JP2007070370A - Coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a coating composition that forms a conductive primer coating film having high brightness color, high opacifying properties and sufficient electroconductivity on a plastic molding such as an automobile bumper, etc., only by adding ordinary white pigment even without using expensive white conductive pigment. <P>SOLUTION: The coating composition comprises a polyolefin or a modified polyolefin (A) and an ionic liquid (B). The coating method comprises using the composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coating composition capable of forming a coating film having sufficient conductivity without using a conductive pigment.

Plastic materials used for automobile bumpers and the like usually have a volume resistivity of about 10 ¹⁰ Ω · cm or more, and an electrostatic coating method with excellent coating efficiency can be applied to such plastic molded products. It is difficult to use and paint directly. For this reason, conventionally, such a material surface is first coated with a conductive primer coating, and then a top coating for coloring purposes is electrostatically coated (see, for example, Patent Document 1).

  In addition, plastic materials used for automobile bumpers and the like usually have a dark color such as black, and when applying a light-colored or low concealing top coat, High concealment and high brightness color are required. In order to meet this requirement, various conductive paints using conductive pigments (antimony-doped type or non-antimony type) having relatively high brightness have been proposed (for example, Patent Document 2 and Patent Document 3). The antimony-doped type conductive pigment has a problem of toxicity, and the non-antimony type conductive pigment has a problem that it is very expensive.

Patent Document 4 proposes to use a conductive primer obtained by adding an inexpensive conductive carbon black pigment and a specific aluminum powder as a conductive filler. As a result, a light gray primer coating film can be formed, and electrostatic painting of a light-colored top coat is possible. However, especially when trying to form a high white pearl-tone multilayer coating film having a whiteness L value of 90 or more based on the CIE color matching function, the above conductive primer is still insufficient. For such a high whiteness conductive primer, it is necessary to use an expensive white conductive pigment.
JP-A-6-165966 Japanese Patent Laid-Open No. 9-12314 Japanese Patent Laid-Open No. 10-53417 JP 2003-231767 A

  The main object of the present invention is to provide a conductive primer coating film having high lightness color, high concealment property and sufficient conductivity only by adding an ordinary white pigment without using an expensive white conductive pigment. It is to provide a coating composition that can be formed.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by using polyolefin or modified polyolefin and an ionic liquid as at least a part of a film-forming component of a paint. It came to complete.

  Thus, according to the present invention, there is provided a coating composition characterized by containing polyolefin or modified polyolefin (A) and ionic liquid (B).

  According to the present invention, there is also provided a coating method characterized by coating the coating composition.

The coating composition of the present invention can form a coating film having sufficient conductivity without using a conductive pigment, and can be suitably used particularly for coating plastic molded articles. In addition, when the coating composition of the present invention contains a white pigment, it can be used as a conductive primer to form a primer film with a high brightness color and a high hiding property. Alternatively, it is possible to easily form a multilayer coating film having a high chroma paint color.
Hereinafter, the present invention will be described in more detail.

Polyolefin and modified polyolefin (A) :
Examples of the polyolefin used in the coating composition of the present invention include a polyolefin obtained by (co) polymerizing one or more of olefins having 2 to 10 carbon atoms such as ethylene, propylene, butylene and hexene. In addition, the modified polyolefin includes an unsaturated carboxylic acid or acid anhydride modified product, an acrylic modified product, a chlorinated product, and a modified polyolefin obtained by combining these modified products.

  As the polyolefin used in the coating composition of the present invention, those containing propylene as a polymerization unit are particularly suitable, and the weight fraction of the propylene unit in the polyolefin or the modified polyolefin (A) is different from that of other components. From the viewpoints of compatibility and adhesion of the formed coating film, those generally in the range of 0.5 or more, particularly 0.6 to 1, more particularly 0.7 to 0.95 are suitable.

  As the polyolefin, those known per se can be used without particular limitation, but the single-site catalyst is used as a polymerization catalyst from the viewpoint that the obtained polyolefin has a narrow molecular weight distribution and excellent random copolymerizability. Those produced by (co) polymerizing olefins using are preferred. The single site catalyst is a polymerization catalyst having a uniform active site structure (single site), and a metallocene catalyst is particularly preferable among the single site catalysts. The metallocene-based catalyst is a metallocene (bis (cyclopentadienyl) which is a transition metal compound of Group 4-6 or Group 8 or a rare earth transition metal compound of Group 3 of the periodic table having at least one conjugated five-membered ring ligand. It can be prepared by combining (a) a metal complex and its derivatives) with an aluminoxane or boron-based co-catalyst that activates the metal complex and an organoaluminum compound such as trimethylaluminum. The (co) polymerization of olefin can be carried out according to a method known per se, for example, by continuously adding alkylaluminum and metallocene while supplying olefin such as propylene and ethylene and hydrogen to the reaction vessel.

  Unsaturated carboxylic acid or acid anhydride-modified polyolefin can be produced, for example, by graft polymerization of an unsaturated carboxylic acid or acid anhydride thereof to polyolefin according to a method known per se. Examples of unsaturated carboxylic acids or acid anhydrides that can be used for modification include aliphatic carboxylic acids having 3 to 10 carbon atoms and containing at least one, preferably one polymerizable double bond in one molecule. Specifically, for example, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride and the like can be mentioned, among which maleic acid or its acid anhydride is particularly preferable. The amount of graft polymerization of the unsaturated carboxylic acid or its acid anhydride to the polyolefin can be varied depending on the physical properties desired for the modified polyolefin, but generally 1 to 20 weights based on the solid content weight of the polyolefin. %, Preferably 1.5 to 15% by weight, more preferably 2 to 10% by weight.

