Coating composition

Abstract

The purpose of the present disclosure is to suppress, in an obtained coating film, whitening of the coating film caused by ambient light, particularly light received from a direction opposite that of a laser light emission unit and a reflected light detection unit, while maintaining retroreflection properties.　A coating composition according to the present disclosure is for use in an object being detected in sensing performed using near-infrared light, the coating composition containing a coating-film-forming resin (A), a coloring pigment (B), and an extender pigment (D). The coloring pigment (B) includes at least one pigment selected from the group consisting of white-based pigments having a near-infrared reflectance of 60% or greater, chromatic pigments having a near-infrared reflectance of 50% or greater, and black-based pigments having a near-infrared reflectance of 30% or greater, where the near-infrared reflectance is the reflectance in a wavelength region of 800-2500 nm. The extender pigment (D) includes one or more pigments selected from carbonates (D1) and metasilicates (D2).

Description

paint composition

[0001] The present disclosure relates to coating compositions.

[0002] Development of automated guided vehicle (AGV) systems is underway with the aim of automating transportation and reducing labor. AGVs are defined in JIS D 6801 as "vehicles that travel automatically within a certain area and have the function of transporting items other than people, such as cargo, and that are not to be used on roads defined by the Road Traffic Act." AGVs are classified into three types: route-guided types, in which the vehicle's position is controlled by some kind of guidance means; autonomous types, in which the vehicle itself has self-position estimation and navigation control functions; and following types, in which the vehicle moves by following a person or vehicle ahead.

[0003] Patent Document 1 describes a cooperative guidance system that includes a processor that applies paint containing a crystalline rare earth phosphor that can convert light into electromagnetic energy to a public road surface, irradiates the painted surface with light, detects the generated electromagnetic energy, and converts it into a processed signal to determine the vehicle's operating characteristics or the characteristics of the public road surface.

[0004] Furthermore, Patent Document 2 describes a pigment that reflects more than 60% of electromagnetic radiation having a wavelength of 850 nm or more and 950 nm or less.

[0005] Patent Document 3 describes an electromagnetic wave absorbing ink composition comprising electromagnetic wave absorbing fine particles, a dispersant, a resin, and a solvent.

[0006] JP-T-2019-513198 A JP-A-2019-131791 JP-A-2002-188031

[0007] In the route guidance system, the vehicle position is typically controlled using magnetism, electromagnetic induction, light reflection, or the like. Among these, a guidance system using light reflection has attracted attention because it allows for easy route setting and modification. In a guidance system using light reflection, accurate position recognition is required, requiring accurate recognition of reflected light from a specific illuminated object such as a marker. Therefore, it is desirable for such a specific illuminated object to exhibit retroreflectivity (the property of reflecting light in the same direction as the incident direction).

[0008] Furthermore, the autonomous mobile system uses LiDAR (Laser Imaging Detection and Ranging) technology to estimate its own position. LiDAR is a remote sensing technology that uses light, and detects the distance and direction from the irradiation position to an object such as a road surface by irradiating near-infrared light, visible light, and / or ultraviolet light onto the object and measuring the light reflected and / or scattered by the object.

[0009] LiDAR is widely used not only in AGVs, but also in autonomous driving technology for automobiles, electronic devices, and various industries. Even when applying LiDAR technology to AGVs and autonomous driving technology, retroreflective properties are required for road surfaces and other objects to ensure visibility. In particular, AGVs and autonomous driving require irradiating a road surface at a long distance from the vehicle with laser light and detecting the reflected light, so the technology must be able to handle high angles of incidence. At low angles of incidence, retroreflective properties can be achieved relatively easily because the difference between the angle of incidence and the angle of reflection is small. However, at high angles of incidence, retroreflective properties become more difficult to achieve because the light must be reflected in a direction significantly different from normal total reflection. The angle of incidence refers to the angle from the normal to the reflective surface.

[0010] On the other hand, in the case of road surfaces or the like to be detected, in addition to the LiDAR visibility of the object, it is necessary for the object to be the same dark color (also called low brightness) as the road surface to prevent misidentification with existing white lines, etc. In other words, the object is required to have low brightness for light in the visible light range, be able to reflect and / or scatter light in the near-infrared range with high intensity, and have retroreflective properties.

[0011] Examples of such means include a method of applying a paint composition containing glass beads, a method of applying a paint composition that has been toned using a color pigment with high near-infrared reflectivity, etc. However, in some embodiments, it has been found that when strong light such as sunlight or automobile headlights is irradiated from the opposite direction of the laser light irradiating section and the reflected light detecting section, there is a risk that it may be mistaken for a white line (hereinafter also referred to as "whitening of the paint film").

[0012] The present disclosure has been made in consideration of such circumstances, and aims to suppress whitening of the coating film caused by ambient light, particularly light irradiated from the opposite direction of the laser light irradiation section and the reflected light detection section, while maintaining retroreflectivity in the resulting coating film.

[0013] [1] A coating composition for a detection target in sensing using near-infrared light, comprising a coating film-forming resin (A), a color pigment (B), and an extender pigment (D), wherein the color pigment (B) comprises at least one pigment selected from the group consisting of a white pigment having a near-infrared reflectance of 60% or more, a chromatic pigment having a near-infrared reflectance of 50% or more, and a black pigment having a near-infrared reflectance of 30% or more, where the reflectance in the wavelength range of 800 to 2,500 nm is defined as the near-infrared reflectance, and the extender pigment (D) comprises one or more pigments selected from carbonates (D1) and metasilicates (D2). [2] The coating composition for a detection target in sensing using near-infrared light according to [1], wherein the surface of the coating film formed has a root-mean-square gradient (Sdq) of 1 or more, as measured in accordance with ISO 25178, and a developed area ratio (Sdr) of 40% or more, as measured in accordance with ISO 25178. [3] The coating composition for a detection target in sensing using near-infrared light according to [1] or [2], wherein the chromatic color pigment comprises at least one pigment selected from the group consisting of reddish pigments, yellowish pigments, and blueish pigments. [4] The coating composition for a detection target in sensing using near-infrared light according to any one of [1] to [3], wherein the reddish pigment and the yellowish pigment each comprise an organic pigment and / or an inorganic pigment. [5] The coating composition for a detection target in sensing using near-infrared light according to any one of [1] to [4], wherein the color pigment (B) comprises at least one selected from the group consisting of a white pigment having a spectral reflectance of 70% or more at wavelengths of 905 nm and / or 1,550 nm, an organic red pigment having a spectral reflectance of 50% or more at said wavelengths, an inorganic red pigment having a spectral reflectance of 20% or more at said wavelengths, an organic yellow pigment having a spectral reflectance of 60% or more at said wavelengths, an inorganic yellow pigment having a spectral reflectance of 20% or more at said wavelengths, a blue pigment having a spectral reflectance of 40% or more at said wavelengths, an organic black pigment having a spectral reflectance of 30% or more at said wavelengths, and an inorganic black pigment having a spectral reflectance of 15% or more at said wavelengths. [6] The coating composition for a detection target in sensing using near-infrared light according to any one of [1] to [5], wherein the lightness of the coating film formed is 80 or less.[7] A coating composition for a detection target for sensing using near-infrared light according to any one of [1] to [6], wherein the average particle diameter D50 of the extender pigment (D) is 5 μm or more and 40 μm or less. [8] A coating composition for a detection target for sensing using near-infrared light according to any one of [1] to [7], wherein the pigment volume concentration of the extender pigment (D) is 25 vol% or more and 60 vol% or less. [9] A coating film for a detection target for sensing using near-infrared light, the surface of which has a root-mean-square gradient (Sdq) measured in accordance with ISO 25178 of 1 or more and a developed area ratio (Sdr) measured in accordance with ISO 25178 of 40% or more.

[10] A coating film for a detection target for sensing using near-infrared light, formed from the coating composition according to any one of [1] to [8].

[11] A coating film for a detection target for sensing using near-infrared light according to

[10] , wherein the surface has a root-mean-square gradient (Sdq) of 1 or more as measured in accordance with ISO 25178 and a developed area ratio (Sdr) of 40% or more as measured in accordance with ISO 25178.

[12] A detection target having a coating film formed using the coating composition for a detection target for sensing according to any one of [1] to [9].

[13] A sensing method for measuring the distance between a vehicle and a detection target, comprising irradiating a traveling vehicle with near-infrared light of a specific wavelength, causing the light to be reflected by the detection target, detecting the reflected light, and calculating the distance from the vehicle to the detection target based on the time required for reflection, wherein the detection target is obtained by coating the detection target with the coating composition according to any one of [1] to [9].

[14] A sensing method for measuring the distance between a vehicle and a detection object, in which near-infrared light of a specific wavelength is irradiated from a traveling vehicle, which is reflected by the detection object, the reflected light is detected, and the distance from the vehicle to the detection object is calculated from the frequency difference between the irradiated light and the reflected light, wherein the detection object is obtained by painting it with the coating composition according to any one of [1] to [9].

[15] A method for producing a coating film, comprising: applying a first coating composition onto a road surface to obtain a coating film; and drying the coating film to obtain a coating film for use as a detection target in sensing using near-infrared light, wherein the first coating composition comprises a coating film-forming resin (A), a coloring pigment (B), and an extender pigment (D), and the coloring pigment (B) comprises at least one pigment selected from the group consisting of white pigments having a near-infrared reflectance of 60% or more, chromatic pigments having a near-infrared reflectance of 50% or more, and black pigments having a near-infrared reflectance of 30% or more, where the reflectance in a wavelength range of 800 to 2,500 nm is defined as the near-infrared reflectance, and the extender pigment (D) comprises one or more pigments selected from carbonates (D1) and metasilicates (D2).

[16] The method for producing a coating film according to

[15] , wherein the coating film for a detection target in sensing using near-infrared light has a surface having a root-mean-square gradient (Sdq) of 1 or more as measured in accordance with ISO 25178 and a developed area ratio (Sdr) of 40% or more as measured in accordance with ISO 25178.

[0014] The coating film of the present disclosure can suppress whitening of the coating film caused by ambient light, particularly light irradiated from the opposite direction of the laser light irradiating section and the reflected light detecting section, while maintaining retroreflectivity.

[0015] The coating composition for detection targets in sensing using near-infrared light according to the present disclosure comprises a coating film-forming resin (A), a color pigment (B), and an extender pigment (D), wherein the color pigment (B) comprises at least one pigment selected from the group consisting of white pigments having a near-infrared reflectance of 60% or more, chromatic pigments having a near-infrared reflectance of 50% or more, and black pigments having a near-infrared reflectance of 30% or more, where the reflectance in a wavelength range of 800 to 2,500 nm is taken as the near-infrared reflectance, and the extender pigment (D) comprises one or more pigments selected from carbonates (D1) and metasilicates (D2).

[0016] The coating composition of the present disclosure can suppress whitening of the coating film caused by ambient light, particularly light irradiated from the opposite direction of the laser light irradiator and the reflected light detector, while maintaining retroreflectivity (LiDAR visibility). While the present disclosure should not be interpreted as being limited to a particular theory, the reason why the coating composition of the present disclosure exhibits such an effect is believed to be as follows. Specifically, the coating composition of the present disclosure contains a color pigment that exhibits a reflectance of at least a certain level in the wavelength range of 800 to 2,500 nm, and further contains an extender pigment selected from carbonates (D1) and metasilicates (D2). Therefore, while infrared reflectivity and retroreflectivity (LiDAR visibility) are maintained, the resulting coating film may have steep surface irregularities. It is believed that ambient light incident on the coating film is repeatedly reflected and absorbed within the irregularities, thereby attenuating the reflected light that escapes to the outside. As a result, it is believed that whitening of the coating film due to ambient light, particularly light irradiated from the opposite direction of the laser light irradiator and the reflected light detector, can be suppressed while maintaining retroreflectivity (LiDAR visibility). Note that in this disclosure, "ambient light" refers to light that can be incident on an object, such as sunlight, that does not participate in LiDAR sensing.

