Optical film and display device containing the same

Abstract

The present invention relates to a light-transmitting substrate having a yellowness index of 5.0 or less before a lightfastness test and a color change (ΔE* ab The present invention provides an optical film and a display device including the same, in which the refractive index is 3.5 or less.

Description

[Technical Field]

[0001] The present invention relates to an optical film and a display device containing the same. [Background technology]

[0002] In recent years, with the trend towards thinner, lighter, and more flexible display devices, the use of optical films containing polymer resins as cover windows instead of glass has been explored. For optical films to be used as cover windows for display devices, they must possess excellent optical and mechanical properties.

[0003] On the other hand, optical films containing polymer resins have the problem of either being highly yellowed initially, or undergoing color changes over time due to exposure to light.

[0004] Therefore, there is a need to develop films that have excellent mechanical properties such as insolubility, chemical resistance, and heat resistance, as well as excellent optical properties such as light resistance. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Therefore, one embodiment of the present invention aims to provide an optical film with excellent light resistance.

[0006] Another embodiment of the present invention aims to provide a display device that includes an optical film with excellent light resistance. [Means for solving the problem]

[0007] One embodiment of the present invention includes a light-transmitting substrate, the yellowness before the lightfastness test is 5.0 or less, and the color change after the lightfastness test (ΔE* ab The present invention provides an optical film in which the coefficient of 3.5 or less is 3.5 or less.

[0008] The light resistance test is carried out for 300 hours under the conditions of a xenon lamp, a daylight filter, 12 kW, 0.8 W / m 2 @420 nm, a 30℃ / 30RH% chamber, and a 55℃ black panel, and the color change (ΔE* ab ) is calculated by the following formula 1.

[0009] [Formula 1] ΔE* ab =[(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 1 / 2

[0010] In the formula 1, ΔL* is the difference in L* before and after the light resistance test, Δa* is the difference in a* before and after the light resistance test, and Δb* is the difference in b* before and after the light resistance test.

[0011] The light-transmissive substrate may contain a polymer resin and a malonate-based ultraviolet absorber.

[0012] When the ultraviolet absorber is dissolved in DAMc (dimethylacetamide) at a concentration of 0.001 wt%, the maximum absorbance in the UVA region (315 - 400 nm) may be 0.45 or more.

[0013] The ultraviolet absorber may contain a compound represented by the following chemical formula 2.

[0014] [Chemical Formula 2] JPEG0007833548000001.jpg3968

[0015] In the chemical formula 2, R 1 , R 2 , R 3 and R 4 ​Each of these is independently hydrogen, a halogen element, a phenyl group, or a linear, branched, or alicyclic alkyl group of C1 to C10, Y is a divalent aromatic or heteroorganic group having 6 to 40 carbon atoms, and the hydrogen atoms in the organic group contained in chemical formula 2 may be substituted with (1) a halogen element, (2) a hydrocarbon group, (3) a halogen-substituted hydrocarbon group, or (4) a hydrocarbon group substituted with a halogen element, oxygen, or nitrogen.

[0016] The UV absorber may also contain tetraethyl 2,2'-(1,4-phenylenedimethylidyne)bismalonate.

[0017] The light-transmitting substrate may contain 1 to 10 parts by weight of the ultraviolet absorber per 100 parts by weight of the polymer resin.

[0018] The polymer resin may contain at least one imide repeating unit and an amide repeating unit.

[0019] The optical film may have a light transmittance of 88.5% or higher after the lightfastness test, and a haze of 1.0 or less after the lightfastness test.

[0020] Another embodiment of the present invention provides a display device comprising a display panel and an optical film disposed on the display panel. [Effects of the Invention]

[0021] According to one embodiment of the present invention, an optical film with excellent light resistance in the UVA region (315-400 nm) can be provided.

[0022] According to another embodiment of the present invention, a display device can be provided that includes an optical film with excellent light resistance in the UVA region (315-400 nm). [Brief explanation of the drawing]

[0023] [Figure 1] This is a cross-sectional view of an optical film (100) according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view of an optical film (101) further including a primer layer (120). [Figure 3] This is a cross-sectional view of an optical film (102) further including a hard coat layer (130). [Figure 4] This is a cross-sectional view showing a part of a display device (200) according to another embodiment of the present invention. [Figure 5] This is an enlarged cross-sectional view of the "P" portion in Figure 4. [Modes for carrying out the invention]

[0024] Embodiments of the present invention will be described in detail below. However, the embodiments described below are presented for illustrative purposes to aid in a clear understanding of the present invention and do not limit the scope of the invention.

