TW201825615A - Hard Coating Film and Image Display Device Having the Same - Google Patents

Abstract

The present invention provides a hard coating film in which a first hard coating layer and a second hard coating layer are laminated on one side of a substrate film, wherein, AB < 0 when the curl values of the first hard coating layer and the second hard coating layer are A and B, respectively. The hard coating film according to the present invention can minimize the occurrence of curling while having excellent bending resistance and scratch resistance.

Description

Hard coating film and image display device having the same

The present invention relates to a hard coating film and an image display device having the same, and particularly to a hard coating film capable of minimizing the occurrence of warping and having excellent bending resistance and scratch resistance. Film image display device.

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

In recent years, flexible displays have received more and more attention as the next-generation display device, because flexible displays use flexible materials such as plastics instead of glass substrates that are not generally flexible, making It is curved, and it can still maintain display performance. Therefore, 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 during its manufacture or use, no warpage occurs at the corners of the film to prevent cracks from forming .

Korean Patent Application Publication No. 10-2016-0057221 discloses a high-hardness hard coating film formed using a hard coating composition including an epoxy silicone resin having a weight average molecular weight of 800 to 30,000, A crosslinking agent containing a compound having an epoxycyclohexane structure, and a photopolymerization initiator.

However, in the case of a hard coating composition having such a high hardness, there are problems in that bending resistance and / or scratch resistance are insufficient and warpage occurs.

【technical problem】

An object of the present invention is to provide a hard coating film, which can suppress the occurrence of warpage and has excellent bending resistance and scratch resistance.

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

[Technical means]

According to a concept of the present invention, a hard coating film is proposed, in which a first hard coating layer and a second hard coating layer are laminated on one side of a base film, and when the first hard coating layer and the When the warpage values of the second hard coat layer are A and B, AB <0.

In an embodiment of the present invention, the first hard coating layer may be formed of a first hard coating composition. The first hard coating composition includes a photocurable acrylic resin, a photopolymerization initiator, and A solvent, and the second hard coating layer may be formed of a second hard coating composition. The second hard coating composition includes a photocurable epoxy resin, a photopolymerization initiator, and a solvent.

In an embodiment of the present invention, the first hard coating layer may be formed of a first hard coating composition, and the first hard coating composition includes a dendritic compound having a (meth) acrylate group at one end, A monofunctional (meth) acrylate, a photopolymerization initiator, and a solvent, and the second hard coating layer may be formed of a second hard coating composition, the second hard coating composition includes a Alkoxysilane compound or polysiloxane resin, a photopolymerization initiator, and a solvent.

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

[Beneficial effects]

The hard coating film according to the present invention can minimize the occurrence of warpage, and at the same time has excellent bending resistance and scratch resistance, and thereby it can be effectively applied to a window of a flexible display device.

The present invention will be described in detail below.

An embodiment of the present invention relates to a hard coating film, wherein the first hard coating layer and the second hard coating layer are laminated on one side of the base film, wherein when the first hard coating layer and the second hard coating layer are When the curl values are A and B, AB <0.

In an embodiment of the present invention, the warpage value of the first hard coating layer and the second hard coating layer is measured after the first hard coating layer or the second hard coating layer is independently laminated on the base film. Value.

The warpage value can be obtained by cutting the hard coating film to a size of 10 cm × 10 cm, leaving it at 25 ° C, 48% RH for 24 hours, and placing the film so that its convex surface contacts a reference surface, and then Measured from the average of the height from the reference surface to the four corners. The positive warpage is represented by a (+) value, and the reverse warp is represented by a (-) value.

When the hard coating film is configured with the surface of the base film facing the reference surface, positive warpage is warping with a concave contour on the surface of the hard coating layer, and the surface of the concave contour is on the opposite side of the base film, and Converse warping is warping with a convex profile on the surface of the hard coating.

Therefore, AB <0 means that one of the warpage values of the first hard coat layer and the second hard coat layer is a (+) value, and the remaining one is a (-) value. That is, either the first hard coating layer or the second hard coating layer has positive warpage, and the remaining one has opposite warpage.

A hard coating film according to an embodiment of the present invention meets a condition that a multiplication value of warpage values of a first hard coating layer and a second hard coating layer is less than 0 (that is, AB <0), thereby suppressing warping The occurrence of the song.

