TW201819547A - 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 terminal (meth)acrylate group, a polyhedral oligomeric silsesquioxane compound, a photoinitiator and a solvent; a hard coating film formed using the same; and an image display device having the hard coating film. The hard coating film according to the present invention can minimize the occurrence of curling while having excellent hardness, scratch resistance and bending resistance.

Description

Hard coating composition and hard coating film using same

The present invention relates to a hard coating composition and a hard coating film using the same. In particular, the present invention relates to a hard coating composition capable of minimizing the occurrence of curl and having excellent hardness, scratch resistance and bending resistance, a hard coating film formed by applying the same, and An image display device having the hard coating film.

Hard-coated films have been used to protect the surfaces of various video displays, including a liquid crystal display (LCD), an electroluminescent display (EL), a plasma display (PD), a field emission display (FED), and the like Surface.

Recently, by using a flexible material, such as plastic, instead of a traditional non-flexible glass substrate, the flexible display device can maintain display performance even if a flexible display device is bent like paper. It has attracted attention as a next-generation display device. In this regard, there is a need for a hard coating film that not only has high hardness and good scratch resistance, but also has appropriate flexibility so that cracks do not occur, and no curling occurs at the edges of the film during production or use.

Korean Patent Application Publication No. 10-2013-0135151 discloses a high-hardness hard-coating composition, which includes a binder containing tri-functional to hexa-functional acrylate monomers, and inorganic fine particles ( inorganic fine particles), a photoinitiator and an organic solvent.

However, a problem with this high-hardness hard coating composition is that the bending resistance after curing is reduced and curling occurs.

The object of the present invention is to provide a hard coating composition, which can be used in the production of a hard coating film. The hard coating film can suppress the occurrence of curl and has excellent hardness, scratch resistance, and bending resistance.

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

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

According to an aspect of the present invention, a hard coating composition is provided, including: a dendrimer compound having a terminal (meth) acrylate group, and a polyhedron. A polyhedral oligomeric silsesquioxane compound, a photoinitiator, and a solvent.

In an embodiment of the present invention, the dendrimer compound having a terminal (meth) acrylate group may include a compound represented by the following Chemical Formula 1. [Chemical Formula 1] [R ₁ ] _4-n -C- [R ₂ -OR ₃ ] _n wherein 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 And at least one R ₃ is R ₄ is mono (meth) acrylfluorenyl or And at least one R ₄ is R ₅ is mono (meth) acrylfluorenyl or R ₆ is a (meth) acrylfluorenyl group, n is an integer from 2 to 4, and m, x, and y are an integer from 2 or 3.

In one embodiment of the present invention, the polyhedral siloxane oligomer compound may include a compound represented by the following Chemical Formula 2. [Chemical Formula 2] Wherein, each R is independently hydrogen, or a straight chain, branched chain, or cyclic hydrocarbon group having 1 to 20 carbon atoms substituted by a (meth) acrylate group, and at least one of them One R is a straight chain, branched chain or cyclic hydrocarbon group having 1 to 20 carbon atoms substituted with a mono (meth) acrylate group.

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

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

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

In another aspect, the present invention provides a hard coating film formed using the hard coating composition.

In another aspect, the present invention provides a hard coating film comprising: a dendrimer compound having a terminal (meth) acrylate group and a polyhedral siloxane oligomer compound, wherein when the hard coating film is folded in half to When the distance between the film surfaces at room temperature is 6 millimeters (mm), the film will spread again and the folded portion can be observed by the naked eye, no cracks are generated or there is no length of 5 mm (mm) ) Or cracks less than 5 mm; and when the hard coating film is folded in half so that the distance between the film surfaces is 6 mm (mm), the film can be left for 24 hours at 85 ° C and 85% relative humidity The film will be unfolded again and the folded part can be observed by the naked eye, no cracks are generated or no cracks with a length of 5 mm (mm) or less are generated.

According to another aspect of the present invention, an image display device having the hard coating film is provided.

The hard coating film formed by using the hard coating composition according to the present invention can minimize the occurrence of curl and has excellent hardness, scratch resistance and bending resistance. This hard coating film can be effectively used in a A window of a flexible display device.

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

An embodiment of the present invention relates to a hard coating composition, including: a dendrimer compound having a terminal (meth) acrylate group, a polyhedral siloxane oligomer compound, and a photoinitiator. With a solvent.

