KR102436845B1 - Hard Coating Composition and Hard Coating Film Using the Same - Google Patents

Abstract

The present invention provides a hard coating composition comprising a photocurable ionic alkali metal salt, a polyfunctional urethane (meth)acrylate having a cyclohexyl group, and a polyfunctional (meth)acrylate having an ethylene glycol group, a photoinitiator and a solvent, and formed using the same It provides a hard coating film and an image display device provided with the hard coating film. The hard coating film according to the present invention has excellent hardness and flexibility, excellent scratch resistance, excellent adhesion and curl properties, as well as excellent antistatic properties.

Description

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 excellent hardness and flexibility and having an excellent antistatic effect, a hard coating film formed using the same, and the hard coating film It relates to an image display device equipped with this.

The hard coating film is used for the purpose of surface protection in image display devices such as liquid crystal displays, electroluminescence (EL) displays, plasma displays (PD), and field emission displays (FEDs).

Recently, a flexible display device that can maintain display performance as it is even when bent like paper by using a flexible material such as plastic instead of the existing inflexible glass substrate is rapidly emerging as a next-generation display device, and hardness is increasing. Research is being conducted on hard coating films that are not only high in scratch resistance, but also do not have curls at the edges of the film during the manufacturing process or use, and have adequate flexibility so that cracks do not occur.

In Korea Patent Publication No. 2013-0135151, a hard coating composition containing a monomer for a binder containing a 3 to 6 functional acrylate-based monomer, inorganic fine particles, a photoinitiator, and an organic solvent, exhibiting high hardness, and no curl or cracking. is presenting

However, in the case of such a conventional hard coating composition of high hardness, flexibility is not sufficient, and when an antistatic agent is included for antistatic properties necessary for preventing adsorption of foreign substances, etc., there is a problem in that hardness properties are lowered, A hard coating composition that exhibits high hardness characteristics with excellent antistatic properties and is also excellent in flexibility has not yet been developed.

Republic of Korea Patent Publication No. 2013-0135151

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 excellent hardness and flexibility and also having an excellent antistatic effect.

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

Another object of the present invention is to provide an image display device provided with the hard coating film.

On the other hand, the present invention provides a hard coating composition comprising a photocurable ionic alkali metal salt, a polyfunctional urethane (meth)acrylate having a cyclohexyl group, and a polyfunctional (meth)acrylate having an ethylene glycol group, a photoinitiator and a solvent do.

In one embodiment of the present invention, the photocurable ionic alkali metal salt may include a compound of formula (I).

[Formula I]

M ⁺ X ^-

In the above formula,

M ⁺ is an alkali metal cation

X ⁻ is an anion having a polymerizable functional group and an ionic functional group.

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

In one embodiment of the present invention, the polyfunctional (meth)acrylate having an ethylene glycol group is an 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 an embodiment of the present invention may further include inorganic nanoparticles.

On the other hand, the present invention provides a hard coating film formed 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 has high hardness and excellent scratch resistance, as well as excellent adhesion, curl and crack properties, and excellent antistatic properties. It can be used effectively for Windows.

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

One embodiment of the present invention is a hard coating composition comprising a photocurable ionic alkali metal salt, a polyfunctional urethane (meth)acrylate having a cyclohexyl group, and a polyfunctional (meth)acrylate having an ethylene glycol group, a photoinitiator and a solvent it's about

In one embodiment of the present invention, the photocurable ionic alkali metal salt may react with the polyfunctional acrylate mixture during photocuring, and may exhibit an antistatic effect by imparting ionic conductivity.

The photocurable ionic alkali metal salt is 0.1 to 20 based on 100 wt% of the photocurable ionic alkali metal salt, polyfunctional urethane (meth)acrylate having a cyclohexyl group, and polyfunctional (meth)acrylate having an ethylene glycol group % by weight, preferably 0.5 to 15% by weight. If it is less than 0.1% by weight, antistatic properties may be insufficient, and if it is greater than 20% by weight, it may be difficult to impart hardness characteristics due to poor durability of the hard coating layer.

In one embodiment of the present invention, the photocurable ionic alkali metal salt may be a compound of the following formula (I).

[Formula I]

M ⁺ X ^-

In the above formula,

M ⁺ is an alkali metal cation,

X ⁻ is an anion having a polymerizable functional group and an ionic functional group.

The alkali metal may be lithium, sodium, potassium or cesium, in particular lithium, sodium or potassium.

