65% ​​or more, even more preferably 65% ​​or more, particularly preferably up to 75%, determined according to DIN ISO 13468-2:2006 (D65, 10°). The transmittance relates to the respective layer at the respective thickness. For example, if the layer has a thickness of 2 mm, the transmittance value should be read on a layer 2 mm thick. According to the present invention, the haze of the transparent layer is preferably less than 5%, more preferably less than 3%, particularly preferably less than 2.0%, determined according to ASTM D1003:2013. The transparent layer is preferably smooth on the visible surface of the lighting unit, i.e. the surface facing away from the artificial light source. In the context of the present invention, "smooth" means that a high gloss surface is present. The maximum roughness Ra of such a surface, determined in accordance with DIN EN ISO 1302:2002-06, is preferably less than 0.1 μm, particularly preferably less than 0.05 μm, very particularly preferably less than 0.025 μm. The surface of the transparent layer opposite the visible surface is three-dimensionally structured.

[0013] The transparent layer consists of a thermoplastic material, which is preferably based on one of the following polymers: copolycarbonates, aromatic polycarbonates (PC), including polyestercarbonates, polystyrene (PS), styrene copolymers, for example transparent polystyrene-acrylonitrile (PSAN), polyalkylenes, such as polyethylene (PE) and polypropylene (PP), aromatic polyesters, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), PET-cyclohexanedimethanol copolymer (PETG), polyethylene naphthalate (PEN), polyacrylates, copolyacrylates, in particular polymethyl methacrylates or copolymethyl methacrylates, such as polymethyl methacrylate (PMMA), polyimides (for example PMMI), polyethersulfones, thermoplastic polyurethanes, cyclic olefin polymers or cyclic olefin copolymers (COP or COC), or mixtures of the mentioned components, as long as these mixtures are transparent, preferably based on aromatic polycarbonates and / or polymethyl methacrylates, particularly preferably based on aromatic polycarbonates.

[0014] In the context of the present invention, the term polycarbonate includes both homopolycarbonates and copolycarbonates. Polycarbonates can be linear or branched, as is known. When "polycarbonates" are mentioned in the context of the present invention, this is always understood to mean aromatic polycarbonates, even if not explicitly mentioned.

[0015] Polycarbonates are prepared, as is known, from dihydroxyaryl compounds, carbonic acid derivatives, and optionally chain terminators and branching agents.

[0016] The details of the production of polycarbonates have been described in numerous patent specifications over the past approximately 40 years. Reference is made herein, for example, to Schnell, "Chemistry and Physics of Polycarbonates", Polymer Reviews, Volume 9, Interscience Publishers, New York, London, Sydney 1964, and D. Freitag, U. Grigo, PR Mueller, H. Nouvertne, BAYER AG, "Polycarbonates" in Encyclopedia of Polymer Science and Engineering, Volume 11, Second Edition, 1988, pages 648-718, and finally Drs. U. Grigo, K. Kirchner and PR Mueller "Polycarbonate [Polycarbonates]" in Becker / Braun, Kunststoff-Handbuch [Plastics Handbook], Volume 3 / 1, Polycarbonate, Polyacetale, Polyester, Celluloseester [Polycarbonates, polyacetals, polyesters, cellulose esters], Carl Hanser Verlag Munich, Vienna 1992, pages Reference may be made to 117-299.

[0017] Dihydroxyaryl compounds suitable for the production of polycarbonates are, for example, hydroquinone, resorcinol, dihydroxydiphenyl, bis(hydroxyphenyl)alkanes, bis(hydroxyphenyl)cycloalkanes, bis(hydroxyphenyl)sulfides, bis(hydroxyphenyl)ethers, bis(hydroxyphenyl)ketones, bis(hydroxyphenyl)sulfones, bis(hydroxyphenyl)sulfoxides, α,α'-bis(hydroxyphenyl)diisopropylbenzene, phthalimidines derived from isatin or phenolphthalein derivatives, as well as ring-alkylated, ring-arylated and ring-halogenated compounds.