In one embodiment of the present invention, the dendrimer compound having a terminal (meth) acrylate group can be cured by ultraviolet rays by replacing the terminal of the branch structure with a (meth) acrylate group. This dendrimer compound having one terminal (meth) acrylate group has a structural characteristic of a completely aliphatic center, and is composed of a tertiary ester bond. Therefore, compared with general polyfunctional acrylate monomers, this dendrimer compound having a terminal (meth) acrylate group has a structural characteristic. The higher the molecular weight in production, the more functional groups it has. . Since this functional group is distributed at the terminal, the core portion can help improve the bending property during curing. Therefore, a hard coating film having high hardness and improved bending characteristics and flexibility can be obtained.

In one embodiment of the present invention, the dendrimer compound having a terminal (meth) acrylate group may be represented by the following Chemical Formula 1: [Chemical Formula 1] [R ₁ ] _4-n -C- [R ₂ -OR ₃ ] _n wherein R ₁ is a C ₁ -C ₆ alkyl group, R ₂ is a C ₁ -C ₆ alkylene group, and R ₃ is a mono (meth) acryl group or And at least one R ₃ is R ₄ is mono (meth) acrylfluorenyl or And at least one R ₄ is R ₅ is mono (meth) acrylfluorenyl or R ₆ is a (meth) acrylfluorenyl group, n is an integer from 2 to 4, and m, x, and y are an integer from 2 or 3.

As used herein, C ₁ -C ₆ alkyl refers to a straight or branched chain monovalent hydrocarbon group having 1 to 6 carbon atoms, and examples thereof include methyl, ethyl, n-propyl, isopropyl, n- Butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, and the like are not limited thereto.

The C ₁ -C ₆ alkylene group used herein refers to a straight or branched chain divalent hydrocarbon group having 1 to 6 carbon atoms, and examples thereof include methylene, ethylene, propylene, butene, and the like, but Not limited to this.

In one embodiment of the present invention, the dendrimer compound having a terminal (meth) acrylate group may generally have a structure represented by the following Chemical Formula 3. [Chemical Formula 3]

This dendrimer compound having a terminal (meth) acrylate group may be commercially available or may be prepared according to a method known in the art. For example, obtaining highly branched dendrimers with multiple (meth) acrylate groups at the ends can be achieved by combining the central skeleton of a specific polyol with dimethylolpropane The dimethylol propionic acid undergoes a condensation reaction to form a first-generation dendritic structure, and the dimethylolpropionic acid is repeatedly subjected to a condensation reaction to a branch structure to grow into a second-generation or more Generation of dendritic structure and condensation reaction of acrylic acid at the end.

Based on 100% of the total weight of the hard coating composition, the dendritic polymer compound may contain 10 to 60% by weight, preferably 30 to 45% by weight. When the dendrimer is less than 10% by weight, it is difficult to exhibit bending characteristics. When the dendrimer is more than 60% by weight, unreacted functional groups are generated due to steric hindrance effect. It may be difficult to give the coating a hardness characteristic.

In one embodiment of the present invention, the polyhedral siloxane oligomer compound (POSS) is a compound represented by the following Chemical Formula 2, and has a size of 1 to 5 nanometers (nm) represented by the molecular formula (RSiO _1.5 ) _n . A silica cage structure. The silica dioxide cage structure is regarded as an organic / inorganic intermediate compound or hybrid compound having the characteristics of silicon dioxide (SiO ₂ , an inorganic material) and polysilicon oxide (R ₂ SiO, an organic material). [Chemical Formula 2]

In the polyhedral siloxane oligomer compound, the number of Si in the structure is not particularly limited, and may be 6 to 12, for example.

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

Specifically, R may be a monoalkyl group having 1 to 6 carbon atoms substituted with a mono (meth) acrylate group, and may particularly be propyl methacrylate.

Unlike ordinary inorganic particles, even when polyhedral oligomer silsesquioxane compounds are used in large amounts in a hard coating composition, polyhedral siloxane oligomer compounds can be synthesized uniformly. Polyhedral siloxane oligomer compounds can improve hardness and mechanical properties, and can improve bending characteristics due to structural stability. In addition, since the polyhedral siloxane oligomer compound has a terminal (meth) acrylate group, the polyhedral siloxane oligomer compound can be used for photocuring to improve mechanical properties.

Based on 100% of the total weight of the hard coating composition, the polyhedral siloxane oligomer compound may contain 3 to 20% by weight, preferably 5 to 15% by weight. When the weight of the polyhedral siloxane oligomer compound is less than 3%, it may be difficult to obtain hardness. When the weight of the polyhedral siloxane oligomer compound is more than 20%, the coating film may be broken, so it is difficult to give bending characteristics .

