KR102031660B1 - Hard Coating Composition and Hard Coating Film Using the Same - Google Patents

Abstract

The present invention provides a hard coating composition comprising a dendrimer compound having a (meth) acrylate end group, a polyhedral oligomeric silsesquioxane compound, a photoinitiator and a solvent, a hard coating film formed using the same, and an image provided with the hard coating film. Provide a display device. Hard coating film according to the present invention is excellent in bending resistance as well as hardness and scratch resistance can be minimized curl generation.

Description

Hard coating composition and hard coating film using the same {Hard Coating Composition and Hard Coating Film Using the Same}

The present invention relates to a hard coating composition and a hard coating film using the same, and more particularly, to a hard coating composition having excellent bending resistance as well as hardness and scratch resistance and minimizing curl generation, and a hard coating film formed using the same. And an image display device provided with the hard coating film.

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

Recently, a flexible display device that can maintain display performance even if it is bent like a paper using a flexible material such as plastic instead of a glass substrate without conventional flexibility has emerged as a next-generation display device. In addition to high and good scratch resistance, research has been made on hard-coating films that do not generate curl at the edges of the film during the manufacturing process or use, and have adequate flexibility and no cracks.

Korean Unexamined Patent Publication No. 2013-0135151 discloses a high hardness hard coating composition comprising a binder monomer, an inorganic fine particle, a photoinitiator, and an organic solvent including a 3 to 6 functional acrylate monomer.

However, in the case of such a hard coating composition of high hardness, there was a problem that curl resistance is degraded or hardening occurs after curing.

Republic of Korea Patent Publication No. 2013-0135151

One object of the present invention is to provide a hard coating composition which can be used for the production of a hard coating film having excellent bending resistance as well as hardness and scratch resistance and controlled curling.

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

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

On the other hand, the present invention provides a hard coating composition comprising a dendrimer compound having a (meth) acrylate end group, a polyhedral oligomeric silsesquioxane compound, a photoinitiator and a solvent.

In one embodiment of the present invention, the dendrimer compound having a (meth) acrylate end group may include a compound of Formula 1 below:

[Formula 1]

[R ₁ ] _4-n -C- [R ₂ -OR ₃ ] _n

Where

R ₁ is an alkyl group of C ₁ -C ₆ ,

R ₂ is a C ₁ -C ₆ alkylene group,

R ₃ is a (meth) acryloyl group or Wherein at least one R ₃ is ego,

R ₄ is a (meth) acryloyl group or Wherein at least one R ₄ is Is,

R ₅ is a (meth) acryloyl group or ego,

R ₆ is a (meth) acryloyl group,

n is an integer from 2 to 4,

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

In one embodiment of the present invention, the polyhedral oligomeric silsesquioxane compound may include a compound of Formula 2:

[Formula 2]

Wherein R is each independently a linear, branched or cyclic hydrocarbon having 1 to 20 carbon atoms substituted with hydrogen or a (meth) acrylate group, and at least one is a straight, minute substituted with (meth) acrylate group Topographic or cyclic hydrocarbon having 1 to 20 carbon atoms.

In one embodiment of the present invention, the hard coating composition may further include at least one of a polyfunctional urethane (meth) acrylate having a cyclohexyl group and a polyfunctional (meth) acrylate having an ethylene glycol group.

In one embodiment of the invention, the hard coating composition may further comprise inorganic particles.

In one embodiment of the present invention, the hard coating composition may further include a fluorine-based leveling agent.

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

On the other hand, the present invention is a hard coating film comprising a dendrimer compound having a (meth) acrylate end group and a polyhedral oligomeric silsesquioxane compound, hard coating so that the gap between the surface of the hard coating film is 6mm at room temperature When the film is folded in half and then unfolded and visually observed, the cracks do not occur or cracks of 5 mm or less in length occur, and the hard coat film is folded in half so that the gap between the surfaces of the hard coat film is 6 mm. After standing for 24 hours at 85 ℃ and 85% relative humidity and then again unfolded when observed by the naked eye, it provides a hard coating film that does not generate cracks or cracks less than 5 mm in length.

