Laser beam-permeable substrate material for use on sensors

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, polyester carbonate and/or polymethylmethacrylate is used here for forming a cover for the sensor against the surroundings.

Claims

1. A vehicle comprising a) a LiDAR sensor which emits laser pulses having a wavelength in the range from 800 to 2500 nm and b) a cover partially or completely surrounding the LiDAR sensor having a substrate layer comprising a region made of a thermoplastic composition based on aromatic polycarbonate, polyester carbonate and/or polymethyl methacrylate, 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 the region of the substrate layer made of the thermoplastic composition in its respective thickness has a permeability to IR radiation in the range from 800 nm to 2500 nm of at least 40% determined according to DIN ISO 13468-2:2006.

2. The vehicle according to claim 1, wherein the thermoplastic composition of the substrate layer contains less than 0.0005% by weight of carbon black.

3. The vehicle according to claim 1, wherein the composition contains no carbon black.

4. The vehicle according to claim 1, wherein the composition contains no further thermoplastic polymers.

5. The vehicle according to claim 1, wherein the composition contains 0% to less than 5.0% by weight of further thermoplastic polymers.

6. The vehicle according to claim 1, wherein the thickness of the region of the substrate layer made of the thermoplastic composition is 2 mm to 4 mm.

7. The vehicle according to claim 1, wherein in addition to the substrate layer and a scratch resistant coating optionally present on one or more sides the cover comprises no further layers.

8. The vehicle according to claim 1, wherein the cover is a front panel, a rear panel, a bumper, a radiator grill, a vehicle roof, a vehicle roof module or a vehicle side element.

9. The vehicle according to claim 1, wherein the thermoplastic composition of the substrate layer contains i) at least 70% by weight of thermoplastic polymer from the group consisting of aromatic polycarbonate, polyester carbonate and/or polymethyl methacrylate, ii) at least one green and/or one blue colorant selected from the group consisting of the colorants of formulae (1), (2a-c), (3), (4a), (4b), (5) and/or (6) ##STR00038## ##STR00039## wherein Rc and Rd independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents an integer between 0 and 3, wherein the radical for n=0 is hydrogen, ##STR00040## iii) at least one red and/or violet colorant selected from the group consisting of the colorants of formulae (7), (8), (9), (10), (11), (12a), (12b) and/or (13) ##STR00041## wherein R is selected from the group consisting of H and p-methylphenylamine radical, ##STR00042## wherein Ra and Rb independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents an integer between 0 and 3, Wherein the radical for n=0 is hydrogen, ##STR00043## iv) optionally one or more further colorants selected from the group consisting of the yellow and orange colorants of formulae (14), (15), (16), (17) and/or (18) ##STR00044## wherein the sum of the colorants ii) to iv) is >0.05% by weight and wherein the composition contains 0% to less than 30.0% by weight of further thermoplastic polymers and 0% to less than 0.02% by weight of carbon black, wherein the composition contains in addition to the colorants of groups ii) to iv) less than 0.1% by weight of further colorants and less than 0.1% by weight of titanium dioxide and wherein the thickness of the region of the substrate layer made of the thermoplastic composition is 1.0 to 7.0 mm.

10. The vehicle according to claim 9, wherein the sum of the colorants ii) to iv) in the thermoplastic composition of the substrate layer is at least 0.10% by weight.

11. The vehicle according to claim 9, wherein the composition contains less than 0.1% by weight of white pigment.

12. The vehicle according to claim 9, wherein, in addition to the components i), ii), iii) and optionally iv), carbon black, further thermoplastic polymer and/or colorants distinct from the colorants of groups ii) to iv), the composition of the substrate layer contains no further components with the exception of v) optionally heat stabilizers, mold release agents, UV absorbers, flame retardants, antistats and/or flow enhancers.

