Coating material composition, kit, coating film, and coating film forming method

Abstract

A coating material composition comprising an organic polyisocyanate (A) and an acrylic polyol (B), wherein the organic polyisocyanate (A) includes a modified polyisocyanate (a), the modified polyisocyanate (a) is a reaction product between a polyisocyanate component (a1) and a polyol component (a2), or is a modification product of said reaction product, the polyisocyanate component (a1) includes an organic diisocyanate or a modification product thereof, the polyol component (a2) includes at least one that is selected from the group consisting of polytetramethylene glycols and polycarbonate polyols, and that has a number average molecular weight of 200-750, and the acrylic polyol (B) includes an acrylic polyol (b) that has a glass transition temperature of 5-30°C and that has a hydroxyl value more than 100 mgKOH / g but not more than 150 mgKOH / g.

Description

Coating composition, kit, coating film, and method for forming coating film

[0001] The present disclosure relates to coating compositions, kits, coatings, and methods of forming coatings.

[0002] Hard coating treatments are known to form coating films with excellent scratch resistance, stain resistance, and other properties on the surface of plastic molded products. Hard coating treatments are methods for forming coating films with high crosslink density and surface hardness. However, once a coating film formed by hard coating treatment is scratched, cracks will develop at that location. Furthermore, when hard-coated plastic molded products are used as exterior parts of automobiles, sand, pebbles, and the like collide with the molded product while the automobile is in motion, causing scratches such as minute dents (dents) on the surface (coating surface). While hard coating treatments can avoid the problem of scratches on the coating surface by thickening the coating film, thickening the coating film reduces the design and increases the weight of the exterior part.

[0003] Therefore, instead of hard coating treatments, soft coating treatments have become popular, in which a coating film is formed using a coating composition that has the ability to absorb external forces and repair scratches (hereinafter referred to as "self-repairing properties"). For example, Patent Document 1 discloses a coating composition for soft coating treatments, which contains a polycarbonate diol containing a specific repeating unit and a terminal hydroxyl group, where the specific repeating unit has an average carbon number of 3.0 to 4.0, a polyol other than the polycarbonate diol, and an organic polyisocyanate. Patent Document 1 claims that this coating composition can provide a coating film that combines high scratch repairability and stain resistance.

[0004] JP 2019-137840 A

[0005] However, the coating film made from the coating composition of Patent Document 1 takes a long time to recover from scratches and does not have sufficient stain resistance.

[0006] One aspect of the present disclosure is directed to providing a coating film that has good stain resistance and excellent self-repairing properties against scratches. Another aspect of the present disclosure is directed to providing a coating film that has good smoothness, stain resistance, and adhesion and excellent self-repairing properties against scratches. Another aspect of the present disclosure is directed to providing a coating composition that contributes to the production of the coating film, a kit for preparing the coating composition, and a method for forming the coating film.

[0007] Each aspect of the present disclosure includes the following embodiments [1] to

[11] .

[0008] [1] A coating composition comprising an organic polyisocyanate (A) and an acrylic polyol (B), wherein the organic polyisocyanate (A) comprises a modified polyisocyanate (a), the modified polyisocyanate (a) is a reaction product of a polyisocyanate component (a1) and a polyol component (a2) or a modified product thereof, the polyisocyanate component (a1) comprises an organic diisocyanate or a modified product thereof, the polyol component (a2) comprises at least one member selected from the group consisting of polytetramethylene glycol and polycarbonate polyols having a number average molecular weight of 200 to 750, and the acrylic polyol (B) comprises an acrylic polyol (b) having a glass transition temperature of 5 to 30°C and a hydroxyl value of more than 100 mgKOH / g but not more than 150 mgKOH / g.

[0009] [2] The coating composition according to [1], wherein the average number of functional groups of the modified polyisocyanate (a) is 4.0 to 6.0.

[0010] [3] The coating composition according to [1] or [2], wherein the polyisocyanate component (a1) comprises at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

[0011] [4] The coating composition according to any one of [1] to [3], wherein the modified polyisocyanate (a) includes an allophanate-modified polyisocyanate.

[0012] [5] The coating composition according to [4], wherein the modified polyisocyanate (a) further contains an isocyanurate-modified polyisocyanate.

[0013] [6] The coating composition according to any one of [1] to [5], further comprising a polydimethylsiloxane compound.

[0014] [7] SiO ２ [6] The coating composition according to [6], wherein the silicon content in terms of silicon is 0.001 to 0.1 mass% based on the total amount of the organic polyisocyanate (A), the acrylic polyol (B), and the polydimethylsiloxane compound.

[0015] [8] The coating composition according to any one of [1] to [7], wherein the ratio of the number of moles of isocyanate groups in the isocyanate group-containing compound contained in the coating composition to the number of moles of hydroxyl groups in the hydroxyl group-containing compound contained in the coating composition is 0.8 to 1.3.

[0016] [9] A kit for preparing the coating composition according to any one of [1] to [8], comprising a first agent containing the organic polyisocyanate (A) and a second agent containing the acrylic polyol (B).

[0017]

[10] A coating film comprising a cured product of the coating composition according to any one of [1] to [8].

[0018]

[11] A method for forming a coating film, comprising applying the coating composition according to any one of [1] to [8] onto an adherend and curing it.

[0019] According to one aspect of the present disclosure, it is possible to provide a coating film that has good contamination resistance and excellent self-repairing ability against scratches. Also, according to another aspect of the present disclosure, it is possible to provide a coating film that has good smoothness, contamination resistance, and adhesion, and excellent self-repairing ability against scratches. Furthermore, according to another aspect of the present disclosure, it is possible to provide a coating composition that contributes to the production of the coating film, a kit for preparing the coating composition, and a method for forming the coating film.

[0020] Exemplary embodiments for carrying out each aspect of the present disclosure will be described in further detail below, although the present disclosure is not limited to the following embodiments.

[0021] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​written before and after "to" as the minimum and maximum values, respectively. Furthermore, unless specifically stated otherwise, the units of the numerical values ​​written before and after "to" are the same. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with the values ​​shown in the examples. Furthermore, the individually described upper and lower limit values ​​can be arbitrarily combined. Furthermore, in this specification, "(meth)acrylic" means at least one of acrylic and the corresponding methacrylic.

[0022] <Coating Composition> A coating composition according to one embodiment of the present disclosure comprises an organic polyisocyanate (A) and an acrylic polyol (B), wherein the organic polyisocyanate (A) comprises a modified polyisocyanate (a), and the modified polyisocyanate (a) is a reaction product of a polyisocyanate component (a1) and a polyol component (a2) or a modified product thereof, wherein the polyisocyanate component (a1) comprises an organic diisocyanate or a modified product thereof, and the polyol component (a2) comprises at least one member selected from the group consisting of polytetramethylene glycol and polycarbonate polyol, each having a number average molecular weight of 200 to 750, and the acrylic polyol (B) comprises an acrylic polyol (b) having a glass transition temperature of 5 to 30°C and a hydroxyl value of more than 100 mgKOH / g but not more than 150 mgKOH / g.

[0023] The coating composition according to one embodiment of the present disclosure can provide a coating film that has good contamination resistance and excellent self-repairing properties against scratches. Furthermore, the coating composition according to one embodiment of the present disclosure can also provide a coating film that has good smoothness and adhesion. The coating composition according to one embodiment of the present disclosure and each component that may be contained in the coating composition are described in detail below.

[0024] (Organic Polyisocyanate (A)) The organic polyisocyanate (A) includes a modified polyisocyanate (a). The modified polyisocyanate (a) is a reaction product of a polyisocyanate component (a1) and a polyol component (a2) or a modified product thereof.

[0025] The reaction product may be a urethane-modified polyisocyanate obtained by reacting the polyisocyanate component (a1) with the polyol component (a2), or may be an allophanate-modified polyisocyanate obtained by allophanating the urethane-modified polyisocyanate, or an isocyanurate-modified polyisocyanate obtained by isocyanating the urethane-modified polyisocyanate.

[0026] Examples of modified products include block modified products of the above reaction products. Block modified products have a structure in which a portion of the isocyanate groups is modified with a blocking agent. By blocking the isocyanate groups, the blocking agent prevents the isocyanate groups from reacting with moisture and active hydrogen groups such as hydroxyl groups, thereby suppressing the progress of the reaction in the coating composition. Therefore, block modified products make it easy to produce one-component coatings. The blocked modified polyisocyanate (a) is a latent curing agent that reacts with active hydrogen groups when the blocking agent is dissociated by heating, reactivating the isocyanate groups. Details of the blocking agent will be described later. In the following description, allophanate-modified polyisocyanates and isocyanurate-modified polyisocyanates include block-modified allophanate-modified polyisocyanates and isocyanurate-modified polyisocyanates.

[0027] The modified polyisocyanate (a) preferably contains an allophanate-modified polyisocyanate. By including an allophanate-modified polyisocyanate in the modified polyisocyanate (a), a flexible yet tough coating film can be obtained, a liquid with a lower viscosity can be obtained, and handling properties during application can be improved, thereby further improving the self-repairing properties of the coating film.