[0018] Preferred dihydroxyaryl compounds are 4,4'-dihydroxydiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 1,1-bis(4-hydroxyphenyl)phenylethane, 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene (bisphenol M), 1,1-bis(4-hydroxyphenyl)-p-diisopropylbenzene, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(3-chloro-4-hydroxyphenyl)propane, bis(3,5-dimethyl-4-hydroxyphenyl)methane, 2,2- ... Bis(3,5-dimethyl-4-hydroxyphenyl)propane, bis(3,5-dimethyl-4-hydroxyphenyl)sulfone, 2,4-bis(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)-p-diisopropylbenzene, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, 1,3-bis[2-(3,5-dimethyl-4-hydroxyphenyl)-2-propyl]benzene, and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC), as well as compounds of formula (I) to formula (III): [ka] (wherein R' in each case is C 1 ~C 4 - alkyl, aralkyl or aryl group, preferably methyl or phenyl, most preferably methyl.

[0019] Particularly preferred dihydroxyaryl compounds are 4,4'-dihydroxydiphenyl, 1,1-bis(4-hydroxyphenyl)phenylethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC), and dihydroxyaryl compounds of formula (I), formula (II), and / or formula (III).

[0020] These and other suitable dihydroxyaryl compounds are described, for example, in U.S. Pat. No. 2,999,835, U.S. Pat. No. 3,148,172, U.S. Pat. No. 2,991,273, U.S. Pat. No. 3,271,367, U.S. Pat. No. 4,982,014 and U.S. Pat. No. 2,999,846, DE-A-1,570,703, DE-A-2,063,050, DE-A-2,036,052, DE-A-2,211,956 and DE-A-3,832,396, FR-A-1,561,518, the monographs "H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964, p. 28 ff. and p. 102 ff." and "DG Legrand, JT Bendler, Handbook of Polycarbonate Science and Technology, Marcel Dekker New York 2000, p. 72 ff.

[0021] In the case of homopolycarbonates, only one dihydroxyaryl compound is used, whereas in the case of copolycarbonates, two or more dihydroxyaryl compounds are used.

[0022] Examples of suitable carbonic acid derivatives are phosgene or diphenyl carbonate.

[0023] Suitable chain terminators that can be used in the preparation of polycarbonates include both monophenols and monocarboxylic acids. Suitable monophenols are, for example, phenol itself, alkylphenols such as cresol, p-tert-butylphenol, cumylphenol, p-n-octylphenol, p-isooctylphenol, p-n-nonylphenol, and p-isononylphenol, and halophenols such as p-chlorophenol, 2,4-dichlorophenol, p-bromophenol, and 2,4,6-tribromophenol, 2,4,6-triiodophenol, p-iodophenol, and mixtures thereof.

[0024] Further preferred chain terminators are linear or branched, preferably unsubstituted C 1 ~C 30 Particularly preferred chain terminators are phenol, cumylphenol, and / or p-tert-butylphenol, which are mono- or polysubstituted with alkyl groups or tert-butyl.

[0025] Further suitable monocarboxylic acids are benzoic acid, alkylbenzoic acids, and halobenzoic acids.

[0026] The amount of chain terminator used is preferably 0.1 mol % to 5 mol %, relative to the molar number of dihydroxyaryl compounds used in each case. The addition of the chain terminator can be carried out before, during or after the reaction with the carbonic acid derivative.

[0027] Suitable branching agents are the tri- or higher functional compounds known in polycarbonate chemistry, in particular compounds having three or more phenolic OH groups.

[0028] Suitable branching agents are, for example, phloroglucinol, 4,6-dimethyl-2,4,6-tri(4-hydroxyphenyl)hept-2-ene, 4,6-dimethyl-2,4,6-tri(4-hydroxyphenyl)heptane, 1,3,5-tri(4-hydroxyphenyl)benzene, 1,1,1-tri(4-hydroxyphenyl)ethane, tri(4-hydroxyphenyl)phenylmethane, 2,2-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane, 2,4-bis(4-hydroxyphenylisopropyl)phenol, 2,6-bis(2-hydroxy-5′-methylbenzyl)-4- These include methylphenol, 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane, hexa-(4-(4-hydroxyphenylisopropyl)phenyl)orthoterephthalate, tetra(4-hydroxyphenyl)methane, tetra(4-(4-hydroxyphenylisopropyl)phenoxy)methane, and 1,4-bis((4',4''-dihydroxytriphenyl)methyl)benzene, as well as 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride, and 3,3-bis(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole.

[0029] The amount of any branching agent used is preferably 0.05 mol % to 2.00 mol %, again relative to the number of moles of dihydroxyaryl compound used in each case.

