Dark-colored primer coating with high LiDAR reflectivity

Abstract

The present invention relates to a primer coating composition, a method for forming primer coating films and layers, at least partially coated substrates, a multi-layer coating system and a method for the production thereof, which primer coating composition is free or essentially free of metallic effect pigments and comprises, besides water and / or organic solvent(s), a film-forming polymer and optionally a crosslinker, as well as a pigment mixture PC, which pigment mixture PC comprises at least two pigments which are different from one another, i.e. which are not carbon black pigments and which are transparent or substantially transparent to NIR-radiation or which are transparent to NIR-radiation. at least one organic or inorganic black pigment P-C1 which is reflective or substantially reflective to X-rays, and at least one inorganic white pigment P-C2 which is reflective or substantially reflective to NIR-radiation, the pigment P-C1 being present in an amount ranging from 0.1 to 20.0% by weight and the pigment P-C2 being present in an amount ranging from 0.2 to 40.0% by weight, in each case relative to the total weight of the primer coating composition, and a primer coating obtained by applying the primer coating composition to a substrate has a lightness value L* according to the CIELAB system of less than or equal to 38 at 45°.

Description

Technical Field

[0001] The present invention relates to a primer coating composition, a primer coating film and a method of forming a layer, a substrate at least partially coated, a multilayer coating system and a method for producing the same, the primer coating composition not containing or essentially not containing metallic effect pigments and, in addition to water and / or organic solvent(s), comprising a film-forming polymer and optionally a crosslinking agent, further comprising a pigment mixture P-C, this pigment mixture P-C comprising at least two pigments different from each other, namely at least one organic black or inorganic black pigment P-C1 which is not a carbon black pigment and is transparent or substantially transparent to NIR-radiation or is reflective or substantially reflective to NIR-radiation, and at least one inorganic white pigment P-C2 which is reflective or substantially reflective to NIR-radiation, the pigment P-C1 being present in an amount in the range of 0.1 to 20.0% by mass and the pigment P-C2 being present in an amount in the range of 0.2 to 40.0% by mass, each in each case relative to the total mass of the primer coating composition, and the primer coating obtained by applying the primer coating composition to a substrate having a lightness value L* according to the CIELAB system of 38 or less at 45°.

Background Art

[0002] In the automotive industry, providing coatings with good infrared reflectivity has become a new requirement. Good infrared reflective coatings help keep vehicles cool. For example, US6,366,3971B1 relates to an IR radiation reflector having an IR reflective layer and an IR transparent layer formed on the IR reflective layer. US6,366,3971B1 aims to provide an IR radiation reflector having good IR reflectivity and a wide range of possible colors. Furthermore, JP2014-210856A relates to a low-brightness coating film. The coating composition used to prepare the coating film comprises a black pigment that reflects and / or transmits IR rays and a transparent blue pigment, and has a brightness L* of 0.1 to 7. JP2014-210856A aims to provide a coating that does not get hot but still has jet-black color characteristics. US10,619,053B2 discloses a solar reflective coating composition comprising, in particular, two different types of NIR-transparent perylene pigments, such as perylene pigments with green or purple hues, and NIR-reflective pigments, such as titanium dioxide. The resulting cured coating exhibits an off-white or gray color and has an L* value ranging from 40 to 95 at an angle of 10°. US10,619,053B2 aims to prevent heat buildup in substrates coated with the coating composition.

[0003] However, good infrared reflective coatings are also useful for ADAS (Advanced Driver-Assistance Systems), especially vehicles equipped with LiDAR (Light Detection and Ranging). ADAS heavily rely on remote sensing technologies by optical or electromagnetic means to determine position and speed. LiDAR is one such remote sensing technology and can be deployed in vehicles as the primary source of object recognition. LiDAR maps the distance to objects in its path in real time by measuring reflections with sensors after illuminating the surrounding environment with laser light (typically 905 nm or 1550 nm). For example, if an object gets too close to the vehicle, a collision with that object can be avoided. Since LiDAR uses near-infrared light (near-IR or NIR light) as its illumination source, this technology must overcome several challenges. Apart from the LiDAR device itself, one of the important factors regarding the accuracy of the measurement is the surface of the object being illuminated. In the case of automobiles and other vehicles, the surface is usually covered with a multilayer coating that plays a crucial role in determining the LiDAR reflectivity.

[0004] In OEMs, coating layers on vehicle bodies and their components typically consist of, starting from the substrate, a chemical conversion coating layer, an electrodeposition coating layer (e.g., a cathode electrodeposition layer), a primer layer (sometimes called a filler layer), at least one basecoat layer, and a clear coat layer as a topcoat on top of the basecoat layer. Thus, a typical OEM multilayer coating layer includes a primer, at least one basecoat, and a clear coat. The clear coat layer is obviously transparent and is usually transparent to IR radiation as well. The basecoat often contains organic pigments and / or effect pigments, such as metal flakes. Beneath the basecoat layer, a dark-colored primer is often used to enhance the dark color of the basecoat. To achieve a dark-colored primer, carbon black is commonly added to the formulation. However, since carbon black absorbs infrared wavelengths, this can lead to undesirable heat accumulation. EP2323777B1 relates to the manufacture of a dark multilayer coating on a substrate, wherein the multilayer comprises, on the substrate, layer A', layer B', and a clear coat layer, in that order. Layer B' is prepared from composition B, which contains at least 50% by mass of a black pigment with low NIR absorption, i.e., high NIR transmittance, such as perylene black pigment, and optionally 50% by mass or less of further pigments (in each case relative to the pigment content of composition B), and layer B' exhibits only low NIR absorption. The dark multilayer exhibits a lightness L* of at most 10 at an angle of 45°. EP2323777B1 aims to provide a dark multilayer coating that does not heat up. US8,679,617B2 discloses, among other things, a solar reflective coating system including a second layer present beneath a first coating layer, the second layer comprising a visible absorbing infrared transparent pigment and a thin flake-like metal or metallic alloy infrared reflective pigment. However, using such thin, flake-like metal or metal alloy pigments, i.e., metallic effect pigments, as a second layer is disadvantageous because their presence introduces undesirable high-angle dependence in LiDAR applications, resulting in LiDAR reflectivity of such coating layers typically being less than 9% or even lower, less than 5%, at an incident angle of 45°.

[0005] In recent years, several approaches have been developed to improve the LiDAR reflectivity of multilayer coatings, particularly those applied to vehicles. In the first approach, NIR-reflective pigments are contained in the basecoat layer. NIR light passes through a non-NIR-absorbing (NIR-transparent) protective clearcoat layer and is reflected by the NIR-reflective pigment(s) in the basecoat layer. However, the basecoat layer is typically the layer that determines the color and / or effect properties of multilayer automotive coatings. Therefore, as mentioned above, the basecoat typically contains organic pigments and effect pigments, such as metal flakes. However, these flake pigments are transparent in the near-infrared (NIR) region. Thus, in another second approach, NIR light passes through a non-NIR-absorbing protective clearcoat layer and a basecoat layer containing non-NIR-absorbing coloring and / or effect pigments, but must then be reflected by the primer layer. Due to the NIR transparency of the aforementioned pigments in the basecoat, the NIR reflectivity of the primer plays a crucial role in determining the reflectivity of such a system. Light-colored primers are generally NIR reflectors, while dark-colored primers, including those containing the aforementioned carbon black, are usually NIR absorbers.

[0006] When designing primers for use as LiDAR reflective primers, one important aspect to consider is light transmittance, particularly in the 280nm to 500nm wavelength range (ultraviolet region). High-energy light at wavelengths of 400-500nm can penetrate the primer layer and degrade the electrodeposited coating layer beneath. TiO2 is the most widely used primary pigment, absorbing UV radiation but scattering visible light. However, some of the scattered low-wavelength radiation (400nm to 500nm) can reach the electrodeposited coating layer. Carbon black excels at absorbing wavelengths across this range, helping to mitigate such degradation and reduce UV transmission. However, the use of carbon black has the aforementioned drawbacks.

[0007] Therefore, there is a need to provide an improved dark-colored primer coating that not only has high IR reflectance / LiDAR reflectance, for example, LiDAR reflectance of over 45% or over 50%, but also provides good shielding in the UV-visible range, for example, UV transmittance of less than 0.005 in the wavelength range of 280-500 nm. At the same time, such a primer should not allow any undesirable heat accumulation originating from any of its components, such as carbon black, especially when it is part of a multilayer coating system used in the automotive industry, and should provide the same dark color as conventional carbon black-containing primer coatings. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] US6,366,3971B1 [Patent Document 2] JP2014-210856A [Patent Document 3] US10,619,053B2 [Patent Document 4] EP2323777B1 [Patent Document 5] US8,679,617B2 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Therefore, the fundamental objective of the present invention is to provide a dark-colored primer coating that not only has high IR reflectance / LiDAR reflectance, for example, LiDAR reflectance of more than 45% or more than 50%, but also exhibits good shielding in the UV-visible range, for example, UV transmittance of less than 0.005 in the wavelength region of 280-500 nm. At the same time, this primer should not allow any undesirable heat accumulation originating from any of its constituent components, such as carbon black, especially when it is part of a multilayer coating system used in the automotive industry, and should provide the same dark color as conventional carbon black-containing primer coatings. [Means for solving the problem]

[0010] This objective has been resolved by the subject matter of the scope of this patent application and by the preferred embodiments thereof disclosed herein, i.e., by the subject matter described herein.

