JP2010077281A - Photocurable coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable coating composition which can be suitably applied to a colored layer coated on a metal-deposited surface or on metals over a metal including plating treatments and various plastic molded products, exhibiting excellent adhesiveness and giving a cured film having excellent hardness and scratch resistance. <P>SOLUTION: The photocurable coating composition contains (meth)acrylate compound containing a phosphate group, an acrylic resin containing a hydrogen oxide group, a polyfunctional (meth)acrylate compound containing a hydroxide group and a photoinitiator. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photocurable resin composition that can be cured by ultraviolet rays, electron beams, radiation, and the like. Specifically, it is a photo-curing type that can produce a cured coating film that exhibits excellent adhesion to metal-deposited surfaces and pigment-containing colored layers of metals and plastic materials including plating treatments, and has excellent hardness and scratch resistance. It is a coating composition.

The photo-curing paint is a paint excellent in productivity and energy saving because it is cured by light and does not require heating and can be cured in a very short time.
In recent years, making use of the characteristics of UV curable paints, not only for woodwork and plastics, but also for metal and metal deposition applications where thermosetting paints such as acrylic resin / melamine resin or urethane resin have been used. Is starting to be used.
The plating of metals and plastics with nickel, tin, chrome, etc. not only prevents oxidation and improves corrosion resistance, but also adds a sense of quality and texture to the surface of metals, etc., such as mobile phones, digital cameras, etc. It is used for information home appliances.
In addition to metal plating, metal deposition is used not only for information appliances such as mobile phones and digital cameras, but also for metal-like parts such as automotive parts such as lamp reflectors and emblems, and containers such as cosmetics. in use. These have a smooth surface on the molding of various plastics such as acrylonitrile-butadiene-styrene copolymer (ABS) resin, polycarbonate (PC) resin, polyethylene terephthalate (PET) resin, fiber reinforced composite material (FRP), etc. An undercoat for coating is applied, and a metal such as aluminum or tin is vacuum-deposited thereon, and a top coat is applied thereon.
These top coats are applied to impart design properties such as gloss and luxury, and to impart hardness and scratch resistance to metals including plating and metal-deposited surfaces.
Not only members with a clear paint applied to a metallic glossy surface but also colored members may be required due to diversification of consumer needs. In that case, two-component urethane paint or lacquer paint is applied as a colored layer to color the metal surface of metal including metal plating, metal vapor deposition or metal plating, in order to improve hardness and wear resistance. The UV paint is applied on the colored layer. Since the same UV-curable coating is required to be applied not only to metal and metal-deposited surfaces, but also to the top coat of the colored layer, the UV-curable coating meets the required performance for adhesion and water resistance to the colored layer. Is desired.

Conventionally, a two-component mixed-curing type paint in which a urethane resin as described above is used as a cross-linking agent and an acrylic resin, a polyester resin, etc. are blended as a top coating material for plating or metal deposition has been mainly used. When UV curable coatings are applied to metal or metal-deposited surfaces, the adhesion is poor compared to general two-component urethane curable coatings, which causes poor water resistance and cannot be used. I had it.
Patent Documents 1 and 2 use a phosphoric acid group-containing (meth) acrylate compound and an alkoxymethyl (meth) acrylamide compound, but as a top coating, the amount of the phosphoric acid group-containing (meth) acrylate compound is large. , Its adhesion and water resistance are insufficient. Patent Document 3 uses a polyfunctional monomer containing a hydroxyl group, but the hydroxyl group is consumed in the esterification reaction, and the residual amount of the hydroxyl group is very small. Therefore, the adhesion is insufficient.
JP-A-6-313127 JP 2002-194013 A JP 2002-284832 A

  In view of the above-mentioned present situation, the present invention can be suitably applied to a metal including a plating treatment and a colored layer applied on a metal-deposited surface or metal on various plastic molded bodies, and has excellent adhesion. And a photocurable coating composition capable of obtaining a cured coating film having excellent hardness and scratch resistance.

