KR20170040598A - Hard coating composition and hard coating film formed therefrom - Google Patents

Abstract

The present invention relates to a hard coating composition and a hard coating film formed therefrom, and specifically, to a hard coating composition comprising: an isosorbide acrylate compound represented by chemical formula 1; a urethane (meta) acrylate-based compound containing a cycloalkyl part; a polyfunctional (meta) acrylate-based compound containing an oxyethylene group; and a photoinitiator, and to a hard coating film formed therefrom. The hard coating film according to the present invention exhibits high hardness and high flexibility at the same time, thereby suitably being applied to a flexible video display device.

Description

TECHNICAL FIELD [0001] The present invention relates to a hard coating composition and a hard coating film formed therefrom. BACKGROUND OF THE INVENTION < RTI ID = 0.0 >

The present invention relates to hard coating compositions and hard coating films formed therefrom.

Mobile devices that can bend or fold beyond curved smartphones that are simply curved in the near future will appear on the market.

Normally, in the case of a display, a cover window made of a glass material is provided at the outermost side to protect the display. However, glass can not be applied to a foldable display.

Accordingly, there is a demand for a hard hard coating film which can replace the glass of the cover window.

However, as the surface hardness of a conventional hard coating film increases, curl due to curing shrinkage occurs, and when applied to a flexible display, flexibility is lowered, cracks may occur, and flexibility may be lowered.

For example, Korean Patent Laid-Open Publication No. 2008-0055698 mentions that hardness can be increased while presenting a multi-layered hard-coating optical film, but no countermeasures against cracks are presented at all.

Korean Patent Laid-Open Publication No. 2001-0129253 discloses a photocurable dianhydrohexanehexol derivative, a process for preparing the same, and a photocurable composition containing the same, wherein a composition containing an isosorbide-based compound is disclosed. However, Flexibility and hardness are insufficient.

Therefore, development of a hard coating composition capable of imparting a high surface hardness while maintaining the flexibility of the base film is required.

Korean Patent Publication No. 2008-0055698 Korea Patent Publication No. 2012-0129253

An object of the present invention is to provide a hard coating composition which is excellent in hardness and can impart flexibility.

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

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

Another object of the present invention is to provide a window of a flexible display device provided with the hard coating film.

Disclosure of the Invention The present invention has been made to solve the above problems, and it is an object of the present invention to provide a film having a high hardness and scratch resistance and having excellent flexibility as a film obtained by using a hard coating composition containing a specific acrylate compound Thereby completing the invention.

An embodiment of the present invention relates to an isosorbide acrylate compound represented by the following general formula (1); Urethane (meth) acrylate-based compounds containing a cycloalkyl moiety; A polyfunctional (meth) acrylate-based compound containing an oxyethylene group; ≪ / RTI > and a photoinitiator.

[Chemical Formula 1]

Wherein R ₁ and R ₂ are the same or different and each independently a group containing a (meth) acrylic group.

An embodiment of the present invention also includes a substrate film; And a coating layer formed on at least one side of the base film, wherein the coating layer is formed from the hard coating composition described above.

An embodiment of the present invention also provides an image display device provided with the above-mentioned hard coating film.

Yet another embodiment of the present invention provides a window of a flexible display device provided with the above-mentioned hard coating film.

By incorporating an isosorbide acrylate compound into a hard coating composition, it is possible to produce a hard coating film having improved hardness while maintaining a flexible property.

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

Whenever a part is referred to as "including " an element in the present invention, it is to be understood that it may include other elements as well, without departing from the other elements unless specifically stated otherwise.

The hard coating composition according to the present invention comprises an isosorbide acrylate compound represented by the following formula (1): A urethane (meth) acrylate-based compound containing a cycloalkyl moiety; A polyfunctional (meth) acrylate-based compound containing an oxyethylene group; And a photoinitiator.

[Chemical Formula 1]

Wherein R ₁ and R ₂ are the same or different and each independently a group containing a (meth) acrylic group.

