KR20160116923A - Anti-Static Hard Coating Composition and Optical Sheet Using the Same - Google Patents

Abstract

Provided is an antistatic hard coating composition including: urethane (meth)acrylate oligomer with acryl gram equivalent ranging from 400 to 600; a solvent satisgfying equation 1; and an alkali alkali earth metal salt antistatic agent. Also, provided is an optical sheet using the same. According to the present invention, the antistatic hard coating composition shows favorable antistatic performance even with a small amount of the antistatic agent, thereby preventing attachment of static foreign substances to optical sheets and exhibiting optical and mechanical properties.

Description

TECHNICAL FIELD [0001] The present invention relates to an antistatic hard coating composition and an optical sheet using the same,

The present invention relates to an antistatic hard coating composition and an optical sheet using the antistatic hard coating composition. More particularly, the present invention relates to an antistatic hard coating composition which not only exhibits excellent antistatic properties but also has excellent optical and mechanical properties, The present invention relates to an optical sheet.

The hard coating composition applied on a substrate such as a plastic generally has no antistatic property in many cases. Even if it has antistatic property, the antistatic property deteriorates with time as the ion conductive material is added. A hard coating composition obtained by mixing a metal and carbon powder having excellent antistatic properties is used but there has been a demand for development of an antistatic hard coating composition which has a problem in chromaticity and can provide satisfactory physical properties.

According to such technical requirements, an antistatic hard coating composition using a metal oxide based conductive sol such as ATO (antimony tin oxide), ITO (indium tin oxide) and the like has been developed. However, such a hard coating composition has excellent antistatic properties, but it has a low transmittance of about 80% to 85% when coated on a base film and has a blue tone, which not only damages the appearance of the base film, The cost of the product is so high that the cost of the product is raised.

Korean Patent Publication No. 2008-0053234 discloses an antistatic coating composition comprising a conductive polymer. However, a large amount of an antistatic agent must be used in order to realize antistatic performance of the object, have. Korean Patent No. 10-0750864 discloses a display light-use sheet for preventing the generation of static electricity by using a bisphenol-type oligomer containing a quaternary ammonium salt. However, since the hardness of the sheet is low and cracks are generated, There is a problem.

Korean Patent Publication No. 2008-0053234 Korean Patent No. 10-0750864

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an antistatic agent which not only exhibits excellent antistatic property even with a small amount of antistatic agent but also has excellent antistatic property Hard coating composition.

Another object of the present invention is to provide an optical sheet produced using the antistatic hard coating composition.

On the other hand, the present invention provides an antistatic hard coating composition comprising a urethane (meth) acrylate oligomer having an acrylate equivalent of 400 to 600, a solvent satisfying the following formula 1, and an alkaline earth metal salt antistatic agent.

[Formula 1]

0.3 < (RP_A x a) + (RP_B x b) < 0.4

In this formula,

RP_A is a relative polarity value of the solvent A,

a is the weight ratio of solvent A to the total solvent,

RP_B is the relative polarity of the solvent B,

b is the weight ratio of solvent B to the total solvent.

In one embodiment of the present invention, the urethane (meth) acrylate oligomer can be prepared by polymerizing a polyfunctional (meth) acrylate having a hydroxyl group in a molecule and a compound having two or more isocyanate groups in the molecule.

In one embodiment of the present invention, the solvent A is an alcohol-based solvent, and the solvent B is a hydrocarbon-based solvent.

In one embodiment of the present invention, the alkaline earth metal salt antistatic agent may be a compound represented by the following formula (1).

[Chemical Formula 1]

In the above formulas,

M is an alkaline earth metal.

The antistatic hard coating composition according to one embodiment of the present invention may further comprise a (meth) acrylate monomer and a photoinitiator.

On the other hand, the present invention provides an optical sheet comprising a hard coating layer formed by applying and curing the antistatic hard coating composition on at least one side of a substrate.

