Multi-layer-based LED lighting element with a stone appearance

Abstract

A multi-layer body is described, which can be illuminated by edge lighting and optionally also by backlighting and has a stone-like appearance. In addition to the stone layer, a layer made of a thermoplastic material is provided. This structure is not only an attractive design element with a day / night design in interior building spaces and facade configurations, but can also be used in various ways in the automotive field.

Description

[0001] The present invention relates to an illuminable multi-layer body having a carrier layer composed of a thermoplastic material and a stone layer, which has a stone appearance.

[0002] In the field of interior architecture of buildings and automotive interiors, there is a desire to equip surfaces with a natural appearance. In particular, the impressions of wood and stone create a comfortable, nature-close and upscale modern atmosphere. In this regard, stone as a surface is of interest because the thickness and solidity emanating from this material imply luxury. If granite elements are selected, for example, as washbasin edgings, kitchen countertops, floor or wall coverings, they are indeed a luxury element due to the cost of the material. At the same time, due to their large self-weight, they make installation difficult. There is a need for configuration elements having a stone appearance. In order to reduce the weight of the corresponding elements, elements using multi-layer bodies instead of solid stone elements have been developed in the past, where the thickness of the stone layer is reduced and a carrier layer is provided instead for stability.

[0003] For example, a composite material is known from DE 102005038022 A1, which has a flexible carrier layer made of plastic, which is joined to a light-transmissive natural stone layer without an adhesive layer. The use of this composite material as a cladding element, in particular for wall and facade claddings, is disclosed.

[0004] German utility model DE 202006013010 U1 describes a flexible planar material having a natural stone surface, which, in addition to the stone layer, has a flexible carrier layer, wherein the planar material is provided with an adhesive layer for fixing to a substrate, since the planar material is used as a floor covering and also as a cladding element for walls, furniture, etc. to create a decorative stone surface with a solid effect.

[0005] WO 2000 / 068530 A1 also describes a multi-layer molded body having a colored carrier layer and a thin natural stone layer visible on the surface, which is notable for a specific color intensity imparted by the color of the carrier layer. The molded body is preferably flexible, wherein the grain microstructure of the natural stone layer is decomposed. The molded body has a transparent cover layer, which imparts a uniform, smooth and optionally also glossy surface to the molded body despite the decomposition of the grain microstructure of the natural stone layer. Possible uses that can be mentioned are especially wall panels for external and internal areas and automotive instrument panels.

[0006] WO 2004 / 052561 A1 describes a method for manufacturing a multi-layer body having a stone layer, wherein a polymer is applied to a stone element, then it is joined to a surface and peeled off together with a layer of stone from the stone element. A seal can be provided on the visible surface of the multi-layer body. The weight of the multi-layer body is significantly reduced compared to a solid stone slab of the same thickness. The use of the multi-layer body for floor coverings and wall panels is described.

[0007] Likewise, in both the automotive and construction fields, an important aspect of the interior configuration is the provision of light. In addition to traditional lighting fixtures (including those with design requirements), lighting elements are integrated into walls, cabinets, or floor areas in an unobtrusive manner.

[0008] Combining a stone appearance with light elements is known from the prior art. For example, WO 2009 / 110870 A1 describes veneers made of thin, still light-transmissive stone layers of 0.3 to 1.5 mm on a transparent, translucent, or opaque carrier layer composed of glass, polycarbonate, or other suitable materials, where the element can be supplied to a variety of applications, and in particular, backlighting can be mentioned.

[0009] However, there is still a need for alternative decorative or functional elements with a stone appearance that have as attractive a day / night design as possible and as low an inherent weight as possible considering the aforementioned high surface quality. Furthermore, preferably in the case of such decorative and functional elements, a high variability and personalization of the light effects should be achievable through new digital light technologies. Therefore, the aim is to provide corresponding elements.

[0010] According to the invention, this aim is achieved by an LED lighting unit that comprises

[0011] a) a multi-layer body and

[0012] b) an LED light source,

[0013] wherein the multi-layer body sequentially comprises the following layers:

[0014] a1) a carrier layer made of a thermoplastic composition,

[0015] a2) a stone layer,

[0016] a3) a transparent layer made of a thermoplastic composition with an average thickness of 1 to 6 mm over the entire surface, which is located on one side of the stone layer a2, and this side is the visible side of the multi-layer body in the LED lighting unit,

[0017] and wherein the LED light source is arranged at at least one side edge of the transparent layer a3 such that the transparent layer a3 can be used as a light conductor for the light emitted by the LED light source.

[0018] The "LED lighting unit" is understood here not only in the narrow sense as a package of mechanically connected single pieces, but also more broadly as a mere combination of single pieces that are (only) functionally connected into a unit. However, it can also be a mechanically connected combination. According to the present invention, the "LED lighting unit" is understood to mean various devices or systems having a multi-layer body that is functionally connected to an LED light source in the sense of the present invention. This can be an element for forming a floor covering, an element for furniture manufacturing, a wall panel or a door panel, a lamp component and a lighting element, the housing of a household appliance or an electrical device, or a component from the automotive field, especially a component from the field of automotive interior configuration, such as a component of the interior trim, a component of the instrument panel, a component of the instrument indicator panel, a decorative strip, a sill strip, an armrest component or a center console component.

[0019] The LED lighting unit of the present invention has an attractive day / night design. In the case where the LED is not turned on, the observer sees an attractive natural stone appearance. When the LED light source is turned on, a significantly different appearance is produced because the three-dimensional topography of the stone layer is generated by edge lighting through a transparent component, which depends on the type of stone used that additionally has a flash or mirror element. In addition, the edge lighting can also be combined with backlighting to produce further lighting effects.

[0020] The "multi-layer body" in the sense of the present invention is various structures formed by a plurality of layers stacked on top of each other, including at least layers a1, a2, and a3. It should be understood that other layers, especially scratch-resistant layers, can be provided, for example, on the outside of the multi-layer body, on one or two flat surfaces of the multi-layer body. "On the outside of the multi-layer body" here refers to the surface of the carrier layer a1 or the transparent layer a3 that is opposite to the surface on which the stone layer a2 is laid.

[0021] The multi-layer body has the shape of a plate or a geometric shape different from that of a plate. In the case of wall elements, tile elements, and elements for floor coverings, a plate is a common shape. On the contrary, an LED lighting element having a geometric shape different from that of a plate and having a three-dimensionally formed visible surface is preferably used for automotive interior applications, such as in the case of an automotive instrument panel. The three-dimensionally formed component can be directly injection-molded, for example, according to the manufacturing method described in the embodiments, from a three-dimensionally processed stone plate, or can be formed by thermoforming a plate-shaped multi-layer body.

[0022] In the sense of the present invention, "transparent" means a transmittance 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%, even more preferably at least 88%, and a haze measured at a layer thickness of 2 mm according to ASTM D1003:2013 of preferably less than 2.0%, more preferably less than 1.5%, even more preferably less than 1.0%, and particularly preferably less than 0.8%.

[0023] Due to their long lifespan, low energy consumption, and good light output, LED light sources are increasingly widely used, for example in the automotive industry, aviation, interior space lighting, facade configurations, etc. The wavelength of the light emitted by an LED depends on the semiconductor material and dopants, so LEDs can be used to produce near-monochromatic light, even in the infrared range or the UV range.

[0024] 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 LEDs that emit blue, red, and green light into a so-called RGB (red-green-blue) module (the combined light impression perceived by this module can be white), or by a light-emitting technique that converts all or part of the LED radiation into other wavelengths through, for example, a phosphor.

[0025] For example, white light can be produced from a blue-emitting LED in the visible light region by adding a single phosphor that converts a part of the radiation in the blue range into red / yellow light. Due to cost reasons and the high efficiency of blue LEDs, this form of producing white light is preferred for commercial applications.

[0026] Alternatively, white light can be produced from UV light generated by an LED with the aid of three different phosphors that emit wavelengths corresponding to an RGB module. If this technology is used, the composition preferably also has improved stability against UV radiation, i.e., is equipped with UV stability, for example.

