Hard coat film, image display device and foldable display device having the same

Abstract

The present application provides a kind of hard coating film and the window of image display device and foldable display device with it, the hard coating film includes transparent substrate and the hard coating layer formed on at least one side of the transparent substrate, wherein, the hard coating layer is formed by the hard coating composition including light-transmitting resin, photoinitiator, fluorine-containing UV curable functional group compound and solvent, the light-transmitting resin includes the tri- to hexa-functional (methyl) acrylate containing oxirane group and hexa-functional urethane (methyl) acrylate.The hard coating film according to the present application is excellent in tensile property, good in stain resistance, wear resistance and chemical reagent resistance, and can ensure finger sliding property, so it can be advantageously used for the window of foldable display device.

Description

Technical Field

[0001] The present invention relates to a hard coating film and a window of an image display device and a foldable display device having the same, and more specifically, to a hard coating film with excellent tensile strength, good stain resistance, abrasion resistance and chemical resistance, and capable of ensuring finger sliding, and an image display device having the hard coating film. Background Technology

[0002] Hard coatings are used for surface protection and other purposes in image display devices such as liquid crystal displays, electroluminescent (EL) displays, plasma displays (PDs), and field emission displays (FEDs).

[0003] Recently, flexible or foldable display devices, which use flexible materials such as plastics or ultra-thin glass (UTG) to replace existing inflexible glass substrates and thus maintain their display performance even when bent like paper, are rapidly emerging as the next generation of display devices. Consequently, research is underway on hard coatings that possess excellent stain resistance, abrasion resistance, and chemical resistance, while also exhibiting appropriate flexibility to prevent cracking during stretching.

[0004] However, there is a trade-off between the tensile strength, abrasion resistance, and chemical resistance of hard coatings, which limits the development of antifouling hard coatings with excellent tensile strength.

[0005] Korean Patent Publication No. 10-2012-0078457 discloses a hard coating composition comprising an impact enhancer having a rubber core and one or more shells, a photopolymerizable compound, and a photopolymerization initiator. It also describes that a hard coating film using the above-mentioned hard coating composition can achieve excellent scratch resistance, film adhesion, impact resistance, solvent resistance, processability, and flexibility.

[0006] However, the aforementioned hard coating film has insufficient tensile and bending resistance for use in foldable display devices, and also lacks sufficient stain resistance and abrasion resistance. Summary of the Invention

[0007] Technical issues

[0008] One object of the present invention is to provide a hard coating film that has excellent tensile properties, good anti-fouling properties, abrasion resistance and chemical resistance, and can ensure finger slippage.

[0009] Another object of the present invention is to provide an image display device having the hard coating film.

[0010] Another object of the present invention is to provide a window of a foldable display device having the aforementioned hard coating.

[0011] Technical solution

[0012] On one hand, the present invention provides a hard coating film comprising a transparent substrate and a hard coating layer formed on at least one side of the transparent substrate, the hard coating layer being formed from a hard coating composition comprising a light-transmitting resin, a photoinitiator, a fluorine-containing UV-curable functional compound and a solvent, wherein the light-transmitting resin comprises tri- to hexafunctional (meth)acrylates and hexafunctional urethane (meth)acrylates containing ethylene oxide.

[0013] In one embodiment of the present invention, the content of the fluorine-containing UV-curable functional compound may be from 0.01 to 40% by weight relative to 100% by weight of the total solid components in the hard coating composition.

[0014] In one embodiment of the present invention, the ethylene oxide-containing tri- to hexafunctional (meth)acrylate may be a compound represented by the following chemical formula 1:

[0015] [Chemical Formula 1]

[0016]

[0017] In the above formula,

[0018] The sum of a, b, c, and d is 5.

[0019] In one embodiment of the present invention, the content of the tri- to hexafunctional (meth)acrylate containing ethylene oxide can be 50 to 90% by weight relative to 100% by weight of the total translucent resin, and the content of the hexafunctional urethane (meth)acrylate can be 10 to 50% by weight.

[0020] In one embodiment of the present invention, the light-transmitting resin may further comprise dendritic acrylates.

[0021] In one embodiment of the present invention, relative to 100% by weight of the total translucent resin, the content of the tri- to hexafunctional (meth)acrylate containing ethylene oxide can be 50 to 70% by weight, the content of the hexafunctional urethane (meth)acrylate can be 10 to 20% by weight, and the content of the dendritic acrylate can be 20 to 30% by weight.

