Coating film comprising coating layer, and display device comprising same

Abstract

One 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 includes an imide repeating unit and / or an amide repeating unit, and the coating layer is formed of a coating composition, the coating composition comprising an alicyclic epoxy compound, an initiator, a solvent and a pigment, wherein the alicyclic epoxy compound comprises a compound represented by chemical formula 1.

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 lightweight, processability, and flexibility. Conventional light-transmitting films are known to have some inferior mechanical and optical properties compared to glass. Accordingly, research is being conducted to improve the mechanical and optical properties of light-transmitting films for their application in the display field.

[0003] One method for improving the mechanical and 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 is also called a coated film.

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

[0005] One embodiment of the present invention is to provide a coating film having excellent light resistance and low yellowness even after a light resistance test.

[0006] One embodiment of the present invention is to provide a coating film applicable to a flexible display, having excellent film breakage elongation and coating breakage elongation.

[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, a solvent, and a pigment, 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] 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.

[0021] According to one embodiment of the present invention, the initiator may be an imidazole-based initiator.

[0022] According to one embodiment of the present invention, the pigment may include at least one of Pigment Blue 15:1, 15:3, 15:4, 15:6, 16, 22, 28, 36, 60, 64, and Pigment Violet 15, 19, 23, 29, 32, 37.

[0023] 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.

[0024] According to one embodiment of the present invention, the coating film may have a yellowness change (△YI) of 3.4 or less based on a thickness of 50 μm.

[0025] Here, the change in yellowness is calculated according to the following equation 1,

[0026] [Formula 1]

[0027] Change in yellowness (△YI) = | Yellowness after lightfastness test (YI2) - Yellowness before lightfastness test (YI1) |

[0028] The above 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 60 hours.

[0029] According to one embodiment of the present invention, the coating film may have a yellowness index (YI2) of 3.7 or less after a light fastness test.

[0030] 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 60 hours.

[0031] A coating film according to one embodiment of the present invention can have a coating printability of 5B.

[0032] Here, the coating printability is evaluated by the BM peeling test results of the coating film,

[0033] The above BM peeling test refers to a cross-cut test conducted based on ASTM D3359 after printing a black matrix with a thickness of 10㎛ on the coating film.

[0034] According to one embodiment of the present invention, the coating film can have a film elongation at break of 20% or more and a coating elongation at break of 20% or more based on a thickness of 50 μm.

[0035] According to one embodiment of the present invention, the coating layer may have a thickness of 50 to 500 nm.

[0036] Another embodiment of the present invention provides a display device including a display panel and the above-described coating film disposed on the display panel.

[0037] 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.

[0038] 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.

[0039] A coating film according to one embodiment of the present invention has excellent light resistance and can maintain excellent yellowness even after a light resistance test.

[0040] 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 light resistance, coating printability, and flexibility.

[0041] FIG. 1 is a schematic cross-sectional view of a coating film according to one embodiment of the present invention.

[0042] FIG. 2 is a cross-sectional view of a portion of a display device according to another embodiment of the present invention.

[0043] Figure 3 is an enlarged cross-sectional view of portion “P” of Figure 2.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Figure 1 is a schematic cross-sectional view of a coating film (100) according to one embodiment of the present invention.

[0052] 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).

[0053] 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 and a polyamide-imide film.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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).

[0061] 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.

[0062] 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), on the lower surface, or on both the upper and lower surfaces. The coating layer (120) may also be referred to as a primer layer.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] [Chemical Formula 1]

[0069]

[0070] In the above chemical formula 1, L and L' are the same or different and may be a C4 to C10 alicyclic alkylene group.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] On the other hand, the coating film (100) according to one embodiment of the present invention may use an epoxy-based coating composition to form a coating layer.

[0080] 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.

[0081] 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.

[0082] [Chemical Formula 2]

[0083]

[0084] [Chemical Formula 3]

[0085]

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] [Chemical Formula 4]

[0091]

[0092] [Chemical Formula 5]

[0093]

[0094] [Chemical Formula 6]

[0095]

[0096] According to one embodiment of the present invention, the coating composition may include an initiator.

[0097] An initiator may be used to cure the coating composition. Either a thermal polymerization initiator or a photopolymerization initiator may be used as the initiator for curing the coating composition. If necessary, both a thermal polymerization initiator and a photopolymerization initiator may be used simultaneously.

[0098] 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 an imidazole-based initiator, an amine-based initiator, phthalic anhydride, and 2,2'-Azobis(2-methylpropionitrile) (AIBN).

