Coating composition

Abstract

To suppress whitening of a coating film by environment light, especially, light emitted from a direction opposite to an irradiation part of a laser beam and a detection part of reflected light, while maintaining retroreflective ability of an obtained coating film.SOLUTION: A coating composition for a detection object for sensing using near infrared light contains a coating film formation resin (A), a coloring pigment (B) and an extender pigment (D), wherein the coloring pigment (B) contains at least one selected from the group consisting of a white pigment having near infrared light reflectance of 60% or more, a chromatic color pigment having near infrared light reflectance of 50% or more, and a black pigment having near infrared light reflectance of 30% or more, when reflectance at a wavelength of 800 to 2,500 nm is considered to be a near infrared light reflectance, and the extender pigment (D) contains one or more kinds selected from carbonate (D1) and meta silicate (D2).SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a paint composition.

Background Art

[0002] For the purpose of automating and labor-saving transportation, the development of an Automated Guided Vehicle (AGV) system has been underway. An AGV is defined in JIS D 6801 as "a vehicle that automatically travels in a certain area and has a function of transporting goods other than people such as loads, and is not used on roads defined by the Road Traffic Law." AGVs are classified into three types: a path guidance type in which vehicle position control is performed by some guidance means by an automatic driving method, an autonomous mobile type in which the vehicle itself has a self-position estimation function and a travel control function, and a following type that moves in a form of following a preceding person or vehicle.

[0003] Patent Document 1 describes a cooperative guidance system including a processor that paints a road surface with a paint containing a crystalline rare earth phosphor capable of converting light into electromagnetic energy, irradiates the painted surface with light, senses the generated electromagnetic energy, and converts it into a processing signal to determine the operating characteristics of a vehicle or the characteristics of a road surface.

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

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

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the path guidance type, typically, position control of a vehicle is performed by using magnetism, electromagnetic induction, light reflection, etc. Among them, an induction method using light reflection, which is easy to set and change a path, has attracted attention. In the induction method using light reflection, in order to perform accurate position recognition, it is required to accurately recognize the reflected light from a specific irradiation target such as a marker. Therefore, it is desirable that such a specific irradiation target exhibits retroreflectivity (the property of reflecting light in the same direction as the incident direction).

[0008] In the autonomous mobile type, LiDAR (Laser Imaging Detection and Ranging) technology is used to estimate its own position. LiDAR is one of the remote sensing technologies using light, which irradiates an object such as a road surface with near-infrared light, visible light, and / or ultraviolet light, and measures the light reflected and / or scattered by the object, thereby detecting the distance and azimuth from the irradiation position to the object.

[0009] LiDAR is widely used not only in AGVs but also in automotive autonomous driving technology, electronic devices, and various industries. Even when applying LiDAR technology to AGVs and autonomous driving technology, it is desirable that an object such as a road surface exhibits retroreflectivity in order to ensure its visibility. Particularly in AGVs and autonomous driving, it is assumed that laser light is irradiated onto a road surface at a long distance from the vehicle and the reflected light is detected. Therefore, it is necessary to be able to cope even when the incident angle becomes a high angle. In the case of a low incident angle, since the difference between the incident angle and its reflection angle is small, retroreflectivity can be relatively easily exhibited. However, in the case of a high incident angle, since it is necessary to reflect light in a direction significantly different from normal total reflection, it becomes difficult to exhibit retroreflectivity. Note that the incident angle refers to the angle from the normal line erected on the reflection surface.

[0010] On the other hand, on the road surface or the like to be detected, in addition to the LiDAR visibility of the object, in order to prevent misrecognition with existing white lines or the like, it is necessary for the object to be a dark color (also referred to as low brightness) of the same system as the road surface. That is, as the object, it is required to have low brightness with respect to light in the visible light region, be able to reflect and / or scatter with high intensity with respect to light in the near-infrared region, and have retroreflectivity.

[0011] Examples of such means include a method of applying a paint composition containing glass beads, a method of applying a paint composition prepared by color matching using a coloring pigment with high reflection intensity in the near-infrared region, and the like. However, in certain embodiments, it has been found that when strong light such as sunlight or the headlight of an automobile is irradiated from the opposite direction of the laser light irradiation part and the reflected light detection part, there is a risk of misrecognition with the white line (hereinafter, also referred to as "whitening of the coating film").

[0012] The present disclosure has been made in view of such circumstances, and an object thereof is to suppress whitening of the coating film due to ambient light, particularly light irradiated from the opposite direction of the laser light irradiation part and the reflected light detection part, while maintaining the retroreflectivity in the obtained coating film.

Means for Solving the Problems

[0013] [1] A paint composition for a sensing detection object using near-infrared light, comprising a coating film-forming resin (A), a coloring pigment (B), and an extender pigment (D), wherein the coloring pigment (B) includes 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). [2] In the surface of the formed coating 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. The paint composition for a detection object of sensing using near-infrared light according to [1]. [3] The paint composition for a detection object of sensing using near-infrared light according to [1] or [2], wherein the colored pigment contains at least one selected from the group consisting of red pigments, yellow pigments, and blue pigments. [4] The paint composition for a detection object of sensing using near-infrared light according to any one of [1] to [3], wherein the red pigment and the yellow pigment each contain an organic pigment and / or an inorganic pigment. [5] The colored pigment (B) is 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 The paint composition for a detection object of sensing using near-infrared light according to any one of [1] to [4], which contains at least one selected from the group consisting of them. [6] The paint composition for a detection object of sensing using near-infrared light according to any one of [1] to [5], wherein the lightness of the formed coating film is 80 or less. [7] The coating composition for a detection object of 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] The coating composition for a detection object of sensing using near-infrared light according to any one of [1] to [7], wherein the volume pigment concentration of the extender pigment (D) is 35% by volume or more and 60% by volume or less. [9] A coating film for a detection object of sensing using near-infrared light, wherein the root mean square gradient (Sdq) measured in accordance with ISO25178 on the surface is 1 or more, and the developed area ratio (Sdr) measured in accordance with ISO25178 is 40% or more.

[10] A coating film for a detection object of 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 object of sensing using near-infrared light according to

[10] , wherein the root mean square gradient (Sdq) measured in accordance with ISO25178 on the surface is 1 or more, and the developed area ratio (Sdr) measured in accordance with ISO25178 is 40% or more.

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

[13] In 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, the coating is obtained by coating 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, which irradiates near-infrared light of a specific wavelength from a moving vehicle, the light is 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 coating is obtained by coating the paint composition described in any one of [1] to [9].

[15] Applying a first paint composition on a road surface to obtain a coating film, and Drying the coating film to obtain a coating film for a detection object for sensing using near-infrared light, The first paint composition contains a film-forming resin (A), a coloring pigment (B), and an extender pigment (D), the coloring pigment (B) includes 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, the extender pigment (D) includes one or more selected from carbonate (D1) and metasilicate (D2), a method for manufacturing a coating film.

[16] The coating film for a detection object for sensing using the near-infrared light has a root mean square gradient (Sdq) measured in accordance with ISO25178 on the surface of 1 or more, and a developed area ratio (Sdr) measured in accordance with ISO25178 of 40% or more, the method for manufacturing a coating film according to

[15] . [Advantages of the Invention]

[0014] The coating film of the present disclosure can suppress the whitening of the coating film caused by ambient light, particularly light irradiated from the reverse direction of the irradiation part and the reflected light detection part of laser light, while maintaining retroreflectivity. [Embodiments for Carrying Out the Invention]

[0015] The paint composition for a detection target object using near-infrared light according to the present disclosure contains a film-forming resin (A), a coloring pigment (B), and an extender pigment (D). When the reflectance in the wavelength range of 800 to 2,500 nm is defined as the near-infrared reflectance, the coloring pigment (B) contains 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. The extender pigment (D) contains one or more selected from carbonate (D1) and metasilicate (D2).

