Black pigment having near-infrared transmission and / or reflection properties and coating composition containing the same

Abstract

IR reflective or transmissive black pigments capable of forming LiDAR responsive black coatings, wherein the pigments have a blackness M similar to non-IR reflective carbon black. y The black pigment having near-IR transmission and / or reflection properties has a plurality of CuO crystallites with a maximum dimension of 18 nm or less and a (-111) / (111) intensity ratio of less than 1.2. The method for forming the CuO crystallites includes precipitating CuCO3 or CuCO3 / Cu(OH)2 and calcining the precipitate at a temperature of about 300°C to about 400°C.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims the interests and priority of U.S. Patent Application No. 16 / 929,414, “Near Infrared Transmitting Copper Oxide Nanoparticles,” filed on 15 July 2020, the contents of which are incorporated herein by reference in their entirety.

[0002] Technical field This disclosure generally relates to copper oxide-based pigments and pigment compositions for coating formulations characterized by near-infrared transmittance and / or reflectance, for use in near-infrared (near-IR) light detection and ranging (LiDAR) applications. [Background technology]

[0003] The background information provided herein is for the purpose of providing an overview of the context of this disclosure. The inventors' research, to the extent described in this background art section, is not, in any aspect of this specification, expressly or implicitly, considered prior art to the present invention, and would not be considered prior art at the time of filing.

[0004] Near-irradiance (NIR), typically 905 nm or 1550 nm, is used by autonomous vehicles to detect objects. As shown in Figure 1, white and many other colors exhibit near-irradiance, but conventional black pigments used in paints and coatings (generally based on carbon black) absorb near-irradiance frequencies. Therefore, objects with coatings containing conventional black pigments are generally virtually undetectable by LiDAR sensors. Using black and dark-colored paints that reflect near-irradiance in the manner shown in Figure 2 for vehicles and other objects commonly encountered in traffic is desirable in the development of autonomous vehicles. Currently available dark-colored near-irradiance pigments based on chromium iron oxide (and its derivatives) do not achieve the aesthetic appeal of currently available black vehicle paints, as shown in Figure 3. Improved black pigments are needed.

[0005] The use of copper(II) oxide (CuO) has been explored as a black pigment and has been used as a dark pigment for ceramic glazes. Coating pigments generally require uniform particles smaller than 3 microns. CuO powder exhibits various forms and properties depending on its manufacturing method. Generally, commercial methods yield large particles or aggregates of fine particles, making it unsuitable for immediate use as a coating pigment. Typical precipitation methods yield CuO with an average particle size of over 10 microns, but particles smaller than 10 microns with a narrow particle size distribution of less than 3 have been produced by milling. For example, U.S. Patent No. 9,683,107 is directed at an infrared-reflective "black" pigment produced by heating CuO with a purity of at least 99% to over 480°C and milling it to produce particles of about 1-3 microns with a crystallite size of over 19 nm, but this "black" pigment has a rather brown appearance, as its CIE-LAB values ​​are approximately 28, 0.5, and -0.3. [Overview of the project] [Problems that the invention aims to solve]

[0006] To implement LiDAR applications, a band gap of approximately 1.2 eV to 1.7 eV with a band edge below 700 nm (or 1.77 eV) is required to absorb the visible spectrum and transmit LiDAR-active near-IR wavelengths. Typical bulk CuO cannot meet this requirement because it has a band gap outside the 1.3 eV to 1.7 eV range and a band edge greater than 1.77 eV. A CuO pigment of appropriate dimensions and composition is needed that exhibits a blackness close to that of carbon black and is configured to selectively reflect near-IR radiation, particularly the 905 nm and / or 1550 nm wavelengths used for object detection in autonomous vehicles using LiDAR technology. [Means for solving the problem]

[0007] This section provides a general summary of this disclosure and does not constitute a comprehensive disclosure of its entire scope or features.

[0008] In various embodiments, this teaching provides a black pigment comprising near-IR transparent and / or reflective particles having CuO on at least a portion of the outer surface of the particles. The particles have a crystal size of less than about 15 nm and a relative intensity of (-111) plane / (111) plane by X-ray diffraction analysis (XRD) of less than about 1.2. The particles can have a diameter from less than about 10 nm to more than about 10 μm. The particles enable reflection of LiDAR radiation at 905 nm and / or 1550 nm for object detection, with a band gap of 1.2 to 1.7 eV and a blackness of at least about 132 M y Show the value.