[0025] The shapes, sizes, proportions, angles, numbers, etc., disclosed in the drawings illustrating embodiments of the present invention are illustrative, and the present invention is not limited to those shown in the drawings. Throughout the specification, identical components may be referred to by the same reference numerals. In describing the present invention, if a specific description of related prior art is deemed to unnecessarily obscure the gist of the invention, such detailed description will be omitted.

[0026] Wherever "includes," "possesses," "performs," ​​etc., as used herein, other parts may be added unless the expression "only" is used. Wherever a constituent element is expressed in the singular, it includes multiple elements unless otherwise explicitly stated. Furthermore, when interpreting a constituent element, it shall be interpreted to include a margin of error, even if not otherwise explicitly stated.

[0027] When describing spatial relationships, for example, when describing the positional relationship between two parts, such as "on top of," "above," "below," or "next to," one or more other parts may be located between the two parts unless the expressions "immediately" or "directly" are used.

[0028] Spatially relative terms such as "below," "below," "above," and "upper" can be used to easily describe the correlation between one element or component and another, as shown in the drawing. Spatially relative terms should be understood as terms that include different orientations of the element during use or operation, in addition to the orientation shown in the drawing. For example, if the elements shown in the drawing are turned over, an element described as "below" or "beneath" of another element may be positioned "above" of that element. Therefore, the exemplary term "below" can include both downward and upward directions. Similarly, the exemplary terms "up" or "upper" can include both upward and downward directions.

[0029] When describing temporal relationships, for example, when describing temporal sequence, such as "after," "following," "next," or "before," it can include non-continuous events unless the expressions "immediately" or "directly" are used.

[0030] While terms such as "first," "second," etc., are used to describe various constituent elements, these constituent elements are not limited by these terms. These terms are used simply to distinguish one constituent element from others. Therefore, the first constituent element referred to below may be the second constituent element within the scope of the technical idea of ​​the present invention.

[0031] The term "at least one" should be understood to include all possible combinations of one or more related items. For example, "at least one of the first, second, and third items" means all possible combinations of items that can be presented from two or more of the first, second, and third items, not just each of the first, second, or third items individually.

[0032] Each feature of the various embodiments of the present invention can be partially or entirely coupled or combined with one another, enabling various technical interlocks and drives, and each embodiment can be implemented independently of one another or together in a related manner.

[0033] Before describing the present invention in detail, it should be understood that the terms used herein are for the purpose of describing specific embodiments and are not limited solely to the appended claims. All technical and scientific terms used herein have the same meaning as commonly understood by those of the ordinary art unless otherwise noted.

[0034] Furthermore, in interpreting the terms and words used in this specification and the claims below, based on the principle that inventors can appropriately define the concepts of terms in order to best explain their invention, they should not necessarily be interpreted only in terms of their common or dictionary meanings, but rather in terms and concepts that are consistent with the technical idea of ​​the present invention, as described herein.

[0035] One embodiment of the present invention provides an optical film (100). Figure 1 is a cross-sectional view of the optical film (100) according to one embodiment of the present invention.

[0036] As shown in Figure 1, an optical film (100) according to one embodiment of the present invention includes a light-transmitting substrate (110).

[0037] An optical film (100) according to one embodiment of the present invention has a yellowness of 5.0 or less before the lightfastness test, and a color change (ΔE*) after the lightfastness test. ab ) is 3.5 or less.

[0038] The degree of yellowness before lightfastness testing can be measured using a spectrophotometer. Specifically, the degree of yellowness of an optical film can be measured using a spectrophotometer, such as a KONICA MINOLTA spectrophotometer (model name: CM-3700D), in accordance with the standard ASTM E313.

[0039] The aforementioned lightfastness test was conducted using a xenon lamp, such as an ATLAS SUNTEST XXL+ device, with a daylight filter, at 420 nm and 0.8 W / m². 2 12kW (12kW 0.8W / m 2 The experiment was conducted for 300 hours under the following conditions: @420nm, a chamber at 30°C and 30% relative humidity (30°C / 30RH% Chamber), and a black panel at 55°C. The aforementioned color change (ΔE* ab ) is calculated using the following formula 1.

[0040] [Formula 1] ΔE* ab =[(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 ] 1 / 2

[0041] In the above formula 1, ΔL* is the difference in L* before and after the lightfastness test, Δa* is the difference in a* before and after the lightfastness test, and Δb* is the difference in b* before and after the lightfastness test.