[0099] More specifically, according to one embodiment of the present invention, an imidazole-based initiator, for example, can be used as the thermal polymerization initiator.

[0100] As the imidazole initiator, for example, at least one of 2-methylimidazole, 2-ethyl-4-methylimidazole, ethylimidazole, isopropylimidazole, 2,4-dimethylimidazole, phenylimidazole, undecylimidazole, heptadecylimidazole and 2-phenyl-4-methylimidazole can be used.

[0101] According to one embodiment of the present invention, when an imidazole-based initiator is used as a thermal polymerization initiator, the coating composition may not contain fluorine.

[0102] 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 300°C for 3 to 30 minutes. More specifically, thermal polymerization and thermal curing may be performed by heat irradiation at 180 to 250°C for 5 to 20 minutes.

[0103] Additionally, to improve the degree of polymerization, heat polymerization and heat curing may be performed by performing a pre-heat treatment at 80 to 140°C for 3 to 7 minutes, followed by heat irradiation at 80 to 300°C for 3 to 30 minutes. More specifically, the pre-heat treatment may be performed at 100 to 120°C for 3 to 5 minutes.

[0104] 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.

[0105] 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.

[0106] 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 2 Photopolymerization 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.

[0107] 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.

[0108] 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 3 to 20 parts by weight relative to 100 parts by weight of the alicyclic epoxy compound. More specifically, the content of the initiator may be included in an amount of about 5 to 10 parts by weight relative to 100 parts by weight of the alicyclic epoxy compound.

[0109] According to one embodiment of the present invention, the coating composition may include a solvent.

[0110] 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.

[0111] As a solvent, at least one selected from the group consisting of, but not limited to, ketones such as acetone, 2-butanone (methyl ethyl ketone), 4-methylpentan-2-one (methyl isobutyl 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.

[0112] 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 2,700 to 6,600 parts by weight per 100 parts by weight of solid content.

[0113] According to one embodiment of the present invention, the coating composition may include a pigment.

[0114] More specifically, the coating composition may include a pigment having a visible light absorption wavelength of 540 to 700 nm. In this case, the yellow color of the coating film (100) can be controlled by effectively absorbing wavelengths of 580 to 630 nm, which are in the yellow region of the visible light spectrum.

[0115] The pigment may include, for example, at least one of a blue pigment and a purple pigment.

[0116] As a blue pigment, for example, at least one of PIGMENT BLUE 15:1, 15:3, 15:4, 15:6, 16, 22, 28, 36, 60, 64 can be used.

[0117] As a purple pigment, for example, at least one of PIGMENT VIOLET 15, 19, 23, 29, 32, 37 can be used.

[0118] More specifically, for absorbing long wavelengths of 500 nm or more, for example, a purple pigment such as CI PIGMENT VIOLET 23 can be used. However, the absorption rate of CI PIGMENT VIOLET 23 decreases at long wavelengths of 640 nm or more. Therefore, for absorbing long wavelengths of 640 nm or more, for example, a blue pigment such as CI PIGMENT BLUE 15:6 can be used together with CI PIGMENT VIOLET 23.

[0119] According to one embodiment of the present invention, the pigment included in the coating composition may be a purple pigment, CI PIGMENT VIOLET 23, and a blue pigment, CI PIGMENT BLUE 15:6, mixed in a weight ratio of 1:5 to 5:1.

[0120] CI PIGMENT VIOLET 23, a purple pigment, absorbs well in the wavelength range of 500 to 640 nm, but its absorption rate decreases for short wavelengths below 500 nm and long wavelengths above 640 nm. In contrast, CI PIGMENT BLUE 15:6, a blue pigment, absorbs well in long wavelengths above 560 nm, but its absorption rate decreases for short wavelengths below 560 nm.

[0121] In addition, the purple pigment CI PIGMENT VIOLET 23 has very fine particles and a rod- or plate-shaped crystal structure, and thus tends to have relatively low dispersibility in a solvent compared to the blue pigment CI PIGMENT BLUE 15:6. In contrast, the blue pigment CI PIGMENT BLUE 15:6 has larger particles and a β-type crystal structure with improved dispersibility in a solvent compared to the purple pigment CI PIGMENT VIOLET 23, and thus has relatively stable dispersibility in a solvent compared to the purple pigment CI PIGMENT VIOLET 23.