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

The hard coating film formed by using the hard coating composition according to the present invention can be effectively used in the window of the flexible display device because the hardness and scratch resistance as well as excellent bending resistance can be minimized.

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

One embodiment of the present invention relates to a hard coating composition comprising a dendrimer compound having a (meth) acrylate end group, a polyhedral oligomeric silsesquioxane compound, a photoinitiator and a solvent.

In one embodiment of the present invention, the dendrimer compound having a (meth) acrylate end group can be used for ultraviolet curing by the end of the branched structure is substituted with a (meth) acrylate group, the center of which is completely aliphatic and tertiary Has a structural feature consisting of an ester bond. Therefore, the dendrimer compound having a (meth) acrylate end group has a structural feature that has more functional groups relative to the molecular weight according to the increase of generation compared to the general multifunctional acrylate monomer, and the functional group is distributed at the end to the core part when curing It can contribute to the improvement of this bending characteristic. Accordingly, it is possible to obtain a hardened hard coat film having improved curl and flexibility.

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

[Formula 1]

[R ₁ ] _4-n -C- [R ₂ -OR ₃ ] _n

Where

R ₁ is an alkyl group of C ₁ -C ₆ ,

R ₂ is a C ₁ -C ₆ alkylene group,

R ₃ is a (meth) acryloyl group or Wherein at least one R ₃ is ego,

R ₄ is a (meth) acryloyl group or Wherein at least one R ₄ is Is,

R ₅ is a (meth) acryloyl group or ego,

R ₆ is a (meth) acryloyl group,

n is an integer from 2 to 4,

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

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

As used herein, an alkylene group of C ₁ -C ₆ refers to a straight or branched divalent hydrocarbon having 1 to 6 carbon atoms, and includes, for example, methylene, ethylene, propylene, butylene, and the like. It doesn't happen.

In one embodiment of the present invention, the dendrimer compound having a (meth) acrylate end group may typically have a structure of formula (3):

[Formula 3]

Dendrimer compounds having the (meth) acrylate end groups can be obtained commercially or prepared according to methods known in the art. For example, by condensation reaction with dimethylolpropionic acid using a specific polyhydric alcohol as a main skeleton to form a first generation dendrimer structure, and then repeatedly condensation reaction of the dimethylolpropionic acid as a branched structure to grow into two or more generation structures. By condensation-reacting acrylic acid to an end group, the dendrimer compound highly branched and the terminal substituted by the many (meth) acrylate group can be obtained.

The dendrimer compound may be included in an amount of 10 to 60 wt%, preferably 30 to 45 wt%, based on 100 wt% of the total hard coating composition. If it is less than 10% by weight it is difficult to exhibit the bending characteristics, if it is larger than 60% by weight it may be difficult to give the hardness characteristics to the coating layer due to the presence of unreacted functional groups due to the steric inhibition effect.

In one embodiment of the present invention, the polyhedral oligomeric silsesquioxane (POSS, polyhedral oligomeric silsesquioxane) compounds are compounds represented by formula (2), molecular formula (RSiO _{1 .5) 1} to 5nm size of silica is represented by _n The cage structure is called an organic-inorganic intermediate or a hybrid compound having both properties of silica (SiO ₂ ), which is inorganic, and silicon (R ₂ SiO), which is organic.

[Formula 2]

The polyhedral oligomeric silsesquioxane compound is not particularly limited in number of Si in the structure, and may include, for example, 6 to 12 Si atoms.

In Formula 2, each R is independently a linear, branched or cyclic C1-C20 hydrocarbon substituted with hydrogen or a (meth) acrylate group, and at least one is a straight-chain substituted with a (meth) acrylate group. It may be a branched or cyclic hydrocarbon having 1 to 20 carbon atoms.

Specifically, R may be an alkyl group having 1 to 6 carbon atoms substituted with a (meth) acrylate group, and in particular, may be methacrylate propyl.

Unlike the general inorganic particles, the polyhedral oligomeric silsesquioxane compound can be uniformly mixed even when a large amount is used in the hard coating composition, and can improve hardness and mechanical properties, and also improve bending properties due to structural stability. It has the characteristic to become. In addition, having a (meth) acrylate end group can be used for photocuring, which is advantageous for improving mechanical properties.

