JP2008208205A - Coating composition, coated article and automobile exterior plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition capable of forming a cured film excellent in abrasion resistance and also excellent in scratch resistance, and useful for a coated article such as an automobile exterior plate, etc. <P>SOLUTION: This coating composition contains (A) a compound obtained by reacting (a1) a compound having 3 isocyanate groups in one molecule with (a2) a compound having one hydroxy group and ≥1 (meth)acryloyl group by a ratio of (the total number of hydroxy groups)/(the total number of isocyanate groups)<1, (B) an acrylic copolymer having -50 to 0°C glass transition point and 50 to 350 mgKOH/g hydroxy value and (C) a radical polymerization initiator, and the coated article having such the cured film and the automobile exterior body panel consisting of such the coated article are also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention is a paint capable of forming a cured film particularly excellent in scratch resistance by heat and / or active energy rays, which is useful as a paint for clear coat layers of automobiles and the like that require a high degree of cosmetics and film performance. The present invention relates to a composition, a coated article having the cured film, and an automobile outer plate comprising the coated article.

  Conventionally, a thermosetting organic solvent-type paint typified by acrylic melamine curing system has been applied to the outermost layer of a car body outer panel such as an automobile in order to maintain the solvent resistance and weather resistance of the coating film. Has been. However, such a conventional thermosetting paint cured film has poor scratch resistance. Accordingly, scratches due to contact with clothing or the like, and scratches due to contact with the metal part of the bag or the key, etc., are easily generated.

  As a solution to such a problem, a technique using photocuring by active energy ray irradiation instead of thermal curing has been proposed (for example, see Patent Documents 1 to 3). When this method is used, a film having a higher crosslink density can be obtained, so that the scratch resistance is remarkably improved. However, with the recent demand for higher functionality of automobile coatings, improvement in scratch resistance against indentation stress is desired. In addition, it is desired to improve the curing of shadows where the active energy rays do not reach.

  Therefore, a method of using both heat curing by heating and photocuring has been proposed (see, for example, Patent Documents 4 to 7). In this technique, a photocurable component is added to a conventional thermosetting paint to increase the crosslink density on the surface of the film and improve its scratch resistance. However, although this method can improve the scratch resistance, it is insufficient to prevent the occurrence of scratches due to indentation stress such as scratches.

In order to solve such a problem, a coating composition containing a compound having a carboxyl group, an acrylic polymer having an epoxy group, and a radical polymerization initiator has been proposed (for example, see Patent Document 8). This coating composition is cured by using both thermosetting and photocuring. And since the compound which has both a thermal functional group and a photofunctional group is used as a crosslinking agent, a fine network structure is formed, without making a crosslinking density extremely high. Therefore, it is possible to obtain a cured film that improves scratch resistance and is less susceptible to scratches such as scratches due to indentation stress. However, since the thermosetting reaction is a reaction between a carboxyl group and an epoxy group, improvement in low-temperature curability is desired.
JP 2001-11140 A JP 2002-285046 A JP 2002-256175 A JP-A-63-113085 Japanese Patent Laid-Open No. 7-126554 JP-A-9-143399 JP 2003-119410 A JP 2005-97515 A

  An object of the present invention is to provide a coating composition capable of forming a cured film excellent in scratch resistance and scratch resistance (performance to prevent generation of scratches due to indentation stress), a coated article having the cured film, and An object of the present invention is to provide an automobile outer plate made of a coated article.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors applied a composition containing specific components on a substrate and cured it by a specific method, whereby scratch resistance and scratch resistance were obtained. The present inventors have found that a cured film having excellent properties can be formed, and have reached the present invention.

  That is, the present invention comprises a compound (a1) having three isocyanate groups in one molecule and a compound (a2) having one hydroxyl group and one or more (meth) acryloyl groups in one molecule. Compound (A) obtained by reacting at a ratio of the total number of hydroxyl groups of compound (a2) / total number of isocyanate groups of compound (a1) <1, glass transition temperature of −50 to 0 ° C., hydroxyl value of 50 to 350 mgKOH / g It is a coating composition containing an acrylic copolymer (B) and a radical polymerization initiator (C).

  Moreover, this invention is a coated article which has the cured film of the said coating composition. In particular, a coated article in which a base coat layer and one or more clear coat layers are sequentially laminated on a substrate, and the outermost layer of the clear coat layer is a cured film of the coating composition is preferable.

  Moreover, this invention is the outer plate | board for motor vehicles consisting of the said coated article.

  In the present invention, “(meth) acryloyl” is a generic term for acryloyl and methacryloyl, “(meth) acrylate” is a generic term for acrylate and methacrylate, and “(meth) acrylic acid” is a generic term for acrylic acid and methacrylic acid. It is.

  Since the coating composition of the present invention is cured by heat and / or active energy rays, a cured film can be formed in a short time and with energy saving. Moreover, the discharge amount of carbon dioxide can be suppressed during the formation of the cured film. Further, a cured film having excellent scratch resistance and scratch resistance can be formed. The cured film having such excellent performance is extremely useful as a film of a coated article such as an automobile outer plate.

<Compound (A)>
The compound (A) (hereinafter referred to as “component A”) used in the present invention is composed of a compound (a1) having three isocyanate groups in one molecule (hereinafter referred to as “component a1”) and one compound in one molecule. Reaction of a hydroxyl group and a compound (a2) having one or more (meth) acryloyl groups (hereinafter referred to as “component a2”) at a ratio of (total number of hydroxyl groups in component (a2) / total number of isocyanate groups in component (a1) <1 It is the compound obtained by making it. As a result of reaction of this a1 component and a2 component, A component turns into a compound which has an isocyanate group and a (meth) acryloyl group. The isocyanate group is a thermosetting functional group, and the (meth) acryloyl group is a photocurable functional group. This component A functions as a curing agent when the coating composition forms a film, and simultaneously imparts scratch resistance and restorability to the cured film.

