Optical film and display device comprising same

Abstract

One embodiment of the present invention provides an optical film and a display device comprising same, the optical film comprising a light-transmitting substrate and a coating layer, and having a friction coefficient index value of 0.1 or less, a transmittance of 89.5% or more on the basis of a thickness of 50 μm, and a yellowness index (Y.I.) of 1.0 or less on the basis of a thickness of 50 μm, wherein the friction coefficient index is represented by relation 1. [Relation 1] Friction coefficient index = coefficient of static friction - coefficient of kinetic friction

Description

Optical film and display device including the same

[0001] The present invention relates to an optical film and a display device including the same, and more particularly, to an optical film having excellent optical properties and improved driving properties.

[0002] Recently, with the trend toward thinner, lighter, and more flexible display devices, the use of optical films instead of glass as cover windows is being considered. For optical films to be used as cover windows for display devices, they must possess both excellent optical and mechanical properties. For example, optical films must possess excellent strength, hardness, wear resistance, and flexibility.

[0003] Furthermore, when forming a coating layer to improve optical properties, the coefficient of friction on the surface of the optical film can change, potentially causing problems with roll-to-roll performance. Therefore, research is ongoing into optical films that offer both superior optical properties and improved performance.

[0004] One embodiment of the present invention is to provide an optical film having excellent optical properties and improved driving properties by including a novel coating layer.

[0005] Another embodiment of the present invention is to provide a display device including an optical film having excellent optical properties and improved driving performance.

[0006] One embodiment of the present invention relates to an optical film comprising a light-transmitting substrate; and a coating layer, wherein the optical film has a friction coefficient index value of 0.1 or less, a transmittance of 89.5% or more based on a thickness of 50 μm, and a yellowness index (YI) of 1.0 or less based on a thickness of 50 μm, wherein the friction coefficient index is expressed by the following Equation 1.

[0007] [Formula 1] Friction coefficient index = static friction coefficient - kinetic friction coefficient

[0008] The above coating layer includes a polymer resin layer including a polymer resin and an ultraviolet absorber and a pigment, and the polymer resin may include at least one selected from an acrylic resin, a urethane resin, and a siloxane resin.

[0009] The pigment may have a diameter of 100 to 200 nm.

[0010] The above coating layer may contain 6 to 14 parts by weight of pigment relative to 100 parts by weight of the polymer resin.

[0011] The polymer resin layer may have a thickness of 73 to 95% of the diameter of the pigment.

[0012] The above pigment can protrude from the surface of the polymer resin layer.

[0013] Another embodiment of the present invention provides a display device including a display panel and the optical film disposed on the display panel.

[0014] According to one embodiment of the present invention, an optical film having excellent optical properties and improved driving properties is provided by including a novel coating layer.

[0015] FIG. 1 is a cross-sectional view of an optical film according to one embodiment of the present invention.

[0016] FIG. 2 is a cross-sectional view of a portion of a display device according to one embodiment of the present invention.

[0017] Figure 3 is an enlarged cross-sectional view of portion “P” of Figure 2.

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. However, the embodiments described below are presented for illustrative purposes only to facilitate a clear understanding of the present invention and do not limit the scope of the present invention.

[0019] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are merely illustrative, and the present invention is not limited to the details depicted in the drawings. Throughout the specification, identical components may be designated by identical reference numerals. In describing the present invention, detailed descriptions of related known technologies will be omitted if they are deemed to unnecessarily obscure the gist of the present invention.

[0020] 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.

[0021] 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.

[0022] Spatially relative terms such as "below," "beneath," "lower," "above," and "upper" can be used to easily describe the relationship of one element or component to another, as illustrated in the drawings. Spatially relative terms should be understood to include different orientations of the elements during use or operation in addition to the orientations depicted in the drawings. For example, if an element depicted in the drawings were flipped over, an element described as "below" or "beneath" another element could instead be positioned "above" the other element. Thus, the exemplary term "below" can encompass both the above and below directions. Similarly, the exemplary term "above" or "above" can encompass both the above and below directions.

[0023] 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.

[0024] 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.

[0025] 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 not only the first, second, or third items, but also any combination of items that can be represented by two or more of the first, second, and third items.

[0026] 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.

[0027]

[0028] *Figure 1 is a cross-sectional view of an optical film (100) according to one embodiment of the present invention. Figure 2 is a cross-sectional view of a portion of a display device (200) according to one embodiment of the present invention. Figure 3 is an enlarged cross-sectional view of a portion “P” of Figure 2.