The polyhedral oligomeric silsesquioxane compound may be included in an amount of 3 to 20 wt%, preferably 5 to 15 wt%, based on 100 wt% of the total hard coating composition. When it is less than 3% by weight, it is difficult to secure hardness, and when it is larger than 20% by weight, the coating film may be cracked, which may make it difficult to impart bending characteristics.

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

The photoinitiator may be included in 0.1 to 5% by weight, preferably 1 to 3% by weight based on 100% by weight of the total hard coating composition. If less than 0.1% by weight, the curing does not proceed sufficiently, the mechanical properties or adhesion of the final obtained coating film may be lowered, and if more than 5% by weight may cause cracks and curls due to curing shrinkage.

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

The solvent may be included in 5 to 90% by weight, preferably 7 to 85% by weight based on 100% by weight of the total hard coating composition. If the content is less than 5% by weight, the workability is high due to the high viscosity, and if the content is more than 90% by weight, it is difficult to adjust the thickness of the coating film, resulting in poor appearance due to dry spots.

The hard coat composition according to one embodiment of the present invention may further include at least one of a polyfunctional urethane (meth) acrylate having a cyclohexyl group and a polyfunctional (meth) acrylate having an ethylene glycol group.

In one embodiment of the present invention, the polyfunctional urethane (meth) acrylate having a cyclohexyl group is a component for improving the mechanical properties, particularly the hardness of the film to be coated, having a diisocyanate having a cyclohexyl group and a hydroxyl group It can manufacture by condensation reaction of polyfunctional (meth) acrylate.

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

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

In one embodiment of the present invention, the polyfunctional urethane (meth) acrylate having a cyclohexyl group may include at least one member selected from the group consisting of compounds represented by the following Formulas 4 to 5.

[Formula 4]

[Formula 5]

The polyfunctional urethane (meth) acrylate having the cyclohexyl group may be included in 3 to 10% by weight, preferably 5 to 8% by weight based on 100% by weight of the total hard coating composition. If less than 3% by weight may have a decrease in mechanical properties, in particular hardness, if greater than 10% by weight may increase the shrinkage force may cause curling, breaking, cracking of the film.

In one embodiment of the present invention, the polyfunctional (meth) acrylate having the ethylene glycol group is a component for imparting flexibility to the film to be coated, by adding ethylene oxide to the polyhydric alcohol to react the polyfunctional alcohol having an ethylene glycol group It can obtain and can manufacture it by condensation reaction of (meth) acrylic acid with the said polyfunctional alcohol.

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

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

In one embodiment of the present invention, the polyfunctional (meth) acrylate having an ethylene glycol group may include one or more selected from the group consisting of compounds represented by the following formulas (6) to (7).

[Formula 6]

[Formula 7]

The polyfunctional (meth) acrylate having the ethylene glycol group may be included in 3 to 10% by weight, preferably 5 to 8% by weight based on 100% by weight of the total hard coating composition. When less than 3% by weight may cause a breakage or cracking of the coating film due to lack of flexibility, when larger than 10% by weight may cause mechanical properties to deteriorate surface scratches or pencil hardness.

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

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

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 One selected from the group consisting of ₂ O ₃ , SnO and MgO can be used, in particular Al ₂ O ₃ , SiO ₂ , ZrO ₂ and the like can be used.

In one embodiment of the present invention, the inorganic particles may be reactive inorganic particles. The reactive inorganic particles may be one in which an organic compound having at least one polymerizable unsaturated group in a molecule is chemically bonded to the inorganic metal oxide particles. Examples of the polymerizable unsaturated group include acryloyl group, methacryloyl group, vinyl group, propenyl group, butadienyl group, styryl group, cinnamoyl group and the like.

In the reactive inorganic particles, the polymerizable unsaturated group can participate in photocuring, thereby improving abrasion resistance, and suppressing warpage of the hard coat film obtained by reducing the curing shrinkage ratio of the composition for hard coating.

In one embodiment of the present invention, the inorganic particles may be purchased directly and used commercially available. Commercially available products may be used dispersed in a concentration of 10 to 80% by weight in an organic solvent.