[0027] In order to set an overall color impression different from "white" in an LED module, the above light sources can also be further modified as needed. This modification can be carried out, for example, in the following ways:

[0028] - In combination with a phosphorescent dye or

[0029] - In combination with other light sources having other emission characteristics.

[0030] According to the present invention, in principle, all of the LED / LED technologies described above can be used alone or together.

[0031] In the context of the present invention, a "LED light source" is understood to mean a light source that emits light with radiation characteristics, where more than 70% of the intensity emitted in the range from 200 nm to 3000 nm lies within the spectral visible range. In the context of the present invention, the visible range is defined as the wavelength range from 360 nm to 780 nm. Particularly preferably, less than 5% of the intensity lies within the range < 360 nm. Considering the range from 360 nm to 500 nm, the LED light in the context of the present invention has a peak wavelength in terms of its intensity - i.e., the wavelength of the maximum intensity - of from 360 nm to 460 nm, more preferably from 400 nm to 460 nm, particularly preferably from 430 nm to 460 nm, or particularly preferably from 400 nm to 405 nm. To determine the peak wavelength, the radiation equivalent parameter, such as the radiant flux, is measured in a spectrally resolved manner and plotted in a Cartesian coordinate system. The radiation equivalent parameter is plotted on the y-axis and the wavelength on the x-axis. The absolute maximum of this curve is the "peak wavelength" (defined according to DIN 5031-1 (1982)). The term "from... to..." includes the stated limits here. Here, the "LED light" preferably has a narrow emission width with a full width at half maximum of at most 60 nm, more preferably at most 45 nm, still more preferably at most 30 nm, where monochromatic light is particularly preferred. Here, the full width at half maximum is the full width of the emission peak at half the height of the intensity.

[0032] "Serving as a light conductor" means that at least a part of the light emitted by the LED light source is transmitted via total internal reflection through the transparent layer a3. Preferably, at least a part of the light emitted by the LED light source is totally reflected at the interface between the transparent layer a3 and the stone layer a2 and / or at the interface between the transparent layer a3 and the ambient air or any other transparent layer optionally located more externally of the multi-layer body. "Interface" here means the surface at which and / or through which two or more layers of the multi-layer body or the ambient air are adjacent directly to each other. The interface is formed by a material transition.

[0033] Edge lighting, i.e., edge lighting is a relatively energy-efficient possible way to produce an attractive lighting effect because relatively few LEDs are required.

[0034] It should be understood that in addition to the LED light source that uses the transparent layer a3 as a light conductor, i.e., for "edge lighting" applications, light can also enter the multi-layer body from the back of the multi-layer body, i.e., from the side of the carrier layer, such that conventional backlighting occurs. In the case of backlighting, the LED light source is located behind the carrier layer such that the light transilluminates the carrier layer, the stone layer, and the transparent layer.

[0035] The fact that the transparent layer a3 can be used as a light conductor for the light emitted by the LED light source does not mean that edge illumination must also be carried out continuously every day during operation. On the contrary, this is a technically predefined option that the user can choose. Edge illumination can of course also be switched off, as is usually the case especially in the case of daylight. It should be understood that the light source can also be controlled accordingly by using sensor technology or time-switching technology. If additional backlighting is provided, it can be selected as an alternative to edge illumination or can be switched on simultaneously therewith. The LED lighting unit can also be used when both the backlighting and the edge illumination are switched off.

[0036] The carrier layer a1 is a layer made of a thermoplastic composition. "Made of" means that the carrier layer consists of this composition.

[0037] The thermoplastic composition is based on a thermoplastic polymer, which is preferably contained in the thermoplastic composition in a proportion of at least 50% by weight, more preferably at least 60% by weight, even more preferably at least 75% by weight, more preferably at least 85% by weight, and most preferably at least 90% by weight.

[0038] In principle, the carrier layer can be transparent, translucent or opaque, where "transparent" is defined as above. In the context of the present invention, "translucent" should be understood as having a transmittance 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%, and particularly preferably < 20% and > 2.9%, and a haze of preferably > 95%, more preferably > 99% measured at a layer thickness of 2 mm according to ASTM D1003:2013. An "opaque" composition in the context of the present invention is those having a light transmittance Ty of less than 2.5%, preferably less than 1.0%, which is determined at a layer thickness of 2 mm according to DIN ISO 13468-2:2006 (D65, 10°).

[0039] The composition of the carrier layer can in particular be black-dyed. According to the present invention, a black composition is understood to mean a composition described by 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, which is determined at a thickness of 2 mm according to ISO 13468-2:2006 (D65, 10°).

[0040] Suitable thermoplastic polymers are, for example, aromatic polycarbonates (PC), polyester carbonates, polystyrene (PS), styrene copolymers, polyolefins such as polyethylene (PE) or polypropylene (PP), aromatic polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), PET-cyclohexanedimethanol copolymers (PETG), polyethylene naphthalate (PEN), polymethyl methacrylate or copolymethyl methacrylate, for example polymethyl methacrylate (PMMA), polyimides (e.g. PMMI), polyethersulfone, thermoplastic polyurethanes, cycloolefin polymers or copolymers (COP or COC) or mixtures thereof, preferably aromatic polycarbonates, aromatic polyesters, cycloolefin polymers, including olefin copolymers, or polymethyl methacrylate, or mixtures thereof. If a mixture of different polymers is used, preference is given to a mixture of an aromatic polycarbonate with PMMA or a polyester.

[0041] More preferably, the polymer comprised in the thermoplastic composition forming the carrier layer is an aromatic polycarbonate, either alone or in the form of a mixture with another polymer, in particular a polyester.

[0042] More preferably, the thermoplastic composition of the carrier layer comprises only an aromatic polycarbonate as the thermoplastic polymer. Aromatic polycarbonates in the sense of the present invention are all known aromatic polycarbonates. This includes homopolycarbonates and copolycarbonates. If only "polycarbonate" is mentioned anywhere in the context of the present invention, it particularly refers to an aromatic polycarbonate. The aromatic polycarbonate in the thermoplastic composition in one of the layers of the multilayer body is a specific aromatic polycarbonate or a mixture of different aromatic polycarbonates, i.e. for example two different aromatic copolycarbonates, or two different aromatic homopolycarbonates, or one aromatic homopolycarbonate and one aromatic copolycarbonate.

[0043] Up to 80 mol%, preferably 20 mol% to 50 mol%, of a part of the carbonate groups in the polycarbonate used according to the invention can be replaced by aromatic dicarboxylate groups. Such a polycarbonate in which not only acid groups from carbonic acid but also acid groups from aromatic dicarboxylic acids are incorporated into the molecular chain is called an aromatic polyester carbonate. In the context of the present invention, they are likewise covered by the general term thermoplastic aromatic polycarbonate.

[0044] Polycarbonates are prepared in a known manner from dihydroxyaryl compounds, carbonic acid derivatives and optionally chain terminators and branching agents.

[0045] For about the last 40 years, details of the preparation of polycarbonates have been listed in many patent documents. For example, reference may be made here to Schnell, "Chemistry and Physics of Polycarbonates", Polymer Reviews, Volume 9, Interscience Publishers, New York, London, Sydney 1964, reference to D. Freitag, U. Grigo, P. R. Müller, H. Nouvertné, BAYER AG, "Polycarbonates", Encyclopedia of Polymer Science and Engineering, Volume 11, Second Edition, 1988, pages 648 - 718 and finally reference to Dres. U. Grigo, K. Kirchner and P. R. Müller "Polycarbonate", Becker / Braun, Kunststoff-Handbuch, Volume 3 / 1, Polycarbonate, Polyacetale, Polyester, Celluloseester, Carl Hanser Verlag München, Wien 1992, pages 117 - 299.

[0046] Dihydroxyaryl compounds suitable for the preparation of polycarbonates are, for example, hydroquinone, resorcinol, dihydroxybiphenyl, 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, benzopyrrolidones derived from isatin or phenolphthalein derivatives and their compounds alkylated on the ring, arylated on the ring and halogenated on the ring.

