JP4982671B2 - CLEAR COATING COMPOSITION AND COATED ARTICLE COMPRISING THE SAME - Google Patents

Description

  The present invention relates to a clear coating composition and a coated article comprising the same.

  Conventional products coated with a solvent-soluble fluororesin clear coating have problems such as being contaminated by automobile exhaust gas, dust, and the like when exposed to the outdoors for a long period of time, resulting in decreased transparency. In particular, when a resin-coated product made of a polycarbonate resin or the like is coated with a conventional solvent-soluble fluororesin clear paint, when exposed to the outdoors for a long period of time, in addition to contamination by automobile exhaust gas, dust, etc., There was a problem that transparency was lowered due to resin deterioration of the resin molded product itself due to ultraviolet rays of sunlight transmitted through the coating film.

  Furthermore, resin molded products made of polycarbonate resin, etc. have poor solvent resistance, and when coated with a coating material, haze, whitening, cracks, etc. are likely to occur. In addition, solvents having low dissolving power such as saturated hydrocarbons and alcohol solvents have been used. Further, even when coating film defects such as haze, whitening, and cracks do not occur, generally, the adhesion between the coating material and a resin molded product made of polycarbonate resin is low.

  On the other hand, conventional solvent-soluble fluororesin coatings require polar solvents with high solubility, such as aromatics, esters, and ketones, and use polyisocyanates as curing agents, so alcoholic solvents are used. It was impossible. Therefore, when coating a resin molded product such as polycarbonate resin with a conventional solvent-soluble fluororesin paint, it is saturated to prevent deterioration of the resin molded product surface due to the solvent and to obtain sufficient coating film adhesion. It has been necessary to pre-coat a primer using a specific resin that is soluble in a solvent having a low solubility such as a hydrocarbon-based or alcohol-based solvent and has sufficient adhesion to a resin molded product. By using a primer, a conventional solvent-soluble fluororesin coating can be applied, but there is a problem that the coating process becomes complicated with 2 coats and 2 bake, leading to an increase in the cost of the coated product.

  As a method for solving such a problem, for example, Patent Document 1 discloses a coating composition for a synthetic resin containing a solvent containing 20% by weight or more of a fluoroolefin-vinyl ether copolymer and cyclohexanone. Although the coating composition can be coated with one coat and one bake without requiring a primer for the synthetic resin, there is a problem that when the synthetic resin molded article has poor solvent resistance, haze increases and transparency is impaired. .

  Therefore, when exposed to the outdoors for a long period of time, it solves the problem that transparency is lowered due to contamination by automobile exhaust gas, dust, etc. and resin deterioration of the resin molded product itself such as polycarbonate resin. Currently, there is no clear coating composition that can be applied in one coat and one bake without requiring primer coating on the resin molded product. In particular, there is no clear coating composition for resin moldings having transparency that satisfies the appearance and optical properties.

Japanese Patent No. 2613202

  The present invention solves such a conventional problem, can maintain high transparency even after being exposed to the outdoors for a long time, has low solvent resistance, and generally provides sufficient adhesion to a paint. It is an object of the present invention to provide a clear coating composition capable of being applied to a resin molded product such as a difficult polycarbonate resin without damaging high transparency with one coat and one bake, and a coated product comprising the same.

That is, the present invention provides (A) a coating composition containing a resin composition containing a hydroxyl group-containing fluororesin and an isocyanate curing agent, per 100 parts by weight of resin solids,
(B) 0.01 to 1.0 part by weight of a fluorosurfactant,
(C) 1 to 15 parts by weight of an ultraviolet absorber,
(D) It is related with the clear coating composition containing 1-30 weight part of organosilicate compounds.

  (E) It preferably contains a solvent containing 5 to 20% by weight of cyclohexanone and 10 to 50% by weight of diisobutyl ketone.

