WO2012160891A1

WO2012160891A1 - Coating composition and method for forming coating film

Info

Publication number: WO2012160891A1
Application number: PCT/JP2012/059780
Authority: WO
Inventors: 祐一稲田; 近藤　充; 正春石黒
Original assignee: 関西ペイント株式会社
Priority date: 2011-05-20
Filing date: 2012-04-10
Publication date: 2012-11-29
Also published as: JP5889291B2; JPWO2012160891A1

Abstract

The present invention provides a coating composition characterized by comprising: (A) a urethane acrylate having an unsaturated group equivalent of 100-900 and a weight average molecular weight of 500-2500; (B) a hydroxy-group-containing acrylic resin comprising, as copolymerization components, (a) a methyl methacrylate in an amount of 65-90 mass%, (b) a hydroxy-group-containing polymerizable unsaturated monomer in an amount of 10-35 mass% and (c) another polymerizable unsaturated monomer in an amount of 0-25 mass% all relative to the total amount of the copolymerization components; (C) a polyisocyanate compound; and (E) a photopolymerization initiator.

Description

Coating composition and coating film forming method

[Cross-reference of related applications]
This application claims priority based on Japanese Patent Application No. 2011-113309 filed on May 20, 2011, the entire disclosure of which is incorporated herein by reference.

The present invention relates to a coating composition and a coating film forming method.

In general, for example, in metallic coating, an electrodeposition coating, an intermediate coating, and a base coating are formed on the body and parts of vehicles such as motorcycles, automobiles, and containers, and then a clear coating is formed. Is done. The clear coating film is, for example, a thermosetting coating composition containing a thermosetting functional group-containing resin such as a hydroxyl group-containing acrylic resin and a crosslinking agent such as a melamine resin, a heat containing an acid group-containing resin and an epoxy group-containing resin. It is formed by a coating film forming method in which a curable coating composition or the like is applied and then heated and cured. According to this coating film forming method, a coating film excellent in coating film performance such as adhesion and coating film hardness can be formed.

In recent years, energy saving and productivity improvement are required in the painting process. From such needs, coating compositions that can be cured at low temperatures and coating compositions that can be cured in a short time are expected. However, the above-mentioned thermosetting coating composition usually requires a heating temperature of about 140 ° C. and a heating time of about 20 to 40 minutes in a general coating process, and satisfies the demands for energy saving and productivity improvement. Not what you want.

Patent Document 1 discloses an acrylic resin, a colorant, and an organic solvent obtained by copolymerizing a monomer mixture containing 30% by weight or more of n-butyl (meth) acrylate and methyl (meth) acrylate as essential components. A coating material containing the above is applied onto a thermoplastic resin substrate and dried on a colored layer, and a compound having three or more (meth) acryloyl groups and methyl (meth) acrylate as essential components There is disclosed a method for forming a laminated coating film in which an energy ray-curable top coating containing an acrylic resin obtained by copolymerizing a monomer mixture containing 20% by weight or more is applied and cured by irradiation with energy rays. According to the present invention, it is possible to obtain a coating film excellent in abrasion resistance, interlayer adhesion between the colored layer and the top coating material, and adhesion between the thermoplastic resin substrate. However, in the present invention, the two-coat method is not satisfied, and does not satisfy the demands for energy saving and productivity improvement, and does not satisfy the sufficient scratch resistance, weather resistance, and finished appearance.

Japanese Patent Laid-Open No. 2002-200456

The present invention has been made in view of the above circumstances, and the object of the present invention is to reduce the heating temperature and shorten the heating time in the coating process, as well as the adhesion to the material and the appearance of the coating film in one coat, Furthermore, it is providing the coating composition and coating-film formation method which can obtain the colored coating film which is excellent in abrasion resistance and a weather resistance.

As a result of intensive studies in order to solve the above-mentioned problems, the present inventors have found that a specific urethane acrylate compound, a hydroxyl group-containing acrylic resin having 65 to 90% by weight of methyl methacrylate as a copolymerization component, a polyisocyanate compound, and light It has been found that the problem can be solved by using a coating composition containing a polymerization initiator.

Furthermore, the present inventors have found that a coating film having excellent adhesion and finished appearance can be obtained with a single coating at a low temperature and in a short time, and the present invention has been completed. .

That is, the present invention provides the following items:
Item 1. Urethane acrylate (A) having an unsaturated group equivalent of 100 to 900 and a weight average molecular weight of 500 to 2500, 65 to 90% by mass of methyl methacrylate (a) based on the total amount of copolymerization components, a hydroxyl group-containing polymerizable unsaturated monomer ( b) Hydroxyl-containing acrylic resin (B), polyisocyanate compound (C) and photopolymerization initiator (E) containing 10 to 35% by mass and other polymerizable unsaturated monomer (c) as a copolymerization component of 0 to 25% by mass ) Containing coating composition.

Item 2. Item 8. The coating composition according to Item 1, comprising 10 to 70 parts by mass of the urethane acrylate (A) in 100 parts by mass of the total resin solid content in the coating composition.

Item 3. Item 3. The coating composition according to Item 1 or 2, further comprising a coloring component (D).

Item 4. Item 4. The coating composition according to any one of Items 1 to 3, wherein the light transmittance at 375 nm of the coating film formed with a dry film thickness of 30 μm is 3.0% or more.

Item 5. A coating composition according to any one of claims 1 to 4 is applied onto an object to be coated and subjected to setting and / or preheating, so that the solid content of the coating film obtained is 90% by mass or more. And then irradiating with active energy rays.

Item 6. Item 5. The method for forming a coating film according to Item 4, wherein heating is performed after the active energy ray irradiation.

Item 7. Item 7. The method for forming a coating film according to Item 5 or 6, wherein the object to be coated is acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene-acrylate resin, polycarbonate resin, polybutylene terephthalate resin, or a hybrid of at least two of these resins.

Item 8. Item 8. The method for forming a coating film according to any one of Items 5 to 7, wherein the maximum temperature reached to the surface of the object to be coated is less than 90 ° C. during irradiation with the active energy ray.

Item 9. 5. An article coated with the coating composition according to any one of items 1 to 4.

Item 10. An article coated by the method for forming a coating film according to any one of items 5 to 8.

According to the present invention, it is possible to obtain a coating composition capable of lowering the heating temperature and shortening the heating time in the coating process and capable of forming a coating film having excellent scratch resistance and weather resistance. Moreover, the coating film excellent also in the adhesiveness to a to-be-coated object, and a finishing external appearance can be obtained only by coating the said coating composition on the to-be-coated object. In addition, even when the object to be coated is a plastic material, a coating film excellent in scratch resistance and weather resistance, adhesion to the object to be coated, and finished appearance can be obtained without deforming the object to be coated.

Urethane acrylate (A) having an unsaturated group equivalent of 100 to 900 and a weight average molecular weight of 500 to 2500, and 65 to 90% by mass of methyl methacrylate (a) based on the total amount of copolymerization components and containing hydroxyl groups Hydroxyl group-containing acrylic resin (B), polyisocyanate compound (C) having 10 to 35% by weight of polymerizable unsaturated monomer (b) and 0 to 25% by weight of other polymerizable unsaturated monomer (c) as copolymerization components It contains a photopolymerization initiator (E).

≪Urethane acrylate (A) ≫
The urethane acrylate (A) having an unsaturated group equivalent of 100 to 900 and a weight average molecular weight of 500 to 2500 used in the coating composition of the present invention is a component that contributes to improving the curability by irradiation with active energy rays, and is usually in one molecule. And a polyurethane compound having two or more acryloyl groups.

The urethane acrylate (A) may be urethane acrylate having 100 to 900 and a weight average molecular weight of 500 to 2500, and may be one kind or a combination of two or more kinds.

Examples of the urethane acrylate (A) include:
It is obtained by reacting a polyisocyanate compound (a1) with a hydroxyl group-containing acrylate (a2) having at least one hydroxyl group and one or more acryloyl groups in one molecule and, if necessary, a polyol compound (a3). Urethane acrylate (Ai) (that is, urethane acrylate obtained by reacting polyisocyanate compound (a1) with hydroxyl group-containing acrylate (a2) having at least one hydroxyl group and one or more acryloyl groups in one molecule ( Ai) or a polyisocyanate compound (a1), a urethane acrylate obtained by reacting a polyol compound (a3) with a hydroxyl group-containing acrylate (a2) having at least one hydroxyl group and one or more acryloyl groups in one molecule (Ai)),
Alternatively, a polyol compound (a3), an isocyanate group-containing acrylate (a4) having one isocyanate group and one or more acryloyl groups in one molecule, and a polyisocyanate compound (a1) as necessary,
Urethane acrylate (Aii) obtained by reacting (that is, reacting a polyol compound (a3) with an isocyanate group-containing acrylate (a4) having one isocyanate group and one or more acryloyl groups in one molecule. Reaction of urethane acrylate (Aii) or polyol compound (a3) obtained by the above, isocyanate group-containing acrylate (a4) having one isocyanate group and one or more acryloyl groups in one molecule, and polyisocyanate compound (a1) The urethane acrylate obtained by making it react so that an unsaturated group equivalent may be set to 100-900, such as urethane acrylate (Aii)) obtained by making it react.

Polyisocyanate compound (a1)
The polyisocyanate compound (a1) is a compound having two or more isocyanate groups in one molecule. For example, aliphatic polyisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, lysine diisocyanate and uretdione type adducts, adduct type adducts, burette type adducts, isocyanurate cycloadditions of these polyisocyanates. Isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 1,3-di (isocyanatomethyl) cyclohexane, 1,4- Di (isocyanatomethyl) cyclohexane, 1,4-cyclohexane diisocyanate, 1,3-cyclopentane diisocyanate, 1,2-cyclo Alicyclic polyisocyanate compounds such as hexane diisocyanate and uretdione type adducts, adduct type adducts, burette type adducts, isocyanurate cycloadducts of these polyisocyanates; xylylene diisocyanate, metaxylylene diisocyanate, tetramethylxylylene Diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 1,4-naphthalene diisocyanate, 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate Aromatic polyisocyanate compounds such as bis (4-isocyanatophenyl) sulfone, isopropylidenebis (4-phenylisocyanate), and uretdione type adducts, adduct type adducts, burette type adducts of these polyisocyanates, Isocyanurate cycloadduct; triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 4,4′-dimethyl Polyisocyanate compounds having three or more isocyanate groups in one molecule such as diphenylmethane-2,2 ′, 5,5′-tetraisocyanate, and uretdione type adducts, adduct type adducts, and burette types of these polyisocyanates Adduct, isocyanurate ring addition The polyisocyanate compound is reacted in an excess ratio of isocyanate groups to hydroxyl groups of polyols such as ethylene glycol, propylene glycol, 1,4-butylene glycol, dimethylolpropionic acid, polyalkylene glycol, trimethylolpropane, and hexanetriol. And urethanated adducts of these polyisocyanates, isocyanurate ring adducts, and the like. These can be used alone or in combination of two or more.