In one embodiment of the present invention, as long as the initiator is commonly used in the technical field, a photo-initiator may be used without particular limitation. Photoinitiators can be classified as type I photoinitiators, where free radicals are generated by molecular decomposition due to differences in chemical structure or molecular binding energy. Photoinitiators can be classified as type II (hydrogen abstraction type) photoinitiators, in which the tertiary amine is combined into a co-initiator. Specific examples of the type I photoinitiator may include acetophenone, such as 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone , 4-t-butyltrichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl-1-acetone (2 -hydroxy-2-methyl-l-phenylpropan-1-one), 1- (4-isopropylphenyl) -2-hydroxy-2-methyl-1-acetone (1- (4-isopropylphenyl) -2 -hydroxy-2-methylpropan-1-one), 1- (4-dodecylphenyl) -2-hydroxy-2-methyl-1-acetone (1- (4-dodecylphenyl) -2-hydroxy- 2-methylpropan-1-one), 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone (4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2- propyl) ketone), 1-hydroxycyclohexyl phenyl ketone or the like, benzoins, such as benzoin, benzoin methyl ether, benzoin ether ( benzoin ethyl ether), benzyl dimethyl ketal or the like, acylphosphine oxides, and Titanocene compounds. Specific examples of the type II photoinitiator may include benzophenones, such as benzophenone, benzoyl benzoic acid, benzoyl benzoic acid methyl ether , 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3'-dimethyl-4-methoxybenzophenone (3,3'-dimethyl-4-methoxybenzophenone) or the like; and thioxanthones, such as thioxanthone ), 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone Keto (isopropylthioxanthone) or the like. These photoinitiators may be used alone or in a combination of two or more of them. In addition, a Type I light initiator can be used together with a Type II light initiator.

Based on 100% of the total weight of the hard coating composition, the photoinitiator may contain 0.1 to 5% by weight, preferably 1 to 3% by weight. If the weight of the photo-initiator is less than 0.1%, curing may not be sufficiently performed, and thus the mechanical properties or adhesion of the hard coating film finally obtained may be reduced. If the weight of the photoinitiator is more than 5%, cracking or curling may occur during curing shrinkage.

In one embodiment of the present invention, as long as it is a solvent commonly used in the technical field, the solvent may be used without particular limitation. Specific examples of the solvent may include alcohols (methanol, ethanol, isopropanol, butanol, propylene glycol methyl ether, etc.), ketones (e.g., methyl ethyl ketone, methyl butyl ketone, methyl Isobutyl ketone, diethyl ketone, dipropyl ketone, etc.), acetate (methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxy acetate, etc.), cellulosic Cellosolves (methyl cellosolve, ethyl cellosolve, propyl cellosolve, etc.), hydrocarbons (n-hexane, n-heptane, benzene, toluene , Xylene, etc.) and the like. These solvents may be used alone or in a combination of two or more of them.

Based on 100% of the total weight of the hard coating composition, it may contain 5 to 90% by weight of the solvent, preferably 7 to 85% by weight. If the weight of the solvent is less than 5%, the viscosity may increase and processability may be deteriorated. If the weight of the solvent is more than 90%, it may be difficult to adjust the thickness of the coating film, and drying unevenness may occur, causing appearance defects.

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

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, hardness) of the film to be coated. This polyfunctional urethane (meth) acrylate having a cyclohexyl group can be produced by a condensation reaction of a diisocyanate having a cyclohexyl group and a polyfunctional (meth) acrylate having a hydroxy group.

Specific examples of the diisocyanate having a monocyclohexyl group may include 1,4-cyclohexyl diisocyanate, isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate (4,4-dicyclohexylmethane diisocyanate) and the like, but are not limited thereto.

Specific examples of the polyfunctional (meth) acrylate having a monohydroxy group may include trimethylolpropane di (meth) acrylate, pentaerythritol tri (pentaerythritol tri (meth) acrylate meth) acrylate), dipentaerythritol penta (meth) acrylate, and the like, but not limited thereto.

In one embodiment of the present invention, the polyfunctional urethane (meth) acrylate having a cyclohexyl group may include at least one selected from the group consisting of compounds represented by the following chemical formulae 4 and 5. [Chemical Formula 4] [Chemical Formula 5]

Based on 100% of the total weight of the hard coating composition, the polyfunctional urethane (meth) acrylate having a cyclohexyl group may contain 3 to 10% by weight, and preferably 5 to 8% by weight. When the weight of the polyfunctional urethane (meth) acrylate is less than 3%, the mechanical properties (particularly hardness) may decrease. When the weight of the multifunctional urethane (meth) acrylate is greater than 10%, the shrinking force will become large, and thus curling, cracking, cracking, etc. may occur on the film.

