Device comprising a multi-layer body and a LiDAR sensor

Abstract

The invention relates to a vehicle utilizing a LiDAR sensor system for driver assistance systems. A composition consisting of a thermoplastic material based on polycarbonate is used here for forming the substrate layer of a cover for the sensor with respect to the surroundings. The cover has a polysiloxane-based topcoat layer comprising a combination of organically modified silane with a silica sol, the silicon dioxide having a d90 particle size of less than 0.50 micron, in order to achieve high abrasion resistance and weathering stability.

Claims

1. A sensor system comprising (a) a LiDAR sensor which emits laser light having a wavelength in the range from 800 to 1600 nm and (b) a cover surrounding all or part of the LiDAR sensor and configured as an element through which the laser light of the LiDAR system is emitted, the cover comprising a multilayer article comprising, in this order, (i) a substrate layer comprising a thermoplastic composition based on aromatic polycarbonate having a melt volume rate MVR of 8 to 20 cm.sup.3/(10 min), determined according to ISO 1133-1:2012-03 (300° C., 1.2 kg), wherein the composition has a light transmission in the range from 380 to 780 nm of less than 25.0% determined at a layer thickness of 4 mm according to DIN ISO 13468-2:2006 (D65, 10°), and wherein the substrate layer in its respective thickness has a transmission for IR radiation in the range from 800 nm to 1600 nm of at least 40%, determined according to DIN ISO 13468-2:2006, and (ii) optionally a primer layer based on polymethyl methacrylate (PMMA) and comprising at least one UV absorber, (iii) a polysiloxane-based topcoat layer comprising a combination of an organically modified silane with a silica sol, the topcoat layer comprising silicon dioxide particles having a D.sub.90, determined by means of scanning transmission electron microscopy, of less than 0.50 μm and comprising no further particles having a D90, determined by means of scanning transmission electron microscopy, ≥ 0.50 μm, wherein the topcoat layer is on the side of the substrate layer that is opposite the side of the substrate layer on which the LiDAR sensor is disposed, and wherein an intensity of the laser light emitted by the LiDAR sensor after passing through the multilayer article in its respective thickness following an abrasion test according to DIN ISO 15082:2017-06 and received by the LiDAR sensor after passing again through the multilayer article is at least 65%.

2. The sensor system according to claim 1, wherein the topcoat layer comprises at least one UV absorber from the group of benzophenones, resorcinols, 2-(2-hydroxyphenyl)benzotriazoles, hydroxyphenyl-s-triazines, 2-cyanoacrylates and/or oxalanilides.

3. The sensor system according to claim 1, wherein the organically modified silane is at least one methyltrialkoxysilane, a dimethyldialkoxysilane or a mixture thereof.

4. The sensor system according to claim 1, wherein the multilayer article comprises one or more primer layers having a thickness of in each case 0.3 μm to 8 μm, comprising 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).

5. The sensor system according to claim 1, wherein the cover comprises no layers other than the substrate layers (i), one or more topcoat layers (iii) and optionally one or more primer layers (ii).

6. The sensor system according to claim 1, wherein between the LiDAR sensor and the cover there is only air or an element that does not adversely affect the functional capacity of the LiDAR sensor.

7. The sensor system according to claim 1, wherein the topcoat layer comprises no particles other than the silicon dioxide particles.

8. The sensor system according to claim 1, wherein the D.sub.90 of the silicon dioxide particles, determined by means of scanning transmission microscopy, is less than 50 nm.

9. The sensor system according to claim 1, wherein the multilayer article comprises, on both sides of the substrate layer, a topcoat layer (iii) and in each case optionally a primer layer (ii).

10. The sensor system according to claim 1, wherein the cover is a front panel, a rear panel, a bumper, a radiator grille, a vehicle roof, a vehicle roof module or a vehicle side element.