[0028] From the viewpoint of obtaining a more flexible and tough coating film, the modified polyisocyanate (a) may contain the allophanate-modified polyisocyanate and an isocyanurate-modified polyisocyanate. When the modified polyisocyanate (a) contains an isocyanurate-modified polyisocyanate, the glass transition temperature of the resulting coating film (the polyurethane resin in the coating film) increases, but the glass transition temperature can be lowered by, for example, increasing the content of a structure derived from a polycarbonate polyol, thereby preventing the loss of self-repairing property.

[0029] When the modified polyisocyanate (a) contains an allophanate-modified polyisocyanate or an isocyanurate-modified polyisocyanate, the smaller the number of urethane groups in the modified polyisocyanate (a), the more the self-repairing property of the coating film can be improved. From this viewpoint, the modified polyisocyanate (a) may be substantially free of urethane groups. The term "substantially free of urethane groups" used in the modified polyisocyanate (a) means that the modified polyisocyanate (a) is substantially free of urethane groups when measured by proton nuclear magnetic resonance ( １ This means that the content of the urethane-modified polyisocyanate confirmed by H-NMR spectrum is 0.5 mol % or less based on the total amount of the allophanate-modified polyisocyanate, the isocyanurate-modified polyisocyanate, and the urethane-modified polyisocyanate.

[0030] From the viewpoint of further improving the self-repairing properties of the coating film, the content (total amount) of the allophanate-modified polyisocyanate and the isocyanurate-modified polyisocyanate in the modified polyisocyanate (a) may be 80% by mass or more, 90% by mass or more, or may be 100% by mass, based on the total mass of the modified polyisocyanate (a).

[0031] When the modified polyisocyanate (a) contains an allophanate-modified polyisocyanate and an isocyanurate-modified polyisocyanate, the content of the isocyanurate-modified polyisocyanate may be 30 mol% or less, 20 mol% or less, or 10 mol% or less, based on the total amount of the allophanate-modified polyisocyanate and the isocyanurate-modified polyisocyanate, from the viewpoint of further improving the self-repairing properties of the coating film. The content of the isocyanurate-modified polyisocyanate may be 1 mol% or more, 2 mol% or more, or 3 mol% or more, based on the total amount of the allophanate-modified polyisocyanate and the isocyanurate-modified polyisocyanate, from the viewpoint of further improving the stain resistance of the coating film. From the above viewpoint, the content of the isocyanurate-modified polyisocyanate may be 1 to 30 mol%, 2 to 20 mol%, or 3 to 10 mol%. The content can be determined by proton nuclear magnetic resonance ( １ This can be confirmed by H-NMR spectrum.

[0032] The average number of functional groups of the modified polyisocyanate (a) may be 4.0 or more, or may be 4.5 or more, from the viewpoint of obtaining a coating film with superior self-repairing properties. The average number of functional groups of the modified polyisocyanate (a) may be 6.0 or less, or may be 5.5 or less, from the viewpoint of viscosity. The average number of functional groups of the modified polyisocyanate (a) may be 4.0 to 6.0 or 4.5 to 5.5, from the above viewpoints.

[0033] In this specification, the average number of functional groups in the modified polyisocyanate (a) refers to the average number of isocyanate groups (-NCO) contained per molecule of the modified polyisocyanate (a). The average number of functional groups in the modified polyisocyanate (a) can be calculated from the isocyanate group content (NCO content) and number average molecular weight of the modified polyisocyanate (a). When the modified polyisocyanate (a) is a block modified product, the average number of functional groups also includes the number of blocked isocyanate groups.

[0034] The NCO content of the modified polyisocyanate (a) may be 13.0 to 23.0 mass%, 14.0 to 22.0 mass%, or 15.0 to 21.0 mass%. When the NCO content of the modified polyisocyanate (a) is 23.0 mass% or less, the self-repairing properties of the coating film are further improved. When the NCO content of the modified polyisocyanate (a) is 13.0 mass% or more, the contamination resistance of the coating film is improved.

[0035] In this specification, the NCO content is a value measured by the method described in JIS K1603-1 (Testing methods for aromatic isocyanates used as raw materials for polyurethanes). However, when the modified polyisocyanate (a) is a block-modified product, the NCO content of the modified polyisocyanate (a) in an unblocked state (a state in which the blocking agent has been dissociated) is measured.

[0036] The number average molecular weight of the modified polyisocyanate (a) may be 500 to 8,000, 600 to 7,500, or 700 to 7,000. When the number average molecular weight of the modified polyisocyanate (a) is 500 or more, the self-repairing properties of the coating film are further improved. When the number average molecular weight of the modified polyisocyanate (a) is 8,000 or less, the smoothness of the coating film is further improved, and the appearance of the coating film is further improved.

[0037] In this specification, the number average molecular weight is a value measured using GPC (gel permeation chromatography) under the following conditions. However, when the modified polyisocyanate (a) is a block-modified product, the number average molecular weight of the modified polyisocyanate (a) in an unblocked state (a state in which the blocking agent has been dissociated) is measured. [Conditions] Measuring instrument: "HLC-8120" (manufactured by Tosoh Corporation) Column: "TSKguard column HXL-L" (manufactured by Tosoh Corporation) Particle size = 6 μm, size = 6 mm ID × 30 cm × 4 columns Carrier: tetrahydrofuran (THF) Detector: parallax refraction Sample: 0.1% THF solution Calibration curve: polystyrene

[0038] The viscosity of the modified polyisocyanate (a) at 25°C may be 500 to 10,000 mPa·s, or may be 800 to 6,000 mPa·s, or 1,000 to 3,000 mPa·s. When the viscosity of the modified polyisocyanate (a) at 25°C is within the above range, the coating film formability is good, the coating film smoothness is even better, and the coating film appearance is even better. The viscosity of the modified polyisocyanate (a) at 25°C is a value measured using a B-type viscometer.

[0039] The organic polyisocyanate (A) may contain one type of modified polyisocyanate (a) alone or in combination of two or more types. Furthermore, the organic polyisocyanate (A) may contain an organic polyisocyanate other than the modified polyisocyanate (a) (for example, a polyisocyanate component (a1) as a reaction raw material) as long as the self-repairing property is not impaired. However, the content of the modified polyisocyanate (a) in the organic polyisocyanate (A) is preferably 80% by mass or more, more preferably 90% by mass, and even more preferably 100% by mass, based on the total mass of the organic polyisocyanate (A). The content of the free polyisocyanate component (a1) may be 1.0% by mass or less, based on the total mass of the organic polyisocyanate (A).

[0040] Next, the polyisocyanate component (a1) and the polyol component (a2), which are reaction raw materials for the modified polyisocyanate (a), and the method for producing the modified polyisocyanate (a) will be described.

[0041] [Polyisocyanate Component (a1)] The polyisocyanate component (a1) is a component composed of an organic compound having multiple isocyanate groups, and includes an organic diisocyanate or a modified product thereof. The organic diisocyanate is an organic compound having two isocyanate groups. Examples of organic diisocyanates include aromatic diisocyanates, araliphatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. The modified product may be a modified product of these organic diisocyanates. Examples of the modified product include allophanate-modified polyisocyanates, isocyanurate-modified polyisocyanates, uretdione-modified polyisocyanates, urethane-modified polyisocyanates, biuret-modified polyisocyanates, uretoimine-modified polyisocyanates, and acylurea-modified polyisocyanates. The polyisocyanate component (a1) may be one selected from the above organic diisocyanates and modified products, or may be a mixture of two or more selected from the above organic diisocyanates and modified products.

[0042] Examples of aromatic diisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a 2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate mixture, m-xylylene diisocyanate, p-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, a 2,4'-diphenylmethane diisocyanate / 4,4'-diphenylmethane diisocyanate mixture, 4,4'-diphenylamine diisocyanate, terdiisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, and the like.

[0043] Examples of the aromatic aliphatic diisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or a mixture thereof, and ω,ω'-diisocyanato-1,4-diethylbenzene.

[0044] Examples of the aliphatic diisocyanate include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, and trioxyethylene diisocyanate.

[0045] Examples of alicyclic diisocyanates include isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, and hydrogenated tetramethylxylene diisocyanate.

[0046] From the viewpoint of the weather resistance of the coating film, organic diisocyanates are preferred, and it is more preferable to use at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. Also, from the viewpoint of the weather resistance of the coating film, polyisocyanates having no unsaturated bonds are preferred. That is, it is more preferable to use at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates having no unsaturated bonds. Among them, hexamethylene diisocyanate is particularly preferred because it is easily available and synthesized, and a coating film having excellent adhesion and self-repairing properties can be obtained.

[0047] The polyisocyanate component (a1) may contain a polyisocyanate other than the organic diisocyanate and its modified product, provided that the content (total amount) of the organic diisocyanate and its modified product in the polyisocyanate component (a1) is preferably 80% by mass or more, more preferably 90% by mass, and even more preferably 100% by mass, based on the total mass of the polyisocyanate component (a1).