In the hard coating film according to the embodiment of the present invention, the warp value of the first hard coat layer may be (+), and the warp value of the second hard coat layer may be (-). At this time, the occurrence of warpage can be minimized.

The hard coating film according to the embodiment of the present invention can be obtained by applying a hard coating composition on one side of a base film, and then curing the first hard coating layer and the second hard coating layer.

In a hard coating film according to an embodiment of the present invention, a first hard coating layer is formed using any of the first hard coating composition or the second hard coating composition described below, and the hard coating film is used. The remaining one of the coating composition forms a second hard coat layer. For example, the first hard coating layer may be formed from a first hard coating composition, and the second hard coating layer may be formed from a second hard coating composition.

For the base film, any polymer film having transparent properties can be used. The polymer film can be produced by a film forming method or an extrusion method and a film manufacturing method according to the molecular weight, and there is no limitation in use as long as it is a commercially available transparent polymer film. Examples include various transparent polymer substrates such as triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, acrylic Propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose, polyester, polystyrene, polyamide, polyether Polyimide (polyether imide), polypropylene (polyacryl), polyimide (polyimide), polyether sulfone, polysulfone, polyethylene (polyethylene), polypropylene (polypropylene), polyethylene Polymethyl pentene, polyvinyl chloride, polyvinylidene chloride, polyvinylcohol, polyvinylacetal, polyether ketone, polyether Polyether ether ketone, polyether sulfone, polymethyl ether Methyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate (Polycarbonate), and the like.

The thickness of the base film is not particularly limited, but may be 10 to 1000 ㎛, and preferably 20 to 150 ㎛. When the thickness of the base film is less than 10 ㎛, the strength of the film decreases and thus the processability decreases. When the thickness of the base film is more than 1000 ㎛, the transparency property decreases or the weight of the hard coating film increases.

The first hard coating layer and the second hard coating layer may each have a thickness of 1 to 10 ㎛. When the thicknesses of the first hard coating layer and the second hard coating layer are each less than 1 ㎛, it may be difficult to ensure the hardness. If the thickness is more than 10 ㎛, bending resistance may be reduced or severe warpage may occur.

<First Hard Coating Composition>

In one embodiment of the present invention, the first hard coating composition may include a photocurable acrylic resin, a photopolymerization initiator, and a solvent.

The photocurable acrylic resin may include a dendrimer compound having a terminal (meth) acrylate group and a monofunctional (meth) acrylate ) At least one of the groups.

In an embodiment of the present invention, the dendritic compound having a terminal (meth) acrylate group can be cured by using ultraviolet light by replacing the terminal end of the branched structure with a (meth) acrylate group, and having a center completely fat. Group and the structure characteristics of tertiary ester bond structure. Therefore, compared with a general polyfunctional acrylate monomer, a dendritic compound having a terminal (meth) acrylate group has a structural characteristic of having more functional groups relative to molecular weight as the production increases. When the functional groups are distributed at the ends, the core portion can help improve bending properties during its curing. Thereby, a hard coating film having high hardness and improved warpage properties and flexibility can be obtained.

A dendritic compound having a terminal (meth) acrylate group can 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 C ₁ -C ₆ alkyl, R ₂ is C ₁ -C ₆ alkyl, R ₃ is (meth) acryloyl group or And at least one R ₃ is R ₄ is (meth) acrylfluorenyl or And at least one R ₄ is R ₅ is (meth) acrylfluorenyl or R ₆ is a (meth) acrylfluorenyl group, n is an integer of 2 to 4, and m, x, and y are integers of 2 or 3.

The C ₁ -C ₆ alkyl group used herein refers to a linear or branched monovalent hydrocarbon group having 1 to 6 carbon atoms, and examples thereof include methyl, ethyl, n-propyl, and isopropyl (I-propyl), n-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, and the like, but not limited thereto.

The C ₁ -C ₆ alkylene group used herein refers to a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms, and examples thereof include a alkenyl group, a vinyl group, a propenyl group, a butenyl group, and the like Things, but not limited to this.

