Coating film comprising coating layer and display device comprising same

Abstract

An embodiment of the present invention provides a coating film and a display device comprising the coating film, the coating film comprising: a light-transmitting substrate; and a coating layer on the light-transmitting substrate, wherein the light-transmitting substrate comprises at least one of an imide repeating unit and an amide repeating unit, the coating layer is formed of a coating composition, the coating composition comprises an alicyclic epoxy compound, an initiator, and a solvent, and the alicyclic epoxy compound includes a compound represented by chemical formula 1 below.

Description

Coating film including a coating layer and a display device including the same

[0001] The present invention relates to a coating film including a coating layer and a display device including the coating film.

[0002] Light-transmitting films are a key material in the optical and flexible display fields, and their importance is growing. Light-transmitting films are being used as a replacement for glass in the display field, particularly due to their light weight, ease of processability, and flexibility. Conventional light-transmitting films are known to have lower mechanical properties than glass, such as low surface hardness and low abrasion resistance. Research is being conducted to improve the mechanical properties of light-transmitting films for their application in the display field.

[0003] One method for improving the mechanical or optical properties of a light-transmitting film is to place a coating layer on the surface of the light-transmitting film. A light-transmitting film with a coating layer placed thereon is also called a coated film.

[0004] One embodiment of the present invention is to provide a coating film including a coating layer having excellent flexibility.

[0005] One embodiment of the present invention is to provide a coating film having excellent hardness and excellent scratch resistance.

[0006] One embodiment of the present invention is to provide a coating film having excellent light resistance and excellent coating adhesion even after a light resistance test.

[0007] Another embodiment of the present invention is to provide a display device including a coating film having the above properties.

[0008] According to one embodiment of the present invention for solving the above problem, a coating film includes a light-transmitting substrate and a coating layer on the light-transmitting substrate, wherein the light-transmitting substrate includes at least one of an imide repeating unit and an amide repeating unit, and the coating layer is formed by a coating composition, wherein the coating composition includes an alicyclic epoxy compound, an initiator, and a solvent, and the alicyclic epoxy compound may include a compound represented by the following chemical formula 1.

[0009] [Chemical Formula 1]

[0010]

[0011] In the above chemical formula 1, L and L' are the same or different and are a C4 to C10 alicyclic alkylene group,

[0012] R1, R2, R3, R4, R 5, R 6, R7 and R8 is each independently selected from the group consisting of hydrogen, a C1 to C4 alkyl group, a C1 to C4 alkoxy group, and combinations thereof.

[0013] According to one embodiment of the present invention, the alicyclic epoxy compound may include at least one of a compound represented by the following chemical formula 2 and a compound represented by the following chemical formula 3.

[0014] [Chemical Formula 2]

[0015]

[0016] [Chemical Formula 3]

[0017]

[0018] In the above chemical formula 2, R1, R2, R3, R4, R 5, R 6, R7 and R8 is each independently selected from the group consisting of hydrogen, a C1 to C4 alkyl group, a C1 to C4 alkoxy group, and combinations thereof,

[0019] In the above chemical formula 3, R1, R2, R3, R4, R 5, R 6, R7 and R8 is each independently selected from the group consisting of hydrogen, a C1 to C4 alkyl group, a C1 to C4 alkoxy group, and combinations thereof.

[0020]

[0021] *According to one embodiment of the present invention, the alicyclic epoxy compound may include at least one of 3,3'-Bi-7-oxabicyclo[4.1.0]heptane, 3,3'-Bi-6-oxabicyclo[3.1.0]hexane, and 5-methyl-3,3'-Bi-7-oxabicyclo[4.1.0]heptane.

[0022] According to one embodiment of the present invention, the coating composition may further include a filler.

[0023]

[0024] *According to one embodiment of the present invention, the filler may include at least one of silica (SiO2), aluminum oxide (Al2O3), and zirconium oxide (ZrO2).

[0025] According to one embodiment of the present invention, the light-transmitting substrate may include an imide repeating unit formed by a diamine compound and a dianhydride compound; and an amide repeating unit formed by a diamine compound and a dicarbonyl compound.

[0026] According to one embodiment of the present invention, the coating layer can satisfy all of the following equations 1 to 3.

[0027] [Formula 1]

[0028] A < 5

[0029] [Formula 2]

[0030] B < 3

[0031] [Formula 3]

[0032] C < 1

[0033] Here, A in the above formula 1 means the number of scratches with a length of less than 1 mm,

[0034] B in Equation 2 represents the number of scratches with a length of 1 mm to 5 mm,

[0035] C in Equation 3 represents the number of scratches longer than 5 mm,

[0036] The above number of scratches means the number of scratches by length observed with the naked eye after cutting the coating film to a size of 100 mm x 50 mm to produce a coating film sample, fixing the coating film sample to a flat surface using 3M Scotch Magic Tape (Cat. 810D) with the coating layer facing upward, and then moving the surface of the coating layer of the coating film sample back and forth 10 times at a load of 0.5 kgf and a speed of 45 RPM with a stainless steel (SUS) jig of size 20 mm x 20 mm wrapped with #0000 (LIBERON) nonwoven fabric.

[0037] A coating film according to one embodiment of the present invention may have a coating adhesion of 4B or a coating adhesion of 5B after a light resistance test.

[0038] Here, the light resistance test is conducted under the conditions of a temperature of 30°C and a humidity of 55RH%, maintaining the temperature of the Black Panel at 55°C, and irradiating the coating film with a Xenon Lamp light source of 420 nm wavelength at an intensity of 1.1 W / ㎡ for 150 hours.

[0039] The above coating adhesion is evaluated by the peeling test results of the above coating film,

[0040] The above peeling test is performed by forming 100 grid patterns (10 x 10) of 1 mm x 1 mm size on the coating layer of the coating film using a cutter knife, attaching 3M Scotch Box Tape (48 mm, transparent) (#3650) to the surface of the coating layer, and then removing the tape within 0.1 second. The number of grid patterns among the 100 grid patterns that are separated from the light-transmitting substrate and attached to the tape is measured.

[0041] The above 4B coating adhesion means that the number of the grid patterns separated from the light-transmitting substrate and attached to the tape is 1 to 5 as a result of the peeling test of the coating film,

[0042] The coating adhesion of the above 5B means that, as a result of the peeling test of the above coating film, there is no grid pattern attached to the tape separated from the light-transmitting substrate.

[0043] A coating film according to one embodiment of the present invention may have a lattice peeling rate of 5% or less after a light resistance test.

[0044] Here, the lattice peeling ratio is calculated according to the following equation 4,

[0045] [Formula 4]

[0046]

[0047] The number of peeled grid patterns in the above formula 4 is measured according to the peeling test of the above coating film,

[0048] The above peeling test is performed by forming 100 grid patterns (10 x 10) of 1 mm x 1 mm size on the coating layer of the coating film using a cutter knife, attaching 3M Scotch Box Tape (48 mm, transparent) (#3650) to the surface of the coating layer, and then removing the tape within 0.1 second. The number of grid patterns among the 100 grid patterns that are separated from the light-transmitting substrate and attached to the tape is measured.

[0049] According to one embodiment of the present invention, the coating film may have a crack point of less than 1.0 mm after a light resistance test based on a thickness of 55 μm.

[0050] Here, the crack point is calculated by the following equation 5,

[0051] [Formula 5]

[0052] Crack point = ((Out-folding crack point radius + In-folding crack point radius) / 2

[0053] The Out-folding crack point radius of the above formula 5 means the radius of curvature (R) of the coating film sample measured at the moment when a crack occurs in the coating film sample when the coating film sample with a size of 20 mm x 100 mm is mounted on a Radius Bending Tester so that the coating layer formation surface is positioned in the outer direction of the bending direction and the coating film sample is repeatedly bent so that the radius of curvature gradually decreases.

[0054] The in-folding crack point radius of the above formula 5 means the radius of curvature (R) of the coating film sample measured in the same manner as the out-folding crack point radius measurement method after mounting the coating film sample of size 20 mm x 100 mm on a Radius Bending Tester so that the coating layer formation surface is positioned inward in the bending direction.

[0055] According to one embodiment of the present invention, the coating film can have an elongation of 10% or more after a light resistance test based on a thickness of 55 μm.

[0056] According to one embodiment of the present invention, the coating film may have a pencil hardness of 4H or more based on a thickness of 55 μm.

[0057] Another embodiment of the present invention provides a display device including a display panel and the coating film disposed on the display panel.

[0058] A coating film according to one embodiment of the present invention can have excellent surface hardness and scratch resistance by including a coating layer formed by a coating composition including an epoxy compound having an alicyclic structure.

[0059] According to one embodiment of the present invention, a carbon-oxygen-carbon bond is formed during a curing reaction of an alicyclic epoxy compound included in a coating composition, so that shrinkage after curing is small, and a coating film formed using the coating composition can have excellent flexibility.

[0060] According to one embodiment of the present invention, the coating layer has excellent light resistance and can maintain excellent coating adhesion to a light-transmitting substrate even after a light resistance test.

[0061] A coating film according to one embodiment of the present invention can be used by being attached to the display surface of a display device. A display device including the coating film can have excellent surface hardness and flexibility.

[0062] FIG. 1 is a schematic cross-sectional view of a coating film according to one embodiment of the present invention.

[0063] FIG. 2 is a schematic cross-sectional view illustrating a grid pattern formation process in a peel test according to one embodiment of the present invention.

[0064] Figures 3a and 3b are schematic cross-sectional views illustrating measurements of the in-folding crack point radius and out-folding crack point radius of a coating film.

[0065] FIG. 4 is a cross-sectional view of a portion of a display device according to another embodiment of the present invention.

[0066] Figure 5 is an enlarged cross-sectional view of portion “P” of Figure 4.

[0067] The present invention will be described in detail below, focusing on examples. The examples described below are provided for illustrative purposes only to facilitate a clear understanding of the present invention and do not limit its scope.