The acrylic-modified polyolefin can be produced by graft polymerization of at least one acrylic unsaturated monomer to the polyolefin by an appropriate method known per se. Examples of the acrylic unsaturated monomer that can be used for this acrylic modification include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid. hexyl, (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) _C 1 _{-C 20} alkyl esters of (meth) acrylic acid, such as stearyl acrylate; (meth) 2-hydroxyethyl acrylate, (meth) _C 1 _{-C 21} hydroxyalkyl esters of (meth) acrylic acid such as acrylic acid 3-hydroxypropyl; (meth) acrylic acid, glycidyl (meth) acrylate, (meth) acrylamide Other (meth) acrylic such as (meth) acrylonitrile Such monomers and further styrene and the like, which may be used alone or in combination.

  In the present specification, “(meth) acryl” means “acryl or methacryl”, and “(meth) acrylate” means “acrylate or methacrylate”.

  For example, the acrylic modification of polyolefin is performed by, for example, an acrylic unsaturated monomer having reactivity with a carboxyl group in the unsaturated carboxylic acid or anhydride modified polyolefin produced as described above, for example, (meth) acrylic. It is carried out by reacting glycidyl acid or the like to introduce a polymerizable unsaturated group into the polyolefin, and then (co) polymerizing the polymerizable unsaturated group alone or in combination of two or more of the above acrylic unsaturated monomers. be able to. The amount of the acrylic unsaturated monomer used in the acrylic modification of the polyolefin can be changed depending on the properties desired for the modified polyolefin, but from the viewpoint of compatibility with other components and adhesion of the formed coating film. In general, it is desirable that the amount is 30% by weight or less, particularly 0.1 to 20% by weight, more particularly 0.15 to 15% by weight, based on the solid content weight of the resulting modified polyolefin.

  A chlorinated product of polyolefin can be produced by chlorinating polyolefin. The chlorination of polyolefin can be performed, for example, by blowing chlorine gas into an organic solvent solution or dispersion of polyolefin or a modified product thereof, and the reaction temperature can be 50 to 120 ° C. The chlorine content in the chlorinated polyolefin (solid content) can be changed according to the physical properties desired for the chlorinated polyolefin. Desirably, the amount is 35% by weight or less, particularly 10 to 30% by weight, more particularly 12 to 25% by weight, based on the weight of the compound.

  The polyolefin or modified polyolefin (A) used in the present invention is usually compatible with other components, from the viewpoints of adhesion of the formed coating film to the polyolefin base material and interlayer adhesion to the top coating film layer, The melting point is 120 ° C. or lower, preferably 30 to 110 ° C., more preferably 50 to 100 ° C., and the weight average molecular weight (Mw) is 50000 to 150,000, preferably 60000 to 135000, more preferably 70000 to 120,000. It is desirable to be within the range. The polyolefin or the modified polyolefin (A) generally has a heat of fusion of 1 to 50 mJ / mg, particularly 2 to 50 mJ / mg, from the viewpoint of adhesion of the formed coating film to the base material and interlayer adhesion to the top coat film layer. It is desirable to be in the range of 50 mJ / mg.

  Here, the melting point and heat of fusion of the polyolefin or modified polyolefin were measured using a scanning scanning calorimeter “DSC-5200” (trade name, manufactured by Seiko Denshi Kogyo Co., Ltd.) using 20 mg of polyolefin or modified polyolefin, and a temperature rising rate of 10 ° C. It was obtained by measuring the calorie at 1 / min. The melting point of the polyolefin or modified polyolefin can be adjusted by changing the monomer composition of the polyolefin, particularly the amount of the α-olefin monomer. When it is difficult to determine the heat of fusion, the sample can be heated to 120 ° C. and then cooled to room temperature at 10 ° C./min, and then the heat can be measured by the above method.

The weight average molecular weight of the polyolefin or modified polyolefin is a value obtained by converting the weight average molecular weight measured by gel permeation chromatography with reference to the weight average molecular weight of polystyrene, and “HLC / GPC150C” is used as a gel permeation chromatography apparatus. (Measured by Water, 60 cm × 1) and o-dichlorobenzene as a solvent, measured at a column temperature of 135 ° C. and a flow rate of 1.0 ml / min. The injection sample was prepared by dissolving at a temperature of 140 ° C. for 1 to 3 hours so as to obtain a solution concentration of 5 mg of polyolefin in 3.4 ml of o-dichlorobenzene. As a column for gel permeation chromatography, “GMH _HR- H (S) HT” (trade name, manufactured by Tosoh Corporation) can be used. The number average molecular weight can also be determined in the same manner as described above.

  Furthermore, the polyolefin or modified polyolefin (A) used in the present invention is generally a ratio of the weight average molecular weight to the number average molecular weight (Mw / M) in terms of compatibility with other components and adhesion of the formed coating film. It is desirable that Mn) is in the range of 1.5 to 7.0, preferably 1.8 to 5.0, more preferably 2.0 to 4.0.

  The polyolefin or modified polyolefin (A) can be used after being diluted with an organic solvent, or can be used as an aqueous dispersion.

  Examples of the organic solvent for diluting the polyolefin or modified polyolefin (A) include aromatic hydrocarbon solvents such as toluene, xylene and benzene; cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, cyclohexane Aliphatic hydrocarbon solvents such as octane and cyclonanone; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; and alcohol solvents such as ethanol, isopropanol and n-butanol These may be used alone or in combination of two or more.

  The water dispersion of the polyolefin or the modified polyolefin (A) is usually performed using an unsaturated carboxylic acid or an acid anhydride-modified polyolefin as a raw material, and neutralizing some or all of the carboxyl groups therein with an amine compound, and It can be carried out by dispersing in water with an emulsifier. From the viewpoint of improving water dispersibility, it is desirable to use neutralization and water dispersion with an emulsifier in combination.

  Examples of amine compounds used for neutralization include tertiary amines such as triethylamine, tributylamine, dimethylethanolamine and triethanolamine; secondary amines such as diethylamine, dibutylamine, diethanolamine and morpholine; propylamine and ethanolamine Examples include primary amines.

  When the amine compound is used, the amount used is preferably within a range of usually 0.1 to 1.0 molar equivalent with respect to the carboxyl group in the unsaturated carboxylic acid or anhydride modified polyolefin. .

