LED lighting elements based on multi-layered bodies with a stone look

Description

[0001] The invention relates to an illuminateable multilayer body with a carrier layer consisting of a thermoplastic material and a rock layer, having a stone appearance.

[0002] In the field of interior design, both for buildings and automotive interiors, there is a growing desire to create surfaces with a natural look. The impression of wood and stone, in particular, fosters an atmosphere of comfort, connection to nature, and sophisticated modernity. Stone is an attractive surface material because its weight and solidity suggest luxury. Granite elements, for example, used as sink surrounds, kitchen countertops, or floor and wall cladding, are indeed a luxury element, if chosen, due to the material's cost. At the same time, their considerable weight makes installation more difficult. There is a demand for design elements with a stone-like appearance.In order to reduce the weight of such elements, elements have been developed in the past in which, instead of a solid stone element, a multi-layered body is used, in which the thickness of the stone layer is reduced and a support layer is provided for stabilization.

[0003] For example, German patent DE 102005038022 A1 discloses a composite material with a dimensionally flexible, plastic-based carrier layer, which is bonded to a translucent natural stone layer without an adhesive layer. The use of the composite material as a cladding element, particularly for wall or facade cladding, is disclosed.

[0004] German utility model DE 202006013010 U1 describes a flexible flat material with a natural stone surface, which, in addition to a stone layer, has a flexible backing layer, wherein the flat material is provided with an adhesive layer for fixing to a substrate, as the use of the flat material as a floor covering, but also as a cladding element for wall surfaces, furniture, etc. to create decorative, solid-looking stone surfaces is intended.

[0005] WO 2000 / 068530 A1 also describes a multi-layered molded body with a colored base layer and a thin, visible surface layer of natural stone, distinguished by its exceptional color intensity, which is determined by the color of the base layer. The molded body is preferably flexible, with the grain structure of the natural stone layer being broken down. The molded body has a transparent top layer that gives it a homogeneous, smooth, and optionally glossy surface, despite the broken grain structure of the natural stone layer. Possible applications include, in particular, wall panels for both exterior and interior use, as well as car dashboards.

[0006] WO 2004 / 052561 A1 describes a process for manufacturing a multi-layered body with a stone layer, in which polymer is applied to a stone element, which then bonds to the surface and is peeled off the stone element together with a layer of stone. A sealant can be applied to the visible side of the multi-layered body. Compared to a solid stone slab of the same thickness, the multi-layered body has a significantly reduced weight. The suitability of the multi-layered bodies for floor coverings and wall panels is described.

[0007] JP 2002 205500 A reveals a series of multi-layered bodies for room lighting using LED technology. The decorative layer can also include a thin stone material.

[0008] Lighting is another essential aspect of interior design, both in automobiles and architecture. Besides conventional lamps, including designer ones, lighting elements are discreetly integrated into walls, cabinets, or floors.

[0009] It is already known from the prior art to combine a stone look with a light element. For example, WO 2009 / 110870 A1 describes a veneer consisting of a 0.3 to 1.5 mm thin, still translucent, stone layer on a transparent, translucent or opaque substrate layer made of glass, polycarbonate or another suitable material, whereby the element can be used for a variety of applications, including backlighting.

[0010] However, there remains a need for alternative decorative or functional elements with a stone look that offer an appealing day / night design and, considering the high-quality surface, have the lowest possible weight. Furthermore, such decorative and functional elements should ideally allow for a high degree of variability in lighting effects and personalization through new digital lighting technologies. The task, therefore, was to provide a suitable element.

[0011] The problem is solved according to the invention by an LED lighting unit comprising a) a multilayer body and b) an LED light source, the multilayer body comprises the following layers in this order: a1) a carrier layer made of a thermoplastic composition, a2) a stone layer, a3) a transparent layer made of a thermoplastic composition with a thickness averaged over the entire surface of 1 to 6 mm, which lies on the side of the stone layer a2, which represents the visible side of the multilayer body in the LED lighting unit, and wherein the LED light source is arranged on at least one side edge of the transparent layer a3 such that the transparent layer a3 can be used as a light guide for light emitted by the LED light source.

[0012] The term "LED lighting unit" is understood not only in the narrow sense of a package of mechanically connected individual parts, but also more broadly as a mere combination of individual parts that are (only) functionally connected to form a unit. It can also refer to a mechanically connected combination. According to the invention, "LED lighting unit" means any device or system that has a multilayer body functionally linked to an LED light source in the sense of the invention.These may be elements for the formation of floor coverings, for furniture construction, wall or door panels, parts of a lamp and lighting elements, a housing of household or electrical appliances, or components from the automotive sector, in particular from the area of ​​automotive interior design, such as parts of interior trim, parts of dashboards, parts of instrument panels, decorative strips, entry strips, parts of armrests, parts of center consoles.

[0013] The LED lighting units according to the invention feature an attractive day / night design. Without the LEDs switched on, the viewer sees an appealing, natural stone appearance. When the LED light source is switched on, a significantly different appearance emerges, as the edge illumination of the transparent component creates a three-dimensional topography of the stone layer, additionally featuring glittering or reflective elements depending on the type of stone used. Furthermore, the edge illumination can also be combined with backlighting to create further lighting effects.

[0014] "Multilayer body" in the sense of the invention is any structure consisting of several superimposed layers, comprising at least layers a1, a2, and a3. It is understood that further layers, for example on the outer surfaces of the multilayer body, on one or both flat sides of the multilayer body, may be provided, in particular a scratch-resistant layer. "On the outer surface of the multilayer body" here means the side of the support layer a1 or the transparent layer a3 that faces the side on which the stone layer a2 lies.

[0015] The multilayer body has the shape of a plate or a geometry that differs from that of a plate. A plate shape is the usual form, particularly for wall elements, tile elements, and floor coverings. LED lighting elements with a geometry that differs from a plate, featuring a three-dimensionally shaped visible surface, are, however, primarily used in automotive interior applications, such as car dashboards. Three-dimensionally shaped parts can be manufactured either directly using injection molding, for example, following the manufacturing process described in the examples, with three-dimensionally machined stone slabs, or through a subsequent thermoforming process of a plate-shaped multilayer body.

[0016] "Transparent" within the meaning of the present invention means a transmission Ty, measured at a thickness of 2 mm according to ISO 13468-2:2006 (D65, 10°), of preferably at least 85%, more preferably at least 86%, more preferably at least 88%, and preferably a turbidity of less than 2.0%, more preferably less than 1.5%, even more preferably less than 1.0%, more preferably less than 0.8%, determined according to ASTM D1003:2013 at a layer thickness of 2 mm.

[0017] Due to their long lifespan, low energy consumption, and good luminous efficacy, LED light sources are increasingly used, for example in the automotive industry, aviation, interior lighting, facade design, etc. LEDs emit light with a wavelength that depends on the semiconductor material and the doping, so that almost monochromatic light, even in the infrared or UV range, can be generated with LEDs.

[0018] There are RGB LEDs that emit red, green, or blue light. For white LED light, light of different wavelengths must be combined. This is usually achieved by combining a blue, a red, and a green LED to create so-called RGB (red-green-blue) modules, whose combined perceived light can be white, or through luminescence techniques in which all or part of the LED radiation is converted to other wavelengths, for example, using phosphors.

[0019] White light can be generated from an LED that emits blue light in the visible spectrum by adding a single phosphor that converts some of the blue radiation into red / yellow light. This method of generating white light is preferred for commercial applications due to cost and the high efficiency of blue LEDs.