[0042] The L*, a*, and b* of the optical film (100) before the lightfastness test can be measured using a colorimeter. Specifically, the optical film (100) is measured three times each for L*, a*, and b* using a colorimeter, for example, a KONICA MINOLTA colorimeter (model name: CM-3600A), with a D65 light source, a viewing angle of 2°, and transmission mode. The average value of the three measured L*, a*, and b* values ​​is then calculated and used as the L*, a*, and b* values ​​of the optical film (100). The L*, a*, and b* values ​​after the lightfastness test can be measured using the same method as the measurement method for L*, a*, and b* before the lightfastness test, after the lightfastness test has been performed.

[0043] The degree of yellowing of the optical film (100) before the lightfastness test is 5.0 or less, and the color change after the lightfastness test (ΔE* ab If the ratio is 3.5 or less, the optical film (100) has excellent visibility and light resistance, especially UV light resistance, making it suitable for use as a cover window for a display device. The polymer resin contained in the light-transmitting substrate (110) of the optical film (100) has a large amount of aromatic rings, so when exposed to ultraviolet (UV) wavelength light for a long time, the optical film (100) will change color. Therefore, as time passes, the color reproducibility and clarity of the optical film (100) will decrease, and its visibility will decrease. On the other hand, an optical film (100) with excellent UV light resistance will change color less even when exposed to ultraviolet (UV) wavelength light, thus increasing the lifespan of the cover window for a display device.

[0044] In one embodiment of the present invention, the light-transmitting substrate (110) may contain a polymer resin and an ultraviolet absorber.

[0045] The polymer resin has excellent flexibility and impact resistance, making it suitable for use as a cover window for flexible display devices. The polymer resin may be included in the film in various forms and shapes, such as in the form of a solid powder, in a form dissolved in a solution, or in the form of a matrix that has solidified after being dissolved in a solution. Regardless of its shape or form, any resin containing the same repeating units as the present invention can be considered identical to the polymer resin of the present invention. Generally, the polymer resin within the film may exist in the form of a matrix that has been coated with a polymer resin solution, dried, and solidified.

[0046] The polymer resin according to one embodiment of the present invention may be any light-transmitting resin. For example, it may contain at least one selected from cycloolefin derivatives, cellulose polymers, ethylene vinyl acetate copolymers, polyester polymers, polystyrene polymers, polyamide polymers, polyamide-imide polymers, polyetherimide polymers, polyacrylic polymers, polyimide polymers, polyethersulfone polymers, polysulfone polymers, polyethylene polymers, polypropylene polymers, polymethylpentene 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 contain at least one of polyimide polymers, polyamide polymers, and polyamideimide polymers. In particular, polyimide polymers, polyamide polymers, and polyamide-imide polymers are excellent not only in physical properties such as thermal properties, hardness, abrasion resistance, and flexibility, but also in optical properties such as light transmittance and haze. It is preferable that the light-transmitting substrate (110) of the optical film (100) used as a cover window for a display device contains at least one of polyimide polymers, polyamide polymers, and polyamide-imide polymers. However, the present invention is not limited to these.

[0047] According to one embodiment of the present invention, the light-transmitting substrate (110) may include a polymer resin containing at least one imide repeating unit and an amide repeating unit. In the present invention, an imide repeating unit refers to a repeating unit produced by the reaction of a diamine compound and a dianehydride compound to form an imidized unit, and an amide repeating unit refers to a repeating unit produced by the reaction of a diamine compound and a dicarbonyl compound. The light-transmitting substrate (110) may be any one of a polyimide substrate, a polyamide substrate, and a polyamideimide substrate. However, one embodiment of the present invention is not limited thereto, and any substrate having light transmittance may be the light-transmitting substrate (110) according to one embodiment of the present invention.

[0048] According to one embodiment of the present invention, the light-transmitting substrate (110) may contain an ultraviolet absorber. The ultraviolet absorber may contain a malonate compound. That is, the light-transmitting substrate (110) according to one embodiment of the present invention may contain a malonate ultraviolet absorber.

[0049] The malonate compounds of the present invention are compounds containing a malonate substituent, and the malonate substituent has a structure represented by the following chemical formula 1. That is, a malonate compound refers to a compound containing a structure represented by the following chemical formula 1.

[0050] [Chemical formula 1] JPEG0007833548000002.jpg3335

[0051] In the above chemical formula 1, R 1 and R 2 Each of these is independently a hydrogen atom, a halogen element, a phenyl group, or a linear, branched, or alicyclic alkyl group of C1-C10.

[0052] Malonate compounds minimize the increase in the initial yellowness of the optical film (100), have excellent effects in improving the lightfastness of the optical film (100), and when included as an ultraviolet absorber, they can minimize the color change of the optical film (100) when exposed to light.