In an embodiment of the present invention, the dendritic compound having a terminal (meth) acrylate group may typically have a structure represented by the following Chemical Formula 2: [Chemical Formula 2]

Dendrimers having a terminal (meth) acrylate group are commercially available or can be prepared according to methods known in the field of the invention. For example, a multi-branched dendritic compound substituted with a plurality of (meth) acrylate groups at the end may be formed by a condensation reaction between a central backbone of a specific polyol and dimethylol propionic acid to form a first generation The dendritic structure is a branched structure in which dimethylolpropionic acid is repeatedly subjected to condensation reaction to grow into a second or higher generated dendritic structure, and then obtained by condensation reaction with acrylic acid at the terminal.

The dendritic compound may be contained in an amount of 30 to 60% by weight, preferably 35 to 55% by weight based on the total weight of the first hard coating composition. When the dendritic compound content is less than 30% by weight, it may be difficult to exhibit bending properties, and when the dendritic compound is more than 60% by weight, it may be due to the presence of unreacted functional groups caused by steric hindrance It becomes difficult to impart hardness characteristics to the coating.

In one embodiment of the present invention, the monofunctional (meth) acrylate can be cured by ultraviolet light, and can improve the bending properties of the hard coating film, improve flexibility, and minimize warpage.

Specific examples of monofunctional (meth) acrylates include ethyl (meth) acrylate, methyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate (2-ethylhexyl (meth) acrylate), butyl (meth) acrylate, isobutyl (meth) acrylate, 2 -2-ethoxyethyl (meth) acrylate, isodecyl (meth) acrylate, octyl (meth ) acrylate), isooctyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, isomethoxytyl (meth) acrylate Acrylate (isobornyl (meth) acrylate), and the like.

The amount of the monofunctional (meth) acrylate that can be contained is 5 to 10% by weight based on the total weight of the first hard coating composition. When the monofunctional (meth) acrylate content is less than 5% by weight, it will be difficult to provide flexibility, and when the monofunctional (meth) acrylate content is more than 10% by weight, the hardness will be reduced characteristic.

In an embodiment of the present invention, the photopolymerization initiator is used for photocuring the first hard coating composition, and is not particularly limited, and an initiator generally used in the technical field may be used.

Photopolymerization initiators can be classified into type I (Type I) photopolymerization initiators and type II (Type II) (hydrogen abstraction) photopolymerization initiators. Free radicals in type I photopolymerization initiators are generated by molecular decomposition caused by differences in chemical structure or molecular binding energy. In type II (hydrogen abstraction type), tertiary amines are used as co-initiators. Specific examples of the type I photopolymerization initiator may include acetophenones, such as 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone (4- t-butyldichloroacetophenone), 4-t-butyltrichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1 -Ketone (2-hydroxy-2-methyl-1-phenylpropan-1-one), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1-one (1- (4- isopropylphenyl) -2-hydroxy-2-methylpropan-1-one), 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one (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 ethyl ether, benzyl dimethyl Ketals (benzyl dimethyl ketal), or the like; acylphosphine oxides; titanocene compounds; and the like. Specific examples of the type II photopolymerization initiator may include benzophenones, such as benzophenone, benzoyl benzoic acid, benzoyl benzoic acid methyl ether), 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide -methyldiphenylsulfide), 3,3'-dimethyl-4-methoxybenzophenone (3,3'-dimethyl-4-methoxybenzophenone), or the like; and thioxanthones, such as thioxanthones Thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropyl Isopropylthioxanthone; or an analogue. These photopolymerization initiators may be used alone or in combination of two or more. In addition, a type I photopolymerization initiator may be used together with a type II photopolymerization initiator.

The photopolymerization initiator may be contained in an amount of 0.1 to 5% by weight, preferably 1 to 3% by weight based on the total weight of the first hard coating composition. If the weight content of the initiator is less than 0.1%, the degree of curing may be insufficient, and therefore the mechanical properties and adhesion of the finally obtained coating film may decrease. If the weight content of the initiator is more than 5%, adhesion failure, cracks and warpage may occur due to curing shrinkage.

In one embodiment of the present invention, the solvent is not particularly limited, and solvents commonly used in the technical field can be used.

Specific examples of the solvent may include alcohol-solvent solvents such as methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol, and the like; ketone-solvent solvents such as methyl ethyl ketone (methyl ethyl ketone) ketone), methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, etc .; acetate solvents such as Methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxy acetate, etc .; cellosolves solvents, such as methyl Methyl cellosolve, ethyl cellosolve, propyl cellosolve, etc .; hydrocarbon solvents, such as n-hexane, n-heptane (n -heptane), benzene, toluene, xylene, etc .; and the like. These solvents may be used alone or in combination of two or more.