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. The present invention is a photocuring comprising a phosphoric acid group-containing (meth) acrylate compound (a1), a hydroxyl group-containing acrylic resin (a2), a hydroxyl group-containing polyfunctional (meth) acrylate compound (a3), and a photoinitiator (a5). Type coating composition. That is,
[1] A phosphoric acid group-containing (meth) acrylate compound (a1), a hydroxyl group-containing acrylic resin (a2), a hydroxyl group-containing polyfunctional (meth) acrylate compound (a3), and a photoinitiator (a5), ) And (a3), 0.1 to 0.9 parts by weight of (a1) is contained with respect to 100 parts by weight in total.
[2] The photocurable coating composition according to [1], further comprising a compound (a4) having an ethylenically unsaturated double bond.
[3] The photocurable coating composition according to [1] or [2], wherein the phosphoric acid group-containing (meth) acrylate compound (a1) is a phosphoric acid (meth) acrylate having a (meth) acryloyloxy group.
[4] The photocurable coating composition according to any one of [1] to [3], wherein the hydroxyl group-containing acrylic resin (a2) has a hydroxyl value of 1 to 200 mgKOH / g and a molecular weight of 5,000 to 100,000. .
[5] The photocurable coating composition according to any one of [1] to [4], wherein the hydroxyl group-containing polyfunctional (meth) acrylate compound (a3) is a 2 to 5 functional (meth) acrylate compound.

  According to the present invention, a cured coating film that exhibits excellent adhesion, and has excellent hardness and scratch resistance, on a metal including a plating treatment and a metal vapor-deposited surface applied on various plastic molded bodies. Obtainable. In the present invention, a coating film can be obtained by photocuring which has high productivity and energy saving.

The present invention will be described in detail below.

<< Phosphate group-containing (meth) acrylate compound (a1) >>
The phosphoric acid group-containing (meth) acrylate (a1) component is composed of a hydroxyl group-containing acrylic resin (a2) and a hydroxyl group-containing polyfunctional (meth) acrylate compound (a3) from the viewpoint of adhesion to a substrate and water resistance. (A1) is in the range of 0.1 to 0.9 parts by weight, preferably 0.1 to 0.45 parts by weight with respect to 100 parts by weight in total.

Specifically, the phosphoric acid group-containing (meth) acrylate (a1) is composed of (meth) acryloyloxyethyl phosphate, di (meth) acryloyloxyethyl phosphate, tri (meth) acryloyloxyethyl phosphate, caprolactone-modified phosphorus Examples include phosphoric acid group-containing (meth) acrylates having at least one (meth) acryloyloxy group in one molecule such as acid (meth) acryloyloxyethyl. Among these, phosphoric acid (meth) acryloyloxyethyl is preferable in order to improve adhesion to a metal, a metal vapor deposition film, and a coloring layer coating agent.
Here, description like methyl (meth) acrylate shows methyl acrylate and / or methyl methacrylate, and the following (meth) has the same meaning.

<< Hydroxyl group-containing acrylic polymer (a2) >>
The acrylic polymer (a2) in the present invention is obtained by copolymerizing a monomer (b1) containing a hydroxyl group with another monomer (b2) in order to develop excellent adhesion and scratch resistance. Can be obtained by:
Examples of the hydroxyl group-containing monomer (b1) include hydroxyl group-containing vinyls such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate.

  Other monomers (b2) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, n -Amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) ) Acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate Alkyl (meth) acrylates such as dicyclopentenyloxyethyl (meth) acrylate; and aromatic vinyls such as styrene, 2-methylstyrene, t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene and divinylbenzene Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and anhydrides thereof; vinyl esters such as vinyl acetate and vinyl propionate; halogenation such as vinylidene chloride and vinylidene fluoride Vinylidenes; N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (methacrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dibutyla Aminoalkyl (meth) acrylates such as noethyl (meth) acrylate and N, N-dihydroxyethylaminoethyl (meth) acrylate; unsaturated sulfonic acids such as styrene sulfonic acid and sodium styrene sulfonate; 2-methoxyethyl acrylate, 2 -Ethoxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, acrylonitrile, methacrylonitrile, vinyl chloride, ethylene, propylene, isoprene, butadiene, chloroprene, vinyl pyrrolidone, 1,2,2,6,6-pentamethyl-4 -Piperidyl (meth) acrylate, 2,2,6,6-tetramethyl-4-piperidyl (meth) acrylate, 2- (2'-hydroxy-5'-methacryloyloxyethyl tyrp) Sulfonyl) -2H- benzotriazole.