[0017] (A) Film-forming resin: The film-forming resin (A) is a resin capable of forming a coating film, and resins commonly used in the coatings field can be used. Examples of the film-forming resin (A) include thermosetting resins, room temperature curing resins, and photocuring resins such as acrylic resins, polyester resins, polyurethane resins, alkyd resins, polyether resins, fluororesins, epoxy resins, silicone resins, and urea resins, and it is preferable to include one or more selected from acrylic resins, polyester resins, polyurethane resins, and urea resins. The film-forming resin (A) may form a coating film by itself, or may form a coating film by the action of a crosslinking agent (C) described below. The film-forming resin (A) may be used alone, or two or more types may be used in combination.

[0018] The acrylic resin represents a polymer having units derived from a monomer having a (meth)acryloyl group, and can be prepared by polymerizing a monomer mixture containing the monomer having a (meth)acryloyl group. The monomer mixture may further contain a monomer having an ethylenically unsaturated bond other than the monomer having a (meth)acryloyl group. In the present disclosure, (meth)acrylic acid represents acrylic acid and methacrylic acid.

[0019] Examples of the monomer having a (meth)acryloyl group include (meth)acrylic acid; (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 1 to 20 carbon atoms; (meth)acrylic monomers having a hydroxy group such as hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and N-methylol (meth)acrylamide; lactone adducts of the above-mentioned (meth)acrylic monomers having a hydroxy group; and (meth)acrylonitrile.

[0020] Examples of the monomer having an ethylenically unsaturated group include, in addition to the monomer having a (meth)acryloyl group, monomers having a carboxy group such as crotonic acid, itaconic acid, and fumaric acid; anhydrides of the monomers having a carboxy group; and vinyl monomers such as styrene.

[0021] The polyester resin refers to a polymer having a plurality of ester bonds in the main chain, and can be obtained as a reaction product of a polyol and a polycarboxylic acid; an addition polymerization product of a cyclic ester; a reaction product of the reaction product of the polyol and polycarboxylic acid with a cyclic ester; etc.

[0022] The polyol is a compound having two or more hydroxy groups in one molecule, and examples thereof include aliphatic polyols such as ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,4-pentanediol, neopentyl glycol, and 1,5-hexanediol; alicyclic polyols such as hydrogenated bisphenol A and 1,4-cyclohexanedimethanol; aromatic polyols such as bisphenol A and hydroxyalkylated bisphenol A; tri- or higher functional polyols such as glycerin, mannitol, trimethylolethane, trimethylolpropane, trimethylolbutane, hexanetriol, pentaerythritol, and dipentaerythritol; sugar alcohols such as sorbitol; tris(hydroxyethyl)isocyanate; and N,N-bis(2-hydroxyethyl)dimethylhydantoin.

[0023] The number of hydroxy groups contained in the polyol is preferably 2 or more, or may be 3 or more, and is preferably 6 or less, more preferably 4 or less, per molecule.

[0024] The polyols may be used alone or in combination of two or more.

[0025] The polycarboxylic acid refers to a compound having two or more carboxy groups in one molecule. Examples of the polycarboxylic acid include aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid; alicyclic polycarboxylic acids such as tetrahydrophthalic acid, hexahydrophthalic acid, methyltetrahydrophthalic acid, cyclohexane-1,4-dicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid, and methyl-5-norbornene-2,3-dicarboxylic acid; aliphatic polycarboxylic acids such as maleic acid, fumaric acid, itaconic acid, adipic acid, azelaic acid, sebacic acid, succinic acid, and dodecenylsuccinic acid; hydroxy acids of lactose; anhydrides of the aromatic polycarboxylic acids, alicyclic polycarboxylic acids, and aliphatic polycarboxylic acids; and the like. The polycarboxylic acids may be used alone or in combination of two or more.

[0026] Examples of the cyclic ester include ε-caprolactone.

[0027] The polyester resin also includes modified products of the polyester resins described above. The resin can be modified by reacting a modifying agent with the end of the main chain constituting the resin. Examples of the modifying agent include compounds having a reactive group such as an isocyanate group, a hydroxy group, or a carboxy group, or a silicone skeleton. Examples of the modified polyester resin include urethane-modified polyester resins, epoxy-modified polyester resins, acrylic-modified polyester resins, and silicone-modified polyester resins.

[0028] Examples of the urethane resin include a reaction product of a polyol and a polyisocyanate; a reaction product of the reaction product with a chain extender that is used as needed; and the like.

[0029] The polyol means a compound having two or more hydroxy groups in one molecule. Examples of the polyol include aliphatic polyols such as ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,4-pentanediol, neopentyl glycol, 1,5-hexanediol, and 1,6-hexanediol; alicyclic polyols such as hydrogenated bisphenol A and 1,4-cyclohexanedimethanol; aromatic polyols such as bisphenol A and hydroxyalkylated bisphenol A (particularly, bisphenol hydroxypropyl ether); tri- or higher functional polyols such as glycerin, mannitol, trimethylolethane, trimethylolpropane, trimethylolbutane, hexanetriol, pentaerythritol, and dipentaerythritol; and high molecular weight polyols (for example, polyols having a weight average molecular weight of 800 or more) such as polyether polyols, acrylic polyols, polyurethane polyols, polyester polyols, and polyesteramide polyols.

[0030] The polyols may be used alone or in combination of two or more.

[0031] The number of hydroxy groups contained in the polyol is 2 or more, and may be 3 or more, but is preferably 6 or less, and more preferably 4 or less.

[0032] The polyisocyanate refers to a compound having two or more isocyanate groups in one molecule. Examples of the polyisocyanate include aliphatic polyisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, and hexamethylene diisocyanate; alicyclic polyisocyanates such as 1,3-cyclopentane diisocyanate, 1,4-dicyclohexylmethane diisocyanate, 1,2-cyclohexane diisocyanate, isophorone diisocyanate, norbornane diisocyanate methyl, and hydrogenated xylylene diisocyanate; Examples of the polyisocyanate include aromatic polyisocyanates such as 4-tolylene diisocyanate, 1,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, metaxylylene diisocyanate, naphthylene diisocyanate, and 3,3'-dimethyl-4,4'-biphenylene diisocyanate; and polymers such as biuret, isocyanurate, urethidine, and allophanate derivatives of the aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. One type of polyisocyanate may be used, or two or more types may be used in combination.

[0033] The chain extender refers to a compound having one or more active hydrogen atoms in one molecule, and may be water or an amine compound. Examples of the amine compound include aliphatic polyamines such as ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, dipropylenetriamine, triethylenetetramine, and tetraethylenepentamine; aromatic polyamines such as tolylenediamine, xylylenediamine, and diaminodiphenylmethane; alicyclic polyamines such as diaminocyclohexylmethane, piperazine, 2,5-dimethylpiperazine, and isophoronediamine; hydrazine compounds such as hydrazine, succinic acid dihydrazide, adipic acid dihydrazide, and phthalic acid dihydrazide; and alkanolamines such as hydroxyethyldiethylenetriamine, 2-[(2-aminoethyl)amino]ethanol, and 3-aminopropanediol.

[0034] In one embodiment, the urethane resin may be an ester-based urethane resin, an ether-based urethane resin, or a carbonate-based urethane resin.

[0035] Examples of the epoxy resin include epoxy resins having two or more epoxy groups in one molecule, such as glycidyl ester resins, glycidyl ether resins such as condensation products of bisphenol A and epichlorohydrin, and condensation products of bisphenol F and epichlorohydrin, as well as alicyclic epoxy resins, linear aliphatic epoxy resins, bromine-containing epoxy resins, phenol novolac epoxy resins, and cresol novolac epoxy resins.

[0036] The urea resin may be a reaction product of a polyamine compound and a polyisocyanate compound, etc. The polyamine compound and the polyisocyanate compound may be separately blended to form a two-component coating composition.

[0037] The polyamine compound is a compound having two or more amino groups, and includes at least one selected from an aliphatic polyamine compound, an alicyclic polyamine compound, and an aromatic polyamine compound, and preferably includes at least one selected from an aliphatic polyamine compound and an alicyclic polyamine compound.

[0038] The amino group is preferably a primary or secondary amino group. In one embodiment, the amino group may be present in the molecular chain of the polyamine compound or at the molecular terminal. The polyamine compound may be, for example, a polyamine compound represented by the formula: R １２ HN-R １１ -NHR １２ (In the formula, R １１ is a divalent C １－３０ represents a hydrocarbon group, and R １１ -CH contained in ２ - represents -O-, -CO- or -NR １２ - may be substituted, and R １２ is a monovalent C １－３０ represents a hydrocarbon group or a hydrogen atom. １－３０ The hydrocarbon group includes C １－３０Aliphatic hydrocarbon group, C ３－３０ Alicyclic hydrocarbon group and C ６－３０ Examples include aromatic hydrocarbon groups.

[0039] The aliphatic polyamine compound refers to a polyamine compound that does not have a ring structure in its molecular structure, and examples of such aliphatic polyamine compounds include alkylene polyamine compounds, polyalkylene polyamine compounds, and other aliphatic polyamine compounds.

[0040] Examples of the alkylene polyamine compound include methylene diamine, ethylene diamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, and 1,10-diaminodecane.

[0041] Examples of the polyalkylene polyamine compound include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexamethylenetetramine.

[0042] Other aliphatic polyamine compounds include, for example, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, triethylene-bis(trimethylene)hexamine, bis(3-aminoethyl)amine, bishexamethylenetriamine, and aspartic acid ester amines represented by the following formula (11):

[0043] The alicyclic polyamine compound means a polyamine compound having an alicyclic structure in its molecular structure.

[0044] Examples of the alicyclic polyamine compound include 1,4-cyclohexanediamine, 4,4'-methylenebiscyclohexylamine, 4,4'-isopropylidenebiscyclohexylamine, 2,5(2,6)-bis(aminomethyl)bicyclo[2.2.1]heptane (e.g., norbornadiamine), bis(aminomethyl)cyclohexane, diaminodicyclohexylmethane (e.g., 4,4'-diaminodicyclohexylmethane), isophoronediamine, menthenediamine (MDA), 1,4-bis-(8-aminopropyl)-piperazine, piperazine-1,4-diazacycloheptane, 1-(2'-aminoethylpiperazine), 1-[2'-(2''-aminoethylamino)ethyl]piperazine, 1,11-diazacycloeicosane, and 1,15-diazacyclooctacosane.

[0045] The aromatic polyamine compound means a polyamine compound having an aromatic ring in the molecular structure. Examples of aromatic polyamine compounds include bis(cyanoethyl)diethylenetriamine, o-xylylenediamine, m-xylylenediamine (MXDA), p-xylylenediamine, phenylenediamine, naphthylenediamine, diaminodiphenylmethane, diaminodiethylphenylmethane, 2,2-bis(4-aminophenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl sulfone, 2,2'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 2,4'-diaminobiphenyl, 2,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, bis(aminomethyl)naphthalene, bis(aminoethyl)naphthalene, and polytetramethylene oxide-di-p-aminobenzoate.

[0046] In one embodiment, the polyamine compound may include an aspartic acid ester amine represented by the following formula (I):

[0047] [In formula (I), R １ is a divalent C １－８０represents one selected from hydrocarbon groups, and R ２ are, independently of each other, C １－２０ represents a hydrocarbon group.]