[0048] [Polyol Component (a2)] The polyol component (a2) is a component composed of an organic compound having multiple hydroxyl groups. The polyol component (a2) contains at least one member selected from the group consisting of polytetramethylene glycol and polycarbonate polyol, each having a number average molecular weight of 200 to 750.

[0049] Polytetramethylene glycol is a compound having an oxytetramethylene group in its molecular skeleton, and is mainly obtained by ring-opening polymerization of tetrahydrofuran. The number average molecular weight of polytetramethylene glycol is 200 to 750, and may be 220 or more or 250 or more, 600 or less or 500 or less, or may be 220 to 600 or 250 to 500. The larger the number average molecular weight of polytetramethylene glycol, the more likely it is that the self-repairing properties of the coating film will be improved, and the smaller the number average molecular weight of polytetramethylene glycol, the more likely it is that the smoothness of the coating film will be improved and the more likely it is that a good coating film appearance will be obtained.

[0050] Polycarbonate polyols are compounds having multiple carbonate groups and multiple hydroxyl groups, and are mainly obtained by a dealcoholization reaction or a dephenolization reaction between a low-molecular-weight polyol (e.g., a polyol having a molecular weight of 500 or less) and a carbonate. Examples of polycarbonate polyols include compounds (reaction products) obtained by a dealcoholization reaction or a dephenolization reaction between at least one compound selected from the group of compounds shown in (α) below and at least one compound selected from the group of compounds shown in (β) below. (α): Low molecular weight polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer diol, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, glycerin, trimethylolpropane, and pentaerythritol. (β): Carbonates such as dialkyl carbonates such as dimethyl carbonate and diethyl carbonate; alkylene carbonates such as ethylene carbonate and propylene carbonate; diaryl carbonates such as diphenyl carbonate, dinaphthyl carbonate, dianthryl carbonate, diphenanthryl carbonate, diindanyl carbonate and tetrahydronaphthyl carbonate.

[0051] From the viewpoint of further enhancing the stain resistance of the coating film, the polycarbonate polyol is preferably one obtained by a dealcoholization reaction between 1,6-hexanediol and a dialkyl carbonate (a reaction product of 1,6-hexanediol and a dialkyl carbonate).

[0052] The number average molecular weight of the polycarbonate polyol is 200 to 750, and may be 220 or more, 250 or more, or 300 or more, or 600 or less, 500 or less, or 400 or less, or may be 220 to 600, 250 to 500, 300 to 750, or 200 to 400. The larger the number average molecular weight of the polycarbonate polyol, the more likely it is that the self-repairing property of the coating film will be improved, and the smaller the number average molecular weight of the polycarbonate polyol, the more likely it is that the smoothness of the coating film will be improved and a good coating film appearance will be obtained.

[0053] The polyol component (a2) may contain a polyol (another polyol) other than polytetramethylene glycol and polycarbonate polyol. In other words, the modified polyisocyanate (a) may be a reaction product of the polyisocyanate component (a1) (e.g., an organic diisocyanate or a modified product thereof), at least one polyol having a number average molecular weight of 200 to 750 selected from the group consisting of polytetramethylene glycol and polycarbonate polyol, and another polyol. However, the content (total amount) of polytetramethylene glycol and polycarbonate polyol in the polyol component (a2) is preferably 80% by mass or more, more preferably 90% by mass, and even more preferably 100% by mass, based on the total mass of the polyol component (a2).

[0054] Examples of other polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer diol, an ethylene oxide adduct of bisphenol A, a propylene oxide adduct of bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, glycerin, trimethylolpropane, and pentaerythritol. As the other polyol, one type of compound may be used, or two or more types of compounds may be used in combination.

[0055] Other polyols that can be used include polyester polyols, polyether polyols, acrylic polyols, polyolefin polyols, fluorine-based polyols, and animal and vegetable oil-based polyols.

[0056] [Method for Producing Modified Polyisocyanate (a)] The modified polyisocyanate (a) can be obtained, for example, through the following first to fourth steps.

[0057] Step 1: Polyisocyanate component (a1) and polyol component (a2) are charged in amounts such that the isocyanate groups are in excess relative to the hydroxyl groups, and a urethane reaction is carried out to obtain an isocyanate-terminated prepolymer I. Step 2: A catalyst is charged to the isocyanate-terminated prepolymer I, and allophanation is allowed to proceed at 70 to 150°C to produce an isocyanate-terminated prepolymer II. Step 3: A reaction terminator is added to the isocyanate-terminated prepolymer II to terminate the reaction. Step 4: Free polyisocyanate component (a1) is removed by thin-film distillation or solvent extraction of the isocyanate-terminated prepolymer II to obtain a modified polyisocyanate (a).

[0058] In the first to third steps, the reaction is carried out in a nitrogen gas or dry air stream. The first to third steps may be carried out in the presence or absence of an organic solvent.

[0059] As the organic solvent, various organic solvents that do not affect the reaction can be used. Examples of the organic solvent include aliphatic hydrocarbons such as octane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as methyl isobutyl ketone and cyclohexanone; esters such as butyl acetate and isobutyl acetate; glycol ether esters such as ethylene glycol ethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, and ethyl-3-ethoxypropionate; ethers such as dioxane; halogenated hydrocarbons such as methylene iodide and monochlorobenzene; and polar aprotic solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and hexamethylphosphonylamide. These organic solvents may be used alone or in combination of two or more.

[0060] Next, the method for producing the modified polyisocyanate (a) according to one embodiment will be described in more detail, taking as an example the production process of the modified polyisocyanate (a) in which allophanate modification mainly proceeds.

[0061] [Step 1: Step of Producing Isocyanate Group-Terminated Prepolymer I] In Step 1, the polyisocyanate component (a1) and the polyol component (a2) are reacted to produce the isocyanate group-terminated prepolymer I. The amounts of the polyisocyanate component (a1) and the polyol component (a2) charged are such that the isocyanate groups are in excess relative to the hydroxyl groups.

[0062] The "excess amount of isocyanate groups relative to hydroxyl groups" refers to the number of moles of isocyanate groups in the polyisocyanate component (a1) (M' ＮＣＯ ) and the number of moles of hydroxyl groups in the polyol component (a2) (M' ＯＨ ) and the ratio R' (=M' ＮＣＯ / M' ＯＨ The amount of the urethane group-containing polyisocyanate may be an amount such that the ratio R' is 6 to 40, or an amount such that the ratio R' is 7 to 30. When the ratio R' is 6 or more, it is possible to further prevent the amount of isocyanurate-modified polyisocyanate in the resulting modified polyisocyanate (a) from becoming excessive. When the ratio R' is 40 or less, it is possible to further prevent an increase in the amount of polyisocyanate containing urethane groups in the resulting modified polyisocyanate (a), it is possible to further prevent a decrease in the number of functional groups, and it is possible to further improve productivity and yield.

[0063] The temperature at which the polyisocyanate component (a1) and the polyol component (a2) are reacted (urethanization reaction temperature) is, for example, 20 to 120° C., and may be 20 to 100° C. or 50 to 100° C. The reaction time for the urethanization reaction varies depending on the presence or absence of a catalyst, the type of catalyst, and the temperature, but is generally within 10 hours, and may be 1 to 5 hours.

[0064] A known urethanization catalyst can be used in the urethanization reaction. Examples of the urethanization catalyst include organometallic compounds such as dibutyltin diacetate, dibutyltin dilaurate, and dioctyltin dilaurate; organic amines such as triethylenediamine and triethylamine, and salts thereof; and the like. These catalysts may be used alone or in combination of two or more.

[0065] [Step 2: Step of Producing Isocyanate Group-Terminated Prepolymer II] In Step 2, an allophanation reaction is further carried out after the urethanization reaction in Step 1 to produce an isocyanate group-terminated prepolymer II. In this case, the allophanation reaction may be carried out simultaneously (in parallel) with the urethanization reaction, or may be carried out after the urethanization reaction is completed.

[0066] When the urethanization reaction and the allophanation reaction are carried out simultaneously (in parallel), the reactions may be carried out in the presence of a urethanization catalyst and an allophanation catalyst. On the other hand, when the allophanation reaction is carried out after the completion of the urethanization reaction, the urethanization reaction may be carried out for a predetermined time in the presence of the urethanization catalyst but in the absence of the allophanation catalyst, and then the allophanation reaction may be carried out by adding the allophanation catalyst.

[0067] The allophanate catalyst can be appropriately selected from known catalysts and includes, for example, metal salts of carboxylic acids (metal salts of alkali metals such as lithium, sodium, and potassium; metal salts of alkaline earth metals such as magnesium, calcium, and barium; metal salts of other typical metals such as tin and lead; and metal salts of transition metals such as manganese, iron, cobalt, nickel, copper, zinc, and zirconium). Examples of carboxylic acids include monocarboxylic acids and polycarboxylic acids.

[0068] Specific examples of the allophanate catalyst include zirconium octylate, etc. The allophanate catalyst may be used alone or in combination of two or more.

