LIDAR reflective materials and marking systems

Abstract

This specification discloses a method for marking a dark surface with a dark LiDAR reflective material, and a marking composition comprising a dark LiDAR reflective material and a marking carrier. In particular, the dark LiDAR reflective material has a reflectance in the visible spectrum of electromagnetic radiation of 10% or less, and a reflectance in the near-IR and LiDAR spectra of electromagnetic radiation of 10% or more.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority under Section 119 of U.S. Patent Application No. 18 / 118,853, filed on 8 March 2023, which is incorporated herein by reference in its entirety.

[0002] Technical field This specification generally relates to methods for marking surfaces with LiDAR reflective materials, compositions of LiDAR reflective materials, and delivery systems comprising marking carriers and LiDAR reflective materials. [Background technology]

[0003] background LiDAR electromagnetic radiation (near infrared (IR), typically 905 nm or 1050 nm) is invisible to the human eye, but can be used by LiDAR detection devices to detect objects that reflect this electromagnetic radiation. However, this electromagnetic radiation is generally absorbed by dark-colored materials. Therefore, there is a need for methods to enable or enhance LiDAR detection by marking surfaces with dark-colored LiDAR reflective materials, and for compositions of LiDAR reflective materials that can be applied to surfaces, especially dark-colored surfaces. [Overview of the Initiative]

[0004] overview The first aspect is a method for marking a surface with a LiDAR reflective material, comprising selecting a surface to be marked and applying a LiDAR reflective material to the surface, wherein the LiDAR reflective material has a reflectance of 10% or less in the visible spectrum of electromagnetic radiation and a reflectance of 10% or more in the near-IR and LiDAR spectra of electromagnetic radiation.

[0005] A second embodiment includes the method of the first embodiment, wherein applying the LiDAR reflective material to the surface includes applying a delivery system comprising the LiDAR reflective material and a marking carrier to the surface.

[0006] A third embodiment includes the method of the first or second embodiment, wherein applying the LiDAR reflective material to the surface includes spraying the LiDAR reflective material onto the surface.

[0007] A fourth aspect includes the method of the first or second aspect, wherein applying the LiDAR reflective material to the surface includes applying the LiDAR reflective material to the surface using an applicator.

[0008] A fifth embodiment includes the method of the fourth embodiment, wherein the applicator is selected from at least one of the group consisting of stamps, brushes, markers, pens, styluses, rollers, and needles.

[0009] A sixth aspect includes a method according to the first or second aspect, wherein applying a LiDAR reflective material to a surface involves contacting the surface with a film encapsulating the LiDAR reflective material, the film being selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol-formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, or two or more combinations thereof, and comprising contacting the film and rupturing the film upon contact with the surface.

[0010] A seventh aspect includes the methods of the first to sixth aspects, wherein the LiDAR reflective material is applied to the surface as a unique marking design.

[0011] The eighth aspect includes the method of the seventh aspect, wherein the unique marking design is a glyph, a barcode, or a QR code (registered trademark).

[0012] The ninth aspect is a marking composition comprising a LiDAR reflective material and a marking carrier, wherein the LiDAR reflective material has a reflectance of 10% or less in the visible spectrum of electromagnetic radiation and a reflectance of 10% or more in the near-IR and LiDAR spectra of electromagnetic radiation.

[0013] A tenth aspect includes the marking composition of the ninth aspect, wherein the marking composition is encapsulated in a membrane selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, and combinations thereof.

[0014] An eleventh aspect includes a marking composition of the ninth aspect, wherein the composition further comprises a propellant selected from the group consisting of difluorochloromethane, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefin, low molecular weight hydrocarbons, butane, isobutene, propane, nitrous oxide, carbon dioxide, nitrogen, and combinations thereof.

[0015] A twelfth aspect comprises a marking composition according to the ninth to eleventh aspects, wherein the marking carrier is a gas selected from the group consisting of argon, nitrogen, oxygen, difluorochloromethane, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefin, chlorofluorocarbon, low molecular weight hydrocarbon, butane, isobutene, propane, nitrous oxide, carbon dioxide, and combinations thereof.

[0016] A thirteenth aspect comprises a marking composition of the ninth to eleventh aspects, wherein the marking carrier is a fluid selected from the group consisting of water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof.

[0017] The 14th embodiment includes a marking composition of the 9th to 11th embodiments, wherein the marking carrier is a polymer selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, and combinations thereof.

[0018] The 15th embodiment includes a marking composition of the 9th to 11th embodiments, wherein the marking carrier is a combination of gas and fluid, the gas being selected from the group consisting of argon, nitrogen, oxygen, difluorochloromethane, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefin, chlorofluorocarbon, low molecular weight hydrocarbon, butane, isobutene, propane, nitrous oxide, carbon dioxide, and combinations thereof, and the fluid being selected from the group consisting of water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof.

[0019] The 16th aspect is that the marking carrier is a combination of a fluid and a polymer, the fluid is selected from the group consisting of water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorone, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof, and the polymer is selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, and combinations thereof, and includes the marking composition of the 9th to 11th aspects.

[0020] The 17th aspect includes the marking composition of the 9th to 16th aspects, wherein the LiDAR reflective material has an average particle size of 5 nm to 15 nm and a blackness M of 130 to 170. y [[ID=z8]]

[0021] The 18th aspect includes the marking composition of the 9th to 17th aspects, wherein the LiDAR reflective material has an average particle size of 8 nm to 12 nm.

[0022] The 19th aspect includes the marking composition of the 9th to 18th aspects, wherein the LiDAR reflective material has a blackness M of 150 to 170. y

[0023] Aspect 20 includes the marking composition of Aspects 9 - 19 having a reflectivity in the visible spectrum of electromagnetic radiation that is 5% or less for the LiDAR reflective material.

[0024] Aspect 21 includes the marking composition of Aspects 9 - 20 having a reflectivity in the near - IR and LiDAR spectra of electromagnetic radiation that is 20% or more for the LiDAR reflective material.

[0025] Aspect 22 includes the marking composition of Aspects 9 - 21 where the LiDAR reflective material includes a dark pigment selected from the group consisting of CuO crystallites, carbon black, chromium ferrite oxides and derivatives thereof, or combinations of two or more of them.

[0026] Aspect 23 includes the marking composition of Aspect 22 where the dark pigment includes CuO crystallites having a (-111) / (111) intensity ratio that is 0.5 - 1.5.

[0027] Aspect 24 includes the marking composition of Aspect 22 where the dark pigment includes CuO crystallites having a (-111) / (111) intensity ratio that is 0.9 - 1.1.

[0028] These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description in conjunction with the drawings.

[0029] Brief Description of the Drawings The embodiments shown in the drawings are exemplary and illustrative in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the exemplary embodiments can be understood when read in conjunction with the following drawings in which like structures are indicated by like reference numerals.