  The hydroxyl group-containing fluororesin is preferably a fluoroolefin-vinyl ether copolymer containing 20 to 80% by weight of fluoroolefin units and 80 to 20% by weight of vinyl ether units.

  The fluorosurfactant (B) is preferably one or more surfactants selected from the group consisting of perfluoroalkyl-containing oligomers, perfluoroalkyl-containing polymers, and polysiloxanes containing fluoroalkyl groups.

  The ultraviolet absorber (C) is preferably a hydroxylphenyltriazine-based ultraviolet absorber.

  The organosilicate compound (D) has the general formula (1):

（式中、Ｒ¹〜Ｒ⁴は、それぞれ同じかまたは異なり、炭素数１〜４のアルキル基である。ｎは、１０より大きく３０以下の整数である。）
で表される化合物であることが好ましい。

(In the formula, R ^{1 to} R ⁴ are the same or different and are each an alkyl group having 1 to 4 carbon atoms. N is an integer greater than 10 and 30 or less.)
It is preferable that it is a compound represented by these.

  The present invention also relates to a coated product having a coating film comprising the clear coating composition.

  The present invention can maintain adhesion and high transparency even after being exposed to the outdoors for a long period of time, has poor solvent resistance, and generally is a resin molded product such as a polycarbonate resin that is difficult to obtain sufficient adhesion with a paint, particularly For those having transparency, it is possible to provide a clear coating composition that can be coated without impairing high transparency by one coat and one bake, and a coated product comprising the same.

The present invention provides (A) a coating composition containing a resin composition containing a hydroxyl group-containing fluororesin and an isocyanate curing agent, per 100 parts by weight of resin solids,
(B) 0.01 to 1.0 part by weight of a fluorosurfactant,
(C) 1 to 15 parts by weight of an ultraviolet absorber,
(D) It is related with the clear coating composition containing 1-30 weight part of organosilicate compounds.

  The resin composition (A) contains a hydroxyl group-containing fluororesin and an isocyanate curing agent.

  The method of introducing a hydroxyl group into the fluororesin is not particularly limited, and examples thereof include a method of copolymerizing a hydroxyl group-containing monomer when polymerizing a fluoroolefin.

  Hydroxyl-containing monomers include hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxypentyl vinyl ether and other hydroxyalkyl vinyl ethers, ethylene glycol monoallyl ether, diethylene glycol monoallyl ether, and triethylene glycol monoallyl ether. Examples include ether, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

Further, as the fluoroolefin, the general formula (2):
R ⁵ R ⁶ C = CFR ⁷ (2)
(In the formula, R ^{5 to} R ⁷ may be the same or different, and each represents a hydrogen atom, a fluorine atom, a chlorine atom, a monovalent alkyl group or a monovalent fluoroalkyl group.)
The monomer represented by can be mentioned.

  Examples of the monovalent alkyl group include alkyl groups having 1 to 10 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the monovalent fluoroalkyl group include a fluoroalkyl group in which one or more hydrogen atoms in the alkyl group are substituted with a fluorine atom.

  Specific examples of the monomer represented by the general formula (2) include vinyl fluoride, vinylidene fluoride, chlorotrifluoroethylene, and tetrafluoroethylene.

  The monomer other than the fluoroolefin and the hydroxyl group-containing monomer is not particularly limited, and any monomer that can be copolymerized with the fluoroolefin and the hydroxyl group-containing monomer can be used. For example, α-olefins such as ethylene, propylene, isobutylene and butylene-1; vinyl ethers such as ethyl vinyl ether, isobutyl vinyl ether, butyl vinyl ether and cyclohexyl vinyl ether; vinyl acetate, vinyl lactate, vinyl butyrate, vinyl isobutyrate, vinyl caproate Fatty acid vinyl esters such as vinyl pivalate and vinyl caprylate; fatty acid isopropenyl esters such as isopropenyl acetate and isopropenyl propionate, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic Propyl acid, isopropyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexane (meth) acrylate Alkyl (carbon number 1 to 18) ester of (meth) acrylic acid such as sil; ethylenically unsaturated carboxylic acid such as acrylic acid and methacrylic acid: vinyl aromatic monomers such as styrene, α-methylstyrene, vinyltoluene; acrylic Acid or methacrylic acid amide compounds and derivatives thereof; Acrylonitrile, methacrylonitrile and the like, ethylenically unsaturated carboxylic acids such as acrylic acid and methacrylic acid: vinyl aromatic monomers such as styrene, α-methylstyrene and vinyltoluene; acrylic acid Examples thereof include amide compounds of methacrylic acid and derivatives thereof; acrylonitrile, methacrylonitrile, or those in which one or more hydrogen atoms in these monomers are substituted with fluorine atoms.