  A component can be manufactured by a well-known method. Specifically, for example, at a temperature of 30 to 80 ° C., in the presence of a tin-based catalyst such as dibutyltin dilaurate and a polymerization inhibitor, the a2 component is dropped into the a1 component, or the a1 component is dropped into the a2 component. The component A is obtained by reacting for several hours. Moreover, you may use a dilution solvent as needed. When using a diluting solvent, it is preferable to use a solvent inert to the isocyanate group.

  The solvent inert to the isocyanate group is not particularly limited. Specific examples include Swazol 1000 (trade name, manufactured by Maruzen Petrochemical Co., Ltd.), Supersol 100 (trade name, manufactured by Nippon Petrochemical Co., Ltd.), Supersol 150 (trade name, manufactured by Nippon Petrochemical Co., Ltd.), benzene Aromatic solvents such as toluene and xylene; cyclic hydrocarbon solvents such as cyclohexane; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone and cyclohexanone; ethyl acetate, n-butyl acetate, isobutyl acetate, n -Acetate solvents such as amyl acetate and propylene glycol acetate;

<A1 component>
The a1 component is a compound having three isocyanate groups in one molecule. In particular, a trimer of a compound having two isocyanate groups in one molecule is preferable.

  Specific examples of the a1 component include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-diphenylmethane diisocyanate, and 4,4-diphenylmethane. Trimers of aromatic polyisocyanates such as diisocyanate; trimers of aliphatic polyisocyanates such as ethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate; isophorone diisocyanate, dicyclohexylmethane-4,4-diisocyanate, Trimers of alicyclic polyisocyanates such as methylcyclohexylene diisocyanate; araliphatic polyisoses such as xylene diisocyanate and tetramethylxylylene diisocyanate And trimers of cyanates; lysine triisocyanate; These can be used alone or in combination of two or more. Among them, hexamethylene diisocyanate trimer is particularly preferable from the viewpoint of coating properties of the resulting coating composition.

<A2 component>
The component a2 is a compound having one hydroxyl group and one or more (meth) acryloyl groups in one molecule.

  Specific examples of the a2 component include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meta ) (Meth) acrylic acid esters having a hydroxyalkyl group such as acrylate and 6-hydroxyhexyl (meth) acrylate; ring-opening adducts of ε-caprolactone or γ-butyrolactone to 2-hydroxyethyl (meth) acrylate [for example , Daicel Chemical Co., Ltd. Plaxel F (trade name), UCC Tone M (trade name), etc.], ring-opening adduct of ethylene oxide to (meth) acrylic acid, propylene oxide to (meth) acrylic acid Ring-opening adducts such as ring-opening adducts; cyclohexane dimeta Rumono (meth) acrylate; and the like. These can be used alone or in combination of two or more. Among these, 4-hydroxybutyl (meth) acrylate is particularly preferable from the viewpoint of achieving both scratch resistance and scratch resistance.

  The a1 component and the a2 component are reacted at a ratio of the total number of hydroxyl groups of the a2 component / the total number of isocyanate groups of the a1 component <1, thereby obtaining the A component. The total number of hydroxyl groups referred to here is the total number of hydroxyl groups contained in the total amount of the a2 component used for the reaction, and the total number of isocyanate groups referred to here is the total number of isocyanate groups contained in the total amount of the a1 component used for the reaction. Moreover, when a1 component or a2 component uses 2 or more types together, it is the total number of isocyanate groups or the total number of hydroxyl groups contained in each mixture whole quantity. If the reaction is carried out at a ratio of the total number of hydroxyl groups / the total number of isocyanate groups <1, the A component has reactivity with the B component, and as a result, a cured film rich in resilience can be obtained. A preferable range of the total number of hydroxyl groups / the total number of isocyanate groups is 0.2 to 0.7.

<Acrylic copolymer (B)>
The acrylic copolymer (B) (hereinafter referred to as “component B”) used in the present invention is an acrylic copolymer having a glass transition temperature of −50 to 0 ° C. and a hydroxyl value of 50 to 350 mgKOH / g. This B component imparts smoothness and scratch resistance to the cured film. The component B can be obtained, for example, by copolymerizing a monomer having one hydroxyl group in one molecule with another monomer.

  Examples of the monomer having one hydroxyl group in one molecule used for obtaining the B component include the same as the specific examples of the a2 component described above.

  Examples of other monomers used to obtain the component B include (meth) acrylic acid ester having an aliphatic hydrocarbon substituent, (meth) acrylic acid ester having an alicyclic hydrocarbon substituent, and a heterocyclic ring. (Meth) acrylic acid ester having a formula substituent, styrene derivative, ethylenically unsaturated nitrile, N-alkoxy substituted amide, vinyl basic monomer, unsaturated aliphatic dibasic acid dialkyl ester, one per molecule Hydroxyl group-containing vinyl monomers other than compounds having a hydroxyl group and one (meth) acryloyl group, carboxyl group-containing α, β-unsaturated vinyl monomers, long-chain carboxyl group-containing vinyl monomers, And vinyl monomers having a dicarboxylic acid monoester group. Specific examples of these monomers are listed below.

  Specific examples of the (meth) acrylic acid ester having an aliphatic hydrocarbon substituent include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, i- Butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, n-pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, Dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, isode Le (meth) acrylate, 2-hexyl decanyl (meth) acrylate. Thus, the aliphatic hydrocarbon substituent in the (meth) acrylic acid ester having an aliphatic hydrocarbon substituent may be linear or branched.

  Specific examples of the (meth) acrylic acid ester having an alicyclic hydrocarbon substituent include cyclohexyl (meth) acrylate, norbornyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclo Examples thereof include pentenyl (meth) acrylate, adamantyl (meth) acrylate, and methyladamantyl (meth) acrylate.