Brief Description of the Drawings

[0030] [Figure 1A] It is a diagram schematically showing the LiDAR detection of a dark object. [Figure 1B]This diagram schematically illustrates how LiDAR detection of dark objects can be enhanced by marking the surface features of the dark objects. [Figure 1C] This diagram schematically illustrates how LiDAR detection of dark objects may include identifying additional information (e.g., object orientation) by marking them with patterns that encode information. [Figure 2] This graph shows the reflectance of carbon black, commercially available "Cool Black," and commercially available N-CuO-C and N-CuO-A pigments against different wavelengths. [Figure 3] This figure shows the blackness My values ​​of paints incorporating carbon black, commercially available "Cool Black," and commercially available N-CuO-C and N-CuO-A pigments, respectively. The inserted photograph illustrates the differences in blackness among these four samples. [Figure 4A] This is a schematic diagram of a demonstration setup using a robotic vehicle equipped with a 905nm 2D laser scanner, mimicking an autonomous vehicle. [Figure 4B] This figure shows a comparison of LiDAR intensities obtained by a robotic vehicle at an 8° position from painted panels incorporating carbon black, N-CuO-A, N-CuO-B, commercially available N-CuO-C, and cool black pigment, respectively. [Figure 4C] This is a schematic diagram of a demonstration in which a robotic vehicle crashes into a carbon black painted panel, with the LiDAR intensity threshold set to 100. [Figure 4D] This is a schematic diagram of a demonstration in which a robotic vehicle stops in front of a painted panel incorporating N-CuO-A pigment, with the LiDAR intensity threshold set to 100. [Modes for carrying out the invention]

[0031] Detailed explanation The methods disclosed and described herein involve marking a surface with a LiDAR-reflective material that reflects near-IR electromagnetic radiation, including LiDAR, having wavelengths between 800 nm and 2500 nm, but is also dark in color, such as dark brown or black. In embodiments, the methods disclosed and described herein include a delivery system comprising a LiDAR-reflective material and a marking carrier to which the LiDAR-reflective material can be applied to a surface, for example, a part of a vehicle, a part of a structure, a part of a document, a part of a fabric, etc., thereby enabling a near-IR and LiDAR detection system to detect a surface coated with the LiDAR-reflective material, even if both the surface and the LiDAR-reflective material are dark in color.

[0032] As used herein, the term "near-IR electromagnetic radiation" refers to electromagnetic radiation having wavelengths between 800 nm and 2500 nm.

[0033] As used herein, the term "LiDAR" refers to electromagnetic radiation having wavelengths between 905 nm and 1550 nm.

[0034] As used herein, the term "visible spectrum" refers to electromagnetic radiation having wavelengths between 350 nm and 750 nm.

[0035] Therefore, it is desirable that articles and structures can be marked with dark-colored LiDAR reflective materials. Dark-colored LiDAR reflective materials may be useful for marking dark-colored articles or structures when it is not desired that the markings be perceived by the naked eye. For example, dark-colored articles or structures that should be marked with images intended for a selected group rather than the general public may be marked by a delivery system that includes dark-colored LiDAR reflective material, so that the markings are perceived only by people who view the markings via LiDAR detection equipment. In this case, using conventional light-colored LiDAR reflective materials would allow anyone to see the markings. An exemplary use might be a dark-colored structure that is desired to be detectable by, for example, an autonomous vehicle or robot, but whose aesthetics are not disturbed by light-colored LiDAR reflective material.

[0036] To date, delivery systems for marking articles and structures with dark-colored LiDAR reflective materials incorporate light-colored LiDAR reflective material into a dark-colored carrier. Overall, these known systems generally fail to achieve a good balance between LiDAR reflectivity and dark color. This disclosure addresses this by providing a marking system for applying dark-colored LiDAR reflective material to articles and structures. The disclosure further provides a marking composition comprising dark-colored LiDAR reflective material and a marking carrier. The embodiments shown herein are illustrative and are not intended to be exhaustive or to limit the scope of the claimed subject matter. Various components of the marking system and methods for using the marking system are discussed herein.

[0037] LiDAR reflective material Dark LiDAR reflective materials that can be used in the systems and methods disclosed herein have a reflectance of 10% or less in the visible spectrum of electromagnetic radiation, and a reflectance of 10% or more in the near-IR and LiDAR spectra of electromagnetic radiation.

[0038] As mentioned above, the performance and accuracy of LiDAR detection depend on the intensity of LiDAR light reflected from an object and received by the LiDAR system. However, dark pigments and colorants (e.g., black pigments used in paints and other materials to provide dark colors) not only absorb visible electromagnetic radiation to provide dark colors, but also near-IR electromagnetic radiation with wavelengths greater than approximately 750 nm, including LiDAR electromagnetic radiation.

[0039] Commonly used dark pigments include carbon black and chromium iron oxide. Carbon black is the standard for "pure black" and has a blackness of approximately 165 (M) as measured by an X-Rite spectrophotometer. y Carbon black has the following properties: However, carbon black absorbs electromagnetic radiation in all of the visible, IR, and near-IR (LiDAR) spectra. Therefore, the LiDAR reflectivity of carbon black is close to 0. Thus, carbon black is not an ideal candidate for applications where IR or LiDAR reflectivity is desired. On the other hand, chromium iron oxide and its derivatives reflect IR and / or LiDAR light while exhibiting high absorption in visible light. Chromium iron oxide has a blackness of about 142 or less. The decrease in blackness of chromium iron oxide is significant compared to "pure black". Therefore, some commercially available pigment products containing chromium iron oxide and its derivatives are available as "cool black," and they have a reddish or bluish tint and are not considered "pure black".

[0040] Therefore, there is a need for a dark LiDAR reflective material that has a blackness similar to carbon black and also reflects near-IR and LiDAR electromagnetic radiation. To meet this need, the reflectivity of the dark LiDAR reflective material needs to increase very rapidly just outside the visible spectrum of electromagnetic radiation.

[0041] This sharp reflectivity or absorption transition is generally determined by the band gap of the material. As used herein, “band gap” generally refers to the energy difference (in electron volts or eV) between the upper part of the valence band (VB) and the lower part of the conduction band (CB). VB is the electron-filled band with the highest energy, and CB is the electron-depleted band with the lowest energy. The band gap is generally the threshold energy that VB electrons can absorb to move from VB to CB. In an optical system, threshold energy refers to the photon energy (E in eV) or wavelength (λ in nm) that can be absorbed by the material. Note that photon energy is inversely proportional to photon wavelength by the following equation.

[0042]

number

[0043] Therefore, without being bound by any particular theory, the band gap determines the wavelength or portion of the electromagnetic spectrum that a material can absorb. In light of this, promising dark-colored LiDAR reflective materials need a band gap of 1.5 eV to 1.8 eV (approximately 688 nm to 826 nm) to absorb visible-spectrum electromagnetic radiation and transmit or reflect LiDAR signals.

[0044] The band gap of a material can be manipulated, for example, by adding dopants in the case of semiconductors, reducing the particle size and shape in the case of nanoparticles, and controlling the crystal structure in the case of crystallites. One dark material of interest for band gap design for LiDAR applications is copper(II) oxide or copper oxide (CuO). It has been shown that the band gap of CuO can be tuned by various methods, including dopants, synthesis solvents and stoichiometry, nanoparticle size, and the shape and morphology of the nanostructure.

[0045] CuO is a monoclinic p-type semiconductor whose indirect band gap has been experimentally determined to be in the range of 1.2 eV to 2.2 eV. In its natural state, CuO is a black solid material. However, not all copper oxides possess this black color. Another stable oxide of copper is cuprous oxide (Cu₂O), which is a red solid in its natural state. CuO is a product of copper mining and a precursor to many other copper-containing products and compounds. CuO is commonly used as a pigment in ceramics, glazes, and other applications, and can be used to provide a high-quality black finish.

[0046] However, without manipulation, bulk CuO has a reported band gap of 2.0 eV, which is outside the 1.2 eV–1.8 eV range required to absorb electromagnetic radiation in the visible spectrum and reflect electromagnetic radiation in the near-IR and LiDAR spectra. Bulk CuO also has a blackness of 128 M y It has a blackness value that is significantly lower than the approximately 165 blackness of carbon black. When CuO is manipulated to have a band gap that easily reflects electromagnetic radiation in the near-IR or LiDAR spectrum, the color of CuO degrades to a brownish-black, which is unsuitable for certain applications such as automotive paints and fabrics.