[0022] On the other hand, the present invention provides an image display device having the hard coating film.

[0023] In another aspect, the present invention provides a window for a foldable display device having the aforementioned hard coating.

[0024] The effects of the invention

[0025] The hard coating of the present invention has excellent tensile properties, good stain resistance, abrasion resistance and chemical resistance, and can ensure finger slippage, thus making it advantageous for use in the window of a foldable display device. Detailed Implementation

[0026] The present invention will now be described in more detail.

[0027] One embodiment of the present invention relates to a hard coating film comprising a transparent substrate and a hard coating layer formed on at least one side of the transparent substrate, wherein the hard coating layer is formed from a hard coating composition comprising a light-transmitting resin, a photoinitiator, a fluorine-containing UV-curable functional compound and a solvent, wherein the light-transmitting resin comprises tri- to hexafunctional (meth)acrylates and hexafunctional urethane (meth)acrylates containing ethylene oxide.

[0028] According to one embodiment of the present invention, a hard coating film is provided by using tri- to hexafunctional (meth)acrylates containing ethylene oxide, which causes a large amount of fluorine to float on the surface when phase separation occurs with fluorine-containing UV-curable functional compounds. This allows the hard coating film to improve its antifouling properties, abrasion resistance, and chemical resistance while ensuring its tensile strength.

[0029] In one embodiment of the present invention, any type of transparent plastic film can be used as the transparent substrate. For example, it can be a film formed from polymers such as triacetyl cellulose, cellulose acetobutyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetopropionyl cellulose, polyester, polystyrene, polyamide, polyetherimide, polyacrylic acid, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polycarbonate. These polymers can be used alone or in combination.

[0030] There is no particular limitation on the thickness of the aforementioned transparent substrate, which can be from 10 to 1,000 μm, specifically from 20 to 150 μm. If the thickness of the aforementioned transparent substrate is less than 10 μm, the strength of the film will decrease, resulting in poor processability; if it is greater than 1,000 μm, problems such as decreased transparency or increased weight of the hard coating film will occur.

[0031] In one embodiment of the present invention, the hard coating composition comprises a light-transmitting resin, a photoinitiator, a fluorine-containing UV-curable functional compound, and a solvent.

[0032] The aforementioned light-transmitting resin contains tri- to hexafunctional (meth)acrylates containing ethylene oxide to ensure the tensile strength, stain resistance, and finger slip resistance of the hard coating film, and contains hexafunctional urethane (meth)acrylates to improve abrasion resistance and chemical resistance.

[0033] Specific examples of the aforementioned tri- to hexafunctional (meth)acrylates containing ethylene oxide include trimethylolpropane (EO)3 tri(meth)acrylate, trimethylolpropane (EO)6 tri(meth)acrylate, trimethylolpropane (EO)9 tri(meth)acrylate, and trimethylolpropane (EO) 15 Tri(meth)acrylate, trimethylolpropane (EO) 20 Tri(meth)acrylate, glycerol (EO)3-tri(meth)acrylate, glycerol (EO)6-tri(meth)acrylate, glycerol (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, dipentaerythritol (EO) 24 Hexa(meth)acrylates, etc.

[0034] In one embodiment of the present invention, the above-mentioned tri- to hexafunctional (meth)acrylate containing ethylene oxide can be a compound represented by the following chemical formula 1:

[0035] [Chemical Formula 1]

[0036]

[0037] In the above formula,

[0038] The sum of a, b, c, and d is 5.

[0039] The hexafunctional urethane (meth)acrylate can be produced by reacting an intramolecularly hydroxyl-containing (meth)acrylate with a compound having an isocyanate group in the presence of a catalyst.

[0040] Specific examples of (meth)acrylates containing hydroxyl groups in the above-mentioned molecules include 2-hydroxyethyl (meth)acrylate, 2-hydroxyisopropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, caprolactone ring-opening hydroxyacrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate. Furthermore, specific examples of compounds containing isocyanate groups include 1,4-diisocyanate butane, 1,6-diisocyanate hexane, 1,8-diisocyanate octane, 1,12-diisocyanate dodecane, 1,5-diisocyanate-2-methylpentane, trimethyl-1,6-diisocyanate hexane, 1,3-bis(isocyanate methyl)cyclohexane, trans-1,4-cyclohexene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and isocyanate... Phlorone diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, xylene-1,4-diisocyanate, tetramethylxylene-1,3-diisocyanate, 1-chloromethyl-2,4-diisocyanate, 4,4'-methylenebis(2,6-dimethylphenylisocyanate), 4,4'-oxobis(phenylisocyanate), trifunctional isocyanates derived from hexamethylene diisocyanate, trimethylolpropane addition to toluene diisocyanate, etc.