  Examples of the emulsifier include polyoxyethylene monooleyl ether, polyoxyethylene monostearyl ether, polyoxyethylene monolauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene Ethylene octylphenyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan mono Nonionic emulsifiers such as laurate; sodium such as alkylsulfonic acid, alkylbenzenesulfonic acid, alkylphosphoric acid And anionic emulsifiers such as ammonium salts, and polyoxyalkylene group-containing anionic emulsifiers having an anionic group and a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group in one molecule, A reactive anionic emulsifier having the anionic group and a polymerizable unsaturated group in one molecule can also be used. These emulsifiers can be used alone or in combination of two or more.

  Said emulsifier can be normally used within the range of 1-20 weight part with respect to 100 weight part of solid content of unsaturated carboxylic acid or acid anhydride modified polyolefin.

  The aqueous dispersion of the unsaturated carboxylic acid or acid anhydride-modified polyolefin thus obtained is listed in the description of acrylic modification in the presence of the water-dispersed unsaturated carboxylic acid or acid anhydride-modified polyolefin, if necessary. By emulsion polymerization of such an acrylic unsaturated monomer, an aqueous dispersion of an acrylic-modified unsaturated carboxylic acid or acid anhydride-modified polyolefin can be obtained.

Ionic liquid (B) :
The ionic liquid (B) used in the coating composition of the present invention includes a molten salt (or molten salt) that is in a liquid state at room temperature. Ordinary salts are generally solid at room temperature, but molten salts are those in which specific cations and anions are ionically bonded and become liquid at room temperature. Here, the room temperature is a temperature of about 20 ° C., and the vicinity of the room temperature means a temperature of about 10 to about 40 ° C.

  Such an ionic liquid (B) contains ionic bonds of various combinations of one kind or two or more kinds of cations and one kind or two or more kinds of anions. A cation having at least one onium salt structure selected from ammonium salts, phosphonium salts and sulfonium salts is preferred.

  Examples of the ionic liquid (B) include quaternary ammonium cations having a nitrogen-containing heterocyclic structure such as imidazolium, pyridinium, pyrrolidinium, pyrazolidinium, isothiazolidinium, and isoxazolidinium having an alkyl chain, and aliphatic groups. Cations such as ammonium cation, phosphonium cation, sulfonium cation, tetrafluoroboric acid, hexafluorophosphoric acid, tris (trifluoromethylsulfonyl) nitric acid, tris (trifluoromethylsulfonyl) carbonic acid, trifluoromethylsulfonylimide, organic Examples include those containing a combination with an anion derived from carboxylic acid, halogen and the like. Here, examples of the organic carboxylic acid include lactic acid, and the halogen includes fluorine, chlorine, bromine, and iodine.

  Specific examples of the ionic liquid (B) include, for example, 1,2-dimethylimidazolium tetrafluoroborate, tetrabutylammonium bromide, hexadecyltributylphosphonium bromide, 1-butyl-3-methylimidazolium hexafluorophosphate, N-hexylpyridinium tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) Imido, 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1-ethyl-3-methylimidazolium triflate, 1-ethyl-3-methylimidazolium chloride N-butylpyridinium chloride, N, N-diethyl-N-methyl- (2-methoxyethyl) ammonium tetrafluoroborate, N, N-diethyl-N-methyl- (2-methoxyethyl) ammonium bis (trifluoromethylsulfonyl) ) Imido, 1-ethyl-3-methylimidazolium- (L) -lactate, 1-butyl-3-methylimidazolium- (L) -lactate and the like.

  As the ionic liquid (B), it is usually desirable to use a colorless and transparent liquid, but it may be colored in a range that does not affect the color of the formed coating film. There are ionic liquids (B) that are soluble in water and those that are hardly soluble or insoluble in water, but it is desirable to use different ionic liquids (B) depending on the form of the coating composition of the present invention. .

  The blending ratio of the ionic liquid (B) in the coating composition of the present invention can be changed according to the application or use form of the coating composition of the present invention, but points such as conductivity, adhesion, water resistance, etc. In general, it can be within the range of 0.5 to 30% by weight, preferably 0.75 to 20% by weight, more preferably 1 to 10% by weight, based on the weight of the non-volatile content of the coating composition. .

Coating composition :
The coating composition of the present invention contains the above-described polyolefin or modified polyolefin (A) and ionic liquid (B) as at least a part of the film-forming component, and is either organic solvent-based or aqueous-based. Form may be sufficient. The coating composition of this invention can contain the hydroxyl-containing resin (C) which has a hydroxyl value in the range of 5-200 mgKOH / g further as needed.

  The hydroxyl group-containing resin (C) includes resins having an average of two or more hydroxyl groups in one molecule, and examples of the resin species include acrylic resins, polyester resins, polyurethane resins, grafts of these resins, Examples include acrylic-modified or polyester-modified epoxy resins, and self-crosslinking resins such as blocked isocyanate group-containing polyester resins, and acrylic resins and polyester resins are particularly preferable. The hydroxyl group-containing resin (C) can be any one of an organic solvent dilution type, a non-aqueous dispersion type, a water-soluble type, and a water-dispersion type depending on the form of the coating composition.

  In general, the hydroxyl group-containing resin (C) desirably has a hydroxyl value in the range of 5 to 150 mgKOH / g, particularly 10 to 100 mgKOH / g, in view of compatibility with other components and curability of the formed coating film. .

  The blending ratio of the hydroxyl group-containing resin (C) can be changed depending on the form of the coating composition, but generally, polyolefin or modified polyolefin (A) / The solid content weight ratio of the hydroxyl group-containing resin (C) can be in the range of 10/90 to 100/0, preferably 20/80 to 85/15, and more preferably 25/75 to 60/40.