[0122] Therefore, when the weight ratio of the purple pigment CI PIGMENT VIOLET 23 and the blue pigment CI PIGMENT BLUE 15:6 is less than 1:5, the absorption rate at a wavelength of 500 nm to 560 nm decreases, making it difficult to obtain a sufficient yellowness reduction effect. On the other hand, when the weight ratio of the purple pigment CI PIGMENT VIOLET 23 and the blue pigment CI PIGMENT BLUE 15:6 exceeds 5:1, compared to CI PIGMENT BLUE 15:6, which has relatively stable dispersibility in a solvent, the content of CI PIGMENT VIOLET 23, which is relatively difficult to disperse in a solvent, increases, making it difficult to disperse the pigment in the coating composition.

[0123] According to one embodiment of the present invention, for the visibility of the coating film (100), the content of the pigment in the coating composition can be appropriately adjusted so that the yellowness of the coating film (100) is in the range of about -0.3 to 0.3.

[0124] According to one embodiment of the present invention, the content of the pigment in the coating composition may be 1 to 5 parts by weight relative to 100 parts by weight of the total solid content of the coating composition.

[0125] If the pigment content is less than 1 part by weight relative to 100 parts by weight of the total solid content of the coating composition, it may be difficult to adjust the yellowness of the coating film (100) to the target level. If the pigment content is more than 5 parts by weight relative to 100 parts by weight of the total solid content of the coating composition, the haze of the coating film may increase due to the inclusion of an excessive amount of pigment.

[0126] According to one embodiment of the present invention, the coating composition can be used to form a coating layer (120) having excellent light resistance and flexibility by including an alicyclic epoxy compound, an initiator, a solvent, and a pigment.

[0127] 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.

[0128] According to one embodiment of the present invention, the coating composition may further comprise a filler.

[0129] 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).

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] According to one embodiment of the present invention, the coating film (100) may have a yellowness change (△YI) of 3.4 or less based on a thickness of 50 μm.

[0135] The above yellowness change (△YI) is calculated according to the following equation 1.

[0136] [Formula 1]

[0137] Change in yellowness (△YI) = | Yellowness after lightfastness test (YI2) - Yellowness before lightfastness test (YI1) |

[0138] In Equation 1, the light resistance test is performed under the conditions of a temperature of 30°C and a humidity of 55RH%, the temperature of the Black Panel is maintained at 55°C, and a Xenon Lamp light source with a wavelength of 420 nm is irradiated on the coating film at an intensity of 1.1 W / ㎡ for 60 hours.

[0139] For calculating the yellowness change (△YI), the yellowness (YI1, YI2) before / after the lightfastness test is measured by cutting the coating film (100) into 50 mm x 50 mm to prepare a coating film sample, and then using a colorimeter, for example, a colorimeter (model name: CM-3600A) from KONICA MINOLTA, measuring the yellowness 5 times with a D65 light source, a viewing angle of 2°, and transmission mode according to ASTM D1925, and calculating the average value of the yellowness measured 5 times, thereby measuring the yellowness (YI1) before the lightfastness test. The yellowness (YI2) after the lightfastness test can be measured by the same method as the method for measuring the yellowness (YI1) before the lightfastness test after performing the lightfastness test.

[0140] When the yellowness change (△YI) of the coating film (100) is 3.4 or less, the UV light resistance of the coating film (100) is excellent, and thus it is suitable for use as a cover window of a display device.

[0141] Since the polymer resin included in the light-transmitting substrate (110) of the coating film (100) has a large number of aromatic rings, it may take on a yellowish tint when exposed to light of ultraviolet (UV) wavelengths. Accordingly, as the usage time of the display device on which the coating film (100) is disposed increases, the yellowness of the coating film (100) may increase.

[0142] Additionally, even if the resin constituting the coating layer (120) contains an aromatic ring, it may take on a yellowish tint when exposed to light of ultraviolet (UV) wavelengths. Accordingly, as the usage time of the display device on which the coating film (100) is disposed increases, the yellowness of the coating film (100) may increase.

[0143] On the other hand, the coating film (100) according to one embodiment of the present invention may have a small increase in yellowness even when exposed to light of an ultraviolet (UV) wavelength, since the resin constituting the coating layer (120) does not include an aromatic ring and does not have a double bond in the structure. Therefore, the coating film (100) according to one embodiment of the present invention has excellent UV light resistance as the coating layer (120) is disposed on a light-transmitting substrate (110), so that even when exposed to light of an ultraviolet (UV) wavelength, the yellowness difference (△YI) may be 3.4 or less.

