KR102419836B1 - UV Curable Coating Composition - Google Patents

Abstract

The present invention relates to an ultraviolet curable coating composition excellent in iodine resistance.

Description

UV Curable Coating Composition {UV Curable Coating Composition}

The present invention relates to an ultraviolet curable coating composition excellent in iodine resistance.

Since the flooring material is exposed to the external environment which is easy to discolor or pollute after construction, it is common to form a coating layer on the surface of the flooring material to prevent this and improve the appearance. In the case of the most widely used PVC flooring, a technology is used to secure the scratch resistance and stain resistance of the flooring material by coating the surface with a thermosetting resin or wax. For example, Korean Patent No. 10-1335571 discloses a urethane-based paint composition for flooring.

However, there is a problem that the surface hardness of the flooring material surface-treated with the conventional coating composition is not sufficient. In addition, conventional UV-curable paints to which solvents are applied have increased viscosity during operation, which reduces the iodine resistance, stain resistance, and adhesion of the coating film, increases gloss, and generates odor due to volatile organic compounds (VOC). there is a problem with

The present invention provides a UV-curable coating composition capable of forming a coating film having improved odor and increased viscosity during operation, and excellent iodine resistance, stain resistance, adhesion, gloss, scratch resistance, and the like.

The present invention is a urethane (meth) acrylate oligomer of 6 or more functional; polyfunctional (meth)acrylate monomers including trifunctional or more (meth)acrylate monomers, bifunctional (meth)acrylate monomers, and bifunctional or more alkoxylated (meth)acrylate monomers; And it provides an ultraviolet curable paint composition comprising a photoinitiator.

The coating composition of the present invention uses a mixture of a urethane (meth)acrylate oligomer with 6 or more functions, a (meth)acrylate monomer with 3 or more functions, a bifunctional (meth)acrylate monomer, and an alkoxylated (meth)acrylate monomer with 2 or more functions. By doing so, it is possible to form a coating film having excellent iodine resistance and excellent stain resistance, adhesion, gloss, scratch resistance, and the like. In addition, the paint composition of the present invention is a solvent-free paint, and can solve the problems of odor, volatile organic substances, and viscosity increase generated during the painting operation of the existing solvent-type paint. The coating composition of the present invention may be used as a coating material for surface coating of a flooring material (eg, PVC flooring material).

Hereinafter, the present invention will be described in detail. However, it is not limited only by the following content, and each component may be variously modified or selectively mixed as needed. Accordingly, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

As used herein, "(meth)acrylate" refers to acrylate and methacrylate, and "polymerizable functional group" refers to a group involved in a polymerization reaction, such as a (meth)acrylate group. As used herein, “weight average molecular weight” is measured by a conventional method known in the art, and may be measured by, for example, a gel permeation chromatograph (GPC) method. In addition, "viscosity" is measured by a conventional method known in the art, for example, can be measured by a Brookfield (Brookield) rotating spindle method (25 ℃, 50rpm).

The UV-curable paint composition according to the present invention includes a urethane (meth)acrylate oligomer having 6 or more functions; polyfunctional (meth)acrylate monomers including trifunctional or more (meth)acrylate monomers, bifunctional (meth)acrylate monomers, and bifunctional or more alkoxylated (meth)acrylate monomers; and photoinitiators. The coating composition according to the present invention may further include additives such as adhesion promoters, dispersants, and surface control agents commonly used in the field of UV-curable coatings, if necessary.

More than 6 functional urethane (meth)acrylate oligomer

In the UV-curable paint composition of the present invention, the urethane (meth)acrylate oligomer having 6 or more functions has at least 6, as another example 6 to 10, as another example 6 to 8 polymerizable functional groups that are polymerizable unsaturated groups. It is a urethane (meth)acrylate oligomer. The oligomer is a main component of the dry coating film, and can improve iodine resistance, stain resistance, adhesion, and the like.

The 6-functional or more urethane (meth)acrylate oligomer may be a 6-functional or more aliphatic urethane (meth)acrylate oligomer. In the case of using an aliphatic urethane (meth)acrylate oligomer having 6 or more functions, excellent physical properties of the paint, such as yellowing prevention, can be advantageously secured.