In one embodiment of the present invention, the polyfunctional (meth) acrylate having a glycol group is a component for imparting flexibility to a film to be coated. Addition reaction of ethylene oxide with a polyhydric alcohol to obtain a polyfunctional alcohol with a glycol group, and then condensation reaction of (meth) acrylic acid with the polyfunctional alcohol, This polyfunctional acrylate having a glycol group was prepared.

This polyhydric alcohol may be, but is not limited to, glycerol, trimethylol propane, pentaerythritol, dipentaerythritol, and the like.

Polyfunctional (meth) acrylate, specific examples include trimethylolpropane (ethylene oxide) glycol having a group of _three tri (meth) acrylate _{(trimethylol propane (EO) 3 tri} (meth) acrylate ), Trimethylol propane (ethylene oxide) ₆ tri (meth) acrylate (trimethylol propane (EO) ₆ tri (meth) acrylate), trimethylol propane (ethylene oxide) ₉ tris (a yl) acrylate _{(trimethylol propane (EO) 9 tri} (meth) acrylate), glycerin (ethylene oxide) ₃ tri (meth) acrylate _{(glycerin (EO) 3 tri (} meth) acrylate), glycerol Alcohol (ethylene oxide) ₆ tri (meth) acrylate, glycerin (EO) ₆ tri (meth) acrylate, glycerin (ethylene oxide) ₉ tri (meth) acrylate (glycerin (EO) ₉ tri (meth) acrylate), pentaerythritol (ethylene oxide) ₄ pentaerythritol (EO) ₄ tetra (meth) acrylate, pentaerythritol (ethylene oxide) ₈ tetra (meth) acrylate ester _{(pentaerythritol (EO) 8 tetra (} meth) acrylate), pentaerythritol (ethylene oxide) ₁₂ tetra (meth) acrylate _{(pentaerythritol (EO) 12 tetra (} meth) acrylate), dipentaerythritol (ethylene oxide) ₆ hexa (meth) acrylate (dipentae _{rythritol (EO) 6 hexa (meth} ) acrylate), dipentaerythritol (ethylene oxide) ₁₂ hexa (meth) acrylate _{(dipentaerythritol (EO) 12 hexa (} meth) acrylate), dipentaerythritol (ethylene oxide) ₁₈ Hexa (meth) acrylate (dipentaerythritol (EO) ₁₈ hexa (meth) acrylate) and the like.

In one embodiment of the present invention, the polyfunctional acrylate having a glycol group may include at least one selected from the group consisting of compounds represented by the following chemical formulae 6 to 7. [Chemical Formula 6] [Chemical Formula 7]

Based on 100% of the total weight of the hard coating composition, the polyfunctional (meth) acrylate having a monoethylene glycol group may contain 3 to 10% by weight, preferably 5 to 8% by weight. When the weight of the polyfunctional (meth) acrylate is less than 3%, flexibility may be insufficient, and thus cracks or cracks may occur in the coating film. When the weight of the polyfunctional (meth) acrylate is more than 10%, the mechanical properties may be deteriorated, so scratches may be produced on the surface or pencil hardness may be reduced.

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

The inorganic particles may have an average particle diameter of 1 to 100 nanometers (nm), preferably 5 to 50 nanometers (nm). These inorganic particles are uniformly formed in the coating film and can improve mechanical properties such as abrasion resistance, scratch resistance, and pencil hardness. If the particle size is smaller than the above range, agglomeration will occur in the composition, so a uniform coating film cannot be formed and the above-mentioned expected effects cannot be obtained. On the other hand, if the particle diameter exceeds the above range, not only the optical properties of the finally obtained coating film may be deteriorated, but also the mechanical properties may be deteriorated.

These inorganic particles can be metal oxides, one of which can be selected from alumina (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), zinc oxide (ZnO), zirconium dioxide (ZrO ₂ ), and barium titanate ( BaTiO ₃ ), titanium dioxide (TiO ₂ ), tantalum pentoxide (Ta ₂ O ₅ ), titanium trioxide (Ti ₃ O ₅ ), indium tin oxide (ITO), indium zinc oxide (IZO), tin antimony oxide ( ATO), zinc aluminum oxide (ZnO-Al), niobium trioxide (Nb ₂ O ₃ ), stannous oxide (SnO) and magnesium oxide (MgO). In particular, alumina (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), zirconium dioxide (ZrO ₂ ), and the like can be used.