The anion having the polymerizable functional group and the ionic functional group is composed of at least one polymerizable functional group selected from the group consisting of a (meth)acrylate group, a vinyl group, an allyl group and a styryl group, and a sulfonate, a carboxylate, and a phosphonate. It may be an anion having one or more ionic functional groups selected from the group.

In one embodiment of the present invention, the anion having a polymerizable functional group and an ionic functional group may be a sulfoalkyl (meth)acrylate, for example, sulfopropyl methacrylate, sulfopropyl acrylate, sulfoethyl methacrylate or sulfoethyl acrylate, but is not limited thereto.

In one embodiment of the present invention, the photocurable ionic alkali metal salt may include at least one of a compound of Formula 1 and a compound of Formula 2 below, but is not limited thereto.

[Formula 1]

[Formula 2]

The photocurable ionic alkali metal salt may be obtained commercially or may be prepared according to a method known in the art.

In one embodiment of the present invention, the polyfunctional urethane (meth)acrylate having a cyclohexyl group is a component for improving mechanical properties, particularly hardness, of a film to be coated, and the photocurable ionic alkali metal salt, a cyclohexyl group 15 to 60% by weight, preferably 30 to 55% by weight, based on 100% by weight of the polyfunctional urethane (meth)acrylate having an ethylene glycol group and the polyfunctional (meth)acrylate having an ethylene glycol group. If it is less than 15% by weight, there may be a decrease in mechanical properties, particularly hardness, and if it is greater than 60% by weight, the shrinkage force may be increased to cause curl, breakage, cracks, etc. of the film.

The polyfunctional urethane (meth)acrylate having a cyclohexyl group may be prepared by condensation reaction of a diisocyanate having a cyclohexyl group and a polyfunctional (meth)acrylate having a hydroxyl group.

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

The polyfunctional (meth)acrylate having a hydroxyl group may be specifically trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, etc., but is limited thereto not.

In one embodiment of the present invention, the polyfunctional urethane (meth)acrylate having a cyclohexyl group may include at least one selected from the group consisting of compounds represented by the following Chemical Formulas 3 to 4.

[Formula 3]

[Formula 4]

In one embodiment of the present invention, the polyfunctional (meth)acrylate having an ethylene glycol group is a component for imparting flexibility to the film to be coated, and the photocurable ionic alkali metal salt, a polyfunctional urethane having a cyclohexyl group ( It may be included in an amount of 10 to 50% by weight based on 100% by weight of the total polyfunctional (meth)acrylate having a meth)acrylate and an ethylene glycol group. If it is less than 10% by weight, fracture or cracking of the coating film may occur due to insufficient flexibility, and if it is greater than 50% by weight, mechanical properties may be lowered and surface scratches or pencil hardness may be reduced.

The polyfunctional (meth)acrylate having an ethylene glycol group can be prepared by adding ethylene oxide to a polyhydric alcohol to obtain a polyfunctional alcohol having an ethylene glycol group, and condensing (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 an ethylene glycol group include trimethylolpropane (EO) ₃ tri (meth) acrylate, trimethylolpropane (EO) ₆ tri (meth) acrylate, trimethylol propane (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, dipenta and erythritol (EO) ₁₂ hexa (meth) acrylate, dipentaerythritol (EO) ₁₈ hexa (meth) acrylate, and the like.

In one embodiment of the present invention, the polyfunctional (meth)acrylate having an ethylene glycol group may include at least one selected from the group consisting of compounds of Formulas 5 to 6 below.

[Formula 5]

[Formula 6]

In one embodiment of the present invention, the photoinitiator may be used without limitation as long as it is used in the art. There are Type 1 photoinitiators, in which radicals are generated by the decomposition of molecules due to differences in chemical structure or molecular binding energy, and Type 2 photoinitiators, which coexist with tertiary amines, and are hydrogen-recovery type photoinitiators. Specific examples of the Type 1 photoinitiator include 4-phenoxydichloroacetphenone, 4-t-butyldichloroacetphenone, 4-t-butyltrichloroacetphenone, diethoxyacetphenone, 2-hydroxy-2-methyl-1 -Phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methyl Acetphenones, such as propan-1-one, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenyl ketone, benzoin, benzoinmethyl Benzoins, such as ether, benzoin ethyl ether, and benzyl dimethyl ketal, acylphosphine oxides, 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'-methyldiphenylsulfide, 3,3' -benzophenones such as methyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, and thioxanthone such as isopropylthioxanthone Oxanthone etc. are mentioned. Each of these may be used alone or in combination of two or more. In addition, the Type 1 photoinitiator and the Type 2 photoinitiator may be used alone or in combination.