The inorganic particles may be included in 5 to 40% by weight relative to the total 100% by weight of the hard coating composition. If it is less than 5% by weight, mechanical properties such as wear resistance, scratch resistance, and pencil hardness may not be sufficient, and when it is more than 40% by weight, the mechanical properties may be deteriorated and the appearance may be poor.

The hard coating composition according to an embodiment of the present invention may further include a leveling agent in order to impart flatness and coating property of the coating film during coating.

The leveling agent may be a commercially available leveling agent in the form of silicon, leveling agent in the form of fluorine, leveling agent in the form of acrylic polymer, and the like, for example, BYK-323, BYK-331, BYK-333, BYK of BK Chemical Co., Ltd. -337, BYK-373, BYK-375, BYK-377, BYK-378, TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300, TEGO Rad 2500, 3M's FC-4430, FC-4432, Shin-Etsu KY-1203, etc. can be used.

In one embodiment of the present invention, the leveling agent may be used in particular in the form of a fluorine in consideration of improving the water resistance. Specifically, a leveling agent in the form of fluorine having at least one polymerizable unsaturated group in the molecule can be used. As said polymerizable unsaturated group, acryloyl group, methacryloyl group, a vinyl group, etc. are mentioned, for example.

The leveling agent may be used in 0.01 to 0.05% by weight relative to the total 100% by weight of the hard coating composition.

In addition to the above components, the hard coating composition according to an embodiment of the present invention may further include components generally used in the art, such as UV stabilizers, heat stabilizers, and the like.

Since the UV stabilizer causes discoloration and brittleness due to decomposition of the surface of the cured coating film by continuous UV exposure, the UV stabilizer may be added to protect the coating film by blocking or absorbing the ultraviolet light. The UV stabilizers are classified into absorbers, quenchers, and hindered amine light stabilizers (HALS) according to functional mechanisms. Depending on the chemical structure, it can be classified into phenyl salicylates (sorbents), benzophenones (sorbents), benzotriazoles (sorbents), nickel derivatives (quenchers), and radical scavengers. Can be. It will not specifically limit, if it is an ultraviolet stabilizer which does not change the initial color of a coating film largely in this invention.

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

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

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

As the transparent substrate, any transparent polymer film can be used. The polymer film may be produced by a film forming method or an extrusion method according to the molecular weight and the film production method, and may be used as long as it is a commercially available transparent polymer film. Examples thereof include triacetyl cellulose, acetyl cellulose butyrate, and ethylene- Vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, polystyrene, polyamide, polyetherimide, polyacryl, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, Polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, Polyethylene naphthalate, pole Various transparent polymer base materials, such as a ricarbonate, are mentioned.

The thickness of the transparent substrate is not particularly limited, but may be 10 to 1000 μm, specifically 20 to 150 μm. If the thickness of the transparent base material is less than 10㎛ the strength of the film is lowered and workability is lowered, if the thickness is more than 1000㎛ transparency problems or the weight of the hard coat film occurs.

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

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

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

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

One embodiment of the present invention is a hard coating film containing a dendrimer compound having a (meth) acrylate end group and a polyhedral oligomeric silsesquioxane compound, the hard coating film so that the gap between the hard coating film surface at a room temperature is 6mm Fold in half and then unfold again when visually observing the folds, no cracks or cracks less than 5 mm in length occur, and the hard coat film is folded in half so that the gap between the surfaces of the hard coat film is 6 mm. The present invention relates to a hard coat film in which no crack is generated or cracks of 5 mm or less in length are generated when the folded part is visually observed after being left for 24 hours at 85 ° C. and 85% relative humidity.

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

In one embodiment of the present invention, the polyhedral oligomeric silsesquioxane compound may be the same as used in the hard coating composition described above.

The hard coat film according to an embodiment of the present invention may have excellent flex resistance under normal temperature and high temperature and high humidity environment by including a dendrimer compound having a (meth) acrylate end group and a polyhedral oligomeric silsesquioxane compound.

One embodiment of the present invention relates to an image display device provided with the hard coating film described above. For example, the hard coat film of the present invention may be used as a window of an image display device, particularly a flexible display device. In addition, the hard coat film of the present invention may be attached to a polarizing plate, a touch sensor, or the like.