[0047] On the other hand, without being bound by any particular theory, it is thought that CuO crystallites can be designed to have both excellent blackness in the visible spectrum of electromagnetic radiation and high reflectivity in the near-IR and LiDAR electromagnetic radiation wavelengths. CuO nanoparticles can be produced by processing CuO using mechanical methods such as ball milling and jet milling. These CuO nanoparticles are transmittance in the IR wavelength range and absorbance in the visible wavelength range. In addition, CuO nanoparticles may have reflectivity in the visible range of less than 10%, and therefore CuO nanoparticles act as a black pigment. It has been found that by manipulating CuO, it is possible to form CuO crystallites in which the absorbance transitions sharply around the 700 nm (approximately 1.77 eV) wavelength. These CuO crystallites have the same measured blackness as carbon black (M yAlthough it can be made indistinguishable from carbon black (value 135.5), these nanocrystalline CuO are 1500% more detectable by LiDAR than carbon black.

[0048] While not bound by any particular theory, the sharp transition of the CuO crystallite is thought to be due to the (-111) / (111) ratio of the crystal facets being approximately 1, and the crystal size of the (-111) plane being approximately 100 Å. In particular, the (111) plane is thought to have the maximum valence band (VB) edge with a band gap energy of 1.5 eV at around 1.2 eV (or -1030 nm), and the (-111) plane is thought to have a slightly larger maximum VB edge with a slightly larger band gap energy of 1.6 eV at around 2.1 eV (or -620 nm). Therefore, visual observation indicates that the (-111) plane is the main source of visible reflection because it starts from the larger maximum VB edge around 620 nm. Therefore, a smaller (-111) / (111) ratio or a smaller crystallite size of the (-111) plane may result in a higher blackness level, while a larger ratio and crystallite size are advantageous for near-IR reflectivity. In other words, the (-111) / (111) plane ratio and the average crystallite size of the crystallite phase are two important indicators that serve as guidelines.

[0049] Here, embodiments of the LiDAR reflective material used to form the marking composition are described.

[0050] Generally, LiDAR reflective materials have a reflectance of 10% or less in the visible spectrum of electromagnetic radiation, and a reflectance of 10% or more in the near-IR and LiDAR spectra of electromagnetic radiation.

[0051] In the embodiment, the LiDAR reflective material that can be used to form the marking composition has a reflectance in the visible spectrum of electromagnetic radiation of 10% or less, for example, 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, 0.5% or less, 0.1% or less.

[0052] In one embodiment, the LiDAR reflective material described herein has a reflectance in the near-IR and LiDAR spectra of electromagnetic radiation of 10% or more, for example, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, or 60% or more. In one or more embodiments, the LiDAR reflective material has a reflectance in the near-IR and LiDAR spectra of electromagnetic radiation of 10% or more and 80% or less, for example, 15% or more and 80% or less, 20% or more and 80% or less, 25% or more and 80% or less, 30% or more and 80% or less, 35% or more and 80% or less, 40% or more and 80% or less, 45% or more and 80% or less, 50% or more and 80% or less, 55% or more and 80% or less, 60% or more and 80% or less, 65% or more and 80% or less, 70% or more and 80% or less, 75% or more and 80% or less.

[0053] In some embodiments, the LiDAR reflective material has a blackness (My) of 130 to 170, for example, 135 to 170, 140 to 170, 145 to 170, 150 to 170, 155 to 170, 160 to 170, 165 to 170, 130 to 165, 135 to 165, 140 to 165, 145 to 165, 150 to 165, 155 to 165, or 160 to 165.

[0054] In some embodiments, the LiDAR reflective material has a wavelength of 5 nm to 2,000 nm, for example, 6 nm to 2,000 nm, 7 nm to 2,000 nm, 8 nm to 2,000 nm, 9 nm to 2,000 nm, 10 nm to 2,000 nm, 11 nm to 2,000 nm, 12 nm to 2,000 nm, 13 nm to 2,000 nm, 14 nm to 2,000 nm, 15 nm to 2,000 nm, 50 nm to 2,000 nm, 100 nm to 2,000 nm, 200 nm to 2,000 nm, 500 nm to 2,000 nm, 1,000 nm to 2,000 nm, 1 It may have an average particle size of 500 nm to 2,000 nm, 5 nm to 1,500 nm, 6 nm to 1,500 nm, 7 nm to 1,500 nm, 8 nm to 1,500 nm, 9 nm to 1,500 nm, 10 nm to 1,500 nm, 11 nm to 1,500 nm, 12 nm to 1,500 nm, 13 nm to 1,500 nm, 14 nm to 1,500 nm, 15 nm to 1,500 nm, 50 nm to 1,500 nm, 100 nm to 1,500 nm, 200 nm to 1,500 nm, or 500 nm to 1,500 nm, 1,000 nm to 1,500 nm, etc.

[0055] Here, we describe an embodiment of a LiDAR reflective material in which the dark pigment contains CuO crystallites. In one embodiment, the CuO crystallites have a (-111) / (111) ratio of 0.8 to 1.3, for example, 0.9 to 1.3, 1.0 to 1.3, 1.1 to 1.3, 1.2 to 1.3, 0.8 to 1.2, 0.9 to 1.2, 1.0 to 1.2, 1.1 to 1.2, 0.8 to 1.1, 0.9 to 1.1, 1.0 to 1.1, 0.8 to 1.0, 0.9 to 1.0, or 0.8 to 0.9, etc.

[0056] The band gap of CuO is reduced by reducing the size of CuO crystallites to, for example, the average grain size disclosed below. In embodiments, the band gap measured by X-ray photoelectron spectroscopy (XPS) of CuO nanoparticles is 1.2 eV to 1.8 eV, for example, 1.3 eV to 1.8 eV, 1.4 eV to 1.8 eV, 1.5 eV to 1.8 eV, 1.6 eV to 1.8 eV, 1.7 eV to 1.8 eV, and 1.2 eV to 1.7 eV, for example, 1.3 eV to 1.7 eV, 1.4 eV to 1.7 eV, 1.5 eV to 1.7 eV. 0.7eV or less, 1.6eV to 1.7eV, 1.2eV to 1.6eV, for example, 1.3eV to 1.6eV, 1.4eV to 1.6eV, 1.5eV to 1.6eV, 1.2eV to 1.5eV, for example, 1.3eV to 1.5eV, 1.4eV to 1.5eV, 1.2eV to 1.4eV, for example, 1.3eV to 1.4eV, or 1.2eV to 1.3eV.

[0057] While not bound by any particular theory, it is generally believed that the smaller the average crystal size of CuO nanoparticles, the smaller the band gap of the CuO nanoparticles. Therefore, by reducing bulk CuO particles to CuO nanoparticles according to the embodiments disclosed and described herein, the band gap of the CuO nanoparticles is within the range that reflects electromagnetic radiation in near-IR and LiDAR spectra, for example, having a band gap of 1.5 eV to 2.0 eV.