13. A vehicle comprising a) a LiDAR sensor which emits laser pulses having a wavelength in the range from 800 to 2500 nm and b) a cover partially or completely surrounding the LiDAR sensor having a substrate layer, wherein the substrate layer comprises a region made of a thermoplastic composition having a light transmission in the range from 380 to 780 nm of less than 0.1% determined at a layer thickness of 4 mm according to DIN ISO 13468-2:2006 (D65, 10°), and the region of the substrate layer in its respective thickness has a permeability to IR radiation in the range from 800 nm to 2500 nm of at least 50% determined according to DIN ISO 13468-2:2006 and wherein the composition consists of i) at least 85% by weight of thermoplastic polymer selected from the group consisting of aromatic polycarbonate, polyester carbonate and/or polymethyl methacrylate, ii) at least one green and/or one blue colorant selected from the group consisting of the colorants of formulae (1), (2a-c), (3), (4a), (4b), (5) and/or (6) ##STR00045## ##STR00046## wherein Rc and Rd independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents an integer between 0 and 3, wherein the radical for n=0 is hydrogen, ##STR00047## and iii) at least one red and/or violet colorant selected from the group consisting of the colorants of formulae (7), (8), (9), (10), (11), (12a), (12b) and/or (13) ##STR00048## wherein R is selected from the group consisting of H and p-methylphenylamine radical, ##STR00049## wherein Ra and Rb independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents an integer between 0 and 3, wherein the radical for n=0 is hydrogen, ##STR00050## iv) optionally further colorants selected from the group consisting of the colorants of formulae (14), (15), (16), (17) and/or (18) ##STR00051## v) optionally heat stabilizers, mold release agents, UV absorbers, antistats and/or flow enhancers, vi) 0% to less than 30.0% by weight of further thermoplastic polymers, vii) 0% to less than 0.02% by weight of carbon black, less than 0.1% by weight of further colorants and less than 0.1% by weight of titanium dioxide, wherein the sum of the colorants ii) to iv) is >0.10% by weight; and wherein the thickness of the region of the substrate layer made of the thermoplastic composition is 1.0 to 6.0 mm.

14. A method of utilizing a molding having a substrate layer comprising a region made of a thermoplastic composition based on aromatic polycarbonate, polyester carbonate and/or polymethyl methacrylate having a thickness of this region of the substrate layer of 1.0 to 7.0 mm, wherein the composition has a light transmission in the range from 380 to 780 nm of less than 25% determined at a layer thickness of 4 mm according to DIN ISO 13468-2:2006 (D65, 10°) and the region of the substrate layer made of the thermoplastic composition in its respective thickness has a permeability to IR radiation in the range from 800 nm to 2500 nm of at least 50% determined according to DIN IS 13468-2:2006, for partially or completely covering a LiDAR sensor which emits laser pulses having a wavelength in the range from 800 to 2500 nm.

15. The method according to claim 14, wherein the composition contains i) at least 70% by weight of a thermoplastic from the group consisting of aromatic polycarbonate, polyester carbonate and/or polymethyl methacrylate, ii) at least one green and/or one blue colorant selected from the group consisting of the colorants of formulae (1), (2a-c), (3), (4a), (4b), (5) and/or (6) ##STR00052## ##STR00053## wherein Rc and Rd independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents an integer between 0 and 3, wherein the radical for n=0 is hydrogen, ##STR00054## and iii) at least one red and/or violet colorant selected from the group consisting of the colorants of formula (7), (8), (9), (10), (11), (12a), (12b) and/or (13) ##STR00055## wherein R is selected from the group consisting of H and p-methylphenylamine radical ##STR00056## wherein Ra and Rb independently of one another represent a linear or branched alkyl radical or halogen, n independently of the respective R represents an integer between 0 and 3, wherein the radical for n=0 is hydrogen, ##STR00057## iv) optionally one or more further colorants selected from the group consisting of the yellow and orange colorants of formulae (14), (15), (16), (17) and/or (18) ##STR00058## wherein the sum of the colorants ii) to iv) is >0.05% by weight and wherein the composition contains 0% to less than 30.0% by weight of further thermoplastic polymers, 0% to less than 0.02% by weight of carbon black, in addition to the colorants of groups ii) to iv) less than 0.1% by weight of further colorants and less than 0.1% by weight of white pigment.

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) There follows a detailed description of the invention with reference to working examples, the methods of determination described here being used for all corresponding parameters in the present invention description unless otherwise stated.

(4) A number of the substrate materials described hereinbelow contained customary additives such as mold release agents, heat stabilizers and/or UV absorbers. Preliminary tests were used to check and determine that these additives do not influence the signal of the LiDAR sensor.