[0009] In another embodiment, the teaching provides a coating composition comprising a fluid medium together with a black pigment containing near-IR permeable and / or reflective particles having CuO arranged on at least a portion of the outer surface of the particles. This coating composition can be used as a black paint or coating.

[0010] In yet another embodiment, this teaching provides a method for producing near-IR permeable and / or reflective particles having CuO on at least the surface of the particles. This method involves the production and precipitation of CuCO3 or CuCO3 / Cu(OH)2 from an aqueous solution by reaction of an alkali metal carbonate with a water-soluble copper(II) salt. If the aqueous solution has suspended particles of either nanoparticles or microparticles, the precipitation may involve the deposition of CuCO3 onto supporting particles. The supporting particles may be core particles of the CuO-containing particles and may have a cross-section ranging from less than 300 nm to greater than 1.5 μm. If deposition is performed on particles of a different composition, the CuO portion of the particles is less than 50 nm. The nanoparticles or microparticles on which CuCO3 / Cu(OH)2 is formed are washed, filtered, dried, and calcined to a temperature of about 300-400°C.

[0011] In a further embodiment, this teaching provides a black paint for application to the exterior surface of a vehicle or other object to enable detection by LiDAR technology. For example, LiDAR technology can support various functions of an autonomous vehicle by detecting the reflectance of wavelengths of 905 nm and / or 1550 nm transmitted from a near-infrared laser for LiDAR technology. The black pigment of this technology has a blackness of at least about 132 M y The blackness value can be expressed, and this blackness value gives the carbon black pigment its aesthetic quality and also provides good infrared reflection.

[0012] Further areas of application and various ways to enhance the coupling technology described above will become apparent from the descriptions provided in this disclosure. The descriptions and examples in this summary are for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0013] This instruction will be better understood from the detailed explanation and attached diagrams. [Brief explanation of the drawing]

[0014] [Figure 1]Figure 1 shows a plot of the reflectance of current white and black paints used in vehicles, indicating that the reflectance in the near IR is insufficient for conventional black paints based on carbon black.

[0015] [Figure 2] Figure 2 shows a plot of the reflectance of a target IR - reflective black paint versus the current black paint, where the goal is to achieve a reflectance in the near IR at 905 nm and / or 1550 nm in addition to achieving a blackness similar to that of the current paint.

[0016] [Figure 3] Figure 3 shows a graph of the "blackness" of current automotive standard carbon black pigments and various commercially available near - IR - reflective pigments based on chromium oxide iron.

[0017] [Figure 4A-4C] Figures 4A - 4C show transmission electron micrographs of IR - reflective CuO particles according to one aspect of the present technology, which are agglomerated particles larger than 6 μm (Figure 4A), agglomerated particles less than about 40 nm (Figure 4B), and mainly particles of about 20 nm (Figure 4C). <( [[ID= (20]]

[0018] [Figure 5] Figure 5 is a plot showing the My values of black touch - up paints, carbon black, CuO - based IR - reflective paints (Cool Black 0912), commercially available CuO variations, and precipitated and fired CuO particles (including particles according to one aspect of the present technology) with various precipitants and firing temperatures.

[0019] [Figures 6A-6E] Figures 6A - 6E are photographs of carbon black (Figure 6A); Na2CO3 - precipitated CuO fired at 300 °C according to one aspect of the present technology (Figure 6B); (NH4)2CO3 - precipitated CuO fired at 300 °C (Figure 6C); NaOH - precipitated CuO fired at 300 °C (Figure 6D); and commercially available CuO powder (Figure 6E) from left to right.

[0020] [Figure 7A-7C] Figures 7A to 7C are X-ray microscope images of NaOH-precipitated CuO fired at 300 °C (Figure 7A); (NH4)2CO3-precipitated CuO fired at 300 °C (Figure 7B); and Na2CO3-precipitated CuO fired at 300 °C (Figure 7C, the scale bar has a length of 1 μm).

[0021] [Figure 8] Figure 8 is a plot showing the relative intensity of the (-111) / (111) reflection for CuO particles formed with different precipitating agents and fired at different temperatures, as shown therein.