Of these, aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds and the like (for example, aliphatic polyisocyanate compounds) can be suitably used from the viewpoint of the weather resistance of the coating film.

Hydroxyl-containing acrylate (a2)
The hydroxyl group-containing acrylate (a2) is a compound having at least one hydroxyl group and one or more acryloyl groups in one molecule, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl. Acrylates, monomers such as 4-hydroxybutyl acrylate, polyacrylates of polyhydric hydroxyl group-containing compounds such as trimethylolpropane diacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and the like. These polyacrylates and ε-caprolactone These adducts, adducts of these hydroxyl group-containing polyacrylates and alkylene oxides, hydroxyl group-containing epoxy acrylates, and the like. These can be used alone or in combination of two or more.

Of these, a hydroxyl group-containing acrylate having one hydroxyl group and 3 to 5 acryloyl groups in one molecule is preferable.

Examples of such acrylates include pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and the like, and these can be preferably used from the viewpoint of obtaining a cured film with high hardness.

Polyol compound (a3)
The polyol compound (a3) is a compound having two or more hydroxyl groups in one molecule. For example, ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1 , 4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,2-butanediol, -Butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol , Tetramethylene glycol, 3-methyl-4,3-penta Diol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2 , 5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydroxypivalic acid neopentyl glycol ester, hydrogenated bisphenol A, hydrogenated bisphenol F, dimethylolpropionic acid, etc. Alcohols; polylactone diols obtained by adding lactone compounds such as ε-caprolactone to these dihydric alcohols; ester diol compounds such as bis (hydroxyethyl) terephthalate; alkylene oxide adducts of bisphenol A, polyethylene glycol, Polyether diol compounds such as propylene glycol and polybutylene glycol; glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tris (2-hydroxy Ethyl) Trivalent or higher alcohols such as isocyanuric acid, sorbitol and mannitol; polylactone polyol compounds obtained by adding lactone compounds such as ε-caprolactone to these trivalent or higher alcohols; fatty acid esterified products of glycerin, etc. . These can be used alone or in combination of two or more.
Isocyanate group-containing acrylate (a4)
The isocyanate group-containing acrylate (a4) is a compound having at least one isocyanate group and one or more acryloyl groups in one molecule, such as 2-acryloyloxyethyl isocyanate, m-isopropenyl-α. , Α-dimethylbenzyl isocyanate, 1,1-bis (acryloyloxymethyl) ethyl isocyanate, and the like. These can be used alone or in combination of two or more.

<Urethane acrylate (Ai-I)>
In the coating composition of the present invention, urethane acrylate (A) is a part of its components,
The coating film contains urethane acrylate (Ai-I) having an isocyanate group and an acryloyl group in one molecule obtained by reacting caprolactone-modified hydroxyalkyl acrylate (a5) with polyisocyanate compound (a1). From the viewpoint of improving weather resistance, particularly crack resistance.

As the polyisocyanate compound (a1) used in the above (Ai-I), hexamethylene which is an isocyanurate cycloaddition product of an aliphatic polyisocyanate compound is used from the viewpoint of curability at low temperature and the weather resistance of the coating film. A polyisocyanate compound which is an isocyanurate cycloadduct of diisocyanate and a uretdione type adduct can be preferably used.

Caprolactone-modified hydroxyalkyl acrylate (a5)
As the caprolactone-modified hydroxyalkyl acrylate (a5), a compound represented by the following general formula (I) can be preferably used.

[Wherein, R ¹ is an alkylene group having 2 to 6 carbon atoms, and n is an integer of 1 to 5]. ].

Specifically, the caprolactone-modified hydroxyalkyl (meth) acrylate includes “Placcel FA-1”, “Placcel FA-2”, “Placcel FA-2D”, “Placcel FA-3”, “Placcel FA-4”, “Placcel FA-5” (all manufactured by Daicel Chemical Industries, trade name, Plaxel \ PLACCEL is a registered trademark) and the like can be mentioned. Of these, caprolactone-modified hydroxyethyl acrylate in which R ¹ is an ethylene group in general formula (I) is preferred from the viewpoint of active energy ray curability. Similarly, in terms of active energy ray curability, caprolactone-modified hydroxyethyl acrylate in which n is in the range of 1 to 3 in the general formula (I) is preferable.

The urethane acrylate (A) can be synthesized by subjecting a hydroxyl group-containing component and an isocyanate group-containing component to a known urethanization reaction.

The above reaction can be usually performed in an organic solution. Examples of the organic solvent include aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, and ester solvents such as ethyl acetate, propyl acetate, isobutyl acetate, and butyl acetate. These can be used as one or a mixture of two or more.

The reaction temperature is preferably from room temperature to 100 ° C., and the reaction time is preferably from 1 to 10 hours.

In the above reaction, an organic tin catalyst such as dibutyltin dilaurate, dibutyltin diethylhexoate or dibutyltin sulfite may be used as necessary. The amount of the catalyst is preferably 0.01 to 1.0 part by mass, more preferably 0.1 to 0.5 part by mass, with respect to 100 parts by mass of the total amount of reaction raw materials. A polymerization inhibitor such as hydroquinone monomethyl ether may be used. The addition amount of the polymerization inhibitor is preferably 0.01 to 1.0 part by mass with respect to 100 parts by mass of the total amount of reaction raw materials.

Urethane acrylate (A) has an unsaturated group equivalent of 100 to 900, preferably 120 to 900, and a weight average molecular weight of 500 to 2500, preferably 700 to 2500. When the unsaturated group equivalent and the weight average molecular weight are within these ranges, it is possible to obtain a coating film having more excellent scratch resistance and weather resistance.

Further, it is preferable that the weight average molecular weight is in the above range from the viewpoint that the viscosity of the coating composition can be easily handled.

In the present invention, the polymerizable unsaturated group means an unsaturated group capable of radical polymerization, and may be simply referred to as an unsaturated group in the present specification. Examples of the polymerizable unsaturated group include a vinyl group, a (meth) acryloyl group, a (meth) acrylamide group, a vinyl ether group, and an allyl group. Here, in this specification, an unsaturated group equivalent is calculated | required by adding dodecyl mercaptan to a radically polymerizable unsaturated group, and carrying out back titration of the remaining dodecyl mercaptan with an iodine solution.

When the urethane acrylate (A) has an isocyanate group, the isocyanate equivalent of the urethane acrylate (A) is preferably in the range of 500 to 2,500 from the viewpoint of scratch resistance of the coating film.

Here, in the present specification, the isocyanate equivalent is an isocyanate equivalent determined by back titration using dibutylamine. The reverse titration is carried out by adding excess dibutylamine to the sample for reaction, and titrating the remaining dibutylamine with an aqueous hydrochloric acid solution using bromophenol blue as a titration indicator.

Here, in this specification, the weight average molecular weight is the retention time (retention capacity) measured with a gel permeation chromatograph (“HLC ^{(registered trademark)} 8120GPC” manufactured by Tosoh Corporation) using tetrahydrofuran as a solvent. The value is calculated based on the weight average molecular weight of polystyrene. The columns are “TSK-gel G4000H _XL ”, “TSK-gel G3000H _XL ”, “TSK-gel G2500H _XL ”, “TSK-gel G2000 _XL ” (both manufactured by Tosoh Corporation, trade name, TSK-gel). , TSK_GEL is a registered trademark), and used under conditions of mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 ml / min, detector: RI.

≪Hydroxyl group-containing acrylic resin (B) ≫
The hydroxyl group-containing acrylic resin (B) used in the coating composition of the present invention comprises, based on the total amount of copolymerization components, methyl methacrylate (a) 65 to 90% by mass, hydroxyl group-containing polymerizable unsaturated monomer (b) 10 to 35% by mass and 0 to 25% by mass of other polymerizable unsaturated monomer (c) can be produced by copolymerization by a method known per se, for example, a solution polymerization method in an organic solvent.

Hydroxyl-containing polymerizable unsaturated monomer (b)
Specific examples of the hydroxyl group-containing polymerizable unsaturated monomer (b) used in the present invention include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxypropyl (meth) acrylate. Monoesterified product of (meth) acrylic acid such as 4-hydroxybutyl (meth) acrylate and a dihydric alcohol having 2 to 8 carbon atoms; and (meth) acrylic acid and a dihydric alcohol having 2 to 8 carbon atoms Ε-caprolactone modified monoester product; N-hydroxymethyl (meth) acrylamide; allyl alcohol, and (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end. These can be used alone or in combination of two or more. In the present invention, the monomer corresponding to the polymerizable unsaturated monomer having an ultraviolet-absorbing functional group, which will be described later, should be defined as the other polymerizable unsaturated monomer (c), and the hydroxyl group-containing polymerizable property. Excluded from unsaturated monomer (b).

In this specification, “(meth) acrylate” means acrylate and methacrylate, “(meth) acrylic acid” means acrylic acid and methacrylic acid, and “(meth) acryloyl” means acryloyl and methacryloyl.

Other polymerizable unsaturated monomer (c)
The other polymerizable unsaturated monomer (c) copolymerizable with the methyl methacrylate (a) and the hydroxyl group-containing polymerizable unsaturated monomer (b) is appropriately selected according to the properties desired for the hydroxyl group-containing acrylic resin (B). You can select and use.

Specific examples of the monomer are listed below. These can be used alone or in combination of two or more.