[0016] According to the paint composition of the present disclosure, while maintaining the retroreflectivity (LiDAR visibility), it is possible to suppress the whitening of the paint film due to ambient light, particularly light irradiated from the reverse direction of the irradiation part of the laser light and the detection part of the reflected light. Although the present disclosure should not be construed as being limited to a specific theory, the reason why the paint composition of the present disclosure exhibits such an effect is considered as follows. That is, the paint composition of the present disclosure contains a coloring pigment that exhibits a reflectance of a certain level or more in the wavelength range of 800 to 2,500 nm, and further contains an extender pigment selected from carbonate (D1) and metasilicate (D2). Therefore, the infrared reflectance is maintained and the retroreflectivity (LiDAR visibility) is maintained. On the other hand, the surface unevenness of the obtained paint film can become steep, and the ambient light incident on the paint film can be attenuated by repeatedly reflecting and absorbing inside the unevenness, resulting in reducing the reflected light going outside. As a result, it is considered that while maintaining the retroreflectivity (LiDAR visibility), it is possible to suppress the whitening of the paint film due to ambient light, particularly light irradiated from the reverse direction of the irradiation part of the laser light and the detection part of the reflected light. In the present disclosure, "ambient light" means light that can enter the object, such as sunlight, and does not participate in LiDAR sensing.

[0017] (A) Film-forming resin The coating film-forming resin (A) is a resin capable of forming a coating film, and resins commonly used in the paint field can be used. Examples of the coating film-forming resin (A) include thermosetting resins, room temperature curable resins, or photocurable resins such as acrylic resins, polyester resins, polyurethane resins, alkyd resins, polyether resins, fluorine resins, epoxy resins, silicone resins, or urea resins, and preferably include one or more selected from acrylic resins, polyester resins, polyurethane resins, and urea resins. Further, the coating film-forming resin (A) may form a coating film alone, or may form a coating film by the action of a crosslinking agent (C) described later. As the coating film-forming resin (A), one type may be used, or two or more types may be used in combination.

[0018] The acrylic resin represents a polymer having units derived from monomers 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 monomers having an ethylenic 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; alkyl (meth)acrylates having a linear or branched alkyl group having 1 to 20 carbon atoms; (meth)hydroxymethyl acrylate, (meth)hydroxyethyl acrylate, (meth)hydroxypropyl acrylate, (meth)hydroxybutyl acrylate, (meth)acrylic monomers having a hydroxy group such as N-methylol(meth)acrylamide; lactone adducts of the (meth)acrylic monomers having a hydroxy group; (meth)acrylonitrile; and the like.

[0020] Examples of the monomer having an ethylenically unsaturated group include, in addition to the monomer having the (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; vinyl monomers such as styrene; and the like.

[0021] The polyester resin represents 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 polymer of a cyclic ester; a reaction product of the reaction product of the polyol and the polycarboxylic acid and a cyclic ester; and the like.

[0022] The polyol is a compound having two or more hydroxy groups in one molecule. For example, 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; polyols having three or more functional groups such as glycerin, mannitol, trimethylolethane, trimethylolpropane, trimethylolbutane, hexanetriol, pentaerythritol, and dipentaerythritol; sugar alcohols such as sorbitol; tris(hydroxyethyl)isocyanate; N,N-bis(2-hydroxyethyl)dimethylhydantoin; and the like.

[0023] The hydroxy groups contained in the polyol are preferably two or more, may be three or more, preferably six or less, and more preferably four or less in one molecule.

[0024] As the polyol, one kind may be used, or two or more kinds may be used in combination.

[0025] The polycarboxylic acid means 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 dodecenyl succinic acid; hydroxy acids of lactose; anhydrides of the aromatic polycarboxylic acids, the alicyclic polycarboxylic acids, and the aliphatic polycarboxylic acids; and the like. As the polycarboxylic acid, one kind may be used, or two or more kinds may be used in combination.

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

[0027] The polyester resin includes modified products of the above-described polyester resin. The modification of the resin can be carried out by reacting a modifier with the terminal of the main chain constituting the resin. Examples of the modifier include reactive groups such as isocyanate groups, hydroxy groups, and carboxy groups, and compounds having a silicone skeleton or the like. Examples of the modified product of the polyester resin include urethane-modified polyester resin, epoxy-modified polyester resin, acrylic-modified polyester resin, and silicone-modified polyester resin.

[0028] Examples of the urethane resin include reaction products of a polyol and a polyisocyanate; reaction products of the reaction product and a chain extender used as necessary; 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, 1,6-hexanediol; alicyclic polyols such as hydrogenated bisphenol A, 1,4-cyclohexanedimethanol; aromatic polyols such as bisphenol A, hydroxyalkylated bisphenol A (especially bisphenol hydroxypropyl ether); polyols having three or more functional groups such as glycerin, anitol, trimethylolethane, trimethylolpropane, trimethylolbutane, hexanetriol, pentaerythritol, dipentaerythritol; high molecular weight polyols such as polyether polyol, acrylic polyol, polyurethane polyol, polyester polyol, polyester amide polyol (for example, a polyol having a weight average molecular weight of 800 or more), and the like.

[0030] As the polyol, one kind may be used, or two or more kinds may be used in combination.

[0031] The number of hydroxy groups contained in the polyol is two or more, and may be three or more, preferably six or less, more preferably four or less.

[0032] The polyisocyanate means 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; aromatic polyisocyanates such as 1,4-tolylene diisocyanate, 1,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, metaxylylene diisocyanate, naphthylene diisocyanate, and 3,3'-dimethyl-4,4'-biphenylene diisocyanate; and multimers such as biuret bodies, isocyanurate bodies, uretdine bodies, and allophanate bodies of the aliphatic polyisocyanate, alicyclic polyisocyanate, and aromatic polyisocyanate. As the polyisocyanate, one kind may be used, or two or more kinds may be used in combination.

[0033] The chain extender means a compound having one or more active hydrogen atoms in one molecule, and water or an amine compound can be used. 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, as the urethane resin, an ester-based urethane resin, an ether-based urethane resin, and a carbonate-based urethane resin can be used.

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

[0036] Examples of the urea resin include reaction products of polyamine compounds and polyisocyanate compounds. The polyamine compound and the polyisocyanate compound may be a two-component type paint composition in which each is separately blended.

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

[0038] The amino group is preferably a primary or secondary amino group. In one aspect, the amino group may be present in the molecular chain of the polyamine compound or at the molecular terminal. The polyamine compound is, for example, R 12 HN-R 11 -NHR 12 (wherein R 11 represents a divalent C 1-30 hydrocarbon group, and -CH2- contained in R 11 may be substituted with -O-, -CO-, or -NR 12 -, and R 12 represents a monovalent C 1-30 hydrocarbon group or a hydrogen atom.) and can be represented by. The C1-30 As the hydrocarbon group, C 1-30 an aliphatic hydrocarbon group, C 3-30 a cycloaliphatic hydrocarbon group, and C 6-30 an aromatic hydrocarbon group can be mentioned.

[0039] The aliphatic polyamine compound means a polyamine compound having no ring structure in its molecular structure. Examples of such aliphatic polyamine compounds include alkylene polyamine compounds, polyalkylene polyamine compounds, and other aliphatic polyamine compounds.

