One-pack curable coating composition and coating method

Abstract

The present invention relates to a one-pack curable coating composition comprising a hydroxylated acrylic resin (A) having a hydroxyl value of 40-300 mgKOH / g, at least one crosslinking agent (B) selected from among blocked isocyanate compounds and melamine resins, a silicone resin (C) containing a hydrolyzable silyl group, a color pigment (D), and a curing catalyst (E).

Description

One-component curing coating composition and coating method

[0001] The present invention relates to a one-component curing coating composition and a coating method using the one-component curing coating composition.

[0002] In the coating materials for exterior building materials, when a high level of weather resistance is required, fluororesin-based coating compositions have been used up to now. However, due to legal restrictions such as PFAS regulations and instability in the supply of fluororesin, it is expected that the use of fluororesin will become difficult in the future. On the other hand, silicone resin-based coating materials are available as highly weather-resistant materials that can replace fluororesin, and they are attracting attention as highly weather-resistant materials that can replace fluororesin.

[0003] Patent Document 1 discloses a coating composition containing an acrylic resin, an epoxy resin having at least two epoxy groups in one molecule, an amine curing agent which may contain aminosilane, and a curing catalyst, with the aim of providing a coating composition which can form a coating film having excellent corrosion resistance and weather resistance at room temperature and in a single coating step in order to protect steel structures from corrosion and maintain their appearance in corrosion-resistant coating.

[0004] Furthermore, Patent Document 2 discloses a weather-resistant coating composition that contains a hydrolyzable silyl group-containing fluororesin, a hydrolyzable silyl group-containing acrylic resin, and a hydrolyzable silyl group-containing silicone resin, as a weather-resistant coating composition that is excellent in thick film coating properties and can form a coating film that is excellent in long-term weather resistance.

[0005] According to the coating compositions described in Patent Documents 1 and 2, a coating film having excellent weather resistance and corrosion resistance can be obtained, and when applied to steel structures and the like, the beauty of the structure can be maintained for a long period of time.

[0006] Japanese Patent Publication No. 2004-051943 Publication of Japanese Special Publication No. 2012-128223

[0007] However, the coating compositions described in Patent Documents 1 and 2 are essentially two-component curing coatings that dry at room temperature, and the one-component coatings required for exterior building material applications pose a problem in terms of weather resistance. Furthermore, exterior building material applications require high levels of coating film performance, such as boiling water resistance, that are not available for applications such as steel structures, and impact resistance is also required.

[0008] The problem to be solved by the present invention is to provide a one-component curing coating composition that has excellent coating film properties such as weather resistance, impact resistance, and boiling water resistance.

[0009] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by providing a one-component curable coating composition containing a hydroxyl-containing acrylic resin (A) having a hydroxyl value of 40 to 300 mgKOH / g, at least one crosslinking agent (B) selected from a blocked isocyanate compound and a melamine resin, a hydrolyzable silyl group-containing silicone resin (C), a color pigment (D), and a curing catalyst (E), and have thus completed the present invention.

[0010] That is, the gist of the present invention is as follows: 1. A one-component curable coating composition containing (A) a hydroxyl group-containing acrylic resin having a hydroxyl value of 40 to 300 mgKOH / g, (B) at least one crosslinking agent selected from a blocked isocyanate compound and a melamine resin, (C) a hydrolyzable silyl group-containing silicone resin, (D) a color pigment, and (E) a curing catalyst.

[0011] 2. A one-component curing coating composition according to item 1, wherein the hydroxyl-containing acrylic resin (A) is a hydroxyl-containing acrylic resin (AX) having both a hydroxyl group and a hydrolyzable silyl group.

[0012] 3. The one-component curing coating composition according to item 1 or 2, wherein the solubility parameter of the hydroxyl group-containing acrylic resin (A) is within the range of 7.0 to 12.0.

[0013] 4. The one-component curable coating composition according to any one of items 1 to 3, wherein the blocked isocyanate compound is a hydrolyzable silyl group-containing blocked isocyanate compound (BX).

[0014] 5. The one-component curing coating composition according to any one of items 1 to 4, further comprising castor oil (F).

[0015] 6. A coating method comprising coating a substrate with the one-component curable coating composition according to any one of items 1 to 5 above.

[0016] In the coating composition according to this embodiment, a specific hydroxyl group-containing acrylic resin is crosslinked with at least one crosslinking agent selected from a blocked isocyanate compound and a melamine resin, and further crosslinking occurs between the hydroxyl groups of the hydroxyl group-containing acrylic resin and the hydrolyzable silyl groups of the hydrolyzable silyl group-containing silicone resin, and also between the hydrolyzable silyl groups of the hydrolyzable silyl group-containing silicone resin, resulting in a crosslinked form in which the entire bulk is integrated, thereby achieving a one-component coating composition.

[0017] Furthermore, it is presumed that the hydrolyzable silyl group-containing silicone resin component is concentrated and unevenly distributed in the surface layer of the coating film made from the one-component curing coating composition, and that this results in the development of coating film performance, including particularly excellent weather resistance. Therefore, the coating composition according to this embodiment has the effect of providing a one-component curing coating composition that is excellent in coating film performance, such as weather resistance, impact resistance, and boiling water resistance.

[0018] The one-component curing coating composition according to this embodiment (hereinafter sometimes simply referred to as the "coating composition") is a one-component curing coating composition containing a hydroxyl group-containing acrylic resin (A) having a hydroxyl value of 40 to 300 mgKOH / g, at least one crosslinking agent (B) selected from a blocked isocyanate compound and a melamine resin, a hydrolyzable silyl group-containing silicone resin (C), a color pigment (D), and a curing catalyst (E). Details are provided below. In this specification, parts by mass and parts by weight, and mass% and weight% are synonymous.

[0019] <Hydroxyl Group-Containing Acrylic Resin (A)> The hydroxyl group-containing acrylic resin (A) in this embodiment preferably contains hydroxyl groups and has a hydroxyl value of 40 to 300 mgKOH / g. The hydroxyl group-containing acrylic resin (A) is usually a copolymer of a hydroxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer.

[0020] The copolymer can be obtained by any known method, such as bulk polymerization, suspension polymerization, solution polymerization in an organic solvent, emulsion polymerization in water, etc. Among these, solution polymerization in an organic solvent is preferably used.

[0021] The hydroxyl group-containing polymerizable unsaturated monomer is a compound having one or more hydroxyl groups and one or more polymerizable unsaturated bonds in one molecule, and specific examples thereof include monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; ε-caprolactone-modified products of the monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms; N-hydroxymethyl (meth)acrylamide; Examples of suitable dihydric alcohols include allyl alcohol, and compounds having one or more hydroxyl groups and one or more polymerizable unsaturated bonds per molecule, such as (meth)acrylates having a polyoxyalkylene chain with a hydroxyl group at the molecular terminal. However, the examples are not limited to the above. Furthermore, the number of carbon atoms in the dihydric alcohol having 2 to 8 carbon atoms is preferably 2 to 4. In this specification, "(meth)acrylate" refers to at least one of acrylate and methacrylate, "(meth)acrylic acid" refers to at least one of acrylic acid and methacrylic acid, "(meth)acrylamide" refers to at least one of acrylamide and methacrylamide, "(meth)acryloyl" refers to at least one of acryloyl and methacryloyl, and "(meth)acrylonitrile" refers to at least one of acrylonitrile and methacrylonitrile.

[0022] These may be used alone or in combination of two or more.

[0023] Of the above hydroxyl group-containing polymerizable unsaturated monomers, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc. can be preferably used from the viewpoint of coating film performance such as weather resistance, coating film hardness, chemical resistance, boiling water resistance, and impact resistance.