Alkyl or cycloalkyl (meth) acrylate; ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (Meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) ) Acrylate, “isostearyl acrylate” (trade name, manufactured by Osaka Organic Chemical Co., Ltd.), cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, Kurododeshiru (meth) acrylate, and the like.

Polymerizable unsaturated monomer having an isobornyl group; isobornyl (meth) acrylate and the like Polymerizable unsaturated monomer having an adamantyl group; adamantyl (meth) acrylate and the like Polymerizable unsaturated monomer having a photopolymerizable functional group such as a maleimide group Vinyl Aromatic compounds; styrene, α-methylstyrene, vinyltoluene and the like.

Polymerizable unsaturated monomer having alkoxysilyl group; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyl Triethoxysilane and the like.

Polymerizable unsaturated monomer having a fluorinated alkyl group; perfluoroalkyl (meth) acrylate such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; fluoroolefin and the like.

Polymerizable unsaturated monomer having a phosphoric acid group; 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, 2-methacryloyloxypropyl acid phosphate and the like.

Carboxyl group-containing polymerizable unsaturated monomer; (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and the like.

Nitrogen-containing polymerizable unsaturated monomers; vinyl compounds such as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate and vinyl acetate; carboxyls such as (meth) acrylic acid, maleic acid, crotonic acid and β-carboxyethyl acrylate Group-containing polymerizable unsaturated monomer: (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, glycidyl (meth) acrylate and amine compound Addenda etc. with.

Polymerizable unsaturated monomer having at least two polymerizable unsaturated groups in one molecule; allyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate and the like.

Epoxy group-containing polymerizable unsaturated monomer; polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule such as allyl (meth) acrylate and 1,6-hexanediol di (meth) acrylate; glycidyl ( (Meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, allyl Glycidyl ether and the like.

(Meth) acrylate having a polyoxyethylene chain whose molecular end is an alkoxy group.

Polymerizable unsaturated monomer having a sulfonic acid group; 2-acrylamido-2-methylpropane sulfonic acid, allyl sulfonic acid, sodium styrene sulfonate, sulfoethyl methacrylate and its sodium salt, ammonium salt and the like.

Polymerizable unsaturated monomer having a UV-absorbing functional group; 2-hydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2-hydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone 2,2′-dihydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2,2′-dihydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone, 2- (2 ′ -Hydroxy-5'-methacryloyloxyethylphenyl) -2H-benzotriazole and the like.

UV-stable polymerizable unsaturated monomer; 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6,6-tetramethyl Piperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-teto Methylpiperidine, and the like.

Polymerizable unsaturated monomer having a carbonyl group; acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrene, vinyl alkyl ketone having 4 to 7 carbon atoms (eg, vinyl methyl ketone, vinyl ethyl) Ketone, vinyl butyl ketone) and the like.

Polymerizable unsaturated monomer having an acid anhydride group; examples thereof include maleic anhydride, itaconic anhydride, citraconic anhydride, and the like.

The hydroxyl group-containing acrylic resin (B) is 65 to 90% by mass, more preferably 65 to 80% by mass of methyl methacrylate (a) based on the total amount of copolymerization components based on the adhesion to the object and the coating film hardness. , Hydroxyl group-containing polymerizable unsaturated monomer (b) 10 to 35% by mass, more preferably 20 to 35% by mass, other polymerizable unsaturated monomer (c) 0 to 25% by mass, more preferably 0 to 15% by mass. It is preferable that

By containing 65 to 90% by mass of methyl methacrylate based on the total amount of copolymerization components, adhesion to a plastic material is particularly good, and at the same time, 10 to 35 of the hydroxyl group-containing polymerizable unsaturated monomer (b). By containing the mass%, a tough film can be formed by reacting with the polyisocyanate compound (C).

The hydroxyl group-containing acrylic resin (B) preferably has an acid group such as a carboxyl group from the viewpoint of reactivity with other components having an isocyanate group.

The hydroxyl group-containing acrylic resin (B) preferably has an acid value in the range of 1 to 25 mgKOH / g, particularly 1 to 20 mgKOH / g.

The hydroxyl group-containing acrylic resin (B) generally has a weight within the range of 3,000 to 100,000, particularly 4,000 to 50,000, more particularly 5,000 to 30,000, from the viewpoint of the weather resistance of the coating film. It preferably has an average molecular weight.

≪Polyisocyanate compound (C) ≫
The polyisocyanate compound (C) is a compound having two or more isocyanate groups in one molecule, and examples thereof include those exemplified in the section of the polyisocyanate compound (a1) of the urethane acrylate (A).

Among these, from the viewpoint of the weather resistance of the coating film, it is preferable to use an isocyanurate cycloadduct of hexamethylene diisocyanate, an uretdione adduct, and an adduct type adduct, which is an isocyanurate cycloadduct of an aliphatic polyisocyanate compound. it can.

≪Coloring component (D) ≫
As the coloring component, coloring components of various tones exemplified below such as coloring pigments and coloring dyes can be used singly or in combination of two or more in order to obtain a desired coating color tone. . However, it is not limited to the following examples.

Examples of the color pigment include titanium oxide, zinc white, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, selenium pigment, perylene pigment, dioxazine pigment, diketopyrrolopyrrole. And pigments.
In addition, the following can be mentioned:
White pigment: Titanium white, zinc white, lithopone, zinc sulfide, antimony white, etc .;
Black pigment: carbon black, acetylene black, lamp black, graphite, iron black, aniline black, etc .;
Yellow pigments: ocher, yellow iron oxide, naphthol yellow S, Hansa Yellow 10G, Hansa Yellow 5G, Hansa Yellow 3G, Hansa Yellow G, Hansa Yellow GR, Hansa Yellow A, Hansa Yellow RN, Hansa Yellow R, Pigment Yellow L, Benzidine Yellow, Benzidine Yellow G, Benzidine Yellow G GR, Permanent Yellow NCG, Vulcan Fast Yellow 5G, Vulcan Fast Yellow R, Tartrage Lake, Quinoline Yellow Lake, Anslagen Yellow 6GL, etc .;
Orange pigments: chrome orange, chrome vermilion, Sudan I, permanent orange, Resol Fast Orange 3GL, permanent orange GTR, Hansa Yellow 3R, Vulcan Fast Orange GG, Benzidine Orange G, Persian Orange, Indanthrene Brilliant Orange GK, Indanthren Brilliant Orange RK, etc .;
Brown pigment: iron oxide, amber, etc .;
Red pigment: Bengala, Permanent Red 4R, Permanent Red F5R, Para Red, Fire Red, Parachlor Ortho Nitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Brilliant Carmine 6B, Permanent Red F2R, Permanent Red F4R, Permanent Red FRL, Permanent Red FRLL, Permanent Red F4RH, Fast Scarlet VD, Vulcan Fast Rubin B, Vulcan Fast Pink G, Light Fast Red Toner B, Light Fast Red Toner R, Permanent Carmine FB, Lake Red, Anthosine B, Brilliant Scarlet G, Risor Rubin GK, Pigment Scarlet 3B, Bol -5B, Toluidine Maroon, Permanent Bordeaux F2R, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Quinacridone Quinacridone red pigments such as magenta, etc .;
Purple pigment: Cobalt purple, manganese purple, fast violet B, methyl violet lake, etc .;
Blue pigments: ultramarine blue, bitumen blue, cobalt blue, cerulean blue, metal-free phthalocyanine blue, phthalocyanine blue such as chlorinated phthalocyanine blue, fast sky blue, indanthrene blue RS, indanthrene blue BC, indigo, etc .;
Green pigment: chrome green, pigment green B, naphthol green B, green gold, phthalocyanine green, etc.

Further, examples of metallic pigments include aluminum flakes and alumina flakes.

As other coloring pigments, aluminum pigments, pearl powder, graphite, MIO and other bright pigments, etc. are typical examples. Further, extender pigments may be blended as necessary, and examples of extender pigments include calcium carbonate, barium sulfate, talc, and quartz.

These coloring components are preferably mixed and dispersed with a dispersant and a dispersion resin, and are preferably pasted into a paint. Known dispersants, dispersion resins, and dispersion methods can be used.

≪Photopolymerization initiator (E) ≫
The coating composition of the present invention further contains a photopolymerization initiator (E).

Examples of the photopolymerization initiator (E) include α-diketone compounds such as benzyl and diacetyl; acyloin compounds such as benzoin; acyloin ether compounds such as benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether; thioxanthone, 2, 4 Thioxanthone compounds such as diethylthioxanthone, 2-isopropylthioxanthone, thioxanthone-4-sulfonic acid; benzophenone compounds such as benzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone; Michler's ketone Compound: acetophenone, 2- (4-toluenesulfonyloxy) -2-phenylacetophenone, p-dimethylaminoacetophenone, α, α'-dimethoxyacetoxyben Phenone, 2,2'-dimethoxy-2-phenylacetophenone, p-methoxyacetophenone, 2-methyl [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1- Acetophenone compounds such as (4-morpholinophenyl) -butan-1-one, α-isohydroxyisobutylphenone, α, α'-dichloro-4-phenoxyacetophenone, 1-hydroxy-cyclohexyl-phenyl-ketone; 2,4 Acylphosphine oxide compounds such as 1,6-trimethylbenzoyldiphenylphosphine oxide and bis (acyl) phosphine oxide; quinones such as anthraquinone and 1,4-naphthoquinone; phenacyl chloride, trihalomethylphenylsulfone, tris (tri Romechiru) -s-halogen compounds such as triazine; peroxides such as di -t- butyl peroxide and the like. These can be used as one or a mixture of two or more.

Commercially available photopolymerization initiators include, for example, IRGACURE-184, IRGACURE-261, IRGACURE-500, IRGACURE-651, IRGACURE-819, IRGACURE-907, IRGACURE-CGI-1700 (product of BASF Corp., product) Name, IRGACURE \ Irgacure is a registered trademark), Darocur-1173, Darocur-1116, Darocur-2959, Darocur-1664, Darocur-4043, Darocur-TPO (Merck Japan, trade name, Darocur \ Darocur is registered) Trademarks), Kayacure-MBP, Kayacure-DETX-S, Kayacure-DMBI, Kayacure-EPA, Kayacure-OA (manufactured by Nippon Kayaku Co., Ltd., trade name, Kayacure \ Kayacure is a registered trademark), Bicure (VI CURE) -10, Vicure-55 (trade name, manufactured by STAUFFER Co., LTD.), Trigonal ^{(registered trademark)} P1, [trade name, manufactured by AKZO Co., LTD.] , SANDORAY 1000 [manufactured by SANDOZ Co., LTD., Product name], Deep (DEAP) [manufactured by APJOHN Co., LTD., Product name], QUANTACURE-PDO , CantaCure-ITX, CantaCure-EPD (trade name, manufactured by WARD BLEKINSOP Co., LTD.), And the like.