  Specific examples of the (meth) acrylic acid ester having a heterocyclic substituent include tetrahydrofurfuryl (meth) acrylate, cyclic trimethylolpropane formal (meth) acrylate, and 4- (meth) acryloyloxymethyl-2- Methyl-2-ethyl-1,3-dioxolane, 4- (meth) acryloyloxymethyl-2-methyl-2-cyclohexyl-1,3-dioxolane, 4- (meth) acryloyloxymethyl-2-methyl-2- Examples include isobutyl-1,3-dioxolane.

  Specific examples of the styrene derivative include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, p. -T-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-dodecyl styrene, p-phenyl styrene and the like.

  Specific examples of the ethylenically unsaturated nitrile include acrylonitrile and methacrylonitrile.

  Specific examples of the N-alkoxy substituted amide include N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, N-butoxymethyl acrylamide and the like.

  Specific examples of the vinyl basic monomer include dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate.

  Specific examples of the unsaturated aliphatic dibasic acid dialkyl ester include dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate and the like.

  Specific examples of the hydroxyl group-containing vinyl monomer other than the compound having one hydroxyl group and one (meth) acryloyl group in one molecule include 4-hydroxybutyl vinyl ether, p-hydroxystyrene and the like.

  Specific examples of the carboxyl group-containing α, β-unsaturated vinyl monomer include methacrylic acid, acrylic acid, crotonic acid, vinyl benzoic acid, fumaric acid, itaconic acid, maleic acid and the like.

  Specific examples of the long chain carboxyl group-containing vinyl monomer include β- (meth) acryloyloxyethyl acid succinate, β- (meth) acryloyloxyethyl acid maleate, β- (meth) acryloyloxyethyl acid phthalate. , Β- (meth) acryloyloxyethyl hexahydrophthalate, γ- (meth) acryloyloxypropyl-acid succinate, ε-caprolactone or γ-butyrolactone ring-opening adduct to 2-hydroxyethyl (meth) acrylate [eg The terminal hydroxyl group of Plaxel F (trade name) manufactured by Daicel Chemical Industries, Ltd. and tone M (trade name) manufactured by UCC, etc.] is esterified with succinic anhydride, phthalic anhydride or hexahydrophthalic anhydride, and carboxylated at the end. Succinic acid monoesters with introduced groups Caprolactone-modified hydroxyl group-containing, such as phthalic acid monoester or hexahydrophthalic anhydride monoester (meth) half-ester reaction product of an acrylic acid ester and an acid anhydride compound, and the like.

  Specific examples of vinyl monomers having a dicarboxylic acid monoester group include α, β-dicarboxylic acid anhydride groups such as maleic anhydride, itaconic anhydride, citraconic anhydride, and 2,3-dimethylmaleic anhydride. Examples thereof include vinyl monomers having monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monooctyl itaconate, monobutyl fumarate, mono-2-ethylhexyl fumarate, monoethyl citraconic acid and the like.

  These can be used alone or in combination of two or more.

  The polymerization method for producing the component B is not particularly limited. For example, known methods such as a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method can be used.

  When the component B is produced by the solution polymerization method, generally, the polymerization temperature is preferably 70 to 200 ° C, more preferably 80 to 180 ° C, and particularly preferably 90 to 170 ° C in order to control the molecular weight. Within.

  As a polymerization initiator used in that case, thermal polymerization initiators, such as an azo compound and an organic peroxide, are mentioned, for example. Specific examples of the azo compound include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (isobutyric acid) dimethyl, , 4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis {2-methyl-N- [2- (1-hydroxybutyl) )]-Propionamide} and the like. Specific examples of the organic peroxide include benzoyl peroxide and lauroyl peroxide.

  Moreover, you may add chain transfer agents, such as 2-mercaptoethanol, n-octyl mercaptan, n-dodecyl mercaptan, (alpha) -methylstyrene dimer, as needed.

  The hydroxyl value of B component is 50-350 mgKOH / g. By using such a component B, good smoothness and scratch resistance are imparted to the cured film. The hydroxyl value in this specification is obtained by calculating the molar concentration (mol / g) of the hydroxyl group contained in the resin component of the B component and multiplying it by the molecular weight of KOH 56.1.

  The glass transition temperature of B component is -50-0 degreeC. By using such a component B, good scratch resistance is imparted to the cured film. This glass transition temperature is a value determined by the Fox equation. The formula of Fox is the following relational expression regarding the glass transition temperature Tg (° C.) of the copolymer.

1 / (273 + Tg) = Σ (Wi / (273 + Tgi))
[Wherein Wi represents the mass fraction of monomer i, and Tgi represents the glass transition temperature (° C.) of the homopolymer of monomer i. ]
As the glass transition temperature of the homopolymer of monomer i, values from various known documents as shown in Table 1 below are used. For some raw materials, the mass fraction of the mixture and the glass transition temperature of the copolymer of the mixture were used.

  As for the weight average molecular weight of B component, 1,000-30,000 are preferable. When the weight average molecular weight is 1000 or more, it is preferable from the viewpoint of film forming property at the time of coating, and when it is 30,000 or less, it is preferable from the viewpoint of curability by active energy rays. This weight average molecular weight is prepared by injecting 100 μl of the above solution into a TOSO gel permeation chromatography apparatus equipped with a TOSO column (GE4000HXL and G2000HXL) after adjusting a B component tetrahydrofuran solution (0.4 mass%). The flow rate is 1 ml / min, the eluent is tetrahydrofuran, the column temperature is 40 ° C., measured using the gel permeation chromatography method, and converted into standard polystyrene.

  In the coating composition of the present invention, the mixing ratio of the A component and the B component is such that the ratio of the total amount of unreacted isocyanate groups contained in the A component and the total amount of hydroxyl groups contained in the B component is NCO / OH = 0.5. It is preferably within the range of ˜2, and particularly preferably equivalent (1). NCO / OH = 0.5 or more is preferable from the viewpoint of scratch resistance, and 2 or less is preferable from the viewpoint of scratch resistance.