[0047] Preferred dihydroxyaryl compounds are 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 1,1-bis(4-hydroxyphenyl)phenyl ethane, 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) and bisphenols of the following formulas (I) to (III)

[0048]

[0049] wherein each R' represents a C1 to C4 alkyl group, an aralkyl group or an aryl group, preferably a methyl group or a phenyl group, most preferably a methyl group.

[0050] Particularly preferred dihydroxyaryl compounds are 4,4'-dihydroxybiphenyl, 1,1-bis(4-hydroxyphenyl)phenyl ethane, 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 the formulas (I), (II) and / or (III).

[0051] These and other suitable dihydroxyaryl compounds are described, for example, in US 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, German Offenlegungsschriften 1 570 703 A, 2 063 050 A, 2 036 052 A, 2 211 956 A and 3 832 396 A, French Patent Document 1 561 518 A1, the monograph "H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964, pages 28 et seq.; pages 102 et seq." and "D.G. Legrand, J.T.Bendler, Handbook of Polycarbonate Science and Technology, Marcel Dekker New York 2000, pages 72 et seq.".

[0052] In the case of homopolycarbonates, only one dihydroxyaryl compound is used; in the case of copolycarbonates, a plurality of dihydroxyaryl compounds are used.

[0053] Examples of suitable carbonic acid derivatives are phosgene or diphenyl carbonate.

[0054] Suitable chain terminators which can be used for the preparation of polycarbonates are both monophenols and monocarboxylic acids. Suitable monophenols are, for example, phenol itself, alkylphenols such as cresol, p-tert-butylphenol, cumylphenol, p-octylphenol, p-isooctylphenol, p-nonylphenol and p-isononylphenol, halogenated phenols such as p-chlorophenol, 2,4-dichlorophenol, p-bromophenol and 2,4,6-tribromophenol, 2,4,6-triiodophenol, p-iodophenol and mixtures thereof.

[0055] Preferred chain terminators are phenols which are mono- or polysubstituted by C1 to C 30 alkyl (linear or branched, preferably unsubstituted) or mono- or polysubstituted by tert-butyl. Particularly preferred chain terminators are phenol, cumylphenol and / or p-tert-butylphenol.

[0056] In addition, suitable monocarboxylic acids are benzoic acid, alkylbenzoic acids and halogenated benzoic acids.

[0057] Based on the number of moles of the dihydroxyaryl compound used in each case, the amount of chain terminator to be used is preferably from 0.1 to 5 mol%. The chain terminator can be added before, during or after the reaction with the carbonic acid derivative.

[0058] Suitable branching agents are trifunctional or more than trifunctional compounds known in polycarbonate chemistry, especially those having three or more phenolic OH groups.

[0059] Suitable branching agents are, for example, phloroglucinol, 4,6-dimethyl-2,4,6-tris(4-hydroxyphenyl)hept-2-ene, 4,6-dimethyl-2,4,6-tris(4-hydroxyphenyl)heptane, 1,3,5-tris(4-hydroxyphenyl)benzene, 1,1,1-tris(4-hydroxyphenyl)ethane, tris(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-methylphenol, 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane, hexakis(4-(4-hydroxyphenylisopropyl)phenyl)terephthalate, tetrakis(4-hydroxyphenyl)methane, tetrakis(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.

[0060] The amount of branching agent used optionally is preferably from 0.05 mol% to 2.00 mol%, again based on the number of moles of the dihydroxyaryl compound used in each case.

[0061] The branching agent can be pre-loaded together with the dihydroxyaryl compound and the chain terminator in the alkaline aqueous phase, or added in dissolved form in an organic solvent before phosgenation. In the case of the transesterification process, the branching agent is used together with the dihydroxyaryl compound. The aromatic polycarbonate comprised in the composition of the invention is preferably prepared by the interfacial process.

[0062] It is preferred to use a linear polycarbonate.

[0063] The aromatic polycarbonate of the invention preferably has a weight-average molecular weight M of from 15,000 to 25,000 g / mol, preferably from 15,000 to 24,000 g / mol, more preferably from 16,000 to 23,500 g / mol, particularly preferably from 18,000 to 22,500 g / mol wThese values apply to measurements by gel permeation chromatography, where dichloromethane is used as the eluent and calibrated with linear polycarbonate of known molar mass distribution (made from bisphenol A and phosgene) from PSS Polymer Standards Service GmbH, Germany, according to method 2301 - 0257502 - 09D (German version 2009) from Currenta GmbH & Co. OHG, Leverkusen. The eluent used for calibration is also dichloromethane. Column combination of crosslinked styrene - divinylbenzene resin. Analytical column diameter: 7.5 mm; length: 300 mm. Particle size of column material: 3 µm to 20 µm. Solution concentration: 0.2 wt%. Flow rate: 1.0 ml / min, solution temperature: 30 °C. Detection is carried out using a refractive index (RI) detector.

[0064] 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 17 cm 3 / (10 min), more preferably 18 to 65 cm 3 / (10 min).

[0065] Said M W and MVR are based on all the aromatic polycarbonates contained in the composition.

[0066] 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.

[0067] It should be understood that the thermoplastic composition may contain other components. In principle, these can be various different components as contained in thermoplastic compositions. In principle, various thermoplastic compositions can be considered, as long as the viscosity of the molding compound does not increase so severely as to prevent sufficient wetting of the stone surface and sufficient penetration of cracks and pores in the stone.

[0068] In the case of a thermoplastic composition based on an aromatic polycarbonate, it generally contains 0 wt% to 5 wt%, preferably 0.05 wt% to 3 wt%, and further preferably 0.1 wt% to 1 wt% of additives. Here, as elsewhere, unless otherwise stated, the wt% data are based on the respective entire composition.

[0069] Conventional polymer additives that can be included 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, München. Such other additives are, for example, release agents, antistatic agents, fillers, antioxidants, flame retardants, drip suppressants, heat stabilizers, flow improvers, optical brighteners, colorants, in particular pigments, such as white pigments, light scatterers, UV absorbers and / or IR absorbers.

[0070] Preferably, only one or more release agents, UV absorbers, colorants (including carbon black), scattering particles and / or one or more heat stabilizers are included as other additives in the carrier layer composition.

[0071] Suitable heat stabilizers are selected from phosphates, phosphites, phosphonites and phosphines. Examples are triphenyl phosphite, diphenyl alkyl phosphite, phenyl dialkyl phosphite, tris(nonylphenyl) phosphite, trilauryl phosphite, tristearyl phosphite, pentaerythritol distearyl diphosphite, tris(2,4-di-tert-butylphenyl) phosphite (Irgafos® 168), pentaerythritol diisodecyl diphosphite, pentaerythritol bis(2,4-di-tert-butylphenyl) diphosphite, pentaerythritol bis(2,6-di-tert-butyl-4-methylphenyl) diphosphite, pentaerythritol bis(2,4-dicumylphenyl) diphosphite, pentaerythritol bis(2,6-di-tert-butyl-4-methylphenyl) diphosphite, pentaerythritol diisodecoxydiphosphite, pentaerythritol bis(2,4-di-tert-butyl-6-methylphenyl) diphosphite, pentaerythritol bis(2,4,6-tri-tert-butylphenyl) diphosphite, sorbitol tris(stearyl) triphosphite, 4,4'-biphenyldiphosphonic acid tetra(2,4-di-tert-butylphenyl) ester, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g]-1,3,2-dioxaphosphocine, 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-dibenzo[d,g]-1,3,2-dioxaphosphocine, 2,2',2''-nitrilo[tris(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl) triethyl phosphite], 2-ethylhexyl (3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl) phosphite, pentaerythritol bis(2,6-di-tert-butyl-4-methylphenyl) diphosphite (PEP-36), 5-butyl-5-ethyl-2-(2,4,6-tri-tert-butylphenoxy)-1,3,2-dioxaphospholane, triphenyl phosphine (TPP), trialkylphenyl phosphine, bis(diphenylphosphino)ethane or trinaphthyl phosphine. Triphenyl phosphine (TPP), Irgafos® 168 (tris(2,4-di-tert-butylphenyl) phosphite), PEP-36 (pentaerythritol bis(2,6-di-tert-butyl-4-methylphenyl) diphosphite) and tris(nonylphenyl) phosphite or mixtures thereof are particularly preferably used.