[0053] According to one embodiment of the present invention, when the ultraviolet absorber is dissolved in DAMC at a concentration of 0.001 wt%, the maximum absorbance in the UVA region (315-400 nm) may be 0.45 or higher.

[0054] The maximum absorbance of an ultraviolet absorber in the UVA region (315-400 nm) can be measured using an ultraviolet spectrophotometer. Specifically, the ultraviolet absorber is dissolved in DMAc (N,N-Dimethylacetamide) at a concentration of 0.001 wt%, and the absorbance in the UVA region (315-400 nm) is measured using an ultraviolet spectrophotometer, such as Shimadzu's UV-1800. The maximum value of the absorbance measured in the UVA region (315-400 nm) is the maximum absorbance of the ultraviolet absorber in the UVA region (315-400 nm).

[0055] When the maximum absorbance of the UV absorber in the UVA region (315-400 nm) is 0.45 or higher, the initial yellowing of the optical film (100) is minimized, and the lightfastness is improved so that the initial yellowing is 5.0 or lower, and the color change (ΔE*) after the lightfastness test is also minimized. ab ) can be made to be 3.5 or less.

[0056] According to one embodiment of the present invention, the ultraviolet absorber may contain at least two structures represented by the chemical formula 1. That is, the ultraviolet absorber may contain at least two malonate substituents.

[0057] If the UV absorber contains two or more malonate substituents, the absorbance of the UV absorber increases, and the maximum absorbance in the UVA region (315-400 nm) may be 0.45 or higher.

[0058] According to one embodiment of the present invention, the ultraviolet absorber may include a compound represented by the following chemical formula 2.

[0059] [Chemical formula 2] JPEG0007833548000003.jpg3968

[0060] In the above chemical formula 2, R 1 , R 2 , R 3 and R 4 Each of these is independently hydrogen, a halogen element, a phenyl group, or a linear, branched, or alicyclic alkyl group of C1 to C10, Y is a divalent aromatic organic group or heteroorganic group having 6 to 40 carbon atoms, and the hydrogen atoms in the organic group contained in chemical formula 2 may be substituted with (1) a halogen element, (2) a hydrocarbon group, (3) a halogen-substituted hydrocarbon group, or (4) a hydrocarbon group substituted with a halogen element, oxygen, or nitrogen.

[0061] In the aforementioned chemical formula 2, Y may include, for example, a structure represented by any one of the structural formulas shown in the following chemical formula 3.

[0062] [Chemical formula 3] JPEG0007833548000004.jpg109119

[0063] In the structural formula of chemical formula 3, * indicates a bond position. In the structural formula, Z may independently be one of the following: a single bond, O, S, SO2, CO, and (C=C)n, and n may be an integer from 1 to 5. The bond position of Z to each ring is not particularly limited, but the bond position of Z may be, for example, ortho or para relative to each ring. The hydrogen atoms in the structural formula of chemical formula 3 may be substituted with (1) a halogen element, (2) a hydrocarbon group, (3) a halogen-substituted hydrocarbon group, or (4) a halogen element, oxygen, or nitrogen-substituted hydrocarbon group. In chemical formula 3, each structural formula may be a heterocyclic organic group in which one or more carbon atoms in the structural formula are substituted with elements such as nitrogen (N), sulfur (S), or oxygen (O).

[0064] According to one embodiment of the present invention, the ultraviolet absorber may include tetraethyl 2,2'-(1,4-phenylenedimethylidyne)bismalonate.

[0065] According to one embodiment of the present invention, the light-transmitting substrate may contain 1 to 10 parts by weight of an ultraviolet absorber per 100 parts by weight of a polymer resin.

[0066] When less than 1 part by weight of UV absorber is included per 100 parts by weight of polymer resin, the effect of improving lightfastness is negligible, and therefore the color change (ΔE*) after the lightfastness test is minimal. ab This would result in a value exceeding 3.5. Conversely, if the UV absorber is present in an amount exceeding 10 parts by weight per 100 parts by weight of polymer resin, the initial yellowness before the lightfastness test will exceed 5.0, and there is a possibility of leaching problems occurring during long-term storage.

[0067] According to one embodiment of the present invention, the optical film (101) may further include a primer layer (120) above the light-transmitting substrate (110). Figure 2 is a cross-sectional view of the optical film (101) further including the primer layer (120).

[0068] As shown in Figure 2, the optical film (101) further including a primer layer (120) may be laminated in the order of light-transmitting substrate (110) and primer layer (120).