[0068] In this specification, where "includes," "has," and "consists of" are used, other parts may be added, unless the expression "only" is used. When a component is expressed in the singular, the plural is included unless otherwise explicitly stated. Furthermore, when interpreting a component, it is interpreted to include a margin of error, even if there is no explicit indication otherwise.

[0069] When describing a positional relationship, for example, when the positional relationship between two parts is described as 'on top of', 'upper part of', 'lower part of', 'next to', etc., one or more other parts may be located between the two parts, unless the expression 'right' or 'directly' is used.

[0070] When describing a temporal relationship, for example, when the temporal relationship is described as 'after', 'following', 'next to', 'before', etc., it can also include cases where it is not continuous, as long as the expression 'immediately' or 'directly' is not used.

[0071] While terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, a "first" component referred to below may also be a "second" component within the technical scope of the present invention.

[0072] The term "at least one" should be understood to include all possible combinations of one or more associated items. For example, "at least one of the first, second, and third items" can mean any combination of items that can be represented by two or more of the first, second, and third items, as well as each of the first, second, and third items.

[0073] The features of each of the various embodiments of the present invention can be partially or wholly combined or combined with each other, and various technical connections and operations are possible, and each embodiment can be implemented independently of each other or implemented together in a related relationship.

[0074] Figure 1 is a schematic cross-sectional view of a coating film (100) according to one embodiment of the present invention.

[0075] Referring to FIG. 1, a coating film (100) according to one embodiment of the present invention includes a light-transmitting substrate (110) and a coating layer (120) on the light-transmitting substrate (110).

[0076] A light-transmitting film can be used as the light-transmitting substrate (110). A polyimide-based (PI) film can be used as the light-transmitting film. Examples of the polyimide-based (PI) film include a polyimide film, a polyamide film, and a polyamide-imide film.

[0077] A polyimide-based film according to one embodiment of the present invention can be manufactured from a composition comprising a dianhydride compound and a diamine compound. More specifically, a polyimide-based film according to one embodiment of the present invention can have imide repeating units formed by the dianhydride compound and the diamine compound. An example of a polyimide-based film having imide repeating units is a polyimide film.

[0078] A polyimide-based film according to one embodiment of the present invention can be manufactured from a composition comprising a dicarbonyl compound and a diamine compound. More specifically, a polyimide-based film according to one embodiment of the present invention can have amide repeating units formed by the dicarbonyl compound and the diamine compound. An example of a polyimide-based film having amide repeating units is a polyamide film.

[0079]

[0080] *A polyimide-based film according to one embodiment of the present invention may be manufactured from a composition further comprising a dicarbonyl compound in addition to a dianhydride compound and a diamine compound. More specifically, a polyimide-based film according to one embodiment of the present invention may have an imide repeating unit formed by a dianhydride compound and a diamine compound, and an amide repeating unit formed by a dicarbonyl compound and a diamine compound. An example of a polyimide-based film having an imide repeating unit and an amide repeating unit is a polyamide-imide film.

[0081] According to one embodiment of the present invention, the diamine monomer is, for example, bis trifluoromethyl benzidine (2,2'-bis(trifluoromethyl)benzidine, TFDB), oxydianiline (4,4'-Oxydianiline, ODA), p-phenylenediamine (para-phenylene diamine, pPDA), m-phenylenediamine (meta-phenylene diamine, mPDA), p-methylene diamine (para-methylene diamine, pMDA), m-methylene diamine (meta-methylene diamine, mMDA), bis aminophenoxy benzene (1,3-bis(3-aminophenoxy) benzene, 133APB), bis aminophenoxy benzene (1,3-bis(4-aminophenoxy) benzene, 134APB), bis amino phenoxy phenyl hexafluoropropane (2,2'-bis[4(4-aminophenoxy)phenyl] hexafluoropropane (4BDAF), bisaminophenyl hexafluoropropane (2,2'-bis(3-aminophenyl)hexafluoropropane, 33-6F), bisaminophenyl hexafluoropropane (2,2'-bis(4-aminophenyl)hexafluoropropane, 44-6F), bisaminophenyl sulfone (bis(4-aminophenyl)sulfone, 4DDS), bisaminophenyl sulfone (bis(3-aminophenyl)sulfone, 3DDS), cyclohexanediamine (1,3-Cyclohexanediamine, 13CHD), cyclohexanediamine (1,4-Cyclohexanediamine, 14CHD), bisaminophenoxy phenylpropane (2,2-Bis[4-(4-aminophenoxy)-phenyl]propane, 6HMDA), bisaminohydroxy phenyl 2,2-Bis(3-amino-4-hydroxy-phenyl)-hexafluoropropane (DBOH), bisaminophenoxy diphenyl sulfone (4,It may include at least one of 4'-Bis(3-amino phenoxy) diphenyl sulfone, DBSDA). However, it is not limited thereto. One type of diamine compound may be used, or two or more types may be used.

[0082] According to one embodiment of the present invention, the dianhydride compound is, for example, biphenyl tetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA), 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellictic acid dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, pyromellicticacid dianhydride, PMDA), benzophenone tetracarboxylic dianhydride (3,3,4,4-Benzophenone tetracarboxylic dianhydride, BTDA), oxydiphthalic dianhydride (4,4-Oxydiphthalic The composition may include at least one of: bis(3,4-dicarboxyphenyl)dimethyl-silane dianhydride (SiDA), bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride (BDSDA), sulfonyldiphthalic anhydride (SO2DPA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), isopropylideneiphenoxy bis phthalic anhydride (4,4'-(4,4'-Isopropylidenediphenoxy) bis(phthalic anhydride, 6HBDA), but is not limited thereto. One type of dianhydride compound may be used, or two or more types may be used.

[0083] According to one embodiment of the present invention, the dicarbonyl compound may include at least one of, for example, terephthaloyl chloride (TPC), phthaloyl chloride, isophthaloyl chloride (IPC), 4,4'-biphenyldicarbonyl chloride (DPDOC), 4,4'-oxybis(benzoyl chloride, OBBOC), naphthalene-2,3-dicarbonyl dichloride, and cyclohexanedicarbonyldichloride (1,4-Cyclohexanedicabonyldichloride, CHDOC). However, the present invention is not limited thereto. One type of the dicarbonyl compound may be used, or two or more types may be used.

[0084] However, one embodiment of the present invention is not limited thereto, and a polycarbonate film (PC), a polyacrylic film, a polyethylene terephthalate film, a cellulose film, or the like may be used as the light-transmitting substrate (110).

[0085] According to one embodiment of the present invention, there is no particular limitation on the thickness of the light-transmitting substrate (110). The light-transmitting substrate (110) may have a thickness sufficient to allow the coating film (100) to protect the display panel. For example, the light-transmitting substrate (110) may have a thickness of 10 to 100 μm.

[0086] According to one embodiment of the present invention, a coating layer (120) may be formed on at least one surface of a light-transmitting substrate (110). The coating layer (120) may be formed on the upper surface of the light-transmitting substrate (110), may be formed on the lower surface, or may be formed on both the upper and lower surfaces.

[0087] According to one embodiment of the present invention, the coating layer (120) can have excellent surface properties and excellent flexibility. As a result, the coating film (100) including the coating layer (120) can have excellent surface properties and excellent flexibility.

[0088] According to one embodiment of the present invention, the coating layer (120) may have a thickness of 5 to 20 μm. If the thickness of the coating layer (120) is less than 5 μm, the scratch resistance characteristics of the coating film (100) due to the coating layer (120) may not be sufficiently exhibited. If the thickness of the coating layer (120) exceeds 20 μm, the thickness of the coating film (100) becomes unnecessarily thick, and the flexibility of the coating film (100) may be reduced.

[0089] According to one embodiment of the present invention, a coating layer (120) can be formed on a light-transmitting substrate (110) by a coating composition.

[0090] According to one embodiment of the present invention, the coating layer (120) may include an epoxy resin. The coating layer (120) may be formed by a coating composition including an epoxy compound.

[0091] For example, the coating layer (120) may be formed by a coating composition including an alicyclic epoxy compound. The alicyclic epoxy compound may include an alicyclic structure within its structure and may have an epoxy group bonded to the alicyclic structure.

[0092] According to one embodiment of the present invention, the alicyclic epoxy compound may include, for example, a compound represented by the structure of the following chemical formula 1.

[0093] [Chemical Formula 1]

[0094]

[0095] In the above chemical formula 1, L and L' are the same or different and may be a C4 to C10 alicyclic alkylene group.

[0096] In the above chemical formula 1, R1, R2, R3, R4, R 5, R 6, R7 and R8 can be independently selected from the group consisting of hydrogen, C1 to C4 alkyl group, C1 to C4 alkoxy group and combinations thereof. R1, R2, R3, R4, R 5, R 6, R7 and R8s can all be the same, some can be the same, or they can all be different.

[0097] Above R1, R 2, At least two of R3 and R4 may be bonded to the same carbon among the carbons contained in L, or may not be bonded to the same carbon.

[0098] Above R5, R 6, At least two of R7 and R8 may be bonded to the same carbon among the carbons contained in L', or may not be bonded to the same carbon.

[0099] According to one embodiment of the present invention, an alicyclic epoxy compound represented by the structure of Chemical Formula 1 has a structure in which alicyclic epoxy groups are directly connected, and thus may have superior environmental resistance compared to an alicyclic epoxy compound having a structure in which alicyclic epoxy groups are connected through another linking group, for example, a linking group having an ester structure. More specifically, a cured product of a coating composition including an alicyclic epoxy compound represented by the structure of Chemical Formula 1 may not easily deform even when exposed to a high temperature and high humidity environment.

[0100] In addition, the alicyclic epoxy compound represented by the structure of chemical formula 1 has a structure in which alicyclic epoxy groups are directly connected, and thus has a relatively short chain length compared to an alicyclic epoxy compound having a structure in which alicyclic epoxy groups are connected through another connecting group, such as an Ester structure and an Ether structure, and thus can have excellent surface hardness.