11. The sensor system according to claim 1, wherein the thermoplastic composition of the substrate layer comprises the following components: (iv) at least 70% by weight of aromatic polycarbonate, (v) at least one green and/or blue colorant and (vi) at least one red and/or violet colorant, (vii) optionally further colorants, wherein the sum of the colorants (v) to (vii) is at least 0.05% by weight and the at least one colorant of group (v) is a colorant selected from the group consisting of the colorants of formulae (1), (2a-c), (3), (4a), (4b), (5), (6), (7) and/or (8), ##STR00018## ##STR00019## wherein Rc and Rd independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents a natural number between 0 and 3, ##STR00020## where the radicals R(5-20) independently of one another represent hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, thexyl, fluoro, chloro, bromo, sulfone or CN and M is aluminum, nickel, cobalt, iron, zinc, copper or manganese, ##STR00021## wherein R1 and R2 independently of one another represent a linear or branched alkyl radical or halogen, n is a natural number between 0 and 4, and the at least one colorant of group (vi) is a colorant selected from the group consisting of the colorants of formulae (9), (10), (11), (12), (13), (14a), (14b) and/or (15), ##STR00022## wherein R is selected from the group consisting of H and p-methylphenylamine radical, ##STR00023## wherein Ra and Rb independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents a natural number between 0 and 3, ##STR00024## and where the colorants of group (vii) are selected from the group consisting of the yellow and orange colorants of formulae (16), (17), (18), (19) and/or (20) ##STR00025## and wherein the composition comprises no colorants other than the colorants of groups (v) to (vii), (viii) optionally one or more additives selected from the group consisting of heat stabilizers, mould release agents, UV absorbers, flame retardants, antistats and/or flow improvers, (ix) 0% to less than 5.0% by weight of further thermoplastic polymers and (x) 0% to less than 0.005% by weight of carbon black, and where the thickness of the substrate layer is 1.0 to 6.0 mm.

12. The sensor system according to claim 11, wherein the sum of the colorants (v) to (vii) in the thermoplastic composition of the substrate layer is at least 0.10% by weight and wherein the thermoplastic composition comprises no other thermoplastics.

13. The sensor system according to claim 11, wherein the composition of the substrate layer comprises no components other than components (iv)-(vi) and optionally one or more of components (vii)-(x).

14. A vehicle comprising the sensor system according claim 1.

15. A method comprising applying a polysiloxane-based topcoat layer comprising a combination of an organically modified silane with a silica sol, the topcoat layer comprising silicon dioxide particles having a D.sub.90, determined by means of scanning transmission electron microscopy, of less than 0.50 μm and comprising no further particles having a D.sub.90, determined by means of scanning transmission electron microscopy, ≥0.50 μm, over a LiDAR sensor cover to form a coating layer of a multilayer article, wherein the cover is configured as an element through which laser light having a wavelength in the range from 800 to 1600 nm from the LiDAR sensor is emitted, and wherein an intensity of the laser light emitted by the LiDAR sensor after passing through the multilayer article in its respective thickness following an abrasion test according to DIN ISO 15082:2017-06 and received by the LiDAR sensor after passing again through the multilayer article is at least 65%.

Description

FIGURES

(1) FIG. 1 shows a front panel as an example for a cover according to the invention.

(2) FIG. 2 shows the experimental set up used in the examples section.

EXAMPLES

(3) The invention is described in more detail hereinafter with reference to examples.

Substrate Material 1: For Comparative Example

(4) Composition containing 99.99984% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol. The composition also contained 0.00006% by weight of Macrolex Violet 3R (colorant of formula (12)) and 0.0001% by weight of Macrolex Blue RR (colorant of formula (7)).

Substrate Material 2: For Comparative Example

(5) Composition containing 99.8% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol. The composition also contained 0.1% by weight of Solvent Blue 36 (further colorant) and 0.1% by weight of Macrolex Green G (colorant of formula (2)).

Substrate Material 3: For Comparative Example

(6) Composition containing 99.8000% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol. The polycarbonate contained 0.134% by weight of Solvent Blue 36 (further colorant), 0.044% by weight of Macrolex Orange 3G (colorant of formula (17)) and 0.022% by weight of Amaplast Yellow GHS (Solvent Yellow 163, colorant of formula (18)).