[0069] The primer layer (120) of the present invention may contain a curable resin. According to one embodiment of the present invention, the curable resin may contain at least one selected from acrylic resins, urethane resins, and siloxane resins.

[0070] According to one embodiment of the present invention, the primer layer (120) of the present invention may further contain at least one of an ultraviolet absorber and a pigment.

[0071] According to one embodiment of the present invention, the primer layer (120) may contain the same malonate-based UV absorber as the light-transmitting substrate (110), or it may contain other UV absorbers in addition to the malonate-based UV absorber. The present invention is not limited thereto.

[0072] According to one embodiment of the present invention, the pigment may include a copper phthalocyanine compound. However, the present invention is not limited thereto, and other pigments other than copper phthalocyanine compounds may be used.

[0073] According to one embodiment of the present invention, the primer layer (120) may have a thickness of 0.1 to 10 μm. Preferably, the primer layer (120) may have a thickness of 1 to 5 μm. However, the present invention is not limited thereto.

[0074] According to one embodiment of the present invention, the optical film (102) may further include a hard coat layer (130) above the light-transmitting substrate (110). Figure 3 is a cross-sectional view of the optical film (102) further including the hard coat layer (130).

[0075] As shown in Figure 3, the optical film (102) further including a hard coat layer (130) may be laminated in the order of light-transmitting substrate (110) and hard coat layer (130).

[0076] The hard coat layer (130) is a layer that protects the adherend to which the optical film (102) and optical film (101) are attached from the external environment. According to one embodiment of the present invention, the hard coat layer (130) may include at least one of a siloxane resin, an acrylic resin, a urethane resin, and an epoxy resin.

[0077] According to one embodiment of the present invention, the hard coat layer (130) may have a thickness of 1 to 10 μm, preferably 1 to 5 μm. However, the present invention is not limited thereto.

[0078] According to one embodiment of the present invention, the optical film may include both a primer layer (120) and a hard coat layer (130) added above the light-transmitting substrate (110) (not shown). The optical film further including the primer layer (120) and the hard coat layer (130) may be laminated in the order of light-transmitting substrate (110), primer layer (120), and hard coat layer (130).

[0079] According to one embodiment of the present invention, the optical film (100) may have light transmittance and flexibility properties. For example, the optical film according to one embodiment of the present invention may have bending properties, folding properties and rollable properties.

[0080] According to one embodiment of the present invention, the optical film (100) may have a light transmittance of 88.5% or more before the lightfastness test, and a haze of 0.4 or less before the lightfastness test.

[0081] Prior to the lightfastness test, the light transmittance can be measured using a spectrophotometer in accordance with the standard ASTM E313. For example, a spectrophotometer from KONICA MINOLTA (model name: CM-3700D) can be used to measure the average light transmittance in the wavelength range of 360 to 740 nm.

[0082] Before the lightfastness test, the haze can be measured three times using a haze meter, for example, a MURAKAMI haze meter (model name: HM-150), by cutting the manufactured optical film (100) into 50mm x 50mm pieces and measuring it according to the ASTM D1003 standard. The average of the three measurements is taken as the haze value.

[0083] According to one embodiment of the present invention, the optical film (100) may have a light transmittance of 88.5% or more after the lightfastness test, and a haze of 1.0 or less after the lightfastness test.

[0084] The light transmittance and haze after the lightfastness test can be measured using the same method as the light transmittance and haze measurement method used before the lightfastness test.

[0085] An optical film (100) according to one embodiment of the present invention can be applied to a display device and protect the display surface of a display panel. The optical film (100) according to one embodiment of the present invention may have a thickness sufficient to protect the display panel. For example, the optical film (100) may have a thickness of 20 to 120 μm. However, the present invention is not limited thereto.

[0086] Hereinafter, a display device using an optical film (100) according to one embodiment of the present invention will be described with reference to Figures 4 and 5.

[0087] Figure 4 is a partial cross-sectional view of a display device (200) according to another embodiment of the present invention, and Figure 5 is an enlarged cross-sectional view of the "P" portion of Figure 4.

[0088] Referring to Figure 4, 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). The optical film (100) in Figure 4 may be the optical film (101) in Figure 2 or the optical film (102) in Figure 3.

[0089] Referring to Figures 4 and 5, the display panel (501) includes a substrate (510), thin-film transistors (TFTs) on the substrate (510), and an organic light-emitting element (570) connected to the thin-film transistors (TFTs). 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 Figures 4 and 5 is an organic light-emitting display device.

[0090] The substrate (510) may be made of glass or plastic. Specifically, the substrate (510) may be made of a plastic such as a polyimide resin. Although not shown in the figures, a buffer layer may be placed on the substrate (510).

