KR102031049B1 - Hard Coating Composition and Hard Coating Film Using the Same - Google Patents

Abstract

The present invention provides a hard coating composition comprising a benzotriazole copolymer, a polyfunctional urethane (meth) acrylate having a cyclohexyl group, a polyfunctional (meth) acrylate having an ethylene glycol group, a photoinitiator and a solvent, and is formed using the same. It provides a hard coating film and an image display device provided with the hard coating film. The hard coat film according to the present invention exhibits an ultraviolet ray blocking effect and has high hardness and excellent scratch resistance, as well as excellent adhesion, curl and crack characteristics.

Description

Hard Coating Composition and Hard Coating Film Using The Same {Hard Coating Composition and Hard Coating Film Using the Same}

The present invention relates to a hard coating composition and a hard coating film using the same, and more particularly, a hard coating composition having a UV protection effect and excellent hardness, and having flexibility, a hard coating film and the hard coating film formed using the same An image display device provided.

The hard coating film is used for the purpose of surface protection in image display apparatuses, such as a liquid crystal display device, an electroluminescence (EL) display device, a plasma display (PD), and a field emission display (FED: Field Emission Display).

Recently, a flexible display device that can maintain display performance even if it is bent like a paper using a flexible material such as plastic instead of a glass substrate without conventional flexibility has emerged as a next-generation display device. There is a need for a hard-coated film that is not only high and scratch resistant, but also has no curl at the edges of the film during the manufacturing process or use, has adequate flexibility, and does not generate cracks.

In addition, since the hard coating film decomposes and discolors due to continuous UV exposure and becomes brittle, a UV absorber or UV stabilizer is generally added to the hard coating layer, and the addition of the additive hardens due to compatibility problems with the binder resin. Problems such as post-layer separation, lowering of adhesion and lowering of hardness occur.

Korean Patent Laid-Open Publication No. 2009-0089088 discloses a UV absorber including a benzotriazole-based acrylic copolymer having excellent UV blocking effect and excellent dispersibility with a polymer.

However, the ultraviolet absorber has a problem that it is difficult to secure sufficient hardness and flexibility enough to be applied to the flexible display.

Republic of Korea Patent Publication No. 2009-0089088

The present invention is to solve the above problems, one object of the present invention is to provide a hard coating composition that can be used in the manufacture of a hard coating film having a UV protection effect and excellent hardness and flexibility.

Another object of the present invention is to provide a hard coating film formed using the hard coating composition.

Still another object of the present invention is to provide an image display device having the hard coating film.

On the other hand, the present invention provides a hard coating composition comprising a benzotriazole copolymer, a polyfunctional urethane (meth) acrylate having a cyclohexyl group, a polyfunctional (meth) acrylate having an ethylene glycol group, a photoinitiator and a solvent. .

In one embodiment of the present invention, the benzotriazole-based copolymer may be a copolymer of a benzotriazole-based monomer and a monofunctional (meth) acrylate.

In addition, the benzotriazole-based monomer may be a benzotriazole-based (meth) acrylate.

In addition, the monofunctional (meth) acrylate may be a (meth) acrylate having an alkyl group having 1 to 12 carbon atoms.

In one embodiment of the present invention, the polyfunctional urethane (meth) acrylate having a cyclohexyl group can be prepared by condensation reaction between a diisocyanate having a cyclohexyl group and a polyfunctional (meth) acrylate having a hydroxy group.

In one embodiment of the present invention, the polyfunctional (meth) acrylate having an ethylene glycol group is obtained by addition reaction of ethylene oxide to a polyhydric alcohol to obtain a polyfunctional alcohol having an ethylene glycol group, and (meth) acrylic acid to the polyfunctional alcohol. It can be prepared by condensation reaction.

The hard coating composition according to one embodiment of the present invention may further include inorganic nanoparticles.

On the other hand, the present invention provides a hard coating film formed by using the hard coating composition.

On the other hand, the present invention provides an image display device provided with the hard coating film.

The hard coating film formed by using the hard coating composition according to the present invention exhibits a UV protection effect, has a high hardness and excellent scratch resistance, and has excellent adhesion, curl, and crack characteristics, so that the window of the flexible display device can be Can be used effectively.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention relates to a hard coating composition comprising a benzotriazole copolymer, a polyfunctional urethane (meth) acrylate having a cyclohexyl group, a polyfunctional (meth) acrylate having an ethylene glycol group, a photoinitiator and a solvent. will be.