[0048] The polyamine compound may be used alone or in combination of two or more kinds.

[0049] The polyisocyanate refers to a compound having two or more isocyanate groups in one molecule. Examples of the polyisocyanate include aliphatic polyisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, and hexamethylene diisocyanate; alicyclic polyisocyanates such as 1,3-cyclopentane diisocyanate, 1,4-dicyclohexylmethane diisocyanate, 1,2-cyclohexane diisocyanate, isophorone diisocyanate, norbornane diisocyanate methyl, and hydrogenated xylylene diisocyanate; Examples of the polyisocyanate include aromatic polyisocyanates such as 4-tolylene diisocyanate, 1,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, metaxylylene diisocyanate, naphthylene diisocyanate, and 3,3'-dimethyl-4,4'-biphenylene diisocyanate; and polymers such as biuret, isocyanurate, urethidine, and allophanate derivatives of the aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. One type of polyisocyanate may be used, or two or more types may be used in combination.

[0050] The equivalent ratio of the isocyanate group of the polyisocyanate compound to the amino group of the polyamine compound (for example, in the case of a secondary amine, NCO / NH ２ ) is preferably 0.5 to 2.0, more preferably 0.8 to 1.2. The amino group used in calculating the above equivalent ratio refers to the amino group that participates in the reaction with the polyisocyanate (for example, the amino group present at the molecular terminal). Having the equivalent ratio within the above range has the advantage of improving the water resistance, etc. of the coating film that is formed.

[0051] The film-forming resin (A) may have a hydrophilic group such as an anionic group, a cationic group, or a nonionic group. Examples of the anionic group include a carboxy group and a sulfonic acid group, and examples of the cationic group include an amino group and a quaternary ammonium group. Examples of the nonionic group include a polyoxyalkylene unit. The hydrophilic group can be introduced by using a compound having a hydrophilic group as a raw material for the film-forming resin (A), for example.

[0052] When the film-forming resin (A) has an anionic group, the coating composition may contain a basic compound capable of neutralizing the anionic group, and when the film-forming resin (A) has a cationic group, the coating composition may contain an acidic compound capable of neutralizing the cationic group.

[0053] When the film-forming resin (A) has an anionic group, the acid value of the film-forming resin (A) is preferably 5 mgKOH / g or more and 50 mgKOH / g or less, more preferably 5 mgKOH / g or more and 30 mgKOH / g or less.

[0054] When the film-forming resin (A) has a cationic group, the amine value of the film-forming resin (A) is preferably from 5 mgKOH / g to 50 mgKOH / g, more preferably from 5 mgKOH / g to 30 mgKOH / g.

[0055] The film-forming resin (A) may contain hydroxy groups. When the film-forming resin (A) contains hydroxy groups, the hydroxyl value of the film-forming resin (A) is preferably from 5 mg KOH / g to 35 mg KOH / g, more preferably from 7 mg KOH / g to 30 mg KOH / g, and even more preferably from 10 mg KOH / g to 25 mg KOH / g.

[0056] The acid value and hydroxyl value are both based on solid content and can be measured in accordance with JIS K 0070: 1999. The amine value is based on solid content and can be measured in accordance with JIS K 7237.

[0057] The coating film-forming resin (A) may be a resin that can be dissolved in an organic solvent, as described below, or may be an aqueous resin. Examples of the aqueous resin include water-soluble resins that can be dissolved in an aqueous medium, and water-dispersible resins that can be dispersed in an aqueous medium, such as colloidal dispersion type and emulsion type (emulsion polymerization type, forced emulsification type).

[0058] The weight average molecular weight of the film-forming resin (A) may be, for example, from 2,000 to 10,000,000, from 10,000 to 2,000,000, or from 50,000 to 2,000,000.

[0059] The weight average molecular weight of the coating film-forming resin (A), in the case of the emulsion-type water-dispersible resin, may be, for example, 50,000 or more and 10,000,000 or less, 100,000 or more and 2,000,000 or less, or 150,000 or more and 500,000 or less.

[0060] In the case of the resin that can be dissolved in an aqueous medium or an organic solvent, the molecular weight may be, for example, 2,000 or more and 100,000 or less, 10,000 or more and 80,000 or less, or 50,000 or more and 80,000 or less.

[0061] In the present disclosure, the weight average molecular weight is a value measured by gel permeation chromatography and converted into polystyrene equivalent.

[0062] The glass transition temperature of the film-forming resin (A) is preferably −30° C. or higher and 120° C. or lower, more preferably −25° C. or higher and 80° C. When the glass transition temperature of the film-forming resin (A) is within this range, the hardness of the coating film is improved, and blocking resistance can be improved even when the coating film is cured in an autoclave.

[0063] In the present disclosure, the glass transition temperature is a value measured by a differential scanning calorimeter, and can be measured, for example, by a differential scanning calorimeter DSC-6100 (manufactured by Seiko Instruments Inc.).

[0064] In a preferred embodiment, the film-forming resin (A) may contain an acrylic resin water dispersion (A1). The glass transition temperature (Tg) of the acrylic resin water dispersion (A1) may be preferably −30 to 50°C, more preferably −25 to 50°C.

[0065] In one embodiment, the hydroxyl value of the acrylic resin in the acrylic resin aqueous dispersion (A1) is preferably 0 mgKOH / g, and in another embodiment, it is preferably 0 mgKOH / g or more and 200 mgKOH / g or less, more preferably 5 mgKOH / g or more and 100 mgKOH / g or less, and even more preferably 10 mgKOH / g or more and 70 mgKOH / g or less. Having a hydroxyl value of the acrylic resin in the above range has advantages such as good water resistance and freeze-thaw resistance of the resulting coating composition.

[0066] The acid value of the acrylic resin in the acrylic resin aqueous dispersion (A1) is preferably 10 mgKOH / g or more and 150 mgKOH / g or less, more preferably 10 mgKOH / g or more and 120 mgKOH / g or less. The acid value of the acrylic resin in this range has advantages such as improving the water resistance and freeze-thaw resistance of the resulting coating composition. In the present disclosure, the acid value and hydroxyl value both indicate values ​​calculated as solids content and are values ​​measured by a method in accordance with JIS K 0070.

[0067] The content of the film-forming resin (A) is preferably 5% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 40% by mass or less, based on 100% by mass of the solid content of the coating composition.

[0068] In the present disclosure, the solid content of the coating composition means the portion of all components of the coating composition excluding the solvent (D) described below.

[0069] The coating composition may also contain a thermoplastic resin in addition to the film-forming resin (A), as long as it does not affect the physical properties of the coating film formed. Examples of the thermoplastic resin include chlorinated olefin resins such as chlorinated polyethylene and chlorinated polypropylene; homopolymers or copolymers containing vinyl chloride, vinyl acetate, vinylidene chloride, or the like as monomer components; cellulose resins; acetal resins; alkyd resins; chlorinated rubber resins; modified polypropylene resins (such as acid anhydride-modified polypropylene resins); fluororesins (such as vinylidene fluoride resins, vinyl fluoride resins, copolymers of fluorinated olefins and vinyl ethers, and copolymers of fluorinated olefins and vinyl esters). One type of thermoplastic resin may be used, or two or more types may be used in combination. By using a thermoplastic resin in combination, it becomes easier to adjust the physical properties of the coating film formed according to the purpose.

[0070] (B) Coloring Pigment The coloring pigment (B) is a pigment having a color such as a chromatic color or an achromatic color, and includes a pigment (B1) capable of reflecting near-infrared rays. The near-infrared reflectance of the pigment (B1) is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more, and is also acceptable to be 100% or less, 90% or less, or 80% or less. By including the pigment (B1), when near-infrared rays are irradiated, the irradiated light is reflected and / or scattered with high intensity, which can contribute to improving the detection accuracy in LiDAR technology.

[0071] In the present disclosure, near-infrared reflectance refers to the arithmetic mean value of spectral reflectance measured in the wavelength range of 800 to 2,500 nm in accordance with JIS K 5602: 2008. The spectral reflectance can be measured using a spectrophotometer.

[0072] In the present disclosure, the near-infrared reflectance of a pigment can be measured by forming a coating film containing the pigment and measuring the reflectance of the coating film. Specifically, the pigment, resin, and solvent described in Measurement Example 1 of Pigment Near-Infrared Reflectance and Spectral Reflectance below are mixed so that the pigment mass concentration (also referred to as PWC) shown in the following formula is 3 to 45% by mass, and the mixture is dispersed using a disperser at a rotation speed of 1,800 rpm for 60 minutes to form a dispersion. The dispersion is then applied to a black-and-white hiding power test paper (manufactured by Nippon Test Panel Co., Ltd.) as a base using an 8-mil doctor blade to a thickness of approximately 50 μm after drying, and dried at 60°C for 20 minutes to form a dried coating film. In accordance with JIS K 5602:2008, the spectral reflectance of the white-based portion of the dried coating film is measured using a spectrophotometer in the wavelength range of 800 to 2,500 nm, and the arithmetic average value is taken as the near-infrared reflectance of the pigment. The spectral reflectance at wavelengths of 905 nm and 1,550 nm, which will be described later, can also be measured in accordance with the method for measuring spectral reflectance described above. For example, a spectrophotometer (Shimadzu Corporation, SHIMADZU-UV3600, etc.) can be used for the measurement. Pigment mass concentration (PWC: mass %) = (pigment solid content) / (pigment solid content + resin solid content) × 100

[0073] In the present disclosure, the solid content of the resin means the total solid content of the film-forming resin (A) and the crosslinking agent (C) used as needed, which will be described later, and can be determined by measuring the heating residue (mass of the residue after heating at 105°C for 60 minutes) in accordance with JIS K 5601-1-2 (2008).

[0074] In addition, when measuring near-infrared reflectance and spectral reflectance, the pigment mass concentration of each pigment is set to a concentration or higher at which the white and black of the underlying layer cannot be seen through when a dry coating film is formed on the black-and-white hiding power test paper. In the present disclosure, the pigment mass concentrations of each pigment are set to 25% by mass for organic red pigments, 30% by mass for inorganic red pigments, 25% by mass for organic yellow pigments, 30% by mass for inorganic yellow pigments, 20% by mass for blue pigments, 45% by mass for white pigments, 3% by mass for organic black pigments, and 50% by mass for inorganic black pigments.

[0075] The pigment (B1) preferably includes a pigment selected from the group consisting of chromatic pigments and achromatic pigments. The chromatic pigments include any pigments with a color saturation greater than 0, such as reddish pigments, greenish pigments, blueish pigments, and yellowish pigments. The pigment (B1) preferably includes one or more pigments selected from the group consisting of reddish pigments, blueish pigments, and yellowish pigments.

[0076] The pigment (B1) may be an organic pigment and / or an inorganic pigment. The organic pigment tends to have high saturation and high near-infrared reflectance, while the inorganic pigment tends to have high weather resistance.

[0077] The content of the organic pigment in 100% by mass of the total pigment (B1) may be 0% by mass or more and 100% by mass or less, 0.3% by mass or more and 70% by mass or less, or 0.5% by mass or more and 60% by mass or less.

[0078] The content of the inorganic pigment in 100% by mass of the total pigment (B1) may be 0% by mass or more and 100% by mass or less, 5% by mass or more and 99% by mass or less, 10% by mass or more and 95% by mass or less, or 10% by mass or more and 93% by mass or less.

[0079] The near-infrared reflectance of the red pigment as the pigment (B1) is, for example, preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and even more preferably 55% or more, and is also acceptable to be, for example, 80% or less, or even 70% or less.