Among the above, as the photopolymerization initiator (E), in particular, those having an absorbance at a wavelength of 375 nm of 1.0 or more measured in a cell having an optical path length of 10 mm in a 0.1% acetonitrile solution are those having a deep film curable point. Can be preferably used.

Examples of such a photopolymerization initiator include acyl phosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (acyl) phosphine oxide. It is not limited to.

Examples of commercially available products include IRGACURE-819, DAROCUR TPO, and the like.

Here, the absorbance can be measured by a known measuring method, and an ultraviolet / visible spectrophotometer can be used for the spectrum measurement. As the measurement cell, a cell made of quartz and having an optical path length of 10 mm can be used.

<Polymerizable unsaturated group-containing compound (F)>
The coating composition of the present invention may further contain a polymerizable unsaturated group-containing compound (F) other than the urethane acrylate (A) as necessary. Accordingly, the coating composition of the present invention includes those containing a polymerizable unsaturated group-containing compound (F) other than the urethane acrylate (A) in addition to the above components.

Examples of the polymerizable unsaturated group-containing compound (F) include a monofunctional polymerizable unsaturated group-containing compound (f1) and a polyfunctional polymerizable unsaturated group-containing compound (f2).

Examples of the monofunctional polymerizable unsaturated group-containing compound (f1) include an esterified product of a monohydric alcohol and (meth) acrylic acid. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (Meth) acrylate, neopentyl (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, N-acryloyloxyethylhexahydro Examples include phthalimide.
Also, for example, hydroxyl-containing (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate; acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid Carboxyl group-containing (meth) acrylates such as 2-carboxyethyl (meth) acrylate, 2-carboxypropyl (meth) acrylate and 5-carboxypentyl (meth) acrylate; glycidyl groups such as glycidyl (meth) acrylate and allyl glycidyl ether Containing radically polymerizable unsaturated group-containing compounds; vinyl aromatic compounds such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene; N, N-dimethylaminoethyl (meth) acrylate, N, N-die Nitrogen-containing alkyl (meth) acrylates such as tilaminoethyl (meth) acrylate and Nt-butylaminoethyl (meth) acrylate; acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, Examples thereof include polymerizable amide compounds such as N-dimethylaminoethyl (meth) acrylamide.

Examples of the polyfunctional polymerizable unsaturated group-containing compound (f2) include an esterified product of a polyhydric alcohol and (meth) acrylic acid. Specifically, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) Acrylate, 1,4-butanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, Dipentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, bisphenol A ethylene oxide modified di (meth) acrylate, etc. Meth) acrylate compounds; glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane propylene oxide modified tri (meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, pentaerythritol tri (meth) ) Acrylate, ε-caprolactone-modified tris (acryloxyethyl) isocyanurate and other tri (meth) acrylate compounds; pentaerythritol tetra (meth) acrylate and other tetra (meth) acrylate compounds; other dipentaerythritol penta (meth) acrylates And dipentaerythritol hexa (meth) acrylate. Furthermore, the epoxy resin which has a (meth) acryloyl group, the polyester resin which has a (meth) acryloyl group, etc. are mentioned.

<Hydroxyl-containing resin (G)>
The coating composition of this invention can contain hydroxyl-containing resin (G) other than a hydroxyl-containing acrylic resin (B) as needed further. Accordingly, the coating composition of the present invention includes those containing a hydroxyl group-containing resin (G) other than the hydroxyl group-containing acrylic resin (B) in addition to the above components.

Examples of the hydroxyl group-containing resin (G) include resins having a hydroxyl group, such as polyester resin, acrylic resin, polyether resin, polycarbonate resin, polyurethane resin, epoxy resin, and alkyd resin. These can be used alone or in combination of two or more.

Of these, the hydroxyl group-containing resin (G) is preferably a hydroxyl group-containing acrylic resin other than the hydroxyl group-containing acrylic resin (B) from the viewpoint of the weather resistance of the resulting coating film.

Further, the hydroxyl group-containing acrylic resin (G) other than the hydroxyl group-containing acrylic resin (B) can impart flexibility to the coating film, and the glass transition temperature is improved in terms of weather resistance, particularly crack resistance. It is preferable to use one having an angle of 30 ° or less, particularly preferably 0 ° or more and 30 ° or less.

<Other ingredients>
The coating composition of the present invention further comprises a curing catalyst, an ultraviolet absorber, a light stabilizer, a thickener, an antifoaming agent, a rust preventive agent, a plasticizer, an organic solvent, a surface conditioner, and an antisettling agent as necessary. The usual paint additives such as can be contained singly or in combination of two or more.
By blending the urethanized curing catalyst curing catalyst, the reaction between the hydroxyl group and the isocyanate group can be promoted, and the performance can be expressed in a shorter time.

Examples of the curing catalyst include tin octylate, dibutyltin diacetate, dibutyltin di (2-ethylhexanoate), dibutyltin dilaurate, dioctyltin diacetate, dioctyltin di (2-ethylhexanoate), Dibutyltin oxide, dioctyltin oxide, dibutyltin fatty acid salt, lead 2-ethylhexanoate, zinc octylate, zinc naphthenate, fatty acid zinc compound, cobalt naphthenate, calcium octylate, copper naphthenate, tetra (2-ethylhexyl) Organometallic compounds such as titanate; tertiary amines and the like can be mentioned, and these can be used alone or in combination of two or more.

Ultraviolet absorber The ultraviolet absorber has an action of suppressing the arrival of the deterioration of the film by absorbing incident light and converting light energy into a harmless form such as heat.

As the ultraviolet absorber, conventionally known ones can be used, and for example, benzotriazole absorber, triazine absorber, salicylic acid derivative absorber, benzophenone absorber and the like can be used.

Specific examples of the benzotriazole absorbent include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-butylphenyl) benzotriazole, 2- (2 '-Hydroxy-3', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole, 2- {2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimi Methyl) -5'-methylphenyl} benzotriazole.

Specific examples of the triazine absorbent include 2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-isooctyloxyphenyl) -1,3,5-triazine, 2- [ 4 ((2-hydroxy-3-dodecyloxypropyl) -oxy) -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4 -((2-hydroxy-3-tridecyloxypropyl) -oxy) -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- ( 2,4-dihydroxyphenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine and the like.

Specific examples of the salicylic acid derivative absorbent include phenyl salicylate, p-octylphenyl salicylate, 4-tert-butylphenyl salicylate, and the like.

Specific examples of the benzophenone absorbent include 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2 -Hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone Sodium 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 5-chloro-2- Hydroxybenzo Examples include phenone, resorcinol monobenzoate, 2,4-dibenzoyl resorcinol, 4,6-dibenzoyl resorcinol, and hydroxydodecylbenzophenone.

Other ultraviolet absorbers include, for example, 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole, 2,2′-dihydroxy-4 (3-methacryloxy-2-hydroxy Propoxy) benzophenone and the like can also be used.

Commercially available products of the above UV absorbers include, for example, TINUVIN 900, TINUVIN 928, TINUVIN 348-2, TINUVIN 479, TINUVIN 405 (trade name, TINUVIN \ Tinuvin is a registered trademark), RUVA 93 (Otsuka Chemical Co., Ltd.) Product name).

While light stabilizers, light stabilizers, one used as a radical chain inhibitor to capture active radical species produced in the degradation process of the coating, for example, light stabilizers such as hindered amine compounds.

Among the light stabilizers, a hindered piperidine compound may be mentioned as a light stabilizer exhibiting an excellent light stabilizing action. Examples of the hindered piperidine compound include bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis ( N-methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 4-benzoyloxy-2,2 ′, 6,6′-tetramethylpiperidine, bis (1,2,2,6, Monomer type such as 6-pentamethyl-4-piperidyl) {[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl} butyl malonate; poly {[6- (1,1 , 3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [ Oligomer type such as (2,2,6,6-tetramethyl-4-piperidyl) iminol]}; 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and succinic acid Examples include polyester-bonded types such as polyesters, but are not limited thereto. A known polymerizable light stabilizer can also be used as the light stabilizer.

Commercially available products of the above light stabilizers include, for example, TINUVIN 123, TINUVIN 152, TINUVIN 292 (trade name, TINUVIN \ Tinuvin is a registered trademark), HOSTAVIN 3058 (trade name, Hostavin is a registered trademark, manufactured by Clariant) ), ADK STAB LA-82 (manufactured by ADEKA Corporation, trade name, ADK STAB \ ADKSTAB and ADK STAB are registered trademarks), and the like.

Content of each component of coating composition The content of each component in the coating composition of the present invention is not particularly limited, but the following ranges are preferable from the viewpoint of the following coating film performance.

The solid content of the urethane acrylate (A) is preferably 10 to 70 parts by mass with respect to 100 parts by mass of the total resin solids in the coating composition of the present invention, from the viewpoint of scratch resistance and weather resistance. More preferably, it is 15 to 60 parts by mass.

Here, the total resin solid content means urethane acrylate (A), hydroxyl group-containing acrylic resin (B), and polyisocyanate (C), hydroxyl group-containing resin (G), and polymerizable unsaturated group-containing compound (F). When it contains, it is the total resin solid content which put them all together.

When the urethane acrylate (Ai-I) is used, the proportion of the urethane acrylate (Ai-I) is 10 mass% or more, preferably 10 to 70 mass% in the total solid content of the urethane acrylate (A). Preferably there is. These ranges are significant in terms of improving the weather resistance of the coating film, particularly in terms of crack resistance.