In one embodiment of the present invention, the benzotriazole-based copolymer is a component for imparting UV protection properties to the film to be coated, the polyfunctional urethane (meth) acrylate having a cyclohexyl group and the benzotriazole-based copolymer and 0.1 to 20% by weight based on 100% by weight of the total polyfunctional (meth) acrylate having an ethylene glycol group. If the content is less than 0.1% by weight it may be difficult to exhibit the sunscreen effect, if it exceeds 20% by weight it may be difficult to secure the hardness due to the lowering of the curing density.

The benzotriazole-based copolymer may be a copolymer of a benzotriazole-based monomer and a monofunctional (meth) acrylate.

The benzotriazole-based monomer may be a benzotriazole-based (meth) acrylate, specifically, may be a compound of formula (1).

[Formula 1]

Where

R ₁ is hydrogen or an alkyl group of C ₁ -C ₁₀ ,

R ₂ is a (meth) acryloyl group or a (meth) acryloylalkyl group.

As used herein, an alkyl group of C ₁ -C ₁₀ refers to a straight or branched hydrocarbon having 1 to 10 carbon atoms, for example methyl, ethyl, n-propyl, i-propyl, n-butyl, i -Butyl, t-butyl, n-pentyl, n-hexyl, and the like.

As used herein, a (meth) acryloylalkyl group refers to a functional group in which a (meth) acryloyl group is bonded to carbon of an alkyl group, for example, (meth) acryloylethyl, (meth) acryloylpropyl, (Meth) acryloylbutyl and the like, but are not limited thereto.

The monofunctional (meth) acrylate may be a (meth) acrylate having an alkyl group having 1 to 12 carbon atoms. Specific examples include n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, Ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, pentyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl ( Meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, and the like. Can be used. Among these, n-butyl acrylate, 2-ethylhexyl acrylate, or a mixture thereof is preferable.

The benzotriazole-based copolymer may be further included in a range in which other polymerizable monomers other than the monomers do not inhibit the effects of the present invention, such as 10 wt% or less, preferably 5 wt% or less.

The method for producing the benzotriazole-based copolymer is not particularly limited, and may be prepared using methods such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization, which are commonly used in the art, and solution polymerization is preferable. In addition, a solvent, a polymerization initiator, a chain transfer agent for molecular weight control, and the like, which are usually used in the polymerization, may be used.

In one embodiment of the present invention, the polyfunctional urethane (meth) acrylate having a cyclohexyl group is a component for improving the mechanical properties, particularly the hardness of the film to be coated, the benzotriazole copolymer and cyclohexyl group It may be included in 10 to 70% by weight relative to the total 100% by weight of the polyfunctional urethane (meth) acrylate having a polyfunctional (meth) acrylate having an ethylene glycol group. If less than 10% by weight may have a decrease in mechanical properties, in particular hardness, when greater than 70% by weight may increase the shrinkage force may cause curling, breaking, cracking of the film.

The polyfunctional urethane (meth) acrylate having the cyclohexyl group can be produced by condensation reaction between a diisocyanate having a cyclohexyl group and a polyfunctional (meth) acrylate having a hydroxy group.

The diisocyanate having a cyclohexyl group may be specifically 1,4-cyclohexyl diisocyanate, isophorone diisocyanate, 4,4-dicyclohexyl methane diisocyanate, and the like, but is not limited thereto.

The polyfunctional (meth) acrylate having the hydroxy group may be specifically trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, and the like, but is not limited thereto. no.

In one embodiment of the present invention, the polyfunctional urethane (meth) acrylate having a cyclohexyl group may include at least one member selected from the group consisting of compounds represented by the following Formulas 2-3.

[Formula 2]

[Formula 3]

In one embodiment of the present invention, the polyfunctional (meth) acrylate having the ethylene glycol group is a component for imparting flexibility to the film to be coated, the polyfunctional urethane having a benzotriazole copolymer and a cyclohexyl group (meth 10 to 40% by weight based on 100% by weight of the total weight of the multifunctional (meth) acrylate having an acrylate and an ethylene glycol group. When less than 10% by weight may cause a breakage or cracking of the coating film due to lack of flexibility, when larger than 40% by weight may cause mechanical properties to degrade and surface scratches or pencil hardness decreases.

The polyfunctional (meth) acrylate having the ethylene glycol group can be prepared by addition reaction of ethylene oxide to a polyhydric alcohol to obtain a polyfunctional alcohol having an ethylene glycol group, and condensation reaction of (meth) acrylic acid to the polyfunctional alcohol. .