[0144] If the yellowness change (△YI) of the coating film (100) exceeds 3.4, aging due to light sources such as ultraviolet (UV) rays may easily occur, resulting in reduced visibility.

[0145] According to one embodiment of the present invention, the coating film (100) may have a yellowness index (YI2) of 3.7 or less after a light resistance test.

[0146] Since the light resistance test conditions have been described in the yellowness change above, duplicate details are omitted.

[0147] If the yellowness index (YI2) of the coating film (100) is 3.7 or less after a light resistance test, the coating film (100) is suitable for use as a cover window of a display device because there is almost no decrease in visibility even when exposed to a light source for a long period of time.

[0148] If the yellowness index (YI2) of the coating film (100) exceeds 3.7 after a light resistance test, the coating film (100) may be difficult to use as a cover window of a display device due to a decrease in visibility when exposed to a light source for a long period of time.

[0149] A coating film (100) according to one embodiment of the present invention can have a coating printability of 5B.

[0150] Here, the coating printability is evaluated by the BM peeling test results of the coating film (100), and the BM peeling test means a cross-cut test performed based on ASTM D3359 after printing a black matrix 1 degree with a thickness of 10㎛ on the coating film (100).

[0151] 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 can maintain excellent coating printability of 5B even if aging occurs.

[0152] If the coating film (100) does not satisfy the coating printability of 5B, for example, when the coating film (100) is laminated to a display device or an additional coating process is performed on the coating film (100), peeling of the coating layer (120) may occur.

[0153] A coating film (100) according to one embodiment of the present invention may have a film break elongation of 20% or more and a coating break elongation of 20% or more based on a thickness of 50 ㎛.

[0154] The coating break elongation of the coating film (100) is defined as a value obtained by, for example, cutting a coating film (100) having a thickness of 50 ㎛ into a size of 100 X 5 mm to produce a coating film sample, and then stretching 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 at the point where a crack occurs in the coating layer (120) or the coating layer (120) is peeled off from the light-transmitting substrate (110), and comparing this length with the length of the coating film sample before stretching.

[0155] The film breaking elongation of the coating film (100) is defined as a value obtained by measuring the length at the point where both the light-transmitting substrate (110) and the coating layer (120) are broken while stretching the coating film sample under the same conditions as the coating breaking elongation, for example, and comparing this length with the length of the coating sample before stretching.

[0156] However, in the above stretching process, if the light-transmitting substrate (110) breaks before the coating layer (120), the film breakage elongation is defined as being calculated based on the length at that point.

[0157] Based on a thickness of 50 ㎛, if the coating film (100) has a film break elongation of less than 20% or a coating break elongation of less than 20%, the coating film (100) may be deformed or broken by an external force, or the coating layer (120) may be peeled off, making it difficult to use it as a cover window of a display device.

[0158] According to one embodiment of the present invention, the coating layer (120) included in the coating film (100) may have a thickness of 50 to 500 nm.

[0159] If the thickness of the coating layer (120) is less than 50 nm, the coating printability may be reduced. If the thickness of the coating layer (120) is more than 500 nm, the flexibility of the coating layer (120) may be reduced due to the excessive thickness formed, and thus the coating breakage elongation may be reduced.

[0160] FIG. 2 is a cross-sectional view of a portion of a display device (200) according to another embodiment of the present invention, and FIG. 3 is an enlarged cross-sectional view of a portion “P” of FIG. 2.

[0161] Referring to FIG. 2, 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. 2 discloses a display device (200) including the coating film (100) of FIG. 1.

[0162] Referring to FIGS. 2 and 3, 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. 2 and 3 is an organic light-emitting display device.

[0163] 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.

[0164] Although not shown, a buffer layer may be disposed on the substrate (510).

[0165] 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).

[0166] Referring to FIG. 3, 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).

[0167] A planarization film (552) is placed on a thin film transistor (TFT) to planarize the upper portion of the thin film transistor (TFT).

[0168] 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).

[0169] 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).

[0170] 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.

[0171] The second electrode (573) is placed on the organic light-emitting layer (572).

[0172] 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).

[0173] 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.

[0174] 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.

[0175] 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).

[0176] Below, a method for manufacturing a coating film (100) according to one embodiment of the present invention is briefly described.

[0177] 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.

[0178] First, the monomer and initiator included in the coating composition are prepared.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] Next, the prepared monomer and initiator are dissolved in a solvent to prepare a coating composition.

[0185] 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, 4-methylpentan-2-one (methyl isobutyl ketone), 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.