The solvent may be contained in an amount of 5 to 90% by weight, preferably 10 to 85% by weight, based on the total weight of the hard coating composition. If the weight content of the solvent is less than 5%, the viscosity may increase to deteriorate the processability. If the weight content of the solvent is higher than 90%, it may be difficult to adjust the thickness of the coating film, and unevenness in drying may occur, causing defects in appearance.

In an embodiment of the present invention, the first hard coating composition may further include inorganic particles to further improve mechanical properties.

The inorganic particles may have an average particle diameter of 1 to 100 nm, preferably 5 to 50 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 diameter is smaller than the above range, an agglomeration phenomenon occurs in the composition, so that a uniform coating film cannot be formed, and the above-mentioned desired effect cannot be achieved. On the other hand, if the particle diameter exceeds the above range, not only the optical properties of the final coating film may be degraded, but also the mechanical properties may be weakened.

The inorganic particles may be metal oxides, and 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- One of the groups consisting of Al, Nb ₂ O ₃ , SnO and MgO. Specifically, Al ₂ O ₃ , SiO ₂ , ZrO ₂ and the like can be used.

Inorganic particles can be manufactured directly or commercially available. In the case of a commercially available product, a product in which inorganic particles are dispersed in an organic solvent at a concentration of 10 to 80% by weight can be used.

The amount of the inorganic particles that can be contained is 5 to 50% by weight based on the total weight of the first hard coating composition. When the content of inorganic particles is less than 5% by weight, mechanical properties such as abrasion resistance, scratch resistance, and pencil hardness may be insufficient, and when the content of inorganic particles exceeds 50% by weight, it may hinder curable properties and cause mechanical problems. Weakness in nature and defects in appearance.

In an embodiment of the present invention, in addition to the components described above, the first hard coating composition may further include components generally used in the technical field, such as a leveling agent, an ultraviolet light stabilizer, and a heat stabilizer. , And the like.

Leveling agents may be used to provide the composition with smoothness during coating and coating film properties. 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-3570 (available from BYK Chemie), 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 (available from Degussa), FC-4430 and FC-4432 (available from 3M), or similar. The leveling agent may be included in an amount of 0.1 to 1% by weight based on the total weight of the first hard coating composition.

Since the surface of the cured coating film will decompose due to continuous exposure to ultraviolet rays and cause discoloration and chipping, an ultraviolet light stabilizer may be added to shield or absorb the ultraviolet rays to protect the coating film. Ultraviolet light stabilizers can be classified into absorbers, quenchers, and hindered amine light stabilizers (HALS) according to the reaction mechanism. Can also be classified according to chemical structure as phenyl salicylate (absorbent), benzophenone (absorbent), benzotriazole (absorbent), nickel derivatives (matting Agent), radical scavenger. In one embodiment of the present invention, the ultraviolet light stabilizer is not particularly limited as long as it can not significantly change the initial color of the coating film.

The thermal stabilizer can be a commercially available product, and can be used independently or in combination as a polyphenol-based thermal stabilizer as a main thermal stabilizer, and a phosphite-based thermal stabilizer as a secondary thermal stabilizer. , And lactone-based heat stabilizers.

The above-mentioned ultraviolet stabilizer and heat stabilizer can be used in an appropriate amount at a level that does not affect ultraviolet curability.

The first hard coating composition can be appropriately applied to the base film by a known coating process, such as a die coater, an air knife, a reverse roll, and a spray coating ( spray), blade, casting, gravure, micro gravure, spin coating, etc.

After the first hard coating composition is applied to the base film, a drying process may be performed in an environment of 30 to 150 ° C. for 10 seconds to 1 hour, more specifically 30 seconds to 30 minutes, to vaporize volatile substances, Then a UV curing process is performed. UV curing can be performed by irradiating UV rays of about 0.01 to 10 J / cm ² , preferably 0.1 to 2 J / cm ² .

＜ Second Hard Coating Composition ＞

In one embodiment of the present invention, the second hard coating composition may include a photo-curable epoxy resin, a photo-polymerization initiator, and a solvent.

In addition, if necessary, the second hard coating composition may further include inorganic particles, and may further include additives such as a leveling agent, an ultraviolet light stabilizer, a heat stabilizer, and the like.