In one embodiment of the present invention, the optical sheet may be a prism sheet further comprising a prism coating layer formed on the other side of the base.

The antistatic hard coating composition according to the present invention can exhibit sufficient antistatic performance even with a small amount of antistatic agent, thereby preventing adhesion of electrostatic foreign matter on the optical sheet, and also has high transparency, low haze, high hardness Excellent scratch resistance and adhesion, and less color change.

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

An embodiment of the present invention relates to an antistatic hard coating composition comprising a urethane (meth) acrylate oligomer having an acrylate equivalent of 400 to 600, a solvent satisfying the following formula 1, and an alkaline earth metal salt antistatic agent.

[Formula 1]

0.3 < (RP_A x a) + (RP_B x b) < 0.4

In this formula,

RP_A is a relative polarity value of the solvent A,

a is the weight ratio of solvent A to the total solvent,

RP_B is the relative polarity of the solvent B,

b is the weight ratio of solvent B to the total solvent.

The acrylic gram equivalent is a value calculated by the following equation (2).

[Formula 2]

Acrylic gram equivalent = Oligomer molecular weight / number of acrylic functional groups per molecule

In one embodiment of the present invention, the acrylate equivalent of the urethane (meth) acrylate oligomer is adjusted to 400 to 600, the value of (RP_A xa) + (RP_B xb) is controlled to 0.3 to 0.4, By using the antistatic agent, it is possible to increase the surface lifting force of the alkaline earth metal salt electrification preventing agent to realize antistatic performance even in a small amount, and to improve the hardness of the hard coat layer to be formed.

In one embodiment of the present invention, the urethane (meth) acrylate oligomer not only improves workability by imparting elasticity and flexibility to an optical sheet produced using the hard coating composition of the present invention, The surface lifting force of the inhibitor is further enlarged so that the antistatic performance can be realized even in a small amount.

The urethane (meth) acrylate oligomer can be prepared by polymerizing a polyfunctional (meth) acrylate having a hydroxyl group in a molecule and a compound having two or more isocyanate groups in the molecule.

Specific examples of the polyfunctional (meth) acrylate having a hydroxyl group in the molecule include 2-hydroxyethyl (meth) acrylate, 2-hydroxyisopropyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate, a mixture of dipentaerythritol penta / hexa (meth) acrylate, a mixture of a hydroxyalkylene glycol having 2 to 4 carbon atoms in the alkylene group (Meth) acrylate, and the like, but are not limited thereto. Particularly, hydroxyalkyleneglycol (meth) acrylate having a caprolactone-modified hydroxyacrylate or an alkylene group having 2 to 4 carbon atoms can be used.

Specific examples of the compound having two or more isocyanate groups in the molecule include 1,4-diisocyanatobutane, 1,6-diisocyanatohexane, 1,8-diisocyanatooctane, 1,12-diisocyanato Decane, 1,5-diisocyanato-2-methylpentane, trimethyl-1,6-diisocyanatohexane, 1,3-bis (isocyanatomethyl) cyclohexane, trans-1,4-cyclohexane diisocyanate , 4,4'-methylenebis (cyclohexylisocyanate), isophorone diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, xylene-1,4-diisocyanate, Diisocyanate, 4,4'-methylenebis (2,6-dimethylphenyl isocyanate), 4,4'-oxybis (phenylisocyanate), 4,4'- Trifunctional isocyanates derived from hexamethylene diisocyanate, trimethylolpropane adduce Toluene diisocyanate, and the like, but is not limited to this. In particular, trifunctional isocyanates derived from hexamethylene diisocyanate or isophorone diisocyanate may be used.

The urethane (meth) acrylate oligomer may be contained in an amount of 10 to 50 wt% based on 100 wt% of the entire antistatic hard coating composition. If the content is less than 10% by weight, the effect of improving the surface lifting force of the alkali earth metal salt antistatic agent is insignificant and the antistatic performance may be reduced. If the content is more than 50% by weight, the thermal stability and the film hardness may be lowered.