The photoinitiator may be included in an amount of 0.1 to 15% by weight, preferably 1 to 10% by weight based on 100% by weight of the total hard coating composition. If it is less than 0.1% by weight, curing may not proceed sufficiently, and the mechanical properties or adhesion of the finally obtained coating film may be reduced.

In one embodiment of the present invention, the solvent may be used without limitation as long as it is used in the art. Specifically, alcohol-based (methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol, etc.), ketone-based (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, etc.), acetate-based (methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxy acetate, etc.), cellosolve (methyl cellosolve, ethyl cellosolve, propyl cellosolve, etc.), hydrocarbon-based (normal hexane, normal heptane, benzene, toluene, xyl Ren et al.) and the like. Each of the above solvents may be used alone or in combination of two or more.

The solvent may be included in an amount of 5 to 90% by weight, preferably 20 to 70% by weight, based on 100% by weight of the total hard coating composition. If it is less than 5% by weight, the viscosity is high and workability is lowered, and if it is more than 90% by weight, it is difficult to adjust the thickness of the coating film, and there is a disadvantage that the appearance is poor due to the occurrence of dry stains.

The hard coating composition according to an 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. These inorganic nanoparticles are uniformly formed in the coating film to improve mechanical properties such as abrasion resistance, scratch resistance, and pencil hardness. If the particle size is less than the above range, aggregation occurs in the composition and a uniform coating film cannot be formed, and the above effect cannot be expected. On the contrary, a problem in which mechanical properties are deteriorated may occur.

The material of these 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 selected from the group consisting of Al, Nb ₂ O ₃ , SnO, MgO, and combinations thereof may be used, and preferably Al ₂ O ₃ , SiO ₂ , ZrO ₂ and the like may be used. The inorganic nanoparticles may be prepared directly or purchased commercially. Commercially available products may be used dispersed in an organic solvent at a concentration of 10 to 80% by weight.

The inorganic nanoparticles may be included in an amount of 5 to 40% by weight based on 100% by weight of the total hard coating composition. If it is less than 5% by weight, mechanical properties such as abrasion resistance, scratch resistance, and pencil hardness may not be sufficient, and if it is more than 40% by weight, it interferes with curability, and the mechanical properties are rather deteriorated, and the appearance may be poor.

The hard coating composition according to an embodiment of the present invention includes, in addition to the above components, components commonly used in the art, for example, a leveling agent, a UV stabilizer, 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 smoothness and coatability of the coating film when coating the hard coating composition. As the leveling agent, commercially available silicone type leveling agents, fluorine type leveling agents, acrylic polymer type leveling agents, etc. may be used, for example, BYK-323, BYK-331, BYK-333, BYK of BYK Chem. -337, BYK-373, BYK-375, BYK-377, BYK-378, Daegusa 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, 3M's FC-4430, FC-4432, etc. can be used. The leveling agent is preferably used in an amount of 3 to 5% by weight based on 100% by weight of the total hard coating composition.

The UV stabilizer is an additive added for the purpose of protecting the coating film by blocking or absorbing UV rays, since the surface of the cured coating film is decomposed by continuous exposure to ultraviolet rays, thereby discoloring and brittle. The ultraviolet stabilizer is classified into an absorber, a quencher, and a hindered amine light stabilizer (HALS, Hindered Amine Light Stabilizer) according to the mechanism of action. In addition, depending on the chemical structure, phenyl salicylate (absorbent), benzophenone (absorbent), benzotriazole (absorbent), nickel derivative (quenching agent), radical scavenger (Radical Scavenger) can be distinguished. The ultraviolet stabilizer is not particularly limited as long as it does not significantly change the initial color of the coating film.

The thermal stabilizer is a commercially applicable product, and a polyphenol-based primary thermal stabilizer, a phosphite-based secondary thermal stabilizer, and a lactone-based thermal stabilizer may be used alone or in combination.

The UV stabilizer and heat stabilizer may be used by appropriately adjusting the content at a level that does not affect UV curability.

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

As the transparent substrate, any transparent plastic film may 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, polyacrylic, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, Polymethyl pentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, It can be used by selecting polyethylene naphthalate, polycarbonate, polyurethane, and epoxy, and an unstretched, 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 μm, the strength of the film is lowered to deteriorate workability, and when it exceeds 1000 μm, there is a problem in that the transparency is lowered or the weight of the hard coating film is increased.

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

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

After the hard coating composition is applied to the transparent substrate, the volatiles are evaporated and dried at a temperature of 30 to 150° C. for 10 seconds to 1 hour, more specifically, for 30 seconds to 30 minutes, and then irradiated with UV light. to harden it. The irradiation amount of the UV light may be specifically about 0.01 to 10J/cm 2 , more specifically 0.1 to 2 J/cm 2 .