[0041] In a hard coating composition according to one embodiment of the present invention, the content of the tri- to hexafunctional (meth)acrylate containing ethylene oxide can be 50 to 90% by weight, preferably 50 to 70% by weight, relative to 100% by weight of the total transparent resin; the content of the hexafunctional urethane (meth)acrylate can be 10 to 50% by weight, preferably 30 to 50% by weight.

[0042] In one embodiment of the present invention, the light-transmitting resin may further comprise dendritic acrylates.

[0043] The aforementioned dendritic (meth)acrylates, with their branched ends that can be replaced by (meth)acrylate groups for UV curing, possess a completely aliphatic structure and are characterized by tertiary ester bonds. Therefore, compared to typical multifunctional acrylate monomers, these dendritic (meth)acrylates exhibit a greater number of functional groups relative to molecular weight with increasing generation, and because the functional groups are distributed at the ends, the core portion helps improve bending properties during curing. Consequently, a high-hardness hard coating film with improved curl and flexibility can be obtained.

[0044] The aforementioned dendritic (meth)acrylates are commercially available or can be manufactured using methods known in the art. For example, a first-generation dendritic macromolecular structure is formed by condensing a specific polyol with dimethylolpropionic acid as the central backbone. This structure is then repeatedly condensed with dimethylolpropionic acid to grow to a second-generation or higher structure. Subsequently, acrylic acid is condensed with terminal groups to obtain a highly branched dendritic macromolecular compound whose terminals are replaced by multiple (meth)acrylate groups.

[0045] Commercially available dendritic (meth)acrylates such as Miramer SP1106 from Migen Corporation, Viscoat #1000, Viscoat #1020, and Viscoat #1080 from Osaka Organics Corporation can be used.

[0046] In one embodiment of the present invention, when the above-mentioned light-transmitting resin further comprises dendritic acrylate, the content of the tri- to hexafunctional (meth)acrylate containing ethylene oxide is 50 to 70% by weight relative to 100% by weight of the total light-transmitting resin, the content of the hexafunctional urethane (meth)acrylate can be 10 to 20% by weight, and the content of the dendritic acrylate can be 20 to 30% by weight.

[0047] The content of the light-transmitting resin can be 50 to 95% by weight relative to 100% of the total solids in the hard coating composition, preferably 65 to 95% by weight. If the content of the light-transmitting resin is less than 50% by weight, it is difficult to achieve a sufficient increase in hardness; if it is greater than 95% by weight, there is a serious problem of curling.

[0048] In one embodiment of the present invention, the photoinitiator is included to induce photocuring of the hard coating composition. For example, it may include a photoradical initiator capable of forming free radicals by light irradiation.

[0049] Examples of the aforementioned photoinitiators include: Type 1 initiators that generate free radicals through molecular decomposition due to differences in chemical structure or molecular bond energy; and Type 2 initiators that induce hydrogen decyclization by coexisting with tertiary amines.

[0050] For example, the aforementioned type 1 initiators may include: 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone, 4-tert-butyltrichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1-one, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)one, 1-hydroxycyclohexylphenyl ketone, and other acetophenones; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin dimethyl ketal, and other benzoin derivatives; phosphine oxides, titanium cephalodecyl compounds, etc.

[0051] The aforementioned type 2 initiators may include: benzophenone, benzoylbenzoic acid, benzoylbenzoic acid methyl ether, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3'-methyl-4-methoxybenzophenone, and other benzophenones; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, and other thioxanthones.

[0052] The above-mentioned photoinitiators can be used alone or in combination of two or more. Furthermore, the above-mentioned type 1 and type 2 initiators can be used alone or in combination.

[0053] In one embodiment of the present invention, the content of the photoinitiator may be 0.1 to 10% by weight, preferably about 1 to 8% by weight, relative to 100% by weight of the total solid components in the hard coating composition. If the content of the photoinitiator is less than 0.1% by weight, the curing speed of the composition may be slow, resulting in uncured components and a decrease in mechanical properties; if it is greater than 10% by weight, cracks may occur in the coating film due to over-curing.