[0080] The spectral reflectance of the red pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 20% or more, more preferably 25% or more, even more preferably 30% or more, and still more preferably 35% or more. For example, it is acceptable for the spectral reflectance to be 90% or less, or even 85% or less.

[0081] The red pigment may be an organic pigment and / or an inorganic pigment, and the content of the organic pigment in the red pigment may be 0% by mass, 1% by mass or more and 100% by mass or less, or 20% by mass or more and 50% by mass or less.

[0082] The near-infrared reflectance of the organic red pigment is preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and even more preferably 55% or more. For example, it is acceptable for the reflectance to be 80% or less, or even 70% or less.

[0083] The spectral reflectance of the organic red pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 40% or more, more preferably 50% or more, even more preferably 55% or more, and still more preferably 60% or more. For example, it is acceptable for the spectral reflectance to be 90% or less, or even 85% or less.

[0084] The near-infrared reflectance of the inorganic red pigment is preferably 40% or more, more preferably 45% or more, and is acceptable to be, for example, 80% or less, and even 70% or less.

[0085] The spectral reflectance of the inorganic red pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 20% or more, more preferably 30% or more, and is acceptable to be, for example, 90% or less, and further 85% or less.

[0086] Examples of red pigments as the pigment (B1) include organic red pigments such as Fastogen Super Magenta RH, Fastogen Super Red 7100Y, Fastogen Super Red 500RG, Fastogen Super Violet RVS, Fastogen Super Red 400RG, and Fastogen Super Red 500RG (all manufactured by DIC Corporation), CINILEX DPP RED SR1C (manufactured by CINIC Chemicals), and Pacific Red 2020 (manufactured by Ciba Specialty Chemicals), and inorganic red pigments such as Todacolor 120ED (manufactured by Toda Kogyo Co., Ltd.) and BAYFERROX 130M (manufactured by Lanxess AG) and the like.

[0087] The near-infrared reflectance of the blue pigment as pigment (B1) is preferably 40% or more, more preferably 45% or more, and is acceptable to be, for example, 80% or less, or even 70% or less.

[0088] The spectral reflectance of the blue pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 30% or more, more preferably 35% or more, and is acceptable to be, for example, 90% or less, and even 85% or less.

[0089] Examples of the blue pigment include Dipyroxide Blue #9453 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), FastogenBlue 5485K, Fastogen Blue RSKE, Fastogen Blue CA5380 (all manufactured by DIC Corporation), Cyanine Blue 5240KB (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), Lionol Blue SPG-8 (manufactured by Toyocolor Co., Ltd.), HELIOGEN BLUE L7460 (manufactured by BASF), Dipyroxide Green #9310 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), FastogenGreen 2YK (manufactured by DIC Corporation), and Lionol Green 6YKP-N (manufactured by Toyocolor Co., Ltd.).

[0090] The near-infrared reflectance of the yellow pigment is preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and even more preferably 55% or more. For example, it is acceptable for the reflectance to be 90% or less, or even 85% or less.

[0091] The spectral reflectance of the yellow pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 15% or more, more preferably 20% or more, even more preferably 25% or more, and still more preferably 30% or more. For example, it is acceptable for the spectral reflectance to be 95% or less, or even 90% or less.

[0092] The yellow pigment may be an organic pigment and / or an inorganic pigment. The content of the organic pigment in the yellow pigment may be 0% by mass, 1% by mass or more, or 10% by mass or more. The content may be 50% by mass or less, with the upper limit being 100% by mass.

[0093] The near-infrared reflectance of the organic yellow pigment is preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and even more preferably 55% or more. For example, it is acceptable for the reflectance to be 90% or less, or even 85% or less.

[0094] The spectral reflectance of the organic yellow pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and even more preferably 55% or more. For example, it is acceptable for the spectral reflectance to be 95% or less, or even 90% or less.

[0095] The near-infrared reflectance of the inorganic yellow pigment is preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and even more preferably 55% or more. For example, it is acceptable for the reflectance to be 90% or less, or even 85% or less.

[0096] The spectral reflectance of the inorganic yellow pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 20% or more, more preferably 25% or more, and is acceptable to be, for example, 90% or less, or even 85% or less.

[0097] Examples of the yellow pigment include organic yellow pigments such as Symuler Fast Yellow 4192 (manufactured by DIC Corporation) and HOSTAPERM YELLOW H3G (manufactured by Clariant Japan K.K.), etc. Examples of inorganic yellow pigments include Irgacolor Yellow 2GLMA (manufactured by Ciba Specialty Chemicals), Shiko Pearl Yellow L-1100 (manufactured by BASF), and TAROX Synthetic Iron Oxide YM1100 (manufactured by Titanium Kogyo Co., Ltd.).

[0098] The chromatic pigment as the pigment (B1) preferably includes a red pigment, a blue pigment, and a yellow pigment, such as a mixture of Symuler Fast Yellow 4192 (manufactured by DIC Corporation) as a yellow pigment, Fastogen Super Red 7100Y (manufactured by DIC Corporation) as a red pigment, and Lionol Blue SPG-8 (manufactured by Toyocolor Co., Ltd.) as a blue pigment.

[0099] The total content of the red pigment, blue pigment, and yellow pigment in the chromatic pigment is, for example, 20% by mass or more, preferably 30% by mass or more, with the upper limit being 100% by mass.

[0100] The content of the chromatic pigment in the pigment (B1) may be, for example, 0% by mass or more, 1% by mass or more, or 5% by mass or more, and may be, for example, 100% by mass or less, 70% by mass or less, 50% by mass or less, 25% by mass or less, 20% by mass or less, or 18% by mass or less.

[0101] The achromatic pigment includes any pigment having a saturation of 0. Examples of the achromatic pigment include white pigments, gray pigments, and black pigments, and include white pigments and black pigments.

[0102] The near-infrared reflectance of the white pigment as the pigment (B1) is preferably 60% or more, more preferably 65% ​​or more, even more preferably 70% or more, and still more preferably 75% by mass or more. For example, it is acceptable for the reflectance to be 99% or less, or even 90% or less.

[0103] Examples of the white pigment include titanium oxides such as TIPAQUE CR-97 and TIPAQUE CR-95 (both manufactured by Ishihara Sangyo Kaisha), and Typure R-902 (manufactured by Chemours).

[0104] The spectral reflectance of the white pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 60% or more, more preferably 65% ​​or more, even more preferably 70% or more, and still more preferably 75% by mass or more. For example, it is acceptable for the spectral reflectance to be 99% or less, or even 90% or less.

[0105] The content of the white pigment in the pigment (B1) may be, for example, 0% by mass or more, 1% by mass or more, or 3% by mass or more, and may be 100% by mass or less, 99% by mass or less, or 90% by mass or less, for example, 80% by mass or less, 70% by mass or less, or 65% by mass or less.

[0106] The near-infrared reflectance of the black pigment as the pigment (B1) is preferably 5% or more, more preferably 8% or more, even more preferably 10% or more, and still more preferably 15% or more. For example, it is acceptable for the reflectance to be 90% or less, or even 85% or less.

[0107] The spectral reflectance of the black pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 5% or more, more preferably 8% or more, even more preferably 10% or more, and even more preferably 15% or more. For example, it is acceptable for the spectral reflectance to be 90% or less, or even 85% or less.

[0108] The black pigment may be an organic pigment and / or an inorganic pigment, and the content of the organic pigment in the black pigment may be 0% by mass, 1% by mass or more, 20% by mass or more, or 50% by mass or less, with the upper limit being 100% by mass.

[0109] The near-infrared reflectance of the organic black pigment is preferably 20% or more, more preferably 30% or more, even more preferably 35% or more, and still more preferably 40% or more. For example, it is acceptable for the reflectance to be 80% or less, or even 70% or less.

[0110] The spectral reflectance of the organic black pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 40% or more, more preferably 50% or more, even more preferably 55% or more, and still more preferably 60% or more. For example, it is acceptable for the spectral reflectance to be 90% or less, or even 85% or less.

[0111] The near-infrared reflectance of the inorganic black pigment is preferably 30% or more, more preferably 40% or more, and is acceptable to be, for example, 80% or less, and even 70% or less.

[0112] The spectral reflectance of the inorganic black pigment at wavelengths of 905 nm and / or 1,550 nm is preferably 5% or more, more preferably 10% or more, and is acceptable to be, for example, 85% or less, or even 80% or less.

[0113] Examples of the black pigment include inorganic black pigments such as Dipyroxide Black #9590, Dipyroxide Brown #9290, and Dipyroxide Brown #9211 (all manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), Black 411A (manufactured by The Shepherd Color Company), and Black 6350N (manufactured by Asahi Kasei Kogyo Co., Ltd.), and organic black pigments such as Chromofine Black A-1103 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), Fastogen Super Black MX (manufactured by DIC Corporation), Paliogen Black S0084, and Paliotol Black L0080 (all manufactured by BASF), and Hoster Palm Brown HFR-01 (manufactured by Clariant Japan KK).

[0114] The content of the black pigment in the pigment (B1) may be 0% by mass or more, 1% by mass or more, or 5% by mass or more, and may be, for example, 50% by mass or less, 45% by mass or less, or 40% by mass or less.

[0115] The total content of the white pigment and the black pigment in the achromatic pigment is, for example, 50% by mass or more, preferably 60% by mass or more, with the upper limit being 100% by mass.

[0116] The content of the achromatic pigment may be 0 parts by mass or more, 10 parts by mass or more, or 50 parts by mass or more relative to 100 parts by mass of the chromatic pigment, and may be, for example, 20,000 parts by mass or less, 10,000 parts by mass or less, 5,000 parts by mass or less, or 2,500 parts by mass or less.

[0117] The pigment (B1) may be used alone or in combination of two or more kinds.

[0118] In one embodiment, the pigment (B1) comprises at least one pigment selected from the group consisting of a white pigment having a near-infrared reflectance of 60% or more, a chromatic pigment having a near-infrared reflectance of 50% or more, and a black pigment having a near-infrared reflectance of 5% or more. By including such a pigment in the pigment (B1), it is possible to improve the near-infrared detection accuracy of the resulting coating film in LiDAR technology, and preferably to improve the near-infrared detection accuracy of the LiDAR technology while maintaining low brightness.

[0119] The pigment (B1) preferably includes at least one selected from the group consisting of a white pigment having a near-infrared reflectance of 60% or more, a blue pigment having a near-infrared reflectance of 50% or more, a red pigment having a near-infrared reflectance of 50% or more, a yellow pigment having a near-infrared reflectance of 50% or more, and a black pigment having a near-infrared reflectance of 30% or more; a white pigment having a spectral reflectance of 70% or more at a wavelength of 905 nm and / or 1,550 nm, a blue pigment having a spectral reflectance of 40% or more at a wavelength of 905 nm and / or 1,550 nm, a black pigment having a spectral reflectance of 50% or more at a wavelength of 905 nm and / or 1,550 nm, a It is more preferable that the pigment contains at least one pigment selected from the group consisting of an organic red pigment having a spectral reflectance of 20% or more at wavelengths of 905 nm and / or 1,550 nm, an organic yellow pigment having a spectral reflectance of 60% or more at wavelengths of 905 nm and / or 1,550 nm, an inorganic yellow pigment having a spectral reflectance of 20% or more at wavelengths of 905 nm and / or 1,550 nm, an organic black pigment having a spectral reflectance of 50% or more at wavelengths of 905 nm and / or 1,550 nm, and an inorganic black pigment having a spectral reflectance of 15% or more at wavelengths of 905 nm and / or 1,550 nm.