[0091] The thin-film transistor (TFT) is placed on a substrate (510). The thin-film transistor (TFT) includes a semiconductor layer (520), a gate electrode (530) insulated from the semiconductor layer (520) and overlapping with at least a portion of the semiconductor layer (520), a source electrode (541) connected to the semiconductor layer (520), and a drain electrode (542) spaced apart from the source electrode (541) and connected to the semiconductor layer (520).

[0092] Referring to Figure 5, a gate insulating film (535) is placed between the gate electrode (530) and the semiconductor layer (520). An interlayer insulating film (551) may be placed on the gate electrode (530), and a source electrode (541) and a drain electrode (542) may be placed on the interlayer insulating film (551).

[0093] The planarization film (552) is placed on a thin-film transistor (TFT) and planarizes the top surface of the thin-film transistor (TFT).

[0094] The first electrode (571) is placed on the planarization film (552). The first electrode (571) is connected to a thin-film transistor (TFT) via a contact hole provided in the planarization film (552).

[0095] The bank layer (580) is positioned on a portion of the first electrode (571) and the planarization film (552) to define a pixel region or light-emitting region. For example, the bank layer (580) can define a pixel region by arranging it in a matrix structure in the boundary region between multiple pixels.

[0096] The organic light-emitting layer (572) is placed on the first electrode (571). The organic light-emitting layer (572) may also be placed on the bank layer (580). The organic light-emitting layer (572) may include one light-emitting layer, or it may include two or more light-emitting layers stacked vertically. Light having one of the colors red, green, and blue may be emitted from such an organic light-emitting layer (572), and white light may also be emitted.

[0097] The second electrode (573) is placed on the organic light-emitting layer (572).

[0098] A first electrode (571), an organic light-emitting layer (572), and a second electrode (573) may be stacked to form an organic light-emitting element (570).

[0099] Although not shown, if the organic light-emitting layer (572) emits white light, each pixel may include a color filter to filter the white light emitted from the organic light-emitting layer (572) according to wavelength. The color filter is formed on the light path.

[0100] A thin film sealing layer (590) may be placed on the second electrode (573). The thin film sealing layer (590) may include at least one organic film and at least one inorganic film, and the at least one organic film and at least one inorganic film may be arranged alternately.

[0101] An optical film (100) is placed on the display panel (501) having the layered structure described above.

[0102] The present invention will be described more specifically below with reference to exemplary embodiments and comparative examples. However, the present invention is not limited by the embodiments and comparative examples described below.

[0103] <Production example: Polymer resin production> A 1 L reactor equipped with a stirrer, nitrogen injection device, dropping funnel, temperature controller, and condenser was filled with 776.655 g of DMAc (N,N-Dimethylacetamide) while passing nitrogen through it. After adjusting the reactor temperature to 25°C, 54.439 g (0.17 mol) of TFDB (Bis(trifluoromethyl)benzidine) was dissolved in it, and the solution was maintained at 25°C. 15.005 g (0.051 mol) of BPDA (biphenyl-tetracarboxylic acid dianhydride) was added and stirred for 3 hours to completely dissolve the BPDA. Then, 22.657 g (0.051 mol) of 6FDA (4,4'-(Hexafluoroisopropylidene)diphthalic anhydride) was added and completely dissolved. After lowering the reactor temperature to 10°C, 13.805 g (0.068 mol) of TPC (Terephthaloyl chloride) was added and the mixture was reacted at 25°C for 12 hours to obtain a polymer solution with a solid content of 12% by weight.

[0104] To the obtained polymer solution, 17.75 g of pyridine and 22.92 g of anhydrous acetic acid were added and stirred for 30 minutes. Then, the mixture was stirred again at 70°C for 1 hour and cooled to room temperature. 20 L of methanol was added to the obtained polymer solution to precipitate the solids, and the precipitated solids were filtered and pulverized. After that, the mixture was washed again with 2 L of methanol and dried under vacuum at 100°C for 6 hours to obtain a powdered polyimide-based polymer solid. The polyimide-based polymer solid produced here is a polyamide-imide polymer solid.

[0105] <Example 1> In a 500 mL reactor, 300 parts by weight of DMAc and 2 parts by weight of tetraethyl 2,2'-(1,4-phenylenedimethylidyne)bismalonate (UV absorber, Cas No.: 6337-43-5, Eversorb 320, Chempia) per 100 parts by weight of polyamide-imide polymer solids were added. After dissolving completely at room temperature for 10 minutes, the reactor was stirred while maintaining the temperature at 5°C. Subsequently, 43.72 parts by weight of the polyimide polymer solids powder prepared in the production example was added, and after stirring for 1 hour, the temperature was raised to 25°C to produce a liquid polyimide resin solution. The maximum absorbance of tetraethyl 2,2'-(1,4-phenylenedimethylidyne)bismalonate was 0.95 (@321 nm).