[0054] In one embodiment of the present invention, the fluorine-containing UV-curable functional compound is a component that imparts antifouling, abrasion resistance, and chemical resistance. There are no particular limitations on the aforementioned fluorine-containing UV-curable functional compound as long as it contains fluorine and simultaneously possesses UV-curable functional groups.

[0055] The aforementioned fluorine-containing UV-curable functional compound can be selected from one or more of the group consisting of (meth)acrylates containing perfluoroalkyl groups, (meth)acrylates containing perfluoropolyether groups, (meth)acrylates containing perfluorocyclic aliphatic groups, and (meth)acrylates containing perfluoroaromatic groups. In this case, it exhibits excellent antifouling properties while forming chemical bonds with the hard coating, thereby maintaining excellent durability of antifouling properties even after repeated use, and is therefore preferred.

[0056] The aforementioned fluorine-containing UV-curable functional compounds preferably have 1 to 6 UV-curable functional groups.

[0057] The content of the fluorine-containing UV-curable functional group compound relative to 100% by weight of the total solid components in the hard coating composition can be from 0.01 to 40% by weight, preferably from 0.1 to 30% by weight, and more preferably from 0.1 to 5% by weight. When the fluorine-containing UV-curable functional group compound is included within the above range, excellent abrasion resistance and stain resistance are imparted, and therefore it is preferred. When the content of the fluorine-containing UV-curable functional group compound is less than the above range, it is difficult to achieve sufficient abrasion resistance or stain resistance; when it is greater than the above range, hardness and abrasion resistance may decrease.

[0058] In one embodiment of the present invention, any solvent known in the art as capable of dissolving or dispersing the aforementioned components may be used without limitation. Usable solvents may include alcohols (methanol, ethanol, isopropanol, butanol, methyl cellosolve, ethyl cellosolve, etc.), ketones (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, cyclohexanone, etc.), acetates (ethyl acetate, propyl acetate, n-butyl acetate, tert-butyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, methoxybutyl acetate, methoxypentyl acetate, etc.), hexanes (hexane, heptane, octane, etc.), benzenes (benzene, toluene, xylene, etc.), and ethers (diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, etc.). The solvents exemplified above can be used individually or in combination of two or more.

[0059] The solvent content can be from 10% to 95% by weight relative to 100% of the total hard coating composition. If the solvent content is below the above range, the viscosity is high and the workability deteriorates; moreover, the substrate cannot swell sufficiently. Conversely, when the content is above the above range, there is a problem of excessive drying time and reduced economy, and haze may occur due to severe swelling of the substrate film. Therefore, the solvent should be used appropriately within the above range.

[0060] The above-mentioned hard coating composition may further include a leveling agent to impart smoothness and coatability to the coating film when the composition is applied.

[0061] The leveling agents mentioned above can be commercially available silicone-based, fluorinated, or acrylic polymer-based leveling agents, such as: BYK-307, BYK-323, BYK-331, BYK-333, BYK-337, BYK-346, BYK-361N, BYK-373, BYK-375, BYK-377, BYK-378, BYK-3550, BYK-UV3500, BYK-UV3530, BYK-UV3575, and BYK-UV3576 from BYK Chemicals; and TEGO Glide 410, TEGO Glide 411, TEGO Glide 415, TEGO Glide 420, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, and TEGO Glide from TIGABYTE. TEGO Rad 450, TEGO Glide 455, TEGO Rad 2100, TEGO Rad 2200N, TEGO Rad 2250, TEGO Rad 2300, TEGO Rad 2500; 3M's FC-4430 and FC-4432; Shin-Etsu's KY-1203, etc.

[0062] The leveling agent content can be from 0.01 to 10% by weight relative to 100% of the total solid components in the hard coating composition. If the leveling agent content is lower than the above range, it will be difficult to achieve sufficient smoothness of the optical film; if it is higher than the above range, the hardness and scratch resistance of the optical film may decrease.

[0063] In addition to the above-mentioned components, the above-mentioned hard coating composition may further contain components commonly used in the art, such as ultraviolet stabilizers, heat stabilizers, antioxidants, lubricants, antifouling agents, etc.