Substrate 1: Comparative Example

(5) 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 (10)) and 0.0001% by weight of Macrolex Blue RR (colorant of formula (6)).

Substrate 2: Comparative Example

(6) 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 and 0.1% by weight of Macrolex Green G (colorant of formula (2)).

Substrate 3: Comparative Example

(7) 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 contains 0.134% by weight of Solvent Blue 36 (further colorant), 0.044% by weight of Macrolex Orange 3G (colorant of formula (15)) and 0.022% by weight of Amaplast Yellow GHS (Solvent Yellow 163, colorant of formula (16)).

Substrate 4: Comparative Example

(8) 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 5: Comparative Example

(9) 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 (14)), 0.00009% by weight of Macrolex Violet 3R (colorant of formula (10)) and 0.054% by weight of Tinopal (2,5-thiophenyldibis(5-tert-butyl-1,3-benzoxazene); optical brightener).

Substrate 6: Comparative Example

(10) 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% by weight of Kronos 2230 (titanium dioxide), 0.03% by weight of Sicotan Yellow K2107 (Pigment Brown 24, CAS 68186-90-3; further colorant), 0.022% by weight of Heucodur Blue 2R from Heubach (Pigment Blue 28, cobalt-aluminate blue spinel, CAS 1345-16-0; further colorant), 0.35% by weight of Macrolex Red EG (structure 8) and 0.063% by weight of Bayferrox 110 M from Lanxess AG (Fe.sub.2O.sub.3; CAS 001309-37-1).

Substrate 7: Comparative Example

(11) 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 8: Comparative Example

(12) Composition containing 99.96% by weight of polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm/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 9: Comparative Example

(13) 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 (11)).

Substrate 10: Inventive

(14) 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 (15)), 0.01% by weight of Macrolex Violet B (colorant of formula (11)) and 0.068% by weight of colorant of formula 4a/4b (1:1).

Substrate 11: Inventive

(15) 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 (10)) and 0.1% by weight of Macrolex Green 5B (colorant of formula (1)).

Substrate 12: Inventive

(16) 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 (6)) and 0.07% by weight of Macrolex Violet 3R (colorant of formula (10)).

Substrate 13: Comparative

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

Substrate 14: Comparative

(18) Acrylonitrile-butadiene-styrene copolymer (ABS) film having a thickness of 0.6 mm.

Substrate 15: Comparative

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

Substrate 16: Comparative

(20) Polyester made of cyclohexanedimethanol, terephthalic acid and tetramethylcyclobutanediol having the trade name Tritan from Eastman Chemical.

Substrate 17: Comparative

(21) 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 18: Comparative

(22) Polypropylene sheet having a thickness of 4 mm.

Substrate 19: Comparative

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

(24) Compounding

(25) The compounding of the components with the substrates 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 compositions were processed into 5 mm-thick injection molded polycarbonate sheets.

(26) Production of the Test Specimens

(27) Round sheets having dimensions of 80 mm×2 mm (diameter by height) were manufactured in optical quality. The melt temperature was 280° C. and the mold temperature was 80° C. The respective granulate was dried at 120° C. in a vacuum drying cabinet for 5 hours prior to processing.

(28) Employed LIDAR Sensor

(29) A Velodyne 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, is 903 nm.

(30) The essential characteristics of this sensor include:

(31) Vertical detection angle −15° to +150 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 300000 points/second are detected. The measurement accuracy achieved is about +/−3 cm, corresponding to 1 Sigma. The detectable measuring distance is between 1 mm and 100 metres. The energy requirement of the sensor system is 8 W of electrical power, corresponding to 0.7 A at 12 V. The overall dimensions of the sensor are: diameter 100 mm and height 65 mm.

(32) Method of Measurement

(33) The LiDAR sensor (Velodyne LiDAR VLP-16, 16 lasers having an operating wavelength of 903 nm) was positioned in a room and oriented such that a target object at a distance of exactly 4.5 m was detected. The accompanying software (Veloview from Velodyne) was set to “intensity mode”. In this setting the input signal reflected into the sensor is represented in a multicolour representation according to its intensity. The sensitivity of the representation was set to 0-100. Subsequently at a distance of about 100 mm plastic sheets having the thicknesses reported in table 1 were placed in front of the active sensor region so that both the output signal and the reflected input signal had to penetrate the wall thickness of the test sheet (FIG. 2). Using the representation of the target object in the evaluation software it is possible to perform an unambiguous assignment of the respective measured signal attenuation for the individual test specimens (plastic sheets) to the colour formulation used.