[0186] According to one embodiment of the present invention, a cyclic epoxy compound that has undergone aging and an initiator are placed in a 1 L brown volumetric flask, a solvent is added thereto, and a magnetic stirrer is used to mix and stir at room temperature at a speed of 50 to 200 rpm for 10 to 60 minutes to prepare a first mixed solution. More specifically, the first mixed solution can be prepared by mixing and stirring at room temperature at a speed of 100 rpm for 30 minutes.

[0187] Next, a pigment may be added to the prepared first mixed solution, and a magnetic stirrer may be used to mix and stir at room temperature for 30 to 100 minutes at a speed of 50 to 200 rpm, thereby producing a second mixed solution. More specifically, the second mixed solution may be prepared by mixing and stirring at room temperature for 60 minutes at a speed of 100 rpm. Here, the prepared second mixed solution may be considered a coating composition.

[0188] 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.

[0189] 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.

[0190] 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).

[0191] The particle size of the filler may be, for example, 5 to 20 nm, but is not limited thereto.

[0192] 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.

[0193] 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.

[0194] Next, a coating layer (120) is formed on a light-transmitting substrate (110) using the manufactured coating composition.

[0195] 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 heat polymerization and heat curing are performed through heat treatment to form a coating layer (120).

[0196] Drying before curing of the coating composition applied on the light-transmitting substrate (110) can be performed at a temperature of 80 to 140°C for 3 to 7 minutes. More specifically, drying before curing of the coating composition can be performed at a temperature of 120°C for 5 minutes.

[0197] When drying is performed at a temperature other than 80 to 140°C, for example, 180°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, and as a result, the thickness of the coating layer (120) may be formed thinly.

[0198] Heat treatment for thermal polymerization and thermal curing of the applied coating layer can be performed at a temperature of 180 to 250°C for 5 to 20 minutes. More specifically, the heat treatment can be performed at a temperature of 230°C for 10 minutes.

[0199] 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.

[0200] 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.

[0201] <Light-transmitting material>

[0202] 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 Co., Ltd.) was used.

[0203] <Coating Film>

[0204] 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 4 and Comparative Examples 1 to 7.

[0205] <Example 1>

[0206] 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.

[0207] After that, 30 g of aged 3,3'-Bi-7-oxabicyclo[4.1.0]heptane (CAS 37777-16-5), 967 g of 4-methylpentan-2-one, and 3 g of 2-Ethyl-4-methylimidazole were placed in a 1 L brown volumetric flask, and mixed and stirred at room temperature at a speed of 100 rpm for 30 minutes using a magnetic stirrer. Then, 0.24 g of Pigment Violet 23 and 0.16 g of Pigment Blue 15:6 were added thereto, and mixed and stirred at room temperature at a speed of 100 rpm for 60 minutes to prepare a coating composition of Preparation Example 1 having a solid content of about 3%.

[0208] 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 Co., Ltd.) was applied using Mayer Bar no. 8, dried and pre-heat treated at 120°C for 5 minutes, and then heat polymerization and heat curing were performed through heat irradiation in an oven at 230°C for 10 minutes to obtain a coating layer with a thickness of 120 nm on a light-transmitting substrate.

[0209] As a result, a coating film according to Example 1 was manufactured.

[0210] <Examples 2 and 3>

[0211] 1) The coating compositions of Manufacturing Examples 2 and 3 in Table 1 below were each manufactured according to the method described in 1) of Example 1.

[0212] 2) Using each of the coating compositions of Manufacturing Examples 2 and 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 120 nm thick coating layer was obtained on each.

[0213] As a result, coating films according to Examples 2 and 3 were manufactured, respectively.

[0214] <Example 4>

[0215] 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.

[0216] After that, 60 g of aged 3,3'-Bi-7-oxabicyclo[4.1.0]heptane (CAS 37777-16-5), 967 g of 4-methylpentan-2-one, and 6 g of 2-Ethyl-4-methylimidazole were placed in a 1 L brown volumetric flask, and mixed and stirred at room temperature at a speed of 100 rpm for 30 minutes using a magnetic stirrer. Then, 0.06 g of Pigment Violet 23 and 0.04 g of Pigment Blue 15:6 were added thereto, and mixed and stirred at room temperature at a speed of 100 rpm for 60 minutes to prepare a coating composition of Preparation Example 4 having a solid content of about 6%.