[0030] The branching agent can be formed in the initial charge in the alkaline aqueous phase together with the dihydroxyaryl compound and the chain terminator, or can be dissolved in an organic solvent and added before the phosgenation. In the case of the transesterification process, the branching agent is used together with the dihydroxyaryl compound. The aromatic polycarbonate present in the composition according to the invention is preferably produced by the interfacial process.

[0031] It is preferred to use linear polycarbonates.

[0032] The aromatic polycarbonates of the invention preferably have a weight-average molecular weight M between 10 000 g / mol and 50 000 g / mol, more preferably between 14 000 g / mol and 40 000 g / mol, even more preferably between 15 000 g / mol and 35 000 g / mol, particularly preferably between 18 000 g / mol and 32 000 g / mol, very particularly preferably between 20 000 g / mol and 28 000 g / mol. w The values ​​apply to determination by gel permeation chromatography using dichloromethane as eluent and calibration with linear polycarbonate (composed of bisphenol A and phosgene) of known molar mass distribution from PSS Polymer Standards Service GmbH (Germany), calibration according to method 2301-0257502-09D (2009, German version) from Currenta GmbH & Co. OHG (Leverkusen). The eluent for calibration is likewise dichloromethane. Column combination of crosslinked styrene-divinylbenzene resin. Diameter of analytical column: 7.5 mm; length: 300 mm. Particle size of column material: 3 μm-20 μm. Concentration of solution: 0.2% by weight. Flow rate: 1.0 ml / min, temperature of solution: 30° C. Detection using a refractive index (RI) detector.

[0033] The MVR value of aromatic polycarbonates measured according to ISO 1133:2012-03 at 300 °C and 1.2 kg is preferably 3 / (10 minutes)~35cm 3 / (10 min), more preferably 10 cm 3 / (10 minutes)~20cm 3 / (10 minutes).

[0034] Reported M W The values ​​and MVR values ​​are based on the total amount of aromatic polycarbonate present in the composition.

[0035] Particularly preferred polycarbonates are homopolycarbonates based on bisphenol A, homopolycarbonates based on 1,3-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and copolycarbonates based on the two monomers bisphenol A and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.

[0036] "Based on" means that preferably at least 60% by weight, more preferably at least 70% by weight, even more preferably at least 80% by weight of the total composition of the thermoplastic material is the corresponding polymer. In addition to the one or more polymers mentioned, the thermoplastic material preferably contains further conventional additives. Examples of these include flame retardants, antistatic agents, UV absorbers, stabilizers, antioxidants, and mold release agents. Suitable UV absorbers are benzotriazoles, triazines, benzophenones, and / or arylated cyanoacrylates. Preferred stabilizers include phosphites and phosphonites, as well as phosphines. It is also possible to use alkyl phosphates, such as monohexyl phosphate, dihexyl phosphate, and trihexyl phosphate, triisooctyl phosphate, and trinonyl phosphate. Usable antioxidants include phenolic antioxidants, such as alkylated monophenols, alkylated thioalkylphenols, hydroquinones, and alkylated hydroquinones. Suitable release agents are, for example, release agents based on fatty acid esters, preferably release agents based on stearic acid esters, particularly preferably release agents based on pentaerythritol. It is preferable to use pentaerythritol tetrastearate (PETS) and / or glycerol monostearate (GMS).

[0037] The composition particularly preferably contains less than 0.1% by weight of scattering additives, for example based on acrylates, polyethylene, polypropylene, polystyrene, glass, aluminum oxide and / or silicon dioxide, and very particularly preferably the composition is free of these.Furthermore, the composition particularly preferably contains less than 0.1% by weight of white pigments or similar pigments, for example titanium dioxide, kaolin, barium sulfate, zinc sulfide, aluminum oxide, aluminum hydroxide, quartz powder, interference pigments and / or pearlescent pigments, i.e. platelet-shaped particles, for example coated and / or uncoated mica, graphite, talc, SiO 2 , chalk and / or titanium dioxide, and very particularly preferably free of these.

[0038] Furthermore, the composition particularly preferably contains less than 0.1% by weight of nanoparticulate systems such as metal particles, metal oxide particles, etc., and very particularly preferably the composition is free of these.The composition also preferably contains less than 0.1% by weight of pigments based on insoluble pigments, such as those described, for example, in DE-A-10057165 and WO-A-2007 / 135032, and particularly preferably is free of these.