  When the coating composition of the present invention is an aqueous system, it can further contain a urethane dispersion as a vehicle component. Urethane dispersion is usually emulsified or self-emulsified while dispersing in water the urethane prepolymer obtained by reacting diol and diisocyanate in advance in the presence of an emulsifier, and if necessary, dimethylolalkanoic acid. Is a dispersion obtained by The urethane dispersion is generally 65% by weight based on the total solid content of the polyolefin or the modified polyolefin (A), the hydroxyl group-containing resin (C) and the crosslinking agent (D) described later, from the viewpoint of improving the physical properties of the coating film. In the following, it is desirable to blend in a range of 5 to 50% by weight, more particularly 10 to 40% by weight.

  The coating composition of the present invention may further contain a crosslinking agent (D) as necessary. As the crosslinking agent (D), an amino resin and / or a block polyisocyanate that can react with the hydroxyl group in the hydroxyl group-containing resin (C) is usually used. Further, when the coating composition contains a modified polyolefin having a carboxyl group, an epoxy compound that can react with the carboxyl group may be used as the crosslinking agent (D).

  As said amino resin, a melamine resin, a urea resin, a benzoguanamine resin etc. are mentioned, for example, Among these, a melamine resin is suitable. As the melamine resin, an alkyl etherified melamine resin etherified with an alkyl group such as methyl, ethyl, n-butyl, isobutyl, hexyl, 2-ethylhexyl is particularly preferable, and any type of hydrophobic or hydrophilic is used. It may be. These melamine resins may further have a methylol group, an imino group or the like. The amino resin usually has a number average molecular weight in the range of 500 to 5,000, particularly 800 to 3,000. The number average molecular weight of the amino resin is a value obtained by converting the weight average molecular weight measured by gel permeation chromatography at a flow rate of 1.0 ml / min using tetrahydrofuran as a solvent, based on the weight average molecular weight of polystyrene. is there. “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) can be used as the gel permeation chromatography device, and “TSKgel G-4000H × L” and “TSKgel G-3000H × L” can be used as columns. “TSKgel G-2500H × L”, “TSKgel G-2000H × L” (both manufactured by Tosoh Corporation, trade name), and the like can be used.

  The block polyisocyanate is obtained by blocking the isocyanate group of a polyisocyanate compound having two or more free isocyanate groups in one molecule with a blocking agent.

  Examples of the polyisocyanate compound include aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; burette type adducts and isocyanurate ring addition of these aliphatic polyisocyanates. Isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4- or -2,6-diisocyanate, 1,3- or 1,4-di (isocyanatomethyl) cyclohexane, 1, Alicyclic diisocyanates such as 4-cyclohexane diisocyanate, 1,3-cyclopentane diisocyanate, 1,2-cyclohexane diisocyanate; Type diisocyanate burette type adducts, isocyanurate cycloadducts; xylylene diisocyanate, tetramethylxylylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate, 1,4 Naphthalene diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, (m- or p-) phenylene diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethyl-4 , 4'-biphenylene diisocyanate, bis (4-isocyanatophenyl) sulfone, isopropylidenebis (4-phenylisocyanate) and the like; Burette type adduct of isocyanate, isocyanurate cycloadduct; hydrogenated MDI and derivatives of hydrogenated MDI; triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatobenzene , 2,4,6-triisocyanatotoluene, 4,4'-dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate, etc., polyisocyanate having three or more isocyanate groups in one molecule Burette type adducts, isocyanurate cycloadducts of these polyisocyanates; polyols such as ethylene glycol, propylene glycol, 1,4-butylene glycol, dimethylolpropionic acid, polyalkylene glycol, trimethylolpropane, hexanetriol Isocyanate group in the hydroxyl group of Urethane adduct in a ratio to be Amaryou made by reacting a polyisocyanate compound; biuret type adducts of these urethane adducts, can be mentioned isocyanurate ring adducts.

  The block polyisocyanate is obtained by adding a blocking agent to the isocyanate group of the above polyisocyanate compound, and the block polyisocyanate compound produced by the addition is stable at ordinary temperature, but the baking temperature of the coating film (usually about When heated to 100 to about 200 ° C., it is desirable that the blocking agent is dissociated to regenerate free isocyanate groups. Examples of the blocking agent satisfying such requirements include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; ε-caprolactam, Lactams such as δ-valerolactam, γ-butyrolactam, β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl Ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol Ethers such as ethyl ether, propylene glycol monomethyl ether and methoxymethanol; benzyl alcohol; glycolic acid; glycolic acid esters such as methyl glycolate, ethyl glycolate and butyl glycolate; lactic acid, methyl lactate, ethyl lactate and butyl lactate Lactic acid ester system: methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and other alcohol systems; formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, Oximes such as cyclohexanone oxime; dimethyl malonate, diethyl malonate, diisopropyl malonate, malonic acid Malonic acid dialkyl esters such as di-n-butyl, diethyl methylmalonate, benzylmethyl malonate, diphenyl malonate, methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, n-propyl acetoacetate, benzyl acetoacetate, phenylacetoacetate Active methylenes such as acetoacetate, acetylacetone, etc .; mercaptans such as butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol; acetanilide , Acetanisids, acetolides, acrylamides, methacrylamides, acetic acid amides, stearic acid amides, benzamides, etc. Imide systems such as taric acid imide and maleic acid imide; diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylysine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenylamine, etc .; imidazole, 2-ethylimidazole, etc. Imidazole series; pyrazole series such as 3,5-dimethylpyrazole; urea series such as urea, thiourea, ethylene urea, ethylenethiourea, diphenylurea; carbamate ester series such as phenyl N-phenylcarbamate; ethyleneimine, propylene Examples thereof include imine-based blocking agents such as imine; sulfite-based blocking agents such as sodium bisulfite and potassium bisulfite. Of these, block polyisocyanate using an active methylene-based blocking agent is particularly preferred from the viewpoint of low-temperature curability and compatibility with polyolefin or modified polyolefin (A) and hydroxyl group-containing resin (C).