[0040] Examples of alkylene polyamine compounds include methylenediamine, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, and the like.

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

[0042] Examples of other aliphatic polyamine compounds include tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, triethylene-bis(trimethylene)hexamine, bis(3-aminoethyl)amine, bishexamethylenetriamine, aspartic acid ester amine represented by the following formula (11), and the like.

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

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

[0045] The aromatic polyamine compound means a polyamine compound having an aromatic ring in its molecular structure. Examples of the aromatic polyamine compound 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, polytetramethylene oxide-di-p-aminobenzoate, and the like.

[0046] In one aspect, the polyamine compound may contain an aspartic acid ester amine represented by the following formula (I).

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

[0048] As the polyamine compound, one kind may be used alone, or two or more kinds may be used in combination.

[0049] The polyisocyanate means 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; aromatic polyisocyanates such as 1,4-tolylene diisocyanate, 1,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, metaxylylene diisocyanate, naphthylene diisocyanate, and 3,3'-dimethyl-4,4'-biphenylene diisocyanate; and multimers such as biuret bodies, isocyanurate bodies, uretdine bodies, and allophanate bodies of the aliphatic polyisocyanate, alicyclic polyisocyanate, and aromatic polyisocyanate. As the polyisocyanate, one kind may be used, or two or more kinds may be used in combination.

[0050] The equivalent ratio of the isocyanate groups of the polyisocyanate compound to the amino groups of the polyamine compound (for example, in the case of a secondary amine, NCO / NH2) is preferably 0.5 to 2.0, more preferably 0.8 to 1.2. The amino groups used in the calculation of the above equivalent ratio refer to the amino groups involved in the reaction with the polyisocyanate (for example, the amino groups present at the molecular terminals). When the equivalent ratio is within the above range, there is an advantage that the water resistance of the formed coating film becomes good.

[0051] The coating film-forming resin (A) may have hydrophilic groups such as anionic groups, cationic groups, and nonionic groups. 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 of the coating film-forming resin (A) or the like.

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

[0055] The coating film-forming resin (A) may have a hydroxy group. When the coating film-forming resin (A) has a hydroxy group, the hydroxyl value of the coating film-forming resin (A) is preferably 5 mgKOH / g or more and 35 mgKOH / g or less, more preferably 7 mgKOH / g or more and 30 mgKOH / g or less, still more preferably 10 mgKOH / g or more and 25 mgKOH / g or less.

[0056] Both the acid value and the hydroxyl value are based on the solid content and can be measured in accordance with JIS K 0070:1999. Further, the amine value is based on the 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 described later, or may be an aqueous resin. Examples of the aqueous resin include a water-soluble resin that can be dissolved in an aqueous medium; a water-dispersible resin that can be dispersed in an aqueous medium such as a colloidal dispersion type, an emulsion type (emulsion polymerization type, forced emulsification type), etc.

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

[0059] In the case of the emulsion type water-dispersible resin, the weight average molecular weight of the coating film-forming resin (A) 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 a resin that can be dissolved in the aqueous medium or the organic solvent, it 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 obtained by converting the measured value by gel permeation chromatography into polystyrene equivalent.

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

[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 coating film-forming resin (A) may contain an acrylic resin aqueous dispersion (A1). The glass transition temperature (Tg) of the acrylic resin aqueous dispersion (A1) may preferably be -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. 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, still more preferably 10 mgKOH / g or more and 70 mgKOH / g or less. When the hydroxyl value of the acrylic resin is within the above range, there are 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. When the acid value of the acrylic resin is within the above range, there are advantages such as good water resistance and freeze-thaw resistance of the resulting coating composition. In the present disclosure, both the acid value and the hydroxyl value indicate values on a solid content basis and are values measured by a method conforming to 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, still more preferably 15% by mass or more and 40% by mass or less in 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 obtained by removing the solvent (D) described later from all the components of the coating composition.

[0069] In a range that does not affect the physical properties of the formed coating film, a thermoplastic resin can also be used in addition to the film-forming resin (A). Examples of the thermoplastic resin include chlorinated olefin resins such as chlorinated polyethylene and chlorinated polypropylene; homopolymers or copolymers having monomers such as vinyl chloride, vinyl acetate, and vinylidene chloride as monomer components; cellulose resins; acetal resins; alkyd resins; chlorinated rubber resins; modified polypropylene resins (such as acid anhydride-modified polypropylene resins); fluorine resins (for example, vinylidene fluoride resins, vinyl fluoride resins, copolymers of fluorinated olefins and vinyl ethers, copolymers of fluorinated olefins and vinyl esters), etc. The thermoplastic resin may be used alone or in combination of two or more. By using the thermoplastic resin in combination, it becomes easy to adjust the physical properties of the formed coating film according to the purpose.

[0070] (B) Coloring pigment The coloring pigment (B) is a pigment having colors such as chromatic colors and achromatic colors, 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, still more preferably 20% or more, and it is also acceptable that it is 100% or less, 90% or less, or 80% or less. By including the pigment (B1), when irradiated with near-infrared rays, the irradiated light is reflected and / or scattered at high intensity, which can contribute to improving the detection accuracy in LiDAR technology.

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

[0072] In the present disclosure, the near-infrared reflectance of the pigment can be measured as the reflectance of a coating film containing the pigment. Specifically, the pigment, resin, and solvent described in Measurement Example 1 of the near-infrared reflectance and spectral reflectance of the pigment to be described later 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 dispersed using a disperser at a rotation speed of 1,800 rpm for 60 minutes to obtain a dispersion. Then, a black-and-white hiding power test paper (manufactured by Nippon Test Panel Co., Ltd.) is used as the base, and using an 8-mil doctor blade, it is applied so that the thickness after drying is about 50 μm, and dried at 60°C for 20 minutes to obtain a dried coating film. In accordance with JIS K 5602:2008, using a spectrophotometer, the spectral reflectance of the white part of the base of the dried coating film is measured in the wavelength range of 800 to 2,500 nm, and the arithmetic mean value thereof is taken as the near-infrared reflectance of the pigment. Also, the spectral reflectance at wavelengths 905 nm and 1,550 nm to be described later can be measured in accordance with the method for measuring the above spectral reflectance. As the spectrophotometer, for example, it can be measured using a spectrophotometer (manufactured by Shimadzu Corporation, SHIMADZU-UV3600, etc.). Pigment mass concentration (PWC: mass%) = (solid content of pigment) / (solid content of pigment + solid content of resin) × 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) described later used as necessary, and can be determined by measuring the heat residue (the mass of the residue after heating at 105°C for 60 minutes) in accordance with JIS K 5601-1-2 (2008).

[0074] Further, when measuring the near-infrared reflectance and the spectral reflectance, the pigment mass concentration of each of the pigments shall be equal to or higher than the concentration at which the underlying white and black 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 concentration of each of the pigments is 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 contains a pigment selected from the group consisting of colored pigments and achromatic pigments. The colored pigments include all pigments having a chroma exceeding 0, and examples thereof include red pigments, green pigments, blue pigments, yellow pigments, etc., and preferably contain one or more selected from the group consisting of red pigments, blue pigments, and yellow pigments.

[0076] Further, as the pigment (B1), an organic pigment and / or an inorganic pigment can be used. The organic pigment tends to have a high chroma and a high near-infrared reflectance, and the inorganic pigment tends to have high weather resistance.