[0020] Alternatively, white light can be generated from UV light produced by LEDs using three different phosphors that emit wavelengths corresponding to an RGB module. If this technique is used, compositions with increased stability against UV radiation are preferred, i.e., those with UV stabilization.

[0021] To achieve an overall color impression in LED modules that deviates from "white," the light sources mentioned above can be further modified as needed. This modification can be done, for example, by: Combination with a phosphorescent dye or combination with additional light sources with a different emission characteristic.

[0022] In principle, all LED / LED technologies described according to the invention can be used separately or together.

[0023] For the purposes of this invention, an "LED light source" is understood to be a light source that emits light with a radiation characteristic in which more than 70% of the intensity emitted in the range from 200 nm to 3000 nm lies in the visible part of the spectrum. For the purposes of this invention, the visible part is defined as the wavelength range from 360 nm to 780 nm. Particularly preferably, less than 5% of the intensity lies in the range < 360 nm. Considering the range from 360 nm to 500 nm, the LED light, according to this invention, has a peak wavelength with respect to its intensity—i.e., the wavelength of maximum intensity—of 360 nm to 460 nm, more preferably of 400 nm to 460 nm, and particularly preferably of 430 nm to 460 nm, or alternatively, particularly preferably of 400 nm to 405 nm. To determine the peak wavelength, a radiation-equivalent quantity such as, for example,The radiative flux is measured with spectral resolution and represented in a Cartesian coordinate system. The y-axis represents the radiation-equivalent quantity, and the x-axis represents the wavelengths. The absolute maximum of this curve is the "peak wavelength" (definition according to DIN 5031-1 (1982)). "From...to"... encompasses the specified limit values. The "LED light" preferably has a narrow emission width with a half-width of at most 60 nm, more preferably of at most 45 nm, and even more preferably of at most 30 nm, with monochromatic light being particularly preferred. Here, the half-width is the full width of an emission peak at half the intensity.

[0024] The use "as a light guide" means that at least a portion of the light emitted by the LED light source is transported through the transparent layer a3 by internal reflection. Preferably, at least a portion of the light emitted by the LED light source undergoes total internal reflection at the interfaces of the transparent layer a3 with the stone layer a2 and / or the transparent layer a3 with the ambient air or an additional transparent layer of the multilayer body located further outwards. "Interface" here refers to the surface at which and / or through which two or more layers of the multilayer body or the ambient air are connected to each other, or directly adjacent to each other. Interfaces are formed by material transitions.

[0025] Edge lighting is a relatively energy-efficient way to generate attractive lighting effects, as it requires relatively few LEDs.

[0026] It goes without saying that, in addition to the LED light source, which uses the transparent layer a3 as a light guide (i.e., for so-called "edge lighting" applications), light can also be shone into the multilayer body from the back, i.e., from the side of the substrate layer, thus creating classic backlighting. In backlighting, the LED light source is located behind the substrate layer, so that the substrate layer, stone layer, and transparent layer are illuminated through.

[0027] The fact that the transparent layer a3 can be used as a light guide for light emitted from the LED light source does not mean that the edge lighting must be continuously activated every day during operation. Rather, it is a technically defined option selectable by the user. Naturally, the edge lighting can also be switched off, as will usually be the case in daylight. It goes without saying that the light source can also be controlled using sensor or timer technology. If additional backlighting is provided, it can be selected as an alternative to the edge lighting or switched on simultaneously. Likewise, the LED lighting unit can also be used when both the backlighting and edge lighting are switched off.

[0028] The support layer a1 is a layer made of a thermoplastic composition. "Made of" means that the support layer consists of the composition. The thermoplastic composition is based on a thermoplastic polymer, which is preferably present in the thermoplastic composition in a proportion of at least 50 wt.%, more preferably at least 60 wt.%, even more preferably at least 75 wt.%, particularly preferably at least 85 wt.%, and most preferably at least 90 wt.%.

[0029] In principle, the substrate layer can be transparent, translucent, or opaque, with "transparent" being defined as described above. For the purposes of this invention, "translucent" refers to molding compounds that have a transmission Ty, measured at a thickness of 2 mm according to ISO 13468-2:2006 (D65, 10°), of < 40% and at least 2.5%, preferably > 2.5%, more preferably < 25% and > 2.7%, particularly preferably < 20% and > 2.9%, and preferably a turbidity, determined according to ASTM D1003:2013 at a layer thickness of 2 mm, of > 95%, particularly preferably > 99%. "Optical" within the meaning of the present invention are compositions which have a light transmission Ty of less than 2.5%, preferably less than 1.0%, determined at a layer thickness of 2 mm according to DIN ISO 13468-2:2006 (D65, 10°).

[0030] The composition of the carrier layer can be, in particular, black. According to the present invention, black compositions are understood to be those compositions which are described by the CIELab color coordinates L* less than 40, a* less than 15 and greater than -15, preferably less than 10 and greater than -10, and b* less than 15 and greater than -15, preferably less than 10 and greater than -10, determined at a thickness of 2 mm according to ISO 13468-2:2006 (D65, 10°).

[0031] Suitable thermoplastic polymers include, for example, aromatic polycarbonate (PC), polyester carbonate, polystyrene (PS), styrene copolymers, a polyalkylene such as polyethylene (PE) or polypropylene (PP), an aromatic polyester such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), PET-cyclohexanedimethanol copolymer (PETG), polyethylene naphthalate (PEN), a poly- or copolymethyl methacrylate such as polymethyl methacrylate (PMMA), a polyimide (e.g., PMMI), a polyethersulfone, a thermoplastic polyurethane, a cyclic olefin polymer or copolymer (COP or COC), or mixtures thereof, preferably aromatic polycarbonate, aromatic polyester, cyclic olefin polymer, including olefin copolymer, or polymethyl methacrylate, or mixtures thereof. If a mixture of different polymers is used, it is preferably a mixture of aromatic polycarbonate with PMMA or a polyester.

[0032] Particularly preferred is the polymer contained in the thermoplastic composition from which the support layer is formed, aromatic polycarbonate, alone or in mixture with another polymer, in particular a polyester.

[0033] The thermoplastic composition of the support layer preferably contains only aromatic polycarbonate as the thermoplastic polymer. Aromatic polycarbonates, as defined in the invention, are all known aromatic polycarbonates. This includes homopolycarbonates and copolycarbonates. Whenever the present invention refers to "polycarbonate" at any point, it specifically means aromatic polycarbonates. The aromatic polycarbonate in a thermoplastic composition in one of the layers of the multilayer body is either a specific aromatic polycarbonate or a mixture of different aromatic polycarbonates, for example, two different aromatic copolycarbonates, two different aromatic homopolycarbonates, or one aromatic homopolycarbonate and one aromatic copolycarbonate.

[0034] A portion, up to 80 mol%, preferably 20 mol% to 50 mol%, of the carbonate groups in the polycarbonates used according to the invention can be replaced by aromatic dicarboxylic acid ester groups. Such polycarbonates, which contain both acid residues of carbonic acid and acid residues of aromatic dicarboxylic acids incorporated into the molecular chain, are referred to as aromatic polyester carbonates. Within the scope of the present invention, they are also subsumed under the general term thermoplastic aromatic polycarbonates.

[0035] The polycarbonates are produced in a known manner from dihydroxyaryl compounds, carbonic acid derivatives, optionally chain terminators and branchers.