The photocurable epoxy resin may include an alkoxysilane compound or a polysiloxane resin having an epoxy group.

In an embodiment of the present invention, the alkoxysilane compound having an epoxy group may include a compound represented by the following Chemical Formula 3: [Chemical Formula 3] R ⁷ _n Si (OR ⁸ ) _4-n wherein R ⁷ is a ring Oxy, R ⁸ is C ₁ -C ₂₀ alkyl, and n is an integer from 1 to 3.

The C ₁ -C ₂₀ alkyl group used herein refers to a linear or branched hydrocarbon group having 1 to 20 carbon atoms, and examples thereof include methyl, ethyl, n-propyl, isopropyl ( i-propyl), n-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, and the like, but not limited thereto.

An alkoxysilane compound having an epoxy group exhibits a cationic photopolymerization reaction from an epoxy group. Cationic photopolymerization exhibits rather low shrinkage on the surface and does not cause oxygen inhibition reactions. Therefore, a stable curing phenomenon can be achieved, and the curing rate is excellent. In addition, the polysiloxane resin prepared by the sol-gel reaction of an alkoxysilane compound has the characteristics of rapid cationic photopolymerization and excellent curing rate due to the presence of a siloxane network. The epoxy-containing alkoxysilane compound and the polysiloxane resin can provide excellent hardness to the hard coating composition, and at the same time provide excellent flexibility.

The alkoxysilane compound having an epoxy group represented by Chemical Formula 3 may be selected from 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexane) ethyltriethoxysilane (2- (3,4-epoxycyclohexyl) ethyltriethoxysilane), 3-glycidoxypropyl trimethoxysilane ), And 3-glycidoxypropyl triethoxysilane.

The polysiloxane resin having an epoxy group can be prepared by hydrolyzing a sol-gel reaction of an alkoxysilane compound.

Specifically, the alkoxysilane of the alkoxysilane as a starting material undergoes a hydrolysis reaction with water to form a hydroxyl group, and is subjected to a condensation reaction with an alkoxy group or a hydroxyl group of another alkoxysilane compound to generate a siloxane bond and is formed Polysiloxane.

A catalyst may preferably be introduced to promote the hydrolytic sol-gel reaction. Catalysts that can be used can include acid catalysts, such as acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, chlorosulfonic acid, para-toluic acid ), Trichloroacetic acid, polyphosphoric acid, pyrophosphoric acid, iodic acid, tartaric acid, perchloric acid; alkali catalysts, such as Ammonia, sodium hydroxide, n-butylamine, di-n-butylamine, tri-n-butylamine, imidazole, perchloric acid Ammonium perchlorate, potassium hydroxide, barium hydroxide; ionic resins, such as Amberite IPA-400 (Cl); and the like. The use amount of the catalyst is not particularly limited, and based on 100 parts by weight of the alkoxysilane, the amount of the catalyst added may be 0.0001 to 10 parts by weight.

The hydrolysis sol-gel reaction can be performed at room temperature for 6 to 144 hours, and can also be performed at 60 to 80 ° C for 12 to 36 hours to accelerate the reaction rate and perform a complete condensation reaction.

Based on the total weight of the second hard coating composition being 100%, the amount that may contain an alkoxysilane compound or a polysiloxane resin is 30 to 60% by weight, preferably 35 to 55% by weight. When the content of the alkoxysilane compound or the polysiloxane resin is less than 30% by weight, it becomes difficult to secure hardness. When the weight content is more than 60%, the coating film may be cracked, and it may become difficult to provide bending properties.

In one embodiment of the present invention, the photopolymerization initiator is used for photocuring the second hard coating composition, and the initiator is not particularly limited. Any initiator generally used in the technical field may be used.

As the photopolymerization initiator, a cation capable of initiating the polymerization reaction of the cationic photo-curable component by generating a cationic substance or Lewis acid from irradiation with active energy rays such as visible light, ultraviolet light, X-rays, and electron beams can be used. Photopolymerization initiator, or the like.