Isosobaid series Acrylate  compound

The isosorbide-based compound represented by the formula (1) is a photo-curable compound having an isosorbide derived dianhydrohexane-1,2,3,4,5,6-hexanol skeleton The compound has a flexible and rigid structural characteristic by a double ring. Therefore, when a hard coating film is prepared using the hard coating composition comprising the isosorbide-based compound represented by Formula 1, it is possible to produce a hard coating film having improved hardness and flexibility.

R ₁ and R ₂ may be the same or different and each independently a group containing a (meth) acrylic group.

In the present invention, the group containing a (meth) acrylic group may be referred to as a case where a part of the functional group includes a methacryl group or an acrylic group. For example, the group containing a (meth) acrylic group may be an alkyl group substituted with a (meth) acrylic group or a (meth) acrylic group itself.

The formula (1) may be represented by the following formula (1-1) or (1-2).

[Formula 1-1]

[Formula 1-2]

The isosorbide compound represented by Formula 1-1 may be prepared by the following reaction scheme, but is not limited thereto.

[Reaction Scheme 1]

For example, the isosorbide compound represented by Formula 1-2 may be prepared by reacting an isoboside compound with an epibromohydrin to obtain a bifunctional isosorbide compound, followed by reacting with acrylic acid.

When the isosorbide epoxy compound and methacrylic acid are reacted in the above reaction formula, the isosorbide compound represented by the general formula (1-2) can be prepared, but is not limited thereto.

The isosorbide acrylate compound may be contained in an amount of 5 to 35 parts by weight, specifically 5 to 30 parts by weight, more specifically 10 to 30 parts by weight, based on the total weight of the hard coating composition. When the isosorbide acrylate compound is contained within the above range, it is possible to prevent the coating layer from being broken and to impart a bending property while having excellent hardness characteristics.

A urethane (meth) acrylate-based compound containing a cycloalkyl moiety

When the urethane (meth) acrylate compound is contained in the hard coating composition, sufficient hardness and scratch resistance can be secured.

The hard coating composition may comprise a urethane (meth) acrylate based compound comprising a cycloalkyl moiety. The term "including a cycloalkyl moiety" may refer to a case where a part of the compound includes a cycloalkyl moiety. For example, the cycloalkyl moiety may be a monovalent cycloalkyl group, or a divalent cycloalkylene group, and the cycloalkyl moiety may be mono- or polysubstituted or unsubstituted. When the cycloalkyl moiety is substituted, the substituent may be an alkyl group such as methyl, ethyl, propyl, or a halogen group such as fluoro, chloro or bromo. The urethane (meth) acrylate resin containing the cycloalkyl moiety may be a polyfunctional compound.

The cycloalkyl group is not particularly limited, but preferably has 3 to 40 carbon atoms. Specific examples include cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, and the like, but are not limited thereto.

The cycloalkylene group is not particularly limited, but preferably has 3 to 40 carbon atoms. Specifically, the cycloalkylene group may be a cyclic alkylene group such as cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, methylcyclopentylene, dimethylcyclopentylene, methylcyclohexylene, dimethylcyclohexylene , Cyclohexylene, and the description of the above-mentioned cycloalkyl group can be applied, except that the cycloalkylene group is a divalent group.

When the hard coating composition comprises a urethane (meth) acrylate-based compound containing the cycloalkyl moiety, it is possible to produce a hard coat film having improved mechanical properties. Specifically, when a hard coating film containing a hard coating layer containing a urethane (meth) acrylate compound containing the cycloalkyl moiety is prepared, it is possible to produce a hard coating film having an improved hardness.

The urethane (meth) acrylate compound containing the cycloalkyl moiety can be prepared by condensation reaction of a diisocyanate having a cycloalkyl group with a polyfunctional (meth) acrylate having a hydroxy group, but is not limited thereto.

The diisocyanate may include at least one of the group consisting of 1,4-cyclohexyl diisocyanate, isophorone diisocyanate, and 4,4-dicyclohexylmethane diisocyanate.

The multifunctional (meth) acrylate containing a hydroxy group includes at least one of trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate and dipentaerythritol penta (meth) acrylate .

The cycloalkyl group may be a cyclohexyl group. That is, the urethane (meth) acrylate compound containing the cycloalkyl moiety of the present invention may be a urethane (meth) acrylate compound containing a cyclohexyl group.