[0069] The amount of the allophanation catalyst used may be 0.001 to 0.1% by mass, or may be 0.005 to 0.03% by mass, based on the total mass of the polyisocyanate component (a1) and the polyol component (a2). When the amount of the allophanation catalyst used is 0.001% by mass or more, the allophanation reaction proceeds more easily, the amount of by-products of the urethane-modified polyisocyanate is suppressed, and a decrease in the number of functional groups in the resulting polyisocyanate is further suppressed. Furthermore, when the amount of the allophanation catalyst used is 0.1% by mass or less, storage stability is further improved.

[0070] The reaction temperature for the allophanate formation reaction is preferably 70 to 150°C, more preferably 90 to 130°C. When the reaction temperature is 70°C or higher, the allophanate-modified polyisocyanate is more easily produced, and the amount of by-products of the urethane-modified polyisocyanate is further suppressed, thereby further suppressing a decrease in the number of functional groups in the resulting polyisocyanate. Furthermore, when the reaction temperature is 150°C or lower, the by-products of the isocyanurate-modified polyisocyanate are suppressed, further improving the self-repairing property.

[0071] The allophanatization reaction is preferably carried out until urethane groups are substantially absent. Here, the term "urethane groups are substantially absent" refers to the state where urethane groups are substantially absent as determined by proton nuclear magnetic resonance ( １ This means that the content of the urethane-modified polyisocyanate confirmed by H-NMR spectrum is 0.5 mol % or less based on the total amount of the allophanate-modified polyisocyanate, the isocyanurate-modified polyisocyanate, and the urethane-modified polyisocyanate.

[0072] In the second step, the allophanate reaction mainly proceeds, but as described above, the ratio R' (=M') in the first step ＮＣＯ / M' ＯＨ For example, by setting the ratio R' to 10 or more, the content of the isocyanurate-modified polyisocyanate (based on the total amount of the allophanate-modified polyisocyanate and the isocyanurate-modified polyisocyanate) can be set to 30 mol % or less.

[0073] [Step 3: Reaction Termination Step] In Step 3, after the allophanation reaction in Step 2, a reaction terminator that deactivates the catalyst is added to terminate the allophanation reaction. The reaction terminator may be added after the allophanation reaction has been completed (after urethane groups have substantially ceased to exist). However, in order to suppress the progression of side reactions, it is preferable to add the reaction terminator promptly after the allophanation reaction has been completed.

[0074] Examples of reaction terminators that can be used include inorganic acids such as phosphoric acid and hydrochloric acid, organic acids having a sulfonic acid group, a sulfamic acid group, and their esters, and known compounds such as acyl halides. These may be used alone or in combination of two or more.

[0075] The amount of reaction terminator added varies depending on the type of catalyst, but may be 0.5 to 10 equivalents, or 0.8 to 5.0 equivalents, relative to the amount of catalyst added. When the amount of reaction terminator added is 0.5 equivalents or more, the storage stability of the resulting modified polyisocyanate is further improved. When the amount of reaction terminator added is 10 equivalents or less, coloration can be further suppressed. After the reaction has stopped, a purification step can be carried out to remove free, unreacted polyisocyanate component (a1).

[0076] [Step 4: Purification Step] In Step 4, any free, unreacted polyisocyanate component (a1) present in the reaction mixture is removed. If an organic solvent is used in the reaction step, it can be removed in this purification step.

[0077] The polyisocyanate component (a1) is preferably removed to a residual content of 1.0% by mass or less, more preferably to a residual content of less than 1.0% by mass. When the residual content is 1.0% by mass or less, odor is further reduced and storage stability is further improved.

[0078] The removal of the polyisocyanate component (a1) is preferably carried out by thin film distillation, which can be carried out, for example, under a high vacuum of 10 to 100 Pa at a temperature of 120 to 140°C.

[0079] Although the method for producing the modified polyisocyanate (a) according to one embodiment has been described above, the method for producing the modified polyisocyanate (a) is not limited to the above-described embodiment.

[0080] For example, in another embodiment, the second to fourth steps may not be carried out, and the isocyanate group-terminated prepolymer I obtained in the first step may be used as the modified polyisocyanate (a).

[0081] Furthermore, for example, in another embodiment, a step of modifying (blocking) a portion of the isocyanate groups with a blocking agent may be carried out after the fourth step. Examples of the blocking agent include phenol-based blocking agents such as phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol, p-hydroxydiphenyl, t-butylphenol, o-isopropylphenol, o-sec-butylphenol, p-nonylphenol, p-t-octylphenol, hydroxybenzoic acid, and hydroxybenzoic acid esters; lactam-based blocking agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; active methylene-based blocking agents such as diethyl malonate, dimethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone; methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, n-amyl alcohol, t-amyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and diethylene glycol monomethyl ether. alcohol-based blocking agents such as ethylene glycol monoethyl ether, propylene glycol monomethyl ether, benzyl alcohol, methoxymethanol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate and other glycolic acid esters; lactic acid, methyl lactate, ethyl lactate, butyl lactate and other lactate esters; methylol urea, methylol melamine, diacetone alcohol, ethylene chlorohydrin, ethylene bromohydrin, 1,3-dichloro-2-propanol, ω-hydroperfluoroalcohol, acetocyanhydrin and other alcohol-based blocking agents; mercaptan-based blocking agents such as butyl mercaptan, hexyl mercaptan, t-butyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol and other mercaptan-based blocking agents; acid amide-based blocking agents such as acetanilide, acetanisidide, acetotoluide, acrylamide, methacrylamide, acetic amide, stearic acid amide, benzamide and other acid amide-based blocking agents; imide-based blocking agents such as succinimide, phthalic acid imide, maleic acid imide and otherExamples of suitable blocking agents include amine-based blocking agents such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylphenylamine; imidazole-based blocking agents such as imidazole and 2-ethylimidazole; urea-based blocking agents such as urea, thiourea, ethyleneurea, ethylenethiourea, and 1,3-diphenylurea; carbamate-based blocking agents such as N-phenylphenylcarbamate and 2-oxazolidone; imine-based blocking agents such as ethyleneimine and propyleneimine; oxime-based blocking agents such as formamidoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexanone oxime; and sulfite-based blocking agents such as sodium bisulfite and potassium bisulfite. These blocking agents may be used alone or in combination of two or more.

[0082] Alternatively, for example, an isocyanurate catalyst may be used instead of an allophanate catalyst to mainly promote isocyanurate modification. The degree of progress of allophanate modification and isocyanurate modification depends on the selection of various catalysts and the above ratio R' (=M' ＮＣＯ / M' ＯＨ ) can be adjusted.

[0083] (Acrylic Polyol (B)) The acrylic polyol (B) includes an acrylic polyol (b). Here, the term "acrylic polyol" refers to a polymer containing (meth)acrylic monomers as monomer units and having a plurality of hydroxyl groups.

[0084] The acrylic polyol (b) may be a homopolymer obtained by polymerizing one kind of (meth)acrylic monomer, or may be a copolymer obtained by copolymerizing two or more kinds of (meth)acrylic monomer. The acrylic polyol (b) may contain a monomer other than the (meth)acrylic monomer as a monomer unit, but from the viewpoint of achieving both a predetermined glass transition temperature and a hydroxyl value, it is preferable that the acrylic polyol (b) contains only the (meth)acrylic monomer as a monomer unit.

[0085] Examples of the homopolymer obtained by polymerizing one type of (meth)acrylic monomer include a homopolymer of a (meth)acrylic acid hydroxy compound. Examples of the copolymer obtained by copolymerizing two or more types of (meth)acrylic monomers include a copolymer obtained by copolymerizing a (meth)acrylic acid ester and a (meth)acrylic acid hydroxy compound.

[0086] Here, the (meth)acrylic acid ester is at least one selected from the group consisting of acrylic acid esters and methacrylic acid esters, and the (meth)acrylic acid hydroxy compound is at least one selected from the group consisting of acrylic acid hydroxy compounds and methacrylic acid hydroxy compounds, each having one or more hydroxyl groups that can serve as reaction sites in its molecule.

[0087] The glass transition temperature (glass transition point, Tg) of the acrylic polyol (b) is 5 to 30°C. If the glass transition temperature of the acrylic polyol (b) is less than 5°C, the self-repairing ability against repeated scratches and the contamination resistance when used outdoors may decrease. Furthermore, if the glass transition temperature of the acrylic polyol (b) exceeds 30°C, the self-repairing ability at room temperature (e.g., 5 to 35°C) and low temperatures (e.g., less than 5°C) may decrease. The glass transition temperature of the acrylic polyol (b) may be 10°C or higher or 15°C or higher, from the viewpoint of improving the self-repairing ability against repeated scratches and the contamination resistance when used outdoors. The glass transition temperature of the acrylic polyol (b) may be 25°C or lower or 20°C or lower, from the viewpoint of improving the self-repairing ability at room temperature and low temperatures. From the above viewpoint, the glass transition temperature of the acrylic polyol (b) may be 10 to 25°C or 15 to 20°C. The polyol (b) having a glass transition temperature within the above range can be synthesized by adjusting the types and compounding ratios of the monomer components. For example, when the acrylic polyol (b) is a copolymer, the glass transition temperature can be estimated by Fox's equation and the compounding ratios of the monomer components can be set to obtain the acrylic polyol (b) having a glass transition temperature within the above range.