<Radical polymerization initiator (C)>
The radical polymerization initiator (C) (hereinafter referred to as “C component”) used in the present invention is a radical polymerization initiator. This C component is used to accelerate the polymerization and curing of the coating composition.

  As the component C, for example, a polymerization initiator that generates radicals by active energy rays and / or a polymerization initiator that generates radicals by heat may be appropriately selected and used.

  Examples of the polymerization initiator that generates radicals by heat include thermal polymerization initiators such as azo compounds and organic peroxides. Specific examples of the azo compound include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (isobutyric acid) dimethyl, , 4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis {2-methyl-N- [2- (1-hydroxybutyl) )]-Propionamide} and the like. Specific examples of the organic peroxide include benzoyl peroxide and lauroyl peroxide.

  Specific examples of the polymerization initiator that generates radicals by active energy rays include benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophene, methylorthobenzoylbenzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2-ethylanthraquinone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl-phenylketone, benzoin methyl ether, benzoin ethyl ether , Benzoin isopropyl ether, benzoin isobutyl ether, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino 1- (4-morpholinophenyl) -butanone-1, diethylthioxanthone, isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine Oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, methylbenzoylformate, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl}- 2-methylpropan-1-one, 2-benzyl-2-dimethylamino-4-morpholinobutyrophenone, 2- (dimethylamino) -2- (4-methylbenzyl) -1- (4-morpholinophenyl) -butane- 1-one etc. are mentioned.

  Among them, a polymerization initiator that generates radicals by active energy rays is preferable because of its high reaction rate. In particular, since it has excellent curability of the coating composition and surface hardness of the cured film, 1-hydroxycyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) It is preferable to use one or more polymerization initiators selected from the group consisting of -phenylphosphine oxide and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one.

  Furthermore, if necessary, known photosensitizers such as methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, amyl 4-dimethylaminobenzoate and 4-dimethylaminoacetophenone may be used in combination.

  In the coating composition of the present invention, the content of the C component is not particularly limited, but is preferably 0.01 to 30 parts by mass, and 0.1 to 15 parts by mass with respect to 100 parts by mass of the total amount of the A and B components. Part is more preferred. When the content of the component C is in each of these ranges, the curability of the coating composition is good, and the cured film tends to exhibit excellent scratch resistance and scratch resistance.

<Active energy ray-curable compound>
The coating composition of the present invention can contain an active energy ray-curable compound as necessary.

  Examples of the active energy ray-curable compound include di (meth) acrylate, polyfunctional (meth) acrylate, urethane poly (meth) acrylate other than component A, polyester poly (meth) acrylate, and the like. Specific examples of these compounds are listed below.

  Specific examples of di (meth) acrylate include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol Di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (repeating unit n = 2 to 15) di (meth) acrylate, polypropylene glycol (repeating unit n = 2 to 15) di (meth) acrylate, polybutylene Glycol (repeat unit n = 2 to 15) di (meth) acrylate, 2,2-bis (4- (meth) acryloyloxyethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxydiethoxyphenyl) ) Propane, trimethylolpropane di (meth) a Relate, tricyclodecane dimethanol diacrylate, bis (2- (meth) acryloyloxyethyl) hydroxyethyl isocyanurate, bis (2- (meth) acryloyloxy propyl) -2-ethoxy-propyl isocyanurate.

  Specific examples of the polyfunctional (meth) acrylate include trimethylolpropane tri (meth) acrylate, tris (2- (meth) acryloyloxyethyl) isocyanurate, tris (2- (meth) acryloyloxypropyl) isocyanurate, penta Trifunctional or higher (meth) such as erythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. An acrylate is mentioned.

  Specific examples of the other compounds include epoxy poly (meth) acrylates such as epoxy di (meth) acrylate obtained by reacting bisphenol A diepoxy and (meth) acrylic acid; 1,6-hexamethylene diisocyanate trimer Urethane tri (meth) acrylate reacted with 2-hydroxyethyl (meth) acrylate, urethane di (meth) acrylate reacted with isophorone diisocyanate and 2-hydroxypropyl (meth) acrylate, isophorone diisocyanate and pentaerythritol tri (meth) Urethane hexa (meth) acrylate reacted with acrylate, dicyclomethane diisocyanate and urethane di (meth) acrylate reacted with 2-hydroxyethyl (meth) acrylate, dicyclomethane di Urethane poly (meth) acrylates such as urethane di (meth) acrylate obtained by reacting urethanization reaction product of isocyanate and poly (repeating unit n = 6 to 15) tetramethylene glycol with 2-hydroxyethyl (meth) acrylate; Polyester (meth) acrylate obtained by reacting methylolethane with succinic acid and (meth) acrylic acid, polyester such as polyester (meth) acrylate obtained by reacting trimethylolpropane with succinic acid, ethylene glycol and (meth) acrylic acid Poly (meth) acrylate; and the like.

  These can be used individually by 1 type or in combination of 2 or more types.

<Organic solvent>
The coating composition of the present invention is necessary, for example, for the purpose of obtaining uniform solubility of the coating composition, and for the purpose of improving viscosity, improving the workability of coating on a substrate, smoothness of a cured film, etc. Depending on the case, an organic solvent can be blended.

  The organic solvent is not particularly limited. Specific examples thereof include alcohol solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, cyclohexanol, diacetone alcohol; methyl cellosolve, cellosolve, butyl cellosolve, methylcarbitol , Ether solvents such as carbitol, butyl carbitol, diethyl carbitol, propylene glycol monomethyl ether; SWAZOL 1000 (trade name, manufactured by Maruzen Petrochemical Co., Ltd.), SUPERSOL 100 (trade name, manufactured by Nippon Oil & Petrochemical Co., Ltd.), Supersol 150 (trade name, manufactured by Nippon Petrochemical Co., Ltd.), aromatic solvents such as benzene, toluene and xylene; cyclic hydrocarbon solvents such as cyclohexane; acetone, methyl ethyl ketone, methyl Sobuchiruketon, diisobutyl ketone, ketone solvents such as cyclohexanone, ethyl acetate, n- butyl acetate, isobutyl acetate, n- amyl acetate, acetate-based solvent such as propylene glycol monomethyl ether acetate; and the like. These organic solvents can be used alone or in combination of two or more. Among these, in order to obtain uniform solubility of the coating composition, a ketone solvent or an acetate solvent and a mixed solvent containing them are preferable. In particular, n-butyl acetate or propylene glycol monomethyl ether acetate is preferable.

