Coating composition and coated article

Abstract

To provide a coating composition which is excellent in hydrophilic property, and drainability (dryness).SOLUTION: A coating composition is provided, containing a hydroxyl group-containing acrylic resin (A), a polyisocyanate compound (B) and a hydrophilizing agent (C), wherein a water receding contact angle of a coated film of the composition is 35° or less. The hydrophilizing agent (C) is a copolymer of a constituent monomer containing at least one compound having any one of a morpholine group, an amide group, an oxyalkylene group and a quarternary ammonium salt group constituent monomer as a hydrophilicity-imparting group, and at least one compound having any one of an organosiloxane and a perfluoroalkyl group as a low polar functional group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coating composition capable of forming a coating film that has excellent hydrophilicity and water-wet drying properties, and to a coated article using the same. [Background technology]

[0002] Known methods for imparting wet-drying properties to materials include making the surface of the material hydrophilic, increasing the surface area for water, and shortening the time it takes for water to evaporate. In addition, material surfaces coated with paints using ordinary resin compositions generally have a relatively large water contact angle and are water-repellent, so they do not become material surfaces that allow water to dry easily.

[0003] Various methods for hydrophilizing surfaces have been studied. For example, it is known to hydrophilize surfaces by applying sulfonic acid compounds. Patent Document 1 discloses a coating composition containing an organic resin (A) and a compound (B) having at least one of a sulfonic acid group and a sulfonate salt group.

[0004] However, although coating films obtained from coating compositions containing sulfonic acid compounds such as those described in Patent Document 1 have a low water contact angle, the sulfonic acid compounds, which act as hydrophilizing agents, are eluted in running water, and the desired water-wet-dry properties cannot be obtained. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2015-189889 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a coating composition and a coated article that can form a coating film that is excellent in hydrophilicity and water-wet-drying properties. [Means for solving the problem]

[0007] According to one aspect of the present invention, Item 1. A composition containing a hydroxyl group-containing acrylic resin (A), a polyisocyanate compound (B), and a hydrophilizing agent (C), a coating composition characterized in that a coating film of the composition has a receding contact angle with water of 35° or less; Item 2. A coating composition according to Item 1, wherein the hydrophilizing agent (C) is a copolymer of constituent monomers containing at least one compound having, as a hydrophilicity-imparting group, any one of a morpholine group, an amide group, an oxyalkylene group, and a quaternary ammonium salt group, and at least one compound having, as a low-polarity functional group, any one of an organosiloxane group and a perfluoroalkyl group; Item 3. A coated article having a coating film formed thereon of the coating composition according to either item 1 or 2 above is provided. [Effects of the Invention]

[0008] The coating composition of the present invention provides a coating film that is excellent in hydrophilicity and wet-drying properties. DETAILED DESCRIPTION OF THE INVENTION

[0009] The coating composition of the present invention is a composition containing a hydroxyl group-containing acrylic resin (A), a polyisocyanate compound (B), and a hydrophilizing agent (C), and is characterized in that the coating film of the composition has a receding contact angle with water of 35° or less.

[0010] <Hydroxyl group-containing acrylic resin (A)> The hydroxyl group-containing acrylic resin (A) can be produced, for example, by copolymerizing a hydroxyl group-containing polymerizable unsaturated monomer with another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer by a method known per se, such as a solution polymerization method in an organic solvent or an emulsion polymerization method in water.

[0011] The hydroxyl group-containing polymerizable unsaturated monomer is a compound having one or more hydroxyl groups and one or more polymerizable unsaturated bonds per molecule. Examples of the hydroxyl group-containing polymerizable unsaturated monomer 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, and 4-hydroxybutyl (meth)acrylate; ε-caprolactone-modified monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms; N-hydroxymethyl (meth)acrylamide; allyl alcohol; and (meth)acrylates having a polyoxyethylene chain with a hydroxyl group at the molecular terminal. These may be used alone or in combination of two or more.

[0012] The blending ratio of the hydroxyl group-containing polymerizable unsaturated monomer is preferably within the range of 10 to 60 mass %, particularly 20 to 50 mass %, and further particularly 30 to 45 mass %, based on the total amount of the monomer components.