[0120] The total content of the pigment (B1) in the color pigment (B) may be 20% by mass or more, 30% by mass or more, or 50% by mass or more, and may be, for example, 100% by mass or less, 98% by mass or less, or 95% by mass or less.

[0121] The color pigment (B) may contain a color pigment (b) other than the pigment (B1) to the extent that the near-infrared reflectance and spectral reflectance of the coating film obtained from the coating composition are not affected. The color pigment (b) may be any compound classified as a pigment in the Color Index other than the pigment (B1). Examples of the color pigment (b) include organic black pigments, such as carbon black. The content (pigment mass concentration) of the color pigment (b) in the color pigment (B) may be 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less.

[0122] The average primary particle diameter (D50) of the color pigment (B) can be preferably 1 nm or more and 500 nm or less, more preferably 5 nm or more and 300 nm or less. The average primary particle diameter (D50) of the color pigment (B) can be measured using a laser Doppler particle size analyzer (e.g., Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.)).

[0123] The content of the organic pigment may be 0% by mass or more and 100% by mass or less, 0.3% by mass or more and 70% by mass or less, or 0.5% by mass or more and 60% by mass or less, relative to 100% by mass of the total pigment (B).

[0124] Furthermore, the content of the inorganic pigment may be 0% by mass or more and 100% by mass or less, 5% by mass or more and 99% by mass or less, 10% by mass or more and 95% by mass or less, or 10% by mass or more and 93% by mass or less, relative to a total of 100% by mass of the pigment (B).

[0125] The content of the pigment (B) (pigment mass concentration) is preferably 5% by mass or more, more preferably 8% by mass or more, and is preferably 55% by mass or less, more preferably 50% by mass or less, based on 100% by mass of the total solid content of the coating film-forming resin (A), the pigment (B), and the crosslinking agent (C) used as needed.

[0126] The content (pigment mass concentration) of the pigment (B1) is preferably 3 mass% or more, more preferably 8 mass% or more, and is preferably 55 mass% or less, more preferably 50 mass% or less, based on 100 mass% of the total solid content of the coating film-forming resin (A), the pigment (B), and the crosslinking agent (C) used as needed.

[0127] The lightness (L* value) of the coating film obtained by the coating composition is preferably 80 or less, and may be, for example, 5 or more. It may also be, for example, 70 or less, or 15 or more. By using the coating composition of the present invention, visibility in LiDAR technology can be maintained even when the lightness (L* value) of the coating film is low. Note that the lightness (L* value) of the coating film may vary depending on the thickness (film thickness) of the coating film.

[0128] In the present disclosure, the brightness of a coating film can be measured in the same manner as the brightness of a coating film containing the pigment. Specifically, the pigment, resin, and solvent described in Measurement Example 1 of Pigment Near-Infrared Reflectance and Spectral Reflectance below are mixed to a pigment mass concentration of 3 to 45% by mass, and dispersed using a disperser at a rotation speed of 1,800 rpm for 60 minutes to form a dispersion. The dispersion is then coated using a black-and-white opacity test paper (manufactured by Nippon Test Panel Co., Ltd.) as a base to a thickness of approximately 100 μm after drying, and dried at 60°C for 20 minutes to form a dried coating film. The brightness of the white-based portion of the resulting dried coating film is measured in accordance with JIS K 5600-4-4-3.2 and JIS K 5600-4-5, and this brightness can be determined. The brightness can be measured, for example, using a colorimeter CR-400 (manufactured by Konica Minolta, Inc.).

[0129] The desired brightness of the coating film is expressed as L* ０ When the above L* ０ The relationship between the range of the pigment mass concentration of each pigment and L* is expressed by the following formula: That is, the pigment mass concentration of each pigment may be in a range that satisfies the following formula: ０ L* can take the value in the range described above as the lightness of the coating film. ０=2.9(W)-0.6(IR)-1.6(OR)+0.6(IY)+29.4(OY)+0.1(OB)-2.0(IBL)-2.1(OBL)+25.6...Formula (1)

[0130] Here, (W) is the pigment mass concentration (% by mass) of the white pigment, (IR) is the pigment mass concentration (% by mass) of the inorganic red pigment, (OR) is the pigment mass concentration (% by mass) of the organic red pigment, (IY) is the pigment mass concentration (% by mass) of the inorganic yellow pigment, (OY) is the pigment mass concentration (% by mass) of the organic yellow pigment, (OB) is the pigment mass concentration (% by mass) of the blue pigment, (IBL) is the pigment mass concentration (% by mass) of the inorganic black pigment, and (OBL) is the pigment mass concentration (% by mass) of the organic black pigment.

[0131] The near-infrared reflectance of the desired coating film is X ０ (%), the X ０ The relationship between the mass concentration of each pigment and the mass ratio of each pigment is expressed by the following formula: In other words, the mass concentration of each pigment may be in a range that satisfies the following formula: ０ (%) can take the value in the range described above as the near-infrared reflectance of the coating film. ０ =3.0(W)+0.2(IR)+0.1(OR)+1.8(IY)+0.6(OY)-2.4(OB)-0.2(IBL)-0.7(OBL)+39.9...Formula (2)

[0132] The spectral reflectance of the target coating film at a wavelength of 905 nm is defined as Y ０ (%), the Y ０ The relationship between the pigment mass concentration of each pigment and the pigment mass ratio (%) is expressed by the following formula: In other words, the pigment mass concentration of each pigment may be in a range that satisfies the following formula: ０ Y (%) can take the value in the range described above as the spectral reflectance of the coating film at a wavelength of 905 nm. ０ =3.5(W)-4.1(IR)+1.1(OR)+1.8(IY)+0.1(OY)-4.3(OB)-0.8(IBL)+0.6(OBL)+52.9...Formula (3)

[0133] The spectral reflectance of the target coating film at a wavelength of 1,550 nm is Z ０ (%), the Z ０The relationship between Z (%) and the pigment mass concentration of each pigment is expressed by the following formula: In other words, the pigment mass concentration of each pigment may be in a range that satisfies the following formula: ０ Z (%) can take the value in the range described above as the spectral reflectance of the coating film at a wavelength of 1,550 nm. ０ =2.9(W)+1.7(IR)-0.4(OR)+1.9(IY)+1.1(OY)-1.6(OB)+0.1(IBL)-1.4(OBL)+39.8...Formula (4)

[0134] The lightness of the coating film may be 80 or less. Various combinations of pigment mass concentrations are calculated using formula (1). Among these combinations, formulas (2) to (4) can be used to calculate combinations of pigment concentrations that achieve desired values ​​or higher (e.g., 15% or higher) for the near-infrared reflectance, the spectral reflectance at a wavelength of 905 nm, and the spectral reflectance at a wavelength of 1,550 nm.

[0135] (C) Crosslinking Agent: In addition to the film-forming resin (A) and the pigment (B), the coating composition may contain a crosslinking agent (C). The crosslinking agent (C) is a compound capable of forming a crosslinked structure in the film-forming resin (A) by forming a chemical bond and / or a physical bond. Examples of the crosslinking agent (C) include a compound having two or more groups containing active hydrogen atoms, such as hydroxy groups, carboxy groups, or amino groups, per molecule; or a compound having two or more groups reactive with the active hydrogen atom-containing groups per molecule. When the film-forming resin (A) contains a group containing an active hydrogen atom or a group reactive with the active hydrogen atom-containing group, it can react with the crosslinking agent (C) to form a crosslinked structure in the film-forming resin (A).

[0136] Examples of the crosslinking agent (C) include polyisocyanate compounds, blocked polyisocyanate compounds, amino resins, phenolic resins, polycarboxylic acids, etc. These may be used alone or in combination of two or more.

[0137] The polyisocyanate compound refers to a compound having two or more isocyanate groups in one molecule. Examples of the polyisocyanate include aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and mixtures thereof, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, and mixtures thereof, naphthylene-1,5-diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, and xylylene diisocyanate; alicyclic polyisocyanates such as dicyclohexylmethane diisocyanate, isophorone diisocyanate, and hydrogenated xylylene diisocyanate; and aliphatic polyisocyanates such as hexamethylene diisocyanate.

[0138] The blocked polyisocyanate compound (hereinafter, sometimes referred to as "BI") means a compound in which the isocyanate group of the isocyanate compound is blocked with a blocking agent.

[0139] The blocking agent may be any compound having an active hydrogen-containing compound, and examples thereof include phenolic compounds such as phenol, cresol, and xylenol; lactam compounds such as ε-caprolactam, δ-valerolactam, and γ-butyrolactam; aliphatic alcohol compounds such as methanol, ethanol, and n-, i-, or t-butyl alcohol; glycol ether compounds such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and propylene glycol monomethyl ether; aromatic alcohol compounds such as benzyl alcohol; oxime compounds such as formamidoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime; and active methylene compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, and acetylacetone. By mixing the polyisocyanate compound with the blocking agent, free isocyanate groups of the polyisocyanate compound can be blocked.

[0140] The amino resin refers to a resin obtained by addition polymerization of an aldehyde with a compound having an amino group. The amino resin is preferred because it has excellent crosslinking reactivity with the coating film-forming resin (A), especially in the absence of a catalyst.

[0141] Examples of the amino resin include melamine resin and urea resin, with melamine resin being preferred.

[0142] The melamine resin is a thermosetting resin synthesized from melamine and aldehyde. The melamine resin has a triazine nucleus and three reactive functional groups (-NX) per triazine nucleus. １ X ２ The melamine resin has a reactive functional group of —N(CH ２ OR) ２ [R represents an alkyl group having 1 to 8 carbon atoms, the same applies hereinafter]; ２ OR) (CH ２ methylol group type containing -N(CH ２ imino group type containing -N(CH ２ OR) (CH ２ -OH) and -N(CH ２ OR)(H), or -N(CH ２ Four types of methylol / imino group type containing (OH)(H) are listed. As the melamine resin, one type may be used, or two or more types may be used in combination. As the crosslinking agent (C), the melamine resin and the polyisocyanate compound may be used in combination. Furthermore, a metal catalyst such as a tin compound or a titanium compound may be used as needed.

[0143] Examples of the phenol compound include glycidyl ether resins such as a condensation reaction product of bisphenol A and epichlorohydrin, and a condensation reaction product of bisphenol F and epichlorohydrin; alicyclic epoxy resins, linear aliphatic epoxy resins, bromine-containing epoxy resins, phenol novolac epoxy resins, and cresol novolac epoxy resins.

[0144] The polycarboxylic acid refers to a compound having two or more carboxy groups in one molecule. Examples of the polycarboxylic acid include aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid; alicyclic polycarboxylic acids such as tetrahydrophthalic acid, hexahydrophthalic acid, methyltetrahydrophthalic acid, cyclohexane-1,4-dicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid, and methyl-5-norbornene-2,3-dicarboxylic acid; aliphatic polycarboxylic acids such as maleic acid, fumaric acid, itaconic acid, adipic acid, azelaic acid, sebacic acid, succinic acid, and dodecenylsuccinic acid; hydroxy acids of lactose; and anhydrides of the aromatic polycarboxylic acids, alicyclic polycarboxylic acids, and aliphatic polycarboxylic acids.

[0145] In one embodiment, the crosslinking agent (C) is preferably at least one selected from the group consisting of polyisocyanate compounds, blocked polyisocyanate compounds, and amino resins.

[0146] The content of the crosslinking agent (C) may be, for example, 3 parts by mass or more, 7 parts by mass or more, 10 parts by mass or more, or 20 parts by mass or more, per 100 parts by mass of the total of 100 parts by mass of the coating film-forming resin (A) and the crosslinking agent (C), and may be, for example, 50 parts by mass or less, 40 parts by mass or less, 35 parts by mass or less, or 30 parts by mass or less.