[0064] The surface of a cured coating film can decompose, discolor, and become brittle due to continuous exposure to ultraviolet (UV) light. Therefore, the aforementioned UV stabilizers are additives added to protect the coating film by blocking or absorbing such UV rays. Based on their mechanism of action, UV stabilizers are classified as absorbers, quenchers, and hindered amine light stabilizers (HALS). Furthermore, based on their chemical structure, they can be classified as phenyl salicylate (absorber), benzophenone (absorber), benzotriazole (absorber), nickel derivatives (quenchers), and radical scavengers, etc. There are no particular restrictions on the use of any UV stabilizer that does not significantly alter the initial color of the coating film.

[0065] In addition, commercially available products can be used as heat stabilizers, namely polyphenols as primary heat stabilizers, phosphate esters and lactones as secondary heat stabilizers, which can be used alone or in combination of two or more.

[0066] The above-mentioned UV stabilizers and heat stabilizers can be used with appropriate adjustments to their content without affecting UV curability.

[0067] The aforementioned hard coating can be formed by applying the aforementioned hard coating composition to a substrate, drying it, and then UV curing it.

[0068] The hard coating composition can be applied to the substrate layer using known methods such as die coating machine, air knife, reverse roller, spraying, doctor blade, casting, gravure, microgravure, spin coating, etc.

[0069] After applying the above-described hard coating composition to a substrate layer, the volatiles are evaporated and dried at a temperature of 30 to 150°C for 10 seconds to 1 hour, more specifically 30 seconds to 30 minutes, followed by UV curing. The UV light irradiation dose can specifically be approximately 0.01 to 10 J / cm². 2 More specifically, it can be 0.1 to 2 J / cm 2 .

[0070] At this point, the thickness of the hard coating can be specifically 1 to 30 μm, more specifically 3 to 20 μm. When the thickness of the hard coating is within the above range, excellent hardness, bending resistance, and curling properties can be obtained.

[0071] One embodiment of the present invention relates to an image display device having the above-described hard coating. For example, the hard coating of the present invention can be used as a window in an image display device, particularly a foldable display device. Furthermore, the hard coating of the present invention can also be attached to polarizing plates, touch sensors, etc.

[0072] The hard coating of one embodiment of the present invention can be used in reflective, transmissive, and semi-transmissive LCDs, or LCDs with various driving methods such as TN, STN, OCB, HAN, VA, and IPS. Furthermore, the hard coating of one embodiment of the present invention can also be used in various image display devices such as plasma displays, field emission displays, organic EL displays, inorganic EL displays, and electronic paper.

[0073] The present invention will now be described in more detail through examples, comparative examples, and experimental examples. These examples, comparative examples, and experimental examples are for illustrative purposes only, and it will be apparent to those skilled in the art that the scope of the present invention is not limited thereto.

[0074] Manufacturing Examples 1 to 8: Manufacturing of Hard Coating Compositions

[0075] The components listed in Table 1 below are mixed using a mixer and filtered using a PP filter to produce a hard coating composition (unit: weight %).

[0076] [Table 1]

[0077]

[0078] A-1: Tetrafunctional acrylate containing ethylene oxide (MIRAMER M4004, MIRAMER Specialty Chemicals Co., Ltd.)

[0079] A-2: Hexafunctional carbamate acrylate (MIRAMER PU610, Miyuan Specialty Chemicals Co., Ltd.)

[0080] A-3: Multifunctional dendritic acrylate (MIRAMER SP1106, Amway Specialty Chemicals Co., Ltd.)

[0081] B: Irgacure-184 (Ciba)

[0082] C: DAC-100 (Daikin Corporation, 20% solids content)

[0083] D: Methyl ethyl ketone

[0084] Examples and Comparative Examples: Manufacturing of Hard Coating Films

[0085] The hard coating composition manufactured in the above manufacturing example was coated onto a polyester film (Toray Advanced Materials, XG7AH7, 50 μm), and after curing, the thickness was 5 μm. After drying, it was irradiated with UV cumulative light intensity of 600 mJ / cm under a nitrogen atmosphere. 2 This process creates a hard coating.

[0086] Experimental Example 1:

[0087] The physical properties of the hard coatings manufactured in the above embodiments and comparative examples were measured as follows, and the results are shown in Table 2 below.

[0088] (1) Water contact angle

[0089] After dropping 2 μl of water onto the coating surface of the hard coating film manufactured in the above embodiments and comparative examples, the water contact angle was measured using a KRUSS DSA100.

[0090] (2) Abrasion resistance

[0091] The abrasion resistance was measured using a wear resistance testing machine from Taisei Precision Machinery Co., Ltd. Specifically, the coating surface was rubbed 5,000 times with an abrasion resistance test rubber and a 500g weight, and then a water droplet was dropped to measure the contact angle. The abrasion resistance was evaluated according to the following evaluation criteria.