Among these, as other monomer (b2), in order to obtain good adhesion, alkyl such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, etc. has 4 or less carbon atoms The alkyl (meth) acrylates are preferably used.
The acrylic polymer (a2) in the present invention usually contains a hydroxyl group having a hydroxyl value of 1 to 200 mgKOH / g, preferably 10 to 180 mgKOH / g, more preferably 30 in order to develop adhesion and hardness. It contains ˜120 mg KOH / g hydroxyl group.

  In addition, the molecular weight of the acrylic polymer (a2) in the present invention is usually 5 in order to express good hardness and scratch resistance of the coating film, and to make the viscosity of the coating composition within a paintable range. It is 10,000-100,000, Preferably it is 10,000-60,000, More preferably, it is 20,000-30,000.

<< Hydroxyl-containing polyfunctional (meth) acrylate compound (a3) >>
The hydroxyl group-containing polyfunctional (meth) acrylate compound (a3) in the present invention is blended in order to exhibit excellent wear resistance and hardness.
Specific examples of the compound (a3) component include dipentaerythritol penta (meth) acrylate, pentaerythritol tri (meth) acrylate, ethylene oxide modified trimethylolpropane di (meth) acrylate, neopentyl glycol modified trimethylolpropane di ( (Meth) acrylate. Dipentaerythritol pentaacrylate and pentaerythritol triacrylate are preferable. Moreover, it is preferable that it is a 2-5 functional (meth) acrylate compound.
Here, the weight ratio of (a1) and (a2) is (a1) / (a2) = 20-80 / 80-20 parts by weight from the viewpoint of the hardness and abrasion resistance of the coating film.

<< Compound (a4) having an ethylenically unsaturated double bond >>
The compound (a4) having an ethylenically unsaturated double bond in the present invention is a compound having an acrylic group.
For example, ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, dipropylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, hydroxyethyl (meth) acrylate, 2- Hydroxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dicyclopentenyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, dimethylol Tricyclodecane di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyp Pyrene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, bis ((meth) acryloxyethyl) bisphenol A, trimethylolpropane tri (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, propylene Oxide-modified trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, ethylene oxide-modified glycerin tri (meth) acrylate, propylene oxide-modified glycerin tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, part of these (meth) acrylates Polyfunctional (meth) acrylate substituted with an alkyl group and ε- caprolactone, acryloyl morpholine with other active double bond, triethylene glycol divinyl ether, hydroxyethyl divinyl ether, styrene, divinylbenzene, and the like.

  Furthermore, polyester poly (meth) acrylates obtained by reaction of polybasic acids such as phthalic acid and adipic acid, polyhydric alcohols such as ethylene glycol and butadiol, and (meth) acrylic acid compounds; epoxy resins and (meth ) Epoxy poly (meth) acrylate obtained by reaction with acrylic acid compound; polysiloxane poly (meth) acrylate obtained by reaction of polysiloxane and (meth) acrylic acid compound; urethane acrylate and the like.

Urethane acrylate is synthesized by performing polymerization by addition reaction of a diisocyanate compound and a glycol species, and further adding (meth) acrylate having an active hydrogen group such as a hydroxyl group to the remaining isocyanate group. Examples of the diisocyanate compound include hexamethylene diisocyanate (HDI), 1,3-diisocyanatomethylcyclohexane (H6 XDI), isophorone diisocyanate (IPDI), and toluene diisocyanate (TDI). Examples of the glycol species include polyester polyols such as polycaprolactone polyol; polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol; polycarbonate polyols such as polyhexamethylene carbonate glycol; ethylene glycol, propanediol, 1 , 4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexane dimethanol and the like. Furthermore, examples of the (meth) acrylate having an active hydrogen group such as a hydroxyl group include hydroxyl group-containing vinyls such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. is there.
Neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, tripropylene glycol di (meth) acrylate, dipentaerythritol Hexa (meth) acrylate is preferably used.