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

[0078] In the total 100% by mass of the pigment (B1), the content of the inorganic pigment may be 0% by mass or more and 100% by mass or less, may be 5% by mass or more and 99% by mass or less, may be 10% by mass or more and 95% by mass or less, and may be 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, still more preferably 50% or more, and even more preferably 55% or more, and is, for example, 80% or less, and may even be 70% or less.

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

[0081] As the red pigment, an organic pigment and / or an inorganic pigment can be used. The content of the organic pigment may be 0% by mass in the red pigment, may be 1% by mass or more and 100% by mass or less, and may be 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, still more preferably 50% or more, and even more preferably 55% or more, and is, for example, 80% or less, and may even be 70% or less.

[0083] The spectral reflectance of the organic red pigment at a wavelength of 905 nm and / or 1,550 nm is preferably 40% or more, more preferably 50% or more, still more preferably 55% or more, and even more preferably 60% or more, and is, for example, 90% or less, and may even be 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, for example, 80% or less, and may even be 70% or less.

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

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

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

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

[0089] Examples of the cyan pigment include, for example, Dipyrroxyde Blue #9453 (manufactured by Dainichi Seika Kogyo Co., Ltd.), Fastogen Blue 5485K, Fastogen Blue RSKE, Fastogen Blue CA5380 (all manufactured by DIC Corporation), Cyanine Blue 5240KB (manufactured by Dainichi Seika Kogyo Co., Ltd.), Lionol Blue SPG-8 (manufactured by Toyo Color Co., Ltd.), HELIOGEN BLUE L7460 (manufactured by BASF), Dipyrroxyde Green #9310 (manufactured by Dainichi Seika Kogyo Co., Ltd.), Fastogen Green 2YK (manufactured by DIC Corporation), Lionol Green 6YKP-N (manufactured by Toyo Color Co., Ltd.), and the like.

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

[0091] The spectral reflectance of the yellow pigment at a wavelength of 905 nm and / or 1550 nm is preferably 15% or more, more preferably 20% or more, still more preferably 25% or more, and even more preferably 30% or more. For example, it may be 95% or less, and more preferably 90% or less.

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

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

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

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

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

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

[0098] The colored pigment as the pigment (B1) preferably includes a red pigment, a blue pigment, and a yellow pigment. For example, 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 Toyo Color Co., Ltd.) as a blue pigment can be mentioned.

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

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

[0101] The achromatic pigments include all pigments having a chroma of 0. Examples of the achromatic pigments 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, still more preferably 70% or more, even more preferably 75% by mass or more, and for example, 99% or less, and further 90% or less is also acceptable.

[0103] Examples of the white pigment include TIPAQUE CR-97, TIPAQUE CR-95 (both manufactured by Ishihara Sangyo Co., Ltd.), and Typure R-902 (manufactured by Kemers Co., Ltd.), which are titanium oxides.

[0104] The spectral reflectance of the white pigment at a wavelength of 905 nm and / or 1,550 nm is preferably 60% or more, more preferably 65% or more, still more preferably 70% or more, even more preferably 75% by mass or more, and for example, 99% or less, and further 90% or less is also acceptable.

[0105] The content rate of the white pigment may be, for example, 0 mass% or more, 1 mass% or more, 3 mass% or more in the pigment (B1). Also, it is 100 mass% or less, may be 99 mass% or less, may be 90 mass% or less, for example, may be 80 mass% or less, may be 70 mass% or less, may be 65 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, still more preferably 10% or more, even more preferably 15% or more, and for example, it is also acceptable that it is 90% or less, further 85% or less.

[0107] The spectral reflectance of the black pigment at a wavelength of 905 nm and / or 1,550 nm is preferably 5% or more, more preferably 8% or more, still more preferably 10% or more, even more preferably 15% or more, and for example, it is also acceptable that it is 90% or less, further 85% or less.

[0108] As the black pigment, an organic pigment and / or an inorganic pigment can be used. The content rate of the organic pigment may be 0 mass% in the black pigment, may be 1 mass% or more, may be 20 mass% or more, and may also be 50 mass% or less, and the upper limit is 100 mass%.

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

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

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

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

[0113] Examples of the black pigment include, as the inorganic black pigment, Di pyro xide Black #9590, Di pyro xide Brown #9290, Di pyro xide Brown #9211 (all manufactured by Dainichi Seika Kogyo Co., Ltd.), Black 411A (manufactured by The Shepherd Color Company), Black 6350N (manufactured by Asahi Kasei Chemicals Corporation), and as the organic black pigment, Chromophine Black A-1103 (manufactured by Dainichi Seika Kogyo Co., Ltd.), Fastogen Super Black MX (manufactured by DIC Corporation), Parioxene Black S0084, Parioxol Black L0080 (all manufactured by BASF SE), Hostaperm Brown HFR-01 (manufactured by Clariant Japan K.K.), and the like.

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

[0115] The total content of the white pigment and the black pigment is, for example, 50% by mass or more, preferably 60% by mass or more in the achromatic pigment, and the upper limit is 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 with respect to 100 parts by mass of the chromatic pigment. Also, for example, it may be 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] As the pigment (B1), one kind may be used, or two or more kinds may be used in combination.

[0118] In one embodiment, the pigment (B1) contains at least one 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 the pigment (B1) containing these pigments, it is possible to improve the detection accuracy of near-infrared rays in the LiDAR technology of the obtained coating film, and preferably, it is possible to improve the detection accuracy of near-infrared rays in the LiDAR technology while having a low lightness.

[0119] The pigment (B1) preferably contains 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; more preferably, it 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, a blue pigment having a spectral reflectance of 40% 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 a wavelength of 905 nm and / or 1,550 nm, an inorganic red pigment having a spectral reflectance of 20% or more at a wavelength of 905 nm and / or 1,550 nm, an organic yellow pigment having a spectral reflectance of 60% or more at a wavelength of 905 nm and / or 1,550 nm, an inorganic yellow pigment having a spectral reflectance of 20% or more at a wavelength of 905 nm and / or 1,550 nm, an organic black pigment having a spectral reflectance of 50% or more at a wavelength of 905 nm and / or 1,550 nm, and an inorganic black pigment having a spectral reflectance of 15% or more at a wavelength of 905 nm and / or 1,550 nm.

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

[0121] The coloring pigment (B) may contain a coloring pigment (b) other than the pigment (B1) as long as it does not affect the near-infrared reflectance and spectral reflectance of the coating film obtained from the coating composition. As the coloring pigment (b), any of the compounds classified as pigments in the Color Index other than the pigment (B1) can be used. Examples of the coloring pigment (b) include organic black pigments, such as carbon black. The content (pigment mass concentration) of the coloring pigment (b) may be 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less in the coloring pigment (B).

[0122] The average primary particle diameter (D50) of the coloring pigment (B) is 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 coloring pigment (B) can be measured using a laser Doppler particle size analyzer (e.g., Microtrac UPA150 manufactured by Nikkiso Co., Ltd., etc.).

[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 in the total 100% by mass of the pigment (B).

[0124] Also, 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 in the total 100% by mass of the pigment (B).