Since the cationic photopolymerization initiator acts as a catalyst by light, it is excellent in storage stability and processability even when mixed with a cationic photocurable component. Examples of compounds capable of generating cationic substances and Lewis acid by irradiating activated energy rays include onium salts, such as aromatic diazonium salts, aromatic iodonium salts, Or aromatic sulfonium salts; iron-allene complexes, and the like. Among these examples, aromatic sulfonium salts are preferred because they have ultraviolet light absorption properties even in a wavelength region of about 300 nm, so they have excellent curable properties and can provide excellent coating film characteristics. . These cationic photopolymerization initiators may be used alone or in combination of two or more.

The photopolymerization initiator may be included in an amount of 0.1 to 5% based on 100% of the total weight of the second hard coating composition. When the weight content of the photopolymerization initiator is less than 0.1%, the curing rate is slow, and when the weight content of the photopolymerization initiator is more than 5%, cracks may occur in the hard coating layer due to excessive curing.

The other components contained in the second hard coating composition, and the methods of coating, drying, and curing are the same as those used to describe the first hard coating composition, and will not be repeated here.

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 coat film of the present invention can be used by being attached to a polarizing plate, a sensor, or the like.

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

Hereinafter, the present invention will be described in more detail with reference to examples, comparative examples, and test examples. For those of ordinary skill in the art, it is obvious that understanding of these examples, comparative examples, and test examples is for illustrative purposes only and is not intended to limit the scope of the invention.

Preparation Example 1: Preparation of the first hard coating composition

Based on 100% of the total weight of the first hard coating composition, 40% by weight of a dendritic compound (SP-1106, manufactured by Miwon Specialty Chemicals) having a terminal (meth) acrylate group was mixed with a stirrer, and the weight was 5 % Monofunctional acrylate (butyl acrylate), 39% inorganic silica particles (particle size 10-15 nm), 2.5% by weight photopolymerization initiator (1-hydroxycyclohexylbenzene) Ketone), 0.5% by weight leveling agent (BYK-3570, manufactured by BYK Chemie), and 13% by weight solvent (methyl ethyl ketone), followed by filtration using a polypropylene (PP) filter medium to prepare The first hard coating composition.

Preparation Example 2: Preparation of a second hard coating composition

Based on the total weight of the second hard coating composition is 100%, 40% by weight of a polysilicone resin (SP-3T, manufactured by Shin-A T & C) and 5% by weight of inorganic silica particles are mixed with a stirrer. (Particle size 10-15 nm), 2.5% by weight of photopolymerization initiator (bis (4-methylphenyl) iodonium hexafluorophosphate), 0.5% by weight A leveling agent (BYK-3570, manufactured by BYK Chemie), and a solvent (methyl ethyl ketone) of 52% by weight, followed by filtration using a polypropylene filter medium to prepare a second hard coating composition.

Examples 1 to 3 and Comparative Examples 1 to 2: Preparation of a hard coating film

Example 1:

The first hard coating composition prepared in Preparation Example 1 was coated on one surface of an optical polyurethane film (100 F) as a substrate, dried in an oven at 80 ° C. for 5 minutes, and then irradiated in a high-pressure mercury lamp. 0.5 J / cm ² of UV light to form a first hard coat layer, thereby having a thickness of 5 ㎛. Then, the second hard coating composition prepared in Preparation Example 2 was coated on the first hard coating layer, dried in an oven at 80 ° C. for 5 minutes, and then irradiated with 0.5 J / cm ² of UV light in a high-pressure mercury lamp. After forming the second hard coat layer, it has a thickness of 5 ㎛. Thereby, a hard coating film was prepared.

Example 2:

The hard coating film was prepared in the same manner as in Example 1, except that the first hard coating composition prepared in Preparation Example 1 was coated on one surface of the substrate, and after drying, had a thickness of 7 ㎛, and was The second hard coating composition prepared in Preparation Example 2 was coated on the first hard coating layer, and after drying to form a second hard coating layer, it had a thickness of 3 ㎛.

Example 3:

The hard coating film was prepared in the same manner as in Example 1, except that the first hard coating composition prepared in Preparation Example 1 was coated on one surface of the substrate, and after drying, it had a thickness of 3 ㎛, and was The second hard coating composition prepared in Preparation Example 2 was coated on the first hard coating layer, and after drying to form a second hard coating layer, it had a thickness of 7 ㎛.

Comparative Example 1:

The hard coating film was prepared in the same manner as in Example 1, except that the first hard coating composition prepared in Preparation Example 1 was coated on one surface of a substrate, and after drying, had a thickness of 5 ㎛, and was The first hard coating composition prepared in Preparation Example 1 was coated on the first hard coating layer, and after drying to form a second hard coating layer, it had a thickness of 5 ㎛.

