TRANSPARENT OPTICAL ELEMENT FOR A MOTOR VEHICLE

Abstract

A transparent optical element for a motor vehicle includes at least one first transparent layer of a polymer material. The optical element further has at least one second transparent layer including at least silicon, titanium, oxygen and nitrogen.

Claims

1: Transparent optical element for a motor vehicle comprising at least one first transparent layer of a polymer material, wherein the optical element further comprises at least one second transparent layer comprising at least silicon, titanium, oxygen and nitrogen.

2: Optical element according to claim 1, wherein the second layer comprises: one or more silicon-oxygen (Si—O) groups, one or more titanium-oxygen (Ti—O) groups, and one or more titanium-nitrogen (Ti—N) groups.

3: Optical element according to claim 1, wherein the second layer comprises a nitrogen derivative of titanium dioxide of formula TiO.sub.2-xN.sub.x with 0.001<x<1.00.

4: Optical element according to claim 3, wherein 0.01≦x≦0.10.

5: Optical element according to claim 1, wherein the second layer has a thickness of at most 100 nm.

6: Optical element according to claim 1, characterized in that the second layer is a hydrophilic layer.

7: Optical element according to claim 1, characterized in that the second layer is directly in physical contact with the first layer.

8: Optical element according to claim 1, characterized in that the second layer is obtained from at least one precursor PR1 containing oxygen and silicon, and at least one precursor PR2 containing oxygen and titanium.

9: Optical element according to claim 8, wherein the precursor PR1 is chosen from among a hydrocarbon silane, a fluorosilane, an organosilicate, a monomer of siloxane, silicon dioxide (SiO.sub.2), or one of their mixtures.

10: Optical element according to claim 9, wherein the hydrocarbon silane is tetramethysilane (TMS).

11: Optical element according to claim 9, wherein the fluorosilane is triethoxyfluorosilane (TEOF).

12: Optical element according to claim 9, wherein the organosilicate is chosen from among tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS), or one of their mixtures.

13: Optical element according to claim 9, wherein the monomer of siloxane is chosen from among hexamethyl disiloxane (HMDSO), tetramethyl disiloxane (TMDSO), octamethyl cyclotetrasiloxane (OMCTSO), or one of their mixtures.

14: Optical element according to claim 8, wherein the precursor PR2 is titanium tetraisopropoxide (TTIP) or one of its derivatives, titanium diisopropoxide bis(acetylacetonate) (TIPO), tetrabutyl orthotitanate (TBOT), tetrapropyl orthotitanate (TPOT), ammonium citratoperoxotitanate, tetrakis (9H-carbazole-9-yl-ethyl-oxy) titanium (Ti(OeCarb).sub.4), titanium dioxide (TiO.sub.2), or one of their mixtures.

15: Optical element according to claim 1, characterized in that the polymer material of the first layer comprises at least one polymer P chosen from among polycarbonate (PC), high temperature modified polycarbonate (PC-HT), polymethyl methacrylate (PMMA), polymethacrylimide (PMMI), cyclo-olefin polymer (COP), cyclo-olefin copolymer (COC), polysulfone (PSU), polyarylate (PAR), transparent polyamide (PA), or mixtures thereof.

16: Optical element according to claim 1, wherein the element is a closure outer lens of a lighting device.

17: Optical element according to claim 16, wherein the closure outer lens of a lighting device comprises an interior face and an exterior face, the first layer being the exterior face of the closure outer lens.

18: Lighting device of a motor vehicle, comprising the transparent optical element according to claim 1.

19: Method of fabrication of an optical element according to claim 1, wherein the second transparent layer is formed by at least one method chosen from among flame treatment, chemical vapor phase deposition, physical vapor phase deposition, and low-pressure deposition of an atomic layer.

Description

EXAMPLE

[0089] Fabrication of an Optical Element According to the Invention

[0090] The support used as the first layer is a transparent polycarbonate (PC), marketed by the company KUDEB under the brand M.AL2447. This polycarbonate is in the form of a rectangular sheet with the following dimensions: 15 cm in length, 10.5 cm in width, and 3.2 mm in thickness.

[0091] The following compounds were used: [0092] PR1: TEOS marketed by the company Sigma Aldrich under the brand 86578 purity ≧99% (CAS No. 78-10-4); [0093] PR 2: TTIP marketed by the company Sigma Aldrich under the brand 87560 purity≧97% (CAS No. 546-68-9); and [0094] The nitrogen used as the carrier and dopant gas is marketed by the company Air Liquide under the brand Alphagaz 1 Azote (CAS No. 7727-37-9).

[0095] The atmospheric plasma method is carried out.

[0096] The power of the generator powering the electrode is 1000 Watts. The mass flow rate of precursor PR1 TEOS is 1.5 ml.sub.s/min and the flow rate of precursor PR2 TTIP is 0.1 ml.sub.s/min, the flow rate of the dopant gas (N.sub.2) is 50 ml.sub.s/min, the flow rate of air (O.sub.2) is 100 mLm. The distance between the nozzle and the substrate is 15 mm. The rate of deposition is set at 100 mm per second.

[0097] One thus obtains a first layer of PC comprising a second layer of silicon, titanium, oxygen and nitrogen, deposited directly on its surface, the second layer having a thickness of around 85 nm.

[0098] This second layer is characterized by a structure of “core/shell” type, in which at least one particle of SiO.sub.2 is covered by a shell of nanoparticles of TiO.sub.2-xN.sub.x distributed on the surface of said particle of SiO.sub.2. The ratio of the mean diameter of the nanoparticles of TiO.sub.2-xN.sub.x to the mean diameter of the particles of SiO.sub.2 is around 1:10. This structure was characterized by using SEM/EDS (scanning electron microscope outfitted with a probe).

[0099] Various tests were conducted on the piece so treated:

1—Evaluation of the Anti-Condensation Effect:

[0100] The samples were placed above a kettle containing water for one minute and then laid flat and left for 10 minutes at 60° C. The samples were then left for 3 days at room temperature (23° C.) in an unconfined atmosphere. The test of exposure to the kettle is repeated (20 times). Observation shows there is no visible condensation in the zone treated according to the invention whereas it is very visible, with formation of droplets of condensed water, on a specimen not treated according to the invention.

2—Climate Cycles

[0101] The samples were placed: [0102] for 16 hours at 85° C. in an atmosphere with relative humidity of 95%, then [0103] for 3 hours at −20° C. in a dry atmosphere (relative humidity equal to 0%), and finally [0104] for 6 hours at 85° C. in an atmosphere with relative humidity less than 30%.
The cycle is repeated 5 times. No alteration or modification of the appearance of the treatment was observed.

3—Angle of Contact

[0105] The angle of contact with distilled water is less than 10°, showing the elevated level of hydrophilia of the second layer realized according to the invention (“superhydrophilia”). This characteristic is preserved after tests 1 and 2.