Substrate Material 4: For Comparative Example

(7) Composition containing 99.84% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol. The material contained 0.16% by weight of carbon black.

Substrate Material 5: For Comparative Example

(8) Composition containing 93.195850% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 18 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with tert-butylphenol. The composition additionally contained 6.756% by weight of Kronos 2230 (titanium dioxide), 0.00006% by weight of Macrolex Yellow 3G (colorant of formula (16)), 0.00009% by weight of Macrolex Violet 3R (colorant of formula (12)) and 0.054% by weight of Tinopal (2,5-thiophenyldibis(5-tert-butyl-1,3-benzoxazene); optical brightener).

Substrate Material 6: For Comparative Example

(9) Composition containing 99.435% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol. The polycarbonate contained 0.1% of Kronos 2230 (titanium dioxide), 0.03% of Sicotan Yellow K2107 (Pigment Brown 24, CAS 68186-90-3; further colorant), 0.022% of Heucodur Blue 2R from Heubach (Pigment Blue 28, cobalt-aluminate blue spinel, CAS 1345-16-0; further colorant), 0.35% of Macrolex Red EG (structure 10) and 0.063% of Bayferrox 110 M from Lanxess AG (Fe.sub.2O.sub.3; CAS 001309-37-1).

Substrate Material 7: For Comparative Example

(10) Polycarbonate/ABS blend from Covestro Deutschland AG having an MVR of about 17 cm.sup.3/10 min measured at 260° C. at a loading of 5.0 kg (according to ISO 1133-1:2012-03) and having an ABS proportion of about 30% by weight and an SAN content of about 10% by weight. The material contained no colorants.

Substrate Material 8: For Comparative Example

(11) Composition containing 99.96% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol. The composition contained 0.04% by weight of carbon black.

Substrate Material 9: For Comparative Example

(12) Composition containing 99.78% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol. The composition contained 0.02% by weight of carbon black and 0.2% by weight of Macrolex Violet B (colorant of formula (13)).

Substrate Material 10: For Inventive Example

(13) Composition containing 99.874% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 18 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with tert-butylphenol. The composition also contained 0.048% by weight of Macrolex Orange 3G (colorant of formula (17)), 0.01% by weight of Macrolex Violet B (colorant of formula (13)) and 0.068% by weight of colorant of formula 4a/4b (1:1).

Substrate Material 11: For Inventive Example

(14) Composition containing 99.8% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol and containing 0.1% by weight of Macrolex Violet 3R (colorant of formula (12)) and 0.1% by weight of Macrolex Green 5B (colorant of formula (1)).

Substrate Material 12: For Inventive Example

(15) Composition containing 99.894% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/10 min measured at 300° C. at a loading of 1.2 kg (according to ISO 1133-1:2012-03) and based on bisphenol A and terminated with phenol and containing 0.0360% by weight of Macrolex Blue RR (colorant of formula (7)) and 0.07% by weight of Macrolex Violet 3R (colorant of formula (12)).

Substrate Material 13: For Comparative Example

(16) Injection moulded colorant- and carbon black-free sheet made of polyamide 6,6 having a thickness of 3.0 mm.

Substrate Material 14: For Comparative Example

(17) Polyether sulfone in the form of a 0.175 mm-thick Ajedium film from Solvay Solexis Inc.

Substrate Material 15: For Comparative Example

(18) Siloxane-containing block co-condensate based on bisphenol A-containing polycarbonate having a siloxane content of 5% and produced as described in EP 3099731 A1.

Substrate Material 16: For Comparative Example

(19) Sheet made of Altuglass-brand polymethyl methacrylate (Arkema).

(20) Test Methods

(21) Determination of Solids Content (Method a for Siloxane Coatings and Primers):

(22) The solids content of the coatings was determined using the Mettler Toledo HB43 solids tester, in which a weighed sample of coating was evaporated at 140° C. until constant mass was reached. The solids content is then given in percent from the ratio of mass after to mass before evaporation. The solids content of the coating after curing of the coating here in the simplest case is the weight of coating minus the weight of solvent.