[0036] Details of the production of polycarbonates have been laid down in numerous patent specifications for about 40 years. Examples include Schnell, "Chemistry and Physics of Polycarbonates," Polymer Reviews, Volume 9, Interscience Publishers, New York, London, Sydney 1964; D. Freitag, U. Grigo, P.R. Müller, H. Nouvertné, 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 P.R. Müller, "Polycarbonate," in Becker / Braun, Kunststoff-Handbuch, Volume 3 / 1, Polycarbonate, Polyacetale, Polyester, Celluloseester, Carl Hanser Verlag Munich, Vienna 1992, pages 117-299.

[0037] Examples of dihydroxyaryl compounds suitable for the production of polycarbonates are hydroquinone, resorcinol, dihydroxydiphenyls, bis-(hydroxyphenyl)-alkanes, bis-(hydroxyphenyl)-cycloalkanes, bis-(hydroxyphenyl)-sulfides, bis-(hydroxyphenyl)-ethers, bis-(hydroxyphenyl)-ketones, bis-(hydroxyphenyl)-sulfones, bis-(hydroxyphenyl)-sulfoxides, alpha-alpha'-bis-(hydroxyphenyl)-diisopropylbenzenes, phthalimidines derived from isatin or phenolphthalein derivatives, and their nuclear-alkylated, nuclear-arylated, and nuclear-halogenated compounds.

[0038] 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 the bisphenols of formulas (I) to (III) in which R' each represents a C 1 to C 4 alkyl group, aralkyl group or aryl group, preferably a methyl group or phenyl group, most preferably a methyl group.

[0039] 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) as well as the dihydroxyaryl compounds of formulas (I), (II) and / or (III).

[0040] These and other suitable dihydroxyaryl compounds are described, for example, in US patents 2,999,835 A, 3,148,172 A, 2,991,273 A, 3,271,367 A, 4,982,014 A and 2,999,846 A, in German patent applications 1,570,703 A, 2,063,050 A, 2,036,052 A, 2,211,956 A and 3,832,396 A, in French patent 1,561,518 A1, and in the monograph "H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964, pp. 28 ff.; pp. 102 ff.." as described in "DG Legrand, JT Bendler, Handbook of Polycarbonate Science and Technology, Marcel Dekker New York 2000, p. 72ff."

[0041] In the case of homopolycarbonates, only one dihydroxyaryl compound is used; in the case of copolycarbonates, several dihydroxyaryl compounds are used.

[0042] Suitable carbon dioxide derivatives include, for example, phosgene or diphenyl carbonate.

[0043] Suitable chain terminators that can be used in the production of polycarbonates include both monophenols and monocarboxylic acids. Suitable monophenols include, for example, phenol itself, alkylphenols such as cresols, p-tert-butylphenol, cumylphenol, pn-octylphenol, p-iso-octylphenol, pn-nonylphenol, and p-iso-nonylphenol, halogenphenols such as p-chlorophenol, 2,4-dichlorophenol, p-bromophenol, 2,4,6-tribromophenol, 2,4,6-triiodophenol, and p-iodophenol, as well as mixtures thereof.

[0044] Preferred chain terminators are also phenols that are single or multiple times substituted with C1 to C30 alkyl groups, linear or branched, preferably unsubstituted or substituted with tert-butyl. Particularly preferred chain terminators are phenol, cumylphenol and / or p-tert-butylphenol.

[0045] Suitable monocarboxylic acids also include benzoic acid, alkylbenzoic acids and halogenbenzoic acids.

[0046] The amount of chain terminator to be used is preferably 0.1 to 5 mol%, based on the number of moles of dihydroxyaryl compounds used. The chain terminator can be added before, during, or after the reaction with a carbonic acid derivative.

[0047] Suitable branchers are the tri- or more than trifunctional compounds known in polycarbonate chemistry, especially those with three or more than three phenolic OH groups.

[0048] Suitable branching agents are, for example, phloroglucin, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptene-2, 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'-methyl-benzyl)-4-methylphenol, 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)-propane, Hexa-(4(4-hydroxyphenylisopropyl)-phenyl)-orthoterephthalic acid ester, 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.

[0049] The amount of any branching agents to be used is preferably 0.05 mol% to 2.00 mol%, based on moles of dihydroxyaryl compounds used.

[0050] The branching agents can either be placed in the aqueous alkaline phase with the dihydroxyaryl compounds and the chain terminations, or added dissolved in an organic solvent prior to phosgenation. In the case of the transesterification process, the branching agents are used together with the dihydroxyaryl compounds. The aromatic polycarbonates contained in the compositions according to the invention are preferably prepared by the interfacial process.

[0051] Linear polycarbonates are preferred.

[0052] The aromatic polycarbonates of the present invention preferably have weight-average molecular weights Mw between 15,000 and 25,000 g / mol, preferably between 15,000 and 24,000 g / mol, more preferably between 16,000 and 23,500 g / mol, and particularly preferably between 18,000 and 22,500 g / mol. These values ​​apply to determination by gel permeation chromatography using dichloromethane as the eluent, calibration with linear polycarbonates (from bisphenol A and phosgene) of known molar mass distribution from PSS Polymer Standards Service GmbH, Germany, and calibration according to method 2301-0257502-09D (from 2009 in German) of Currenta GmbH & Co. OHG, Leverkusen. The eluent is also dichloromethane during calibration. Column combination made of cross-linked styrene-divinylbenzene resins. Diameter of analytical columns: 7.5 mm; Length: 300 mm. Particle size of column material: 3 µm to 20 µm. Concentration of solutions: 0.2 wt%.Flow rate: 1.0 ml / min, solution temperature: 30°C. Detection using a refractive index (RI) detector.

[0053] The MVR value of the aromatic polycarbonate, measured according to ISO 1133:2012-03 at 300°C and 1.2 kg, is preferably 14 to 70 cm³ / (10 min), more preferably 18 to 65 cm³ / (10 min).

[0054] The MW and MVR values ​​refer to the total amount of aromatic polycarbonates contained in the composition.

[0055] Particularly preferred polycarbonates are the homopolycarbonate based on bisphenol A, the homopolycarbonate based on 1,3-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and the copolycarbonates based on the two monomers bisphenol A and 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.

[0056] It goes without saying that the thermoplastic composition can contain other components. These can be a wide variety of components, such as those found in thermoplastic compositions. In principle, any thermoplastic composition is suitable, as long as the viscosity of the molding compound is not so high as to impede sufficient wetting of the stone surface and adequate penetration of the cracks and pores in the stone.

[0057] A thermoplastic composition based on aromatic polycarbonate typically contains 0 to 5 wt.%, preferably 0.05 wt.% to 3 wt.%, and more preferably 0.1 wt.% to 1 wt.% additives. Here, as elsewhere, unless otherwise stated, the wt.% values ​​refer to the respective total composition.

[0058] Common polymer additives, such as those that may be present in the composition, are described, for example, in EP-A 0 839 623, WO-A 96 / 15102, EP-A 0 500 496 or "Plastics Additives Handbook", Hans Zweifel, 5th Edition 2000, Hanser Verlag, Munich. Other such additives include, for example, release agents, antistatic agents, fillers, antioxidants, flame retardants, anti-drip agents, thermostabilizers, flow improvers, optical brighteners, colorants, especially pigments such as white pigments, light scattering agents, UV absorbers and / or IR absorbers.

[0059] Preferably, the only additional additives in the composition of the carrier layer are one or more demolding agents, UV absorbers, colorants (including carbon black), scattering particles and / or one or more thermostabilizers.