  The compounding quantity of the organic solvent in the coating composition of this invention is not specifically limited. For example, from the viewpoint of coating workability, the total amount of raw materials that are contained in the A component, the B component, and the C component is within the range of 30 to 100% by mass of the entire coating composition. preferable. In addition, as an indicator of the blending amount of the organic solvent, for example, when the coating composition is applied by air spray gun coating, airless spray coating or rotary atomization coating, it is usually at 20 ° C. using a Ford Cup No. 4 viscometer. It is preferable to blend an organic solvent so that the viscosity range is about 15 to 60 seconds.

<Others>
The coating composition of the present invention includes, for example, non-reactive thermoplastic polymers, organic bentons, polyamides, microgels, fiber-based resins, and other rheology modifiers, surface modifiers, ultraviolet absorbers, light stabilizers, Additives such as antioxidants, polymerization inhibitors, silane coupling agents, inorganic fillers, organic fillers, surface-organized inorganic fillers, anti-sagging agents, and the like can be appropriately blended using known means as necessary. it can. Especially, it is preferable to use a ultraviolet absorber, a light stabilizer, and antioxidant from the point which can improve the storage stability of a composition and can suppress discoloration and a quality change of a cured film.

<Coating material>
The coating object of the coating composition of this invention is not specifically limited. For example, it is very useful when the body of various vehicles such as automobiles and motorcycles is used as an object to be coated. Examples of the base material of these objects include cold-rolled steel sheets, galvanized steel sheets, zinc alloy-plated steel sheets, stainless steel sheets, tin-plated steel sheets, aluminum substrates, aluminum alloy plates and other metal substrates, and various plastic substrates. Can be mentioned.

  Further, the surface of the base material may be subjected to surface treatment such as phosphate treatment, chromate treatment, or complex oxide treatment. Furthermore, an undercoating film such as an electrodeposition coating and / or an intermediate coating film may be formed on the substrate. As an electrodeposition coating material, the coating material which mixed block polyisocyanate resin as a crosslinking agent to an epoxy resin is mentioned, for example. Examples of coatings for intermediate coatings include acrylic resins having a functional group such as hydroxyl group, carboxyl group, and epoxy group, polyester resins, and urethane resins, and melamine resins, urea resins, polyisocyanate resins, and block polymers as crosslinking agents. What mixed isocyanate resin, a carboxyl group-containing compound, etc. is mentioned. They may be solvent-based paints or water-based paints. In addition, a solvent-based paint in which a melamine resin or the like as a crosslinking agent is mixed with an acrylic resin, polyester resin, urethane resin or the like having a functional group such as a hydroxyl group, a carboxyl group, or an epoxy group is formed on the intermediate coating film as a top coating film. You can also

<Coating method>
The coating method of the coating composition of the present invention is not particularly limited. Specific examples thereof include air spray coating, airless spray coating, rotary atomization coating, and curtain coat coating. In these coating methods, electrostatic application may be performed as necessary. Among these, an air spray coating method and an electrostatic coating method are preferable. The coating amount of the coating composition is preferably such that the cured film has a thickness of about 5 to 80.

<Curing method>
Examples of the curing method of the coating composition coated on the article to be coated include a method of irradiating active energy rays after heating, a method of heating after irradiating active energy rays, and a method of simultaneously heating and irradiating active energy rays.

  Heating can be performed by a known method. For example, a drying furnace such as a hot air furnace, an electric furnace, or an infrared induction heating furnace can be used.

  The active energy ray irradiation can be performed by a known method. The active energy rays are not particularly limited, and α, β, γ rays, ultraviolet rays, and the like can be used. From the viewpoint of versatility, ultraviolet rays are preferable. As the ultraviolet ray generation source, an ultraviolet lamp is preferable from the viewpoint of practicality and economy. Specific examples of the ultraviolet lamp include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a metal halide lamp, and an electrodeless UV lamp using a magnetron.

  The coating composition of the present invention is cured even when the atmosphere during irradiation with active energy rays is air or an inert gas such as nitrogen or argon. In particular, it is preferable to cure in an air atmosphere from the viewpoint of practicality and economy.

<Film formation method>
The coated article of the present invention has a cured film of the coating composition of the present invention. In particular, a coated article (for example, an automobile), in which a base coat layer and one or more clear coat layers are sequentially laminated on a substrate, and the outermost layer of the clear coat layer is a cured film of the coating composition of the present invention. The outer plate) is preferable. Hereinafter, an example of a method for forming a film of such a coated article will be described.

  As a method for forming the film, for example, a base coat layer is formed with a thermosetting paint on a substrate, and then a clear coat layer is formed with the coating composition of the present invention, and a thermosetting paint is formed on the substrate. Examples include a method of forming a base coat layer, then forming a melamine type or acid-epoxy type thermosetting clear coat layer, and then forming a clear coat layer with the coating composition of the present invention.

  The base coat layer is a layer that is a base of the clear coat layer, and is a layer that is formed for the purpose of coloring the base material in a desired color. The base coat layer is, for example, a known curable resin; a diluent made of an organic solvent and / or water; a hardener made of an amino resin or a polyisocyanate compound; a brightening agent such as aluminum paste, mica, flake iron oxide; Necessary inorganic pigments and organic pigments such as titanium oxide, carbon black and quinacridone; other resins such as polyester resins, epoxy resins and cellulose resins; additives such as surface conditioners, ultraviolet absorbers and antioxidants; It consists of a cured coating film of a base coat paint prepared by appropriately selecting them and mixing them appropriately using known means.