[0011] The first subject of the present invention is a primer coating composition that does not contain or is essentially free of metallic effect pigments, the composition comprising the following components: As at least one component PA, at least one film-forming polymer P-A1, and if P-A1 is externally crosslinkable, at least one crosslinking agent-PA2, The constituent components (multiple) PB include water and / or one or more organic solvents. A pigment mixture comprising, as at least one component PC, at least two different pigments, namely, at least one organic black or inorganic black pigment P-C1 which is not a carbon black pigment and is transparent or substantially transparent to NIR radiation, or reflective or substantially reflective to NIR radiation, and at least one inorganic white pigment P-C2 which is reflective or substantially reflective to NIR radiation. Includes, Pigment P-C1 is present in an amount ranging from 0.1 to 20.0% by mass relative to the total mass of the primer coating composition, and pigment P-C2 is present in an amount ranging from 0.2 to 40.0% by mass relative to the total mass of the primer coating composition, and The primer coating obtained by applying the primer coating composition to a substrate has a lightness value L* of 38 or less according to the CIELAB system at 45°.

[0012] Preferably, the primer coating obtained by applying the primer coating composition to a substrate and curing the resulting primer coating film has a CIELAB system brightness value L* of 38 or less, more preferably 35 or less, and even more preferably 30 or less at 45°C. Preferably, curing is carried out at approximately 140°C for 25 minutes.

[0013] A further subject of the present invention is a method for forming a primer coating film at least partially on at least one surface of a substrate, the method comprising at least step (a), i.e. (a) A step of applying the primer coating composition of the present invention to at least partially one surface of an optionally pre-coated substrate to form a primer coating film on the surface of the substrate. Includes.

[0014] A further subject of the present invention is a method for forming a primer coating layer at least partially on at least one surface of a substrate, the method comprising at least step (a) and at least step (b) as defined above, i.e. (b) A step of curing the primer coating film obtained after step (a) to obtain a primer coating layer. Includes.

[0015] A further subject of the present invention is a coating film obtainable from the primer coating composition of the present invention or by the method of the present invention for forming a primer coating film, and a coating layer obtainable from the primer coating composition of the present invention or by the method of the present invention for forming a primer coating layer.

[0016] A further subject of the present invention is a substrate at least partially coated obtainable by the method of the present invention for forming a primer coating layer, which substrate is preferably not LiDAR reflective or essentially not LiDAR reflective before performing the said method.

[0017] A further subject of the present invention is a multilayer coating system present on an optionally pre-coated substrate and comprising at least three coating layers L1, L2 and L3 different from each other, namely a first coating layer L1 applied on at least a part of the optionally pre-coated substrate, a second coating layer L2 applied on the first coating layer L1, and a third top coating layer L3 applied on the second coating layer L2 wherein the first coating layer L1 is formed from the primer coating composition of the present invention, and the second coating layer L2 is formed from a base coat composition different from the primer coating composition, and the third coating layer L3 is formed from a top coat, preferably a clear coat composition different from both the primer coating composition and the base coat composition. A further subject of the present invention is a method for preparing the multilayer coating system of the present invention, which method comprises at least steps (1), (2), (3), and (4), namely

[0018] A further subject of the present invention is a method for preparing the multilayer coating system of the present invention, which method comprises at least steps (1), (2), (3), and (4), namely (1) Applying the primer coating composition of the present invention to at least a portion of an optionally pre-coated substrate and forming a first coating film on at least a portion of the optionally pre-coated substrate; (2) Applying a base coat composition different from the primer coating composition applied in step (1) to the first coating film present on the substrate obtained after step (1), and preferably forming a second coating film adjacent to the first coating film; (3) Applying a coating composition different from the compositions applied in steps (1) and (2) to the second coating film present on the substrate obtained after step (2), and preferably forming a third coating film adjacent to the second coating film, wherein the coating composition is preferably a clear coat composition, and (4) Curing together the at least second and third coating films applied in steps (2) and (3), and optionally the first coating film applied in step (1) if the first coating film was not cured before the implementation of step (2), to obtain a multi-layer coating system including at least the first, second, and third coating layers L1, L2, and L3 comprising.

[0019] A further subject of the present invention is a method of using the coating film or layer of the present invention, and / or the substrate of the present invention at least partially coated, and / or an object manufactured from said substrate, and / or the multi-layer coating system of the present invention, in LiDAR visibility applications related to vehicles and their parts.

[0020] Particularly surprising, it has been found that the primer coating compositions of the present invention can provide a dark-colored primer coating having both high IR reflectance, high NIR reflectance, and consequently high LiDAR reflectance. In particular, it has been found that a LiDAR reflectance of at least 40%, preferably at least 45%, more preferably at least 50%, even more preferably at least 55%, still more preferably at least 60%, even more preferably at least 65%, and especially at least 70% can be achieved when measured at an angle of incidence (AOI) of 0°. The LiDAR reflectance is measured according to the method disclosed in the Methods section. In particular, it has been found that an infrared solar reflectance (IRSR) of more than 30%, preferably more preferably more than 35%, and even more preferably more than 40% can be achieved. The IRSR is measured according to the method disclosed in the Methods section.

[0021] Even more surprisingly, it has been found that the primer coating composition of the present invention can provide a dark-colored primer coating that also exhibits good shielding in the UV-visible range (UV Vis), for example, a UV transmittance of less than 0.005 in the wavelength region of 280 to 500 nm. In particular, it has been found that a UV Vis transmittance of less than 0.005, preferably less than 0.003, and more preferably ≤0.002 can be achieved. The UV Vis transmittance is measured by the method disclosed in the Methods section.

[0022] Furthermore, it has been found that the primer coating composition of the present invention does not require, or is essentially unnecessary to use, carbon black to provide a primer coating, and therefore can provide a dark-colored primer coating that prevents any undesirable heat accumulation originating from any of its components, such as carbon black, especially when it is part of a multilayer coating system used in the automotive industry. In particular, the primer coating composition does not contain, or is essentially unnecessary to contain, any carbon black pigment. Rather, the primer coating composition uses other suitable organic or inorganic black pigments instead, particularly perylene pigments such as Paliogen® black L0086.

[0023] Furthermore, it has been found that the primer coating composition of the present invention can provide a dark-colored primer coating having the same or substantially the same dark color as conventional carbon black-containing primer coatings. This index is the weighted average of the color difference (mDE*) between the primer coating of the present invention and an equivalent conventional carbon black-containing primer. [Modes for carrying out the invention]

[0024] In the sense of the present invention, the term "contains," for example in relation to a primer coating composition, preferably means "consisting of." For example, in terms of a primer coating composition, in addition to all essential components present therein, one or more of the further optional components specified below herein may be included. Any component may, in each case, be present in their preferred embodiments as specified below.

[0025] Any proportion and wt.-% (mass%) of the following components present in each coating composition, such as a primer coating composition, will, in each case, total 100% by mass relative to the total mass of the coating composition, such as a primer coating composition.

[0026] As used herein, the terms “near-IR” or “near-infrared radiation or light” or “NIR” refer to electromagnetic radiation in the near-infrared range of the electromagnetic spectrum. Such near-IR electromagnetic radiation may have wavelengths of 800 nm to 2500 nm, for example, 850 nm to 2000 nm, or for example, 900 nm to 1600 nm. In particular, the NIR light used has wavelengths of 880 nm to 930 nm, with a central wavelength of 905 nm. Near-IR electromagnetic radiation sources that can be used in the present invention to generate NIR light include, without limitation, light-emitting diodes (LEDs), laser diodes, or any light source capable of emitting electromagnetic radiation having wavelengths of 800 nm to 2500 nm (near-IR range). Near-IR electromagnetic radiation sources may be used in LiDAR systems. LiDAR systems may utilize lasers to generate electromagnetic radiation having wavelengths of 900 nm to 1600 nm.

[0027] The term "pigment" is known to those skilled in the art, for example, from DIN 55943 (dated October 2001). In the sense of the present invention, "pigment" preferably refers to components in the form of powder or flakes, which are substantially, preferably completely, insoluble in the surrounding medium, such as one of the coating compositions. A pigment is preferably a colorant and / or substance that can be used as a pigment due to its magnetic, electrical and / or electromagnetic properties. The refractive index of a pigment is preferably ≥1.7, unlike that of a "filler," such as barium sulfate. The term "filler" is known to those skilled in the art, for example, from DIN 55943 (dated October 2001). Pigments can be inorganic or organic.