[0072] Phosphate stabilizers are, for example, phosphates of the formula (IV) or mixtures of these phosphates

[0073]

[0074] wherein R1 independently of one another represent branched alkyl and / or optionally substituted alkyl, where the alkyl is preferably C1- to C 18-Alkyl, more preferably C1- to C8-alkyl. If a phosphate stabilizer is included, it is more preferably tris(2-ethylhexyl) phosphate (triisooctyl phosphate).

[0075] The aryl group is preferably substituted with C1- to C8-alkyl, branched C1- to C8-alkyl or cumyl, where the substituents may be the same or different, but are preferably the same substituents. Preferably, the aryl group is substituted at the 2- and 4-positions or the 2-, 4- and 6-positions. Very particularly preferably, tert-butyl substituents are present at these positions.

[0076] More preferably, all R1 are the same.

[0077] In addition, phenolic antioxidants can be used, such as alkylated monophenols, alkylated thioalkylphenols, hydroquinones and alkylated hydroquinones. 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-(octadecyloxycarbonylethyl)phenol) are preferably used. Irganox 1076® (2,6-di-tert-butyl-4-(octadecyloxycarbonylethyl)phenol) is particularly preferably used.

[0078] In a particular embodiment, the phosphine compound of the invention is used together with a phosphite or a phenolic antioxidant or a mixture of the two compounds mentioned later.

[0079] 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 a phenolic antioxidant and a phosphite, preferably consisting of a mixture of Irganox® 1076 or Irganox® 1010 and Irgafos® 168 or PEP-36.

[0080] In another preferred embodiment, the stabilizer system consists of a phosphine, a phosphite and a phenolic antioxidant, such as triphenylphosphine, Irganox® 1076 and Irgafos® 168.

[0081] Suitable release agents are, for example, esters or partial esters of mono- to hexavalent alcohols, especially esters or partial esters of glycerol, pentaerythritol or Guerbet alcohols. Monoalcohols are, for example, stearyl alcohol, palmityl alcohol and Guerbet alcohols. Diols are, for example, ethylene glycol; triols are, for example, glycerol; tetrols are, for example, pentaerythritol and erythritol; pentols are, for example, arabitol, ribitol and xylitol; hexols are, for example, mannitol, glucitol (sorbitol) and hexahydroxyhexane.

[0082] The esters are preferably from saturated, aliphatic C10 - to C 36 - monocarboxylic acids and optionally hydroxy monocarboxylic acids, preferably comprising saturated, aliphatic C 14 - to C 32 - mono - esters, di - esters, tri - esters, tetra - esters, penta - esters and hexa - esters of monocarboxylic acids and optionally hydroxy monocarboxylic acids or mixtures thereof, in particular statistical mixtures.

[0083] Commercially available fatty acid esters, in particular fatty acid esters of pentaerythritol and glycerol, may contain < 60% of different partial esters due to their preparation.

[0084] Saturated, aliphatic monocarboxylic acids having 10 to 36 carbon atoms are, for example, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, hydroxystearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid and montanic acid. Particularly suitable release agents as component f) of the composition according to the invention are, for example, pentaerythritol tetrastearate (PETS) or glycerol monostearate (GMS). In a particularly preferred embodiment of the invention, the entire composition contains a release agent in a proportion of 0 ppm to 3000 ppm, preferably 100 ppm to 1000 ppm, more preferably 150 ppm to 500 ppm, based on the mass of the entire composition.

[0085] Preferred UV absorbers are compounds having as low a transmittance as possible below 400 nm and as high a transmittance as possible above 400 nm. Such compounds and their preparation are known from the literature and are described, for example, in EP - A 0 839623, WO - A 96 / 15102 and EP - A 0 500 496. Particularly suitable UV absorbers for the compositions according to the invention are benzotriazoles, triazines, benzophenones and / or arylated cyanoacrylates.

[0086] Very particularly suitable UV absorbers are hydroxybenzotriazoles, such as 2 - (3',5' - bis(1,1 - dimethylbenzyl) - 2' - hydroxyphenyl)benzotriazole (Tinuvin ® 234, Ciba Spezialitätenchemie, Basel), 2 - (2' - hydroxy - 5' - (tert - octyl)phenyl)benzotriazole (Tinuvin ® 329, Ciba Spezialitätenchemie, Basel), 2 - (2' - hydroxy - 3' - (2 - butyl) - 5' - (tert - butyl)phenyl)benzotriazole (Tinuvin ® 350, Ciba Spezialitätenchemie, Basel), bis(3 - (2H - benzotriazolyl) - 2 - hydroxy - 5 - tert - octyl)methane (Tinuvin ®360, Ciba Spezialitätenchemie, Basel), (2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(hexyloxy)phenol (Tinuvin ® 1577, Ciba Spezialitätenchemie, Basel) and benzophenone 2,4-dihydroxybenzophenone (Chimasorb ® 22, Ciba Spezialitätenchemie, Basel) and 2-hydroxy-4-(octyloxy)benzophenone (Chimassorb ® 81, Ciba, Basel), 2-cyano-3,3-diphenyl-2-acrylate 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-bis(4-phenyl)phenyl-1,3,5-triazine (CGX UVA 006, Ciba Spezialitätenchemie, Basel) or 2,2'-(1,4-phenylenedimethylene)bis(tetraethyl malonate) (Hostavin ® B-Cap, Clariant AG).

[0087] Highly preferred UV absorbers are, for example, Tinuvin ® 360, Tinuvin ® 350, Tinuvin ® 329, Hostavin ® B-CAP, more preferably TIN 329 and Hostavin ® B-Cap.

[0088] Mixtures of these UV absorbers can also be used.

[0089] There is no particular limitation on the amount of the UV absorber contained in the composition. In a particular embodiment of the present invention, the amount of the UV absorber contained in the composition is 0 ppm to 6000 ppm, preferably 500 ppm to 5000 ppm, more preferably 1000 ppm to 2000 ppm, based on the weight of the entire composition.

[0090] The anti-dripping agent is preferably a fluorine-containing anti-dripping agent, especially polytetrafluoroethylene.

[0091] However, if in addition to edge illumination of the multilayer body, backlighting is also provided, the carrier layer should be configured such that a sufficient amount of light still passes through it. In this case, the selected carrier layer is transparent or at least translucent. In this case, the stone layer should also be chosen thin enough in each case so that it still transmits light to the desired extent.

[0092] The carrier layer is preferably dyed. In this case, for the respective thermoplastic material, common colorants and pigments can be used, in particular white pigments. In "night design", the color impression of the multilayer body is in particular determined by the color of the dyed carrier layer at this time, especially when using white LED lights. A colored night design, for example red, can alternatively be achieved by using colored LED light, in particular colored LED light from RGB LEDs, instead of a white light-emitting LED light source - cold white or warm white.

[0093] The thickness of the carrier layer can be freely selected according to the respective desired application. Generally, the thickness of the carrier layer is chosen such that the carrier layer imparts sufficient stability to the multilayer body, but without using more material than necessary, since this not only results in unnecessary costs but also unnecessarily increases the weight of the component. Especially in the case of automotive interior elements, it is important to achieve the smallest possible weight for functional components. Therefore, preferably, the thickness is 0.5 to 6 mm, more preferably 1.0 to 5 mm, and even more preferably 1.5 to 4 mm. This thickness is averaged over the entire surface of the carrier layer made of thermoplastic material. The deviation of the thickness at individual points in this layer from the thickness averaged over the entire surface is preferably at most ±10%, more preferably at most ±5%. Since the stone layer usually has a slightly irregular surface and the material enters the gaps here, there are minor deviations from the average value at many points.

[0094] The carrier layer preferably covers the entire surface of the stone layer or projects beyond the stone layer at at least one side edge.