[0039] Colorants can be added to the transparent material to change the color impression. The thermoplastic material is preferably transparently pigmented, particularly preferably neutrally pigmented. This has the advantage that it preserves the color space of the light source that is located behind the transparent layer and transmits information, which may be, for example, a display. Such neutrally pigmented compositions are described, for example, in EP 2 652 029, which describes preferred materials for the transparent thermoplastic layer. The corresponding polycarbonate compositions are: I. (1a) and / or (1b) and (4) and (2a) and / or (2b), II. (1a) and / or (1b) and (5) and (2a) and / or (2b), III.(1a) and / or (1b) and (7), IV.(1a) and / or (1b) and (4) and (7), V.(1a) and / or (1b) and (5) and (7), VI.(4) and (2a) and / or (2b), VII.(5) and (2a) and / or (2b), VIII.(2a) and / or (2b) and (4) and (6), IX.(2a) and / or (2b) and (5) and (6), X. (3) and (4), XI.(3) and (5), XII.(3) and (4) and (6), XIII.(3) and (5) and (6), XIV.(3) and (4) and (7), XV.(3) and (5) and (7), XVI.(3) and (4) and (2a) and / or (2b), XVII.(3) and (5) and (2a) and / or (2b), XVIII.(6) and (1a) and / or (1b), XIX.(6) and (1a) and / or (1b) and (7), XX.(1a) and / or (1b) and (8), XXI.(7) and (4), XXII.(7) and (5), XXIII.(1a) and / or (1b), XXIV.(2a) and / or (2b), XXV.(7), XXVI.(2a) and / or (2b) and (7), wherein the structure is selected from the following: [ka] (In the formula, Ra and Rb are independently a linear or branched alkyl group or a halogen; n, independently of each R, is a natural number between 0 and 3, and when n=0, the group is hydrogen. [ka] (In the formula, Rc and Rd are independently a linear or branched alkyl group or a halogen; n, independently of each R, is a natural number between 0 and 3, and when n=0, the group is hydrogen. [ka] where R is selected from the group consisting of H and p-methylphenylamine groups. [ka] (In the formula, R3 is a halogen; n=4) [ka] (In the formula, R1 and R2 are independently a linear or branched alkyl group or a halogen; (n is a natural number between 0 and 4) [ka] (In the formula, The radicals R(5 to 20) are, in each case independently of one another, hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, t-hexyl, fluorine, chlorine, bromine, sulfone or CN, and M is selected from the group consisting of aluminum, nickel, cobalt, iron, zinc, copper, and manganese; Here, the colorants of Structure (1a), Structure (1b), Structure (2a), Structure (2b), and Structure (3), and the colorants of Structure (4), Structure (5), Structure (6), Structure (7), and Structure (8a / b) are used in the thermoplastic polymer composition in an amount of 0.000001% by weight to 1.000000% by weight based on the individual components, relative to the total polymer composition.

[0040] The transparent layer is preferably produced by an injection molding process. Thermoforming is also conceivable in principle.

[0041] The thickness of the transparent layer preferably ranges between 2 mm and 8 mm, particularly preferably between 2.5 mm and 6 mm, very particularly preferably between 3 mm and 4 mm.

[0042] The transparent thermoplastic layer has a three-dimensional structured surface. The term "three-dimensional structured surface" encompasses patterns, textures and particles, including the spatial arrangement and distribution of individual structural elements, especially those introduced into the surface, which produce a visual impression of an optical design to the observer. For this purpose, the structural elements are preferably present in a lateral extent having a dimension of at least 1 mm, more preferably more than 3 mm, particularly preferably more than 5 mm. Furthermore, the surface normals of these structural elements preferably have an angular deviation of more than 0.5°, preferably more than 2.5°, particularly preferably more than 10°, with respect to the surface normals of adjacent structural elements. Furthermore, the height of the three-dimensional structural elements is preferably in the range of 0.1 mm to 4 mm, preferably in the range of 0.2 mm to 1.5 mm, particularly preferably in the range of 0.5 mm to 1 mm. "From" / "to" here includes the lower / upper limits listed. The height of the three-dimensional structure here refers to the difference between the highest and lowest points of the structure, which corresponds to the difference between the minimum and maximum wall thickness in terms of the cross section of the component. The surface of the three-dimensional structured surface preferably has a plurality of mutually distinguishable faces. More preferably, there are at least 2 faces, even more preferably more than 10 faces, and especially preferably more than 50 faces.