[0013] The other polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer is a compound having one unsaturated bond per molecule other than the above hydroxyl group-containing polymerizable unsaturated monomer, and specific examples thereof are listed below in (1) to (8). (1) Acid group-containing polymerizable unsaturated monomer: a compound having one or more acid groups and one unsaturated bond in one molecule, such as carboxyl group-containing polymerizable unsaturated monomers such as (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, and maleic anhydride; sulfonic acid group-containing polymerizable unsaturated monomers such as vinyl sulfonic acid and sulfoethyl (meth)acrylate; acidic phosphate ester-based polymerizable unsaturated monomers such as 2-(meth)acryloyloxyethyl acid phosphate, 2-(meth)acryloyloxypropyl acid phosphate, 2-(meth)acryloyloxy-3-chloropropyl acid phosphate, and 2-methacryloyloxyethylphenyl phosphoric acid. These can be used alone or in combination of two or more.

[0014] (2) Monoesters of acrylic acid or methacrylic acid with monohydric alcohols having 1 to 20 carbon atoms: for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isomyristyl (meth)acrylate, isostearyl acrylate (trade name, manufactured by Osaka Organic Chemical Industry Ltd.), lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, etc.

[0015] (3) Aromatic polymerizable unsaturated monomers: for example, styrene, α-methylstyrene, vinyltoluene, etc.

[0016] When an aromatic polymerizable unsaturated monomer is used as a constituent component, the blending ratio thereof is preferably within the range of 3 to 50 mass %, particularly 5 to 40 mass %, based on the total amount of the monomer components.

[0017] (4) Glycidyl group-containing polymerizable unsaturated monomer: a compound having one glycidyl group and one unsaturated bond in one molecule, specifically, glycidyl acrylate, glycidyl methacrylate, etc.

[0018] (5) Nitrogen-containing polymerizable unsaturated monomers: for example, acrylamide, methacrylamide, dimethylacrylamide, N,N-dimethylpropylacrylamide, N-butoxymethylacrylamide, N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide, N,N-dimethylaminoethyl (meth)acrylate, vinylpyridine, vinylimidazole, etc.

[0019] (6) Alicyclic hydrocarbon group-containing polymerizable unsaturated monomers: for example, cyclohexyl (meth)acrylate, methylcyclohexylmethyl (meth)acrylate (for example, 4-methylcyclohexylmethyl (meth)acrylate), ethylcyclohexylmethyl (meth)acrylate (for example, 4-ethylcyclohexylmethyl (meth)acrylate), methoxycyclohexylmethyl (meth)acrylate (for example, 4-methoxycyclohexylmethyl (meth)acrylate), tert-butylcyclohexyl Examples of the cycloalkyl (meth)acrylate include cycloalkyl (meth)acrylates such as cyclooctyl (meth)acrylate, cyclododecyl (meth)acrylate, and the like; isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, adamantyl (meth)acrylate, 3,5-dimethyladamantyl (meth)acrylate, and 3-tetracyclododecyl (meth)acrylate, and preferred examples include cyclohexyl (meth)acrylate and isobornyl (meth)acrylate.

[0020] (7) Other vinyl compounds: for example, vinyl acetate, vinyl propionate, vinyl chloride, Versatic acid vinyl esters such as Veova 9 and Veova 10 (Japan Epoxy Resin).

[0021] (8) Unsaturated bond-containing nitrile compounds: for example, acrylonitrile, methacrylonitrile, etc.

[0022] These other polymerizable unsaturated monomers can be used alone or in combination of two or more. In this specification, "(meth)acrylate" means acrylate or methacrylate, "(meth)acrylic acid" means acrylic acid or methacrylic acid, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylamide" means acrylamide or methacrylamide.

[0023] The hydroxyl group-containing acrylic resin (A) preferably has a glass transition temperature in the range of 0°C to 100°C, particularly 5°C to 50°C, and more particularly 10°C to 40°C, from the viewpoint of the water wetting and drying properties of the resulting coating film.

[0024] In this specification, the glass transition temperature Tg of the hydroxyl group-containing acrylic resin is a value calculated by the following formula. 1 / Tg(K)=W1 / T1+W2 / T2+...Wn / Tn Tg(℃)=Tg(K)-273 In the formula, W1, W2, ···Wn are the mass fractions of each monomer, and T1, T2 ···Tn are the glass transition temperatures Tg (K) of the homopolymers of each monomer. The glass transition temperatures of the homopolymers of each monomer are values ​​taken from POLYMER HANDBOOK Fourth Edition, edited by J. Brandrup, Eh Immergut, and E.A. Grulke (1999). For the glass transition temperatures of monomers not described in the literature, the values ​​used are those obtained 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 by differential scanning calorimetry.

[0025] The weight average molecular weight of the hydroxyl group-containing acrylic resin (A) is preferably within the range of 3,000 to 100,000, particularly 4,000 to 20,000, and even more particularly 5,000 to 10,000, from the viewpoint of the wettability and drying properties of the coating film.