In one embodiment of the present invention, the inorganic particles may be reactive inorganic particles. The active inorganic particle may be an organic compound having at least one polymerizable unsaturated group in a molecule of the active inorganic particle, and the organic compound forms a chemical bond with inorganic metal oxide particles. Examples of the polymerizable unsaturated group include an acrylyl group, a methacrylyl group, a vinyl group, a propenyl group, a butadienyl group, and a styryl group group), cinnamoyl group and the like.

In this active inorganic particle, the polymerizable unsaturated group can participate in photo-curing to improve abrasion resistance, and at the same time, can reduce the curing shrinkage of the hard coating composition to suppress warpage of the hard coating film.

This inorganic particle can be produced directly or obtained from the market. For commercial products, inorganic particles having a concentration of 10 to 80% by weight can be dispersed in an organic solvent.

The inorganic particles may contain 5 to 40% by weight based on 100% of the total weight of the hard coating composition. When the weight of the inorganic particles is less than 5%, the mechanical properties of the coating film such as abrasion resistance, scratch resistance, and pencil hardness may be insufficient. When the weight of the inorganic particles exceeds 40%, it will interfere with the curing ability and cause the deterioration of mechanical properties, and there will be appearance defects.

The hard coating composition according to an embodiment of the present invention may further include a leveling agent to provide smoothness and coating property of the coating film during coating of the composition.

As the leveling agent, commercially available silicon-type, fluorine-type, and acrylic polymer-type leveling agents can be selected and used. For example, BYK-323, BYK-331, BYK-333, BYK-337, BYK-373, BYK-375, BYK-377, BYK-378 (BYK Chemie, BYK Chemical Company), 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 (Degussa), FC-4430, FC-4432 (3M), KY-1203 (Shin-Etsu, Shin-Etsu Chemical Industry) or the like.

In one embodiment of the present invention, in consideration of improving water resistance, the leveling agent may be a fluorine-based leveling agent. Specifically, a fluorine-based leveling agent having at least one polymerizable unsaturated group in the molecule can be used. Examples of the polymerizable unsaturated group include acrylfluorenyl, methacrylfluorenyl, vinyl, and the like.

The leveling agent may be contained in an amount of 0.01 to 0.05% by weight based on 100% by weight of the hard coating composition.

In addition to the above components, the hard coating composition according to one embodiment of the present invention may further include components commonly used in the art, such as an ultraviolet stabilizer, a thermal stabilizer, and the like.

Because the surface of the cured coating film is decomposed by continuous exposure to ultraviolet rays, the surface of the cured coating film will be discolored and cracked. A UV stabilizer may be added to protect the coating film by blocking or finely collecting the ultraviolet rays. Ultraviolet stabilizers can be classified into absorbers, quenchers, and hindered amine light stabilizers (HALS) according to their mechanism of action. Similarly, UV stabilizers can be classified into phenyl salicylate (absorber), benzophenone (absorber), benzotriazole (absorber), and nickel derivatives according to their chemical structure. (nickel derivative) (matting agent) and free radical scavenger. The ultraviolet light stabilizer is not particularly limited as long as the initial color of the coating film is not significantly changed.

Thermal stabilizer is a product that can be applied to commerce, and polyphenol type (first-class thermal stabilizer), phosphite type (second-level thermal stabilizer), and lactone type ( lactone type) can be used alone or in combination.

Ultraviolet stabilizers and heat stabilizers can be used by appropriately adjusting the content thereof to a level that does not affect ultraviolet curability.

An embodiment of the present invention relates to forming a hard coating film using the hard coating composition described above. A hard coating film according to an embodiment of the present invention is characterized in that a coating of a cured product containing the hard coating composition is formed on one surface or both surfaces of a transparent substrate.

For the transparent substrate, any polymer film having transparency can be used. Depending on the molecular weight and production method of the film, the polymer film can be produced by a film-forming method or an extrusion method. As long as it is a commercially available transparent polymer film, there are no restrictions on its use.

Examples include various transparent polymer substrates such as triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer , Propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, polystyrene, polyamine, polyether imide ), Polyacryl, polyimide, polyether sulfone, polyfluorene, polyethylene, polypropylene, polymethyl pentene, polyvinyl chloride, polyvinylidene chloride , Polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polymethyl methacrylate, polyethylene terephthalate, poly Polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and the like.