Comparative Example 2:

The hard coating film was prepared in the same manner as in Example 1, except that the second hard coating composition prepared in Preparation Example 2 was coated on one surface of the substrate, and after drying, had a thickness of 5 ㎛, and was The second hard coating composition prepared in Preparation Example 2 was coated on the first hard coating layer, and after drying to form a second hard coating layer, it had a thickness of 5 ㎛.

Test example 1:

Test example 1-1:

The first hard coating composition prepared in Preparation Example 1 was coated on one surface of an optical polyurethane film (100 F) as a substrate, dried in an oven at 80 ° C. for 5 minutes, and then irradiated in a high-pressure mercury lamp. 0.5 J / cm ² of UV light was used to form only the first hard coat layer on the base film, thereby having a thickness of 3 3, thereby obtaining a first hard coat film.

The warpage value is obtained by cutting the hard coating film to a size of 10 cm × 10 cm and leaving it at 25 ° C and 48% RH for 24 hours. The film is placed on a flat glass plate to make its convex surface Touch the glass plate and then measure the average of the height from the glass plate (reference surface) to the four corners. The positive warpage is represented by a (+) value, and the reverse warp is represented by a (-) value.

The measured warpage value was 3 mm.

Test example 1-2:

The hard coating film was prepared in the same manner as in Test Example 1-1 except that the first hard coating composition was applied, and after drying, it had a thickness of 5 ㎛, and its warpage value was measured.

The measured warpage value was 5 mm.

Test example 1-3:

The hard coating film was prepared in the same manner as in Test Example 1-1, except that the first hard coating composition was applied, and after drying, it had a thickness of 7 ㎛, and its warpage value was measured.

The measured warpage value was 7 mm.

Test example 1-4:

The hard coating film was prepared in the same manner as in Test Example 1-1, except that the second hard coating composition was used instead of the first hard coating composition, and its warpage value was measured.

The measured warpage value was -10 mm.

Test example 1-5:

The hard coating film was prepared in the same manner as in Test Example 1-2, except that the second hard coating composition was used instead of the first hard coating composition, and its warpage value was measured.

The measured warpage value was -15 mm.

Test example 1-6:

The hard coating film was prepared in the same manner as in Test Example 1-3, except that the second hard coating composition was used instead of the first hard coating composition, and its warpage value was measured.

The measured warpage value was -20 mm.

Test example 2:

The physical properties of the hard coating films prepared in the examples and comparative examples were measured by the methods described below, and the results are shown in Table 1 below.

(1) Resistance to bending at room temperature

The hard coating film (width × length = 10 mm × 100 mm) is folded in half so that the distance between the film surfaces is 6 mm. Then, when the film was opened again, it was confirmed with a naked eye whether cracks occurred at the bends, and thereby the bending resistance at room temperature was evaluated.

＜ Evaluation criteria ＞

◎: No crack occurred at the bend

○ -A: Cracks occurred at the bend (length is 5 mm or less, and the number is 5 or less)

○ -B: Cracks occur at the bend (length is 5 mm or less, and the number is more than 5 and equal to or less than 10)

○ -C: Cracks occur at the bend (length is 5 mm or less, and the number is greater than 10)

△ -A: There are cracks at the bend (length is more than 5 mm and equal to or less than 10 mm, and the number is equal to or less than 5)

△ -B: Cracks occur at the bend (length greater than 5 mm and equal to or less than 10 mm, and the number is greater than 5 and equal to or less than 10)

△ -C: Cracks occur at the bends (length is greater than 5 mm and equal to or less than 10 mm, and the number is greater than 10)

×: Rupture at the bend

(2) High temperature-high humidity resistance to bending

The hard coating film (width × length = 10 mm × 100 mm) was folded in half so that the distance between the film surfaces was 6 mm, and then left in an environment of 85 ° C and 85% relative humidity for 24 hours. Then, when the film was opened again, it was visually confirmed whether cracks occurred at the bends, and the bending resistance was evaluated therefrom.