[0029] One embodiment of the present invention provides an optical film (100). According to one embodiment of the present invention, the optical film (100) includes a light-transmitting substrate (110) and a coating layer (120). As illustrated in FIG. 1, the optical film (100) according to one embodiment of the present invention may have the coating layer (120) formed on the upper surface of the light-transmitting substrate (110). However, one embodiment of the present invention is not limited thereto, and the coating layer (120) may be formed on the lower surface of the light-transmitting substrate (110).

[0030] The light-transmitting substrate (110) according to one embodiment of the present invention may be any material that allows light to pass through. For example, the light-transmitting substrate (110) may include glass or a polymer resin. In particular, polymer resins have excellent bending properties and impact resistance, making them suitable for use as cover windows for flexible display devices.

[0031] The polymer resin can be included in various shapes and forms, such as a solid powder form in a film, a form dissolved in a solution, a matrix form solidified after being dissolved in a solution, etc., and any resin containing the same repeating unit as the present invention can be considered to be the same as the polymer resin of the present invention regardless of shape and form. Generally, the polymer resin in the film can exist in the form of a matrix solidified by applying a polymer resin solution and then drying it.

[0032] The polymer resin according to one embodiment of the present invention may be any light-transmitting resin. For example, it may include at least one selected from among cycloolefin derivatives, cellulose polymers, ethylene vinyl acetate copolymers, polyester polymers, polystyrene polymers, polyamide polymers, polyamide imide polymers, polyether imide polymers, polyacrylic polymers, polyimide polymers, polyether sulfone polymers, polysulfone polymers, polyethylene polymers, polypropylene polymers, polymethyl pentene polymers, polyvinyl chloride polymers, polyvinylidene chloride polymers, polyvinyl alcohol polymers, polyvinyl acetal polymers, polyether ketone polymers, polyether ether ketone polymers, polymethyl methacrylate polymers, polyethylene terephthalate polymers, polybutylene terephthalate polymers, polyethylene naphthalate polymers, polycarbonate polymers, polyurethane polymers, and epoxy polymers. Preferably, the polymer resin according to one embodiment of the present invention may include at least one of a polyimide-based polymer, a polyamide-based polymer, and a polyamide-imide-based polymer.

[0033] According to one embodiment of the present invention, the light-transmitting substrate (110) may be any one of a polyimide-based substrate, a polyamide-based substrate, and a polyamide-imide-based substrate. However, one embodiment of the present invention is not limited thereto, and any substrate having light transmission properties may be the light-transmitting substrate (110) according to one embodiment of the present invention.

[0034] According to one embodiment of the present invention, the optical film (100) has a friction coefficient index value expressed by the following equation 1 of 0.1 or less.

[0035] [Formula 1]

[0036] Friction coefficient index = static friction coefficient - kinetic friction coefficient

[0037] In the above equation 1, the static friction coefficient and kinetic friction coefficient were measured using a friction coefficient measuring device (Ametek Lloyd instrument LF Plus) according to the ASTM D1894 standard.

[0038] Specifically, an optical film sample cut to 100 mm x 63.5 mm was cut to 63.5 mm 2 A metal block (200 g) was attached to the bottom, and a 20 x 10 cm film was placed on the bottom. The metal block was pulled at a speed of 180 mm / min to move 130 mm, and then the metal block was stopped. The static friction coefficient and kinetic friction coefficient were measured from the data from the time the metal block was pulled to the time the metal block was stopped.

[0039] When the static friction coefficient of the optical film (100) according to one embodiment of the present invention is 0.5 or less and the friction coefficient index value is 0.1 or less, it means that the process runnability and rollability are excellent.

[0040] On the other hand, if the friction coefficient index value of the optical film (100) exceeds 0.1, the running and slipping properties of the optical film are poor, and scratches may occur during winding.

[0041] According to one embodiment of the present invention, the transmittance is 89.5% or more based on a thickness of 50 μm.

[0042] At this time, the above transmittance is the average value obtained by cutting the manufactured optical film into 50 mm x 50 mm and measuring the transmittance 5 times according to ASTM-D1003 using a haze meter (model name: HM-150) from MURAKAMI.

[0043] According to one embodiment of the present invention, the yellowness index (YI) is 1.0 or less based on a thickness of 50 μm.