[0022] [Figures 9A-9D] Figures 9A to 9D are photographs of various milled pigments, from left to right: carbon black (Figure 9A); Na2CO3-precipitated CuO fired at 300 °C according to one aspect of the present technology (Figure 9B); Na2CO3-precipitated CuO fired at 400 °C according to one aspect of the present technology (Figure 9C); and Na2CO3-precipitated CuO fired at 500 °C (Figure 9D).

[0023] [Figure 10] Figure 10 is a plot of (-111) / (111) relative intensity versus crystallite size for Na2CO3-precipitated CuO fired at temperatures of 300 °C, 400 °C, 500 °C, and 600 °C.

[0024] [Figure 11] Figure 11 is a hybrid reflectance spectrum of various coatings including carbon black, commercially available CuO, a typical commercially available NIR reflective coating, and NIR reflective CuO according to one embodiment.

[0025] [Figure 12] Figure 12 is a schematic cross-section of a typical layered, painted substrate.

[0026] [Figure 13]Figure 13 is a plot of reflectance versus rotation angle for LiDAR detection of a mirror, red pigment, green pigment, and black pigment according to one embodiment of this technology. [Modes for carrying out the invention]

[0027] It should be noted that the figures described herein are intended to illustrate the outlines of methods, algorithms, and devices of the Art for the purpose of describing specific embodiments. These figures may not accurately reflect the features of any given embodiment and are not necessarily intended to define or limit any particular embodiment within the scope of the Art. Furthermore, a particular embodiment may incorporate features from a combination of the figures.

[0028] This technology generally provides a black pigment comprising near-IR transparent and / or reflective particles having CuO disposed on at least a portion of the outer (i.e., exposed) surface of the particles. The entire particle may be CuO. CuO provides strong absorption of visible light across most of the visible spectrum but exhibits significant reflectivity in the near-IR. In various embodiments, the crystal size, indicated by the magnitude of the (-111) reflectivity, can have a maximum dimension of less than about 18 nm, and the relative intensity of the (-1,1,1) plane / (1,1,1) plane is less than about 1.2. The particles can have a diameter dimension of less than about 40 nm. The particles enable reflection of 905 nm and / or 1550 nm LiDAR radiation for object detection, and the particles exhibit a band gap of 1.2–1.7 eV and a blackness of at least about 132 M y The values ​​are shown. The particles can have dimensions ranging from nanometers less than 40 nm to micrometers greater than 10 μm. The small crystal size of CuO particles provides near-IR transmittance or reflectance without significant reflection of visible light, and this near-IR transmittance or reflectance characterizes the black pigment obtained therefrom. The reflectance of LiDAR radiation at 905 nm and / or 1550 nm can be used in particle detection.

[0029] In one aspect of this technology, the black pigment is incorporated into the coating composition such that, when applied to a surface, the composition retains, provides, or enhances the near-IR reflectivity of the black pigment. The black pigment has a blackness of about 132 or higher M y The black coating can exhibit a value and, as a result, provides a black coating with black quality similar to that provided by conventional carbon black-based black coatings, which are coatings that lack the ability to reflect or transmit IR. The coating composition may include a fluid medium for applying the black pigment in a particle formulation that achieves the desired aesthetic appearance on the desired surface. The fluid medium is preferably a fluid that enables coating by common techniques such as spraying or dip coating.

[0030] In another embodiment, this teaching provides a method for producing near-IR transparent and / or reflective particles having at least CuO on the particle surface. This method involves the formation and precipitation of CuCO3 from an aqueous solution by the reaction of an alkali metal carbonate with a water-soluble copper(II) salt, such as copper(II) nitrate. The precipitation may involve the deposition of CuCO3 onto support particles. The support particles can be nanoparticles of mica, synthetic mica, glass, quartz, alumina, or any other particles that enhance the reflection and / or transmission of IR radiation while maintaining the aesthetic appearance of a black pigment. The particles can have a cross-section of less than 300 nm, where the CuO portion of the particle is 50 nm or less. The particles can take the form of particle aggregates, which can be milled to form nanoparticles or aggregated nanoparticles, for example, particles of less than 300 nm. Milling methods include ball milling, jet milling, or any other method that contributes to the formation of particles of the desired size. The particles can generally be less than 300 nm or more than 10 μm, while maintaining a small crystal size of, for example, about 15 nm or less.