[0106] The obtained polyimide resin solution was applied to a casting substrate and cast, and the film was dried with hot air at 130°C for 30 minutes to produce a film. After that, the produced film was peeled off the casting substrate and fixed to the frame with pins. There are no particular restrictions on the type of casting substrate. Glass substrates, stainless steel (SUS) substrates, Teflon® substrates, etc., may be used as casting substrates. In Example 1, an organic substrate was used as the casting substrate. The same applies hereafter.

[0107] The frame on which the film was fixed was placed in a vacuum oven and slowly heated from 100°C to 280°C for 2 hours. After that, it was gradually cooled and separated from the frame to obtain a polyimide optical film. The polyimide optical film was then heat-treated again at 250°C for 5 minutes. As a result, a polyimide optical film with a thickness of 50 μm was completed.

[0108] <Example 2> An optical film of Example 2 was manufactured using the same method as in Example 1, but with a different content of the ultraviolet absorber.

[0109] The specific UV absorber content in Example 2 is shown in Table 1 below.

[0110] <Comparative Examples 1-4> Optical films of Comparative Examples 1 to 4 were manufactured using the same method as in Example 1, but with variations in the type and content of the ultraviolet absorber.

[0111] The specific types and contents of UV absorbers in Comparative Examples 1 to 4 are shown in Table 1 below.

[0112] In this study, the maximum absorbance of each UV absorber in the UVA region (315-400 nm) was determined by dissolving each UV absorber in DMAc at a concentration of 0.001 wt%, then measuring the absorbance in the UVA region (315-400 nm) using a Shimadzu UV spectrophotometer (UV-1800). The maximum value among the absorbances measured in the UVA region (315-400 nm) was defined as the maximum absorbance of the UV absorber in the UVA region (315-400 nm).

[0113] [Table 1]

[0114] <Measurement Examples> The following measurements were performed on the optical films manufactured in Examples 1-2 and Comparative Examples 1-4. The following measurement examples were taken before the lightfastness test and again after the lightfastness test.

[0115] Lightfastness testing was conducted using a xenon lamp, specifically an ATLAS SUNTEST XXL+ device, with a daylight filter and a 12kW 0.8W / m² output. 2 The experiment was conducted for 300 hours under the conditions of @420nm, 30℃ / 30RH% Chamber, and 55℃ Black Panel.

[0116] 1) Yellowness (YI) The degree of yellowness was measured using a spectrophotometer. Specifically, the degree of yellowness of the optical film was measured using a spectrophotometer in accordance with the standard ASTM E313, for example, a spectrophotometer (model name: CM-3700D) manufactured by Konica Minolta.

[0117] 2) L*, a*, b* and color change (ΔE* ab ) Color change (ΔE*) of optical films produced by the examples and comparative examples. ab ) was calculated using formula 1 below.

[0118] [Formula 1] ΔE* ab =[(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 ] 1 / 2

[0119] In the above formula 1, ΔL* is the difference in L* before and after the lightfastness test, Δa* is the difference in a* before and after the lightfastness test, and Δb* is the difference in b* before and after the lightfastness test.

[0120] The L*, a*, and b* values ​​of the optical film (100) before the lightfastness test were measured using a colorimeter. Specifically, for the optical film (100), a colorimeter was used, for example, a KONICA MINOLTA colorimeter (model name: CM-3600A), and L*, a*, and b* were measured three times each using a D65 light source, a viewing angle of 2°, and transmission mode. The average values ​​of the three measured L*, a*, and b* values ​​were then calculated and used as the L*, a*, and b* values ​​of the optical film (100). The L*, a*, and b* values ​​after the lightfastness test were measured using the same method as the measurement method for L*, a*, and b* before the lightfastness test.

[0121] 3) Light transmittance The optical films produced according to the examples and comparative examples were measured for average light transmittance in the wavelength range of 360 to 740 nm using a spectrophotometer, such as a KONICA MINOLTA spectrophotometer (model name: CM-3700D), in accordance with the standard ASTM E313.

[0122] 4) Hayes The optical films produced according to the examples and comparative examples were cut into 50mm x 50mm pieces and measured five times using a haze meter in accordance with the standard ASTM D1003, for example, using a haze meter (model name: HM-150) from MURAKAMI Corporation. The average of the five measurements was taken as the haze value of the optical film.