[0060] Geeignete Thermostabilisatoren sind ausgewählt aus den Gruppen der Phosphate, Phosphite, Phosphonite und Phosphine. Beispiele sind Triphenylphosphit, Diphenylalkylphosphit, Phenyldialkylphosphit, Tris(nonylphenyl)phosphit, Trilaurylphosphit, Trioctadecylphosphit, Distearylpentaerythritoldiphosphit, Tris(2,4-di-tert-butylphenyl)phosphit (Irgafos ®< 168), Diisodecylpentaerythritoldiphosphit, Bis(2,4-di-tert-butylphenyl)pentaerythritoldiphosphit, Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol-diphosphit, Bis(2,4-di- cumylphenyl)-pentaerythritoldiphosphit, Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritoldiphosphit, Diisodecyloxypentaerythritoldiphosphit, Bis(2,4-di-tert-butyl-6-methylphenyl)-penta-erythritoldiphosphit, Bis(2,4,6-tris(tert-butylphenyl)pentaerythritoldiphosphit, Tristearylsorbitoltriphosphit, Tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylendiphosphonit, 6-Isooctyloxy-2,4,8, 10-tetra-tert-butyl-12H-dibenz[d,g]-1,3,2-dioxaphosphocin, Bis(2,4-di-tert-butyl-6-methylphenyl)methyl phosphite, bis(2,4-di-tert-butyl-6-methylphenyl)ethyl phosphite, 6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenz[d,g]-1,3,2-dioxaphosphocin, 2,2',2"-Nitrilo-[triethyltris(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite], 2-ethylhexyl(3,3',5,5'-tetra-tert-butyl-1, 1'-biphenyl-2,2'-diyl)phosphite, Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (PEP-36), 5-Butyl-5-ethyl-2-(2,4,6-tri-tert-butylphenoxy)-1,3,2-dioxaphosphirane, triphenylphosphine (TPP), trialkylphenylphosphine, bisdiphenylphosphinoethane, or a trinaphthylphosphine. In particular, triphenylphosphine (TPP), Irgafos®< 168 (tris(2,4-di-tert-butylphenyl)phosphite), PEP-36 (bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite), and tris(nonylphenyl)phosphite, or mixtures thereof, are used.

[0061] Phosphate stabilizers are, for example, phosphates of formula (IV) or mixtures of these phosphates. where R1 independently represents branched alkyl groups and / or optionally substituted aryl groups, the alkyl group being preferably a C1 to C18 alkyl, more preferably a C1 to C8 alkyl group. If a phosphate stabilizer is included, it is particularly preferably tri-(2-ethylhexyl) phosphate (triisooctyl phosphate).

[0062] The aryl group is preferably substituted with C1 to C8 alkyl, branched C1 to C8 alkyl, or cumyl, wherein the substituents may be the same or different, but identical substituents are preferred. Preferably, the aryl groups are substituted at positions 2 and 4 or 2, 4, and 6. Particularly preferred are tert-butyl substituents at these positions.

[0063] Furthermore, all R1s are preferred.

[0064] Furthermore, antioxidants such as phenolic antioxidants, for example, alkylated monophenols, alkylated thioalkylphenols, hydroquinones, and alkylated hydroquinones, can be used. Preferably, Irganox® < 1010 (pentaerythritol-3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate; CAS: 6683-19-8) and / or Irganox® < 1076 (2,6-di-tert-butyl-4-(octadecanoxycarbonylethyl)phenol) are used. Irganox® < 1076 (2,6-di-tert-butyl-4-(octadecanoxycarbonylethyl)phenol) is used with particular preference.

[0065] In a special embodiment, the phosphine compounds according to the invention are used together with a phosphite or a phenolic antioxidant or a mixture of the latter two compounds.

[0066] In a preferred embodiment, the stabilizer system consists of triphenylphosphine, a mixture of triphenylphosphine and a phenolic antioxidant such as Irganox®< 1076 or Irganox®< 1010 and / or a combination of phenolic antioxidant and phosphite, preferably a mixture of Irganox®< 1076 or Irganox®< 1010 and Irgafos®< 168 or PEP-36.

[0067] In another preferred embodiment, the stabilizer system consists of a phosphine, a phosphite and a phenolic antioxidant, for example triphenylphosphine, Irganox ®< 1076 and Irgafos ®< 168.

[0068] Suitable demolding agents include, for example, the esters or partial esters of monohydric to hexahydric alcohols, in particular glycerol, pentaerythritol, or Guerbet alcohols. Monohydric alcohols include, for example, stearyl alcohol, palmitic alcohol, and Guerbet alcohols. A dihydric alcohol is, for example, glycol; a trihydric alcohol is, for example, glycerol; tetrahydric alcohols include, for example, pentaerythritol and mesoerythritol; pentahydric alcohols include, for example, arabitol, ribitol, and xylitol; hexahydric alcohols include, for example, mannitol, glucite (sorbitol), and dulcite.

[0069] The esters are preferably the monoesters, diesters, triesters, tetraesters, pentaesters and hexaesters or mixtures thereof, in particular statistical mixtures, of saturated, aliphatic C 10 to C 36 monocarboxylic acids and optionally hydroxymonocarboxylic acids, preferably with saturated, aliphatic C 14 to C 32 monocarboxylic acids and optionally hydroxymonocarboxylic acids.

[0070] Commercially available fatty acid esters, especially of pentaerythritol and glycerol, may contain < 60% different partial esters due to manufacturing processes.

[0071] Saturated aliphatic monocarboxylic acids with 10 to 36 carbon atoms include, for example, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, hydroxystearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, and montanic acids. Particularly suitable release agents as component f) of the composition according to the invention are, for example, pentaerythritol tetrastearate (PETS) or glycerol monostearate (GMS). According to a specific embodiment of the invention, the overall composition contains release agents in a proportion of 0 ppm to 3000 ppm, preferably 100 ppm to 1000 ppm, and more preferably 150 ppm to 500 ppm, based on the mass of the overall composition.

[0072] Preferred UV absorbers are compounds that exhibit the lowest possible transmission below 400 nm and the highest possible transmission above 400 nm. Such compounds and their preparation are known from the literature and are described, for example, in EP-A 0 839 623, WO-A 96 / 15102 and EP-A 0 500 496. Particularly suitable ultraviolet absorbers for use in the composition according to the invention are benzotriazoles, triazines, benzophenones and / or arylated cyanoacrylates.

[0073] Particularly suitable ultraviolet absorbers are hydroxy benzotriazoles, such as 2-(3',5'-Bis-(1,1-dimethylbenzyl)-2'-hydroxy-phenyl)-benzotriazole (Tinuvin® < 234, Ciba Specialty Chemicals, Basel), 2-(2'-Hydroxy-5'-(tert.-octyl)-phenyl)-benzotriazole (Tinuvin® < 329, Ciba Specialty Chemicals, Basel), 2-(2'-Hydroxy-3'-(2-butyl)-5'-(tert.butyl)-phenyl)-benzotriazole (Tinuvin® < 350, Ciba Specialty Chemicals, Basel), Bis-(3-(2H-benztriazolyl)-2-hydroxy-5-tert.-octyl)methane, (Tinuvin® < 360, Ciba Specialty Chemicals, Basel), (2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(hexyloxy)-phenol (Tinuvin® < 1577, Ciba Specialty Chemicals, Basel), as well as the benzophenones 2,4-dihydroxy-benzophenone (Chimasorb® < 22, Ciba Specialty Chemicals, Basel) and 2-hydroxy-4-(octyloxy)-benzophenone (Chimasorb® < 81, Ciba, Basel), 2-cyano-3,3-diphenyl-2-propenic acid 2-ethylhexyl ester, 2,2-bis[[(2-cyano-1-oxo-3,3-diphenyl-2-propenyl)oxy]-methyl]-1,3-propanediyl ester (-9CI) (Uvinul® < 3030, BASF AG Ludwigshafen), 2-[2-Hydroxy-4-(2-ethylhexyl)oxy]phenyl-4,6-di(4-phenyl)phenyl-1,3,5-triazine (CGX UVA 006, Ciba Specialty Chemicals, Basel) or Tetraethyl-2,2'-(1,4-phenylene-dimethylidene)-bismalonate (Hostavin ®< B-Cap, Clariant AG).