In one embodiment of the present invention, the solvent is a mixed solvent of the solvent A and the solvent B, and any solvent known in the art can be used as long as the above formula 1 is satisfied.

In one embodiment of the present invention, the solvent A is a polar solvent, specifically an alcohol solvent having a relative polarity value of 0.3 to 0.8 such as methanol (relative polarity: 0.762), ethanol (relative polarity: 0.654) (Relative value: 0.546), butanol (relative value: 0.586), and diethylene glycol (relative value: 0.713). Ethanol may be used.

As the solvent B, a nonpolar solvent, a hydrocarbon solvent having a relative polarity value of 0.001 to 0.15, such as n-hexane (relative polarity value: 0.009), n-heptane (relative polarity value: 0.012) Value: 0.111), toluene (relative polarity value: 0.099), xylene (relative polarity value: 0.074), and toluene can be used.

The solvent may be contained in an amount of 30 to 70% by weight based on 100% by weight of the total amount of the antistatic hard coating composition. If the content is less than 30% by weight, the viscosity may increase and the workability may deteriorate and the surface flatness may be deteriorated. If the content is more than 70% by weight, the coating pressure may increase during coating and flatness may be deteriorated. The processing cost is increased and it is not environmentally friendly.

In one embodiment of the present invention, the alkaline earth metal salt antistatic agent may be a compound represented by the following formula (1).

[Chemical Formula 1]

In the above formulas,

M is an alkaline earth metal, specifically beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) or radium (Ra), in particular magnesium (Mg).

The alkali earth metal salt antistatic agent may be contained in an amount of 1 to 15% by weight based on 100% by weight of the entire antistatic hard coating composition. If the content is less than 1% by weight, the antistatic property is insignificant, and the function of preventing electrostatic foreign matters from adhering to the sheet may not be improved. If the content is more than 15% by weight, problems such as yellowing, lack of adhesion, .

In addition, the alkali earth metal salt antistatic agent has less effect on the antistatic performance depending on the exposure environment as compared with the alkali metal salt antistatic agent, and has an advantage that the antistatic performance to be expressed can be maintained regardless of the change in temperature or humidity.

The antistatic hard coating composition according to one embodiment of the present invention may further comprise a (meth) acrylate monomer and a photoinitiator.

The (meth) acrylate monomer serves to improve the hardening density of the hard coat layer formed from the antistatic hard coat composition of the present invention.

Specific examples of the (meth) acrylate monomers include neopentyl glycol (meth) acrylate, 1,6-hexanediol (meth) acrylate, propylene glycol di (meth) acrylate, triethylene glycol di Acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylol ethane tri Acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, pentaerythritol tetra (Meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (Meth) acrylates such as tripentaerythritol tri (meth) acrylate, tripentaerythritol hexa tri (meth) acrylate, bis (2-hydroxyethyl) isocyanurate di (Meth) acrylate, stearyl (meth) acrylate, tetrahydroperfuryl (meth) acrylate, isobutyl (meth) acrylate, Acrylate, phenoxyethyl (meth) acrylate, and isobonole (meth) acrylate.

The (meth) acrylate monomer may be contained in an amount of 10 to 40% by weight based on 100% by weight of the entire antistatic hard coating composition. When the content is less than 10% by weight, the curing rate and the surface hardness are lowered. When the content is more than 40% by weight, warpage of the optical sheet may occur due to reduction of crack resistance and flexibility.