The solid content of the hydroxyl group-containing acrylic resin (B) is preferably from 100 parts by weight of the total resin solid content in the coating composition of the present invention, from the viewpoint of low-temperature curability and adhesion to an object to be coated. 1 to 70 parts by mass, more preferably 5 to 60 parts by mass.

The solid content of the polyisocyanate compound (C) is preferably 5 to 30 parts by mass with respect to 100 parts by mass of the total resin solids in the coating composition of the present invention in terms of low temperature curability. More preferably, it is 10 to 25 parts by mass.

When the coating composition of the present invention contains the coloring component (D), the content is not particularly limited, but the total resin solid content in the coating composition is 100 in terms of material concealment and design. A range of 0.1 to 5.0 parts by mass is preferable with respect to parts by mass, and a range of 0.2 to 3.0 parts by mass is more preferable.

From the viewpoint of coating film hardness, the coating composition of the present invention is preferably a coating composition having a light transmittance of 2.0 or more at 375 nm of a coating film formed with a dry film thickness of 30 μm, and is 3.0% or more. A coating composition is more preferred. For the measurement of the light transmittance of the coating film, for example, a spectrophotometer such as UV-3100 manufactured by Shimadzu Corporation is used. It is desirable to adjust the content of the coloring component (D) so that the light transmittance is 3.0% or more.

The content of the photopolymerization initiator (E) is preferably 0.5 to 6.0 parts by mass, more preferably 1 to 100 parts by mass of the total resin solid content in the coating composition of the present invention. 0.0 to 5.0 parts by mass. These ranges are significant in terms of reactivity to active energy rays.

When the polymerizable unsaturated group-containing compound (F) is used, the solid content thereof is 1 to 50 masses with respect to 100 mass parts of the total resin solid content in the coating composition of the present invention in terms of weather resistance. Part, preferably in the range of 3 to 40 parts by weight.

When other hydroxyl group-containing resin (G) is used, the solid content is based on 100 mass parts of the total resin solid content in the coating composition of the present invention, and the hydroxyl group-containing acrylic resin (B) and other hydroxyl group content. The content of the hydroxyl group-containing resin (G) is preferably selected so that the total resin solid content of the resin (G) is in the range of 1 to 70 parts by mass, more preferably 5 to 60 parts by mass.

When a curing catalyst is used, the content thereof is 0.005 to 5 parts by mass, preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the total resin solid content in the coating composition of the present invention, from the viewpoint of scratch resistance. It is suitable that the content is in the range of 0.5 parts by mass, more preferably 0.03 to 0.3 parts by mass.

In the case of using an ultraviolet absorber, the content is not particularly limited, but from the viewpoint of adhesion to the article to be coated and weather resistance, the total resin solid content in the coating composition of the present invention is 100 parts by mass. On the other hand, the range of 0.1 to 15 parts by mass, preferably 0.3 to 10 parts by mass is appropriate.

When the light stabilizer is used, its content is not particularly limited, but from the viewpoint of weather resistance, it is 0.1 to 10 with respect to 100 parts by mass of the total resin solid content in the coating composition of the present invention. Part by mass, preferably in the range of 0.2 to 5, is suitable.

Moreover, when urethane acrylate (A) has an isocyanate group in this invention, hydroxyl groups other than a hydroxyl-containing acrylic resin (B), a polyisocyanate compound (C), and a hydroxyl-containing acrylic resin (B) mix | blended as needed. The blending ratio of the containing resin (G) is the total amount of isocyanate groups of the polyisocyanate compound (C) and the urethane acrylate (A) and the total amount of hydroxyl groups of the hydroxyl group-containing acrylic resin (B) and the hydroxyl group-containing resin (G). Are preferably in a range where the equivalent ratio is NCO / OH = 0.30 to 2.0, and more preferably in a range of 0.50 to 1.8. These ranges are significant in terms of scratch resistance and weather resistance of the coating film.

The coating composition of the present invention may be either an organic solvent-type coating composition or a water-based coating composition, but is preferably an organic solvent-type coating composition from the viewpoint of storage stability and the like. In the present specification, the water-based coating composition is a coating in which the main component of the solvent is water, and the organic solvent-type coating composition is a coating that does not substantially contain water as a solvent.

≪Method of coating film formation≫
In the method for forming a coating film of the present invention, the coating composition is applied onto an object to be coated, set and / or preheated, and the resulting coating has a solid content of 90% by mass or more. The coating film forming method is characterized by irradiating active energy rays.

Examples of coated materials include polyethylene resin, polypropylene resin, polymethyl methacrylate resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene-acrylate (ASA) resin, polyamide resin, acrylic resin, vinylidene chloride resin, Examples of the resin include polycarbonate resin, polybutylene terephthalate (PBT) resin, polyurethane resin, and epoxy resin, and various plastic materials such as FRP, and these hybrid resins may also be used.

The object to be coated with the coating composition of the present invention is at least one selected from the group consisting of acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene-acrylate resin, polycarbonate resin, polybutylene terephthalate resin, and hybrids thereof (ie, Acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene-acrylate resin, polycarbonate resin, polybutylene terephthalate resin or a hybrid of at least two of these resins), among them, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile -Styrene-acrylate (ASA) resins are preferred.

Furthermore, metal materials such as iron, aluminum, brass, copper, stainless steel, tinplate, galvanized steel, alloyed zinc (Zn-Al, Zn-Ni, Zn-Fe, etc.) plated steel, glass, cement, concrete, etc. Application to inorganic materials; wood; fiber materials (paper, cloth, etc.) is also possible.

In addition, the application of the object to be coated with the coating composition of the present invention is not particularly limited, and examples thereof include an outer plate part of an automobile body such as a passenger car, a truck, a motorcycle, and a bus; an automobile part; a mobile phone and an audio. An example of the outer plate of a household electric product such as a device can be given.

The coating film obtained by the coating composition of the present invention exhibits excellent adhesion to various plastic materials at a low temperature and in a short time, and has a finished appearance, scratch resistance, water resistance without any deformation of the material. Excellent in resistance and impact resistance. Especially, it can be used suitably for the use to the outer-plate part of a motor vehicle body, a motor vehicle component, especially a center pillar.

The coating composition of the present invention has a solid content of usually 15% by mass or more, particularly 20 to 60% by mass, and a viscosity of 5 to 30 seconds / Ford Cup # 4/20 ° C. It is preferable to adjust within the range.

The method for applying the coating composition of the present invention is not particularly limited. For example, it can be applied by air spray, airless spray, rotary atomizing coater, dip coating, brush or the like. Electrostatic application may be performed during coating. The coating film thickness can be in the range of usually 10 to 100 μm, preferably 10 to 50 μm, and more preferably 15 to 35 μm as a cured film thickness.

In the method for forming a coating film of the present invention, the coating composition is applied on an object to be coated, setting and / or preheating is performed, and after the solid content of the obtained coating film is 90% by mass or more, Irradiates active energy rays.

Here, the confirmation of the solid content of the obtained coating film was performed by weighing the change in mass after curing and calculating the solid content. Specifically, 100 mm × 150 mm × 3.0 mm ABS coated object (m ₀ ) was weighed, and this coating composition was applied onto the coated object. Then, after preheating at 80 ° C. for 3 minutes, a semi-cured coated plate (m ₁ ) was obtained. Then heated 60 minutes at 80 ° C., to obtain fully cured painted plate (m _2). These ABS coated objects and coated plates were weighed and confirmed to be 90% by mass or more according to the following formula.

Solid content (mass%) of coating film = (m ₂ -m ₀ ) / (m ₁ -m ₀ ) × 100
m ₀ : Mass of the object to be coated before painting (g)
m ₁ : Mass (g) after pre-coating and semi-curing after coating
m ₂ : Mass (g) after the coating film is completely cured
Making the solid content of the coating film 90% by mass or more is performed in order to reduce the volatile content of the coating film immediately after coating or to remove the volatile component, and can be performed by an air blow, an IR furnace or the like. Setting can usually be performed by leaving the coated object to stand for 30 to 600 seconds at room temperature in a dust-free atmosphere. The preheating can be usually performed by directly or indirectly heating the coated article in a drying furnace at a temperature of 40 to 90 ° C., preferably 50 to 70 ° C. for 1 to 30 minutes. Further, when air blowing is performed, it can be usually performed by blowing air heated to a normal temperature or a temperature of 25 ° C. to 80 ° C. on the coated surface of the object to be coated.

In the present invention, heating may be performed after active energy ray irradiation, or heating and active energy ray irradiation may be performed simultaneously.

Further, when heating and active energy ray irradiation are performed simultaneously, heat from an active energy ray irradiation source (for example, heat generated by a lamp) may be used as a heat source. Further, when the active energy ray irradiation is performed after the heating, the active energy ray irradiation may be performed in a state where the object to be coated is heated (a state having a residual heat).

The heating conditions at the time of irradiation with active energy rays are not particularly limited, but when the plastic material is deformed by heat, it is preferable that the maximum surface temperature of the object to be coated is less than 90 ° C, and further 50 ° C. The temperature is preferably 80 ° C. or lower.

As described above, it is preferable to use a heat ray cut filter and / or a cold mirror in order to control the temperature rise during irradiation with active energy rays.

If the heating condition during irradiation with active energy rays is higher than the above range, it is not preferable because deformation occurs depending on the material.

The coating composition of the present invention has curability at a low temperature, and it is possible to obtain desired performance such as scratch resistance and weather resistance without heating at a high temperature (eg, 90 ° C. or higher). .

In addition, since the coating composition of the present invention can be cured even with active energy rays, desired performance such as scratch resistance and weather resistance can be obtained without heating for a long time. Heating is preferably performed for 1 to 30 minutes, more preferably 1 to 20 minutes.

Examples of the active energy ray include ultraviolet light, visible light, and laser light (near infrared light, visible light laser, ultraviolet laser, etc.). The irradiation dose is usually in the range of 100 to 5,000 mJ / cm ² , preferably 300 to 3,000 mJ / cm ² . As the active energy ray irradiation source, conventionally used ones such as ultra-high pressure, high pressure, medium pressure, low pressure mercury lamp, FusionUV electrodeless lamp, chemical lamp, carbon arc lamp, xenon lamp, metal halide Lamps, fluorescent lamps, tungsten lamps, light sources obtained from each light source such as sunlight, visible light rays cut by an ultraviolet cut filter, various lasers having oscillation lines in the visible region, etc., but metal halide lamps are particularly suitable Can be used for

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the specific embodiments described in the following examples. “Part” and “%” indicate “part by mass” and “% by mass” unless otherwise specified.