[0031] As detailed herein, this instruction is directed not only to the development of black pigments in coating compositions, but also to the application and use of coating compositions as cured paints on the exterior surfaces of vehicles or other objects to enable detection by LiDAR technology. LiDAR detection can enable proper functionality of autonomous vehicles by detecting the reflectance of 905 nm and / or 1050 nm wavelengths transmitted from a near-infrared laser for LiDAR technology, while the coating composition maintains the typical blackness due to the carbon black IR-absorbing pigment.

[0032] In one aspect of this technology, the CuO portion of the nanoparticles can be less than 50 nm, and the band gap is less than 1.7 eV, for example, less than 1.2 to 1.6 eV. This size is obtained from the synthesis of nanoparticles by precipitation of CuCO3 or CuCO3 / Cu(OH)2 nanoparticles, followed by drying of the particles at a temperature of about 300 to about 400°C and subsequent calcination, thereby decomposing the CuCO3 or CuCO3 / Cu(OH)2 nanoparticles to CuO nanoparticles with a cross-sectional area ranging from less than 40 nm to greater than 10 μm. Exemplary CuO nanoparticles are shown in TEM images of Figures 4A to 4C, with aggregated particles greater than 6 μm (4A), aggregated nanoparticles less than about 40 nm (4B), and mainly particles of about 20 nm (4C).

[0033] In another aspect of this technology, the method for producing nanoparticles is carried out by precipitation, in which an aqueous solution of Cu(NO3)2 or other highly soluble Cu(II) salts, such as CuBr2, CuCl2, Cu(ClO3)2, or CuSO4, is combined with an aqueous solution of a precipitant, which may be Na2CO3, K2CO3, Li2CO3, Rb2CO3, Cs2CO3, Fr2CO3, or any combination thereof. The basic precipitant can be added to the Cu(NO3)2 solution until the pH reaches a level of 9-10. Subsequent isolation and washing with water of the resulting precipitate effectively yields nitrate-alkali and carbonate-free suspended solid CuCO3 or CuCO3 / Cu(OH)2 particles. CuCO3 / Cu(OH)2 particles, like malachite, are composed of CuCO3, Cu(OH)2, and CO3 -2 and OH - It contains a mixed anionic copper salt. After filtration and drying, the aggregated CuCO3 particles are ground into a fine powder suitable for formulation in coating compositions, and the particles are calcined at a temperature of approximately 300 to 400°C to form black CuO particles.

[0034] The washed CuCO3 particles or CuCO3 / Cu(OH)2 are dried. Drying can be carried out in air, nitrogen, an inert atmosphere, an oxygen-rich atmosphere, or under vacuum. Drying can be carried out at temperatures ranging from ambient temperature to about 120°C, depending on the pressure used during drying. The dried CuCO3-containing particles can be ground into a fine powder or ultrafine powder. Grinding can be carried out in any mill suitable for the hardness of the material. For example, the mill can be, but is not limited to, a ball mill, jet mill, high-compression roll mill, roll mill, or universal mill. The dried particles are then calcined at a temperature of about 300-400°C to convert the CuCO3-containing particles into CuO-containing particles exhibiting a band gap of about 1.7 eV or less. Instead of preparing particles by precipitation, CuO particles can be formed from ground malachite using, for example, CuCO3-Cu(OH)2(Sigma), where calcination is carried out in the same manner as for Na2CO3 precipitate particles to obtain a LIDAR-activated black pigment with similar properties. Thus, with appropriate calcination temperature and precursor composition, the resulting black pigment can have a blackness M greater than approximately 132. y It can show a value.

[0035] The precipitation method according to various embodiments of this technology can be a deposition precipitation method. A solution of Cu(NO3)2 can be combined with nanoparticles as a core material, such as mica, synthetic mica, glass, quartz, or alumina, to form a suspension, and CuCO3 can be deposited on it by reaction with a precipitating agent to form a shell. The shell can be continuous or discontinuous, for example, provided as CuO islands on the core particles. During washing and calcination, the core-shell nanoparticles have a core covered with or coated with a CuO shell. In one embodiment, the core has a cross-section of 10 μm or less, the shell has a thickness of less than 50 nm, and the shell can be continuous or discontinuous. In another embodiment, the core particles can have a cross-section of 300 nm or less, and the dimensions of the CuO surface features are less than 50 nm.