[0043] The structure is preferably introduced into the surface by injection compression molding or is already introduced in the injection molding process.

[0044] The metal layer is applied to the surface opposite to the visible surface of the transparent thermoplastic layer, i.e., the surface having a three-dimensional structured surface. The metal layer typically conforms to the three-dimensional structured surface of the transparent thermoplastic layer in terms of its three-dimensional shape. The metal layer is preferably applied by sputtering technology or via an overmolded metal foil, a transfer film with a metal coating, or a metal spray coating system.

[0045] The metal layer preferably comprises at least one of the following metals or metalloids: Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Pd, Pt, Cu, Ag, Au, Zn, B, Al, In, Tl, Si, Ge, Sn, Pb, Sb, Bi. Of course, the metal layer can also comprise alloys or mixed layers of these elements. The metal layer preferably consists exclusively of one of these metals / metalloids / transition metals and / or alloys and / or mixed layers of these elements. Of course, the metal layer can also contain the usual impurities. The metal layer is a single layer or a layer sequence of two or more different metal layers.

[0046] In the simplest case, the metal layer has a total reflection configuration, similar to a mirror layer. As well as vacuum methods, in particular sputtering methods, involved in the application of metal layers, other possible methods are plating and wet chemical deposition methods.

[0047] The above-mentioned method is described in detail, for example, in "Vakuumbeschichtung Bd.1 bis 5" (Vacuum Coating Vol. 1 to 5), H. Frey, VDI-Verlag Duesseldorf 1995, or in "Oberflaechen- und Duennschicht-Technologie" (Surface and Thin-Film Technology) Part 1, RA Haefer, Springer Verlag 1987.

[0048] To achieve better metal adhesion and to clean the substrate surface, the surface to be coated can be subjected to a plasma pretreatment, which in some circumstances may change the surface properties of the polymer. These methods are described, for example, in "Metallized plastics 5&6: Fundamental and applied aspects" and H. Gruenwald et al. "Surface and Coatings Technology, 111 (1999), 287-296".

[0049] The transmittance Ty of the combination of metal layer and transparent layer, determined in accordance with DIN ISO 13468-2:2006 (D65, 10°), is at least 3.0%, more preferably at least 7.5%, even more preferably at least 10% and particularly preferably at least 14%.

[0050] The protective layer is preferably applied to the metal layer with the side facing the diffuser layer. A protective layer, which may consist of one or more individual layers, means a protective layer that protects the metal layer from external influences, i.e. from corrosion or even other external influences. Such a protective layer can be applied in a PECVD (plasma enhanced chemical vapor deposition) process or a plasma polymerization process. In this case, low-boiling precursors, in particular siloxane-based precursors, are vaporized and plasmatized and thus activated so that they can form a coating. Typical substances here are hexamethyldisiloxane (HMDSO), tetramethyldisiloxane, decamethylcyclopentasiloxane, octamethylcyclotetrasiloxane and trimethoxymethylsilane, in particular hexamethyldisiloxane. Most preferably, the layer is a layer comprising hexamethyldisiloxane (HMDSO).

[0051] The total thickness of the protective layer is less than or equal to 100 nm, more preferably less than 100 nm, particularly preferably less than 50 nm, very particularly preferably less than 35 nm.

[0052] In one embodiment, the protective layer may be formed from a conductive layer, for example from an indium tin oxide (ITO)-containing layer. Particularly preferably, this layer contains more than 50% by weight of ITO. Further useful conductive layers are zinc sulfide, silver chloride, zinc selenide, and cadmium telluride conductive layers. In this particular embodiment, the layer thickness may be up to 5 μm.

[0053] Preferably, at least 50%, more preferably at least 75%, and very particularly preferably the entire back surface of the transparent thermoplastic layer, i.e. the surface facing away from the visible surface, is covered with metal.

[0054] The metallic layer produces a metallic luster discernible at the visible surface of the transparent thermoplastic layer and through said transparent thermoplastic layer, which is produced by visible reflection of sunlight, where the total reflection is at least 10%, as determined in accordance with ASTM E 1331:2015. The surface of the metallic layer can be either reflective or semi-glossy.