[0101] In general, to improve the physical properties of the film, such as surface hardness, resilience, and flexibility, a coating layer is formed on the film using an acrylic coating composition or a siloxane coating composition.

[0102] The coating layer formed by the acrylic coating composition has excellent surface hardness and resilience, and has excellent flexibility compared to the coating layer formed by the siloxane coating composition, but the shrinkage of the cured product is relatively high, which may cause curling in the film.

[0103] A coating layer formed by a siloxane-based coating composition has superior surface hardness and resilience compared to a coating layer formed by an acrylic-based coating composition, but may lack flexibility.

[0104] On the other hand, in the coating film (100) according to one embodiment of the present invention, an epoxy-based coating composition may be used to form a coating layer (120).

[0105] The alicyclic epoxy compound included in the coating composition according to one embodiment of the present invention has a structure as represented by Chemical Formula 1, and can form a carbon-oxygen-carbon unit bond structure upon curing. Therefore, the cured product exhibits less shrinkage than an acrylic compound that forms a carbon-carbon unit bond structure upon curing, and the length of the formed unit bond structure is longer than that of the acrylic compound, thereby providing excellent flexibility. In addition, since it does not contain inorganic elements such as Si within the polymer chain, it provides excellent flexibility compared to siloxane compounds, and since it includes an alicyclic structure, it can provide excellent surface hardness compared to compounds having a linear structure.

[0106] According to one embodiment of the present invention, the alicyclic epoxy compound may include, for example, at least one of a compound represented by the following chemical formula 2 and a compound represented by the following chemical formula 3.

[0107] [Chemical Formula 2]

[0108]

[0109] [Chemical Formula 3]

[0110]

[0111] In chemical formula 2, R1, R2, R3, R4, R 5, R 6, R7 and R8 can be independently selected from the group consisting of hydrogen, C1 to C4 alkyl group, C1 to C4 alkoxy group and combinations thereof. In addition, in chemical formula 2, R1, R2, R3, R4, R 5, R 6, R7 and R8s can all be the same, some can be the same, or they can all be different.

[0112] In chemical formula 3, R1, R2, R3, R4, R 5, R 6, R7 and R8 can be independently selected from the group consisting of hydrogen, C1 to C4 alkyl group, C1 to C4 alkoxy group and combinations thereof. In addition, in chemical formula 3, R1, R2, R3, R4, R 5, R 6, R7 and R8s can all be the same, some can be the same, or they can all be different.

[0113] According to one embodiment of the present invention, the alicyclic epoxy compound may include, for example, at least one of 3,3'-Bi-7-oxabicyclo[4.1.0]heptane, 3,3'-Bi-6-oxabicyclo[3.1.0]hexane, and 5-methyl-3,3'-Bi-7-oxabicyclo[4.1.0]heptane.

[0114] According to one embodiment of the present invention, the alicyclic epoxy compound may include, for example, at least one of the compounds represented by the following chemical formulae 4 to 6.

[0115] [Chemical Formula 4]

[0116]

[0117] [Chemical Formula 5]

[0118]

[0119] [Chemical Formula 6]

[0120]

[0121] According to one embodiment of the present invention, the coating composition may include an initiator.

[0122] An initiator may be used to cure the coating composition. Either a photopolymerization initiator or a thermal polymerization initiator may be used as the initiator for curing the coating composition. If necessary, both a photopolymerization initiator and a thermal polymerization initiator may be used simultaneously.

[0123] According to one embodiment of the present invention, at least one or more of triazine-based, acetophenone-based, benzophenone-based, thioxanthone-based, benzoin-based, phosphorus-based, and oxime-based photopolymerization initiators may be used, but the present invention is not limited thereto.

[0124] More specifically, the coating composition may include at least one photopolymerization initiator selected from the group consisting of Diphenyl[4-(phenylthio)phenyl]sulfonium hexafluoroantimonate, [4-(Octyloxy)phenyl](phenyl) iodonium Hexafluoroantimonate, Bis(4-methylphenyl)iodonium hexafluorophosphate, and (4-Isobutylphenyl)(p-tolyl)iodonium hexafluorophosphate.

[0125] According to one embodiment of the present invention, when the coating composition includes a photopolymerization initiator, for example, UV-A 50 to 1,500 mW / cm 2 and 0.5 to 5 J / cm 2Photopolymerization and photocuring can be carried out by light irradiation under the conditions of UV-A 120mW / cm 2 and 2J / cm 2 Photopolymerization and photocuring can be carried out by light irradiation under the conditions.

[0126] According to one embodiment of the present invention, the thermal polymerization initiator may include, for example, at least one thermal polymerization initiator selected from among imidazole, amine, phthalic anhydride, and 2,2'-Azobis(2-methylpropionitrile) (AIBN).

[0127] According to one embodiment of the present invention, when the coating composition includes a thermal polymerization initiator, thermal polymerization and thermal curing may be performed by heat irradiation at, for example, 80 to 200°C for 5 to 30 minutes. More specifically, thermal polymerization and thermal curing may be performed by heat irradiation at 200°C for 10 minutes.

[0128] According to one embodiment of the present invention, when heat irradiation is performed according to the heat irradiation conditions of the thermal polymerization initiator instead of light irradiation on a coating composition including a photopolymerization initiator, the photopolymerization initiator can also be used as a cationic initiator, and thus, heat polymerization and heat curing of the coating composition can proceed.

[0129] According to one embodiment of the present invention, the content of the initiator is not particularly limited, but may be included in an amount of about 0.5 to 5.0 parts by weight relative to 100 parts by weight of the alicyclic epoxy compound.

[0130] According to one embodiment of the present invention, the coating composition may include a solvent.

[0131] According to one embodiment of the present invention, a solvent may be used to form a coating layer (120). The viscosity of the coating composition may be controlled by the solvent, and accordingly, the processability of the coating composition may be controlled, so that the thickness of the coating layer (120) may be easily adjusted.

[0132] As the solvent, at least one selected from the group consisting of, but not limited to, ketones such as acetone, 2-butanone (methyl ethyl ketone), methyl butyl ketone, and cyclohexanone; cellosolves such as methyl cellosolve and butyl cellosolve; ethers such as ethyl ether and dioxane; alcohols such as isobutyl alcohol, isopropyl alcohol, butanol, and methanol; halogenated hydrocarbons such as dichloromethane, chloroform, and trichloroethylene; and hydrocarbons such as normal hexane, benzene, and toluene may be used.

[0133] According to one embodiment of the present invention, the content of the solvent is not particularly limited, but may be included in an amount of about 80 to 120 parts by weight based on 100 parts by weight of solid content.

[0134] According to one embodiment of the present invention, the solvent may be included in an amount equal to, for example, the amount of the solid component included in the coating composition.

[0135] According to one embodiment of the present invention, the coating composition can be used to form a coating layer (120) having excellent surface properties and flexibility by including an alicyclic epoxy compound, an initiator, and a solvent.

[0136] A coating composition according to one embodiment of the present invention may further include, if necessary, one or more additives selected from the group consisting of fillers, antioxidants, leveling agents, UV absorbers, UV shielding agents, and coating agents.

[0137] According to one embodiment of the present invention, the coating composition may further comprise a filler.

[0138] According to one embodiment of the present invention, the filler may include at least one of silica (SiO2), aluminum oxide (Al2O3), and zirconium oxide (ZrO2).

[0139] According to one embodiment of the present invention, the scratch resistance of the coating layer (120) can be improved by further including a filler in the coating composition.

[0140] According to one embodiment of the present invention, the particle size of the filler may be, for example, 5 to 20 nm, but is not limited thereto.

[0141] According to one embodiment of the present invention, the content of the filler may be included in an amount of, for example, 40 parts by weight or less with respect to 100 parts by weight of the alicyclic epoxy compound.

[0142] When the content of the filler included in the coating composition exceeds 40 parts by weight per 100 parts by weight of the alicyclic epoxy compound, the light transmittance of the coating film (100) may decrease, haze may increase, and flexibility may be insufficient.

[0143] According to one embodiment of the present invention, the coating layer (120) of the coating film (100) can satisfy all of the following equations 1 to 3.

[0144] [Formula 1]

[0145] A < 5

[0146] [Formula 2]

[0147] B < 3

[0148] [Formula 3]

[0149] C < 1

[0150] Here, A in the above formula 1 means the number of scratches with a length of less than 1 mm, B in the formula 2 means the number of scratches with a length of 1 mm to 5 mm, and C in the formula 3 means the number of scratches with a length of more than 5 mm.

[0151] According to one embodiment of the present invention, the number of scratches is defined as the number of scratches by cutting the coating film (100) into a size of 100 mm x 50 mm to prepare a coating film sample, fixing the coating film sample to a flat surface using an adhesive tape (e.g., 3M Scotch Magic Tape (Cat. 810D)) so that the coating layer (120) faces upward, and then moving the surface of the coating layer (120) of the coating film sample back and forth 10 times at a load of 0.5 kgf and a speed of 45 RPM with a stainless steel (SUS) jig of 20 mm x 20 mm wrapped with #0000 (LIBERON) nonwoven fabric, and then the number of scratches is observed with the naked eye.

[0152] According to one embodiment of the present invention, the coating layer (120) of the coating film (100) may have less than 5 scratches less than 1 mm, may have less than 3 scratches, may have less than 2 scratches, or may have none.

[0153] According to one embodiment of the present invention, the coating layer (120) of the coating film (100) may have less than three scratches of 1 mm to 5 mm, may have less than two scratches, or may have none.

[0154] According to one embodiment of the present invention, the coating layer (120) of the coating film (100) may not have a scratch exceeding 5 mm.

[0155] If the coating layer (120) does not satisfy any one of Equations 1 to 3, scratches are likely to occur on the surface of the coating layer (120) due to external force, and thus, for example, it may be difficult to use it as a cover window of a display device.

[0156] According to one embodiment of the present invention, even if the coating layer (120) undergoes a scratch-inducing process, very few or no scratches are generated. Therefore, the coating film (100) according to one embodiment of the present invention including the coating layer (120) can be said to have excellent scratch resistance.