[0217] 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 Co., Ltd.) was applied using Mayer Bar no. 16, dried at 120°C for 5 minutes, and then heat polymerization and heat curing were performed through heat irradiation in an oven at 230°C for 10 minutes to obtain a coating layer with a thickness of 500 nm on a light-transmitting substrate.

[0218] As a result, a coating film according to Example 4 was manufactured.

[0219] <Comparative Example 1>

[0220] 1) The coating composition of Comparative Manufacturing Example 1 in Table 1 below was manufactured according to the method described in 1) of Example 1.

[0221] 2) Using the coating composition of Comparative 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 110 nm thick coating layer.

[0222] As a result, a coating film according to Comparative Example 1 was manufactured.

[0223] <Comparative Example 2>

[0224] 1) The coating composition of Comparative Manufacturing Example 2 in Table 1 below was manufactured according to the method described in 1) of Example 1.

[0225] 2) Using the coating composition of Comparative Manufacturing Example 2 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 115 nm thick coating layer.

[0226] As a result, a coating film according to Comparative Example 2 was manufactured.

[0227] <Comparative Example 3>

[0228] 1) The coating composition of Comparative Manufacturing Example 3 in Table 1 below was manufactured according to the method described in 1) of Example 1.

[0229] 2) Using the coating composition of Comparative Manufacturing Example 3 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 113 nm thick coating layer.

[0230] As a result, a coating film according to Comparative Example 3 was manufactured.

[0231] Comparative Example 4

[0232] 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.

[0233] After that, 120 g of aged 3,3'-Bi-7-oxabicyclo[4.1.0]heptane (CAS 37777-16-5), 967 g of 4-methylpentan-2-one, and 12 g of 2-Ethyl-4-methylimidazole were placed in a 1 L brown volumetric flask, and mixed and stirred at room temperature at a speed of 100 rpm for 30 minutes using a magnetic stirrer. Then, 0.03 g of Pigment Violet 23 and 0.02 g of Pigment Blue 15:6 were added thereto, and mixed and stirred at room temperature at a speed of 100 rpm for 60 minutes to prepare a coating composition of Comparative Preparation Example 4 having a solid content of about 12%.

[0234] 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 Co., Ltd.) was applied using Mayer Bar no. 8, dried at 120°C for 5 minutes, and then heat polymerization and heat curing were performed through heat irradiation in an oven at 230°C for 10 minutes to obtain a coating layer with a thickness of 1,000 nm on a light-transmitting substrate.

[0235] As a result, a coating film according to Comparative Example 4 was manufactured.

[0236] Comparative Example 5

[0237] In Example 1, a coating composition excluding the pigment was prepared, and then a 50 μm thick polyimide film (KOLON CPI) as a light-transmitting substrate was applied. ® , KOLON Co., Ltd.) was applied using Mayer Bar no. 8, dried at 120°C for 5 minutes, and then heat polymerization and heat curing were performed through heat irradiation in an oven at 230°C for 10 minutes to obtain a coating layer with a thickness of 118 nm on a light-transmitting substrate.

[0238] As a result, a coating film according to Comparative Example 5 was manufactured.

[0239] Comparative Example 6

[0240] After preparing a coating composition having the same composition as Example 1, a 50 μm thick polyimide film (KOLON CPI) as a light-transmitting substrate was applied. ® , KOLON Co., Ltd.) was applied using Mayer Bar no. 8, and thermal polymerization and thermal curing were performed through heat irradiation in an oven at 230°C for 10 minutes without drying or prior heat treatment, thereby obtaining a coating layer with a thickness of 120 nm on a light-transmitting substrate.

[0241] As a result, a coating film according to Comparative Example 6 was manufactured.

[0242] <Comparative Example 7>

[0243] A coating composition was prepared in the same manner as in Example 1, except that aging of 3,3'-Bi-7-oxabicyclo[4.1.0]heptane (CAS 37777-16-5) was not performed, and then a 50 μm thick polyimide film (KOLON CPI) as a light-transmitting substrate was prepared. ® , KOLON Co., Ltd.) was applied using Mayer Bar no. 8, dried and pre-heat treated at 120°C for 5 minutes, and then heat polymerization and heat curing were performed through heat irradiation in an oven at 230°C for 10 minutes to obtain a coating layer with a thickness of 120 nm on a light-transmitting substrate.

[0244] As a result, a coating film according to Comparative Example 7 was manufactured.

[0245] The types and contents (unit: g) of each component included in the coating compositions used in Examples 1 to 4 and Comparative Examples 1 to 7 can be summarized as in Table 1.