[0058] In embodiments, the CuO crystallites are 5 nm or more and 15 nm or less, for example, 6 nm or more and 15 nm or less, 7 nm or more and 15 nm or less, 8 nm or more and 15 nm or less, 9 nm or more and 15 nm or less, and 10 nm or more. 15nm or less, 11nm or more and 15nm or less, 12nm or more and 15nm or less, 13nm or more and 15nm or less, 14nm or more and 15nm or less, 5nm or more and 14nm or less, 6nm or more and 14nm or less, 7nm or more 14nm or less, 8nm or more and 14nm or less, 9nm or more and 14nm or less, 10nm or more and 14nm or less, 11nm or more and 14nm or less, 12nm or more and 14nm or less, 13nm or more and 14nm or less, 5nm or less Upper 13nm or less, 6nm or more and 13nm or less, 7nm or more and 13nm or less, 8nm or more and 13nm or less, 9nm or more and 13nm or less, 10nm or more and 13nm or less, 11nm or more and 13nm or less, 12nm or more The average particle size may be 13nm or less, 5nm to 12nm, 6nm to 12nm, 7nm to 12nm, 8nm to 12nm, 9nm to 12nm, 10nm to 12nm, 11nm to 12nm, 5nm to 11nm, 6nm to 11nm, 7nm to 11nm, 8nm to 11nm, 9nm to 11nm, 10nm to 11nm, 5nm to 10nm, 6nm to 10nm, 7nm to 10nm, 8nm to 10nm, 9nm to 10nm, 5nm to 9nm, 6nm to 9nm, 7nm to 9nm, 8nm to 9nm, 5nm to 8nm, 6nm to 8nm, 7nm to 8nm, 5nm to 7nm, 6nm to 7nm, or 5nm to 6nm.

[0059] In embodiments, the blackness My (i.e., the scale of blackness) of CuO crystallites is 130 to 170, for example, 135 to 170, 140 to 170, 145 to 170, 150 to 170, 155 to 170, 160 to 170, 165 to 170, 130 to 165, 135 to 165, 140 to 165, 145 to 165, 150 to 165, 155 to 165, or 160 to 165.

[0060] The copper oxide crystallites according to the embodiments disclosed and described herein have a reflectance in the visible spectrum of electromagnetic radiation of 10.0% or less, for example, 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, or 0.5% or less.

[0061] Copper oxide crystallites according to embodiments disclosed and described herein have reflectance in the near-IR and LiDAR spectra of electromagnetic radiation of 10% or more, for example, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, or 60% or more. In one or more embodiments, copper oxide crystallites have reflectance in the near-IR and LiDAR spectra of electromagnetic radiation of 10% to 60%, for example, 15% to 60%, 20% to 60%, 25% to 60%, 30% to 60%, 35% to 60%, 40% to 60%, 45% to 60%, 50% to 60%, or 55% to 60%.

[0062] By combining CuO crystallites with carbon black, chromium iron oxide and its derivatives, or combinations thereof, the blackness or near-IR reflectivity of dark pigments can be further improved. Herein, an embodiment of a LiDAR reflective material is described in which the dark pigment comprises CuO crystallites and at least one selected from the group consisting of carbon black, chromium iron oxide and its derivatives, or combinations thereof.

[0063] In some embodiments, the dark pigment is a core-shell system comprising an inner shell and an outer shell. The core consists of carbon black or chromium iron oxide and its derivatives, and the shell consists of CuO crystallites. The CuO crystallite shell reflects near-IR and LiDAR radiation and absorbs visible radiation. When the pigment has a core made of carbon black, residual visible radiation passing through the CuO crystallite shell is further absorbed by the carbon black core, which can result in increased blackness. When the pigment has a core made of chromium iron oxide and its derivatives, residual near-IR and LiDAR radiation passing through the CuO crystallite shell is reflected by the chromium iron oxide core, which can result in increased reflectivity at near-IR and LiDAR wavelengths.

[0064] Marking carrier LiDAR reflective materials are generally solid. While fine powders of LiDAR reflective materials can be applied directly to a surface by brushing, electrostatic spraying, etc., pigments are often used with additional marking carriers to expand the available means for applications such as painting and wet spraying. Therefore, the marking methods described herein may further include applying a delivery system comprising the LiDAR reflective material and marking carriers to a surface. The marking carriers disclosed herein are agents that assist and facilitate the application of LiDAR reflective materials to selected surfaces.

[0065] Generally, surface marking is a method that involves exposing the surface of an object to a layer of marking material (e.g., LiDAR reflective material) and retaining the layer of marking material on the object's surface for an intended application (e.g., LiDAR detection). A wide variety of surface marking methods are available, ranging from simple methods such as pen writing, brush painting, and aerosol spraying to more advanced techniques such as thermal spraying, solution deposition, laser deposition, electrochemical deposition, and electrostatic deposition. However, a reliable marking method depends on the type of surface selected (e.g., metallic or nonmetallic) and its properties (e.g., porous, hydrophilic, or hydrophobic). Furthermore, different methods or techniques require different material states (liquid, solid (including molten), and gaseous) as well as different material properties (concentration, viscosity, density, melting point, boiling point, etc.). For example, simple spraying generally requires marking material in a liquid state, while thermal spraying requires marking material in a molten state.

[0066] After applying a marking material to a surface, many applications, including LiDAR detection, require the marking layer to be permanently or temporarily retained on the surface for minutes, hours, or days for the intended application to function. Retention of the marking material on a surface can be achieved through physical interactions (e.g., electrostatic interactions) or chemical bonding (e.g., surface modification). For example, ultrafine carbon black powder can adhere to a glass surface using electrostatic forces, and hydrophilic surface modifiers can form hydrogen bonds to connect pigments to hydroxyl groups on a glass surface. Therefore, several marking carriers may be required depending on the intended application.

[0067] According to the embodiment, the marking carrier may be a fluid, a polymer, a gas, or a combination thereof. Each of these marking carriers will be described in more detail below.

[0068] Embodiments of fluid marking carriers are described below. The LiDAR reflective material disclosed above can be incorporated into a fluid marking carrier, such as a solvent, which allows the LiDAR reflective material to be sprayed or applied using a stamp, brush, marker, pen, stylus, roller, needle, etc. In some embodiments, the solvent containing the LiDAR reflective material may be contained in a pressurized vessel or in a vessel further containing a propellant, so that the solvent containing the LiDAR reflective material can be applied as an aerosol (similar to spray paint). In other embodiments, the solvent containing the LiDAR reflective material may be absorbed into an absorbent material so that it can be applied by a physical applicator such as a wooden or rubber stamp. In embodiments, the stamp may have a unique design, such as a glyph, QR code, barcode, etc. Other marking carriers may contain a liquid solvent containing the LiDAR reflective material so that the solvent containing the LiDAR reflective material can be applied by a brush, marker, pen, etc. The viscosity of the liquid solvent containing the LiDAR reflective material may vary depending on the desired end application. In some embodiments, the liquid solvent containing the LiDAR reflective material may have high viscosity and appear as a sticky or slimy substance. By incorporating the LiDAR reflective material into the solvent, the application of the LiDAR reflective material to an article or structure can be controlled, thereby making it easier for the user to apply the LiDAR reflective material in the design. Thus, the image or design is barely visible to the naked eye but is easily recognized by a LiDAR detection device.

[0069] Forming a solvent containing LiDAR reflective material involves combining LiDAR reflective material with one or more solvent systems to form a LiDAR reflective material-doped solvent. In some embodiments, the LiDAR reflective material-doped solvent may be one or more LiDAR reflective material-doped suspensions or one or more LiDAR reflective material-doped suspension gels. For example, in embodiments, the solvent may be a ketone (such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, etc.), an ester (such as ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, etc.), an alcohol (such as ethanol, butanol, propanol, etc.), or a glycol ether (such as ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, etc.). Of course, a combination of solvents may be used as desired. To enhance the properties of the solvent, various additives such as thickeners, stabilizers, emulsifiers, and dispersants can be included in the solvent.