  Among these, if the copolymerization ratio of the fluoroolefin is too small, excellent weather resistance tends to be not obtained, and if the copolymerization ratio of the fluoroolefin is too large, the solubility in a solvent is lowered. It is preferably a fluoroolefin-vinyl ether copolymer containing 20 to 80% by weight of olefin units and 80 to 20% by weight of vinyl ether units, 40 to 70% by weight of fluoroolefin units, and 60 to 30% by weight of vinyl ether units. % Of fluoroolefin-vinyl ether copolymer is more preferred.

  The number average molecular weight of the hydroxyl group-containing fluororesin used in the present invention is preferably 2,000 to 100,000, and more preferably 5,000 to 30,000. If the number average molecular weight is less than 2,000, the durability and stain resistance of the coating film tend to be lowered. If the number average molecular weight is more than 100,000, the compatibility with the isocyanate curing agent is lowered and the paint is stored. There is a tendency for stability to decrease.

  The hydroxyl value of the hydroxyl group-containing fluororesin used in the present invention is preferably 20 to 200 mgKOH / g, and more preferably 20 to 150 mgKOH / g. When the hydroxyl value is less than 20 mgKOH / g, the durability and stain resistance of the coating film tend to be lowered. When the hydroxyl value exceeds 200 mgKOH / g, the durability, water resistance and stain resistance of the coating film are lowered. Tend.

  Examples of the isocyanate curing agent include isocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate, dimers and trimers thereof, and reaction products with water or alcohols. .

  The mixing ratio of the hydroxyl group-containing fluororesin and the isocyanate curing agent is preferably such that the isocyanate group of the isocyanate curing agent is 0.8 to 2.0 mol with respect to 1 mol of the hydroxyl group of the hydroxyl group-containing fluororesin. More preferably, it is -1.5 mol. If it is less than 0.8 mol, the coating film will be insufficiently cured and solvent resistance and stain resistance will tend to be reduced. If it exceeds 2.0 mol, unreacted isocyanate groups will remain in the coating film. , Weather resistance and contamination resistance tend to decrease.

  The clear coating composition of the present invention has a low solvent resistance and is generally applied to a resin molded product such as a polycarbonate resin, which is difficult to obtain sufficient adhesion to a paint, without damaging high transparency in one coat and one bake. It is preferable to use a solvent (E) containing 5 to 20% by weight of cyclohexanone and 10 to 50% by weight of diisobutyl ketone, and 7 to 15% by weight of cyclohexanone and 15 to 40% by weight of diisobutyl ketone. More preferred. When the content is less than 5% by weight of the cyclohexanone, in the transparent coated product coated on the polycarbonate resin or the like, the coating film adhesion tends to decrease, and when it exceeds 20% by weight, the haze increases and the transparency tends to be impaired. By adding 10 to 50% by weight of diisobutyl ketone to the solvent (E) used in the present invention, high transparency can be obtained.