[0026] In this specification, the weight-average molecular weight and number-average molecular weight are values ​​obtained by converting the retention time (retention volume) measured using a gel permeation chromatograph (GPC) into the molecular weight of polystyrene using the retention time (retention volume) of standard polystyrene of known molecular weight measured under the same conditions. Four columns, "TSKgel G-4000HxL," "TSKgel G-3000HxL," "TSKgel G-2500HxL," and "TSKgel G-2000HxL" (all trade names, manufactured by Tosoh Corporation), were used, and the conditions for the mobile phase were tetrahydrofuran, the measurement temperature was 40°C, the flow rate was 1 ml / min, and the detector was RI.

[0027] The hydroxyl value of the hydroxyl-containing acrylic resin (A) is preferably within the range of 10 to 200 mgKOH / g, particularly 70 to 190 mgKOH / g, and further particularly 100 to 180 mgKOH / g, from the viewpoint of water wetting and drying properties.

[0028] <Polyisocyanate compound (B)> The coating composition of the present invention contains a polyisocyanate compound (B) as a crosslinking agent.

[0029] The polyisocyanate compound (B) is a compound having at least two isocyanate groups in one molecule, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of the polyisocyanates.

[0030] Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate (trivial name: lysine diisocyanate), aliphatic diisocyanates such as 2-isocyanatoethyl 2,6-diisocyanatohexanoate, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, and 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane.

[0031] Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: isophorone diisocyanate), 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, Alicyclic diisocyanates such as 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or a mixture thereof, methylenebis(4,1-cyclohexanediyl)diisocyanate (common name: hydrogenated MDI), and norbornane diisocyanate; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2-(3-isocyanatopropyl)- 2,5-di(isocyanatomethyl)-bicyclo(2,2,1)heptane, 2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo(2,2,1)heptane, 3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2,2,1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2,2,1)heptane, 6-(2-isocyanatoethyl)-bicyclo(2,2,1)heptane alicyclic triisocyanates such as (2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2,2,1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2,2,1)heptane, and 6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2,2,1)heptane.

[0032] Examples of the aromatic aliphatic polyisocyanate include aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene)diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or a mixture thereof; and aromatic aliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene.

[0033] Examples of the aromatic polyisocyanate include aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (common name: 2,4-TDI) or 2,6-tolylene diisocyanate (common name: 2,6-TDI) or a mixture thereof, 4,4'-toluidine diisocyanate, and 4,4'-diphenyl ether diisocyanate; aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene; and aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate.

[0034] Furthermore, examples of the derivatives of the polyisocyanates include dimers, trimers, biurets, allophanates, uretdione, uretoimine, isocyanurates, oxadiazinetrione, polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI), crude TDI, and the like of the above polyisocyanates.

[0035] As the polyisocyanate compound (B), from the viewpoint of curability, the above-mentioned aliphatic diisocyanates, alicyclic diisocyanates and derivatives thereof can be suitably used.

[0036] The polyisocyanate compound may be a prepolymer obtained by reacting the polyisocyanate or a derivative thereof with a compound reactive with the polyisocyanate under conditions of excess isocyanate groups. Examples of the compound reactive with the polyisocyanate include compounds having an active hydrogen group such as a hydroxyl group or an amino group, and specific examples of the compound that can be used include polyhydric alcohols, low-molecular-weight polyester resins, amines, and water.

[0037] Furthermore, as the polyisocyanate compound, a polymer of an isocyanate group-containing polymerizable unsaturated monomer, or a copolymer of the isocyanate group-containing polymerizable unsaturated monomer and a polymerizable unsaturated monomer other than the isocyanate group-containing polymerizable unsaturated monomer, can also be used.

[0038] The polyisocyanate compound may be a polyisocyanate compound in which the isocyanate group is blocked with a blocking agent, that is, a so-called blocked polyisocyanate compound.

[0039] The polyisocyanate compounds (B) can be used either alone or in combination of two or more.

[0040] From the viewpoints of curability and performance sustainability, the proportion of the polyisocyanate compound (B) in the coating composition of the present invention is preferably such that the equivalent ratio (NCO / OH) of the isocyanate groups (including blocked isocyanate groups) of the polyisocyanate compound to the hydroxyl groups of the hydroxyl group-containing acrylic resin (A) is within the range of 0.5 to 2.0, preferably 0.8 to 1.8, and particularly preferably 1.0 to 1.6.