[0036] Precipitation or sedimentation can be carried out as a batch or continuous process in combination with a precipitant solution and a solution or suspension containing Cu(NO3)2. Slow addition of the basic precipitant solution can be carried out using at least one dropping funnel or equivalent, or at least one pump, where the addition profile is maintained at a desired rate so as to optimize the quality and throughput of the precipitated CuCO3-containing particles, where the rate can be constant, accelerating, or decelerating. Adequate stirring can be provided by at least one stirrer or other mixer. A continuous mixing loop can be constructed by employing at least one active or passive in-line mixer in the flow of the suspension through the loop. Alternatively or additionally, mixing can be carried out or enhanced by cavitation, which may be facilitated by ultrasound, piezoelectricity, or other means.

[0037] After the formation of precipitated CuCO3 or CuCO3 / Cu(OH)2-containing particles, the aqueous solution from the resulting particles can be removed by filtration or centrifugation. Filtration can be performed by pressurizing the proximal side of the filter or depressurizing the distal side of the filter. Subsequently, the particles are washed to remove water-soluble salts. Washing can be performed in batches, by suspending the particles in purified water and re-filtration or re-centrifugation, or by continuously washing the particles by flowing water through a filter bed or centrifugation bed. If necessary, the water can be distilled water, deionized water, or reverse osmosis purified water.

[0038] The use of alkali metal carbonates as precipitants yields excellent blackness with no significant visible light reflectivity, along with a small crystallite size of less than approximately 18 nm and a preferred (-111) / (111) ratio, when calcination, which is performed to convert carbonate / hydroxide particles to CuO particles, is carried out at a temperature of approximately 300-400°C. Other precipitants, as shown in Figure 5, do not yield high-quality black IR reflective pigments, nor do milling or other means of reducing particle size. yAs can be seen from the values, the blackness required to assimilate with the blackness of carbon black, such as in non-IR reflective touch-up paints, cannot be achieved from commercially available CuO formed by milling or as nanoparticles from CuO. In the precipitation method employed to obtain the black pigment of the present invention, using NaCO3 as the precipitant achieves sufficient blackness when calcined at 300°C, but not at 450°C. Using ammonium carbonate as the precipitant yields a sufficient value when calcined at 300°C, but not at 450°C. Thus, the use of NaOH as the precipitant does not enable sufficient blackness. As shown in Figures 6A to 6E, commercially available CuO (6E) gives insufficient blackness, similar to NaOH precipitated Cu(OH)2 (6D) calcined at 300°C. On the other hand, black pigments formed using CuCO3 from precipitation of sodium carbonate (6B) or ammonium carbonate (6C) and calcination at 300°C give a black pigment similar to carbon black (6A), but CuO derived from ammonium carbonate has a slightly reddish hue.

[0039] CuO formed by the precipitation of CuCO3 or Cu(OH)2 exhibits different morphologies and aggregate sizes depending on the precipitating agent used, as shown in Figures 7A-7C. Those formed from NaOH precipitation of Cu(OH)2 show aggregated and elongated fibrils (7A), and discrete, nearly spherical particles of CuO are formed from carbonates, but those from ammonium carbonate (7B) are smaller in size than those from sodium carbonate (7C). Focusing on the fact that CuCO3 produced from ammonium carbonate shows a slightly reddish hue, it was found that the best black color was achieved when the values ​​of both characteristics were smaller, based on the difference in relative (-111) / (111) intensity and the crystallite size determined from the (-111) peak. As shown in Figure 8, superior black pigments were formed from CuO that showed smaller values ​​for (-111) size and relative (-111) / (111) intensity, and sufficient blackness could not be obtained with particles exceeding approximately 150 Å and approximately 1.2, respectively.

[0040] As shown in Figures 9A-9D, when CuCO3 / Cu(OH)2 is fired at 400°C, almost black CuO remains at low temperatures, but when fired at 500°C, a more brownish CuO can be formed. The relative intensity (-111) / (111) remains low and decreases from the highest value obtained when fired at 300°C, but the crystallite size determined by the (-111) size increases from approximately 15 nm when fired at 400°C to approximately 40 nm when fired at 600°C, as shown in Figure 10.