[0070] The solvent containing the LiDAR reflective material may also be administered and encapsulated in a membrane for long-distance application of the LiDAR reflective material. Optionally, the membrane may be designed to break upon impact with an article or structure at high force, so that the solvent containing the LiDAR reflective material is applied to the article or structure upon impact. These membranes may be made from plastics (such as PET or polystyrene) or gelatinous membranes. The solvent-filled membrane can then be delivered by a pressurized delivery device, which allows the article or structure to be marked with the LiDAR reflective material-containing solvent at a distance.

[0071] In embodiments where the marking carrier is a fluid, the marking carrier is a fluid selected from the group consisting of water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof.

[0072] The fluid marking carrier has a boiling point at 760 mm Hg that is between 0°C and 300°C, for example, between 20°C and 280°C, between 40°C and 260°C, between 60°C and 240°C, between 80°C and 200°C, between 100°C and 180°C, or between 120°C and 160°C.

[0073] LiDAR reflective materials can also be applied using polymer marking carriers, which physically or chemically form a network to hold the LiDAR reflective material as a film. The polymer marking carriers can form a network through exposure to heat or light. Embodiments of polymer marking carriers are described below.

[0074] In embodiments where the marking carrier is a polymer, the marking carrier may be a polymer selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol-formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, and combinations thereof.

[0075] The polymer marking carrier has a tensile strength of 10 MPa to 220 MPa, for example, 20 MPa to 200 MPa, 30 MPa to 180 MPa, 40 MPa to 160 MPa, 50 MPa to 140 MPa, 60 MPa to 120 MPa, or 70 MPa to 100 MPa.

[0076] The polymer marking carrier includes transmittance in the near-IR and LiDAR spectra of electromagnetic radiation of 90% or more, for example, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more.

[0077] Dry LiDAR reflective material or powder can be applied using a gaseous marking carrier in the same manner as described above. For example, LiDAR reflective material can be applied to tag a surface for LiDAR visibility by dry aerosol. In embodiments, the above film can encapsulate dry LiDAR reflective material that can be delivered over a certain distance, with or without a marking carrier. Embodiments of a gaseous marking carrier are described here.

[0078] In embodiments where the marking carrier is a gas, the gas may be selected from the group consisting of argon, nitrogen, oxygen, difluorochloromethane, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefin, chlorofluorocarbon, low molecular weight hydrocarbons, butane, isobutene, propane, nitrous oxide, carbon dioxide, and combinations thereof. Non-limiting uses of the gaseous marking carrier include thermal spraying processes that use the gas to support dry LiDAR reflective material and / or provide an energy source for flame, plasma, etc.

[0079] In some embodiments, the marking carrier may be a combination of fluid and polymer, or a combination of fluid and gas. By combining a fluid and polymer, a polymer gel can be formed that gives the LiDAR reflective film enhanced coverage and elasticity. Certain solvents can also be used to attenuate or enhance the fracture toughness of the polymer. The solvent can then be removed. By combining a fluid and gas, the spray particle size can be refined, resulting in a smaller particle size and a smoother finish, thus reducing the scattering loss of reflected LiDAR radiation. Embodiments of fluid-polymer marking carriers are described here.

[0080] In embodiments where the marking carrier is a combination of fluid and polymer, the fluid is selected from the group consisting of water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof, and the polymer is gelatin, polyethylene terephthalate (PET: polyethylene The fluid-polymer combination may be selected from the group consisting of terephthalate, polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol-formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, and combinations thereof. Non-limiting examples of fluid-polymer combinations include polyethylene glycol and water, polyurethane and dimethyl sulfoxide, polymethyl methacrylate, polystyrene and ethyl acetate, and the like.

[0081] The fluid-polymer marking carrier includes transmittance in the near-IR and LiDAR spectra of electromagnetic radiation of 90% or more, for example, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more.

[0082] Here, we will describe an embodiment of a fluid-gas marking carrier. In embodiments where the carrier is a combination of gas and fluid, the gas may be selected from the group consisting of argon, nitrogen, oxygen, difluorochloromethane, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefin, chlorofluorocarbon, low molecular weight hydrocarbons, butane, isobutene, propane, nitrous oxide, carbon dioxide, and combinations thereof, and the fluid may be selected from the group consisting of water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof. Non-limiting exemplary uses of fluid-gas carriers include purging oxygen contained in a solvent to reduce the degradation of LiDAR reflective materials.

[0083] Additionally, in embodiments, the marking carrier portion may be physically blended with the LiDAR reflective material, or the marking carrier portion may be chemically bonded with the LiDAR reflective material. In particular, if the marking carrier includes a polymer portion and a fluid portion, the polymer portion can be chemically bonded to the LiDAR reflective material to form a polymer shell around the LiDAR reflective material. In some cases, the polymer shell can be used as a surface modifier to adhere LiDAR reflective core shell particles to the surface. In embodiments in which such a polymer shell is formed around the LiDAR reflective material, the polymer can transmit LiDAR radiation.

[0084] Delivery system The delivery systems disclosed herein enable the tuned application of LiDAR reflective materials to various types of surfaces for specific purposes. Non-limiting examples of surfaces include natural or synthetic fabrics, paper, plastics, concrete or rock, metals, elastomers, and the like.

[0085] A delivery system for applying LiDAR reflective material to a selected surface comprises the LiDAR reflective material and marking carrier described above. The total weight ratio of the marking carrier in the delivery system is 0.01% to 99% by weight, for example, 0.1% to 99% by weight, 1% to 99% by weight, 5% to 99% by weight, 10% to 99% by weight, 20% to 99% by weight, 40% to 99% by weight, 60% to 99% by weight, 80% to 99% by weight, 90% to 99% by weight, 95% to 99% by weight, 0.1% to 80% by weight, 1% to 80% by weight, 5% to 80% by weight, 10% to 80% by weight, 20% to 80% by weight, 40% to 80% by weight, 60% to 80% by weight, 0.1% by weight or less. The following are the weights: 60% or less, 1% to 60%, 5% to 60%, 10% to 60%, 20% to 60%, 40% to 60%, 0.1% to 40%, 1% to 40%, 5% to 40%, 10% to 40%, 20% to 40%, 0.1% to 20%, 1% to 20%, 5% to 20%, 10% to 20%, 0.1% to 10%, 1% to 10%, 5% to 10%, 0.1% to 5%, 1% to 5%, or 0.1% to 3%.

[0086] The delivery system of the embodiment may further include additives such as thickeners, stabilizers, emulsifiers, surfactants, plasticizers, binders, and dispersants to enhance the properties of the marking carrier. Surfactants and emulsifiers can control and stabilize the aggregation or deaggregation of LiDAR reflective material in the delivery system. Thickeners and plasticizers can rheologically adjust the delivery system to provide desirable processability, coverage, and stability of the LiDAR reflective marking. Binders can enable the formation of a film of LiDAR reflective material that adheres to the surface when the delivery system is applied to a surface and dries. Stabilizers can suppress degradation and extend the life of the marking. Dispersants can improve the formation of particles or droplets of LiDAR reflective material in the delivery system and maintain the separation of LiDAR reflective particles or droplets in the delivery system to prevent their settling or aggregation.

[0087] Non-exclusive examples of thickeners include palygorskite, fumed silica, hydroxyethylcellulose, methylcellulose, fibrillated cellulose, methyl methacrylate, 2-ethylhexyl methacrylate, butanediol diacrylate, vinyl acetate, methacrylic acid esters, polyethylene glycol, gum, alginate, poly(butylene oxide), poly(ethylene oxide), and combinations thereof.

[0088] Non-exclusive examples of stabilizers include tris(2,4-di-tert-butylphenyl) phosphite, butyrate hydroxytoluene, nickel phenolate, calcium stearate, calcium oxide, zinc oxide, magnesium oxide, isothiazolinone, benzophenone, benzotriazole, hydroxyphenyl-triazine, oxanilide, p-phenylenediamine, and combinations thereof.