[0044] At this time, the yellowness (YI) is the average value obtained by cutting the manufactured optical film into 50 mm x 50 mm and measuring it 5 times using a colorimeter (model name: CM-3600A) from KONICA MINOLTA with a D65 light source, a viewing angle of 2°, and transmission mode.

[0045] According to one embodiment of the present invention, the haze is 1.0% or less based on a thickness of 50 μm.

[0046] At this time, the haze is the average value obtained by cutting the manufactured optical film into 50 mm x 50 mm and measuring the haze 5 times according to ASTM-D1003 using a haze meter (model name: HM-150) from MURAKAMI.

[0047] According to one embodiment of the present invention, the surface roughness (Ra) is 30 to 80 nm based on a thickness of 50 μm.

[0048] At this time, the surface roughness (Ra) was measured using a 10x magnification lens with a non-contact 3D micro-shape measuring device, NV-2000 from Nanosystem Co., Ltd., for an area of ​​1 mm x 1 mm.

[0049] According to one embodiment of the present invention, when the surface roughness (Ra) of the optical film (100) is 30 to 80 nm, it means that the process runnability and windability are excellent.

[0050] On the other hand, if the surface roughness (Ra) value of the optical film (100) is outside the range of 30 to 80 nm, the running and slipping properties of the optical film are poor, and scratches may occur during winding.

[0051] According to one embodiment of the present invention, the coating layer (120) includes a polymer resin layer (121) and a pigment (122).

[0052] Specifically, the polymer resin layer (121) includes a polymer resin and an ultraviolet absorber.

[0053] According to one embodiment of the present invention, the polymer resin may include at least one selected from an acrylic resin, a urethane resin, and a siloxane resin. The polymer resin may include any one selected from an acrylic resin, a urethane resin, and a siloxane resin depending on the type of the light-transmitting substrate (110) and the physical properties of the optical film (100).

[0054] According to one embodiment of the present invention, when the polymer resin layer (121) includes an ultraviolet absorber, the ultraviolet absorber can absorb ultraviolet rays incident on the optical film (100), thereby suppressing peeling of the light-transmitting substrate (110) and the coating layer (120) and reducing the increase in yellowness index (YI).

[0055] According to one embodiment of the present invention, the type of ultraviolet absorber is not limited, and any ultraviolet absorber that suppresses peeling of the light-transmitting substrate (110) and the coating layer (120) and reduces the increase in yellowness (YI) may be used.

[0056] According to one embodiment of the present invention, the polymer resin layer (121) may include 0.01 to 0.5 parts by weight of an ultraviolet absorber per 100 parts by weight of the polymer resin, but may not be limited thereto.

[0057] According to one embodiment of the present invention, an initiator may be additionally included for polymerization of the polymer resin. For example, a photopolymerization initiator such as an onium salt or an organometallic salt and a thermal polymerization initiator such as an amine or imidazole may be used, but the present invention is not limited thereto. The amount of the initiator to be added is not particularly limited, but may be added in an amount of about 0.5 to 3.0 parts by weight relative to 100 parts by weight of the polymer resin, but the present invention is not limited thereto.

[0058] In general, when the coating layer (120) includes a polymer resin layer (121) containing an ultraviolet absorber, the peeling of the light-transmitting substrate (110) and the coating layer (120) is suppressed and the increase in yellowness (YI) is suppressed, but there is a problem that the initial yellowness (YI) of the optical film (100) increases.

[0059] That is, in order to reduce the initial yellowness (YI), a pigment may be included, but when a general pigment is included, there is an advantage of reducing the initial yellowness (YI) of the optical film (100), but there is a problem that the transmittance is reduced and the driving property is reduced at the same time.

[0060] Therefore, in order to suppress the increase in initial yellowness (YI), secure transmittance, and improve driving performance, according to one embodiment of the present invention, the diameter and content of the pigment (122) and the thickness of the polymer resin layer (121) can be adjusted.

[0061] According to one embodiment of the present invention, the pigment (122) may have a diameter of 100 to 200 μm. Specifically, when the diameter of the pigment (122) is 100 to 200 μm, an increase in the initial yellowness index (YI) of the optical film (100) is suppressed, transmittance is secured, and driving properties are improved.

[0062] On the other hand, if the diameter of the pigment (122) exceeds 200 ㎛, a problem of increasing haze of the optical film (100) may occur.

[0063] Additionally, if the diameter of the pigment (122) is less than 100 ㎛, problems with driving performance may occur.