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

[0126] The content ratio (pigment mass concentration) of the pigment (B1) is preferably 3% by mass or more, more preferably 8% by mass or more, and 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 film-forming resin (A), the pigment (B), and a cross-linking agent (C) described later 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. Also, for example, it may be 70 or less and may be 15 or more. By using the coating composition of the present invention, even when the lightness (L* value) of the coating film is low, the visibility in LiDAR technology can be maintained. 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 lightness of the coating film can be measured in the same manner as the lightness of the coating film containing the pigment. Specifically, the pigment, resin, and solvent described in Measurement Example 1 of the near-infrared reflectance and spectral reflectance of the pigment described later are mixed so that the pigment mass concentration is 3 to 45% by mass, and dispersed using a disperser at a rotation speed of 1,800 rpm for 60 minutes to obtain a dispersion. Then, a black and white hiding power test paper (manufactured by Nippon Test Panel Co., Ltd.) is used as a base, and it is applied so that the thickness after drying is about 100 μm, and dried at 60°C for 20 minutes to obtain a dried coating film. For the obtained coating film, the lightness of the white part of the base of the dried coating film obtained in accordance with 3.2 of JIS K 5600-4-4 and JIS K 5600-4-5 is measured, and the lightness can be used as the above-mentioned lightness. The lightness can be measured, for example, using a color difference meter CR-400 (manufactured by Konica Minolta).

[0129] When the target lightness of the coating film is L*0, the relationship between the range of L*0 and the pigment mass concentration of each pigment 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. Also, L*0 can take a value within the range described above as the lightness of the coating film. L*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 … Equation (1)

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

[0131] When the near-infrared reflectance of the target coating film is X0 (%), the relationship between the X0 (%) and the pigment mass concentration of each pigment is expressed by the following equation. That is, the pigment mass concentration of each pigment may be in a range that satisfies the following equation. Also, X0 (%) can take values within the range described above as the near-infrared reflectance of the coating film. X0 = 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 … Equation (2)

[0132] When the spectral reflectance of the target coating film at a wavelength of 905 nm is Y0 (%), the relationship between the Y0 (%) and the pigment mass concentration of each pigment is expressed by the following equation. That is, the pigment mass concentration of each pigment may be in a range that satisfies the following equation. Also, Y0 (%) can take values within the range described above as the spectral reflectance of the coating film at a wavelength of 905 nm. Y0 = 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 … Equation (3)

[0133] When the spectral reflectance of the target coating film at a wavelength of 1,550 nm is Z0 (%), the relationship between the Z0 (%) and the pigment mass concentration of each pigment is represented by the following formula. That is, the pigment mass concentration of each pigment may be in a range that satisfies the following formula. Also, Z0 (%) can take a value within the range described above as the spectral reflectance of the coating film at a wavelength of 1,550 nm. Z0 = 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 … Equation (4)

[0134] The lightness of the coating film may be 80 or less. Combinations of the respective pigment mass concentrations in that case are variously calculated by Equation (1). Among those combinations, combinations of pigment concentrations that make the near-infrared reflectance, the spectral reflectance at a wavelength of 905 nm, and the spectral reflectance at a wavelength of 1,550 nm equal to or higher than a desired value (for example, 15% or higher) can be calculated by Equations (2) to (4).

[0135] (C) Crosslinking agent In addition to the coating film-forming resin (A) and the pigment (B), the coating composition may contain a crosslinking agent (C). The crosslinking agent (C) is a compound that can form a crosslinked structure in the coating film-forming resin (A) by forming a chemical bond and / or a physical bond, and examples thereof include a compound having two or more groups having an active hydrogen atom such as a hydroxy group, a carboxy group, and an amino group in one molecule; or a compound having two or more groups capable of reacting with the group having an active hydrogen atom in one molecule; and the like. When the coating film-forming resin (A) has a group having an active hydrogen atom or a group capable of reacting with the group having an active hydrogen atom, a crosslinked structure can be formed in the coating film-forming resin (A) by reacting with the crosslinking agent (C).

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

[0137] The polyisocyanate compound means 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, xylylene diisocyanate; alicyclic polyisocyanates such as dicyclohexylmethane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate and the like.

[0138] The blocked polyisocyanate compound (hereinafter sometimes referred to as "BI") means a compound obtained by blocking the isocyanate groups of the isocyanate compound with a blocking agent.

[0139] The blocking agent may be any compound having an active hydrogen-containing compound. For example, phenol 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, 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 monoxime, benzophenone oxime, and cyclohexanone oxime; active methylene compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, and acetylacetone can be used. By mixing the polyisocyanate compound and the blocking agent, the free isocyanate groups of the polyisocyanate compound can be blocked.

[0140] The amino resin means a resin obtained by addition polymerization of an aldehyde to a compound having an amino group. The amino resin is excellent in crosslinking reactivity with the film-forming resin (A), and is particularly excellent in crosslinking reactivity with the film-forming resin (A) even without a catalyst, which is preferable.

[0141] Examples of the amino resin include melamine resin, urea resin, etc., and melamine resin is preferable.

[0142] The melamine resin means a thermosetting resin synthesized from melamine and an aldehyde. The melamine resin has a triazine nucleus and three reactive functional groups (-NX1X2) per triazine nucleus. Examples of the melamine resin include a fully alkylated type containing only -N(CH2OR)2 [R represents an alkyl group having 1 to 8 carbon atoms, the same applies hereinafter] as a reactive functional group; a methylol group type containing -N(CH2OR)(CH2OH) as a reactive functional group; an imino group type containing -N(CH2OR)(H) as a reactive functional group; and a methylol / imino group type containing -N(CH2OR)(CH2OH) and -N(CH2OR)(H), or containing -N(CH2OH)(H). As the melamine resin, one kind may be used, or two or more kinds may be used in combination. The melamine resin and the polyisocyanate compound may be used in combination as the crosslinking agent (C). Further, if necessary, a metal catalyst such as a tin compound or a titanium compound may be used.

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

[0144] The polycarboxylic acid means 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 dodecenyl succinic acid; hydroxy acids of lactose; anhydrides of the aromatic polycarboxylic acids, the alicyclic polycarboxylic acids, and the aliphatic polycarboxylic acids; and the like.

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

[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 in a total of 100 parts by mass of the film-forming resin (A) and the crosslinking agent (C). Also, for example, it may be 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 ratio 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, still more preferably 15% by mass or more, and preferably 70% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less in the solid content of the coating composition.

[0148] (D) Extender pigment The paint composition of the present disclosure contains an extender pigment (D). In the present disclosure, the extender pigment means a pigment other than a coloring pigment and is intended for increasing the volume and reinforcing the paint composition. In one aspect, the extender pigment (D) can be a pigment with little contribution to coloring, and the refractive index of the extender pigment (D) with respect to white light can be preferably 1.2 or more and 1.8 or less, more preferably 1.3 or more and 1.7 or less at 25°C.

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

[0150] The carbonate (D1) preferably contains, for example, a metal carbonate, and more preferably contains at least one selected from the group consisting of alkali metal carbonates such as calcium carbonate, magnesium carbonate, dolomite (CaMg(CO3)2); transition metal carbonates such as iron(II) carbonate. In one aspect, the carbonate is calcium carbonate. The calcium carbonate preferably contains either heavy calcium carbonate or light calcium carbonate, and more preferably contains 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 still 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 of the obtained paint film and the LiDAR recognition performance are good.

[0152] The average particle size (D50) in the present disclosure is the average particle size determined by the laser diffraction / scattering method. Specifically, it can be measured using a laser diffraction / scattering type particle size distribution measuring device such as the Microtrac MT3000II series (manufactured by Microtrac).

[0153] As the calcium carbonate, commercially available products may be used. Examples of such commercially available products include heavy calcium carbonate, R-30, R-50A, 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, still more preferably 90 parts by mass or more and 400 parts by mass or less, based on 100 parts by mass in total of the solid content of the film-forming resin (A) and the crosslinking agent (C) used as necessary. By the content of the carbonate (D1) being within the above range, it becomes possible to easily suppress the whitening of the coating film due to ambient light, particularly light irradiated from the reverse direction of the irradiation part of laser light and the detection part of reflected light, while maintaining the retroreflectivity (LiDAR visibility).