The polyhydric alcohol may be specifically glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, and the like, but is not limited thereto.

Specific examples of the polyfunctional (meth) acrylate having the ethylene glycol group include trimethylolpropane (EO) ₃ tri (meth) acrylate and trimethylolpropane (EO) ₆ Tri (meth) acrylate, trimethylolpropane (EO) ₉ Tri (meth) acrylate, glycerin (EO) ₃ Tri (meth) acrylate, glycerin (EO) ₆ Tri (meth) acrylate, glycerin (EO) ₉ Tri (meth) acrylate, pentaerythritol (EO) ₄ tetra (meth) acrylate, pentaerythritol (EO) ₈ tetra (meth) acrylate, pentaerythritol (EO) ₁₂ Tetra (meth) acrylate, dipentaerythritol (EO) ₆ hexa (meth) acrylate, dipentaerythritol (EO) ₁₂ hexa (meth) acrylate, dipentaerythritol (EO) ₁₈ hexa (meth) acrylate, and the like. have.

In one embodiment of the present invention, the polyfunctional (meth) acrylate having an ethylene glycol group may include one or more selected from the group consisting of compounds represented by the following formulas (4) to (5).

[Formula 4]

[Formula 5]

In one embodiment of the invention, the photoinitiator can be used without limitation so long as it is used in the art. Type 1 photoinitiators, which generate radicals through the decomposition of molecules due to differences in chemical structure or molecular binding energy, and hydrogen cyclic type 2 photoinitiators, coexist with tertiary amines. Specific examples of Type 1 photoinitiators include 4-phenoxydichloroacetphenone, 4-t-butyldichloroacetphenone, 4-t-butyltrichloroacetphenone, diethoxyacetphenone, 2-hydroxy-2-methyl-1 -Phenylpropane-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-l-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methyl Acetphenones such as propane-1-one, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, and 1-hydroxycyclohexylphenylketone, benzoin, benzoinmethyl Benzoin, such as ether, benzoin ethyl ether, benzyl dimethyl ketal, an acyl phosphine oxide, a titanocene compound, etc. are mentioned. Specific examples of Type 2 photoinitiators include benzophenone, benzoylbenzoic acid, benzoylbenzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzol-4'-methyldiphenyl sulfide, 3,3 '. Benzophenones such as -methyl-4-methoxy benzophenone, thioxanthone, 2-chlorothioxanthone, 2-methyl thioxanthone, 2,4-dimethyl thioxanthone and isopropyl thioxanthone Oxanthone etc. are mentioned. These can be used individually or in combination of 2 or more, respectively. Moreover, Type 1 type photoinitiator and Type 2 type photoinitiator can also be used individually or in combination.

The photoinitiator may be included in 0.1 to 10% by weight based on 100% by weight of the total hard coating composition. If less than 0.1% by weight hardening does not proceed sufficiently, it is difficult to implement the mechanical properties or adhesion of the final coating film, if more than 10% by weight may result in poor adhesion or cracking phenomenon and curl phenomenon due to curing shrinkage.

In one embodiment of the present invention, the solvent can be used without limitation so long as it is used in the art. Specifically, alcohol type (methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol, etc.), ketone type (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, etc.), acetate type (Methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxy acetate, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, propyl cellosolve, etc.), hydrocarbons (normal hexane, normal heptane, benzene, toluene, xyl And the like). The solvents may be used alone or in combination of two or more.

The solvent may be included in 10 to 70% by weight based on 100% by weight of the total hard coating composition. If it is less than 10% by weight, the workability is high due to the high viscosity, and if it is more than 70% by weight, it is difficult to adjust the thickness of the coating film and dry stains may occur, resulting in poor appearance.

The hard coating composition according to one embodiment of the present invention may further include inorganic nanoparticles to further improve mechanical properties.

The inorganic nanoparticles may have an average particle diameter of 1 to 100 nm, preferably 5 to 50 nm. Such inorganic nanoparticles may be uniformly formed in the coating film to improve mechanical properties such as wear resistance, scratch resistance, and pencil hardness. If the particle size is less than the above range, aggregation may occur in the composition to form a uniform coating film and the above effect cannot be expected. On the contrary, if the particle size exceeds the above range, the optical properties of the finally obtained coating film are not only degraded. Rather, a problem occurs that the mechanical properties are lowered.