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

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

Example  1 to 4 and Comparative example  1 to 2: Hard coating  Preparation of the composition

Each component was mixed with the composition shown in Table 1 below to prepare a hard coating composition (unit: wt%).

Dendrimer Compound Inorganic particles Photoinitiator Fluorine Leveling Agent solvent POSS Formula 4 Formula 7 Example 1 40 40 2 0.03 7.97 5 5 Example 2 45 40 2 0.03 7.97 5 Example 3 30 30 2 0.03 22.97 10 5 Example 4 35 25 2 0.03 12.97 15 5 5 Comparative Example 1 40 40 2 0.03 7.97 5 5 Comparative Example 2 40 2 0.03 17.97 20 10 10

Dendrimer Compound: SP-1106 (Miwon Specialty Chemical)

Inorganic particles: silica particles, particle size 10-15nm

Photoinitiator: 1-hydroxy cyclohexylphenyl ketone

Fluorine Leveling Agent: KY-1203 (Shin-Etsu)

Solvent: Methyl Ethyl Ketone

POSS: MA0736 (Hybrid plastics)

Compound of Formula 4: SOU-1700B (Shin A T & C)

Compound of Formula 7: DPEA126 (Japanese Gunpowder)

Experimental Example  One:

The hard coating composition prepared in Examples and Comparative Examples was coated on one surface of the optical polyimide film (100 μm) to have a thickness of 10 μm, and dried in an oven at 80 ° C. for 5 minutes, followed by 500 mJ in a high pressure mercury lamp. Curing with a light amount to prepare a hard coat film.

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

(1) pencil hardness

Pencil hardness was measured using a pencil hardness tester (PHT, Korea Seokbo Science). Pencils were made using Mitsubishi products, and were carried out five times for each pencil hardness. If there were two or more gis, it was judged bad and recorded as the maximum hardness determined as OK.

(2) Scratch resistance

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

<Evaluation Criteria>

S: 0 scratches

A: 1 to 10 scratches

B: 11-20 scratches

C: 21-30 scratches

D: 31 or more scratches

(3) adhesion

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

Adhesion = n / 100

n: number of rectangles not peeled off

100: total squares

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

(4) curl

After cutting the hard coating film into a size of 10cm × 10cm and left for 24 hours at 25 ℃, 48RH% was measured the average height of the four corners from the bottom. The result was described as follows.

<Evaluation Criteria>

◎: height average of four corners is 20 mm or less

○: height average of the four corners is greater than 20 mm and less than 50 mm

(Triangle | delta): The height average of four corners exceeds 50 mm

×: Four corners are fully lifted and the film curls into a cylinder

(5) room temperature flex resistance

After folding in half so that the space | interval between the surfaces of a hard-coating film (horizontal x length = 10 mm x 100 mm) becomes 6 mm at room temperature, it evaluated by visually confirming whether a crack generate | occur | produced when folded again. The result was described as follows.

<Evaluation Criteria>

◎: No folded part crack

○ -A: crease in crease (5 mm or less in length, 5 or less in number)

○ -B: crease in crease (5 mm or less in length, more than 5 and 10 or less)

○ -C: crease in crease (5 mm or less in length, more than 10)

(Triangle | delta) -A: Fold part crack generation (more than 5 mm in length, 10 mm or less, and number is 5 or less)

(Triangle | delta) -B: Fold part crack generation (more than 5 mm in length and 10 mm or less, and the number is more than 5 and 10 or less)

Δ-C: Folded part crack generation (more than 5 mm in length and less than 10 mm, number more than 10)

×: folded part breaking

(6) High temperature and high humidity  Flex resistance

Fold in half so that the gap between the surfaces of the hard-coating film (width × length = 10mm × 100mm) becomes 6mm, and after leaving the film for 24 hours at 85 ° C and 85% relative humidity, if the film is unfolded, the naked eye It confirmed and evaluated as.