The aliphatic urethane (meth)acrylate oligomer having 6 or more functionalities contains an unsaturated group capable of polymerization with a bifunctional aliphatic isocyanate compound (eg, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, etc.) per molecule. It can be prepared by reaction of a hydroxy acrylate monomer containing three or more (eg, pentaerythritol triacrylate, dipentaerythritol triacrylate, etc.).

Non-limiting examples of the urethane (meth)acrylate oligomer having more than 6 functional properties include PU610 of Miwon Corporation, Ebecryl 1290, 5129 of Cytec, U400 of Bayer, DM 87A of Double Bond Chemical, etc. or two or more of them may be used in combination.

The 6-functional or more urethane (meth)acrylate oligomer has a weight average molecular weight (Mw) of 1,000 to 3,000 g/mol, for example, 1,500 to 2,500 g/mol, and a viscosity (25°C) of 50,000 to 150,000 cps, for example For example, it may be 85,000 to 120,000 cps. When the weight average molecular weight (Mw) of the 6-functional or higher urethane (meth)acrylate oligomer is less than 1,000 g/mol, the viscosity is too low, the iodine resistance and gloss of the coating film may be reduced, and when it exceeds 3,000 g/mol Since the crosslinking density is greatly increased, the elasticity of the coating film may be lowered, and iodine resistance, stain resistance and scratch resistance may be deteriorated. In addition, when the viscosity (25° C.) of the 6-functional or higher urethane (meth)acrylate oligomer is less than 50,000 cps, the viscosity is too low, so that the coating film is not formed or the adhesion and iodine resistance of the coating film may be reduced, exceeding 150,000 cps In this case, the paint workability may be deteriorated and the appearance of the coating film may be deteriorated.

If necessary, the urethane (meth)acrylate oligomer having 6 or more functions may be mixed with a reactive oligomer, for example, a polyester (meth)acrylate oligomer. In this case, the hardenability, moisture resistance, heat resistance cycle resistance, heat resistance of the coating film may be improved, and the leveling property and workability of the composition and adhesion and flexibility of the coating film may be further improved.

The content of the 6-functional or higher urethane (meth)acrylate oligomer may be in the range of 15 to 45 wt%, for example, 20 to 30 wt%, based on the total weight of the coating composition. When the content of the 6-functional or higher urethane (meth)acrylate oligomer is less than 15% by weight, the viscosity is low, the crosslinking density is lowered, and heat resistance and adhesion may be reduced. If it exceeds 45% by weight, the viscosity of the composition is high The property may deteriorate and the appearance of the coating film may be deteriorated.

Polyfunctional (meth)acrylate monomer

In the ultraviolet curable coating composition of the present invention, the polyfunctional (meth)acrylate monomer is an auxiliary component of the dry coating film, and while improving the flowability, leveling property and workability of the composition, iodine resistance, stain resistance, and adhesion of the coating film improve sex. In particular, the polyfunctional (meth)acrylate monomer replaces the solvent applied to the conventional iodine-resistant paint, increases the hardness and cure density of the coating film, increases the viscosity during operation, and improves the problem of VOC and odor can be effective.

The polyfunctional (meth)acrylate monomer may include a trifunctional or higher (meth)acrylate monomer, a bifunctional (meth)acrylate monomer, and a bifunctional or higher alkoxylated (meth)acrylate monomer.

Trifunctional or higher (meth)acrylate monomer

The trifunctional or more (meth)acrylate monomer is a (meth)acrylate monomer having three or more, for example, 3 to 6, another example 3 or 4 polymerizable functional groups that are unsaturated groups that can be polymerized, the composition It plays a role in improving the adhesion of the coating film while improving the flowability, leveling property and workability of the film.

Non-limiting examples of the trifunctional or higher (meth)acrylate monomer include trifunctional (meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate; tetrafunctional (meth)acrylate monomers such as pentaerythritol tetra(meth)acrylate and ditrimethylolpropane tetra(meth)acrylate; There are dipentaerythritol poly(meth)acrylates, and these may be used alone or in combination of two or more. For example, the trifunctional or more (meth)acrylate monomer may be a trifunctional (meth)acrylate monomer, such as pentaerythritol tri(meth)acrylate.