The material of the inorganic nanoparticles may be a metal oxide, Al ₂ O ₃ , SiO ₂ , ZnO, ZrO ₂ , BaTiO ₃ , TiO ₂ , Ta ₂ O ₅ , Ti ₃ O ₅ , ITO, IZO, ATO, ZnO- One kind selected from the group consisting of Al, Nb ₂ O ₃ , SnO, MgO, and combinations thereof may be used, and Al ₂ O ₃ , SiO ₂ , ZrO ₂ , or the like may be preferably used. The inorganic nanoparticles can be prepared and used directly or commercially available. Commercially available products may be used dispersed in a concentration of 20 to 60% by weight in an organic solvent.

The inorganic nanoparticles may be included in 10 to 60% by weight relative to the total 100% by weight of the hard coating composition. If it is less than 10% by weight may not be sufficient mechanical properties such as wear resistance, scratch resistance, pencil hardness, and if more than 60% by weight may interfere with the curing properties, rather the mechanical properties are lowered, the appearance may be poor.

In addition to the components described above, the hard coating composition according to the embodiment of the present invention may be a component generally used in the art, such as a leveling agent, a heat stabilizer, an antioxidant, a UV absorber, a surfactant, a lubricant, an antifouling agent. And the like may be additionally included.

The leveling agent may be used to impart flatness and coating property of the coating film when the hard coating composition is coated. The leveling agent may be a commercially available leveling agent in the form of silicon, leveling agent in the form of fluorine, leveling agent in the form of acrylic polymer, and the like. -337, BYK-373, BYK-375, BYK-377, BYK-378, TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300, TEGO Rad 2500, 3-4's FC-4430, FC-4432 and the like can be used. The leveling agent may be used in the range of 0.1 to 3% by weight relative to the total 100% by weight of the hard coating composition.

One embodiment of the present invention relates to a hard coat film formed using the hard coat composition described above. Hard coating film according to an embodiment of the present invention is characterized in that the coating layer containing the cured product of the above-described hard coating composition is formed on one side or both sides of the transparent substrate.

As the transparent substrate, any plastic film having transparency can be used. For example, a cycloolefin derivative having a unit of a monomer containing a cycloolefin such as norbornene or a polycyclic norbornene monomer, cellulose (diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl ester cellulose, Propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose), ethylene vinyl acetate copolymer, polyester, polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyether sulfone, polysulfone, polyethylene, polypropylene, Polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, Polyethylene naphthalene , Polycarbonate, polyurethane, and epoxy can be selected and used, and an unoriented, uniaxial or biaxially oriented film can be used.

The thickness of the transparent substrate is not particularly limited, but may be 8 to 1000 μm, specifically 20 to 150 μm. If the thickness of the transparent substrate is less than 8㎛ the strength of the film is lowered and workability is lowered, if the thickness is more than 1000㎛ transparency or the weight of the hard coating film occurs.

Hard coating film according to an embodiment of the present invention can be prepared by applying a hard coating composition of the present invention on one side or both sides of the transparent substrate and cured to form a coating layer.

The hard coating composition according to an embodiment of the present invention is coated on a transparent substrate by appropriately using a known method such as die coater, air knife, reverse roll, spray, blade, casting, gravure, micro gravure, spin coating, etc. Is possible.

After applying the hard coating composition on a transparent substrate, the volatiles are dried by evaporation for 10 seconds to 1 hour, more specifically 30 seconds to 30 minutes at a temperature of 30 to 150 ℃, and then irradiated with UV light To harden. The irradiation amount of the UV light may be specifically about 0.01 to 10J / ㎠, more specifically 0.1 to 2J / ㎠.

At this time, the thickness of the coating layer formed may be specifically 2 to 30um, more specifically 3 to 20um. When the thickness of the coating layer is included in the range can be obtained an excellent hardness effect.

One embodiment of the present invention relates to an image display device provided with the hard coating film described above. For example, the hard coat film of the present invention may be attached to a window of an image display device, particularly a flexible display device.

The hard coat film according to an embodiment of the present invention can be used in reflective, transmissive, semi-transmissive LCD or LCD of various driving methods such as TN type, STN type, OCB type, HAN type, VA type, and IPS type. In addition, the hard coat film according to one embodiment of the present invention can also be used in various image display devices such as a plasma display, a field emission display, an organic EL display, an inorganic EL display, and an electronic paper.

Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples and Experimental Examples. These examples, comparative examples and experimental examples are only for illustrating the present invention, it is apparent to those skilled in the art that the scope of the present invention is not limited thereto.