The urethane (meth) acrylate-based compound containing the cycloalkyl moiety may be represented by the following general formula (2) or (3).

(2)

(3)

When the urethane (meth) acrylate includes the cycloalkyl moiety, there is an advantage that the hardness can be improved due to rigidity of the molecular structure of the cycloalkyl group. In addition, since the compound is stable to light as compared with an aryl group such as a phenyl group, there is an advantage that a hard coat composition having excellent optical characteristics can be produced.

The urethane (meth) acrylate compound containing the cycloalkyl moiety may be contained in an amount of 20 to 70 parts by weight, specifically 30 to 70 parts by weight based on the total weight of the hard coating composition. When the urethane (meth) acrylate compound containing the cycloalkyl moiety is contained within the above range, the phenomenon of deterioration of the mechanical properties can be prevented. In particular, there is an advantage in that it is possible to produce a hard coat film having excellent hardness. In addition, there is an advantage that the phenomenon of curling, breaking, cracking, etc. of the film can be prevented by preventing the phenomenon that the shrinking force is increased.

Oxyethylene group  Included Multifunctional  ( Meta ) Acrylate series  compound

The polyfunctional (meth) acrylate-based compound containing the oxyethylene group is included for imparting flexibility.

The polyfunctional (meth) acrylate-based compound containing oxyethylene group can be used without any limitations as commonly used in the art. The polyfunctional (meth) acrylate-based compound containing oxyethylene group is preferably selected from the group consisting of trimethylol propane (EO) ₃ tri (meth) acrylate, trimethylol propane (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, dipentaerythritol (EO) ₁₂ hexa (meth) acrylate and dipentaerythritol (EO) ₁₈ hexa (meth) acrylate.

Specifically, the polyfunctional (meth) acrylate compound containing an oxyethylene group may 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 then condensing (meth) acrylic acid with the polyfunctional alcohol But it is not limited thereto.

The polyfunctional alcohol may be a polyhydric alcohol, and specifically may be glycerol, trimethylol propane, pentaerythritol, or dipentaerythritol, but is not limited thereto.

The polyfunctional (meth) acrylate compound having oxyethylene group may be represented by the following general formula (4) or (5).

[Chemical Formula 4]

[Chemical Formula 5]

When the hard coating composition contains the polyfunctional (meth) acrylate compound, there is an advantage that a coating layer having improved durability can be produced. When the polyfunctional (meth) acrylate compound includes the oxyethylene group, flexibility There is also an advantage that can be given.

The content of the oxyethylene group-containing polyfunctional (meth) acrylate compound is preferably 10 to 70 parts by weight, more preferably 10 to 60 parts by weight, and still more preferably 20 to 60 parts by weight, based on the total weight of the hard coating composition, May be included in the coating composition, but are not limited thereto. When the oxyalkylene group-containing polyfunctional (meth) acrylate compound is contained within the above range, it is possible to produce a hard coating film having excellent durability and flexibility. When the oxyethylene group-containing polyfunctional (meth) acrylate compound satisfies the above range, it is possible to realize mechanical properties such as pencil hardness or scratch resistance and to prevent the shrinkage of the hard coating film from becoming large, And cracks can be prevented.

Photoinitiator

The photoinitiator can be applied without limitation as long as it is generally used in the art. Specifically, the photoinitiator may be a Type 1 initiator in which a radical is generated by decomposition of a molecule due to a difference in chemical structure or molecular binding energy, and a hydrogen recycle type Type 2 initiator coexisting with a tertiary amine.

Specific examples of the Type 1 initiator include 4-phenoxy dichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyl trichloroacetophenone, diethoxyacetophenone, 2- Methylpropane-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2- Acetophenones such as methylpropane-1-one, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone and 1-hydroxycyclohexylphenylketone, benzoin, Benzoates such as methyl ether, benzoin ethyl ether and benzyl dimethyl 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 ' Methyl-4-methoxybenzophenone and the like, benzophenones such as thioxanthone, 2-chromothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone and isopropylthioxanthone Oxanone, and the like.

These photoinitiators may be used alone or in combination of two or more. Type 1 and Type 2 may be used alone or in combination.