[0074] Highly preferred UV absorbers include, for example, Tinuvin ®< 360, Tinuvin ®< 350, Tinuvin ®< 329, Hostavin ®< B-CAP, with TIN 329 and Hostavin ®< B-Cap being particularly preferred.

[0075] Mixtures of these ultraviolet absorbers can also be used.

[0076] There are no particular restrictions regarding the amount of ultraviolet absorber contained in the composition. According to a specific embodiment of the invention, the composition contains ultraviolet absorber in an amount of 0 ppm to 6000 ppm, preferably 500 ppm to 5000 ppm, and more preferably 1000 ppm to 2000 ppm, based on the weight of the total composition.

[0077] Anti-drip agents are preferably fluorine-containing anti-drip agents, in particular polytetrafluoroethylene.

[0078] However, if backlighting of the multi-layered body is planned in addition to edge lighting, the substrate layer must be designed to allow sufficient light to pass through it. In this case, the substrate layer should be transparent or at least translucent. The stone layer must also be chosen to be thin enough to maintain the desired degree of light transmission.

[0079] The substrate layer is preferably colored. Colorants and pigments, especially white pigments, commonly used for the respective thermoplastic material can be employed. In the "night design," the perceived color of the multilayer body is then determined by the color of the colored substrate layer, particularly when using white LED light. However, a colored night design, such as red, can also be achieved by using colored LED light, especially RGB LED light, instead of a white, cool white, or warm white LED light source.

[0080] The thickness of the support layer can be freely selected according to the specific application. Typically, the thickness of the support layer is chosen to provide sufficient stability to the multilayer component without using more material than necessary, as this not only incurs unnecessary costs but also unnecessarily increases the component's weight. Particularly in automotive interior components, however, it is crucial to achieve the lowest possible weight for the functional parts. Therefore, the thickness is preferably in the range of 0.5 to 6 mm, more preferably in the range of 1.0 to 5 mm, and even more preferably in the range of 1.5 to 4 mm. This thickness is averaged over the entire surface of the thermoplastic support layer. The deviation of the thickness at any single point of the layer from the thickness averaged over the entire surface is preferably a maximum of ± 10%, and more preferably a maximum of ± 5%.Since the stone layer usually has a slightly irregular surface and the material runs into the gaps, there is an insignificant, slight deviation from the average value at many points.

[0081] Preferably, the support layer completely covers the stone layer or extends beyond it on at least one side edge.

[0082] The rock layer a2 is a layer of metamorphic or sedimentary rock. It consists of several relatively discrete layers that can be peeled off as thin sheets of the natural rock material. Suitable rock materials include, for example, shaly claystones or clay shales, limestone, sandstone, mudstone, clay shale, quartzite, phyllite, mica schist, chlorite schist, gneiss, talc schist, blue schist or gluacophane schist, variegated schist, prasinite, epidote amphibolite, amphibolite, embrechite, agmatite, calcareous schist, mylonite, argillite, migmatite, marble, serpentinite, eclogite, schist, fruit schist, or granulite. The rock layer preferably comprises variegated schist, mica schist, limestone, sandstone, or marble; more preferably, it consists of one of these rocks. Basically, the layer of stone can be composed of different stone elements and, for example, represent a mosaic of one or more types of stone.Preferably, however, the stone layer consists of one type of stone and is made in one piece.

[0083] The thickness of the stone layer is ≤ 2 mm, preferably ≤ 1 mm, more preferably ≤ 0.5 mm, and particularly preferably ≤ 0.3 mm, where this is a thickness averaged over the entire flat surface of the stone layer. "Flat surface" is the side of the stone layer that, in the case of the multi-layered body, is oriented towards the visible side, i.e., intended to determine the optical appearance of the multi-layered body, as well as the side opposite this side.

[0084] Alternatively, the stone layer can also have an average thickness of > 2 mm across its entire surface. This is useful, for example, if the lighting unit is not to be equipped with backlighting, meaning that no light needs to pass through the stone layer.

[0085] The stone layer preferably exhibits a cohesive grain structure.

[0086] It is further preferred that the stone layer, at least on the flat side facing the transparent layer, has a topography with a maximum roughness Rz of preferably at least 0.1 µm, more preferably at least 0.5 µm, more preferably 0.5 to 10,000 µm, and particularly preferably 1.0 to 5,000 µm. The maximum roughness Rz is defined by the absolute vertical distance between the maximum profile peak height and the maximum profile valley depth. The measuring distance is preferably at least 2 cm. These values ​​of maximum roughness Rz are advantageous because, when illuminated laterally via one or more edges, this topography is visually emphasized by shadows, refraction, and the like on the rough stone surface, thus enhancing the three-dimensional impression perceived by the eye.

[0087] The transparent layer a3 is also a layer made of a thermoplastic composition. The principles already described for the carrier layer apply here, including the embodiments described as preferred, with the exception that the components of the thermoplastic composition must be selected to obtain a transparent composition as defined by the invention. Preferably, the composition of the transparent layer contains only one or more mold release agents, UV absorbers, and / or one or more thermostabilizers as further additives.

[0088] The transparent layer must have a thickness that is sufficient, but not excessive, to allow edge illumination of the multilayer body. At the same time, it is desirable to keep the thickness of the transparent layer a3 as low as possible to avoid unnecessarily increasing the weight of the LED lighting unit. The thickness is therefore in the range of 1 to 6 mm, more preferably in the range of 2 to 5 mm, and even more preferably in the range of 2.5 to 4 mm, with the thickness averaged over the entire surface of the transparent layer. The deviation of the thickness at any single point of the transparent layer from the thickness averaged over the entire surface is preferably a maximum of ± 10%.

[0089] To ensure sufficient flowability of the thermoplastic compositions and thus sufficiently good processability, the MVR value of the compositions (measured according to ISO 1133:2012-03 at 300°C and 1.2 kg) should preferably be between 14 cm³ / (10 min) and 80 cm³ / (10 min), more preferably between 20 cm³ / (10 min) and 80 cm³ / (10 min), even more preferably between 30 cm³ / (10 min) and 80 cm³ / (10 min) and particularly preferably between 32 cm³ / (10 min) and 75 cm³ / (10 min).

[0090] For good mechanical stability, the impact strength of the thermoplastic compositions, measured according to ISO 179 / 1eA:2010 at room temperature on 3 mm thick specimens, should preferably be at least 40 kJ / m², more preferably between 50 kJ / m² and 130 kJ / m², even more preferably between 55 kJ / m² and 120 kJ / m² and particularly preferably between 55 kJ / m² and 80 kJ / m².

[0091] The common thickness of the layers carrier layer a1, stone layer a2 and transparent layer a3 of the multilayer body of the lighting unit according to the invention is preferably 1.5 to 12 mm, more preferably 3 to 10 mm, and even more preferably 4 to 8 mm.

[0092] It is preferred that the transparent layer covers the stone layer almost completely, in particular to at least 90%.