[0055] In one embodiment, the metallic layer also provides color effects or colored shimmer by colorily reflecting ambient or incident white light. Such effects are preferably achieved by a colored transparent thermoplastic layer. This can be the transparent thermoplastic layer already described or a layer bonded thereto.

[0056] The overall nature and thickness of the metal layer, or of all metal layers in the case of two or more individual metal layers, should be selected such that the metal layer has a visible transmittance Ty (D65, 10°) according to DIN ISO 13468-2:2006 of 4% or more, preferably 8% or more, more preferably 10% or more, particularly preferably 15% or more, very particularly preferably 25% or more. This ensures that the information emitted by the light source not only passes through the diffuser layer, but also through the transparent layer after passing through the metal layer. Due to this transparency, the metal layer can transmit the entire color spectrum emitted by the light source / image source.

[0057] The diffuser layer is arranged at a distance of 5 mm or less, preferably less than 2 mm, from the metal layer, even if the diffuser layer is directly adjacent to the metal layer. In principle, it is possible to move the diffuser layer at a larger distance, but this is not preferred, since this would result in a loss of brightness, image sharpness, and viewing angle.

[0058] The diffuser layer is a layer that scatters white light, preferably at least in the wavelength range of from 450 nm to 670 nm, more preferably from 400 nm to 780 nm.

[0059] In principle different types of diffuser layers can be used: these are surface diffusers, volumetric diffusers or holographic diffusers.

[0060] The diffuser layer can be a film or a coating.

[0061] The thickness of the actively scattering layer in the diffuser is preferably less than 2 mm, more preferably less than 1 mm, even more preferably less than 650 μm, particularly preferably 500 μm or less, very particularly preferably less than 100 μm.

[0062] The diffuser layer has at least a transmittance, determined in accordance with DIN ISO 13468-2:2006, of more than 50%, preferably more than 75%, more preferably more than 80%, particularly preferably more than 85%.

[0063] Furthermore, the diffuser layer has a half-power angle measured according to DIN 5036:1978 (based on light intensity) of 10° to 50°, preferably 15° to 30°, and more preferably 18° to 25°.

[0064] Diffuser layers may be isotropically or anisotropically scattering. Anisotropically scattering diffuser layers are characterized by a greater spread in horizontal disparity and a smaller spread in vertical disparity, as measured by half-maximum angle.

[0065] In principle, any diffuser layer is suitable as a diffuser layer in the structure according to the invention, provided that it has a transmittance Ty of at least more than 50%, determined in accordance with DIN ISO 13468-2:2006 (D65, 10°), and a half-value angle of 10°≦x≦50°, determined in accordance with DIN 5036:1978 (based on light intensity).

[0066] The area of ​​the diffuser layer corresponds to the maximum image area of ​​the lighting unit.

[0067] The multilayer body of the lighting unit, which comprises a transparent thermoplastic layer with a three-dimensional structured surface, a metal layer and a diffuser layer with a direct or functionally oriented connection to the multilayer body, may be provided with further layers, in particular protective layers and / or connection layers. The transparent thermoplastic layer, in particular based on aromatic polycarbonate, preferably has a protective layer, in particular a scratch-resistant coating, which is arranged on the visible side of the lighting unit. Alternatively or more preferably, the diffuser layer has a protective layer on the side facing the light source.

[0068] Even more preferably, there are no further layers.

[0069] The light source is preferably an LED light source. In the context of the present invention, an "LED light source" should be understood to mean a light source emitting light having emission characteristics in which more than 70% of the intensity emitted in the range from 200 nm to 3000 nm is in the visible range of the spectrum. In the context of the present invention, the visible range is defined as the wavelength range from 360 nm to 780 nm. It is particularly preferred if less than 5% of the intensity is in the range below 360 nm. Considering the range from 360 nm to 500 nm, an LED light in the context of the present invention has a peak wavelength for its intensity (i.e. the wavelength of maximum intensity) of 360 nm to 460 nm, more preferably 400 nm to 460 nm, particularly preferably 430 nm to 460 nm or particularly preferably 400 nm to 405 nm. To determine the peak wavelength, a radiation-equivalent parameter, for example the radiation flux, is measured spectrally resolved and plotted in a Cartesian coordinate system. On the y-axis the radiation-equivalent parameter is plotted and on the x-axis the wavelength. The absolute maximum of this curve is the "peak wavelength" (as defined by DIN 5031-1 (1982)). The term "from to" includes the specified threshold values. The "LED light" preferably has a narrow emission width with a full width at half maximum of 60 nm or less, more preferably 45 nm or less, even more preferably 30 nm or less, where monochromatic light is particularly preferred. In this case, the full width at half maximum is the full width of the emission peak at half the height of the intensity.