(23) Solids Content Determination (Method B for UV Coating Systems):

(24) The solids content of the coatings was determined using the Mettler Toledo HB43 solids tester, in which a weighed sample of coating was evaporated at 110° C. until constant mass was reached. The solids content is then given in percent from the ratio of mass after to mass before evaporation. The solids content of the coating after curing of the coating here in the simplest case is the weight of coating minus the weight of solvent.

Multilayer Article 1: Comparative Example

(25) Multilayer article 1 comprising substrate material 11 with a topcoat layer containing silicon dioxide particles having a particle size of 4 μm (Amosil FW600; fired silicon dioxide Amosil FW 600 from Quarzwerke GmbH at Frechen, with a mean particle size of around 4 μm, a D.sub.10/D.sub.90 ratio of around 1.5/10 [μm/μm] determined by Cilas Granulometer; ISO 13320:2009 (particle measurement by laser light scattering) and a specific surface area of around 6 m.sup.2/g, determined according to DIN ISO 9277 (DIN-ISO 9277:2014-01).

(26) Production of the Coating Material:

(27) In a flask equipped with a stirrer and condenser, 27.5 g of methyltrimethoxysilane were mixed with 0.2 g of concentrated acetic acid.

(28) In a further vessel, 5.0 g of Joncryl 587 were dissolved in a mixture of 6.0 g each of isopropanol and n-butanol. Using a dissolver, 6.8 g of Amosil FW 600 were subjected to high-shear dispersing for 30 minutes, after which 15.7 g of deionized water were added.

(29) With stirring, the previously prepared Joncryl 587/Amosil FW 600-dispersion was added slowly to the acidified methyltrimethoxysilane.

(30) The batch was diluted with 15.5 g each of isopropanol and n-butanol, and 0.1 g of tetra-n-butylammonium acetate (TBAA) was added.

(31) The solids of the sol-gel coating material was adjusted, using a 1:1 solvent mixture of isopropanol and n-butanol, to a solids content of 25% as measured by Method A for siloxane coatings and primers.

(32) Solids Content: 25%

(33) pH: 6.0

(34) The topcoat layer was applied by hand by means of a flow coating process. To form the protective layer, the coating, starting from the top edge of a polycarbonate sheet composed of substrate 11 with dimensions of 250 mm×105 mm×3.2 mm, was poured over the sheet in the lengthwise direction, while at the same time the starting point of the coating on the sheet was guided from left to right over the width of the sheet.

(35) Hanging vertically on a bracket, the coated sheet was cured after a flash-off time of 30 minutes at 23° C. and subsequently at 130° C. for 60 minutes.

Multilayer Article 2: Comparative Example

(36) Multilayer article comprising substrate material 11 with a topcoat layer containing silicon dioxide particles having a particle size D.sub.90 of 1.2 μm (Amosil FW960-943 from Quarzwerke GmbH at Frechen, with a mean particle size of 1.2 μm and a specific surface area of around 14 m.sup.2/g, determined according to DIN ISO 9277 (DIN-ISO 9277:2014-01).

(37) Production of the coating material: The coating material was produced as for multilayer article 1, but using Amosil FW 960-943 in the present example.

(38) The solids of the sol-gel coating material was adjusted, using a 1:1 solvent mixture of isopropanol and n-butanol, to a solids content of 25% as measured by Method A for siloxane coatings and primers.

(39) Solids Content: 25%

(40) pH: 5.5

(41) The coating material was applied, as for multilayer article 1, to a polycarbonate sheet composed of substrate 11 with dimensions of 250×105×3.2 mm.

Multilayer Article 3: Inventive Example

(42) Multilayer article made of substrate material 11 with a topcoat layer containing silicon dioxide particles having a particle size of around 22 nm (Ludox AS-40 Silica, colloidal, specific surface area 140 m.sup.2/g; W.R. Grace&Co.—Conn. Maryland 21044 USA).

(43) Production of the Coating Material:

(44) In a flask equipped with a stirrer and condenser, 27.5 g of methyltrimethoxysilane were mixed with 0.2 g of concentrated acetic acid.