[0089] Non-exclusive examples of surfactants include alcohol ethoxylates, sulfosuccinates, polyethersiloxanes, acetylenediols, polyoxyethylene glycol octylphenol ethers, polyoxyethylene glycol sorbitan alkyl esters, polyethylene glycols, polypropylene glycols, perfluorooctanesulfonates, lignosulfonates, dioctyl sodium sulfosuccinates, and combinations thereof.

[0090] Non-limiting examples of plasticizers include diisodecyl phthalate, diisoundecyl phthalate, ditridecyl phthalate, bis(2-ethylhexyl) adipate, dibutyl sebacate, butylbenzyl phthalate, bis(2-ethylhexyl) phthalate, diisononyl phthalate, bis(2-propylheptyl) phthalate, polycarboxylates, and combinations thereof.

[0091] Non-exclusive examples of binders include acrylic resins, alkyd resins, latex, phenolic resins, urethane resins, epoxy resins, and combinations thereof.

[0092] Non-exclusive examples of dispersants include sodium pyrophosphate, sodium citrate, sodium tartrate, sodium succinate, sodium polyacrylate, sodium polysulfonate, ammonium polyacrylate, ammonium citrate, glyceryl trioleate, phosphate esters, poly(acrylic acid), poly(methacrylic acid), poly(ethyleneimine), and combinations thereof.

[0093] The total weight ratio of additives in the delivery system is between 0.1% and 20.0% by weight, for example, between 0.5% and 18.0% by weight, between 1.0% and 15.0% by weight, between 1.5% and 12.0% by weight, between 1.0% and 10.0% by weight, between 2.5% and 8.0% by weight, or between 3.0% and 5.0% by weight.

[0094] The delivery system according to the embodiment may further comprise a propellant that pressurizes the delivery system and enables the delivery system to be applied in aerosol form. Non-limiting examples of propellants include methane, propane, n-butane, isobutene, ethanol, kerosene, hydrogen, oxygen, nitrogen, nitrous oxide, carbon dioxide, chlorofluorocarbon dichlorodifluoromethane, diesel, gasoline, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefins, and combinations thereof.

[0095] The weight ratio of the propellant in the delivery system of the embodiment is 5% by weight or more and 30% by weight or less, for example, 5% by weight or more and 20% by weight or less, 5% by weight or more and 10% by weight or less, 10% by weight or more and 30% by weight or less, 10% by weight or more and 20% by weight or less, or 20% by weight or more and 30% by weight or less.

[0096] In one or more embodiments, the delivery system may be pressurized to an operating pressure of 1.5 atm to 8 atm, for example, 2 atm to 6 atm or 3 atm to 5 atm.

[0097] The delivery system may further comprise, according to embodiments, adjustment means for adjusting the volume ratio of LiDAR reflective material to marking carrier, the adjustment means comprising at least a gas, a fluid, or a combination thereof. In such embodiments, the gases include argon, nitrogen, oxygen, difluorochloromethane, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefin, chlorofluorocarbon, low molecular weight hydrocarbons, butane, isobutene, propane, nitrous oxide, carbon dioxide, and combinations thereof; the fluids include water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether esters, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof.

[0098] Applicable The application (surface marking) methods using LiDAR reflective materials disclosed herein include selecting a surface to be marked and applying the LiDAR reflective material to the surface, wherein the LiDAR reflective material has a reflectance in the visible spectrum of electromagnetic radiation of 10% or less, and a reflectance in the near-IR and LiDAR spectra of electromagnetic radiation of 10% or more. Specifically, embodiments of applying LiDAR reflective material to a surface include applying a delivery system comprising the LiDAR reflective material and a marking carrier to the surface by spraying a film containing the LiDAR reflective material to the surface using an applicator, wherein the film breaks upon contact with the surface, or by contact, or a combination thereof. Non-limiting examples of applications according to embodiments include marking a surface with a unique design, pattern, image, or mark such as a glyph, barcode, or QR code for identification purposes, by using an applicator, etc. One or more embodiments include marking a large free-form surface area by spraying for economic and efficiency purposes, and marking the surface with a film containing a LiDAR reflective material, which breaks upon contact with the surface for the purpose of movable marking.

[0099] Here, we describe an embodiment in which an applicator is used to apply a delivery system comprising LiDAR reflective material and a marking carrier to a surface.

[0100] According to the embodiment, the applicator may be selected from at least one of the group consisting of stamps, brushes, markers, pens, styluses, rollers, and needles. According to the embodiment, the applicator can be used to apply a delivery system comprising LiDAR reflective material, the delivery system being in the form of a solution, suspension, emulsion, gel, powder, film, fiber, filament, or a combination thereof.

[0101] Applicators can apply LiDAR reflective material in various forms. Non-limiting examples include using a brush to apply LiDAR reflective material in powder form to a surface, the powder which may be deposited on the surface by adhesion or electrostatic force; using a pen to apply LiDAR reflective material in solution form to an absorbent surface such as paper, the LiDAR reflective material solute which may be deposited on or below the surface as the solvent evaporates; using a stamp with a specific pattern to apply LiDAR reflective material in concentrated suspension form to a semi-absorbent surface such as leather, the LiDAR reflective material suspension which may be deposited on a semi-absorbent surface displaying a specific pattern; using a roller to deposit LiDAR reflective material in film onto a surface, the film which may be adhered to the surface using adhesive or electrostatic force; or using a roller to spread viscous LiDAR reflective material onto a non-absorbent surface such as metal or plastic, the viscous LiDAR reflective material which may adhere to the surface. Applicators may be used to apply unique markings, such as glyphs, barcodes, and QR codes, to a surface that can be scanned by a LiDAR detection device but is invisible to the naked eye when the surface is dark, such as in a delivery system. These unique markings can provide hidden identification information to a user scanning the unique marking. In embodiments, the unique markings can link a user scanning the unique marking with a LiDAR detection device to additional information about the surface, such as by linking a QR code to a website.

[0102] Referring to Figures 1A, 1B, and 1C, these figures provide illustrations of marking the surface of a dark object 100 with LiDAR reflective marks 121 or LiDAR reflective pattern 141 for the purpose of enhancing LiDAR detection or identification. For example, as shown in Figure 1A, a cubic object 100 has, to the human eye, a dark surface 110, corners 120, and edges 130. However, because the dark surface 110 absorbs LiDAR light and reduces the intensity of LiDAR reflection, the LiDAR sensor may mischaracterize the cubic object 100, detecting an indistinct object 200 with a surface 210, or failing to detect the dark object 100 at all.

[0103] To provide or enhance LiDAR detection of cube 100, the corners 120 of cube 100 can be marked with LiDAR reflective marks 121 formed by the LiDAR reflective delivery system disclosed herein, as shown in Figure 1B (left). The LiDAR reflective marks 121 reflect LiDAR radiation, enabling the identification of the corners 220 of the detected object 200 by the LiDAR detection device, as shown in Figure 1B (right). However, the marked corners 121 are indistinguishable to the human eye from the dark surface 110. Based on the surface 210 and corner 220 observed by the LiDAR detection device, the edges 230 of the detected object 200 can be predicted. By identifying its surface 210, corner 220, and edges 230, the LiDAR-detected object 200 accurately depicts the cube object 100.

