KR20170131205A - Hard Coating Composition and Hard Coating Film Using the Same - Google Patents

Abstract

Provided are: a hard coating composition, which comprises a rubber-based impact reinforcing agent with a core-shell structure including a rubber core and a shell of at least one layer, a dendrimer compound having a (meth) acrylate terminal group, a polyfunctional urethane (meth) acrylate having a cyclohexyl group, a polyfunctional (meth) acrylate having an ethylene glycol group, a photoinitiator and a solvent; a hard coating film formed by using the same; and an image display device provided with the hard coating film. The hard coating film according to the present invention has high impact resistance and is excellent in hardness, flexibility and bending resistance, as well as in adhesiveness, curling and cracking properties.

Description

[0001] The present invention relates to a hard coating composition and a 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, to a hard coating composition having excellent hardness and impact resistance as well as flexibility and bending resistance, a hard coating film formed using the composition, And an image display apparatus provided with the same.

The hard coating film is used for surface protection for image display devices such as a liquid crystal display device, an electroluminescence (EL) display device, a plasma display (PD), and a field emission display (FED).

In recent years, a flexible display capable of maintaining the display performance even if bent like paper by using a flexible material such as plastic instead of a conventional glass substrate has rapidly emerged as a next generation display device, and has a high hardness There is a demand for a hard coating film which is not only excellent in scratch resistance but also does not cause a curl phenomenon at the edge of the film during the production process or use and has appropriate flexibility and does not generate cracks.

Korean Patent Laid-Open No. 10-2012-0078457 discloses a hard coating composition comprising an impact modifier, a photopolymerizable compound and a photopolymerization initiator, which comprises a rubber core and at least one shell, wherein the hard coating film Can exhibit excellent scratch resistance, adhesion to a film, impact resistance, solvent resistance, processability and flexibility.

However, the hard coating film has hardness and flexibility sufficient to be applicable to a flexible display device, and it is difficult to secure impact resistance and flexural resistance.

Korean Patent Publication No. 10-2012-0078457

It is an object of the present invention to provide a hard coating composition which can be used in the production of a hard coat film having excellent hardness and impact resistance as well as flexibility and bending resistance.

It is another object of the present invention to provide a hardcoat film formed using the hardcoat composition.

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

On the other hand, the present invention relates to a rubber-based impact modifier having a core-shell structure comprising a rubber core and at least one shell, a dendrimer compound having a (meth) acrylate terminal group, 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 rubber core of the impact modifier may be composed of a rubber elastomer, a polysiloxane rubber elastomer, or a mixture thereof, which is composed of at least one monomer selected from a diene monomer and a (meth) acrylic acid ester monomer have.

In one embodiment of the present invention, the shell of the impact modifier may be composed of at least one member selected from the group consisting of an acrylic resin, a polyester and a polyvinyl carbonate.

In one embodiment of the present invention, the dendrimer compound having the (meth) acrylate end group may include a compound represented by the following formula (1).

[Chemical Formula 1]

[R ₁ ] _4-n -C- [R ₂ -OR ₃ ] _n

In this formula,

R ₁ is a C ₁ -C ₆ alkyl group,

R ₂ is a C ₁ -C ₆ alkylene group,

로서, 적어도 하나의 R₃는

이고, R ₃ is a (meth) acryloyl group or

, At least one R < ₃ >

ego,

로서, 적어도 하나의 R₄는

이며, R ₄ is a (meth) acryloyl group or

, At least one R < ₄ >

Lt;

이고,R ₅ is a (meth) acryloyl group or

ego,

R ₆ is a (meth) acryloyl group,

n is an integer of 2 to 4,

m, x and y are integers of 2 or 3;

In one embodiment of the present invention, the polyfunctional urethane (meth) acrylate having a cyclohexyl group can be prepared by a 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 subjecting a polyhydric alcohol to an addition reaction with ethylene oxide to obtain a polyfunctional alcohol having an ethylene glycol group, and adding (meth) acrylic acid Can be produced by a condensation reaction.