The trifunctional or more (meth)acrylate monomer may have a molecular weight of 100 to 500 g/mol, for example, 200 to 400 g/mol, and a viscosity (25° C.) of 800 to 2,000 cps, for example, 1,000 to It may be 1,800 cps. When the molecular weight of the trifunctional or higher (meth)acrylate monomer is less than 100 g/mol, crosslinking efficiency and intermolecular bonding strength may be lowered, so that iodine resistance and heat resistance may be reduced. If it exceeds 500 g/mol, the curing reaction is delayed and adhesion may deteriorate. In addition, when the viscosity (25°C) of the trifunctional or higher (meth)acrylate monomer is less than 800 cps, the viscosity is too low, so that the coating film is not formed or the adhesion and heat resistance of the coating film may be reduced. The workability may be deteriorated and the appearance may be deteriorated.

The content of the trifunctional or higher (meth)acrylate monomer may be in the range of 10 to 50% by weight, for example, 20 to 40% by weight, based on the total amount of the coating composition. When the content of the trifunctional or higher (meth)acrylate monomer is less than 10% by weight, the viscosity is low and the crosslinking density is lowered, so that the degree of crosslinking, adhesion and painting workability may be reduced, and if it exceeds 50% by weight, the viscosity is too high High, the flexibility of the coating film may be lowered, and the gloss may be lowered.

Bifunctional (meth)acrylate monomer

The bifunctional (meth)acrylate monomer is mixed with the trifunctional or higher (meth)acrylate monomer, and serves to replace the solvent and improve the hardness and curing density of the coating film.

The bifunctional (meth) acrylate monomer is, for example, hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, glycerin di (meth) acrylate, diethylene glycol di (meth) acrylate, Alkylene glycol di(meth)acrylates such as triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, etc. It may be a monomer. For example, the bifunctional (meth)acrylate monomer may be 1,6-hexanediol diacrylate.

The bifunctional (meth)acrylate monomer may have a molecular weight of 50 to 450 g/mol, for example, 150 to 350 g/mol, and a viscosity (25° C.) of 1 to 30 cps, for example, 5 to 15 It can be cps. If the molecular weight of the bifunctional (meth)acrylate monomer is less than 50 g/mol, the crosslinking efficiency may be lowered, so that iodine resistance and appearance may be deteriorated. Appearance, adhesion, and heat resistance may be deteriorated due to poor elasticity. In addition, when the viscosity (25°C) of the bifunctional (meth)acrylate monomer is less than 1 cps, the viscosity is too low and the heat resistance of the coating film may be lowered. may be lowered.

The content of the bifunctional (meth)acrylate monomer may be in the range of 10 to 50% by weight, for example, 20 to 40% by weight, based on the total amount of the coating composition. When the content of the bifunctional (meth)acrylate monomer is less than 10% by weight, the viscosity of the coating composition may increase and flowability and leveling properties may decrease, and if it exceeds 50% by weight, the viscosity of the composition is very low and curability As a result, workability and adhesion may be deteriorated.

Bifunctional or higher alkoxylated (meth)acrylate monomer

The bifunctional or more alkoxylated (meth)acrylate monomer is an alkoxylated (meth)acrylate monomer having two or more, for example, two to five, polymerizable functional groups that are unsaturated groups that can be polymerized, and the above-mentioned trifunctional or more Mixed with a (meth)acrylate monomer and a bifunctional (meth)acrylate monomer, it serves to replace the solvent and improve the hardness and curing density of the coating film.

In the bifunctional or higher alkoxylated (meth)acrylate monomer, the alkoxy group may be, for example, an alkoxy group having 1 to 5 carbon atoms, and in another example, an alkoxy group having 2 or 3 carbon atoms.

The bifunctional or more alkoxylated (meth)acrylate monomer is, for example, ethoxylated polypropylene glycol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acryl acrylate, ethoxylated glycerin tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and ethoxylated pentaerythritol tetra(meth)acrylate. For example, the bifunctional or more alkoxylated (meth)acrylate monomer may be ethoxylated bisphenol A dimethacrylate (bisphenol A (EO) ₂ dimethacrylate).