[0088] The glass transition temperature of the acrylic polyol (b) can be determined by measuring the inflection point of DSC in accordance with JIS K7121.

[0089] The hydroxyl value of the acrylic polyol (b) is greater than 100 mgKOH / g and less than 150 mgKOH / g. If the hydroxyl value of the acrylic polyol (b) is outside this range, the self-repairing property, contamination resistance, and smoothness may be reduced. The hydroxyl value of the acrylic polyol (b) may be 120 mgKOH / g or greater or 140 mgKOH / g or greater, from the viewpoint of improving contamination resistance and smoothness. The hydroxyl value of the acrylic polyol (b) may be 130 mgKOH / g or less or 110 mgKOH / g or less, from the viewpoint of improving self-repairing property. From the above viewpoints, the hydroxyl value of the acrylic polyol (b) may be 120 to 150 mgKOH / g, 140 to 150 mgKOH / g, 120 to 130 mgKOH / g, greater than 100 and less than 130 mgKOH / g, or greater than 100 and less than 110 mgKOH / g. The hydroxyl value of the acrylic polyol (b) is a value measured by a method in accordance with JIS K1557.

[0090] The acrylic polyol (b) can be obtained, for example, by applying energy (light energy such as ultraviolet light or electron beam, or thermal energy) to a mixture of a (meth)acrylic monomer and a polymerization initiator to polymerize the (meth)acrylic monomer. In other words, the acrylic polyol (b) may be a thermal polymer or a photopolymer. The acrylic polyol (b) may be a thermal polymer because it is likely to become a polymer in which the polymerization reaction and crosslinking reaction are completed.

[0091] The acrylic polyol (B) may contain one acrylic polyol (b) alone or two or more acrylic polyols (b) in combination. The acrylic polyol (B) may also contain an acrylic polyol (b') other than the acrylic polyol (b) (an acrylic polyol having one or both of a glass transition temperature and a hydroxyl value outside the above ranges).

[0092] The content of the acrylic polyol (b') in the acrylic polyol (B) may be 50% by mass or less (for example, 0 to 50% by mass), 30% by mass or less, or 10% by mass or less, based on the total mass of the acrylic polyol (B), from the viewpoint that a coating film having better self-repairing properties and stain resistance can be more easily obtained.

[0093] Next, the (meth)acrylic acid ester and (meth)acrylic acid hydroxy compound, which can be reaction raw materials for the acrylic polyol (b), and the polymerization initiator will be described.

[0094] [(Meth)acrylic acid esters] Examples of (meth)acrylic acid esters include alkyl esters having an alkyl group having 1 to 20 carbon atoms. Examples of such (meth)acrylic acid esters include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, and dodecyl (meth)acrylate; (meth)acrylic acid cycloalkyl esters (products obtained by esterification of (meth)acrylic acid with an alicyclic alcohol) such as cyclohexyl (meth)acrylate; and (meth)acrylic acid aryl esters such as phenyl (meth)acrylate and benzyl (meth)acrylate. These (meth)acrylic acid esters may be used alone or in combination of two or more.

[0095] [(Meth)acrylic Acid Hydroxy Compound] The (meth)acrylic acid hydroxy compound has one or more hydroxyl groups in the molecule that can serve as a reaction site with the polyisocyanate composition. Examples of the (meth)acrylic acid hydroxy compound include acrylic acid hydroxy compounds such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 3-hydroxy-2,2-dimethylpropyl acrylate, and pentaerythritol triacrylate; and methacrylic acid hydroxy compounds such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethylpropyl methacrylate, and pentaerythritol trimethacrylate. These (meth)acrylic acid hydroxy compounds may be used alone or in combination of two or more.

[0096] [Polymerization initiator] Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator. The polymerization initiator is appropriately selected depending on the polymerization method.

[0097] Examples of the thermal polymerization initiator include peroxydicarbonates such as di-2-ethylhexyl peroxydicarbonate; peroxyesters such as t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisopropyl carbonate, and t-hexylperoxyisopropyl carbonate; and peroxyketals such as di(t-butylperoxy)-2-methylcyclohexane, di(t-butylperoxy)3,3,5-trimethylcyclohexane, and di(t-butylperoxy)cyclohexane.

[0098] Examples of the photopolymerization initiator include acetophenones such as acetophenone, methoxyacetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, α-hydroxy-α,α'-dimethylacetophenone, 2-hydroxy-2-cyclohexylacetophenone, and 2-methyl-1[4-(methylthio)phenyl]-2-montmorillonite-1; benzoin ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl butyl ether; and benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl butyl ether. ketones such as benzophenone, 2-chlorobenzophenone, p,p'-dichlorobenzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, and 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone; thioxanthones such as thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone; phosphine oxides such as bisacylphosphine oxide and benzoylphosphine oxide; ketals such as benzyl dimethyl ketal; and quinones such as camphane-2,3-dione and phenanthrenequinone.

[0099] (Polydimethylsiloxane Compound) The coating composition may contain a polydimethylsiloxane compound. By using a polydimethylsiloxane compound, it is possible to further improve the smoothness and contamination resistance of the coating film, as well as further improve the scratch resistance while maintaining self-repairing properties. Therefore, by using a polydimethylsiloxane compound, it is possible to achieve a high level of both self-repairing properties and scratch resistance, even when the coating film obtained by coating is a thin film with a thickness of less than 20 μm.

[0100] Here, the polydimethylsiloxane compound includes not only polydimethylsiloxane (dimethylpolysiloxane) but also modified polydimethylsiloxane. Examples of modified polydimethylsiloxane include polydimethylsiloxane modified with a compound having at least one hydroxyl group. Such modified polydimethylsiloxane has at least one hydroxyl group.

[0101] Examples of polydimethylsiloxane compounds include dimethylpolysiloxane-acrylic block copolymers having an acrylic moiety, dimethylpolysiloxane-polyether block copolymers having a polyether moiety, dimethylpolysiloxane-polyester block copolymers having a polyester moiety, and dimethylpolysiloxane-polyether-polyester block copolymers having a polyether moiety and a polyester moiety. Any of the above copolymers may have at least one hydroxyl group in its structure (in the acrylic moiety, the polyether moiety, or the polyester moiety). When the polydimethylsiloxane compound has at least one hydroxyl group in its structure, the additive reacts with the polyisocyanate, making it less likely for the additive to bleed out after coating film formation, facilitating improved stain resistance and excellent recoatability. Among polydimethylsiloxane compounds, those having two or more hydroxyl groups and an acrylic block are not considered to be acrylic polyols (B).

[0102] Examples of dimethylpolysiloxane-acrylic block copolymers include BYK-SILCLEAN 3700 (manufactured by BYK Japan, number average molecular weight: 7600, silicon content (SiO ２ (equivalent to 1 mass %).

[0103] Examples of dimethylpolysiloxane-polyether block copolymers include BYK-377 (number average molecular weight: 1400, silicon content: 18% by mass), BYK-SILCLEAN 3720 (number average molecular weight: 1100, silicon content: 17% by mass), BYK-9200 (number average molecular weight: 4600, silicon content: 36% by mass), and BYK-9201 (number average molecular weight: 4100, silicon content: 17% by mass). Elemental content: 20% by mass), BYK-9204 (number average molecular weight: 5700, silicon content: 26% by mass), BYK-9205 (number average molecular weight: 4800, silicon content: 37% by mass), BYK -9206 (number average molecular weight: 5400, silicon content: 34% by mass), BYK-9210 (number average molecular weight: 4200, silicon content: 14% by mass), BYK-9211 (number average molecular weight: 49 00, silicon content: 37% by mass), BYK-9215 (number average molecular weight: 4500, silicon content: 29% by mass), BYK-9230 (number average molecular weight: 6000, silicon content: 20% by mass) ), BYK-9241 (number average molecular weight: 6000, silicon content: 22% by mass), BYK-9242 (number average molecular weight: 10500, silicon content: 16% by mass), BYK-9247 (number average molecular weight: 10500, silicon content: 16% by mass) Examples of such polyisocyanates include BYK-9420 (number average molecular weight: 2500, silicon content: 33% by mass), BYK-9001 (number average molecular weight: 6800, silicon content: 22% by mass), BYK-9004 (number average molecular weight: 6800, silicon content: 17% by mass), and BYK-9020 (number average molecular weight: 10500, silicon content: 17% by mass). All of the above products are manufactured by BYK Japan.

[0104] An example of the dimethylpolysiloxane-polyester block copolymer is BYK-370 (manufactured by BYK Japan, number average molecular weight: 2100, silicon content: 8% by mass).

[0105] Examples of dimethylpolysiloxane-polyether-polyester block copolymers include BYK-375 (manufactured by BYK Japan, number average molecular weight: 2200, silicon content: 15% by mass).