[0024] Furthermore, other polymerizable unsaturated monomers copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer include, for example, hydrolyzable silyl group-containing polymerizable unsaturated monomers which are compounds having one or more hydrolyzable silyl groups and one or more polymerizable unsaturated bonds in one molecule; carboxy group-containing polymerizable unsaturated monomers which are compounds having one or more carboxy groups and one or more polymerizable unsaturated bonds in one molecule, such as (meth)acrylic acid, maleic acid, crotonic acid, itaconic acid, fumaric acid, allyloxypropionic acid, 2-(meth)acryloylethylsuccinic acid, 3-butenoic acid, 4-pentenoic acid, 2-hexenoic acid, 3-hexenoic acid, 5-hexenoic acid, 2-heptenoic acid, 3-heptenoic acid, 3-octenoic acid, 2-nonenoic acid, 3-nonenoic acid, 9-decenoic acid, 10-undecenoic acid, 2-tridecenoic acid, and β-carboxyethyl acrylate; Alkyl or cycloalkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, and cyclododecyl (meth)acrylate; polymerizable unsaturated monomers having an isobornyl group, such as isobornyl (meth)acrylate; Polymerizable unsaturated monomers having an adamantyl group, such as adamantyl (meth)acrylate; vinyl aromatic compounds, such as styrene, α-methylstyrene, and vinyltoluene; perfluoroalkyl (meth)acrylates, such as perfluorobutylethyl (meth)acrylate and perfluorooctylethyl (meth)acrylate; polymerizable unsaturated monomers having a fluorinated alkyl group, such as fluoroolefin; polymerizable unsaturated monomers having a photopolymerizable functional group, such as a maleimide group;Vinyl compounds such as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, and vinyl acetate; nitrogen-containing polymerizable unsaturated monomers such as (meth)acrylonitrile, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, and adducts of glycidyl (meth)acrylate and amine compounds; polymerizable unsaturated monomers having two or more polymerizable unsaturated groups in one molecule such as allyl (meth)acrylate and 1,6-hexanediol di(meth)acrylate; epoxy group-containing polymerizable unsaturated monomers such as glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, and allyl glycidyl ether; (Meth)acrylates having a polyoxyalkylene chain whose molecular terminal is an alkoxy group; polymerizable unsaturated monomers having a sulfonic acid group, such as 2-acrylamido-2-methylpropanesulfonic acid, allylsulfonic acid, styrenesulfonic acid sodium salt, sulfoethyl methacrylate and its sodium salts and ammonium salts; polymerizable unsaturated monomers having a phosphoric acid group, such as 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, and 2-methacryloyloxypropyl acid phosphate; polymerizable unsaturated monomers having an ultraviolet absorbing functional group, such as 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, and 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole;UV-stable polymerizable unsaturated monomers such as 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, and 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine; Examples of polymerizable unsaturated monomer compounds having a carbonyl group include acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrene, and vinyl alkyl ketones having 4 to 7 carbon atoms (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone). However, the examples are not limited to the above. These can be used alone or in combination of two or more.

[0025] Among the other polymerizable unsaturated monomers copolymerizable with the above-mentioned hydroxyl group-containing polymerizable unsaturated monomer, the hydrolyzable silyl group-containing polymerizable unsaturated monomer is particularly suitable for use from the viewpoint of improving the reactivity with the hydrolyzable silyl group-containing silicone resin (C) (improving the crosslink density).

[0026] In this specification, the term "hydrolyzable silyl group" refers to a group that generates a silanol group by hydrolysis, and that the silanol group undergoes dehydration condensation to form a siloxane bond. There are no particular limitations on the silyl group, as long as it has both or either a monovalent hydrolyzable atom (an atom that generates a silanol group by reacting with water) directly bonded to a silicon atom and a monovalent hydrolyzable group (a group that generates a silanol group by reacting with water) directly bonded to a silicon atom.

[0027] Specific examples of the hydrolyzable silyl group include, but are not limited to, halogenated silyl groups such as chlorosilyl and bromosilyl, alkoxysilyl groups such as methoxysilyl, ethoxysilyl, propoxysilyl and butoxysilyl, and any combinations thereof.

[0028] Specific examples of hydrolyzable silyl group-containing polymerizable unsaturated monomers include vinyltri(C1-C6 alkoxy)silanes such as vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(2-methoxyethoxy)silane; vinyltri(C2-C6 alkanoyloxy)silanes such as vinyltriacetoxysilane; and (meth)acryloyloxyalkyltri-C1-C8 alkoxysilanes such as 2-(meth)acryloyloxyethyltrimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane (KBM-503), 3-(meth)acryloyloxypropyltriethoxysilane (KBE-503), and 8-(meth)acryloyloxyoctyltrimethoxysilane. However, the above is not intended to limit the scope of the present invention. In this specification, a notation consisting of a C and a number refers to the number of carbon atoms constituting the alkoxy group, alkanoyloxy group, or alkoxysilane. These may be used alone or in combination of two or more.

[0029] Among the hydrolyzable silyl group-containing polymerizable unsaturated monomers, silane compounds such as vinyltri(C1-C6 alkoxy)silane and (meth)acryloyloxyalkyltri-C1-C8 alkoxysilane are preferred from the viewpoint of coating film performance such as weather resistance, coating film hardness, chemical resistance, and impact resistance, and in particular (meth)acryloyloxyalkyltri-C1-C8 alkoxysilane can be more preferably used.

[0030] By forming a copolymer containing at least a hydroxyl group-containing polymerizable monomer and a hydrolyzable silyl group-containing polymerizable unsaturated monomer as constituent components, a hydroxyl group-containing acrylic resin (AX) having both a hydroxyl group and a hydrolyzable silyl group can be obtained.

[0031] From the viewpoint of coating film performance such as weather resistance, coating film hardness, chemical resistance, and impact resistance, the hydroxyl group-containing acrylic resin (AX) preferably contains 10 to 50 parts by mass, and more preferably 20 to 40 parts by mass, of the hydrolyzable silyl group-containing polymerizable unsaturated monomer relative to the total amount of all polymerizable unsaturated monomers. Here, the content is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and is preferably 50 parts by mass or less, and more preferably 40 parts by mass or less.

[0032] From the viewpoint of workability and coating film performance, the hydroxyl group-containing acrylic resin (A) preferably has a weight average molecular weight in the range of 3,000 to 50,000, particularly 5,000 to 40,000, and even more particularly 10,000 to 30,000. Here, the weight average molecular weight is preferably 3,000 or more, more preferably 5,000 or more, and even more preferably 10,000 or more, and is preferably 50,000 or less, more preferably 40,000 or less, and even more preferably 30,000 or less.

[0033] The "weight average molecular weight" in this specification is a value calculated based on the molecular weight of standard polystyrene from a chromatogram measured by gel permeation chromatography in accordance with the method described in JIS K 0124-2011.

[0034] The gel permeation chromatograph used is "HLC8120GPC" (manufactured by Tosoh Corporation). Four columns, "TSKgel G-4000HXL," "TSKgel G-3000HXL," "TSKgel G-2500HXL," and "TSKgel G-2000HXL" (all manufactured by Tosoh Corporation, trade names), are used, and measurements can be performed under the following conditions: mobile phase: tetrahydrofuran, measurement temperature: 40°C, flow rate: 1 ml / min, detector: RI.

[0035] From the viewpoints of curability and finished appearance, the hydroxyl value of the hydroxyl-containing acrylic resin (A) is preferably 40 to 300 mgKOH / g, particularly 60 to 250 mgKOH / g, and even more particularly 100 to 200 mgKOH / g. Here, the hydroxyl value is preferably 40 mgKOH / g or more, more preferably 60 mgKOH / g or more, and even more preferably 100 mgKOH / g or more, and is preferably 300 mgKOH / g or less, more preferably 250 mgKOH / g or less, and even more preferably 200 mgKOH / g or less.

[0036] From the viewpoint of coating film hardness and weather resistance, the glass transition temperature (Tg point) of the hydroxyl group-containing acrylic resin (A) is preferably −20° C. to 120° C., particularly preferably 0 to 100° C., and even more particularly preferably 40 to 90° C. Here, the Tg point is preferably −20° C. or higher, more preferably 0° C. or higher, and even more preferably 40° C. or higher, and is preferably 120° C. or lower, more preferably 100° C. or lower, and even more preferably 90° C. or lower.