  Examples of the form of the base coat paint include known ones such as an organic solvent type, a high solid type, a non-dispersion type, an aqueous solution type, and a water dispersion type. Among these, from the viewpoint of suppressing the amount of solvent discharged during the formation of the coating film, an aqueous paint such as an aqueous solution type or a water dispersion type is preferable, and an aqueous thermosetting paint is more preferable.

  The water-based thermosetting paint is a paint containing a thermosetting resin and water, and a color pigment may be appropriately added as necessary. Specific examples of thermosetting resins include, for example, acrylic resins / amino resins, alkyd resins / amino resins, polyester resins / amino resins, acrylic resins / polyisocyanates, alkyd resins / polyisocyanates, polyester resins / Examples include polyisocyanate-based, epoxy-based acrylic resin / carboxylic acid-based acrylic resin.

  The thermosetting resin may be appropriately selected and used so as to have desired characteristics. For example, from the viewpoint of curability, the hydroxyl value of the thermosetting resin is preferably 10 to 200, and more preferably 30 to 120. From the viewpoint of stability, the acid value of the thermosetting resin is preferably 5 to 150, and more preferably 15 to 100. Furthermore, from the viewpoint of paintability, the number average molecular weight of the thermosetting resin is preferably 2,000 to 1,000,000, and more preferably 3,000 to 50,000.

  Among them, thermosetting resins such as acrylic resins, vinyl resins, polyester resins, alkyd resins, and urethane resins having a crosslinkable functional group such as a hydroxyl group and a hydrophilic functional group such as a carboxyl group are particularly used as base coats for automobile outer plates. It can be suitably used as a resin component of a paint.

  As the color pigment, for example, known paint pigments such as solid color pigments, metallic pigments, and light interference pigments can be used. They can be used alone or in combination of two or more as required.

  Specific examples of solid color pigments include titanium oxide, zinc white, lithopone, antimony white, carbon black, acetylene black, lamp black, naphthol yellow S, Hansa Yellow, pigment yellow L, benzidine yellow, permanent yellow, chrome orange, chrome bar Million, permanent orange, iron oxide, amber, bengara, red lead, permanent red, quinacridone red pigment, cobalt purple, fast violet, methyl violet lake, ultramarine, bitumen, cobalt blue, phthalocyanine blue, indigo, chrome green, pigment green B, phthalocyanine green and the like.

  Specific examples of the metallic pigment include flakes or vapor-deposited pieces such as aluminum, aluminum oxide, bismuth oxychloride, nickel and copper, mica flakes, titanium oxide-coated mica flakes, iron oxide-coated mica flakes, and the like.

  These color pigments may be appropriately selected as desired, and can be used alone or in combination of two or more.

  If necessary, the base coat paint may contain a hydrophilic organic solvent and / or a hydrophobic organic solvent as long as the effects of the present invention are not impaired. The hydrophilic organic solvent here means an organic solvent in which an amount of 50 parts by mass or more dissolves with respect to 100 parts by mass of water at 20 ° C. The hydrophobic organic solvent means an organic solvent in which an amount of less than 50 parts by mass dissolves at 100 ° C. water at 20 ° C.

  The hydrophilic organic solvent can be used, for example, as a film forming aid. Specific examples thereof include ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, Diethylene glycol diethyl ether, diethylene glycol monobutyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, methyl alcohol, ethyl alcohol, allyl alcohol, n-propyl alcohol, isopropyl alcohol, tertiary butyl alcohol, ethylene glycol, 1,2- Examples include propylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, hexylene glycol, hexanediol, dipropylene glycol, acetone, diacetone alcohol, and propylene glycol monomethyl ether acetate. Especially, since it exists in the tendency for the smoothness of a cured coating film to become favorable, the organic solvent whose boiling point exists in the range of 180-200 degreeC is preferable. The hydrophilic organic solvent is preferably used as a mixed solution with water. In this case, the amount of the hydrophilic organic solvent is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less with respect to 100 parts by mass of the mixed solution.

  Furthermore, the base coat paint may contain a crosslinking agent such as a melamine resin or a block polyisocyanate compound.

  The blending ratio of the thermosetting resin and the crosslinking agent in the base coat paint is not particularly limited. In a total of 100 parts by mass of the thermosetting resin and the crosslinking agent, the content of the thermosetting resin is preferably 50 to 90 parts by mass, more preferably 60 to 80 parts by mass, and the content of the crosslinking agent is 50 to 10 parts by mass. Is preferable, and 40 to 20 parts by mass is more preferable. If the content is within these ranges, the curability and coating workability of the thermosetting paint tend to be good.

  A neutralizing agent may be added to the base coat paint as necessary. When the base coat paint is a water-based thermosetting paint, the neutralizing agent is added to neutralize the carboxyl groups and the like contained in the thermosetting resin as hydrophilic functional groups. Or water dispersion. Specific examples of the neutralizing agent include ammonia, methylamine, ethylamine, propylamine, isopropylamine, butylamine, 2-ethylhexylamine, cyclohexylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, trimethylamine, triethylamine. , Triisopropylamine, tributylamine, ethylenediamine, morpholine, N-alkylmorpholine, pyridine, monoisopropanolamine, methylethanolamine, methylisopropanolamine, dimethylethanolamine, diisopropanolamine, diethanolamine, triethanolamine, diethylethanolamine, tri Examples include ethanolamine. These can be used individually by 1 type or in combination of 2 or more types. The addition amount of the neutralizing agent is usually preferably 0.1 to 2 equivalents and more preferably 0.3 to 1.2 equivalents with respect to hydrophilic functional groups such as carboxyl groups contained in the thermosetting resin. . If the addition amount is within these ranges, the carboxyl groups and the like contained in the thermosetting resin tend to be sufficiently neutralized.