＜ Evaluation criteria ＞

◎: No crack occurred at the bend

○ -A: Cracks occurred at the bend (length is 5 mm or less, and the number is 5 or less)

○ -B: Cracks occur at the bend (length is 5 mm or less, and the number is more than 5 and equal to or less than 10)

○ -C: Cracks occur at the bend (length is 5 mm or less, and the number is greater than 10)

△ -A: There are cracks at the bend (length is more than 5 mm and equal to or less than 10 mm, and the number is equal to or less than 5)

△ -B: Cracks occur at the bend (length greater than 5 mm and equal to or less than 10 mm, and the number is greater than 5 and equal to or less than 10)

△ -C: Cracks occur at the bends (length is greater than 5 mm and equal to or less than 10 mm, and the number is greater than 10)

×: Rupture at the bend

(3) Pencil hardness

The pencil hardness is measured using a pencil hardness tester (PHT, manufactured by Sukbo Science, Korea) with a load of 500 g. A pencil made by Mitsubishi Corporation was used, and the hardness of each pencil was measured 5 times. When two or more scratches are found, they are judged to be defective, and the maximum hardness judged as OK is recorded.

(4) Warping

The hard coating films prepared in the examples and comparative examples were cut to a size of 10 cm × 10 cm, left in an environment of 25 ° C. and 48% RH for 24 hours, and then placed on a flat glass plate so that the convex surface was Contact with glass plate. Next, the average of the height from the bottom (reference surface) of the glass plate to the four corners was measured to obtain the warpage value. Results are recorded based on the following evaluation criteria.

＜ Evaluation criteria ＞

◎: The average height of the four corners is equal to or less than 20 mm

◯: The average height of the four corners is greater than 20 mm and equal to or less than 50 mm

Δ: The average height of the four corners is greater than 50 mm

×: The four corners completely floated, and the film warped into a cylindrical shape

(5) Scratch resistance

Scratch resistance was tested using a steel wool tester (WT-LCM100, manufactured by Korean Protec Corporation) under a load of 1 kg / (2 cm × 2 cm) for 10 times. Steel wool uses the number 0000 (# 0000).

＜ Evaluation criteria ＞

S: 0 scratches

A: 1 to 10 scratches

B: 11 to 20 scratches

C: 21 to 30 scratches

D: 31 or more scratches [Table 1]

As shown in Table 1, the hard coating films according to Examples 1 to 3 of the present invention not only have excellent bending resistance and scratch resistance, but also suppress the occurrence of warping. On the other hand, it was found that the hard coating films of Comparative Examples 1 and 2 had poor bending resistance, scratch resistance, and warpage characteristics.

In summary, although the present invention has been disclosed as above with the embodiments, it is not intended to limit the present invention. 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 (10)

A hard coating film in which a first hard coating layer and a second hard coating layer are laminated on one side of a base film, wherein when the first hard coating layer and the second hard coating layer are warped, For A and B, AB <0. The hard coating film according to item 1 of the scope of patent application, wherein the first hard coating layer and the second hard coating layer each have a thickness of 1 to 10 ㎛. The hard coating film according to item 1 of the patent application scope, wherein the first hard coating layer is formed of a first hard coating composition, and the first hard coating composition includes a photo-curable acrylic resin, a light A polymerization initiator and a solvent, and the second hard coating layer is formed of a second hard coating composition, and the second hard coating composition includes a photocurable epoxy resin, a photopolymerization initiator, and a solvent. The hard coating film according to item 3 of the application, wherein the first hard coating layer is formed of a first hard coating composition, and the first hard coating composition includes a (meth) acrylate having one end. Based dendritic compound, monofunctional (meth) acrylate, photopolymerization initiator, and solvent, and the second hard coating layer is formed of a second hard coating composition, and the second hard coating composition It includes an alkoxysilane compound or a polysiloxane resin having an epoxy group, a photopolymerization initiator, and a solvent. The hard coating film according to item 3 of the application, wherein the first hard coating composition and the second hard coating composition further include inorganic particles. The hard coating film according to item 1 of the application, wherein the warpage value of the first hard coat layer is (+), and the warpage value of the second hard coat layer is (-). An image display device having the hard coating film according to any one of claims 1 to 6 of the scope of patent application. A window of a flexible display device has a hard coating film according to any one of claims 1 to 6 of the scope of patent application. A polarizing plate having a hard coating film according to any one of claims 1 to 6 of the scope of patent application. A touch sensor having a hard coating film as described in any one of claims 1 to 6 of the scope of patent application.