[0106] The number average molecular weight of the polydimethylsiloxane compound may be 1,000 to 15,000, 1,500 to 12,000, or 2,000 to 8,000. When the number average molecular weight of the polydimethylsiloxane compound is 1,000 or more, the self-repairing properties of the coating film are further improved. When the number average molecular weight of the polydimethylsiloxane compound is 15,000 or less, the smoothness of the coating film is further improved, and the appearance of the coating film is further improved.

[0107] The silicon content of the polydimethylsiloxane compound may be 0.1% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, based on the total mass of the polydimethylsiloxane compound, from the viewpoint of further improving the smoothness, slipperiness, contamination resistance, and scratch resistance of the coating film. The silicon content of the polydimethylsiloxane compound may be 50% by mass or less, 45% by mass or less, 40% by mass or less, 15% by mass or less, 10% by mass or less, or 5.0% by mass or less, based on the total mass of the polydimethylsiloxane compound, from the viewpoint of further suppressing the occurrence of cissing and further suppressing a decrease in recoatability. From the above viewpoints, the silicon content of the polydimethylsiloxane compound may be 0.1 to 50% by mass, 0.1 to 15% by mass, 0.5 to 45% by mass, 0.5 to 10% by mass, 1.0 to 40% by mass, or 1.0 to 5.0% by mass, based on the total mass of the polydimethylsiloxane compound. The silicon content is determined by the following formula: SiO ２ It is a converted value measured by thermogravimetry-differential thermal analysis (TG-DTA) method.

[0108] The polydimethylsiloxane compounds may be used alone or in combination of two or more.

[0109] The amount of polydimethylsiloxane compound added is determined by the amount of SiO in the coating composition. ２ The converted silicon content (based on the total amount of the organic polyisocyanate (A), the acrylic polyol (B), and the polydimethylsiloxane compound) may be adjusted to fall within the range described below.

[0110] The polydimethylsiloxane compound may be added when mixing the acrylic polyol (B) and the organic polyisocyanate (A). For example, when forming a coating film, the organic polyisocyanate (A), the acrylic polyol (B), and the polydimethylsiloxane compound may be mixed and stirred. Furthermore, when the polydimethylsiloxane compound has at least one hydroxyl group, the polydimethylsiloxane compound may be incorporated into the organic polyisocyanate (A) by reacting it with the organic polyisocyanate in advance. In other words, the organic polyisocyanate (A) (e.g., modified polyisocyanate (a)) may be an organic polyisocyanate modified with a polydimethylsiloxane compound. In this case, the reaction liquid obtained by the reaction of the polydimethylsiloxane compound with the organic polyisocyanate may be mixed and stirred with the acrylic polyol (B) and used when forming a coating film.

[0111] (Other Components) Various paint additives can be used in the paint composition as needed. Examples of paint additives include those that impart leveling properties and contamination resistance to the coating film, as well as those that further improve scratch resistance while maintaining self-repair properties. Paint additives make it easier to achieve both self-repair properties and scratch resistance in practical use, even when the coating film is thin. Examples of additives include antioxidants such as 2,6-di-tert-butyl-4-methylphenol, ultraviolet absorbers, pigments, dyes, solvents, flame retardants, hydrolysis inhibitors, lubricants, plasticizers, fillers, antistatic agents, dispersants, catalysts, storage stabilizers, thickeners, etc.

[0112] As the catalyst, a known urethanization catalyst can be used. Examples include organometallic compounds such as dibutyltin diacetate, dibutyltin dilaurate, and dioctyltin dilaurate, and organic amines and salts thereof such as triethylenediamine, triethylamine, diazabicycloundecene, and diazabicyclononene. These catalysts may be used alone or in combination of two or more. The catalyst may be added when forming a coating film.

[0113] (M ＮＣＯ / M ＯＨ) The number of moles of hydroxyl groups in the hydroxyl group-containing compound contained in the coating composition (M ＯＨ ) relative to the number of moles of isocyanate groups in the isocyanate group-containing compound contained in the coating composition (M ＮＣＯ ) ratio R (= M ＮＣＯ / M ＯＨ ) may be 0.8 or more, 0.9 or more, or 1.0 or more, from the viewpoint of further suppressing excessive hydroxyl groups and further improving water resistance and moist heat resistance, and from the viewpoint of further suppressing a decrease in crosslink density and further improving durability (stain resistance, etc.) and the mechanical strength of the coating film. The ratio R may be 1.3 or less, 1.2 or less, or 1.1 or less, from the viewpoint of further suppressing excessive isocyanate groups, suppressing excessive production of isocyanurate groups and urea groups, and further improving the flexibility and self-repairing ability of the coating film. From the above viewpoints, the ratio R may be 0.8 to 1.3, 0.9 to 1.2, or 1.0 to 1.1.

[0114] From the same viewpoint as above, the ratio of the number of moles of isocyanate groups in the organic polyisocyanate (A) to the sum of the number of moles of hydroxyl groups in the acrylic polyol (B) and the number of moles of hydroxyl groups in the polydimethylsiloxane compound may be 0.8 to 1.3.

[0115] (Silicon content) SiO in the coating composition ２ The silicon content in terms of the total amount of the organic polyisocyanate (A), the acrylic polyol (B), and the polydimethylsiloxane compound is preferably 0.001 to 0.1% by mass. When the silicon content is 0.001% by mass or more, the resulting coating film has even better smoothness, slip properties, stain resistance, and scratch resistance. When the silicon content is 0.1% by mass or less, the occurrence of cissing can be further suppressed, and a decrease in recoatability can be further suppressed. From the same viewpoint as above, the silicon content may be 0.002% by mass or more, 0.005% by mass or more, or 0.01% by mass or more, and may be 0.09% by mass or less, or 0.05% by mass or less. Note that the "total amount of the organic polyisocyanate (A), the acrylic polyol (B), and the polydimethylsiloxane compound" can be rephrased as "the amount of all resin solids."

[0116] The coating composition can be prepared, for example, by mixing the organic polyisocyanate (A), the acrylic polyol (B), and optionally the polydimethylsiloxane compound and / or the additives so that the ratio R and the silicon content fall within the above-mentioned ranges.

[0117] As described above, the coating composition according to one embodiment of the present disclosure can provide a coating film that combines high self-repairability and contamination resistance. Furthermore, a coating film that is excellent not only in self-repairability and contamination resistance but also in smoothness and adhesion can be obtained. In particular, when the polydimethylsiloxane compound is used, a thin coating film of less than 20 μm that combines high self-repairability and contamination resistance can be obtained. For these reasons, the coating composition according to one embodiment of the present disclosure can be suitably used for forming surface coatings on automotive exterior components that require fine processing, high designability, and lightweight exterior parts, as well as on plastic molded products.

[0118] Although the coating composition according to one embodiment of the present disclosure has been described above, the coating composition and its production method according to the present disclosure are not limited to the above embodiment. For example, the coating composition may contain a reaction product of the organic polyisocyanate (A) and a polydimethylsiloxane compound having at least one hydroxyl group, instead of or in addition to the organic polyisocyanate (A) and the polydimethylsiloxane compound.

[0119] <Kit> A kit according to one aspect of the present disclosure is a kit for preparing the above-described coating composition (a coating composition preparation kit), and includes, for example, a first agent containing the above-described organic polyisocyanate (A) and a second agent containing the above-described acrylic polyol (B). Here, the organic polyisocyanate (A) contained in the first agent includes a modified polyisocyanate that is a reaction product of an organic polyisocyanate and a polydimethylsiloxane compound having at least one hydroxyl group (for example, a reaction product of a reaction product of a polyisocyanate component (a1) and a polyol component (a2) or a modified product thereof, with a polydimethylsiloxane compound).

[0120] The paint composition preparation kit may further include other agents in addition to the first and second agents. The other agents may include, for example, the polydimethylsiloxane compound.

[0121] The first and second agents may be prepared so that the coating composition is obtained by mixing them, or the coating composition may be prepared so that the coating composition is obtained by mixing the first agent, the second agent, and an agent other than the first and second agents. For example, when preparing a coating composition containing the polydimethylsiloxane compound, the polydimethylsiloxane compound may be blended in the first agent and / or the second agent, or the polydimethylsiloxane compound may be blended in another agent. The additives that can be contained in the coating composition may be contained in any of the first agent, the second agent, and the other agents.

[0122] When using the paint composition preparation kit, for example, the first agent, the second agent, and any other agents that are used optionally may be mixed so that the ratio R falls within the above-mentioned range.

[0123] <Coating Film> A coating film according to one embodiment of the present disclosure is a self-repairing coating film and includes a cured product of the coating composition described above. The coating film can exhibit self-repairing properties within one hour at room temperature (e.g., 5 to 35°C) or when heated to 40 to 60°C. The coating film can also exhibit good smoothness and good stain resistance under high humidity conditions. The present inventors speculate that the improved smoothness is due to improved drying properties and moisture resistance, and that the improved stain resistance is due to improved crosslink density.

[0124] The cured product of the coating composition contains a polyurethane resin having a urethane structure formed by a urethanization reaction between an organic polyisocyanate (A) and an acrylic polyol (B). The urethane structure contained in the polyurethane resin contains, in addition to a urethane group (-CONH-), reaction residues of the organic polyisocyanate (A) and the acrylic polyol (B), and optionally reaction residues of a polydimethylsiloxane compound (a polydimethylsiloxane compound having at least one hydroxyl group).