(45) In a further vessel, 17 g of Ludox AS-40 (silica sol from Grace) were mixed with 5.5 g of deionized water.

(46) With stirring, the diluted silica sol was added to the acidified methyltrimethoxysilane and the mixture was stirred at room temperature for a further 4 hours. After the 4 hours, a further 1.7 g of concentrated acetic acid were added. To bring about the hydrolysis-condensation reaction, stirring took place at room temperature for 3 hours more.

(47) Added to the mixture with stirring at room temperature were 21.5 g each of isopropanol and n-butanol, and 0.1 g of tetra-n-butylammonium acetate (TBAA). Subsequently 5.0 g of Joncryl 587 were dissolved in the mixture.

(48) The solids of the sol-gel coating material was adjusted, using a 1:1 solvent mixture of isopropanol and n-butanol, to a solids content of 25% as measured by Method A for siloxane coatings and primers.

(49) Solids Content: 25%

(50) pH: 5.0

(51) The coating material was applied, as for multilayer article 1, to a polycarbonate sheet composed of substrate 11 with dimensions of 250×105×3.2 mm.

Multilayer Article 4: Inventive Example

(52) A commercially available primer solution was used, having a solids content of 10.5% (method A). This primer is based on polymethyl methacrylate and also glycol ether, and contains 1-methoxy-2-propanol and diacetone alcohol as solvents and dibenzoylresorcinol as UV absorber.

(53) In order to be within the layer thickness specification of the manufacturer, this coating material requires dilution with a 1:1 solvent mixture of diacetone alcohol:1-methoxy-2-propanol. For this purpose, the primer described above was admixed with a solution of Tinuvin 479 (a hydroxyphenyltriazine UV absorber in methoxy-2-propanol/diacetone alcohol (1:1), to give a primer solution containing 5.00% by weight of Tinuvin 479 with a solids content of 5.9%. The coating material was subsequently filtered with a suction filter (2-4 μm cellulose filter).

(54) Production of the Hard Coat Solution (for the Topcoat Layer):

(55) A topcoat layer solution was used that contained Ludox AS particles with a particle diameter of around 22 nm. The solids content was around 20% by weight and the UV absorber content was around 11% by weight. The UV absorber used was a UV absorber of structure (III) (with n=3). The method for producing the topcoat layer solution is described in U.S. Pat. No. 5,041,313 A.

(56) 24.5 g of this solution were admixed with stirring with 0.88 g of glacial acetic acid (100% acetic acid), to give a hard coat solution with a 3.5% by weight addition of acetic acid, based on the total amount of coating material.

(57) Application took place by hand. To form the layers, the liquid primer solution, starting from the top edge of the small part, in the case of a polycarbonate sheet composed of substrate 11 with dimensions of 250 mm×105 mm×3.2 mm, was poured over the sheet in the lengthwise direction, while at the same time the starting point of the coating on the sheet was guided from left to right over the width of the sheet. Hanging vertically on a bracket, the coated sheet was cured after a flash-off time of 30 minutes at 23° C. and subsequently at 130° C. for 60 minutes. Following the application of the primer layer, the topcoat material (the scratch resistance layer) was applied analogously as a topcoat layer and, after a 30-minute flash-off time at 23° C., was cured at 130° C. for 60 minutes.

Multilayer Article 5: Inventive

(58) Multilayer article 5 corresponds to multilayer article 4 except that the below-stated substrate layer thickness is 4 mm rather than 3.2 mm.

(59) Production and application of the primer and topcoat took place as described for multilayer article 4.

Multilayer Article 6: Inventive

(60) Multilayer article composed of substrate material 11, corresponding to multilayer article 3 but with a different substrate layer thickness (4 mm) instead of 3.2 mm. The production of the coating material and its application took place as described in the multilayer article 3 example.

Multilayer Article 7: Comparative Example

(61) Multilayer article composed of substrate material 11 and a UV-curing urethane acrylate coating system.