The photoinitiator serves to change the hard coating composition in a liquid phase to a solid phase by light irradiation. As the photoinitiator, there are a Type 1 photoinitiator and a hydrogen recycle photoinitiator which generate radicals by decomposition of molecules due to a difference in chemical structure or molecular binding energy. Specific examples of the Type 1 type photoinitiator include 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyltrichloroacetophenone, diethoxyacetophenone, 3-methylacetophenone, 2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2 2-methylpropan-1-one, 4- (2-hydroxyethoxy) -phenyl ( Acetophenones such as 2-hydroxy-2-propyl ketone, 1-hydroxycyclohexyl phenyl ketone and 4-hydroxycyclophenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, Benzophenones, acylphosphine oxides, titanocene compounds, and the like. Specific examples of the Type 2 type photoinitiator include benzophenone, benzoyl benzoic acid, benzoyl benzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3 ' Benzophenones such as methyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, and isopropylthioxanthone Oxanone, and the like. The above-exemplified photoinitiators may be used singly or in combination of two or more. Type 1 and Type 2 may be used in combination. In addition, the photoinitiator may be any of those known in the art without limitation. Specific examples thereof include 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinepropanone- -Hydroxy-2-methyl-1-phenyl-1-one, anthraquinone, fluorene, triphenylamine and carbazole.

The photoinitiator may be included in an amount of 0.1 to 10% by weight based on 100% by weight of the entire antistatic hard coating composition. If the content is less than 0.1% by weight, the curing rate is slow and it may be difficult to realize sufficient mechanical properties and adhesion due to insufficient curing. If the content is more than 10% by weight, adhesion failure or cracking may occur due to curing shrinkage. The value can rise.

The antistatic hard coating composition according to one embodiment of the present invention may contain, in addition to the above-mentioned components, components commonly used in the art such as leveling agents, ultraviolet stabilizers, heat stabilizers, antioxidants, UV absorbers, An activator, a lubricant, an antifouling agent, and the like.

One embodiment of the present invention relates to an optical sheet produced using the antistatic hard coating composition described above. An optical sheet according to an embodiment of the present invention includes a hard coating layer formed by applying and curing the antistatic hard coating composition described above on at least one side of a substrate.

Specific examples of the substrate include cellulose derivatives such as diacetyl cellulose, triacetyl cellulose and acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, polyester, polystyrene, polyamide, polyether amide, polyacryl, polyimide, poly But are not limited to, ether sulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate , Polycarbonate and the like can be used, and triacetyl cellulose, polyethylene terephthalate, polymethyl methacrylate and the like can be preferably used, but it is not limited thereto.

The antistatic hard coating composition may be coated on at least one side of the substrate by a conventional method known in the art. Specifically, a die coater, an air knife, a reverse roll, a spray, a blade, Gravure or spin coating may be used.

After the antistatic hard coating composition is applied to the substrate, the volatiles are evaporated at a temperature of 30 to 150 캜 for 10 seconds to 1 hour, more specifically for 30 seconds to 30 minutes, Irradiation and curing. The irradiation amount of the UV light may be about 0.01 to 10 J / cm 2, and more specifically, about 0.1 to 2 J / cm 2.

In one embodiment of the present invention, the optical sheet may be a prism sheet further including a prism coating layer formed on the other surface of the base material. That is, a hard coating layer formed of the antistatic hard coating composition may be formed on one side of the substrate, and a prism coating layer may be formed on the other side of the substrate. The prism coating layer can be formed by coating a conventional prism-forming composition on a frame in which a three-dimensional structure (prism structure) having a brightness improving function is coated on a frame by a known method, and irradiating ultraviolet light to photo-cure the composition.

The optical sheet can be suitably used for various types of LCDs of various driving types such as reflective type, transmissive type, transflective type LCD or TN type, STN type, OCB type, HAN type, VA type and IPS type. It can also be suitably used for various display devices such as plasma display, field emission display, organic EL display, inorganic EL display, electronic paper and the like.

The present invention also provides a backlight unit device of a liquid crystal display device having the optical sheet. The backlight unit device is not limited, and a structure known in the art can be employed. For example, a light source such as an LED and a light guide plate for guiding light from a light source and a diffusion sheet, a prism sheet, and the like may be provided on the upper surface of the light guide plate.