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

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

The hard coating film according to an embodiment of the present invention may be used in LCDs of various driving methods such as reflective, transmissive, transflective LCD or TN type, STN type, OCB type, HAN type, VA type, IPS type, and the like. In addition, the hard coating film according to an embodiment of the present invention may 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 electronic paper.

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

Examples 1 to 8 and Comparative Examples 1 to 5: Preparation of a hard coating composition

A mixture was obtained by mixing a photocurable ionic alkali metal salt with the composition of Table 1 , a polyfunctional urethane (meth)acrylate having a cyclohexyl group, and a polyfunctional (meth)acrylate having an ethylene glycol group (unit: wt%) ).

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

Formula 1 Formula 2 Ionic non-metal salt Formula 3 Formula 4 UA-306H Formula 5 Formula 6 M-340 Example 1 10 5 50 35 Example 2 5 10 50 35 Example 3 8 7 45 40 Example 4 10 5 45 40 Example 5 5 10 50 35 Example 6 8 7 55 30 Example 7 10 5 50 0 35 Example 8 5 10 45 40 Comparative Example 1 10 5 50 35 Comparative Example 2 5 10 50 35 Comparative Example 3 55 45 Comparative Example 4 8 7 45 0 0 40 Comparative Example 5 15 50 35

Compound of formula 1 (3-sulfopropyl methacrylate potassium salt, Sigma Aldrich)

Compound of formula 2 (3-sulfopropyl acrylate potassium salt, Sigma Aldrich)

Ionic non-metal salt (quaternary ammonium salt, MORESTAT ES-7205, Morechem)

Compound of Formula 3 (Shinah T&C SOU-1700B)

Compound of Formula 4 (Shinah T&C SOU-1290)

UA-306H (public corporation)

Compound of Formula 5 (Miwon Specialty Chemical M4004)

Compound of Formula 6 (Japanese Explosives DPEA126)

M-340 (Miwon Specialty Chemical)

Experimental Example 1:

The hard coating composition prepared in Examples and Comparative Examples is coated on one side of an optical polyimide film (Mitsubishi Gas Chemical, 100㎛, L-3430) so that the thickness becomes 20㎛ after drying, and in an oven at 80°C for 2 minutes After drying, the hard coating film was prepared by curing it with a light quantity of 350 mJ/cm 2 in a high-pressure mercury lamp.

The physical properties of the prepared hard coating film were measured by the method described below, and the results are shown in Tables 2 and 3 below.

(1) Pencil hardness

Using a pencil hardness tester (PHT, Seokbo Science Co., Korea), a load of 500 g was applied and the pencil hardness was measured. Pencils manufactured by Mitsubishi were used, and the average value was recorded by performing 5 times per pencil hardness.

(2) scratch resistance

Abrasion resistance was tested by reciprocating 10 times under 1kg/(2cm×2cm) using a steel wool tester (WT-LCM100, Protec, Korea). Steel wool #0000 was used.

<Evaluation criteria>

S: 0 scratches

A: 1 to 10 scratches

B: 11-20 scratches

C: 21 to 30 scratches

D: 31 or more scratches

(3) Adhesion

After making 100 squares by drawing 11 straight lines horizontally and vertically at intervals of 1 mm on the coated side of the film, a peel test was performed three times using a tape (CT-24, Nichiban, Japan). Three 100 squares were tested and the average was recorded. Adhesion was recorded as follows.

Adhesion = n/100

n: the number of non-exfoliated rectangles among all rectangles

100: the total number of squares

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

(4) curl

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

(5) crack resistance

In order to evaluate cracking properties, place the coated film sample cut to a size of 1cm×10cm on a steel bar of each diameter (2φ~10φ) and fold the coating layer up by hand to mark the smallest diameter that does not cause cracks on the surface did.

(6) Antistatic properties (surface resistivity)

Using a surface resistance measuring device (MCP-HT450, Mitsubishi chemical, Probe: URS, UR100, Probe checker: for URS, for UR100), measure the three points of the coating layer 10 times each, then calculate the average value and follow the criteria below. based on the evaluation.

<Evaluation criteria>

○: Surface resistivity ≤ 5.0×10 ¹⁰ Ω/□

△: 5.0×10 ¹⁰ Ω/□ < Surface resistivity ≤ 9.9×10 ¹⁰ Ω/□

×: 9.9×10 ¹⁰ Ω/□ < surface resistivity

(7) Antistatic properties over time

The antistatic property was evaluated after the sample, whose antistatic property was measured as described above, was heat-treated in a heat-resistant oven at 60° C. for 24 hours.