The thickness of the transparent substrate is not particularly limited, but may be 10 to 1000 micrometers (mm), specifically 20 to 150 micrometers (mm). When the thickness of the transparent substrate is less than 10 micrometers (mm), the strength of the film is reduced, and thus the processability is also reduced. When the thickness of the transparent substrate is greater than 1000 micrometers (mm), the transparency may decrease or the weight of the hard coating film may increase.

The hard coating composition of the present invention can be applied on one or both surfaces of a transparent substrate to produce a hard coating film according to an embodiment of the present invention, and then cured to form a coating.

By using a conventional coating process as appropriate, such as die coater, air knife, reverse roll, spray, knife, casting, gravure, micro gravure coating, spin coating Etc., coating a hard coating composition according to an embodiment of the present invention on a transparent substrate.

After applying the hard coat composition on the transparent substrate, a drying process may be performed by evaporating volatile substances at a temperature of 10 to 1 hour, more specifically 30 seconds to 30 minutes, and 30 to 150 ° C. UV curing is then performed. The ultraviolet curing can be performed by ultraviolet irradiation of 0.01 to 10 J / cm ² , especially 0.1 to 2 J / cm ² .

At this time, the formation thickness of the coating layer may be specifically 2 to 30 micrometers (mm), and more specifically 3 to 20 micrometers (mm). When the thickness of the coating is within the above range, a coating with excellent hardness can be obtained.

An embodiment of the present invention relates to a hard coating film, including: a dendrimer compound having a terminal (meth) acrylate group and a polyhedral siloxane oligomer compound, wherein when the hard coating film is folded in half So that the distance between the film surfaces at room temperature is 6 millimeters (mm), the film will be unfolded again and the folded part can be observed with the naked eye, no cracks or cracks with a length of 5 mm (mm) or less will be generated. And when the hard coating film is folded in half so that the distance between the film surfaces is 6 millimeters (mm), the film can be left at 85 ° C and 85% relative humidity for 24 hours, and the film will unfold again and can be seen with the naked eye. It was observed that the folded portion did not generate cracks or cracks having a length of 5 millimeters (mm) or less.

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

In one embodiment of the present invention, the polyhedral siloxane oligomer compound may be the same as the polyhedral siloxane oligomer compound used in the hard coat composition.

Since the hard coating film according to an embodiment of the present invention includes a dendrimer compound having a terminal (meth) acrylate group and a polyhedral siloxane oligomer compound, the hard coating film can be used at room temperature. Excellent resistance to bending in high temperature-high humidity environments.

An embodiment of the present invention relates to an image display device having the hard coating film. For example, the hard coating film of the present invention can be used as a window of an image display device, particularly a window of a flexible display. Furthermore, the hard coating film of the present invention can be used by attaching to a polarizing plate, a touch sensor, or the like.

The hard coating film according to an embodiment of the present invention can be used for liquid crystal devices (LCDs) in various operation modes, including reflective, transmissive, transflective, and twisted nematic. (TN), super-twisted nematic (STN), optically compensated bend (OCB), hybrid-aligned nematic (HAN), vertical alignment , VA) -type and in-plane switching (IPS) liquid crystal devices (LCDs). In addition, the hard coating film according to an embodiment of the present invention can be used in various image display devices, including plasma displays, field emission displays, organic EL displays, and inorganic EL displays. display), electronic paper, and the like.

Hereinafter, the present invention will be described in more detail based on examples, comparative examples, and experimental examples. Those with ordinary knowledge in the technical field should know that these examples, comparative examples, and experimental examples are merely illustrative, and are not intended to limit the present invention.

Examples 1 to 4 and Comparative Examples 1 to 2: Preparation of Hard Coating Composition

A hard coat composition was prepared by mixing each of the ingredients and compositions shown in Table 1. (Unit:% by weight) [Table 1] Dendrimer: SP-1106 (Miwon Specialty Chemicals) Inorganic particles: silica particles, particle diameter 10-15 nanometers (nm) Light initiator: 1- 1-hydroxycyclohexyl phenyl ketone Fluorine leveling agent: KY-1203 (Shin-Etsu) Solvent: Methyl ethyl ketone POSS: MA0736 (Hybrid plastics )) Compound of Chemical Formula 4: SOU-1700B (Shin-A T & C) Compound of Chemical Formula 7: DPEA126 (Nippon Kayaku)

Experimental Example 1:

The hard coating composition prepared in the examples and comparative examples was applied onto one surface of a polyimide film (100 micrometers (mm)) in an oven at 80 ° C. After 5 minutes of drying, the hard coating composition was made to have a thickness of 10 micrometers (mm), and the hard coating composition was exposed to 500 mJ of light from a high pressure mercury lamp. Curing is performed to prepare a hard coating film.