[0028] Primer coating composition The primer coating composition does not contain, or is essentially free of, any metallic effect pigments, and in particular does not contain, or is essentially free of, any aluminum pigments. Preferably, the primer coating composition does not contain, or is essentially free of, any effect pigments. The terms “effect pigment” and “metallic effect pigment” are described in more detail below. In this context, “essentially free” preferably means that metallic effect pigments or effect pigments are not intentionally added, and preferably, if they are present, their amount is less than 0.1% by mass, particularly less than 0.01% by mass, and most preferably less than 0.001% by mass, relative to the total mass of the primer coating composition.

[0029] The primer coating composition can be aqueous (water-based) or organic solvent (solvent-based, non-aqueous) based. Preferably, the primer coating composition is aqueous.

[0030] The terms “solvent-based” or “non-aqueous” are understood to preferably mean, for the purposes of the present invention, that an organic solvent(s) is present as a solvent(s) and / or diluent(s) in each coating composition, e.g., a primer coating composition, where each coating composition is solvent-based, and is present as a major component of any solvent and / or diluent(s) present in each coating composition, e.g., a primer coating composition. Preferably, the organic solvent(s) are present in an amount of at least 35% by mass of the total mass of the coating composition. The solvent-based coating composition preferably contains at least 40% by mass, more preferably at least 45% by mass, and very preferably at least 50% by mass of the organic solvent(s) fraction in each case, based on the total mass of the coating composition. Any conventional organic solvent known to those skilled in the art can be used as the organic solvent. The term “organic solvent” is known to those skilled in the art, in particular from Council Directive 1999 / 13 / EC of 11 March 1999. Examples of such organic solvents include heterocyclic, aliphatic, or aromatic hydrocarbons, monoalcohols, or polyhydric alcohols, particularly methanol and / or ethanol, ethers, esters, ketones, and amides, such as N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, toluene, xylene, butanol, ethyl glycol and butyl glycol and their acetates, butyl diglycol, diethylene glycol dimethyl ether, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, isophorone, or mixtures thereof. The solvent-based coating composition is preferably water-free or essentially water-free. In this context, the term "essentially" preferably means that water is not intentionally added when preparing the coating composition.

[0031] The terms “aqueous” or “water-based” are preferably understood to mean, for the purposes of the present invention, that water is present as a major component of any solvent and / or diluent present in the aqueous coating composition, e.g., a primer coating composition. Preferably, water is present in an amount of at least 35% by mass relative to the total mass of the coating composition. The aqueous coating composition preferably contains at least 40% by mass, more preferably at least 45% by mass, and very preferably at least 50% by mass of the water fraction, relative to the total mass of the coating composition in each case. The organic solvent fraction is preferably in the range of <20% by mass, more preferably 0 to <20% by mass, very preferably 0.5 to 20% by mass, or ~17.5% by mass, or ~15% by mass, or ~10% by mass, relative to the total mass of the coating composition in each case.

[0032] The terms “primer” or “primer coating composition” are known to those skilled in the art. The primer is typically applied after a cured electrodeposited coating layer has been provided on the substrate. The cured electrodeposited coating film is located beneath, and preferably adjacent to, the cured primer coating film. Thus, the primer coating composition can be applied to an optionally pre-coated substrate, and a primer coating film can be formed on the optionally pre-coated substrate. Any curing process of this primer coating film is then possible before any further coating compositions are applied.

[0033] Primer coating composition - constituent components (multiple components possible) PA The primer coating composition comprises at least one film-forming polymer P-A1 as at least one component PA, and, if P-A1 is externally crosslinkable, at least one crosslinking agent-PA2.

[0034] At least one film-forming polymer P-A1 functions as a binder. For the purposes of this invention, the term “binder” is understood to mean a non-volatile component of the coating composition involved in film formation, in accordance with DIN EN ISO 4618 (German version, dated March 2007). This term includes crosslinking agents, e.g., crosslinking agent P-A2, and additives (if these represent non-volatile components). Therefore, pigments and / or fillers contained are not included in the term “binder”. Preferably, at least one polymer P-A1 is the main binder of the coating composition. In this invention, the main binder is preferably a binder component that is present in a higher proportion of the total mass of the coating composition when no other binder components are present in the coating composition.

[0035] The term "polymer" is known to those skilled in the art and, for the purposes of this invention, encompasses polyadditives, polymers, and polycondensates. The term "polymer" includes both homopolymers and copolymers.

[0036] At least one polymer used as component P-A1 may be self-crosslinkable or non-self-crosslinkable. Suitable polymers that can be used are known from, for example, EP0228003A1, DE4438504A1, EP0593454B1, DE19948004A1, EP0787159B1, DE4009858A1, DE4437535A1, WO92 / 15405A1 and WO2005 / 021168A1.

[0037] The at least one polymer used as component P-A1 is preferably selected from the group consisting of polyurethane, polyurea, polyester, polyamide, polyether, poly(meth)acrylate and / or copolymers of the structural units of the said polymer, particularly polyurethane-poly(meth)acrylate and / or polyurethane-polyurea. The at least one polymer used as component P-A1 is particularly preferably selected from the group consisting of polyurethane, polyester, poly(meth)acrylate and / or copolymers of the structural units of the said polymer. In the context of the present invention, the terms “(meth)acrylic” or “(meth)acrylate” each include the meanings of “methacrylic” and / or “acrylic” or “methacrylate” and / or “acrylate”.

[0038] Preferred polyurethanes are described, for example, on pages 4, line 19 to 11, line 29 (polyurethane prepolymer B1) of German patent application DE19948004A1, on pages 3, line 24 to 5, line 40 of European patent application EP0228003A1, on pages 38 to 8, line 9 of European patent application EP0634431A1, and on pages 2, line 35 to 10, line 32 of International patent application WO92 / 15405.

[0039] Preferred polyethers are described, for example, in WO2017 / 097642A1 and WO2017 / 121683A1.

[0040] Preferred polyesters are described, for example, in DE4009858A1, columns 6, line 53 to 7, line 61 and 10, line 24 to 13, line 3, or in WO2014 / 033135A2, pages 2, line 24 to 7, line 10, and 28, line 13 to 29, line 13. Similarly preferred polyesters are those having a dendritic or stellate structure, as described, for example, in WO2008 / 148555A1.

[0041] Preferred polyurethane-poly(meth)acrylate copolymers (e.g., (meth)acrylated polyurethanes) and their preparations are described, for example, on pages 3, line 21 to 20, line 33 of WO91 / 15528A1, and on pages 27 to 6, line 22 of DE4437535A1.

[0042] Preferred (meth)acrylic copolymers are OH-functional. Examples of hydroxyl-containing monomers include hydroxyalkyl esters of acrylic or methacrylic acid that can be used to prepare copolymers. Non-limiting examples of hydroxyl-functional monomers include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl-(meth)acrylate, hydroxyhexyl (meth)acrylate, propylene glycol mono(meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, pentaerythritol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, reaction products of these with epsilon-caprolactone, and other hydroxyalkyl-(meth)acrylates having up to about 10 carbon-branched or linear alkyl groups, and mixtures thereof. Hydroxyl groups on vinyl polymers, such as (meth)acrylic polymers, may be generated by other means, such as ring-opening of glycidyl groups, e.g., from copolymerized glycidyl methacrylate, by organic acids or amines. Hydroxyl functionality may also be introduced through thio-alcohol compounds, including but not limited to 3-mercapto-1-propanol, 3-mercapto-2-butanol, 11-mercapto-1-undecanol, 1-mercapto-2-propanol, 2-mercaptoethanol, 6-mercapto-1-hexanol, 2-mercaptobenzyl alcohol, 3-mercapto-1,2-propanediol, 4-mercapto-1-butanol, and combinations thereof. Any of these methods may be used to prepare useful hydroxyl-functionalized (meth)acrylic polymers.Examples of suitable comonomers that may be used include, but are not limited to, α,β-ethylenically unsaturated monocarboxylic acids containing 3 to 5 carbon atoms, such as acrylic acid, methacrylic acid, and crotonic acid, and alkyl and cycloalkyl esters, nitriles, and amides of acrylic acid, methacrylic acid, and crotonic acid; α,β-ethylenically unsaturated dicarboxylic acids containing 4 to 6 carbon atoms and their anhydrides, monoesters, and diesters, vinyl esters, vinyl ethers, vinyl ketones, and aromatic or heterocyclic aliphatic vinyl compounds. Typical examples of suitable esters of acrylic acid, methacrylic acid, and crotonic acid include esters obtained from reactions with saturated aliphatic alcohols containing 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, hexyl, 2-ethylhexyl, dodecyl, 3,3,5-trimethylhexyl, stearyl, lauryl, cyclohexyl, alkyl-substituted cyclohexyl, alkanol-substituted cyclohexyl, such as 2-tert-butyl and 4-tert-butylcyclohexyl, 4-cyclohexyl-1-butyl, 2-tert-butylcyclohexyl, 4-tert-butylcyclohexyl, 3,3,5,5-tetramethylcyclohexyl, tetrahydro This includes, but is not limited to, furfuryl, isobornyl acrylates, methacrylates and crotonates, unsaturated dialkanoates and anhydrides, such as fumaric acid, maleic acid, itaconic acid and anhydrides, and alcohols, such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol and tert-butanol, and their mono- and diesters, such as maleic anhydride, dimethyl maleate and monohexyl maleate, vinyl acetate, vinyl propionate, vinyl ethyl ether and vinyl ethyl ketone, styrene, α-methylstyrene, vinyltoluene, 2-vinylpyrrolidone and p-tert-butylstyrene. (Meth)acrylic copolymers may be prepared using prior art, for example, by heating monomers in the presence of polymerization initiators and optionally chain transfer agents.