  When the coating composition of the present invention is an aqueous system, a blocked polyisocyanate imparted with water dispersibility can be used as the block polyisocyanate as necessary. As the blocked polyisocyanate imparted with water dispersibility, for example, the isocyanate group of the polyisocyanate compound is blocked with a blocking agent containing a hydroxy monocarboxylic acid, and the carboxyl group introduced by the hydroxy monocarboxylic acid is neutralized. Blocked polyisocyanates imparted with water dispersibility, and those dispersed in water by addition or reaction of a surfactant or the like are included.

  The epoxy compound is not particularly limited as long as it has two or more epoxy groups in one molecule, and a known one can be used, for example, bisphenol type epoxy resin, novolak type epoxy resin. And polyethylene glycol diglycidyl ether.

  The content of the cross-linking agent (D) is generally in terms of compatibility with the polyolefin or modified polyolefin (A) and the hydroxyl group-containing resin (C), and the curability, adhesion, and water resistance of the formed coating film. The total solid content of the polyolefin or modified polyolefin (A) and the hydroxyl group-containing resin (C) is 40 parts by weight or less, preferably 3 to 30 parts by weight, more preferably 5 to 20 parts by weight. it can.

  The coating composition of this invention can contain a pigment (E) further as needed. The content of the pigment (E) is generally 0.5% per 100 parts by weight of the total solid content of the polyolefin or the modified polyolefin (A) and the hydroxyl group-containing resin (C) from the viewpoints of adhesion of the formed coating film and water resistance. It can be in the range of ˜200 parts by weight, preferably 0.75 to 175 parts by weight, more preferably 1 to 150 parts by weight.

  The pigment (E) includes color pigments, extender pigments, conductive pigments, and examples of the color pigments include titanium dioxide, bengara, aluminum paste, azo, and phthalocyanine. Examples include talc, silica, calcium carbonate, barium sulfate, zinc white (zinc oxide), and these can be used alone or in combination of two or more. The conductive pigment is not particularly limited as long as it can impart conductivity to the coating film to be formed, and any shape of particles, flakes, and fibers (including whiskers) can be used. For example, carbon powder such as conductive carbon black and graphite, and metal powder such as silver, nickel, copper, and aluminum are exemplified, and further, tin oxide doped with antimony and phosphorus are doped. Tin oxide, acicular titanium oxide surface coated with tin oxide / antimony, antimony oxide, zinc antimonate, indium tin oxide, carbon or graphite whisker surface coated with tin oxide, etc .; flake-like mica surface Tin oxide, antimony-doped tin oxide, tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), phosphorus-doped A pigment coated with at least one conductive metal oxide selected from the group consisting of tin oxide and nickel oxide; and a pigment having conductivity containing tin oxide and phosphorus on the surface of titanium dioxide particles. Or in combination of two or more.

  In particular, when the coating composition of the present invention is used as a white coating, it is desirable to use a white pigment as the pigment (E), particularly titanium oxide, and the average particle size thereof from the viewpoint of design and chemical resistance. It is preferable to use those having a diameter in the range of about 0.05 to about 2 μm, particularly 0.1 to 1 μm.

  The coating composition of the present invention can contain a terpene resin as required from the viewpoint of compatibility of the coating. Examples of the terpene resin include terpenes, terpene-phenols, and hydrogenated products of aromatic modified terpene resins. The terpene resin preferably has a melting point of 30 to 120 ° C, particularly 40 to 100 ° C. Melting | fusing point of this terpene resin can be measured by the method similar to the said polyolefin or modified polyolefin (A). The terpene resin is usually 30% by weight or less, preferably 5 to 20% by weight based on the total solid content of the polyolefin or modified polyolefin (A), the hydroxyl group-containing resin (C) and the crosslinking agent (D). It is desirable to blend within the range.

  If necessary, the coating composition of the present invention may further contain coating additives such as a curing catalyst, a rheology control agent, an antifoaming agent, and an organic solvent.

Painting method :
The coating composition of the present invention is applied to a surface to be coated which is desired to impart conductivity to the surface. Such an object to be coated is not particularly limited, but a plastic molded product is particularly preferable from the viewpoint of imparting conductivity.

  Examples of plastic molded products include automobile outer plate parts such as bumpers, spoilers, grills, and fenders; plastic molded products used for outer plate parts of home appliances, etc. Polyolefins obtained by (co) polymerizing one or more of olefins having 2 to 10 carbon atoms such as ethylene, propylene, butylene, hexene and the like are particularly suitable. Besides these, polycarbonate, ABS resin, urethane The coating composition of the present invention can also be applied to resins, polyamides and the like.

  Prior to application of the coating composition of the present invention, these plastic molded products can be appropriately subjected to degreasing treatment, washing treatment, and the like by a method known per se.

  The coating of the coating composition of the present invention is usually applied to an object by air spray, airless spray, dip coating, brush, etc. so that the dry film thickness is in the range of 1 to 30 μm, preferably 3 to 15 μm. Can be used. After application of the coating composition, the resulting coated surface can be set at room temperature for 1 to 60 minutes as necessary, or preheated at a temperature of about 40 to 80 ° C. for 1 to 60 minutes, or about 60 It can be cured by heating for about 20 to 40 minutes at a temperature of about 140 ° C., preferably about 70 to about 120 ° C.

The coating film formed as described above easily has a surface resistivity of 1 × 10 ⁸ Ω / □ or less, and can be satisfactorily electrostatically coated in the next step as a conductive primer coating film. In the present specification, the “surface resistivity” is measured by drying a coating film coated so that the dry film thickness is about 20 μm at 80 ° for 10 minutes, a surface resistance meter manufactured by TREK, It can be carried out using the trade name “TREK MODEL 150” (unit: Ω / □).

  In the present invention, a coating film formed from the coating composition of the present invention can be used as a primer coating, and a colored base coating and a clear coating can be sequentially applied thereon.