[0093] A preferred LED lighting unit according to the invention comprises a) a multilayer body and b) an LED light source, the multilayer body comprises the following layers in this order: a1) a carrier layer made of a thermoplastic composition, wherein the thermoplastic composition is based on aromatic polycarbonate, a2) a stone layer, a3) a transparent layer made of a thermoplastic composition based on aromatic polycarbonate with an average thickness of 1 to 6 mm over the entire surface, which lies on the side of stone layer a2, which is the visible side of the multilayer body in the LED lighting unit, and wherein the LED light source is arranged on at least one side edge of the transparent layer such that the transparent layer can be used as a light guide for light emitted by the LED light source.

[0094] A further preferred LED lighting unit according to the invention comprises a) a multilayer body and b) an LED light source, the multilayer body comprises the following layers in this order: a1) a carrier layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50 wt.%, more preferably at least 75 wt.%, and even more preferably at least 90 wt.% aromatic polycarbonate, with a thickness of 0.5 to 6 mm averaged over the entire surface of the carrier layer, a2) a stone layer, a3) a transparent layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50 wt.%, more preferably at least 75 wt.%, and even more preferably at least 90 wt.% aromatic polycarbonate, with a thickness of 1 to 6 mm averaged over the entire surface, which lies on the side of stone layer a2 that represents the visible side of the multilayer body in the LED lighting unit, and wherein the LED light source is arranged on at least one side edge of the transparent layer such that the transparent layer can be used as a light guide for light emitted by the LED light source.

[0095] A further preferred LED lighting unit according to the invention comprises a) a multilayer body and b) an LED light source, the multilayer body comprises the following layers in this order: a1) a carrier layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50 wt.%, more preferably at least 75 wt.%, and even more preferably at least 90 wt.% aromatic polycarbonate, with a thickness averaged over the entire surface of the carrier layer of 0.5 to 6 mm, a2) a translucent stone layer, preferably selected from the group consisting of variegated slate, incandescent slate, limestone, sandstone and / or marble, with a thickness of ≤ 2 mm, preferably ≤ 1 mm, a3) a transparent layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50 wt.%, more preferably at least 75 wt.%, and even more preferably at least 90 wt.% aromatic polycarbonate, with a thickness averaged over the entire surface of 1 to 6 mm, which lies on the side of the stone layer a2, which represents the visible side of the multilayer body in the LED lighting unit, and wherein the LED light source is arranged on at least one side edge of the transparent layer such that the transparent layer can be used as a light guide for light emitted by the LED light source.

[0096] A particularly preferred LED lighting unit according to the invention comprises a) a multilayer body and b) a first LED light source, which is arranged on at least one side edge of the transparent layer in such a way that the transparent layer can be used as a light guide for light emitted by the LED light source, c) a second LED light source, which is arranged in such a way that it serves as backlighting for the multilayer body, the multilayer body comprises the following layers in this order: a1) a carrier layer made of a transparent or translucent thermoplastic composition, wherein the thermoplastic composition contains at least 50 wt.%, more preferably at least 75 wt.%, and even more preferably at least 90 wt.% aromatic polycarbonate, with a thickness averaged over the entire surface of the carrier layer of 0.5 to 6 mm, a2) a translucent stone layer, preferably selected from the group consisting of variegated slate, incandescent slate, limestone, sandstone and / or marble, with a thickness averaged over the entire surface of the stone layer of ≤ 2 mm, preferably ≤ 1 mm, a3) a transparent layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50 wt.%, more preferably at least 75 wt.%, and even more preferably at least 90 wt.% aromatic polycarbonate.-% aromatic polycarbonate, with an average thickness of 1 to 6 mm across the entire surface, located on the side of the stone layer a2, which represents the visible side of the multilayer body in the LED lighting unit.

[0097] The multilayer body most preferably comprises no further layers other than layers a1 to a3 and any protective layers present, in particular transparent scratch-resistant layers.

[0098] The production of the molding compounds for the layers and ultimately the layers of the multilayer body from thermoplastic compositions, starting from the components described, is carried out using conventional incorporation methods by combining, mixing, and homogenizing, with homogenization preferably taking place in the melt under the influence of shear forces. For this purpose, the aromatic polycarbonate and any other components of the polycarbonate molding compound are mixed, extruded, and granulated in the melt under standard conditions on conventional melt mixing units such as single- or multi-shaft extruders or kneaders. The additives can be metered either separately as granules or pellets via dosing scales or side feeders, or, at elevated temperatures, as a melt using metering pumps at a suitable point in the solids conveying section of the extruder or into the polymer melt.The masterbatches, in the form of granules or pellets, can also be combined with other particulate compounds to form a premix and then fed together via metering hoppers or side feeders into the solids conveying section of the extruder or into the polymer melt in the extruder. The compounding unit is, for example, a twin-screw extruder, particularly preferably a twin-screw extruder with shafts rotating in the same direction, wherein the twin-screw extruder has a length-to-diameter ratio of the screw shaft preferably of 20 to 44, more preferably of 28 to 40. Such a twin-screw extruder comprises a melting and mixing zone or a combined melting and mixing zone and optionally a degassing zone, in which an absolute pressure p of preferably at most 800 mbar, more preferably at most 500 mbar, and more preferably at most 200 mbar, is set.The average residence time of the mixture in the extruder is preferably limited to a maximum of 120 s, more preferably to a maximum of 80 s, and most preferably to a maximum of 60 s. In a preferred embodiment, the temperature of the melt of the polymer or polymer alloy at the extruder exit is between 200°C and 400°C.

[0099] After the production of the molding compounds, these can be transformed into corresponding molded parts by extrusion, hot pressing, injection compression molding, or injection molding. Injection molding or injection compression molding, particularly injection molding, is preferred for the production of the molded parts according to the invention. In the first step, a stone slab is placed in an injection mold and overmolded with a molding compound. After demolding and a further cooling period, the molding compound, which has solidified into a thermoplastic molded part, is removed from the stone slab, leaving a thin layer of stone on the molded part. In the second step, this molded part with the thin layer of stone is again placed in an injection mold, and the side with the stone layer is overmolded with another layer of molding compound. After the cooling period has elapsed, the finished multi-layered body is demolded.

[0100] Injection molding processes are known to those skilled in the art and are described, for example, in the "Handbook of Injection Molding", Friedrich Johannnaber / Walter Michaeli, Munich; Vienna: Hanser, 2001, ISBN 3-446-15632-1 or in "Instructions for the Construction of Injection Molding Tools", Menges / Michaeli / Mohren, Munich; Vienna: Hanser, 1999, ISBN 3-446-21258-2.

[0101] Injection molding here includes all injection molding processes, including multi-component injection molding and injection compression molding.

[0102] Injection compression molding processes differ from conventional injection molding processes in that the injection and / or solidification process is carried out by moving the mold plates. In the known injection compression molding process, the mold plates are already slightly opened before injection to compensate for shrinkage during subsequent solidification and to reduce the required injection pressure. Therefore, a pre-enlarged cavity is present right from the start of the injection process. The mold's plunge edges ensure sufficient sealing of the pre-enlarged cavity even with the mold plates slightly open. The plastic compound is injected into this pre-enlarged cavity and, during or after this process, compressed in the closing direction by moving the mold. The more complex injection compression molding technique is preferred, or may be used, particularly for the production of large-area, thin-walled molded parts with long flow paths.Absolutely essential. Only in this way can a reduction in the injection pressures required for large molded parts be achieved. Furthermore, stresses or distortion in the injection-molded part, which occur as a result of high injection pressures, can be avoided through injection compression molding.

[0103] The multilayer bodies can be shaped as plates or have a three-dimensionally shaped surface, i.e., a shape different from a plate, where a plate is understood to be a body in which the three pairs of opposite sides of the layers a1, a2 and a3 are plane-parallel or at least approximately plane-parallel to each other.