[0041] <Hydrophilic Agent (C)> The hydrophilizing agent may be any agent as long as it has hydrophilicity, and is usually a compound that imparts hydrophilicity to the coating film by floating and localizing on the surface layer of the coating film formed from the coating composition.

[0042] Examples of the hydrophilicity-imparting group include anionic groups, cationic groups, and nonionic groups.

[0043] Examples of the anionic group include a carboxyl group, a carbonyl group, a sulfonic acid group, and a phosphate group.

[0044] Examples of the cationic group include an amino group and an ammonium salt group.

[0045] Examples of the nonionic group include a morpholine group, an amide group, a hydroxyl group, and an oxyalkylene group.

[0046] Furthermore, examples of the hydrophilicity-imparting group include betaine, which is an amphoteric compound. As the hydrophilicity-imparting group, a nonionic group is preferred from the viewpoint of surface orientation, and among nonionic groups, a morpholine group is particularly preferred from the viewpoint of water-repellency.

[0047] Furthermore, the hydrophilizing agent (C) preferably contains a low polarity functional group in order to impart surface orientation.

[0048] Examples of the low polarity functional group include an organosiloxane group and a perfluoroalkyl group.

[0049] Of the above, perfluoroalkyl groups are particularly suitable from the viewpoint of surface orientation.

[0050] As the hydrophilizing agent (C), a copolymer of constituent monomers containing at least one compound having, as a hydrophilicity-imparting group, any one of a morpholine group, an amide group, an oxyalkylene group, and a quaternary ammonium base, and at least one compound having, as a low-polarity functional group, any one of an organosiloxane group and a perfluoroalkyl group, can be particularly preferably used.

[0051] Specifically, for example, copolymers of constituent monomers containing at least a (meth)acrylate compound having an organosiloxane group and a (meth)acrylate compound having an acryloylmorpholine group, copolymers of constituent monomers containing at least a (meth)acrylate compound having a perfluoroalkyl group and a (meth)acrylate compound having an acryloylmorpholine group, copolymers of constituent monomers containing at least a (meth)acrylate compound having an organosiloxane group and a (meth)acrylamide compound, copolymers of constituent monomers containing at least a (meth)acrylate compound having a perfluoroalkyl group and a (meth)acrylamide compound, copolymers of constituent monomers containing at least an organosiloxane group and a (meth)acrylate compound having an oxyalkylene group; a copolymer of constituent monomers containing at least a (meth)acrylate compound having a perfluoroalkyl group and a (meth)acrylate compound having an oxyalkylene group; a copolymer of constituent monomers containing at least a (meth)acrylate compound having an organosiloxane group and a (meth)acrylate compound having a quaternary ammonium salt group; and a copolymer of constituent monomers containing at least a (meth)acrylate compound having a perfluoroalkyl group and a (meth)acrylate compound having a quaternary ammonium salt group.

[0052] Among the above, from the viewpoint of water-wet drying properties, copolymers of constituent monomers containing at least a (meth)acrylate compound having an acryloylmorpholine group as a hydrophilicity-imparting group, particularly copolymers of constituent monomers containing at least a (meth)acrylate compound having an acryloylmorpholine group and a (meth)acrylate compound having a perfluoroalkyl group, and copolymers of constituent monomers containing at least a (meth)acrylate compound having an acryloylmorpholine group and a (meth)acrylate compound having an organosiloxane group can be preferably used.

[0053] From the viewpoint of water wetting and drying properties, the solid content of the hydrophilizing agent (C) is preferably within a range of 0.1 to 20 mass%, particularly 0.1 to 15 mass%, and even more particularly 1 to 10 mass%, relative to the total solid content of the hydroxyl group-containing acrylic resin (A) and the polyisocyanate compound (B).

[0054] The coating composition of the present invention may also contain a urethanization reaction catalyst.

[0055] Specific examples of the urethanization reaction catalyst include organometallic compounds such as tin octoate, dibutyltin diacetate, dibutyltin di(2-ethylhexanoate), dibutyltin dilaurate, dioctyltin diacetate, dioctyltin di(2-ethylhexanoate), dibutyltin oxide, dibutyltin sulfite, dioctyltin oxide, dibutyltin fatty acid salts, lead 2-ethylhexanoate, zinc octoate, zinc naphthenate, zinc fatty acids, bismuth octanoate, bismuth 2-ethylhexanoate, bismuth oleate, bismuth neodecanoate, bismuth versatate, bismuth naphthenate, cobalt naphthenate, calcium octoate, copper naphthenate, and tetra(2-ethylhexyl)titanate; and tertiary amines. These can be used alone or in combination of two or more.