[0064] According to one embodiment of the present invention, the coating layer (120) may include 6 to 14 parts by weight of a pigment (122) relative to 100 parts by weight of the polymer resin. Specifically, when the pigment (122) is included in an amount of 6 to 14 parts by weight relative to 100 parts by weight of the polymer resin, an increase in the initial yellowness (YI) of the optical film (100) is suppressed, transmittance is secured, and driving properties are improved.

[0065] On the other hand, if the content of the pigment (122) exceeds 14 parts by weight based on 100 parts by weight of the polymer resin, a problem of increasing haze of the optical film (100) may occur.

[0066] In addition, if the content of pigment (122) is less than 6 parts by weight relative to 100 parts by weight of polymer resin, problems with driving performance may occur.

[0067] According to one embodiment of the present invention, the pigment (122) protrudes from the surface of the polymer resin layer (121). Specifically, FIG. 1 illustrates a configuration in which a portion of the pigment (122) protrudes from one surface of the polymer resin layer (121). Although FIG. 1 illustrates a configuration in which all of the pigments (122) of the coating layer (120) protrude from the polymer resin layer (121), one embodiment of the present invention is not limited thereto, and at least a portion of the pigments (122) may protrude from the surface of the polymer resin layer (121).

[0068] According to one embodiment of the present invention, the polymer resin layer (121) may have a thickness of 73 to 95% of the diameter of the pigment (122). Specifically, when the thickness of the polymer resin layer (121) is 73 to 95% of the diameter of the pigment (122), an increase in the initial yellowness (YI) of the optical film (100) is suppressed, the transmittance is secured, and the driving performance is improved.

[0069] On the other hand, if the thickness of the polymer resin layer (121) exceeds 95% of the diameter of the pigment (122), the process runnability may deteriorate and the transmittance of the optical film may decrease.

[0070] In addition, when the thickness of the polymer resin layer (121) is less than 73% of the diameter of the pigment (122), the process runnability and transmittance may be improved, but problems such as increased haze and decreased improvement in yellowness (YI) may occur.

[0071] According to one embodiment of the present invention, the coating layer (120) may further include an additive. The additive may include an additive that increases the surface energy of the coating layer, thereby improving adhesion during additional functional surface treatment or enhancing drivability. When the coating layer (120) includes an additive, the coefficient of friction index value can be implemented to be 0.1 or less, thereby improving drivability.

[0072] According to one embodiment of the present invention, the optical film (100) may have light-transmitting and flexible properties. For example, the optical film according to one embodiment of the present invention may have bending properties, folding properties, and rollable properties.

[0073] According to one embodiment of the present invention, the optical film (100) may further include a hard coating layer on top of the coating layer (120).

[0074] Although not shown in the drawing, an optical film (100) further including a hard coating layer may be laminated in the order of a light-transmitting substrate (110), a coating layer (120), and a hard coating layer.

[0075] The hard coating layer is a layer that protects the optical film (100) and the adherend to which the optical film (100) is attached from the external environment. According to one embodiment of the present invention, the hard coating layer may include at least one of a siloxane-based resin, an acrylic-based resin, a urethane-based resin, and an epoxy-based resin.

[0076] Referring to FIG. 2, a display device (200) according to another embodiment of the present invention includes a display panel (501) and an optical film (100) on the display panel (501).

[0077] 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, for example, an organic light-emitting display device.

[0078] The substrate (510) may be made of glass or plastic. Specifically, the substrate (510) may be made of plastic such as a polyimide-based resin or an optical film. Although not shown, a buffer layer may be disposed on the substrate (510).

[0079] 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).

[0080] 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).

[0081] A planarization film (552) is placed on a thin film transistor (TFT) to planarize the upper portion of the thin film transistor (TFT).

[0082] The first electrode (571) is placed on the planarization film (552). The first electrode (571) is connected to a thin film transistor (TFT) through a contact hole provided in the planarization film (552).

[0083] The bank layer (580) is disposed on a portion of 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 disposed in a matrix structure in a boundary area between a plurality of pixels, thereby defining a pixel area by the bank layer (580).

[0084] 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 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.

[0085] The second electrode (573) is placed on the organic light-emitting layer (572).

[0086] An organic light-emitting element (270) can be formed by stacking a first electrode (571), an organic light-emitting layer (572), and a second electrode (573).

[0087] 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.

[0088] 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.

[0089] An optical film (100) is placed on a display panel (501) having the laminated structure described above.

[0090] Hereinafter, the present invention will be described in more detail with reference to exemplary embodiments. However, the present invention is not limited to the manufacturing examples or embodiments described below.