The photoinitiator may be included in an amount of 0.1 to 20 parts by weight, specifically 0.1 to 15 parts by weight, based on the total weight of the hard coating composition. When the photoinitiator is included within the above range, there is an advantage that hardness can be improved through polymerization between the compounds contained in the hard coating composition without affecting flexibility. In addition, there is an advantage that productivity can be improved by giving an appropriate curing time. Particularly, when a sufficient curing time is given, the final obtained coating film is excellent in mechanical properties, excellent adhesion can be achieved, curing shrinkage phenomenon can be prevented, and problems such as poor adhesion, breakage and curling can be prevented have.

additive

An embodiment of the present invention may also include the coating composition may further include an additive, and the additive may include at least one of the group consisting of inorganic nanoparticles, leveling agent, and stabilizer.

(1) Inorganic nanoparticles

The inorganic nanoparticles may be optionally added to improve the hardness of the hard coating layer. Specifically, when the inorganic nanoparticles are contained in the coating composition, there is an advantage that the mechanical properties can be further improved. More specifically, the inorganic nanoparticles are uniformly formed in the coating film, and the mechanical properties such as abrasion resistance, scratch resistance and pencil hardness can be improved.

The inorganic nanoparticles may have an average particle diameter of 1 to 100 nm, specifically 1 to 80 nm, more specifically 5 to 50 nm. When the average particle diameter of the inorganic nanoparticles satisfies the above range, there is an advantage that a uniform coating film can be formed by preventing coagulation in the composition. Further, it is possible to prevent the problem that the optical properties and the mechanical properties of the coating film are deteriorated.

The inorganic nanoparticles are _{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. The metal oxide may include, but is not limited to, metal oxides commonly used in the art.

Specifically, the inorganic nanoparticles may be Al ₂ O ₃ , SiO ₂ , or ZrO ₂ . The inorganic nanoparticles may be prepared directly or commercially available ones. In the case of commercially available products, the inorganic nanoparticles may be dispersed in an organic solvent at a concentration of 10 to 80% by weight.

The inorganic nanoparticles may be included in an amount of 20 to 70 parts by weight based on the total weight of the hard coating composition. When the inorganic nanoparticles are contained in an amount of 20 to 70 parts by weight based on 100 parts by weight of the entire hard coating composition, mechanical properties such as abrasion resistance, scratch resistance and pencil hardness can be excellent and workability Is increased, and the phenomenon that appearance becomes poor can be prevented.

(2) Leveling agent

The leveling agent may include at least one of a silicone leveling agent, a fluorine leveling agent, and an acrylic leveling agent. When the leveling agent is included in the hard coating composition, smoothness and coating properties can be imparted when the coating film is formed.

Specifically, the leveling agent may be selected from the group consisting of BYK-323, BYK-331, BYK-333, BYK-337, BYK-375, BYK-377, BYK-378, TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, 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, , FC-4430 and FC-4432 manufactured by 3M Company. However, the present invention is not limited thereto, and leveling agents conventionally used in the art can be applied.

The leveling agent may be included in an amount of 0.1 to 3 parts by weight based on the total weight of the hard coating composition, but is not limited thereto. However, when the leveling agent is contained in the hard coating composition within the above range, the smoothness and coatability of the coating film are maximized, and the hardness and flexibility can be maintained excellent.

(3) Stabilizer

The stabilizer may be a hindered amine type; Phenyl salicylate system; Benzophenone type; Benzotriazole systems; Nickel derivatives; Radical scavenger; Polyphenolics; Phosphite system; And a lactone-based stabilizer.

In the present invention, the ultraviolet stabilizer means an additive added for the purpose of shielding or absorbing ultraviolet rays to protect the adhesive since 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 Salicylates (absorbent), Benzophenone (absorbent), Benzotriazole (absorber), Nickel derivative (quencher), Radical Scavenger .

In the present invention, there is no particular limitation as long as it is an ultraviolet stabilizer that does not largely change the initial color of the adhesive.

The heat stabilizer is a commercially applicable product, and can be used either singly or as a mixture of 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.