[0037] In this specification, the glass transition temperature (absolute temperature) of the acrylic resin is a value calculated by the following formula.

[0038] 1 / Tg=W1 / T1+W2 / T2+...Wn / Tn, where W1, W2...Wn are the mass % of each monomer [=(amount of each monomer blended / total mass of monomers) x 100], and T1, T2...Tn are the glass transition temperatures (absolute temperatures) of the homopolymers of each monomer. The glass transition temperatures of the homopolymers of each monomer are values ​​according to the Polymer Hand Book (4th Edition). The glass transition temperatures of homopolymers of monomers not described in the document are measured by synthesizing a homopolymer of the monomer so as to have a weight-average molecular weight of about 50,000, and measuring the glass transition temperature using a differential scanning calorimetry "DSC-50Q" (trade name, manufactured by Shimadzu Corporation). The sample is placed in a measuring cup, and the solvent is removed by vacuum suction. The calorific value is then measured in the range of -100°C to +100°C at a heating rate of 3°C / min, and the first baseline change point on the low-temperature side is used.

[0039] From the viewpoints of compatibility with the hydrolyzable silyl group-containing silicone resin (C) and water resistance, the hydroxyl group-containing acrylic resin (A) preferably has a solubility parameter (SP value) of 7.0 to 12.0, more preferably 7.0 to 11.0, even more preferably 7.0 to 10.0, and even more preferably 8.0 to 10.0. Here, the solubility parameter is preferably 7.0 or more, more preferably 8.0 or more, and is preferably 12.0 or less, more preferably 11.0 or less, and even more preferably 10.0 or less.

[0040] The solubility parameter of a resin is numerically quantified based on a turbidity measurement method known to those skilled in the art, and specifically, can be determined in accordance with the formula of K. W. SUH and J. M. CORBETT (Journal of Applied Polymer Science, 12, 2359, 1968).

[0041] The hydroxyl group-containing acrylic resin (A) can be used alone or in combination of two or more kinds.

[0042] When the hydroxyl-containing acrylic resin (A) contains a hydroxyl-containing acrylic resin (AX), the content is preferably 1 to 100% by mass, more preferably 10 to 80% by mass, and even more preferably 20 to 50% by mass, based on the total solid content of the hydroxyl-containing acrylic resin (A). Here, the content is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. The content may be 100% by mass, i.e., the total amount of the hydroxyl-containing acrylic resin (A) may be the hydroxyl-containing acrylic resin (AX), or it may be 80% by mass or less, or 50% by mass or less.

[0043] <Crosslinking Agent (B)> The crosslinking agent (B) in this embodiment is at least one selected from a blocked isocyanate compound and a melamine resin, and is a component that undergoes a crosslinking reaction with the hydroxyl group-containing acrylic resin (A).

[0044] The blocked isocyanate compound is a compound obtained by blocking the free isocyanate groups of an isocyanate compound with a blocking agent.

[0045] Examples of the isocyanate compound include, but are not limited to, aliphatic isocyanate compounds, alicyclic isocyanate compounds, araliphatic isocyanate compounds, aromatic isocyanate compounds and crude products thereof, and modified products of these isocyanate compounds.

[0046] Specific examples of the aliphatic isocyanate compound include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl)fumarate, bis(2-isocyanatoethyl)carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate, but are not limited to the above.

[0047] Specific examples of the alicyclic isocyanate compound include isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis(2-isocyanatoethyl)-4-cyclohexene-1,2-dicarboxylate, 2,5- and / or 2,6-norbornane diisocyanate, etc. However, the compounds are not limited to the above.

[0048] Specific examples of the araliphatic isocyanate compound include m- and / or p-xylylene diisocyanate (XDI), α,α,α',α'-tetramethylxylylene diisocyanate (TMXDI), etc. However, the compounds are not limited to these.

[0049] Specific examples of aromatic isocyanate compounds include 1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4'- and / or 4,4'-biphenylmethane diisocyanate (MDI), 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, crude MDI, 1,5-naphthylene diisocyanate, 4,4',4"-triphenylmethane triisocyanate, m- and p-isocyanatophenylsulfonyl isocyanate, and the like. However, the compounds are not limited to the above.

[0050] Examples of the modified product include biuret modified products, isocyanurate modified products, and mixtures of two or more of these.

[0051] As the isocyanate compound, from the viewpoint of coating film performance such as weather resistance, coating film hardness, chemical resistance, and impact resistance, hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) can be preferably used.

[0052] Examples of blocking agents that block isocyanate groups include: phenol-based agents such as phenol, cresol, and xylenol; lactam-based agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; alcohol-based agents such as methanol, ethanol, n- or i-propyl alcohol, n-, i-, or t-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and benzyl alcohol; oxime-based agents such as formamidoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime; and pyrazole-based agents such as 3,5-dimethylpyrazole, 1,5-dimethylpyrazole, and 3,4-dimethylpyrazole. Examples of blocking agents include active methylene-based agents such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone, but are not limited to the above.

[0053] Among the above blocking agents, oxime-based, lactam-based, pyrazole-based, and active methylene-based blocking agents are preferably used from the viewpoint of curability. In particular, methyl ethyl ketoxime, dimethylpyrazoles such as 3,5-dimethylpyrazole, 1,5-dimethylpyrazole, and 3,4-dimethylpyrazole, and diethyl malonate are preferably used.

[0054] By mixing the isocyanate compound with the blocking agent, the free isocyanate groups of the isocyanate compound can be easily blocked.

[0055] In the coating composition according to this embodiment, the blocked isocyanate compound (BX) containing a hydrolyzable silyl group can be suitably used as the blocked isocyanate compound from the viewpoint of imparting reactivity with the hydrolyzable silyl group-containing silicone resin (C), and forming a stronger crosslinked structure by crosslinking through siloxane bonds through a condensation reaction, thereby integrating the entire bulk.

[0056] The blocked isocyanate compound (BX) containing a hydrolyzable silyl group includes all blocked isocyanate compounds in which the above-mentioned blocked isocyanate compounds further contain a hydrolyzable silyl group.

[0057] Specific examples of the hydrolyzable silyl group include, but are not limited to, halogenated silyl groups such as chlorosilyl and bromosilyl, alkoxysilyl groups such as methoxysilyl, ethoxysilyl, propoxysilyl and butoxysilyl, and any combinations thereof.

[0058] As the hydrolyzable silyl group, an alkoxysilyl group is preferred from the viewpoint of curability.

[0059] As the blocking agent for the hydrolyzable silyl group-containing blocked isocyanate compound (BX), from the viewpoint of coating film performance such as weather resistance, coating film hardness, chemical resistance, and impact resistance, blocking agents such as ethanol, caprolactam, dimethylpyrazole, etc., particularly a hydrolyzable silyl group-containing caprolactam-blocked isocyanate compound, can be preferably used.

[0060] Commercially available hydrolyzable silyl group-containing blocked isocyanate compounds (BX) include X-12-1195, X-12-1293, and X-12-1308ES (all of which are trade names manufactured by Shin-Etsu Chemical Co., Ltd.).

[0061] When the coating composition according to this embodiment contains a hydrolyzable silyl group-containing blocked isocyanate compound (BX), the solids content is preferably 1 to 100% by mass, more preferably 20 to 80% by mass, and even more preferably 30 to 60% by mass, based on the total solids content of the blocked isocyanate compound (B). Here, the content is preferably 1% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. The content may be 100% by mass, i.e., the total amount of the blocked isocyanate compound (B) may be the hydrolyzable silyl group-containing blocked isocyanate compound (BX), or it may be 80% by mass or less, or 60% by mass or less.

[0062] From the viewpoint of curability, the number average molecular weight of the blocked isocyanate compound is preferably 100 to 10,000, particularly preferably in the range of 100 to 5,000. The number average molecular weight is preferably 100 or more, and is preferably 10,000 or less, more preferably 5,000 or less.