[0043] Suitable poly(meth)acrylates can also be prepared by multi-step free-radical emulsion polymerization of olefinic unsaturated monomers in water and / or organic solvents. Examples of seed-core-shell polymers (SCS polymers) obtained by this method are disclosed in WO2016 / 116299A1.

[0044] Preferred polyurethane-polyurea copolymers are preferably polyurethane-polyurea particles having a Z-average particle size of 40 to 2000 nm, wherein each polyurethane-polyurea particle contains, in its reacted form, at least one isocyanate group-containing polyurethane prepolymer containing an anionic group and / or a group convertible to an anionic group, and at least one polyamine containing two primary amino groups and one or two secondary amino groups. Preferably, such copolymers are used in the form of aqueous dispersions. Such polymers can, in principle, be prepared by conventional polyaddition of polyisocyanates with polyols and polyamines, for example.

[0045] The polymer used as component P-A1 preferably has a reactive functional group that enables a crosslinking reaction. Any common crosslinkable reactive functional group known to those skilled in the art may be present. Preferably, the polymer used as component P-A1 has at least one reactive functional group selected from the group consisting of primary amino groups, secondary amino groups, hydroxyl groups, thiol groups, carboxyl groups, and carbamate groups. Preferably, the polymer used as component P-A1 has a functional hydroxyl group and / or a carbamate group.

[0046] Preferably, the polymer used as component P-A1 is hydroxyl functional and more preferably has an OH value in the range of 15 to 400 mg KOH / g, more preferably 20 to 250 mg KOH / g.

[0047] The polymer used as component P-A1 is particularly preferably a hydroxyl-functional polyurethane-poly(meth)acrylate copolymer, a hydroxyl-functional polyester, and / or a hydroxyl-functional polyurethane-polyurea copolymer.

[0048] Furthermore, the primer coating composition may contain at least one typical crosslinking agent P-A2 known on its own. The crosslinking agent is included in the film-forming non-volatile components of the coating composition and is therefore included in the general definition of “binder”.

[0049] Any conventional crosslinking agent can be used. This includes melamine resins, preferably melamine aldehyde resins, more preferably melamine formaldehyde resins, blocked polyisocyanates, polyisocyanates having free (unblocked) isocyanate groups, crosslinking agents having amino groups such as secondary and / or primary amino groups, crosslinking agents having epoxide groups and / or hydrazide groups, and crosslinking agents having carbodiimide groups, insofar as the functional groups of the particular crosslinking agent are suitable for reacting with the crosslinkable functional groups of the film-forming polymer used as a binder in the crosslinking reaction. For example, crosslinking agents having blocked or free isocyanate groups can be reacted with film-forming polymers having crosslinkable OH groups and / or amino groups at high temperatures for 1K formulations and at ambient temperatures for 2K formulations.

[0050] The crosslinking agent, if present, is preferably at least one aminoplast resin and / or at least one blocked or free polyisocyanate, and is preferably an aminoplast resin. Among aminoplast resins, melamine resins such as melamineformaldehyde resin are particularly preferred. Preferably, the melamineformaldehyde resin, preferably the melamineformaldehyde resin, has in each case at least one of an imino group, an alkylol group, and an etherified alkylol group as a functional group, which is reactive with the functional groups of polymer P-A1. An example of an alkylol group is a methylol group.

[0051] Primer coating composition - constituent components (multiple components possible) PB The primer coating composition comprises water and / or one or more organic solvents as constituent(s) PB. This is as previously stated herein in relation to the terms “aqueous” and “solvent system”.

[0052] Primer coating composition - Components (multiple components possible) including P-C1, P-C2, and P-C3 PC The primer coating composition includes a pigment mixture as at least one component PC, which comprises at least two different pigments, namely, at least one organic black or inorganic black pigment P-C1 that is not a carbon black pigment and is transparent or substantially transparent to NIR radiation, or reflective or substantially reflective to NIR radiation, and at least one inorganic white pigment P-C2 that is reflective or substantially reflective to NIR radiation. The term "NIR radiation" is defined above and, in particular, covers a wavelength range of 800 nm to 2500 nm, for example 850 nm to 2000 nm, or for example 900 nm to 1600 nm, most preferably at least 880 nm to 930 nm, with a central wavelength of 905 nm. Of course, the primer coating composition may also include a pigment mixture PC, the component comprising at least two pigments P-C1 and at least one pigment P-C2, one of which is transparent or substantially transparent to NIR radiation and the other is reflective or substantially reflective to NIR radiation. Preferably, pigment P-C1 is transparent or substantially transparent to NIR radiation. Since the primer coating composition does not contain or is essentially free of any metallic effect pigments, it is clear that none of the pigments present therein (including the pigments in the pigment mixture PC) can be such metallic effect pigments.

[0053] Pigment P-C1 is transparent or substantially transparent to NIR radiation, or reflective or substantially reflective to NIR radiation, while pigment P-C2 is necessarily reflective to NIR radiation or substantially reflective. The term "substantially" in relation to "substantially transparent" means that preferably, a major portion of the NIR radiation wavelength range, preferably 800 nm to 2500 nm, e.g., 850 nm to 2000 nm or e.g., 900 nm to 1600 nm, is transmitted by each pigment, more preferably at least 80%, 90%, or 95% of the wavelength range is transmitted. The term "substantially" in relation to "substantially reflective" means that preferably, 25% to <100% of the NIR radiation wavelength range of 900 nm to 1600 nm is reflected by each pigment.

[0054] Pigment P-C1 is present in an amount of 0.1 to 20.0% by mass, preferably 0.2 to 15.0% by mass, more preferably 0.5 to 12.0% by mass, even more preferably 1.0 to 10.0% by mass, even more preferably 1.5 to 8.5% by mass, and even more preferably 2.0 to 7.0% by mass, relative to the total mass of the primer coating composition, and pigment P-C2 is present in an amount of 0.2 to 40.0% by mass, preferably 0.5 to 35.0% by mass, more preferably 1.0 to 30.0% by mass, even more preferably 2.0 to 25.0% by mass, even more preferably 4.0 to 20.0% by mass, and even more preferably 5.0 to 18.0% by mass, relative to the total mass of the primer coating composition.

[0055] Preferably, the amount of pigment P-C2 in the primer coating composition exceeds the amount of pigment P-C1, and more preferably, the relative mass ratio of pigment P-C2 to P-C1 is in the range of 15:1 to 1.1:1, more preferably 12:1 to 1.5:1, and even more preferably 10:1 to 2:1.

[0056] Preferably, the color of pigment P-C1 is characterized by an L* value of less than 17, more preferably less than 15, at 45° according to the CIELAB system, and a* and b* values ​​greater than -4 and less than 9, more preferably less than 6, most preferably less than 4, and preferably greater than 0. Preferably, the color of pigment P-C2 is characterized by an L* value greater than 85, preferably greater than 90, at 45° according to the CIELAB system, an a* value greater than -2 and less than 2, preferably less than 0, and a b* value less than 6, preferably greater than 0, more preferably greater than 2 or 3.

[0057] Preferably, At least one black pigment P-C1 is a black pigment having a master tone color with L*<17, a*>-4 and <9, and b*>-4 and <9 values ​​at 45° according to the CIELAB system, and At least one white pigment P-C2 is a white pigment having a mastertone color with L*>85, a*>-2 and <2, and b*>0 and <6 values ​​at 45° according to the CIELAB system.

[0058] The terms “mastone color” or “mastone color of complete opacity” are used and understood as they are commonly used and understood in colorimetry. “Masttone color” is defined as the color obtained by applying coating layers containing the respective pigments to a thickness that prevents the transmission of black and white color information, so as to completely cover a black and white substrate (typically, so-called “checkerboard” patterns, which are partially black and partially white, are used). Each layer thickness is obtained by repeatedly spraying the coating composition until the L*, A*, and B* colorimetric data are the same for the coated black and white portions of the substrate, respectively, and as a result, it is ensured that the color-specific information of the substrate is not confused with the inherent values ​​of the pigments. Further details are disclosed in the section on the method of the present invention. Thus, the term “mastone color” can be used to determine whether a particular pigment is a black pigment or a white pigment in the sense of this term.