[0104] Furthermore, the surface 110 of the cubic object 100 can be marked with a unique LiDAR reflective pattern 141, as shown in Figure 1C. The unique LiDAR reflective pattern 141 has a unique pattern that contains information. For example, but not limited to, the unique LiDAR reflective pattern 141 may be an arrow that identifies the orientation of the object 100, a QR code that identifies the content contained within the object 100, a trademark, or other information-containing pattern that can communicate a message to a robot, autonomous vehicle, or other observer using a LiDAR detection device. The unique LiDAR reflective pattern (arrow) 141 shown in Figure 1C is light in color, but this is for illustrative purposes only, and it should be understood that the unique LiDAR reflective pattern 141 is not distinguishable from a dark surface 110 with the naked human eye. The unique LiDAR reflective pattern 141 reflects LiDAR light, enabling a LiDAR sensor to identify the mark 240 on the surface 210 of the detected object 200 and the information contained therein.

[0105] Additionally, the unique LiDAR reflection pattern 141 may, in an embodiment, be an information encoding pattern in which information is encoded by characters, images, barcodes, glyphs, QR codes, or any other format. As shown in Figure 1C, the unique LiDAR reflection pattern 141 can provide information such as the orientation or identification information of an object, enabling a LiDAR detection device to detect the orientation or identity of an object. Herein, an embodiment is described in which a delivery system comprising LiDAR reflective material and a marking carrier is applied to a surface by spraying.

[0106] Methods for spraying LiDAR reflective material may further include introducing a propellant into a delivery system, adjusting the volume ratio of LiDAR reflective material to a marking carrier, pressurizing the delivery system, or a combination thereof. Spraying methods are applicable to various forms of LiDAR reflective material. Non-limiting examples include aerosol spraying of a suspension of LiDAR reflective material or aerosol spraying of a dry powder of LiDAR reflective material. Spraying for application of LiDAR reflective material enables large-area surface marking. Non-limiting examples include spraying LiDAR reflective material onto portions of the surface of dark-colored objects (e.g., doors or body panels of dark-colored vehicles) to improve LiDAR detection and thus road safety, or spraying LiDAR reflective material onto portions of the surface of structural or building materials (e.g., support columns or reinforcing bars) for non-contact or non-destructive structural integrity and fatigue monitoring, including surface cracks, deformation, erosion, etc.

[0107] The spraying may be carried out using at least one of the group consisting of air sprayers, electrostatic powder sprayers, powder sprayers, ultrasonic spray coaters, plasma spray coaters, and electric arc spray coaters. For example, but not limited to, LiDAR reflective material in the form of fibers can be sprayed to form a nonwoven fabric. Furthermore, LiDAR reflective fibers can also be sprayed onto the surface of a fabric article, followed by a flock printing process to form a LiDAR reflective fabric.

[0108] Here, we describe an embodiment in which a LiDAR reflective material is applied to a surface by contacting it with a film that encapsulates the LiDAR reflective material, the film of which breaks upon contact with the surface. The encapsulated LiDAR reflective material may be in the form of a solution, suspension, emulsion, gel, powder, film, fiber, filament, or a combination thereof.

[0109] Bringing a membrane into contact with a surface can be achieved by physically projecting or mechanically firing the LiDAR reflective material encapsulated within the membrane. Upon contact, the impact force ruptures the membrane, releasing the encapsulated LiDAR reflective material, thereby marking the contact surface. Mechanical firing can be achieved by pressurized delivery devices that allow marking of an object or surface with LiDAR reflective material from a certain distance, or by slings, catapults, trebuchets, bows, etc.

[0110] The impact force required to rupture the membrane depends on the elasticity and brittleness of the membrane, which can vary depending on the membrane's composition. As described above, in embodiments, the membrane is selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, nylon, polycarbonate, epoxy, phenol-formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, and combinations thereof. The elasticity of these polymer materials can be modified using plasticizers, but are not limited to, diisodecyl phthalate, diisoundecyl phthalate, ditridecyl phthalate, bis(2-ethylhexyl) adipate, dibutyl sebacate, butylbenzyl phthalate, bis(2-ethylhexyl) phthalate, diisononyl phthalate, bis(2-propylheptyl) phthalate, polycarboxylates, and combinations thereof.

[0111] Additionally, a method for marking a surface with LiDAR reflective material may further include applying the LiDAR reflective material to a surface by printing the LiDAR reflective material onto a sheet, the printed LiDAR reflective mark having a unique design. The unique design may be a glyph, barcode, QR code, or other information-containing pattern that can communicate a message to a robot, autonomous vehicle, or other observer. The sheet can be removed or dissolved by water. When the sheet is removed, the unique LiDAR reflective mark is transferred to the surface.

[0112] In addition, dark LiDAR markings can be used for security purposes by having intricate designs on dark objects that are imperceptible to the naked eye but perceptible to LiDAR detection devices. Similarly, articles or structures (e.g., trees, collapsed structures, and vehicles) can be marked by the systems disclosed herein and targeted by LiDAR detection devices such as robots or drones. For example, a dark landing pad marked by the delivery system described herein can be detected by a drone using a LiDAR detection device.

[0113] Examples Here, the embodiments will be further clarified by the following examples. Example 1 This study compares the reflectivity behavior of paint samples incorporating dark pigments. The samples contain two types of CuO crystallites: N-CuO-A has a crystal size of approximately 100 Å and a (111) / (-111) ratio close to 1; and N-CuO-C has a crystal size of approximately 204 Å and a (111) / (-111) ratio close to 1.1. A chromium iron oxide-based near-infrared (NIR) reflective black pigment, HEUCODUR HD910, was obtained from Heucotech LTD (referred to as "Cool Black"). Carbon black, MONARCH900, was obtained from Cabot Corporation (referred to as "Carbon Black").

[0114] The crystallographic information of CuO nanoparticles was investigated using powder X-ray diffraction (XRD, Rigaku Miniflex600, Japan) with CuKα radiation (λ = 0.1541 nm). The average crystallite size τ of the prepared particles was estimated from the measured width of the XRD diffraction curve by using Scherrer's formula.

[0115]

Number

[0116] Here, k is a dimensionless shape factor with a value close to 1. λ represents the wavelength of X-ray radiation, β is the line broadening at half of the maximum intensity (FWHM), and θ is the Bragg angle.

[0117] The optical properties of the painted panels were studied using a UV / Vis / NIR spectrophotometer (Agilent Cary7000, USA). Band gap calculations were based on the Kubelka-Munk function F(R ∞ related to the diffuse reflectance R ∞ ) of the sample.

[0118]

Number

[0119] Here, R ∞ is the absolute value of the reflectance, and F(R ∞ ) is equivalent to the absorption coefficient. The indirect band gap of the sample was estimated by plotting (F(R _ ∞)hν) 0.5 against energy. The linear part of the curve was extrapolated to (F(R _ ∞)hν) 0.5 = 0 to obtain the indirect band gap energy.

[0120] The blackness M of the painted samples directly related to the standards provided by the instrument yThis was evaluated using an X-Rite Ci7600 benchtop spectrophotometer (X-Rite, USA).

[0121]

number

[0122] Here, Y n =100.000 is one of the CIE white point values ​​under the D65 / 10 condition. Y is one of the CIE tristimulus values ​​of the sample being measured.

[0123] The reflectance spectrum shown in Figure 2 demonstrates that the paint sample incorporating N-CuO-A provides a beautiful black color with near-perfect absorption in visible light, exhibiting an NIR reflectance similar to carbon black but with a maximum peak close to 905 nm. The measure of blackness is a high 135.5, as shown in Figure 3. y The values ​​are shown. In comparison, paints containing carbon black exhibit very low reflectivity (less than 1%) across the entire visible and NIR wavelength range, resulting in a high blackness value of approximately 135. Paints with N-CuO-C have selectively higher NIR reflectivity between 900 and 1000 nm, but they exhibit distinguishable reflectivity in the visible wavelength range, particularly in red hues, resulting in a distinctly brownish appearance with a blackness value of less than 130. In contrast, the "cool black" samples exhibit strong reflectivity at the deeper ends of the NIR spectrum above 905 nm, but do not absorb well in the visible wavelength range, resulting in a blackness value of 128. The inset in Figure 3 shows the differences in blackness of these raw pigment samples and is in good agreement with the visible reflectivity spectra of the paint samples shown in Figure 3.