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

(1) Pencil hardness

Pencil hardness was measured by applying a load of 500 grams (g) using a pencil hardness tester (PHT, Korea Sukbo Science). A pencil made by Mitsubishi Corporation was used, and the hardness of the hard coating film was measured five times. When two or more scratches are found, the hard coating film is judged as a defective product, and the maximum hardness determined to pass the test is recorded.

(2) Scratch resistance

By reciprocating 10 times using a steel wool tester (WT-LCM100, Korea Protec) under a load of 1 kg (2 cm (cm) x 2 cm (cm)) Test for scratch resistance. The steel wool used is # 0000. <Evaluation Criteria> S: 0 scratches A: 1 to 10 scratches B: 11 to 20 scratches C: 21 to 30 scratches D: 31 scratches or more

(3) Adhesiveness

On the coated surface of the film, 11 straight lines spaced 1 mm apart were drawn horizontally and vertically to create 100 regular squares. A tape (CT-24, Nichiban Co., Ltd., Japan) was then used to perform three peeling tests. Perform three hundred grid tests and record the average. The adhesion record is as follows. Adhesiveness = n / 100 n: The number of squares that did not fall out of all squares 100: The total number of squares Therefore, when no squares fall off, it will be recorded as 100/100.

(4) Curl

The hard coating film cut into a size of 10 cm (cm) x 10 cm (cm) was left at a temperature of 25 ° C and a relative humidity of 48% for 24 hours. Then, a curl value was obtained by measuring the average height of the hard coating film from the bottom to the four edges. The results are explained below. <Evaluation Criteria> ⊚: The average height of the four edges is equal to or less than 20 millimeters (mm) ◯: The average height of the four edges is greater than 20 millimeters (mm) and equal to or less than 50 millimeters (mm) Δ: The average of the four edges Height greater than 50 millimeters (mm) X: The four edges are completely lifted up, and the film is curled into a cylindrical shape.

(5) Bending resistance at room temperature

Fold the hard coating film in half (width x length = 10 millimeters (mm) x 100 millimeters (mm)) so that the distance between the film surfaces is 6 millimeters (mm). Then, the film was unrolled again, and it was possible to determine whether the folded portion had cracks with the naked eye, thereby evaluating the bending resistance of the film. The results are explained below. <Evaluation Criteria> ◎: There are no cracks in the folded part ○ -A: There are cracks in the folded part (length equal to or less than 5 millimeters (mm), and the number is 5 or less) ○ -B: folded part The occurrence of cracks (length equal to or less than 5 millimeters (mm), and the number is greater than 5 and equal to or less than 10) ○ -C: the occurrence of cracks in the folded portion (length equal to or less than 5 millimeters (mm), and The number is greater than 10) △ -A: The folded part has cracks (length greater than 5 millimeters (mm) and equal to or less than 10 millimeters (mm), and the number is equal to or less than 5) △ -B: the folded part has The occurrence of cracks (length greater than 5 millimeters (mm) and equal to or less than 10 millimeters (mm), and the number is greater than 5 and equal to or less than 10) △ -C: The folded part has cracks (length greater than 5 mm ( mm) and equal to or less than 10 millimeters (mm), and the number is greater than 10) ×: The folded part has cracks

(6) Bending resistance under high temperature and high humidity

Fold this hard coating film in half (width x length = 10 millimeters (mm) x 100 millimeters (mm)) so that the distance between the film surfaces is 6 millimeters (mm), and make the film at 85 ° C and 85% Store at relative humidity for 24 hours. Then, the film is unfolded again, and the cracks of the folded portion can be determined with the naked eye to evaluate the bending resistance of the film. <Evaluation Criteria> ◎: There are no cracks in the folded part ○ -A: There are cracks in the folded part (length equal to or less than 5 millimeters (mm), and the number is 5 or less) ○ -B: folded part The occurrence of cracks (length equal to or less than 5 millimeters (mm), and the number is greater than 5 and equal to or less than 10) ○ -C: the occurrence of cracks in the folded portion (length equal to or less than 5 millimeters (mm), and The number is greater than 10) △ -A: The folded part has cracks (length greater than 5 millimeters (mm) and equal to or less than 10 millimeters (mm), and the number is equal to or less than 5) △ -B: the folded part has The occurrence of cracks (length greater than 5 millimeters (mm) and equal to or less than 10 millimeters (mm), and the number is greater than 5 and equal to or less than 10) △ -C: The folded part has cracks (length greater than 5 mm ( mm) and equal to or less than 10 millimeters (mm), and the number is greater than 10) ×: The folded part has cracks