[0063] The blocked isocyanate compounds can be used alone or in combination of two or more.

[0064] The melamine resin may include a methylol melamine resin obtained by reacting melamine with an aldehyde.

[0065] Examples of the aldehyde used in the above reaction include, but are not limited to, formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde.

[0066] Furthermore, the above methylol melamine resins etherified with alcohols can also be used as the melamine resin.

[0067] Examples of alcohols used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, 2-ethylhexanol, etc. However, the alcohols are not limited to the above.

[0068] As the melamine resin, from the viewpoints of compatibility and coating hardness, a melamine resin containing a methyl ether group etherified with methyl alcohol, or a melamine resin containing a methyl ether group and a butyl ether group etherified with methyl alcohol and butyl alcohol can be preferably used.

[0069] Furthermore, from the viewpoints of finished appearance such as smoothness and image clarity, and coating film performance such as weather resistance, the melamine resin preferably has a weight-average molecular weight of 400 to 4,000, more preferably 500 to 3,000, and even more preferably 600 to 2,000. Here, the weight-average molecular weight is preferably 400 or more, more preferably 500 or more, and even more preferably 600 or more, and is preferably 4,000 or less, more preferably 3,000 or less, and even more preferably 2,000 or less.

[0070] Specific examples of the melamine resin include methyl etherified melamine resins such as CYMEL (registered trademark) 300, 303, 325, 327, 350, 730, 736, and 738 (all manufactured by Mitsui Cytec Co., Ltd., trade names), Melan 522 and 523 (all manufactured by Hitachi Chemical Co., Ltd., trade names), Nikalac MS001, MX430, and MX650 (all manufactured by Sanwa Chemical Co., Ltd., trade names), Sumimar M-55, M-100, and M-40S (all manufactured by Sumitomo Chemical Co., Ltd., trade names), and Resimin 740 and 747 (all manufactured by Monsanto Co., Ltd., trade names); Butyl etherified melamine resins such as U-BAN (registered trademark) 20SE and 225 (all of which are trade names manufactured by Mitsui Toatsu Co., Ltd.), Super Beckamin J820-60, Super Beckamin L-117-60, Super Beckamin L-109-65, Super Beckamin 47-508-60, Super Beckamin L-118-60, and Super Beckamin G821-60 (all of which are trade names manufactured by Dainippon Ink and Chemicals, Inc.); Examples of suitable etherified melamine resins include mixed etherified melamine resins of methyl ether and butyl ether, such as CYMEL (registered trademark) 232, 266, XV-514, and 1130 (all of which are trade names manufactured by Mitsui Cytec Co., Ltd.), Nikalac MX500, MX600, MS35, and MS95 (all of which are trade names manufactured by Sanwa Chemical Co., Ltd.), Resimin 753 and 755 (all of which are trade names manufactured by Monsanto Co.), and Sumimar M-66B (trade name manufactured by Sumitomo Chemical Co., Ltd.). However, the examples are not limited to the above.

[0071] The melamine resins may be used alone or in combination of two or more.

[0072] When a blocked isocyanate compound and a melamine resin are used in combination as a crosslinking agent, from the viewpoint of coating film performance such as weather resistance, coating film hardness, chemical resistance, and impact resistance, the solids concentration of the blocked isocyanate compound is preferably more than 0% by mass and less than 100% by mass, more preferably 1 to 99% by mass, even more preferably 30 to 80% by mass, and even more preferably 50 to 70% by mass, based on the total solids content of both. Similarly, the solids concentration of the melamine resin is preferably more than 0% by mass and less than 100% by mass, more preferably 1 to 99% by mass, even more preferably 20 to 70% by mass, and even more preferably 30 to 50% by mass. Here, the solids concentration of the blocked isocyanate compound is preferably more than 0% by mass, more preferably 1% by mass or more, even more preferably 30% by mass or more, and even more preferably 50% by mass or more, and preferably less than 100% by mass, more preferably 99% by mass or less, even more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0073] <Hydrolyzable Silyl Group-Containing Silicone Resin (C)> In this embodiment, the hydrolyzable silyl group-containing silicone resin (C) is a resin that contains a hydrolyzable silyl group and has a polysiloxane skeleton.

[0074] The hydrolyzable silyl group-containing silicone resin (C) is, for example, a silicone resin represented by the following formula (1): SiX ｎ Y ４－ｎ The organosilane compound is a resin, such as an oligomer, produced by chemically bonding two or more identical or different organosilanes represented by formula (1): (wherein X represents a hydroxyl group or an alkoxy group, Y represents a monovalent hydrocarbon group which may have a substituent, and n represents an integer of 1 to 4).

[0075] In the hydrolyzable silyl group-containing silicone resin (C), the organosilane represented by formula (1) can be bonded in a linear or branched chain. Furthermore, the hydrolyzable silyl group-containing silicone resin (C) preferably has a hydrocarbon group directly bonded to a silicon atom.

[0076] Examples of organosilanes represented by formula (1) include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-(3,4-epoxycyclohexyl)ethyltriethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, phenyltrimethoxysilane, phenyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, β-cyano Ethyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, dimethyldichlorosilane, diphenyldichlorosilane, methylphenyldimethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, γ-aminopropyltriethoxysilane, 4-aminobutyltriethoxysilane, p-aminophenyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, aminoethylaminomethylphenethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2-(3,Examples of the silane include (4-epoxycyclohexyl)ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 4-aminobutyltriethoxysilane, N-(6-aminohexyl)aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltrichlorosilane, (p-chloromethyl)phenyltrimethoxysilane, 4-chlorophenyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, styrylethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, trifluoropropyltrimethoxysilane, and any combination thereof. However, the examples are not limited to the above.

[0077] From the viewpoints of compatibility with the hydroxyl group-containing acrylic resin (A) and the weather resistance of the coating film formed, the hydrolyzable silyl group-containing silicone resin (C) preferably has a methyl group and / or a phenyl group directly bonded to a silicon atom.

[0078] Commercially available hydrolyzable silyl group-containing silicone resins (C) include, for example, "DOWSIL (trademark) SR2406," "DOWSIL (trademark) SR2410," "DOWSIL (trademark) SR2420," "DOWSIL (trademark) SR2416," "DOWSIL (trademark) SR2402," "DOWSIL (trademark) AY42-161," "DOWSIL (trademark) 3074," and "DOWSIL (trademark) SR2406." 3037" (all trade names, manufactured by Dow Corning Toray Silicone Co., Ltd.), "FZ-3704" and "FZ-3511" (all trade names, manufactured by Nippon Unicar Co., Ltd.), "KC-89S", "KR-500", "X-40-9225", "X-40-9246", "X-40-9250", "KR-217", "KR-9218", "KR-213", "KR-510", "X-40-9227", "X-40-9247", "X-41-1053", "X-41-1056", "X-41-1 805", "X-41-1810", "X-40-2651", "X-40-2308", "X-40-9238", "X-40-2239", "X-40-2327", "KR-400", "X-40-175" and "X-40-9740" (all of which are product names manufactured by Shin-Etsu Chemical Co., Ltd.), "XR31-B2733", "XR31-B1410", "XC96-B0446", "TSR-165", "XR31-B2230" (all of which are product names manufactured by Momentive Corporation), and the like. However, examples thereof are not limited to the above.

[0079] <Coloring Pigment (D)> The coloring pigment (D) is contained in order to give the coating film obtained from the coating composition according to this embodiment a desired color.

[0080] Specific examples of color pigments include titanium oxide, carbon black, yellow lead, yellow ochre, yellow iron oxide, Hansa Yellow, Pigment Yellow, chrome orange, chrome vermilion, permanent orange, amber, permanent red, brilliant carmine, fast violet, methyl violet lake, ultramarine, Prussian blue, cobalt blue, phthalocyanine blue, pigment green, naphthol green, and aluminum paste, but are not limited to these.