[0155] The metasilicate (D2) is a salt of metasilicic acid (H2SiO3). The metasilicate (D2) typically includes metal salts of metasilicic acid, and preferably may include alkaline earth metal salts of metasilicic acid. Specific examples of the metasilicate include magnesium metasilicate, calcium metasilicate, strontium metasilicate, barium metasilicate, and the like.

[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, still more preferably 25 μm or more and 40 μm or less. By the average particle diameter of the metasilicate (D2) being within the above range, there is an advantage that the whitening of the coating film due to ambient light, particularly light irradiated from the reverse direction of the irradiation part of laser light and the detection part of reflected light, can be suppressed while maintaining the retroreflectivity (LiDAR visibility).

[0157] As the metasilicate (D2), commercially available products may be used. Examples of such commercially available products include 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, still 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 film-forming resin (A) and the crosslinking agent (C). By the content of the metasilicate (D2) being within the above range, it may be easy to improve the visibility of the coating film by ambient light while maintaining the retroreflectivity (LiDAR visibility).

[0159] In the coating composition of the present disclosure, the total content ratio of the carbonate (D1) and the metasilicate (D2) is 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, still more preferably 90% by mass or more and 100% by mass or less, in 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 more and 40 μm or less, still more preferably 25 μm or more and 40 μm or less. By the average particle diameter being within the above range, there is an advantage that whitening of the coating film by ambient light, particularly light irradiated from the reverse direction of the irradiation part and the detection part of the reflected light of laser light, can be suppressed while maintaining the retroreflectivity (LiDAR visibility).

[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, still 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 film-forming resin (A) and the crosslinking agent (C). By the content of the extender pigment (D) being within the above range, it may be easy to suppress the visibility of the coating film by ambient light while maintaining the retroreflectivity (LiDAR visibility).

[0163] The content of the extender pigment (D) (pigment volume concentration (PVC: % by volume)) is preferably 25% by volume or more and 60% by volume or less, more preferably 40% by volume or more and 60% by volume or less, still more preferably 45% by volume or more and 60% by volume or less, based on 100% by volume of the total solid content of the film-forming resin (A), the crosslinking agent (C), and the extender pigment (D). By the content of the extender pigment (D) (pigment volume concentration) being within the above range, it may be easy to improve the visibility of the coating film by ambient light while maintaining the retroreflectivity (LiDAR visibility). Extender pigment concentration (extender pigment PVC: % by volume) = (solid volume amount of extender pigment) / (solid volume amount of extender pigment + solid volume amount of resin) × 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. By using such a hydrophilic solvent, there is an advantage that the wettability of the resulting coating composition with the substrate is improved.

[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., Ltd.); hydrocarbon solvents such as pentane, iso-pentane, hexane, iso-hexane, and cyclohexane; and mineral oils such as solvent naphtha and mineral spirit. These may be used alone or in combination of two or more.

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

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

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

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

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

[0173] The coating composition can be prepared by dissolving or dispersing the film-forming resin (A), the pigment (B), the extender pigment (D), the crosslinking agent (C) used as necessary, and other additives in the solvent (E) used as necessary. Further, the mixing order of the various materials to be used is not particularly limited. For example, after premixing a part of the pigment (B) and the film-forming resin (A) to form a pigment paste, the remaining components and other components used as necessary may be mixed to produce a coating composition. The coating composition of the present disclosure can be prepared by selecting and using a mixer, a disperser, a kneader, etc., such as a sand grinder, a ball mill, a blender, a paint shaker, or a disper, and mixing the respective components.

[0174] The coating film formed from the coating composition is also included in 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, still more preferably 35% or more, and for example, 99% or less, and even 90% or less is also acceptable.

[0176] The spectral reflectance of the coating film at a wavelength of 905 nm and / or 1,550 nm is preferably 20% or more, more preferably 30% or more, still more preferably 35% or more, and for example, 99% or less, and even 90% or less is also acceptable.

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

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

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

[0180] In the coating film obtained from the coating composition, the lightness (L* value) may be 80 or less, for example, 70 or less. Also, for example, it may be 5 or more, and 15 or more.

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

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

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

[0184] On the surface of the coating film formed by the coating composition of the present disclosure, the root mean square gradient (Sdq) measured in accordance with ISO 25178 is preferably 0.5 or more, more preferably 1 or more, still more preferably 1.3 or more and 2.0 or less, and even more preferably 1.5 or more and 2.0 or less. When the root mean square gradient (Sdq) on the coating film surface is within such a range, environmental light is likely to be attenuated by repeating reflection and absorption in the coating film, and while maintaining retroreflectivity, it becomes easy to suppress whitening of the coating film caused by environmental light, particularly light irradiated from the reverse direction of the irradiation part of laser light and the detection part of reflected light.

[0185] The root mean square gradient (Sdq) is a parameter representing the average magnitude of the local gradient (inclination) of the uneven shape of the surface when measured based on ISO 25178. The larger this Sdq, the steeper the surface, and the Sdq of a completely flat surface is 0.

[0186] On the surface of the coating film formed by the coating composition of the present disclosure, the developed area ratio (Sdr) measured in accordance with ISO 25178 is preferably 40% or more, more preferably 70% or more and 150% or less, still more preferably 85% or more and 150% or less. When the developed area ratio (Sdr) on the coating film surface is within such a range, environmental light is likely to be attenuated by reflection in the coating film, and while maintaining retroreflectivity, it becomes easy to improve the visibility of the coating film by environmental light.

[0187] The developed area ratio (also referred to as "Sdr") is a parameter representing how much the surface area (developed area) reflecting the actual unevenness in the measurement area increases with respect to the area of a flat surface without unevenness in the measurement area when measured based on ISO 25178, and is represented by the following formula. It can be said that the smaller this Sdr, the smoother the surface, and the Sdr of a completely flat surface is 0%.

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

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

[0190] The method for forming a coating film using the coating composition of the present disclosure is also included in the technical scope of the present disclosure. The method for manufacturing the first coating film of the present disclosure is applying the coating composition on 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. including.

[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 still more preferably 30 μm or more and 2,000 μm or less.

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

[0193] Also, the drying temperature when drying the coating film is preferably 0°C or higher and 200°C or lower, more preferably 5°C or higher and 80°C or lower, still more preferably 5°C or higher and 40°C or lower, and preferably 10 minutes or longer and 24 hours or shorter, more preferably 10 minutes or longer and 60 minutes or shorter, still more preferably 10 minutes or longer and 45 minutes or shorter. As the heating means, hot air heating, infrared heating, induction heating, etc. can be adopted.

[0194] In the manufacturing method, although the paint composition is applied on the road surface, it is not limited thereto, and it may be applied to other objects to be coated. Examples of the objects to be coated with the coating film include metal plates, members made of metal plates, plastic members, inorganic material members, wooden members, and paving bodies such as road surfaces.

[0195] Examples of the metal plate include metal plates such as galvanized steel plates, zinc-aluminum alloy plated steel plates, aluminum alloy plated steel plates, molten zinc-aluminum-magnesium alloy plated steel plates, stainless steel plates, and cold-rolled steel plates manufactured by a melting method or an electrolysis method, etc. In addition to these steel plates or plated steel plates, metal plates such as aluminum plates (including aluminum alloy plates) can also be coating targets. The metal plate is preferably surface-treated. Specifically, it is preferable that the metal plate is subjected to a chemical conversion treatment after being subjected to pretreatment such as alkaline degreasing treatment, hot water washing treatment, and water washing treatment. The chemical conversion treatment may be performed by a known method, and examples thereof include non-chromate treatments such as chromate treatment and zinc phosphate treatment. The surface treatment can be appropriately selected according to the steel plate to be used, but a treatment containing no heavy metals is preferable.