The stabilizer may be included in an amount of 0.1 to 10 parts by weight based on the total weight of the hard coating composition, but is not limited thereto. When the stabilizer is contained within the above range with respect to the total weight of the hard coating composition, it is possible to prevent the surface of the cured coating film from being decomposed by the ultraviolet rays without lowering the hardness and flexibility, There is an advantage not to be.

solvent

The solvent is not limited as long as it is capable of dissolving or dispersing the above-mentioned composition and is known as a solvent of a composition for forming a coating layer 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 parts by weight, specifically 10 to 80 parts by weight, more specifically 20 to 70 parts by weight, based on the total weight of the hard coating composition. When the solvent is contained within the above range, it is possible to obtain a hard coating composition having an appropriate viscosity, thereby increasing the workability, controlling the thickness of the coating film easily, preventing the occurrence of drying unevenness, It is possible.

The hard coating composition according to the present invention may contain, in addition to the above-mentioned components, an optical stimulant, an antioxidant, a UV absorber, a light stabilizer, a thermal polymerization inhibitor, An activator, an antioxidant lubricant, an antifouling agent, and the like. At this time, selection and content control of each additive can be suitably selected by those skilled in the art.

In the present invention, there is provided a hard coat film produced using the composition for hard coating described above. The hard coating film according to the present invention comprises a hard coating layer formed by applying the above-mentioned composition for hard coating onto one side or both sides of a transparent substrate and then curing.

The hard coating film prepared using the hard coating composition according to the present invention exhibits excellent hardness and flexibility.

The base film is not limited as long as it is a transparent polymer film.

In the present invention, the term "transparent" means that the transmittance of the visible ray is 70% or more or 80% or more. Incidentally, the case where the entire area is not transparent and the aperture ratio is 60% or more may be included.

The polymer film may be manufactured by a film-forming method or an extrusion method according to a manufacturing method, but is not limited thereto. Specifically, the transparent polymer film may be a cycloolefin-based derivative having a unit of a monomer including a cycloolefin such as norbornene or a polycyclic norbornene monomer, a cellulose (diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, iso Propyl cellulose, butyryl cellulose, acetyl propionyl cellulose), ethylene vinyl acetate copolymer, polyester, polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyether sulfone, polysulfone, polyethylene , Polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutyl Ren Terephthal Sites may be used polyethylene naphthalate, polycarbonate, polyurethane, and can be selected from among epoxy, non-stretched, uniaxially or biaxially stretched film.

More specifically, among the transparent substrates exemplified above, monoaxially or biaxially stretched polyester films excellent in transparency and heat resistance, cycloolefin-based derivative films excellent in transparency and heat resistance and capable of coping with the enlargement of the film, transparent and optically anisotropic A triacetylcellulose film having no transparency and a low transparency and a low cost acrylic copolymer film can be suitably used. However, the present invention is not limited thereto, and a substrate including a transparent plastic generally used in the art can be appropriately selected and used .

Plasma or corona treatment may be performed before forming the coating layer on the base film, but the present invention is not limited thereto. When the pretreatment such as plasma or corona treatment is performed on the base film, adhesion between the coating layer and the base film is increased. The plasma or corona treatment may be performed by a method commonly used in the art.

The thickness of the base film may be 8 to 1000 탆, specifically 40 to 100 탆. When the thickness of the base film is in the above-mentioned range, the strength of the film is high, so that the workability is excellent and the transparency is prevented from being lowered, and the hard coating film can be lightened.

The coating layer can be produced using the hard coating composition described above. Specifically, the coating layer may be formed by a suitable method such as die coater, air knife, reverse roll, spray, blade, casting, gravure, microgravure, and spin coating.

The thickness of the coating layer may be 3 占 퐉 to 200 占 퐉, specifically 10 占 퐉 to 100 占 퐉, more specifically, 20 占 퐉 to 30 占 퐉, but is not limited thereto. However, when the thickness of the coating layer satisfies the above range, there is an advantage that a hard coating film having excellent hardness, flexibility, thinning, and hardly causing curling phenomenon can be produced. The thickness of the coating layer may be referred to as the thickness after drying.

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

The hard coating film according to the present invention contains the above-mentioned isosorbide acrylate compound, the urethane (meth) acrylate compound containing the cycloalkyl moiety, and the polyfunctional (meth) acrylate compound containing the oxyethylene group It has an advantage of being excellent in hardness and having flexibility.