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

Manufacturing example  1 to 4: urethane ( Meta ) Acrylate Oligomeric  Produce

A 1 L three-necked flask equipped with an electronic stirrer, a heating mantle, a cooling tube and a temperature controller was charged with a compound having at least two isocyanate groups in the molecule, a polyfunctional (meth) acrylate having a hydroxyl group in the molecule, a methoxyhydroquinone (HQ- (Fascat 4202, Akemi) as a catalyst were charged into the composition shown in Table 1 below, and the reaction temperature was raised to 55 ° C by self-heating while stirring. When the temperature was gradually decreased, the reaction temperature was increased to 75 Lt; 0 &gt; C, and the reaction was maintained for 5 hours. When the characteristic peak of NCO on the FT-IR peak of 2260 cm &lt; ^-1 &gt; disappears, the reaction was terminated to prepare a urethane (meth) acrylate oligomer (unit: parts by weight).

Production Example 1 Production Example 2 Production Example 3 Production Example 4 The compound having an isocyanate group 191
(TKA-100 ¹⁾ ) 191
(TKA-100 ¹⁾ ) 111
(IPDI ²⁾⁾ 111
(IPDI ²⁾⁾ A polyfunctional (meth) acrylate having a hydroxy group 378
(FA-2D ³⁾⁾ 370
(PEA-6 ⁴⁾ ) 378
(FA-2D ³⁾⁾ 246
(2-hydroxyethyl acrylate ^{5 )} ) Methoxyhydroquinone 0.2 0.2 0.2 0.2 Dibutyl tin dilaurate 0.3 0.3 0.3 0.3 Acrylic gram equivalent 535 528 455 223

1) Isocyanurate type HDI trimer (Nissan Chemical Industries, Ltd., content 22%)

2) isophorone diisocyanate (Bayer, molecular weight 222)

3) Caprolactone denatured acrylate monomer (Diesell, molecular weight 344)

4) Ethylene oxide modified acrylate monomer (Cognis, molecular weight: 336)

5) Osaka Yucca, molecular weight 112

Manufacturing example  5: urethane ( Meta ) Acrylate Oligomeric  Produce

111 g of isophorone diisocyanate (IPDI, Bayer, molecular weight 222), polytetraethylene glycol (PolyTHF 1000, BASF Corp., molecular weight 1000) 250 (trade name, available from BASF) was added to a 1 L three-necked flask equipped with a stirrer, g, and 0.3 g of dibutyltin dilaurate (Fascat 4202, Akemi) as a catalyst, and the mixture was reacted at 65 DEG C for 4 hours. At this time, the NCO content by end-of-term analysis was 5.8%. 124 g of 2-hydroxyethyl acrylate (Osaka Oil Company, molecular weight 112) and 0.2 g of methoxyhydroquinone (HQ-MME, Eastman) as a polymerization inhibitor were further added, the reaction temperature was raised to 75 캜, Respectively. The urea (meth) acrylate oligomer was prepared by terminating the reaction when the characteristic peak of NCO of 2260 cm &lt; ^-1 &gt; peaks on FT-IR disappeared. At this time, the equivalent of acrylic grams was 834.

Example  1 to 5: Antistatic Hard coating  Preparation of composition

An antistatic hard coating composition was prepared by mixing the urethane (meth) acrylate oligomer, the (meth) acrylate monomer, the solvent, the photoinitiator and the antistatic agent obtained in Production Examples 1 to 3 in the composition shown in Table 2 below part).

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Production Example 1 25 - - 25 20 - Production Example 2 - 25 - - - - Production Example 3 - - 25 - - 25 1) M-340 15 15 15 10 10 15 2) Ethanol 28 28 30 27 29 - 3) Isopropanol - - - - - 32 4) Toluene 28 28 26 26 27 - 5) Benzene - - - - - 24 6) I-184 2 2 One 2 2 One 7) Mg (FSI) ₂ 2 2 4 10 12 - 8) Ba (FSI) ₂ - - - - - 4 (RP_A x a) + (RP_B x b) 0.377 0.377 0.397 0.382 0.387 0.360

1) Pentaerythritol triacrylate (Miwon Chemical Co.)