[0196] Examples of the plastic member include acrylic plates, polyvinyl chloride plates, polycarbonate plates, ABS plates, polyethylene terephthalate plates, polyolefin plates, etc.

[0197] Examples of the inorganic member include ceramic building materials, glass substrates, etc. described in JIS A 5422, JIS A 5430, etc. Specific examples include silica calcium boards, pulp cement boards, slag gypsum boards, magnesium carbonate boards, asbestos perlite boards, wood chip cement boards, hard wood cement boards, concrete boards, lightweight foamed concrete boards, etc.

[0198] Examples of the wooden member include sawn timber, glued laminated timber, plywood, particle board, fiber board, improved wood, chemically treated wood, floor boards, etc.

[0199] Examples of the pavement such as a road surface include asphalt pavement, concrete pavement, brick pavement, etc.

[0200] Specific examples of the object to be coated include structures and articles that may become obstacles during the automatic driving of a vehicle. For example, various products for sale, roadways, road structures (e.g., pavement, road markings, sidewalks, crosswalks, drainage facilities, flat intersection structures, bridges, earthworks, tunnels, shelters, traffic safety facilities (e.g., overpasses, guardrails, guard poles, protective fences, lighting facilities, line of sight guiding signs, road mirrors, etc.), traffic islands, bus stops, parking strips, parking lots, etc.), various building structures and their internal facilities, railway structures, various protective facilities, various vehicles and their accessories, pedestrian clothing, utility poles, inner walls of various building structures, etc.

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

[0202] For example, in a sensing method for measuring the distance between a vehicle and a painted object, which irradiates near-infrared light of a specific wavelength from a moving vehicle, detects the reflection of the light on the detection target object, and calculates the distance from the vehicle to the painted object detection target based on the time taken for the reflection, (time-of-flight measurement method: ToF (Time-of-Flight)), the painted object can be obtained by painting the paint composition. Also, in a sensing method for measuring the distance between a vehicle and a painted object, which irradiates near-infrared light of a specific wavelength from a moving vehicle, detects the reflection of the light on the detection target object, and calculates the distance from the vehicle to the detection target object based on the change in the frequency difference between the irradiated light and the reflected light, (frequency modulation continuous wave method: FMCW (Frequency Modulated Continuous Wave)), the painted object can be obtained by painting the paint composition.

[0203] Even when the paint composition and the paint film are formed on a road surface, a display that can exhibit high retroreflectivity (particularly, retroreflectivity at a high incident angle) without being misrecognized as a white line can be realized. According to such a display, it is possible to improve the detection accuracy of near-infrared light in LiDAR technology, and preferably, while having a low brightness, it is possible to improve the detection accuracy of near-infrared light in LiDAR technology, particularly the detection accuracy at the incident angle assuming long-distance recognition, and it is useful as a paint and a paint film for a detection target object in sensing using near-infrared light.

Examples

[0204] The present invention will be described more specifically by the following examples, but the present invention is not limited thereto.

[0205] <Example 1 of Measuring Near-Infrared Reflectivity and Spectral Reflectivity of Pigments> Measurement example of near-infrared reflectance of organic red pigments and spectral reflectance at wavelengths 905 nm and / or 1,550 nm As a dispersant, 3.50 parts by mass of SN Dispersant 5027, as an antifoaming agent, 0.5 part by mass of SN Deformer 154, as a solvent, 7.0 parts by mass of (E-1) tap water, and as an organic red pigment, 13.0 parts by mass of (B2-1) FASTOGEN SUPER RED 500RG were mixed. Then, using an SG mill (medium: glass beads), the mixture was dispersed until the maximum particle diameter of the pigment coarse particles became 10 μm or less. Next, 74.0 parts by mass of (A-1) Cybinol YC-102 as a coating film-forming resin and 2.0 parts by mass of (E-1) tap water as a solvent were added, and the mixture was stirred using a disperser to obtain a coating composition (R1-1).

[0206] The coating composition obtained above was applied onto a black-and-white hiding power test paper (manufactured by TP Giken Co., Ltd.) using a 10-mil doctor blade so that the dry film thickness became 50 μm, dried at 60 °C for 20 minutes, and then left standing at room temperature for 1 day to obtain a coating film.

[0207] Regarding the obtained coating film, for the white background part, using a spectrophotometer (manufactured by Shimadzu Corporation, SHIMADZU-UV3600), the reflectance in the wavelength range of 800 to 2,500 nm was measured every 2 nm in accordance with the method specified in JIS K 5602. The arithmetic mean value of the reflectance at each obtained wavelength was defined as the near-infrared reflectance of the inorganic red pigment. Also, the near-infrared reflectances at 905 and 1,550 nm are the values of the respective spectral reflectances at each wavelength.

[0208] For the near-infrared reflectances of other pigments, except that the types of each pigment and the pigment mass concentration were set to the amounts described in Table 1, the near-infrared reflectances and spectral reflectances of each pigment were measured in the same manner as in Measurement Example 1 of the near-infrared reflectance and spectral reflectance of the pigment.

[0209]

Table 1

[0210] Preparation Example 1 of White Pigment Paste 3.5 parts by mass of SN Dispersant 5027 as a dispersant, 0.5 parts by mass of SN Deformer 154 as an antifoaming agent, 14.0 parts by mass of (E-1) tap water as a solvent, and 24.0 parts by mass of (B1-1) TIPAQUE CR-97.0 as a white pigment were mixed, and then dispersed using an SG mill (medium: glass beads) until the maximum particle diameter of the pigment coarse particles became 10 μm or less. Next, 56.0 parts by mass of (A-1) Cymel YC-102 as a film-forming resin and 2.0 parts by mass of (E-1) tap water as a solvent were added, and the mixture was stirred using a stirrer while stirring 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 the respective components were changed as described in Table 2.

[0212]

Table 2

[0213] <Example 1> 8.0 parts by mass of the red pigment paste (R1-1), 14.0 parts by mass of the yellow pigment paste (Y1-1), and 6.0 parts by mass of the blue pigment paste (Bu-1) were mixed while stirring with a stirrer, and 23.4 parts by mass of the film-forming resin (A-1), 4.0 parts by mass of the solvent (E-1), and 45.0 parts by mass of KS-800 (D-1) as an extender pigment were added to the obtained colored pigment paste and mixed at 1,500 rpm for 15 minutes while stirring with a stirrer to prepare Paint Composition 1 shown in Example 1.

[0214] <Preparation Example 1 of a Coating Film (Test Plate)> The paint composition 1 obtained above was applied onto asphalt felt 430 (100 × 150 mm, manufactured by Shizuoka Asphalt Industry Co., Ltd.) using a 20-mil applicator, dried at 60 °C for 20 minutes, and then allowed to stand at room temperature for 1 day to obtain Test Plate 1.

[0215] <Examples 2 to 12> Except for changing the types and amounts of the respective components as shown in Table 3, each coating film (test panel) was obtained in the same manner as in Preparation Example 1 of the coating film.