[0157] When a coating film (100) according to one embodiment of the present invention is used as a cover window of a display device (200), the coating film (100) is exposed to a scratch environment. Since the coating film (100) according to one embodiment of the present invention has excellent scratch resistance, even when the coating film (100) is used as a cover window of a display device (200), scratches may not occur, or may hardly occur.

[0158] The coating film (100) according to one embodiment of the present invention may have a coating adhesion of 4B or a coating adhesion of 5B after a light resistance test.

[0159] The light resistance test of the coating film (100) is performed, for example, using Ci3000+ equipment from ATLAS, under conditions of a temperature of 30°C and a humidity of 55RH%, by maintaining the temperature of the black panel at 55°C and irradiating the coating film (100) with a Xenon Lamp light source of 420 nm wavelength at an intensity of 1.1 W / ㎡ for 150 hours.

[0160] The coating adhesion after the light resistance test of the coating film (100) refers to the coating adhesion between the coating layer (120) and the light-transmitting substrate (110) after the coating film (100) is aged by irradiating it with light.

[0161] The coating adhesion of the coating film (100) refers to the adhesion between the light-transmitting substrate (110) and the coating layer (120), and can be evaluated based on the results of a peeling test of the coating film (100). More specifically, the number of grid patterns (120a) separated from the light-transmitting substrate (110) and attached to the tape is measured through a peeling test of the coating film (100), and the number of measured grid patterns (120a) is evaluated based on the classification criteria below. According to the classification criteria below, the coating adhesion is better as it goes from 0B to 5B, that is, the fewer the number of grid patterns (120a) separated from the light-transmitting substrate (110), the better.

[0162] [Coating Adhesion Classification Criteria]

[0163] 5B: No grid pattern (120a) separated from the light-transmitting substrate (110).

[0164] 4B: 1 to 5 grid patterns (120a) separated from the light-transmitting substrate (110)

[0165] 3B: 6 to 15 grid patterns (120a) separated from the light-transmitting substrate (110)

[0166] 2B: 16 to 35 grid patterns (120a) separated from the light-transmitting substrate (110)

[0167] 1B: 36 to 65 grid patterns (120a) separated from the light-transmitting substrate (110)

[0168] 0B: 66 or more grid patterns (120a) separated from a light-transmitting substrate (110)

[0169] According to one embodiment of the present invention, a peeling test of a coating film (100) is performed by forming 100 (10 x 10) grid patterns (120a) of 1 mm x 1 mm size on a coating layer (120) of a coating film (100) using a cutter knife, attaching 3M Scotch Box Tape (48 mm, transparent) (#3650) to the surface of the coating layer (120), and then removing the tape within 0.1 second, and measuring the number of grid patterns (120a) that are separated from the light-transmitting substrate (110) and attached to the tape among the 100 formed grid patterns (120a).

[0170] In the above peeling test, the grid pattern (120a) can be formed as follows.

[0171] FIG. 2 is a schematic cross-sectional view illustrating a process of forming a grid pattern (120a) in a peeling test according to one embodiment of the present invention.

[0172] Referring to FIG. 2, the grid pattern (120a) is formed by cutting from the surface where the coating layer (120) is formed to a portion of the light-transmitting substrate (110) based on the thickness direction of the coating film (100) using a cutter knife (K).

[0173] More specifically, the light-transmitting substrate (110) is cut to a thickness of 0.2T to 0.3T in the thickness direction from the surface on which the coating layer (120) is formed, when the total thickness of the light-transmitting substrate (110) is T. Accordingly, a cutting groove (120b) is formed that penetrates from the surface of the coating layer (120) to a portion of the light-transmitting substrate (110).

[0174] According to one embodiment of the present invention, by forming the cutting grooves (120b) at intervals of 1 mm in width and length so that 100 grid patterns (120a) of 1 mm x 1 mm (10 width x 10 height) are formed in the coating layer (120) of the coating film (100), the grid pattern (120a) required in the peeling test is finally formed.

[0175] According to one embodiment of the present invention, if the coating film (100) does not satisfy the coating adhesion of 4B and the coating adhesion of 5B after the light resistance test, for example, if the coating film (100) is placed as a cover window of a display device (200) and exposed to an external light source for a long period of time, the coating adhesion of the coating layer (120) may be reduced, causing a portion of the coating layer (120) to be lifted off, and separation of the coating layer (120) and the light-transmitting substrate (110) may occur.

[0176] According to one embodiment of the present invention, the alicyclic epoxy compound included in the coating composition may have, for example, no double bonds in its structure, and thus may be less prone to deformation due to external light irradiation after curing. Accordingly, the coating film (100) according to one embodiment of the present invention has excellent light resistance, is less prone to aging due to a light source, and even if aging occurs, can maintain excellent coating adhesion of 4B or 5B.

[0177] A coating film (100) according to one embodiment of the present invention can have a coating adhesion of 5B before a light resistance test.

[0178] The details of the coating adhesion and peeling test of the coating film (100) are the same as those described above, so they are omitted.

[0179] According to one embodiment of the present invention, since the coating layer (120) has excellent adhesion to the light-transmitting substrate (110), the coating film (100) can have excellent coating adhesion of 5B before the light resistance test.

[0180] The coating film (100) according to one embodiment of the present invention may have a lattice peeling rate of 5% or less after a light resistance test.

[0181] According to one embodiment of the present invention, the lattice peeling ratio is calculated according to the following equation 4.

[0182] [Formula 4]

[0183]

[0184] In Equation 4, the number of peeled grid patterns refers to the number of grid patterns separated from the light-transmitting substrate (110) and attached to the tape according to the peeling test of the coating film (100). In addition, the total number of grid patterns refers to the total number of grid patterns having a size of 1 mm x 1 mm formed on the coating layer (120) of the coating film (100) using a cutter knife during the peeling test. For example, the total number of grid patterns may be 100 (10 x 10) grid patterns having a size of 1 mm x 1 mm.

[0185] The details of the light resistance test and peeling test of the coating film (100) are the same as those described above, so they are omitted.

[0186] If the lattice peeling rate exceeds 5% after the light resistance test of the coating film (100), for example, if the coating film (100) is placed as a cover window of a display device and exposed to an external light source for a long period of time, separation of the coating layer (120) of the coating film (100) and the light-transmitting substrate (110) may occur due to an external force.

[0187] According to one embodiment of the present invention, the coating film (100) has a coating layer (120) that has excellent adhesion to the light-transmitting substrate (110), so that, for example, even if an external force is applied to the coating film (100), the coating layer (120) may not be easily separated from the light-transmitting substrate (110).

[0188] According to one embodiment of the present invention, the coating film (100) may have a crack point of less than 1.0 mm after a light resistance test based on a thickness of 55 μm.

[0189] The details of the light resistance test of the coating film (100) are the same as those described above, so they are omitted.

[0190] The crack point of the coating film (100) is calculated by the following equation 5.

[0191] [Formula 5]

[0192] Crack point = ((Out-folding crack point radius + In-folding crack point radius) / 2

[0193] FIG. 3a and FIG. 3b are schematic diagrams illustrating measurements of the out-folding crack point radius and the in-folding crack point radius of the coating film (100).

[0194] In the above formula 5, the Out-folding crack point radius is measured by cutting the coating film (100) into a size of 20 mm x 100 mm to manufacture a coating film sample, then mounting the manufactured coating film sample on a Radius Bending Tester so that the coating layer (120) formation surface is arranged in the outer direction of the bending direction as shown in FIG. 3a, and then repeatedly applying bending to the coating film sample so that the radius of curvature gradually decreases, and taking the radius of curvature (R) of the coating film sample measured at the moment when a crack occurs in the coating film sample as the Out-folding crack point radius.

[0195] In addition, in the above formula 5, the In-folding crack point radius is measured by cutting the coating film (100) into a size of 20 mm x 100 mm to manufacture a coating film sample, then mounting the manufactured coating film sample on a Radius Bending Tester so that the coating layer (120) forming surface is arranged in the inner direction of the bending direction as shown in FIG. 3b, and then repeatedly applying bending to the coating film sample so that the radius of curvature gradually decreases, and taking the radius of curvature (R) of the coating film sample measured at the moment when a crack occurs in the coating film sample as the In-folding crack point radius.

[0196] The average value of the Out-folding crack point radius and the In-folding crack point radius of the above-mentioned measured coating film (100) is calculated, and this is defined as the crack point value of the coating film (100).

[0197] According to one embodiment of the present invention, the coating film (100) may have an out-folding crack point radius of less than 1.0 mm and an in-folding crack point radius of less than 1.0 mm after a light resistance test, and as a result, may have a very small crack point of less than 1.0 mm. Accordingly, the coating film (100) may have excellent bendability and flexibility.

[0198] More specifically, the coating film (100) according to one embodiment of the present invention may have a crack point of less than 0.7 mm after a light resistance test.

[0199] If the crack point of the coating film (100) exceeds 1.0 mm, for example, when placed on a flexible display device and used for a long time, cracks or clouding may occur at the folded portion of the coating film, which may reduce the visibility of the flexible display device or cause it to malfunction.

[0200] A coating film (100) according to one embodiment of the present invention may have a crack point of less than 1.0 mm before a light resistance test.

[0201] The coating layer (120) of the coating film (100) according to one embodiment of the present invention may have excellent flexibility by being formed by curing a coating composition including an alicyclic epoxy compound having a structure such as Chemical Formula 1 as described above. Accordingly, the coating film (100) according to one embodiment of the present invention may have a crack point of less than 1.0 mm both before and after the light resistance test.

[0202] A coating film (100) according to one embodiment of the present invention includes a coating layer (120) formed by curing a coating composition including an alicyclic epoxy compound having a structure such as chemical formula 1 as described above, thereby having a number of scratches of 5 or less and a crack point of less than 1.0 mm after a light resistance test, thereby having excellent scratch resistance as well as excellent bending and flexibility.