  In addition, solvents other than cyclohexanone and diisobutylketone contained in the solvent (E) include aromatic hydrocarbons such as toluene and xylene, saturated hydrocarbons such as n-hexane, n-heptane, n-octane and mineral spirits. , Halogenated hydrocarbons such as methylene chloride, trichlorethylene, trichloroethane, perchloroethylene, alkyl ethers such as ethyl ether and dipropyl ether, esters such as ethyl acetate, cellosolve acetate, butyl acetate, acetone, methyl ethyl ketone, methyl Examples thereof include ketones such as isobutyl ketone. Among these, from the viewpoint of solubility in the resin composition (A), ketones are preferable, and methyl isobutyl ketone is more preferable.

  The addition amount of the solvent other than cyclohexanone and diisobutyl ketone is not particularly limited as long as it is 100% by weight in total with cyclohexanone and diisobutyl ketone, but is 30 to 85 in the solvent (E). It is preferable that it is weight%, and it is more preferable that it is 35-70 weight%.

  In solvents other than cyclohexanone and diisobutylketone, when there are many aromatic hydrocarbons, halogenated hydrocarbons, esters, and ketones, transparent coated products coated on polycarbonate resin, etc. have cracks, haze, and whitening on the surface. When there is much saturated hydrocarbon, there exists a tendency for the solubility with respect to a resin composition (A) to become inadequate and to become difficult to obtain a uniform coating.

  The solubility parameter (hereinafter referred to as SP value) of cyclohexanone used in the solvent (E) is 9.9, and the hydroxyl group-containing fluororesin (SP value 10.2) and polycarbonate resin (SP value 9.8) used in the present invention. ) Are excellent in solubility. Therefore, in the coating to polycarbonate resin, cyclohexanone causes swelling / dissolution of the substrate surface, and helps the diffusion / dissolution of the resin composition (A) in the coating composition into the substrate. A layer can be formed.

  The addition amount of the solvent (E) is not particularly limited, but is preferably 150 to 500 parts by weight, preferably 200 to 400 parts by weight per 100 parts by weight of the resin solid content of the resin composition (A). More preferably. If the addition amount of the solvent (E) is less than 150 parts by weight, the smoothness of the coating film tends to decrease when the vertical surface is coated with air spray or the like. When coated with, the film thickness cannot be ensured and the weather resistance tends to decrease.

  Examples of the fluorosurfactant (B) include perfluoroalkyl-containing oligomers, perfluoroalkyl-containing polymers, polysiloxanes containing fluoroalkyl groups, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl carboxylates, perfluoroalkyl phosphorus. Examples thereof include acid esters, perfluoroalkyltrimethylammonium salts, and perfluoroalkylbetaines. Among these, at least one selected from the group consisting of a perfluoroalkyl-containing oligomer, a perfluoroalkyl-containing polymer, and a polysiloxane containing a fluoroalkyl group from the viewpoint that the compatibility with a resin and a solvent and stain resistance are reduced. It is preferable that it is surfactant.

  Specifically, examples of the perfluoroalkyl-containing oligomer include MEGAFAC F-477 (Dainippon Ink Industries Co., Ltd.), and examples of the perfluoroalkyl-containing polymer include Surflon S-393 (Seimi Chemical Co., Ltd.). Examples of the polysiloxane containing a fluoroalkyl group include EFKA-3034 (manufactured by EFKA).

  By using a fluorine-type surfactant (B), the surface tension of a coating composition can be reduced and the wettability with respect to polycarbonate resin etc. can be improved. As a result, sufficient adhesion can be obtained even when the content of cyclohexanone is 5 to 20% by weight, which is less than the conventionally used amount.

  The amount of the fluorosurfactant (B) added is preferably 0.01 to 1.0 part by weight per 100 parts by weight of the resin solid content of the resin composition (A), and 0.02 to 0. More preferably, it is 0.07 part by weight. When the addition amount of the fluorosurfactant (B) is less than 0.01 parts by weight, the wettability with respect to the polycarbonate resin or the like tends to decrease, and when it exceeds 1.0 parts by weight, the stain resistance tends to decrease. is there.