2) ethanol (relative polarity value: 0.654, purified water)

3) Isopropanol (relative polarity value: 0.546, purified water)

4) Toluene (relative polarity value: 0.099, purified water)

5) Benzene (relative polarity value: 0.111, purified water)

6) Hydroxycyclohexyl phenyl ketone (Shiba gauge)

7) The compound of formula (1) wherein M is magnesium

8) The compound of formula (I) wherein M is barium

Comparative Example  1 to 5: Antistatic Hard coating  Preparation of composition

An antistatic hard coating composition was prepared by mixing the urethane (meth) acrylate oligomer, the (meth) acrylate monomer, the solvent, the photoinitiator and the antistatic agent obtained in Production Examples 1, 4 and 5 in the composition shown in the following Table 3 : Parts by weight).

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Production Example 1 25 20 - - 25 25 20 Production Example 4 - - 25 - - - - Production Example 5 - - - 25 - - - M-340 15 20 15 15 10 15 20 ethanol 17 45 30 30 27 17 28 toluene 39 28 26 26 26 - 28 9) Benzonitrile 39 - I-184 2 2 One One 2 2 2 Mg (FSI) ₂ 2 2 4 4 - 2 - 10) LiI - 2 11) EDX10 - - - 10 - - (RP_A x a) + (RP_B x b) 0.268 0.441 0.397 0.397 0.382 0.431 0.377

9) benzonitrile (relative polarity value: 0.333, purified water)

10) LiI: alkali metal salt antistatic agent (NanochemTech)

11) ELECOM EDX10: Quaternary ammonium salt antistatic agent (Nano Chemtech)

Experimental Example  One:

Examples and Comparative examples of antistatic polyethylene terephthalate (PET) for the hard coating composition of 188 μm obtained in the coated film, and dried for one minute at 70 ℃ hard to screen optical path light amount 500 mJ / cm ² from a high pressure mercury lamp To prepare a coating film.

(1) transmittance and Hayes

Total transmittance and haze were measured using a spectrophotometer (HZ-1, manufactured by Nippon Sugar Co., Ltd.).

(2) Pencil hardness

The pencil hardness was measured by applying a load of 500 g using a pencil hardness tester (PHT, Korea Science and Engineering Corp.). The pencil was made using Mitsubishi products and was performed five times per pencil hardness. If the gas was 0 or 1, it was OK. If the gas was 2 or more, it was NG.

(3) Scratch resistance

Scratch resistance was tested by reciprocating ten times under 1 kg / (2 cm x 2 cm) using a steel wool tester (WT-LCM100, Korea Protec Co., Ltd.). Steel wool used # 0000.

<Evaluation Criteria>

S: 0 scratches

A: 1 to 10 scratches

B: 11-20 scratches

C: 21 ~ 30 scratches

D: More than 31 scratches

(4) Adhesion

11 straight lines were drawn on the coated surface of the film at intervals of 1 mm to form 100 squares, and then peel test was performed three times using a tape (CT-24, Nichii Co., Ltd.). Three 100 squares were tested and the average was recorded. The adhesion was recorded as follows.

Adhesion = n / 100

n: the number of rectangles that are not to be peeled out of the entire rectangle

100: total number of squares

Therefore, when none of them were peeled off, 100/100 was recorded.

(5) Color change

The PET film and each composition were coated and cured in a transmission mode using a Spectro color meter SE200 manufactured by Nippon Denshoku Co., Ltd., and the color values were measured to determine ΔE ^* _ab .

_{^{ΔE * ab = {(ΔL *}} ) 2 + (Δa *) 2 + (Δb *) 2} 1/2

(6) Surface resistivity

Surface resistance was measured using Hiresta's MCP-HT450.