[0125] The coating film has a thickness of, for example, 5 to 40 μm. The coating film may be a thin film having a thickness of less than 20 μm. When the coating composition contains the polydimethylsiloxane compound (or a reaction product of the organic polyisocyanate (A) and a polydimethylsiloxane compound having at least one hydroxyl group), the coating film has good smoothness, contamination resistance, and adhesion, and is excellent in self-repairing ability against scratches, even if the thickness is less than 20 μm (for example, 5 μm).

[0126] The coating film is usually formed on an adherend. That is, one embodiment of the present disclosure includes an adherend and a coating film formed on the adherend. The adherend will be described later.

[0127] <Method for forming a coating film> A method for forming a coating film according to one aspect of the present disclosure comprises applying the coating composition described above onto an adherend, and curing the coating composition. Details of the adherend are as described above.

[0128] Examples of the adherend include molded articles made from materials such as stainless steel, phosphate-treated steel, zinc-coated steel, iron, copper, aluminum, brass, glass, acrylic polyol, polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene phthalate resin, polystyrene resin, AS resin, ABS resin, polycarbonate-ABS resin, 6-nylon resin, 6,6-nylon resin, MXD6 nylon resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyurethane resin, phenolic resin, melamine resin, polyacetal resin, chlorinated polyolefin resin, polyolefin resin, polyamide resin, polyether ether ketone resin, polyphenylene sulfide resin, NBR resin, chloroprene resin, SBR resin, and SEBS resin, as well as surface-treated articles of such molded articles. The surface-treated article may be a molded article (surface-treated molded article) made from an olefin resin such as polyethylene or polypropylene that has been subjected to a surface treatment such as corona discharge treatment.

[0129] The adherend may have another coating film on its surface that can serve as an intermediate layer. In other words, the coating composition may be applied directly to the surface of the molded body described above, or may be applied on top of another coating film that has been applied as a base coat on the surface of the molded body described above. The other coating film may be a single layer or multiple layers.

[0130] The coating composition may be applied by spraying, brushing, dipping, etc. According to the coating composition of one embodiment of the present disclosure, a coating film having excellent smoothness and self-repairing properties can be obtained even by spray coating, which is easily affected by humidity.

[0131] The coating composition may be cured, for example, by heating. The heating for curing may be heating for drying. That is, when the coating composition contains a solvent, the coating composition may be cured simultaneously (in parallel) with drying for removing the solvent. The heating temperature may be, for example, 60 to 150°C. The heating time may be, for example, 1 to 10 hours.

[0132] Examples of the present disclosure will be described below, but the present disclosure should not be construed as being limited to these examples.

[0133] <Measurement of Number Average Molecular Weight> The number average molecular weight disclosed in this example is a value measured under the following conditions. [Conditions] Measuring instrument: "HLC-8120" (manufactured by Tosoh Corporation) Column: "TSKguard column HXL-L" (manufactured by Tosoh Corporation) Particle size = 6 μm, size = 6 mm ID x 30 cm x 4 Carrier: tetrahydrofuran (THF) Detector: parallax refraction Sample: 0.1% THF solution Calibration curve: polystyrene

[0134] <Measurement of NCO Content> The NCO content disclosed in the examples is a value measured according to the method described in JIS K1603-1 (Testing method for aromatic isocyanates as raw materials for polyurethanes).

[0135] <Viscosity Measurement> The viscosity values ​​disclosed in the examples are values ​​obtained by measuring the viscosity at 25°C using a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd., model "DVL-BII") with a No. 4 rotor.

[0136] <Measurement of Free HDI Content> The free HDI content disclosed in the examples is a value calculated from the area ratio of the peak of hexamethylene diisocyanate in the polyisocyanate composition measured by GPC (HLC-8120 manufactured by Tosoh Corporation).

[0137] <Measurement of Silicon Content> The silicon content disclosed in the present examples was determined by measuring the mass residual rate after holding in a nitrogen atmosphere at 500°C for 30 minutes using thermogravimetry-differential thermal analysis (TG-DTA), and the mass residual rate was determined as equivalent to the silica residual rate, and was calculated as SiO ２ This value is obtained by calculating the conversion value.

[0138] <Synthesis of modified polyisocyanate> (Synthesis Example 1) A 1 L four-necked flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with 890 g of hexamethylene diisocyanate (manufactured by Tosoh Corporation, NCO content: 49.9% by mass, hereinafter referred to as "HDI"), and 110 g of PTMG-250 (manufactured by BASF Corporation, polytetramethylene glycol, trade name: Poly THF250, number average molecular weight 250), and a urethanization reaction was carried out for 2 hours at 80 ° C. under a nitrogen stream. Thereafter, 0.05 g of zirconium octylate (trade name: zirconyl octylate, manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd., hereinafter referred to as "OctZr") was added, and the allophanate reaction was carried out at 110 ° C. for 2 hours. After the NCO content reached 37.0% by mass, 0.5 g of JP-508 (trade name, acidic phosphate ester, manufactured by Johoku Chemical Industry Co., Ltd.) was added to terminate the reaction, and the reaction solution was cooled to room temperature. This reaction solution was subjected to thin-film distillation at 130°C and 0.04 kPa to remove unreacted HDI, yielding polyisocyanate P1.

[0139] Polyisocyanate P1 had an NCO content of 16.2% by mass, was a transparent liquid in appearance, had a number average molecular weight of 1,400, an average functionality calculated from the NCO content and number average molecular weight of 5.4, a viscosity at 25°C of 2,000 mPa·s, and a free HDI content of 0.2% by mass. Polyisocyanate P1 was found to contain mainly allophanate-modified polyisocyanate and a small amount of isocyanurate-modified polyisocyanate by proton nuclear magnetic resonance ( １The content of the isocyanurate-modified polyisocyanate was 2 mol % based on the total amount of the allophanate-modified polyisocyanate and the isocyanurate-modified polyisocyanate.

[0140] (Synthesis Example 2) In a 1 L four-neck flask equipped with a stirrer, thermometer, condenser, and dropping funnel, 880 g of HDI and 120 g of PCD-250 (polyhexamethylene polycarbonate diol, number average molecular weight 250) were charged, and the urethanization reaction was carried out for 2 hours at 80 ° C. under a nitrogen stream. Thereafter, 0.05 g of OctZr was added, and the allophanation reaction was carried out for 2 hours at 110 ° C. After the NCO content reached 35.9% by mass, 0.05 g of JP-508 was added to carry out a termination reaction, and the reaction solution was cooled to room temperature. This reaction solution was subjected to thin-film distillation at 130 ° C. and 0.04 kPa to remove unreacted HDI, and polyisocyanate P2 was obtained.

[0141] Polyisocyanate P2 had an NCO content of 15.9% by mass, was a transparent liquid in appearance, had a number average molecular weight of 1,350, an average functionality calculated from the NCO content and number average molecular weight of 5.1, a viscosity at 25°C of 4,000 mPa·s, and a free HDI content of 0.2% by mass. Polyisocyanate P2 was found to contain mainly allophanate-modified polyisocyanate and a small amount of isocyanurate-modified polyisocyanate by proton nuclear magnetic resonance ( １ The content of the isocyanurate-modified polyisocyanate was 2 mol % based on the total amount of the allophanate-modified polyisocyanate and the isocyanurate-modified polyisocyanate.

[0142] (Synthesis Example 3) A 1 L four-neck flask equipped with a stirrer, thermometer, condenser, and dropping funnel was charged with 870 g of HDI and 130 g of PCD-500 (polyhexamethylene polycarbonate diol, number average molecular weight 500), and the urethanization reaction was carried out for 2 hours at 80 ° C. under a nitrogen stream. Thereafter, 0.05 g of OctZr was added, and the allophanation reaction was carried out for 2 hours at 110 ° C. After the NCO content reached 39.1% by mass, 0.05 g of JP-508 was added to carry out a termination reaction, and the reaction solution was cooled to room temperature. This reaction solution was subjected to thin-film distillation at 130 ° C. and 0.04 kPa to remove unreacted HDI, and polyisocyanate P3 was obtained.

[0143] Polyisocyanate P3 had an NCO content of 13.2% by mass, a number average molecular weight of 1,450, an average functionality of 4.6 calculated from the NCO content and the number average molecular weight, a viscosity of 6,000 mPa·s at 25°C, and a free HDI content of 0.2% by mass. Polyisocyanate P3 was found to contain mainly allophanate-modified polyisocyanate and a small amount of isocyanurate-modified polyisocyanate by proton nuclear magnetic resonance ( １ The content of the isocyanurate-modified polyisocyanate was 3 mol % based on the total amount of the allophanate-modified polyisocyanate and the isocyanurate-modified polyisocyanate.