  As the colored base paint, those known per se can be used. Usually, an organic solvent and / or water as a main solvent, a colored component such as a colored pigment, a bright pigment, and a dye, a base resin, and a crosslinking agent are used. Those containing a resin component such as are used.

  Examples of the base resin used in the colored base paint include acrylic resins having a crosslinkable functional group such as a hydroxyl group, an epoxy group, a carboxyl group, and a silanol group, a polyester resin, and an alkyd resin. Examples of the crosslinking agent include amino resins such as melamine resin and urea resin that can react with these functional groups, (block) polyisocyanate, polyepoxide, and polycarboxylic acid.

  If necessary, the colored base paint further contains extender pigments, curing catalysts, UV absorbers, coating surface preparation agents, rheology control agents, antioxidants, antifoaming agents, wax additives such as paints, and the like. Can be included.

  The colored base coating is usually electrostatically coated on the uncured or cured conductive primer coating so as to have a dry film thickness of 3 to 50 μm, preferably 5 to 20 μm, The resulting coated surface can be set at room temperature for 1 to 60 minutes as necessary, or preheated at a temperature of about 40 to about 80 ° C for 1 to 60 minutes, or about 60 to about 140 ° C, preferably It can be cured by heating at a temperature of about 70 to about 120 ° C. for about 20 to 40 minutes.

  In particular, when the coating composition of the present invention forms a high white primer coating, a high white pearl-tone multi-layer coating can be formed by applying an interference pearl color base coating thereon. Furthermore, a white base paint and an interference pearl base paint may be sequentially applied as the colored base coating layer to form a multilayer film.

  The clear paint contains a resin component such as a base resin and a crosslinking agent, an organic solvent, water, and the like, and further, an ultraviolet absorber, a light stabilizer, a curing catalyst, a coating surface conditioner, and a rheology control as necessary. An organic solvent-based or water-based thermosetting coating containing additives such as an agent, an antioxidant, an antifoaming agent, and a wax, and a lower layer coating through the clear coating formed It is possible to use a material having such a transparency that can be visually recognized.

  Examples of the base resin include an acrylic resin, a polyester resin, an alkyd resin, a fluororesin, a urethane resin, and a silicon-containing resin containing at least one crosslinkable functional group such as a hydroxyl group, a carboxyl group, a silanol group, and an epoxy group. In particular, a hydroxyl group-containing acrylic resin is suitable. Examples of the crosslinking agent include melamine resin, urea resin, (block) polyisocyanate compound, epoxy compound, carboxyl group-containing compound, acid anhydride, alkoxysilane group-containing compound, etc., which can react with these functional groups. Isocyanate compounds are preferred.

  The clear coating is applied on an uncured or cured colored base coating film by electrostatic coating so that the dry film thickness is within the range of 10 to 50 μm, preferably 15 to 45 μm. The surface is optionally set at room temperature for 1-60 minutes or preheated at a temperature of about 40 to about 80 ° C. for 1-60 minutes, then about 60 to about 140 ° C., preferably about 80 to about 120 ° C. It can be cured by heating at a temperature for about 20 to 40 minutes.

  Thus, a plastic molded article in which the colored base coating and the clear coating are electrostatically coated on the conductive primer coating can be obtained.

  Hereinafter, the present invention will be described more specifically with reference to examples. “Parts” and “%” represent “parts by weight” and “% by weight” unless otherwise specified.

Example 1
Aqueous chlorinated polypropylene (A-1) (maleic acid-modified chlorinated polypropylene water having a melting point of 70 ° C., a weight average molecular weight of about 90,000, an acid value by maleic acid modification of 35 mg KOH / g and a chlorine content of 22% 30 parts by weight of the solid dispersion, 30 parts by weight of the acrylic emulsion having a hydroxyl value of 30 mg KOH / g, and 30 parts by weight of “WS-5000” (Mitsui Takeda Chemicals, urethane dispersion). Parts, "X-03-101B" (manufactured by Asahi Kasei Co., Ltd., active methylene adduct of polyethylene oxide-modified polyisocyanate) by solids weight, 10 parts by weight, "TITANIX JR-903" (manufactured by Teika, titanium white) And 5 parts of 1-ethyl-3-methylimidazolium triflate are blended according to a conventional method to give a solid content of 43%. As such, it was diluted with deionized water to obtain a conductive coating composition (1).

Example 2
Aqueous polypropylene / ethylene copolymer (A-2) (maleic acid having a propylene / ethylene copolymer ratio of 96/4 by weight, a melting point of 40 ° C., a weight average molecular weight of about 60,000 and an acid value of 40 mgKOH / g) Modified propylene / ethylene copolymer aqueous dispersion) is 30 parts by weight in terms of solid content, 30 parts by weight of a water-soluble acrylic resin having a hydroxyl value of 30 mg KOH / g, and 30 parts by weight of “WS-5000”. 10 parts by weight of “X-03-101B”, 100 parts of “TITANIX JR-903” and 5 parts of 1-ethyl-3-methylimidazolium triflate according to a conventional method, % Was diluted with deionized water to obtain a conductive coating composition (2).

Example 3
Maleic acid-modified chlorinated polypropylene (A-3) (Toluene solution of maleic acid-modified chlorinated polypropylene having a melting point of 80 ° C., a weight average molecular weight of about 90,000, an acid value of 10 mg KOH / g, and a chlorine content of 20%) 40 parts by weight of solid content, 40 parts by weight of polyester resin having a hydroxyl value of 20 mgKOH / g, 10 parts by weight of “Cymel 325” (made by Nippon Cytec Industries, Inc., melamine resin), “TITANIX JR -903 "and 100 parts of 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide were blended in accordance with a conventional method, and diluted with toluene so that the solid content was 40%. A composition (3) was obtained.