  As the ultraviolet absorber (C), hydroxyphenyl triazine ultraviolet absorber, benzophenone ultraviolet absorber, benzotriazole ultraviolet absorber, cerium oxide ultraviolet absorber, cyanoacrylate ultraviolet absorber, zinc oxide ultraviolet absorber And oxalic anilide-based UV absorbers, titanium oxide-based UV absorbers, and the like. Among these, a hydroxyphenyltriazine-based ultraviolet absorber is preferable because of excellent heat resistance and ultraviolet absorption stability.

  Specific examples of hydroxyphenyl triazine-based ultraviolet absorbers include 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxyphenyl and Reaction product of oxirane [(C10-C16 mainly C12-C13 alkyloxy) methyl] oxirane, 2- (2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1, Reaction product of 3,5-triazine and (2-ethylhexyl) -glycidic acid ester, 2,4-bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1 , 3,5-triazine and the like.

  The addition amount of the ultraviolet absorber (C) is preferably 1 to 15 parts by weight, more preferably 5 to 12 parts by weight per 100 parts by weight of the resin solid content of the resin composition (A). . If the amount is less than 3 parts by weight, the weather resistance tends to decrease, and if it exceeds 15 parts by weight, the haze and the contamination resistance tend to decrease.

  As the organosilicate compound (D), the general formula (1):

（式中、Ｒ¹〜Ｒ⁴は、それぞれ同じかまたは異なり、炭素数１〜４のアルキル基である。ｎは、１０より大きく３０以下の整数である。）
で示される化合物などをあげることができる。

(In the formula, R ^{1 to} R ⁴ are the same or different and are each an alkyl group having 1 to 4 carbon atoms. N is an integer greater than 10 and 30 or less.)
And the like.

  Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an n-butyl group, and a t-butyl group.

  Among the compounds represented by the general formula (1), the methyl group is the highest in reactivity. However, from the viewpoint of low stability, it is preferable to partially substitute a methyl group with a butyl group or an ethyl group in order to balance solubility in a solvent and compatibility with a resin.

  By adding the organosilicate compound (D), the surface of the coating film can be highly hydrophilic from the early stage after painting, and as a result, it is possible to suppress contamination due to exhaust gas, dust, etc. of automobiles. Even when exposed to the outdoor period, high transparency can be maintained.

  The addition amount of the organosilicate compound (D) is preferably 1 to 30 parts by weight and more preferably 3 to 20 parts by weight per 100 parts by weight of the resin solid content of the resin composition (A). If the amount is less than 1 part by weight, the stain resistance tends to decrease. If the amount exceeds 30 parts by weight, the coating film becomes hard and cracks occur, or the compatibility with the resin composition (A) decreases and the coating film becomes cloudy. Tend to.

  In addition, a catalyst may be added for the purpose of promoting hydrolysis of the organosilicate compound (D). As the catalyst, a metal compound catalyst such as a metal chelate, a metal ester, or a metal alkoxide is used, and examples of the metal include aluminum, titanium, silicon, tin, and zinc. Specific examples include aluminum monoacetylacetonate bis (ethylacetoacetate) and aluminum tris (acetylacetonate).

  The addition amount of the catalyst is not particularly limited, but is preferably 0.1 to 20 parts by weight, more preferably 1 to 15 parts by weight per 100 parts by weight of the organosilicate compound (E). .

  In the present invention, other materials usually used for coating compositions can be blended. Examples of other materials include plasticizers, color pigments, reflectors, surfactants, antifoaming agents, inorganic fillers, and curing catalysts.

  The method for producing the coating composition of the present invention is not particularly limited, and a usual method for producing a coating composition can be employed. For example, a solution obtained by mixing and stirring a hydroxyl group-containing fluororesin, a solvent, a fluorine-based surfactant, an ultraviolet absorber, and the like, and an isocyanate-based curing agent, a solvent, an organosilicate compound, a catalyst, and the like are mixed and stirred uniformly Each solution is prepared individually. A method of preparing these solutions and a viscosity adjusting solvent before coating can be used.