[0056] When the urethane reaction catalyst is used, the amount of the catalyst is preferably within a range of 0.0001 to 2.0 mass %, particularly 0.0005 to 1.5 mass %, in terms of solid content, relative to the total amount of solid content of the hydroxyl group-containing acrylic resin (A) and the polyisocyanate compound (B).

[0057] When the coating composition of the present invention contains the above-mentioned urethane reaction catalyst, from the viewpoint of storage stability and curing properties, it may contain organic acids such as acetic acid, propionic acid, butyric acid, isopentanoic acid, hexanoic acid, 2-ethylbutyric acid, naphthenic acid, octylic acid, nonanoic acid, decanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, neodecanoic acid, versatic acid, isobutyric anhydride, itaconic anhydride, acetic anhydride, citraconic anhydride, propionic anhydride, maleic anhydride, butyric anhydride, citric anhydride, trimellitic anhydride, pyromellitic anhydride, and phthalic anhydride; inorganic acids such as hydrochloric acid and phosphoric acid; and metal coordination compounds such as acetylacetone and imidazole compounds.

[0058] The coating composition of the present invention may contain other additives that are commonly used in the field of coatings, such as resin particles (excluding the hydroxyl group-containing acrylic resin (A)), solvents, pigments, ultraviolet absorbers, light stabilizers, antioxidants, surface conditioners, antifoaming agents, emulsifiers, surfactants, antifouling agents, wetting agents, thickeners, dyes, gloss adjusters, etc., as long as the hydrophilicity is not impaired.

[0059] The coating composition of the present invention may be in the form of a melt, solution, suspension, or emulsion, but is preferably in the form of a solution in which the hydroxyl group-containing acrylic resin is dissolved in a solvent from the viewpoint of productivity and workability. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether, esters such as ethyl acetate and butyl acetate, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, ethanol, propanol, and butanol, tetrahydrofuran, dimethylformamide, and petroleum hydrocarbons.

[0060] Examples of the pigment include luster pigments, color pigments, extender pigments, etc. The pigments can be used alone or in combination of two or more.

[0061] Examples of the luster pigment include aluminum, copper, zinc, brass, nickel, glass flakes, aluminum oxide, mica, aluminum oxide coated with titanium oxide and / or iron oxide, and mica coated with titanium oxide and / or iron oxide.

[0062] Examples of the color pigment include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, threne pigments, perylene pigments, dioxazine pigments, and diketopyrrolopyrrole pigments.

[0063] Examples of the extender pigment include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white.

[0064] When the coating composition of the present invention contains the above-mentioned pigment, the content of the pigment is preferably within the range of 1 to 70 mass %, preferably 5 to 60 mass %, and more preferably 15 to 50 mass %, based on the total solid content of the hydroxyl group-containing acrylic resin (A) and the polyisocyanate compound (B).

[0065] The coating composition of the present invention may be a one-component coating material, or a multi-component coating material in which a base component containing a hydroxyl group-containing acrylic resin (A) and a hydrophilizing agent (C) is mixed with a curing agent containing a polyisocyanate compound (B) and the like before application.

[0066] <Water receding contact angle> The coating film of the coating composition of the present invention has a receding water contact angle of 35° or less, preferably 0 to 30°, and more preferably 0 to 25°.

[0067] More specifically, the coating composition of the present invention is applied to a substrate surface so that the cured film thickness is 40 μm, and the coating film formed has a receding water contact angle of 35° or less, preferably 0 to 30°, and more preferably 0 to 25°.

[0068] In the present invention, the water receding contact angle is very important for the water wetting and drying properties, and there is a very high correlation between the water wetting and drying properties and the water receding contact angle.

[0069] By making the receding contact angle of water of the coating film formed from the coating composition of the present invention 35° or less, the water used does not remain on the surface even after washing, and the coating film has extremely high water-wetting and drying properties on the surface.

[0070] In the present invention, the receding water contact angle was measured using the expansion / contraction method. Specifically, 2 μL of distilled water was deposited on a test specimen using an automatic contact angle measurement device to form a water droplet. Next, a stainless steel needle (SNS021 / 011, manufactured by Eiko Seiki Co., Ltd.) with an outer diameter of 0.21 mm and an inner bore diameter of 0.11 mm attached to a 500 μL glass syringe (DS500 / GT, manufactured by Eiko Seiki Co., Ltd.) was inserted into the center of the water droplet so that the tip of the needle was 0.2 mm above the test specimen surface. The contact angle immediately after 40 μL of distilled water was injected through the needle at a rate of 20 μL / s was taken as the advancing contact angle. After allowing the water to stand for 1 second, the contact angle immediately after aspirating 40 μL at a rate of 20 μL / s was taken as the receding contact angle.