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

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 is a hard coat film comprising a rubber-based impact modifier having a core-shell structure and a dendrimer compound having a (meth) acrylate end group, which comprises a rubber core and at least one shell, When the hard coating film was folded in half so that the gap between the film faces was 6 mm, and then the folded portion was again unfolded, the cracks did not occur or cracks having a length of 5 mm or less were generated. The hard coating film was folded in half so as to have a thickness of 6 mm and then allowed to stand for 24 hours at 85 ° C. and 85% relative humidity. Then, when the folded portion was observed again with naked eyes, cracks were generated or cracks having a length of 5 mm or less Coating film.

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

The hard coating film formed using the hard coating composition according to the present invention is excellent in flexibility and bending resistance as well as in hardness and impact resistance, and excellent in adhesiveness, curling and cracking properties, so that it can be effectively used in a window of a flexible display device .

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

One embodiment of the present invention relates to a rubber-based impact modifier having a core-shell structure including a rubber core and at least one shell, a dendrimer compound having a (meth) acrylate terminal group, a polyfunctional urethane (meth) acrylate having a cyclohexyl group (Meth) acrylate having an ethylene glycol group, a photoinitiator, and a solvent.

In one embodiment of the present invention, a rubber-based impact modifier having a core-shell structure including the rubber core and one or more shells is a component for securing the impact resistance of the hard coat film, 3 to 30% by weight, preferably 5 to 25% by weight. If it is less than 3% by weight, it may be difficult to expect an impact resistance improving effect, and if it exceeds 30% by weight, it may be difficult to secure a sufficient cured coating film.

The polymer constituting the rubber core of the impact modifier is preferably a rubber elastomer composed of at least one kind of monomer selected from a diene monomer and a (meth) acrylic acid ester monomer, a rubber elastomer based on a polysiloxane rubber An elastic body, or a combination thereof. In the present invention, (meth) acryl means acryl and / or methacryl.

The diene monomer (conjugated diene monomer) constituting the rubber elastomer is not particularly limited and includes, for example, butadiene, isoprene, chloroprene and the like. Of these, butadiene is particularly preferable in that the obtained polymer is excellent in the properties as a rubber. The (meth) acrylic acid ester monomer is not particularly restricted but includes, for example, butyl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate and the like, but the obtained polymer has excellent properties as a rubber Particular preference is given to butyl acrylate or 2-ethylhexyl acrylate. These may be used alone or in combination of two or more.

The rubber elastic body may be a copolymer of a diene monomer or a (meth) acrylic acid ester monomer and a vinyl monomer copolymerizable therewith. Examples of the vinyl monomer copolymerizable with the diene monomer or the (meth) acrylic acid ester monomer include aromatic vinyl monomers, vinyl cyanide monomers and the like. Examples of the aromatic vinyl monomer include styrene,? -Methylstyrene, vinylnaphthalene and the like, and examples of the vinyl cyanide monomer include (meth) acrylonitrile, substituted acrylonitrile and the like Is available. These may be used alone or in combination of two or more.

The amount of the diene monomer or (meth) acrylic acid ester monomer to be used may be preferably 50% by weight or more, more preferably 60% by weight or more based on the total weight of the rubber elastic body.

On the other hand, the amount of the monomer copolymerizable therewith is preferably 50% by weight or less, more preferably 40% by weight or less based on the weight of the entire rubber elastic body.

As the rubber core, it is also possible to use a polysiloxane rubber-based elastomer in place of or in combination with the rubber elastomer. When a polysiloxane rubber-based elastomer is used as the rubber core, polysiloxane rubber composed of alkyl or aryl 2-substituted silyloxy units such as dimethylsilyloxy, methylphenylsilyloxy, diphenylsilyloxy and the like can be used.

The shell of the impact modifier may be a polymer layer formed by graft polymerization of a polymer constituting the rubber core.

The shell of the impact modifier may be at least one selected from the group consisting of acrylic resin, polyester and polyvinyl carbonate.