[0070] Such luminescent properties are achieved, inter alia, by using semiconductors or lasers as light sources. Nowadays, semiconductor technology is often used, for example in LEDs (light emitting diodes), organic LEDs (OLEDs) and electroluminescent films.

[0071] The light source that transmits information is a projection unit. According to the present invention, "can transmit information" means, for example, that a moving image can be emitted by the light source. Suitable projection units are, for example, LED microprojectors, preferably near-edge projectors (short-distance projectors), in particular with an optical system adapted to the shape of the component, or flat display screens, for example of the LCD type or the organic LED type or the micro LED type. The flat display screen preferably does not have its own diffuser in front of its panel, but instead uses a diffuser element of the multilayer body of the lighting unit.

[0072] The light source is not necessarily directly mechanically joined to the other elements of the lighting unit: the light source may simply be functionally joined to other elements to form a unit, however mechanically joined combinations may be relevant as well.

[0073] The field of view of the lighting unit according to the invention preferably ranges (each in the horizontal direction) from -90° to +90°, preferably from -70° to +70°, in particular from -60° to +60°. If it is desired to increase the field of view, this can be achieved by imparting a convex curvature to the transparent thermoplastic layer at the visible surface.

[0074] The lighting unit according to the invention is preferably used in car-to-X communication in the activated state and as a passive design element in the switched-off state (switched-off light source). Due to the three-dimensional surface structure of the rear and the applied metallization, the component, which is preferably used in the exterior area of ​​passenger cars, has a very premium look. Possible applications are for example front panels, side panels, rear spoilers or tailgates. In the activated state, i.e. by rear projection, firstly light and design effects can be created, which can be blended with the three-dimensional structure to give the component an even more premium and elegant look. This can be used for example as a meet-and-greet function. Secondly, the entire surface of the component can also be used as a display for car-to-X communication. This is particularly important for autonomous vehicles. If the lighting unit according to the invention is located in the front module of the vehicle, it can be shown to pedestrians, for example, that they are allowed to cross at a pedestrian crossing and that the vehicle is waiting. If the lighting unit according to the invention is located in the rear area of ​​the vehicle, road users traveling at the rear can be made aware of dangerous situations at an early stage, for example traffic jams or construction sites. Other possible applications are, for example, status indications such as the state of charge for electric vehicles or the number of available seats for autonomous taxis. However, the lighting unit according to the invention can also be used as a decorative and / or information-carrying element in building facades, signs or building interiors.

[0075] The invention will now be described on the basis of an exemplary embodiment and with reference to FIG. [Brief description of the drawings]

[0076] [Figure 1] FIG. 1 shows a lighting unit according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0077] 1 shows a lighting unit according to the invention comprising a multi-layer body and a light source 600 for communicating information. The multi-layer body comprises a transparent thermoplastic layer 300 having a visible surface and a back surface opposite the visible surface. A scratch resistant coating 500 is applied to the visible surface of the transparent thermoplastic layer 300.

[0078] A three-dimensional structure is disposed on the rear surface of a transparent thermoplastic layer 300. A metal layer 200 is applied directly to the rear surface of the transparent thermoplastic layer 300, following the contours of the three-dimensional structure. A diffuser layer 100 is disposed at a distance from the metal layer 200, leaving a space 400 between them. Behind this is a light source 600, which is a projection element. EXAMPLES