(62) A coating solution consisting of 100 g of Desmolux VP LS2308 (ALLNEX, unsaturated aliphatic urethane acrylate), 61.0 g of Ebecryl 8301 (Cytec, hexafunctional aliphatic urethane acrylate), 4.86 g of Irgacure 814 (BASF), 1.62 g of BYK 306 (BYK), 3.78 g of Hostavin 3206 LIQ (Clariant), 1.70 g of Hostavin® 3058 LIQ (Clariant), 160 g of methoxypropanol and 160 g of diacetone alcohol was applied single-sidedly by a flow coating process to plates composed of substrate 11 in a size of 10.5 cm×15 cm×0.4 cm.

(63) Coating took place by hand. Here, starting from the top edge of the small part, the coating solution was poured in the lengthwise direction over the sheet, while at the same time the starting point of the primer on the sheet was guided from left to right over the width of the sheet. After an evaporation time of 5 minutes, the sheet was subjected to primary curing at 75° C. for 6 minutes. This was followed by the UV curing with a dose of ˜7-8 J/cm.sup.2, using a mercury-doped UV lamp (80 W/cm).

(64) Compounding

(65) The compounding of the components to give the compositions for the substrate layers was effected in a KraussMaffei Berstorff ZE25 twin-screw extruder at a barrel temperature of 260° C., a melt temperature of about 280° C. and a speed of 100 rpm with the amounts of components specified in the examples. The coloured compositions were processed into 5 mm, 4 mm- and 3.2 mm-thick injection-moulded, rectangular polycarbonate sheets.

(66) Pretreatment/Cleaning of the Sheets Prior to Coating

(67) Coating took place in a controlled-atmosphere coating chamber under the respective stipulations of the coating manufacturer, at 23 to 25° C. and at 40% to 48% relative humidity.

(68) The specimen sheets were cleaned using so-called iso wipes (LymSat® from LymTech Scientific; saturated with 70% isopropanol and 30% deionized water), rinsed off with isopropanol, dried in air for 30 minutes and blown with ionized air.

(69) LiDAR Sensor Employed

(70) A Velodyne Ty Puck VLP 16 LiDAR sensor was employed. Said sensor operates in the wavelength range from 895 to 915 nm (tolerance range). The nominal wavelength, i.e. actual operating wavelength, of the 16 lasers is 903 nm.

(71) The essential characteristics of this sensor include:

(72) Vertical detection angle −15° to +15° with 2° spacing between scanning planes; horizontal detection angle 360°. The software includes a multibeam function with 16 beams for minimizing shadow effects. Horizontal resolution of the laser system is 0.1° to 0.4° depending on rotational velocity. The rotational velocity of vertical detection is adjustable between 5 to 20 Hz. At a data rate of 2 Mbyte/sec, 300 000 points/second are detected. The measurement accuracy achieved is about +/−3 cm, corresponding to 1 sigma. The detectable measuring distance is between 1 mm to 100 metres. The energy requirement of the sensor system is 8 watts of electrical power, corresponding to 0.7 A at 12 volts. The overall dimensions of the sensor are: diameter 100 mm and height 65 mm.

(73) Method of Measurement

(74) To reduce the scattered-light signals, the sensor head of the LiDAR sensor was shielded on the side away from the measurement path. Only lasers 1, 3, 5, 7, 8, 10, 12 and 14 were used. Furthermore, the field of view (FOV) of the sensor in the sensor interface was limited to 20° (350°-10°). The reflection surface used was a smooth white surface coated with TiO.sub.2-containing paint. The wall was at a distance of 2.5 m from the LiDAR sensor.

(75) The test specimens were tested by means of a sample holder parallel to the LiDAR sensor, with the reverse side of the samples being around 15 mm in front of the LiDAR sensor, so that both the output signal and the input signal returned had to pass through the wall thickness of the test sheet. Analysis was carried out using the “VeloView” software from the manufacturer of the LiDAR sensor, Velodyne. A determination was made of the mean value of the intensities measured for a sample. This mean sample value was divided by the mean value of the reference measurement (air), so as to determine the relative intensity.