[0059] Preferably, At least one pigment P-C1 is selected from the group consisting of iron / chromium oxide compounds, manganese ferrite black oxide, calcium manganese titanium oxide, perylene pigments, azomethine pigments and mixtures thereof, preferably selected from perylene pigments, azomethine pigments and mixtures thereof, particularly pigment numbers 31 and 32 (PBk31 and PBk32; CI name), most preferably selected from perylene pigments, and / or At least one pigment P-C2 is selected from the group consisting of titanium dioxide-based pigments or titanium dioxide-containing pigments, and is preferably selected from titanium / aluminum / silicon oxide-based pigments and rod-shaped aluminum-doped titanium dioxide pigments.

[0060] The rod-shaped pigments preferably have a length dimension of 1 to 5, for example, 2 to 4 μm, and a heart dimension of 0.2 to 0.6, for example, 0.3 to 0.5 μm. Preferably, the rod-shaped pigments have an average D50 value, i.e., median particle size, in the range of 0.01 μm to 1 μm, determined by laser particle size analysis according to ISO 13320-1 (determined with a CILAS 1064 instrument).

[0061] Commercially available P-C2 pigments include, for example, Tipaque Black SG103 (from Ishihara) and Paliogen® Black L0086 from BASF. Commercially available white P-C2 pigments are selected from, for example, Altiris 550 and Altiris 800 (both from Vanator), Tipaque PFR404 (from Ishihara), Ti-Pure® R-906, and Kronos® 2310.

[0062] The mass ratio of [(P-C1)+(P-C2)] / [(P-A1)+(P-A2)] in the primer coating composition is preferably in the range of 0.005 to 1.2, more preferably in the range of 0.01 to 1.0, and most preferably in the range of 0.015 to 0.75.

[0063] Preferably, the primer coating composition further comprises at least one preferably organic or inorganic, more preferably organic, coloring pigment P-C3, which is different from both pigments P-C1 and P-C2 and is not a carbon black pigment, and is more preferably selected from blue, red, and purple organic pigments.

[0064] Preferably, the primer coating composition does not contain any carbon black pigment, or is essentially free of any. "Essentially free" means that carbon black pigment is not intentionally added, and preferably, if present, its amount is less than 0.1% by mass, particularly less than 0.01% by mass, and most preferably less than 0.001% by mass, relative to the total mass of the coating composition.

[0065] The primer coating obtained by applying the primer coating composition to a substrate has a lightness value L* of 38 or less on the CIELAB system at 45°. Preferably, the primer coating obtained by applying the primer coating composition to a substrate has a lightness value L* of 35 or less, more preferably 30 or less. Preferably, the primer coating obtained by applying the primer coating composition to a substrate has a lightness value L* of 0.1 to 38 or less on the CIELAB system at 45°.

[0066] Preferably, the primer coating obtained by applying the primer coating composition to a substrate and curing the resulting primer coating film has a CIELAB system brightness value L* of 38 or less, more preferably 35 or less, and even more preferably 30 or less at 45°C. Preferably, curing is performed at approximately 140°C for 25 minutes. Preferably, the primer coating obtained by applying the primer coating composition to a substrate and curing the resulting primer coating film has a CIELAB system brightness value L* in the range of 0.1 to 38 or less at 45°C.

[0067] Preferably, a CIELAB system lightness value L* of 38 or less at 45° is desirable to ensure that the primer coating is dark in color. Preferably, a CIELAB system lightness value L* of 38 or less at 45° is achieved by incorporating at least two types of pigments, P-C1 and P-C2, into the primer coating composition in the amounts shown above and below.

[0068] Preferably, the primer coating obtained by applying the primer coating composition to a substrate can reflect NIR light, preferably NIR light having a wavelength of 800 to 2500 nm.

[0069] Preferably, the primer coating obtained by applying the primer coating composition to the substrate is Measured at an incident angle of 0°, the LiDAR reflectance is at least 40%, preferably at least 45%, more preferably at least 50%, even more preferably at least 55%, still more preferably at least 60%, even more preferably at least 65%, and especially at least 70%. UV Vis transmittance of less than 0.005, preferably less than 0.003, more preferably 0.002 or less, and / or Infrared solar reflectance (IRSR) of more than 30%, preferably more than 35%, and more preferably more than 40% It has.

[0070] Preferably, the primer coating obtained by applying the primer coating composition to a substrate and curing the resulting primer coating film has a LiDAR reflectance of at least 40%, preferably at least 45%, more preferably at least 50%, even more preferably at least 55%, even more preferably at least 60%, even more preferably at least 65%, and particularly at least 70%, measured at an incident angle of 0°. Preferably, the primer coating obtained by applying the primer coating composition to a substrate and curing the resulting primer coating film has a UV Vis transmittance of less than 0.005, preferably less than 0.003. Preferably, the primer coating obtained by applying the primer coating composition to a substrate and curing the resulting primer coating film has an infrared solar reflectance (IRSR) of more than 30%, preferably more than 35%, and even more preferably more than 40%. Preferably, curing is carried out at about 140°C for 25 minutes in each case.

[0071] Method for forming a primer coating film and a primer coating layer A further subject of the present invention is a method for forming a primer coating film at least partially on at least one surface of a substrate, the method comprising at least step (a), i.e. (a) A step of applying the primer coating composition of the present invention to at least partially one surface of an optionally pre-coated substrate to form a primer coating film on the surface of the substrate. Includes.

[0072] A further subject of the present invention is a method for forming a primer coating layer at least partially on at least one surface of a substrate, the method comprising at least step (a) and at least step (b) as defined above, i.e. (b) A step of curing the primer coating film obtained after step (a) to obtain a primer coating layer. Includes.

[0073] In relation to the primer coating composition of the present invention and any preferred embodiments thereof, all preferred embodiments described above are also preferred embodiments of the method of the present invention for preparing primer coating films and primer coating layers.

[0074] Primer coating film and primer coating layer Further subject matter of the present invention includes a coating film that can be obtained from the primer coating composition of the present invention or by the method of the present invention for forming a primer coating film, and a coating layer that can be obtained from the primer coating composition of the present invention or by the method of the present invention for forming a primer coating layer.

[0075] Any preferred embodiments described above relating to the primer coating composition, primer coating film, and method of the present invention for preparing a primer coating layer, and each of those preferred embodiments in each case, are also preferred embodiments of the primer coating film and primer coating layer of the present invention.

[0076] Coated substrate A further subject of the present invention is a substrate that can be obtained by the method of the present invention for forming a primer coating layer, wherein the substrate is preferably not LiDAR reflective or is not LiDAR reflective before the method is performed.

[0077] The primer coating composition, primer coating film, and method for preparing the primer coating layer of the present invention, as well as all preferred embodiments described above relating to the primer coating film and primer coating layer of the present invention, and each of those preferred embodiments, are also preferred embodiments of the coated substrate of the present invention.

[0078] Multilayer coating system A further subject of the present invention is a coating layer L1, L2, and L3 which is optionally present on a pre-coated substrate and is different from each other, i.e. A first coating layer L1 applied to at least a portion of an optionally pre-coated substrate, A second coating layer L2 applied on top of the first coating layer L1, and A third top coating layer L3 applied on top of the second coating layer L2. It is a multilayer coating system that includes, The first coating layer L1 is formed from the primer coating composition of the present invention, the second coating layer L2 is formed from a base coat composition different from the primer coating composition, and the third coating layer L3 is formed from a top coat, preferably a clear coat composition different from both the primer coating composition and the base coat composition.

[0079] Preferably, at least the second and third coating layers L2 and L3 are located adjacent to each other. More preferably, the first and second coating layers L1 and L2 are also located adjacent to each other.

[0080] Preferably, both the primer coating composition used to form the first coating layer L1 and the base coat composition used to form the second coating layer L2 do not contain any carbon black, or are essentially carbon black. Preferably, the top coat composition used to form the third coating layer L3 also does not contain any carbon black, or is essentially carbon black. "Essentially carbon black" means that carbon black pigment is not intentionally added, and preferably, if present, the amount is less than 0.1% by mass, particularly less than 0.01% by mass, and most preferably less than 0.001% by mass, relative to the total mass of each coating composition.

[0081] The primer coating composition, primer coating film, and method for preparing the primer coating layer of the present invention, the primer coating film and primer coating layer of the present invention, and all preferred embodiments described above relating to the coated substrate of the present invention, as well as the preferred embodiments in each case, are also preferred embodiments of the multilayer coating system of the present invention.

[0082] Each of the coating compositions used in the method of the present invention, particularly in each of the steps (1) to (3) described later, and / or in the preparation of the multilayer coating system, can be aqueous (water-based) or organic solvent (solvent-based, non-aqueous) based. Preferably, the top coat, preferably the clear coat composition, is organic solvent (solvent-based, non-aqueous). Preferably, the base coat composition is aqueous or solvent-based, and more preferably aqueous.

[0083] Preferably, the multilayer coating system of the present invention can reflect NIR light, preferably NIR light having a wavelength of 800 to 2500 nm. In particular, the first coating layer L1 can reflect NIR light, preferably NIR light having a wavelength of 800 to 2500 nm.