Examples of the acrylic resin include polymers obtained by polymerizing (meth) acrylic acid alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and 2- Lt; / RTI >

The weight ratio of the rubber core / shell of the rubber-based impact modifier having a core-shell structure including the rubber core and one or more shells is preferably in the range of 40/60 to 95/5, more preferably 50/50 to 95/5, 5, and more preferably 60/40 to 85/15.

The refractive index of the impact modifier may be 1.45 to 1.56. If the refractive index of the impact modifier is smaller than 1.45 or larger than 1.56, transparency may be lowered and optical properties may be deteriorated.

The rubber-based impact modifier having a core-shell structure including the rubber core and one or more shells can be produced by polymerizing monomers constituting rubber to form a rubber core and then further graft-polymerizing monomers constituting the shell have.

In one embodiment of the present invention, the dendrimer compound having a (meth) acrylate terminal group can be used for ultraviolet curing by replacing the terminal of the branch structure with a (meth) acrylate group, and the center thereof is completely aliphatic, Ester linkage. Therefore, the dendrimer compound having a (meth) acrylate terminal group has a structural characteristic that it has a functional group with respect to the molecular weight as the generation increases, as compared with the general multifunctional acrylate monomer, and the functional group is distributed at the terminal, Can contribute to the improvement of the bending property. As a result, it is possible to obtain a curl and a hard hard coating film having improved flexibility.

The dendrimer compound may be contained in an amount of 5 to 30% by weight, preferably 10 to 25% by weight based on 100% by weight of the total hard coat composition. If it is less than 5 wt%, it is difficult to exhibit the bending property, and if it is more than 30 wt%, it may be difficult to impart the hardness characteristic to the coating layer due to the presence of unreacted functional groups due to the steric hindrance effect.

In one embodiment of the present invention, the dendrimer compound having the (meth) acrylate terminal group may be represented by the following formula (1): < EMI ID =

[Chemical Formula 1]

[R ₁ ] _4-n -C- [R ₂ -OR ₃ ] _n

In this formula,

R ₁ is a C ₁ -C ₆ alkyl group,

R ₂ is a C ₁ -C ₆ alkylene group,

로서, 적어도 하나의 R₃는

이고, R ₃ is a (meth) acryloyl group or

, At least one R < ₃ >

ego,

로서, 적어도 하나의 R₄는

이며, R ₄ is a (meth) acryloyl group or

, At least one R < ₄ >

Lt;

이고,R ₅ is a (meth) acryloyl group or

ego,

R ₆ is a (meth) acryloyl group,

n is an integer of 2 to 4,

m, x and y are integers of 2 or 3;

As used herein, the C ₁ -C ₆ alkyl group means a linear or branched monovalent hydrocarbon having 1 to 6 carbon atoms, for example, methyl, ethyl, n-propyl, i-propyl, , i-butyl, t-butyl, n-pentyl, n-hexyl, and the like.

As used herein, a C ₁ -C ₆ alkylene group means a linear or branched divalent hydrocarbon having 1 to 6 carbon atoms, and includes, for example, methylene, ethylene, propylene, and butylene. It is not.

In one embodiment of the present invention, the dendrimer compound having the (meth) acrylate terminal group may have a structure represented by the following general formula (2): < EMI ID =

(2)

Dendrimer compounds having the (meth) acrylate end groups are commercially available or can be prepared according to methods known in the art. For example, a first-generation dendrimer structure is formed by condensing a specific polyhydric alcohol with dimethylol propionic acid as a central skeleton, and then dimethylol propionic acid is repeatedly condensed as a branched structure to grow a structure of second generation or more , And a condensation reaction of acrylic acid at the terminal end makes it possible to obtain a dendrimer compound which is highly branched and whose terminals are substituted with a plurality of (meth) acrylate groups.