[0246] Classification Resin Composition Pigment Solvent Initiator A1 A2 A3 A4 A5 A6 B1 B2 CD Manufacturing Example 1 30-----0.24 0.169673 Manufacturing Example 2 - 30----0.24 0.169673 Manufacturing Example 3 - 30 - 0.24 0.169673 Manufacturing Example 460-----0.06 0.049676 Comparative Manufacturing Example 1 - 30 - 0.24 0.169673 Comparative Manufacturing Example 2 - 30 - 0.24 0.169673 Comparative Manufacturing Example 3 - 30 0.24 0.169673 Comparative Manufacturing Example 4120-----0.03 0.0296712

[0247] The initiator was used in an amount of 10 parts by weight per 100 parts by weight of the resin composition.

[0248] The specific components used in Table 1 above are as follows.

[0249] Resin composition

[0250] A1: 3,3'-Bi-7-oxabicyclo[4.1.0]heptane (Cas no. 3777-16-5)

[0251] A2: 3,3'-Bi-6-oxabicyclo[3.1.0]hexane

[0252] A3: 5-methyl-3,3'-Bi-7-oxabicyclo[4.1.0]heptane

[0253] A4: 2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane (KBM-303)

[0254] A5: Dipentaerythritol Hexaacrylate (DPHA)

[0255] A6: 5,5-Dimethyl-3,7-dioxa-1,9(2)-bis(oxirana)-4,6(2,4)-dibenzenanonaphane

[0256] Pigment

[0257] B1: Pigment Violet 23

[0258] B2: Pigment Blue 15:6

[0259] Solvent

[0260] C: 4-methylpentan-2-one (methyl isobutyl ketone)

[0261] Initiation

[0262] D: 2-Ethyl-4-methylimidazole

[0263] <Measurement of physical properties>

[0264] The physical properties of the coating films manufactured according to Examples 1 to 4 and Comparative Examples 1 to 7 were measured according to the following methods.

[0265] (1) Yellowness before and after light resistance test

[0266] For the coating films manufactured according to Examples 1 to 4 and Comparative Examples 1 to 7, the yellowness before and after the light resistance test was measured as follows.

[0267] [Yellowness measurement before lightfastness test]

[0268] The coating films manufactured according to Examples 1 to 4 and Comparative Examples 1 to 7 were cut into 50 mm x 50 mm to manufacture coating film samples, and then the yellowness was measured five times in accordance with ASTM D1925 using a colorimeter (model name: CM-3600A) manufactured by KONICA MINOLTA with a D65 light source, a viewing angle of 2°, and transmission mode, and the average value of the five yellowness measurements was calculated to measure the yellowness (YI1) before the light fastness test.

[0269] [Lightfastness Test]

[0270] Using ATLAS's Ci3000+ equipment, the temperature of the black panel was maintained at 55℃ under the conditions of temperature 30℃ and humidity 55RH%, and a Xenon Lamp light source with a wavelength of 420nm was irradiated on the coating film at an intensity of 1.1W / ㎡ for 60 hours.

[0271] [Yellowness measurement after lightfastness test]

[0272] The coating films manufactured according to Examples 1 to 4 and Comparative Examples 1 to 7 were subjected to a light fastness test according to the light fastness test conditions, and then the yellowness (YI2) after the light fastness test was measured using the same method as the yellowness measurement method before the light fastness test.

[0273] (2) Coating printability

[0274] After printing Black Matrix (HS Chemical's Solvent ink (TOL)) at a thickness of 10㎛ on the coating films manufactured according to Examples 1 to 4 and Comparative Examples 1 to 7, a BM peeling test of the coating film (100) was performed according to the Cross-cut Test performed based on ASTM D3359 to evaluate the coating printability.

[0275] (3) Film breakage elongation and coating breakage elongation

[0276] 1) Coating films manufactured according to Examples 1 to 4 and Comparative Examples 1 to 7 were cut to a size of 100 X 5 mm to produce coating film samples.

[0277] 2) Each of the coating film samples manufactured in the above 1) was placed on an Instron universal testing machine, and stretched at an elongation strength of 10 kN and an elongation speed of 20 mm / min using an Instron universal tensile testing machine (MODEL 5967) according to the ASTM D885 method.

[0278] 3) Coating fracture elongation: The length at the point where a crack occurs in the coating layer (120) of the coating film sample stretched as in 2) above or the coating layer (120) is peeled off from the light-transmitting substrate (110) is measured, and the value obtained by comparing this with the length of the coating film sample before stretching is defined as the coating fracture elongation of the film.