[0081] These may be used alone or in combination of two or more.

[0082] In particular, when titanium oxide is used as a color pigment, from the viewpoint of the weather resistance of the coating film, titanium oxide that has been surface-treated with silica, alumina, zirconia, selenium, an organic component (such as a polyol), etc. is preferably used. The amount of surface treatment is preferably such that the titanium oxide content falls within the range of 83 to 95 mass %.

[0083] Commercially available surface-treated titanium oxide products include "TIPAQUE (registered trademark) PFC105" and "TIPAQUE CR95" (all trade names, manufactured by Ishihara Sangyo Kaisha), "D918" (trade name, manufactured by Sakai Chemical Industry Co., Ltd.), "TITANIX WP0038" and "TITANIX JR805" (all trade names, manufactured by Teika Corporation), "Ti-Pure R960" and "Ti-Select TS-6200" (all trade names, manufactured by DuPont), but are not limited to these.

[0084] <Curing catalyst (E)> The coating composition according to this embodiment contains a curing catalyst from the viewpoints of curability and the weather resistance of the resulting coating film. The curing catalyst (E) is blended to promote the reaction between the hydroxyl group-containing acrylic resin (A) and the crosslinking agent (B), and to promote the hydrolysis and condensation of the hydrolyzable silyl group-containing silicone resin (C).

[0085] For melamine resins, sulfonic acid compounds or amine-neutralized products of sulfonic acid compounds, alkyl phosphoric acid compounds or amine-neutralized products of alkyl phosphoric acid compounds can be suitably used.

[0086] Typical examples of sulfonic acid compounds include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and dinonylnaphthalenedisulfonic acid.

[0087] Representative examples of alkyl phosphate compounds include dodecyl phosphate, tetradecyl phosphate, and stearyl phosphate.

[0088] The amine in the neutralized product may be any of primary amines, secondary amines, and tertiary amines. Among these, amine-neutralized products of p-toluenesulfonic acid and / or dodecylbenzenesulfonic acid, and amine-neutralized products of alkylphosphate compounds are preferably used from the viewpoints of paint stability, reaction acceleration effect, and the performance of the resulting coating film.

[0089] For the blocked isocyanate compound and the hydrolyzable silyl group-containing silicone resin (C), examples of organometallic compounds include tin octoate, dibutyltin di(2-ethylhexanoate), dioctyltin di(2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, monobutyltin trioctate, lead 2-ethylhexanoate, and zinc octoate, but are not limited to these.

[0090] <Castor Oil (F)> The coating composition according to this embodiment preferably contains castor oil (F) from the viewpoint of the recoat adhesion of the coating film formed.

[0091] Castor oil (F) is a vegetable oil made from castor bean seeds, and is a glyceride of unsaturated fatty acids such as ricinoleic acid and oleic acid, and saturated fatty acids such as palmitic acid.

[0092] In this specification, castor oil (F) includes natural castor oil, synthetic castor oil and castor oil derivatives.

[0093] As the synthetic castor oil, castor oil-based polyol (F') can be suitably used.

[0094] The castor oil-based polyol (F') is not particularly limited, but examples thereof include castor oil, alkylene oxide adducts of castor oil, and esters of castor oil fatty acids with hydroxyl group-containing compounds.

[0095] As the castor oil-based polyol (F'), commercially available products can be used. Examples of commercially available trade names include "URIC H-30", "URIC H-31", "URIC H-52", "URIC H-57", "URIC H-62", "URIC H-73X", "URIC H-81", "URIC H-102", "URIC H-420", "URIC H-854", "URIC H-870", "URIC H-1823", "URIC H-1824", "URIC H-1830", "URIC HF-1300", "URIC POLYCASTOR #10", and "URIC POLYCASTOR #30" (all trade names, manufactured by Ito Oil Mills), "TLM", "LM-R", "ELA-DR", "HS CM", "HS 2G-120", and "HS Examples of such oils include "HS 2G-160R," "HS 2G-270B," "HS KA-001," "HS CM-025P," "HS CM-075P," and "HS 3G-500B" (all trade names, manufactured by Toyokuni Oil Mills), "SOVERMOL (registered trademark) 805," "SOVERMOL (registered trademark) 815," "SOVERMOL (registered trademark) 819," "SOVERMOL (registered trademark) 830," "SOVERMOL (registered trademark) 1005," and "SOVERMOL (registered trademark) 1092" (all trade names, manufactured by BASF). However, the oils are not limited to the above.

[0096] The castor oil-based polyols (F') can be used either alone or in combination of two or more.

[0097] From the viewpoints of recoat adhesion, curing ability, and finished appearance of the coating film formed, the hydroxyl value of the castor oil (F) is preferably in the range of 80 to 230 mgKOH / g, more preferably in the range of 90 to 215 mgKOH / g, and even more preferably in the range of 100 to 200 mgKOH / g. Here, the hydroxyl value is preferably 80 mgKOH / g or more, more preferably 90 mgKOH / g or more, and even more preferably 100 mgKOH / g or more, and is preferably 230 mgKOH / g or less, more preferably 215 mgKOH / g or less, and even more preferably 200 mgKOH / g or less.

[0098] <Coating Composition> In terms of curability and weather resistance, the coating composition according to this embodiment is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, and even more preferably 40 to 70% by mass, based on the total solid content of the hydroxyl-containing acrylic resin (A), crosslinker (B), and hydrolyzable silyl-group-containing silicone resin (C). The total solid content of the hydroxyl-containing acrylic resin (A) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. The total solid content is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. The total solid content of the crosslinker (B) is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, and even more preferably 15 to 30% by mass. Here, the total solid content is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The total solid content of the hydrolyzable silyl group-containing silicone resin (C) is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, and even more preferably 20 to 40% by mass. Here, the total solid content is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. The total solid content of the color pigment (D) is preferably 10 to 200% by mass, more preferably 30 to 150% by mass, and even more preferably 40 to 100% by mass. Here, the total solid content is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and preferably 200% by mass or less, more preferably 150% by mass or less, and even more preferably 100% by mass or less. The total solid content of the curing catalyst (E) is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 2.0% by mass, and even more preferably 0.1 to 1.0% by mass. Here, the total solid content is preferably 0.1% by mass or more, and preferably 5.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less.

[0099] A preferred combination of the content ratios of the above-mentioned components is, for example, based on the total solid content of the hydroxyl group-containing acrylic resin (A), the crosslinking agent (B), and the hydrolyzable silyl group-containing silicone resin (C), that the total solid content of the hydroxyl group-containing acrylic resin (A) is 20 to 90 mass %, the total solid content of the crosslinking agent (B) is 5 to 50 mass %, the total solid content of the hydrolyzable silyl group-containing silicone resin (C) is 5 to 60 mass %, the total solid content of the color pigment (D) is 10 to 200 mass %, and the total solid content of the curing catalyst (E) is 0.1 to 5.0 mass %.

[0100] In addition to the above, when the coating composition according to this embodiment further contains castor oil (F), the content of castor oil (F) is preferably within the range of 1 to 10 parts by mass, more preferably within the range of 2 to 8 parts by mass, and even more preferably within the range of 3 to 7 parts by mass, based on 100 parts by mass of the total solid content of the hydroxyl group-containing acrylic resin (A), the crosslinking agent (B), and the hydrolyzable silyl group-containing silicone resin (C), from the viewpoint of the recoat adhesion of the formed coating film, etc. Here, the content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less.

[0101] In this specification, the term "solid content" refers to the residue remaining after removing volatile components, and the residue may be in a solid form at room temperature or in a fluid liquid form. The solid content mass can be calculated by multiplying the sample mass before drying by the solid content percentage, which is the ratio of the amount of material remaining after drying to the mass before drying.

[0102] Drying conditions include heating 3 grams of the sample at 105° C. for 3 hours.