[0092] <Evaluation Criteria>

[0093] ○: Contact angle of 100° or more

[0094] ×: Contact angle less than 100°

[0095] (3) Resistance to chemical reagents

[0096] The abrasion resistance was measured using a wear resistance testing machine from Taisei Precision Machinery Co., Ltd. Specifically, using an abrasion resistance test rubber and a 500g weight, the coating surface was rubbed 3,000 times in the presence of ethanol. A water droplet was then dropped to measure the contact angle, and the abrasion resistance was evaluated according to the following evaluation criteria.

[0097] <Evaluation Criteria>

[0098] ○: Contact angle of 100° or more

[0099] ×: Contact angle less than 100°

[0100] (4) Tensile properties

[0101] Tensile properties were evaluated using a UTM (Universal Tensile Testing Machine). The hard coating was fixed to a load cell and subjected to tensile testing. The elongation at the point where cracks appeared in the hard coating was recorded.

[0102] (5) Finger gliding

[0103] The smoothness of the coating is evaluated by rubbing the hardened coating with your fingers 10 times.

[0104] ◎: Excellent sliding properties

[0105] ○: Excellent sliding properties

[0106] △: Slightly better sliding performance

[0107] ×: Poor slippage

[0108] [Table 2]

[0109]

[0110] As can be confirmed by Table 2 above, the hard coating films of Examples 1 to 3 formed from transparent resins containing tri- to hexafunctional (meth)acrylates and hexafunctional urethane (meth)acrylates with ethylene oxide and hard coating compositions containing fluorine-based UV-curable functional group compounds exhibit excellent tensile properties, a high water contact angle, and excellent abrasion resistance, chemical resistance, and finger slip resistance.

[0111] In contrast, it was confirmed that the hard coating films of Comparative Examples 1 to 5, which used hard coating compositions that did not contain any of the tri- to hexafunctional (meth)acrylates and hexafunctional urethane (meth)acrylates containing ethylene oxide, had poorer tensile strength, or exhibited lower water contact angle, or poorer abrasion resistance, chemical resistance, or finger slippage.

[0112] The foregoing has described specific aspects of the present invention in detail. It will be apparent to those skilled in the art that these specific descriptions are merely preferred embodiments, and the scope of the present invention is not limited thereto. Those skilled in the art will be able to make diverse applications and modifications within the scope of the present invention based on the above content.

[0113] Therefore, the essential scope of the invention will be defined by the appended claims and their equivalents.

Claims

1. A hard coating film comprising a transparent substrate and a hard coating layer formed on at least one side of the transparent substrate, wherein, The hard coating is formed from a hard coating composition comprising a transparent resin, a photoinitiator, a fluorine-containing UV-curable functional compound, and a solvent. The light-transmitting resin comprises tri- to hexafunctional (meth)acrylates and hexafunctional urethane (meth)acrylates containing ethylene oxide.

2. The hard coating film according to claim 1, wherein, The content of the fluorine-containing UV-curable functional compound is from 0.01 to 40% by weight relative to 100% by weight of the total solid components in the hard coating composition.

3. The hard coating film according to claim 1, wherein, The ethylene oxide-containing tri- to hexafunctional (meth)acrylate is a compound represented by the following chemical formula 1: Chemical Formula 1 In the above formula, The sum of a, b, c, and d is 5.

4. The hard coating film according to any one of claims 1 to 3, wherein, Relative to 100% by weight of the overall translucent resin, the content of the tri- to hexafunctional (meth)acrylate containing ethylene oxide is 50 to 90% by weight, and the content of the hexafunctional urethane (meth)acrylate is 10 to 50% by weight.

5. The hard coating film according to claim 1, wherein, The light-transmitting resin further comprises dendritic acrylates.

6. The hard coating film according to claim 5, wherein, Relative to 100% by weight of the overall translucent resin, the content of the tri- to hexafunctional (meth)acrylate containing ethylene oxide is 50 to 70% by weight, the content of the hexafunctional urethane (meth)acrylate is 10 to 20% by weight, and the content of the dendritic acrylate is 20 to 30% by weight.

7. An image display device comprising a hard coating according to any one of claims 1 to 6.

8. A window of a foldable display device having a hard coating according to any one of claims 1 to 6.

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