[0203] A coating film (100) according to one embodiment of the present invention can have an elongation of 10% or more after a light resistance test based on a thickness of 55 ㎛.

[0204] The light resistance test of the coating film (100) is the same as described above and is therefore omitted.

[0205] After the light resistance test of the coating film (100), the elongation (%) can be obtained by cutting the coating film (100) on which the light resistance test was performed into a size of 100 X 5 mm to produce a coating film sample, and then elongating the sample at a stretching strength of 10 kN and a stretching speed of 20 mm / min using an Instron universal testing machine, and measuring the length of the elongated coating film sample at the moment when a crack occurs in the coating layer (120) or the sample breaks, and comparing the measured length with the length of the coating film sample before elongation.

[0206] According to one embodiment of the present invention, the alicyclic epoxy compound included in the coating composition may have, for example, no double bonds in its structure, and thus may exhibit little or no deformation due to external light irradiation after curing. Accordingly, the coating film (100) according to one embodiment of the present invention may have an elongation of 10% or more even after a light resistance test, and thus may maintain excellent flexibility even when exposed to a light source for a long period of time, for example.

[0207] If the elongation (%) of the coating film (100) is less than 10% after a light resistance test, it may be subject to breakage or deformation when folded or rolled while continuously exposed to a light source or when an external force is applied, and thus, it may be difficult to use it as a substrate material or cover window of a flexible display device, for example.

[0208] A coating film (100) according to one embodiment of the present invention may have an elongation of 10% or more before a light resistance test based on a thickness of 55 ㎛.

[0209] The details on measuring the elongation of the coating film (100) are the same as those described above, so they are omitted.

[0210] The coating layer (120) of the coating film (100) according to one embodiment of the present invention may have excellent flexibility by being formed by curing a coating composition including an alicyclic epoxy compound having a structure such as Chemical Formula 1. Accordingly, the coating film (100) according to one embodiment of the present invention may have an elongation of 10% or more both before and after the light resistance test.

[0211] A coating film (100) according to one embodiment of the present invention may have a pencil hardness of 4H or more based on a thickness of 55 μm.

[0212] According to one embodiment of the present invention, the coating layer (120) may have a pencil hardness of 4H or more based on a thickness of 5 μm. As a result, it can be said that the coating film (100) may have a pencil hardness of 4H or more.

[0213] The pencil hardness of the coating film (100) is measured at five points on the entire surface of the coating film sample on which the coating layer is formed, under the conditions of a speed of 180 mm / min and a load of 750 gf, based on the measurement conditions of ASTM D3363, after manufacturing a 190 mm X 250 mm coating film sample, using a pencil hardness measuring device from IMOTO. The average value is defined as the average value. The five measured points are as follows.

[0214] [Pencil hardness measurement points (5)]

[0215] Pencil hardness was measured at the following five points based on the center (exact center) of the coating film sample.

[0216] Point 1: From the top left toward the center, 20mm inside horizontally and 20mm inside vertically

[0217] Point 2: From the top right toward the center, 20mm inside horizontally and 20mm inside vertically

[0218] Point 3: Central

[0219] Point 4: From the lower left to the center, 20mm inside horizontally and 20mm inside vertically

[0220] Point 5: From the bottom right toward the center, 20mm inside horizontally and 20mm inside vertically

[0221] When the pencil hardness of the coating film (100) is 4H or higher, it has a uniform and excellent surface hardness, so that deformation due to external force can be suppressed. When the pencil hardness of the coating film (100) is less than 4H, there is a risk of deformation or breakage due to external force.

[0222]

[0223] *Figure 4 is a cross-sectional view of a portion of a display device (200) according to another embodiment of the present invention, and Figure 5 is an enlarged cross-sectional view of a “P” portion of Figure 4.

[0224] Referring to FIG. 4, a display device (200) according to another embodiment of the present invention includes a display panel (501) and a coating film (100) on the display panel (501). FIG. 4 discloses a display device (200) including the coating film (100) of FIG. 1.

[0225] Referring to FIGS. 4 and 5, the display panel (501) includes a substrate (510), a thin film transistor (TFT) on the substrate (510), and an organic light-emitting element (570) connected to the thin film transistor (TFT). The organic light-emitting element (570) includes a first electrode (571), an organic light-emitting layer (572) on the first electrode (571), and a second electrode (573) on the organic light-emitting layer (572). The display device (200) disclosed in FIGS. 4 and 5 is an organic light-emitting display device.

[0226] The substrate (510) may be made of plastic. Specifically, the substrate (510) may be made of a polyimide-based resin or a polyimide-based film.

[0227] Although not shown, a buffer layer may be disposed on the substrate (510).

[0228] A thin film transistor (TFT) is disposed on a substrate (510). The thin film transistor (TFT) includes a semiconductor layer (520), a gate electrode (530) that is insulated from the semiconductor layer (520) and overlaps at least a portion of the semiconductor layer (520), a source electrode (541) connected to the semiconductor layer (520), and a drain electrode (542) that is spaced apart from the source electrode (541) and connected to the semiconductor layer (520).

[0229] Referring to FIG. 5, a gate insulating film (535) is disposed between a gate electrode (530) and a semiconductor layer (520). An interlayer insulating film (551) may be disposed on the gate electrode (530), and a source electrode (541) and a drain electrode (542) may be disposed on the interlayer insulating film (551).

[0230] A planarization film (552) is placed on a thin film transistor (TFT) to planarize the upper portion of the thin film transistor (TFT).

[0231] A first electrode (571) of an organic light-emitting element (570) is placed on a planarization film (552). The first electrode (571) is connected to a drain electrode (542) of a thin film transistor (TFT) through a contact hole provided in the planarization film (552). The first electrode (571) may also be connected to a source electrode (541).

[0232] The bank layer (580) is arranged on the first electrode (571) and the planarization film (552) to define a pixel area or a light-emitting area. For example, the bank layer (580) may be arranged in a matrix structure in a boundary area between a plurality of pixels, thereby defining a pixel area by the bank layer (580).

[0233] The organic light-emitting layer (572) is disposed on the first electrode (571). The organic light-emitting layer (572) may also be disposed on the bank layer (580). The organic light-emitting layer (572) may include one light-emitting layer, or may include two or more light-emitting layers stacked one above the other. The organic light-emitting layer (572) may emit light having any one of red, green, and blue colors, and may also emit white light.

[0234] The second electrode (573) is placed on the organic light-emitting layer (572).

[0235] A first electrode (571), an organic light-emitting layer (572), and a second electrode (573) can be laminated to form an organic light-emitting element (570).

[0236] Although not shown, when the organic light-emitting layer (572) emits white light, each pixel may include a color filter for filtering the white light emitted from the organic light-emitting layer (572) by wavelength. The color filter is formed on the path of light.

[0237] A thin film encapsulation layer (590) may be disposed on the second electrode (573). The thin film encapsulation layer (590) may include at least one organic film and at least one inorganic film, and at least one organic film and at least one inorganic film may be disposed alternately.

[0238] A coating film (100) is placed on a display panel (501) having the laminated structure described above. The coating film (100) can be used as a cover window that covers and protects the light-emitting surface of the display panel (501).

[0239] Below, a method for manufacturing a coating film (100) according to one embodiment of the present invention is briefly described.

[0240] A method for manufacturing a coating film (100) according to one embodiment of the present invention may include a step of preparing a monomer and an initiator included in a coating composition, a step of dissolving the prepared monomer and initiator in a solvent to prepare a coating composition, and a step of forming a coating layer on a light-transmitting substrate using the prepared coating composition. Through the above steps, a coating film according to one embodiment of the present invention can be manufactured. Hereinafter, each step will be described in detail.

[0241] First, the monomer and initiator included in the coating composition are prepared.

[0242] The alicyclic epoxy compound described above may be used as a monomer included in the coating composition, and the alicyclic epoxy compound may include a compound represented by the structure of the chemical formula 1 described above.

[0243] More specifically, the alicyclic epoxy compound may include at least one of 3,3'-Bi-7-oxabicyclo[4.1.0]heptane, 3,3'-Bi-6-oxabicyclo[3.1.0]hexane, and 5-methyl-3,3'-Bi-7-oxabicyclo[4.1.0]heptane.

[0244] According to one embodiment of the present invention, the alicyclic epoxy compound, which is a monomer included in the coating composition, is in a liquid form at room temperature, but may contain impurities such as moisture when stored at low temperatures, for example, under refrigeration, and isomer precipitation may occur. If the alicyclic epoxy compound contains impurities and isomer precipitation, the physical properties and physical property uniformity of the cured product formed by the coating composition including the impurities may be affected. Therefore, the alicyclic epoxy compound may be used after aging is performed to remove impurities and mature the raw material.

[0245] If a coating composition is prepared using an alicyclic epoxy compound that has not been aged, sufficient and uniform mixing may not occur due to, for example, impurities. In addition, a coating layer formed by a coating composition containing an alicyclic epoxy compound that has not been aged may be unevenly coated on a light-transmitting substrate due to impurities, and the physical properties of the coating layer unevenly coated on the light-transmitting substrate may not be uniform over the entire area of ​​the coating layer.

[0246] According to one embodiment of the present invention, the aging of the alicyclic epoxy compound may be performed by, for example, placing about 1 kg of the alicyclic epoxy compound in an oven set to a temperature of 60 to 80°C and performing the aging for 30 to 120 minutes. More specifically, the aging of the alicyclic epoxy compound may be performed by placing about 1 kg of the alicyclic epoxy compound in an oven set to a temperature of 70°C and performing the aging for 60 minutes.

[0247] Next, the prepared monomer and initiator are dissolved in a solvent to prepare a coating composition.

[0248] As a solvent for preparing a coating composition, for example, at least one selected from the group consisting of ketones such as acetone, 2-butanone (methyl ethyl ketone), methyl butyl ketone, and cyclohexanone; cellosolves such as methyl cellosolve and butyl cellosolve; ethers such as ethyl ether and dioxane; alcohols such as isobutyl alcohol, isopropyl alcohol, butanol, and methanol; halogenated hydrocarbons such as dichloromethane, chloroform, and trichloroethylene; and hydrocarbons such as normal hexane, benzene, and toluene may be used. However, the solvent according to one embodiment of the present invention is not limited thereto, and other solvents may be used.