(34) The measured intensities of the recorded laser signal were between 0% and 100%. The lower the attenuation (weakening) of the signal, the more suitable is the formulation for LiDAR-assisted sensor applications in the automotive sector. The permeability of the respective sheet to IR radiation in the range from 800 nm to 2500 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.

(35) It was also investigated whether the signal of the LiDAR sensor changes according to the distance between the sensor and the cover. There was no relevant change in the signal of the LiDAR sensor in an investigated distance range from 5 to 50 cm.

(36) Results

(37) TABLE-US-00001 TABLE 1 Measured results for light transmission and LiDAR sensor suitability Intensity of LiDAR Total signal after Colorants and concentration traversing Examples Substrate other components of colorant Ty Thickness substrate 1 comparative substrate (6); (10) 0.00016% by 88.1%   .sup. 5 mm 70-90%     example 1 weight 2 comparative substrate (2); further 0.2% by 0% .sup. 2 mm 20-25%     example 2 colorant weight 3 comparative substrate (15); (16); further 0.199% by 0% .sup. 2 mm 35-40%     example 3 colorant weight 4 comparative substrate Carbon black 0.16% by 0% .sup. 5 mm 0% example 4 weight 5 comparative substrate (14); (10); 0.00015% by 0% 3.2 mm 0% example 5 TiO.sub.2 weight 6 comparative substrate TiO.sub.2; (8); further 0.465% by 0% 3.2 mm 0% example 6 colorants; Fe.sub.2O.sub.3 weight 7 comparative substrate — 0% by 23.8%   3.2 mm 0% example 7 weight 8 comparative substrate Carbon black 0.04% by 0% 2.0 mm 0% example 8 weight 9 comparative substrate Carbon black; 0.2% by 0% 2.0 mm 0% example 9 (11) weight 10 inventive substrate (4a/4b); (11); 0.126% by 0% 2.0 mm 70-90%     10 (15) weight 11 inventive substrate (10); (1) 0.2% by 0% 4.0 mm 50-70%     11 weight 12 inventive substrate (6); (10) 0.106% by 0.7%.sup.  2.0 mm 70-90%     12 weight 13 inventive Substrate (6); (10) 0.106% by <0.5% .sup.   4.0 mm 70-90%     12, two weight 2.0 mm sheets one behind the other 14 inventive substrate (4a/4b); (11); 0.126% by 0% 3.0 mm 70-90%     10 (15) weight 15 comparative substrate — — 46%  3.0 mm 0% example 13 16 comparative substrate — — 40%  0.6 mm 0% example 14 17 comparative substrate — — 87%  0.175 mm  5% example 15 18 comparative substrate — — 90%  2.3 mm 10-20%     example 16 19 comparative substrate — — 23%  2.3 mm 0% example 17 20 comparative substrate — — 61%  4.0 mm 0% example 18 21 comparative substrate — — 92.5%   2.7 mm 70-90%     example 19

(38) 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. 15) and ABS (Ex. 16) 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.

(39) Even modified polycarbonates such as siloxane-containing polycarbonates cannot be suitably combined with a LiDAR sensor. While BPA-containing polycarbonate has a good permeability to the LiDAR sensor, traces of pigments are sufficient to drastically attenuate permeability. It is thus known that carbon black has a high absorption over the entire spectral range, i.e. in the IR range too; nevertheless polycarbonate containing traces of carbon black still exhibits a residual transmission. Nevertheless, such compositions are unsuitable for combination with a LiDAR sensor (Example 9).

(40) 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 a thermoplastic matrix such as bisphenol A-based polycarbonate and/or polymethyl methacrylate is suitable for use in conjunction with a LiDAR sensor.

(41) 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.

(42) TABLE-US-00002 TABLE 2 MVR at 300° C. and 320° C., 1.2 kg loading for substrate materials 2, 3 and 11 Substrate Substrate Substrate material 2 material 3 material 11 300° 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