Example 4
Acrylic modified chlorinated polypropylene (A-4) (melting point is 90 ° C., weight average molecular weight is about 110,000, acid value is 10 mg KOH / g, modified with cyclohexyl methacrylate / propylene = 5/95 ratio and maleic acid modified. 40 parts by weight of a chlorinated polypropylene toluene solution having a chlorine content of 18%), 40 parts by weight of a polyester resin having a hydroxyl value of 20 mg KOH / g, and 10 parts of “Cymel 325” by weight of solids. 100 parts of “TITANIX JR-903”, 1 part of “Ketjen Black EC600J” (manufactured by Lion Akzo Co., Ltd., conductive carbon black pigment) and 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) ) 7 parts of imide was blended in accordance with a conventional method, so that the amount of solid was 41%. The conductive coating composition (4) was obtained by diluting with water.

Example 5
30 parts by weight of aqueous polypropylene / ethylene copolymer (A-2), 30 parts by weight of water-soluble acrylic resin having a hydroxyl value of 30 mgKOH / g, and 30 parts by weight of “WS-5000”. 10 parts by weight of “X-03-101B”, 100 parts of “TITANIX JR-903” and 5 parts of 1-ethyl-3-methylimidazolium tetrafluoroborate according to a conventional method. The conductive coating composition (5) was obtained by diluting with deionized water so that the content was 40%.

Example 6
30 parts by weight of an aqueous chlorinated polypropylene (A-1) in solids weight, 30 parts by weight of an acrylic emulsion having a hydroxyl value of 30 mgKOH / g, 30 parts by weight in solids of “WS-5000”, “X- "03-101B" by solid weight, 10 parts by weight, "Dentol WK500" (manufactured by Otsuka Chemical Co., Ltd., acicular titanium oxide surface-coated with tin oxide / antimony) 130 parts and 1-ethyl-3-methylimidazolium 5 parts of tetrafluoroborate was blended according to a conventional method, and diluted with deionized water so as to have a solid content of 43% to obtain a coating composition (6).

Example 7
Aqueous polypropylene / ethylene copolymer (A-5) (maleic acid having a propylene / ethylene copolymer ratio of 96/4 by weight, a melting point of 40 ° C., a weight average molecular weight of about 100,000 and an acid value of 40 mgKOH / g) (Modified propylene / ethylene copolymer aqueous dispersion) 100 parts by weight in solid content, 130 parts of “TITANIX JR-806” and 3 parts of 1,2-dimethylimidazolium tetrafluoroborate are blended according to a conventional method, The conductive coating composition (7) was obtained by diluting with deionized water to a solid content of 40%.

Example 8
100 parts by weight of aqueous chlorinated polypropylene (A-1), 130 parts of “TITANIX JR-806” and 3 parts of 1,2-dimethylimidazolium tetrafluoroborate were blended according to a conventional method to obtain a solid content of 40 % Was diluted with deionized water to obtain a conductive coating composition (8).

Example 9
50 parts by weight of aqueous polypropylene / ethylene copolymer (A-2) in solid weight, 50 parts by weight of acrylic emulsion having a hydroxyl value of 50 mg KOH / g, 130 parts of “TITANIX JR-806”, “Denacol EX512” 3 parts of polyethylene glycol diglycidyl ether (manufactured by Nagase Chemtech Co., Ltd.) and 3 parts of 1,2-dimethylimidazolium tetrafluoroborate are mixed according to a conventional method, and diluted with deionized water to a solid content of 40% As a result, a conductive coating composition (9) was obtained.

Comparative Example 1
30 parts by weight of an aqueous chlorinated polypropylene (A-1) in solid weight, 30 parts by weight of an acrylic emulsion having a hydroxyl value of 30 mgKOH / g, 30 parts by weight of “WS-5000”, “X- "03-101B" in a solid content weight of 10 parts and "TITANIX JR-903" (Taika, Titanium White) are blended according to a conventional method, and diluted with deionized water to a solid content of 40%. Thus, a coating composition (10) was obtained.

Comparative Example 2
40 parts by weight of solid content weight of chlorinated polypropylene (A-3), 40 parts by weight of polyester resin having a hydroxyl value of 20 mgKOH / g, 10 parts by weight of “Cymel 325”, “TITANIX JR-903” 100 parts were blended according to a conventional method and diluted with toluene so as to have a solid content of 35% to obtain a coating composition (11).

Comparative Example 3
30 parts by weight of an aqueous chlorinated polypropylene (A-1) in solids weight, 30 parts by weight of an acrylic emulsion having a hydroxyl value of 30 mgKOH / g, 30 parts by weight in solids of “WS-5000”, “X- "03-101B" in a solid content weight of 10 parts and "Dentor WK500" (manufactured by Otsuka Chemical Co., Ltd., acicular titanium oxide surface-coated with tin oxide / antimony) were blended according to a conventional method to obtain a solid content of 43 % Was diluted with deionized water to obtain a coating composition (12).

Preparation of test paint Example 10
After spray coating the conductive coating composition (1) prepared as described above on a polypropylene plate (degreased) to a dry film thickness of about 20 μm to form a primer coating layer, the uncured coating “WBC # 713T Mica Base” (water-based transparent colored base coat paint, manufactured by Kansai Paint Co., Ltd.) is electrostatically applied on the film to a dry film thickness of about 15 μm, preheated at 80 ° C. for 10 minutes, and then used as a clear paint. K # 5001T "(manufactured by Kansai Paint Co., Ltd., acrylic urethane two-component solvent-based clear paint) is electrostatically coated to a dry film thickness of about 30 μm, and heated and dried at 120 ° C. for 30 minutes to prepare a test coating plate. Produced.

Examples 11 to 18 and Comparative Example 6
In Example 10 above, each test coated plate was produced in the same manner as in Example 10 except that the coating composition shown in Table 1 was used as a primer.