<Evaluation Criteria>

◎: No folded part crack

○ -A: crease in crease (5 mm or less in length, 5 or less in number)

○ -B: Folded part crack occurrence (length 5 mm or less, number more than 5 and 10 or less)

○ -C: crease in crease (5 mm or less in length, more than 10)

(Triangle | delta) -A: Fold part crack generation (more than 5 mm in length, 10 mm or less, and number is 5 or less)

(Triangle | delta) -B: Fold part crack generation (more than 5 mm in length and 10 mm or less, and more than 5 and less than 10 pieces)

Δ-C: Folded part crack generation (more than 5 mm in length and less than 10 mm, number more than 10)

×: folded part breaking

(7) Mandorel

In order to evaluate the bending properties and cracking properties of the coated film, coated film samples cut to a size of 1 cm × 10 cm were placed on the iron bars of each diameter (2φ to 20 φ) and bent by hand with the coating layer upward. The smallest diameter that does not occur is indicated.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Pencil hardness 3H 3H 3H 3H HB HB Scratch resistance A A A A C C Adhesion 100/100 100/100 100/100 100/100 100/100 30/100 curl ◎ ◎ ◎ ◎ △ △ Room temperature flex resistance ◎ ◎ ○ -A ○ -A △ -B × High temperature, high humidity flex resistance ◎ ◎ ○ -A ○ -B △ -C × Mandorel 2φ 2φ 3φ 2φ 15φ 20φ

As shown in Table 2, the hard coating film prepared using the hard coating composition of Examples 1 to 4 according to the present invention is compared with the hard coating film prepared using the hard coating composition of Comparative Examples 1 and 2 It was confirmed that not only the scratch resistance was excellent, but also the flex resistance and the curl generation were suppressed.

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

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

Claims (12)

Hard coating composition for flexible displays containing a dendrimer compound which has a (meth) acrylate terminal group, a polyhedral oligomer silsesquioxane compound, a photoinitiator, and a solvent. The hard coating composition of claim 1, wherein the dendrimer compound having a (meth) acrylate end group comprises a compound of Formula 1 below:
[Formula 1]
[R ₁ ] _4-n -C- [R ₂ -OR ₃ ] _n
Where
R ₁ is an alkyl group of C ₁ -C ₆ ,
R ₂ is a C ₁ -C ₆ alkylene group,
R ₃ is a (meth) acryloyl group or Wherein at least one R ₃ is ego,
R ₄ is a (meth) acryloyl group or Wherein at least one R ₄ is Is,
R ₅ is a (meth) acryloyl group or ego,
R ₆ is a (meth) acryloyl group,
n is an integer from 2 to 4,
m, x and y are integers of 2 or 3. The hard coating composition of claim 1, wherein the polyhedral oligomeric silsesquioxane compound comprises a compound of Formula 2
[Formula 2]

Wherein R is each independently a linear, branched or cyclic hydrocarbon having 1 to 20 carbon atoms substituted with hydrogen or a (meth) acrylate group, and at least one is a straight, minute substituted with (meth) acrylate group Topographic or cyclic hydrocarbon having 1 to 20 carbon atoms. The hard coating composition for flexible display according to claim 1, further comprising at least one of a polyfunctional urethane (meth) acrylate having a cyclohexyl group and a polyfunctional (meth) acrylate having an ethylene glycol group. The hard coating composition of claim 1, further comprising inorganic particles. The hard coating composition of claim 1, further comprising a fluorine-based leveling agent. Hard coating film formed using the hard coating composition for flexible display according to any one of claims 1 to 6. As a hard coat film for flexible displays containing the dendrimer compound which has a (meth) acrylate terminal group, and a polyhedral oligomeric silsesquioxane compound,
When the hard coat film is folded in half so that the gap between the surfaces of the hard coat film is 6 mm at room temperature, when the folded portion is unfolded and visually observed, the crack does not occur or a crack of 5 mm or less in length occurs.
When the hard coat film was folded in half so that the gap between the surfaces of the hard coat film was 6 mm, and left standing at 85 ° C. and 85% relative humidity for 24 hours, then the unfolded part was visually observed and no cracks occurred. Hard-coating film for flexible display that cracks below mm occur. An image display device provided with the hard coating film for flexible display according to claim 8. A window of a flexible display device provided with the hard coating film for flexible display according to claim 8. A polarizing plate provided with a hard coating film for flexible display according to claim 8. Touch sensor with a hard coating film for a flexible display according to claim 8.