[0095] The stone layer a2 is a layer made of a metamorphic rock layer or a sedimentary rock. There are a plurality of relatively discrete layers here, which can be peeled off from natural stone as thin layers. Suitable stones are, for example, claystone or schist clay with a schistose structure, limestone, sandstone, mudstone, clay schist, quartzite, phyllite, mica schist, chlorite schist, gneiss, talc schist, blue or glaucophane schist, colored schist, epidote-chlorite schist, epidote-amphibolite, amphibolite, restite migmatite, breccia migmatite, calcareous schist, mylonite, pelitic rock, migmatite, marble, serpentine, eclogite, schist, contact metamorphic rock (Fruchtschiefer) or granulite. The stone layer preferably contains colored schist, mica schist, limestone, sandstone or marble; it is further preferably composed of one of these rocks. In principle, the stone layer can be composed of different stone elements and is, for example, a mosaic of one or more stone types. However, the stone layer is preferably composed of one stone type and is processed in one piece.

[0096] The thickness of the stone layer is ≤ 2 mm, preferably ≤ 1 mm, further preferably ≤ 0.5 mm, particularly preferably ≤ 0.3 mm, where this is the average thickness over the entire flat surface of the stone layer. The "flat surface" is the side of the stone layer facing the visible surface in the multi-layer body, i.e., the side that is intended to present the visual appearance of the multi-layer body, and the side opposite to this side.

[0097] As an alternative to this, it is also possible that the average thickness of the stone layer over the entire surface of the stone layer is > 2 mm. For example, this is desirable when the lighting unit is not equipped with backlighting and thus no light has to pass through the stone layer for illumination.

[0098] The stone layer preferably has a coherent grain microstructure.

[0099] Further preferably, the stone layer has a topography with a maximum roughness Rz of preferably at least 0.1 μm, more preferably at least 0.5 μm, further preferably 0.5 to 10000 μm, more preferably 1.0 to 5000 μm at least on the flat surface facing the transparent layer. The maximum roughness Rz is defined here by the absolute vertical distance between the maximum profile peak height and the maximum profile valley depth. Here, the measuring distance is preferably at least 2 cm. These values of the maximum roughness Rz are thus advantageous because, in the case of incidence from the side through one or more side edges, this topography is optically highlighted by projection shadows, light refraction, etc. on the rough stone surface, and the three-dimensional impression perceived by the eye is enhanced.

[0100] The transparent layer a3 is likewise a layer made of a thermoplastic composition. In principle, what has been described regarding the carrier layer, including the preferred embodiments, applies here, with the limitation that the components of the thermoplastic composition should be selected such that a composition that is transparent in the sense of the present invention is obtained. Preferably, only one or more release agents, UV absorbers, and / or one or more heat stabilizers are included as other additives in the composition of the transparent layer.

[0101] The transparent layer must have a sufficient but not too thick thickness so that the multilayer body can be edge-illuminated through this layer. At the same time, it is interesting to keep the thickness of the transparent layer a3 as small as possible so as not to unnecessarily increase the weight of the LED lighting unit. Therefore, the thickness is 1 to 6 mm, more preferably 2 to 5 mm, even more preferably 2.5 to 4 mm, where the thickness is averaged over the entire surface of the transparent layer. The deviation of the thickness at each individual point of the transparent layer from the thickness averaged over the entire surface is preferably at most ±10%.

[0102] To ensure sufficient flowability of the thermoplastic composition and thus good processability, the MVR value of the composition (measured according to ISO 1133:2012-03 at 300 °C and 1.2 kg) should preferably be 14 cm 3 / (10 min) to 80 cm 3 / (10 min), further preferably 20 cm 3 / (10 min) to 80 cm 3 / (10 min), even further preferably 30 cm 3 / (10 min) to 80 cm 3 / (10 min), particularly preferably 32 cm 3 / (10 min) to 75 cm 3 / (10 min).

[0103] For good mechanical stability, the notched impact toughness of the thermoplastic composition (measured according to ISO 179 / 1eA:2010 at room temperature on specimens with a thickness of 3 mm) is preferably at least 40 kJ / m 2 , further preferably 50 kJ / m 2 to 130 kJ / m 2 , even more preferably 55 kJ / m 2 to 120 kJ / m 2 , particularly preferably 55 kJ / m 2 to 80 kJ / m 2 .

[0104] The total thickness of the layers of the multilayer body of the lighting unit of the present invention, namely the carrier layer a1, the stone layer a2, and the transparent layer a3, is preferably 1.5 to 12 mm, more preferably 3 to 10 mm, and still more preferably 4 to 8 mm.

[0105] Preferably, the transparent layer covers substantially the entire surface of the stone layer, especially at least 90%.

[0106] The LED lighting unit preferably according to the present invention comprises

[0107] a) a multilayer body and

[0108] b) an LED light source,

[0109] wherein the multilayer body sequentially comprises the following layers:

[0110] a1) a carrier layer made of a thermoplastic composition, wherein the thermoplastic composition is based on an aromatic polycarbonate,

[0111] a2) a stone layer,

[0112] a3) a transparent layer made of a thermoplastic composition based on an aromatic polycarbonate with an average thickness of 1 to 6 mm on the entire surface, which is located on one surface of the stone layer a2, and this surface is the visible surface of the multilayer body in the LED lighting unit,

[0113] and

[0114] wherein the LED light source is arranged at at least one side edge of the transparent layer such that the transparent layer can be used as a light conductor for the light emitted by the LED light source.

[0115] The LED lighting unit further preferably according to the present invention comprises

[0116] a) a multilayer body and

[0117] b) an LED light source,

[0118] wherein the multilayer body sequentially comprises the following layers:

[0119] a1) a carrier layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50% by weight, more preferably at least 75% by weight, and even more preferably at least 90% by weight of an aromatic polycarbonate, and the average thickness of the carrier layer on the entire surface of the carrier layer is 0.5 to 6 mm,

[0120] a2) a stone layer,

[0121] a3) A transparent layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50% by weight, more preferably at least 75% by weight, and even more preferably at least 90% by weight of an aromatic polycarbonate, and has an average thickness of 1 to 6 mm over the entire surface, and is located on one side of the stone layer a2, which is the visible surface of the multi-layer body in the LED lighting unit.

[0122] and

[0123] wherein the LED light source is arranged at at least one side edge of the transparent layer such that the transparent layer can be used as a light conductor for the light emitted by the LED light source.

[0124] An even further preferred LED lighting unit according to the present invention comprises

[0125] a) A multi-layer body and

[0126] b) An LED light source,

[0127] wherein the multi-layer body sequentially comprises the following layers:

[0128] a1) A carrier layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50% by weight, more preferably at least 75% by weight, and even more preferably at least 90% by weight of an aromatic polycarbonate, and the average thickness of the carrier layer over the entire surface of the carrier layer is 0.5 to 6 mm.

[0129] a2) A light-transmitting stone layer, which is preferably selected from colored schist, mica schist, limestone, sandstone, and / or marble, and has a thickness of ≤2 mm, preferably ≤1 mm.

[0130] a3) A transparent layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50% by weight, more preferably at least 75% by weight, and even more preferably at least 90% by weight of an aromatic polycarbonate, and has an average thickness of 1 to 6 mm over the entire surface, and is located on one side of the stone layer a2, which is the visible surface of the multi-layer body in the LED lighting unit.

[0131] and

[0132] wherein the LED light source is arranged at at least one side edge of the transparent layer such that the transparent layer can be used as a light conductor for the light emitted by the LED light source.

[0133] A particularly preferred LED lighting unit according to the present invention comprises

[0134] a) A multi-layer body and

[0135] b) A first LED light source, which is arranged at at least one side edge of the transparent layer such that the transparent layer can be used as a light conductor for the light emitted by the LED light source.