[0091] Example 1

[0092] 2-(3,4-Epoxycylohexyl)ethytrimethoxysilane (TCI), TEOS (Tetraethyl orthosilicate, Sigma-Aldrich), and H2O were mixed in a ratio of 747.66 mL: 38.28 mL: 93.88 mL and placed in a 1500 mL flask. 0.1 g of sodium hydroxide was added as a catalyst and stirred at 60°C for 10 hours. Subsequently, the mixture was filtered using a 0.45 μm Teflon filter to obtain an epoxy siloxane resin. The mixture was stirred at 60°C for 10 hours. Subsequently, the mixture was filtered using a 0.45 μm Teflon filter to obtain an epoxy siloxane resin.

[0093] MEK (Methyl Ethyl Ketone) : MIBK (Methyl Isobutyl Ketone) was diluted in a ratio of 2:8 to the epoxy siloxane resin manufactured as described above, and 600 mL was added, and then 3 parts by weight of IRGACURE 250 (BASF) as a photoinitiator was added relative to 100 parts by weight of the epoxy siloxane resin manufactured as described above, 2.5 parts by weight of Tinuvin 477 (solid content 80 wt%, BASF) as a UV absorber relative to 100 parts by weight of the epoxy siloxane resin based on solid content, 2.5 parts by weight of Tinuvin 479 (solid content 100 wt%, Basf) as a UV absorber relative to 100 parts by weight of the epoxy siloxane resin based on solid content, and SWN VILOET 899W (solid content 25 wt%, Ilsam) as a pigment having an average particle size of about 150 nm was added. A coating composition was obtained by adding 10 parts by weight based on solid content to 100 parts by weight of the above epoxy siloxane resin, and adding 0.25 parts by weight of Glide 406 (solid content 50 wt%, TEGO) as an additive based on solid content to 100 parts by weight of the above epoxy siloxane resin.

[0094] The above coating composition was applied to the upper surface of a transparent polyimide substrate (A_50, Kolon Industries) using a No. 4 Mayer Bar and then dried at 100°C / 10 minutes.

[0095] Then, an optical film having a thickness of 50 μm with a polymer resin layer having a thickness of 130 nm was manufactured by exposing it to 1 J / cm2 with an ultraviolet lamp having a wavelength of 315 nm.

[0096] Example 2

[0097] It was manufactured by the same process as Example 1, except that the thickness of the polymer resin layer was 110 nm.

[0098] Example 3

[0099] It was manufactured by the same process as Example 1, except that the thickness of the polymer resin layer was 140 nm.

[0100] Comparative Example 1-6

[0101] According to the conditions of Table 1, an optical film (100) was manufactured in the same manner as Example 1, and each was referred to as Comparative Example 1-6.

[0102] Thickness of polymer coating layer (nm) Type of pigment Pigment diameter (nm) Content of pigment (parts by weight) Example 1 1 30 First pigment 15 0 10 Example 2 1 10 First pigment 15 0 10 Example 3 1 40 First pigment 15 0 10 Example 4 1 30 First pigment 15 0 6 Example 5 1 10 First pigment 15 0 14 Comparative Example 1 1 50 First pigment 15 0 10 Comparative Example 2 1 00 First pigment 15 0 10 Comparative Example 3 70 Second pigment 8 0 10 Comparative Example 4 1 80 Third pigment 20 0 10 Comparative Example 5 1 30 First pigment 15 0 5 Comparative Example 6 1 30 First pigment 15 0 15

[0103] The first, second, and third pigments according to Table 1 are as follows. First pigment: SWN VILOET 899W (Ilsam Co., Ltd.)

[0104] Second pigment: OP2708B-80N (SAT NANO)

[0105] Third pigment: OP2708B-200N (SAT NANO)

[0106] In Table 1, parts by weight represent relative weights per 100 parts by weight of polymer resin.

[0107] The following physical properties were measured for the optical films manufactured in Examples 1 to 3 and Comparative Examples 1 to 6.

[0108] (1) Measurement of transmittance (%)

[0109] Transmittance is the average value obtained by cutting the manufactured optical film into 50 mm x 50 mm pieces and measuring the transmittance 5 times using a haze meter (model name: HM-150) from MURAKAMI Co., Ltd. according to ASTM-D1003.