[0147] The total content of the film-forming resin (A) and the crosslinking agent (C) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the solid content of the coating composition, and is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less.

[0148] (D) Extender Pigment The coating composition of the present disclosure contains an extender pigment (D). In this disclosure, the term "extender pigment" refers to a pigment other than a coloring pigment that is intended to increase or reinforce the coating composition. In one embodiment, the extender pigment (D) may be a pigment that contributes little to coloring, and the refractive index of the extender pigment (D) with respect to white light at 25°C may be preferably 1.2 or more and 1.8 or less, more preferably 1.3 or more and 1.7 or less.

[0149] It contains one or more selected from carbonates (D1) and metasilicates (D2).

[0150] The carbonate (D1) preferably contains, for example, a metal carbonate, such as calcium carbonate, magnesium carbonate, or dolomite (CaMg(CO ３ ) ２ and transition metal carbonates such as iron(II) carbonate. In one embodiment, the carbonate is calcium carbonate. The calcium carbonate preferably includes either heavy calcium carbonate or light calcium carbonate, and more preferably includes heavy calcium carbonate.

[0151] The average particle size (D50) of the carbonate (D1) is preferably 10 μm or more and 40 μm or less, more preferably 15 μm or more and 40 μm or less, and even more preferably 25 μm or more and 40 μm or less. When the average particle size of the carbonate (D1) is within the above range, there is an advantage that the appearance and LiDAR recognizability of the obtained coating film are improved.

[0152] The average particle diameter (D50) in the present disclosure is an average particle diameter determined by a laser diffraction / scattering method, and specifically, can be measured using a laser diffraction / scattering particle size distribution measuring device, Microtrac MT3000II series (manufactured by Microtrac Corporation), or the like.

[0153] The calcium carbonate may be a commercially available product, such as ground calcium carbonate, R-30, R-50A, or R-70H (all manufactured by Maruo Calcium Co., Ltd.).

[0154] In the coating composition of the present disclosure, the content of the carbonate (D1) is preferably 40 parts by mass or more and 800 parts by mass or less, more preferably 70 parts by mass or more and 500 parts by mass or less, and even more preferably 90 parts by mass or more and 400 parts by mass or less, relative to 100 parts by mass of the total solids content of the coating film-forming resin (A) and the optional crosslinking agent (C). When the content of the carbonate (D1) is within this range, it can be easy to suppress whitening of the coating film due to ambient light, particularly light irradiated from the opposite direction of the laser light irradiation unit and the reflected light detection unit, while maintaining retroreflectivity (LiDAR visibility).

[0155] The metasilicate (D2) is metasilicic acid (H ２ SiO ３ ) salt. The metasilicate (D2) typically includes a metal salt of metasilicic acid, and preferably includes an alkaline earth metal salt of metasilicic acid. Specific examples of the metasilicate include magnesium metasilicate, calcium metasilicate, strontium metasilicate, and barium metasilicate.

[0156] The average particle diameter D50 of the metasilicate (D2) is preferably 5 μm or more and 40 μm or less, more preferably 15 μm or more and 40 μm or less, and even more preferably 25 μm or more and 40 μm or less. When the average particle diameter of the metasilicate (D2) is within the above range, there is an advantage that whitening of the coating film due to ambient light, particularly light irradiated from the opposite direction of the laser light irradiation unit and the reflected light detection unit, can be suppressed while maintaining retroreflectivity (LiDAR visibility).

[0157] The metasilicate (D2) may be a commercially available product, such as Wollastonite WP200 (manufactured by Nippon Talc Co., Ltd.).

[0158] In the coating composition of the present disclosure, the content of the metasilicate (D2) is preferably 100% by mass or more and 500% by mass or less, more preferably 150% by mass or more and 400% by mass or less, and even more preferably 200% by mass or more and 400% by mass or less, based on 100% by mass of the total solid content of the coating film-forming resin (A) and the crosslinking agent (C). When the content of the metasilicate (D2) is within this range, it can be easy to improve the visibility of the coating film in ambient light while maintaining retroreflectivity (LiDAR visibility).

[0159] In the coating composition of the present disclosure, the total content of the carbonate (D1) and the metasilicate (D2) may be preferably 70% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less, based on 100% by mass of the total amount of the extender pigment (D).

[0160] The extender pigment (D) may contain other extender pigments in addition to the carbonate (D1) and the metasilicate (D2). Examples of such other extender pigments include barium sulfate, clay, talc, kaolin, mica, silica, alumina, and bentonite. The other extender pigments may be surface-treated.

[0161] The average particle diameter D50 of the extender pigment (D) is preferably 5 μm or more and 40 μm or less, more preferably 15 μm or less and 40 μm or less, and even more preferably 25 μm or more and 40 μm or less. Having an average particle diameter within this range has the advantage of being able to maintain retroreflectivity (LiDAR visibility) while suppressing whitening of the coating film due to ambient light, particularly light irradiated from the opposite direction of the laser light irradiation unit and the reflected light detection unit.

[0162] The content of the extender pigment (D) is preferably 90% by mass or more and 800% by mass or less, more preferably 150% by mass or more and 500% by mass or less, and even more preferably 200% by mass or more and 400% by mass or less, based on 100% by mass of the total solids content of the coating film-forming resin (A) and the optional crosslinking agent (C). By having the content of the extender pigment (D) within this range, it can be easy to suppress the visibility of the coating film due to ambient light while maintaining retroreflectivity (LiDAR visibility).

[0163] The content of the extender pigment (D) (pigment volume concentration (PVC: volume %)) is preferably 25 to 60 volume %, more preferably 40 to 60 volume %, and even more preferably 45 to 60 volume %, based on 100 volume % of the total solids content of the film-forming resin (A), the optional crosslinker (C), and the extender pigment (D). Having the content (pigment volume concentration) of the extender pigment (D) within this range makes it easy to improve the visibility of the coating film in ambient light while maintaining retroreflectivity (LiDAR visibility). Extender pigment concentration (extender pigment PVC: volume %) = (volume of solids content of extender pigment) / (volume of solids content of extender pigment + volume of solids content of resin) x 100

[0164] (E) Solvent The coating composition may further contain a solvent (E). The solvent preferably contains an aqueous medium (E1) and / or an organic solvent (E2).

[0165] Examples of the aqueous medium (E1) include water, a hydrophilic solvent, and a mixture of water and a hydrophilic solvent.

[0166] Examples of the hydrophilic solvent include glycol solvents such as ethylene glycol, propylene glycol, butanediol, pentanediol, diethylene glycol, dipropylene glycol, and triethylene glycol; glycol ether solvents such as ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and propylene glycol monomethyl ether acetate; alcohol solvents such as methanol, ethanol, and isopropyl alcohol; ketone solvents such as acetone; and N-methyl-2-pyrrolidone. The use of such hydrophilic solvents has the advantage of improving the wettability of the resulting coating composition with the substrate.

[0167] Examples of the organic solvent (E2) include ether solvents such as dioxane and tetrahydrofuran; ester solvents such as 3-methoxybutyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; aromatic hydrocarbon solvents such as toluene, T-SOL 100, and T-SOL 150 (all manufactured by Exxon Chemical Co.); hydrocarbon solvents such as pentane, isopentane, hexane, isohexane, and cyclohexane; and mineral oils such as solvent naphtha and mineral spirits. These may be used alone or in combination of two or more.

[0168] The coating composition may be an aqueous coating composition containing an aqueous medium (E1) as the solvent (E), or a solvent-based coating composition containing an organic solvent (E2) as the solvent (E). When the coating composition is an aqueous coating composition, the content of the aqueous medium (E1) in the solvent (E) is preferably 50% by mass or more, more preferably 70% by mass or more, and preferably 100% by mass or less. When the coating composition is a solvent-based coating composition, the content of the organic solvent (E2) in the solvent (E) is preferably 50% by mass or more, more preferably 70% by mass or more, and preferably 100% by mass or less.

[0169] The content of the solvent (E) in the coating composition is preferably 0% by mass or more, more preferably 10% by mass or more, even more preferably 25% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less.

[0170] The coating composition may be a water-based coating, an organic solvent-based coating, or a solventless coating such as a powder coating.

[0171] The coating composition may further contain other additives. Examples of the other additives include surface conditioners; colorants such as dyes; waxes; luster pigments; fillers, aggregates; ultraviolet absorbers (benzophenone-based ultraviolet absorbers, etc.); antioxidants (phenolic, sulfide, and hindered amine antioxidants, etc.); plasticizers; coupling agents (silane-based, titanium-based, and zirconium-based coupling agents, etc.); anti-sagging agents; thickeners; pigment dispersants; pigment wetting agents; leveling agents; color separation inhibitors; precipitation inhibitors; antifoaming agents; antifreeze agents; emulsifiers; preservatives; mildew inhibitors; antibacterial agents; and stabilizers. These additives may be used alone or in combination of two or more.

[0172] Examples of the luster pigment include mica, aluminum foil, tin foil, gold foil, silver foil, titanium gold foil, stainless steel foil, and metal foil such as nickel or copper foil.

[0173] The coating composition can be prepared by dissolving or dispersing the film-forming resin (A), the pigment (B), the extender pigment (D), and the optional crosslinker (C) and other additives in the optional solvent (E). The order of mixing the various materials used is not particularly limited. For example, the pigment (B) and a portion of the film-forming resin (A) may be premixed to form a pigment paste, which may then be mixed with the remaining components and other optional components to produce the coating composition. The coating composition of the present disclosure can be prepared by mixing the components using a mixer, disperser, kneader, or the like, selected from a sand grinding mill, ball mill, blender, paint shaker, or disperser.

[0174] A coating film formed from the coating composition is also included within the technical scope of the present disclosure.

[0175] The near-infrared reflectance of the coating film is preferably 15% or more, more preferably 30% or more, and even more preferably 35% or more, and is acceptable to be, for example, 99% or less, or even 90% or less.

[0176] The spectral reflectance of the coating film at wavelengths of 905 nm and / or 1,550 nm is preferably 20% or more, more preferably 30% or more, and even more preferably 35% or more. For example, it is acceptable for the reflectance to be 99% or less, or even 90% or less.

[0177] The near-infrared reflectance of the coating film, and the spectral reflectance at wavelengths of 950 nm and / or 1,550 nm, can be measured, for example, according to a method similar to the method described as the method for measuring the near-infrared reflectance of a coating film containing a pigment when measuring the near-infrared reflectance of a pigment.

[0178] The coating film for measuring the near-infrared reflectance can be formed, for example, by the following method.

[0179] The coating composition is applied to a black-and-white hiding power test paper (manufactured by TP Giken Co., Ltd.) as a base so that the thickness of the wet coating film becomes 30 μm or more and 2,000 μm or less, and the coating film is heated at a heating temperature of 20° C. or more and 200° C. or less for 10 minutes to 24 hours or less to obtain a dry coating film.

[0180] The lightness (L* value) of the coating film obtained from the coating composition may be 80 or less, for example, 70 or less. It may also be, for example, 5 or more, or 15 or more.

[0181] The brightness of the coating film can be measured using a colorimeter, for example, in accordance with JIS K 5600-4-4-3.2 and JIS K 5600-4-5. The colorimeter can be, for example, a CR-400 (manufactured by Konica Minolta).

[0182] Since the wavelength range of near-infrared light is close to the visible light range, a coating composition with high near-infrared reflectance tends to have high visible light reflectance and high brightness. Generally, when the brightness (L* value) falls below 80, the near-infrared reflectance tends to decrease, and LiDAR visibility tends to decrease. However, by having the above-mentioned configuration, the coating composition can easily increase the near-infrared reflectance while lowering the brightness.