(76) The measured intensities of the recorded laser signal were between 0% and 100%. The lower the attenuation (weakening) of the signal, and hence the higher the intensity of the signal measured, the more suitable the cover is classed for LiDAR-assisted sensor applications in the automotive sector. The transmission of the respective sheet for IR radiation in the range from 800 nm to 1600 nm was determined according to DIN ISO 13468-2:2006. The light transmission in the VIS region of the spectrum (380 to 780 nm, degree of transmission Ty) was determined according to DIN ISO 13468-2:2006 (D65, 10°, layer thickness of specimen sheet: 4 mm). The transmission measurements were performed using a Perkin Elmer Lambda 950 spectrophotometer with a photometer sphere.

(77) Abrasion Testing:

(78) The abrasion test took the form of a carwash test according to DIN ISO 15082:2017-06.

(79) 10 Double washes were performed with a stirred suspension of quartz flour in water (1.5 g of quartz flour per litre of water).

(80) MVR:

(81) Melt volume flow rate (MVR) was determined in accordance with ISO 1133-1:2012 (at a test temperature of 300° C., mass 1.2 kg) using the Zwick 4106 instrument from Zwick Roell. In addition MVR was measured after a preheating time of 5, 20 and 30 minutes. This is a measure of melt stability under elevated thermal stress.

(82) Results

(83) TABLE-US-00001 TABLE 1 Results of measurement for light transmission Ty (D65, 10°) (VIS) and LiDAR sensor suitability of the substrate layers Intensity of the laser Total colorant signal after passage Substrate Colorants and concentration Ty Thickness through the substrate Examples material other components [% by weight] [%] [mm] [%]  1 comparative 1 (7); (12) 0.00016 88.1 5 70.8 example  2 comparative 2 (2); 0.2 0 2 24.9 example further colorant  3 comparative 3 (17); (18); 0.199 0 2 24.3 example further colorant  4 comparative 4 Carbon black 0.16 0 5 0 example  5 comparative 5 (16); (12); TiO.sub.2 0.00015 0 3.2 0 example  6 comparative 6 Titanium dioxide; 0.465 0 3.2 0 example (10); further colorants; iron(III) oxide  7 comparative 7 — 0 23.8 3.2 0 example  8 comparative 8 Carbon black 0.04 0 2.0 0 example  9 comparative 9 Carbon black; (13) 0.2 0 2.0 0 example 10 according 10 (4a/4b); (13); (17) 0.126 0 2.0 71.7 to the invention 11 according 11 (12); (1) 0.2 0 4.0 69.6 to the invention 12 according 12 7/12 0.106 0.7 2.0 76.7 to the invention 13 comparative 13 — — 46 3.0 0 example 14 comparative 14 — — 87 0.175 2.9 example 15 comparative 15 — — 23 2.3 0 example 16 comparative 16 — — 92.5 2.7 73.4 example

(84) As is apparent from table 1 only certain substrate materials are suitable. Even very thin layer thicknesses of unsuitable materials, for example of polypropylene, attenuate the sensor signal to such an extent that an intensity was no longer measurable in the measuring setup. It was likewise surprising that different substrates such as polyamide (Ex. 16) and ABS (Ex. 17) showed no permeability to the LiDAR sensor in the measuring setup. All of these thermoplastics are transparent or at least semitransparent in the IR range in relevant layer thicknesses. Surprisingly, completely amorphous polymers such as polyethersulfone and polyester also exhibit a high attenuation for the LiDAR sensor.

(85) Even modified polycarbonates such as siloxane-containing polycarbonates cannot be suitably combined with a LiDAR sensor.

(86) It was furthermore entirely surprising that combinations of colorants soluble in a polycarbonate matrix in some cases also resulted in high attenuations of the LiDAR signal (examples 2 and 3). By contrast the inventive combination of colorants in the thermoplastic matrix of bisphenol A-based polycarbonate can be suitably combined with a LiDAR sensor.