The bifunctional or more alkoxylated (meth)acrylate monomer may have a molecular weight of 300 to 600 g/mol, for example, 350 to 550 g/mol, and a viscosity (25° C.) of 800 to 1,600 cps, for example, It may be 1,000 to 1,400 cps. When the molecular weight of the bifunctional or more alkoxylated (meth)acrylate monomer is less than 300 g/mol, the viscosity is low, and the heat resistance and cold-and-heat resistance of the coating film may decrease, and when it exceeds 600 g/mol, the crosslinking density increases Appearance, adhesion, heat resistance, etc. may be deteriorated due to poor elasticity of the coating film. In addition, when the viscosity (25° C.) of the bifunctional or higher alkoxylated (meth)acrylate monomer is less than 800 cps, the viscosity is low, so that the coating film is not formed or the iodine resistance and stain resistance of the coating film may be reduced, exceeding 1,600 cps In this case, the paint workability may be deteriorated, and gloss and adhesion may be reduced.

The content of the bifunctional or higher alkoxylated (meth)acrylate monomer may be in the range of 0.5 to 25% by weight, for example, 5 to 15% by weight, based on the total amount of the coating composition. When the content of the bifunctional or more alkoxylated (meth)acrylate monomer is less than 0.5 wt%, curability and crosslinking density are lowered, and thus the strength and adhesion of the coating film may be reduced, and if it exceeds 25 wt%, the viscosity is too high Workability and iodine resistance may be deteriorated.

In the present invention, the trifunctional or more (meth)acrylate monomer, the bifunctional (meth)acrylate monomer and the bifunctional or more alkoxylated (meth)acrylate monomer are 1: 0.5 to 2: 0.05 to 0.75 weight ratio, for example, 1: 0.8 to 1.2: may be mixed in a weight ratio of 0.1 to 0.4. When the monomer is used in the above-mentioned mixing ratio, proper viscosity is maintained and curability is improved, so that physical properties such as iodine resistance, stain resistance, and adhesion of the coating film are improved, and the effect of controlling viscosity and improving odor during operation can be further improved. have.

photoinitiator

In the coating composition of the present invention, the photoinitiator is a component that is excited by ultraviolet (UV) or the like to initiate photopolymerization, and any photoinitiator generally known in the art may be used without limitation.

Non-limiting examples of usable photoinitiators, Irgacure 184, Irgacure 369, Irgacure 651, Irgacure 819, Irgacure 907, benzion alkyl ether (Benzionalkylether), benzophenone (Benzophenone), benzyl dimethyl catal (Benzyl dimethyl katal), hydride Hydroxycyclohexyl phenylacetone, Chloro acetophenone, 1,1-Dichloro acetophenone, Diethoxy acetophenone, Hydroxyacetophenone ), 2-Chloro thioxanthone, 2-ETAQ (2-EthylAnthraquinone), 1-hydroxy-cyclohexyl-phenyl-ketone (1-Hydroxy-cyclohexylphenyl-ketone), 2-hydroxy- 2-methyl-1-phenyl-1-propanone (2-Hydroxy-2-methyl-1-phenyl-1-propanone), 2-hydroxy-1-[4- (2-hydroxyethoxy) phenyl] -2-methyl-1-propanone (2-Hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone), methylbenzoylformate, bis(2,4, 6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and the like. These may be used alone or two or more may be used in combination.

The maximum absorption wavelength of the photoinitiator is not particularly limited as long as it can absorb ultraviolet light, and may be, for example, in the range of 200 to 410 nm.

The content of the photoinitiator may be 0.01 to 10% by weight, for example, 3 to 8% by weight based on the total amount of the coating composition. If the content of the photoinitiator is less than 0.01% by weight, the strength and adhesion of the coating film may be reduced due to reduced curability or non-curing, and wrinkles may occur due to non-curing of the coating film. On the other hand, if the content of the photoinitiator exceeds 10% by weight, it may cause contamination due to unreacted photoinitiator or decrease in adhesion due to low polymerization degree.

additive

The coating composition according to the present invention may further optionally include additives commonly known in the art in addition to the above-described components according to the purpose and environment of use of the coating composition.

For example, the coating composition of the present invention may further include a matting agent. The matting agent serves to control the viscosity and gloss of the coating composition, and is not particularly limited as long as it is known in the art. For example, silica may be used.