In one embodiment of the present invention, the polyfunctional urethane (meth) acrylate having a cyclohexyl group is used as a component for improving the mechanical properties, particularly hardness, of a film to be coated, 30% by weight, preferably 10 to 25% by weight. If it is less than 10% by weight, mechanical properties, particularly hardness, may be lowered, and if it is more than 30% by weight, shrinkage may be increased and curling, breaking or cracking of the film may occur.

The polyfunctional urethane (meth) acrylate having a cyclohexyl group can be prepared by condensation reaction of a diisocyanate having a cyclohexyl group with a polyfunctional (meth) acrylate having a hydroxy group.

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

The polyfunctional (meth) acrylate having a hydroxy group may be specifically exemplified by trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, 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 (3) to (4).

(3)

[Chemical Formula 4]

In one embodiment of the present invention, the polyfunctional (meth) acrylate having an ethylene glycol group is used as a component for imparting flexibility to a film to be coated, in an amount of 5 to 30% by weight based on 100% May be included in an amount of 10 to 25% by weight. If it is less than 5% by weight, flexibility may be insufficient, and breakage or cracking of the coating film may occur. If it is more than 30% by weight, mechanical properties may be deteriorated and surface scratches and pencil hardness may be lowered.

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

Specific examples of the polyhydric alcohol include, but are not limited to, glycerol, trimethylol propane, pentaerythritol, dipentaerythritol and the like.

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, trimethylolpropane (EO) ₉ Tri (meth) acrylate, glycerin (EO) ₃ Tri (meth) acrylate, glycerin (EO) ₆ Tri (meth) acrylate, glycerin (EO) ₉ Pentaerythritol (EO) ₄ tetra (meth) acrylate, pentaerythritol (EO) ₈ tetra (meth) acrylate, pentaerythritol (EO) ₁₂ Such as tetra (meth) acrylate, dipentaerythritol (EO) ₆ hexa (meth) acrylate, dipentaerythritol (EO) ₁₂ hexa (meth) acrylate, dipentaerythritol (EO) ₁₈ hexa (meth) acrylate have.

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

[Chemical Formula 5]

[Chemical Formula 6]

In one embodiment of the present invention, the photoinitiator may be used without limitation as long as it is used in the technical field. Type 1 type photoinitiator, in which radicals are generated by decomposition of molecules due to difference in chemical structure or molecular binding energy, and type 2 photoinitiator, which is a hydrogen reclamation type, coexisting with tertiary amines. Specific examples of the Type 1 type photoinitiator include 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyl trichloroacetophenone, diethoxyacetophenone, 2-hydroxy- 2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone and the like, benzoin, benzoin methyl Benzoin ethers such as benzoin ethyl ether and benzyldimethyl ketal, acylphosphine oxides, and titanocene compounds. 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. These may be used alone or in combination of two or more. The Type 1 type photoinitiator and the Type 2 type photoinitiator may be used alone or in combination.

The photoinitiator may be included in an amount of 0.1 to 5% by weight based on 100% by weight of the entire hard coating composition. If the amount is less than 0.1% by weight, the curing may not proceed sufficiently, and the mechanical properties and adhesion of the finally obtained coating film may be deteriorated. When the amount exceeds 5% by weight, cracking and curling due to curing shrinkage may occur.

In one embodiment of the present invention, the solvent can be used without limitation as long as it is used in the technical field. Specific examples of the solvent include alcohols such as methanol, ethanol, isopropanol, butanol and propylene glycol methoxy alcohol, ketones such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone and dipropyl ketone, (Such as methyl acetate, ethyl acetate, butyl acetate and propylene glycol methoxy acetate), cellosolves (methyl cellosolve, ethyl cellosolve and propyl cellosolve), hydrocarbons (normal hexane, normal heptane, benzene, toluene, Etc.). These 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 entire hard coat composition. When the amount is less than 5% by weight, the viscosity is high and the workability is poor. When the amount is more than 90% by weight, the thickness of the coating film is difficult to adjust, and drying unevenness occurs.