[0103] Furthermore, the coating composition according to this embodiment may contain, as optional components, dehydrating agents; pigments (excluding the color pigment (D)); modifying resins such as acrylic resins, fluororesins, alkyd resins, and urethane resins (excluding the hydroxyl group-containing acrylic resin (A), at least one crosslinking agent (B) selected from blocked isocyanate compounds and melamine resins, and the hydrolyzable silyl group-containing silicone resin (C)); organic solvents; reactive diluents; adhesion promoters, antisettling agents, dispersants, wetting agents, UV absorbers, light stabilizers, antioxidants, surface conditioners, antifoaming agents, surfactants, preservatives, and coating additives such as antifreeze agents.

[0104] Dehydrating agents are used to improve storage stability and to prevent deterioration of the paint due to moisture present in the paint or in the air, and specific examples include trimethyl orthoacetate and trimethyl orthoformate, but are not limited to these.

[0105] From the viewpoint of storage stability and curability of the coating material, the content of the dehydrating agent may be 0 to 20% by mass, 5 to 15% by mass, or 5 to 10% by mass, based on the total solid content of the hydroxyl group-containing acrylic resin (A), the crosslinking agent (B), and the hydrolyzable silyl group-containing silicone resin (C). Here, the content may be 0% by mass or more, more than 0% by mass, or 5% by mass or more, and may be 20% by mass or less, 15% by mass or less, or 10% by mass or less.

[0106] Examples of the pigments (excluding the color pigment (D)) include extender pigments such as talc, silica, calcium carbonate, mica, kaolin, barium sulfate, and zinc oxide; and anti-rust pigments. However, the pigments are not limited to the above. These can be used alone or in combination of two or more.

[0107] Known ultraviolet absorbers can be used, including, for example, benzotriazole-based absorbers, triazine-based absorbers, salicylic acid derivative-based absorbers, and benzophenone-based absorbers. By incorporating an ultraviolet absorber, the weather resistance of the coating film can be improved. However, the ultraviolet absorber is not limited to the above.

[0108] The content of the ultraviolet absorber in the coating composition may usually be 0 to 10 mass%, 0.2 to 5 mass%, or 0.3 to 2 mass%, relative to the total amount of resin solids. Here, the content may be 0 mass% or more, more than 0 mass%, 0.2 mass% or more, or 0.3 mass% or more, or 10 mass% or less, 5 mass% or less, or 2 mass% or less.

[0109] As the light stabilizer, a conventionally known light stabilizer can be used, for example, a hindered amine light stabilizer can be mentioned, but is not limited thereto. By adding a light stabilizer, the weather resistance, yellowing resistance, etc. of the coating film can be improved.

[0110] The content of the light stabilizer in the coating composition may usually be 0 to 10% by mass, 0.2 to 5% by mass, or 0.3 to 2% by mass, based on the total amount of resin solids. Here, the content may be 0% by mass or more, more than 0% by mass, 0.2% by mass or more, 0.3% by mass or more, or 10% by mass or less, 5% by mass or less, or 2% by mass or less.

[0111] The coating composition according to this embodiment can be produced by mixing the hydroxyl group-containing acrylic resin (A), at least one crosslinking agent (B) selected from a blocked isocyanate compound and a melamine resin, the hydrolyzable silyl group-containing silicone resin (C), the color pigment (D), and the curing catalyst (E), as well as other optional components used as needed, using a mixing device such as a disper or homogenizer.

[0112] The coating composition according to this embodiment can be applied by a coating method such as, for example, dip coating, brush coating, roll brush coating, spray coating, roll coating, spin coating, dip coating, bar coating, flow coating, electrostatic coating, airless coating, electrodeposition coating, die coating, etc. However, the methods are not limited to those mentioned above.

[0113] The present invention also relates to a coating method for applying the above-mentioned coating composition. In the coating method according to this embodiment, the above-mentioned one-component curing coating composition is applied to a substrate. The coating film thickness of the coating composition can be set as desired depending on the substrate and the required coating film performance, but is typically 10 to 100 μm, and preferably in the range of 20 to 60 μm. Here, the coating film thickness may be 10 μm or more, or 20 μm or more, or may be 100 μm or less, or 60 μm or less.

[0114] The coating film of the coating composition in this embodiment can be cured by heating for 5 to 40 minutes, and particularly 10 to 30 minutes, typically at a temperature in the range of 100 to 200°C, and particularly 130 to 180°C. The temperature for curing the coating film may be 100°C or higher, or 130°C or higher, or may be 200°C or lower, or 180°C or lower. The time for curing the coating film may be 5 minutes or longer, 10 minutes or longer, or 40 minutes or shorter, or 30 minutes or shorter.

[0115] The surface to be coated with the coating composition of this embodiment is not particularly limited, and examples include metal materials that have been primed as desired, such as steel sheets such as cold-rolled steel sheets, black steel sheets, alloyed galvanized steel sheets, and electrogalvanized steel sheets, zinc plating, stainless steel, aluminum, etc., alkaline substrates such as concrete, mortar, slate, slate roofing tiles, ceramic building materials, plastics, etc. However, the surface is not limited to the above.

[0116] The application of the coating composition according to this embodiment is not particularly limited, but it can be particularly suitably used as a topcoat coating for exterior building walls, civil engineering and construction materials, vehicle and aircraft materials, etc., particularly for exterior building materials such as building materials.

[0117] The above-mentioned coating surface and coating object may be subjected to shot blasting, surface conditioning, surface treatment, etc., and may also be coated with a primer, if necessary.

[0118] The primer coating may include water-based or solvent-based primer coatings known in the art.

[0119] Specific examples of the primer paint include, but are not limited to, epoxy resin paint, modified epoxy resin paint, epoxy resin-based glass flake paint, epoxy resin coating material, phthalic acid resin-based paint, and epoxy ester resin paint.

[0120] The coating composition according to this embodiment is a non-fluororesin, one-component curing coating composition that exhibits excellent coating film performance, such as weather resistance, impact resistance, and boiling water resistance, and is also easy to handle. Therefore, it can be particularly suitably used as a topcoat coating that complies with PFAS regulations for the above-mentioned substrates.

[0121] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. In each example, "parts" means parts by mass and "%" means % by mass.

[0122] <Production of Coating Compositions> Example 1: Production of Coating Composition No. 1 50 parts (solid content) of a hydroxyl group-containing acrylic resin (A-1), 20 parts (solid content) of a blocked isocyanate compound (B-1), 30 parts (solid content) of a hydrolyzable silyl group-containing silicone resin (C-1), 90 parts (solid content) of a color pigment (D-1) (PFC-105, titanium oxide, manufactured by Ishihara Sangyo Kaisha), 0.2 parts (solid content) of a curing catalyst (E-1) (TOS-TK1, organotin compound, manufactured by Osaka Shinyaku Co., Ltd.), 1.5 parts (solid content) of an ultraviolet absorber (Ti400, Note 2), and 1 part (solid content) of a light stabilizer (Ti123, Note 3) were mixed and stirred, and the solid content concentration was adjusted with a solvent to obtain a coating composition No. 1 having a solid content of 60% by mass.

[0123] In the above, the color pigment (D-1) was added and mixed as a pigment dispersion paste prepared using 20 parts (solid content) of 50 parts (solid content) of the hydroxyl group-containing acrylic resin (A-1).

[0124] Examples 2 to 53 and Comparative Examples 1 to 6: Production of Coating Compositions No. 2 to 59 Coating compositions No. 2 to No. 59 each having a solids content of 60 mass% were obtained in the same manner as in Example 1, except that the raw materials were blended as shown in Tables 1 to 6.

[0125] The raw material compositions (values) in Tables 1 to 6 are solid content masses. Blanks in the tables indicate that no ingredients were added.