[0123] The measurement results are shown in Tables 2 and 3 below.

[0124] [Table 2]

[0125] [Table 3]

[0126] As disclosed in the measurement results in Tables 2 and 3 above, the optical films of Examples 1 and 2 of the present invention all had a degree of yellowing of 5.0 or less before the lightfastness test, a degree of yellowing of 7.8 or less after the lightfastness test, a light transmittance of 88.5% or more, a haze of 1.0 or less, and ΔE* ab The value was 3.5 or less. However, looking at the optical films of Comparative Examples 1 to 4, Comparative Examples 1 to 3 had a ΔE* after the lightfastness test. ab The value exceeded 3.5, confirming a decrease in the color reproduction and clarity of the optical film, and a reduction in visibility. In Comparative Example 4, the initial yellowing degree before the lightfastness test exceeded 5.0, and the haze after the lightfastness test exceeded 1.0, ΔE* ab The value exceeded 3.5, indicating a high degree of initial yellowing of the optical film. It was confirmed that the color reproduction and clarity of the optical film after the lightfastness test decreased, resulting in reduced visibility.

[0127] The features, structures, and effects exemplified in each of the embodiments described above can be combined or modified and implemented in other embodiments by a person with ordinary skill in the art to which the embodiments belong. Therefore, such combinations and modifications should be interpreted as being within the scope of the present invention. [Explanation of Symbols]

[0128] 100 Optical Film 101 Optical Film 102 Optical Film 110 Light-transmitting substrate 120 Primer layer 130 Hard court layer 200 Display device 501 Display Panel 510 circuit board 520 Semiconductor Layers 530 gate 535 Gate Insulator 541 Source electrode 542 Drain electrode 551 Interlayer insulating film 552 Planarization film 570 Organic light-emitting element 571 First electrode 572 Organic light-emitting layer 573 Second electrode 580 bank layers 590 Thin film sealing layer

Claims

1. Includes a light-transmitting substrate, The yellowness level before the lightfastness test was 5.0 or less. Color change after lightfastness test (ΔE* ab ) is 3.5 or less, The aforementioned light-transmitting substrate is polymer resins and Contains malonate-based UV absorbers. The light-transmitting substrate contains 1 to 10 parts by weight of the ultraviolet absorber per 100 parts by weight of the polymer resin. The aforementioned UV absorber includes tetraethyl 2,2'-(1,4-phenylenedimethylidyne)bismalonate. Optical film: The aforementioned lightfastness test was conducted using a xenon lamp with a daylight filter at 420 nm and a reading of 0.8 W / m². 2 12kW (12kW 0.8W / m 2 The experiment is conducted for 300 hours under the following conditions: @420nm, 30°C, 30% relative humidity chamber (30°C / 30RH% Chamber), and 55°C black panel (Black Panel). The aforementioned color change (ΔE* ab ) is calculated using the following formula 1. [Formula 1] ΔE* ab =[(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 ] 1 / 2 In the above formula 1, ΔL* is the difference in L* before and after the lightfastness test, Δa* is the difference in a* before and after the lightfastness test, and Δb* is the difference in b* before and after the lightfastness test.

2. The aforementioned ultraviolet absorber, when dissolved in dimethylacetamide (DAMc) at a concentration of 0.001 wt%, exhibits a maximum absorbance of 0.45 or higher in the UVA region (315-400 nm). The optical film according to claim 1.

3. The aforementioned ultraviolet absorber contains a compound represented by the following chemical formula 2: The optical film according to claim 1: [Chemical formula 2] In the above chemical formula 2, R 1 , R 2 , R 3 and R 4 Each of these is independently hydrogen, a halogen element, a phenyl group, or a linear, branched, or alicyclic alkyl group of C1 to C10, Y is a divalent aromatic or heteroorganic group having 6 to 40 carbon atoms, and the hydrogen atoms in the organic group contained in chemical formula 2 may be substituted with (1) a halogen element, (2) a hydrocarbon group, (3) a halogen-substituted hydrocarbon group, or (4) a hydrocarbon group substituted with a halogen element, oxygen, or nitrogen.

4. The polymer resin comprises at least one imide repeating unit and an amide repeating unit. The optical film according to claim 1.

5. The light transmittance after the lightfastness test is 88.5% or higher. The haze after the lightfastness test is 1.0 or less. The optical film according to claim 1.

6. Display panel and The optical film, which is disposed on the display panel, includes the optical film according to any one of claims 1 to 5. Display device.

Images