[0084] The multilayer coating system of the present invention is particularly suitable for coating automobile vehicle bodies or their components, including metal substrates and plastic substrates such as polymer substrates. Therefore, preferred substrates are automobile vehicle bodies or their components.

[0085] Suitable metal substrates for use in the present invention are any conventionally used substrates known to those skilled in the art. The substrates used in the present invention are preferably metal substrates, more preferably steel, preferably steel selected from the group consisting of bare steel, cold-rolled steel (CRS), hot-rolled steel, galvanized steel, e.g., hot-dip galvanized steel (HDG), alloy galvanized steel (e.g., Galvalume, Galvannealed, or Galfan), and aluminum-plated steel, as well as aluminum, magnesium, and Zn / Mg alloys and Zn / Ni alloys. Particularly suitable substrates are parts of vehicle bodies for production or complete automobile bodies.

[0086] Preferably, a thermoplastic polymer is used as the plastic substrate. Suitable polymers include poly(meth)acrylates, including polymethyl(meth)acrylate and polybutyl(meth)acrylate; polyesters, including polyethylene terephthalate, polybutylene terephthalate, polyvinylidene fluoride, polyvinyl chloride, polycarbonate, and polyvinyl acetate; polyamides; polyolefins, such as polyethylene, polypropylene, polystyrene, and polybutadiene; polyacrylonitrile; polyacetal; polyacrylonitrile-ethylene-propylene-diene-styrene copolymer (A-EPDM); ASA (acrylonitrile-styrene-acrylic ester copolymer); and ABS (acrylonitrile-butadiene-styrene copolymer); polyetherimide; phenolic resins; urea resins; melamine resins; alkyd resins; epoxy resins; polyurethanes, including TPU; polyetherketones; polyphenylene sulfide; polyethers; polyvinyl alcohol; and mixtures thereof. Polycarbonate and poly(meth)acrylate are particularly preferred.

[0087] The substrate used in the present invention is preferably a metal substrate pretreated with at least one metal phosphate, such as zinc phosphate, and / or at least one oxalate. This type of phosphate pretreatment is usually performed after the substrate has been washed and before it is electrodeposited, and is a conventional pretreatment step, particularly in the automotive industry.

[0088] As outlined above, the substrate used may be a pre-coated substrate, i.e., a substrate having at least one cured coating film. The substrate can be pre-coated with a cured electrodeposited coating layer.

[0089] The term "base coat" is well known in the art and is defined, for example, in Roempp Lexikon, *paints and printing inks*, Georg Thieme Verlag, 1998, 10th edition, page 57. Therefore, base coats are used, particularly in automotive painting and general industrial paint coloring, to provide coloring and / or optical effects by using a base coat as an intermediate coating composition.

[0090] Preferably, the base coat composition contains at least one pigment that is not a carbon black pigment and is not absorbent to NIR radiation, and more preferably, at least one pigment that is transparent or substantially transparent to NIR radiation, or reflective or substantially reflective to NIR radiation. The at least one pigment present in the base coat composition is preferably transparent or substantially transparent to NIR radiation and may be identical or different from the pigment P-C1 present in the primer coating composition. Preferably, the at least one pigment is selected from perylene pigments, azomethine pigments and mixtures thereof, particularly pigment numbers 31 and 32 (PBk31 and PBk32; CI names). Furthermore, at least one effect pigment, such as a metallic effect pigment, may be additionally or alternatively present in the base coat composition. If, in addition to at least one pigment that is transparent or substantially transparent to NIR radiation, such as a perylene pigment, at least one effect pigment, such as a metallic effect pigment, is present, the amount of the effect pigment present in the base coat composition preferably exceeds the amount of the at least one pigment that is transparent or substantially transparent to NIR radiation. Preferably, if present, the metallic effect pigment is present in the form of flakes, more preferably in the form of opaque flakes. Preferably, the pigment has a D50 value, i.e., median particle size, in the range of 5 μm to 100 μm, and more preferably in the range of 15 μm to 30 μm, as determined by laser particle size analysis according to ISO 13320-1 (determined with a CILAS 1064 instrument).

[0091] Those skilled in the art are familiar with the concept of effect pigments. A corresponding definition can be found, for example, in Roempp Lexikon, Lacke und Druckfarben, Georg Thieme Verlag, 1998, 10th edition, pp. 176 and 471. A general definition of pigment and further specializations thereof are provided in DIN 55943 (dated October 2001). Effect pigments are preferably pigments that impart optical effects, or both color and optical effects, particularly optical effects. Thus, the terms “optical effect and color pigments,” “optical effect pigments,” and “effect pigments” are preferably interchangeable.

[0092] The term "metallic effect pigment" is used in accordance with EN ISO 18451-1:2019 (Pigments, dyes and extenders - Terminology - Part 1). It is defined as a pigment in the form of a small plate made of metal. In this invention, the term "made of metal" does not exclude the presence of additional oxide layers, such as a silicon dioxide layer, which may be surface modifications of the metallic effect pigment. The term "metal" as used in "metallic effect pigment" also includes metals and metal alloys. Metallic effect pigments can be oriented parallel to each other, as already outlined above, and exhibit a metallic luster due to the reflection of light on the flakes.

[0093] Typical metals and alloys used in metallic effect pigments are aluminum and its alloys. In the present invention, the most preferred and suitable aluminum effect pigments are plate-shaped, which may or may not be coated. In particular, preferred aluminum pigments are preferably coated to inhibit their reaction with water in the aqueous base coat composition. Such inhibition can be achieved, for example, by organophosphorus stabilization, passivation of the aluminum pigment by a chemical treatment layer, such as chromate treatment, or encapsulation using a protective layer such as a polymer coating or silica coating (Peter Wissling, "Metallic Effect Pigments", Vincentz Network 2006, pp. 85-89). Such aluminum effect pigments are commercially available, for example, from ECKART GmbH (Germany) under the trade names STAPA® Hydroxal (stabilized), STAPA® Hydrolux (chromate treated), and STAPA® Hydrolan (silica encapsulated). Further modification of the pigment surface is also possible, for example, by modification with nonpolar groups such as alkyl groups that produce a so-called semi-leafing effect.

[0094] Metallic effect pigments, particularly aluminum effect pigments, may be coated with an oxide layer such as a silica layer, which further helps stabilize the pigment against mechanical shock and, in particular, improves the stability of the circulation line. In the present invention, silica-encapsulated aluminum metallic effect pigments are most preferred. Preferably, the amount of silica is in the range of 3 to 15% by mass, more preferably 5 to 12% by mass, and most preferably 6 to 10% by mass, relative to the total amount of aluminum and silica in such preferred aluminum effect pigments. However, the term “metallic effect pigment” is understood to encompass such coated pigments, and the total mass of such coated metallic effect pigments is understood to be the mass of the metallic effect pigment. Thus, the mass includes the coating material.

[0095] Alternatively, or additionally, the base coat composition comprises at least one pearlescent or interfering pigment. Preferably, such pigment exists in the form of flakes, more preferably in the form of opaque flakes. Preferably, the pigment is selected from mica pigments coated with at least one metal or metalloid oxide, such as aluminum oxide and / or silica. Examples of commercially available pigments for use as pigments B-C1 include, for example, Mearlin® Bright Silver 1303Z-Ext (mica flakes coated with titanium dioxide and / or iron oxide), and Iriodin. (登録商標) 9225 Rutile Blue Pearl SW (Mica flakes) and Iriodin (登録商標) This is 9605 Blue-Shade Silver SW (mica flakes). Other examples include Mearlin® Bright Silver 1303V and Iriodin. (登録商標) 9602 is one example.

[0096] Method for preparing multilayer coating systems A further subject of the present invention is a method for preparing the multilayer coating system of the present invention, the method comprising at least steps (1), (2), (3), and (4), namely (1) A step of applying the primer coating composition of the present invention to at least a portion of a pre-coated substrate to form a first coating film on at least a portion of the pre-coated substrate. (2) A step of applying a base coat composition different from the primer coating composition applied in step (1) to a first coating film present on the substrate obtained after step (1), preferably forming a second coating film adjacent to the first coating film. (3) A step of applying a coating composition different from the compositions applied in steps (1) and (2) to a second coating film present on a substrate obtained after step (2), preferably forming a third coating film adjacent to the second coating film, wherein the coating composition is preferably a clear coat composition, and (4) A step of curing together the at least second and third coating films applied in steps (2) and (3), and optionally, the first coating film applied in step (1) if the first coating film was not cured before step (2), to obtain a multilayer coating system including at least first, second, and third coating layers L1, L2, and L3. Includes.

[0097] All preferred embodiments described above relating to the primer coating composition, primer coating film, and method for preparing the primer coating layer of the present invention, the primer coating film and primer coating layer of the present invention, the coated substrate of the present invention, and the multilayer coating system of the present invention, as well as the preferred embodiments in each case, are also preferred embodiments of the method for preparing the multilayer coating system of the present invention.