Comparative Example 4
After forming a primer coating layer by spray-coating the coating composition (10) prepared as described above on a polypropylene plate (degreased) to a dry film thickness of about 20 μm, When “WBC # 713T Mica Base” was electrostatically coated to a dry film thickness of about 15 μm, it was difficult to apply. Therefore, instead of the electrostatic coating, the same base coat paint was used with a dry film thickness of about 15 μm. After spraying at 80 ° C. for 10 minutes, “K # 5001T” (manufactured by Kansai Paint Co., Ltd., acrylic urethane two-component solvent-based clear paint) is about 30 μm in dry film thickness. The test coating plate was produced by spray coating as described above and drying by heating at 120 ° C. for 30 minutes.

Comparative Example 5
In Comparative Example 4, a test coated plate was produced in the same manner as in Comparative Example 4 except that the coating composition shown in Table 1 was used as a primer.

  Each test painted plate produced as described above was subjected to the following performance test. The results are shown in Table 1.

Performance test method (* 1) Surface resistivity of primer coating surface:
After heating the primer coating film formed by spray-coating each coating composition (1) to (12) on a polypropylene plate (degreased) to a dry film thickness of about 20 μm at 80 ° C. for 10 minutes. The surface resistivity (Ω / □) of each coating film surface was measured at 20 ° C. with “MODEL150” (manufactured by TREK).

(* 2) Coating efficiency:
Electrostatic coating in each of the examples and comparative examples was performed using a Landsberg microbell (bell diameter: 50 mmφ), a paint discharge rate of 200 cc / min, a bell head rotation speed of 30,000 rpm, a bell head applied voltage of −60 kV, The coating efficiency at the vertical part was calculated according to the following formula under the condition that the distance between the bell head of the coating machine and the surface to be coated was 25 cm.

Coating efficiency (%) = (solid weight of the paint applied to the coated surface) / (of the paint used for coating)
Solid weight) x 100
○ indicates that the coating efficiency is 70% or more, and x indicates that the coating efficiency is less than 70%.

(* 3) Lightness (L value):
After heating the primer coating film formed by spray-coating each coating composition (1) to (12) on a polypropylene plate (degreased) to a dry film thickness of about 20 μm at 80 ° C. for 10 minutes. The brightness of each coating film surface was measured with “Color Computer SM-7” (manufactured by Suga Test Instruments Co., Ltd.).

  Subsequently, the brightness of each multilayer coating film surface of each test coating plate obtained in Examples 10 to 18 and Comparative Examples 4 to 6 was measured in the same manner.

(* 4) Initial adhesion:
Cut lines with a cutter to reach the substrate on each coating surface of each test coating plate obtained in Examples 10 to 18 and Comparative Examples 4 to 6, and make 100 squares with a size of 2 mm x 2 mm. Adhesive cellophane tape was stuck on the surface, and the number of residual coatings in the grid after the abrupt peeling at 20 ° C. was examined. No peeling was marked with ◯, and peeling over 1 square was marked with x.

(* 5) Water resistance:
Each test coated plate obtained in Examples 10 to 18 and Comparative Examples 4 to 6 was immersed in warm water at 40 ° C. for 10 days, pulled up and dried, and then the coated surface was visually evaluated. ○ indicates no occurrence of blister, and × indicates occurrence of blister.

Claims (16)

  A coating composition comprising a polyolefin or a modified polyolefin (A) and an ionic liquid (B).   The coating composition according to claim 1, wherein the modified polyolefin is a modified polyolefin obtained by using an unsaturated carboxylic acid or acid anhydride modified product, an acrylic modified product, a chlorinated product, or a combination of these modified products.   The coating composition according to claim 1 or 2, wherein the polyolefin or the modified polyolefin (A) has a melting point of 120 ° C or lower and a weight average molecular weight in the range of 50,000 to 150,000.   The coating composition according to any one of claims 1 to 3, wherein the polyolefin or the modified polyolefin (A) has a heat of fusion within a range of 1 to 50 mJ / mg.   The coating composition according to any one of claims 1 to 4, wherein the ionic liquid (B) contains a cation having an onium salt structure.   The ionic liquid (B) is 1,2-dimethylimidazolium tetrafluoroborate, tetrabutylammonium bromide, hexadecyltributylphosphonium bromide, 1-butyl-3-methylimidazolium hexafluorophosphate, N-hexylpyridinium tetrafluoroborate 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1-butyl-3 -Methylimidazolium bis (trifluoromethylsulfonyl) imide, 1-ethyl-3-methylimidazolium triflate, 1-ethyl-3-methylimidazolium chloride, N-butylpyridinium Loride, N, N-diethyl-N-methyl- (2-methoxyethyl) ammonium tetrafluoroborate, N, N-diethyl-N-methyl- (2-methoxyethyl) ammonium bis (trifluoromethylsulfonyl) imide, 1 The coating composition according to any one of claims 1 to 5, which is selected from the group consisting of -ethyl-3-methylimidazolium- (L) -lactate and 1-butyl-3-methylimidazolium- (L) -lactate. object.   The coating composition according to any one of claims 1 to 6, which contains the ionic liquid (B) in a range of 0.5 to 30% by weight based on the nonvolatile content of the coating composition.   The coating composition according to any one of claims 1 to 7, further comprising a hydroxyl group-containing resin (C) having a hydroxyl value in the range of 5 to 200 mgKOH / g.   The coating composition according to claim 8, wherein the hydroxyl group-containing resin (C) is contained in a proportion within a range of 10/90 to 100/0 in terms of a solid weight ratio of polyolefin or modified polyolefin (A) / hydroxyl group-containing resin (C). object.   The coating composition according to any one of claims 1 to 9, further comprising a crosslinking agent (D).   The coating composition according to claim 10, wherein the crosslinking agent (D) is an amino resin or a blocked polyisocyanate.   The coating composition according to any one of claims 1 to 11, further comprising a pigment (E).   The coating composition according to claim 1, which is a white paint containing a white pigment.   A coating method comprising coating the coating composition according to any one of claims 1 to 13 on a surface to be coated.   The coating method according to claim 14, wherein the article to be coated is a plastic molded product.   A coated article obtained by the coating method according to claim 14 or 15.