[0110] (2) Yellowness (YI) measurement

[0111] Yellowness (YI) is the average value obtained by cutting the manufactured optical film into 50 mm x 50 mm pieces and measuring it 5 times using a colorimeter (model name: CM-3600A) from KONICA MINOLTA with a D65 light source, a viewing angle of 2°, and transmission mode.

[0112] (3) Haze measurement

[0113] Haze is the average value obtained by cutting the manufactured optical film into 50 mm x 50 mm pieces and measuring the haze 5 times using a haze meter (model name: HM-150) from MURAKAMI according to ASTM-D1003.

[0114] (4) Measurement of static friction coefficient and kinetic friction coefficient

[0115] The static and kinetic coefficients of friction were measured using a friction coefficient measuring instrument (Ametek Lloyd instrument LF Plus) according to ASTM D1894.

[0116] Specifically, an optical film sample cut to 100 mm x 63.5 mm was cut to 63.5 mm2 A metal block (200 g) was attached to the bottom, and a 20 x 10 cm film was placed on the bottom. The metal block was pulled at a speed of 180 mm / min to move 130 mm, and then the metal block was stopped. The static friction coefficient and kinetic friction coefficient were measured from the data from the time the metal block was pulled to the time the metal block was stopped.

[0117] (5) Calculation of friction coefficient index

[0118] The coefficient of friction index is calculated using the static friction coefficient and kinetic friction coefficient measured above using Equation 1 below.

[0119] [Formula 1]

[0120] Friction coefficient index = static friction coefficient - kinetic friction coefficient

[0121] (6) Surface roughness (Ra)

[0122] Surface roughness (Ra) was measured using a 10x magnification lens using a non-contact 3D micro-shape measuring device, NV-2000 from Nanosystems, Inc., for an area of ​​1 mm x 1 mm.

[0123] The measurement results are shown in Table 2 below.

[0124] Transmittance (%) Haze (%) Yellowness (YI) Static friction coefficient Kinetic friction coefficient Friction coefficient index Surface roughness (Ra) (㎛) Example 1 89.7 0.9 0.7 0.45 0.37 0.08 40 nm Example 2 89.9 1.0 0.9 0.47 0.38 0.09 43 nm Example 3 89.5 0.8 0.6 0.42 0.35 0.07 33 nm Example 4 89.8 0.8 0.8 0.41 0.32 0.09 31 nm Example 5 89.6 1.0 0.6 0.49 0.42 0.07 50 nm Comparative example 189.10.6 0.50.560.450.1122nmComparison Example 290.01.31.10.410.370.0485nmComparison Example 390.20.81.10.550.430.1227nmComparison Example 488.81.30.50.460.380.0834nmComparison Example 589.80.71.50.480.390.0914nmComparison Example 688.51.10.20.370.300.0780nm

[0125] As disclosed in the measurement results in Table 2, it can be seen that the optical film (100) according to the embodiment of the present invention has transmittance, haze, yellowness, friction coefficient index, and surface roughness (Ra) all within the standards.

Claims

1. Light-transmitting substrate; and Containing a coating layer, The coefficient of friction index value is less than 0.1, The transmittance is 89.5% or more based on a thickness of 50 ㎛, The yellowness index (YI) is 1.0 or less at a thickness of 50 ㎛. The above friction coefficient index is expressed by the following equation 1, optical film: [Formula 1] Friction coefficient index = static friction coefficient - kinetic friction coefficient 2. In paragraph 1, An optical film having a surface roughness (Ra) of 30 to 80 nm.

3. In paragraph 1, The above coating layer is, A polymer resin layer comprising a polymer resin and an ultraviolet absorber; and Containing pigments; An optical film, wherein the polymer resin comprises at least one selected from an acrylic resin, a urethane resin, and a siloxane resin.

4. In paragraph 3, An optical film, wherein the pigment has a diameter of 100 to 200 nm.

5. In paragraph 3, An optical film, wherein the coating layer contains 6 to 14 parts by weight of a pigment relative to 100 parts by weight of the polymer resin.

6. In paragraph 3, An optical film, wherein the polymer resin layer has a thickness of 73 to 95% of the diameter of the pigment.

7. In paragraph 3, An optical film in which the pigment protrudes from the surface of the polymer resin layer.

8. In paragraph 1, An optical film having a static friction coefficient of 0.5 or less.

9. In paragraph 1, An optical film having a haze of 1.0% or less based on a thickness of 50 ㎛.

10. Display panel; and A display device comprising an optical film according to any one of claims 1 to 9, arranged on the display panel.

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