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

The inorganic particles may have an average particle diameter of 1 to 100 nm, preferably 5 to 50 nm. Such inorganic particles are uniformly formed in the coating film, and mechanical properties such as abrasion resistance, scratch resistance and pencil hardness can be improved. If the particle size is less than the above range, agglomeration occurs in the composition and a uniform coating film can not be formed. As a result, the above effect can not be expected. On the other hand, if the particle size exceeds the above range, The mechanical properties may be deteriorated.

The material of the inorganic particles 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-Al , Nb ₂ O ₃ , SnO, MgO, and combinations thereof. Al ₂ O ₃ , SiO ₂ , ZrO ₂ and the like can be preferably used. The inorganic particles can be produced directly or commercially available. In the case of commercially available products, those dispersed in an organic solvent at a concentration of 10 to 80% by weight can be used.

The inorganic particles may be contained in an amount of 5 to 40% by weight based on 100% by weight of the entire 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. If it is more than 40% by weight, mechanical properties may be deteriorated and appearance may be deteriorated.

The 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, surfactants, 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 the hard coating composition is coated. Examples of the leveling agent include BYK-323, BYK-331, BYK-333, and BYK-333 manufactured by BYK Corporation, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 440, TEGO Glide 412, BYK- Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300, TEGO Rad 2500, 3M FC-4430 and FC-4432. The leveling agent is preferably used in a range of 0.1 to 1% by weight based on 100% by weight of the entire hard coating composition.

The ultraviolet stabilizer is an additive added for the purpose of protecting the coating film by blocking or absorbing ultraviolet rays because the surface of the cured coating film is decomposed by continuous ultraviolet ray exposure to be discolored and crumbled. The ultraviolet stabilizer may be classified into an absorbent, a quencher, and a hindered amine light stabilizer (HALS) according to the action mechanism. Also, depending on the chemical structure, it is possible to use Phenyl salicylate (absorbent), Benzophenone (absorbent), Benzotriazole (absorber), Nickel derivative (quencher), Radical Scavenger . The ultraviolet stabilizer is not particularly limited as long as it does not significantly change the initial color of the coating film.

The heat stabilizer is a commercially applicable product, and it can be used either alone or in combination with a polyphenol as a primary heat stabilizer, a phosphite as a secondary heat stabilizer, and a lactone system.

The ultraviolet stabilizer and the heat stabilizer can be appropriately used at a level at which the ultraviolet curing property is not affected.

One embodiment of the present invention is directed to a hardcoat film formed using the hardcoat composition described above. The hard coating film according to an embodiment of the present invention is characterized in that a coating layer containing a cured product of the hard coating composition described above 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, cycloolefin-based derivatives having units of monomers including cycloolefins such as norbornene and polycyclic norbornene monomers, cellulose (such as diacetylcellulose, triacetylcellulose, acetylcellulose butylate, isobutylestercellulose, Propylene cellulose, butyryl cellulose and acetyl propionyl cellulose), ethylene vinyl acetate copolymer, polyester, polystyrene, polyamide, polyether imide, polyacryl, polyimide, polyether sulfone, polysulfone, polyethylene, polypropylene, Polyolefins such as polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyethersulfone, polymethylmethacrylate, polyethylene terephthalate, polybutylene terephthalate, Polyethylene naphthalate Polyesters, polycarbonates, polyurethanes, and epoxies. Unstretched, uniaxially or biaxially stretched films can be used.

The thickness of the transparent substrate is not particularly limited, but may be 8 to 1000 탆, specifically 20 to 150 탆. If the thickness of the transparent base material is less than 8 占 퐉, the strength of the film is lowered and the workability is lowered. If the thickness is more than 1000 占 퐉, the transparency is lowered or the weight of the hard coating film is increased.

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

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

After the hard coating composition is applied to the transparent substrate, volatiles are evaporated at a temperature of 30 to 150 ° C for 10 seconds to 1 hour, more specifically for 30 seconds to 30 minutes, And cured. 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.