[0136] c) A second LED light source arranged to be used as backlighting for the multilayer body,

[0137] wherein the multilayer body sequentially comprises the following layers:

[0138] a1) A carrier layer made of a transparent or translucent thermoplastic composition, wherein the thermoplastic composition contains at least 50% by weight, more preferably at least 75% by weight, even more preferably at least 90% by weight of an aromatic polycarbonate, and the average thickness of the carrier layer over the entire surface of the carrier layer is 0.5 to 6 mm,

[0139] a2) A light-transmitting stone layer, preferably selected from colored schist, mica schist, limestone, sandstone and / or marble, and having an average thickness over the entire surface of the stone layer of ≤2 mm, preferably ≤1 mm,

[0140] a3) A transparent layer made of a thermoplastic composition, wherein the thermoplastic composition contains at least 50% by weight, more preferably at least 75% by weight, even more preferably at least 90% by weight of an aromatic polycarbonate, and having an average thickness over the entire surface of 1 to 6 mm, located on one side of the stone layer a2, which side is the visible surface of the multilayer body in the LED lighting unit.

[0141] Most preferably, the multilayer body does not contain other layers except for layers a1 to a3 and an optionally present protective layer, in particular a transparent scratch-resistant layer.

[0142] The preparation of the molding compound for the layer and the layer of the multi-layer body finally made of the thermoplastic composition starting from the said components is carried out by means of conventional incorporation methods by combining, mixing and homogenizing, wherein in particular the homogenization preferably takes place in the melt by the action of shear forces. For this purpose, the aromatic polycarbonate and the optional other components of the polycarbonate molding compound are mixed, extruded and granulated in a conventional melt mixing device, such as in a single-screw or multi-screw extruder or in a kneader, in the melt under conventional conditions. The additives can be metered into the solid conveying zone of the extruder or into the polymer melt at a suitable location either individually as pellets or granules by means of a dosing balance or a side-feed device or as a melt at an elevated temperature by means of a metering pump. The masterbatch in the form of pellets or granules can also be combined with other particulate compounds to produce a premix, which is then fed together through a metering hopper or a side-feed device into the solid conveying zone of the extruder or into the polymer melt in the extruder. The compounding device is, for example, a twin-screw extruder, more preferably a twin-screw extruder with co-rotating screws, wherein the screw length / diameter ratio of the twin-screw extruder is preferably from 20 to 44, more preferably from 28 to 40. Such a twin-screw extruder comprises a melting zone and a mixing zone or a combined melting and mixing zone and optionally a degassing zone, wherein the absolute pressure p is set to preferably at most 800 mbar, more preferably at most 500 mbar, more preferably at most 200 mbar. The average residence time of the mixture composition in the extruder is preferably limited to at most 120 seconds, more preferably at most 80 seconds, more preferably at most 60 seconds. In a preferred embodiment, the melt temperature of the polymer or polymer alloy at the extruder outlet is from 200 °C to 400 °C.

[0143] After the molding compound has been prepared, it can be converted into the corresponding molded parts by extrusion, hot pressing, injection compression molding or injection molding. For the preparation of the molded parts according to the invention, injection molding or injection compression molding is preferred here, especially injection molding. Here, in a first step, the stone plate is inserted into the injection molding mold and overmolded with the molding compound. After the demolding and further cooling time, the molding compound solidified into a thermoplastic molded part is peeled off the stone plate, leaving a thin stone layer on the molded part. In a second step, this molded part with the thin stone layer is reinserted into the injection molding mold and the face with the stone layer is overmolded with another molding compound. After the cooling time has elapsed, the finished multi-layer body is demolded.

[0144] The injection molding method is known to those skilled in the art and is described, for example, in "Handbuch Spritzgießen", Friedrich Johannnaber / Walter Michaeli, München: Wien: Hanser, 2001, ISBN 3-446-15632-1 or "Anleitung zum Bau von Spritzgießwerkzeugen", Menges / Michaeli / Mohren, München: Wien: Hanser, 1999, ISBN 3-446-21258-2.

[0145] Herein, injection molding includes all injection molding methods, including multi-component injection molding and injection compression molding.

[0146] The injection compression molding method differs from the conventional injection molding method in that the injection and / or solidification process is carried out with the movement of the platen. In the known injection compression molding method, the platen is slightly opened before the injection process to compensate for the shrinkage occurring during subsequent solidification and to reduce the required injection pressure. Thus, a pre-expanded cavity already exists at the beginning of the injection process. The flashing edges (Tauchkanten) of the mold ensure that the pre-expanded cavity remains sufficiently sealed even with the platen slightly opened. The plastic material is injected into this pre-expanded cavity and is pressed in the closing direction during or with the operation of the mold. In particular, when manufacturing large-area and thin-walled molded parts with long flow paths, more complex injection compression molding techniques are preferred or optionally mandatory. Only in this way can the injection pressure required for large molded parts be reduced. In addition, stress or warping in the injection molded parts due to high injection pressure can be avoided by injection compression molding.

[0147] The multilayer body can be formed as a plate or can have a three-dimensional forming surface, i.e., a shape different from that of the plate, where the plate is understood to be an object in which, for the three pairs of opposite surfaces of layers a1, a2, and a3 - relative to each other and all together - they are parallel or at least almost parallel to each other.

[0148] As described above, the multilayer body can have a scratch-resistant paint on one or both of its outer flat surfaces as part of or as the protective layer. This is preferably a polysiloxane paint produced by the sol-gel method. The protective layer particularly preferably also contains at least one UV absorber. The protective layer has high abrasion resistance and scratch resistance, thus particularly realizing the function of a scratch-resistant coating.

[0149] For example, commercially available systems are the 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 / 109072A1. These materials are typically synthesized by the condensation of alkoxysilanes and / or alkylalkoxysilanes under acid catalysis or base catalysis. Nanoparticles can be optionally incorporated. Preferred solvents are alcohols such as butanol, isopropanol, methanol, ethanol, and mixtures thereof.

[0150] A variety of methods are known for applying scratch-resistant coatings to plastic articles. The scratch-resistant coating can be applied, for example, by dip coating, spin coating, spraying, or flow coating, preferably by dip coating or flow coating. Curing can be carried out thermally or by UV radiation. The scratch-resistant coating can be applied, for example, directly or after preparing the substrate surface with a primer. A scratch-resistant coating can also be applied by a plasma-assisted polymerization method, for example, by SiO2 plasma. Anti-fog or anti-reflection coatings can also be prepared by the plasma method. A specific injection molding method can also be used, for example, overmolding of a surface-treated film, to apply a scratch-resistant coating on the resulting molded body. Various additives can be present in the scratch-resistant layer, such as UV absorbers, which are derived, for example, from triazoles or triazines.

[0151] The protective layer can be a single-layer or multi-layer system and can thus also be a combination of two or more layers. In particular, the protective layer can consist of layers, namely a topcoat layer a' and a primer layer a'', where the primer layer is arranged between the topcoat layer and the layer to be protected.

[0152] The polysiloxane-based scratch-resistant coating is preferably applied by dip coating or flow coating. Curing is carried out at a temperature of 50°C - 140°C.

[0153] Preferably, a primer containing a UV absorber is used to improve the adhesion of the scratch-resistant paint to the substrate to be coated. The primer may contain other stabilizers, such as HALS systems (hindered amine-based stabilizers), adhesion promoters, and / or flow aids. The respective resins of the substrate forming the primer layer can be selected from a variety of materials and are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Volume A18, pages 368 - 426, VCH, Weinheim 1991. Polyacrylates, polyurethanes, phenol-based systems, melamine-based systems, epoxy systems, and alkyd systems or mixtures of these systems can be used. The resin is usually dissolved in a suitable solvent - usually in an alcohol. Depending on the resin selected, curing can be carried out at room temperature or at an elevated temperature. A temperature of 50 °C to 140 °C is preferably used - usually after most of the solvent has been removed in a short time at room temperature. Commercially available primer systems are, 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.