[0071] The contact angle meter used in the present specification for measuring the contact angle is "DMo-502" (manufactured by Kyowa Interface Science Co., Ltd.).

[0072] In the present invention, the water receding contact angle was measured using a coating film prepared after 24 hours had elapsed.

[0073] <Object to be coated> The material of the substrate to which the coating composition of the present invention can be applied is not particularly limited, and may be any of inorganic materials, organic materials, and organic-inorganic hybrid materials.

[0074] Examples of the inorganic materials include metal materials such as iron, aluminum, brass, copper, tin, stainless steel, zinc-plated steel, and zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.)-plated steel; glass; cement; concrete; polysiloxane; and the like.

[0075] The organic material is a material containing an organic resin, and examples of the organic resin include acrylic resins such as polymethyl methacrylate, polyester resins such as polyethylene terephthalate, polyethylene naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, polyethylene-1,2-diphenoxyethane-4,4'-dicarboxylate, and polybutylene terephthalate, epoxy resins represented by commercially available products such as Epicoat (trade name: manufactured by Yuka Shell Epoxy Co., Ltd.), polycarbonate resins, polyimide resins, novolac resins, phenolic resins, and acrylic resins. Examples of such resins include acrylonitrile-butadiene-styrene (ABS) resin, vinylidene chloride resin, polyurethane resin, cellulose ester (e.g., triacetyl cellulose, diacetyl cellulose, propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose, nitrocellulose), polyamide, polystyrene (e.g., syndiotactic polystyrene), polyolefin (e.g., polypropylene, polyethylene, polymethylpentene), polysulfone, polyethersulfone, polyarylate, polyetherimide, and polyether ketone.

[0076] The organic material may contain pigments, fibers, shrinkage reducing agents, fillers, additives, etc. as part of its components.

[0077] Examples of the pigment include calcium carbonate, silica, barium sulfate, barium carbonate, talc, clay, kaolin, aluminum hydroxide, magnesium oxide, and aluminum oxide.

[0078] Examples of the fibers include glass fibers, aramid fibers, carbon fibers, and cellulose fibers.

[0079] Therefore, various fiber reinforced plastic materials (hereinafter referred to as FRP materials or simply FRP), SMC (Sheet Molding Compound), etc. are included in the above organic materials.

[0080] As the material of the above-mentioned substrate, from the viewpoint of adhesion etc., organic materials are preferred, and among them, organic materials with a relatively low melting point, such as acrylic resin, ABS resin, FRP, SMC, etc. are preferred.

[0081] The shape of the object to be coated may be flat or three-dimensional, for example, a film and a substrate, or a three-dimensionally processed molded object.

[0082] The above-mentioned substrate may be one that has been degreased, surface-treated and coated with a primer composition.

[0083] <Painting> The coating method of the coating composition of the present invention is not particularly limited, and can be carried out by coating methods such as air spray, airless spray, rotary atomization coating, curtain coating, and the like. These coating methods may be carried out with electrostatic application, if necessary. The coating amount of the coating composition of the present invention is usually preferably an amount that results in a cured film thickness of about 20 to 100 μm.

[0084] In addition, when applying the coating composition of the present invention, it is preferable to adjust the viscosity of the coating composition using a solvent such as an organic solvent so that it falls within a viscosity range suitable for the coating method; for example, in the case of rotary atomization coating, the viscosity falls within a range of about 15 to 40 seconds when measured at 20°C using a Ford Cup No. 4 viscometer.

[0085] The coating film formed from the coating composition of the present invention can be heated by known means, for example, a drying oven such as a hot air oven, an electric oven, or an infrared induction heating oven. The heating temperature is suitably in the range of 60 to 180°C, preferably 80 to 160°C. The heating time is not particularly limited, but is preferably in the range of 5 to 120 minutes, more preferably 10 to 60 minutes.

[0086] In particular, when the substrate is an organic material and its melting point is 100°C or higher, it is appropriate to set the heating temperature within the range of 60 to 180°C, preferably 80 to 160°C, and when the substrate has a melting point of less than 140°C, it is appropriate to set the heating temperature within the range of 60 to 90°C, preferably 65 to 85°C.

[0087] The heating time is not particularly limited, but is preferably within the range of 10 to 130 minutes, more preferably 10 to 120 minutes. [Example]

[0088] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples. Note that "parts" and "%" are all based on mass.

[0089] Hydroxyl-containing acrylic resin (A) Details of the hydroxyl group-containing acrylic resins (A-1) to (A-3) used in the examples of the present invention are as follows.