≪Manufacture of urethane acrylate≫
(Production Example 1) Urethane acrylate (A-1)
A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and an air blowing device was charged with 888 parts of isophorone diisocyanate, 464 parts of 2-hydroxyethyl acrylate, and 0.70 part of hydroquinone monomethyl ether, and air was introduced into the reaction container. The temperature was raised to 80 ° C. while blowing, and maintained at that temperature for 5 hours. After confirming that all of the added 2-hydroxyethyl acrylate had reacted, 136 parts of pentaerythritol, 372 parts of butyl acetate and dibutyl Add 0.20 parts of tin dilaurate and maintain at 80 ° C., confirm that substantially all of the isophorone diisocyanate has reacted, and cool to obtain a urethane acrylate (A-1) solution having a solid content of 80%. It was. The weight average molecular weight of the obtained urethane acrylate was 1488, and the unsaturated group equivalent was 372.

The confirmation of the urethanization reaction was confirmed by measuring the isocyanate equivalent by the method described in the section of the urethane acrylate (A).

(Production Example 2) Urethane acrylate (A-2)
191 parts of methoxypropyl acetate, 168 parts of hexamethylene diisocyanate, 596 parts of pentaerythritol triacrylate, and 0.10 parts of hydroquinone monomethyl ether are charged into a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and air blowing device. While blowing air into the reaction vessel, the temperature was raised to 80 ° C., kept at that temperature for 5 hours, cooled after confirming that substantially all of the hexamethylene diisocyanate had reacted, and urethane acrylate having a solid content of 80% (A-2) A solution was obtained. The weight average molecular weight of the obtained urethane acrylate was 764, and the unsaturated group equivalent was 127.

(Production Example 3) Urethane acrylate (A-3)
In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and dropping device, 25.3 parts of methoxypropyl acetate, 50.0 parts of isocyanurate cycloadduct of hexamethylene diisocyanate, 0.02 parts of dibutyltin dilaurate, and hydroquinone A mixture of 0.20 parts of monomethyl ether was charged. The mixture was heated to 50 ° C. with stirring. Subsequently, 51.1 parts of Plaxel FA-2D (trade name, manufactured by Daicel Chemical Industries) was added dropwise over 8 hours while keeping the temperature of the mixture not exceeding 60 ° C., and the mixture was further stirred at 60 ° C. for 1 hour. As a result, a urethane acrylate (A-3) solution having a solid content of 80% was obtained. The obtained urethane acrylate had an isocyanate equivalent of 681, an unsaturated group equivalent of 681, and a weight average molecular weight of 1021.

(Production Example 4) Urethane acrylate (A-4)
In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and air blowing apparatus, 113.5 parts of methoxypropyl acetate, 222 parts of isophorone diisocyanate, 232 parts of 2-hydroxyethyl acrylate, and 0.10 parts of hydroquinone monomethyl ether While blowing air into the reaction vessel, the temperature was raised to 80 ° C., kept at that temperature for 5 hours, cooled after confirming that substantially all of the isophorone diisocyanate had reacted, and urethane having a solid content of 80% An acrylate (A-4) solution was obtained. The weight average molecular weight of the obtained urethane acrylate was 454, and the unsaturated group equivalent was 227.

≪Production of hydroxyl group-containing acrylic resin (B) ≫
(Production Example 5) Hydroxyl group-containing acrylic resin (B-1)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a dropping device was charged with 40 parts of xylene and 40 parts of methoxypropyl acetate and stirred at 100 ° C. while blowing nitrogen gas, and 68 parts of methyl methacrylate, A mixture of 10 parts of n-butyl acrylate, 20 parts of 2-hydroxyethyl acrylate, 2.0 parts of acrylic acid and 6.0 parts of 2,2′-azobisisobutyronitrile was added dropwise at a uniform rate over 3 hours. The mixture was further aged for 2 hours at the same temperature. Thereafter, a mixture of 10 parts of xylene and 0.50 part of 2,2′-azobisisobutyronitrile was added dropwise to the reaction vessel over 1 hour, and after completion of the addition, the mixture was aged for 1 hour to obtain a hydroxyl group-containing acrylic having a solid content of 55%. A resin (B-1) solution was obtained.

The resulting hydroxyl group-containing acrylic resin (B-1) had an acid value of 15.6 mgKOH / g, a hydroxyl value of 96.6 mgKOH / g, a weight average molecular weight of 10,000, and a glass transition temperature of 34.9 ° C.

(Production Example 6) Hydroxyl group-containing acrylic resin (B-2)
A hydroxyl group-containing acrylic having a solid content of 55%, except that 75 parts of methyl methacrylate, 3.0 parts of n-butyl acrylate, 20 parts of 2-hydroxyethyl acrylate, and 2.0 parts of acrylic acid are blended. A resin (B-2) solution was obtained.

The obtained hydroxyl group-containing acrylic resin (B-2) had an acid value of 15.6 mgKOH / g, a hydroxyl value of 96.6 mgKOH / g, a weight average molecular weight of 10,000, and a glass transition temperature of 48.2 ° C.

<Manufacture of other hydroxyl group-containing resin (G)>
(Production Example 7) Hydroxyl group-containing acrylic resin (G-1)
10 parts of styrene, 33 parts of methyl methacrylate, 8.0 parts of i-butyl methacrylate, 27 parts of n-butyl acrylate, 20 parts of 2-hydroxyethyl acrylate, 2.0 parts of acrylic acid, 2,2′-azobisisobuty A hydroxyl group-containing acrylic resin (G-1) solution having a solid content of 55% was obtained in the same manner as in Production Example 5 except that 3.0 parts of nitrile and 0.50 part of addition were added.

The obtained hydroxyl group-containing acrylic resin (G-1) had an acid value of 15.6 mgKOH / g, a hydroxyl value of 96.6 mgKOH / g, a weight average molecular weight of 20000, and a glass transition temperature of 3.9 ° C.

(Production Example 8) Hydroxyl group-containing acrylic resin (G-2)
A hydroxyl group-containing acrylic resin having a solid content of 55% (same as Production Example 5) except that 60 parts of methyl methacrylate, 18 parts of n-butyl acrylate, 20 parts of 2-hydroxyethyl acrylate, and 2.0 parts of acrylic acid were blended. G-2) A solution was obtained.

The obtained hydroxyl group-containing acrylic resin (G-2) had an acid value of 15.6 mgKOH / g, a hydroxyl value of 96.66 mgKOH / g, a weight average molecular weight of 10,000, and a glass transition temperature of 21.0 ° C.

(Production Example 9) Hydroxyl group-containing acrylic resin (G-3)
A hydroxyl group-containing acrylic resin (G-3) solution having a solid content of 55% was prepared in the same manner as in Production Example 5 except that 95 parts of methyl methacrylate, 3.0 parts of 2-hydroxyethyl acrylate, and 2.0 parts of acrylic acid were added. Obtained.

The obtained hydroxyl group-containing acrylic resin (G-3) had an acid value of 15.6 mgKOH / g, a hydroxyl value of 14.5 mgKOH / g, a weight average molecular weight of 10,000, and a glass transition temperature of 96.4 ° C.

≪Production of coloring component (D) ≫
(Production Example 10) Colored component paste (D-1)
A mill base was prepared by mixing 52.4 parts of methoxypropyl acetate, 15 parts of carbon black and 32.6 parts of DISPERBYK-2001 (dispersant, 46% active ingredient manufactured by Big Chemie Japan). Dispersion was carried out for 60 minutes with a bead mill to obtain a black paste (D-1) having a pigment concentration of 15% by weight.

(Production Example 11) Colored component paste (D-2)
A mill base was prepared by mixing 52.4 parts of methoxypropyl acetate, 15 parts of chlorinated copper phthalocyanine blue and 32.6 parts of DISPERBYK-2001 (dispersant, 46% active ingredient manufactured by Big Chemie Japan). Dispersion was carried out for 60 minutes with a bead mill to obtain a blue paste (D-2) having a pigment concentration of 15% by weight.

(Production Example 12) Colored component paste (D-3)
A mill base was prepared by mixing 52.4 parts of methoxypropyl acetate, 15 parts of quinacridone magenta, and 32.6 parts of DISPERBYK-2001 (dispersant, 46% active ingredient, manufactured by BYK Japan). Dispersion was carried out for 60 minutes with a bead mill to obtain a blue paste (D-3) having a pigment concentration of 15% by weight.

(Production Example 13) Urethane acrylate (A-7)
Dry air was blown into a 1 liter clean four-necked flask equipped with a stirrer, gas inlet tube, condenser and thermometer, and the air in the flask was replaced with dry air, and then Aronix M-305 [Toa Synthetic Co., Ltd. pentaerythritol triacrylate, Gardner viscosity (25 ° C.): R, hydroxyl value: 130] 651.6 parts, Sumilizer BHT [Sumitomo Chemical Industries, Ltd. antioxidant] 2.4 parts, 0.2 parts of Metoquinone (a polymerization inhibitor manufactured by Seiko Chemical Industry Co., Ltd.), 0.1 parts of dibutyltin diacetate and 200 parts of butyl acetate were added and stirred uniformly, and the temperature was raised to 70 ° C. Next, 145.7 parts of isophorone diisocyanate was added in portions in the flask while paying attention to heat generation, and the temperature was raised to 80 ° C. and maintained for 4 hours to obtain a urethane acrylate (A-7) solution having a weight molecular weight of 1056 [nonvolatile content: 80 996 parts of 3%, Gardner viscosity (25 ° C.): OP, Gardner color: 1 or less]. The unsaturated group equivalent of urethane acrylate (A-7) was 176. In this urethane acrylate (A-7), it was confirmed by IR measurement that the 2240 cm ⁻¹ peak due to the isocyanate group had disappeared.