  Base coat paints include barita powder, precipitated barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, silica, white carbon, diatomaceous earth, talc, magnesium carbonate, alumina white, gloss white, mica powder, etc. Extender pigments and the like may also be blended.

  The base coat paint can be applied to the substrate by a known method such as an air spray method, an airless spray method, or an electrostatic coating method. The coating thickness may be appropriately selected according to the desired use of the coated article, and is not particularly limited. Specifically, for example, the thickness of the cured coating film of the base coat layer for automobiles is preferably 5 to 20 μm, more preferably 5 to 15 μm, and particularly preferably 5 to 13 μm.

  Below, an example of the method for obtaining the coated article of this invention is demonstrated.

  First, a base coat layer is appropriately formed on a substrate as necessary. The base coat layer is, for example, applied by spraying a base coat paint, and dried so that the solid content is 40% by mass or more, preferably 50 to 100% by mass, with the coating film being uncured. Further, it can be obtained by drying at 50 to 100 ° C. for about 1 to 30 minutes.

Next, a clear coat paint is applied on the base material or a base coat layer previously formed or pre-dried on the base material, and if necessary, it is heated and irradiated with active energy rays to form a clear coat layer. it can. For example, after applying a clear coat paint, solvent drying and heat curing are performed in a drying furnace at 100 to 140 ° C., and then UV light is irradiated with an integrated light amount of 500 to 10,000 mJ / cm ² using a light source such as a metal halide lamp. Can be cured.

  If necessary, a cured product layer of a melamine type or acid-epoxy type thermosetting clear coat paint may be formed as an intermediate coating clear coat layer between the base coat layer and the clear coat layer.

  The clear coat layer may be formed after the cured coating film of the base coat paint is formed, or after the base coat paint film is dried, the clear coat paint may be applied and these paint films may be cured simultaneously.

  For example, when a clear coat layer is formed on the base coat layer using the coating composition of the present invention to obtain a coated article such as an automobile outer plate, the clear coat layer can impart excellent smoothness and weather resistance. Therefore, a method of curing by irradiating with active energy rays after heat treatment for the purpose of drying and volatilizing the solvent or water in the clear coat film is preferable.

  The coated article of the present invention can be used particularly suitably for outdoor use, specifically for an automobile outer plate, because the cured coating film is excellent in acid rain resistance and scratch resistance.

  Hereinafter, the present invention will be described in more detail by way of examples. In the examples, “part” or “%” means “part by mass” or “mass%”.

  The evaluation method of the cured film is as follows.

  [Abrasion resistance]: The obtained coated coated plate is subjected to a car wash test 10 times using a car wash test machine (Amtec, Car-wash Lab Apparatus). [Test method: Quarzwerke product, silica fine particles, product The brush is rotated (127 rpm) while spraying a test solution in which the name Sikron SH200 (particle size: 24 μm) is mixed at a rate of 1.5 g with respect to 1 liter of water, and 10 reciprocating brushes are applied. After the test, washing and drying are performed, and the 20 ° gloss before and after the test is measured using a gloss meter (manufactured by Byk-Gardner, apparatus name: Micro Tri Gross), and the gloss retention is calculated from the following equation.

○: 80% or more.
X: Less than 80%.

  [Scratch resistance]: With respect to the obtained coated coated plate, a load was applied from 0 g using a scratch tester (manufactured by HEYDON, device name tribogear, scratching needle: sapphire, tip diameter 0.1 mmR, tip angle 60 °). Tested at a distance of 100 mm at a scratching speed of 300 mm / min while continuously shifting up to 200 g at an increasing rate of 2 g / 1 mm, and after the test, the distance χ [mm] between the points where scratches started from the end of the test Measure after 24 hours and calculate scratch resistance.

Scratch resistance [g] = (100 (test length [mm]) − χ [mm]) × 2
○: 100 g or more.
X: Less than 100 g.

<Synthesis of component A>
(Synthesis Example 1)
In a reaction vessel equipped with a flask, a stirrer, a temperature controller and a condenser, hexamethylene diisocyanate trimer (product name: Duranate TPA manufactured by Asahi Kasei Chemical Co., Ltd.) as a compound having three isocyanate groups in one molecule (a1 component) -100) 907 parts, and reaction catalyst dibutyltin dilaurate 0.58 part were charged, and the temperature was raised to 60 ° C. with stirring. Next, 5 parts of 260 parts of 4-hydroxybutyl acrylate (trade name 4-HBA, manufactured by Osaka Organic Chemical Co., Ltd.), which is a compound (a2 component) having one hydroxyl group and one or more (meth) acryloyl groups in one molecule. It was added dropwise over time. After completion of the dropwise addition, the mixture was further stirred for 3 hours to obtain Compound NA-1. Here, the total number of hydroxyl groups / total number of isocyanate groups in the raw material used for synthesizing NA-1 is 1/3 (= 0.33).

<Synthesis of B component>
(Polymerization example 1)
Into a reaction vessel equipped with a flask, a stirrer, a temperature controller and a condenser, 1400 parts of propylene glycol monomethyl ether acetate was charged, and the temperature was raised to 130 ° C. while stirring. 6 parts of acid, 300 parts of 2-hydroxyethyl acrylate, ε-caprolactone ring-opening adduct of 2-hydroxyethyl methacrylate (manufactured by Daicel Chemical Industries, Ltd., trade name: Plaxel FM4), and t-butylperoxy-2- A mixture of 80 parts of ethyl hexaate (Nippon Yushi Co., Ltd., trade name Perbutyl O) was added dropwise over 3 hours. After completion of the dropwise addition, a mixture of 20 parts of t-butyl peroxy-2-ethyl hexaate and 200 parts of propylene glycol monomethyl ether acetate was further added dropwise over 1 hour. After completion of the dropwise addition, stirring was continued for 1 hour, and 300 parts of propylene glycol monomethyl ether acetate was added while cooling to room temperature. Compound PD-1 having one or more hydroxyl groups (solid content 61% by mass, hydroxyl value 120 mgKOH / g, Glass transition temperature (Tg) -36 ° C., weight average molecular weight 13,000) was obtained.