[0154] In a preferred embodiment for achieving particularly good weathering stability, the protective layer comprises

[0155] a polysiloxane-based scratch-resistant coating, which comprises

[0156] i. at least one UV absorber selected from benzophenone, resorcinol, 2-(2-hydroxyphenyl)benzotriazole, hydroxyphenyl-s-triazine, 2-cyanoacrylate, oxanilide

[0157] and / or a UV inhibitor selected from hindered amines (HALS), in particular based on 2,2,6,6-tetramethylpiperidine or its derivatives;

[0158] ii. at least one combination of an organically modified silane and silica sol. The organically modified silane is, for example, methyltrialkoxysilane or dimethyldialkoxysilane;

[0159] And optionally, in another preferred embodiment, an additional primer layer (layer a''), which is arranged on the substrate to be coated, serves as an adhesion promoter between the polysiloxane-based scratch-resistant coating and the substrate to be coated, and contains at least one UV absorber selected from benzophenone, resorcinol, 2-(2-hydroxyphenyl)benzotriazole, hydroxyphenyl-s-triazine, 2-cyanoacrylate, oxanilide 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 from 0.3 μm to 8 μm, preferably from 1.1 μm to 4.0 μm.

[0160] Most preferably, the protective layer does not contain other layers.

[0161] According to the present invention, "derivative" is understood to mean those compounds whose molecular structure has another atom or another atomic group at the position of an H atom or a functional group or in which one or more atoms / atomic groups are removed. Thus, the parent compound can still be recognized.

[0162] The polysiloxane layer preferably contains organosilicon compounds of the formula R n SiX 4-n and / or their partial condensates, where the R groups are the same or different and are straight-chain or branched, saturated or mono- or poly-unsaturated or aromatic hydrocarbon groups, the X groups are the same or different and are hydrolyzable groups or hydroxyl groups, preferably halogens, especially chlorine or bromine, alkoxy groups, alkylcarbonyl groups or acyloxy groups, and n is 0, 1, 2 or 3, preferably 1 or 2, most preferably 1. R preferably represents a saturated, branched or unbranched alkyl group having 1 to 20 carbon atoms and / or a mono- or poly-unsaturated branched or unbranched alkenyl group having 2 to 20 carbon atoms or an aromatic group having 6 to 12 carbon atoms. The alkyl or alkenyl group further preferably has at most 12, more preferably at most 8 carbon atoms. More preferably, all groups are methyl and / or phenyl. More preferably, X is an alkoxy group, most preferably a C1- to C4-alkoxy group, such as a methoxy or ethoxy group.

[0163] The silicon compound R n SiX 4-n is hydrolyzable and condensable via the X groups. Through these hydrolyzable and condensable groups, an inorganic network containing Si-O-Si units is formed. Compared with the X groups, the R groups are stable to hydrolysis under conventional condensation conditions.

[0164] When using the above-mentioned siloxane system, a dry layer thickness of 3 μm - 20 μm is preferred, further preferably 5 μm - 15 μm, particularly preferably 6 μm - 12 μm. "Dry layer thickness" herein means the layer thickness of the paint after application and subsequent solvent evaporation and subsequent curing by heat or UV.

[0165] Instead of the primer / scratch-resistant coating combination, a one-component hybrid system (which is cured thermally or by UV) can also be used for the multi-layer body of the present invention.

[0166] They are described, for example, in EP 0570165 A2 or WO 2008 / 071363 A2 or DE 2804283 A. Commercially available hybrid systems can be obtained, for example, from Momentive Performance Materials under the names PHC 587, PHC 587C as thermosetting paints or UVHC 3000 and UVHC 5000 as UV-curing paints. Other commercially available UV-curing paint systems suitable according to the present invention are UVT 610 and UVT 820 from Redspot.

[0167] In a particularly preferred method for manufacturing the molded part of the present invention, the protective layer is applied by the flow coating method, because this produces a coated part with high optical quality.

[0168] The flow coating method can be carried out manually through a hose or a suitable coating head, or automatically in a continuous process through a flow coating robot and optionally a slot nozzle.

[0169] Other possible application methods are dip coating, knife coating, roll coating, spraying or spin coating. Here, the part can be coated either in a suspended manner or in a manner of being mounted in a corresponding bracket.

[0170] For larger and / or 3D parts - i.e., parts with a three-dimensional surface having a geometry different from that of a plate - the part to be coated is suspended or placed in a suitable bracket.

[0171] In the case of small parts, coating can also be carried out manually. Here, the liquid primer solution or paint solution for forming the protective layer to be coated is poured longitudinally onto the plate starting from the upper edge of the small part, and at the same time, the starting point of the paint on the plate is guided from left to right across the width of the plate. According to the instructions of the respective manufacturer, the coated plate is ventilated and cured in a vertically suspended manner at the fixture.

[0172] The present invention particularly relates to the following embodiments:

[0173] 1. An LED lighting unit, which comprises

[0174] a) A multi-layer body and

[0175] b) An LED light source,

[0176] wherein the multi-layer body sequentially comprises the following layers:

[0177] a1) A carrier layer made of a thermoplastic composition,

[0178] a2) a stone layer,

[0179] a3) a transparent layer made of a thermoplastic composition with an average thickness of 1 to 6 mm over the entire surface, which is located on one side of the stone layer a2, and this side is the visible surface of the multi-layer body in the LED lighting unit,

[0180] and wherein the LED light source is arranged at least at one side edge of the transparent layer a3 such that the transparent layer a3 can be used as a light conductor for the light emitted by the LED light source.

[0181] 2. The LED lighting unit according to embodiment 1, characterized in that the composition of the carrier layer a1 and / or the composition of the transparent layer a3 is based on an aromatic polycarbonate.

[0182] 3. The LED lighting unit according to the foregoing embodiment 1 or 2, characterized in that the stone layer a2 has a coherent grain microstructure.

[0183] 4. The LED lighting unit according to any one of the foregoing embodiments, characterized in that the average thickness of the stone layer a2 over the entire surface of the stone layer a2 is ≤ 2 mm, especially ≤ 0.3 mm.

[0184] 5. The LED lighting unit according to any one of embodiments 1 to 11, characterized in that the average thickness of the stone layer a2 over the entire surface of the stone layer a2 is > 2 mm.

[0185] 6. The LED lighting unit according to any one of the foregoing embodiments, characterized in that the stone layer a2 has a topography with a maximum roughness Rz of preferably at least 0.1 μm, preferably at least 0.5 μm, more preferably 0.5 to 10000 μm, and more preferably 1.0 to 5000 μm at least on the flat surface facing the transparent layer a3.

[0186] 7. The LED lighting unit according to any one of the foregoing embodiments, characterized in that the average thickness of the carrier layer a1 over the entire surface of the carrier layer is 0.5 to 6 mm.

[0187] 8. The LED lighting unit according to any one of the foregoing embodiments, characterized in that the transparent layer a3 covers substantially the entire surface of the stone layer a2, especially at least 90%.

[0188] 9. The LED lighting unit according to any one of the foregoing embodiments, characterized in that the carrier layer a1 covers the entire surface of the stone layer a2 or protrudes beyond the stone layer a2 at least at one side edge.

[0189] 10. The LED lighting unit according to any one of the foregoing embodiments, wherein the LED light source is arranged such that at least a part of the light emitted by the LED light source is totally reflected at the interface between the transparent layer a3 and the stone layer a2 and / or at the interface between the transparent layer a3 and the ambient air or any other transparent layer optionally located more externally of the multi-layer body.

[0190] 11. The LED lighting unit according to any one of the foregoing embodiments, wherein the multi-layer body has a geometric shape different from that of a plate.

[0191] 12. The LED lighting unit according to any one of the foregoing embodiments, wherein the thermoplastic composition of the carrier layer a1 is a semi-transparent black composition.

[0192] 13. The LED lighting unit according to any one of the foregoing embodiments, wherein the LED lighting unit has a second LED light source, which is arranged such that it is used for backlighting the multi-layer body.

[0193] 14. The LED lighting unit according to any one of the foregoing embodiments, wherein the multi-layer body comprises at least one protective layer having a scratch-resistant coating based on polysiloxane.

[0194] 15. The LED lighting unit according to any one of the foregoing embodiments, wherein the multi-layer body does not comprise other layers except for the optionally present protective layer.

[0195] 16. The LED lighting unit according to any one of the foregoing embodiments, wherein the stone layer a2 is a colored schist layer, a mica schist layer, a limestone layer, a sandstone layer, and / or a marble layer.