[0279] 4) Film break elongation: The length at which both the light-transmitting substrate (110) and the coating layer (120) of the coated film sample stretched as in 2) above are broken is measured, and this is defined as the value obtained by comparing it with the length of the coating sample before stretching.

[0280] However, in the above stretching process, if the light-transmitting substrate (110) breaks before the coating layer (120), the film breakage elongation is calculated based on the length at that point.

[0281] <Results of physical property measurement>

[0282] The results of the above physical property measurements are disclosed in Table 2 below.

[0283] Yellowness Coating Printability Film Breaking Elongation Coating Breaking Elongation Before Lightfastness Test (YI1) After Lightfastness Test (YI2) Yellowness Change (△YI) Example 103.43.45B27%27% Example 20.13.53.45B27%27% Example 3-0.13.23.35B27%27% Example 40.33.73.45B21%21% Comparative Example 10.13.63.53B25%16% Comparative Example 20.24.54.35B17%17% Comparative Example 30.24.64.45B29%29% Comparative Example 40.13.73.65B11%11% Comparative Example 52.76.13.45B28%28%Comparative example 60.13.53.44B28%12%Comparative example 70.03.53.54B26%26%

[0284] According to Table 2, the coating films according to the embodiments of the present invention exhibit excellent coating printability, excellent film peel strength, and coating peel strength, making them suitable for use as cover windows for display devices. Furthermore, when comparing the yellowness before and after the lightfastness test, the increase in yellowness after the lightfastness test was low, confirming excellent lightfastness against external light sources.

[0285] On the other hand, the coating films according to Comparative Examples 1 and 4 showed low film peel strength and coating peel strength, indicating insufficient flexibility. The coating films according to Comparative Examples 2 and 3 showed a high increase in yellowness after a light resistance test, indicating insufficient light resistance to external light sources.

[0286] The coating film according to Comparative Example 5 has a high yellowness before and after the light resistance evaluation, so it appears yellow, and thus it may be difficult to use it as a cover window of a display device.

[0287] It can be confirmed that the coating film according to Comparative Example 6 has insufficient coating fracture elongation due to insufficient curing of the epoxy resin.

[0288] It can be confirmed that the coating film according to Comparative Example 7 has poor coating printability and coating breakage elongation because a uniform coating layer is not formed.

[0289] [Explanation of symbols]

[0290] 100: Coating film

[0291] 110: Base film

[0292] 120: Coating layer

[0293] 200: Display device

[0294] 501: Display panel

[0295] 570: Organic light-emitting device

[0296] TFT: Thin Film Transistor

Claims

1. 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 comprises an alicyclic epoxy compound, an initiator, a solvent and a pigment, 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.

2. In paragraph 1, The above 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.

3. In paragraph 1, 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.

4. In paragraph 1, A coating film, wherein the above initiator comprises at least one initiator selected from the group consisting of imidazole, amine, phthalic anhydride, and 2,2'-Azobis(2-methylpropionitrile) (AIBN).

5. In paragraph 1, A coating film, wherein the pigment comprises at least one of Pigment Blue 15:1, 15:3, 15:4, 15:6, 16, 22, 28, 36, 60, 64, and Pigment Violet 15, 19, 23, 29, 32, 37.

6. In paragraph 1, 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.

7. In paragraph 1, Coating film with a yellowness change (△YI) of 3.4 or less based on a thickness of 50㎛: Here, the change in yellowness is calculated according to the following equation 1, [Formula 1] Change in yellowness (△YI) = | Yellowness after lightfastness test (YI2) - Yellowness before lightfastness test (YI1) | The above 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 60 hours.

8. In paragraph 1, A coating film having a yellowness index (YI2) of 3.7 or less after a light fastness test.

9. In paragraph 1, Coated film with 5B coating printability: Here, the coating printability is evaluated by the BM peeling test results of the coating film. The above BM peeling test refers to a cross-cut test conducted based on ASTM D3359 after printing a black matrix with a thickness of 10㎛ on the coating film.

10. In paragraph 1, A coated film having a film elongation at break of 20% or more and a coating elongation at break of 20% or more based on a thickness of 50 ㎛.

11. In paragraph 1, A coating film, wherein the coating layer has a thickness of 50 to 500 nm.

12. Display panel; and A display device comprising a coating film according to any one of claims 1 to 11, disposed on the display panel.

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