(Polymerization Examples 2-9)
Polymerization example, except that the mixture to be dropped was 80 parts of t-butyl peroxy-2-ethylhexaate (manufactured by NOF Corporation, trade name Perbutyl O) and the composition and composition shown in the composition column of Table 3 In the same manner as in Example 1, a compound having one or more hydroxyl groups was obtained. Further, Table 2 also shows the solid content, hydroxyl value, glass transition temperature, and weight average molecular weight of the obtained compound.

[Example 1]
40.9 parts of NA-1 obtained in Synthesis Example 1 as component A, 96.9 parts (solid content 59.1 parts) of PD-1 obtained in Polymerization Example 1 as component B, 1-hydroxycyclohexyl-phenyl Ketone (Ciba Specialty Chemicals, trade name Irgacure 184) is blended with 2.95 parts as component C, dibutyltin dilaurate as 0.03 parts as thermosetting catalyst, Modaflow (trade name, manufactured by Cytec, trade name as MODAFLOW Resin) modifier) 0.3 part was added. Further, 62.2 parts of propylene glycol monomethyl ether acetate was added so that the solid content of the composition was 50%, and the mixture was stirred and mixed to obtain a coating composition.

Next, a 150 × 70 × 0.8 mm dull steel plate treated with zinc phosphate was coated with an epoxy resin cationic electrodeposition coating to a thickness of 20 μm and cured by heating at 170 ° C. for 30 minutes. Subsequently, an automotive solvent-based polyester melamine curable intermediate coating was applied by air spray to a thickness of 30 μm and cured by heating at 140 ° C. for 30 minutes. Further, a solvent-based melamine curable monocoat solid paint for automobiles was applied by air spraying to a thickness of 40 μm and heat cured at 140 ° C. for 30 minutes to provide a multilayer coating film layer. On top of that, the previously prepared coating composition was applied, allowed to stand at room temperature for 15 minutes, and heated for 30 minutes in a hot air dryer at 140 ° C. to evaporate the organic solvent and perform thermosetting. Subsequently, using an electrodeless UV lamp irradiation device (D bulb), an ultraviolet ray with an integrated light amount of 3300 mJ / cm ² (an ultraviolet integrated energy amount of a wavelength of 320 to 380 nm) was irradiated to obtain a coated coated plate having a cured film thickness of 20 μm. Using this coated coated plate, scratch resistance and scratch resistance were evaluated, and the results are shown in Table 3.

[Examples 2 to 5 and Comparative Examples 1 to 4]
A coating composition was prepared in the same manner as in Example 1 except that 0.03 part of dibutyltin dilaurate and 0.3 part of Modaflow were used and the other components were blended in the composition column shown in Table 3. Then, a coated coated plate was obtained and evaluated. The results are shown in Table 3.

The amount in parentheses in the usage amount of the B component in the table indicates the solid content.
The symbols and abbreviations in the table are as follows.
NA-1: Compound (NA-1) obtained in Synthesis Example 1
PD-1: Compound having one or more hydroxyl groups obtained in Polymerization Example 1 PD-2: Compound having one or more hydroxyl groups obtained in Polymerization Example 2 PD-1: 1 obtained in Polymerization Example 3 Compound PD-4 having one or more hydroxyl groups: Compound PD-5 having one or more hydroxyl groups obtained in Polymerization Example 4: Compound PD-6 having one or more hydroxyl groups obtained in Polymerization Example 5: Polymerization Compound PD-7 having one or more hydroxyl groups obtained in Example 6: Compound PD-8 having one or more hydroxyl groups obtained in Polymerization Example 7: One or more hydroxyl groups obtained in Polymerization Example 8 Compound PD-9: Compound PNCO having one or more hydroxyl groups obtained in Polymerization Example 9: Hexamethylene diisocyanate trimer (trade name Duranate TPA-100, manufactured by Asahi Kasei Chemical Co., Ltd.)
IT-1: 1-hydroxycyclohexyl-phenyl ketone (manufactured by Ciba Specialty Chemicals, trade name Irgacure 184)
DPHA: Dipentaerythritol hexaacrylate (Nippon Kayaku Co., Ltd., trade name Kayarad DPHA)
PMA: Propylene glycol monomethyl ether acetate

Claims (9)

The compound (a1) having three isocyanate groups in one molecule and the compound (a2) having one hydroxyl group and one or more (meth) acryloyl groups in one molecule are combined with the total amount of the compounds (a2). Compound (A) obtained by reacting at a ratio of hydroxyl number / total number of isocyanate groups of compound (a1) <1,
Acrylic copolymer (B) having a glass transition temperature of −50 to 0 ° C. and a hydroxyl value of 50 to 350 mgKOH / g, and a radical polymerization initiator (C)
A coating composition containing   The coating composition according to claim 1, wherein the radical polymerization initiator (C) is an initiator that generates radicals by active energy rays.   The coating composition according to claim 1, wherein the compound (a1) is a trimer of a compound having two isocyanate groups in one molecule.   The coating composition according to claim 3, wherein the compound (a1) is a trimer of hexamethylene diisocyanate.   A coated article having a cured film of the coating composition of claim 1.   A coated article comprising a base coat layer and one or more clear coat layers sequentially laminated on a substrate, wherein the outermost layer of the clear coat layer is a cured film of the coating composition according to claim 1.   The coated article according to claim 6, wherein the thickness of the outermost layer of the clear coat layer is in the range of 5 to 80 µm.   The coated article according to claim 6, wherein the base coat layer is a cured film of a water-based paint.   The outer plate | board for motor vehicles consisting of the coated article as described in any one of Claims 5-8.