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

An embodiment of the present invention is a hard coating film comprising a rubber-based impact modifier having a core-shell structure and a dendrimer compound having a (meth) acrylate end group, the rubber core having at least one shell, When the hard coating film is folded in half so that the gap between the faces is 6 mm, and then the folded portion is re-spread and observed with naked eyes, cracks do not occur or cracks having a length of 5 mm or less are generated, The hard coating film was folded in half so as to have a thickness of 6 mm and then allowed to stand for 24 hours at 85 ° C. and 85% relative humidity. Then, when the folded portion was observed again with naked eyes, cracks were generated or cracks having a length of 5 mm or less To a coating film.

In one embodiment of the present invention, the rubber-based impact modifier of the core-shell structure comprising the rubber core and one or more shells may be the same as that used in the hard coating composition described above.

In one embodiment of the present invention, the dendrimer compound having the (meth) acrylate terminal group may be the same as that used in the hard coating composition described above.

The hard coating film according to one embodiment of the present invention includes a rubber-based impact modifier having a core-shell structure including a rubber core and at least one shell, and a dendrimer compound having a (meth) acrylate end group, It is possible to have excellent flex resistance.

One embodiment of the present invention relates to an image display apparatus provided with the above-mentioned hard coating film. For example, the hard coating film of the present invention can be used as an image display device, particularly as a window of a flexible display device. Further, the hard coating film of the present invention may be used by being attached to a polarizing plate, a touch sensor, or the like.

The hard coating film according to one embodiment of the present invention can be used in reflective, transmissive, semi-transmissive LCD or various driving LCDs such as TN type, STN type, OCB type, HAN type, VA type and IPS type. The hard coating 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 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.

Example  1 to 4 and Comparative Example  1 to 3: Hard coating  Preparation of composition

Hard coating compositions were prepared with the compositions shown in Table 1 below (unit: wt%).

Impact modifier (3) 6 Dendrimer Inorganic particle Photoinitiator solvent Example 1 10 10 15 10 20 2 33 Example 2 5 15 10 15 20 2 33 Example 3 5 10 10 20 20 2 33 Example 4 10 10 10 15 20 2 33 Comparative Example 1 - 15 20 10 20 2 33 Comparative Example 2 10 15 20 - 20 2 33 Comparative Example 3 - 20 20 - 25 2 33

Core-shell rubber impact modifier: M211 (Kaneka)

Compound (3) (Shin-A & T, C, SOU-1700B)

Compound (6) (DPEA-126, Japanese explosive)

Dendrimer: SP1106 (Miwon Specialty Chemicals)

Inorganic particles: silica particles, 10-15 nm in particle diameter

Photoinitiator: 1-hydroxycyclohexyl phenyl ketone

Solvent: methyl ethyl ketone

Experimental Example  One:

The hard coating compositions prepared in the above Examples and Comparative Examples were dried on one side of an optical polyimide film (100 탆) to have a thickness of 45 탆, dried in an oven at 110 캜 for 5 minutes, To produce a hardcoat film.

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

(1) Pencil Hardness

Pencil hardness was measured by applying a load of 1 kg using a pencil hardness tester (PHT, Kobo Scientific Co., Ltd.). The pencil was made five times per pencil hardness using Mitsubishi products.

(2) Impact resistance

Steel balls (44 g) were degreased at a height of 50 cm to visually confirm the breakage of the coating film and marked as good and broken.

(3) Adhesion

11 straight lines were drawn on the coated side 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 one of them was not peeled off, it was recorded as 100/100.

(4) Curl

A sample cut into a square shape of A4 size (29.7 x 21.0 cm) was placed on a flat glass plate with the coated side of the film facing up, and the distance from the four-sided glass plate was measured at 25 DEG C and 50% As a measurement value.

(5) Mandrell

In order to evaluate the cracking property, a coated film sample cut into a size of 1 cm × 10 cm was placed on a steel rod of each diameter (2φ to 20φ), and the coating layer was folded by hand to obtain the smallest diameter Respectively.