[0090] (A-1): An acrylic resin having a weight average molecular weight of 5,500, a glass transition temperature of 17°C, and a hydroxyl value of 141 (A-2): An acrylic resin having a weight average molecular weight of 7500, a glass transition temperature of 79°C, and a hydroxyl value of 121 (A-3): An acrylic resin having a weight average molecular weight of 35,000, a glass transition temperature of 80°C, and a hydroxyl value of 140. Polyisocyanate compound (B) Details of the polyisocyanate compounds (B-1) and (B-2) used in the examples of the present invention are as follows.

[0091] (B-1): "Duranate TPA-100" product name, manufactured by Asahi Kasei Corporation, hexamethylene diisocyanate nurate, NCO content = 23%, solid content = 100% (B-2): "Duranate 24A-100" product name, manufactured by Asahi Kasei Corporation, biuret form of hexanemethylene diisocyanate, NCO content = 23%, solid content = 100% Hydrophilizing agent (C) Synthesis of hydrophilizing agent (C-1) 100 parts of cyclohexanone was added to a four-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, and the temperature was raised to 100° C. with stirring.

[0092] To this was mixed 5 parts of (c1) one-end methacrylate-modified dimethyl silicone (manufactured by Shin-Etsu Chemical Co., Ltd., product name "X-22-2475"), 91.9 parts of (c3) acryloylmorpholine (manufactured by KJ Chemical Co., Ltd., product name "ACMO"), 3.1 parts of (c7) 2-hydroxyethyl acrylate (manufactured by Nippon Shokubai, product abbreviation name "BHEA"), 1.0 part of 2,2'-azobis(2-methylbutyronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "V-59"), and 100 parts of cyclohexanone (manufactured by Sumitomo Chemical), and the mixture was added dropwise over 3 hours to a flask heated to 100°C.

[0093] After the dropwise addition was completed, the mixture was stirred for 30 minutes at 100°C, and then a solution of 0.3 parts of 2,2'-azobis(2-methylbutyronitrile) and 10 parts of cyclohexanone was added dropwise over 30 minutes, and the mixture was allowed to react for 1 hour at 100°C while continuing to stir. 26.4 parts of cyclohexanone was further added to obtain a hydrophilizing agent (C-1) with a solids mass concentration of 55%.

[0094] Synthesis of hydrophilizing agents (C-2) to (C-8) Hydrophilizing agents (C-2) to (C-8) each having a solid mass concentration of 55% were obtained by synthesizing in the same manner as hydrophilizing agent (C-1) except for using the compositions shown in Table 1.

[0095] The raw materials used other than the hydrophilizing agent (C-1) in Table 1 are as follows:

[0096] (c2): 2-(perfluorohexyl)ethyl acrylate (manufactured by Unimatec Co., Ltd., product name "CHEMINOX FAAC-6") (c4): Dimethylacrylamide (c5): Methoxypolyethylene glycol acrylate (product name "AM-90G" manufactured by Shin-Nakamura Chemical Co., Ltd.) (c6): Dimethylaminopropylacrylamide methyl chloride quaternary salt DMAPAA-Q manufactured by KJ Chemicals The hydrophilizing agents (C-9) and (C-10) are as follows:

[0097] (C-9): "Newcol 293" product name, manufactured by Nippon Nyukazai Co., Ltd., monoalkyl succinate sulfonate (C-10): "Newcol 290" product name, manufactured by Nippon Nyukazai Co., Ltd., sodium alkyl succinate sulfonate

[0098] [Table 1]

[0099] Manufacture of coating compositions No. 1 to No. 20 Example 1 100 parts (solids) of a hydroxyl-containing acrylic resin (A-1) solution with a mass solids concentration of 55%, 68 parts (solids) of a polyisocyanate compound (B-1), 15 parts (solids) of a hydrophilizing agent (C-1), and 0.1 parts of dibutyltin dilaurate were uniformly mixed, and the solids content was further adjusted with butyl acetate to a viscosity of 15±1 seconds / Iwata cup (20°C), thereby obtaining coating composition No. 1.

[0100] In Coating Composition No. 1, the equivalent ratio of the total amount of hydroxyl groups (OH) of the hydroxyl-containing acrylic resin to the isocyanate groups (NCO) of the polyisocyanate compound is NCO / OH=1.5.

[0101] Examples 2 to 14 and Comparative Examples 1 to 6 Coating compositions No. 2 to No. 20 were obtained in the same manner as in Example 1, except that the compositional ratios of the components (A) to (C) were as shown in Table 2. The blending amounts in Table 2 indicate the blending amounts of solids. Coating compositions No. 15 to No. 20 are comparative coatings.