[0126] Details of each raw material are as follows:

[0127] Hydroxyl group-containing acrylic resin (A-1): styrene / t-butyl methacrylate / 2-ethylhexyl acrylate / isobornyl acrylate / hydroxyethyl methacrylate / = 30 / 9 / 3 / 30 / 28 (mass ratio) copolymer butyl acetate solution, hydroxyl value 121 mg KOH / g, weight average molecular weight 8000, glass transition temperature 79 ° C, SP value 8.9, solid content 60%. Hydroxyl group-containing acrylic resin (A-2): styrene / isobutyl methacrylate / 2-ethylhexyl acrylate / 2-hydroxypropyl methacrylate / methyl acrylate = 20 / 33.3 / 1 / 45 / 0.7 (mass ratio) copolymer butyl acetate solution, hydroxyl value 175 mg KOH / g, weight average molecular weight 8000, glass transition temperature 46 ° C, SP value 8.8, solid content 60%. Hydroxyl-containing acrylic resin (A-3): styrene / isobutyl methacrylate / butyl acrylate / hydroxyethyl methacrylate / =40 / 25 / 18 / 16 (mass ratio) copolymer in butyl acetate solution, hydroxyl value 69 mg KOH / g, weight average molecular weight 13,000, glass transition temperature 42 ° C, SP value 9.0, solids content 60%. Hydroxyl-containing acrylic resin (A-4): styrene / 2-ethylhexyl methacrylate / 2-ethylhexyl acrylate / hydroxyethyl methacrylate / =20 / 32 / 10 / 38 (mass ratio) copolymer in butyl acetate solution, hydroxyl value 141 mg KOH / g, weight average molecular weight 6,000, glass transition temperature 17 ° C, SP value 8.9, solids content 60%. Hydroxyl group-containing acrylic resin (A-5): butyl acetate solution of a copolymer of methyl methacrylate / styrene / ethyl acrylate / hydroxyethyl methacrylate / =38 / 25 / 4.5 / 32.5 (mass ratio), hydroxyl value 140 mg KOH / g, weight average molecular weight 30,000, glass transition temperature 80°C, SP value 10.0, solids content 60%.

[0128] Hydroxyl group-containing acrylic resin (A-6): butyl acetate solution of a copolymer of methyl methacrylate / ethyl acrylate / hydroxyethyl methacrylate / Cardura E = 68 / 15 / 7 / 10 (mass ratio), hydroxyl value 31 mg KOH / g, weight average molecular weight 470,000, glass transition temperature 72 ° C, SP value 9.2, solid content 60%. Hydroxyl group-containing acrylic resin (A-7): butyl acetate solution of a copolymer of styrene / 2-ethylhexyl acrylate / hydroxyethyl methacrylate = 10 / 20 / 70 (mass ratio), hydroxyl value 301 mg KOH / g, weight average molecular weight 9,000, glass transition temperature 22 ° C, SP value 9.4, solid content 60%.

[0129] Hydroxyl group-containing acrylic resin (AX-1): butyl acetate solution of a copolymer of styrene / methyl methacrylate / butyl acrylate / 2-ethylhexyl acrylate / hydroxyethyl methacrylate / 3-methacryloyloxypropyltrimethoxysilane=15 / 1 / 1 / 15 / 38 / 30 (mass ratio), hydroxyl value 164 mg KOH / g, weight average molecular weight 9000, glass transition temperature 12°C, SP value 9.1, solids content 60%.

[0130] Blocked isocyanate compound (B-1): "Desmodur (registered trademark) BL-3175", trade name, manufactured by COVESTRO, methyl ethyl ketoxime blocked HDI isocyanurate, NCO content 11.2%.

[0131] Blocked isocyanate compound (B-2): "DURANATE SBN-70D", trade name, manufactured by Asahi Kasei Corporation, dimethylpyrazole blocked HDI isocyanurate, NCO content 10.0%.

[0132] Melamine resin (B-3): "CYMEL (registered trademark) 325", product name, manufactured by Allnex, imino group-containing methyl etherified melamine resin. Weight average molecular weight: 650

[0133] Melamine resin (B-4): imino group-containing methyl / butyl etherified melamine resin. Weight average molecular weight: 750

[0134] Blocked isocyanate compound (BX-1): "X-12-1293", trade name, manufactured by Shin-Etsu Chemical Co., Ltd., a hydrolyzable silyl group-containing methyl ethyl ketoxime blocked isocyanate compound (monoisocyanate). Blocked isocyanate compound (BX-2): "X-12-1308ES", trade name, manufactured by Shin-Etsu Chemical Co., Ltd., a hydrolyzable silyl group-containing dimethylpyrazole blocked isocyanate compound (monoisocyanate).

[0135] Hydrolyzable silyl group-containing silicone resin (C-1): "DOWSIL 3074": trade name, manufactured by Toray Dow Coatings Co., Ltd., an alkoxysilyl group-containing silicone resin containing a methyl group and a phenyl group. Hydrolyzable silyl group-containing silicone resin (C-2): "TSR-165": trade name, manufactured by Momentive Corporation, an alkoxysilyl group-containing silicone resin containing a methyl group and a phenyl group. Hydrolyzable silyl group-containing silicone resin (C-3): "KR-500": trade name, manufactured by Toray Dow Coatings Co., Ltd., an alkoxysilyl group-containing silicone resin containing a methyl group.

[0136] Silicone resin (C-4): "KF-96": product name, manufactured by Shin-Etsu Chemical Co., Ltd., dimethyl silicone resin. Contains no alkoxysilyl groups. Used as a comparative example.

[0137] Color pigment (D-1): "Tipake (registered trademark) PFC105", titanium oxide, trade name, manufactured by Ishihara Sangyo Kaisha, Ltd., Al, Si, Zr organically treated titanium oxide, titanium oxide content 87%.

[0138] Color pigment (D-2): "MA-100", carbon black, trade name, manufactured by Mitsubishi Chemical Corporation

[0139] Curing catalyst (E-1): "TOS-TK1": trade name, manufactured by Osaka Shinyaku Co., Ltd., organotin compound Curing catalyst (E-2): "Nacure (registered trademark) 4167": trade name, manufactured by KING INDUSTRIES, alkyl phosphate triethylamine salt compound Curing catalyst (E-3): "Nacure (registered trademark) 5076": trade name, manufactured by KING INDUSTRIES, dodecylbenzenesulfonic acid

[0140] Castor oil (F-1): "URIC H-30": trade name, manufactured by Ito Oil Mills, castor oil, Castor oil (F-2): "URIC H-52": trade name, manufactured by Ito Oil Mills, castor oil, Castor oil (F-3): "URIC H-57": trade name, manufactured by Ito Oil Mills, castor oil, Castor oil (F-4): "URIC H-1824": trade name, manufactured by Ito Oil Mills, castor oil, Castor oil (F-5): "URIC H-62": trade name, manufactured by Ito Oil Mills, castor oil, Castor oil (F-6): "SOVERMOL (registered trademark) 805": trade name, manufactured by BASF, castor oil derivative, Castor oil (F-7): "SOVERMOL (registered trademark) 815": trade name, manufactured by BASF, castor oil derivative, Castor oil (F-8): "SOVERMOL (registered trademark) 819": trade name, manufactured by BASF Corporation, castor oil-containing adhesion-improving component, Castor oil (F-9): "SOVERMOL (registered trademark) 830": trade name, manufactured by BASF Corporation, castor oil-containing adhesion-improving component, Castor oil (F-10): "SOVERMOL (registered trademark) 1005": trade name, manufactured by BASF Corporation, castor oil derivative, Castor oil (F-11): "SOVERMOL (registered trademark) 1092": trade name, manufactured by BASF Corporation, castor oil-containing adhesion-improving component,

[0141] (Note 1) Linseed oil: natural oil, "Linseed oil", trade name, manufactured by Summit Oil Refining Co., Ltd. (Note 2) Ti400: ultraviolet absorber, "TINUVIN400", trade name, manufactured by BASF. (Note 3) Ti123: light stabilizer, "TINUVIN123", trade name, manufactured by BASF. (Note 4) MOA: trimethyl orthoacetate

[0142] The test panels were prepared and the performance was evaluated as follows: the test panels were prepared and subjected to the tests; the results are shown in Table 1.