(6) Flexibility at room temperature

The film was folded in half so that the gap between the faces of the hard coating film (width × length = 10 mm × 100 mm) was 6 mm at room temperature, and then visually confirmed whether cracks were generated in the folded portion when the film was reextended.

<Evaluation Criteria>

◎: No crease occurred in the folded part

○ -A: Creation of crack in folded part (length is 5mm or less, the number is 5 or less)

○ -B: Creation of crack in the folded part (length less than 5mm, number more than 5 but less than 10)

○ -C: Creation of crack in folded part (length less than 5mm, number more than 10)

△ -A: Creation of crack in folded part (length is more than 5mm but less than 10mm, number is not more than 5)

△ -B: Creation of crack in folded part (length is more than 5mm but less than 10mm, number is more than 5 but less than 10)

C: Creation of a folded part (length is more than 5mm but less than 10mm, number is more than 10)

X: Creation of a crack in the folded portion (length greater than 10 mm)

(7) High temperature and high humidity  Flexibility

The film was folded in half so that the gap between the faces of the hard coating film (width × length = 10 mm × 100 mm) was 6 mm, and then the film was left for 24 hours at 85 ° C. and 85% relative humidity. And examined with naked eyes.

<Evaluation Criteria>

◎: No crease occurred in the folded part

○ -A: Creation of crack in folded part (length is 5mm or less, the number is 5 or less)

○ -B: Creation of crack in the folded part (length less than 5mm, number more than 5 but less than 10)

○ -C: Creation of crack in folded part (length less than 5mm, number more than 10)

△ -A: Creation of crack in folded part (length is more than 5mm but less than 10mm, number is not more than 5)

△ -B: Creation of crack in folded part (length is more than 5mm but less than 10mm, number is more than 5 but less than 10)

C: Creation of a folded part (length is more than 5mm but less than 10mm, number is more than 10)

X: Creation of a crack in the folded portion (length greater than 10 mm)

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Pencil hardness 5H 5H 5H 5H 5H B HB Impact resistance Good Good Good Good fracture Good fracture Adhesiveness 100/100 100/100 100/100 100/100 95/100 90/100 95/100 curl 8mm 6mm 7mm 6mm 14mm 16mm 16mm Mandrell 6φ 6φ 8φ 7φ 15φ 15φ 15φ Flexibility at room temperature ◎ ◎ ◎ ○ -A × × × Flexibility in high temperature and high humidity ◎ ◎ ◎ ○ -A × × ×

As shown in Table 2, the hard coating films prepared using the hard coating compositions of Examples 1 to 4 according to the present invention were excellent in hardness, impact resistance, adhesion, curling property, crack resistance and flex resistance. On the other hand, it was confirmed that the hard coating films prepared using the hard coating compositions of Comparative Examples 1 to 3 exhibited decreased hardness, impact resistance, adhesion, curling property, crack resistance or flex resistance. In particular, the hard coating films prepared using the hard coating compositions of Comparative Examples 1 to 3 were found to have poor flexibility at room temperature and high temperature and high humidity.

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 (20)

(Meth) acrylate terminal group, a polyfunctional urethane (meth) acrylate having a cyclohexyl group, an ethylene glycol group, and a rubber-based impact modifier having a core-shell structure including a rubber core and one or more shells A hard coat composition comprising a functional (meth) acrylate, a photoinitiator and a solvent. The hard coating composition according to claim 1, wherein the rubber core of the impact modifier comprises a rubber elastic body composed of a diene monomer and a (meth) acrylic acid ester monomer, a polysiloxane rubber elastomer, or a mixture thereof . The hard coating composition according to claim 1, wherein the shell of the impact modifier comprises at least one member selected from the group consisting of acrylic resin, polyester and polyvinyl carbonate. The hard coating composition according to claim 1, wherein the refractive index of the impact modifier is 1.45 to 1.56. The hard coating composition of claim 1, wherein the dendrimer compound having a (meth) acrylate end group comprises a compound of formula (1): &lt; EMI ID =
[Chemical Formula 1]
[R ₁ ] _4-n -C- [R ₂ -OR ₃ ] _n
In this formula,
R ₁ is a C ₁ -C ₆ alkyl group,
R ₂ is a C ₁ -C ₆ alkylene group,
R ₃ is a (meth) acryloyl group or