  The addition amount of the compound (a4) having an ethylenically unsaturated double bond is an optional component, but from the viewpoints of viscosity adjustment and coating film properties, the hydroxyl group-containing acrylic resin (a2) and the hydroxyl group-containing polyfunctional (meta ) 0 to 50 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight in total with the acrylate compound (a3).

<< Photoinitiator (a5) >>
The photoinitiator (a5) of the present invention is a compound capable of generating radicals by ultraviolet rays, electron beams, radiation, etc., and specific examples thereof include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether. , Benzoin isobutyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4 -Bis (dimethylaminobenzophenone), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 1- (4-isopropylphenyl) -2-hydroxy Carbonyl compounds such as 2-methylpropan-1-one; sulfur compounds such as tetramethylthiuram disulfide; azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile; anthraquinones such as 2-ethylanthraquinone Peroxide compounds such as benzoyl peroxide and ditertiary butyl peroxide; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, etc. An acyl phosphine oxide compound can be mentioned. Examples of preferred initiators include benzophenone, methylphenylglyoxylate, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine These are oxides, and these may be used alone or in combination of two or more.

  The ratio of a photoinitiator (a5) is 0.1-10 weight part normally with respect to 100 weight part of total of (a1)-(a4), Preferably it is 1-8 weight part.

  In the photocurable resin composition of the present invention, an organic solvent, a polymerization inhibitor, an ultraviolet absorber, a light stabilizer, an antioxidant, an anti-yellowing agent, a dye, a pigment, a leveling agent, an antifoaming agent, a thickener, Various additives such as an anti-settling agent, an antistatic agent, an antifogging agent, an anti-fogging agent, a wetting agent, a dispersing agent, an anti-dripping agent, and a coupling agent can be contained.

There is no limitation on the method of applying such a photocurable coating composition to a substrate, and it is carried out by a conventional method such as spray coating, dip coating, spin coating or brush coating.
In order to express sufficient hardness and good adhesion without generating cracks in the coating, it is preferable that the film thickness of the cured coating is 5 to 30 μm as the coating amount.
As a means for curing the coating applied to the substrate, a known method of irradiating active energy rays such as ultraviolet rays, electron beams, and radiation can be used. An ultraviolet lamp is generally used.
Specific examples include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a gallium lamp, a metal halide lamp, and ultraviolet rays such as sunlight. The irradiation atmosphere may be air or an inert gas such as nitrogen or argon.
Examples of the metal treatment include nickel, chromium, zinc and the like.
Metal vapor deposition is performed using methods such as vapor deposition, sputtering, ion plating, and plating, but vacuum vapor deposition is more preferable from the viewpoint of productivity.
Examples of the metal to be deposited include Al, Zn, Cu, Ag, Au, Sn, Ni, and alloys thereof. As a plastic used as a base material for metal vapor deposition, various synthetic resin molded products are exemplified.

Specific examples of synthetic resin molded products include acrylonitrile-butadiene-styrene copolymer (ABS) resin, polycarbonate (PC) resin, polyethylene terephthalate (PET) resin, fiber reinforced composite material (FRP), polyester resin, polymethylmethacrylate resin, Examples include polystyrene resin, polyolefin resin, acrylonitrile-styrene copolymer resin, polyamide resin, polyarylate resin, polymethacrylimide resin, and polyallyl diglycol carbonate resin. Synthetic resin molded products include sheet-shaped molded products, film-shaped molded products, and various injection molded products made of these resins.
When coloring metal or metal-deposited surfaces including plating, the colored layer can be acrylic lacquer, or a two-component urethane curable paint with a combination of acrylic polyol and urethane resin, or a hydroxyl group-containing acrylic resin, polyester resin and curing agent can be melamine. Resin baking paint.