<Evaluation criteria>

○: Surface resistivity change ≤ 3.0×10 ¹⁰ Ω/□

△: 3.0×10 ¹⁰ Ω/□ < Surface resistivity change ≤ 5.0×10 ¹⁰ Ω/□

×: 5.0×10 ¹⁰ Ω/□ < change in surface resistivity

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 pencil hardness 6H 5H 6H 4H 5H 5H 5H 4H scratch resistance S S S S S S S A adhesion 100/100 100/100 100/100 100/100 100/100 100/100 100/100 100/100 curl 2mm 2mm 2mm 2mm 5mm 5mm 3mm 4mm mandorel 2φ 2φ 3φ 3φ 3φ 2φ 3φ 3φ antistatic ○ ○ ○ △ ○ ○ ○ △ anti-static property ○ ○ ○ ○ ○ ○ △ ○

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 pencil hardness H H F F 2B scratch resistance B B B B C adhesion 95/100 90/100 70/100 75/100 60/100 curl 6mm 8mm 8mm 8mm 11mm mandorel 7φ 8φ 8φ 8φ 10φ antistatic △ △ × △ △ anti-static property △ △ × △ △

As shown in Tables 2 and 3, the hard coating films prepared using the hard coating compositions of Examples 1 to 8 according to the present invention have hardness, abrasion resistance, adhesion, curl properties and crack resistance as well as antistatic properties. All were excellent. On the other hand, it was confirmed that the hard coating films prepared using the hard coating compositions of Comparative Examples 1 to 5 were inferior in hardness, scratch resistance, adhesion, curl properties, crack resistance or antistatic properties.

As the specific part of the present invention has been described in detail above, for those of ordinary skill in the art to which the present invention pertains, it is clear that these specific techniques are only preferred embodiments, and the scope of the present invention is not limited thereto. do. Those of ordinary skill 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.

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

Claims (18)

A hard coating composition comprising a photocurable ionic alkali metal salt, a polyfunctional urethane (meth)acrylate having a cyclohexyl group, and a polyfunctional (meth)acrylate having an ethylene glycol group, a photoinitiator and a solvent,
The polyfunctional (meth)acrylate having an ethylene glycol group is at least one hard coating composition selected from the group consisting of compounds of the following Chemical Formulas 5 to 6:
[Formula 5]

[Formula 6]

. The hard coating composition according to claim 1, wherein the photocurable ionic alkali metal salt comprises a compound of formula (I):
[Formula I]
M ⁺ X ^-
In the above formula,
M ⁺ is an alkali metal cation,
X ⁻ is an anion having a polymerizable functional group and an ionic functional group. The hard coating composition of claim 2, wherein the alkali metal is lithium, sodium, potassium or cesium. The method of claim 2, wherein the anion having a polymerizable functional group and an ionic functional group comprises at least one polymerizable functional group selected from the group consisting of a (meth)acrylate group, a vinyl group, an allyl group and a styryl group, sulfonate, carboxylate and A hard coating composition which is an anion having at least one ionic functional group selected from the group consisting of phosphonates. The hard coating composition of claim 2, wherein the anion having a polymerizable functional group and an ionic functional group is a sulfoalkyl (meth)acrylate. The hard coating composition of claim 1, wherein the photocurable ionic alkali metal salt comprises at least one of a compound of Formula 1 and a compound of Formula 2 below:
[Formula 1]

[Formula 2]

The hard coating composition of claim 1, wherein the polyfunctional urethane (meth)acrylate having a cyclohexyl group is prepared by condensation reaction of a diisocyanate having a cyclohexyl group and a polyfunctional (meth)acrylate having a hydroxyl group. The hard coating composition of claim 7, wherein the diisocyanate having a cyclohexyl group is 1,4-cyclohexyl diisocyanate, isophorone diisocyanate or 4,4-dicyclohexylmethane diisocyanate. The hard coating composition of claim 7, wherein the polyfunctional (meth)acrylate having a hydroxyl 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 selected from the group consisting of compounds represented by the following Chemical Formulas 3 to 4:
[Formula 3]

[Formula 4]

delete delete delete delete The hard coating composition of claim 1, further comprising inorganic nanoparticles. A hard coating film formed using the hard coating composition according to any one of claims 1 to 10 and 15. An image display device provided with the hard coating film according to claim 16 . A window of a flexible display device provided with the hard coating film according to claim 16 .