[0249] According to one embodiment of the present invention, a coating composition may be prepared by placing an aged alicyclic epoxy compound and an initiator in a 20 ml brown bottle, adding a solvent thereto, and mixing and stirring the mixture at room temperature at a speed of 50 to 200 rpm for 10 to 60 minutes using a magnetic stirrer. More specifically, a coating composition may be prepared by mixing and stirring the mixture at room temperature at a speed of 100 rpm for 30 minutes.

[0250] The above-mentioned manufactured coating composition may further include additives as needed. The additives may be additionally added to the manufactured coating composition after the monomer and initiator are mixed and stirred in a solvent to prepare the coating composition.

[0251] The above additive may be at least one selected from the group consisting of fillers, antioxidants, leveling agents, UV absorbers, UV shielding agents, and coating agents.

[0252] According to one embodiment of the present invention, the filler may include at least one of silica (SiO2), aluminum oxide (Al2O3), and zirconium oxide (ZrO2).

[0253] The particle size of the filler may be, for example, 5 to 20 nm, but is not limited thereto.

[0254] The content of the filler may be, for example, included in an amount of 40 parts by weight or less relative to 100 parts by weight of the alicyclic epoxy compound included in the coating composition.

[0255] When the content of the filler included in the coating composition exceeds 40 parts by weight per 100 parts by weight of the alicyclic epoxy compound, the light transmittance of the coating film (100) may decrease and haze may increase.

[0256] Next, a coating layer (120) is formed on a light-transmitting substrate (110) using the manufactured coating composition.

[0257] According to one embodiment of the present invention, a coating composition prepared on a light-transmitting substrate (110) is applied, dried before curing, and then photopolymerization and photocuring are performed through light irradiation to form a coating layer (120).

[0258] Drying before curing of the coating composition applied on the light-transmitting substrate (110) can be performed at a temperature of 70 to 80°C for 3 to 7 minutes. More specifically, drying before curing of the coating composition can be performed at a temperature of 80°C for 5 minutes.

[0259] When drying is performed at a temperature other than 70 to 80°C, for example, 100°C, prior to curing of the coating composition, or when drying is performed for a time other than 3 to 7 minutes, for example, 10 minutes, some of the monomers included in the coating composition may volatilize, thereby causing the coating layer (120) to be formed thin. In addition, as the coating layer (120) is formed thin, the surface hardness (pencil hardness) of the coating film may be reduced.

[0260] Light irradiation for photopolymerization and photocuring of the applied coating layer is UV-A 50 to 1,500 mW / cm2 and 0.5 to 5 J / cm 2 It can be performed under the condition of . More specifically, the light irradiation is UV-A 120 mW / cm 2 and 2 J / cm 2 It can be performed under the conditions of .

[0261] When the coating layer (120) on the light-transmitting substrate (110) is completely cured by performing the above steps, a coating film (100) according to one embodiment of the present invention can be manufactured.

[0262] Hereinafter, the present invention will be described in more detail through specific examples, comparative examples, and reference examples. These examples, comparative examples, and reference examples are intended solely to illustrate the present invention more specifically and are not intended to limit the present invention.

[0263] <Light-transmitting material>

[0264] Polyimide film (KOLON CPI) as a light-transmitting substrate used in the manufacture of coating films according to examples, comparative examples and reference examples ® , KOLON) was used.

[0265] <Coating Film>

[0266] Coating compositions prepared according to the compositions in Table 1 below were applied to a light-transmitting substrate and then cured to prepare coating films according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1.

[0267] <Example 1>

[0268] 1) 1 kg of 3,3'-Bi-7-oxabicyclo[4.1.0]heptane (CAS 37777-16-5) was aged in an oven at 70°C for 60 minutes.

[0269] After that, 5 g of aged 3,3'-Bi-7-oxabicyclo[4.1.0]heptane was placed in a 20 ml brown bottle, 5 g of 2-butanone and 0.05 g of Irgacure 250 were added to the brown bottle, and the mixture was mixed and stirred at room temperature at a speed of 100 rpm for 30 minutes using a magnetic stirrer to prepare a coating composition of Manufacturing Example 1 having a solid content of about 50%.

[0270] 2) The coating composition manufactured in the above 1) is applied to a 50㎛ thick polyimide film (KOLON CPI) which is a light-transmitting substrate. ® , KOLON) using Mayer Bar no. 8, dried at 80℃ for 5 minutes, and then exposed to UV-A 120mW / cm 2 and 2J / cm 2 By irradiating the light under the conditions of light, photopolymerization and photocuring were performed, and a coating layer with a thickness of 5 ㎛ was obtained on a light-transmitting substrate.

[0271] As a result, a coating film according to Example 1 was manufactured.

[0272] <Examples 2 to 6>

[0273] 1) The coating compositions of Manufacturing Examples 2 to 6 in Table 1 below were each manufactured according to the method described in 1) of Example 1.

[0274] 2) Using each of the coating compositions of Manufacturing Examples 2 to 6 manufactured in 1) above, a 50 ㎛ thick polyimide film (KOLON CPI) as a light-transmitting substrate was manufactured according to the method described in 2) of Example 1 above. ® , KOLON) and a 5㎛ thick coating layer was obtained on each.

[0275] As a result, coating films according to Examples 2 to 6 were each manufactured.

[0276] <Comparative Examples 1 to 3>

[0277] 1) The coating compositions of Comparative Manufacturing Examples 1 to 3 in Table 1 below were each manufactured according to the method described in 1) of Example 1.

[0278] 2) Using each of the coating compositions of Comparative Manufacturing Examples 1 to 3 manufactured in 1) above, a 50 μm thick polyimide film (KOLON CPI) as a light-transmitting substrate was manufactured according to the method described in 2) of Example 1 above. ® , KOLON) and a 5㎛ thick coating layer was obtained on each.

[0279] As a result, coating films according to Comparative Examples 1 to 3 were each manufactured.

[0280] Comparative Example 4

[0281] 1) The coating composition of Comparative Manufacturing Example 4 in Table 1 below was manufactured according to the method described in 1) of Example 1.

[0282] 2) The coating composition of Comparative Manufacturing Example 4 manufactured in 1) above was applied to a 50 ㎛ thick polyimide film (KOLON CPI) which is a light-transmitting substrate. ® , KOLON Co., Ltd.) was applied using Mayer Bar no. 8, dried at 80°C for 5 minutes, and then heat-polymerized and heat-cured in an oven at 200°C for 10 minutes to obtain a 5 μm thick coating layer on a light-transmitting substrate.

[0283] As a result, a coating film according to Comparative Example 4 was manufactured.

[0284] Comparative Example 5

[0285] 5 g of 3,3'-Bi-7-oxabicyclo[4.1.0]heptane, which had not been aged, was placed in a 20 ml brown bottle, and 5 g of 2-butanone and 0.05 g of Irgacure 250 were added to the brown bottle. The mixture was mixed and stirred at room temperature for 30 minutes at a speed of 100 rpm using a magnetic stirrer to produce a coating composition of Comparative Example 5 having a solid content of approximately 50%.

[0286] 2) The coating composition manufactured in the above 1) is applied to a 50㎛ thick polyimide film (KOLON CPI) which is a light-transmitting substrate. ®, KOLON) using Mayer Bar no. 8, dried at 80℃ for 5 minutes, and then exposed to UV-A 120mW / cm 2 and 2J / cm 2 By irradiating the light under the conditions of light, photopolymerization and photocuring were performed, and a coating layer with a thickness of 5 ㎛ was obtained on a light-transmitting substrate.

[0287] As a result, a coating film according to Comparative Example 5 was manufactured.

[0288] Comparative Example 6

[0289] 1) A coating composition was prepared according to the same composition and method as the coating composition of Manufacturing Example 1 prepared in Example 1 above.

[0290] 2) The coating composition of manufacturing example 1 manufactured in the above 1) is applied to a 50 ㎛ thick polyimide film (KOLON CPI) which is a light-transmitting substrate. ® , KOLON) using Mayer Bar no. 8, dried at 100℃ for 5 minutes, and then exposed to UV-A 120mW / cm 2 and 2J / cm 2 By irradiating the light under the conditions of light, photopolymerization and photocuring were performed, and a coating layer with a thickness of 3 ㎛ was obtained on a light-transmitting substrate.

[0291] As a result, a coating film according to Comparative Example 6 was manufactured.

[0292] Comparative Example 7

[0293] 1) A coating composition was prepared according to the same composition and method as the coating composition of Manufacturing Example 1 prepared in Example 1 above.

[0294] 2) The coating composition of manufacturing example 1 manufactured in the above 1) is applied to a 50 ㎛ thick polyimide film (KOLON CPI) which is a light-transmitting substrate. ® , KOLON) using Mayer Bar no. 8, dried at 80℃ for 10 minutes, and then exposed to UV-A 120mW / cm 2 and 2J / cm 2By irradiating the light under the conditions of light, photopolymerization and photocuring were performed, and a coating layer with a thickness of 3 ㎛ was obtained on a light-transmitting substrate.

[0295] As a result, a coating film according to Comparative Example 7 was manufactured.

[0296] <Reference Example 1>

[0297] 1) The coating composition of Reference Manufacturing Example 1 in Table 1 below was manufactured according to the method described in 1) of Example 1.

[0298] 2) Using the coating composition of Reference Manufacturing Example 1 manufactured in 1) above, a 50 ㎛ thick polyimide film (KOLON CPI) as a light-transmitting substrate was manufactured according to the method described in 2) of Example 1 above. ® , KOLON) to obtain a coating layer with a thickness of 5㎛.

[0299] As a result, a coating film according to Reference Example 1 was manufactured.

[0300] The types and contents (unit: g) of each component included in the coating compositions used in Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1 can be summarized as shown in Table 1.