  The coating film obtained by the photocurable resin composition of the present invention exhibits excellent adhesion to the metal-plated metal and the surface of metal-deposited on various plastic moldings, and has hardness and resistance. Since it has excellent scratch resistance, it can be suitably used in applications such as automobile parts, electrical appliance parts, containers, and building materials.

Hereinafter, the synthesis examples and examples of the present invention will be described. However, the present invention is not limited to these examples.
[Synthesis Example 1]
<Synthesis Example (Ac1) of Acrylic Polymer (a2)>
A mixed solution of 85 g of methyl methacrylate (MMA), 14 g of 2-hydroxyethyl methacrylate (HEMA), 1 g of methacrylic acid (MAA) and 1 g of azobisisobutyronitrile was charged with 85 g of butyl acetate and 37 g of methyl isobutyl ketone (MIBK). The reaction vessel was added dropwise at 100 ° C. over 4 hours under an air stream.
Furthermore, in order to maintain 100 degreeC and to complete polymerization, 0.2 g of azobisisobutyronitrile was added twice every hour.
The mixture was cooled 3 hours after the completion of the dropping to obtain an acrylic polymer (a2) solution (Ac1) having a nonvolatile content of 45% and a weight average molecular weight of 25,000.

[Synthesis Example 2]
<Synthesis Example (Ac2) of Acrylic Polymer (a2)>
The mixing ratio of styrene and the acrylic monomer was changed as shown in Table 1, and an acrylic polymer (a2) solution (Ac2) was obtained by the same operation as in Synthesis Example 1.

[Example 1]
As phosphoric acid group-containing (meth) acrylate compound (a1), 0.3 parts of phosphoric acid group-containing methacrylate Kayamer PM-2, and acrylic polymer (Ac1) of Synthesis Example 1 as hydroxyl group-containing acrylic resin (a2) 89 parts, 55 parts of Aronics M305 (pentaerythritol triacrylate manufactured by Toa Gosei Co., Ltd.) as the hydroxyl group-containing polyfunctional (meth) acrylate compound (a3), and NK as the compound (a4) having an ethylenically unsaturated double bond 5 parts of ester A-NPG (Neopentyl glycol diacrylate manufactured by Shin-Nakamura Chemical Co., Ltd.), 5 parts of Irgacure 184 (photoinitiator manufactured by Ciba Specialty) as photoinitiator (a5), and methyl ethyl ketone as diluted thinner 51 parts were mixed to obtain a photocurable coating composition.

[Examples 2 to 6]
A phosphoric acid group-containing (meth) acrylate compound (a1), a hydroxyl group-containing acrylic resin (a2), a hydroxyl group-containing polyfunctional (meth) acrylate compound (a3), and a compound (a4) having an ethylenically unsaturated double bond; The type and mixing ratio of the photoinitiator (a5) were changed as shown in Table 1, and a photocurable coating composition was obtained by the same operation as in Example 1.

[Comparative Examples 1-4]
A phosphoric acid group-containing (meth) acrylate compound (a1), a hydroxyl group-containing acrylic resin (a2), a hydroxyl group-containing polyfunctional (meth) acrylate compound (a3), and a compound (a4) having an ethylenically unsaturated double bond; The type and mixing ratio of the photoinitiator (a5) were changed as shown in Table 1, and a photocurable coating composition was obtained by the same operation as in Example 1.
[Evaluation Method] The photocurable coating composition obtained above was tested by the following method.
The results are shown in Table 2.

<Measurement of molecular weight>
The molecular weight of the acrylic polymer (a2) was measured with a RI detector using GPC (Shodex GPC SYSTEM-11: Showa Denko).

<Measurement of hydroxyl value>
The hydroxyl value was evaluated according to JIS K0070.