Production Example  One: Benzotriazole  Preparation of Copolymer

20 parts by weight of n-butyl acrylate (BA), 15 parts by weight of 2-ethylhexyl acrylate, benzotriazole-based methacrylate (R ₁ is hydrogen) And R ₂ is a (meth) acryloylethyl group), and a monomer mixture consisting of 15 parts by weight of methyl ethyl ketone (MEK) was added as a solvent. Then, after purging nitrogen gas for 1 hour to remove oxygen, it was maintained at 70 ℃. After the mixture was uniformly mixed, 0.05 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and reacted for 8 hours to prepare a benzotriazole copolymer.

Production Example  2: Benzotriazole  Preparation of Copolymer

Benzotriazole-based acrylate (R ₁ is methyl, R ₂ is acryloyl group) instead of benzotriazole-based methacrylate (R ₁ is hydrogen, R ₂ is a (meth) acryloylethyl group) A benzotriazole-based copolymer was prepared in the same manner as in Preparation Example 1, except that the compound of Formula 1) was used.

Example  1 to 5 and Comparative example  1 to 4: Hard coating  Preparation of the composition

To the composition of Table 1, a mixture was obtained by mixing a benzotriazole copolymer, a polyfunctional urethane (meth) acrylate having a cyclohexyl group, and a polyfunctional (meth) acrylate having an ethylene glycol group (unit: wt%). .

Then, 30 parts by weight of the obtained mixture, 30 parts by weight of silica inorganic nanoparticles Nanopol 784 (Evonik, 20 nm silica sol diluted with 50% PGMEA), 5 parts by weight of photoinitiator Igacure 184 (BASF), leveling agent BYK- 333 3 parts by weight, methyl ethyl ketone 30 parts by weight, toluene 10 parts by weight were mixed to prepare a hard coating composition.

　
Production Example Formula 2 Formula 3 UA-306H Formula 4 Formula 5 M-340 One 2 Example 1 15 40 20 0 25 0 0 Example 2 15 30 40 0 15 0 0 Example 3 15 40 20 0 0 25 0 Example 4 15 25 30 0 0 30 0 Example 5 15 40 20 0 0 25 0 Example 6 15 30 30 0 0 25 0 Example 7 15 40 20 0 25 0 0 Example 8 15 25 30 0 0 30 0 Comparative Example 1 15 0 0 60 25 0 0 Comparative Example 2 15 40 20 0 0 0 25 Comparative Example 3 15 0 0 60 0 0 25 Comparative Example 4 45 25 0 30 0 0

Compound of Formula 2 (Shin A T & C SOU-1700B)

Compound of Formula 3 (Shin A T & C SOU-1290)

UA-306H (public company)

Compound of Formula 4 (Miwon Specialty Chemical M4004)

Compound of Chemical Formula 5 (Japanese Explosives DPEA126)

M-340 (Miwon Specialty Chemical)

Experimental Example  One:

The hard coating composition prepared in Examples and Comparative Examples was coated on one surface of an optical polyimide film (Mitsubishi Chemical, 100 μm, L-3430) to have a thickness of 20 μm, and then, the resultant was dried at 80 ° C. in an oven. After drying for a minute, a hard coat film was prepared by curing a light quantity of 350mJ / cm 2 in a high pressure mercury lamp.

Physical properties of the prepared hard coat film was measured by the method described below, and the results are shown in Tables 2 and 3 below.

(1) pencil hardness

Pencil hardness was measured using a pencil hardness tester (PHT, Korea Seokbo Science). Pencils were made using Mitsubishi products, and were carried out five times per pencil hardness. If there were two or more gases, it was determined to be defective.

<Evaluation Criteria>

Kis 0: OK

Kiss 1: OK

Kis 2 or higher: NG

(2) Scratch resistance

The scratch resistance was tested by using a steel wool tester (WT-LCM100, Protec Co., Ltd.) for 10 reciprocations at 1 kg / (2 cm × 2 cm). Steel wool used # 0000.

<Evaluation Criteria>

S: 0 scratches

A: 1 to 10 scratches

B: 11-20 scratches

C: 21-30 scratches

D: 31 or more scratches

(3) adhesion

After eleven straight lines were drawn on the coated surface of the film at intervals of 1 mm to make 100 squares, three peel tests were performed using a tape (CT-24, Nichi-Shin, Japan). Three 100 squares were tested and averaged. The adhesion was recorded as follows.

Adhesion = n / 100

n: number of rectangles not peeled off

100: total squares

Therefore, when none was peeled off, it was recorded as 100/100.