In addition, it may further include one or more selected from the group consisting of adhesion promoters, dispersants, surface control agents, UV absorbers, UV stabilizers, leveling agents, defoamers, and color tone agents.

The content of each additive is not particularly limited, and may be, for example, 0.1 to 10% by weight, for example, 2 to 7% by weight, based on the total amount of the coating composition.

There is no particular limitation in the method for preparing the coating composition of the present invention, for example, the above-described urethane (meth)acrylate oligomer, polyfunctional (meth)acrylate monomer, and photoinitiator with other additives as necessary together with a dissolver, a stirrer After being put into mixing equipment, such as, it may be prepared according to a conventional method of mixing at an appropriate temperature (eg, room temperature).

The UV curable paint composition of the present invention can be applied to various substrates, for example, is useful for surface treatment of PVC flooring, but is not limited thereto. According to one example, the UV curable paint composition of the present invention is applied to the surface of a substrate and dried, and then cured under an ultraviolet irradiation dose of less than 3,000 mJ/cm 2 , for example, 2,500 mJ/cm 2 or less (eg 1,500 to 2,500 mJ/cm 2 ). to form a coating layer.

The present invention will be described in more detail with reference to the following examples. However, the following examples are only provided to help the understanding of the present invention, and the scope of the present invention is not limited to the examples in any sense.

[Example 1-11]

According to the composition shown in Table 1 below, the UV curable coating composition of Examples 1-11 was prepared. The usage unit of each component in Table 1 below is weight %.

[Comparative Example 1-9]

According to the composition shown in Table 2 below, the UV curable coating composition of Comparative Examples 1-9 was prepared. The usage unit of each component in Table 2 below is weight %.

Oligomer 1: Hexafunctional aliphatic urethane acrylic oligomer (Mw 1,800 g/mol, viscosity (25℃) 100,000 cps)

Oligomer 2: 6-functional aliphatic urethane acrylic oligomer (Mw 1,300 g/mol, viscosity (25°C) 74,000 cps)

Oligomer 3: hexafunctional aliphatic urethane acrylic oligomer (Mw 2,700 g/mol, viscosity (25°C) 129,000 cps)

Oligomer 4: hexafunctional aliphatic urethane acrylic oligomer (Mw 900 g/mol, viscosity (25°C) 48,000 cps)

Oligomer 5: hexafunctional aliphatic urethane acrylic oligomer (Mw 3,200 g/mol, viscosity (25°C) 158,000 cps)

Oligomer 6: pentafunctional aliphatic urethane acrylic oligomer (Mw 1,600 g/mol, viscosity (25°C) 90,000 cps)

Monomer 1: trifunctional acrylate monomer (Pentaerythritol triacrylate, molecular weight 298 g/mol, viscosity (25°C) 1,400 cps, [MIRAMER M340, Miwon Corporation])

Monomer 2: bifunctional acrylate monomer (1,6-Hexanediol diacrylate, molecular weight 226 g/mol, viscosity (25℃) 10 cps, [MIRAMER M200, Miwon Corporation])

Monomer 3: Bifunctional alkoxylated acrylate monomer (Bisphenol A (EO) ₂ Dimethacrylate, molecular weight 452 g/mol, viscosity (25℃) 1,200 cps, [KOMERATE D020M, KPX])

Photoinitiator 1: 1-Hydroxy-cyclohexyl-phenyl-ketone [Omnirad 481, IGM]

Photoinitiator 2: Methyl benzoyl formate [Darocur MBF, IGM]

Photoinitiator 3: Benzophenone [MICURE BP, Miwon Corporation]

Matter 1: Synthetic amorphous silicon dioxide [NIPSIL E-220A, Tosoh Corporation]

Matter 2: Untreated Thermal Silica [ACEMATT TS-100, Evonik]

Leveling agent 1: Silicone acrylate, [RAD2500, Tego]

Leveling agent 2: Silicone acrylate, [RAD2700, Tego]

[Experimental Example-Physical Property Evaluation]

The physical properties of the UV-curable coating composition prepared according to each Example and Comparative Example and the coating film formed therefrom were carried out according to the following method for measuring physical properties, and the results are shown in Tables 3 and 4 below.