[0183] The brightness of the coating film measured by the above method may be, for example, 90 or less, or 80 or less, or 3 or more, or 5 or more.

[0184] The root mean square gradient (Sdq) of the surface of a coating film formed from the coating composition of the present disclosure, measured in accordance with ISO 25178, is preferably 0.5 or more, more preferably 1 or more, even more preferably 1.3 to 2.0, and even more preferably 1.5 to 2.0. When the root mean square gradient (Sdq) of the coating film surface is within this range, ambient light is more likely to be attenuated by repeated reflection and absorption within the coating film, and whitening of the coating film due to ambient light, particularly light irradiated from the opposite direction of the laser light irradiation unit and the reflected light detection unit, can be easily suppressed while maintaining retroreflectivity.

[0185] The root mean square gradient (Sdq) is a parameter that represents the average magnitude of the local gradient (slope) of the surface irregularities when measured in accordance with ISO 25178. A larger Sdq indicates a steeper surface, and a completely flat surface has an Sdq of 0.

[0186] The surface of a coating film formed from the coating composition of the present disclosure may preferably have a developed area ratio (Sdr) of 40% or more, more preferably 70% to 150%, and even more preferably 85% to 150% as measured in accordance with ISO 25178. When the developed area ratio (Sdr) on the coating film surface is within this range, ambient light is more likely to be attenuated by reflection within the coating film, making it easier to improve the visibility of the coating film in ambient light while maintaining retroreflectivity.

[0187] The developed area ratio (also referred to as "Sdr") is a parameter that indicates how much the surface area (developed area) reflecting the actual irregularities in the measurement area increases relative to the area of ​​a flat surface without irregularities in the measurement area when measured according to ISO 25178, and is expressed by the following formula: The smaller this Sdr is, the smoother the surface is, and a completely flat surface has an Sdr of 0%.

[0188] The root mean square gradient (Sdq) and the developed area ratio (Sdr) can be measured, for example, by a laser microscope. The laser microscope that can be used is the VK-X3000 series (manufactured by Keyence Corporation). Developed area ratio (Sdr) = {(A - B) / B} x 100 [%] A: surface area (developed area) reflecting the actual unevenness in the measurement region B: area of ​​a flat surface without unevenness in the measurement region

[0189] The thickness of the coating film of the present disclosure may be preferably 10 μm or more and 3,000 μm or less, more preferably 10 μm or more and 2,000 μm or less, and even more preferably 10 μm or more and 1,500 μm or less.

[0190] A method for forming a coating film using the coating composition of the present disclosure is also included within the technical scope of the present disclosure. A first method for producing a coating film of the present disclosure includes applying the coating composition to a road surface to obtain a coating film, and drying the coating film to obtain a coating film for use in sensing an object using near-infrared light.

[0191] The coating film is preferably applied so that the thickness of the wet coating film is preferably 10 μm or more and 3,000 μm or less, more preferably 20 μm or more and 2,500 μm or less, and even more preferably 30 μm or more and 2,000 μm or less.

[0192] The coating can be carried out by a coating method such as spray coating, bar coater coating, air knife coating, gravure coating, brush coating, roller coating, air gun coating, air electrostatic gun coating, or dip coating.

[0193] The drying temperature for drying the coating film is preferably from 0° C. to 200° C., more preferably from 5° C. to 80° C., and even more preferably from 5° C. to 40° C., and the drying time is preferably from 10 minutes to 24 hours, more preferably from 10 minutes to 60 minutes, and even more preferably from 10 minutes to 45 minutes. As the heating means, hot air heating, infrared heating, induction heating, etc. can be used.

[0194] In the above-described production method, the coating composition is applied to a road surface, but the present invention is not limited to this, and the coating composition may be applied to other substrates, such as metal plates and members made of metal plates, as well as plastic members, inorganic material members, wooden members, and pavements such as road surfaces.

[0195] Examples of the metal sheet include galvanized steel sheets, zinc-aluminum alloy-plated steel sheets, aluminum alloy-plated steel sheets, hot-dip zinc-aluminum-magnesium alloy-plated steel sheets, stainless steel sheets, and cold-rolled steel sheets, all of which are manufactured by hot-dip or electrolytic processes. In addition to these steel sheets or plated steel sheets, metal sheets such as aluminum sheets (including aluminum alloy sheets) can also be coated. The metal sheet is preferably surface-treated. Specifically, the metal sheet is preferably subjected to a pretreatment such as alkaline degreasing, hot water washing, or water washing, followed by a chemical conversion treatment. The chemical conversion treatment may be performed by a known method, and examples include non-chromate treatments such as chromate treatment and zinc phosphate treatment. The surface treatment can be appropriately selected depending on the steel sheet to be used, but a treatment that does not contain heavy metals is preferred.

[0196] Examples of the plastic member include an acrylic plate, a polyvinyl chloride plate, a polycarbonate plate, an ABS plate, a polyethylene terephthalate plate, and a polyolefin plate.

[0197] Examples of the inorganic member include ceramic building materials and glass substrates described in JIS A 5422, JIS A 5430, etc., such as calcium silicate boards, pulp cement boards, slag gypsum boards, magnesium carbonate boards, asbestos-perlite boards, wood chip cement boards, hard wood cement boards, concrete boards, and lightweight aerated concrete boards.

[0198] Examples of the wooden members include lumber, laminated lumber, plywood, particle board, fiber board, improved wood, chemically treated wood, and floorboards.

[0199] Examples of the pavement such as road surfaces include asphalt pavement, concrete pavement, and brick pavement.

[0200] Specific examples of the substrate include structures, articles, etc. that may become obstacles during automatic driving of automobiles, such as various products for sale, driving paths, road structures (e.g., pavements, road markings, sidewalks, crosswalks, drainage facilities, at-grade intersections, bridges, earthworks, tunnels, turnouts, traffic safety facilities (e.g., grade separation facilities, guardrails, guard poles, protective fences, lighting facilities, delineators, road reflectors, etc.), traffic islands, bus stops, parking lanes, parking lots, etc.), various building structures and their internal equipment, railway structures, various protective facilities, various vehicles and their accessories, pedestrian wear, utility poles, and the interior walls of various building structures.

[0201] Furthermore, a sensing method using near-infrared light and the coating film is also included within the technical scope of the present invention.

[0202] For example, in a sensing method (time-of-flight: ToF) for measuring the distance between a vehicle and a painted object, in which near-infrared rays of a specific wavelength are irradiated from a traveling vehicle, the rays are reflected by the object, the reflected light is detected, and the distance from the vehicle to the object is calculated based on the time it takes for the rays to reflect, the object can be obtained by painting the object with the coating composition. Also, in a sensing method (frequency-modulated continuous wave: FMCW) for measuring the distance between a vehicle and a painted object, in which near-infrared rays of a specific wavelength are irradiated from a traveling vehicle, the rays are reflected by the object, the reflected light is detected, and the distance from the vehicle to the object is calculated based on the change in the frequency difference between the irradiated light and the reflected light, the object can be obtained by painting the object with the coating composition.

[0203] The paint composition and coating film can realize a marking that exhibits high retroreflectivity (particularly at high incidence angles) even when formed on a road surface, without being mistaken for a white line. Such a marking can improve the detection accuracy of near-infrared light in LiDAR technology, and preferably can improve the detection accuracy of near-infrared light in LiDAR technology, particularly at incidence angles when long-distance recognition is assumed, while maintaining low brightness. Therefore, the paint and coating film are useful as a paint and coating film for detecting objects using near-infrared light.

[0204] The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to these examples.

[0205] <Measurement Example 1 of Near-Infrared Reflectance and Spectral Reflectance of Pigment> Measurement Example of Near-Infrared Reflectance of Organic Red Pigment, Spectral Reflectance at Wavelengths of 905 nm and / or 1,550 nm 3.5.0 parts by mass of SN Dispersant 5027 as a dispersant, 0.5 parts by mass of SN Deformer 154 as an antifoaming agent, 7.0 parts by mass of tap water (E-1) as a solvent, and 13.0 parts by mass of FASTOGEN SUPER RED 500RG (B2-1) as an organic red pigment were mixed, and then dispersed using an SG mill (medium: glass beads) until the maximum particle size of the pigment coarse particles was 10 μm or less. Next, 74.0 parts by mass of Saibinol YC-102 (A-1) as a coating film-forming resin and 2.0 parts by mass of tap water (E-1) as a solvent were added, and the mixture was mixed while stirring using a disperser to obtain a coating composition (R1-1).

[0206] The coating composition obtained above was applied to a black and white hiding power test paper (manufactured by TP Giken Co., Ltd.) using an 8 mil doctor blade so that the dry film thickness would be 50 μm, and after drying at 60° C. for 20 minutes, it was left to stand at room temperature for 1 day to obtain a coating film.

[0207] For the resulting coating film, the reflectance of the white-based portion was measured in 2-nm wavelength increments in the wavelength range of 800 to 2,500 nm using a spectrophotometer (Shimadzu Corporation, SHIMADZU-UV3600) according to a method in accordance with JIS K 5602. The arithmetic mean value of the reflectance at each wavelength obtained was taken as the near-infrared reflectance of the inorganic red pigment. The near-infrared reflectances at 905 and 1,550 nm are the spectral reflectance values ​​at each wavelength.

[0208] The near-infrared reflectance and spectral reflectance of each of the other pigments were measured in the same manner as in Measurement Example 1 of Near-Infrared Reflectance and Spectral Reflectance of Pigments, except that the type and mass concentration of each pigment were set to the amounts shown in Table 1.

[0209]

[0210] White pigment paste preparation example 1: 3.5 parts by mass of SN Dispersant 5027 as a dispersant, 0.5 parts by mass of SN Defoamer 154 as a defoaming agent, 14.0 parts by mass of tap water (E-1) as a solvent, and 24.0 parts by mass of TIPAQUE CR-97.0 (B1-1) as a white pigment were mixed, and then dispersed using an SG mill (medium: glass beads) until the maximum particle size of the pigment coarse particles was 10 μm or less. Next, 56.0 parts by mass of Saibinol YC-102 (A-1) as a coating film-forming resin and 2.0 parts by mass of tap water (E-1) as a solvent were added, and the mixture was mixed while stirring using a disper to obtain a white pigment paste (W-1).

[0211] Preparation Examples 2 to 6 Pigment pastes of each pigment were obtained in the same manner as in Preparation Example 1, except that the types and amounts of each component were changed as shown in Table 2.

[0212]

[0213] Example 1 8.0 parts by mass of the reddish pigment paste (R1-1), 14.0 parts by mass of the yellowish pigment paste (Y1-1), and 6.0 parts by mass of the blueish pigment paste (Bu-1) were mixed while stirring with a disper, and the resulting colored pigment paste was mixed with 23.4 parts by mass of a coating film-forming resin (A-1), 4.0 parts by mass of a solvent (E-1), and 45.0 parts by mass of KS-800 (D-1) as an extender pigment while stirring with a disper for 15 minutes at 1,500 rpm, to prepare coating composition 1 shown in Example 1.

[0214] <Coating Film (Test Panel) Preparation Example 1> The coating composition 1 obtained above was applied to asphalt felt 430 (100 x 150 mm, manufactured by Shizuoka Rekisei Kogyo Co., Ltd.) using a 20-mil applicator, dried at 60°C for 20 minutes, and then left to stand at room temperature for 1 day to obtain test panel 1.