[0104] As previously described, the multilayer bodies can have a scratch-resistant lacquer on one or both of their outer flat surfaces, either as part of a protective layer or as a protective layer in its own right. This lacquer is preferably a polysiloxane lacquer produced using the sol-gel process. The protective layer particularly preferably also contains at least one UV absorber. The protective layer exhibits high abrasion and scratch resistance and thus fulfills, in particular, the function of a scratch-resistant coating.

[0105] Commercially available systems include AS4000, SHC5020, and AS4700 from Momentive Performance Materials. Such systems are described, for example, in US 5,041,313 A, DE 3,1213,85 A1, US 5,391,795 A, and WO 2008 / 109072 A1. The synthesis of these materials typically proceeds via the condensation of alkoxy and / or alkylalkoxysilanes under acid or base catalysis. Optionally, nanoparticles can be incorporated. Preferred solvents are alcohols such as butanol, isopropanol, methanol, ethanol, and mixtures thereof.

[0106] Several methods exist for applying scratch-resistant coatings to plastic articles. These coatings can be applied, for example, via dipping, spin coating, spraying, or flow coating, preferably via dipping or flow coating. Curing can be achieved thermally or by UV irradiation. The scratch-resistant coating can be applied directly or after preparing the substrate surface with a primer. Furthermore, scratch-resistant coatings can be applied using plasma-assisted polymerization processes, such as SiO₂ plasma. Anti-fog or anti-reflective coatings can also be produced using plasma processes. Additionally, it is possible to apply a scratch-resistant coating to the resulting molded part using certain injection molding processes, such as back-injection molding of surface-treated films.The scratch-resistant layer may contain various additives, such as UV absorbers derived from triazoles or triazines.

[0107] The protective layer can be a single-layer or multi-layer system, and thus also a combination of two or more layers. In particular, the protective layer can consist of the topcoat layer a' and the primer layer a", with the primer layer being positioned between the topcoat layer and the layer to be protected.

[0108] Scratch-resistant coatings based on polysiloxane are preferably applied by dipping or flow coating processes. Curing takes place at temperatures of 50 °C to 140 °C.

[0109] A primer containing a UV absorber is preferably used to improve the adhesion of the scratch-resistant coating to the substrate. The primer may contain further stabilizers such as HALS systems (stabilizers based on sterically hindered amines), adhesion promoters, and / or flow agents. The resin that forms the base material of the primer layer can be selected from a wide variety of materials and is described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A18, pp. 368–426, VCH, Weinheim 1991. Polyacrylates, polyurethanes, phenol-based, melamine-based, epoxy, and alkyd systems, or mixtures of these systems, can be used. The resin is usually dissolved in suitable solvents—often alcohols. Depending on the resin chosen, curing can take place at room temperature or at elevated temperatures.Temperatures between 50 °C and 140 °C are preferred – often after a large portion of the solvent has been briefly removed at room temperature. Commercially available primer systems include, for example, SHP470, SHP470-FT2050, and SHP401 from Momentive Performance Materials. Such coatings are described, for example, in US 6,350,512 B1, US 5,869,185 A, EP 1308084 A1, and WO 2006 / 108520 A1.

[0110] In a preferred embodiment, which provides particularly good weather resistance, the protective layer comprises a scratch-resistant coating based on polysiloxane, containing i. at least one UV absorber from the group of benzophenones, resorcinols, 2-(2-hydroxyphenyl)bentriazoles, hydroxyphenyl s-triazines, 2-cyanoacrylates, oxalanilides and / or a UV inhibitor from the group of sterically hindered amines (HALS), in particular based on 2,2,6,6-tetramethylpiperidine or its derivatives; ii. at least one combination of an organo-modified silane with a silica sol. The organo-modified silane is, for example, a methyltrialkoxy or dimethyldialkoxysilane; and optionally, in a further preferred embodiment, additionally a bonding agent arranged on the substrate to be coated between the scratch-resistant coating A primer layer (layer a") based on polysiloxane and acting on the substrate to be coated, containing at least one UV absorber from the group of benzophenones, resorcinols, 2-(2-hydroxyphenyl)bentriazoles, hydroxyphenyl-s-triazines, 2-cyanoacrylates, oxalanilides and / or sterically hindered amines (HALS), in particular based on 2,2,6,6-tetramethylpiperidine and its derivatives, wherein the thickness of the primer layer is 0.3 µm to 8 µm, preferably 1.1 µm to 4.0 µm.

[0111] Ideally, the protective layer should not include any further layers.

[0112] According to the invention, "derivatives" are understood to be compounds whose molecular structure has a different atom or group of atoms in place of a hydrogen atom or a functional group, or in which one or more atoms / groups of atoms have been removed. The parent compound is thus still recognizable.

[0113] The polysiloxane layer preferably contains organosilicon compounds of the formula RnSiX4-nn, and / or partial condensates thereof, wherein the R groups are the same or different and represent a linear or branched, saturated or mono- or polyunsaturated or aromatic hydrocarbon residue, the X groups are the same or different and represent hydrolyzable groups or hydroxyl groups, preferably halogen, in particular chlorine or bromine, alkoxy groups, alkyl carbonyl groups or acyloxy groups, and n is 0, 1, 2 or 3, preferably 1 or 2, most preferably 1. R preferably represents saturated, branched or unbranched alkyl residues with 1 to 20 carbon atoms and / or mono- or polyunsaturated branched or unbranched alkenyl residues with 2 to 20 carbon atoms or aromatic groups with 6 to 12 carbon atoms. The alkyl or...Alkenyl groups with up to 12, and even more preferably up to 8, carbon atoms. Methyl and / or phenyl groups are particularly preferred. X is particularly preferably an alkoxy group, and most preferably a C1 to C4 alkoxy group, for example a methoxy or ethoxy group.

[0114] The silicon compounds RnSiX4n are hydrolyzable and condensable via the X groups. An inorganic network with Si-O-Si units is formed via these hydrolytically condensable groups. Unlike the X groups, the R groups are stable against hydrolysis under typical condensation conditions.

[0115] When using the aforementioned siloxane systems, dry film thicknesses of 3 µm - 20 µm are preferred, more preferably 5 µm - 15 µm, and particularly preferably 6 µm - 12 µm. Dry film thickness here refers to the thickness of the coating after application, subsequent evaporation of the solvent, and subsequent thermal or UV curing.

[0116] Instead of primer / scratch-resistant coating combinations, single-component hybrid systems, either thermally or UV-curing, can also be used for the multi-layer bodies according to the invention.

[0117] These are described, for example, in EP 0570165 A2 or WO 2008 / 071363 A2 or DE 2804283 A. Commercially available hybrid systems are available, for example, under the names PHC 587 and PHC 587C as thermally curing coatings or UVHC 3000 and UVHC 5000 as UV-curing coatings from Momentive Performance Materials. Further commercially available UV-curing coating systems suitable according to the invention are UVT 610 and UVT 820 from Redspot.

[0118] In a particularly preferred method for manufacturing the molded parts according to the invention, the protective layer is applied via the flooding process, since it leads to coated parts with high optical quality.

[0119] The flood coating process can be carried out manually with a hose or suitable coating head, or automatically in a continuous flow using flood coating robots and, if necessary, slot nozzles.

[0120] Other possible application methods include dipping, doctor blade coating, rolling, spraying, or spin coating. Components can be coated either while suspended or stored in a suitable carrier.