, At least one R &lt; ₃ &gt;

ego,
R ₄ is a (meth) acryloyl group or

, At least one R &lt; ₄ &gt;

Lt;
R ₅ is a (meth) acryloyl group or

ego,
R ₆ is a (meth) acryloyl group,
n is an integer of 2 to 4,
m, x and y are integers of 2 or 3; The hard coat composition according to claim 1, wherein the cyclohexyl group-containing polyfunctional urethane (meth) acrylate is produced by condensation reaction of a diisocyanate having a cyclohexyl group with a polyfunctional (meth) acrylate having a hydroxy group. The hard-coating composition according to claim 6, wherein the diisocyanate having a cyclohexyl group is 1,4-cyclohexyl diisocyanate, isophorone diisocyanate or 4,4-dicyclohexylmethane diisocyanate. The composition of claim 6, wherein the polyfunctional (meth) acrylate having a hydroxyl group is trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate or dipentaerythritol penta (meth) . The hard coating composition according to claim 1, wherein the cyclohexyl group-containing polyfunctional urethane (meth) acrylate is at least one selected from the group consisting of compounds represented by the following formulas (3) to (4)
(3)

[Chemical Formula 4]

The method of claim 1, wherein the polyfunctional (meth) acrylate having an ethylene glycol group is obtained by subjecting a polyhydric alcohol to an addition reaction with ethylene oxide to obtain a polyfunctional alcohol having an ethylene glycol group, &Lt; / RTI &gt; The hard coating composition according to claim 10, wherein the polyhydric alcohol is glycerol, trimethylol propane, pentaerythritol or dipentaerythritol. The polyfunctional (meth) acrylate according to claim 1, wherein the polyfunctional (meth) acrylate having an ethylene glycol group is trimethylolpropane (EO) ₃ Tri (meth) acrylate, 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 Pentaerythritol (EO) ₄ tetra (meth) acrylate, pentaerythritol (EO) ₈ tetra (meth) acrylate, pentaerythritol (EO) ₁₂ (Meth) acrylate, dipentaerythritol (EO) ₆ hexa (meth) acrylate, dipentaerythritol (EO) ₁₂ hexa (meth) acrylate and dipentaerythritol (EO) ₁₈ hexa Lt; RTI ID = 0.0 &gt; 1, &lt; / RTI &gt; The hard coating composition according to claim 1, wherein the polyfunctional (meth) acrylate having an ethylene glycol group is at least one selected from the group consisting of compounds represented by the following formulas (5) to (6)
[Chemical Formula 5]

[Chemical Formula 6]

The hard coating composition of claim 1, further comprising inorganic particles. A hardcoat film formed using the hard coating composition of any one of claims 1 to 14. A hard coating film comprising a rubber-based impact modifier having a core-shell structure including a rubber core and at least one shell, and a dendrimer compound having a (meth) acrylate terminal group,
When the hard coating film was folded in half so that the gap between the hard coating film surfaces was 6 mm at room temperature, the folded portions were visually observed at the folded portion, cracks were not generated, cracks less than 5 mm in length were generated,
The hard coating film was folded in half so that the gap between the faces of the hard coating film was 6 mm, and then allowed to stand for 24 hours at 85 ° C and 85% relative humidity. Then, when the folded portion was visually observed, lt; RTI ID = 0.0 &gt; mm. &lt; / RTI &gt; An image display device comprising the hard coating film according to claim 16. A window of a flexible display device comprising a hard coating film according to claim 16. A polarizer plate comprising the hard coating film according to claim 16. A touch sensor comprising the hard coating film according to claim 16.