[0098] Curing is preferably selected from chemical curing, e.g., chemical crosslinking, radiation curing, and / or physical drying (non-chemical curing), in each case carried out at room temperature or high temperature, and more preferably selected from chemical curing, e.g., chemical crosslinking, and / or physical drying (non-chemical curing), in each case carried out at room temperature or high temperature. The curing temperature may vary from 80°C to 160°C.

[0099] Each of the coating compositions used in steps (1), (2), and (3) of the method of the present invention, and / or used to prepare the coating layers L1, L2, and L3 of the multilayer coating system of the present invention, may contain one or more commonly used additives, in addition to the components outlined in more detail below, depending on the desired application. For example, each of the coating compositions may independently contain at least one additive selected from the group consisting of reactive diluents, catalysts, light stabilizers, antioxidants, degassing agents, emulsifiers, slip additives, polymerization inhibitors, plasticizers, free radical polymerization initiators, adhesion promoters, flow regulators, film-forming aids, sagging regulators (SCAs), flame retardants, corrosion inhibitors, drying agents, thickeners, biocides, and / or matting agents. They can be used in known and conventional proportions. Preferably, their content is 0.01 to 20.0% by mass, more preferably 0.05 to 15.0% by mass, particularly preferably 0.1 to 10.0% by mass, most preferably 0.1 to 7.5% by mass, particularly 0.1 to 5.0% by mass, and most preferably 0.1 to 2.5% by mass, based on the total mass of each coating composition.

[0100] How to use A further subject of the present invention is a method of using the coating film or layer of the present invention, and / or a substrate of the present invention that is at least partially coated, and / or an object manufactured from the substrate, and / or a multilayer coating system of the present invention, in LiDAR visibility applications relating to vehicles and their components.

[0101] All preferred embodiments described above relating to the primer coating composition, primer coating film, and method for preparing the primer coating layer of the present invention, the primer coating film and primer coating layer of the present invention, the coated substrate of the present invention, the multilayer coating system of the present invention, and the method for preparing the multilayer coating system of the present invention, as well as each preferred embodiment in each case, are also preferred embodiments of the method of use of the present invention.

[0102] By using the present invention, autonomous driving systems, such as self-driving vehicles and ADAS-equipped vehicles, can particularly benefit from better infrared and LiDAR visibility.

[0103] method 1. Determination of the non-volatile fraction The solids content, including total solids (non-volatile content, solids percentage), is measured at 110°C for 60 minutes, according to DIN EN ISO3251:2019-09.

[0104] 2. Measurement of color values The L*a*b* color space or L*a*b* color model (i.e., the CIELAB color model) is known to those skilled in the art. The L*a*b* color model is standardized, for example, in DIN EN ISO / CIE11664-4:2020-03. Each recognizable color in the L*a*b* color space is described by a specific color position having coordinates {L*, a*, b*} in a three-dimensional coordinate system. The a* axis represents the green or red portion of the color, with negative values ​​representing green and positive values ​​representing red. The b* axis represents the blue or yellow portion of the color, with negative values ​​representing blue and positive values ​​representing yellow. Thus, a lower number indicates a bluer color. The L* axis is perpendicular to this plane and represents lightness (brightness). The color value L* is determined according to ASTM E284-81a. The values ​​are measured using a BYK-mac i (BYK-Gardner) instrument in accordance with ASTM D2244, E308, E1164, and E2194. Sample analysis is performed according to the BYK-mac i spectrophotometer standard operating procedure, following the measurement of color, luster, and graininess. The sample to be analyted is carefully wiped with a microfiber cloth. The BYK-mac i instrument is then placed on the substrate surface, and measurements are taken at angles of 15°, 45°, and 110° using a D65 light source, recording data for each angle. This measurement is performed on individual panels at at least three different positions, and the values ​​are reported as the average of the trials. The weighted average of the two color differences (mDE*) is given by the following formula:

number

[0105] 3. Determination of LiDAR reflectivity LiDAR measurements of primers or multilayer coatings at different angles were performed using a Velodyne VLP-16 instrument (905 nm) at a distance of 1 m. The instrument was calibrated using Permaflect's 10%, 50%, and 80% calibration tiles, yielding reflectances of 10%, 50%, and 80% at a 0° AOI, respectively.

[0106] 4. UV measurement For UV measurement, a primer was sprayed onto the Tedlar film TTR10SG4 to a thickness of 14 μm. Measurements were performed using a Shimadzu Scientific 2600 series instrument. UV transmittance was measured from 290 nm to 700 nm using a blank film as a control. UV reflectance was determined by subtracting the absorbance of the plain Tedlar film.

[0107] 5. Total Solar Reflectance (TSR) Total solar reflectance was measured according to ASTM E903.

[0108] 6. IRSR (Infrared Solar Reflectance) IRSR (Infrared Solar Reflectance) is calculated in the visible range (300nm to 700nm) using the following formula:

number

number

number

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[0109] 7. Measurement of master tone color of pigment(s) P-C1 and P-C2. The “master tone color” was determined as the color obtained by applying a coating layer containing each pigment to a thickness that completely covers a black and white substrate (typically, so-called “checker tiles” that are partially black and partially white are used), so as to completely cover the black and white color information (complete shielding). The coating compositions used to determine the master tone color for the purposes of the present invention are listed in the table below. For each pigment P-C1 or P-C2, or a mixture of each pigment P-C1 or a mixture of pigment P-C2, a pigment paste was prepared by vibration and shaking. The material components of each pigment paste were as follows: 30 parts by mass of each solid pigment (i.e., pigment P-C1 or pigment P-C2 or a mixture of pigment P-C1 or a mixture of pigment P-C2), 15 parts by mass of water, 2 parts by mass of butyl cellosolve, 39.2 parts by mass of polyurethane pulverized resin, 4.8 parts by mass of Pluracol 1010 polyol, and 9 parts by mass of Byk 184. The pigment paste was incorporated into the coating composition so that the volume concentration of the pigment was approximately 20%. Each layer thickness was obtained by repeatedly spraying the coating composition until the L*, A*, and B* colorimetric data were the same for the coated black and white areas of the substrate, respectively, ensuring that the substrate's color-specific information was not confused with the pigment's inherent values. Typically, this is achieved with a coating thickness of approximately 20 μm. [Table 1] [Examples]

[0110] The following embodiments further illustrate the present invention but are not intended to limit its scope. "Parts by mass (Pbw)" means parts by mass. Unless otherwise defined, "parts" means "parts by mass".

[0111] 1. Preparation of primer coating composition 1.1 Comparative Example Primer coating composition P1C1 was prepared by mixing the components shown in Table 1 in this order.

[0112] [Table 2]

[0113] White pigment paste WP1 had a solid content of 63% by mass relative to the total mass of WP1 and contained 49% by mass of commercially available titanium dioxide white reflective pigment (Kronos® 2310). Black pigment paste BP1 contained 10% by mass of Monarch® 1400, a carbon black pigment commercially available from Cabot, relative to its total mass. Binder dispersion BD1 contained acrylic resin and had a solid content (resin solids) of 27% by mass. Crosslinking agent dispersion CD1 contained crosslinking agent resin (Cymel® 203) and polyester resin and had a total solid content (resin solids) of 55.54% by mass. OS1 was a mixture of organic solvents commercially available as Isopar® and Shellsol® OMS. OS2 was a mixture of organic solvents commercially available as Exxal® 13.

[0114] 1.2 The primer coating composition P1I1 of the present invention was prepared by mixing the components shown in Table 2a in this order.

[0115] [Table 3]

[0116] WP1, BD1, CD1, and OS2 have already been described in relation to P1C1. OS3 was a mixture of organic solvents commercially available as Isopar®. Black pigment paste BP2 contained 18.5% by mass of Paliogen® L0086 (an organic black pigment commercially available from BASF) (not a carbon black pigment) based on its total mass. BP2 further contained 21% by mass of polyacrylic resin solids based on its total mass. Color pigment paste CP1 was a commercially available pigment paste containing red pigment (Hostaperm® Scarlet GO). In each case, CP1 contained 25% by mass of pigment and 22% by mass of polyurethane resin based on its total mass. Color pigment paste CP2 contained phthalocyanine blue pigment. In each case, CP2 contained 27.47% by mass of pigment and 17% by mass of polyacrylic resin based on its total mass.

[0117] 1.3 The primer coating compositions P1I2 and P1I3 of the present invention were prepared in the same manner as described above for P1I1.

[0118] For P1I2, the components listed in Table 2b were used.

[0119] [Table 4]

[0120] BP3 contained an inorganic non-carbon black pigment, namely Tipaque® black SG103 (calcium manganese titanium oxide black pigment) from Ishihara Sangyo Co., Ltd., Japan. BP3 contained 30% by mass of Tipaque® black SG103.

[0121] For P1I3, the components listed in Table 2c were used.