The results of the measurement by the above-described method are shown in Tables 4 and 5 below.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Transmittance /
Hayes 95.1 /
1.0 95.3 /
0.9 96.1 /
1.1 93.9 /
1.5 94.1 /
1.9 96.1 /
1.1 Pencil hardness 2H 2H 2H 2H 2H 2H Scratch resistance A A A B B A Adhesiveness 100/100 100/100 100/100 100/100 100/100 100/100 Color change 0.1 0.1 0.2 0.2 0.2 0.2 Surface resistivity 10 ¹⁰ 10 ¹⁰ 10 ⁹ 10 ⁸ 10 ⁶ 10 ¹⁰

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Transmittance /
Hayes 94.9 /
0.9 95.2 /
2.0 95.4 /
2.1 95.1 /
1.3 93.7 /
2.2 94.9 /
0.9 95.2 /
2.0 Pencil hardness 2H 2H 2H HB 2H 2H 2H Scratch resistance A A A B A A A Adhesiveness 100/100 100/100 100/100 100/100 100/100 100/100 100/100 Color change 0.1 0.1 0.1 0.1 0.4 0.3 0.4 Surface resistivity 10 ¹¹ over 10 ¹² 10 ¹¹ 10 ¹¹ 10 ¹² over

As shown in Table 4, the hard coating films prepared using the antistatic hard coating compositions of Examples 1 to 6 according to the present invention had a high transmittance, a good hardness, a small color change and a surface resistivity of 10 ¹⁰ or less It was found that the antistatic property was excellent. On the other hand, as shown in Table 5, it was found that the hard coating films prepared using the antistatic hard coating compositions of Comparative Examples 1 to 7 had poor antistatic properties, had a low hardness and a large color change.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Do. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the actual scope of the invention is defined by the appended claims and their equivalents.

Claims (11)

An antistatic hard coating composition comprising a urethane (meth) acrylate oligomer having an acrylate equivalent of 400 to 600, a solvent satisfying Formula 1, and an alkaline earth metal salt antistatic agent:
[Formula 1]
0.3 < (RP_A xa) + (RP_B xb) < 0.4
In this formula,
RP_A is a relative polarity value of the solvent A,
a is the weight ratio of solvent A to the total solvent,
RP_B is the relative polarity of the solvent B,
b is the weight ratio of solvent B to the total solvent. The antistatic hard coating composition according to claim 1, wherein the urethane (meth) acrylate oligomer is prepared by polymerizing a polyfunctional (meth) acrylate having a hydroxyl group in a molecule and a compound having two or more isocyanate groups in the molecule. The polyfunctional (meth) acrylate according to claim 1, wherein the polyfunctional (meth) acrylate having a hydroxyl group in the molecule is caprolactone-modified hydroxyacrylate or a hydroxyalkylene glycol (meth) acrylate having 2-4 carbon atoms in the alkylene group Coating composition. The antistatic hard-coating composition according to claim 1, wherein the compound having two or more isocyanate groups in the molecule is a trifunctional isocyanate derived from hexamethylene diisocyanate or isophorone diisocyanate. The antistatic hard-coating composition according to claim 1, wherein the solvent A is an alcohol-based solvent and the solvent B is a hydrocarbon-based solvent. The antistatic hard-coating composition according to claim 1, wherein the solvent A is ethanol and the solvent B is toluene. The antistatic hard coating composition according to claim 1, wherein the alkaline earth metal salt antistatic agent is a compound represented by the following formula
[Chemical Formula 1]

In the above formulas,
M is an alkaline earth metal. 8. The method of claim 7,
And M is magnesium (Mg). The antistatic hard-coating composition of claim 1, further comprising a (meth) acrylate monomer and a photoinitiator. An optical sheet comprising a hard coating layer formed by applying and curing an antistatic hard coating composition according to any one of claims 1 to 9 on at least one side of a substrate. The optical sheet according to claim 10, wherein the optical sheet is a prism sheet further comprising a prism coating layer formed on the other surface of the substrate.