  The present invention also relates to a clear coating composition and a coated article comprising the same.

  The substrate to which the coating composition of the present invention is applied is not particularly limited. Specifically, a resin molded product made of a synthetic resin such as an acrylic resin, a polycarbonate resin, a polyurethane resin, or a polyester resin, a coated molded steel plate, stainless steel, aluminum, brass, or a chrome-plated steel material can be given.

  Moreover, the coating composition of the present invention preferably has a contact angle with water of 60 ° or less in a 200-hour sunshine carbon arc lamp type weather resistance tester on the surface of the finally formed coating film, 30 ° More preferably, If it exceeds 60 °, the contamination resistance tends to decrease.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, it is not limited to these Examples. Unless otherwise specified, “part” means part by weight, and “%” means% by weight.

<Appearance>
It observed visually and evaluated by the following references | standards.
A: Whitening is not recognized and good.
○: Some whitening is observed, but good.
Δ: Whitening is observed.
X: Significant whitening is observed.

<Total light transmittance>
The total light transmittance (%) was measured according to JIS K7105.

<Haze>
Haze was measured according to JIS K7105.

<Adhesion>
After the coated product was immersed in boiling water for 1 hour, it was evaluated by a cross-cut tape test according to JIS K5600 (gap 1 mm, square 100). Shows the number of bags that did not peel.

<Accelerated weather resistance test 1>
With a metalling weather meter (manufactured by Suga Test Instruments Co., Ltd.), the appearance after 100 hours, 300 hours, and 500 hours was visually observed, and the yellowness was measured.

<Accelerated weather resistance test 2>
With a sunshine carbon arc lamp type weather resistance tester (Suga Test Co., Ltd.), the appearance after 200 hours, 1000 hours, 3000 hours and 5000 hours was observed and the water contact angle was measured.

<Outdoor exposure test>
The coated plate was placed vertically and exposed outdoors for 12 months, and then the degree of soiling was visually observed, and the brightness difference (ΔL ^* ) and total light transmittance were measured.

<Yellowness>
The yellowness was measured according to JIS K7105.

<Water contact angle>
Using a contact angle meter CAX-150 (manufactured by Kyowa Interface Science Co., Ltd.), measurement was performed 30 seconds after the formation of the droplet. The lower the water contact angle, the more hydrophilic the coating film surface is.

<Degree of dirt>
It observed visually and evaluated by the following references | standards.
A: Good with almost no dirt.
○: Good with little contamination.
Δ: Dirt is observed.
X: Dirt is remarkable.

<Lightness difference (ΔL ^* )>
Lightness difference by measuring the brightness after exposure and before exposure (L ^*) in color difference meter CR-200 (manufactured by Minolta Co.) - was determined ([Delta] L ^* = after exposure L ^* L ^* before exposure) . In the measurement, the measurement was performed with the white plate addressed to one side of the test piece. It shows that it is dirty, so that the value of a brightness difference ((DELTA) L ^* ) is low.

<Fluorine resin>
Fluoroolefin-vinyl ether copolymer (chlorotrifluoroethylene / cyclohexyl vinyl ether / ethyl vinyl ether / hydroxybutyl vinyl ether = 50/15/25/10), number average molecular weight 13,000, resin solid content 100% by weight, hydroxyl value 47 mgKOH / G

<Isocyanate curing agent>
Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd., resin solid content 100% by weight, NCO content 21.3% by weight)

<Fluorosurfactant>
EFKA-3034 (manufactured by EFKA)

<Silicone surfactant>
BYK-310 (manufactured by BYK, polyester-modified polydimethylsiloxane)

<Ultraviolet absorber (benzophenone series)>
Biosorb 130 (manufactured by Kyodo Yakuhin Co., Ltd., 2-hydroxy-4-n-octoxybenzophenone)