[0079] The examples set forth in Table 1 were prepared, measured and evaluated as follows: For the tests, injection-molded sample plates with a three-dimensional surface structure on the back and dimensions of 200 mm x 150 mm x 3 mm were produced from the polycarbonate composition. To obtain different transmittances, different mixing ratios of clear transparent polycarbonate (Makrolon™ AG2677 / 550396) and dark transparent pigmented polycarbonate (Makrolon AG2677 / 18F123MA03) from Covestro Deutschland AG were set up. The proportion of dark polycarbonate was between 5% and 75% by weight. Subsequently, aluminum layers with different transmittances Ty (1%-25%) were applied to the sample plates under vacuum by a sputtering process. The transmittances were previously determined in a reference sample (small glass plate) according to DIN ISO 13468-2:2006 (D65, 10°). This resulted in suitable sputtering process times for the different transmittances. Finally, the transmittance of the injection-molded sample plates with and without a metallized layer was measured according to DIN ISO 13468-2:2006 (D65, 10°) and visually evaluated (% values ​​in the table). The sample without metallization serves only as a reference. A diffuser film (Makrofol™ LM 309 from Covestro Deutschland AG with a thickness of 300 μm, a transmittance of 86% according to DIN ISO 13468-2:2006 (D65, 10°) and a half-value angle of 20° according to DIN 5036:1978 (based on light intensity)) was applied directly to the rear of the metallized plates and these were illuminated from the rear, i.e. from the side facing away from the thermoplastic transparent layer, by a projector with a light output of 2000 lumens. The front side of the sample plate was exposed to direct sunlight. The images projected through the sample plates were then evaluated, among other things, for light quantity and color vividness. The visual evaluation was divided into good (++), fair (+) and poor (-). Plates rated good and fair correspond to embodiments according to the invention. The information transmitted by the projector was good to well discernible.

[0080] [Table 1]

Claims

1. The following elements: a transparent thermoplastic layer (300) having a visible surface and a surface facing away from the visible surface, the transparent layer (300) having a transmittance Ty of 10% or more, determined according to DIN ISO 13468-2:2006 (D65, 10°), and a three-dimensional structured surface on the surface facing away from the visible surface; a metal layer (200) on a surface facing away from the visible surface directly above the transparent layer (300), the metal layer (200) having a transmittance Ty of 4% or more, determined according to DIN ISO 13468-2:2006 (D65, 10°); wherein the transmittance Ty of the combination of said metal layer (200) and said transparent layer (300), determined in accordance with DIN ISO 13468-2:2006 (D65, 10°), is at least 3.0%; a diffuser layer (100) located at a distance of 5 mm or less from the metal layer and having a transmittance Ty of at least 50% as determined in accordance with DIN ISO 13468-2:2006 (D65, 10°) and a half-value angle of 10°≦<x≦50° as determined in accordance with DIN 5036:1978 (based on light intensity); a light source (600) transmitting information and located at a distance of less than 80 cm from said diffuser layer; Including, in this order, a lighting unit.

2. 2. The lighting unit according to claim 1, wherein the metal layer (200) is evaporated or applied onto the transparent layer (300).

3. 3. The lighting unit according to claim 1 or 2, wherein the diffuser layer (100) is arranged directly above the metal layer (200).

4. The lighting unit according to any one of the preceding claims, wherein the diffuser layer (100) faces a rear side of the metal layer (200).

5. The lighting unit according to any one of the preceding claims, wherein the light source (600) is a projector.

6. 6. Lighting unit according to any one of the preceding claims, wherein the transmittance of the diffuser layer (100) is more than 80%, determined according to DIN ISO 13468-2:2006.

7. 7. The lighting unit according to claim 1, wherein the three-dimensional structured surface has structural elements with a lateral extent of at least 1 mm, where the surface normals of these structural elements have an angular deviation of more than 0.5° with respect to the surface normals of adjacent structural elements, and where the heights of these structural elements are in the range from 0.1 mm to 4 mm.

8. 8. The lighting unit of claim 7, wherein the three-dimensional structured surface of the transparent thermoplastic layer (300) has more than ten mutually distinguishable faces.

9. The lighting unit according to any one of the preceding claims, wherein the material of the transparent thermoplastic layer (300) is based on aromatic polycarbonate.

10. 10. The lighting unit according to any one of claims 1 to 9, wherein the transparent thermoplastic layer (300) at the visible side of the lighting unit has a maximum roughness of less than 0.1 μm, determined in accordance with DIN EN ISO 1302:2002-06.

11. The lighting unit according to any one of the preceding claims, wherein the diffuser layer (100) is applied directly to the metal layer (200).

12. The lighting unit according to any one of the preceding claims, wherein the transparent thermoplastic layer (300) has a neutral grey colour.

13. A component from the exterior area of ​​a passenger vehicle, comprising a lighting unit according to any one of the preceding claims.

14. The component of claim 13 , wherein the component is a front panel, a side panel, a rear spoiler, a tailgate, or a sub-region of these elements.

15. Component according to claim 13 or 14, designed for car-to-X communication.

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