(7) mandrel

In order to evaluate the bending characteristics and cracking properties of the coating film, a coated film sample cut into a size of 1 cm (cm) x 10 cm (cm) was placed at each diameter (2 ɸ-20 ɸ). ) On an iron rod. With the coated layer facing up and folded by hand, indicate the minimum diameter of the surface where no cracks occur. 【Table 2】

As shown in Table 2, the hard coating films prepared according to the hard coating compositions used in Examples 1 to 4 of the present invention have excellent hardness, scratch resistance, and bending resistance, and are better than those used in Comparative Examples 1 to 2. The hard coating film prepared by the hard coating composition can suppress the occurrence of curl.

Although the above embodiments have been disclosed in the present invention, those with ordinary knowledge in the technical field to which this invention pertains may know that these contents only disclose preferred embodiments, and the scope of protection of the present invention is not limited thereto. Those with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention.

Therefore, the protection scope of the present invention shall be determined by the scope of the attached patent application.

no

no

Claims (12)

A hard coating composition includes a dendrimer compound having a terminal (meth) acrylate group, and a polyhedral siloxane oligomer compound. oligomeric silsesquioxane compound), a photoinitiator and a solvent. The hard coating composition according to item 1 of the scope of patent application, wherein the dendrimer compound having a terminal (meth) acrylate group includes a compound represented by the following Chemical Formula 1: [Chemical Formula 1] [R ₁ ] _4-n -C- [R ₂ -OR ₃ ] _n wherein R ₁ is a C ₁ -C ₆ alkyl group, R ₂ is a C ₁ -C ₆ alkylene group, and R ₃ is a (methyl ) (Meth) acryloyl group or And at least one R ₃ is R ₄ is mono (meth) acrylfluorenyl or And at least one R ₄ is R ₅ is mono (meth) acrylfluorenyl or R ₆ is a (meth) acrylfluorenyl group, n is an integer from 2 to 4, and m, x, and y are an integer from 2 or 3. The hard coating composition according to item 1 of the scope of the patent application, wherein the polyhedral siloxane oligomer compound includes a compound represented by the following Chemical Formula 2: [Chemical Formula 2] Wherein, each R is independently hydrogen, or a straight chain, branched chain, or cyclic hydrocarbon group having 1 to 20 carbon atoms substituted with a (meth) acrylate group, and at least one of them -R is a straight-chain, branched-chain or cyclic hydrocarbon group having 1 to 20 carbon atoms substituted with a (meth) acrylate group. The hard coating composition according to item 1 of the scope of the patent application, further comprising a polyfunctional urethane (meth) acrylate having a cyclohexyl group and a glycol functional group (ethylene glycol group) at least one of a multifunctional (meth) acrylate. The hard coating composition according to item 1 of the scope of patent application, further includes inorganic particles. The hard coating composition as described in item 1 of the scope of patent application, further includes a fluorine-based leveling agent. A hard coating film is formed by using the hard coating composition according to any one of claims 1 to 6 of the scope of patent application. A hard coating film includes: a dendrimer compound having a terminal (meth) acrylate group and a polyhedral siloxane oligomer compound, wherein when the hard coating film is folded in half to make the distance between the film surfaces When it is 6 millimeters (mm) at room temperature, spreading the film again and observing the folded portion with the naked eye will not cause cracks or cracks having a length of 5 millimeters (mm) or less; and Wherein when the hard coating film is folded in half so that the distance between the film surfaces is 6 millimeters (mm), the film is left at a temperature of 85 ° C and a relative humidity of 85% for 24 hours, and the film is unfolded again with the naked eye. Observing the folded portion, no cracks or cracks having a length of 5 millimeters (mm) or less were generated. An image display device has a hard coating film as described in item 8 of the scope of patent application. A window of a flexible display device has a hard coating film as described in item 8 of the scope of patent application. A polarizing plate has a hard coating film as described in item 8 of the scope of patent application. A touch sensor has a hard coating film as described in item 8 of the patent application scope.