[0301] Classification Resin Composition Filler Solvent Initiator A1 A2 A3 A4 A5 A6 B1 B2 B3 CD 1 D2 Manufacturing Example 15-------- 50.05 - Manufacturing Example 25----- 0.5 - 5.5 0.05 - Manufacturing Example 35------ 0.5 - 5.5 0.05 - Manufacturing Example 45------- 0.5 5.5 0.05 - Manufacturing Example 5 - 5------- 50.05 - Manufacturing Example 6 - 5------ 50.05 - Comparative Manufacturing Example 1 - 5----- 50.05 - Comparative Manufacturing Example 2 - 5 - 0.5 - 5.5 0.05 - Comparative Manufacturing Example 3 - 5---- 50.05 - Comparative Manufacturing Example 4 - 5 - 5 - 0.05 Reference Manufacturing Example 15-----2.5--7.50.05-

[0302] Each coating composition was prepared with a solid content of 50%.

[0303] The initiator was used in an amount of 1 part by weight per 100 parts by weight of the resin composition.

[0304] The specific components used in Table 1 above are as follows.

[0305] Resin composition

[0306] A1: 3,3'-Bi-7-oxabicyclo[4.1.0]heptane (Cas no. 3777-16-5)

[0307] A2: 3,3'-Bi-6-oxabicyclo[3.1.0]hexane

[0308] A3: 5-methyl-3,3'-Bi-7-oxabicyclo[4.1.0]heptane

[0309] A4: 2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane (KBM-303)

[0310] A5: 3,4-Epoxycyclohexylmethyl 3,4 epoxycyclohexane-carboxylate (Cas no. 2386-87-0)

[0311] A6: Dipentaerythritol Hexaacrylate (DPHA)

[0312] Filler

[0313] B1: Silica (SiO2 in PGME), particle size 10 nm

[0314] B2: Aluminum oxide (Al2O3, in PGME), particle size 15 nm

[0315] B3: Zirconium oxide (ZrO2, in PGME), particle size 10 nm

[0316] Solvent

[0317] C: 2-butanone (methyl ethyl ketone)

[0318] Initiation

[0319] D1: (4-Isobutylphenyl)(p-tolyl)iodonium hexafluorophosphate (Irgacure 250)

[0320] D2: 2,2'-Azobis(2-methylpropionitrile) (AIBN)

[0321] Lightfastness Test

[0322] In the present invention, the light resistance test of the coating film was performed using Ci3000+ equipment from ATLAS, under the conditions of a temperature of 30°C and a humidity of 55RH%, maintaining the temperature of the black panel at 55°C, and irradiating the coating film with a Xenon Lamp light source of 420 nm wavelength at an intensity of 1.1 W / ㎡ for 150 hours.

[0323] <Measurement of physical properties>

[0324] The physical properties of the coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1 were measured according to the following method.

[0325] (1) Scratch resistance of coating film

[0326] 1) Each of the coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1 was cut into a size of 100 mm x 50 mm to manufacture a coating film sample, and the coating film sample was fixed to a flat surface using an adhesive tape (3M) with the coating layer facing upward, and then the surface of the coating layer of the coating film sample was moved back and forth 10 times at a load of 0.5 kgf and a speed of 45 RPM using a stainless steel (SUS) jig of 20 mm x 20 mm wrapped with #0000 (LIBERON) nonwoven fabric, and the number of scratches observed with the naked eye was measured by length.

[0327] A: Number of scratches less than 1 mm in length

[0328] B: Number of scratches 1 mm to 5 mm long

[0329] C: Number of scratches longer than 5 mm

[0330] 2) If the number of scratches by length measured in 1) above satisfies all of the following equations 1 to 3, an OK decision was made, and if even one of them was not satisfied, an NG decision was made.

[0331] [Formula 1]

[0332] A < 5

[0333] [Formula 2]

[0334] B < 3

[0335] [Formula 3]

[0336] C < 1

[0337] (2) Coating adhesion before and after light resistance test of the coating film

[0338] 1) Coating adhesion after light resistance test

[0339] a) A light resistance test was performed on the coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1, respectively.

[0340] b) Afterwards, a peeling test was performed under the following conditions to measure the number of grid patterns that were separated from the light-transmitting substrate of the coating film and attached to the tape.

[0341] [Peeling Test]

[0342] After forming 100 grid patterns (10 x 10) of 1 mm x 1 mm size on the coating layer of the coating film using a cutter knife, 3M Scotch Box Tape (48 mm, transparent) (#3650) was attached to the surface of the coating layer, and when the tape was removed within 0.1 second, the number of grid patterns separated from the light-transmitting substrate of the coating film and attached to the tape was measured.

[0343] c) The number of grid patterns separated from the light-transmitting substrate of the coating film and attached to the tape, as measured by the above peeling test, was evaluated according to the following classification criteria, and this was used as the coating adhesion after the light resistance test.

[0344] [Coating Adhesion Classification Criteria]

[0345] 5B: No grid pattern separated from the light-transmitting substrate.

[0346] 4B: 1 to 5 grid patterns separated from the light-transmitting substrate

[0347] 3B: 6 to 15 grid patterns separated from the light-transmitting substrate.

[0348] 2B: 16 to 35 grid patterns separated from the light-transmitting substrate.

[0349] 1B: 36 to 65 grid patterns separated from a light-transmitting substrate

[0350] 0B: 66 or more grid patterns separated from the light-transmitting substrate

[0351] 2) Coating adhesion before light resistance test

[0352] a) For the coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1, a light resistance test was not performed, but a peeling test was performed as in b) of 1) above, and the number of grid patterns separated from the light-transmitting substrate of the coating film and attached to the tape was measured.

[0353] b) The number of grid patterns separated from the light-transmitting substrate of the coating film and attached to the tape, as measured by the peeling test, was evaluated according to the classification criteria in c) of the coating adhesion after the light fastness test in 1) above, and this was taken as the coating adhesion before the light fastness test.

[0354] (3) Grid peeling rate after light resistance test

[0355] 1) A light resistance test was performed on the coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1.

[0356] 2) After that, a peeling test was performed under the same conditions and method as the peeling test performed on the coating adhesion before and after the above (2) light resistance test, and the number of grid patterns separated from the light-transmitting substrate and attached to the tape was measured, and then the grid peeling rate after the light resistance test of the coating film was obtained by calculating according to the following equation 4.

[0357] [Formula 4]

[0358]

[0359] (4) Elongation before and after light resistance test of coating film

[0360] 1) Elongation after light resistance test

[0361] a) A light resistance test was performed on the coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1, and then each coating film sample was manufactured by cutting it into a size of 100 X 5 mm.

[0362] b) Using each manufactured coating film sample, the length of the stretched coating film sample at the moment when a crack occurs in the coating layer or the sample breaks was measured while stretching the sample at a stretching strength of 10 kN and a stretching speed of 20 mm / min using an Instron universal tensile tester (MODEL 5967) according to the ASTM D885 method, and the elongation after the light resistance test of each coating film was obtained by comparing the measured length with the length of the coating film sample before stretching.

[0363] 2) Elongation before light resistance test

[0364] a) For the coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1, a light resistance test was not performed, and each coating film sample was manufactured by cutting it into a size of 100 X 5 mm.

[0365] b) For each of the manufactured coating film samples, the elongation was measured according to the conditions and method measured in the elongation after the light resistance test in 1) above, and the elongation before the light resistance test of each coating film was obtained.

[0366] (5) Pencil hardness of coating film

[0367] 1) The coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1 were cut to a size of 190 mm x 250 mm to manufacture coating film samples.

[0368] 2) After that, for each manufactured coating film sample, a pencil hardness tester from IMOTO was used and, according to ASTM D3363, the pencil hardness was measured at five points based on the direction of the surface in which the coating layer of the coating film sample was formed under the conditions of a speed of 180 mm / min and a load of 750 gf, and the average value was taken as the pencil hardness of the coating film.

[0369] [Pencil hardness measurement points (5)]

[0370] Pencil hardness was measured at the following five points based on the center (exact center) of the coating film sample.

[0371] 1. 20mm inside horizontally and 20mm inside vertically from the upper left toward the center

[0372] 2. 20mm inside horizontally and 20mm inside vertically from the top right toward the center

[0373] 3. Center

[0374] 4. 20mm inside horizontally and 20mm inside vertically from the bottom left toward the center

[0375] 5. 20mm inside horizontally and 20mm inside vertically from the bottom right toward the center

[0376] (6) Crack points before and after light resistance test of the coating film

[0377] 1) Crack point before light resistance test

[0378] The coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1 were not subjected to a light resistance test, but were cut into 20 mm x 100 mm sizes to manufacture coating film samples.

[0379] b) Using the manufactured coating film sample, the out-folding crack point radius and the in-folding crack point radius were measured as follows.

[0380] The out-folding crack point radius of the coating film was obtained by mounting the coating film sample on a Radius Bending Tester so that the coating layer formation surface is positioned outward in the bending direction, as shown in Fig. 3a, and then repeatedly bending the coating film sample so that the radius of curvature gradually decreases, and measuring the radius of curvature (R) of the coating film sample at the moment when a crack occurs in the coating film sample.

[0381] The in-folding crack point radius of the coating film was obtained by mounting the coating film sample on a Radius Bending Tester so that the coating layer formation surface was positioned inward in the bending direction, as shown in Fig. 3b, and then measuring the radius of curvature (R) of the coating film sample using the same method as the out-folding crack point radius measurement method.

[0382] c) Using the measured Out-folding crack point radius and In-folding crack point radius values, the crack point of the coating film was calculated according to Equation 5 below, and this was used as the crack point before the light resistance test.

[0383] [Formula 5]

[0384] Crack point = (Out-folding crack point radius + In-folding crack point radius) / 2

[0385] 2) Crack point after light resistance test

[0386] a) After performing a light resistance test on the coating films manufactured according to Examples 1 to 6, Comparative Examples 1 to 7, and Reference Example 1, a coating film sample was manufactured by cutting it into a size of 20 mm x 100 mm.