[0041] Near-IR reflective CuO-containing particles can be incorporated into coating compositions having spectral characteristics as shown in Figure 11. These particles can be included in aqueous or oil-based formulations, such as aqueous acrylic polyurethane enamel basecoats. This black near-IR reflective coating composition can be used as a basecoat positioned between the primer and clearcoat of the finished body panel to which it is applied, as shown in Figure 12. As shown in Figure 13, the rotation angle for detection of a LiDAR surface with a black coating according to one embodiment is lower and more easily detected than that of the developed green and red LiDAR coatings.

[0042] The above description is essentially illustrative and is not intended in any way to limit the disclosure, its application, or use. Where used herein, the expression "at least one of A, B, and C" should be interpreted as meaning logical (A or B or C) using a non-exclusive logical "or". It should be understood that various steps in a particular method may be performed in a different order without altering the principles of this disclosure. The scope disclosure shall include the full scope and the subdivided scope within the full scope.

[0043] The headings (such as "Background Art" and "Summary of the Invention") and subheadings used herein are for general organization of the topics within this disclosure and are not intended to limit the disclosure of the Art or any aspect thereof. The descriptions of multiple embodiments having the described features are not intended to exclude other embodiments having additional features or incorporating different combinations of the described features.

[0044] As used herein, the terms “comprise” and “include,” and their variations thereto, are intended to be non-limiting so as not to exclude other similar items that may also be useful in the devices and methods of the Art. Similarly, the terms “may,” and “may,” and their variations thereto, are intended to be non-limiting so as not to exclude other embodiments of the Art that do not include certain elements or features, if a statement that an embodiment may include or may include certain elements or features.

[0045] The extensive teachings of this disclosure can be implemented in various forms. Therefore, while this disclosure includes specific examples, the true scope of this disclosure should not be limited to the teachings herein, as other modifications will become apparent to those skilled in the art through examination of this specification and the following claims. In this specification, reference to one aspect or various aspects means that a particular feature, structure, or characteristic described in relation to an embodiment or particular system is included in at least one embodiment or aspect. The appearance of the phrase "in one aspect" (or a variation thereof) does not necessarily refer to the same aspect or embodiment. Furthermore, it should be understood that the various method steps discussed herein do not need to be performed in the same order as described, and not every method step is required in every aspect or embodiment.