[0196] 17. The LED lighting unit according to any one of the foregoing embodiments, wherein the proportion of the aromatic polycarbonate in the thermoplastic composition of the carrier layer a1 and / or the transparent layer a3 is at least 90% by weight.

[0197] 18. The LED lighting unit according to any one of the foregoing embodiments, wherein the LED lighting unit is an element for forming a floor covering, an element for furniture manufacturing, a wall panel, a door panel, a lamp component, a lighting element, a housing of a household appliance or an electrical device, or an element from the automotive field.

[0198] 19. The LED lighting unit according to any one of the foregoing embodiments, characterized in that the LED lighting unit is a component from the automotive field, more precisely a lighting component, an interior component, an instrument panel component, an instrument indicator panel component, a decorative strip, a sill strip, an armrest component or a center console component. Example

[0199] The present invention is illustrated in detail by the following examples, but is not limited thereto.

[0200] Materials used

[0201] Transparent Makrolon® Ai from Covestro Deutschland AG: Aromatic polycarbonate based on bisphenol A, MVR is 19 cm³ / (10 min), measured according to DIN ISO 1133:2012-03 at 300 °C and 1.2 kg, containing UV absorber and release agent. Ty, measured according to ISO 13468-2:2006 (D65, 10°) at 2 mm thickness: 88.07%. Haze, measured according to ASTM D1003:2013 at 2 mm layer thickness: 0.68%.

[0202] Semi-transparent black-colored Makrolon® Ai from Covestro Deutschland AG: Aromatic polycarbonate based on bisphenol A, MVR is 19 cm³ / (10 min), measured according to DIN ISO 1133:2012-03 at 300 °C and 1.2 kg, containing UV absorber and release agent. Ty, measured according to ISO 13468-2:2006 (D65, 10°) at 2 mm thickness: 3.84%. Haze, measured according to ASTM D1003:2013 at 2 mm layer thickness: 100%.

[0203] For pretreatment, the polycarbonate was dried in dry air at 120 °C for 4 hours.

[0204] Colored slate stone plates, mica slate stone plates and sandstone plates each having a thickness of about 3 mm, cut to a size of 200 mm x 150 mm.

[0205] Manufacture of the molded body

[0206] On a KM GX400 injection molding machine from KraussMaffei Group GmbH, multilayer molded parts with dimensions of 200 mm x 150 mm x 6 mm were manufactured for each stone plate.

[0207] For this purpose, in a first step, the stone slabs pre-conditioned in a heating cabinet at 150 °C for 15 minutes are each inserted into the first half of a steel mold with an internal mold size of 200 mm x 150 mm x 6 mm. After the mold is closed, the transparent polycarbonate material melted at 305 °C is injected onto the stone surface in the mold with a maximum specific injection pressure of approximately 2000 bar. The temperature of the mold wall is 100 °C on the ejection side and 90 °C on the opposite injection side. The injection time is 2.5 seconds. After a holding pressure time of 15 seconds (specific holding pressure: 850 bar) and a cooling time of 35 seconds, the mold is opened and the molded part is removed.

[0208] After the molded part has cooled at room temperature for about 5 minutes, the polycarbonate plate injected onto the stone surface is peeled off the stone slab. A very thin stone layer fixed to the polycarbonate plate remains here, with an average thickness of <2 mm over the entire surface.

[0209] The polycarbonate plate with the thin stone layer, together having an average thickness slightly greater than 3 mm, is pre-conditioned again in the heating cabinet at 115 °C for 15 minutes. At the same time, the polycarbonate material in the injection barrel is changed from transparent to translucent black. Subsequently, the plate is re-inserted into the first half of a steel mold with an internal mold size of 200 mm x 150 mm x 6 mm, with the surface having the stone layer facing the second half of the mold. After the mold is closed, the translucent black polycarbonate material melted at 305 °C is injected onto the transparent polycarbonate plate with the stone surface in the mold with a maximum specific injection pressure of approximately 2000 bar. The temperature of the mold wall is 90 °C on the ejection side and 65 °C on the opposite injection side. The injection time is 2.2 seconds. After a holding pressure time of 15 seconds (specific holding pressure: 800 bar) and a cooling time of 30 seconds, the mold is opened and the finished molded part with a total thickness of approximately 6 mm is removed.

[0210] For the illumination of the molded body, it is clamped in a light box, which is manufactured to accommodate a plate with dimensions of 200 mm x 150 mm. This light box has LED strips extending around the plate for edge illumination and an RGB-LED printed circuit board on the back for backlighting. The edge illumination and the backlighting can be operated here either individually or in combination. The effects mentioned above in the description are achieved here.

Claims

1. An LED lighting unit, comprising a) a multi-layer body and b) an LED light source, wherein the multi-layer body sequentially comprises the following layers: a1) a carrier layer made of a thermoplastic composition, a2) a stone layer, a3) a transparent layer made of a thermoplastic composition with an average thickness of 1 to 6 mm over the entire surface, which is located on one side of the stone layer a2, and this side is the visible surface of the multi-layer body in the LED lighting unit, and wherein the LED light source is arranged at at least one side edge of the transparent layer a3 such that the transparent layer a3 can be used as a light conductor for the light emitted by the LED light source, wherein the stone layer a2 has a maximum roughness R of at least 0.1 μm at least on the flat surface facing the transparent layer a3 z in terms of topography 2. The 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 based on an aromatic polycarbonate.

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

4. The LED lighting unit according to claim 1 or 2, characterized in that, The average thickness of the stone layer a2 over the entire surface of the stone layer a2 is ≤ 2 mm.

5. The LED lighting unit according to claim 1 or 2, characterized in that, The average thickness of the stone layer a2 over the entire surface of the stone layer a2 is > 2 mm.

6. The LED lighting unit according to claim 1 or 2, characterized in that, The average thickness of the carrier layer a1 over the entire surface of the carrier layer is 0.5 to 6 mm.

7. The LED lighting unit according to claim 1 or 2, characterized in that, The transparent layer a3 covers at least 90% of the stone layer a2.

8. The LED lighting unit according to claim 1 or 2, characterized in that, The carrier layer a1 covers the entire surface of the stone layer a2 or protrudes beyond the stone layer a2 at at least one side edge.

9. The LED lighting unit according to claim 1 or 2, characterized in that, The LED light source is arranged such that at least a part of the light emitted by the LED light source is totally reflected at the interface between the transparent layer a3 and the stone layer a2 and / or at the interface between the transparent layer a3 and the ambient air or any other optional outermost transparent layer of the multi-layer body.

10. The LED lighting unit according to claim 1 or 2, characterized in that The multi-layer body has a geometric shape different from that of a plate.

11. The LED lighting unit according to claim 1 or 2, characterized in that, The thermoplastic composition of the carrier layer a1 is a translucent black composition.

12. The LED lighting unit according to claim 1 or 2, characterized in that, The LED lighting unit has a second LED light source, which is arranged to be used as backlighting for the multi-layer body.

13. The LED lighting unit according to claim 1 or 2, characterized in that, The multi-layer body comprises at least one protective layer having an anti-scratch coating based on polysiloxane.

14. The LED lighting unit according to claim 1 or 2, characterized in that, The multi-layer body does not contain other layers except for the optionally present protective layer.

15. The LED lighting unit according to claim 1 or 2, characterized in that, The stone layer a2 is a colored schist layer, a mica schist layer, a limestone layer, a sandstone layer or a marble layer.

16. The LED lighting unit according to claim 1 or 2, characterized in that, The proportion of the aromatic polycarbonate in the thermoplastic composition of the carrier layer a1 and / or the transparent layer a3 is at least 90% by weight.

17. The LED lighting unit according to claim 1 or 2, characterized in that, The LED lighting unit is an element for forming a floor covering, an element for furniture manufacturing, a wall panel, a lighting element, a housing of an electrical device or an element from the automotive field.

18. The LED lighting unit according to claim 1 or 2, characterized in that, The LED lighting unit is selected from instrument panel components, decorative strips, armrest components or center console components.

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