[0121] For larger and / or 3D components - i.e. components with a three-dimensional surface, which therefore have a geometry that differs from that of a plate - the part to be coated is suspended or placed in a suitable carrier.

[0122] For small parts, coating can also be done manually. In this process, the liquid primer or lacquer solution to form the protective layer is poured lengthwise across the plate, starting from the top edge of the small part, while simultaneously the starting point of the lacquer on the plate is moved from left to right across the width of the plate. The lacquered plates are then suspended vertically from a clamp and allowed to dry and cure according to the respective manufacturer's instructions. Examples

[0123] The invention will be explained in more detail with reference to the following examples, without, however, being limited to them. Materials used

[0124] Transparent Makrolon® Ai from Covestro Deutschland AG: aromatic polycarbonate based on bisphenol A with an MVR of 19 cm³ / (10 min), determined at 300 °C and 1.2 kg according to DIN ISO 1133:2012-03, containing UV absorber and mold release agent. Ty, measured at a thickness of 2 mm according to ISO 13468-2:2006 (D65, 10°): 88.07%. Turbidity, determined according to ASTM D1003:2013 at a thickness of 2 mm: 0.68%.

[0125] Translucent black-tinted Makrolon®< Ai from Covestro Deutschland AG: aromatic polycarbonate based on bisphenol A with an MVR of 19 cm³ / (10 min), determined at 300 °C and 1.2 kg according to DIN ISO 1133:2012-03, containing UV absorber and mold release agent. Ty, measured at a thickness of 2 mm according to ISO 13468-2:2006 (D65, 10°): 3.84%. Turbidity, determined according to ASTM D1003:2013 at a thickness of 2 mm: 100%.

[0126] For pretreatment, the polycarbonates were dried for 4 hours at 120 °C in dry air.

[0127] Stone slabs of variegated slate, stone slabs of mica schist and stone slabs of sandstone, each with a thickness of approximately 3 mm, which were cut to the dimensions 200 mm x 150 mm. Production of the molded parts

[0128] A multi-layer molded part measuring 200 mm x 150 mm x 6 mm was produced for each of the stone slabs on a KM GX400 injection molding machine from KraussMaffei Group GmbH.

[0129] In a first step, a stone slab, pre-tempered at 115 °C for 15 minutes in a heating oven, was placed into the first half of a steel mold with internal dimensions of 200 mm x 150 mm x 6 mm. After closing the mold, the transparent polycarbonate material, melted at 305 °C, was injected onto the stone surface at a maximum specific injection pressure of approximately 2000 bar. The mold wall temperature was 100 °C on the ejector side and 90 °C on the opposite injection side. The injection time was 2.5 seconds. After a holding pressure of 15 seconds (specific holding pressure: 850 bar) and a cooling time of 35 seconds, the mold was opened and the molded part removed.

[0130] After approximately 5 minutes of cooling at room temperature, the polycarbonate sheet, which had been sprayed onto the stone surface, was peeled off the stone slab. A very thin layer of stone remained firmly attached to the polycarbonate sheet, with an average thickness of less than 2 mm across the entire surface.

[0131] This polycarbonate sheet with the thin stone layer, which together had an average thickness of slightly more than 3 mm, was pre-tempered again at 115 °C for 15 minutes in a heating oven. Simultaneously, the polycarbonate material in the injection cylinder was changed from transparent to translucent black. This sheet was then placed back into the first half of the steel mold, which had internal dimensions of 200 mm x 150 mm x 6 mm, with the stone-layered surface facing the second half of the mold. After closing the mold, the translucent black polycarbonate material, melted at 305 °C, was injected into the mold onto the transparent polycarbonate sheet with the stone surface at a maximum specific injection pressure of approximately 2000 bar. The mold wall temperature was 90 °C on the ejector side and 65 °C on the opposite injection side. The injection time was 2.2 seconds.After a holding pressure of 15 seconds (specific holding pressure: 800 bar) and a cooling time of 30 seconds, the tool was opened and the finished molded part with a total thickness of approximately 6 mm was removed.

[0132] To illuminate the molded parts, they were clamped into a light box designed to hold panels measuring 200 mm x 150 mm. This light box features an LED strip running around the perimeter of the panel for edge lighting and an RGB LED board on the back for backlighting. Edge lighting and backlighting can be operated separately or in combination. The effects described earlier were achieved using this setup.

Claims

1. LED lighting unit comprising a) a multilayer body and b) an LED light source, wherein the multilayer body comprises the following layers in this sequence: a1) a carrier layer of a thermoplastic composition, a2) a stone layer, a3) a transparent layer of a thermoplastic composition having an average thickness over the total area of 1 to 6 mm, on the face of the stone layer a2 that constitutes the visible face of the multilayer body in the LED lighting unit, and wherein the LED light source is disposed at at least one lateral edge of the transparent layer a3 such that the transparent layer a3 is utilizable as light guide for light emitted by the LED light source.

2. LED lighting unit according to Claim 1, characterized in that the composition of the carrier layer a1 and / or the composition of the transparent layer a3 is / are based on aromatic polycarbonate.

3. LED lighting unit according to Claim 1 or 2, characterized in that the stone layer a2 has a coherent grain microstructure.

4. LED lighting unit according to any of the preceding claims, characterized in that the stone layer a2, at least on the flat side facing the transparent layer a3, has a topography having maximum roughness Rz of preferably at least 0.1 µm, wherein the maximum roughness Rz is determined as defined in the description.

5. LED lighting unit according to any of the preceding claims, characterized in that the thickness of the carrier layer a1, averaged over the total area of the carrier layer, is 0.5 to 6 mm.

6. LED lighting unit according to any of the preceding claims, characterized in that the transparent layer a3 covers the stone layer a2 over very substantially its full area, and / or in that the carrier layer a1 covers the stone layer a2 over its full area or projects beyond it at at least one lateral edge.

7. LED lighting unit according to any of the preceding claims, characterized in that the LED light source is disposed such that at least some of the light emitted by the LED light source is totally reflected at the interfaces of the transparent layer a3 with the stone layer a2 and / or of the transparent layer a3 with the ambient air or any additional transparent layer of the multilayer body further to the outside.

8. LED lighting unit according to any of the preceding claims, characterized in that the multilayer body has a geometry other than that of a sheet.

9. LED lighting unit according to any of the preceding claims, characterized in that the thermoplastic composition of the carrier layer a1 is a translucent black composition.

10. LED lighting unit according to any of the preceding claims, characterized in that the LED lighting unit has a second LED light source arranged in such a way that it serves as backlighting for the multilayer body.

11. LED lighting unit according to any of the preceding claims, characterized in that the multilayer body includes at least one protective layer having a polysiloxane-based scratch-resistant coating, and / or in that the multilayer body does not have any further layers aside from optional protective layers, and / or in that the stone layer a2 is a coloured slate layer, mica shale layer, limestone layer, sandstone layer and / or marble layer.

12. LED lighting unit according to any of the preceding claims, characterized in that the proportion of aromatic polycarbonate in the thermoplastic composition of the carrier layer a1 and / or of the transparent layer a3 is at least 90% by weight.

13. LED lighting unit according to any of the preceding claims, characterized in that the LED lighting unit is an element for formation of a floor, for furniture making, a wall panel, a door panel, part of a lamp, a lighting element, a housing of domestic appliances or electrical equipment, or an element from the automotive sector.

14. LED lighting unit according to any of the preceding claims, characterized in that the LED lighting unit is an element from the automotive sector, specifically a lighting element, part of interior trim, part of a dashboard, part of an instrument panel, a decorative strip, a doorsill strip, part of an armrest or part of a centre console.