(87) In addition, the melt volume flow rate of a number of compositions was determined over a particular time interval according to ISO 1133-1:2011 at 300° C./320° C. at a loading of 1.2 kg (table 2). Is it apparent therefrom that the substrate materials 2 and 3 of the comparative examples are markedly more unstable than the inventive substrate material 11.

(88) TABLE-US-00002 TABLE 2 MVR for the substrate materials 2, 3 and 11 Substrate Substrate Substrate material 2 material 3 material 11 [cm.sup.3/(10 min)] [cm.sup.3/(10 min)] [cm.sup.3/(10 min)] 300° C. after 5 min 12.0 12.3 12.5 after 20 min 12.5 13.7 13.2 after 30 min 13.0 15.0 13.3 320° C. after 5 min 21.5 22.3 21.9 after 20 min 24.8 30.1 23.0 after 30 min 26.5 34.7 23.5

(89) TABLE-US-00003 TABLE 3 Results of measurement for the LiDAR sensor suitability of the protective layers Thickness of Intensity Multilayer multilayer after passage article Substrate article Particle size D.sub.90 in through the Example material [mm] the coating system substrate 1 11 3.2 4 μm 24.6% 2 11 3.2 1.2 μm 36.8% 3 11 3.2 22 nm 67.1% 4 11 3.2 22 nm 74.2% The results were evaluated arithmetically.

(90) TABLE-US-00004 TABLE 4 Transmissions of the multilayer articles in the IR range Thickness Direct Total Direct Total Multilayer Multilayer trans- trans- trans- trans- article article mission at mission at mission at mission at Example [mm]* 905 nm 905 nm 1550 nm 1550 nm 1 3.2 74.5% 88.1% 82.0% 87.2% 2 3.2 82.5% 88.4% 84.4% 87.9% 3 3.2 87.1% 89.8% 86.6% 88.4% 4 3.2 91.2% 92.0% 90.2% 91.0% *corresponds essentially to the thickness of the substrate layer

(91) For the tests on multilayer articles, a substrate material was selected which showed a high permeability to the LiDAR signal in the test. Various multilayer bodies were tested and investigated, being combinations which exhibited high permeability. It was found that the attenuation of the LiDAR signal is effected in particular by the size of the particles used in order to achieve good scratch resistance. High scratch resistance is important in order to reduce effects of weathering. It was found that only certain particle sizes in combination with suitable substrate materials are suitable for LiDAR sensors.

(92) TABLE-US-00005 TABLE 5 Attenuation of the LiDAR signal before the abrasion test Thickness Intensity after Multilayer Multilayer passage through article Substrate article the substrate Example material [mm] [%] 5 (inv.) 11 4 74.2 6 (inv.) 11 4 69.6 7 (comp.) 11 4 68.7

(93) TABLE-US-00006 TABLE 6 Attenuation of the LiDAR signal after the abrasion test Arithmetic evaluation: Thickness of Multilayer multilayer Intensity after article Substrate article passage through Example material [mm] the substrate Delta 5 (inv.) 11 4 73.4% 0.8 6 (inv.) 11 4 68.7% 0.9 7 (comp.) 11 4 47.7% 22.5

(94) Multilayer articles of the invention still have a minimum signal of 65% after the abrasion test.

(95) TABLE-US-00007 TABLE 7 Transmissions of the multilayer articles in the IR range Thickness Direct Total Direct Total Multilayer trans- trans- trans- trans- article mission at mission at mission at mission at Example [mm] 905 nm 905 nm 1550 nm 1550 nm 5 4 89.1% 92.0% 88.8% 90.3% (91.2%) (92.0%) (90.2%) (91.0%) 6 4 88.8% 91.4% 87.8% 89.7% (91.1%) (91.9%) (88.8%) (89.6%) 7 4 79.5% 89.2% 83.2% 88.0% (88.8%) (89.7%) (87.5%) (88.4%) * The figures in brackets indicate the results before the carwash test.

(96) It is found, completely surprisingly, that an organic coating system, including in particular one without nanoparticles, after the carwash test according to DIN ISO 15082:2017-06, exhibits greater attenuation for the LiDAR sensor.