[0387] b) After that, using the manufactured coating film sample, the Out-folding crack point radius and the In-folding crack point radius were measured according to the same method as b) of the crack point before the light resistance test in 1) above, and then the crack point was calculated according to Equation 5 in c) of the crack point before the light resistance test in 1) above using the measured Out-folding crack point radius and In-folding crack point radius values, and this was used as the crack point after the light resistance test of the coating film.

[0388] <Results of physical property measurement>

[0389] The results of the above physical property measurements are disclosed in Tables 2 and 3 below.

[0390] Classification Pencil hardness (H) Scratch resistance Characteristic Peeling rate (%) Point 1 Point 2 Point 3 Point 4 Point 5 Average ABC evaluation result Example 1 444444210O.K0 Example 2 444444300O.K2 Example 3 444444110O.K1 Example 444444220O.K2 Example 5 444444120O.K0 Example 6 444444310O.K0 Comparative example 1444444220O.K100 Comparative example 2444444120O.K100 Comparative example 333333855N.G30 Comparative example 4222222574N.G100 Comparative example 5243433.2512N.G0 Comparative example 6333333510N.G1 Comparative example 7333333520N.G0 Reference example 1444444310O.K4

[0391] <Pencil hardness measurement point>

[0392] Pencil hardness was measured at the following five points based on the center (exact center) of the coating film sample.

[0393] Point 1. 20mm inside horizontally and 20mm inside vertically from the upper left corner toward the center.

[0394] Point 2. 20mm inside horizontally and 20mm vertically from the top right toward the center.

[0395] Branch 3. Central

[0396] Point 4. 20mm inside horizontally and 20mm inside vertically from the lower left toward the center.

[0397] Point 5. 20mm inside horizontally and 20mm vertically from the bottom right toward the center.

[0398] Scratch resistance

[0399] A: Number of scratches less than 1mm

[0400] B: Number of scratches between 1 mm and 5 mm

[0401] C: Number of scratches exceeding 5 mm

[0402] Classification Elongation (%) Crack Point Coating Adhesion Lightfastness Test Before Lightfastness Test After Lightfastness Test Before Lightfastness Test After Lightfastness Test Before Lightfastness Test After Example 11817<1.0<1.05B5B Example 21513<1.0<1.05B4B Example 31513<1.0<1.05B4B Example 41513<1.0<1.05B4B Example 51716<1.0<1.05B5B Example 62018<1.0<1.05B5B Comparative Example 1532.03.05B0B Comparative Example 2333.04.05B0B Comparative Example 385<1.0<1.05B2B Comparative Example 4422.53.55B0B Comparative Example 51717<1.0<1.05B5BComparative example 61816<1.0<1.05B5BComparative example 71616<1.0<1.05B5BReference example 1653.03.05B4B

[0403] According to Tables 2 and 3, the coating films according to the embodiments of the present invention have excellent surface properties, including excellent pencil hardness and excellent scratch resistance, and excellent flexibility, with an elongation after a light fastness test and a crack point of less than 1.0 mm. In addition, when comparing the coating adhesion before and after the light fastness test, it can be confirmed that there is no decrease in the coating adhesion after the light fastness test, indicating excellent light fastness against an external light source.

[0404] In contrast, the coating film according to the comparative example was found to lack scratch resistance and flexibility. Furthermore, after a light resistance test, the coating adhesion was significantly reduced, confirming poor light resistance to external light sources.

[0405] Meanwhile, the coating film according to the reference example has excellent light resistance properties with almost no decrease in coating adhesion after excellent scratch resistance and light resistance tests, but it can be confirmed that it lacks flexibility due to containing an excessive amount of filler.

[0406] [Explanation of symbols]

[0407] 100: Coating film

[0408] 110: Base film

[0409] 120: Coating layer

[0410] 200: Display device

[0411] 501: Display panel

[0412] 570: Organic light-emitting device

[0413] TFT: Thin Film Transistor

Claims

a light-transmitting substrate; and A coating layer on the above light-transmitting substrate; The above-mentioned light-transmitting substrate comprises at least one of an imide repeating unit and an amide repeating unit, The above coating layer is formed by a coating composition, The above coating composition, Alicyclic epoxy compounds; Initiator; and menstruum; Including, The above-mentioned alicyclic epoxy compound is a coating film comprising a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, L and L' are the same or different and are a C4 to C10 alicyclic alkylene group, R1, R2, R3, R4, R 5, R 6, R7 and R8 is each independently selected from the group consisting of hydrogen, a C1 to C4 alkyl group, a C1 to C4 alkoxy group, and combinations thereof. In the first paragraph, The above-mentioned alicyclic epoxy compound comprises at least one of a compound represented by the following chemical formula 2 and a compound represented by the following chemical formula 3. Coating film: [Chemical Formula 2] [Chemical Formula 3] In the above chemical formula 2, R1, R2, R3, R4, R 5, R 6, R7 and R8 is each independently selected from the group consisting of hydrogen, a C1 to C4 alkyl group, a C1 to C4 alkoxy group, and combinations thereof, In the above chemical formula 3, R1, R2, R3, R4, R 5, R 6, R7 and R8 is each independently selected from the group consisting of hydrogen, a C1 to C4 alkyl group, a C1 to C4 alkoxy group, and combinations thereof. In the first paragraph, A coating film, wherein the above-mentioned cycloaliphatic epoxy compound comprises at least one of 3,3'-Bi-7-oxabicyclo[4.1.0]heptane, 3,3'-Bi-6-oxabicyclo[3.1.0]hexane and 5-methyl-3,3'-Bi-7-oxabicyclo[4.1.0]heptane. In the first paragraph, A coating film, wherein the coating composition further comprises a filler. In paragraph 4, A coating film wherein the filler comprises at least one of silica (SiO2), aluminum oxide (Al2O3), and zirconium oxide (ZrO2). In the first paragraph, The above light-transmitting substrate is, Imide repeating units formed by diamine compounds and dianhydride compounds; and An amide repeating unit formed by a diamine compound and a dicarbonyl compound; Coating film. In the first paragraph, The above coating layer is a coating film that satisfies all of the following equations 1 to 3: [Formula 1] A < 5 [Formula 2] B < 3 [Formula 3] C < 1 Here, A in the above formula 1 means the number of scratches with a length of less than 1 mm, B in the above formula 2 means the number of scratches with a length of 1 mm to 5 mm, C in the above formula 3 means the number of scratches longer than 5 mm, The above number of scratches means the number of scratches by length observed with the naked eye after cutting the coating film to a size of 100 mm x 50 mm to prepare a coating film sample, fixing the coating film sample to a flat surface using adhesive tape so that the coating layer faces upward, and then moving the surface of the coating layer of the coating film sample back and forth 10 times at a load of 0.5 kgf and a speed of 45 RPM with a stainless steel (SUS) jig of size 20 mm x 20 mm wrapped with #0000 (LIBERON) nonwoven fabric. In the first paragraph, Coated film having a coating adhesion of 4B or 5B after light fastness test: Here, the light resistance test is conducted under the conditions of a temperature of 30°C and a humidity of 55RH%, maintaining the temperature of the Black Panel at 55°C, and irradiating the coating film with a Xenon Lamp light source of 420 nm wavelength at an intensity of 1.1 W / ㎡ for 150 hours. The above coating adhesion is evaluated by the peeling test results of the above coating film, The above peeling test is performed by forming 100 grid patterns (10 x 10) of 1 mm x 1 mm size on the coating layer of the coating film using a cutter knife, attaching 3M Scotch Box Tape (48 mm, transparent) (#3650) to the surface of the coating layer, and then removing the tape within 0.1 second. The number of grid patterns among the 100 grid patterns that are separated from the light-transmitting substrate and attached to the tape is measured. The above 4B coating adhesion means that the number of the grid patterns separated from the light-transmitting substrate and attached to the tape is 1 to 5 as a result of the peeling test of the coating film, The coating adhesion of the above 5B means that, as a result of the peeling test of the above coating film, there is no grid pattern attached to the tape separated from the light-transmitting substrate. In the first paragraph, Coated films with a grid peeling rate of 5% or less after light resistance testing: Here, the lattice peeling ratio is calculated according to the following equation 4, [Formula 4] The number of peeled grid patterns in the above formula 4 is measured according to the peeling test of the above coating film, The above peeling test is performed by forming 100 grid patterns (10 x 10) of 1 mm x 1 mm size on the coating layer of the coating film using a cutter knife, attaching 3M Scotch Box Tape (48 mm, transparent) (#3650) to the surface of the coating layer, and then removing the tape within 0.1 second. The number of grid patterns among the 100 grid patterns that are separated from the light-transmitting substrate and attached to the tape is measured. In the first paragraph, Coating film having a crack point of less than 1.0 mm after light resistance test based on a thickness of 55㎛: Here, the crack point is calculated by the following equation 5, [Formula 5] Crack point = (Out-folding crack point radius + In-folding crack point radius) / 2 The Out-folding crack point radius of the above formula 5 means the radius of curvature (R) of the coating film sample measured at the moment when a crack occurs in the coating film sample when the coating film sample with a size of 20 mm x 100 mm is mounted on a Radius Bending Tester so that the coating layer formation surface is positioned in the outer direction of the bending direction and the coating film sample is repeatedly bent so that the radius of curvature gradually decreases. The in-folding crack point radius of the above formula 5 means the radius of curvature (R) of the coating film sample measured in the same manner as the out-folding crack point radius measurement method after mounting the coating film sample of size 20 mm x 100 mm on a Radius Bending Tester so that the coating layer formation surface is positioned in the inner direction of the bending direction. In the first paragraph, A coating film having an elongation of 10% or more after a light resistance test based on a thickness of 55㎛. In the first paragraph, A coating film having a pencil hardness of 4H or higher based on a thickness of 55㎛. display panel; and A coating film according to any one of claims 1 to 12, disposed on the display panel; A display device including:

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