[0122] [Table 5]

[0123] WP2 contained Tipaque® PFR404 (rutile-type TiO2), a white reflective pigment from Ishihara Sangyo Co., Ltd. of Japan, instead of Kronos® 2310. Tipaque® PFR404 had a larger average particle size than Kronos® 2310. WP2 contained 30% by mass of Tipaque® PFR404.

[0124] 2. Characterization of the primer Table 3 compares the standard primer (Comparative Example P1C1) with the primers P1I1, P1I2, and P1I3 of the present invention. All primers had the same lightness value (L* = approximately 25 at 45°). The properties shown in the table were measured as described in the "Methods" section of this specification.

[0125] [Table 6]

[0126] Table 3 clearly shows that P1C1 exhibits significantly higher Lidar reflectance and significantly better infrared solar reflectance (IRSR) compared to P1I1, P1I2, and P1I3, respectively. The best performance was observed with P1I1.

[0127] Table 4 compares the color values ​​of primers P1I1 and P1C1.

[0128] [Table 7]

[0129] The weighted average of color differences (mDE*) for P1C1 and P1I1 color values ​​was very small (mDE* was only 0.72).

[0130] 3. Characterization of multilayer coating systems Table 5 illustrates and compares the properties of multilayer coating systems obtained using either P1C1 or P1I1. A primer layer made from P1C1 or P1I1 was formed on a pre-treated steel panel coated with a cathode electrodeposition coating layer using Cathoguard 800 and cured at approximately 140°C for 25 minutes (dry film thickness approximately 20-23 μm). Next, a base coat film formed from a commercially available base coat composition containing NIR-transparent black pigment (Paliogen® L0086) (p / b ratio 0.1) was applied onto the cured primer film and flash-off at approximately 71°C for 7 minutes. Then, a clear coat composition was applied on top of the flash-off base coat film. Subsequently, the two films were cured together at approximately 140°C for 25 minutes (dry base coat film thickness approximately 20-23 μm, dry clear coat film thickness approximately 50 μm). A commercially available clear coat product (ProGloss / 2K4) was used. All compositions were applied by pneumatic spray. The clear coat layer was transparent and was also transparent to IR radiation. Next, the obtained multilayer coating system (MLCS) was investigated. The properties shown in Table 5 were measured as described in the "Methods" section of this specification.

[0131] [Table 8]

[0132] The weighted average of the color difference (mDE*) in the color values ​​of MLCS using P1C1 and MLCS using P1I1 was very small (mDE* was only 0.48). This was found to be achieved, in particular, by adding IR transparent red and blue pigments to the primers to achieve the desired color space.

[0133] Table 5 further demonstrates that a significantly higher Lidar reflectivity was achieved when comparing P1C1 and P1I1.

Claims

1. A primer coating composition that does not contain or is essentially free of metallic effect pigments, and contains the following components: As at least one component P-A, at least one film-forming polymer P-A1, and if P-A1 is externally crosslinkable, at least one crosslinking agent-PA2, The constituent component P-B is water and / or one or more organic solvents. A pigment mixture comprising, as at least one component P-C, at least two different pigments, namely, at least one organic black or inorganic black pigment P-C1 which is not a carbon black pigment and transmits at least 80% of NIR radiation in the 800 nm to 2500 nm wavelength range, or reflects 25 to <100% of NIR radiation in the 900 nm to 1600 nm wavelength range, and at least one inorganic white pigment P-C2 which reflects 25 to <100% of NIR radiation in the 900 nm to 1600 nm wavelength range. Includes, Pigment P-C1 is present in an amount ranging from 0.1 to 20.0% by mass relative to the total mass of the primer coating composition, and pigment P-C2 is present in an amount ranging from 0.2 to 40.0% by mass relative to the total mass of the primer coating composition, and The primer coating obtained by applying the primer coating composition to the substrate has a lightness value L* of 38 or less according to the CIELAB system at 45°. The relative mass ratio of pigments P-C2 to P-C1 is in the range of 15:1 to 1.1:

1. The primer coating obtained by applying the primer coating composition to the substrate has a LiDAR reflectance of at least 40% when measured at an incident angle of 0°. The at least one pigment P-C1 is selected from the group consisting of iron / chromium oxide compounds, manganese ferrite black oxide, calcium manganese titanium oxide, perylene pigment, azomethine pigment, and mixtures thereof. The at least one pigment P-C2 is selected from the group consisting of titanium dioxide-based pigments or titanium dioxide-containing pigments. Characterized by, Primer coating composition.

2. The primer coating composition according to claim 1, characterized in that the relative mass ratio of pigment P-C2 to P-C1 is in the range of 12:1 to 1.5:

1.

3. The primer coating composition according to claim 1 or 2, further comprising at least one organic or inorganic coloring pigment P-C3, wherein the coloring pigment is different from both pigments P-C1 and P-C2 and is not a carbon black pigment.

4. At least one black pigment P-C1 is a black pigment having a master tone color with L* < 17, a* > -4 and < 9, and b* > -4 and < 9 at 45° according to the CIELAB system, and The invention is characterized in that at least one white pigment P-C2 is a white pigment having a master tone color with L* > 85, a* > -2 and < 2, and b* > 0 and < 6 at 45° according to the CIELAB system. The primer coating composition according to claim 1 or 2.

5. A primer coating composition according to claim 1 or 2, which does not contain any carbon black pigment, or which is essentially free of any carbon black pigment.

6. A primer coating composition according to claim 1 or 2, wherein a primer coating obtained by applying the primer coating composition to a substrate is Measured at an incident angle of 0°, the LiDAR reflectance is at least 45%, and / or UV Vis transmittance of less than 0.005, and / or Infrared solar reflectance (IRSR) of over 30% A primer coating composition characterized by having the following:

7. A method for forming a primer coating film at least partially on at least one surface of a substrate, wherein the method comprises at least step (a), i.e. (a) A step of applying the primer coating composition according to claim 1 to at least partially on at least one surface of an optionally pre-coated substrate to form a primer coating film on the surface of the substrate. Methods that include...

8. A method for forming a primer coating layer at least partially on at least one surface of a substrate, comprising at least step (a) and at least step (b) as defined in claim 7, i.e. (b) A step of curing the primer coating film obtained after step (a) to obtain a primer coating layer. Methods that include...

9. A coating film that can be obtained from the primer coating composition described in claim 1 or 2, or by the method described in claim 7.

10. A coating layer that can be obtained from the primer coating composition described in claim 1 or 2, or by the method described in claim 8.

11. A substrate that can be obtained by the method of claim 8, wherein the substrate itself before the coating method described in claim 8 is not LiDAR reflective, or is not essentially LiDAR reflective.

12. A coating layer L1, L2, and L3, which are at least three different coating layers, are present on an arbitrarily pre-coated substrate, i.e. A first coating layer L1 applied to at least a portion of an optionally pre-coated substrate, A second coating layer L2 applied on the first coating layer L1, and A third top coating layer L3 applied on top of the second coating layer L2. A multilayer coating system including, A multilayer coating system in which the first coating layer L1 is formed from the primer coating composition described in claim 1 or 2, the second coating layer L2 is formed from a base coat composition different from the primer coating composition, and the third coating layer L3 is formed from a clear coat composition different from both the primer coating composition and the base coat composition.

13. A multilayer coating system according to claim 12, wherein the base coat composition comprises at least one pigment that is not a carbon black pigment and is not a pigment that absorbs NIR radiation.

14. A method for producing the multilayer coating system described in claim 12, comprising at least steps (1), (2), (3), and (4), i.e. (1) A step of applying the primer coating composition according to claim 1 to at least a portion of an optionally pre-coated substrate to form a first coating film on at least a portion of the optionally pre-coated substrate. (2) A step of applying a base coat composition different from the primer coating composition applied in step (1) to the first coating film present on the substrate obtained after step (1) to form a second coating film adjacent to the first coating film. (3) A step of applying a coating composition different from the compositions applied in steps (1) and (2) to the second coating film present on the substrate obtained after step (2), thereby forming a third coating film adjacent to the second coating film, wherein the coating composition is a clear coat composition, and (4) A step of curing together at least the second and third coating films applied in steps (2) and (3), and optionally, if the first coating film was not cured before step (2), the first coating film applied in step (1), to obtain a multilayer coating system including at least the first, second, and third coating layers L1, L2, and L3. Methods that include...

15. A method for using the coating film according to claim 9 and / or the at least partially coated substrate according to claim 11 in a LiDAR visibility application relating to a vehicle and its parts.

16. A method for using the multilayer coating system described in claim 12 in LiDAR visibility applications relating to vehicles and their components.

17. A primer coating composition according to claim 1 or 2, wherein the primer coating obtained by applying the primer coating composition to a substrate has a LiDAR reflectance of at least 50%, or at least 55%, or at least 60%, or at least 65%, or at least 70%, as measured at an incident angle of 0°, and / or UV Vis transmittance of less than 0.003, and / or Infrared solar reflectance (IRSR) exceeding 35% or exceeding 40% A primer coating composition characterized by having the following:

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