<Base material>
As the chrome-plated steel plate, JIS G3141 chrome-plated steel plate (abbreviated as Cr) was used. A base material (abbreviated as Al1) on which an ABS plate was coated with an undercoat of an ultraviolet curable paint or a two-component urethane curable paint and aluminum was deposited by a vacuum deposition method was used as a deposition base material. A base material (Al2 abbreviated) coated with a paint in which an acrylic polyol mixed with a pigment and a urethane resin mixed with a vapor deposition base material Al1 was used as a deposition base with a colored layer.

<Ultraviolet curing conditions>
Each substrate was coated with a photocurable coating composition so as to have a thickness of 10 μm with a bar coater, dried at 60 ° C. × 1 min, and then irradiated with an ultraviolet irradiation device having three 100 w / cm high-pressure mercury lamps at an irradiation distance of 10 cm. Ultraviolet rays were irradiated at a line speed of 10 m / min.
The test piece thus obtained was subjected to subsequent tests.

<Adhesion>
The adhesion was evaluated by a cross cut test (JIS K5600-5-6).

<Hot water resistance>
The test piece was immersed in warm water of 85 ° C. for 4 hours, and “O” indicates that the appearance did not change, “Δ” indicates that the coating film became slightly white, and “X” indicates that the coating film became completely white.

<Hardness>
The pencil hardness was evaluated according to (JIS K5600-5-6).
Practically, it is higher than HB.

<Abrasion resistance>
The change in appearance was examined with a CS-10F wear wheel at a load of 250 g and 50 revolutions by the Taber abrasion test method (JIS K5600-5-9).
Good appearance, ◎, scratches in the coating film are very small, those in which the coating film is scratched and whitened, and those in which the coating film is scratched and the metal is completely lost Was marked with x.
[Evaluation results]

<Table 1 footnote> All the numerical values of the formulation in Table 1 represent parts by weight.
MMA: methyl methacrylate, ST: styrene, HEMA: 2-hydroxyethyl methacrylate, MAC: methacrylic acid, MIBK: methyl isobutyl ketone

<Table 2 footnote> All the numerical values of the formulation in Table 2 represent parts by weight.
Phosphoric acid group-containing (meth) acrylate compound (a1) Kayamar PM-2: [Nippon Kayaku Co., Ltd. ethylene oxide-modified phosphate methacrylate], hydroxyl group-containing polyfunctional (meth) acrylate compound (a3) Aronix M-305 : [Pentaerythritol triacrylate manufactured by Toa Gosei Co., Ltd.], Aronix M-403: [Dipentaerythritol hexaacrylate pentaerythritol triacrylate / Dipentaerythritol pentaacrylate pentaerythritol triacrylate produced by Toa Gosei Co., Ltd. = 1 / 1], compound having ethylenically unsaturated double bond (a4) NK ester A-NPG: [Neopentyl glycol diacrylate manufactured by Shin-Nakamura Chemical Co., Ltd.], photoinitiator (a5) Irgacure 184: (Ciba・ Specialty 1-hydroxy-cyclohexyl-phenyl-ketone from Mical)

Claims (5)

A phosphoric acid group-containing (meth) acrylate compound (a1), a hydroxyl group-containing acrylic resin (a2), a hydroxyl group-containing polyfunctional (meth) acrylate compound (a3), and a photoinitiator (a5), (a2) and ( A photocurable coating composition comprising 0.1 to 0.9 parts by weight of (a1) with respect to 100 parts by weight in total with a3). The photocurable coating composition according to claim 1, further comprising a compound (a4) having an ethylenically unsaturated double bond. The photocurable coating composition of Claim 1 or 2 whose phosphoric acid group containing (meth) acrylate compound (a1) is phosphoric acid (meth) acrylate which has a (meth) acryloyloxy group. The photocurable coating composition according to any one of claims 1 to 3, wherein the hydroxyl group-containing acrylic resin (a2) has a hydroxyl value of 1 to 200 mgKOH / g and a molecular weight of 5,000 to 100,000. The photocurable coating composition according to any one of claims 1 to 4, wherein the hydroxyl group-containing polyfunctional (meth) acrylate compound (a3) is a 2 to 5 functional (meth) acrylate compound.