(Production Example 14) Acrylic resin After nitrogen gas was blown into a 2-liter clean separable flask equipped with a stirrer, gas introduction tube, condenser, dropping funnel and thermometer, and the air in the flask was replaced with nitrogen gas Then, 275 parts of toluene and 275 parts of n-butanol were added to the flask, and the temperature was raised to 110 ° C. with stirring. Next, 180 parts of methyl methacrylate, 270 parts of n-butyl methacrylate, 2 parts of perbutyl O [t-butylperoxy-2-ethylhexanoate manufactured by Nippon Oil & Fats Co., Ltd.] and perbutyl Z [Nippon Oils & Fats Co., Ltd.] A premix containing 2 parts of t-butylperoxybenzoate manufactured in the mixture was dropped into the flask over 4 hours using a dropping funnel, and after the completion of dropping, the mixture was kept at 110 ° C. for 6 hours to hold an acrylic resin solution [nonvolatile Minute: 45.3%, Gardner viscosity (25 ° C.): X, Gardner color: 1 or less, Number average molecular weight (Mn) of acrylic resin: 30,000, Weight average molecular weight (Mw) of acrylic resin: 7
2,000] 997 parts were obtained.

(Production Example 15) Acrylic resin (G-4)
Synthesis Example 1 except that a premix containing 202.5 parts methyl methacrylate, 202.5 parts n-butyl methacrylate, 45 parts β-hydroxyethyl methacrylate, 2 parts perbutyl O and 2 parts perbutyl Z was used. In the same manner as above, an acrylic resin (G-4) solution [nonvolatile content: 45.0%, Gardner viscosity (25 ° C.): V, Gardner color: 1 or less, number average molecular weight (Mn) of acrylic resin: 28,000 The weight average molecular weight (Mw) of acrylic resin (G-4): 60,000] 998 parts.

≪Preparation of paint composition≫
(Example 1) Coating composition No. 1
Urethane acrylate (A-1) 62.5 parts (solid content 50 parts), hydroxyl group-containing acrylic resin (B-1) 54.5 parts (solid content 30 parts), hexamethylene diisocyanate isocyanate ring adduct 20 parts, coloring 6.7 parts of component paste (D-1) (coloring component amount 1.0 part), 0.50 part of Darocur TPO, 3.0 part of Darocur 1173, and acetic acid so that the solid content of the paint is 50% After dilution with butyl, the coating composition No. 1 was obtained.

(Examples 2 to 27, Comparative Examples 1 to 6)
In the same manner as in Example 1 with the solid content shown in Tables 1 and 2, the coating composition No. 2-33 were obtained.

Moreover, the light transmittance of the coating film produced with each coating composition was measured, and the measurement results are shown in Table 1 and Table 2.

(Note 1) EBECRYL ^{(registered trademark)} 244: manufactured by Daicel Cytec Co., Ltd., trade name, bifunctional urethane acrylate, weight molecular weight 2000, unsaturated group equivalent 1000.
(Note 2) EBECRYL ^{(registered trademark)} 8405: manufactured by Daicel-Cytec, Inc., trade name, tetrafunctional urethane acrylate, weight molecular weight 2700, unsaturated group equivalent 675.
(Note 3) Duranate ^TM P301-75E: Asahi Kasei Chemicals, product name, adduct type adduct of hexamethylene diisocyanate.
(Note 4) Darocur ^{(registered trademark)} TPO: manufactured by Merck Japan, trade name, photopolymerization initiator.
(Note 5) Irgacure ^{(registered trademark)} 819: manufactured by BASF, trade name, photopolymerization initiator.
(Note 6) Darocur ^{(registered trademark)} 1173: Merck Japan, trade name, photopolymerization initiator.
(Note 7) Hostavin ^{(registered trademark)} 3058 LIQ. : Made by Clariant, trade name, light stabilizer.
(Note 8) Light transmittance:
The average light transmittance at a wavelength of 375 nm of the cured coating film having a thickness of 30 μm was measured by the following method;
First, each coating composition was applied on a polypropylene plate so that the thickness of the coating film when cured was 30 μm. Next, the coating film on the polypropylene plate was cured. Next, the cured coating film was peeled off and collected, and the light transmittance at a wavelength of 375 nm was measured using a spectrophotometer. As the spectrophotometer, “UV-3100” (trade name, manufactured by Shimadzu Corporation) was used.

(Comparative Example 7) Coating composition No. Preparation of 34 (colored paint composition) 100 parts of the acrylic resin (G-4) solution obtained in Production Example 15 and 15.8 parts of carbon black [MA-100 manufactured by Mitsubishi Chemical Co., Ltd.] were blended to prepare a colored paint. Composition No. 34 was prepared. Subsequently, the obtained colored coating composition No. 34 was diluted with a thinner having the following composition such that the viscosity of Ford Cup # 4 was 10 seconds at 25 ° C .:
Thinner composition: xylene / toluene / ethyl acetate / butyl acetate / ethylene glycol monoethyl ether acetate = 25/40/15/10/10 (% by weight).

(Comparative Example 8) Coating composition No. Production of 35 (energy ray curable top coat) 37 parts by mass of the acrylate compound (A-7) solution obtained in Production Example 13 and 30 parts of Kayrad DPHA [Nippon Kayaku Co., Ltd. dipentaerythritol hexaacrylate], Production Example 14 and 3.0 parts of Irgacure 184 (manufactured by BASF Corporation, 1-hydroxycyclohexylphenylphenyl ketone) are blended. 35 was obtained.

≪Preparation of test version≫
(ASA coating)
The surface of a 100 mm × 150 mm × 3.0 mm acrylonitrile-styrene-acrylate plate was degreased with isopropyl alcohol to obtain an ASA coating.

(ABS substrate)
The surface of a 100 mm × 150 mm × 3.0 mm acrylonitrile-butadiene-styrene plate was degreased with isopropyl alcohol to obtain an ABS coating.

(PC / PBT substrate)
The surface of a 100 mm × 150 mm × 3.0 mm polycarbonate-polybutylene terephthalate plate was degreased with isopropyl alcohol to obtain a PC / PBT coated object.

(Al coated material)
5182 material (JIS), which is an aluminum / magnesium alloy material of 100 mm × 150 mm × 0.23 mm, was used as the Al coating.

(Fe coating)
A steel sheet having a surface treated with zinc phosphate having a size of 100 mm × 150 mm × 1.0 mm was degreased with petroleum benzine to obtain an Fe coating.

≪Painting process≫
(Examples 28 to 63, Comparative Examples 9 to 14)
Each of the coating compositions obtained in Examples 1 to 27 and Comparative Examples 1 to 6 was applied to the coating materials shown in Tables 3 and 4 by air spray so that the dry film thickness was 30 μm. The curing process of preheating after coating, irradiation with active energy rays and heating was performed under the following conditions.

(Curing process 1)
After drying with a hot air dryer set at 80 ° C. for 5 minutes to make the solid content of the coating film 90% by mass or more, it is 300 mW / d with D-bulb (UV irradiation device manufactured by Fusion UV Systems) equipped with a cold mirror. UV irradiation of cm ² and 1500 mJ / cm ² was performed for 1 minute. The curing process time was 6 minutes.

(Curing process 2)
After drying for 5 minutes with a hot air dryer set at 80 ° C., the solid content of the coating film is set to 90% by mass or more, and then 300 mW / d with a D-bulb (an ultraviolet irradiation device manufactured by Fusion UV Systems) with an aluminum mirror attached. UV irradiation of cm ² and 1500 mJ / cm ² was performed for 1 minute. The curing process time was 6 minutes.

(Curing process 3)
After drying for 5 minutes with a hot air dryer set at 80 ° C., the solid content of the coating film is set to 90% by mass or more, and then 300 mW / d with a D-bulb (an ultraviolet irradiation device manufactured by Fusion UV Systems) with an aluminum mirror attached. UV irradiation of cm ² and 1500 mJ / cm ² was performed for 1 minute. Then, it heated for 10 minutes with the hot air dryer set to 80 degreeC. The curing process time was 16 minutes.

(Curing process 4)
After drying with a hot air dryer set at 80 ° C. for 5 minutes to make the solid content of the coating film 90% by mass or more, 300 mW with D-bulb (ultraviolet irradiation device manufactured by Fusion UV Systems) equipped with a heat ray cut filter. / Cm ² and 1500 mJ / cm ² of UV irradiation were performed for 1 minute. The curing process time was 6 minutes.

(Curing process 5)
After drying with a hot air dryer set at 80 ° C. for 5 minutes to make the solid content of the coating film 90% by mass or more, it is 300 mW / d with D-bulb (UV irradiation device manufactured by Fusion UV Systems) equipped with a cold mirror. UV irradiation of cm ² and 1500 mJ / cm ² was performed for 1 minute. Then, it heated for 10 minutes with the hot air dryer set to 80 degreeC. The curing process time was 16 minutes.

(Curing process 6)
D-bulb (ultraviolet irradiation device manufactured by Fusion UV Systems) equipped with a cold mirror after drying for 10 seconds using a parallel irradiation type line heater HYP-20N manufactured by Hibeck Co., Ltd. after setting at 20 ° C for 50 seconds And 300 mW / cm ² and 1500 mJ / cm ² of UV irradiation were performed for 1 minute. Incidentally, the solid content of the coating film was 90 mass or more by drying with a parallel irradiation type line heater HYP-20N for 10 seconds. The curing process time was 2 minutes.

Test plates were obtained from the coating compositions and processes described in Tables 3, 4 and 5 for the coating compositions obtained in Tables 1 and 2. The evaluation results of each test plate are also shown in Table 3, Table 4, and Table 5.

(Comparative Example 15)
A colored coating composition no. No. 34 was spray-coated, and further, heat-dried at 70 ° C. for 10 minutes in a hot air drying furnace to obtain a colored coated plate having a colored layer having a thickness of 10 μm. Thereafter, the obtained colored coated plate was coated with a coating composition No. 35 (Comparative Example; energy beam curable top coat) was applied using a bar coater to a film thickness of 10 μm, dried in a hot air drying oven set at 70 ° C. for 10 minutes, and then 160 W / cm ^The sample was passed under a high-pressure mercury lamp No. 2 once at a speed of 5 m / min from a distance of 15 cm and subjected to UV irradiation for 1 minute to obtain a test plate. The curing process time was 21 minutes. (Curing process 7)
Table 5 shows the evaluation results of the test plate.