[0124] Example 2 N-CuO-A crystallites were mixed with polyurethane resin in a 1:4 powder / resin ratio and then applied via a doctor blade with a wet film thickness of 200 μm (or 8 mil) onto a steel panel surface that had been pre-coated with a half-black (reflectance - maximum 1%) and half-white (reflectance - minimum 78%) finish. A transparent clear coat with a dry film thickness of 60 μm was then applied onto a sample simulating an automotive paint system.

[0125] Example 3 To verify the LiDAR reflectivity of N-CuO-A crystallites, an autonomous vehicle was simulated using a robotic vehicle (Model TurtleBot3 Burger) equipped with a 905nm 2D laser scanner. The laser scanner can detect 360 degrees, collecting a dataset around the robot for use in SLAM (Simultaneous Localization and Mapping) and navigation, and stopping when obstacles are detected. Figure 4A shows the setup in which the painted panel was placed in front of the autonomous robotic vehicle each time, and the inset shows a prepared N-CuO-A painted panel that looks identical to carbon black paint. The LiDAR sensor intensity reflected by the panel and recorded on the screen is proportional only to the panel's reflectivity at 905nm when the distance and angle are fixed. When the panel tested was placed in front of the robotic vehicle at a fixed distance of 6 inches and a fixed angle (8°), the detected LiDAR intensity values ​​on the sensor were recorded via Bluetooth in Figure 4B. This clearly shows that the N-CuO-A painted panel has significantly higher LiDAR intensity (almost 1500%) than that of the carbon black panel. Therefore, the LiDAR reflectance from the N-CuO-A paint sample is sufficient for the robotic vehicle to detect it and perform an automatic "stop," as shown in Figure 4D, but it "collides" with the carbon black panel because it is almost completely absorbed at near-IR wavelengths, as shown in Figure 4C.

[0126] While specific embodiments have been illustrated and described herein, it should be understood that various other changes and modifications can be made without departing from the spirit and scope of the claimed subject matter. Furthermore, although various aspects of the claimed subject matter are described herein, such aspects do not need to be used in combination. Accordingly, the attached claims are intended to encompass all such changes and modifications that fall within the scope of the claimed subject matter.

Claims

1. A method for marking a surface with a LiDAR reflective material, Regarding the selection of surfaces to be marked, Applying the LiDAR reflective material to the surface, The LiDAR reflective material is The reflectance of electromagnetic radiation in the visible spectrum is 10% or less, and Applicable to electromagnetic radiation with reflectance of 10% or more in the near-IR and LiDAR spectra. Methods that include...

2. The method according to claim 1, wherein applying the LiDAR reflective material to the surface includes applying a delivery system comprising the LiDAR reflective material and a marking carrier to the surface.

3. The method according to claim 1, wherein applying the LiDAR reflective material to the surface includes spraying the LiDAR reflective material onto the surface.

4. The method according to claim 1, wherein applying the LiDAR reflective material to the surface includes applying the LiDAR reflective material to the surface using an applicator.

5. The method according to claim 4, wherein the applicator is selected from at least one of the group consisting of stamps, brushes, markers, pens, styluses, rollers, and needles.

6. Applying the LiDAR reflective material to the surface The method involves contacting the surface with a film containing the LiDAR reflective material, wherein the film is selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol-formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, or two or more combinations thereof. The film is to be broken when it comes into contact with the surface. The method according to claim 1, including the method described in claim 1.

7. The method according to claim 1, wherein the LiDAR reflective material is applied to the surface as a unique marking design.

8. The method according to claim 7, wherein the unique marking design is a glyph, a barcode, or a QR code.

9. A marking composition, LiDAR reflective material, Marking carrier and The LiDAR reflective material is equipped with, The reflectance of electromagnetic radiation in the visible spectrum is 10% or less, and A marking composition having reflectance in the near-IR and LiDAR spectra of electromagnetic radiation of 10% or more.

10. The marking composition according to claim 9, wherein the marking composition is encapsulated in a membrane selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, and combinations thereof.

11. The marking composition according to claim 9, wherein the composition further comprises a propellant selected from the group consisting of difluorochloromethane, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefin, low molecular weight hydrocarbon, butane, isobutene, propane, nitrous oxide, carbon dioxide, nitrogen, and combinations thereof.

12. The marking composition according to claim 9, wherein the marking carrier is a gas selected from the group consisting of argon, nitrogen, oxygen, difluorochloromethane, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefin, chlorofluorocarbon, low molecular weight hydrocarbon, butane, isobutene, propane, nitrous oxide, carbon dioxide, and combinations thereof.

13. The marking composition according to claim 9, wherein the marking carrier is a fluid selected from the group consisting of water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof.

14. The marking composition according to claim 9, wherein the marking carrier is a polymer selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, and combinations thereof.

15. The marking carrier is a combination of gas and fluid. The gas is selected from the group consisting of argon, nitrogen, oxygen, difluorochloromethane, dimethyl ether, methyl ethyl ether, tetrafluoroethane, heptafluoropropane, hydrofluoroolefin, chlorofluorocarbon, low molecular weight hydrocarbon, butane, isobutene, propane, nitrous oxide, carbon dioxide, and combinations thereof. The marking composition according to claim 9, wherein the fluid is selected from the group consisting of water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof.

16. The marking carrier is a combination of a fluid and a polymer. The fluid is selected from the group consisting of water, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, isophorene, diacetone alcohol, diisobutyl ketone, ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, glycol ether ester, propylene glycol monomethyl ether acetate, ethanol, butanol, propanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, and combinations thereof. The marking composition according to claim 9, wherein the polymer is selected from the group consisting of gelatin, polyethylene terephthalate (PET), polystyrene, gelatin, nylon, polycarbonate, epoxy, phenol formaldehyde resin, urethane, polyester, vinyl ester, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, acrylonitrile-butadiene-styrene (ABS), polydimethylsiloxane, polysulfide, and combinations thereof.

17. The LiDAR reflective material has an average particle size of 5 nm to 15 nm, and Blackness level 130-170 M y The marking composition according to claim 9, having the following:

18. The marking composition according to claim 9, wherein the LiDAR reflective material has an average particle size of 8 nm to 12 nm.

19. The LiDAR reflective material has a blackness of 150 to 170 M y The marking composition according to claim 9, having the following:

20. The marking composition according to claim 9, wherein the LiDAR reflective material has a reflectance in the visible spectrum of electromagnetic radiation of 5% or less.

21. The marking composition according to claim 9, wherein the LiDAR reflective material makes up 20% or more of the composition and has reflectance in the near-IR and LiDAR spectra of electromagnetic radiation.

22. The marking composition according to claim 12, wherein the LiDAR reflective material comprises a dark pigment selected from the group consisting of CuO crystallites, carbon black, chromium iron oxide and its derivatives, or two or more combinations thereof.

23. The marking composition according to claim 22, wherein the dark pigment comprises CuO crystallites having an intensity ratio of 0.5 to 1.5 (-111) / (111).

24. The marking composition according to claim 22, wherein the dark pigment comprises CuO crystallites having an intensity ratio of 0.9 to 1.1 (-111) / (111).

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