<Ultraviolet absorber (triazine type)>
Tinuvin 400 (manufactured by Ciba Specialty Chemicals, 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxyphenyl and oxirane [ (C10-C16 mainly C12-C13 alkyloxy) methyl] reaction product with oxirane)

<Organosilicate compound>
MKC silicate MS58B30 (Mitsubishi Chemical Co., Ltd., methyl silicate condensate in which the methyl group is partially substituted with a butyl group, average degree of condensation≈15)

<Catalyst>
Aluminum monoacetylacetonate bis (ethyl acetoacetate) (manufactured by Kawaken Fine Chemical Co., Ltd., product number: aluminum chelate D)

Examples 1-3, Comparative Examples 1-6
Coating compositions A to I were obtained with the formulations shown in Table 1. In Examples 1 to 3 and Comparative Examples 1 to 6, the mixing ratio of the hydroxyl group-containing fluororesin and the isocyanate curing agent is such that the isocyanate group of the isocyanate curing agent is 1. 1 mole.

Examples 4-9, Comparative Examples 7-12
A transparent polycarbonate plate (Mitsubishi Gas Chemical Co., Ltd., 5 mm thick) and a transparent acrylic resin plate (Sumitomo Chemical Co., Ltd., 5 mm thick) are coated on both sides. A polyurethane molded product produced by applying a polyurethane resin paint to a polyurethane resin molded product was coated with the obtained coating compositions A to I on the coated surface by air spray so that the film thickness after drying was 20 μm. After leaving it at room temperature for 15 minutes, it was baked and dried at 80 ° C. for 1 hour to prepare a substrate. The coating performance test results are shown in Tables 2 and 3.

Comparative Examples 13 and 14
Comparative Example 13 is a polycarbonate plate not coated with a coating composition (Mitsubishi Gas Chemical Co., Ltd., thickness 5 mm), and Comparative Example 14 is an acrylic plate not coated with a coating composition (Sumitomo Chemical Co., Ltd.). Manufactured, thickness 5 mm).

  The clear coating composition of the present invention can be baked in one coat, can be applied without impairing high transparency, and can maintain adhesion and high transparency even when exposed to the outdoors for a long time. Can be suitably used for sound insulation walls, resin windows for automobiles, resin lighting windows for buildings, and roofing materials such as carports and arcades.

Claims (6)

(A) To a coating composition containing a resin composition containing a hydroxyl group-containing fluororesin and an isocyanate curing agent, per 100 parts by weight of resin solids,
(B) 0.01 to 1.0 part by weight of a fluorosurfactant,
(C) 1 to 15 parts by weight of an ultraviolet absorber,
(D) A clear coating composition containing 1 to 30 parts by weight of an organosilicate compound ,
(E) a solvent containing 5 to 20% by weight of cyclohexanone and 10 to 50% by weight of diisobutyl ketone
A clear coating composition comprising: Hydroxyl group-containing fluororesin, a fluoroolefin unit 20 to 80 wt%, fluoroolefin containing vinyl ether unit 80-20 wt% - vinyl ether copolymer in which claim 1 clear coating composition. Fluorine-based surfactant (B) is a perfluoroalkyl-containing oligomer, claim is at least one surfactant selected from the group consisting of a polysiloxane having a perfluoroalkyl-containing polymer and a fluoroalkyl group 1 or 3. The clear coating composition according to 2. The clear coating composition according to any one of claims 1 to 3 , wherein the ultraviolet absorber (C) is a hydroxylphenyltriazine-based ultraviolet absorber. The organosilicate compound (D) has the general formula (1):

(In the formula, R ^{1 to} R ⁴ are the same or different and are each an alkyl group having 1 to 4 carbon atoms. N is an integer greater than 10 and 30 or less.)
The clear coating composition according to any one of claims 1 to 4 , which is a compound represented by the formula: A coated article having a coating film comprising the clear coating composition according to any one of claims 1 to 5 on a substrate.