≪Test method≫
(Note 9) Finishability:
For each test plate, the following appearance (crude) was evaluated by visual evaluation and gloss measurement according to the following criteria:
<Appearance (Hada)>
The state of the coating film was visually observed to examine the appearance of the coating film such as Yuzuhada:
S: Smooth and no YUZHADA is recognized A: Very few YUZHADA is recognized B: YUZHADA is observed C: Significant YUZHADA is recognized <Gloss Measurement>
The glossiness of each coated surface was measured according to the specular glossiness (60 degrees) of JIS K5600-4-7 (1999). The measured gloss was evaluated according to the following criteria:
S: No abnormality is observed on the coating film surface, and the specular gloss (60 degrees) is 85 or more A: The specular gloss (60 degrees) is 70 or more and less than 85 B: The specular gloss (60 degrees) is 60 or more and less than 70 C: Specular gloss (60 degrees) is less than 60 <Material concealment>
An ASA plate (flat plate) that was rubbed back and forth 10 times with # 2000 sandpaper and polished was used as the coated plate. Further, the coating composition was applied thereon so as to have a dry film thickness of 30 μm to prepare a cured coating film under predetermined curing conditions, and a test plate (with polishing) was obtained. In addition, the ASA plate was coated under the same conditions as above without polishing, to produce a cured coating film, and a test plate (no polishing) was obtained. The L ^* value of this test plate (without polishing) and the test plate (with polishing) was measured, and the difference ΔL ^* was determined to evaluate the material concealment property according to the following criteria:
S: ΔL ^* is less than 0.3 A: ΔL ^* is 0.3 or more and less than 0.5 B: ΔL ^* is 0.5 or more and less than 1 C: ΔL ^* is 1.0 or more.

(Note 10) Scratch resistance:
Each test plate was subjected to a Taber abrasion test (abrasion wheel CF-10P, load 500 g, 100 rotations) in accordance with ASTM D1044. With respect to the coating film before and after the test, the glossiness of each coated surface was measured according to the specular glossiness (60 degrees) of JIS K5600-4-7 (1999). The gloss after the test relative to the gloss before the test was determined as a gloss retention (%) and evaluated according to the following criteria:
S: Gloss retention 90% or more A: Gloss retention 80% or more and less than 90% B: Gloss retention 60% or more and less than 80% C: Gloss retention 20% or less.

(Note 11) Adhesion (initial):
After making 100 goby meshes of 2.0mm x 2.0mm on the coated surface according to JIS K 5600-5-6 (1990) on each coated surface, sticking adhesive tape on the surface and peeling it off rapidly The number of Gobang eye coats remaining on the paint surface was evaluated according to the following criteria:
A: remaining number / total number = 100/100 B: remaining number / total number = 99 to 90/100 C: remaining number / total number = 89 or less / 100

(Note 12) Water resistance:
About each test board, it was immersed in 40 degreeC warm water for 7 days, and the water resistance test was done. The test plate after the test was evaluated for appearance and adhesion according to the following criteria:
<Appearance (after water resistance test)>
The state of the coating after the water resistance test was visually observed to examine the appearance of the coating, such as whitening:
A: No abnormality B: Slight whitening is observed C: Whitening is observed <Adhesion (after water resistance test)>
Make 100 pieces of 2.0mm x 2.0mm goblet on the coated surface of the test plate according to JIS K 5600-5-6 (1990) and apply adhesive tape to the surface. After peeling off, the number of goby eye coatings remaining on the paint surface was evaluated according to the following criteria:
A: remaining number / total number = 100/100 B: remaining number / total number = 99 to 90/100 C: remaining number / total number = 89 or less / 100

(Note 13) Weather resistance:
Each test plate was subjected to a 2000-hour weather resistance test using a sunshine weatherometer in accordance with JIS K 5600-7-8 (1999). The test plate after the test was evaluated for appearance (warming), gloss measurement and adhesion according to the following criteria:
<Appearance (wallet)>
The state of the coating film after the weather resistance test was visually observed to examine the appearance of the coating film such as cracks:
S: No abnormality A: Cracks are recognized in the coating film when viewed closely, but there is no problem when the product is made. B: Slight cracking is observed in the coating film C: Cracking is observed in the coating film <Gloss retention rate ( After weather resistance test) ＞
For the coating film before and after the test, the gloss of each coated surface was measured according to the specular gloss (60 degrees) of JIS K5600-4-7 (1999). The gloss after the test relative to the gloss before the test was determined as a gloss retention (%) and evaluated according to the following criteria:
S: Gloss retention 90% or more A: Gloss retention 80% or more and less than 90% B: Gloss retention 60% or more and less than 80% C: Gloss retention 60% or less <Adhesion (after weather resistance test)>
In accordance with JIS K 5600-5-6 (1990), 100 2.0 mm × 2.0 mm goby meshes are made on the coating surface of each test plate, and adhesive tape is affixed to the surface, and After peeling off, the number of Gobang eye coats remaining on the paint surface was evaluated according to the following criteria:
A: remaining number / total number = 100/100 B: remaining number / total number = 99 to 90/100 C: remaining number / total number = 89 or less / 100

(Note 14) Coating film hardness:
A pencil scratch test (hand scuffing method) was performed on the coating surface of each test plate in accordance with JIS K 5600-5-6 (1990). Evaluation was based on the following criteria:
S: F or more A: HB or more and less than F B: B or more and less than HB C: Less than B.

(Note 15) Curing process time:
It refers to the total number of fractions required for setting, preheating using a hot air dryer or the like after application of the coating composition, irradiation with active energy rays, and post-baking using a hot air dryer after irradiation with active energy rays. In each step, the total time required for coating film curing was evaluated. The time required for the active energy ray irradiation step was uniformly 1 minute.

(Note 16) Maximum surface temperature:
A thermocouple of a temperature measuring machine equipped with a recording device was attached to the surface of each object before irradiation with active energy rays, and irradiation was performed in the same manner as irradiation of active energy rays performed in each curing step. At that time, the maximum temperature recorded in the temperature measuring machine was defined as the maximum temperature reached by the surface of each article to be coated.

(Note 17) Warpage of workpiece:
Evaluation was made with each coated plate of 100 mm × 150 mm. For items with warpage, place them on a glass that is flat in a convex direction, and evaluate the warpage in millimeters based on the difference between the thickness of the plate before painting and the height from the glass surface to the highest part of the convex part according to the following criteria. did:
S: No warpage at all A: Less than 0.5 mm B: 0.5 mm or more and less than 2.0 mm C: 2.0 mm or more

(Note 18) Comprehensive evaluation In the field of paints to which the present invention belongs, the heating temperature in the coating process can be reduced and the heating time can be shortened, the scratch resistance and weather resistance of the resulting coating film are high, and the finished appearance is good. It is desirable that there be good adhesion to the object. Therefore, a comprehensive evaluation was performed according to the following criteria:
S: The above curing process time is 20 minutes or less, the maximum surface temperature is less than 90 ° C., and the finish <appearance (crude)>, finish <gloss measurement>, scratch resistance, adhesion (initial) , Water resistance <appearance (after water resistance test)>, water resistance <adhesion (after water resistance test)>, weather resistance <appearance (warming)>, weather resistance <gloss retention (after weather resistance test)>, weather resistance < Adhesiveness (after weather resistance test)>, coating film hardness, and warpage of the object are all S or A. A: The above curing process time is 20 minutes or less, and the maximum temperature reached on the surface is 90 ° C. And the above 11 items are all A. B: The curing process time is 20 minutes or less, the maximum surface temperature is less than 90 ° C., and all the 11 items are S, A or B. At least one is B. C: The above curing process time is longer than 20 minutes or Either the highest temperature is 90 ° C. or higher, or at least one of the 11 items is C.

As apparent from the above results, urethane methacrylate (A) having an unsaturated group equivalent of 100 to 900 and a weight average molecular weight of 500 to 2500, methyl methacrylate (a) 65 to 90% by mass based on the total amount of copolymerization components , Hydroxyl group-containing acrylic resin (B) having a hydroxyl group-containing polymerizable unsaturated monomer (b) of 10 to 35% by mass and another polymerizable unsaturated monomer (c) of 0 to 25% by mass as a copolymerization component; The coating composition containing C) and the photopolymerization initiator (E) can reduce the heating temperature and the heating time in the coating process, and the resulting coating film has high scratch resistance and weather resistance, and has a finished appearance. It can be seen that it is good and has good adhesion to the object. Moreover, material concealment property can further be improved by mix | blending a coloring component (D) with this coating composition.

Claims

Urethane acrylate (A) having an unsaturated group equivalent of 100 to 900 and a weight average molecular weight of 500 to 2500, 65 to 90% by mass of methyl methacrylate (a) based on the total amount of copolymerization components, a hydroxyl group-containing polymerizable unsaturated monomer ( b) Hydroxyl-containing acrylic resin (B), polyisocyanate compound (C) and photopolymerization initiator (E) containing 10 to 35% by mass and other polymerizable unsaturated monomer (c) as a copolymerization component of 0 to 25% by mass ) Containing coating composition.
The coating composition according to claim 1, comprising 10 to 70 parts by mass of the urethane acrylate (A) in 100 parts by mass of the total resin solid content in the coating composition.
The coating composition according to claim 1, further comprising a coloring component (D).
The coating composition according to claim 1, wherein the light transmittance at 375 nm of the coating film formed with a dry film thickness of 30 μm is 3.0% or more.
The coating composition according to claim 1 is applied on an object to be coated, setting and / or preheating is performed, the solid content of the obtained coating film is set to 90% by mass or more, and then an active energy ray is applied. Irradiating a coating film forming method.
The coating film formation method of Claim 4 which heats after the said active energy ray irradiation.
The method for forming a coating film according to claim 4, wherein the article to be coated is acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene-acrylate resin, polycarbonate resin, polybutylene terephthalate resin, or a hybrid of at least two of these resins.
The method for forming a coating film according to claim 4, wherein the maximum temperature reached to the surface of the article to be coated is less than 90 ° C during irradiation with the active energy ray.
An article coated with the coating composition according to claim 1.
An article coated by the coating film forming method according to claim 4.