Specimen preparation

Specimens were prepared by coating the paint compositions prepared in each Example and Comparative Example on a PVC flooring (thickness: 10-15 μm), and photocuring (light quantity: 2,000 mJ/cm2, light intensity: 140 mW/cm2) .

Exterior

It was evaluated whether there were defects such as roll marks, dewetting and orange peel by visual observation.

hardenability

Each of the prepared specimens was left at a temperature of 120° C. for 1 hour, and then the appearance was observed.

adherence

A cross cut tape test was performed according to the ASTM D3359 test method.

Iodine resistance

After dropping Chinese iodine on each specimen, the erasability was confirmed after 30 minutes.

stain resistance

Oil-based magic was applied to each specimen, and erasability was confirmed after 5 minutes.

Polish

The gloss of each specimen was measured using a glossmeter (60 degrees).

From the results of Tables 3 and 4, it was confirmed that the coating films formed of the UV-curable coating compositions of Examples according to the present invention were generally superior in physical properties to the coating films formed of the coating compositions of Comparative Examples.

Comparative Examples 1 and 2 were compositions containing urethane (meth)acrylate oligomers having 6 or more functionalities in an amount outside the content range of the present application, and adhesion was poor. Comparative Examples 3 and 4 were compositions containing trifunctional or higher (meth)acrylate monomers in an amount outside the content range of the present application, and exhibited poor curability. Comparative Example 5 was a composition containing a bifunctional or higher alkoxylated (meth)acrylate monomer in an amount outside the content range of the present application, and showed poor appearance and curability. Comparative Examples 6-8 is a composition that does not use a urethane (meth)acrylate oligomer having 6 or more functions, a (meth)acrylate monomer having more than trifunctionality, and an alkoxy (meth)acrylate monomer having more than 2 functional functionality, respectively, and curability, adhesion, The stain resistance and gloss were inferior. Comparative Example 9 was a composition in which a 5-functional urethane (meth)acrylate oligomer was applied instead of a 6-functional or higher urethane (meth)acrylate oligomer, and showed poor appearance and adhesion when forming a coating film.

Claims (5)

Based on the total weight of the coating composition, 15 to 45% by weight of a hexafunctional urethane (meth)acrylate oligomer, 10 to 50% by weight of a trifunctional or more (meth)acrylate monomer, and 10 to 50% by weight of a bifunctional (meth)acrylate monomer , containing 0.5 to 25% by weight of a bifunctional or more alkoxylated (meth)acrylate monomer and 0.01 to 10% by weight of a photoinitiator,
The six-functional urethane (meth)acrylate oligomer has a weight average molecular weight of 1,000 to 3,000 g/mol, and a viscosity (25° C.) of 50,000 to 150,000 cps,
The trifunctional or higher (meth)acrylate monomer is trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylic It is at least one selected from the group consisting of rate and dipentaerythritol poly (meth) acrylate,
The bifunctional (meth) acrylate monomer is hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, glycerin di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and at least one selected from the group consisting of tetraethylene glycol di (meth) acrylate,
The bifunctional or more alkoxylated (meth)acrylate monomer is ethoxylated polypropylene glycol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, ethoxylated at least one selected from the group consisting of glycerin tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and ethoxylated pentaerythritol tetra(meth)acrylate,
The trifunctional or more (meth)acrylate monomer, the bifunctional (meth)acrylate monomer, and the bifunctional or more alkoxylated (meth)acrylate monomer are 1: 0.8 to 1.2: UV curable mixed in a weight ratio of 0.1 to 0.4 paint composition. delete The UV-curable coating composition according to claim 1, wherein the trifunctional or higher (meth)acrylate monomer has a molecular weight of 100 to 500 g/mol and a viscosity (25° C.) of 800 to 2,000 cps. The UV-curable coating composition according to claim 1, wherein the bifunctional (meth)acrylate monomer has a molecular weight of 50 to 450 g/mol and a viscosity (25° C.) of 1 to 30 cps. The UV curable coating composition according to claim 1, wherein the bifunctional or higher alkoxylated (meth)acrylate monomer has a molecular weight of 300 to 600 g/mol and a viscosity (25° C.) of 800 to 1,600 cps.