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149] <Preparation of Test Panels> A chromium phosphate-treated aluminum plate A-1050P (size: 0.8 × 150 × 150 mm, degreased with acetone) was air-spray coated (pressure 0.4 MPa) with Kanpe Baked Plaster Surfacer 500A (product name, manufactured by Kansai Paint Co., Ltd.) to a dry film thickness of 10 μm, and after setting at 20°C for 10 minutes, heated at 130°C for 10 minutes using an electric drying oven. Thereafter, each of Coating Compositions No. 1 to 59 was air-spray coated (pressure 0.4 MPa) to a dry film thickness of 40 μm, and after setting at 20°C for 10 minutes, heated and dried at 160°C for 20 minutes using an electric hot air dryer, and further aged at 20°C for 72 hours to obtain test panels bearing coatings of each of Coating Compositions No. 1 to 59.

[0150] <<Performance Evaluation>> Each of Coating Compositions No. 1 to 59 and each of the test panels on which a coating film was formed using these compositions was subjected to performance tests for the following test items, and performance evaluations were carried out according to the following evaluation criteria. The performance evaluation results are also shown in Tables 1 to 6. Of the test items listed below, it is sufficient for the weather resistance, impact resistance, and boiling water resistance to all pass, and it is preferable for one or more of storage stability, pencil hardness, finished appearance, acid resistance, alkali resistance, and recoat adhesion to pass, more preferably two or more. The more items that pass, the better, and it is most preferable for all to pass.

[0151] <Storage stability> After storing each coating composition for 30 days in a thermostatic chamber at 40°C, the liquid state was evaluated according to the following criteria. ◎ or ○ is acceptable, while △ or × is unacceptable. ◎: No increase in liquid viscosity. ○: A slight increase in liquid viscosity is observed. △: A slight increase in liquid viscosity is observed. ×: The liquid gels.

[0152] <Weather resistance> The accelerated weather resistance of each test panel was evaluated using a xenon weather meter tester. The gloss of the test panel coating film after 5000 hours was compared with the gloss of the initial test panel coating film that had not been subjected to the accelerated weather resistance test, according to the following criteria: ◎ or ○ indicates passing, while △ or × indicates failing. ◎: Gloss was hardly reduced. ○: Gloss was slightly reduced, but this is not a problem in practical use. △: Gloss was reduced so much that it was not at a practical level. ×: Gloss was significantly reduced.

[0153] <Pencil hardness> According to JIS K 5600-5-4 (1999), a pencil lead was placed at an angle of approximately 45° against the surface of each test panel on which a coating film made from each coating composition had been formed (test panel surface), and the lead was pressed firmly against the test panel surface without breaking, while being moved forward at a uniform speed of approximately 10 mm. The hardness symbol of the hardest pencil that did not break the coating film was taken as the pencil hardness. ◎ or ○ indicates a pass, while △ or × indicates a fail. ◎: 2H or higher. ○: H or F. △: HB. ×: B or lower.

[0154] <Finished Appearance> According to JIS K 5600-4-7:1999, the surface of each test panel on which a coating film of each coating composition was formed (test panel surface) was evaluated by visual inspection and gloss value. The gloss value refers to the specular gloss value, and is a value obtained by measuring the specular gloss value at a measurement angle of 60 degrees using a specular gloss meter. A rating of ◎ or ◯ indicates passing, and × indicates failing. ◎: Good smoothness, and a 60-degree gloss value of 70 or more. ○: Good smoothness, and a 60-degree gloss value of 60 to less than 70. ×: Significant deterioration in at least one type of finished appearance selected from sidewalls, wavy, matte finish, and chipped surface, or a 60-degree gloss value of less than 60.

[0155] <Impact Resistance> According to JIS K-56005-3:1999, "Part 5: Mechanical Properties of Coating Films, Section 3: Resistance to Falling Weights," a DuPont impact test was performed on the front coating surface of each test panel at a room temperature of 20°C using a DuPont impact tester with a falling weight of 500 g, a falling weight height of 50 cm, and a tip diameter of 1 / 2 inch. Cellophane adhesive tape was then adhered to the coating surface and rapidly peeled off, after which the degree of cracking and peeling of the coating was evaluated. ◎ or ○ was considered a pass, while △ or × was considered a fail. ◎: No cracking or peeling of the coating was observed. ○: Cracking was observed in the coating, but no peeling was observed. △: Cracking was observed in the coating, and peeling occurred. ×: Significant cracking and significant peeling were observed in the coating.

[0156] <Acid resistance> After each test panel was immersed in a 5% aqueous sulfuric acid solution at 23°C for 72 hours, the appearance of the coating film was visually compared with the gloss of the initial panel (the test panel before immersion) and evaluated. ⊚ or ○ indicates passing, while △ or × indicates failing. ⊚: Almost no decrease in gloss. ○: Gloss slightly decreased, but no practical problem. △: Gloss decreased and was not at a practical level. ×: Gloss significantly decreased.

[0157] <Alkali resistance> Each test panel was immersed in a 5% aqueous sodium carbonate solution at 40°C for 144 hours, and the appearance of the coating film after that was visually compared with the gloss of the initial panel and evaluated. ◎ or ○ indicates passing, while △ or × indicates failing. ◎: Almost no decrease in gloss. ○: Gloss slightly decreased, but no practical problem. △: Gloss decreased and was not at a practical level. ×: Gloss significantly decreased.

[0158] <Boiling water resistance> Each test panel was immersed in deionized water at 99°C for 7 hours, and the appearance of the coating film after that was visually compared with the gloss of the initial panel and evaluated. ◎ or ○ indicates passing, while △ or × indicates failing. ◎: Almost no decrease in gloss. ○: Gloss slightly decreased, but no practical problem. △: Gloss decreased and was not at a practical level. ×: Gloss decreased significantly.

[0159] <Recoat Adhesion> The same coating composition was applied to the surface of each test panel on the side where the coating film had been formed, and the coating was set at 20°C for 10 minutes. After setting, the coating was dried by heating at 160°C for 20 minutes using an electric hot air dryer, and then aged at 20°C for 72 hours to prepare each recoat test coated panel. A cross-hatched adhesive tape peel test (100 cross-hatched squares, 1 mm x 1 mm) according to JIS K5600-5-6 (1999) was conducted and evaluated according to the following criteria: ◎ or ○ indicates pass, and △ or × indicates fail. ◎: 100 cross-hatched coating film remains. ◯: 99 to 90 cross-hatched coating film remains. △: 89 to 11 cross-hatched coating film remains. ×: 10 or fewer cross-hatched coating film remains.

[0160] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2023-190491) filed on November 8, 2023, the contents of which are incorporated herein by reference.

[0161] According to the present invention, it is possible to provide a one-component curing coating composition that has excellent coating film properties such as weather resistance, impact resistance, and boiling water resistance and is compliant with fluororesin regulations such as PFAS regulations.

Claims

1. A one-component curing coating composition comprising (A) a hydroxyl-containing acrylic resin having a hydroxyl value of 40 to 300 mgKOH / g, (B) at least one crosslinking agent selected from a blocked isocyanate compound and a melamine resin, (C) a hydrolyzable silyl-group-containing silicone resin, (D) a coloring pigment, and (E) a curing catalyst.

2. A one-component curing coating composition according to claim 1, comprising, as the hydroxyl-containing acrylic resin (A), a hydroxyl-containing acrylic resin (AX) having both a hydroxyl group and a hydrolyzable silyl group.

3. The one-component curing coating composition according to claim 1 or 2, wherein the solubility parameter of the hydroxyl-containing acrylic resin (A) is within the range of 7.0 to 12.

0.

4. A one-component curing coating composition according to claim 1 or 2, which contains a hydrolyzable silyl group-containing blocked isocyanate compound (BX) as the blocked isocyanate compound.

5. A one-component curing coating composition according to claim 1 or 2, further comprising castor oil (F).

6. A coating method comprising coating a substrate with the one-component curing coating composition according to claim 1 or 2.