[0215] Examples 2 to 12 Each coating film (test plate) was obtained in the same manner as in Preparation Example 1 of Coating Film (Test Plate), except that the type and amount of each component was changed as shown in Table 3.

[0216] The details of each component shown in Table 3 below and used in the examples and comparative examples are as follows: Film-forming resins (A) (A-1) Saivinol YC-102 (acrylic styrene resin emulsion, manufactured by Saiden Chemical Industry Co., Ltd.): glass transition temperature: -20°C, acid value: 19 mg KOH / g, hydroxyl value: 0 mg KOH / g, solid content: 50% by mass Extender pigments (D) (D-1) KS-800 (heavy calcium carbonate, manufactured by Kalfin Corporation, average particle size: 7.8 μm) (D-2) KS-500 (heavy calcium carbonate, manufactured by Kalfin Corporation, average particle size: 17.7 μm) (D-3) FP-300 (heavy calcium carbonate, manufactured by Kalfin Corporation, average particle size: 26.7 μm) (D-4) Wollastonite WP200 (wollastonite, manufactured by Nippon Talc Co., Ltd., average particle size: 40 μm) (D-5) Wollastonite WP325 (wollastonite, manufactured by Nippon Talc Co., Ltd., average particle size: 18 μm) (D-6) Wollastonite WP2500 (wollastonite, manufactured by Nippon Talc Co., Ltd., average particle size: 5 μm) (D-7) KS-1300 (heavy calcium carbonate, manufactured by Kalfin Co., Ltd., average particle size: 3.2 μm) (d-1) GASIL HP395 (silicon dioxide, manufactured by Wilbur-Ellis Co., Ltd., average particle size: 15 μm) solvent (E) (E-1) Tap water and other materials Dispersant: SN Dispersant 5027 (special ammonium polycarboxylate, manufactured by San Nopco Co., Ltd.) Defoamer: SN Deformer 154 (mineral oil-based, manufactured by San Nopco Co., Ltd.)

[0217] Evaluation Items 1) Coating Film Brightness The brightness (L* value) of the coating film surface of the test panels obtained in the Examples and Comparative Examples was measured using a color difference meter CR-400 (manufactured by Konica Minolta) in accordance with JIS K 5600-4-4-3.2 and JIS K 5600-4-5.

[0218] 2) Near-infrared reflectance and spectral reflectance For the test panels obtained in the examples and comparative examples, the reflectance in the wavelength range of 800 to 2,500 nm was measured at wavelength intervals of 2 nm using a spectrophotometer (Shimadzu Corporation, SHIMADZU-UV3600) according to a method conforming to JIS K-5602. The arithmetic mean value of the reflectance at each wavelength obtained was taken as the near-infrared reflectance of the coating film. The near-infrared reflectance at 905 and 1,550 nm is the spectral reflectance value at each wavelength.

[0219] 3) Surface Roughness The root mean square gradient (Sdq) and developed area ratio (Sdr) of the coating film surfaces of the test panels obtained in the Examples and Comparative Examples were measured in accordance with ISO 25178 using a laser microscope VK-X3000 (manufactured by Keyence Corporation, laser confocal mode, magnification: 50x).

[0220] 4) Visual Appearance The test specimens obtained in the Examples and Comparative Examples were placed on an asphalt road surface, and visually observed from a position 3 m away from the test specimen and 1.2 m high in the direction directly facing the sunlight (backlit position) during a time period when the sun's altitude was relatively high (10:00-14:00), and evaluated according to the following criteria. A score of 3 or higher was considered acceptable. 6: Appears the same as or slightly darker than the road surface color (low brightness), and is barely noticeable. 5: Appears slightly whiter than the road surface color (high brightness), but is barely noticeable. 4: Appears slightly whiter than the road surface color (high brightness), but is not mistaken for a white line. 3: Appears whiter than the road surface color (high brightness), and is slightly noticeable, but not enough to be mistaken for a white line. 2: Appears clearly whiter than the road surface color (high brightness), and may be mistaken for a white line. 1: Appears the same as a white line, and is indistinguishable from a white line.

[0221] 5) LiDAR Recognition Asphalt Felt 430 (manufactured by Shizuoka Rekisei Kogyo Co., Ltd.) was installed at a height of 0.9 m as the test plate and reference plate obtained in the examples and comparative examples, and LiDAR Mid-40 (manufactured by Livox, wavelength: 905 nm, incident angle: 20 ° and 80 °) was used to measure the reflectance of 10 locations arbitrarily selected from the entire test piece from the same height as the test piece and reference plate, and from a point 5 m away. The arithmetic mean value was taken as the LiDAR reflectance of the test piece and reference plate, and the reflectance of the test piece relative to the reflectance of the reference plate was taken as the LiDAR contrast value and evaluated according to the following criteria. A score of 3 or higher was considered a pass. Note that if the LiDAR contrast value is 4 or higher at an incident angle of 20 ° and 2 or higher at an incident angle of 80 °, the LiDAR wavelength can be detected without any problems using a normal LiDAR receiver. At an incident angle of 20°: 5: The LiDAR contrast of the test piece is 8 or more; 4: The LiDAR contrast of the test piece is 6 or more but less than 8; 3: The LiDAR reflectivity of the test piece is 4 or more but less than 6; 2: The LiDAR reflectivity of the test piece is 2 or more but less than 4; 1: The LiDAR reflectivity of the test piece is less than 2 At an incident angle of 80°: 5: The LiDAR contrast of the test piece is 4 or more; 4: The LiDAR contrast of the test piece is 3 or more but less than 4; 3: The LiDAR reflectivity of the test piece is 2 or more but less than 3; 2: The LiDAR reflectivity of the test piece is 1 or more but less than 2; 1: The LiDAR reflectivity of the test piece is less than 1

[0222]

[0223] Examples 1 to 14 are examples of the present disclosure, and the resulting coating films had good visual appearance and good LiDAR visibility. Comparative Example 1 is an example that did not contain the extender pigment (D), and the resulting coating films had good LiDAR visibility but not fully satisfactory visual appearance. Comparative Example 2 is an example that contained silicon dioxide instead of the extender pigment (D), and it was not possible to prepare a coating composition. Comparative Example 3 is an example that did not contain, as the coloring pigment (B), any of a white pigment with a near-infrared reflectance of 60% or more, a chromatic pigment with a near-infrared reflectance of 50% or more, and a black pigment with a near-infrared reflectance of 30% or more. The resulting coating films had good visual appearance but not fully satisfactory LiDAR visibility.

[0224] The coating film of the present disclosure can maintain retroreflectivity while suppressing whitening of the coating film due to ambient light, particularly light irradiated from the opposite direction of the laser light irradiator and the reflected light detector. Therefore, the coating composition of the present disclosure is widely used not only in AGVs but also in autonomous driving technology for automobiles, electronic devices, and various industries.

Claims

1. A paint composition for a sensing detection object using near-infrared light, which contains a film-forming resin (A), a coloring pigment (B), and an extender pigment (D), wherein the coloring pigment (B) is at least one selected from the group consisting of a white pigment having a near-infrared reflectance of 60% or more, a colored pigment having a near-infrared reflectance of 50% or more, and a black pigment having a near-infrared reflectance of 30% or more when the reflectance in the wavelength range of 800 to 2,500 nm is defined as the near-infrared reflectance, and the extender pigment (D) contains one or more selected from carbonate (D1) and metasilicate (D2).

2. The paint composition for a sensing detection object using near-infrared light according to claim 1, wherein on the surface of the formed paint film, the root mean square gradient (Sdq) measured in accordance with ISO 25178 is 1 or more, and the developed area ratio (Sdr) measured in accordance with ISO 25178 is 40% or more.

3. The paint composition for a sensing detection object using near-infrared light according to claim 1, wherein the colored pigment contains at least one selected from the group consisting of a red pigment, a yellow pigment, and a blue pigment.

4. The paint composition for a sensing detection object using near-infrared light according to claim 3, wherein the red pigment and the yellow pigment each contain an organic pigment and / or an inorganic pigment.

5. The paint composition for a sensing detection object using near-infrared light according to claim 1, wherein the coloring pigment (B) contains at least one selected from the group consisting of a white pigment having a spectral reflectance of 70% or more at a wavelength of 905 nm and / or 1,550 nm, an organic red pigment having a spectral reflectance of 50% or more at the wavelength, an inorganic red pigment having a spectral reflectance of 20% or more at the wavelength, an organic yellow pigment having a spectral reflectance of 60% or more at the wavelength, an inorganic yellow pigment having a spectral reflectance of 20% or more at the wavelength, a blue pigment having a spectral reflectance of 40% or more at the wavelength, an organic black pigment having a spectral reflectance of 30% or more at the wavelength, and an inorganic black pigment having a spectral reflectance of 15% or more at the wavelength.

6. The paint composition for a sensing detection object using near-infrared light according to claim 1, wherein the lightness of the formed paint film is 80 or less.

7. The paint composition for a detection object for near-infrared light sensing according to claim 1, wherein the average particle diameter D50 of the extender pigment (D) is 5 μm or more and 40 μm or less.

8. The paint composition for a detection object for near-infrared light sensing according to claim 1, wherein the pigment volume concentration of the extender pigment (D) is 25% by volume or more and 60% by volume or less.

9. A coating film for a detection object for near-infrared light sensing, having a root mean square gradient (Sdq) measured in accordance with ISO 25178 on the surface of 1 or more, and a developed area ratio (Sdr) measured in accordance with ISO 25178 of 40% or more.

10. A coating film for a detection object for near-infrared light sensing formed from the paint composition according to any one of claims 1 to 8.

11. A coating film for a detection object for near-infrared light sensing according to claim 10, having a root mean square gradient (Sdq) measured in accordance with ISO 25178 on the surface of 1 or more, and a developed area ratio (Sdr) measured in accordance with ISO 25178 of 40% or more.

12. A detection object having a coating film formed using the paint composition for a detection object for sensing according to any one of claims 1 to 9.

13. A sensing method for measuring the distance between a vehicle and a detection object, wherein near-infrared light of a specific wavelength is irradiated from a traveling vehicle, reflected by the detection object, the reflected light is detected, and the distance from the vehicle to the detection object is calculated based on the time taken for the reflection, wherein the detection object is obtained by coating with the paint composition according to any one of claims 1 to 9.

14. A sensing method for measuring the distance between a vehicle and a detection object, wherein near-infrared light of a specific wavelength is irradiated from a traveling vehicle, reflected by the detection object, the reflected light is detected, and the distance from the vehicle to the detection object is calculated based on the frequency difference between the irradiated light and the reflected light, wherein the detection object is obtained by coating with the paint composition according to any one of claims 1 to 9.

15. Applying a first coating composition onto a road surface to obtain a coating film, and drying the coating film to obtain a coating film for a detection object of sensing using near-infrared light, the method for manufacturing a coating film comprising: the first coating composition includes a film-forming resin (A), a coloring pigment (B), and an extender pigment (D); the coloring pigment (B) is at least one selected from the group consisting of a white pigment having a near-infrared reflectance of 60% or more, a colored pigment having a near-infrared reflectance of 50% or more, and a black pigment having a near-infrared reflectance of 30% or more when the reflectance in the wavelength range of 800 to 2,500 nm is defined as the near-infrared reflectance; and the extender pigment (D) includes one or more selected from carbonate (D1) and metasilicate (D2).

16. The method for manufacturing a coating film according to claim 15, wherein the coating film for a detection object of sensing using near-infrared light has a root mean square gradient (Sdq) measured in accordance with ISO 25178 on the surface of 1 or more and a developed area ratio (Sdr) measured in accordance with ISO 25178 of 40% or more.

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