The hard coating film may be used for a flexible display. Specifically, the hard coating film may be used for a display such as LCD, OLED, LED, FED or various mobile communication terminals using the same, a cover glass for a touch panel or an electronic paper of a smart phone or a tablet PC Or as a functional layer.

The present invention provides an image display apparatus having the hard coating film. Further, the present invention provides a window of a flexible display device provided with the hard coating film.

Hereinafter, the present invention will be described in detail by way of examples to illustrate the present invention. However, the embodiments according to the present disclosure can be modified in various other forms, and the scope of the present specification is not construed as being limited to the above-described embodiments. Embodiments of the present disclosure are provided to more fully describe the present disclosure to those of ordinary skill in the art.

Example  1 to 7 and Comparative Example  1 to 5: For hard coating  Preparation of composition

Hard coating compositions were prepared with the ingredients as shown in Table 1 below.

Composition Example Comparative Example One 2 3 4 5 6 7 One 2 3 4 5 Isosorbide acrylate compound (1-1) 6 9 4.5 3 1.5 3 - - - - - 6 1-2 3 - 4.5 3 4.5 3 6 - - - - SOU-1700B 12 - 9 - 21 - - - - - - 3 SOU-1290 - 12 - 12 - 21 18 - - 18 - M4004 9 9 - - - - - 15 15 - 18 DPEA-126 - - 12 12 3 3 6 - - 12 12 6 UA-306H - - - - - - - 15 - - - 15 M-340 - - - - - - - - 15 - - Nanopol 764 30 30 30 30 30 30 30 30 30 30 30 30 Photoinitiator Iga Cure 184 5 5 5 5 5 5 5 5 5 5 5 5 BYK-333 3 3 3 3 3 3 3 3 3 3 3 3 solvent MEK 30 30 30 30 30 30 30 30 30 30 30 30 Toluene 10 10 10 10 10 10 10 10 10 10 10 10

SOU-1700B: Shin-A T & C SOU-1700B (formula 2)

SOU-1290: Shin-A T & C SOU-1290 (formula 3)

M4004: Means specific chemical (Formula 4)

DPEA-126: Japanese chemistry (Chemical formula 5)

UA-306H: Copolymer (Formula 6)

[Chemical Formula 6]

(7)

Nanopol 764: Evonics, PGMEA 50% diluted 20 nm silica sol

Igar Cure 184: BASF Corp.

BYK-333: Kei Kei Misawa

MEK: Methyl ethyl ketone (Samcheon Chemical Co.)

Toluene: Toluene (Samcheon Chemical Co.)

Experimental Example

Each of the hard coating compositions prepared in Examples and Comparative Examples was coated on one side of an optical polyimide film (Mitsubishi Gas Chemical Co., Ltd., 100 占 퐉, L-3430) to have a thickness of 20 占 퐉. Thereafter, the resultant was dried in an oven at 80 ° C for 2 minutes, and cured at 350 mJ in a high-pressure mercury lamp to produce a hardcoat film.

The properties of the thus-prepared hard coating film were measured as follows. The results are shown in Table 2 below.

(1) 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 a Mitsubishi product and was run five times per pencil hardness test. If the number of cigarettes was two or more, it was judged to be defective and the maximum hardness judged to be good was recorded.

Kiss: 0 Good

Kiss: 1 Good

Gas: 2 or more defective

(2) Scratch resistance

The 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.). Steel wool # 0000 was used and it was judged whether or not the surface was scratched.

S: 0 scratches

A: 1 to 10 scratches

B: 11-20 scratches

C: 21 ~ 30 scratches

D: 21 ~ 30 scratches

(3) 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 their average values were recorded and the results are shown in Table 2 below. The adhesion measurement standard is as follows. That is, when none of them were peeled off, they were marked with 100/100.

Adhesion = n / 100

n: Number of unfixed rectangles of the entire rectangle

100: total number of squares

(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 glass plates was measured at 25 DEG C and 50% RH, The results are shown in Table 2 below.