[0144] Synthesis of Acrylic Polyol (B) (Synthesis Example 4) 70 g of butyl acetate was charged into a 300 mL four-neck flask equipped with a stirrer, thermometer, condenser, and dropping funnel, and the temperature was raised to 120°C. Next, 38.0 g of methyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc., hereinafter referred to as "MMA"), 26.0 g of butyl acrylate (manufactured by Nippon Shokubai Co., Ltd., hereinafter referred to as "BA"), 31.0 g of 2-hydroxyethyl acrylate (manufactured by Nippon Shokubai Co., Ltd., hereinafter referred to as "2HEA"), 5.0 g of isobornyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., hereinafter referred to as "IBXA"), and 2 g of Perbutyl O (manufactured by NOF Corporation, t-butylperoxy-2-ethylhexanoate) were added to the dropping funnel to prepare a mixed solution, and this mixed solution was then added dropwise to a reaction vessel over 4 hours. The reaction solution was then maintained at 120°C for 1 hour. Next, 30 g of butyl acetate and 1 g of Perbutyl O were added to the dropping funnel to prepare a mixed solution, which was then added dropwise to the reaction vessel over 1 hour. The mixture was then maintained at 120°C for 3 hours and cooled to room temperature. This yielded a solution of acrylic polyol 1 (AP1).

[0145] The hydroxyl value of the acrylic polyol 1 in AP1 was measured by a method in accordance with JIS K1557 and was found to be 150.0 mgKOH / g. AP1 appeared as a transparent liquid, the solids content of AP1 (content of acrylic polyol 1) was 50 mass%, and the glass transition temperature (hereinafter referred to as "Tg") of acrylic polyol 1 was 15°C.

[0146] Synthesis Examples 5 to 10 Using the raw materials and their charging ratios shown in Table 1, the same operation as in Synthesis Example 4 was carried out to obtain solutions of acrylic polyols 2 to 7 (AP2 to 7, solid content: 50% by mass).

[0147]

[0148] Examples 1 to 10 and Comparative Examples 1 to 5 [Preparation of Coating Compositions] The materials shown in Tables 2 to 3 were mixed in the amounts (unit: g) shown in Tables 2 to 3 to prepare coating compositions 1 to 15 of Examples 1 to 10 and Comparative Examples 1 to 5, respectively. The ratio R in Tables 2 to 3 represents the number of moles of hydroxyl groups in the hydroxyl-containing compound contained in the coating composition (the sum of the number of moles of hydroxyl groups in the acrylic polyol and the number of moles of hydroxyl groups in the polydimethylsiloxane compound) [M ＯＨ ], the number of moles of isocyanate groups in the isocyanate group-containing compound contained in the coating composition (the number of moles of isocyanate groups in the organic polyisocyanate) [M ＮＣＯ ] ratio [M ＮＣＯ / M ＯＨ The Si content in Tables 2 and 3 indicates the SiO content in the coating composition measured by the above-mentioned method. ２ The converted silicon content (based on the total amount of organic polyisocyanate, acrylic polyol, and polydimethylsiloxane compound) is shown.

[0149] [Preparation of Coating Films] Each of coating compositions 1 to 15 was applied to an adherend under the following conditions, and the coating composition was cured to obtain the coating films of Examples 1 to 10 and Comparative Examples 1 to 5. The adherends used were acrylic resin plates (manufactured by Kuraray, 2 mm thick) or thermoplastic polyurethane films. (Coating Conditions) Coating method: using an applicator Humidity conditions: 50% RH Temperature conditions: 23°C Drying (curing) conditions: forced drying at 80°C for 5 hours Film thickness: approximately 20 μm

[0150] <Evaluation> The following evaluation tests 1 to 4 were carried out on the coating films of Examples 1 to 10 and Comparative Examples 1 to 5 obtained above. Evaluation tests 1, 3 and 4 used coating films prepared using an acrylic resin plate (2 mm thick, manufactured by Kuraray Co., Ltd.) as the adherend, while evaluation test 2 used a coating film prepared using a thermoplastic polyurethane film as the adherend.

[0151] (Evaluation Test 1: Coating Film Appearance (Smoothness)) In accordance with JIS Z8741, the gloss of the coating film at 60° was measured using a haze-gloss reflectometer (manufactured by BYK Additives & Instruments), and the coating film appearance was evaluated according to the following evaluation criteria. If the evaluation was A, the coating film appearance was deemed to be good. In this evaluation, good coating film appearance also essentially means that the smoothness is good. [Evaluation Criteria] A: Glossiness is 80% or more B: Glossiness is less than 80%

[0152] (Evaluation Test 2: Stain Resistance) The coating film surface was stained with a black marker manufactured by Sharpie Corporation, and then allowed to stand for 1 hour in an environment of a temperature of 23°C and a humidity of 50% RH. After standing, the stained coating film surface was wiped with gauze soaked in ethanol, and the color difference before and after staining was calculated from the following formula using a spectro2guide (manufactured by BYK-Gardner). Color difference = [(ΔL ＊ ) ２ + (Δa ＊ ) ２ + (Δb ＊ ) ２ ] １／２

[0153] The stain resistance was evaluated according to the following evaluation criteria. A rating of A was deemed to indicate good stain resistance. [Evaluation criteria] A: Color difference less than 1 B: Color difference 1 or more but less than 2 C: Color difference 2 or more

[0154] (Evaluation Test 3: Self-repairing property) In an environment of 23°C and 50% RH, the coating film was rubbed with a brass wire brush to scratch the surface of the coating film. The degree of scratch repair was observed visually, and the time until the scratch was completely repaired after scratching was measured. If the evaluation was A or B, the self-repairing property was deemed to be good. [Evaluation Criteria] A: The scratch was repaired within 1 hour at room temperature. B: The scratch was not repaired within 1 hour at room temperature, but when heated at 50°C, the scratch was repaired within 1 hour. C: The scratch was not repaired within 1 hour, whether at room temperature or when heated at 50°C.

[0155] (Evaluation Test 4: Adhesion) An adhesion test was carried out using a cross-cut method in accordance with JIS 5600-5-6, and the adhesion was evaluated according to the following evaluation criteria. If the evaluation was A, the adhesion was considered to be good. [Evaluation Criteria] A: Class 0 to 1 B: Class 2 to 5

[0156]

[0157]

[0158] Details of each raw material in Tables 2 to 3 are as follows: Polyisocyanates P1 to P3: Polyisocyanates P1 to P3 synthesized in Synthesis Examples 1 to 3 Polyisocyanate P4: HDI isocyanurate (trade name: Coronate HXR, manufactured by Tosoh Corporation) AP1 to AP7: Acrylic polyol solutions AP1 to AP7 synthesized in Synthesis Examples 4 to 10 U-CAT SA102: (manufactured by San-Apro Co., Ltd., urethane catalyst, 2-ethylhexanoate of DBU) BYK-SILCLEAN3700: (manufactured by BYK Japan, dimethylpolysiloxane-acrylic block copolymer, number average molecular weight: 7600, silicon content (SiO ２ Conversion rate: 1%)

Claims

1. An organic polyisocyanate (A) and an acrylic polyol (B), The organic polyisocyanate (A) contains a modified polyisocyanate (a), The modified polyisocyanate (a) is a reaction product of a polyisocyanate component (a1) and a polyol component (a2) or a modified product thereof, The polyisocyanate component (a1) contains an organic diisocyanate or a modified product thereof, the polyol component (a2) contains polytetramethylene glycol having a number average molecular weight of 200 to 750, The coating composition, wherein the acrylic polyol (B) contains an acrylic polyol (b) having a glass transition temperature of 5 to 30° C. and a hydroxyl value of more than 100 mg KOH / g and not more than 150 mg KOH / g.

2. The coating composition according to claim 1, wherein the average functionality of the modified polyisocyanate (a) is 4.0 to 6.

0.

3. The coating composition according to claim 1 or 2, wherein the polyisocyanate component (a1) comprises at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

4. The coating composition according to any one of claims 1 to 3, wherein the modified polyisocyanate (a) comprises an allophanate-modified polyisocyanate.

5. The coating composition of claim 4, wherein the modified polyisocyanate (a) further comprises an isocyanurate-modified polyisocyanate.

6. The coating composition according to any one of claims 1 to 5, further comprising a polydimethylsiloxane compound.

7. SiO ２ The coating composition according to claim 6, wherein the silicon content is 0.001 to 0.1 mass% based on the total amount of the organic polyisocyanate (A), the acrylic polyol (B), and the polydimethylsiloxane compound.

8. The coating composition according to any one of claims 1 to 7, wherein the ratio of the number of moles of isocyanate groups in the isocyanate group-containing compound contained in the coating composition to the number of moles of hydroxyl groups in the hydroxyl group-containing compound contained in the coating composition is 0.8 to 1.

3.

9. A kit for preparing the coating composition according to any one of claims 1 to 8, comprising: A kit comprising a first agent containing the organic polyisocyanate (A) and a second agent containing the acrylic polyol (B).

10. A coating film comprising a cured product of the coating composition according to any one of claims 1 to 8.

11. A method for forming a coating film, comprising applying the coating composition according to any one of claims 1 to 8 onto an adherend and curing the composition.