[0046] The foregoing description of embodiments is provided for illustrative and explanatory purposes only. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally interchangeable and can be used in selected embodiments, even if not specifically illustrated or described, but are not limited to that particular embodiment. The same can also be modified in many ways. Such modifications should not be considered departures from the disclosure, and any such modifications are intended to be within the scope of the disclosure. Some embodiments of the present invention are shown below. [Embodiment 1] A black pigment having near-infrared transmission and / or reflection properties, comprising a plurality of CuO crystallites having a maximum dimension of 18 nm or less and an intensity ratio of (-111) / (111) less than 1.2. [Embodiment 2] The CuO crystallites are present in at least a portion of the outer surface of the particle. The diameter of the aforementioned particles is approximately 50 nm to approximately 10 μm. The black pigment described in Embodiment 1. [Embodiment 3] The black pigment according to Embodiment 2, wherein the particles include a core portion containing one of mica, synthetic mica, glass, quartz, or alumina. [Embodiment 4] The black pigment according to Embodiment 3, wherein the portion of the outer surface containing CuO has a thickness of less than about 50 nm. [Embodiment 5] The black pigment according to Embodiment 3, wherein the portion of the outer surface containing CuO is a continuous or discontinuous shell on the core. [Embodiment 6] The black pigment according to Embodiment 1, wherein the crystallite has a maximum size of 15 nm or less. [Embodiment 7] The black pigment according to Embodiment 1, wherein the black pigment exhibits a band gap of approximately 1.7 eV or less. [Embodiment 8] Fluid vehicle and, A black pigment having near-infrared transmission and / or reflection properties suspended in the fluid vehicle, A coating composition comprising the black pigment, wherein the black pigment comprises CuO crystallites having a maximum dimension of 18 nm or less and an intensity ratio of (-111) / (111) less than 1.2. [Embodiment 9] The CuO crystallites are present in at least a portion of the outer surface of the particle, and The aforementioned particles have a cross-section of 50 nm to 10 μm. The coating composition according to Embodiment 8. [Embodiment 10] The coating composition according to Embodiment 9, wherein the particles include a core portion containing one of mica, synthetic mica, glass, quartz, or alumina. [Embodiment 11] The coating composition according to Embodiment 10, wherein the portion of the outer surface containing CuO has a thickness of less than about 50 nm. [Embodiment 12] The coating composition according to Embodiment 8, wherein the crystallites have a maximum size of 15 nm or less. [Embodiment 13] The black pigment in the coating composition has a blackness of at least 132 M y A coating composition according to Embodiment 8, showing a value. [Embodiment 14] The coating composition according to Embodiment 8, wherein the coating composition exhibits a band gap of about 1.7 eV or less. [Embodiment 15] A method for forming near-infrared reflective or transmissive CuO crystallites, including the following: To provide a solution or suspension containing a water-soluble Cu(II) salt; A precipitating agent solution containing an alkali metal carbonate is added to the aforementioned solution or suspension to form CuCO 3 Forming a precipitate containing; Wash the aforementioned precipitate with water; Isolating the aforementioned precipitate; and The precipitate is calcined at a temperature of approximately 300 to 400°C to form near-infrared reflective or transmissive CuO crystallites, wherein the CuO crystallites have a maximum dimension of 18 nm or less and an intensity ratio of (-111) / (111) less than 1.2. [Embodiment 16] The aforementioned water-soluble Cu(II) salt is Cu(NO 3 ) 2 The method according to Embodiment 15, including the method described in Embodiment 15. [Embodiment 17] The method according to Embodiment 15, wherein the suspension comprises a suspension of core-forming particles, and the precipitate comprises shells on the core-forming particles. [Embodiment 18] The method according to Embodiment 17, wherein the core-forming particles include at least one of mica, synthetic mica, glass, quartz, or alumina. [Embodiment 19] The method according to Embodiment 15, wherein the step of isolating the precipitate comprises filtering or centrifuging the precipitate, and the method further comprises drying the precipitate after isolation to form a dried precipitate. [Embodiment 20] Furthermore, the method according to Embodiment 15, further comprising grinding the precipitate. [Embodiment 21] Furthermore, the method according to Embodiment 15, comprising grinding the near-infrared reflective or transparent CuO crystallites. [Embodiment 22] The method according to Embodiment 15, wherein the CuO crystallite exhibits a band gap of approximately 1.7 eV or less.

Claims

1. A black pigment having near-infrared transmission and / or reflection properties, comprising a plurality of CuO crystallites having a maximum dimension of 18 nm or less and an intensity ratio of (-111) / (111) less than 1.2, The CuO crystallite is in the form of a shell present on the outer surface of a core made up of support particles. The aforementioned core has a cross-sectional dimension of less than 300 nm. The core comprises one of mica, synthetic mica, glass, or quartz. The aforementioned shell has a thickness of less than 50 nm. Black pigment.

2. The CuO crystallites are present in at least a portion of the outer surface of the core, The diameter of the core is 50 nm or more and less than 300 nm. The black pigment according to claim 1.

3. The black pigment according to claim 1, wherein the CuO crystallite has a maximum dimension of 15 nm or less.

4. The black pigment according to claim 1, wherein the black pigment exhibits a band gap of 1.7 eV or less.

5. Fluid vehicle and, A black pigment having near-infrared transmission and / or reflection properties suspended in the fluid vehicle, A coating composition comprising the black pigment comprising CuO crystallites having a maximum dimension of 18 nm or less and an intensity ratio of (-111) / (111) less than 1.2, The CuO crystallite is in the form of a shell present on the outer surface of a core made up of support particles. The aforementioned core has a cross-sectional dimension of less than 300 nm. The core comprises one of mica, synthetic mica, glass, or quartz. The aforementioned shell has a thickness of less than 50 nm. Coating composition.

6. The CuO crystallites are present in at least a portion of the outer surface of the core, and The core has a cross-sectional dimension of 50 nm or more and less than 300 nm. The coating composition according to claim 5.

7. The coating composition according to claim 5, wherein the CuO crystallite has a maximum dimension of 15 nm or less.

8. The black pigment in the coating composition has a blackness M of at least 132 ｙ The coating composition according to claim 5, which shows a value.

9. The coating composition according to claim 5, wherein the coating composition exhibits a band gap of 1.7 eV or less.

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