(5) Mandrell

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

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Pencil hardness 6H 3H 6H 6H 5H 5H 5H H 2H H H H Abrasion resistance S B S S A A A C C C C C Adhesiveness 100/100 90/100 100/100 100/100 100/100 100/100 100/100 70/100 65/100 72/100 64/100 70/100 curl 2mm 7mm 2mm 2mm 5mm 5mm 4mm 15mm 12mm 15mm 20mm 15mm Mandrell 6φ 9φ 6φ 6φ 7φ 5φ 6φ 10φ 10φ 10φ 10φ 10φ

Referring to Table 2, it can be seen that the hard coating film of the examples is excellent in pencil hardness and scratch resistance and is a hard hard coating film. However, it can be seen that the coating film according to the comparative example is not excellent in both pencil hardness and scratch resistance.

In addition, it was confirmed that the hard coating film of the example had excellent adhesion in the peeling test, but the coating film according to the comparative example was found to have significantly lower adhesion than the hard coating film according to the example.

In addition, the hard coating films according to the examples showed excellent effects both in the curl test and the mandolell test, and in particular, in the Mandrel test for testing the flexibility and crack resistance, the hard coating films had better performance than the comparative coating films .

Claims (15)

An isosorbide acrylate compound represented by the following formula (1);
A urethane (meth) acrylate-based compound containing a cycloalkyl moiety;
A polyfunctional (meth) acrylate-based compound containing an oxyethylene group; And
A hardcoat composition comprising a photoinitiator:
[Chemical Formula 1]

Wherein R ₁ and R ₂ are the same or different and each independently a group containing a (meth) acrylic group. The method according to claim 1,
Wherein the urethane (meth) acrylate compound containing the cycloalkyl moiety is prepared by condensation reaction of a diisocyanate containing a cycloalkyl moiety and a polyfunctional (meth) acrylate containing a hydroxy group. 3. The method of claim 2,
Wherein said diisocyanate comprises at least one of the group consisting of 1,4-cyclohexyl diisocyanate, isophorone diisocyanate and 4,4-dicyclohexylmethane diisocyanate. 3. The method of claim 2,
The polyfunctional (meth) acrylate containing a hydroxyl group includes at least one member selected from the group consisting of trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol penta (meth) ≪ / RTI > The method according to claim 1,
The polyfunctional (meth) acrylate-based compound containing oxyethylene group is preferably selected from the group consisting of trimethylol propane (EO) ₃ tri (meth) acrylate, trimethylol propane (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, dipentaerythritol (EO) ₁₂ hexa (meth) acrylate and dipentaerythritol (EO) ₁₈ hexa (meth) acrylate. The method according to claim 1,
Wherein the coating composition further comprises a solvent. The method according to claim 1,
Characterized in that the coating composition further comprises an additive,
Wherein said additive comprises at least one of the group consisting of inorganic nanoparticles, leveling agents and stabilizers. 8. The method of claim 7,
The inorganic nanoparticles are _{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. ≪ RTI ID = 0.0 > 11. < / RTI > 8. The method of claim 7,
Wherein the leveling agent comprises at least one of a silicone leveling agent, a fluorine leveling agent, and an acrylic leveling agent. 8. The method of claim 7,
The stabilizer may be a hindered amine type; Phenyl salicylate system; Benzophenone type; Benzotriazole systems; Nickel derivatives; Radical scavenger; Polyphenolics; Phosphite system; And a lactone-based stabilizer. The method according to claim 1,
Based on the total weight of the hard coating composition,
5 to 35 parts by weight of the isosorbide acrylate compound;
20 to 70 parts by weight of a urethane (meth) acrylate compound containing the cycloalkyl moiety;
10 to 70 parts by weight of a polyfunctional (meth) acrylate compound containing the oxyethylene group; And
And 0.1 to 20 parts by weight of the photoinitiator. The method according to claim 6,
Based on the total weight of the hard coating composition,
≪ / RTI > wherein said solvent comprises from 5 to 90 parts by weight. A base film; And
And a coating layer formed on at least one surface of the base film,
Wherein the coating layer is formed from the hard coating composition of any one of claims 1 to 12. An image display apparatus comprising the hard coating film according to claim 13. A window of a flexible display device comprising the hard coating film according to claim 13.