[0102] [Table 2]

[0103] [Table 3]

[0104] Creating the object to be painted Object to be coated The substrate used was a pretreated steel plate measuring 100 mm x 200 mm x 0.8 mm.

[0105] Creating test panels Example 1 The coating composition No. 1 obtained in Example 1 was applied to the substrate using an air spray to a film thickness of 40 μm, and after setting at room temperature for 10 minutes, the coating was heated to 90°C for 30 minutes to cure, thereby obtaining corresponding test panels coated with each of the coating compositions Nos. 1 to 20.

[0106] Evaluation Test The obtained test panels were evaluated by the following test methods, and the evaluation results are shown in Table 3.

[0107] Water receding contact angle At least 24 hours after the test plate was prepared, 2 μL of distilled water was deposited on the test specimen using an automatic contact angle measurement device to form a water droplet. Next, a stainless steel needle (SNS021 / 011, manufactured by Eiko Seiki Co., Ltd.) with an outer diameter of 0.21 mm and an inner bore diameter of 0.11 mm attached to a 500 μL glass syringe (DS500 / GT, manufactured by Eiko Seiki Co., Ltd.) was inserted into the center of the water droplet so that the tip of the needle was 0.2 mm above the surface of the test specimen. The contact angle immediately after 40 μL of distilled water was injected from the needle at a rate of 20 μL / s was recorded as the advancing contact angle. After allowing to stand for 1 second, the contact angle immediately after aspirating 40 μL at a rate of 20 μL / s was recorded as the receding contact angle.

[0108] water static contact angle At least 24 hours after the preparation of the test plate, 1.0 μL of distilled water was dropped onto the test plate, and the contact angle (unit: °) was measured 5 seconds later. The contact angle meter used for the contact angle measurement was the "CA-X150 Model" (manufactured by Kyowa Interface Science Co., Ltd.).

[0109] Wet and dry 50cc of water was sprayed onto the test plate using a spray bottle, and the test plate was tilted 5 degrees from the horizontal and left to stand for 30 minutes. After that, the amount of water droplets remaining was calculated from the mass ratio of the amount of water droplets remaining before and after the test using the following formula and evaluated. Water droplet remaining rate (%) = {(Test plate mass (g) after leaving it for 30 minutes - Test plate mass (g) before water spraying)} / {(Weight of test plate after water spraying (g) - Weight of test plate before water spraying (g))} ○: Water droplets remaining rate is 0% or more and less than 30% △: Water droplets remaining rate is 30% or more and less than 60% ×: Water droplets remaining rate is 60% or more

[0110] [Table 4]

[0111] [Table 5] [Brief explanation of the drawings]

[0112] [Figure 1] 1 is a graph showing the relationship between water receding contact angle and water wetting and drying properties in the present invention. [Industrial Applicability]

[0113] It is possible to provide a coated article having a coating film that is excellent in hydrophilicity, water wetting and drying properties, and stain resistance.

Claims

1. A composition containing a hydroxyl group-containing acrylic resin (A), a polyisocyanate compound (B), and a hydrophilizing agent (C), the hydrophilizing agent (C) comprises at least one compound having, as a hydrophilicity-imparting group, any one of a morpholine group, an amide group, an oxyalkylene group, and a quaternary ammonium salt group; a copolymer of constituent monomers containing at least one of a compound having an organosiloxane group or a perfluoroalkyl group as a low-polarity functional group, A coating composition characterized in that the coating film of the composition has a receding contact angle with water of 35° or less.

2. A paint composition as described in claim 1, wherein the hydrophilizing agent (C) is a copolymer of constituent monomers containing at least one compound having either a morpholine group or an oxyalkylene group as a hydrophilicity-imparting group.

3. A paint composition as described in claim 1 or 2, wherein the hydrophilizing agent (C) is a copolymer of constituent monomers containing a compound having a perfluoroalkyl group as a low-polarity functional group.

4. The equivalent ratio (NCO / OH) of the isocyanate group of the polyisocyanate compound to the hydroxyl group of the hydroxyl group-containing acrylic resin (A) is 0.5 to 2.0, and the solid content mass % of the hydrophilizing agent (C) is 0.1 to 20 mass % based on the total solid content of the hydroxyl group-containing acrylic resin (A) and the polyisocyanate compound (B); The coating composition of claim 1.

5. A coated article having a coating film formed from the coating composition according to any one of claims 1 to 4.

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