[0216] Details of each component shown in Table 3 below used in the Examples and Comparative Examples are as follows. Film-forming resin (A) (A-1) Cybinol YC-102 (acrylic styrene resin emulsion, manufactured by Siden Chemical Co., Ltd.): glass transition temperature: -20 °C, acid value: 19 mgKOH / g, hydroxyl value: 0 mgKOH / g, solid content concentration: 50 mass% Extender pigment (D) (D-1) KS-800 (heavy calcium carbonate, manufactured by Calfine Co., Ltd., average particle diameter: 7.8 μm) (D-2) KS-500 (heavy calcium carbonate, manufactured by Calfine Co., Ltd., average particle diameter: 17.7 μm) (D-3) FP-300 (heavy calcium carbonate, manufactured by Calfine Co., Ltd., average particle diameter: 26.7 μm) (D-4) Wollastonite WP200 (wollastonite, manufactured by Nippon Talc Co., Ltd., average particle diameter: 40 μm) (D-5) Wollastonite WP325 (wollastonite, manufactured by Nippon Talc Co., Ltd., average particle diameter: 18 μm) (D-6) Wollastonite WP2500 (wollastonite, manufactured by Nippon Talc Co., Ltd., average particle diameter: 5 μm) (D-7) KS-1300 (heavy calcium carbonate, manufactured by Calfine Co., Ltd., average particle diameter: 3.2 μm) (d-1) GASIL HP395 (silicon dioxide, manufactured by Wilbur Ellis Co., Ltd., average particle diameter: 15 μm) Solvent (E) (E-1) Tap water Other materials Dispersant: SN Dispersant 5027 (special ammonium polycarboxylate, manufactured by Sannopco Co., Ltd.) Defoamer: SN Deformer 154 (mineral oil type, manufactured by Sannopco Co., Ltd.)

[0217] Evaluation items 1) Coating film lightness The lightness (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 Inc.) in accordance with 3.2 of JIS K 5600-4-4 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 every 2 nm using a spectrophotometer (SHIMADZU-UV3600, manufactured by Shimadzu Corporation) in accordance with the method specified in JIS K-5602. The arithmetic mean value of the reflectance at each obtained wavelength was defined as the near-infrared reflectance of the coating film. Also, the near-infrared reflectances at 905 and 1,550 nm are the values of the spectral reflectances at their respective wavelengths.

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

[0220] 4) Visual appearance The test pieces obtained in the examples and comparative examples were placed on an asphalt road surface, and observed visually from a height of 1.2 m at a position 3 m away from the test pieces in the direction facing the sunlight (backlight position) during a time period with a relatively high solar altitude (10 to 14 o'clock), and evaluated according to the following criteria. A score of 3 or more was considered a pass. 6: Appears to be equivalent to the road surface color or slightly darker (low lightness), hardly noticeable. 5: Appears slightly whiter (high lightness) than the road surface color, but hardly noticeable. 4: Appears slightly whiter (high lightness) than the road surface color, but is not misrecognized as a white line. 3: Appears whiter (high lightness) than the road surface color, slightly noticeable, but not misrecognized as a white line. 2: Appears clearly whiter (high lightness) than the road surface color, there is a risk of being misrecognized as a white line. 1: Appears the same as a white line, indistinguishable from a white line.

[0221] 5) LiDAR Recognition Performance Asphalt felt 430 (manufactured by Shizuoka Asphalt Industry Co., Ltd.) was installed at a height of 0.9 m as the test plates and reference plates obtained in the examples and comparative examples. Using LiDAR Mid-40 (manufactured by Livox, wavelength: 905 nm, incident angles: 20° and 80°) from the same height as the test specimens and reference plates and a point 5 m away, the reflectivities at 10 randomly selected locations across the entire test specimens were measured. The arithmetic mean value was taken as the LiDAR reflectivity of the test specimens and reference plates, and the reflectivity of the test specimens relative to that of the reference plate was taken as the LiDAR contrast value and evaluated according to the following criteria. A score of 3 or above was considered a pass. Note that if the LiDAR contrast value is 4 or above when the incident angle is 20° or 2 or above when the incident angle is 80°, the LiDAR wavelength can be detected without problems using a normal LiDAR receiver. When the incident angle is 20°; 5: The LiDAR contrast of the test specimen is 8 or above 4: The LiDAR contrast of the test specimen is 6 or above and less than 8 3: The LiDAR reflectivity of the test specimen is 4 or above and less than 6 2: The LiDAR reflectivity of the test specimen is 2 or above and less than 4 1: The LiDAR reflectivity of the test specimen is less than 2 When the incident angle is 80°; 5: The LiDAR contrast of the test specimen is 4 or above 4: The LiDAR contrast of the test specimen is 3 or above and less than 4 3: The LiDAR reflectivity of the test specimen is 2 or above and less than 3 2: The LiDAR reflectivity of the test specimen is 1 or above and less than 2 1: The LiDAR reflectivity of the test specimen is less than 1

[0222]

Table 3

[0223] Examples 1 to 14 are examples of the present disclosure, and the obtained coating films had good visual appearance and good LiDAR visibility. Comparative Example 1 is an example that does not contain the extender pigment (D). The obtained coating film had good LiDAR visibility, but the visual appearance was not sufficiently satisfactory. Comparative Example 2 is an example that contains silicon dioxide instead of the extender pigment (D), and the coating composition could not be prepared. Comparative Example 3 is an example that does not contain any of a white pigment with a near-infrared reflectance of 60% or more, a colored pigment with a near-infrared reflectance of 50% or more, and a black pigment with a near-infrared reflectance of 30% or more as the coloring pigment (B). The visual appearance of the obtained coating film was good, but the LiDAR visibility was not sufficiently satisfactory.

Industrial Applicability

[0224] 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 irradiation part of laser light and the detection part of reflected light, while maintaining retroreflectivity. Therefore, the coating composition of the present disclosure is widely used not only in AGVs but also in the automatic driving technology of automobiles, electronic devices, and various industries.

Claims

1. A paint composition for a detection object for sensing using near-infrared light, comprising a film-forming resin (A), a coloring pigment (B), and an extender pigment (D), wherein the coloring pigment (B) includes 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).

2. The paint composition for a detection object for sensing using near-infrared light according to claim 1, wherein on the surface of the formed coating 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 detection object for sensing using near-infrared light according to claim 1, wherein the colored pigment includes 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 detection object for sensing using near-infrared light according to claim 1, wherein the red pigment and the yellow pigment each include an organic pigment and / or an inorganic pigment.

5. The coloring pigment (B) is 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 and includes at least one selected from the group consisting of them. The paint composition for a detection object for sensing using near-infrared light according to claim 1.

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

7. The paint composition for a detection object for sensing using near-infrared light 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 sensing using near-infrared light according to claim 1, wherein the volume pigment concentration of the extender pigment (D) is 35% by volume or more and 60% by volume or less.

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

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

11. A coating film for a detection object for sensing using near-infrared light according to claim 10, wherein the root mean square gradient (Sdq) measured in accordance with ISO 25178 on the surface is 1 or more, and the developed area ratio (Sdr) measured in accordance with ISO 25178 is 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. In 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, the coating is obtained by coating the paint composition according to any one of claims 1 to 9.

14. In 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, the coating is obtained by coating the paint composition according to any one of claims 1 to 9.

15. Applying a first paint composition on a road surface to obtain a coating film, and Drying the coating film to obtain a coating film for a detection object for sensing using near-infrared light, wherein the first paint composition contains a film-forming resin (A), a coloring pigment (B), and an extender pigment (D). When the reflectance in the wavelength range of 800 to 2,500 nm of the coloring pigment (B) is defined as the near-infrared reflectance, the coloring pigment (B) contains 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. The method for producing a coating film, wherein the extender pigment (D) contains one or more selected from carbonate (D1) and metasilicate (D2).

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

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