(4) curl

The sample cut into a square shape of A4 size (29.7 × 21.0 cm) was placed on a flat glass plate with the coated surface of the film facing up, and the distance from the square glass plate was measured at 25 ° C. and 50% RH. It was set as the measured value.

(5) Crack resistance

In order to evaluate the crackability, the coated film samples cut to 1 cm × 10 cm are placed on the iron bars of each diameter (2φ ~ 10φ), and the coating layer is turned upward to show the smallest diameter without cracks on the surface. It was.

(6) UV  A absorption performance

The spectral absorption spectrum of the film was measured using a spectrophotometer, and the transmittance | permeability in 380 nm was calculated | required, and it determined as follows. The lower the transmittance of 380 nm, the better the UV A absorption performance.

<Evaluation Criteria>

A: less than 20% transmittance

B: transmittance 20% or more but less than 50%

C: transmittance 50% or more but less than 80%

D: transmittance of 80% or more

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Pencil hardness 6H 5H 6H 5H 5H 5H 3H 3H Scratch resistance S S S S S S A A Adhesion 100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/100 curl 3 mm 3 mm 4mm 3 mm 3 mm 4mm 7 mm 8 mm Mandorel 3φ 3φ 3φ 3φ 3φ 3φ 6φ 7φ UV A absorption performance B B B B B B B B

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Pencil hardness B 2B 2B B Scratch resistance B B B B Adhesion 90/100 84/100 85/100 60/100 curl 20 mm 25 mm 30 mm 30 mm Mandorel 10φ 15φ 18φ 18φ UV A absorption performance C C C D

As shown in Tables 2 and 3, the hard coating film prepared using the hard coating composition of Examples 1 to 8 according to the present invention are all hardness, scratch resistance, adhesion, curl properties, crack resistance and UV protection Excellent. On the other hand, the hard coating film prepared using the hard coating composition of Comparative Examples 1 to 4 was confirmed that the hardness, scratch resistance, adhesion, curl properties, crack resistance or UV protection is lowered.

Having described the specific part of the present invention in detail, it is apparent to those skilled in the art that this specific technology is only a preferred embodiment, which is not intended to limit the scope of the present invention. Do. Those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

Therefore, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.

Claims (17)

A benzotriazole copolymer, a polyfunctional urethane (meth) acrylate having a cyclohexyl group, a polyfunctional (meth) acrylate having an ethylene glycol group, a photoinitiator and a solvent,
The polyfunctional (meth) acrylate having the ethylene glycol group is at least one hard coating composition selected from the group consisting of compounds of the following formulas 4 to 5:
[Formula 4]

[Formula 5]

The hard coating composition of claim 1, wherein the benzotriazole-based copolymer is a copolymer of a benzotriazole-based monomer and a monofunctional (meth) acrylate. The hard coating composition of claim 2, wherein the benzotriazole-based monomer is a benzotriazole-based (meth) acrylate. The hard coating composition of claim 2, wherein the benzotriazole-based monomer is a compound of Formula 1
[Formula 1]

Where
R ₁ is hydrogen or an alkyl group of C ₁ -C ₁₀ ,
R ₂ is a (meth) acryloyl group or a (meth) acryloylalkyl group. The hard coating composition of claim 2, wherein the monofunctional (meth) acrylate is a (meth) acrylate having an alkyl group having 1 to 12 carbon atoms. The hard coating composition of claim 1, wherein the polyfunctional urethane (meth) acrylate having a cyclohexyl group is prepared by condensation reaction between a diisocyanate having a cyclohexyl group and a polyfunctional (meth) acrylate having a hydroxy group. The hard coating composition of claim 6, wherein the diisocyanate having a cyclohexyl group is 1,4-cyclohexyl diisocyanate, isophorone diisocyanate or 4,4-dicyclohexylmethane diisocyanate. 7. The hard coating composition of claim 6, wherein the polyfunctional (meth) acrylate having a hydroxy group is trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate or dipentaerythritol penta (meth) acrylate. The hard coating composition of claim 1, wherein the polyfunctional urethane (meth) acrylate having a cyclohexyl group is at least one member selected from the group consisting of compounds represented by the following Chemical Formulas 2-3:
[Formula 2]

[Formula 3]

delete delete delete delete The hard coating composition of claim 1, further comprising inorganic nanoparticles. Hard coating film formed using the hard coating composition according to any one of claims 1 to 9 and 14. An image display device having a hard coating film according to claim 15. A window of a flexible display device having a hard coat film according to claim 15.